WO2024003662A1 - Secondary battery and method for producing positive electrode active material - Google Patents

Secondary battery and method for producing positive electrode active material Download PDF

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Publication number
WO2024003662A1
WO2024003662A1 PCT/IB2023/056234 IB2023056234W WO2024003662A1 WO 2024003662 A1 WO2024003662 A1 WO 2024003662A1 IB 2023056234 W IB2023056234 W IB 2023056234W WO 2024003662 A1 WO2024003662 A1 WO 2024003662A1
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Prior art keywords
positive electrode
active material
secondary battery
electrode active
nickel
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PCT/IB2023/056234
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French (fr)
Japanese (ja)
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山崎舜平
池田隆之
横溝和音
小國哲平
栗城和貴
吉谷友輔
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株式会社半導体エネルギー研究所
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Publication of WO2024003662A1 publication Critical patent/WO2024003662A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • One embodiment of the present invention relates to a product, a method, or a manufacturing method. Alternatively, the invention relates to a process, machine, manufacture, or composition of matter.
  • One embodiment of the present invention relates to a power storage device including a secondary battery, a semiconductor device, a display device, a light emitting device, a lighting device, an electronic device, or a manufacturing method thereof.
  • electronic equipment refers to all devices that have a power storage device, and an electro-optical device that has a power storage device, an information terminal device that has a power storage device, etc. are all electronic devices.
  • lithium ion secondary batteries lithium ion capacitors
  • air batteries air batteries
  • all-solid-state batteries lithium ion secondary batteries
  • demand for high-output, high-capacity lithium-ion secondary batteries is rapidly expanding along with the development of the semiconductor industry, and they have become indispensable in today's information society as a source of rechargeable energy. .
  • Non-Patent Documents 1 to 3 fluorides such as fluorite (calcium fluoride) have been used as fluxing agents in iron manufacturing and the like for a long time, and their physical properties have been studied (Non-Patent Documents 1 to 3).
  • Non-Patent Document 2 has a description regarding the physical properties of nickel fluoride
  • Non-Patent Document 3 has a description regarding the physical properties of aluminum fluoride.
  • Non-Patent Document 4 It is also known that lithium ion secondary batteries go through several states and reach thermal runaway when the temperature rises.
  • An object of one embodiment of the present invention is to provide a positive electrode active material that does not easily deteriorate and a method for manufacturing the same. Another object of the present invention is to provide a novel positive electrode active material and a method for producing the same. Another object of the present invention is to provide a highly safe or reliable secondary battery and a method for producing the same. Another object of the present invention is to provide a secondary battery that does not easily deteriorate and a method for manufacturing the same. Another object of the present invention is to provide a long-life secondary battery and a method for manufacturing the same. Another object of the present invention is to provide a novel secondary battery and a method for manufacturing the same.
  • NCM in which a large amount of nickel is used has a problem in that oxygen is easily desorbed, especially at high temperatures, and deterioration is likely to occur.
  • transition metals M typified by nickel and manganese, enter lithium sites where lithium ions are inserted or desorbed during charging and discharging.
  • a plurality of primary particles may aggregate to form secondary particles.
  • the a-axis length and/or c-axis length of the crystals of the primary particles of NCM changes, and the volume expands or contracts.
  • the air gap becomes larger. This causes cracks or refinement of the secondary particles.
  • the voids between the primary particles herein do not necessarily mean spaces.
  • the electrolyte may be present in the gap. In the case of an all-solid-state battery, it is a space.
  • an additive element such as one or more selected from fluorine, aluminum, magnesium, titanium, and calcium is added to NCM.
  • magnesium can be added to zero relative to the transition metal M (sum of nickel, cobalt, and manganese) in the composite oxide so that the desired amount is contained by the practitioner. It is desirable to add it by weighing in the range of .5 atomic % or more and 3 atomic % or less.
  • a secondary particle is an aggregate of multiple primary particles, and there may be gaps between the primary particles within the secondary particle.
  • primary particles include polycrystals or single crystals.
  • a nickel compound also called a precursor
  • a mixture of the nickel compound and a lithium compound is mixed.
  • an additional element source is mixed and heated at a second temperature higher than the first temperature to produce a positive electrode active material.
  • an aqueous solution containing a water-soluble salt of nickel, cobalt, and manganese, and an alkaline solution are supplied to the reaction tank, and mixed inside the reaction tank. to precipitate a compound containing at least nickel, cobalt, and manganese, heat the first mixture of the compound and the lithium compound at a first heating temperature, crush or crush it, and then further heat it for a second time.
  • This is a method for producing a positive electrode active material, in which a second mixture obtained by heating a crushed or pulverized first mixture and an additive element source is heated at a third heating temperature.
  • Another configuration disclosed in this specification is to obtain a nickel compound (also referred to as a precursor) containing nickel, cobalt, and manganese using a coprecipitation method, and then add the nickel compound, lithium compound, and additional element source;
  • a positive electrode active material is produced by heating the mixture at a first temperature and pulverizing or crushing the mixture.
  • an aqueous solution containing a water-soluble salt of nickel, cobalt, and manganese, and an alkaline solution are supplied to the reaction tank, and mixed inside the reaction tank. to precipitate a compound containing at least nickel, cobalt, and manganese, and heat the first mixture of the compound, lithium compound, and additive element source at a first heating temperature to crush or crush the compound, and then further Preparation of a positive electrode active material by heating a second mixture obtained by heating at a second heating temperature and mixing a crushed or pulverized first mixture and an additive element source at a third heating temperature. It's a method.
  • heating is performed at a second temperature higher than the first temperature, and the mixing state of the mixture is improved by performing the heat treatment twice in total. Therefore, when a secondary battery is produced, voids in the secondary particles can be reduced. Further, by performing the heat treatment a total of two times, the crystallinity of the positive electrode active material can be improved.
  • the range of the first heating temperature is from 400°C to 750°C.
  • the range of the second heating temperature and the third heating temperature is higher than 750°C and lower than 1050°C.
  • an aqueous solution containing a water-soluble salt of nickel, a water-soluble cobalt salt, and a water-soluble manganese salt and an alkaline solution are supplied to a reaction tank and mixed inside the reaction tank. to precipitate a nickel compound (hydroxide containing cobalt, manganese, and nickel).
  • the reaction may be referred to as a neutralization reaction, an acid-base reaction, or a coprecipitation reaction, and the compound containing at least nickel, cobalt, and manganese is a nickel-cobalt-manganese compound containing at most cobalt, or a nickel-cobalt-manganese compound of NCM.
  • a precursor When referred to as a precursor. Thereafter, a mixture of the nickel compound and the lithium compound is obtained.
  • aqueous solution containing the water-soluble salt of nickel a nickel sulfate aqueous solution or a nickel nitrate aqueous solution can be used.
  • an aqueous cobalt sulfate solution or an aqueous cobalt nitrate solution can be used.
  • an aqueous manganese sulfate solution or an aqueous manganese nitrate solution can be used.
  • the pH of the mixed solution inside the reaction tank is preferably 9.0 or more and 12.0 or less, more preferably 10.0 or more and 11.5 or less.
  • a chelate aqueous solution it makes it easier to control the pH of the mixed liquid present inside the reaction tank when obtaining the cobalt compound. Further, it is preferable to use a chelate aqueous solution because it can suppress unnecessary generation of crystal nuclei and promote growth. When the generation of unnecessary nuclei is suppressed, the generation of fine particles is suppressed, so that a composite oxide with a good particle size distribution can be obtained. In addition, by using an aqueous chelate solution, the acid-base reaction can be delayed, and the reaction proceeds gradually, making it possible to obtain nearly spherical secondary particles.
  • Glycine has the effect of keeping the pH constant at a pH of 9.0 to 10.0 and around it, and by using a glycine aqueous solution as the chelate aqueous solution, the pH of the reaction tank when obtaining the above cobalt compound can be adjusted. is preferable because it becomes easier to control.
  • the glycine concentration of the glycine aqueous solution is preferably 0.05 mol/L or more and 0.09 mol/L or less in the aqueous solution.
  • the positive electrode active material obtained by the above method has secondary particles, and the secondary particles have a plurality of primary particles.
  • the positive electrode active material obtained by the above method has a crystal with a hexagonal layered structure, and the crystal is not limited to a single crystal (also called a crystallite), but in the case of a polycrystal, several crystallites are gathered together.
  • Form primary particles refers to a particle that is recognized as a single particle during SEM observation.
  • secondary particles refer to aggregates of primary particles.
  • the bonding force acting between a plurality of primary particles does not matter. It may be a covalent bond, an ionic bond, a hydrophobic interaction, a van der Waals force, or any other intermolecular interaction, or a plurality of bonding forces may be at work.
  • secondary particles may be formed.
  • the positive electrode active material has secondary particles, the secondary particles have a plurality of primary particles, and at least one of the plurality of primary particles has a layer containing a large amount of additive elements on the surface layer.
  • the thickness of the layer containing a large amount of additive elements is 1 nm or more and 10 nm or less.
  • a secondary battery using the above positive electrode active material is also one of the configurations disclosed in this specification.
  • a secondary battery has a positive electrode having a positive electrode active material and a negative electrode having a negative electrode active material. Furthermore, a separator is provided between the positive electrode and the negative electrode. The separator is used to prevent short circuits, and can provide a highly safe or reliable secondary battery.
  • Another configuration disclosed in this specification supplies an aqueous solution containing a water-soluble salt of a water-soluble salt of nickel, a water-soluble salt of cobalt, and a water-soluble salt of manganese to the reaction tank, and an alkaline solution,
  • a composite hydroxide containing at least nickel, cobalt, and manganese is precipitated by mixing inside a reaction tank, and a first heating is applied to the mixture of the composite hydroxide, the lithium compound, and the additive element source.
  • This is a method for producing a positive electrode active material, in which, after crushing or crushing, a second heating is further performed to crush or crush.
  • the additive element source is preferably one or more selected from a fluorine source, an aluminum source, a magnesium source, a titanium source, and a calcium source.
  • a cathode active material that does not easily deteriorate and a method for producing the same can be provided.
  • a novel positive electrode active material and a method for producing the same can be provided.
  • a highly safe or reliable secondary battery and a method for manufacturing the same can be provided.
  • a long-life secondary battery can be provided.
  • a novel secondary battery and a method for producing the same can be provided.
  • FIG. 1A and FIG. 1B are calculation model diagrams comparing the energy difference between Li 2 O generation and LiF generation in the positive electrode active material.
  • 2A to 2E are calculation model diagrams in which the surface of a composite oxide is coated with AlF 3 and LiF.
  • FIG. 3A is a schematic diagram showing the appearance of secondary particles
  • FIG. 3B is a schematic diagram showing an example of a cross section of the secondary particles.
  • FIG. 4A is a diagram showing an example of a cross section of a secondary particle
  • FIG. 4B is a schematic diagram showing an example of a cross section of a secondary particle.
  • FIGS. 5A and 5B are diagrams showing an example of a cross section of a single particle.
  • FIG. 6A and 6B are an example of a flow diagram of a manufacturing process illustrating one embodiment of the present invention.
  • FIG. 7 is an example of a flow diagram of a manufacturing process illustrating one embodiment of the present invention.
  • FIG. 8 is a phase diagram showing the relationship between the composition and temperature of lithium fluoride and magnesium fluoride.
  • FIG. 9 is a phase diagram showing the relationship between the composition and temperature of lithium fluoride and nickel fluoride.
  • FIG. 10 is a phase diagram showing the relationship between the composition and temperature of lithium fluoride and aluminum fluoride.
  • FIG. 11A is an exploded perspective view of a coin-type secondary battery
  • FIG. 11B is a perspective view of the coin-type secondary battery
  • FIG. 11C is a cross-sectional perspective view thereof.
  • FIG. 11A is an exploded perspective view of a coin-type secondary battery
  • FIG. 11B is a perspective view of the coin-type secondary battery
  • FIG. 11C is a cross-sectional perspective view thereof.
  • FIG. 12A shows an example of a cylindrical secondary battery.
  • FIG. 12B shows an example of a cylindrical secondary battery.
  • FIG. 12C shows an example of a plurality of cylindrical secondary batteries.
  • FIG. 12D shows an example of a power storage system having a plurality of cylindrical secondary batteries.
  • 13A and 13B are diagrams illustrating an example of a secondary battery, and
  • FIG. 13C is a diagram illustrating the inside of the secondary battery.
  • 14A to 14C are diagrams illustrating examples of secondary batteries.
  • 15A and 15B are diagrams showing the appearance of a secondary battery.
  • 16A to 16C are diagrams illustrating a method for manufacturing a secondary battery.
  • FIG. 17A is a perspective view of a battery pack showing one embodiment of the present invention, FIG.
  • FIG. 17B is a block diagram of the battery pack
  • FIG. 17C is a block diagram of a vehicle having the battery pack
  • 18A to 18D are diagrams illustrating an example of a transportation vehicle.
  • FIG. 18E is a diagram illustrating an example of an artificial satellite.
  • FIG. 19A is a diagram showing an electric bicycle
  • FIG. 19B is a diagram showing a secondary battery of the electric bicycle
  • FIG. 19C is a diagram explaining a scooter.
  • 20A to 20D are diagrams illustrating an example of an electronic device.
  • FIG. 21 is a graph showing the temperature rise of the secondary battery.
  • FIGS. 22A to 22C are diagrams illustrating a nail penetration test.
  • FIG. 23 is a graph showing the temperature rise of the secondary battery when an internal short circuit occurs.
  • FIGS. 24A and 24B are photographs showing the nail penetration test.
  • FIG. 25A is a graph showing changes in battery voltage during the nail penetration test
  • FIG. 25B is a graph showing changes in battery temperature
  • particles is not limited to only spherical shapes (circular cross-sectional shapes), but also includes individual particles whose cross-sectional shapes are elliptical, rectangular, trapezoidal, pyramidal, square with rounded corners, and asymmetrical. Further, individual particles may have an amorphous shape.
  • homogeneity refers to a state in which a certain element (for example, A) is distributed with similar characteristics in a specific region in a solid composed of multiple elements (for example, A, B, and C). Note that it is sufficient that the concentrations of the elements in the specific regions are substantially the same. For example, it is sufficient if the difference in the detected amount of a certain element (for example, the count number in STEM-EDX) between specific regions is within 10%.
  • Specific areas include, for example, the surface layer, the surface, protrusions, recesses, and the inside.
  • a positive electrode active material to which additive elements are added may be expressed as a composite oxide, a positive electrode material, a positive electrode material, a positive electrode material for secondary batteries, etc.
  • the positive electrode active material of one embodiment of the present invention preferably contains a compound.
  • the positive electrode active material of one embodiment of the present invention preferably has a composition.
  • the positive electrode active material of one embodiment of the present invention preferably has a composite.
  • all particles do not necessarily have to have the characteristics. For example, if 50% or more, preferably 70% or more, more preferably 90% or more of three or more randomly selected positive electrode active material particles have the characteristic, it is sufficient to have the positive electrode active material and the same. It can be said that this has the effect of improving the characteristics of the secondary battery.
  • a short circuit in the secondary battery not only causes problems in the charging and/or discharging operation of the secondary battery, but also may cause heat generation and ignition.
  • short current is suppressed even at high charging voltage. Therefore, it is possible to obtain a secondary battery that has both high discharge capacity and safety.
  • materials included in the secondary battery will be described in terms of their state before deterioration.
  • a decrease in discharge capacity due to aging treatment (which may also be called burn-in treatment) in the secondary battery manufacturing stage is not called deterioration.
  • a lithium ion secondary cell or a lithium secondary assembled battery hereinafter referred to as a lithium ion secondary battery
  • the rated capacity is based on JIS C 8711:2019 for lithium ion secondary batteries for portable devices. In the case of other lithium ion secondary batteries, they comply with not only the JIS standards mentioned above but also JIS and IEC standards for electric vehicle propulsion, industrial use, etc.
  • the state of the materials of the secondary battery before deterioration is called the initial product or initial state
  • the state after deterioration (the state when the secondary battery has a discharge capacity of less than 97% of its rated capacity) is called the initial product or initial state.
  • ignition in the nail penetration test means that flame is observed outside the exterior body within one minute after the nail penetration test. Or, it means that thermal runaway of the secondary battery has occurred. For example, if the temperature rise of the secondary battery exceeds 100°C, it can be said that thermal runaway has occurred. The temperature at this time can be measured by a temperature sensor attached to the outer casing of the secondary battery. Furthermore, if a solid thermal decomposition product derived from the positive electrode and/or negative electrode is observed at a location 2 cm or more away from the nail penetration test after the nail penetration test, it can also be said that a fire has occurred.
  • the O/M ratio (M is the sum of nickel, cobalt, and manganese) is theoretically 2.
  • oxygen is released from LiMO 2 due to thermal runaway, the O/M ratio decreases. Therefore, for example, if the O/M ratio in EDX analysis is less than 1.3 at a location 2 cm or more away from the nail penetration test after the nail penetration test, it can be said that thermal runaway has occurred, that is, ignition has occurred.
  • the thermal decomposition products of the positive electrode and/or negative electrode also include, for example, aluminum oxide, which is the oxidation of aluminum in the positive electrode current collector, and copper oxide, which is the oxidation of the copper in the negative electrode current collector.
  • the positive electrode active material 101 includes lithium, a transition metal M, and oxygen.
  • the transition metal M is one or more selected from nickel, manganese, and cobalt, and other elements are not applicable.
  • an additive element for example, one or more selected from fluorine, aluminum, magnesium, titanium, calcium, and zirconium can be used.
  • the positive electrode active material 101 may include nickel-manganese-lithium cobalt oxide to which additional elements are added.
  • the positive electrode active material of a lithium ion secondary battery must contain a transition metal capable of redox in order to maintain charge neutrality even when lithium ions are inserted or removed.
  • the positive electrode active material 101 according to one embodiment of the present invention includes nickel, manganese, and cobalt as the transition metal M responsible for the redox reaction.
  • FIG. 3A is a schematic diagram showing an example of the appearance of the positive electrode active material 101.
  • the positive electrode active material 101 has a plurality of primary particles 100 aggregated to form one secondary particle.
  • the term "primary particle" refers to a particle that is recognized as a single particle during SEM observation.
  • secondary particles refer to aggregates of primary particles.
  • the bonding force acting between a plurality of primary particles does not matter. It may be a covalent bond, an ionic bond, a hydrophobic interaction, a van der Waals force, or any other intermolecular interaction, or a plurality of bonding forces may be at work. Note that in FIG. 3A, the layer 100m containing a large amount of additive elements is not shown for clarity.
  • FIG. 3B shows an example of a schematic cross-sectional view of the positive electrode active material 101.
  • FIG. 3B shows several variations in the case where a layer containing a large amount of additive elements is provided on the primary particles constituting the secondary particles. Some primary particles and their surface layer portions drawn out by arrows are shown in multiple locations in FIG. 3B.
  • the primary particles 100 a region other than the layer containing a large amount of additive elements is referred to as the inside. In other words, the inside is a region where the detected amount of the added element is relatively small.
  • the layer 100m containing a large amount of additive elements is provided on the entire surface of the primary particles 100, and there are also cases where the primary particles 100 are not provided with a layer containing a large amount of additive elements. Further, layers 100m1 and 100m2 containing a large amount of additive elements may be provided at both ends of the primary particles 100, respectively. Further, even in the case of the primary particle 100 disposed in the central part of the secondary particle, the layer 100m containing a large amount of additive elements may be provided on the entire surface of the primary particle 100. Further, a layer 100 m3 containing a large amount of additive elements may be provided only on a part of the surface. Further, a layer 100m4 containing a large amount of additive elements common to the two primary particles may be provided. The thickness of the layer 100m containing a large amount of additive elements is preferably 1 nm or more and 10 nm or less.
  • FIG. 4A shows an example of a schematic cross-sectional view of the positive electrode active material 101a.
  • FIG. 4A shows an example in which a layer 100m5 containing a large amount of additive elements is provided so as to cover the entire outside of the positive electrode active material 101a.
  • FIG. 4B also shows an example of a schematic cross-sectional view of the positive electrode active material 101b.
  • FIG. 4B shows an example in which a layer 100m6 containing a large amount of additive elements is provided on the surface layer of the positive electrode active material 101b.
  • FIG. 4B it can be said that the surface layer portion of the positive electrode active material 101b and the layer 100m6 containing a large amount of additive elements coincide with each other.
  • the positive electrode active material 101 shown in FIG. 3B and FIG. It is possible to obtain the configuration of either the positive electrode active material 101a in FIG. 4A or the positive electrode active material 101b in FIG. 4B, or a configuration similar thereto.
  • the surface layer of at least one of the plurality of primary particles contains a layer containing a large amount of additive elements, cracks that occur between the primary particles during charging and discharging can be reduced, and the secondary battery can improve the safety or longevity characteristics of
  • the positive electrode active material 101 which is a secondary particle, has been described in FIGS. 3 and 4, one embodiment of the present invention is not limited thereto.
  • the positive electrode active material 101 may be a single particle (also referred to as a primary particle) as shown in FIG. 5A. In this case, although it may have grain boundaries 105 inside as shown in FIG. 5B, it is preferable to have high crystallinity, and more preferably to be a single crystal.
  • the layer 100m containing a large amount of the additive element and the inside thereof have the same main component (for example, nickel), and the layer 100m containing a large amount of the additive element and the inside thereof are connected to each other.
  • the layer 100m containing a large amount of additive elements protects the inside, it has an excellent effect against internal short circuits when used in a secondary battery.
  • the structure since the structure has 100 m of layers containing a large amount of additive elements when a nail or the like is penetrated from the outside of the secondary battery, it can be regarded as a positive electrode active material structure that does not ignite or is difficult to ignite.
  • the detected amount of one selected from the additive elements is greater than that inside, so that excessive reaction between the positive electrode active material 101 and the electrolyte can be suppressed. . Therefore, when used in a secondary battery, it can be expected to improve safety against internal short circuits of the secondary battery. Furthermore, corrosion resistance against hydrofluoric acid can be effectively improved.
  • the detected amount of one or more selected from the additive elements in the layer 100m containing a large amount of additive elements becomes higher than that inside the layer 100m, thereby changing the conductivity of the surface of the positive electrode active material 101.
  • the powder resistance of the positive electrode active material 101 is increased.
  • a highly safe secondary battery can be obtained when used in a secondary battery. For example, ignition due to internal short circuits can be suppressed.
  • the amount of the added element detected is larger in the layer 100m containing more added elements than in the inside.
  • the additive element be contained inside at a low concentration.
  • the crystal structure of the positive electrode active material 101 may be made more stable.
  • the concentration of the added element even if it exists inside, it may be below the detection limit in analysis such as EDX and XPS.
  • FIGS. 1A and 1B show models of lithium cobalt oxide containing magnesium and lithium cobalt oxide containing magnesium and fluorine, as examples of positive electrode active materials having 100 m of layers containing many additive elements. For these two models, the energy change upon reaction with metallic lithium was calculated.
  • FIG. 1A there is no fluorine on the surface, and when oxygen is desorbed from lithium cobalt oxide, the oxygen reacts with metal Li originating from the negative electrode (assuming a Li dendrite extending from the negative electrode), forming Li 2 O (lithium oxide). ) is generated.
  • FIG. 1B is a model assuming a case where fluorine is present on the surface and LiF (lithium fluoride) is generated by the reaction between the metal Li derived from the negative electrode and the fluorine.
  • metal Li generates less heat when it reacts with fluorine than with oxygen, so by creating a 100m layer containing a large amount of fluorine-containing additive elements, it can be used in secondary batteries with high safety. There is a possibility that it can be used as a secondary battery.
  • FIG. 2A where only aluminum fluoride is assumed as the additive element source, there is a region with little bonding, as shown by the broken ellipse line in the figure, and it was predicted that the adhesion between the interior and the surface layer would be poor.
  • FIGS. 2B to 2D which assume that both aluminum fluoride and lithium fluoride are used as additive element sources, the regions with few bonds as in FIG. 2A are reduced, and the crystal structure is oriented in at least a portion It was predicted that the adhesion between the inside and the surface layer was relatively good.
  • the positive electrode active material 101 of one embodiment of the present invention preferably has a layered rock salt crystal structure.
  • it is preferable that x, y, and z satisfy x:y:z 1:4:1 or a value in the vicinity thereof.
  • a value in the vicinity of a composition refers to a range in which the composition is obtained when the significant figure is set to one digit. At this time, the digits below the significant figures are rounded off.
  • a positive electrode active material having a layered rock salt type crystal structure and containing nickel, cobalt, and manganese as transition metals M is also referred to as NCM.
  • the positive electrode active material 101 according to one embodiment of the present invention is a single particle (primary particle), it is preferable that the particle size is smaller so that cracks are less likely to occur. On the other hand, if the particle size is too small, there is a concern that the specific surface area will increase and side reactions with the electrolyte will increase. Therefore, the positive electrode active material of one embodiment of the present invention preferably has a median diameter of 2 ⁇ m or more and 20 ⁇ m or less as measured by a laser diffraction/scattering method.
  • the surface of the positive electrode active material is preferably smooth and glossy.
  • the positive electrode active material has no corners or is rounded. Due to its smooth surface and lack of corners, the specific surface area is small and cracks are less likely to occur.
  • ultrafine particles may be fragments of the positive electrode active material and/or sources of additive elements that have not reacted.
  • ultrafine particles refer to metal compound particles having a particle size of 0.001 ⁇ m or more and 1 ⁇ m or less.
  • the particle size of the ultrafine particles is the Feret diameter or projection circle equivalent diameter measured from a surface SEM image. Whether it is a metal compound or not can be analyzed by SEM-EDX or the like.
  • the positive electrode active material of one embodiment of the present invention a material that functions as a flux is added together with the additive element source.
  • the surface of the composite oxide and the additive element source are melted during heating, and then solidified. Therefore, even if extremely small particles are attached to the surface, they will be melted together in these steps and will not remain on the surface or will be extremely small.
  • the fact that there are no or very few ultrafine particles on the surface of the positive electrode active material can also be said to indicate that the composite oxide and the material functioning as a flux were heated together in the manufacturing process.
  • the above analysis method is particularly effective when the particle size is 1 ⁇ m or more because of the resolution of the surface SEM image.
  • the positive electrode active material 101 having a relatively small particle size is expected to have high charge/discharge rate characteristics.
  • the positive electrode active material 101 having a relatively large particle size is expected to have high charge/discharge cycle characteristics and maintain a high discharge capacity.
  • transition metal M sources that is, a nickel source (Ni source), a cobalt source (Co source), and a manganese source (Mn source) are first prepared. It is preferable that the mixing ratio of nickel, cobalt, and manganese be such that a layered rock salt type crystal structure can be formed.
  • the raw material may be cheaper than when the positive electrode active material 101 contains a large amount of cobalt, and the charge/discharge capacity per weight may increase, which is preferable.
  • nickel in the transition metal M (M is the sum of nickel, cobalt, and manganese), nickel preferably exceeds 25 atom %, more preferably 60 atom % or more, and even more preferably 80 atom % or more.
  • the content of nickel in the transition metal M is 95 atomic % or less.
  • cobalt as the transition metal M, since the average discharge voltage is high and cobalt contributes to stabilizing the layered rock-salt structure, resulting in a highly reliable secondary battery.
  • the transition metal M it is preferable to have manganese as the transition metal M because heat resistance and chemical stability are improved. However, if the proportion of manganese is too high, the discharge voltage and discharge capacity tend to decrease. Therefore, for example, it is preferable that the content of manganese in the transition metal M is 2.5 atomic % or more and 34 atomic % or less.
  • the transition metal M source is prepared as an aqueous solution containing transition metal M.
  • an aqueous solution of nickel salt can be used.
  • nickel salt for example, nickel sulfate, nickel chloride, nickel nitrate, or hydrates thereof can be used.
  • organic acid salts of nickel such as nickel acetate, or hydrates thereof can also be used.
  • an aqueous solution of nickel alkoxide or an organic nickel complex can be used as the nickel source.
  • an organic acid salt refers to a compound of an organic acid such as acetic acid, citric acid, oxalic acid, formic acid, butyric acid, and a metal.
  • an aqueous solution of cobalt salt can be used as the cobalt source.
  • cobalt salt for example, cobalt sulfate, cobalt chloride, cobalt nitrate, or hydrates thereof can be used.
  • organic acid salts of cobalt such as cobalt acetate, or hydrates thereof can also be used.
  • an aqueous solution of a cobalt alkoxide or an organic cobalt complex can be used as the cobalt source.
  • an aqueous solution of manganese salt can be used as the manganese source.
  • the manganese salt for example, manganese sulfate, manganese chloride, manganese nitrate, or an aqueous solution of a hydrate thereof can be used.
  • organic acid salts of manganese such as manganese acetate, or hydrates thereof can also be used.
  • an aqueous solution of manganese alkoxide or an organic manganese complex can be used as the manganese source.
  • an aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate are dissolved in pure water is prepared as a transition metal M source.
  • the aqueous solution exhibits acidity.
  • a chelating agent may be prepared.
  • Chelating agents include, for example, glycine, oxine, 1-nitroso-2-naphthol, 2-mercaptobenzothiazole, or EDTA (ethylenediaminetetraacetic acid).
  • you may use multiple types selected from glycine, oxine, 1-nitroso-2-naphthol, and 2-mercaptobenzothiazole. At least one of these is dissolved in pure water and used as a chelate aqueous solution.
  • Chelating agents are complexing agents that create chelate compounds and are preferred over common complexing agents.
  • a complexing agent may be used instead of a chelating agent, and aqueous ammonia can be used as the complexing agent.
  • a chelate aqueous solution because it can suppress unnecessary generation of crystal nuclei and promote growth. When the generation of unnecessary nuclei is suppressed, the generation of fine particles is suppressed, so that a composite hydroxide with a good particle size distribution can be obtained.
  • an aqueous chelate solution the acid-base reaction can be delayed, and the reaction proceeds gradually, making it possible to obtain nearly spherical secondary particles.
  • Glycine has the effect of keeping the pH value constant at a pH of 9 or more and 10 or less, and by using a glycine aqueous solution as the chelate aqueous solution, the pH of the reaction tank when obtaining the above composite hydroxide 98 can be adjusted. This is preferable because it is easier to control.
  • Step S114 Next, in step S114 in FIG. 6A, a transition metal M source and a chelating agent are mixed to prepare an acid solution.
  • an alkaline solution is prepared.
  • an aqueous solution containing sodium hydroxide, potassium hydroxide, lithium hydroxide or ammonia can be used.
  • An aqueous solution in which these are dissolved using pure water can be used.
  • it may be an aqueous solution in which multiple types selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia are dissolved in pure water.
  • the pure water preferably used for the transition metal M source and alkaline solution is water with a specific resistance of 1 M ⁇ cm or more, more preferably water with a specific resistance of 10 M ⁇ cm or more, and even more preferably 15 M ⁇ cm or more. water. Water that satisfies the specific resistance has high purity and contains very few impurities.
  • Step S122 it is preferable to prepare water in the reaction tank.
  • This water may be an aqueous solution of a chelating agent, but is more preferably pure water. By using pure water, nucleation is promoted and a composite hydroxide with a small particle size can be produced.
  • the water prepared in this reaction tank can be called a filling liquid or adjustment liquid for the reaction tank.
  • a chelate aqueous solution the description of step S13 can be referred to.
  • step S131 of FIG. 6A the acid solution and the alkaline solution are mixed and reacted.
  • the reaction can be referred to as a coprecipitation reaction, a neutralization reaction, or an acid-base reaction.
  • the pH of the reaction system is 9.0 or more and 11.5 or less.
  • the pH of the aqueous solution in the reaction tank when an alkaline solution is placed in a reaction tank and an acid solution is dropped into the reaction tank, it is preferable to maintain the pH of the aqueous solution in the reaction tank within the range of the above conditions.
  • an acid solution is placed in a reaction tank and an alkaline solution is added dropwise.
  • the amount of solution in the reaction tank is 200 mL or more and 350 mL or less
  • the dropping rate of the acid solution or alkaline solution is preferably 0.01 mL/min or less because pH conditions can be easily controlled.
  • the reaction tank has a reaction container and the like.
  • stirring means include stirring by rotation of a stirrer or stirring blades. Two or more stirring blades and six or less stirring blades can be provided. For example, when four stirring blades are provided, they are preferably arranged in a cross shape when viewed from above.
  • the rotation speed of the stirring means is preferably 800 rpm or more and 1200 rpm or less.
  • a baffle plate may be provided in the reaction tank to change the stirring direction and flow rate. By providing a baffle plate, mixing efficiency is improved and more uniform composite hydroxide particles can be synthesized.
  • the temperature of the reaction tank is preferably adjusted to 50°C or more and 90°C or less. It is preferable to start dropping the alkaline solution or acid solution after the reaction tank has reached the desired temperature.
  • the inert atmosphere in this case can be nitrogen or argon.
  • nitrogen gas is preferably introduced at a flow rate of 0.5 L/min or more and 2 L/min or less.
  • a reflux condenser allows nitrogen gas to be vented from the reactor and water vapor to be returned to the reactor.
  • Step S132> In order to recover the composite hydroxide 98, it is preferable to perform filtration as shown in step S132 of FIG. 6A.
  • the filtration is preferably suction filtration.
  • an organic solvent such as acetone
  • the filtered composite hydroxide 98 is preferably dried. For example, it is dried under vacuum at a temperature of 60° C. or more and 200° C. or less for 0.5 hours or more and 20 hours or less. For example, it can be dried for 12 hours. In this way, composite hydroxide 98 can be obtained.
  • composite hydroxide 98 containing transition metal M can be obtained.
  • the composite hydroxide 98 refers to hydroxides of multiple types of metals.
  • the composite hydroxide 98 can be said to be a precursor of the positive electrode active material 101.
  • Step S141 Next, in step S141 of FIG. 6B, a lithium source and an additive element source are prepared.
  • lithium when the sum of nickel, cobalt, and manganese atoms is 1, it is more preferable that lithium be around 1.0 (atomic ratio).
  • lithium hydroxide lithium carbonate, lithium fluoride, or lithium nitrate
  • a material with a low melting point among lithium compounds such as lithium hydroxide (melting point: 462°C). Since cation mixing occurs more easily in a positive electrode active material containing a high proportion of nickel than in lithium cobalt oxide, etc., it is necessary to perform heating in step S143 and the like at a low temperature. Therefore, it is preferable to use a material with a low melting point.
  • the particle size of the lithium source is small because the reaction tends to proceed well.
  • a lithium source made into fine particles using a fluidized bed jet mill can be used.
  • the particle size here is the average particle size (also called average particle size) of the particle size distribution.
  • additive element source a compound having one or more selected from fluorine, aluminum, magnesium, titanium, calcium, and zirconium can be used.
  • fluorine sources include lithium fluoride (LiF), magnesium fluoride (MgF 2 ), aluminum fluoride (AlF 3 ), titanium fluoride (TiF 4 ), cobalt fluoride (CoF 2 , CoF 3 ), and nickel fluoride ( NiF 2 ), zirconium fluoride (ZrF 4 ), vanadium fluoride (VF 5 ), manganese fluoride, iron fluoride, chromium fluoride, niobium fluoride, zinc fluoride (ZnF 2 ), calcium fluoride (CaF 2 ) ), sodium fluoride (NaF), potassium fluoride (KF), barium fluoride (BaF 2 ), cerium fluoride (CeF 3 , CeF 4 ), lanthanum fluoride (LaF 3 ), or sodium aluminum hexafluoride ( Na 3 AlF 6 ), etc. can be used.
  • lithium fluoride is preferable because it has a relatively
  • the fluorine source may be a gas, such as fluorine (F 2 ), fluorocarbon, sulfur fluoride, or fluorinated oxygen (OF 2 , O 2 F 2 , O 3 F 2 , O 4 F 2 , O 5 F 2 , O 6 F 2 , O 2 F) or the like may be used and mixed in the atmosphere in the heating step described later. Further, a plurality of the above-mentioned fluorine sources may be used.
  • aluminum compounds such as aluminum oxide, aluminum hydroxide, and aluminum fluoride, and/or metal aluminum can be used.
  • magnesium sources for example, magnesium compounds such as magnesium fluoride, magnesium oxide, magnesium hydroxide, or magnesium carbonate, and/or magnesium metal can be used. Further, a plurality of the above-mentioned magnesium sources may be used.
  • Magnesium fluoride can be used both as a fluorine source and as a magnesium source. Lithium fluoride can also be used as a lithium source.
  • titanium compounds such as titanium oxide, titanium hydroxide, and titanium fluoride, and/or titanium metal can be used.
  • calcium compounds such as calcium carbonate, calcium fluoride, calcium hydroxide, and calcium oxide, and/or metallic calcium can be used.
  • zirconium compounds such as zirconium oxide, zirconium hydroxide, and zirconium fluoride, and/or metal zirconium can be used.
  • lithium fluoride can function as a flux in the subsequent heating step.
  • a phase diagram of magnesium fluoride, which is a fluorine source and a magnesium source, and lithium fluoride, which is a fluxing agent is shown in FIG. 8 (cited and added from FIG. 7 of Non-Patent Document 1).
  • the eutectic point P of LiF and MgF 2 is around 742° C. (T1).
  • FIG. 9 a phase diagram of nickel fluoride, which is a fluorine source and a nickel source, and lithium fluoride, which is a flux, is shown in FIG. 9 (cited from Non-Patent Document 2, FIG. 3).
  • the eutectic point of LiF and NiF 2 is within the range of 1060 [K] to 1065 [K] (787°C to within the range of 792°C).
  • the eutectic point of aluminum fluoride which is a fluorine source and an aluminum source
  • lithium fluoride which is a flux
  • lithium fluoride which can function as a flux
  • an additive element source such as aluminum fluoride
  • they can be melted together with part of the surface layer of the composite oxide in the subsequent heating process. , forming a molten layer.
  • the molten layer is cooled after the heating step, it becomes a thin and dense barrier film, such as a film formed by an ALD (Atomic Layer Deposition) method.
  • the additive elements are dissolved in solid solution with good concentration and distribution of the additive elements, resulting in a barrier film in which the crystal orientation roughly matches that of the inside.
  • step S142 in FIG. 6B the composite hydroxide 98 and a lithium source are mixed.
  • Mixing can be done dry or wet.
  • a ball mill, a bead mill, etc. can be used for mixing.
  • zirconia balls it is preferable to use zirconia balls as the media, for example.
  • the peripheral speed is preferably 100 mm/sec to 2000 mm/sec in order to suppress contamination from media or materials.
  • the cobalt compound and the lithium compound may be crushed.
  • Step S143 Next, the mixture of the composite hydroxide 98 and the lithium source is heated. To distinguish from other heating steps, in FIGS. 6B and 7, step S143 may be referred to as first heating, step S145 as second heating, and step S153 as third heating.
  • An electric furnace or a rotary kiln can be used as a firing device for performing this heating.
  • the crucible, sheath, setter, and container used during heating are preferably made of materials that do not easily release impurities.
  • an aluminum oxide crucible with a purity of 99.9% may be used.
  • mullite/cordierite (Al 2 O 3 .SiO 2 .MgO) pods may be used.
  • the temperature of the heating in step S143 is preferably 400°C or more and 750°C or less, more preferably 650°C or more and 750°C or less. Further, the heating time in step S143 is preferably 1 hour or more and 30 hours or less, more preferably 2 hours or more and 20 hours or less.
  • the heating atmosphere is preferably an oxygen-containing atmosphere or an oxygen-containing atmosphere that is so-called dry air and contains little water (for example, a dew point of -50°C or lower, more preferably a dew point of -80°C or lower).
  • step S144 it is preferable to include a crushing step after heating as step S144. Disintegration can be carried out, for example, in a mortar. Furthermore, it may be classified using a sieve.
  • step S145 heating is performed. It is preferable that the heating temperature in step S145 is higher than the heating temperature in step S143.
  • the heating in step S143 may be referred to as preliminary firing, and the heating in step S145 may be referred to as main firing.
  • the temperature of the heating in step S145 is preferably higher than 750°C and lower than 1050°C. Further, the heating time in step S145 is preferably 1 hour or more and 30 hours or less, more preferably 2 hours or more and 20 hours or less.
  • step S146 it is preferable to include a crushing step after heating as step S146. Disintegration can be carried out, for example, in a mortar. Furthermore, it may be classified using a sieve. Through the above steps, a positive electrode active material 101 is obtained.
  • FIGS. 6A and 6B describe a manufacturing method in which the step of adding an additive element source is performed once, one embodiment of the present invention is not limited to this.
  • the additive element source may be added in multiple portions.
  • a method for producing a positive electrode active material in which an additive element source is added in two steps will be described with reference to FIG. Mainly, points different from the manufacturing method explained with reference to FIGS. 6A and 6B will be explained.
  • Step S111 to Step S133 First, as in FIG. 6A, a composite hydroxide 98 is produced through steps S111 to S133.
  • Step S141 to Step S146> a composite oxide 99 is obtained through steps similar to steps S141 to S146 in FIG. 6B.
  • step S151 in FIG. 7 an additive element source is prepared.
  • the description in step S141 can be referred to.
  • Step S152 Next, the composite oxide 99 and the additive element source are mixed.
  • step S142 the description of step S142 can be referred to.
  • Step S153 Next, the mixture of the composite oxide 99 and the additive element source is heated.
  • the heating in step S153 is preferably at a sufficiently high temperature in order to increase the crystallite size of the positive electrode active material 101, but the temperature range may vary depending on the composition of the transition metal M.
  • the temperature is preferably 750°C or higher.
  • the temperature is preferably 950°C or lower, more preferably 920°C or lower, and even more preferably 900°C or lower.
  • the temperature is preferably 850°C or higher, more preferably 900°C or higher, and even more preferably 1000°C or lower.
  • the heating temperature in step S153 is too high, the same disadvantages as described above may occur, so it is preferably 1050° C. or lower. For other heating conditions, refer to the description of step S143.
  • step S154 it is preferable to include a crushing step after heating as step S154.
  • the description of step S144 can be referred to.
  • FIG. 7 describes a method of heating in step S153 after mixing the additive element source in step S151, one embodiment of the present invention is not limited to this. Heating may be performed two or more times as the heating in step S153.
  • the positive electrode active material 101 can be produced.
  • additive elements may be added together with the transition metal M source.
  • the additive element may be added after the composite oxide containing lithium and the transition metal M is produced.
  • additional elements may be added to the composite oxide containing lithium and transition metal M that has been prepared in advance. By changing the process of adding the additive element, it may be possible to change the depth profile of the additive element in the positive electrode active material.
  • FIG. 11A is an exploded perspective view of a coin-shaped (single-layer flat type) secondary battery
  • FIG. 11B is an external view
  • FIG. 11C is a cross-sectional view thereof.
  • Coin-shaped secondary batteries are mainly used in small electronic devices.
  • FIG. 11A is a schematic diagram so that the overlapping (vertical relationship and positional relationship) of members can be seen. Therefore, FIG. 11A and FIG. 11B are not completely corresponding diagrams.
  • the positive electrode 304, separator 310, negative electrode 307, spacer 322, and washer 312 are stacked. These are sealed with a negative electrode can 302 and a positive electrode can 301 with a gasket. Note that in FIG. 11A, a gasket for sealing is not shown.
  • the spacer 322 and the washer 312 are used to protect the inside or fix the position inside the can when the positive electrode can 301 and the negative electrode can 302 are crimped together.
  • the spacer 322 and washer 312 are made of stainless steel or an insulating material.
  • a positive electrode 304 has a laminated structure in which a positive electrode active material layer 306 is formed on a positive electrode current collector 305 .
  • a slurry containing the positive electrode active material 101 is applied onto the current collector and dried to form the positive electrode active material layer 306. Pressing may be performed after forming the positive electrode active material layer 306.
  • the slurry includes a conductive material, a binder, and a solvent in addition to the positive electrode active material 101. Note that a carbon material such as graphite or carbon fiber is used as the conductive material.
  • a carbon material or a metal material is typically used as the conductive material.
  • the conductive material is in the form of particles, and examples of the conductive material in the form of particles include carbon black (furnace black, acetylene black, graphite, etc.). Carbon black often has a smaller particle size than the positive electrode active material.
  • the conductive material may be in the form of fibers, and carbon nanotubes (CNTs) and VGCF (registered trademark) are examples of the conductive aids in the form of fibers.
  • CNTs carbon nanotubes
  • VGCF registered trademark
  • sheet-like conductive materials such as multilayer graphene as a sheet-like conductive aid.
  • the sheet-like conductive additive may appear thread-like in the cross section of the positive electrode.
  • Particulate conductive materials can get into gaps in the positive electrode active material, etc., and are likely to aggregate. Therefore, the particulate conductive material can assist in forming a conductive path between the cathode active materials disposed nearby.
  • the fibrous conductive material also has a bent region, but it is larger than the positive electrode active material. Therefore, the fibrous conductive material can assist the conductive path not only between adjacent positive electrode active materials but also between distant positive electrode active materials. In this way, it is preferable to mix two or more shapes of conductive aids.
  • the weight of carbon black is 1.5 times or more and 20 times or less of the multilayer graphene. , preferably 2 times or more and 9.5 times or less in weight.
  • graphene includes multilayer graphene and multigraphene.
  • graphene refers to something that contains carbon, has a shape such as a flat plate or a sheet, and has a two-dimensional structure formed of a six-membered carbon ring.
  • the two-dimensional structure formed by the six-membered carbon ring is sometimes called a carbon sheet.
  • graphene compounds include graphene oxide, multilayer graphene oxide, multilayer graphene oxide, reduced graphene oxide, reduced multilayer graphene oxide, reduced multilayer graphene oxide, graphene quantum dots, and the like.
  • the graphene compound may have a functional group.
  • it is preferable that the graphene or graphene compound has a bent shape.
  • graphene or a graphene compound may be rounded, and rounded graphene is sometimes called carbon nanofiber.
  • graphene oxide refers to one that contains carbon and oxygen, has a sheet-like shape, and has a functional group, particularly an epoxy group, a carboxy group, or a hydroxy group.
  • Fluorine-containing graphene may be used as the graphene compound. Fluorine in the graphene compound is preferably adsorbed on the surface. Further, fluorine-containing graphene can be produced by bringing graphene and a fluorine compound into contact (referred to as fluorination treatment). Fluorine (F 2 ) or a fluorine compound may be used for the fluorination treatment. Examples of fluorine compounds include hydrogen fluoride, fluorinated halogens ( ClF3 , IF5, etc.), gaseous fluorides ( BF3 , NF3 , PF5 , SiF4 , SF6 , etc.), metal fluorides (LiF, NiF2, etc. ).
  • the fluorination treatment it is preferable to use a gaseous fluoride, and the gaseous fluoride may be diluted with an inert gas.
  • the temperature of the fluorination treatment is preferably room temperature, and is preferably 0° C. or higher and 250° C. or lower, which includes the room temperature. When the fluorination treatment is performed at 0° C. or higher, fluorine can be adsorbed onto the surface of graphene.
  • Graphene compounds may have excellent electrical properties such as high conductivity, and excellent physical properties such as high flexibility and high mechanical strength. Further, the graphene compound has a sheet-like shape. Graphene compounds may have curved surfaces, allowing surface contact with low contact resistance. Further, even if it is thin, it may have very high conductivity, and a conductive path can be efficiently formed within the active material layer with a small amount. Therefore, by using a graphene compound as a conductive material, the contact area between the active material and the conductive material can be increased.
  • the graphene compound preferably covers 80% or more of the area of the active material. Note that it is preferable that the graphene compound clings to at least a portion of the active material particles.
  • the graphene compound overlaps at least a portion of the active material particles. Further, it is preferable that the shape of the graphene compound matches at least a portion of the shape of the active material particles.
  • the shape of the active material particles refers to, for example, the unevenness of a single active material particle or the unevenness formed by a plurality of active material particles. Further, it is preferable that the graphene compound surrounds at least a portion of the active material particles. Further, the graphene compound may have holes.
  • active material particles with a small particle size for example, active material particles of 1 ⁇ m or less
  • the specific surface area of the active material particles is large, and more conductive paths connecting the active material particles are required.
  • Rapid charging and discharging refers to charging and discharging at a rate of, for example, 200 mA/g, 400 mA/g, or 1000 mA/g or more.
  • Fluorine-containing acetylene black may be used as the conductive material.
  • the fluorine present in the fluorine-containing acetylene black is preferably adsorbed on the surface.
  • fluorine-containing acetylene black can be produced by bringing acetylene black into contact with a fluorine compound (referred to as fluorination treatment).
  • fluorination treatment the content explained for graphene can be applied to acetylene black.
  • fluorine present in the fluorine-containing carbon nanotubes as a conductive material is preferably adsorbed on the surface.
  • fluorine-containing carbon nanotubes can be produced by bringing carbon nanotubes into contact with a fluorine compound (referred to as fluorination treatment).
  • fluorination treatment the content explained for graphene can be applied to carbon nanotubes.
  • binder it is preferable to use rubber materials such as styrene-butadiene rubber (SBR), styrene-isoprene-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, and ethylene-propylene-diene copolymer. Furthermore, fluororubber can be used as the binder.
  • SBR styrene-butadiene rubber
  • fluororubber can be used as the binder.
  • the binder it is preferable to use, for example, a water-soluble polymer.
  • a water-soluble polymer for example, polysaccharides can be used.
  • the polysaccharide one or more of cellulose derivatives such as carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, regenerated cellulose, starch, etc. can be used. Further, it is more preferable to use these water-soluble polymers in combination with the above-mentioned rubber material.
  • CMC carboxymethyl cellulose
  • ethyl cellulose methyl cellulose
  • hydroxypropyl cellulose diacetyl cellulose
  • regenerated cellulose starch, etc.
  • polystyrene polymethyl acrylate, polymethyl methacrylate (polymethyl methacrylate, PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride
  • PVA polyvinyl alcohol
  • PEO polyethylene oxide
  • PEO polypropylene oxide
  • polyimide polyvinyl chloride
  • materials such as polytetrafluoroethylene, polyethylene, polypropylene, polyisobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), ethylene propylene diene polymer, polyvinyl acetate, nitrocellulose, etc.
  • the binder may be used in combination of more than one of the above.
  • FIG. 11B is a perspective view of the completed coin-shaped secondary battery.
  • a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 302 that also serves as a negative electrode terminal are insulated and sealed with a gasket 303 made of polypropylene or the like.
  • the positive electrode 304 is formed by a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with the positive electrode current collector 305 .
  • the negative electrode 307 is formed of a negative electrode current collector 308 and a negative electrode active material layer 309 provided in contact with the negative electrode current collector 308. Further, the negative electrode 307 is not limited to a laminated structure, and lithium metal foil or lithium-aluminum alloy foil may be used.
  • each of the positive electrode 304 and negative electrode 307 used in the coin-shaped secondary battery 300 may be formed only on one side.
  • the positive electrode can 301 and the negative electrode can 302 metals such as nickel, aluminum, titanium, etc., which are corrosion resistant to electrolyte, or alloys thereof, or alloys of these and other metals (for example, stainless steel, etc.) can be used. can. Further, in order to prevent corrosion due to electrolyte and the like, it is preferable to coat with nickel, aluminum, or the like.
  • the positive electrode can 301 is electrically connected to the positive electrode 304
  • the negative electrode can 302 is electrically connected to the negative electrode 307.
  • negative electrode 307, positive electrode 304, and separator 310 are immersed in an electrolytic solution, and the positive electrode 304, separator 310, negative electrode 307, and negative electrode can 302 are stacked in this order with the positive electrode can 301 facing down, as shown in FIG. 301 and a negative electrode can 302 are crimped together via a gasket 303 to produce a coin-shaped secondary battery 300.
  • an electrolytic solution including a solvent and an electrolyte dissolved in the solvent can be used.
  • aprotic organic solvents are preferred, such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate, ⁇ -butyrolactone, ⁇ -valerolactone, and dimethyl carbonate.
  • DMC diethyl carbonate
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • methyl formate methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1,3-dioxane, 1,4 -
  • DME dimethoxyethane
  • DME dimethyl sulfoxide
  • diethyl ether methyl diglyme
  • acetonitrile benzonitrile
  • tetrahydrofuran sulfolane
  • sultone etc.
  • Ionic liquids are composed of cations and anions, and include organic cations and anions.
  • Examples of the organic cation used in the electrolytic solution include aliphatic onium cations such as quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, and aromatic cations such as imidazolium cations and pyridinium cations.
  • examples of anions used in the electrolytic solution include monovalent amide anions, monovalent methide anions, fluorosulfonic acid anions, perfluoroalkylsulfonic acid anions, tetrafluoroborate anions, perfluoroalkylborate anions, and hexafluorophosphate anions. , or perfluoroalkyl phosphate anion.
  • electrolytes to be dissolved in the above solvent examples include LiPF 6 , LiClO 4 , LiAsF 6 , LiBF 4 , LiAlCl 4 , LiSCN, LiBr, LiI, Li 2 SO 4 , Li 2 B 10 Cl 10 , Li 2 B 12 Cl12 , LiCF3SO3 , LiC4F9SO3 , LiC (CF3SO2 ) 3 , LiC( C2F5SO2 ) 3 , LiN ( CF3SO2 ) 2 , LiN ( C4F9
  • One type of lithium salt such as SO 2 )(CF 3 SO 2 ), LiN(C 2 F 5 SO 2 ) 2 , lithium bis(oxalate)borate (Li(C 2 O 4 ) 2 , LiBOB), or any of these Two or
  • the electrolyte contains vinylene carbonate, propane sultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), lithium bis(oxalate)borate (LiBOB), and dinitrile compounds such as succinonitrile and adiponitrile.
  • Additives such as fluorobenzene and ethylene glycose bis(propionitrile) ether may also be added.
  • the concentration of each additive may be, for example, 0.1 wt% or more and 5 wt% or less with respect to the solvent in which the electrolyte is dissolved.
  • adiponitrile is expected to enhance high voltage resistance through interaction with the surface of the positive electrode active material 101 of one embodiment of the present invention, and therefore adiponitrile cannot be used in a secondary battery using the positive electrode active material of one embodiment of the present invention.
  • the additive may form a film that adheres to the surface of the active material during aging treatment of the secondary battery. Therefore, in a secondary battery that has been charged and discharged even slightly, at least some additives may not be detected in the electrolyte.
  • vinylene carbonate is known to form a film on the surface of the negative electrode active material, so even if it is added at the manufacturing stage, it may not be detected in the electrolyte of commercially available secondary batteries.
  • a separator When the electrolyte contains an electrolytic solution, a separator is placed between the positive electrode and the negative electrode.
  • a separator for example, fibers containing cellulose such as paper, nonwoven fabrics, glass fibers, ceramics, synthetic fibers using nylon (polyamide), vinylon (polyvinyl alcohol fiber), polyester, acrylic, polyolefin, polyurethane, etc. It is possible to use one formed of . It is preferable that the separator is processed into a bag shape and arranged so as to surround either the positive electrode or the negative electrode.
  • the separator may have a multilayer structure.
  • a film of an organic material such as polypropylene or polyethylene can be coated with a ceramic material, a fluorine material, a polyamide material, or a mixture thereof.
  • the ceramic material for example, aluminum oxide particles, silicon oxide particles, etc. can be used.
  • the fluorine-based material for example, PVDF, polytetrafluoroethylene, etc. can be used.
  • the polyamide material for example, nylon, aramid (meta-aramid, para-aramid), etc. can be used.
  • Coating with a ceramic material improves oxidation resistance, so it is possible to suppress deterioration of the separator during high voltage charging and discharging and improve the reliability of the secondary battery. Furthermore, coating with a fluorine-based material makes it easier for the separator and electrode to come into close contact with each other, thereby improving output characteristics. Coating with a polyamide-based material, especially aramid, improves heat resistance, thereby improving the safety of the secondary battery.
  • a mixed material of aluminum oxide and aramid may be coated on both sides of a polypropylene film.
  • the surface of the polypropylene film in contact with the positive electrode may be coated with a mixed material of aluminum oxide and aramid, and the surface in contact with the negative electrode may be coated with a fluorine-based material.
  • the safety of the secondary battery can be maintained even if the overall thickness of the separator is thin, so the capacity per volume of the secondary battery can be increased.
  • the cylindrical secondary battery 616 has a positive electrode cap (battery lid) 601 on the top surface and a battery can (exterior can) 602 on the side and bottom surfaces. These positive electrode cap 601 and battery can (exterior can) 602 are insulated by a gasket (insulating packing) 610.
  • FIG. 12B is a diagram schematically showing a cross section of a cylindrical secondary battery.
  • the cylindrical secondary battery shown in FIG. 12B has a positive electrode cap (battery lid) 601 on the top surface and a battery can (exterior can) 602 on the side and bottom surfaces.
  • These positive electrode caps and the battery can (exterior can) 602 are insulated by a gasket (insulating packing) 610.
  • a band-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 in between.
  • a wound body in which a band-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 in between is wound around a central axis.
  • the battery can 602 has one end closed and the other end open.
  • metals such as nickel, aluminum, titanium, etc., which are corrosion resistant to electrolyte, or alloys thereof, or alloys of these and other metals (for example, stainless steel, etc.) can be used. .
  • the battery can 602 in order to prevent corrosion caused by the electrolyte, it is preferable to coat the battery can 602 with nickel, aluminum, or the like. Inside the battery can 602, a wound body in which a positive electrode, a negative electrode, and a separator are wound is sandwiched between a pair of opposing insulating plates 608 and 609. Furthermore, a non-aqueous electrolyte (not shown) is injected into the inside of the battery can 602 provided with the wound body. As the non-aqueous electrolyte, the same one as a coin-type secondary battery can be used.
  • a positive electrode terminal (positive electrode current collector lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collector lead) 607 is connected to the negative electrode 606.
  • Both the positive electrode terminal 603 and the negative electrode terminal 607 can be made of a metal material such as aluminum.
  • the positive terminal 603 and the negative terminal 607 are resistance welded to the safety valve mechanism 613 and the bottom of the battery can 602, respectively.
  • the safety valve mechanism 613 is electrically connected to the positive electrode cap 601 via a PTC element (Positive Temperature Coefficient) 611. The safety valve mechanism 613 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the increase in the internal pressure of the battery exceeds a predetermined threshold value.
  • the PTC element 611 is a heat-sensitive resistance element whose resistance increases when the temperature rises, and the increase in resistance limits the amount of current to prevent abnormal heat generation.
  • Barium titanate (BaTiO 3 )-based semiconductor ceramics or the like can be used for the PTC element.
  • FIG. 12C shows an example of the power storage system 615.
  • Power storage system 615 includes a plurality of secondary batteries 616.
  • the positive electrode of each secondary battery contacts a conductor 624 separated by an insulator 625 and is electrically connected.
  • the conductor 624 is electrically connected to the control circuit 620 via the wiring 623.
  • the negative electrode of each secondary battery is electrically connected to the control circuit 620 via a wiring 626.
  • As the control circuit 620 a charging/discharging control circuit that performs charging and discharging, or a protection circuit that prevents overcharging and/or overdischarging can be applied.
  • FIG. 12D shows an example of the power storage system 615.
  • the power storage system 615 has a plurality of secondary batteries 616, and the plurality of secondary batteries 616 are sandwiched between a conductive plate 628 and a conductive plate 614.
  • the plurality of secondary batteries 616 are electrically connected to a conductive plate 628 and a conductive plate 614 by wiring 627.
  • the plurality of secondary batteries 616 may be connected in parallel, connected in series, or connected in parallel and then further connected in series.
  • the set may be further connected in series.
  • a temperature control device may be provided between the plurality of secondary batteries 616.
  • the secondary battery 616 When the secondary battery 616 is overheated, it can be cooled by the temperature control device, and when the secondary battery 616 is too cold, it can be heated by the temperature control device. Therefore, the performance of power storage system 615 is less affected by outside temperature.
  • the power storage system 615 is electrically connected to the control circuit 620 via wiring 621 and wiring 622.
  • the wiring 621 is electrically connected to the positive electrodes of the plurality of secondary batteries 616 via the conductive plate 628
  • the wiring 622 is electrically connected to the negative electrodes of the plurality of secondary batteries 616 via the conductive plate 614.
  • FIGS. 13 and 14 A structural example of a secondary battery will be described using FIGS. 13 and 14.
  • a secondary battery 913 shown in FIG. 13A has a wound body 950 in which a terminal 951 and a terminal 952 are provided inside a casing 930.
  • the wound body 950 is immersed in the electrolyte inside the housing 930.
  • the terminal 952 is in contact with the housing 930, and the terminal 951 is not in contact with the housing 930 by using an insulating material or the like.
  • the housing 930 is shown separated in FIG. 13A for convenience, in reality, the wound body 950 is covered by the housing 930, and the terminals 951 and 952 extend outside the housing 930.
  • a metal material for example, aluminum
  • a resin material can be used as the housing 930.
  • the casing 930 shown in FIG. 13A may be formed of a plurality of materials.
  • a housing 930a and a housing 930b are bonded together, and a wound body 950 is provided in an area surrounded by the housing 930a and the housing 930b.
  • an insulating material such as organic resin can be used.
  • a material such as an organic resin on the surface where the antenna is formed shielding of the electric field by the secondary battery 913 can be suppressed.
  • an antenna may be provided inside the housing 930a.
  • a metal material can be used as the housing 930b.
  • the wound body 950 includes a negative electrode 931, a positive electrode 932, and a separator 933.
  • the wound body 950 is a wound body in which a negative electrode 931 and a positive electrode 932 are stacked on top of each other with a separator 933 in between, and the laminated sheet is wound. Note that a plurality of layers of the negative electrode 931, the positive electrode 932, and the separator 933 may be stacked.
  • a secondary battery 913 having a wound body 950a as shown in FIG. 14 may be used.
  • a wound body 950a shown in FIG. 14A includes a negative electrode 931, a positive electrode 932, and a separator 933.
  • the negative electrode 931 has a negative electrode active material layer 931a.
  • the positive electrode 932 has a positive electrode active material layer 932a.
  • the separator 933 has a width wider than the negative electrode active material layer 931a and the positive electrode active material layer 932a, and is wound so as to overlap with the negative electrode active material layer 931a and the positive electrode active material layer 932a. Further, from the viewpoint of safety, it is preferable that the width of the negative electrode active material layer 931a is wider than that of the positive electrode active material layer 932a. Further, the wound body 950a having such a shape is preferable because it has good safety and productivity.
  • the negative electrode 931 is electrically connected to the terminal 951 by ultrasonic bonding, welding, or crimping.
  • Terminal 951 is electrically connected to terminal 911a.
  • the positive electrode 932 is electrically connected to the terminal 952 by ultrasonic bonding, welding, or crimping.
  • Terminal 952 is electrically connected to terminal 911b.
  • the wound body 950a and the electrolyte are covered by the casing 930, forming a secondary battery 913.
  • the housing 930 is provided with a safety valve, an overcurrent protection element, and the like.
  • the safety valve is a valve that opens the inside of the casing 930 at a predetermined internal pressure in order to prevent the battery from exploding.
  • the secondary battery 913 may have a plurality of wound bodies 950a. By using a plurality of wound bodies 950a, the secondary battery 913 can have a larger discharge capacity.
  • the description of the secondary battery 913 shown in FIGS. 13A to 13C can be referred to.
  • FIGS. 15A and 15B an example of an external view of an example of a laminate type secondary battery is shown in FIGS. 15A and 15B.
  • 15A and 15B have a positive electrode 503, a negative electrode 506, a separator 507, an exterior body 509, a positive lead electrode 510, and a negative lead electrode 511.
  • FIG. 16A shows an external view of the positive electrode 503 and negative electrode 506.
  • the positive electrode 503 has a positive electrode current collector 501 , and the positive electrode active material layer 502 is formed on the surface of the positive electrode current collector 501 . Further, the positive electrode 503 has a region (hereinafter referred to as a tab region) where the positive electrode current collector 501 is partially exposed.
  • the negative electrode 506 has a negative electrode current collector 504 , and the negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504 . Further, the negative electrode 506 has a region where the negative electrode current collector 504 is partially exposed, that is, a tab region. Note that the area or shape of the tab regions of the positive electrode and the negative electrode is not limited to the example shown in FIG. 16A.
  • FIG. 13B shows a stacked negative electrode 506, separator 507, and positive electrode 503.
  • an example is shown in which five sets of negative electrodes and four sets of positive electrodes are used. It can also be called a laminate consisting of a negative electrode, a separator, and a positive electrode.
  • the tab regions of the positive electrodes 503 are joined together, and the positive lead electrode 510 is joined to the tab region of the outermost positive electrode. For example, ultrasonic welding or the like may be used for joining.
  • the tab regions of the negative electrodes 506 are bonded to each other, and the negative lead electrode 511 is bonded to the tab region of the outermost negative electrode.
  • a negative electrode 506, a separator 507, and a positive electrode 503 are placed on the exterior body 509.
  • the exterior body 509 is bent at the portion indicated by the broken line. After that, the outer peripheral portion of the exterior body 509 is joined. For example, thermocompression bonding or the like may be used for joining. At this time, a region (hereinafter referred to as an inlet) that is not joined is provided in a part (or one side) of the exterior body 509 so that the electrolyte can be introduced later.
  • an inlet a region (hereinafter referred to as an inlet) that is not joined is provided in a part (or one side) of the exterior body 509 so that the electrolyte can be introduced later.
  • the electrolytic solution is introduced into the interior of the exterior body 509 from the introduction port provided in the exterior body 509.
  • the electrolytic solution is preferably introduced under a reduced pressure atmosphere or an inert atmosphere.
  • connect the inlet In this way, a laminate type secondary battery 500 can be manufactured.
  • a secondary battery can typically be applied to an automobile.
  • automobiles include next-generation clean energy vehicles such as hybrid vehicles (HV), electric vehicles (EV), and plug-in hybrid vehicles (PHEV or PHV).
  • a secondary battery can be applied.
  • Vehicles are not limited to automobiles.
  • vehicles include trains, monorails, ships, submersibles (deep sea exploration vehicles, unmanned submarines), flying vehicles (helicopters, unmanned aerial vehicles (drones), airplanes, rockets, artificial satellites), electric bicycles, electric motorcycles, etc.
  • the secondary battery of one embodiment of the present invention can be applied to these vehicles.
  • the electric vehicle includes first batteries 1301a and 1301b as main drive secondary batteries, and a second battery 1311 that supplies power to an inverter 1312 that starts a motor 1304. is installed.
  • the second battery 1311 is also called a cranking battery (also called a starter battery).
  • the second battery 1311 only needs to have a high output, and a large capacity is not required, and the capacity of the second battery 1311 is smaller than that of the first batteries 1301a and 1301b.
  • the internal structure of the first battery 1301a may be a wound type shown in FIG. 13C or FIG. 14A, or a stacked type shown in FIG. 15A or FIG. 15B.
  • this embodiment shows an example in which two first batteries 1301a and 1301b are connected in parallel, three or more may be connected in parallel. Furthermore, if the first battery 1301a can store sufficient power, the first battery 1301b may not be necessary.
  • a battery pack that includes a plurality of secondary batteries, a large amount of electric power can be extracted.
  • a plurality of secondary batteries may be connected in parallel, may be connected in series, or may be connected in parallel and then further connected in series.
  • a plurality of secondary batteries is also called an assembled battery.
  • the first battery 1301a has a service plug or circuit breaker that can cut off high voltage without using tools. provided.
  • the electric power of the first batteries 1301a and 1301b is mainly used to rotate the motor 1304, but it is also used to power 42V-based in-vehicle components (electric power steering 1307, heater 1308, defogger 1309, etc.) via a DCDC circuit 1306. ). Even when the rear motor 1317 is provided on the rear wheel, the first battery 1301a is used to rotate the rear motor 1317.
  • the second battery 1311 supplies power to 14V vehicle components (audio 1313, power window 1314, lamps 1315, etc.) via the DCDC circuit 1310.
  • FIG. 17A shows an example in which nine square secondary batteries 1300 are used as one battery pack 1415. Further, nine prismatic secondary batteries 1300 are connected in series, one electrode is fixed by a fixing part 1413 made of an insulator, and the other electrode is fixed by a fixing part 1414 made of an insulator.
  • this embodiment shows an example in which the battery is fixed using the fixing parts 1413 and 1414, it may also be configured to be housed in a battery housing box (also referred to as a housing). Since it is assumed that a vehicle is subjected to vibrations or shaking from the outside (road surface, etc.), it is preferable to fix the plurality of secondary batteries using fixing parts 1413, 1414, a battery housing box, or the like.
  • one electrode is electrically connected to the control circuit section 1320 by a wiring 1421.
  • the other electrode is electrically connected to the control circuit section 1320 by a wiring 1422.
  • FIG. 17B shows an example of a block diagram of the battery pack 1415 shown in FIG. 17A.
  • the control circuit section 1320 includes a switch section 1324 including at least a switch for preventing overcharging and a switch for preventing overdischarge, a control circuit 1322 for controlling the switch section 1324, and a voltage measuring section for the first battery 1301a. has.
  • the control circuit section 1320 has an upper limit voltage and a lower limit voltage set for the secondary battery to be used, and limits the upper limit of the current from the outside or the upper limit of the output current to the outside.
  • the range of the secondary battery's lower limit voltage to upper limit voltage is within the recommended voltage range, and when it is outside that range, the switch section 1324 is activated and functions as a protection circuit.
  • control circuit section 1320 can also be called a protection circuit because it controls the switch section 1324 to prevent overdischarge and/or overcharge. For example, when the control circuit 1322 detects a voltage that is likely to cause overcharging, the switch section 1324 is turned off to cut off the current. Furthermore, a PTC element may be provided in the charging/discharging path to provide a function of cutting off the current in response to a rise in temperature. Further, the control circuit section 1320 has an external terminal 1325 (+IN) and an external terminal 1326 (-IN).
  • the switch section 1324 can be configured by combining n-channel transistors or p-channel transistors.
  • the switch section 1324 is not limited to a switch having an Si transistor using single crystal silicon, but includes, for example, Ge (germanium), SiGe (silicon germanium), GaAs (gallium arsenide), GaAlAs (gallium aluminum arsenide), InP (phosphide).
  • the switch portion 1324 may be formed using a power transistor including indium (indium), SiC (silicon carbide), ZnSe (zinc selenide), GaN (gallium nitride), GaOx (gallium oxide; x is a real number greater than 0), or the like.
  • the first batteries 1301a and 1301b mainly supply power to 42V system (high voltage system) on-board equipment, and the second battery 1311 supplies power to 14V system (low voltage system) onboard equipment.
  • the second battery 1311 a lead-acid battery is often used because it is advantageous in terms of cost.
  • the second battery 1311 may be a lead-acid battery, an all-solid-state battery, or an electric double layer capacitor.
  • regenerated energy from the rotation of the tires 1316 is sent to the motor 1304 via the gear 1305, and charged to the second battery 1311 from the motor controller 1303 or the battery controller 1302 via the control circuit section 1321.
  • the first battery 1301a is charged from the battery controller 1302 via the control circuit section 1320.
  • the first battery 1301b is charged from the battery controller 1302 via the control circuit unit 1320. In order to efficiently charge the regenerated energy, it is desirable that the first batteries 1301a and 1301b can be rapidly charged.
  • the battery controller 1302 can set the charging voltage, charging current, etc. of the first batteries 1301a and 1301b.
  • the battery controller 1302 can set charging conditions according to the charging characteristics of the secondary battery to be used and perform rapid charging.
  • the outlet of the charger or the connection cable of the charger is electrically connected to the battery controller 1302.
  • Power supplied from an external charger charges the first batteries 1301a and 1301b via the battery controller 1302.
  • a control circuit is provided and the function of the battery controller 1302 is not used in some cases, but in order to prevent overcharging, the first batteries 1301a and 1301b are charged via the control circuit section 1320. It is preferable.
  • the connecting cable or the connecting cable of the charger is provided with a control circuit.
  • the control circuit section 1320 is sometimes called an ECU (Electronic Control Unit).
  • the ECU is connected to a CAN (Controller Area Network) provided in the electric vehicle.
  • CAN is one of the serial communication standards used as an in-vehicle LAN.
  • the ECU includes a microcomputer. Further, the ECU uses a CPU or a GPU.
  • External chargers installed at charging stations etc. include 100V outlet-200V outlet, or 3-phase 200V and 50kW. It is also possible to charge the battery by receiving power from an external charging facility using a non-contact power supply method or the like.
  • the capacity decrease is suppressed even when the electrode layer is made thicker and the loading amount is increased, and the synergistic effect of maintaining high capacity has resulted in a secondary battery with significantly improved electrical characteristics.
  • It is particularly effective for secondary batteries used in vehicles, and provides a vehicle with a long cruising range, specifically a cruising range of 500 km or more on one charge, without increasing the weight ratio of the secondary battery to the total vehicle weight. be able to.
  • the secondary battery of this embodiment described above can have a high operating voltage by using the positive electrode active material 101 described in Embodiment 1, and can be used as the charging voltage increases. Capacity can be increased. Further, by using the positive electrode active material 101 described in Embodiment 1 for the positive electrode, a secondary battery for a vehicle with excellent safety can be provided.
  • next-generation clean energy such as a hybrid vehicle (HV), electric vehicle (EV), or plug-in hybrid vehicle (PHV) can be realized.
  • HV hybrid vehicle
  • EV electric vehicle
  • PSV plug-in hybrid vehicle
  • a car can be realized.
  • secondary batteries in agricultural machinery, motorized bicycles including electric assist bicycles, motorcycles, electric wheelchairs, electric carts, ships, submarines, aircraft, rockets, artificial satellites, space probes, planetary probes, or spacecraft. It can also be installed.
  • the secondary battery of one embodiment of the present invention can be a high capacity secondary battery. Therefore, the secondary battery of one embodiment of the present invention is suitable for reduction in size and weight, and can be suitably used for transportation vehicles.
  • a car 2001 shown in FIG. 18A is an electric car that uses an electric motor as a power source for driving. Alternatively, it is a hybrid vehicle that can appropriately select and use an electric motor and an engine as a power source for driving.
  • a secondary battery is mounted on a vehicle, the example of the secondary battery shown in Embodiment 5 is installed at one or multiple locations.
  • a car 2001 shown in FIG. 18A includes a battery pack 2200, and the battery pack includes a secondary battery module to which a plurality of secondary batteries are connected. Furthermore, it is preferable to include a charging control device electrically connected to the secondary battery module.
  • the automobile 2001 can be charged by receiving power from an external charging facility using a plug-in method, a non-contact power supply method, or the like to a secondary battery of the automobile 2001.
  • a predetermined charging method or connector standard such as CHAdeMO (registered trademark) or combo may be used as appropriate.
  • the charging equipment may be a charging station provided at a commercial facility or may be a home power source.
  • plug-in technology it is possible to charge the power storage device mounted on the vehicle 2001 by supplying power from the outside. Charging can be performed by converting AC power into DC power via a conversion device such as an ACDC converter.
  • a power receiving device can be mounted on a vehicle, and power can be supplied from a ground power transmitting device in a non-contact manner for charging.
  • this non-contact power supply method by incorporating a power transmission device into the road or outside wall, charging can be performed not only while the vehicle is stopped but also while the vehicle is running. Further, electric power may be transmitted and received between two vehicles using this contactless power supply method.
  • a solar cell may be provided on the exterior of the vehicle, and the secondary battery may be charged when the vehicle is stopped or traveling.
  • an electromagnetic induction method or a magnetic resonance method can be used.
  • FIG. 18B shows a large transport vehicle 2002 having an electrically controlled motor as an example of a transport vehicle.
  • the secondary battery module of the transport vehicle 2002 has a maximum voltage of 170V, for example, in which four secondary batteries with a nominal voltage of 3.0 V or more and 5.0 V or less are connected in series, and 48 cells are connected in series. Except for the difference in the number of secondary batteries constituting the secondary battery module of the battery pack 2201, etc., it has the same functions as those in FIG. 18A, so a description thereof will be omitted.
  • FIG. 18C shows, as an example, a large transport vehicle 2003 with an electrically controlled motor.
  • the secondary battery module of the transportation vehicle 2003 has a maximum voltage of 600 V, for example, by connecting in series one hundred or more secondary batteries with a nominal voltage of 3.0 V or more and 5.0 V or less. Therefore, a secondary battery with small variations in characteristics is required.
  • a secondary battery in which the positive electrode active material 101 described in Embodiments 1 to 3 is used as a positive electrode a secondary battery having stable battery characteristics can be manufactured, and from the viewpoint of yield, it can be manufactured in large quantities at low cost. Production is possible. Further, except for the difference in the number of secondary batteries constituting the secondary battery module of the battery pack 2202, etc., it has the same functions as those in FIG. 17A, so a description thereof will be omitted.
  • FIG. 18D shows an example aircraft 2004 with an engine that burns fuel. Since the aircraft 2004 shown in FIG. 18D has wheels for takeoff and landing, it can be said to be part of a transportation vehicle, and a secondary battery module is configured by connecting a plurality of secondary batteries, and the aircraft 2004 is connected to a secondary battery module and charged.
  • the battery pack 2203 includes a control device.
  • the secondary battery module of the aircraft 2004 has a maximum voltage of 32V, for example, by connecting eight 4V secondary batteries in series. Except for the difference in the number of secondary batteries constituting the secondary battery module of the battery pack 2203, etc., it has the same functions as those in FIG. 18A, so a description thereof will be omitted.
  • FIG. 18E shows an artificial satellite 2005 equipped with a secondary battery 2204 as an example. Since the artificial satellite 2005 is used in outer space, it is desired that there be no failure due to ignition, and it is preferable to include the secondary battery 2204, which is an aspect of the present invention and has excellent safety. Furthermore, it is more preferable that the secondary battery 2204 is mounted inside the artificial satellite 2005 while being covered with a heat insulating member.
  • FIG. 19A is an example of an electric bicycle using the power storage device of one embodiment of the present invention.
  • the power storage device of one embodiment of the present invention can be applied to an electric bicycle 8700 illustrated in FIG. 19A.
  • a power storage device according to one embodiment of the present invention includes, for example, a plurality of storage batteries and a protection circuit.
  • the electric bicycle 8700 includes a power storage device 8702.
  • the power storage device 8702 can supply electricity to a motor that assists the driver. Further, the power storage device 8702 is portable, and FIG. 19B shows a state in which it has been removed from the bicycle. Further, the power storage device 8702 includes a plurality of built-in storage batteries 8701 included in the power storage device of one embodiment of the present invention, and can display the remaining battery level and the like on a display portion 8703.
  • Power storage device 8702 also includes a control circuit 8704 that can control charging or detect abnormality of a secondary battery, an example of which is shown in Embodiment 6. The control circuit 8704 is electrically connected to the positive and negative electrodes of the storage battery 8701.
  • the positive electrode active material 101 obtained in Embodiment 1 with a secondary battery using the positive electrode as the positive electrode, a synergistic effect regarding safety can be obtained.
  • the secondary battery and control circuit 8704 using the positive electrode active material 101 obtained in Embodiment 1 as a positive electrode are highly safe and can greatly contribute to eradicating accidents such as fires caused by secondary batteries.
  • FIG. 19C is an example of a two-wheeled vehicle using the power storage device of one embodiment of the present invention.
  • a scooter 8600 shown in FIG. 19C includes a power storage device 8602, a side mirror 8601, and a direction indicator light 8603.
  • the power storage device 8602 can supply electricity to the direction indicator light 8603.
  • the power storage device 8602 that houses a plurality of secondary batteries using the positive electrode active material 101 obtained in Embodiment 1 as a positive electrode can have a high capacity and can contribute to miniaturization.
  • the scooter 8600 shown in FIG. 19C can store a power storage device 8602 in an under-seat storage 8604.
  • the power storage device 8602 can be stored in the under-seat storage 8604 even if the under-seat storage 8604 is small.
  • a secondary battery which is one embodiment of the present invention, is mounted in an electronic device
  • electronic devices incorporating secondary batteries include television devices (also called televisions or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (mobile phones, Examples include mobile phone devices (also referred to as mobile phone devices), portable game machines, personal digital assistants, audio playback devices, and large game machines such as pachinko machines.
  • portable information terminals include notebook personal computers, tablet terminals, electronic book terminals, and mobile phones.
  • FIG. 20A shows an example of a mobile phone.
  • the mobile phone 2100 includes a display section 2102 built into a housing 2101, as well as operation buttons 2103, an external connection port 2104, a speaker 2105, a microphone 2106, and the like.
  • the mobile phone 2100 includes a secondary battery 2107.
  • a secondary battery 2107 in which the positive electrode active material 101 described in Embodiment 1 is used as a positive electrode, a high capacity can be achieved, and a configuration can be realized that can accommodate space saving due to downsizing of the housing. Can be done.
  • the mobile phone 2100 can execute various applications such as mobile phone calls, e-mail, text viewing and creation, music playback, Internet communication, computer games, etc.
  • the operation button 2103 can have various functions such as turning on and off the power, turning on and off wireless communication, executing and canceling silent mode, and executing and canceling power saving mode.
  • the functions of the operation buttons 2103 can be freely set using the operating system built into the mobile phone 2100.
  • the mobile phone 2100 is capable of performing short-range wireless communication according to communication standards. For example, by communicating with a headset capable of wireless communication, it is also possible to make hands-free calls.
  • the mobile phone 2100 is equipped with an external connection port 2104, and can directly exchange data with other information terminals via a connector. Charging can also be performed via the external connection port 2104. Note that the charging operation may be performed by wireless power supply without using the external connection port 2104.
  • the mobile phone 2100 has a sensor.
  • a human body sensor such as a fingerprint sensor, a pulse sensor, a body temperature sensor, a touch sensor, a pressure sensor, an acceleration sensor, or the like.
  • the mobile phone 2100 may be configured to include an external battery 2150.
  • External battery 2150 has a secondary battery and a plurality of terminals 2151.
  • the external battery 2150 can charge a mobile phone 2100 or the like via a cable 2152 or the like.
  • the positive electrode active material of one embodiment of the present invention for a secondary battery included in the external battery 2150, the external battery 2150 can have high performance.
  • the capacity of the secondary battery 2107 included in the main body of the mobile phone 2100 is small, it can be used for a long time by charging from the external battery 2150. Therefore, it is possible to make the main body of the mobile phone 2100 smaller and/or lighter, and to improve safety.
  • the product may include only the external battery 2150.
  • the external battery 2150 can charge various types of portable information terminals in addition to the mobile phone 2100.
  • FIG. 20B is an unmanned aircraft 2300 with multiple rotors 2302.
  • Unmanned aerial vehicle 2300 is sometimes called a drone.
  • Unmanned aircraft 2300 includes a secondary battery 2301, which is one embodiment of the present invention, a camera 2303, and an antenna (not shown).
  • Unmanned aerial vehicle 2300 can be remotely controlled via an antenna.
  • a secondary battery using the positive electrode active material 101 obtained in Embodiment 1 as a positive electrode has a high energy density and is highly safe, so it can be used safely for a long time and is suitable for use in the unmanned aerial vehicle 2300. It is suitable as a secondary battery to be mounted.
  • FIG. 20C shows an example of a robot.
  • the robot 6400 shown in FIG. 20C includes a secondary battery 6409, an illuminance sensor 6401, a microphone 6402, an upper camera 6403, a speaker 6404, a display section 6405, a lower camera 6406, an obstacle sensor 6407, a movement mechanism 6408, a calculation device, and the like.
  • the microphone 6402 has a function of detecting the user's speaking voice, environmental sounds, and the like. Furthermore, the speaker 6404 has a function of emitting sound.
  • the robot 6400 can communicate with a user using a microphone 6402 and a speaker 6404.
  • the display unit 6405 has a function of displaying various information.
  • the robot 6400 can display information desired by the user on the display section 6405.
  • the display unit 6405 may include a touch panel. Further, the display unit 6405 may be a removable information terminal, and by installing it at a fixed position on the robot 6400, charging and data exchange are possible.
  • the upper camera 6403 and the lower camera 6406 have a function of capturing images around the robot 6400. Further, the obstacle sensor 6407 can detect the presence or absence of an obstacle in the direction of movement of the robot 6400 when the robot 6400 moves forward using the moving mechanism 6408.
  • the robot 6400 uses an upper camera 6403, a lower camera 6406, and an obstacle sensor 6407 to recognize the surrounding environment and can move safely.
  • the robot 6400 includes a secondary battery 6409 according to one embodiment of the present invention and a semiconductor device or electronic component in its internal area.
  • a secondary battery using the cathode active material 101 obtained in Embodiment 1 as a cathode has high energy density and is highly safe, so it can be used safely for a long time and can be mounted on the robot 6400. It is suitable as the secondary battery 6409.
  • FIG. 20D shows an example of a cleaning robot.
  • the cleaning robot 6300 includes a display portion 6302 placed on the top surface of a housing 6301, a plurality of cameras 6303 placed on the side, a brush 6304, an operation button 6305, a secondary battery 6306, various sensors, and the like.
  • the cleaning robot 6300 is equipped with tires, a suction port, and the like.
  • the cleaning robot 6300 is self-propelled, detects dirt 6310, and can suck the dirt from a suction port provided on the bottom surface.
  • the cleaning robot 6300 can analyze the image taken by the camera 6303 and determine the presence or absence of obstacles such as walls, furniture, or steps. Furthermore, if an object such as wiring that is likely to become entangled with the brush 6304 is detected through image analysis, the rotation of the brush 6304 can be stopped.
  • the cleaning robot 6300 includes a secondary battery 6306 according to one embodiment of the present invention and a semiconductor device or an electronic component in its internal area.
  • a secondary battery using the positive electrode active material 101 obtained in Embodiment 1 as a positive electrode has a high energy density and is highly safe, so it can be used safely for a long time and is suitable for the cleaning robot 6300. This is suitable as the secondary battery 6306 to be mounted.
  • FIG. 21 is a graph of the internal temperature of the secondary battery (hereinafter simply referred to as temperature) versus time, and shows that as the temperature rises, thermal runaway occurs through several states.
  • the negative electrode decomposes, and finally (7) the positive electrode and negative electrode come into direct contact.
  • the secondary battery reaches thermal runaway after going through the above-mentioned state (5), (6), or (7).
  • thermal runaway it is necessary to suppress the temperature rise of the secondary battery, and to maintain a stable state at high temperatures of the negative electrode, positive electrode and/or electrolyte exceeding 100°C. It will be done.
  • the positive electrode active material 101 which is one embodiment of the present invention, has a stable crystal structure and has the effect of suppressing oxygen desorption. Therefore, it is thought that the secondary battery using the positive electrode active material 101 does not reach at least the state after the above (5), and the temperature rise of the secondary battery is suppressed, and has the remarkable effect of being less likely to cause thermal runaway.
  • the nail penetration test is a test in which a nail 1003 satisfying a predetermined diameter selected from 2 mm or more and 10 mm or less is inserted into the secondary battery 500 at a predetermined speed selected from 1 mm/s or more and 20 mm/s or less. be. In this embodiment and the examples described below, the secondary battery 500 is fully charged (States of Charge: SOC 100%).
  • FIG. 22A shows a cross-sectional view of the secondary battery 500 with a nail 1003 inserted therein.
  • the secondary battery 500 has a structure in which a positive electrode 503, a separator 507, a negative electrode 506, and an electrolyte 530 are housed in an exterior body 531.
  • the positive electrode 503 has a positive electrode current collector 501 and a positive electrode active material layer 502 formed on both sides thereof, and the negative electrode 506 has a negative electrode current collector 504 and a negative electrode active material layer 505 formed on one or both sides thereof.
  • FIG. 22B shows an enlarged view of the nail 1003 and the positive electrode current collector 501, and clearly shows the positive electrode active material 101, which is one embodiment of the present invention, and the conductive material 553, which the positive electrode active material layer 502 has.
  • FIG. 22C shows an enlarged view of the positive electrode active material 101.
  • the positive electrode active material 101 has the characteristics as described in the above embodiment.
  • FIG. 23 is a partially revised graph based on the graph shown on page 70 [FIG. 2-12] of Non-Patent Document 4, and is a graph of the temperature of the secondary battery against time, and is a graph of the temperature of the secondary battery with respect to time.
  • the transition metal M is reduced by the electrons rapidly flowing into the positive electrode active material (for example, cobalt changes from Co 4+ to Co 2+ ), and a reaction occurs in which oxygen is released from the positive electrode active material. There is. Since this reaction is exothermic, positive feedback is applied to thermal runaway. That is, if this reaction can be suppressed, a positive electrode active material that is less likely to undergo thermal runaway can be obtained.
  • the surface layer portion of the positive electrode active material which tends to become a site for the above-mentioned reaction, has a crystal structure that makes it difficult to release oxygen.
  • the concentration of a metal that is difficult to release oxygen is high. If oxygen is difficult to be released from the positive electrode active material, the above-mentioned reduction reaction (for example, the reaction from Co 4+ to Co 2+ ) is also suppressed.
  • the metal that does not easily release oxygen is a metal that forms a stable metal oxide, such as magnesium and aluminum. Nickel is also considered to have the effect of suppressing oxygen release when present at the lithium site. It is also thought to have the effect of suppressing thermite reaction between the aluminum foil used for the positive electrode current collector and the positive electrode active material.
  • the positive electrode active material 101 When a nail penetration test was performed on a secondary battery using the positive electrode active material 101 which is one embodiment of the present invention, it was found that the positive electrode active material 101 had the unique effect of suppressing oxygen release because it had the above-mentioned barrier film. It is thought that the oxidation reaction of the electrolytic solution is suppressed and heat generation is also suppressed. Further, according to the positive electrode active material 101, since the barrier film in the surface layer has characteristics similar to an insulator, it is thought that the speed of current flowing into the positive electrode at the time of an internal short circuit becomes slow. It is expected that this will have the remarkable effect of making it difficult for thermal runaway to occur and for fires to occur.
  • the transition metal M such as cobalt
  • the transition metal M such as cobalt
  • positive electrode active materials with and without additive elements were prepared, and their safety was evaluated.
  • Nickel sulfate, cobalt sulfate, and manganese sulfate were prepared as the nickel source, cobalt source, and manganese source in step S111 of FIG. 6A, and first glycine was prepared as the chelating agent S113. In step S114, these were mixed with water to obtain an acid solution. In the acid solution, the combined concentration of cobalt sulfate, nickel sulfate, and manganese sulfate was 2 mol/L, and the concentration of the first glycine was 0.100 mol/L.
  • sodium hydroxide dissolved in pure water sodium hydroxide aqueous solution
  • concentration of sodium hydroxide was adjusted to 5 mol/L.
  • the water shown in S122 of FIG. 6A was an aqueous solution containing the second glycine. This was adjusted so that the second glycine concentration was 0.100 mol/L.
  • the aqueous solution containing the second glycine is also referred to as a filling solution.
  • a baffle plate is installed in the reaction container of the coprecipitation device, the charging solution is filled, the stirring is done with a stirrer at a rotation speed of 1000 rpm, the temperature is adjusted to maintain 50°C and the pH is 11.0, and the reaction container is heated. Nitrogen was supplied from the top at a rate of 1 L/min, and preparations were made to drop an aqueous sodium hydroxide solution to maintain the above pH. The rate of addition of the acid solution was 0.10 mL/min. Co-precipitation reaction proceeded in the reaction vessel. After the dropwise addition was completed, the liquid temperature was maintained at 25°C. OptiMax (manufactured by Mettler Toledo) was used as a coprecipitation device (step S131).
  • step S132 in FIG. 6A the suspension produced by the coprecipitation reaction was suction-filtered with pure water, and then suction-filtered with acetone to obtain a precipitate. Thereafter, according to step S133, the precipitate was dried in a vacuum drying oven at 200° C. for 12 hours to obtain composite hydroxide 98.
  • the composite hydroxide 98 may be called a precursor.
  • lithium hydroxide was prepared as a lithium source in S141 of FIG.
  • Lithium hydroxide was crushed in a fluidized bed jet mill at 10,000 rpm for 50 minutes or more.
  • no additional element source was mixed in S141.
  • step S142 the molar ratio of lithium hydroxide to the precursor (hereinafter referred to as Li/Co or Li/(Ni+Co+Mn)) was adjusted and mixed to be 1.01. Mixing was performed three times at 1500 rpm using an autorotating/revolving mixer.
  • step S143 in FIG. 7 the mixture obtained above was heated.
  • the heating conditions in step S143 were 700° C. for 10 hours.
  • a roller hearth kiln simulator furnace manufactured by Noritake Company
  • oxygen was flowed at a flow rate of 10 L/min.
  • step S144 was heated again in step S145.
  • the heating conditions in step S145 were the same as in step S143, except that the heating conditions were 800° C. for 10 hours.
  • the composite oxide 99 can function as a positive electrode active material even at this stage. Further, the atomic ratio of the positive electrode active material obtained through such a process may not be equal to the molar ratio adjusted at the time of weighing the raw materials.
  • An additive element source was prepared as step S151 in FIG.
  • calcium carbonate was used as the additive element source.
  • Calcium carbonate was adjusted to be 1 mol% of composite oxide 99 and mixed (step S152).
  • step S153 in FIG. 7 the mixture obtained above was heated.
  • the heating conditions in step S153 were the same as in step S143, except that the heating conditions were 800° C. for 2 hours. Thereafter, it was cooled to room temperature and crushed in step S154 to obtain the positive electrode active material 101 (step S175). This was designated as sample 1.
  • Sample 2 was prepared in the same manner as Sample 1, except that the steps after step S151 were not performed and no additional elements were added.
  • Table 3 shows an excerpt of the manufacturing conditions for Sample 1 and Sample 2.
  • the above sample 1 or sample 2 was prepared as a positive electrode active material, acetylene black (AB) was prepared as a conductive material, and polyvinylidene fluoride (PVDF) was prepared as a binder. PVDF was prepared in advance by dissolving it in N-methyl-2-pyrrolidone (NMP) at a weight ratio of 5%. Next, a positive electrode active material: AB:PVDF was mixed at a ratio of 95:3:2 (weight ratio) to prepare a slurry, and the slurry was applied to a positive electrode current collector. Aluminum foil (both mirror surfaces) with a thickness of 20 ⁇ m was used as the positive electrode current collector. NMP was used as a solvent for the slurry. After applying the slurry to the positive electrode current collector, the solvent was evaporated.
  • NMP N-methyl-2-pyrrolidone
  • pressing treatment was performed using a roll press machine.
  • the conditions for the press treatment were a linear pressure of 210 kN/m.
  • both the upper roll and lower roll of the roll press machine were set to 120 degreeC.
  • Graphite was prepared as a negative electrode active material.
  • CMC and SBR were prepared as binders.
  • Carbon fiber manufactured by Showa Denko K.K., VGCF (registered trademark)
  • VGCF registered trademark
  • a porous polypropylene film with a thickness of 25 ⁇ m was used as the separator.
  • An aluminum laminate film in which nylon, aluminum, and polypropylene were laminated was used for the exterior body.
  • Table 4 shows the manufacturing conditions for the secondary battery manufactured using the above materials.
  • Initial charging and discharging were performed for these secondary batteries. Initial charging and discharging is sometimes called aging or conditioning.
  • a nail penetration test was conducted on the cell containing Sample 1 or Sample 2.
  • the nail penetration tester used was Advanced Safety Tester manufactured by ESPEC Co., Ltd. A nail with a diameter of 3 mm was used. The speed of the nail piercing operation was 1 mm/s. The amount of nail penetration was set to the cell thickness plus 6 mm. Regarding other points, the nail penetration test was conducted in accordance with the description of SAE J2464 "Safety and abuse test for electric/hybrid vehicle power storage system".
  • FIG. 24A is a photograph showing a nail penetration test of a secondary battery having Sample 1
  • FIG. 24B is a photograph showing a state of a nail penetration test of a secondary battery having Sample 2. No ignition was observed in either case.
  • FIG. 25A is a graph showing voltage changes of a secondary battery having Sample 1 or Sample 2 in a nail penetration test.
  • Sample 1 containing the additive element the voltage suddenly decreased immediately after the nail was inserted, returned to 3.5 V or higher, and then slowly decreased again.
  • Sample 2 which did not contain any additive elements, the voltage suddenly decreased immediately after the nail was inserted, and although the voltage returned soon after, it did not recover to 2.5V or higher.
  • FIG. 25B is a graph showing the temperature change of the secondary battery having Sample 1 or Sample 2 in the nail penetration test.
  • the temperature increase was 15° C. or less.
  • the temperature rise was 30° C. or more.

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Abstract

The present invention provides a novel positive electrode active material. The present invention also provides a highly safe secondary battery. This lithium ion secondary battery has a positive electrode, wherein the positive electrode has a positive electrode active material, the positive electrode active material having nickel, cobalt, manganese, oxygen, and additive elements. The additive elements are at least one or two or more selected from fluorine, aluminum, magnesium, titanium, and calcium. The positive electrode active material comprises a layer having a large amount of additive elements, and an interior, wherein the layer having a large amount of additive elements has at least one selected from among additive elements the amount of which is larger than in the interior.

Description

二次電池、および正極活物質の作製方法Secondary battery and method for producing positive electrode active material
　本発明の一様態は、物、方法、又は、製造方法に関する。または、本発明は、プロセス、マシン、マニュファクチャ、又は、組成物（コンポジション・オブ・マター）に関する。本発明の一態様は、二次電池を含む蓄電装置、半導体装置、表示装置、発光装置、照明装置、電子機器またはそれらの製造方法に関する。 One embodiment of the present invention relates to a product, a method, or a manufacturing method. Alternatively, the invention relates to a process, machine, manufacture, or composition of matter. One embodiment of the present invention relates to a power storage device including a secondary battery, a semiconductor device, a display device, a light emitting device, a lighting device, an electronic device, or a manufacturing method thereof.
　なお、本明細書中において電子機器とは、蓄電装置を有する装置全般を指し、蓄電装置を有する電気光学装置、蓄電装置を有する情報端末装置などは全て電子機器である。 Note that in this specification, electronic equipment refers to all devices that have a power storage device, and an electro-optical device that has a power storage device, an information terminal device that has a power storage device, etc. are all electronic devices.
　近年、リチウムイオン二次電池、リチウムイオンキャパシタ、空気電池、全固体電池等、種々の蓄電装置の開発が盛んに行われている。特に高出力、高容量であるリチウムイオン二次電池は半導体産業の発展と併せて急速にその需要が拡大し、充電可能なエネルギーの供給源として現代の情報化社会に不可欠なものとなっている。 In recent years, various power storage devices, such as lithium ion secondary batteries, lithium ion capacitors, air batteries, and all-solid-state batteries, have been actively developed. In particular, demand for high-output, high-capacity lithium-ion secondary batteries is rapidly expanding along with the development of the semiconductor industry, and they have become indispensable in today's information society as a source of rechargeable energy. .
　なかでもモバイル電子機器向け二次電池等では、重量あたりの放電容量が大きく、サイクル特性に優れた二次電池の需要が高い。これらの需要に応えるため、二次電池の正極が有する正極活物質の改良が盛んに行われている（たとえば特許文献１）。 Among them, there is a high demand for secondary batteries for mobile electronic devices, etc., which have a large discharge capacity per weight and excellent cycle characteristics. In order to meet these demands, improvements in positive electrode active materials included in positive electrodes of secondary batteries are actively being carried out (for example, Patent Document 1).
　また蛍石（フッ化カルシウム）等のフッ化物は古くから製鉄などにおいて融剤として用いられており、物性の研究がされてきた（非特許文献１乃至非特許文献３）。たとえば非特許文献２には、フッ化ニッケルの物性に関する記載が、非特許文献３にはフッ化アルミニウムの物性に関する記載がある。 Furthermore, fluorides such as fluorite (calcium fluoride) have been used as fluxing agents in iron manufacturing and the like for a long time, and their physical properties have been studied (Non-Patent Documents 1 to 3). For example, Non-Patent Document 2 has a description regarding the physical properties of nickel fluoride, and Non-Patent Document 3 has a description regarding the physical properties of aluminum fluoride.
　またリチウムイオン二次電池は、温度が上昇するといくつかの状態を経て熱暴走に至ることが知られている（非特許文献４）。 It is also known that lithium ion secondary batteries go through several states and reach thermal runaway when the temperature rises (Non-Patent Document 4).
特開２０２０−０６８２１０号公報JP2020-068210A
　本発明の一態様は、劣化しにくい正極活物質およびその作製方法を提供することを課題の一とする。または、新規な正極活物質およびその作製方法を提供することを課題の一とする。または、安全性または信頼性の高い二次電池およびその作製方法を提供することを課題の一とする。または、劣化しにくい二次電池およびその作製方法を提供することを課題の一とする。または、長寿命の二次電池およびその作製方法を提供することを課題の一とする。または、新規な二次電池およびその作製方法を提供することを課題の一とする。 An object of one embodiment of the present invention is to provide a positive electrode active material that does not easily deteriorate and a method for manufacturing the same. Another object of the present invention is to provide a novel positive electrode active material and a method for producing the same. Another object of the present invention is to provide a highly safe or reliable secondary battery and a method for producing the same. Another object of the present invention is to provide a secondary battery that does not easily deteriorate and a method for manufacturing the same. Another object of the present invention is to provide a long-life secondary battery and a method for manufacturing the same. Another object of the present invention is to provide a novel secondary battery and a method for manufacturing the same.
　なお、これらの課題の記載は、他の課題の存在を妨げるものではない。なお、本発明の一態様は、これらの課題の全てを解決する必要はないものとする。なお、明細書、図面、請求項の記載から、これら以外の課題を抽出することが可能である。 Note that the description of these issues does not preclude the existence of other issues. Note that one embodiment of the present invention does not need to solve all of these problems. Note that problems other than these can be extracted from the description, drawings, and claims.
　正極活物質にＬｉＡＮｉＸＣｏＹＭｎＺＯ２（０．８９≦Ａ≦１．０７、Ｘ＋Ｙ＋Ｚ＝１）で表される、いわゆるＮＣＭを用いたリチウムイオン二次電池が販売されている。Ｎｉ：Ｃｏ：Ｍｎ＝１：１：１のように遷移金属Ｍ（Ｍは遷移金属を表し、本明細書等において特に言及がない限り、Ｍはニッケル、コバルトおよび／またはマンガンとする。またこれらの和を表す。）を同程度に含む材料はコバルトを多く含むため、高コスト化につながりやすい。コバルトの使用量を少なくし、ニッケルの使用量を多くすることで電池の高容量化が試みられている。 Lithium ion secondary batteries using so-called NCM represented by Li A Ni X Co Y Mn Z O 2 (0.89≦A≦1.07, X+Y+Z=1) as a positive electrode active material are on sale. Transition metal M (M represents a transition metal, and unless otherwise mentioned in this specification, M is nickel, cobalt, and/or manganese, such as Ni:Co:Mn=1:1:1. ) to the same extent contains a large amount of cobalt, which tends to lead to higher costs. Attempts are being made to increase the capacity of batteries by using less cobalt and more nickel.
　ニッケルの使用量を多くしたＮＣＭは、特に高温において酸素が脱離しやすく劣化が生じやすいという問題がある。また、充放電の際にリチウムイオンが挿入または脱離するためのリチウムサイトにニッケル、マンガンで代表される遷移金属Ｍが入り込んでしまうという問題もある。 NCM in which a large amount of nickel is used has a problem in that oxygen is easily desorbed, especially at high temperatures, and deterioration is likely to occur. There is also the problem that transition metals M, typified by nickel and manganese, enter lithium sites where lithium ions are inserted or desorbed during charging and discharging.
　ＮＣＭは複数の一次粒子が凝集して二次粒子を構成している場合がある。この場合、充電または放電によるリチウムイオンの挿入または脱離が生じる際に、ＮＣＭの一次粒子の結晶のａ軸長および／またはｃ軸長が変化し、体積が膨張または収縮するため、一次粒子間の空隙が大きくなる。これにより二次粒子にはひび割れ、または微細化が生じる。なお、ここでいう一次粒子間の空隙とは必ずしも空間を意味しない。電解液を有する二次電池とした場合には空隙の位置には電解液が存在しうる。全固体電池とする場合は、空間である。 In NCM, a plurality of primary particles may aggregate to form secondary particles. In this case, when intercalation or desorption of lithium ions occurs due to charging or discharging, the a-axis length and/or c-axis length of the crystals of the primary particles of NCM changes, and the volume expands or contracts. The air gap becomes larger. This causes cracks or refinement of the secondary particles. Note that the voids between the primary particles herein do not necessarily mean spaces. In the case of a secondary battery having an electrolyte, the electrolyte may be present in the gap. In the case of an all-solid-state battery, it is a space.
　ＮＣＭの二次粒子にひび割れ、または微細化が生じると、正極において電子伝導が確保されない部分が増加して内部抵抗が増加し、二次電池の寿命特性が低下する。 When cracks or miniaturization occur in the secondary particles of NCM, the portion of the positive electrode where electron conduction is not ensured increases, internal resistance increases, and the life characteristics of the secondary battery deteriorate.
　そこで、上記複数の課題の少なくとも一つを解決するため、ＮＣＭに添加元素、たとえばフッ素、アルミニウム、マグネシウム、チタン、カルシウムから選ばれる一または二以上を添加することとする。これによりＮＣＭの劣化を抑制し、二次電池の寿命特性を向上させる。マグネシウムは、添加前の複合酸化物の組成を考慮して、実施者が適宜、所望の量が含有されるように複合酸化物の遷移金属Ｍ（ニッケル、コバルトおよびマンガンの和）に対して０．５原子％以上３原子％以下の範囲で秤量して添加することが望ましい。 Therefore, in order to solve at least one of the above-mentioned problems, an additive element such as one or more selected from fluorine, aluminum, magnesium, titanium, and calcium is added to NCM. This suppresses deterioration of the NCM and improves the life characteristics of the secondary battery. Considering the composition of the composite oxide before addition, magnesium can be added to zero relative to the transition metal M (sum of nickel, cobalt, and manganese) in the composite oxide so that the desired amount is contained by the practitioner. It is desirable to add it by weighing in the range of .5 atomic % or more and 3 atomic % or less.
　二次粒子は、複数の一次粒子の凝集体であり、二次粒子内の一次粒子間には隙間がある場合がある。また、一次粒子は多結晶または単結晶を含む。複数の一次粒子が凝集して構成された二次粒子の外表面のみでなく、内部の空隙、一次粒子間の結合が不完全な部分でも二次電池を製造した場合には電解液との接触が生じる。従って、電解液と接触する領域ではリチウムの挿入及び脱離が可能となり、容量特性が向上するメリットがある。その一方、電解液と接触する領域が不安定であれば、その部分の劣化が促進されるというサイクル特性が低下するデメリットもある恐れがある。 A secondary particle is an aggregate of multiple primary particles, and there may be gaps between the primary particles within the secondary particle. Moreover, primary particles include polycrystals or single crystals. When manufacturing a secondary battery, not only the outer surface of the secondary particles, which are composed of agglomerated primary particles, but also the internal voids and areas where the bonds between the primary particles are incomplete, may come into contact with the electrolyte. occurs. Therefore, insertion and desorption of lithium becomes possible in the region in contact with the electrolytic solution, which has the advantage of improving capacity characteristics. On the other hand, if the region that comes into contact with the electrolyte is unstable, there is a possibility that deterioration of that region will be accelerated, resulting in a decrease in cycle characteristics.
　本明細書で開示する構成は、共沈法を用いてニッケル、コバルト、及びマンガンを含むニッケル化合物（前駆体とも呼ばれる）を得た後、該ニッケル化合物とリチウム化合物と、を混合した混合物を第１の温度で加熱し、混合物を粉砕または解砕した後、添加元素源を混合し、第１の温度より高い温度である第２の温度で加熱して正極活物質を作製する。 In the configuration disclosed in this specification, a nickel compound (also called a precursor) containing nickel, cobalt, and manganese is obtained using a coprecipitation method, and then a mixture of the nickel compound and a lithium compound is mixed. After heating at a first temperature and pulverizing or crushing the mixture, an additional element source is mixed and heated at a second temperature higher than the first temperature to produce a positive electrode active material.
　より具体的には、反応槽にニッケルの水溶性塩、コバルトの水溶性塩、及びマンガンの水溶性塩の水溶性塩を含む水溶液と、アルカリ溶液と、を供給し、反応槽の内部で混合して少なくともニッケル、コバルト、マンガン、を含む化合物を析出させ、化合物とリチウム化合物とを混合した第１の混合物を第１の加熱温度で加熱し、解砕または粉砕した後、さらに第２の加熱温度で加熱し、解砕または粉砕した第１の混合物と、添加元素源と、を混合して得られた第２の混合物を第３の加熱温度で加熱する正極活物質の作製方法である。 More specifically, an aqueous solution containing a water-soluble salt of nickel, cobalt, and manganese, and an alkaline solution are supplied to the reaction tank, and mixed inside the reaction tank. to precipitate a compound containing at least nickel, cobalt, and manganese, heat the first mixture of the compound and the lithium compound at a first heating temperature, crush or crush it, and then further heat it for a second time. This is a method for producing a positive electrode active material, in which a second mixture obtained by heating a crushed or pulverized first mixture and an additive element source is heated at a third heating temperature.
　本明細書で開示する他の構成は、共沈法を用いてニッケル、コバルト、及びマンガンを含むニッケル化合物（前駆体とも呼ばれる）を得た後、該ニッケル化合物とリチウム化合物と添加元素源と、を混合した混合物を第１の温度で加熱し、混合物を粉砕または解砕して正極活物質を作製する。 Another configuration disclosed in this specification is to obtain a nickel compound (also referred to as a precursor) containing nickel, cobalt, and manganese using a coprecipitation method, and then add the nickel compound, lithium compound, and additional element source; A positive electrode active material is produced by heating the mixture at a first temperature and pulverizing or crushing the mixture.
　より具体的には、反応槽にニッケルの水溶性塩、コバルトの水溶性塩、及びマンガンの水溶性塩の水溶性塩を含む水溶液と、アルカリ溶液と、を供給し、反応槽の内部で混合して少なくともニッケル、コバルト、マンガン、を含む化合物を析出させ、化合物とリチウム化合物と添加元素源とを混合した第１の混合物を第１の加熱温度で加熱し、解砕または粉砕した後、さらに第２の加熱温度で加熱し、解砕または粉砕した第１の混合物と、添加元素源と、を混合して得られた第２の混合物を第３の加熱温度で加熱する正極活物質の作製方法である。 More specifically, an aqueous solution containing a water-soluble salt of nickel, cobalt, and manganese, and an alkaline solution are supplied to the reaction tank, and mixed inside the reaction tank. to precipitate a compound containing at least nickel, cobalt, and manganese, and heat the first mixture of the compound, lithium compound, and additive element source at a first heating temperature to crush or crush the compound, and then further Preparation of a positive electrode active material by heating a second mixture obtained by heating at a second heating temperature and mixing a crushed or pulverized first mixture and an additive element source at a third heating temperature. It's a method.
　第１の温度での加熱により、水分を脱離させた後に、第１の温度よりも高い第２の温度での加熱を行い、合計２回の加熱処理を行うことで混合物の混合状態が改善され、二次電池を作製した場合に二次粒子の中の空隙を少なくすることができる。また、合計２回の加熱処理を行うことで正極活物質の結晶性を向上させることができる。 After removing moisture by heating at the first temperature, heating is performed at a second temperature higher than the first temperature, and the mixing state of the mixture is improved by performing the heat treatment twice in total. Therefore, when a secondary battery is produced, voids in the secondary particles can be reduced. Further, by performing the heat treatment a total of two times, the crystallinity of the positive electrode active material can be improved.
　第１の加熱温度の範囲は４００℃以上７５０℃以下の範囲とする。 The range of the first heating temperature is from 400°C to 750°C.
　第２の加熱温度及び第３の加熱温度の範囲は、７５０℃より高く１０５０℃以下の範囲とする。 The range of the second heating temperature and the third heating temperature is higher than 750°C and lower than 1050°C.
　上記ニッケル化合物を析出させる共沈法は、反応槽にニッケルの水溶性塩、コバルトの水溶性塩、及びマンガンの水溶性塩を含む水溶液と、アルカリ溶液を供給し、反応槽の内部で混合してニッケル化合物（コバルト、マンガン、及びニッケルを含む水酸化物）を析出させる。当該反応は、中和反応、酸塩基反応、または共沈反応と記すことがあり、当該少なくともニッケル、コバルト、マンガンを含む化合物は、コバルトの含有量が多くとも少なくともニッケルコバルトマンガン化合物、またはＮＣＭの前駆体と記すことがある。その後、ニッケル化合物とリチウム化合物とを混合した混合物を得る。 In the coprecipitation method for precipitating the nickel compound, an aqueous solution containing a water-soluble salt of nickel, a water-soluble cobalt salt, and a water-soluble manganese salt and an alkaline solution are supplied to a reaction tank and mixed inside the reaction tank. to precipitate a nickel compound (hydroxide containing cobalt, manganese, and nickel). The reaction may be referred to as a neutralization reaction, an acid-base reaction, or a coprecipitation reaction, and the compound containing at least nickel, cobalt, and manganese is a nickel-cobalt-manganese compound containing at most cobalt, or a nickel-cobalt-manganese compound of NCM. Sometimes referred to as a precursor. Thereafter, a mixture of the nickel compound and the lithium compound is obtained.
　ニッケルの水溶性塩を含む水溶液としては、硫酸ニッケル水溶液または硝酸ニッケル水溶液を用いることができる。 As the aqueous solution containing the water-soluble salt of nickel, a nickel sulfate aqueous solution or a nickel nitrate aqueous solution can be used.
　コバルトの水溶性塩を含む水溶液としては、硫酸コバルト水溶液または硝酸コバルト水溶液を用いることができる。 As the aqueous solution containing a water-soluble salt of cobalt, an aqueous cobalt sulfate solution or an aqueous cobalt nitrate solution can be used.
　マンガンの水溶性塩を含む水溶液としては、硫酸マンガン水溶液または硝酸マンガン水溶液を用いることができる。 As the aqueous solution containing the water-soluble salt of manganese, an aqueous manganese sulfate solution or an aqueous manganese nitrate solution can be used.
　また、反応槽の内部の混合液のｐＨとして、好ましくは９．０以上１２．０以下、より好ましくは１０．０以上１１．５以下にするとよい。 Furthermore, the pH of the mixed solution inside the reaction tank is preferably 9.0 or more and 12.0 or less, more preferably 10.0 or more and 11.5 or less.
　水溶液と、アルカリ溶液とを混合してコバルト化合物を析出させる際に、キレート剤を添加する。キレート剤として、たとえばグリシン、オキシン、１−ニトロソ−２−ナフトール、２−メルカプトベンゾチアゾールまたはＥＤＴＡ（エチレンジアミン四酢酸）が挙げられる。なお、グリシン、オキシン、１−ニトロソ−２−ナフトールまたは２−メルカプトベンゾチアゾールから選ばれた複数種を用いてもよい。なおキレート剤を純水に溶解させ、キレート水溶液として用いる。キレート剤は、キレート化合物を作る錯化剤であり、一般的な錯化剤より好ましい。勿論キレート剤以外の錯化剤を用いてもよく、錯化剤としてアンモニア水を用いることができる。 A chelating agent is added when mixing an aqueous solution and an alkaline solution to precipitate a cobalt compound. Chelating agents include, for example, glycine, oxine, 1-nitroso-2-naphthol, 2-mercaptobenzothiazole or EDTA (ethylenediaminetetraacetic acid). In addition, you may use multiple types selected from glycine, oxine, 1-nitroso-2-naphthol, and 2-mercaptobenzothiazole. Note that the chelating agent is dissolved in pure water and used as a chelate aqueous solution. Chelating agents are complexing agents that create chelate compounds and are preferred over common complexing agents. Of course, a complexing agent other than the chelating agent may be used, and aqueous ammonia can be used as the complexing agent.
　キレート水溶液を用いることで、コバルト化合物を得る際の反応槽の内部に存在する混合液のｐＨが制御しやすくなり好ましい。またキレート水溶液を用いることで結晶の核の不要な発生を抑え、成長を促すことができ好ましい。不要な核の発生が抑制されると微粒子の生成が抑制されるため、粒度分布が良好な複合酸化物を得ることができる。またキレート水溶液を用いることで、酸塩基反応を遅らせることができ、徐々に反応が進むことで球状に近い二次粒子を得ることができる。グリシンは９．０以上１０．０以下およびその付近のｐＨにて、当該ｐＨ値を一定に保つ作用があり、キレート水溶液としてグリシン水溶液を用いることで、上記コバルト化合物を得る際の反応槽のｐＨが制御しやすくなり好ましい。さらにグリシン水溶液のグリシン濃度は、水溶液において、０．０５モル／Ｌ以上０．０９モル／Ｌ以下とするとよい。 It is preferable to use a chelate aqueous solution because it makes it easier to control the pH of the mixed liquid present inside the reaction tank when obtaining the cobalt compound. Further, it is preferable to use a chelate aqueous solution because it can suppress unnecessary generation of crystal nuclei and promote growth. When the generation of unnecessary nuclei is suppressed, the generation of fine particles is suppressed, so that a composite oxide with a good particle size distribution can be obtained. In addition, by using an aqueous chelate solution, the acid-base reaction can be delayed, and the reaction proceeds gradually, making it possible to obtain nearly spherical secondary particles. Glycine has the effect of keeping the pH constant at a pH of 9.0 to 10.0 and around it, and by using a glycine aqueous solution as the chelate aqueous solution, the pH of the reaction tank when obtaining the above cobalt compound can be adjusted. is preferable because it becomes easier to control. Furthermore, the glycine concentration of the glycine aqueous solution is preferably 0.05 mol/L or more and 0.09 mol/L or less in the aqueous solution.
　上記方法で得られる正極活物質は、二次粒子を有し、二次粒子は複数の一次粒子を有する。 The positive electrode active material obtained by the above method has secondary particles, and the secondary particles have a plurality of primary particles.
　上記方法で得られる正極活物質は六方晶の層状構造を有する結晶を有し、結晶は、単結晶（結晶子ともいう）に限らず、多結晶である場合はいくつかの結晶子が集まって一次粒子を形成する。一次粒子とは、ＳＥＭ観察の際に一つの粒と認識される粒子のことを意味する。また、二次粒子とは一次粒子が凝集した塊を指す。一次粒子の凝集には、複数の一次粒子の間に働く結合力は問わない。共有結合、イオン結合、疎水性相互作用、ファンデルワールス力、その他の分子間相互作用のいずれであってもよいし、複数の結合力が働いていてもよい。 The positive electrode active material obtained by the above method has a crystal with a hexagonal layered structure, and the crystal is not limited to a single crystal (also called a crystallite), but in the case of a polycrystal, several crystallites are gathered together. Form primary particles. The term "primary particle" refers to a particle that is recognized as a single particle during SEM observation. In addition, secondary particles refer to aggregates of primary particles. For the aggregation of primary particles, the bonding force acting between a plurality of primary particles does not matter. It may be a covalent bond, an ionic bond, a hydrophobic interaction, a van der Waals force, or any other intermolecular interaction, or a plurality of bonding forces may be at work.
　共沈法を用いる場合には、二次粒子が形成される場合がある。 When using the coprecipitation method, secondary particles may be formed.
　上記六方晶の層状構造を有する結晶は、第１の遷移金属、第２の遷移金属および第３の遷移金属の中から選ばれる一または複数を有する。具体的には、第１の遷移金属はニッケルであり、第２の遷移金属はコバルトであり、第３の遷移金属はマンガンであり、ＬｉＮｉｘＣｏｙＭｎｚＯ２（ｘ＞０、ｙ＞０、ｚ＞０、０．８＜ｘ＋ｙ＋ｚ＜１．２）で表されるＮｉＣｏＭｎ系（ＮＣＭともいう）を用いることができる。具体的には例えば、０．１ｘ＜ｙ＜８ｘかつ０．１ｘ＜ｚ＜８ｘを満たすことが好ましい。一例として、ｘ、ｙおよびｚは、ｘ：ｙ：ｚ＝１：１：１またはその近傍の値を満たすことが好ましい。または一例として、ｘ、ｙおよびｚは、ｘ：ｙ：ｚ＝５：２：３またはその近傍の値を満たすことが好ましい。または一例として、ｘ、ｙおよびｚは、ｘ：ｙ：ｚ＝８：１：１またはその近傍の値を満たすことが好ましい。または一例として、ｘ、ｙおよびｚは、ｘ：ｙ：ｚ＝９：０．５：０．５またはその近傍の値を満たすことが好ましい。または一例として、ｘ、ｙおよびｚは、ｘ：ｙ：ｚ＝６：２：２またはその近傍の値を満たすことが好ましい。または一例として、ｘ、ｙおよびｚは、ｘ：ｙ：ｚ＝１：４：１またはその近傍の値を満たすことが好ましい。 The crystal having a hexagonal layered structure has one or more selected from a first transition metal, a second transition metal, and a third transition metal. Specifically, the first transition metal is nickel, the second transition metal is cobalt, the third transition metal is manganese, and LiNix Co y Mn z O 2 (x>0, y> 0, z>0, 0.8<x+y+z<1.2) NiCoMn system (also referred to as NCM) can be used. Specifically, for example, it is preferable to satisfy 0.1x<y<8x and 0.1x<z<8x. As an example, it is preferable that x, y, and z satisfy x:y:z=1:1:1 or a value in the vicinity thereof. Alternatively, as an example, it is preferable that x, y, and z satisfy x:y:z=5:2:3 or a value in the vicinity thereof. Alternatively, as an example, it is preferable that x, y, and z satisfy x:y:z=8:1:1 or a value in the vicinity thereof. Alternatively, as an example, it is preferable that x, y, and z satisfy x:y:z=9:0.5:0.5 or a value in the vicinity thereof. Alternatively, as an example, it is preferable that x, y, and z satisfy x:y:z=6:2:2 or a value in the vicinity thereof. Alternatively, as an example, it is preferable that x, y, and z satisfy x:y:z=1:4:1 or a value in the vicinity thereof.
　また、正極活物質は、二次粒子を有し、二次粒子が複数の一次粒子を有し、複数の一次粒子のうち、少なくとも一の一次粒子の表層部に添加元素を多く含む層を有し、添加元素を多く含む層の厚さは１ｎｍ以上１０ｎｍ以下である。ＮＣＭに添加元素を添加することで、充放電時、一次粒子間に生じるひび割れを減少させ、二次電池の寿命特性を向上させる。 In addition, the positive electrode active material has secondary particles, the secondary particles have a plurality of primary particles, and at least one of the plurality of primary particles has a layer containing a large amount of additive elements on the surface layer. However, the thickness of the layer containing a large amount of additive elements is 1 nm or more and 10 nm or less. By adding additive elements to NCM, cracks that occur between primary particles during charging and discharging are reduced, and the life characteristics of the secondary battery are improved.
　また、上記正極活物質を用いた二次電池も本明細書で開示する構成の一つである。二次電池は、正極活物質を有する正極と、負極活物質を有する負極とを有する。また、正極と負極の間にセパレータを有する。セパレータは短絡防止のために用いられ、安全性又は信頼性の高い二次電池を提供することができる。 Further, a secondary battery using the above positive electrode active material is also one of the configurations disclosed in this specification. A secondary battery has a positive electrode having a positive electrode active material and a negative electrode having a negative electrode active material. Furthermore, a separator is provided between the positive electrode and the negative electrode. The separator is used to prevent short circuits, and can provide a highly safe or reliable secondary battery.
　また本明細書で開示する他の構成は、反応槽にニッケルの水溶性塩、コバルトの水溶性塩、及びマンガンの水溶性塩の水溶性塩を含む水溶液と、アルカリ溶液と、を供給し、反応槽の内部で混合して少なくともニッケル、コバルト、マンガン、を含む複合水酸化物を析出させ、複合水酸化物と、リチウム化合物と、添加元素源と、を混合した混合物に第１の加熱を行い、解砕または粉砕した後、さらに第２の加熱を行い、解砕または粉砕する、正極活物質の作製方法である。 Further, another configuration disclosed in this specification supplies an aqueous solution containing a water-soluble salt of a water-soluble salt of nickel, a water-soluble salt of cobalt, and a water-soluble salt of manganese to the reaction tank, and an alkaline solution, A composite hydroxide containing at least nickel, cobalt, and manganese is precipitated by mixing inside a reaction tank, and a first heating is applied to the mixture of the composite hydroxide, the lithium compound, and the additive element source. This is a method for producing a positive electrode active material, in which, after crushing or crushing, a second heating is further performed to crush or crush.
　上記において、添加元素源は、フッ素源、アルミニウム源、マグネシウム源、チタン源、カルシウム源から選ばれる一または二以上であることが好ましい。 In the above, the additive element source is preferably one or more selected from a fluorine source, an aluminum source, a magnesium source, a titanium source, and a calcium source.
　また上記において、ニッケルの水溶性塩、コバルトの水溶性塩、及びマンガンの水溶性塩が有するニッケル、コバルトおよびマンガンの原子数比は、Ｎｉ：Ｃｏ：Ｍｎ＝６：２：２またはその近傍であることが好ましい。 Further, in the above, the atomic ratio of nickel, cobalt and manganese in the water-soluble salt of nickel, water-soluble cobalt, and water-soluble manganese is Ni:Co:Mn=6:2:2 or in the vicinity thereof. It is preferable that there be.
　本発明の一態様により、劣化しにくい正極活物質およびその作製方法を提供することができる。または、新規な正極活物質およびその作製方法を提供することができる。または、安全性または信頼性の高い二次電池およびその作製方法を提供することができる。または、劣化しにくい二次電池およびその作製方法を提供することができる。または、長寿命の二次電池を提供することができる。または、新規な二次電池およびその作製方法を提供することができる。 According to one embodiment of the present invention, a cathode active material that does not easily deteriorate and a method for producing the same can be provided. Alternatively, a novel positive electrode active material and a method for producing the same can be provided. Alternatively, a highly safe or reliable secondary battery and a method for manufacturing the same can be provided. Alternatively, it is possible to provide a secondary battery that does not easily deteriorate and a method for manufacturing the same. Alternatively, a long-life secondary battery can be provided. Alternatively, a novel secondary battery and a method for producing the same can be provided.
　なお、これらの効果の記載は、他の効果の存在を妨げるものではない。なお、本発明の一態様は、必ずしも、これらの効果の全てを有する必要はない。なお、これら以外の効果は、明細書、図面、請求項の記載から、自ずと明らかとなるものであり、明細書、図面、請求項の記載から、これら以外の効果を抽出することが可能である。 Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily need to have all of these effects. Note that effects other than these will naturally become apparent from the description, drawings, and claims, and it is possible to extract effects other than these from the description, drawings, and claims. .
図１Ａおよび図１Ｂは、正極活物質における、Ｌｉ２Ｏ生成と、ＬｉＦ生成のエネルギー差を比較する計算モデル図である。
図２Ａ乃至図２Ｅは、複合酸化物の表面にＡｌＦ３およびＬｉＦを被覆させた計算モデル図である。
図３Ａは二次粒子の外観を示す概略図であり、図３Ｂは二次粒子の断面の一例を示す模式図である。
図４Ａは二次粒子の断面の一例を示す図であり、図４Ｂは二次粒子の断面の一例を示す模式図である。
図５Ａおよび図５Ｂは単粒子の断面の一例を示す図である。
図６Ａおよび図６Ｂは本発明の一態様を示す作製工程のフロー図の一例である。
図７は本発明の一態様を示す作製工程のフロー図の一例である。
図８はフッ化リチウムとフッ化マグネシウムの組成および温度の関係を示す相図である。
図９はフッ化リチウムとフッ化ニッケルの組成および温度の関係を示す相図である。
図１０はフッ化リチウムとフッ化アルミニウムの組成および温度の関係を示す相図である。
図１１Ａはコイン型二次電池の分解斜視図であり、図１１Ｂはコイン型二次電池の斜視図であり、図１１Ｃはその断面斜視図である。
図１２Ａは、円筒型の二次電池の例を示す。図１２Ｂは、円筒型の二次電池の例を示す。図１２Ｃは、複数の円筒型の二次電池の例を示す。図１２Ｄは、複数の円筒型の二次電池を有する蓄電システムの例を示す。
図１３Ａ及び図１３Ｂは、二次電池の例を説明する図であり、図１３Ｃは、二次電池の内部の様子を示す図である。
図１４Ａ乃至図１４Ｃは、二次電池の例を説明する図である。
図１５Ａ及び図１５Ｂは、二次電池の外観を示す図である。
図１６Ａ乃至図１６Ｃは、二次電池の作製方法を説明する図である。
図１７Ａは、本発明の一態様を示す電池パックの斜視図であり、図１７Ｂは、電池パックのブロック図であり、図１７Ｃは、電池パックを有する車両のブロック図である。
図１８Ａ乃至図１８Ｄは、輸送用車両の一例を説明する図である。図１８Ｅは、人工衛星の一例を説明する図である。
図１９Ａは、電動自転車を示す図であり、図１９Ｂは、電動自転車の二次電池を示す図であり、図１９Ｃは、スクータを説明する図である。
図２０Ａ乃至図２０Ｄは、電子機器の一例を説明する図である。
図２１は、二次電池の温度上昇を示すグラフである。
図２２Ａ乃至図２２Ｃは、釘刺し試験を説明する図である。
図２３は、内部短絡が生じたときの二次電池の温度上昇を示すグラフである。
図２４Ａおよび図２４Ｂは、釘刺し試験の様子を示す写真である。
図２５Ａは、釘刺し試験における電池電圧の変化を示すグラフ、図２５Ｂは、釘刺し試験における電池温度の変化を示すグラフである。 FIG. 1A and FIG. 1B are calculation model diagrams comparing the energy difference between Li 2 O generation and LiF generation in the positive electrode active material.
2A to 2E are calculation model diagrams in which the surface of a composite oxide is coated with AlF 3 and LiF.
FIG. 3A is a schematic diagram showing the appearance of secondary particles, and FIG. 3B is a schematic diagram showing an example of a cross section of the secondary particles.
FIG. 4A is a diagram showing an example of a cross section of a secondary particle, and FIG. 4B is a schematic diagram showing an example of a cross section of a secondary particle.
FIGS. 5A and 5B are diagrams showing an example of a cross section of a single particle.
FIGS. 6A and 6B are an example of a flow diagram of a manufacturing process illustrating one embodiment of the present invention.
FIG. 7 is an example of a flow diagram of a manufacturing process illustrating one embodiment of the present invention.
FIG. 8 is a phase diagram showing the relationship between the composition and temperature of lithium fluoride and magnesium fluoride.
FIG. 9 is a phase diagram showing the relationship between the composition and temperature of lithium fluoride and nickel fluoride.
FIG. 10 is a phase diagram showing the relationship between the composition and temperature of lithium fluoride and aluminum fluoride.
FIG. 11A is an exploded perspective view of a coin-type secondary battery, FIG. 11B is a perspective view of the coin-type secondary battery, and FIG. 11C is a cross-sectional perspective view thereof.
FIG. 12A shows an example of a cylindrical secondary battery. FIG. 12B shows an example of a cylindrical secondary battery. FIG. 12C shows an example of a plurality of cylindrical secondary batteries. FIG. 12D shows an example of a power storage system having a plurality of cylindrical secondary batteries.
13A and 13B are diagrams illustrating an example of a secondary battery, and FIG. 13C is a diagram illustrating the inside of the secondary battery.
14A to 14C are diagrams illustrating examples of secondary batteries.
15A and 15B are diagrams showing the appearance of a secondary battery.
16A to 16C are diagrams illustrating a method for manufacturing a secondary battery.
FIG. 17A is a perspective view of a battery pack showing one embodiment of the present invention, FIG. 17B is a block diagram of the battery pack, and FIG. 17C is a block diagram of a vehicle having the battery pack.
18A to 18D are diagrams illustrating an example of a transportation vehicle. FIG. 18E is a diagram illustrating an example of an artificial satellite.
FIG. 19A is a diagram showing an electric bicycle, FIG. 19B is a diagram showing a secondary battery of the electric bicycle, and FIG. 19C is a diagram explaining a scooter.
20A to 20D are diagrams illustrating an example of an electronic device.
FIG. 21 is a graph showing the temperature rise of the secondary battery.
FIGS. 22A to 22C are diagrams illustrating a nail penetration test.
FIG. 23 is a graph showing the temperature rise of the secondary battery when an internal short circuit occurs.
FIGS. 24A and 24B are photographs showing the nail penetration test.
FIG. 25A is a graph showing changes in battery voltage during the nail penetration test, and FIG. 25B is a graph showing changes in battery temperature during the nail penetration test.
　以下では、本発明の実施の形態について図面を用いて詳細に説明する。ただし、本発明は以下の説明に限定されず、その形態および詳細を様々に変更し得ることは、当業者であれば容易に理解される。また、本発明は以下に示す実施の形態の記載内容に限定して解釈されるものではない。 Hereinafter, embodiments of the present invention will be described in detail using the drawings. However, those skilled in the art will easily understand that the present invention is not limited to the following description, and that its form and details can be changed in various ways. Further, the present invention is not to be interpreted as being limited to the contents described in the embodiments shown below.
　なお本明細書等において、粒子とは球形（断面形状が円）のみを指すことに限定されず、個々の粒子の断面形状が楕円形、長方形、台形、錐形、角が丸まった四角形、非対称の形状などが挙げられ、さらに個々の粒子は不定形であってもよい。 In this specification, etc., the term "particles" is not limited to only spherical shapes (circular cross-sectional shapes), but also includes individual particles whose cross-sectional shapes are elliptical, rectangular, trapezoidal, pyramidal, square with rounded corners, and asymmetrical. Further, individual particles may have an amorphous shape.
　また均質とは、複数の元素（例えばＡ，Ｂ，Ｃ）からなる固体において、ある元素（例えばＡ）が特定の領域に同様の特徴を有して分布する状態をいう。なお特定の領域同士の元素の濃度が実質的に同一であればよい。たとえば特定領域同士のある元素の検出量（たとえばＳＴＥＭ−ＥＤＸにおけるカウント数）の差が１０％以内であればよい。特定の領域としてはたとえば表層部、表面、凸部、凹部、内部などが挙げられる。 In addition, homogeneity refers to a state in which a certain element (for example, A) is distributed with similar characteristics in a specific region in a solid composed of multiple elements (for example, A, B, and C). Note that it is sufficient that the concentrations of the elements in the specific regions are substantially the same. For example, it is sufficient if the difference in the detected amount of a certain element (for example, the count number in STEM-EDX) between specific regions is within 10%. Specific areas include, for example, the surface layer, the surface, protrusions, recesses, and the inside.
　また添加元素が添加された正極活物質を複合酸化物、正極材、正極材料、二次電池用正極材、等と表現する場合がある。また本明細書等において、本発明の一態様の正極活物質は、化合物を有することが好ましい。また本明細書等において、本発明の一態様の正極活物質は、組成物を有することが好ましい。また本明細書等において、本発明の一態様の正極活物質は、複合体を有することが好ましい。 In addition, a positive electrode active material to which additive elements are added may be expressed as a composite oxide, a positive electrode material, a positive electrode material, a positive electrode material for secondary batteries, etc. Further, in this specification and the like, the positive electrode active material of one embodiment of the present invention preferably contains a compound. Further, in this specification and the like, the positive electrode active material of one embodiment of the present invention preferably has a composition. Further, in this specification and the like, the positive electrode active material of one embodiment of the present invention preferably has a composite.
　また、以下の実施の形態等で正極活物質の個別の粒子の特徴について述べる場合、必ずしも全ての粒子がその特徴を有していなくてもよい。たとえばランダムに３個以上選択した正極活物質の粒子のうち５０％以上、好ましくは７０％以上、より好ましくは９０％以上がその特徴を有していれば、十分に正極活物質およびそれを有する二次電池の特性を向上させる効果があるということができる。 Furthermore, when describing the characteristics of individual particles of the positive electrode active material in the following embodiments, etc., all particles do not necessarily have to have the characteristics. For example, if 50% or more, preferably 70% or more, more preferably 90% or more of three or more randomly selected positive electrode active material particles have the characteristic, it is sufficient to have the positive electrode active material and the same. It can be said that this has the effect of improving the characteristics of the secondary battery.
　また、二次電池のショートは二次電池の充電動作および／または放電動作における不具合を引き起こすのみでなく、発熱および発火を招く恐れがある。安全な二次電池を実現するためには、高い充電電圧においてもショート電流が抑制されることが好ましい。本発明の一態様の正極活物質は、高い充電電圧においてもショート電流が抑制される。そのため高い放電容量と安全性と、を両立した二次電池とすることができる。 Furthermore, a short circuit in the secondary battery not only causes problems in the charging and/or discharging operation of the secondary battery, but also may cause heat generation and ignition. In order to realize a safe secondary battery, it is preferable that short-circuit current be suppressed even at a high charging voltage. In the positive electrode active material of one embodiment of the present invention, short current is suppressed even at high charging voltage. Therefore, it is possible to obtain a secondary battery that has both high discharge capacity and safety.
　また特に言及しない限り、二次電池が有する材料（正極活物質、負極活物質、電解質、セパレータ等）は、劣化前の状態について説明するものとする。なお二次電池製造段階におけるエージング処理（バーンイン処理といってもよい）によって放電容量が減少することは劣化とは呼ばないとする。たとえば、リチウムイオン二次単電池およびリチウム二次組電池（以下、リチウムイオン二次電池という）の定格容量の９７％以上の放電容量を有する場合は、劣化前の状態と言うことができる。定格容量は、ポータブル機器用リチウムイオン二次電池の場合ＪＩＳ　Ｃ　８７１１：２０１９に準拠する。これ以外のリチウムイオン二次電池の場合、上記ＪＩＳ規格に限らず電動車両推進用、産業用などの各ＪＩＳ、ＩＥＣ規格等に準拠する。 Unless otherwise specified, materials included in the secondary battery (positive electrode active material, negative electrode active material, electrolyte, separator, etc.) will be described in terms of their state before deterioration. Note that a decrease in discharge capacity due to aging treatment (which may also be called burn-in treatment) in the secondary battery manufacturing stage is not called deterioration. For example, when a lithium ion secondary cell or a lithium secondary assembled battery (hereinafter referred to as a lithium ion secondary battery) has a discharge capacity of 97% or more of the rated capacity, it can be said to be in a state before deterioration. The rated capacity is based on JIS C 8711:2019 for lithium ion secondary batteries for portable devices. In the case of other lithium ion secondary batteries, they comply with not only the JIS standards mentioned above but also JIS and IEC standards for electric vehicle propulsion, industrial use, etc.
　また二次電池が有する材料の劣化前の状態を、初期品、または初期状態と呼称し、劣化後の状態（二次電池の定格容量の９７％未満の放電容量を有する場合の状態）を、使用中品または使用中の状態、あるいは使用済み品または使用済み状態と呼称する場合がある。 In addition, the state of the materials of the secondary battery before deterioration is called the initial product or initial state, and the state after deterioration (the state when the secondary battery has a discharge capacity of less than 97% of its rated capacity) is called the initial product or initial state. Sometimes referred to as a used product or in use state, or a used product or used state.
　本明細書等において、釘刺し試験における発火とは、釘を刺してから１分以内に炎が外装体より外に観察されることをいう。または二次電池の熱暴走が起きたことをいう。たとえば二次電池の温度上昇が１００℃を超えた場合、熱暴走が起きたということができる。このときの温度は二次電池の外装体に取り付けた温度センサにより測定することができる。また釘刺し試験終了後に、刺した箇所から２ｃｍ以上離れた場所において、正極および／または負極由来の固体の熱分解物が観察される場合も、発火したということができる。 In this specification, etc., ignition in the nail penetration test means that flame is observed outside the exterior body within one minute after the nail penetration test. Or, it means that thermal runaway of the secondary battery has occurred. For example, if the temperature rise of the secondary battery exceeds 100°C, it can be said that thermal runaway has occurred. The temperature at this time can be measured by a temperature sensor attached to the outer casing of the secondary battery. Furthermore, if a solid thermal decomposition product derived from the positive electrode and/or negative electrode is observed at a location 2 cm or more away from the nail penetration test after the nail penetration test, it can also be said that a fire has occurred.
　たとえば正極活物質に層状岩塩型のＬｉＭＯ２を用いる場合、理論的にはＯ／Ｍ比（Ｍはニッケル、コバルトおよびマンガンの和）は２である。一方、熱暴走によりＬｉＭＯ２から酸素が放出されると、Ｏ／Ｍ比は低下する。そのため、たとえば釘刺し試験終了後に、刺した箇所から２ｃｍ以上離れた場所において、ＥＤＸ分析におけるＯ／Ｍ比が１．３未満である場合、熱暴走が生じた、すなわち発火したということができる。 For example, when layered rock salt type LiMO 2 is used as the positive electrode active material, the O/M ratio (M is the sum of nickel, cobalt, and manganese) is theoretically 2. On the other hand, when oxygen is released from LiMO 2 due to thermal runaway, the O/M ratio decreases. Therefore, for example, if the O/M ratio in EDX analysis is less than 1.3 at a location 2 cm or more away from the nail penetration test after the nail penetration test, it can be said that thermal runaway has occurred, that is, ignition has occurred.
　また正極および／または負極の熱分解物には、たとえば正極集電体のアルミニウムが酸化した酸化アルミニウム、負極集電体の銅が酸化した酸化銅なども含む。 The thermal decomposition products of the positive electrode and/or negative electrode also include, for example, aluminum oxide, which is the oxidation of aluminum in the positive electrode current collector, and copper oxide, which is the oxidation of the copper in the negative electrode current collector.
　一方、火花および／または発煙が観察されても延焼しない、すなわち二次電池全体の熱暴走に至らなければ発火とはいわない。たとえば二次電池に釘刺し試験を行っても、上記発火が生じていなければ、発火しない二次電池ということができる。 On the other hand, even if sparks and/or smoke are observed, if the fire does not spread, that is, if the entire secondary battery does not go into thermal runaway, it is not considered a fire. For example, even if a secondary battery is subjected to a nail penetration test, if the above-mentioned ignition does not occur, it can be said that the secondary battery does not ignite.
（実施の形態１）
　本実施の形態では、図１乃至図１０を用いて本発明の一態様の正極活物質１０１について説明する。 (Embodiment 1)
In this embodiment, a positive electrode active material 101 of one embodiment of the present invention will be described with reference to FIGS. 1 to 10.
　正極活物質１０１は、リチウムと、遷移金属Ｍと、酸素とを有する。遷移金属Ｍは、ニッケルと、マンガンと、コバルトから選ばれる一または二以上であり、他の元素は当てはまらないとする。これに加えて添加元素を有することが好ましい。添加元素としては、たとえばフッ素、アルミニウム、マグネシウム、チタン、カルシウム、ジルコニウムから選ばれる一または二以上を用いることができる。または正極活物質１０１はニッケル−マンガン−コバルト酸リチウムに添加元素が加えられたものを有することができる。 The positive electrode active material 101 includes lithium, a transition metal M, and oxygen. The transition metal M is one or more selected from nickel, manganese, and cobalt, and other elements are not applicable. In addition to this, it is preferable to have an additive element. As the additive element, for example, one or more selected from fluorine, aluminum, magnesium, titanium, calcium, and zirconium can be used. Alternatively, the positive electrode active material 101 may include nickel-manganese-lithium cobalt oxide to which additional elements are added.
　リチウムイオン二次電池の正極活物質は、リチウムイオンが挿入または脱離しても電荷中性を保つために、酸化還元が可能な遷移金属を有する必要がある。本発明の一態様の正極活物質１０１は酸化還元反応を担う遷移金属Ｍとしてニッケルと、マンガンと、コバルトと、を有する。 The positive electrode active material of a lithium ion secondary battery must contain a transition metal capable of redox in order to maintain charge neutrality even when lithium ions are inserted or removed. The positive electrode active material 101 according to one embodiment of the present invention includes nickel, manganese, and cobalt as the transition metal M responsible for the redox reaction.
　図３Ａは、正極活物質１０１の外観の一例を示す模式図である。図３Ａに示すように正極活物質１０１は複数の一次粒子１００が凝集して一つの二次粒子を構成していることが好ましい。一次粒子とは、ＳＥＭ観察の際に一つの粒と認識される粒子のことを意味する。また、二次粒子とは一次粒子が凝集した塊を指す。一次粒子の凝集には、複数の一次粒子の間に働く結合力は問わない。共有結合、イオン結合、疎水性相互作用、ファンデルワールス力、その他の分子間相互作用のいずれであってもよいし、複数の結合力が働いていてもよい。なお、図３Ａにおいては、図を明瞭にするため添加元素を多く含む層１００ｍを示していない。 FIG. 3A is a schematic diagram showing an example of the appearance of the positive electrode active material 101. As shown in FIG. 3A, it is preferable that the positive electrode active material 101 has a plurality of primary particles 100 aggregated to form one secondary particle. The term "primary particle" refers to a particle that is recognized as a single particle during SEM observation. In addition, secondary particles refer to aggregates of primary particles. For the aggregation of primary particles, the bonding force acting between a plurality of primary particles does not matter. It may be a covalent bond, an ionic bond, a hydrophobic interaction, a van der Waals force, or any other intermolecular interaction, or a plurality of bonding forces may be at work. Note that in FIG. 3A, the layer 100m containing a large amount of additive elements is not shown for clarity.
　また、図３Ｂは、正極活物質１０１の断面模式図の一例を示している。 Further, FIG. 3B shows an example of a schematic cross-sectional view of the positive electrode active material 101.
　図３Ｂにおいて、二次粒子を構成する一次粒子に添加元素を多く含む層を設けた場合のバリエーションをいくつか図示している。矢印で引き出した一部の一次粒子およびその表層部を図３Ｂに複数箇所示している。一次粒子１００のうち、添加元素を多く含む層以外の領域を内部ということとする。つまり内部は相対的に添加元素の検出量が少ない領域である。 FIG. 3B shows several variations in the case where a layer containing a large amount of additive elements is provided on the primary particles constituting the secondary particles. Some primary particles and their surface layer portions drawn out by arrows are shown in multiple locations in FIG. 3B. Among the primary particles 100, a region other than the layer containing a large amount of additive elements is referred to as the inside. In other words, the inside is a region where the detected amount of the added element is relatively small.
　一次粒子１００の表層部に添加元素を多く含む層１００ｍが全面に設けられる場合もあれば、一次粒子１００に添加元素を多く含む層が設けられないものも混在する場合もある。また、一次粒子１００の両端にそれぞれ添加元素を多く含む層１００ｍ１、１００ｍ２が設けられる場合もある。また、二次粒子の中央部分に配置された一次粒子１００であっても一次粒子１００の表層部に添加元素を多く含む層１００ｍが全面に設けられる場合もある。また、一部の面にのみ添加元素を多く含む層１００ｍ３が設けられる場合もある。また、２つの一次粒子に共通する添加元素を多く含む層１００ｍ４が設けられる場合もある。添加元素を多く含む層１００ｍの厚さは１ｎｍ以上１０ｎｍ以下であることが好ましい。 There are cases where the layer 100m containing a large amount of additive elements is provided on the entire surface of the primary particles 100, and there are also cases where the primary particles 100 are not provided with a layer containing a large amount of additive elements. Further, layers 100m1 and 100m2 containing a large amount of additive elements may be provided at both ends of the primary particles 100, respectively. Further, even in the case of the primary particle 100 disposed in the central part of the secondary particle, the layer 100m containing a large amount of additive elements may be provided on the entire surface of the primary particle 100. Further, a layer 100 m3 containing a large amount of additive elements may be provided only on a part of the surface. Further, a layer 100m4 containing a large amount of additive elements common to the two primary particles may be provided. The thickness of the layer 100m containing a large amount of additive elements is preferably 1 nm or more and 10 nm or less.
　また、図４Ａは正極活物質１０１ａの断面模式図の一例を示している。図４Ａにおいては、正極活物質１０１ａの外側全体を覆うように、添加元素を多く含む層１００ｍ５を設ける例を示している。 Further, FIG. 4A shows an example of a schematic cross-sectional view of the positive electrode active material 101a. FIG. 4A shows an example in which a layer 100m5 containing a large amount of additive elements is provided so as to cover the entire outside of the positive electrode active material 101a.
　また、図４Ｂも、正極活物質１０１ｂの断面模式図の一例を示している。図４Ｂにおいては、正極活物質１０１ｂの表層部に添加元素を多く含む層１００ｍ６を設ける例を示している。図４Ｂにおいては、正極活物質１０１ｂの表層部と添加元素を多く含む層１００ｍ６は一致するとも言える。 Further, FIG. 4B also shows an example of a schematic cross-sectional view of the positive electrode active material 101b. FIG. 4B shows an example in which a layer 100m6 containing a large amount of additive elements is provided on the surface layer of the positive electrode active material 101b. In FIG. 4B, it can be said that the surface layer portion of the positive electrode active material 101b and the layer 100m6 containing a large amount of additive elements coincide with each other.
　正極活物質の製造方法、具体的には加熱温度、混合する添加元素源の量、添加元素源の材料、添加元素を添加するタイミングなどの様々な条件によって、図３Ｂの正極活物質１０１、図４Ａの正極活物質１０１ａ、図４Ｂの正極活物質１０１ｂのいずれかの構成、またはそれに近い構成を得ることができる。このように複数の一次粒子のうち、少なくとも一の一次粒子の表層部に添加元素を多く含む層を有する構成とすることで、充放電時、一次粒子間に生じるひび割れを減少させ、二次電池の安全性または寿命特性を向上させることができる。 The positive electrode active material 101 shown in FIG. 3B and FIG. It is possible to obtain the configuration of either the positive electrode active material 101a in FIG. 4A or the positive electrode active material 101b in FIG. 4B, or a configuration similar thereto. By creating a structure in which the surface layer of at least one of the plurality of primary particles contains a layer containing a large amount of additive elements, cracks that occur between the primary particles during charging and discharging can be reduced, and the secondary battery can improve the safety or longevity characteristics of
　なお図３および図４では二次粒子である正極活物質１０１について説明したが、本発明の一態様はこれに限らない。正極活物質１０１は図５Ａに示すように単粒子（一次粒子ともいう）であってもよい。この場合、図５Ｂに示すように内部に結晶粒界１０５を有していてもよいが、結晶性が高いことが好ましく、単結晶であることがより好ましい。 Although the positive electrode active material 101, which is a secondary particle, has been described in FIGS. 3 and 4, one embodiment of the present invention is not limited thereto. The positive electrode active material 101 may be a single particle (also referred to as a primary particle) as shown in FIG. 5A. In this case, although it may have grain boundaries 105 inside as shown in FIG. 5B, it is preferable to have high crystallinity, and more preferably to be a single crystal.
　添加元素を多く含む層１００ｍと、内部は、同じ主成分（たとえばニッケル）を有し、添加元素を多く含む層１００ｍと、内部とが、互いに連結している構成であることが好ましい。当該構成とすることで、添加元素を多く含む層１００ｍが内部を保護しているため、二次電池に用いた際に内部ショートに対して優れた効果を奏する。例えば、二次電池の外部から釘などが刺さった場合に、添加元素を多く含む層１００ｍを有する構成であるため、発火しない、または発火し難い正極活物質の構造と捉えることができる。 It is preferable that the layer 100m containing a large amount of the additive element and the inside thereof have the same main component (for example, nickel), and the layer 100m containing a large amount of the additive element and the inside thereof are connected to each other. With this configuration, since the layer 100m containing a large amount of additive elements protects the inside, it has an excellent effect against internal short circuits when used in a secondary battery. For example, since the structure has 100 m of layers containing a large amount of additive elements when a nail or the like is penetrated from the outside of the secondary battery, it can be regarded as a positive electrode active material structure that does not ignite or is difficult to ignite.
　たとえば添加元素を多く含む層１００ｍにおいて添加元素から選ばれた一、たとえばフッ素の検出量が内部よりも多くなることで、正極活物質１０１と、電解液との過剰な反応を抑制することができる。そのため二次電池に用いた際に、二次電池の内部ショート等に対する安全性が高まることが期待できる。またフッ酸に対する耐食性を効果的に向上させることができる。 For example, in the layer 100m containing a large amount of additive elements, the detected amount of one selected from the additive elements, such as fluorine, is greater than that inside, so that excessive reaction between the positive electrode active material 101 and the electrolyte can be suppressed. . Therefore, when used in a secondary battery, it can be expected to improve safety against internal short circuits of the secondary battery. Furthermore, corrosion resistance against hydrofluoric acid can be effectively improved.
　また添加元素を多く含む層１００ｍにおいて添加元素から選ばれた一または二以上の検出量が内部よりも高くなることで、正極活物質１０１表面の導電性が変化するとより好ましい。たとえば正極活物質１０１の粉体抵抗が高まることが好ましい。粉体抵抗の高い正極活物質１０１とすることで、二次電池に用いた際に、二次電池の内部ショート等に対する安全性が高まることが期待できる。 Furthermore, it is more preferable that the detected amount of one or more selected from the additive elements in the layer 100m containing a large amount of additive elements becomes higher than that inside the layer 100m, thereby changing the conductivity of the surface of the positive electrode active material 101. For example, it is preferable that the powder resistance of the positive electrode active material 101 is increased. By using the positive electrode active material 101 with high powder resistance, when used in a secondary battery, it can be expected that the safety against internal short circuits of the secondary battery will be increased.
　上記のような正極活物質とすることで、二次電池に用いた際に安全性の高い二次電池とすることができる。たとえば、内部ショートによる発火を抑制することができる。 By using the positive electrode active material as described above, a highly safe secondary battery can be obtained when used in a secondary battery. For example, ignition due to internal short circuits can be suppressed.
　内部よりも、添加元素を多く含む層１００ｍにおいて、添加元素の検出量が多いことが好ましい。同時に、内部にも添加元素が低濃度で含まれていることが好ましい。特に、フッ素およびアルミニウムから選ばれる一または二を、低濃度で正極活物質１０１の内部に有することで、正極活物質１０１の結晶構造をより安定にできる可能性がある。ただし添加元素の濃度によっては、内部に存在していても、ＥＤＸ、ＸＰＳ等の分析において検出下限以下となる場合がある。 It is preferable that the amount of the added element detected is larger in the layer 100m containing more added elements than in the inside. At the same time, it is preferable that the additive element be contained inside at a low concentration. In particular, by having one or two selected from fluorine and aluminum at a low concentration inside the positive electrode active material 101, the crystal structure of the positive electrode active material 101 may be made more stable. However, depending on the concentration of the added element, even if it exists inside, it may be below the detection limit in analysis such as EDX and XPS.
　図１Ａおよび図１Ｂに、添加元素を多く含む層１００ｍを有する正極活物質の例として、マグネシウムを有するコバルト酸リチウムと、マグネシウムおよびフッ素を有するコバルト酸リチウムのモデルを示す。これら２つのモデルについて、それぞれ金属リチウムとの反応の際のエネルギー変化を計算した。 FIGS. 1A and 1B show models of lithium cobalt oxide containing magnesium and lithium cobalt oxide containing magnesium and fluorine, as examples of positive electrode active materials having 100 m of layers containing many additive elements. For these two models, the energy change upon reaction with metallic lithium was calculated.
　図１Ａは、表面にフッ素が無く、コバルト酸リチウムから酸素が脱離した時にその酸素が負極由来（負極から伸びてきたＬｉデンドライトを想定）の金属Ｌｉと反応して、Ｌｉ２Ｏ（酸化リチウム）が生成するケースを想定したモデルである。図１Ｂは、表面にフッ素があり、負極由来の金属Ｌｉとフッ素が反応して、ＬｉＦ（フッ化リチウム）が生成するケースを想定したモデルである。 In Figure 1A, there is no fluorine on the surface, and when oxygen is desorbed from lithium cobalt oxide, the oxygen reacts with metal Li originating from the negative electrode (assuming a Li dendrite extending from the negative electrode), forming Li 2 O (lithium oxide). ) is generated. FIG. 1B is a model assuming a case where fluorine is present on the surface and LiF (lithium fluoride) is generated by the reaction between the metal Li derived from the negative electrode and the fluorine.
　計算条件は下記の通りとした。
ソフトウェア：ＶＡＳＰ（Ｖｉｅｎｎａ　Ａｂ　ｉｎｉｔｉｏ　Ｓｉｍｕｌａｔｉｏｎ　Ｐａｃｋａｇｅ）
バージョン：６．２．１
汎関数：ＧＧＡ−ＰＢＥ
擬ポテンシャル：ＰＡＷ
ｋ点：
　表面モデル：ガンマ点のみ
　金属Ｌｉ：５×５×５
　ＬｉＦ：５×５×５
　Ｌｉ２Ｏ：５×５×５
カットオフエネルギー：１０００ｅＶ
ファンデルワールス力：ＤＦＴ−Ｄ２
ＬＤＡＵＵ：
　Ｃｏ：２．０
　それ以外の元素：０．０
ＬＤＡＵＪ：
　全元素で０．０ The calculation conditions were as follows.
Software: VASP (Vienna Ab initio Simulation Package)
Version: 6.2.1
Functional: GGA-PBE
Pseudopotential: PAW
Point k:
Surface model: Gamma point only Metal Li: 5×5×5
LiF: 5×5×5
Li2O : 5×5×5
Cutoff energy: 1000eV
Van der Waals force: DFT-D2
LDAUU:
Co:2.0
Other elements: 0.0
LDAUJ:
0.0 for all elements
　それぞれの反応前後のエネルギー差ΔＥを計算すると、図１Ｂ（ＬｉＦ生成）に比べて図１Ａ（Ｌｉ２Ｏ生成）のほうが、ΔＥが負に大きい（つまり発熱量が大きい）結果となった。 When calculating the energy difference ΔE before and after each reaction, it was found that ΔE was negatively larger (that is, the calorific value was larger) in FIG. 1A (Li 2 O production) than in FIG. 1B (LiF production).
　図１Ａと図１Ｂについての計算結果の詳細を表１に示す。単位はｅＶである。 Details of the calculation results for FIGS. 1A and 1B are shown in Table 1. The unit is eV.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　上記のように、金属Ｌｉは酸素よりもフッ素と反応したほうが、発熱量が小さいため、フッ素を有する添加元素を多く含む層１００ｍとすることで、二次電池に用いた際に安全性の高い二次電池とすることができる可能性がある。 As mentioned above, metal Li generates less heat when it reacts with fluorine than with oxygen, so by creating a 100m layer containing a large amount of fluorine-containing additive elements, it can be used in secondary batteries with high safety. There is a possibility that it can be used as a secondary battery.
　次に添加元素源としてフッ化アルミニウムとフッ化リチウムを用いる場合を想定した表面モデルの量子分子動力学（ＭＤ）計算を行った。 Next, quantum molecular dynamics (MD) calculations were performed on a surface model assuming a case where aluminum fluoride and lithium fluoride were used as sources of additive elements.
　計算条件は下記の通りとした。
ソフトウェア：ＶＡＳＰ（Ｖｉｅｎｎａ　Ａｂ　ｉｎｉｔｉｏ　Ｓｉｍｕｌａｔｉｏｎ　Ｐａｃｋａｇｅ）
　バージョン：６．２．１
汎関数：ＧＧＡ−ＰＢＥ
擬ポテンシャル：ＰＡＷ
ｋ点：ガンマ点のみ
カットオフエネルギー：１０００ｅＶ
ファンデルワールス力：ＤＦＴ−Ｄ２
ＬＤＡＵＵ：
　Ｎｉ：５．２６
　Ｃｏ：４．９１
　Ｍｎ：４．６４
　それ以外の元素：０．０
ＬＤＡＵＪ：
　全元素で０．０
量子分子動力学（ＭＤ）計算：
　アンサンブル：ＮＰＴ
　温度：３００Ｋ The calculation conditions were as follows.
Software: VASP (Vienna Ab initio Simulation Package)
Version: 6.2.1
Functional: GGA-PBE
Pseudopotential: PAW
K point: Gamma point only Cutoff energy: 1000eV
Van der Waals force: DFT-D2
LDAUU:
Ni: 5.26
Co:4.91
Mn: 4.64
Other elements: 0.0
LDAUJ:
0.0 for all elements
Quantum molecular dynamics (MD) calculations:
Ensemble:NPT
Temperature: 300K
図２Ａ乃至図２Ｅに示すフッ化アルミニウムとフッ化リチウムの割合を変えた計算結果を示す。図２Ａ乃至図２Ｅの計算モデルの詳細を表２に示す。 Calculation results are shown in which the ratios of aluminum fluoride and lithium fluoride shown in FIGS. 2A to 2E are changed. Details of the calculation models shown in FIGS. 2A to 2E are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　添加元素源としてフッ化アルミニウムのみを想定した図２Ａでは、図中に楕円の破線で示すように、結合が少ない領域が存在し、内部と表層部との密着性が悪いことが予想された。 In FIG. 2A, where only aluminum fluoride is assumed as the additive element source, there is a region with little bonding, as shown by the broken ellipse line in the figure, and it was predicted that the adhesion between the interior and the surface layer would be poor.
　一方で添加元素源としてフッ化リチウムのみを想定した図２Ｅでは、内部と添加元素を多く含む層１００ｍにおいて結晶構造の配向が概略一致しており、内部と表層部との密着性がよいことが予想された。 On the other hand, in Figure 2E, which assumes only lithium fluoride as the additive element source, the orientation of the crystal structure in the interior and in the layer 100m containing a large amount of additive elements is approximately the same, indicating that the adhesion between the interior and the surface layer is good. It was expected.
　添加元素源としてフッ化アルミニウムとフッ化リチウムの両方を用いることを想定した図２Ｂ乃至図２Ｄでは、図２Ａのような結合が少ない領域が減少しており、また少なくとも一部で結晶構造の配向が概略一致しており、内部と表層部との密着性が比較的よいことが予想された。 In FIGS. 2B to 2D, which assume that both aluminum fluoride and lithium fluoride are used as additive element sources, the regions with few bonds as in FIG. 2A are reduced, and the crystal structure is oriented in at least a portion It was predicted that the adhesion between the inside and the surface layer was relatively good.
　上記のように、添加元素源にフッ化リチウムを用いると、正極活物質１０１における表層部に存在する添加元素を多く含む層１００ｍと、内部との連結を強化できる可能性がある。 As described above, when lithium fluoride is used as an additive element source, there is a possibility that the connection between the layer 100m containing a large amount of additive elements present in the surface layer of the positive electrode active material 101 and the interior thereof can be strengthened.
　また本発明の一態様の正極活物質１０１は、層状岩塩型の結晶構造を有することが好ましい。また本発明の一態様の正極活物質１０１の組成は、ＬｉＮｉｘＣｏｙＭｎｚＯ２（ｘ＞０、ｙ＞０、ｚ＞０、０．８＜ｘ＋ｙ＋ｚ＜１．２）で表すとき、ｘ、ｙおよびｚは、ｘ：ｙ：ｚ＝６：２：２またはその近傍の値を満たすことが好ましい。またはｘ、ｙおよびｚは、ｘ：ｙ：ｚ＝１：１：１またはその近傍の値を満たすことが好ましい。またはｘ、ｙおよびｚは、ｘ：ｙ：ｚ＝５：２：３またはその近傍の値を満たすことが好ましい。またはｘ、ｙおよびｚは、ｘ：ｙ：ｚ＝８：１：１またはその近傍の値を満たすことが好ましい。またはｘ、ｙおよびｚは、ｘ：ｙ：ｚ＝１：４：１またはその近傍の値を満たすことが好ましい。なお本明細書等において、組成における近傍の値とは、有効数字を１桁としたとき該組成になる範囲をいうことする。このとき有効数字の下の桁は四捨五入する。たとえばｘ：ｙ：ｚ＝４．６：２．３：３．１はｘ：ｙ：ｚ＝５：２：３の近傍の値ということができる。 Further, the positive electrode active material 101 of one embodiment of the present invention preferably has a layered rock salt crystal structure. Further, the composition of the positive electrode active material 101 of one embodiment of the present invention is expressed as LiNix Co y Mn z O 2 (x>0, y>0, z>0, 0.8<x+y+z<1.2), It is preferable that x, y, and z satisfy x:y:z=6:2:2 or a value in the vicinity thereof. Alternatively, it is preferable that x, y, and z satisfy x:y:z=1:1:1 or a value in the vicinity thereof. Alternatively, x, y, and z preferably satisfy x:y:z=5:2:3 or a value in the vicinity thereof. Alternatively, x, y, and z preferably satisfy x:y:z=8:1:1 or a value in the vicinity thereof. Alternatively, it is preferable that x, y, and z satisfy x:y:z=1:4:1 or a value in the vicinity thereof. Note that in this specification and the like, a value in the vicinity of a composition refers to a range in which the composition is obtained when the significant figure is set to one digit. At this time, the digits below the significant figures are rounded off. For example, x:y:z=4.6:2.3:3.1 can be said to be a value near x:y:z=5:2:3.
　層状岩塩型の結晶構造を有し、遷移金属Ｍとしてニッケル、コバルトおよびマンガンを有する正極活物質をＮＣＭともいう。 A positive electrode active material having a layered rock salt type crystal structure and containing nickel, cobalt, and manganese as transition metals M is also referred to as NCM.
＜粒径＞
　本発明の一態様の正極活物質１０１が単粒子（一次粒子）の場合、粒径は小さい方が、割れが生じにくく好ましい。一方で粒径が小さすぎると、比表面積が大きくなり電解液との副反応が増大する、等の懸念がある。そのため本発明の一態様の正極活物質は、レーザ回折・散乱法から測定されるメディアン径が２μｍ以上２０μｍ以下であることが好ましい。 <Particle size>
When the positive electrode active material 101 according to one embodiment of the present invention is a single particle (primary particle), it is preferable that the particle size is smaller so that cracks are less likely to occur. On the other hand, if the particle size is too small, there is a concern that the specific surface area will increase and side reactions with the electrolyte will increase. Therefore, the positive electrode active material of one embodiment of the present invention preferably has a median diameter of 2 μm or more and 20 μm or less as measured by a laser diffraction/scattering method.
　また単粒子の場合、正極活物質の表面はなめらかで、つやつやであることが好ましい。または、正極活物質は角がない、または丸みを帯びていることが好ましい。表面がなめらかである、角がない、といった特徴により比表面積が小さくなり、かつ割れが生じにくくなる。 In the case of single particles, the surface of the positive electrode active material is preferably smooth and glossy. Alternatively, it is preferable that the positive electrode active material has no corners or is rounded. Due to its smooth surface and lack of corners, the specific surface area is small and cracks are less likely to occur.
　または正極活物質は表面に極微小粒が観察されないか、極めて少ないことが好ましい。極微小粒は、正極活物質の破片、および／または反応しなかった添加元素源等である場合がある。本明細書等において極微小粒とは、粒径０．００１μｍ以上１μｍ以下の金属化合物粒子を言うこととする。 Alternatively, it is preferable that no or very few ultrafine particles be observed on the surface of the positive electrode active material. The ultrafine particles may be fragments of the positive electrode active material and/or sources of additive elements that have not reacted. In this specification and the like, ultrafine particles refer to metal compound particles having a particle size of 0.001 μm or more and 1 μm or less.
　該極微小粒の粒径は、表面ＳＥＭ像から測定されるＦｅｒｅｔ径または投影円相当径とする。金属化合物であるか否かはＳＥＭ−ＥＤＸ等で分析することができる。 The particle size of the ultrafine particles is the Feret diameter or projection circle equivalent diameter measured from a surface SEM image. Whether it is a metal compound or not can be analyzed by SEM-EDX or the like.
　後述するように、本発明の一態様の正極活物質の作製工程では、添加元素源と共に融剤として機能する材料を加える。これにより加熱の際に複合酸化物の表面と、添加元素源と、が溶融し、その後固化する。そのため表面に極微小粒が付着していたとしても、これらの工程において共に溶融し、表面に残らないか、極めて少なくなる。正極活物質の表面に極微小粒がない、または極めて少ないことは、作製工程において複合酸化物と融剤として機能する材料とを共に加熱したことを示すともいえる。 As described below, in the manufacturing process of the positive electrode active material of one embodiment of the present invention, a material that functions as a flux is added together with the additive element source. As a result, the surface of the composite oxide and the additive element source are melted during heating, and then solidified. Therefore, even if extremely small particles are attached to the surface, they will be melted together in these steps and will not remain on the surface or will be extremely small. The fact that there are no or very few ultrafine particles on the surface of the positive electrode active material can also be said to indicate that the composite oxide and the material functioning as a flux were heated together in the manufacturing process.
　なお上記の測定するために表面ＳＥＭ像を取得する場合、二次電池に用いられた正極についてはセパレータと接していた領域の影響を無視できる領域から取得することが好ましい。たとえば正極活物質層からカーボン両面テープ等で一部剥離させたものから表面ＳＥＭ像を取得することが好ましい。また上記の分析方法は、表面ＳＥＭ像の分解能から、粒径が１μｍ以上の場合に特に有効である。 Note that when acquiring a surface SEM image for the above measurements, it is preferable to acquire the positive electrode used in the secondary battery from a region where the influence of the region in contact with the separator can be ignored. For example, it is preferable to obtain a surface SEM image from a portion of the positive electrode active material layer that has been peeled off with a double-sided carbon tape or the like. Further, the above analysis method is particularly effective when the particle size is 1 μm or more because of the resolution of the surface SEM image.
　また、粒径の異なる粒子を混合して正極に用いると、電極密度を増大させることができ、エネルギー密度の高い二次電池とすることができ好ましい。相対的に粒径の小さい正極活物質１０１は充放電レート特性が高いことが期待される。相対的に粒径の大きい正極活物質１０１は、充放電サイクル特性が高く、放電容量を高く保てることが期待される。 Furthermore, it is preferable to use a mixture of particles with different particle sizes in the positive electrode, since the electrode density can be increased and a secondary battery with high energy density can be obtained. The positive electrode active material 101 having a relatively small particle size is expected to have high charge/discharge rate characteristics. The positive electrode active material 101 having a relatively large particle size is expected to have high charge/discharge cycle characteristics and maintain a high discharge capacity.
≪正極活物質の作製方法１≫
　図６Ａ乃至図７を用いて、上記正極活物質１０１を作製する方法について以下に一例を説明する。 ≪Method for producing positive electrode active material 1≫
An example of a method for manufacturing the positive electrode active material 101 will be described below with reference to FIGS. 6A to 7.
＜ステップＳ１１１＞
　図６ＡのステップＳ１１１として、まず遷移金属Ｍ源、すなわちニッケル源（Ｎｉ源）、コバルト源（Ｃｏ源）およびマンガン源（Ｍｎ源）を用意する。これらは層状岩塩型の結晶構造をとりうる範囲のニッケル、コバルト、マンガンの混合比とすることが好ましい。 <Step S111>
As step S111 in FIG. 6A, transition metal M sources, that is, a nickel source (Ni source), a cobalt source (Co source), and a manganese source (Mn source) are first prepared. It is preferable that the mixing ratio of nickel, cobalt, and manganese be such that a layered rock salt type crystal structure can be formed.
　特に正極活物質１０１が有する遷移金属Ｍとしてニッケルを多く含むと、コバルトが多い場合と比較して原料が安価になる場合があり、また重量あたりの充放電容量が増加する場合があり好ましい。たとえば遷移金属Ｍ（Ｍはニッケル、コバルトおよびマンガンの和）のうちニッケルは、２５原子％を超えることが好ましく、６０原子％以上がより好ましく、８０原子％以上がさらに好ましい。しかしニッケルの占める割合が高すぎると、化学安定性および耐熱性が下がるおそれがある。そのため遷移金属Ｍのうちニッケルは９５原子％以下であることが好ましい。 In particular, when the positive electrode active material 101 contains a large amount of nickel as the transition metal M, the raw material may be cheaper than when the positive electrode active material 101 contains a large amount of cobalt, and the charge/discharge capacity per weight may increase, which is preferable. For example, in the transition metal M (M is the sum of nickel, cobalt, and manganese), nickel preferably exceeds 25 atom %, more preferably 60 atom % or more, and even more preferably 80 atom % or more. However, if the proportion of nickel is too high, chemical stability and heat resistance may decrease. Therefore, it is preferable that the content of nickel in the transition metal M is 95 atomic % or less.
　遷移金属Ｍとしてコバルトを有すると、平均放電電圧が高く、またコバルトが層状岩塩型の構造の安定化に寄与するため信頼性の高い二次電池とすることができ好ましい。 It is preferable to have cobalt as the transition metal M, since the average discharge voltage is high and cobalt contributes to stabilizing the layered rock-salt structure, resulting in a highly reliable secondary battery.
　遷移金属Ｍとしてマンガンを有すると、耐熱性および化学安定性が向上するため好ましい。しかしマンガンの占める割合が高すぎると、放電電圧および放電容量が低下する傾向がある。そのためたとえば遷移金属Ｍのうちマンガンは、２．５原子％以上３４原子％以下であることが好ましい。 It is preferable to have manganese as the transition metal M because heat resistance and chemical stability are improved. However, if the proportion of manganese is too high, the discharge voltage and discharge capacity tend to decrease. Therefore, for example, it is preferable that the content of manganese in the transition metal M is 2.5 atomic % or more and 34 atomic % or less.
　遷移金属Ｍ源は遷移金属Ｍを含む水溶液として用意する。ニッケル源としては、ニッケル塩の水溶液を用いることができる。ニッケル塩としては、たとえば硫酸ニッケル、塩化ニッケル、硝酸ニッケル、またはこれらの水和物を用いることができる。また酢酸ニッケルをはじめとするニッケルの有機酸塩、またはこれらの水和物を用いることもできる。またニッケル源としてニッケルアルコキシドまたは有機ニッケル錯体の水溶液を用いることができる。なお本明細書等において、有機酸塩とは、酢酸、クエン酸、シュウ酸、ギ酸、酪酸等の有機酸と金属の化合物をいうこととする。 The transition metal M source is prepared as an aqueous solution containing transition metal M. As the nickel source, an aqueous solution of nickel salt can be used. As the nickel salt, for example, nickel sulfate, nickel chloride, nickel nitrate, or hydrates thereof can be used. Further, organic acid salts of nickel such as nickel acetate, or hydrates thereof can also be used. Further, an aqueous solution of nickel alkoxide or an organic nickel complex can be used as the nickel source. Note that in this specification and the like, an organic acid salt refers to a compound of an organic acid such as acetic acid, citric acid, oxalic acid, formic acid, butyric acid, and a metal.
　同様にコバルト源としては、コバルト塩の水溶液を用いることができる。コバルト塩としては、たとえば硫酸コバルト、塩化コバルト、硝酸コバルト、またはこれらの水和物を用いることができる。また酢酸コバルトをはじめとするコバルトの有機酸塩、またはこれらの水和物を用いることもできる。またコバルト源としてコバルトアルコキシド、有機コバルト錯体の水溶液を用いることができる。 Similarly, an aqueous solution of cobalt salt can be used as the cobalt source. As the cobalt salt, for example, cobalt sulfate, cobalt chloride, cobalt nitrate, or hydrates thereof can be used. Furthermore, organic acid salts of cobalt such as cobalt acetate, or hydrates thereof can also be used. Furthermore, an aqueous solution of a cobalt alkoxide or an organic cobalt complex can be used as the cobalt source.
　同様にマンガン源としては、マンガン塩の水溶液を用いることができる。マンガン塩としては、たとえば硫酸マンガン、塩化マンガン、硝酸マンガン、またはこれらの水和物の水溶液を用いることができる。また酢酸マンガンをはじめとするマンガンの有機酸塩、またはこれらの水和物を用いることもできる。またマンガン源としてマンガンアルコキシド、または有機マンガン錯体の水溶液を用いることができる。 Similarly, an aqueous solution of manganese salt can be used as the manganese source. As the manganese salt, for example, manganese sulfate, manganese chloride, manganese nitrate, or an aqueous solution of a hydrate thereof can be used. Furthermore, organic acid salts of manganese such as manganese acetate, or hydrates thereof can also be used. Furthermore, an aqueous solution of manganese alkoxide or an organic manganese complex can be used as the manganese source.
　本実施の形態では、遷移金属Ｍ源として、硫酸ニッケル、硫酸コバルトおよび硫酸マンガンを純水に溶解させた水溶液を用意することとする。このときニッケル、コバルトおよびマンガンの原子数比は、Ｎｉ：Ｃｏ：Ｍｎ＝６：２：２またはこの近傍とする。該水溶液は酸性を示す。 In this embodiment, an aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate are dissolved in pure water is prepared as a transition metal M source. At this time, the atomic ratio of nickel, cobalt, and manganese is set to Ni:Co:Mn=6:2:2 or around this. The aqueous solution exhibits acidity.
＜ステップＳ１１３＞
　また図６ＡのステップＳ１１３に示すように、キレート剤を用意してもよい。キレート剤として、たとえばグリシン、オキシン、１−ニトロソ−２−ナフトール、２−メルカプトベンゾチアゾール、またはＥＤＴＡ（エチレンジアミン四酢酸）が挙げられる。なお、グリシン、オキシン、１−ニトロソ−２−ナフトールまたは２−メルカプトベンゾチアゾールから選ばれた複数種を用いてもよい。これらのうち少なくとも一つを純水に溶解させキレート水溶液として用いる。キレート剤は、キレート化合物を作る錯化剤であり、一般的な錯化剤より好ましい。勿論キレート剤でなく錯化剤を用いてもよく、錯化剤としてアンモニア水を用いることができる。キレート水溶液を用いることで結晶の核の不要な発生を抑え、成長を促すことができ好ましい。不要な核の発生が抑制されると微粒子の生成が抑制されるため、粒度分布が良好な複合水酸化物を得ることができる。またキレート水溶液を用いることで、酸塩基反応を遅らせることができ、徐々に反応が進むことで球状に近い二次粒子を得ることができる。グリシンは９以上１０以下及びその付近のｐＨにて、当該ｐＨ値を一定に保つ作用があり、キレート水溶液としてグリシン水溶液を用いることで、上記複合水酸化物９８を得る際の反応槽のｐＨが制御しやすくなり好ましい。 <Step S113>
Further, as shown in step S113 in FIG. 6A, a chelating agent may be prepared. Chelating agents include, for example, glycine, oxine, 1-nitroso-2-naphthol, 2-mercaptobenzothiazole, or EDTA (ethylenediaminetetraacetic acid). In addition, you may use multiple types selected from glycine, oxine, 1-nitroso-2-naphthol, and 2-mercaptobenzothiazole. At least one of these is dissolved in pure water and used as a chelate aqueous solution. Chelating agents are complexing agents that create chelate compounds and are preferred over common complexing agents. Of course, a complexing agent may be used instead of a chelating agent, and aqueous ammonia can be used as the complexing agent. It is preferable to use a chelate aqueous solution because it can suppress unnecessary generation of crystal nuclei and promote growth. When the generation of unnecessary nuclei is suppressed, the generation of fine particles is suppressed, so that a composite hydroxide with a good particle size distribution can be obtained. In addition, by using an aqueous chelate solution, the acid-base reaction can be delayed, and the reaction proceeds gradually, making it possible to obtain nearly spherical secondary particles. Glycine has the effect of keeping the pH value constant at a pH of 9 or more and 10 or less, and by using a glycine aqueous solution as the chelate aqueous solution, the pH of the reaction tank when obtaining the above composite hydroxide 98 can be adjusted. This is preferable because it is easier to control.
＜ステップＳ１１４＞
　次に図６ＡのステップＳ１１４として、遷移金属Ｍ源とキレート剤を混合し、酸溶液を作製する。 <Step S114>
Next, in step S114 in FIG. 6A, a transition metal M source and a chelating agent are mixed to prepare an acid solution.
＜ステップＳ１２１＞
　次に図６ＡのステップＳ１２１として、アルカリ溶液を用意する。アルカリ溶液としては、たとえば水酸化ナトリウム、水酸化カリウム、水酸化リチウム、またはアンモニアを有する水溶液を用いることができる。純水を用いてこれらを溶解させた水溶液を用いることができる。また水酸化ナトリウム、水酸化カリウム、水酸化リチウム、またはアンモニアから選ばれた複数種を純水に溶解させた水溶液でもよい。 <Step S121>
Next, in step S121 of FIG. 6A, an alkaline solution is prepared. As the alkaline solution, for example, an aqueous solution containing sodium hydroxide, potassium hydroxide, lithium hydroxide or ammonia can be used. An aqueous solution in which these are dissolved using pure water can be used. Alternatively, it may be an aqueous solution in which multiple types selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia are dissolved in pure water.
　上記遷移金属Ｍ源およびアルカリ溶液に用いると好ましい純水とは、比抵抗が１ＭΩ・ｃｍ以上の水、より好ましくは比抵抗が１０ＭΩ・ｃｍ以上の水、さらに好ましくは比抵抗が１５ＭΩ・ｃｍ以上の水である。当該比抵抗を満たす水は純度が高く、含有される不純物が非常に少ない。 The pure water preferably used for the transition metal M source and alkaline solution is water with a specific resistance of 1 MΩ·cm or more, more preferably water with a specific resistance of 10 MΩ·cm or more, and even more preferably 15 MΩ·cm or more. water. Water that satisfies the specific resistance has high purity and contains very few impurities.
＜ステップＳ１２２＞
　また図６ＡのステップＳ１２２に示すように、水を反応槽に用意することが好ましい。この水は、キレート剤の水溶液であってもよいが、純水であることがより好ましい。純水を用いることで核形成が促進され、小粒径の複合水酸化物を作製することができる。この反応槽に用意した水は、反応槽の張り込み液または調整液ということができる。キレート水溶液とする場合、ステップＳ１３の記載を参照することができる。 <Step S122>
Moreover, as shown in step S122 of FIG. 6A, it is preferable to prepare water in the reaction tank. This water may be an aqueous solution of a chelating agent, but is more preferably pure water. By using pure water, nucleation is promoted and a composite hydroxide with a small particle size can be produced. The water prepared in this reaction tank can be called a filling liquid or adjustment liquid for the reaction tank. When using a chelate aqueous solution, the description of step S13 can be referred to.
＜ステップＳ１３１＞
　次に図６ＡのステップＳ１３１として、酸溶液とアルカリ溶液を混合し、反応させる。該反応は、共沈反応、中和反応または酸塩基反応ということができる。 <Step S131>
Next, in step S131 of FIG. 6A, the acid solution and the alkaline solution are mixed and reacted. The reaction can be referred to as a coprecipitation reaction, a neutralization reaction, or an acid-base reaction.
　ステップＳ１３１の共沈反応中は、反応系のｐＨを９．０以上１１．５以下となるようにすることが好ましい。 During the coprecipitation reaction in step S131, it is preferable that the pH of the reaction system is 9.0 or more and 11.5 or less.
　たとえばアルカリ溶液を反応槽に入れ酸溶液を反応槽へ滴下する場合、反応槽の水溶液のｐＨを上記条件の範囲に維持するとよい。また酸溶液を反応槽に入れておき、アルカリ溶液を滴下する場合も、同様である。酸溶液またはアルカリ溶液の滴下速度は、反応槽の溶液が２００ｍＬ以上３５０ｍＬ以下の場合、０．０１ｍＬ／分以下とするとｐＨ条件を制御しやすく好ましい。反応槽は反応容器等を有する。 For example, when an alkaline solution is placed in a reaction tank and an acid solution is dropped into the reaction tank, it is preferable to maintain the pH of the aqueous solution in the reaction tank within the range of the above conditions. The same applies when an acid solution is placed in a reaction tank and an alkaline solution is added dropwise. When the amount of solution in the reaction tank is 200 mL or more and 350 mL or less, the dropping rate of the acid solution or alkaline solution is preferably 0.01 mL/min or less because pH conditions can be easily controlled. The reaction tank has a reaction container and the like.
　反応槽では攪拌手段を用いて水溶液を攪拌しておくとよい。攪拌手段としてはスターラーまたは攪拌翼等の回転による攪拌が挙げられる。攪拌翼は２枚以上６枚以下設けることができ、たとえば４枚の攪拌翼とする場合、上方からみて十字状に配置するとよい。攪拌手段の回転数は、８００ｒｐｍ以上１２００ｒｐｍ以下とするとよい。また反応槽にバッフル板を設け、攪拌の方向および流速を変化させてもよい。バッフル板を設けることで混合効率が向上し、より均一な複合水酸化物の粒子を合成することができる。 It is preferable to stir the aqueous solution using a stirring means in the reaction tank. Examples of stirring means include stirring by rotation of a stirrer or stirring blades. Two or more stirring blades and six or less stirring blades can be provided. For example, when four stirring blades are provided, they are preferably arranged in a cross shape when viewed from above. The rotation speed of the stirring means is preferably 800 rpm or more and 1200 rpm or less. Alternatively, a baffle plate may be provided in the reaction tank to change the stirring direction and flow rate. By providing a baffle plate, mixing efficiency is improved and more uniform composite hydroxide particles can be synthesized.
　反応槽の温度は５０℃以上９０℃以下となるように調整することが好ましい。アルカリ溶液または酸溶液の滴下は反応槽が当該温度になったのちに開始するとよい。 The temperature of the reaction tank is preferably adjusted to 50°C or more and 90°C or less. It is preferable to start dropping the alkaline solution or acid solution after the reaction tank has reached the desired temperature.
　また反応槽内は不活性雰囲気とするとよい。この場合の不活性雰囲気には窒素またはアルゴンを用いることができる。窒素雰囲気とする場合、窒素ガスを０．５Ｌ／分以上２Ｌ／分以下の流量で導入するとよい。 Also, it is preferable to create an inert atmosphere inside the reaction tank. The inert atmosphere in this case can be nitrogen or argon. When creating a nitrogen atmosphere, nitrogen gas is preferably introduced at a flow rate of 0.5 L/min or more and 2 L/min or less.
　また反応槽には還流冷却器を配置するとよい。還流冷却器により、窒素ガスを反応槽から放出させることができ、水蒸気は反応槽に戻すことができる。 It is also advisable to arrange a reflux condenser in the reaction tank. A reflux condenser allows nitrogen gas to be vented from the reactor and water vapor to be returned to the reactor.
　上記の共沈反応により、遷移金属Ｍを有する複合水酸化物９８が沈殿する。 Through the above coprecipitation reaction, composite hydroxide 98 containing transition metal M is precipitated.
＜ステップＳ１３２＞
　複合水酸化物９８を回収するために、図６ＡのステップＳ１３２に示すように濾過を行うことが好ましい。濾過は吸引濾過が好ましい。濾過の際、反応槽に沈殿した反応生成物を純水で洗浄した後に、有機溶媒（例えばアセトン等）を用いてもよい。 <Step S132>
In order to recover the composite hydroxide 98, it is preferable to perform filtration as shown in step S132 of FIG. 6A. The filtration is preferably suction filtration. During filtration, an organic solvent (such as acetone) may be used after washing the reaction product precipitated in the reaction tank with pure water.
＜ステップＳ１３３＞
　図６ＡのステップＳ１３３に示すように、濾過後の複合水酸化物９８は乾燥させるとよい。たとえば６０℃以上２００℃以下の真空下にて、０．５時間以上２０時間以下で乾燥させる。たとえば１２時間乾燥させることができる。このようにして複合水酸化物９８を得ることができる。 <Step S133>
As shown in step S133 in FIG. 6A, the filtered composite hydroxide 98 is preferably dried. For example, it is dried under vacuum at a temperature of 60° C. or more and 200° C. or less for 0.5 hours or more and 20 hours or less. For example, it can be dried for 12 hours. In this way, composite hydroxide 98 can be obtained.
　このようにして、遷移金属Ｍを有する複合水酸化物９８を得ることができる。本明細書等において複合水酸化物９８とは、複数種の金属の水酸化物をいうこととする。複合水酸化物９８は、正極活物質１０１の前駆体ということができる。 In this way, composite hydroxide 98 containing transition metal M can be obtained. In this specification and the like, the composite hydroxide 98 refers to hydroxides of multiple types of metals. The composite hydroxide 98 can be said to be a precursor of the positive electrode active material 101.
＜ステップＳ１４１＞
　次に図６ＢのステップＳ１４１として、リチウム源および添加元素源を用意する。 <Step S141>
Next, in step S141 of FIG. 6B, a lithium source and an additive element source are prepared.
　たとえばニッケル、コバルトおよびマンガンの原子の和を１としたとき、リチウムを１．０（原子数比）近傍とすることがより好ましい。 For example, when the sum of nickel, cobalt, and manganese atoms is 1, it is more preferable that lithium be around 1.0 (atomic ratio).
　リチウム源としてはたとえば水酸化リチウム、炭酸リチウム、フッ化リチウムまたは硝酸リチウムを用いることができる。特に水酸化リチウム（融点４６２°Ｃ）などリチウム化合物のなかでは融点の低い材料を用いると好ましい。ニッケルの割合が高い正極活物質は、コバルト酸リチウム等と比較してカチオンミキシングが生じやすいため、ステップＳ１４３などの加熱を低温で行う必要がある。そのため融点の低い材料を用いることが好ましい。 As the lithium source, for example, lithium hydroxide, lithium carbonate, lithium fluoride, or lithium nitrate can be used. In particular, it is preferable to use a material with a low melting point among lithium compounds, such as lithium hydroxide (melting point: 462°C). Since cation mixing occurs more easily in a positive electrode active material containing a high proportion of nickel than in lithium cobalt oxide, etc., it is necessary to perform heating in step S143 and the like at a low temperature. Therefore, it is preferable to use a material with a low melting point.
　またリチウム源の粒径が小さい方が、反応が良好に進みやすく好ましい。たとえば流動層式ジェットミルを用いて微粒子化したリチウム源を用いることができる。ここでいう粒径とは、粒度分布の平均粒径（平均粒子径とも呼ぶ）である。 Furthermore, it is preferable that the particle size of the lithium source is small because the reaction tends to proceed well. For example, a lithium source made into fine particles using a fluidized bed jet mill can be used. The particle size here is the average particle size (also called average particle size) of the particle size distribution.
　また添加元素源としては、フッ素、アルミニウム、マグネシウム、チタン、カルシウム、ジルコニウムから選ばれる一または二以上を有する化合物を用いることができる。 Further, as the additive element source, a compound having one or more selected from fluorine, aluminum, magnesium, titanium, calcium, and zirconium can be used.
　フッ素源として例えばフッ化リチウム（ＬｉＦ）、フッ化マグネシウム（ＭｇＦ２）、フッ化アルミニウム（ＡｌＦ３）、フッ化チタン（ＴｉＦ４）、フッ化コバルト（ＣｏＦ２、ＣｏＦ３）、フッ化ニッケル（ＮｉＦ２）、フッ化ジルコニウム（ＺｒＦ４）、フッ化バナジウム（ＶＦ５）、フッ化マンガン、フッ化鉄、フッ化クロム、フッ化ニオブ、フッ化亜鉛（ＺｎＦ２）、フッ化カルシウム（ＣａＦ２）、フッ化ナトリウム（ＮａＦ）、フッ化カリウム（ＫＦ）、フッ化バリウム（ＢａＦ２）、フッ化セリウム（ＣｅＦ３、ＣｅＦ４）、フッ化ランタン（ＬａＦ３）、又は六フッ化アルミニウムナトリウム（Ｎａ３ＡｌＦ６）等を用いることができる。なかでも、フッ化リチウムは融点が８４８℃と比較的低く、後述する加熱工程で融剤として機能しやすいため好ましい。 Examples of fluorine sources include lithium fluoride (LiF), magnesium fluoride (MgF 2 ), aluminum fluoride (AlF 3 ), titanium fluoride (TiF 4 ), cobalt fluoride (CoF 2 , CoF 3 ), and nickel fluoride ( NiF 2 ), zirconium fluoride (ZrF 4 ), vanadium fluoride (VF 5 ), manganese fluoride, iron fluoride, chromium fluoride, niobium fluoride, zinc fluoride (ZnF 2 ), calcium fluoride (CaF 2 ) ), sodium fluoride (NaF), potassium fluoride (KF), barium fluoride (BaF 2 ), cerium fluoride (CeF 3 , CeF 4 ), lanthanum fluoride (LaF 3 ), or sodium aluminum hexafluoride ( Na 3 AlF 6 ), etc. can be used. Among these, lithium fluoride is preferable because it has a relatively low melting point of 848° C. and easily functions as a flux in the heating step described below.
　またフッ素源は気体でもよく、フッ素（Ｆ２）、フッ化炭素、フッ化硫黄、又はフッ化酸素（ＯＦ２、Ｏ２Ｆ２、Ｏ３Ｆ２、Ｏ４Ｆ２、Ｏ５Ｆ２、Ｏ６Ｆ２、Ｏ２Ｆ）等を用い、後述する加熱工程において雰囲気中に混合させてもよい。また上述したフッ素源を複数用いてもよい。 Further, the fluorine source may be a gas, such as fluorine (F 2 ), fluorocarbon, sulfur fluoride, or fluorinated oxygen (OF 2 , O 2 F 2 , O 3 F 2 , O 4 F 2 , O 5 F 2 , O 6 F 2 , O 2 F) or the like may be used and mixed in the atmosphere in the heating step described later. Further, a plurality of the above-mentioned fluorine sources may be used.
　アルミニウム源としては例えば酸化アルミニウム、水酸化アルミニウム、フッ化アルミニウムをはじめとするアルミニウム化合物、および／または金属アルミニウムを用いることができる。 As the aluminum source, for example, aluminum compounds such as aluminum oxide, aluminum hydroxide, and aluminum fluoride, and/or metal aluminum can be used.
　マグネシウム源としては例えばフッ化マグネシウム、酸化マグネシウム、水酸化マグネシウム、又は炭酸マグネシウムをはじめとするマグネシウム化合物、および／または金属マグネシウムを用いることができる。また上述したマグネシウム源を複数用いてもよい。 As the magnesium source, for example, magnesium compounds such as magnesium fluoride, magnesium oxide, magnesium hydroxide, or magnesium carbonate, and/or magnesium metal can be used. Further, a plurality of the above-mentioned magnesium sources may be used.
　フッ化マグネシウムはフッ素源としてもマグネシウム源としても用いることができる。またフッ化リチウムはリチウム源としても用いることができる。 Magnesium fluoride can be used both as a fluorine source and as a magnesium source. Lithium fluoride can also be used as a lithium source.
　チタン源としては例えば、酸化チタン、水酸化チタン、フッ化チタンをはじめとするチタン化合物、および／または金属チタンを用いることができる。 As the titanium source, for example, titanium compounds such as titanium oxide, titanium hydroxide, and titanium fluoride, and/or titanium metal can be used.
　カルシウム源としては例えば、炭酸カルシウム、フッ化カルシウム、水酸化カルシウム、酸化カルシウムはじめとするカルシウム化合物、および／または金属カルシウムを用いることができる。 As the calcium source, for example, calcium compounds such as calcium carbonate, calcium fluoride, calcium hydroxide, and calcium oxide, and/or metallic calcium can be used.
　ジルコニウム源としては例えば、酸化ジルコニウム、水酸化ジルコニウム、フッ化ジルコニウムはじめとするジルコニウム化合物、および／または金属ジルコニウムを用いることができる。 As the zirconium source, for example, zirconium compounds such as zirconium oxide, zirconium hydroxide, and zirconium fluoride, and/or metal zirconium can be used.
　上述したようにフッ化リチウムは後の加熱工程で融剤として機能しうる。たとえば、フッ素源およびマグネシウム源であるフッ化マグネシウムと、融剤であるフッ化リチウムの相図を図８（非特許文献１の図７より引用し加筆）に示す。図８のようにＬｉＦとＭｇＦ２の共融点Ｐは７４２℃付近（Ｔ１）である。 As mentioned above, lithium fluoride can function as a flux in the subsequent heating step. For example, a phase diagram of magnesium fluoride, which is a fluorine source and a magnesium source, and lithium fluoride, which is a fluxing agent, is shown in FIG. 8 (cited and added from FIG. 7 of Non-Patent Document 1). As shown in FIG. 8, the eutectic point P of LiF and MgF 2 is around 742° C. (T1).
　またフッ素源およびニッケル源であるフッ化ニッケルと、融剤であるフッ化リチウムの相図を図９（非特許文献２、図３より引用）に示す。図９のようにＬｉＦとＮｉＦ２の共融点は例えば、ＮｉＦ２の含有量（図９の横軸ｘ）が０．２において、１０６０［Ｋ］乃至１０６５［Ｋ］の範囲内（７８７℃乃至７９２℃の範囲内）にある。 Further, a phase diagram of nickel fluoride, which is a fluorine source and a nickel source, and lithium fluoride, which is a flux, is shown in FIG. 9 (cited from Non-Patent Document 2, FIG. 3). As shown in FIG. 9 , the eutectic point of LiF and NiF 2 is within the range of 1060 [K] to 1065 [K] (787°C to within the range of 792°C).
　またフッ素源およびアルミニウム源であるフッ化アルミニウムと、融剤であるフッ化リチウムの共融点は、図１０（非特許文献３より引用）に示すように、ＬｉＦ：ＡｌＦ３＝６４：３６（ｍｏｌ比）において７２０℃付近である。 In addition, the eutectic point of aluminum fluoride, which is a fluorine source and an aluminum source, and lithium fluoride, which is a flux, is as shown in FIG . The temperature is around 720°C.
　融剤として機能しうるフッ化リチウムと、フッ化アルミニウムをはじめとする添加元素源と、を混合して添加することで、後の加熱工程においてこれらが複合酸化物の表層部の一部と共に溶け、融解層を形成する。該融解層が加熱工程後に冷却されることで、たとえばＡＬＤ（Ａｔｏｍｉｃ　ｌａｙｅｒ　ｄｅｐｏｓｉｔｉｏｎ）法で形成された膜のように、薄く緻密なバリア膜となる。より具体的には、添加元素が良好な添加元素の濃度および分布を有して固溶し、結晶の配向が内部と概略一致するバリア膜となる。 By mixing and adding lithium fluoride, which can function as a flux, and an additive element source such as aluminum fluoride, they can be melted together with part of the surface layer of the composite oxide in the subsequent heating process. , forming a molten layer. When the molten layer is cooled after the heating step, it becomes a thin and dense barrier film, such as a film formed by an ALD (Atomic Layer Deposition) method. More specifically, the additive elements are dissolved in solid solution with good concentration and distribution of the additive elements, resulting in a barrier film in which the crystal orientation roughly matches that of the inside.
　図８乃至図１０には、それぞれの添加元素源と、融剤との共融点を示すが、本発明の一態様の正極活物質の作製方法において、フッ化マグネシウム、フッ化ニッケル、フッ化アルミニウム及びフッ化リチウムから選ばれる３つ以上の材料を共に混合する場合には、さらなる融点降下も生じうる。 8 to 10 show the eutectic points of the respective additive element sources and the flux. Further melting point depression may also occur when three or more materials selected from lithium fluoride and lithium fluoride are mixed together.
＜ステップＳ１４２＞
　次に図６ＢのステップＳ１４２として、複合水酸化物９８とリチウム源とを混合する。混合は乾式または湿式で行うことができる。混合には例えばボールミル、ビーズミル等を用いることができる。ボールミルを用いる場合は、例えばメディアとしてジルコニアボールを用いることが好ましい。また、ボールミル、またはビーズミル等を用いる場合、メディアまたは材料からのコンタミネーションを抑制するために、周速を１００ｍｍ／秒以上２０００ｍｍ／秒以下とすることが好ましい。混合と同時にコバルト化合物及びリチウム化合物は粉砕されることがある。 <Step S142>
Next, in step S142 in FIG. 6B, the composite hydroxide 98 and a lithium source are mixed. Mixing can be done dry or wet. For example, a ball mill, a bead mill, etc. can be used for mixing. When using a ball mill, it is preferable to use zirconia balls as the media, for example. Further, when using a ball mill, bead mill, etc., the peripheral speed is preferably 100 mm/sec to 2000 mm/sec in order to suppress contamination from media or materials. At the same time as mixing, the cobalt compound and the lithium compound may be crushed.
＜ステップＳ１４３＞
　次に複合水酸化物９８とリチウム源の混合物に加熱を行う。他の加熱工程との区別のために、図６Ｂおよび図７ではステップＳ１４３を第１の加熱、ステップＳ１４５を第２の加熱、ステップＳ１５３を第３の加熱という場合がある。 <Step S143>
Next, the mixture of the composite hydroxide 98 and the lithium source is heated. To distinguish from other heating steps, in FIGS. 6B and 7, step S143 may be referred to as first heating, step S145 as second heating, and step S153 as third heating.
　これらの加熱を行う焼成装置としては、電気炉、またはロータリーキルン炉を用いることができる。加熱の際に用いる、るつぼ、サヤ、セッター、容器は不純物を放出しにくい材質であると好ましい。たとえば純度が９９．９％の酸化アルミニウムのるつぼを用いるとよい。量産する場合には例えばムライト・コーディライト（Ａｌ２Ｏ３・ＳｉＯ２・ＭｇＯ）のサヤを用いるとよい。また、これらの容器に蓋をした状態で加熱することが好ましい。 An electric furnace or a rotary kiln can be used as a firing device for performing this heating. The crucible, sheath, setter, and container used during heating are preferably made of materials that do not easily release impurities. For example, an aluminum oxide crucible with a purity of 99.9% may be used. For mass production, for example, mullite/cordierite (Al 2 O 3 .SiO 2 .MgO) pods may be used. Moreover, it is preferable to heat these containers with a lid on.
　ステップＳ１４３の加熱は、温度は４００℃以上７５０℃以下が好ましく、６５０℃以上７５０℃以下がより好ましい。また、ステップＳ１４３の加熱の時間は、１時間以上３０時間以下が好ましく、２時間以上２０時間以下がより好ましい。 The temperature of the heating in step S143 is preferably 400°C or more and 750°C or less, more preferably 650°C or more and 750°C or less. Further, the heating time in step S143 is preferably 1 hour or more and 30 hours or less, more preferably 2 hours or more and 20 hours or less.
　加熱雰囲気は、酸素を有する雰囲気、又はいわゆる乾燥空気であって水が少ない酸素含有雰囲気（例えば露点が−５０℃以下、より好ましくは露点が−８０℃以下）であることが好ましい。 The heating atmosphere is preferably an oxygen-containing atmosphere or an oxygen-containing atmosphere that is so-called dry air and contains little water (for example, a dew point of -50°C or lower, more preferably a dew point of -80°C or lower).
　またステップＳ１４４として、加熱の後に解砕工程を有することが好ましい。解砕はたとえば乳鉢で行うことができる。さらに、ふるいを用いて分級してもよい。 Furthermore, it is preferable to include a crushing step after heating as step S144. Disintegration can be carried out, for example, in a mortar. Furthermore, it may be classified using a sieve.
　次いで、ステップＳ１４５として、加熱を行う。ステップＳ１４５の加熱の温度は、ステップＳ１４３の加熱の温度より高いことが好ましい。ステップＳ１４３の加熱を仮焼成と記し、ステップＳ１４５の加熱を本焼成と記すことがある。 Next, in step S145, heating is performed. It is preferable that the heating temperature in step S145 is higher than the heating temperature in step S143. The heating in step S143 may be referred to as preliminary firing, and the heating in step S145 may be referred to as main firing.
　ステップＳ１４５の加熱は、温度は７５０℃より高く１０５０℃以下が好ましい。また、ステップＳ１４５の加熱の時間は、１時間以上３０時間以下が好ましく、２時間以上２０時間以下がより好ましい。 The temperature of the heating in step S145 is preferably higher than 750°C and lower than 1050°C. Further, the heating time in step S145 is preferably 1 hour or more and 30 hours or less, more preferably 2 hours or more and 20 hours or less.
　またステップＳ１４６として、加熱の後に解砕工程を有することが好ましい。解砕はたとえば乳鉢で行うことができる。さらに、ふるいを用いて分級してもよい。以上の工程により、正極活物質１０１を得る。 Furthermore, it is preferable to include a crushing step after heating as step S146. Disintegration can be carried out, for example, in a mortar. Furthermore, it may be classified using a sieve. Through the above steps, a positive electrode active material 101 is obtained.
≪正極活物質の作製方法２≫
　図６Ａおよび図６Ｂでは、添加元素源を加える工程が１回である作製方法について説明したが、本発明の一態様はこれに限らない。複数回に分けて添加元素源を加えてもよい。図７を用いて、２回にわけて添加元素源を加える正極活物質の作製方法について説明する。主に図６Ａおよび図６Ｂで説明した作製方法と異なる点について説明する。 ≪Method for producing positive electrode active material 2≫
Although FIGS. 6A and 6B describe a manufacturing method in which the step of adding an additive element source is performed once, one embodiment of the present invention is not limited to this. The additive element source may be added in multiple portions. A method for producing a positive electrode active material in which an additive element source is added in two steps will be described with reference to FIG. Mainly, points different from the manufacturing method explained with reference to FIGS. 6A and 6B will be explained.
＜ステップＳ１１１乃至ステップＳ１３３＞
　まず図６Ａと同様にステップＳ１１１乃至ステップＳ１３３を経て複合水酸化物９８を作製する。 <Step S111 to Step S133>
First, as in FIG. 6A, a composite hydroxide 98 is produced through steps S111 to S133.
＜ステップＳ１４１乃至ステップＳ１４６＞
　次に図６ＢのステップＳ１４１乃至ステップＳ１４６と同様の工程で、複合酸化物９９を得る。 <Step S141 to Step S146>
Next, a composite oxide 99 is obtained through steps similar to steps S141 to S146 in FIG. 6B.
＜ステップＳ１５１＞
　次に図７のステップＳ１５１として、添加元素源を用意する。添加元素源は、ステップＳ１４１の記載を参照することができる。 <Step S151>
Next, in step S151 in FIG. 7, an additive element source is prepared. For the additional element source, the description in step S141 can be referred to.
＜ステップＳ１５２＞
　次に複合酸化物９９と、添加元素源とを混合する。混合は、ステップＳ１４２の記載を参照することができる。 <Step S152>
Next, the composite oxide 99 and the additive element source are mixed. For mixing, the description of step S142 can be referred to.
＜ステップＳ１５３＞
　次に複合酸化物９９と添加元素源の混合物に加熱を行う。ステップＳ１５３の加熱は正極活物質１０１の結晶子サイズを大きくするため、十分に高い温度であることが好ましいが、その範囲は遷移金属Ｍの組成により異なる場合がある。 <Step S153>
Next, the mixture of the composite oxide 99 and the additive element source is heated. The heating in step S153 is preferably at a sufficiently high temperature in order to increase the crystallite size of the positive electrode active material 101, but the temperature range may vary depending on the composition of the transition metal M.
　遷移金属Ｍのうちニッケルの占める割合が高い、たとえば７０％以上である場合は、７５０℃以上が好ましい。一方でステップＳ１５３の加熱温度が高すぎるとニッケル等の遷移金属Ｍが２価に還元される等の恐れがある。そのため、たとえば９５０℃以下が好ましく、９２０℃以下がより好ましく、９００℃以下がさらに好ましい。 When the proportion of nickel in the transition metal M is high, for example 70% or more, the temperature is preferably 750°C or higher. On the other hand, if the heating temperature in step S153 is too high, there is a risk that the transition metal M such as nickel may be reduced to a divalent metal. Therefore, for example, the temperature is preferably 950°C or lower, more preferably 920°C or lower, and even more preferably 900°C or lower.
　遷移金属Ｍのうちニッケルの占める割合が０％を超えて７０％未満の場合は、たとえば８５０℃以上が好ましく、９００℃以上がより好ましく、１０００℃以下がより好ましい。一方でステップＳ１５３の加熱温度が高すぎると上記と同様のデメリットが生じる恐れがあり、１０５０℃以下が好ましい。加熱のその他の条件は、ステップＳ１４３の記載を参照することができる。 When the proportion of nickel in the transition metal M is more than 0% and less than 70%, the temperature is preferably 850°C or higher, more preferably 900°C or higher, and even more preferably 1000°C or lower. On the other hand, if the heating temperature in step S153 is too high, the same disadvantages as described above may occur, so it is preferably 1050° C. or lower. For other heating conditions, refer to the description of step S143.
　またステップＳ１５４として、加熱の後に解砕工程を有することが好ましい。解砕はステップＳ１４４の記載を参照することができる。 Furthermore, it is preferable to include a crushing step after heating as step S154. Regarding the crushing, the description of step S144 can be referred to.
　また図７ではステップＳ１５１で添加元素源を混合した後、ステップＳ１５３の加熱をする方法について説明するが、本発明の一態様はこれに限らない。ステップＳ１５３の加熱として２回以上の加熱を行ってもよい。 Further, although FIG. 7 describes a method of heating in step S153 after mixing the additive element source in step S151, one embodiment of the present invention is not limited to this. Heating may be performed two or more times as the heating in step S153.
　以上の工程により、正極活物質１０１を作製することができる。 Through the above steps, the positive electrode active material 101 can be produced.
　なお本実施の形態では、リチウム源と共に、またはリチウム源を加えた後に添加元素を加える作製方法について説明したが、本発明の一態様はこれに限らず、他の工程で添加元素を加えてもよい。たとえば遷移金属Ｍ源と共に添加元素を加えてもよい。またリチウムと遷移金属Ｍを有する複合酸化物を作製した後に添加元素を加えてもよい。またあらかじめ作製されたリチウムと遷移金属Ｍを有する複合酸化物について、添加元素を加えてもよい。添加元素を加える工程を変えることで、正極活物質中の添加元素の深さ方向のプロファイルを変えることができる場合がある。 Note that although this embodiment mode describes a manufacturing method in which the additive element is added together with the lithium source or after the lithium source is added, one embodiment of the present invention is not limited to this. good. For example, additive elements may be added together with the transition metal M source. Further, the additive element may be added after the composite oxide containing lithium and the transition metal M is produced. Additionally, additional elements may be added to the composite oxide containing lithium and transition metal M that has been prepared in advance. By changing the process of adding the additive element, it may be possible to change the depth profile of the additive element in the positive electrode active material.
　本実施の形態は他の実施の形態と自由に組み合わせることができる。 This embodiment can be freely combined with other embodiments.
（実施の形態２）
　本実施の形態では、先の実施の形態で説明した作製方法によって作製された正極活物質１０１を用いる二次電池に関し、形状の例を説明する。 (Embodiment 2)
In this embodiment, examples of shapes will be described with respect to a secondary battery using the positive electrode active material 101 manufactured by the manufacturing method described in the previous embodiment.
［コイン型二次電池］
　コイン型の二次電池の一例について説明する。図１１Ａはコイン型（単層偏平型）の二次電池の分解斜視図であり、図１１Ｂは、外観図であり、図１１Ｃは、その断面図である。コイン型の二次電池は主に小型の電子機器に用いられる。 [Coin type secondary battery]
An example of a coin-shaped secondary battery will be described. FIG. 11A is an exploded perspective view of a coin-shaped (single-layer flat type) secondary battery, FIG. 11B is an external view, and FIG. 11C is a cross-sectional view thereof. Coin-shaped secondary batteries are mainly used in small electronic devices.
　なお、図１１Ａでは、わかりやすくするために部材の重なり（上下関係、及び位置関係）がわかるように模式図としている。従って図１１Ａと図１１Ｂは完全に一致する対応図とはしていない。 Note that, in order to make it easier to understand, FIG. 11A is a schematic diagram so that the overlapping (vertical relationship and positional relationship) of members can be seen. Therefore, FIG. 11A and FIG. 11B are not completely corresponding diagrams.
　図１１Ａでは、正極３０４、セパレータ３１０、負極３０７、スペーサ３２２、ワッシャー３１２を重ねている。これらを負極缶３０２と正極缶３０１とガスケットで封止している。なお、図１１Ａにおいて、封止のためのガスケットは図示していない。スペーサ３２２、ワッシャー３１２は、正極缶３０１と負極缶３０２を圧着する際に、内部を保護または缶内の位置を固定するために用いられている。スペーサ３２２、ワッシャー３１２はステンレスまたは絶縁材料を用いる。 In FIG. 11A, the positive electrode 304, separator 310, negative electrode 307, spacer 322, and washer 312 are stacked. These are sealed with a negative electrode can 302 and a positive electrode can 301 with a gasket. Note that in FIG. 11A, a gasket for sealing is not shown. The spacer 322 and the washer 312 are used to protect the inside or fix the position inside the can when the positive electrode can 301 and the negative electrode can 302 are crimped together. The spacer 322 and washer 312 are made of stainless steel or an insulating material.
　正極集電体３０５上に正極活物質層３０６が形成された積層構造を正極３０４としている。集電体上に、正極活物質１０１を含むスラリーを塗工し、乾燥させて正極活物質層３０６を形成する。正極活物質層３０６を形成した後にプレスを行ってもよい。スラリーは、正極活物質１０１の他に導電材、バインダ、溶媒を有する。なお、導電材としては、黒鉛、炭素繊維などの炭素材料を用いる。 A positive electrode 304 has a laminated structure in which a positive electrode active material layer 306 is formed on a positive electrode current collector 305 . A slurry containing the positive electrode active material 101 is applied onto the current collector and dried to form the positive electrode active material layer 306. Pressing may be performed after forming the positive electrode active material layer 306. The slurry includes a conductive material, a binder, and a solvent in addition to the positive electrode active material 101. Note that a carbon material such as graphite or carbon fiber is used as the conductive material.
［導電材］
　導電材は、代表的には炭素材料又は金属材料が用いられる。導電材は粒子状をなし、当該粒子状の導電材としてカーボンブラック（ファーネスブラック、アセチレンブラック、黒鉛など）がある。カーボンブラックは正極活物質より小さな粒径を有するものが多い。導電材は繊維状をなしてもよく、当該繊維状の導電助剤としてカーボンナノチューブ（ＣＮＴ）、ＶＧＣＦ（登録商標）がある。導電材はシート状のものがあり、例えばシート状の導電助剤として多層グラフェンがある。シート状の導電助剤は正極の断面において、糸状に見えることがある。 [Conductive material]
A carbon material or a metal material is typically used as the conductive material. The conductive material is in the form of particles, and examples of the conductive material in the form of particles include carbon black (furnace black, acetylene black, graphite, etc.). Carbon black often has a smaller particle size than the positive electrode active material. The conductive material may be in the form of fibers, and carbon nanotubes (CNTs) and VGCF (registered trademark) are examples of the conductive aids in the form of fibers. There are sheet-like conductive materials, such as multilayer graphene as a sheet-like conductive aid. The sheet-like conductive additive may appear thread-like in the cross section of the positive electrode.
　粒子状の導電材は正極活物質等の隙間に入り込むことが可能であり、また凝集しやすい。そのため粒子状の導電材は近くに配置された正極活物質間の導電パスを補助することができる。繊維状の導電材は、折れ曲がった領域も有するが、正極活物質より大きなものとなる。そのため繊維状の導電材は、隣接した正極活物質間に加えて、離れた正極活物質間の導電パスを補助することもできる。このように導電助剤は二以上の形状のものを混合するとよい。 Particulate conductive materials can get into gaps in the positive electrode active material, etc., and are likely to aggregate. Therefore, the particulate conductive material can assist in forming a conductive path between the cathode active materials disposed nearby. The fibrous conductive material also has a bent region, but it is larger than the positive electrode active material. Therefore, the fibrous conductive material can assist the conductive path not only between adjacent positive electrode active materials but also between distant positive electrode active materials. In this way, it is preferable to mix two or more shapes of conductive aids.
　シート状の導電材として多層グラフェンを用い、粒子状の導電材としてカーボンブラックを用いた場合、これらが混合されたスラリーの状態で、カーボンブラックの重量が多層グラフェンの１．５倍以上２０倍以下、好ましくは２倍以上９．５倍以下の重量となるとよい。多層グラフェンとカーボンブラックの混合割合を上記範囲とすることで、急速充電に対応することができる。 When multilayer graphene is used as a sheet-like conductive material and carbon black is used as a particulate conductive material, in the state of a slurry in which these are mixed, the weight of carbon black is 1.5 times or more and 20 times or less of the multilayer graphene. , preferably 2 times or more and 9.5 times or less in weight. By setting the mixing ratio of multilayer graphene and carbon black within the above range, it is possible to support rapid charging.
　本明細書等においてグラフェンは多層グラフェン、マルチグラフェンを含む。別言すると、グラフェンとは、炭素を有し、平板状、シート状等の形状を有し、炭素６員環で形成された二次元的構造を有するものをいう。該炭素６員環で形成された二次元的構造は炭素シートと呼ぶ場合がある。 In this specification, graphene includes multilayer graphene and multigraphene. In other words, graphene refers to something that contains carbon, has a shape such as a flat plate or a sheet, and has a two-dimensional structure formed of a six-membered carbon ring. The two-dimensional structure formed by the six-membered carbon ring is sometimes called a carbon sheet.
　本明細書等においてグラフェン化合物とは、酸化グラフェン、多層酸化グラフェン、マルチ酸化グラフェン、還元された酸化グラフェン、還元された多層酸化グラフェン、還元されたマルチ酸化グラフェン、グラフェン量子ドット等を含む。別言すると、グラフェン化合物は官能基を有してもよい。またグラフェン又はグラフェン化合物は屈曲した形状を有することが好ましい。またグラフェン又はグラフェン化合物は丸まっていてもよく、丸まったグラフェンをカーボンナノファイバーと呼ぶことがある。本明細書等において酸化グラフェンとは、炭素と、酸素を有し、シート状の形状を有し、官能基、特にエポキシ基、カルボキシ基またはヒドロキシ基を有するものをいう。 In this specification and the like, graphene compounds include graphene oxide, multilayer graphene oxide, multilayer graphene oxide, reduced graphene oxide, reduced multilayer graphene oxide, reduced multilayer graphene oxide, graphene quantum dots, and the like. In other words, the graphene compound may have a functional group. Further, it is preferable that the graphene or graphene compound has a bent shape. Further, graphene or a graphene compound may be rounded, and rounded graphene is sometimes called carbon nanofiber. In this specification and the like, graphene oxide refers to one that contains carbon and oxygen, has a sheet-like shape, and has a functional group, particularly an epoxy group, a carboxy group, or a hydroxy group.
　グラフェン化合物として、フッ素含有グラフェンを用いてもよい。グラフェン化合物中にあるフッ素は、表面に吸着しているとよい。またフッ素含有グラフェンは、グラフェンとフッ素化合物が接触すること（フッ化処理と呼ぶ）により作製することができる。フッ化処理にはフッ素（Ｆ２）又はフッ素化合物を用いるとよい。フッ素化合物として、フッ化水素、フッ化ハロゲン（ＣｌＦ３、ＩＦ５等）、ガス状フッ化物（ＢＦ３、ＮＦ３、ＰＦ５、ＳｉＦ４、ＳＦ６等）、金属フッ化物（ＬｉＦ、ＮｉＦ２、ＡｌＦ３、ＭｇＦ２等）等が好ましい。フッ化処理には、ガス状フッ化物を用いると好ましく、ガス状フッ化物を不活性ガスで希釈してもよい。フッ化処理の温度は室温がよいが、当該室温が含まれる０℃以上２５０℃以下がよい。０℃以上でフッ化処理を行うと、グラフェンの表面にフッ素を吸着させることができる。 Fluorine-containing graphene may be used as the graphene compound. Fluorine in the graphene compound is preferably adsorbed on the surface. Further, fluorine-containing graphene can be produced by bringing graphene and a fluorine compound into contact (referred to as fluorination treatment). Fluorine (F 2 ) or a fluorine compound may be used for the fluorination treatment. Examples of fluorine compounds include hydrogen fluoride, fluorinated halogens ( ClF3 , IF5, etc.), gaseous fluorides ( BF3 , NF3 , PF5 , SiF4 , SF6 , etc.), metal fluorides (LiF, NiF2, etc. ). , AlF 3 , MgF 2 , etc.) are preferred. In the fluorination treatment, it is preferable to use a gaseous fluoride, and the gaseous fluoride may be diluted with an inert gas. The temperature of the fluorination treatment is preferably room temperature, and is preferably 0° C. or higher and 250° C. or lower, which includes the room temperature. When the fluorination treatment is performed at 0° C. or higher, fluorine can be adsorbed onto the surface of graphene.
　グラフェン化合物は、高い導電性を有するという優れた電気特性と、高い柔軟性および高い機械的強度を有するという優れた物理特性と、を有する場合がある。また、グラフェン化合物はシート状の形状を有する。グラフェン化合物は、湾曲面を有する場合があり、接触抵抗の低い面接触を可能とする。また、薄くても導電性が非常に高い場合があり、少ない量で効率よく活物質層内で導電パスを形成することができる。そのため、グラフェン化合物を導電材として用いることにより、活物質と導電材との接触面積を増大させることができる。グラフェン化合物は活物質の８０％以上の面積を覆っているとよい。なお、グラフェン化合物が活物質粒子の少なくとも一部にまとわりついていると好ましい。また、グラフェン化合物が活物質粒子の少なくとも一部の上に重なっていると好ましい。また、グラフェン化合物の形状が活物質粒子の形状の少なくとも一部に一致していると好ましい。該活物質粒子の形状とは、たとえば、単一の活物質粒子が有する凹凸、または複数の活物質粒子によって形成される凹凸をいう。また、グラフェン化合物が活物質粒子の少なくとも一部を囲んでいることが好ましい。また、グラフェン化合物は穴が空いていてもよい。 Graphene compounds may have excellent electrical properties such as high conductivity, and excellent physical properties such as high flexibility and high mechanical strength. Further, the graphene compound has a sheet-like shape. Graphene compounds may have curved surfaces, allowing surface contact with low contact resistance. Further, even if it is thin, it may have very high conductivity, and a conductive path can be efficiently formed within the active material layer with a small amount. Therefore, by using a graphene compound as a conductive material, the contact area between the active material and the conductive material can be increased. The graphene compound preferably covers 80% or more of the area of the active material. Note that it is preferable that the graphene compound clings to at least a portion of the active material particles. Further, it is preferable that the graphene compound overlaps at least a portion of the active material particles. Further, it is preferable that the shape of the graphene compound matches at least a portion of the shape of the active material particles. The shape of the active material particles refers to, for example, the unevenness of a single active material particle or the unevenness formed by a plurality of active material particles. Further, it is preferable that the graphene compound surrounds at least a portion of the active material particles. Further, the graphene compound may have holes.
　粒子径の小さい活物質粒子、例えば１μｍ以下の活物質粒子を用いる場合には、活物質粒子の比表面積が大きく、活物質粒子同士を繋ぐ導電パスがより多く必要となる。このような場合には、少ない量でも効率よく導電パスを形成することができるグラフェン化合物を用いると好ましい。 When using active material particles with a small particle size, for example, active material particles of 1 μm or less, the specific surface area of the active material particles is large, and more conductive paths connecting the active material particles are required. In such a case, it is preferable to use a graphene compound that can efficiently form a conductive path even in a small amount.
　上述のような性質を有するため、急速充電および急速放電が要求される二次電池には、グラフェン化合物を導電材として用いることが特に有効である。例えば２輪または４輪の車両用二次電池、ドローン用二次電池などは急速充電および急速放電特性が要求される場合がある。またモバイル電子機器などでは急速充電特性が要求される場合がある。急速充放電とは、たとえば２００ｍＡ／ｇ、４００ｍＡ／ｇ、または１０００ｍＡ／ｇ以上の充電および放電をいうこととする。 Because of the properties described above, it is particularly effective to use graphene compounds as a conductive material for secondary batteries that require rapid charging and rapid discharging. For example, secondary batteries for two-wheeled or four-wheeled vehicles, secondary batteries for drones, etc. may be required to have rapid charging and rapid discharging characteristics. Furthermore, mobile electronic devices and the like may require quick charging characteristics. Rapid charging and discharging refers to charging and discharging at a rate of, for example, 200 mA/g, 400 mA/g, or 1000 mA/g or more.
　導電材としてフッ素含有アセチレンブラックを用いてもよい。フッ素含有アセチレンブラック中にあるフッ素は、表面に吸着しているとよい。またフッ素含有アセチレンブラックは、アセチレンブラックとフッ素化合物が接触すること（フッ化処理と呼ぶ）により作製することができる。フッ化処理についてはグラフェンで説明した内容を、アセチレンブラックに適用できる。 Fluorine-containing acetylene black may be used as the conductive material. The fluorine present in the fluorine-containing acetylene black is preferably adsorbed on the surface. Further, fluorine-containing acetylene black can be produced by bringing acetylene black into contact with a fluorine compound (referred to as fluorination treatment). Regarding the fluorination treatment, the content explained for graphene can be applied to acetylene black.
　導電材としてフッ素含有カーボンナノチューブ中にあるフッ素は、表面に吸着しているとよい。またフッ素含有カーボンナノチューブは、カーボンナノチューブとフッ素化合物が接触すること（フッ化処理と呼ぶ）により作製することができる。フッ化処理についてはグラフェンで説明した内容を、カーボンナノチューブに適用できる。 The fluorine present in the fluorine-containing carbon nanotubes as a conductive material is preferably adsorbed on the surface. Furthermore, fluorine-containing carbon nanotubes can be produced by bringing carbon nanotubes into contact with a fluorine compound (referred to as fluorination treatment). Regarding the fluorination treatment, the content explained for graphene can be applied to carbon nanotubes.
［バインダ］
　バインダとしては、例えば、スチレン−ブタジエンゴム（ＳＢＲ）、スチレン−イソプレン−スチレンゴム、アクリロニトリル−ブタジエンゴム、ブタジエンゴム、エチレン−プロピレン−ジエン共重合体などのゴム材料を用いることが好ましい。またバインダとして、フッ素ゴムを用いることができる。 [Binder]
As the binder, it is preferable to use rubber materials such as styrene-butadiene rubber (SBR), styrene-isoprene-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, and ethylene-propylene-diene copolymer. Furthermore, fluororubber can be used as the binder.
　また、バインダとしては、例えば水溶性の高分子を用いることが好ましい。水溶性の高分子としては、例えば多糖類などを用いることができる。多糖類としては、カルボキシメチルセルロース（ＣＭＣ）、メチルセルロース、エチルセルロース、ヒドロキシプロピルセルロース、ジアセチルセルロース、再生セルロースなどのセルロース誘導体、澱粉などのうち一以上を用いることができる。また、これらの水溶性の高分子を、前述のゴム材料と併用して用いると、さらに好ましい。 Further, as the binder, it is preferable to use, for example, a water-soluble polymer. As the water-soluble polymer, for example, polysaccharides can be used. As the polysaccharide, one or more of cellulose derivatives such as carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, regenerated cellulose, starch, etc. can be used. Further, it is more preferable to use these water-soluble polymers in combination with the above-mentioned rubber material.
　または、バインダとしては、ポリスチレン、ポリアクリル酸メチル、ポリメタクリル酸メチル（ポリメチルメタクリレート、ＰＭＭＡ）、ポリアクリル酸ナトリウム、ポリビニルアルコール（ＰＶＡ）、ポリエチレンオキシド（ＰＥＯ）、ポリプロピレンオキシド、ポリイミド、ポリ塩化ビニル、ポリテトラフルオロエチレン、ポリエチレン、ポリプロピレン、ポリイソブチレン、ポリエチレンテレフタレート、ナイロン、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリアクリロニトリル（ＰＡＮ）、エチレンプロピレンジエンポリマー、ポリ酢酸ビニル、ニトロセルロース等の材料を用いることが好ましい。 Or, as a binder, polystyrene, polymethyl acrylate, polymethyl methacrylate (polymethyl methacrylate, PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride It is preferable to use materials such as polytetrafluoroethylene, polyethylene, polypropylene, polyisobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), ethylene propylene diene polymer, polyvinyl acetate, nitrocellulose, etc. .
　バインダは上記のうち複数を組み合わせて使用してもよい。 The binder may be used in combination of more than one of the above.
　図１１Ｂは、完成したコイン型の二次電池の斜視図である。 FIG. 11B is a perspective view of the completed coin-shaped secondary battery.
　コイン型の二次電池３００は、正極端子を兼ねた正極缶３０１と負極端子を兼ねた負極缶３０２とが、ポリプロピレン等で形成されたガスケット３０３で絶縁シールされている。正極３０４は、正極集電体３０５と、これと接するように設けられた正極活物質層３０６により形成される。また、負極３０７は、負極集電体３０８と、これに接するように設けられた負極活物質層３０９により形成される。また、負極３０７は、積層構造に限定されず、リチウム金属箔またはリチウムとアルミニウムの合金箔を用いてもよい。 In the coin-shaped secondary battery 300, a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 302 that also serves as a negative electrode terminal are insulated and sealed with a gasket 303 made of polypropylene or the like. The positive electrode 304 is formed by a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with the positive electrode current collector 305 . Further, the negative electrode 307 is formed of a negative electrode current collector 308 and a negative electrode active material layer 309 provided in contact with the negative electrode current collector 308. Further, the negative electrode 307 is not limited to a laminated structure, and lithium metal foil or lithium-aluminum alloy foil may be used.
　なお、コイン型の二次電池３００に用いる正極３０４及び負極３０７は、それぞれ活物質層は片面のみに形成すればよい。 Note that the active material layer of each of the positive electrode 304 and negative electrode 307 used in the coin-shaped secondary battery 300 may be formed only on one side.
　正極缶３０１、負極缶３０２には、電解液に対して耐食性のあるニッケル、アルミニウム、チタン等の金属、若しくはこれらの合金又はこれらと他の金属との合金（例えばステンレス鋼等）を用いることができる。また、電解液などによる腐食を防ぐため、ニッケルまたはアルミニウム等を被覆することが好ましい。正極缶３０１は正極３０４と、負極缶３０２は負極３０７とそれぞれ電気的に接続する。 For the positive electrode can 301 and the negative electrode can 302, metals such as nickel, aluminum, titanium, etc., which are corrosion resistant to electrolyte, or alloys thereof, or alloys of these and other metals (for example, stainless steel, etc.) can be used. can. Further, in order to prevent corrosion due to electrolyte and the like, it is preferable to coat with nickel, aluminum, or the like. The positive electrode can 301 is electrically connected to the positive electrode 304, and the negative electrode can 302 is electrically connected to the negative electrode 307.
　これら負極３０７、正極３０４及びセパレータ３１０を電解液に浸し、図１１Ｃに示すように、正極缶３０１を下にして正極３０４、セパレータ３１０、負極３０７、負極缶３０２をこの順で積層し、正極缶３０１と負極缶３０２とをガスケット３０３を介して圧着してコイン形の二次電池３００を製造する。 These negative electrode 307, positive electrode 304, and separator 310 are immersed in an electrolytic solution, and the positive electrode 304, separator 310, negative electrode 307, and negative electrode can 302 are stacked in this order with the positive electrode can 301 facing down, as shown in FIG. 301 and a negative electrode can 302 are crimped together via a gasket 303 to produce a coin-shaped secondary battery 300.
　上記の構成を有することで、安全性に優れたコイン型の二次電池３００とすることができる。 By having the above configuration, a coin-shaped secondary battery 300 with excellent safety can be obtained.
［電解液］
　電解液の一つの形態として、溶媒と、溶媒に溶解した電解質と、を有する電解液を用いることができる。電解液の溶媒としては、非プロトン性有機溶媒が好ましく、例えば、エチレンカーボネート（ＥＣ）、プロピレンカーボネート（ＰＣ）、ブチレンカーボネート、クロロエチレンカーボネート、ビニレンカーボネート、γ−ブチロラクトン、γ−バレロラクトン、ジメチルカーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、エチルメチルカーボネート（ＥＭＣ）、ギ酸メチル、酢酸メチル、酢酸エチル、プロピオン酸メチル、プロピオン酸エチル、プロピオン酸プロピル、酪酸メチル、１，３−ジオキサン、１，４−ジオキサン、ジメトキシエタン（ＤＭＥ）、ジメチルスルホキシド、ジエチルエーテル、メチルジグライム、アセトニトリル、ベンゾニトリル、テトラヒドロフラン、スルホラン、スルトン等の１種、又はこれらのうちの２種以上を任意の組み合わせおよび比率で用いることができる。 [Electrolyte]
As one form of the electrolytic solution, an electrolytic solution including a solvent and an electrolyte dissolved in the solvent can be used. As the solvent for the electrolytic solution, aprotic organic solvents are preferred, such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone, and dimethyl carbonate. (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1,3-dioxane, 1,4 - Use one or more of dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfolane, sultone, etc., or two or more of these in any combination and ratio. be able to.
　また、電解液の溶媒として、難燃性および難揮発性であるイオン液体（常温溶融塩）を一つ又は複数用いることで、蓄電装置の内部短絡または、過充電等によって内部温度が上昇しても、蓄電装置の破裂および発火などを防ぐことができる。イオン液体は、カチオンとアニオンからなり、有機カチオンとアニオンとを含む。電解液に用いる有機カチオンとして、四級アンモニウムカチオン、三級スルホニウムカチオン、および四級ホスホニウムカチオン等の脂肪族オニウムカチオン、イミダゾリウムカチオンおよびピリジニウムカチオン等の芳香族カチオンが挙げられる。また、電解液に用いるアニオンとして、１価のアミド系アニオン、１価のメチド系アニオン、フルオロスルホン酸アニオン、パーフルオロアルキルスルホン酸アニオン、テトラフルオロボレートアニオン、パーフルオロアルキルボレートアニオン、ヘキサフルオロホスフェートアニオン、またはパーフルオロアルキルホスフェートアニオン等が挙げられる。 In addition, by using one or more flame-retardant and non-volatile ionic liquids (room-temperature molten salts) as the solvent for the electrolyte, it is possible to prevent the internal temperature from rising due to internal short circuits or overcharging of the power storage device. It is also possible to prevent the power storage device from bursting and catching fire. Ionic liquids are composed of cations and anions, and include organic cations and anions. Examples of the organic cation used in the electrolytic solution include aliphatic onium cations such as quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, and aromatic cations such as imidazolium cations and pyridinium cations. In addition, examples of anions used in the electrolytic solution include monovalent amide anions, monovalent methide anions, fluorosulfonic acid anions, perfluoroalkylsulfonic acid anions, tetrafluoroborate anions, perfluoroalkylborate anions, and hexafluorophosphate anions. , or perfluoroalkyl phosphate anion.
　また、上記の溶媒に溶解させる電解質としては、例えばＬｉＰＦ６、ＬｉＣｌＯ４、ＬｉＡｓＦ６、ＬｉＢＦ４、ＬｉＡｌＣｌ４、ＬｉＳＣＮ、ＬｉＢｒ、ＬｉＩ、Ｌｉ２ＳＯ４、Ｌｉ２Ｂ１０Ｃｌ１０、Ｌｉ２Ｂ１２Ｃｌ１２、ＬｉＣＦ３ＳＯ３、ＬｉＣ４Ｆ９ＳＯ３、ＬｉＣ（ＣＦ３ＳＯ２）３、ＬｉＣ（Ｃ２Ｆ５ＳＯ２）３、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＮ（Ｃ４Ｆ９ＳＯ２）（ＣＦ３ＳＯ２）、ＬｉＮ（Ｃ２Ｆ５ＳＯ２）２、リチウムビス（オキサレート）ボレート（Ｌｉ（Ｃ２Ｏ４）２、ＬｉＢＯＢ）等のリチウム塩を一種、又はこれらのうちの二種以上を任意の組み合わせおよび比率で用いることができる。 Examples of electrolytes to be dissolved in the above solvent include LiPF 6 , LiClO 4 , LiAsF 6 , LiBF 4 , LiAlCl 4 , LiSCN, LiBr, LiI, Li 2 SO 4 , Li 2 B 10 Cl 10 , Li 2 B 12 Cl12 , LiCF3SO3 , LiC4F9SO3 , LiC (CF3SO2 ) 3 , LiC( C2F5SO2 ) 3 , LiN ( CF3SO2 ) 2 , LiN ( C4F9 One type of lithium salt such as SO 2 )(CF 3 SO 2 ), LiN(C 2 F 5 SO 2 ) 2 , lithium bis(oxalate)borate (Li(C 2 O 4 ) 2 , LiBOB), or any of these Two or more of these can be used in any combination and ratio.
　また、電解液にビニレンカーボネート、プロパンスルトン（ＰＳ）、ｔｅｒｔ−ブチルベンゼン（ＴＢＢ）、フルオロエチレンカーボネート（ＦＥＣ）、リチウムビス（オキサレート）ボレート（ＬｉＢＯＢ）、またスクシノニトリル、アジポニトリル等のジニトリル化合物、フルオロベンゼン、エチレングリコースビス（プロピオニトリル）エーテルなどの添加剤を添加してもよい。添加剤の濃度はそれぞれ、例えば電解質が溶解した溶媒に対してそれぞれ０．１ｗｔ％以上５ｗｔ％以下とすればよい。特に、アジポニトリルは本発明の一態様の正極活物質１０１の表面と相互作用により高電圧耐性を増強することが期待されるため、本発明の一態様の正極活物質を用いる二次電池に用いることでよりエネルギー密度の高い二次電池にすることができ好ましい。なお添加剤は二次電池のエージング処理の際に活物質表面に付着する被膜となる場合がある。そのため少しでも充放電を経た二次電池では、電解液から少なくとも一部の添加剤が検出されない場合がある。たとえばビニレンカーボネートは負極活物質表面で被膜となることが知られているため、製造段階で加えられたとしても市販の二次電池の電解液から検出されない場合がある。 In addition, the electrolyte contains vinylene carbonate, propane sultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), lithium bis(oxalate)borate (LiBOB), and dinitrile compounds such as succinonitrile and adiponitrile. Additives such as fluorobenzene and ethylene glycose bis(propionitrile) ether may also be added. The concentration of each additive may be, for example, 0.1 wt% or more and 5 wt% or less with respect to the solvent in which the electrolyte is dissolved. In particular, adiponitrile is expected to enhance high voltage resistance through interaction with the surface of the positive electrode active material 101 of one embodiment of the present invention, and therefore adiponitrile cannot be used in a secondary battery using the positive electrode active material of one embodiment of the present invention. This is preferable since it can be used as a secondary battery with higher energy density. Note that the additive may form a film that adheres to the surface of the active material during aging treatment of the secondary battery. Therefore, in a secondary battery that has been charged and discharged even slightly, at least some additives may not be detected in the electrolyte. For example, vinylene carbonate is known to form a film on the surface of the negative electrode active material, so even if it is added at the manufacturing stage, it may not be detected in the electrolyte of commercially available secondary batteries.
［セパレータ］
　電解質が電解液を含む場合、正極と負極の間にセパレータを配置する。セパレータとしては、例えば、紙をはじめとするセルロースを有する繊維、不織布、ガラス繊維、セラミックス、或いはナイロン（ポリアミド）、ビニロン（ポリビニルアルコール系繊維）、ポリエステル、アクリル、ポリオレフィン、ポリウレタンを用いた合成繊維等で形成されたものを用いることができる。セパレータは袋状に加工し、正極または負極のいずれか一方を包むように配置することが好ましい。 [Separator]
When the electrolyte contains an electrolytic solution, a separator is placed between the positive electrode and the negative electrode. As a separator, for example, fibers containing cellulose such as paper, nonwoven fabrics, glass fibers, ceramics, synthetic fibers using nylon (polyamide), vinylon (polyvinyl alcohol fiber), polyester, acrylic, polyolefin, polyurethane, etc. It is possible to use one formed of . It is preferable that the separator is processed into a bag shape and arranged so as to surround either the positive electrode or the negative electrode.
　セパレータは多層構造であってもよい。例えばポリプロピレン、ポリエチレン等の有機材料フィルムに、セラミックス系材料、フッ素系材料、ポリアミド系材料、またはこれらを混合したもの等をコートすることができる。セラミックス系材料としては、例えば酸化アルミニウム粒子、酸化シリコン粒子等を用いることができる。フッ素系材料としては、例えばＰＶＤＦ、ポリテトラフルオロエチレン等を用いることができる。ポリアミド系材料としては、例えばナイロン、アラミド（メタ系アラミド、パラ系アラミド）等を用いることができる。 The separator may have a multilayer structure. For example, a film of an organic material such as polypropylene or polyethylene can be coated with a ceramic material, a fluorine material, a polyamide material, or a mixture thereof. As the ceramic material, for example, aluminum oxide particles, silicon oxide particles, etc. can be used. As the fluorine-based material, for example, PVDF, polytetrafluoroethylene, etc. can be used. As the polyamide material, for example, nylon, aramid (meta-aramid, para-aramid), etc. can be used.
　セラミックス系材料をコートすると耐酸化性が向上するため、高電圧充放電の際のセパレータの劣化を抑制し、二次電池の信頼性を向上させることができる。またフッ素系材料をコートするとセパレータと電極が密着しやすくなり、出力特性を向上させることができる。ポリアミド系材料、特にアラミドをコートすると、耐熱性が向上するため、二次電池の安全性を向上させることができる。 Coating with a ceramic material improves oxidation resistance, so it is possible to suppress deterioration of the separator during high voltage charging and discharging and improve the reliability of the secondary battery. Furthermore, coating with a fluorine-based material makes it easier for the separator and electrode to come into close contact with each other, thereby improving output characteristics. Coating with a polyamide-based material, especially aramid, improves heat resistance, thereby improving the safety of the secondary battery.
　例えば、ポリプロピレンのフィルムの両面に酸化アルミニウムとアラミドの混合材料をコートしてもよい。また、ポリプロピレンのフィルムの、正極と接する面に酸化アルミニウムとアラミドの混合材料をコートし、負極と接する面にフッ素系材料をコートしてもよい。 For example, a mixed material of aluminum oxide and aramid may be coated on both sides of a polypropylene film. Alternatively, the surface of the polypropylene film in contact with the positive electrode may be coated with a mixed material of aluminum oxide and aramid, and the surface in contact with the negative electrode may be coated with a fluorine-based material.
　多層構造のセパレータを用いると、セパレータ全体の厚さが薄くても二次電池の安全性を保つことができるため、二次電池の体積あたりの容量を大きくすることができる。 By using a separator with a multilayer structure, the safety of the secondary battery can be maintained even if the overall thickness of the separator is thin, so the capacity per volume of the secondary battery can be increased.
［円筒型二次電池］
　円筒型の二次電池の例について図１２Ａを参照して説明する。円筒型の二次電池６１６は、図１２Ａに示すように、上面に正極キャップ（電池蓋）６０１を有し、側面及び底面に電池缶（外装缶）６０２を有している。これら正極キャップ６０１と電池缶（外装缶）６０２とは、ガスケット（絶縁パッキン）６１０によって絶縁されている。 [Cylindrical secondary battery]
An example of a cylindrical secondary battery will be described with reference to FIG. 12A. As shown in FIG. 12A, the cylindrical secondary battery 616 has a positive electrode cap (battery lid) 601 on the top surface and a battery can (exterior can) 602 on the side and bottom surfaces. These positive electrode cap 601 and battery can (exterior can) 602 are insulated by a gasket (insulating packing) 610.
　図１２Ｂは、円筒型の二次電池の断面を模式的に示した図である。図１２Ｂに示す円筒型の二次電池は、上面に正極キャップ（電池蓋）６０１を有し、側面及び底面に電池缶（外装缶）６０２を有している。これら正極キャップと電池缶（外装缶）６０２とは、ガスケット（絶縁パッキン）６１０によって絶縁されている。 FIG. 12B is a diagram schematically showing a cross section of a cylindrical secondary battery. The cylindrical secondary battery shown in FIG. 12B has a positive electrode cap (battery lid) 601 on the top surface and a battery can (exterior can) 602 on the side and bottom surfaces. These positive electrode caps and the battery can (exterior can) 602 are insulated by a gasket (insulating packing) 610.
　中空円柱状の電池缶６０２の内側には、帯状の正極６０４と負極６０６とがセパレータ６０５を間に挟んで捲回されている。図示しないが、帯状の正極６０４と負極６０６とがセパレータ６０５を間に挟んで捲回された捲回体は中心軸を中心に捲回されている。電池缶６０２は、一端が閉じられ、他端が開いている。電池缶６０２には、電解液に対して耐腐食性のあるニッケル、アルミニウム、チタン等の金属、又はこれらの合金、これらと他の金属との合金（例えば、ステンレス鋼等）を用いることができる。また、電解液による腐食を防ぐため、ニッケル及びアルミニウム等を電池缶６０２に被覆することが好ましい。電池缶６０２の内側において、正極、負極及びセパレータが捲回された捲回体は、対向する一対の絶縁板６０８、６０９により挟まれている。また、捲回体が設けられた電池缶６０２の内部は、非水電解液（図示せず）が注入されている。非水電解液は、コイン型の二次電池と同様のものを用いることができる。 Inside a hollow cylindrical battery can 602, a band-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 in between. Although not shown, a wound body in which a band-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 in between is wound around a central axis. The battery can 602 has one end closed and the other end open. For the battery can 602, metals such as nickel, aluminum, titanium, etc., which are corrosion resistant to electrolyte, or alloys thereof, or alloys of these and other metals (for example, stainless steel, etc.) can be used. . Further, in order to prevent corrosion caused by the electrolyte, it is preferable to coat the battery can 602 with nickel, aluminum, or the like. Inside the battery can 602, a wound body in which a positive electrode, a negative electrode, and a separator are wound is sandwiched between a pair of opposing insulating plates 608 and 609. Furthermore, a non-aqueous electrolyte (not shown) is injected into the inside of the battery can 602 provided with the wound body. As the non-aqueous electrolyte, the same one as a coin-type secondary battery can be used.
　円筒型の蓄電池に用いる正極及び負極は捲回するため、集電体の両面に活物質を形成することが好ましい。 Since the positive and negative electrodes used in a cylindrical storage battery are wound, it is preferable to form active materials on both sides of the current collector.
　実施の形態１で得られる正極活物質１０１を正極６０４に用いることで、安全性に優れた円筒型の二次電池６１６とすることができる。 By using the positive electrode active material 101 obtained in Embodiment 1 for the positive electrode 604, a cylindrical secondary battery 616 with excellent safety can be obtained.
　正極６０４には正極端子（正極集電リード）６０３が接続され、負極６０６には負極端子（負極集電リード）６０７が接続される。正極端子６０３及び負極端子６０７は、ともにアルミニウムなどの金属材料を用いることができる。正極端子６０３は安全弁機構６１３に、負極端子６０７は電池缶６０２の底にそれぞれ抵抗溶接される。安全弁機構６１３は、ＰＴＣ素子（Ｐｏｓｉｔｉｖｅ　Ｔｅｍｐｅｒａｔｕｒｅ　Ｃｏｅｆｆｉｃｉｅｎｔ）６１１を介して正極キャップ６０１と電気的に接続されている。安全弁機構６１３は電池の内圧の上昇が所定の閾値を超えた場合に、正極キャップ６０１と正極６０４との電気的な接続を切断するものである。また、ＰＴＣ素子６１１は温度が上昇した場合に抵抗が増大する熱感抵抗素子であり、抵抗の増大により電流量を制限して異常発熱を防止するものである。ＰＴＣ素子には、チタン酸バリウム（ＢａＴｉＯ３）系半導体セラミックス等を用いることができる。 A positive electrode terminal (positive electrode current collector lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collector lead) 607 is connected to the negative electrode 606. Both the positive electrode terminal 603 and the negative electrode terminal 607 can be made of a metal material such as aluminum. The positive terminal 603 and the negative terminal 607 are resistance welded to the safety valve mechanism 613 and the bottom of the battery can 602, respectively. The safety valve mechanism 613 is electrically connected to the positive electrode cap 601 via a PTC element (Positive Temperature Coefficient) 611. The safety valve mechanism 613 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the increase in the internal pressure of the battery exceeds a predetermined threshold value. Further, the PTC element 611 is a heat-sensitive resistance element whose resistance increases when the temperature rises, and the increase in resistance limits the amount of current to prevent abnormal heat generation. Barium titanate (BaTiO 3 )-based semiconductor ceramics or the like can be used for the PTC element.
　図１２Ｃは蓄電システム６１５の一例を示す。蓄電システム６１５は複数の二次電池６１６を有する。それぞれの二次電池の正極は、絶縁体６２５で分離された導電体６２４に接触し、電気的に接続されている。導電体６２４は配線６２３を介して、制御回路６２０に電気的に接続されている。また、それぞれの二次電池の負極は、配線６２６を介して制御回路６２０に電気的に接続されている。制御回路６２０として、充放電などを行う充放電制御回路、または過充電もしくは／及び過放電を防止する保護回路を適用することができる。 FIG. 12C shows an example of the power storage system 615. Power storage system 615 includes a plurality of secondary batteries 616. The positive electrode of each secondary battery contacts a conductor 624 separated by an insulator 625 and is electrically connected. The conductor 624 is electrically connected to the control circuit 620 via the wiring 623. Further, the negative electrode of each secondary battery is electrically connected to the control circuit 620 via a wiring 626. As the control circuit 620, a charging/discharging control circuit that performs charging and discharging, or a protection circuit that prevents overcharging and/or overdischarging can be applied.
　図１２Ｄは、蓄電システム６１５の一例を示す。蓄電システム６１５は複数の二次電池６１６を有し、複数の二次電池６１６は、導電板６２８及び導電板６１４の間に挟まれている。複数の二次電池６１６は、配線６２７により導電板６２８及び導電板６１４と電気的に接続される。複数の二次電池６１６は、並列接続されていてもよいし、直列接続されていてもよいし、並列に接続された後さらに直列に接続されていてもよい。複数の二次電池６１６を有する蓄電システム６１５を構成することで、大きな電力を取り出すことができる。 FIG. 12D shows an example of the power storage system 615. The power storage system 615 has a plurality of secondary batteries 616, and the plurality of secondary batteries 616 are sandwiched between a conductive plate 628 and a conductive plate 614. The plurality of secondary batteries 616 are electrically connected to a conductive plate 628 and a conductive plate 614 by wiring 627. The plurality of secondary batteries 616 may be connected in parallel, connected in series, or connected in parallel and then further connected in series. By configuring a power storage system 615 that includes a plurality of secondary batteries 616, a large amount of electric power can be extracted.
　複数の二次電池６１６を、並列に接続させた後、その集合をさらに直列に接続させてもよい。 After the plurality of secondary batteries 616 are connected in parallel, the set may be further connected in series.
　また、複数の二次電池６１６の間に温度制御装置を有していてもよい。二次電池６１６が過熱されたときは、温度制御装置により冷却し、二次電池６１６が冷えすぎているときは温度制御装置により加熱することができる。そのため蓄電システム６１５の性能が外気温に影響されにくくなる。 Additionally, a temperature control device may be provided between the plurality of secondary batteries 616. When the secondary battery 616 is overheated, it can be cooled by the temperature control device, and when the secondary battery 616 is too cold, it can be heated by the temperature control device. Therefore, the performance of power storage system 615 is less affected by outside temperature.
　また、図１２Ｄにおいて、蓄電システム６１５は制御回路６２０に配線６２１及び配線６２２を介して電気的に接続されている。配線６２１は導電板６２８を介して複数の二次電池６１６の正極に、配線６２２は導電板６１４を介して複数の二次電池６１６の負極に、それぞれ電気的に接続される。 Further, in FIG. 12D, the power storage system 615 is electrically connected to the control circuit 620 via wiring 621 and wiring 622. The wiring 621 is electrically connected to the positive electrodes of the plurality of secondary batteries 616 via the conductive plate 628, and the wiring 622 is electrically connected to the negative electrodes of the plurality of secondary batteries 616 via the conductive plate 614.
［二次電池の他の構造例］
　二次電池の構造例について図１３及び図１４を用いて説明する。 [Other structural examples of secondary batteries]
A structural example of a secondary battery will be described using FIGS. 13 and 14.
　図１３Ａに示す二次電池９１３は、筐体９３０の内部に端子９５１と端子９５２が設けられた捲回体９５０を有する。捲回体９５０は、筐体９３０の内部で電解液中に浸される。端子９５２は、筐体９３０に接し、端子９５１は、絶縁材などを用いることにより筐体９３０に接していない。なお、図１３Ａでは、便宜のため、筐体９３０を分離して図示しているが、実際は、捲回体９５０が筐体９３０に覆われ、端子９５１及び端子９５２が筐体９３０の外に延在している。筐体９３０としては、金属材料（例えばアルミニウムなど）又は樹脂材料を用いることができる。 A secondary battery 913 shown in FIG. 13A has a wound body 950 in which a terminal 951 and a terminal 952 are provided inside a casing 930. The wound body 950 is immersed in the electrolyte inside the housing 930. The terminal 952 is in contact with the housing 930, and the terminal 951 is not in contact with the housing 930 by using an insulating material or the like. Note that although the housing 930 is shown separated in FIG. 13A for convenience, in reality, the wound body 950 is covered by the housing 930, and the terminals 951 and 952 extend outside the housing 930. There is. As the housing 930, a metal material (for example, aluminum) or a resin material can be used.
　なお、図１３Ｂに示すように、図１３Ａに示す筐体９３０を複数の材料によって形成してもよい。例えば、図１３Ｂに示す二次電池９１３は、筐体９３０ａと筐体９３０ｂが貼り合わされており、筐体９３０ａ及び筐体９３０ｂで囲まれた領域に捲回体９５０が設けられている。 Note that, as shown in FIG. 13B, the casing 930 shown in FIG. 13A may be formed of a plurality of materials. For example, in the secondary battery 913 shown in FIG. 13B, a housing 930a and a housing 930b are bonded together, and a wound body 950 is provided in an area surrounded by the housing 930a and the housing 930b.
　筐体９３０ａとしては、有機樹脂など、絶縁材料を用いることができる。特に、アンテナが形成される面に有機樹脂などの材料を用いることにより、二次電池９１３による電界の遮蔽を抑制できる。なお、筐体９３０ａによる電界の遮蔽が小さければ、筐体９３０ａの内部にアンテナを設けてもよい。筐体９３０ｂとしては、例えば金属材料を用いることができる。 As the housing 930a, an insulating material such as organic resin can be used. In particular, by using a material such as an organic resin on the surface where the antenna is formed, shielding of the electric field by the secondary battery 913 can be suppressed. Note that if the shielding of the electric field by the housing 930a is small, an antenna may be provided inside the housing 930a. For example, a metal material can be used as the housing 930b.
　さらに、捲回体９５０の構造について図１３Ｃに示す。捲回体９５０は、負極９３１と、正極９３２と、セパレータ９３３と、を有する。捲回体９５０は、セパレータ９３３を挟んで負極９３１と、正極９３２が重なり合って積層され、該積層シートを捲回させた捲回体である。なお、負極９３１と、正極９３２と、セパレータ９３３と、の積層を、さらに複数重ねてもよい。 Furthermore, the structure of the wound body 950 is shown in FIG. 13C. The wound body 950 includes a negative electrode 931, a positive electrode 932, and a separator 933. The wound body 950 is a wound body in which a negative electrode 931 and a positive electrode 932 are stacked on top of each other with a separator 933 in between, and the laminated sheet is wound. Note that a plurality of layers of the negative electrode 931, the positive electrode 932, and the separator 933 may be stacked.
　また、図１４に示すような捲回体９５０ａを有する二次電池９１３としてもよい。図１４Ａに示す捲回体９５０ａは、負極９３１と、正極９３２と、セパレータ９３３と、を有する。負極９３１は負極活物質層９３１ａを有する。正極９３２は正極活物質層９３２ａを有する。 Alternatively, a secondary battery 913 having a wound body 950a as shown in FIG. 14 may be used. A wound body 950a shown in FIG. 14A includes a negative electrode 931, a positive electrode 932, and a separator 933. The negative electrode 931 has a negative electrode active material layer 931a. The positive electrode 932 has a positive electrode active material layer 932a.
　実施の形態１で得られる正極活物質１０１を正極９３２に用いることで、安全性に優れた二次電池９１３とすることができる。 By using the positive electrode active material 101 obtained in Embodiment 1 for the positive electrode 932, a secondary battery 913 with excellent safety can be obtained.
　セパレータ９３３は、負極活物質層９３１ａ及び正極活物質層９３２ａよりも広い幅を有し、負極活物質層９３１ａ及び正極活物質層９３２ａと重畳するように捲回されている。また正極活物質層９３２ａよりも負極活物質層９３１ａの幅が広いことが安全性の点で好ましい。またこのような形状の捲回体９５０ａは安全性及び生産性がよく好ましい。 The separator 933 has a width wider than the negative electrode active material layer 931a and the positive electrode active material layer 932a, and is wound so as to overlap with the negative electrode active material layer 931a and the positive electrode active material layer 932a. Further, from the viewpoint of safety, it is preferable that the width of the negative electrode active material layer 931a is wider than that of the positive electrode active material layer 932a. Further, the wound body 950a having such a shape is preferable because it has good safety and productivity.
　図１４Ｂに示すように、負極９３１は、超音波接合、溶接、または圧着により端子９５１と電気的に接続される。端子９５１は端子９１１ａと電気的に接続される。また正極９３２は、超音波接合、溶接、または圧着により端子９５２と電気的に接続される。端子９５２は端子９１１ｂと電気的に接続される。 As shown in FIG. 14B, the negative electrode 931 is electrically connected to the terminal 951 by ultrasonic bonding, welding, or crimping. Terminal 951 is electrically connected to terminal 911a. Further, the positive electrode 932 is electrically connected to the terminal 952 by ultrasonic bonding, welding, or crimping. Terminal 952 is electrically connected to terminal 911b.
　図１４Ｃに示すように、筐体９３０により捲回体９５０ａ及び電解液が覆われ、二次電池９１３となる。筐体９３０には安全弁、過電流保護素子等を設けることが好ましい。安全弁は、電池破裂を防止するため、筐体９３０の内部が所定の内圧で開放する弁である。 As shown in FIG. 14C, the wound body 950a and the electrolyte are covered by the casing 930, forming a secondary battery 913. It is preferable that the housing 930 is provided with a safety valve, an overcurrent protection element, and the like. The safety valve is a valve that opens the inside of the casing 930 at a predetermined internal pressure in order to prevent the battery from exploding.
　図１４Ｂに示すように二次電池９１３は複数の捲回体９５０ａを有していてもよい。複数の捲回体９５０ａを用いることで、より放電容量の大きい二次電池９１３とすることができる。図１４Ａ及び図１４Ｂに示す二次電池９１３の他の要素は、図１３Ａ乃至図１３Ｃに示す二次電池９１３の記載を参照することができる。 As shown in FIG. 14B, the secondary battery 913 may have a plurality of wound bodies 950a. By using a plurality of wound bodies 950a, the secondary battery 913 can have a larger discharge capacity. For other elements of the secondary battery 913 shown in FIGS. 14A and 14B, the description of the secondary battery 913 shown in FIGS. 13A to 13C can be referred to.
＜ラミネート型二次電池＞
　次に、ラミネート型の二次電池の例について、外観図の一例を図１５Ａ及び図１５Ｂに示す。図１５Ａ及び図１５Ｂは、正極５０３、負極５０６、セパレータ５０７、外装体５０９、正極リード電極５１０、及び負極リード電極５１１を有する。 <Laminated secondary battery>
Next, an example of an external view of an example of a laminate type secondary battery is shown in FIGS. 15A and 15B. 15A and 15B have a positive electrode 503, a negative electrode 506, a separator 507, an exterior body 509, a positive lead electrode 510, and a negative lead electrode 511.
　図１６Ａは正極５０３及び負極５０６の外観図を示す。正極５０３は正極集電体５０１を有し、正極活物質層５０２は正極集電体５０１の表面に形成されている。また、正極５０３は正極集電体５０１が一部露出する領域（以下、タブ領域という）を有する。負極５０６は負極集電体５０４を有し、負極活物質層５０５は負極集電体５０４の表面に形成されている。また、負極５０６は負極集電体５０４が一部露出する領域、すなわちタブ領域を有する。なお、正極及び負極が有するタブ領域の面積または形状は、図１６Ａに示す例に限られない。 FIG. 16A shows an external view of the positive electrode 503 and negative electrode 506. The positive electrode 503 has a positive electrode current collector 501 , and the positive electrode active material layer 502 is formed on the surface of the positive electrode current collector 501 . Further, the positive electrode 503 has a region (hereinafter referred to as a tab region) where the positive electrode current collector 501 is partially exposed. The negative electrode 506 has a negative electrode current collector 504 , and the negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504 . Further, the negative electrode 506 has a region where the negative electrode current collector 504 is partially exposed, that is, a tab region. Note that the area or shape of the tab regions of the positive electrode and the negative electrode is not limited to the example shown in FIG. 16A.
＜ラミネート型二次電池の作製方法＞
　図１５Ａに外観図を示すラミネート型二次電池の作製方法の一例について、図１６Ｂ及び図１６Ｃを用いて説明する。 <Method for manufacturing a laminated secondary battery>
An example of a method for manufacturing a laminated secondary battery whose appearance is shown in FIG. 15A will be described with reference to FIGS. 16B and 16C.
　まず、負極５０６、セパレータ５０７及び正極５０３を積層する。図１３Ｂに積層された負極５０６、セパレータ５０７及び正極５０３を示す。ここでは負極を５組、正極を４組使用する例を示す。負極とセパレータと正極からなる積層体とも呼べる。次に、正極５０３のタブ領域同士の接合と、最表面の正極のタブ領域への正極リード電極５１０の接合を行う。接合には、例えば超音波溶接等を用いればよい。同様に、負極５０６のタブ領域同士の接合と、最表面の負極のタブ領域への負極リード電極５１１の接合を行う。 First, the negative electrode 506, separator 507, and positive electrode 503 are stacked. FIG. 13B shows a stacked negative electrode 506, separator 507, and positive electrode 503. Here, an example is shown in which five sets of negative electrodes and four sets of positive electrodes are used. It can also be called a laminate consisting of a negative electrode, a separator, and a positive electrode. Next, the tab regions of the positive electrodes 503 are joined together, and the positive lead electrode 510 is joined to the tab region of the outermost positive electrode. For example, ultrasonic welding or the like may be used for joining. Similarly, the tab regions of the negative electrodes 506 are bonded to each other, and the negative lead electrode 511 is bonded to the tab region of the outermost negative electrode.
　次に、外装体５０９上に、負極５０６、セパレータ５０７及び正極５０３を配置する。 Next, a negative electrode 506, a separator 507, and a positive electrode 503 are placed on the exterior body 509.
　次に、図１６Ｃに示すように、外装体５０９を破線で示した部分で折り曲げる。その後、外装体５０９の外周部を接合する。接合には例えば熱圧着等を用いればよい。この時、後に電解液を入れることができるように、外装体５０９の一部（または一辺）に接合されない領域（以下、導入口という）を設ける。 Next, as shown in FIG. 16C, the exterior body 509 is bent at the portion indicated by the broken line. After that, the outer peripheral portion of the exterior body 509 is joined. For example, thermocompression bonding or the like may be used for joining. At this time, a region (hereinafter referred to as an inlet) that is not joined is provided in a part (or one side) of the exterior body 509 so that the electrolyte can be introduced later.
　次に、外装体５０９に設けられた導入口から、電解液を外装体５０９の内側へ導入する。電解液の導入は、減圧雰囲気下、或いは不活性雰囲気下で行うことが好ましい。そして最後に、導入口を接合する。このようにして、ラミネート型の二次電池５００を作製することができる。 Next, the electrolytic solution is introduced into the interior of the exterior body 509 from the introduction port provided in the exterior body 509. The electrolytic solution is preferably introduced under a reduced pressure atmosphere or an inert atmosphere. Finally, connect the inlet. In this way, a laminate type secondary battery 500 can be manufactured.
　実施の形態１で得られる正極活物質１０１を正極５０３に用いることで、安全性に優れた二次電池５００とすることができる。 By using the positive electrode active material 101 obtained in Embodiment 1 for the positive electrode 503, a secondary battery 500 with excellent safety can be obtained.
（実施の形態３）
　本実施の形態では、本発明の一態様の二次電池を有する車両の例を示す。 (Embodiment 3)
In this embodiment, an example of a vehicle including a secondary battery according to one embodiment of the present invention will be described.
　車両として、代表的には自動車に二次電池を適用することができる。自動車としては、ハイブリッド車（ＨＶ）、電気自動車（ＥＶ）、又はプラグインハイブリッド車（ＰＨＥＶまたはＰＨＶともいう）等の次世代クリーンエネルギー自動車を挙げることができ、自動車に搭載する電源の一つとして二次電池を適用することができる。車両は自動車に限定されない。例えば、車両としては、電車、モノレール、船、潜水艇（深海探査艇、無人潜水艇）、飛行体（ヘリコプター、無人航空機（ドローン）、飛行機、ロケット、人工衛星）、電動自転車、電動バイクなども挙げることができ、これらの車両に本発明の一態様の二次電池を適用することができる。 As a vehicle, a secondary battery can typically be applied to an automobile. Examples of automobiles include next-generation clean energy vehicles such as hybrid vehicles (HV), electric vehicles (EV), and plug-in hybrid vehicles (PHEV or PHV). A secondary battery can be applied. Vehicles are not limited to automobiles. For example, vehicles include trains, monorails, ships, submersibles (deep sea exploration vehicles, unmanned submarines), flying vehicles (helicopters, unmanned aerial vehicles (drones), airplanes, rockets, artificial satellites), electric bicycles, electric motorcycles, etc. The secondary battery of one embodiment of the present invention can be applied to these vehicles.
　電気自動車には、図１７Ｃのブロック図に示すように、メインの駆動用の二次電池として第１のバッテリ１３０１ａ、１３０１ｂと、モータ１３０４を始動させるインバータ１３１２に電力を供給する第２のバッテリ１３１１が設置されている。第２のバッテリ１３１１はクランキングバッテリー（スターターバッテリーとも呼ばれる）とも呼ばれる。第２のバッテリ１３１１は高出力できればよく、大容量はそれほど必要とされず、第２のバッテリ１３１１の容量は第１のバッテリ１３０１ａ、１３０１ｂと比較して小さい。 As shown in the block diagram of FIG. 17C, the electric vehicle includes first batteries 1301a and 1301b as main drive secondary batteries, and a second battery 1311 that supplies power to an inverter 1312 that starts a motor 1304. is installed. The second battery 1311 is also called a cranking battery (also called a starter battery). The second battery 1311 only needs to have a high output, and a large capacity is not required, and the capacity of the second battery 1311 is smaller than that of the first batteries 1301a and 1301b.
　第１のバッテリ１３０１ａの内部構造は、図１３Ｃまたは図１４Ａに示した捲回型であってもよいし、図１５Ａまたは図１５Ｂに示した積層型であってもよい。 The internal structure of the first battery 1301a may be a wound type shown in FIG. 13C or FIG. 14A, or a stacked type shown in FIG. 15A or FIG. 15B.
　本実施の形態では、第１のバッテリ１３０１ａ、１３０１ｂを２つ並列に接続させている例を示しているが３つ以上並列に接続させてもよい。また、第１のバッテリ１３０１ａで十分な電力を貯蔵できるのであれば、第１のバッテリ１３０１ｂはなくてもよい。複数の二次電池を有する電池パックを構成することで、大きな電力を取り出すことができる。複数の二次電池は、並列接続されていてもよいし、直列接続されていてもよいし、並列に接続された後、さらに直列に接続されていてもよい。複数の二次電池を組電池とも呼ぶ。 Although this embodiment shows an example in which two first batteries 1301a and 1301b are connected in parallel, three or more may be connected in parallel. Furthermore, if the first battery 1301a can store sufficient power, the first battery 1301b may not be necessary. By configuring a battery pack that includes a plurality of secondary batteries, a large amount of electric power can be extracted. A plurality of secondary batteries may be connected in parallel, may be connected in series, or may be connected in parallel and then further connected in series. A plurality of secondary batteries is also called an assembled battery.
　また、車載用の二次電池において、複数の二次電池からの電力を遮断するため、工具を使わずに高電圧を遮断できるサービスプラグまたはサーキットブレーカを有しており、第１のバッテリ１３０１ａに設けられる。 In addition, in order to cut off power from multiple secondary batteries in a vehicle-mounted secondary battery, the first battery 1301a has a service plug or circuit breaker that can cut off high voltage without using tools. provided.
　また、第１のバッテリ１３０１ａ、１３０１ｂの電力は、主にモータ１３０４を回転させることに使用されるが、ＤＣＤＣ回路１３０６を介して４２Ｖ系の車載部品（電動パワーステアリング１３０７、ヒーター１３０８、デフォッガ１３０９など）に電力を供給する。後輪にリアモータ１３１７を有している場合にも、第１のバッテリ１３０１ａがリアモータ１３１７を回転させることに使用される。 The electric power of the first batteries 1301a and 1301b is mainly used to rotate the motor 1304, but it is also used to power 42V-based in-vehicle components (electric power steering 1307, heater 1308, defogger 1309, etc.) via a DCDC circuit 1306. ). Even when the rear motor 1317 is provided on the rear wheel, the first battery 1301a is used to rotate the rear motor 1317.
　また、第２のバッテリ１３１１は、ＤＣＤＣ回路１３１０を介して１４Ｖ系の車載部品（オーディオ１３１３、パワーウィンドウ１３１４、ランプ類１３１５など）に電力を供給する。 Further, the second battery 1311 supplies power to 14V vehicle components (audio 1313, power window 1314, lamps 1315, etc.) via the DCDC circuit 1310.
　次に、第１のバッテリ１３０１ａについて、図１７Ａを用いて説明する。 Next, the first battery 1301a will be explained using FIG. 17A.
　図１７Ａでは９個の角型二次電池１３００を一つの電池パック１４１５としている例を示している。また、９個の角型二次電池１３００を直列接続し、一方の電極を絶縁体からなる固定部１４１３で固定し、もう一方の電極を絶縁体からなる固定部１４１４で固定している。本実施の形態では固定部１４１３、１４１４で固定する例を示しているが電池収容ボックス（筐体とも呼ぶ）に収納させる構成としてもよい。車両は外部（路面など）から振動または揺れが加えられることを想定されているため、固定部１４１３、１４１４、又は電池収容ボックスなどで複数の二次電池を固定することが好ましい。また、一方の電極は配線１４２１によって制御回路部１３２０に電気的に接続されている。またもう一方の電極は配線１４２２によって制御回路部１３２０に電気的に接続されている。 FIG. 17A shows an example in which nine square secondary batteries 1300 are used as one battery pack 1415. Further, nine prismatic secondary batteries 1300 are connected in series, one electrode is fixed by a fixing part 1413 made of an insulator, and the other electrode is fixed by a fixing part 1414 made of an insulator. Although this embodiment shows an example in which the battery is fixed using the fixing parts 1413 and 1414, it may also be configured to be housed in a battery housing box (also referred to as a housing). Since it is assumed that a vehicle is subjected to vibrations or shaking from the outside (road surface, etc.), it is preferable to fix the plurality of secondary batteries using fixing parts 1413, 1414, a battery housing box, or the like. Further, one electrode is electrically connected to the control circuit section 1320 by a wiring 1421. The other electrode is electrically connected to the control circuit section 1320 by a wiring 1422.
　次に、図１７Ａに示す電池パック１４１５のブロック図の一例を図１７Ｂに示す。 Next, FIG. 17B shows an example of a block diagram of the battery pack 1415 shown in FIG. 17A.
　制御回路部１３２０は、少なくとも過充電を防止するスイッチと、過放電を防止するスイッチを含むスイッチ部１３２４と、スイッチ部１３２４を制御する制御回路１３２２と、第１のバッテリ１３０１ａの電圧測定部と、を有する。制御回路部１３２０は、使用する二次電池の上限電圧と下限電圧が設定されており、外部からの電流上限、または外部への出力電流の上限などを制限している。二次電池の下限電圧以上上限電圧以下の範囲内は、使用が推奨されている電圧範囲内であり、その範囲外となるとスイッチ部１３２４が作動し、保護回路として機能する。また、制御回路部１３２０は、スイッチ部１３２４を制御して過放電および／または過充電を防止するため、保護回路とも呼べる。例えば、過充電となりそうな電圧を制御回路１３２２で検知した場合にスイッチ部１３２４のスイッチをオフ状態とすることで電流を遮断する。さらに充放電経路中にＰＴＣ素子を設けて温度の上昇に応じて電流を遮断する機能を設けてもよい。また、制御回路部１３２０は、外部端子１３２５（＋ＩＮ）と、外部端子１３２６（−ＩＮ）とを有している。 The control circuit section 1320 includes a switch section 1324 including at least a switch for preventing overcharging and a switch for preventing overdischarge, a control circuit 1322 for controlling the switch section 1324, and a voltage measuring section for the first battery 1301a. has. The control circuit section 1320 has an upper limit voltage and a lower limit voltage set for the secondary battery to be used, and limits the upper limit of the current from the outside or the upper limit of the output current to the outside. The range of the secondary battery's lower limit voltage to upper limit voltage is within the recommended voltage range, and when it is outside that range, the switch section 1324 is activated and functions as a protection circuit. Furthermore, the control circuit section 1320 can also be called a protection circuit because it controls the switch section 1324 to prevent overdischarge and/or overcharge. For example, when the control circuit 1322 detects a voltage that is likely to cause overcharging, the switch section 1324 is turned off to cut off the current. Furthermore, a PTC element may be provided in the charging/discharging path to provide a function of cutting off the current in response to a rise in temperature. Further, the control circuit section 1320 has an external terminal 1325 (+IN) and an external terminal 1326 (-IN).
　スイッチ部１３２４は、ｎチャネル型のトランジスタまたはｐチャネル型のトランジスタを組み合わせて構成することができる。スイッチ部１３２４は、単結晶シリコンを用いるＳｉトランジスタを有するスイッチに限定されず、例えば、Ｇｅ（ゲルマニウム）、ＳｉＧｅ（シリコンゲルマニウム）、ＧａＡｓ（ガリウムヒ素）、ＧａＡｌＡｓ（ガリウムアルミニウムヒ素）、ＩｎＰ（リン化インジウム）、ＳｉＣ（シリコンカーバイド）、ＺｎＳｅ（セレン化亜鉛）、ＧａＮ（窒化ガリウム）、ＧａＯｘ（酸化ガリウム；ｘは０より大きい実数）などを有するパワートランジスタでスイッチ部１３２４を形成してもよい。 The switch section 1324 can be configured by combining n-channel transistors or p-channel transistors. The switch section 1324 is not limited to a switch having an Si transistor using single crystal silicon, but includes, for example, Ge (germanium), SiGe (silicon germanium), GaAs (gallium arsenide), GaAlAs (gallium aluminum arsenide), InP (phosphide). The switch portion 1324 may be formed using a power transistor including indium (indium), SiC (silicon carbide), ZnSe (zinc selenide), GaN (gallium nitride), GaOx (gallium oxide; x is a real number greater than 0), or the like.
　第１のバッテリ１３０１ａ、１３０１ｂは、主に４２Ｖ系（高電圧系）の車載機器に電力を供給し、第２のバッテリ１３１１は１４Ｖ系（低電圧系）の車載機器に電力を供給する。第２のバッテリ１３１１は鉛蓄電池がコスト上有利のため採用されることが多い。 The first batteries 1301a and 1301b mainly supply power to 42V system (high voltage system) on-board equipment, and the second battery 1311 supplies power to 14V system (low voltage system) onboard equipment. As the second battery 1311, a lead-acid battery is often used because it is advantageous in terms of cost.
　本実施の形態では、第１のバッテリ１３０１ａと第２のバッテリ１３１１の両方にリチウムイオン電池を用いる一例を示す。第２のバッテリ１３１１は、鉛蓄電池、全固体電池、または電気二重層キャパシタを用いてもよい。 In this embodiment, an example is shown in which lithium ion batteries are used as both the first battery 1301a and the second battery 1311. The second battery 1311 may be a lead-acid battery, an all-solid-state battery, or an electric double layer capacitor.
　また、タイヤ１３１６の回転による回生エネルギーは、ギア１３０５を介してモータ１３０４に送られ、モータコントローラ１３０３、またはバッテリーコントローラ１３０２から制御回路部１３２１を介して第２のバッテリ１３１１に充電される。またはバッテリーコントローラ１３０２から制御回路部１３２０を介して第１のバッテリ１３０１ａに充電される。またはバッテリーコントローラ１３０２から制御回路部１３２０を介して第１のバッテリ１３０１ｂに充電される。回生エネルギーを効率よく充電するためには、第１のバッテリ１３０１ａ、１３０１ｂが急速充電可能であることが望ましい。 In addition, regenerated energy from the rotation of the tires 1316 is sent to the motor 1304 via the gear 1305, and charged to the second battery 1311 from the motor controller 1303 or the battery controller 1302 via the control circuit section 1321. Alternatively, the first battery 1301a is charged from the battery controller 1302 via the control circuit section 1320. Alternatively, the first battery 1301b is charged from the battery controller 1302 via the control circuit unit 1320. In order to efficiently charge the regenerated energy, it is desirable that the first batteries 1301a and 1301b can be rapidly charged.
　バッテリーコントローラ１３０２は第１のバッテリ１３０１ａ、１３０１ｂの充電電圧及び充電電流などを設定することができる。バッテリーコントローラ１３０２は、用いる二次電池の充電特性に合わせて充電条件を設定し、急速充電することができる。 The battery controller 1302 can set the charging voltage, charging current, etc. of the first batteries 1301a and 1301b. The battery controller 1302 can set charging conditions according to the charging characteristics of the secondary battery to be used and perform rapid charging.
　また、図示していないが、外部の充電器と接続させる場合、充電器のコンセントまたは充電器の接続ケーブルは、バッテリーコントローラ１３０２に電気的に接続される。外部の充電器から供給された電力はバッテリーコントローラ１３０２を介して第１のバッテリ１３０１ａ、１３０１ｂに充電する。また、充電器によっては、制御回路が設けられており、バッテリーコントローラ１３０２の機能を用いない場合もあるが、過充電を防ぐため制御回路部１３２０を介して第１のバッテリ１３０１ａ、１３０１ｂを充電することが好ましい。また、接続ケーブルまたは充電器の接続ケーブルに制御回路を備えている場合もある。制御回路部１３２０は、ＥＣＵ（Ｅｌｅｃｔｒｏｎｉｃ　Ｃｏｎｔｒｏｌ　Ｕｎｉｔ）と呼ばれることもある。ＥＣＵは、電動車両に設けられたＣＡＮ（Ｃｏｎｔｒｏｌｌｅｒ　Ａｒｅａ　Ｎｅｔｗｏｒｋ）に接続される。ＣＡＮは、車内ＬＡＮとして用いられるシリアル通信規格の一つである。また、ＥＣＵは、マイクロコンピュータを含む。また、ＥＣＵは、ＣＰＵまたはＧＰＵを用いる。 Although not shown, when connecting to an external charger, the outlet of the charger or the connection cable of the charger is electrically connected to the battery controller 1302. Power supplied from an external charger charges the first batteries 1301a and 1301b via the battery controller 1302. Further, depending on the charger, a control circuit is provided and the function of the battery controller 1302 is not used in some cases, but in order to prevent overcharging, the first batteries 1301a and 1301b are charged via the control circuit section 1320. It is preferable. In some cases, the connecting cable or the connecting cable of the charger is provided with a control circuit. The control circuit section 1320 is sometimes called an ECU (Electronic Control Unit). The ECU is connected to a CAN (Controller Area Network) provided in the electric vehicle. CAN is one of the serial communication standards used as an in-vehicle LAN. Further, the ECU includes a microcomputer. Further, the ECU uses a CPU or a GPU.
　充電スタンドなどに設置されている外部の充電器は、１００Ｖコンセント−２００Ｖコンセント、または３相２００Ｖ且つ５０ｋＷなどがある。また、非接触給電方式等により外部の充電設備から電力供給を受けて、充電することもできる。 External chargers installed at charging stations etc. include 100V outlet-200V outlet, or 3-phase 200V and 50kW. It is also possible to charge the battery by receiving power from an external charging facility using a non-contact power supply method or the like.
　急速充電を行う場合、短時間での充電を行うためには、高電圧での充電に耐えうる二次電池が望まれている。 When performing rapid charging, a secondary battery that can withstand high voltage charging is desired in order to perform charging in a short time.
　また、導電材としてグラフェンを用い、電極層を厚くして担持量を高くしても容量低下を抑え、高容量を維持することが相乗効果として大幅に電気特性が向上された二次電池を実現できる。特に車両に用いる二次電池に有効であり、車両全重量に対する二次電池の重量の割合を増加させることなく、航続距離が長い、具体的には一充電走行距離が５００ｋｍ以上の車両を提供することができる。 In addition, by using graphene as a conductive material, the capacity decrease is suppressed even when the electrode layer is made thicker and the loading amount is increased, and the synergistic effect of maintaining high capacity has resulted in a secondary battery with significantly improved electrical characteristics. can. It is particularly effective for secondary batteries used in vehicles, and provides a vehicle with a long cruising range, specifically a cruising range of 500 km or more on one charge, without increasing the weight ratio of the secondary battery to the total vehicle weight. be able to.
　特に上述した本実施の形態の二次電池は、実施の形態１で説明した正極活物質１０１を用いることで二次電池の動作電圧を高くすることができ、充電電圧の増加に伴い、使用できる容量を増加させることができる。また、実施の形態１で説明した正極活物質１０１を正極に用いることで安全性に優れた車両用の二次電池を提供することができる。 In particular, the secondary battery of this embodiment described above can have a high operating voltage by using the positive electrode active material 101 described in Embodiment 1, and can be used as the charging voltage increases. Capacity can be increased. Further, by using the positive electrode active material 101 described in Embodiment 1 for the positive electrode, a secondary battery for a vehicle with excellent safety can be provided.
　次に、本発明の一態様である二次電池を車両、代表的には輸送用車両に実装する例について説明する。 Next, an example in which a secondary battery, which is one embodiment of the present invention, is mounted in a vehicle, typically a transportation vehicle, will be described.
　図１２Ｄ、図１４Ｃ、図１７Ａのいずれか一に示した二次電池を車両に搭載すると、ハイブリッド車（ＨＶ）、電気自動車（ＥＶ）、又はプラグインハイブリッド車（ＰＨＶ）等の次世代クリーンエネルギー自動車を実現できる。また、農業機械、電動アシスト自転車を含む原動機付自転車、自動二輪車、電動車椅子、電動カート、船舶、潜水艦、航空機、ロケット、人工衛星、宇宙探査機、惑星探査機、または宇宙船に二次電池を搭載することもできる。本発明の一態様の二次電池は高容量の二次電池とすることができる。そのため本発明の一態様の二次電池は、小型化、軽量化に適しており、輸送用車両に好適に用いることができる。 When the secondary battery shown in any one of Fig. 12D, Fig. 14C, and Fig. 17A is installed in a vehicle, next-generation clean energy such as a hybrid vehicle (HV), electric vehicle (EV), or plug-in hybrid vehicle (PHV) can be realized. A car can be realized. We also install secondary batteries in agricultural machinery, motorized bicycles including electric assist bicycles, motorcycles, electric wheelchairs, electric carts, ships, submarines, aircraft, rockets, artificial satellites, space probes, planetary probes, or spacecraft. It can also be installed. The secondary battery of one embodiment of the present invention can be a high capacity secondary battery. Therefore, the secondary battery of one embodiment of the present invention is suitable for reduction in size and weight, and can be suitably used for transportation vehicles.
　図１８Ａ乃至図１８Ｄにおいて、本発明の一態様を用いた輸送用車両を例示する。図１８Ａに示す自動車２００１は、走行のための動力源として電気モータを用いる電気自動車である。または、走行のための動力源として電気モータとエンジンを適宜選択して用いることが可能なハイブリッド自動車である。二次電池を車両に搭載する場合、実施の形態５で示した二次電池の一例を一箇所または複数個所に設置する。図１８Ａに示す自動車２００１は、電池パック２２００を有し、電池パックは、複数の二次電池を接続させた二次電池モジュールを有する。さらに二次電池モジュールに電気的に接続する充電制御装置を有すると好ましい。 18A to 18D illustrate a transportation vehicle using one embodiment of the present invention. A car 2001 shown in FIG. 18A is an electric car that uses an electric motor as a power source for driving. Alternatively, it is a hybrid vehicle that can appropriately select and use an electric motor and an engine as a power source for driving. When a secondary battery is mounted on a vehicle, the example of the secondary battery shown in Embodiment 5 is installed at one or multiple locations. A car 2001 shown in FIG. 18A includes a battery pack 2200, and the battery pack includes a secondary battery module to which a plurality of secondary batteries are connected. Furthermore, it is preferable to include a charging control device electrically connected to the secondary battery module.
　また、自動車２００１は、自動車２００１が有する二次電池にプラグイン方式または非接触給電方式等により外部の充電設備から電力供給を受けて、充電することができる。充電に際しては、充電方法またはコネクタの規格等はＣＨＡｄｅＭＯ（登録商標）またはコンボ等の所定の方式で適宜行えばよい。充電設備は、商用施設に設けられた充電ステーションでもよく、また家庭の電源であってもよい。例えば、プラグイン技術によって、外部からの電力供給により自動車２００１に搭載された蓄電装置を充電することができる。充電は、ＡＣＤＣコンバータ等の変換装置を介して、交流電力を直流電力に変換して行うことができる。 Further, the automobile 2001 can be charged by receiving power from an external charging facility using a plug-in method, a non-contact power supply method, or the like to a secondary battery of the automobile 2001. When charging, a predetermined charging method or connector standard such as CHAdeMO (registered trademark) or combo may be used as appropriate. The charging equipment may be a charging station provided at a commercial facility or may be a home power source. For example, using plug-in technology, it is possible to charge the power storage device mounted on the vehicle 2001 by supplying power from the outside. Charging can be performed by converting AC power into DC power via a conversion device such as an ACDC converter.
　また、図示しないが、受電装置を車両に搭載し、地上の送電装置から電力を非接触で供給して充電することもできる。この非接触給電方式の場合には、道路または外壁に送電装置を組み込むことで、停車中に限らず走行中に充電を行うこともできる。また、この非接触給電の方式を利用して、２台の車両同士で電力の送受電を行ってもよい。さらに、車両の外装部に太陽電池を設け、停車時または走行時に二次電池の充電を行ってもよい。このような非接触での電力の供給には、電磁誘導方式または磁界共鳴方式を用いることができる。 Although not shown, a power receiving device can be mounted on a vehicle, and power can be supplied from a ground power transmitting device in a non-contact manner for charging. In the case of this non-contact power supply method, by incorporating a power transmission device into the road or outside wall, charging can be performed not only while the vehicle is stopped but also while the vehicle is running. Further, electric power may be transmitted and received between two vehicles using this contactless power supply method. Furthermore, a solar cell may be provided on the exterior of the vehicle, and the secondary battery may be charged when the vehicle is stopped or traveling. For such non-contact power supply, an electromagnetic induction method or a magnetic resonance method can be used.
　図１８Ｂは、輸送用車両の一例として電気により制御するモータを有した大型の輸送車２００２を示している。輸送車２００２の二次電池モジュールは、例えば公称電圧３．０Ｖ以上５．０Ｖ以下の二次電池を４個セルユニットとし、４８セルを直列に接続した１７０Ｖの最大電圧とする。電池パック２２０１の二次電池モジュールを構成する二次電池の数などが違う以外は、図１８Ａと同様な機能を備えているので説明は省略する。 FIG. 18B shows a large transport vehicle 2002 having an electrically controlled motor as an example of a transport vehicle. The secondary battery module of the transport vehicle 2002 has a maximum voltage of 170V, for example, in which four secondary batteries with a nominal voltage of 3.0 V or more and 5.0 V or less are connected in series, and 48 cells are connected in series. Except for the difference in the number of secondary batteries constituting the secondary battery module of the battery pack 2201, etc., it has the same functions as those in FIG. 18A, so a description thereof will be omitted.
　図１８Ｃは、一例として電気により制御するモータを有した大型の輸送車両２００３を示している。輸送車両２００３の二次電池モジュールは、例えば公称電圧３．０Ｖ以上５．０Ｖ以下の二次電池を百個以上直列に接続した６００Ｖの最大電圧とする。従って、特性バラツキの小さい二次電池が求められる。実施の形態１乃至３で説明した正極活物質１０１を正極に用いた二次電池を用いることで、安定した電池特性を有する二次電池を製造することができ、歩留まりの観点から低コストで大量生産が可能である。また、電池パック２２０２の二次電池モジュールを構成する二次電池の数などが違う以外は、図１７Ａと同様な機能を備えているので説明は省略する。 FIG. 18C shows, as an example, a large transport vehicle 2003 with an electrically controlled motor. The secondary battery module of the transportation vehicle 2003 has a maximum voltage of 600 V, for example, by connecting in series one hundred or more secondary batteries with a nominal voltage of 3.0 V or more and 5.0 V or less. Therefore, a secondary battery with small variations in characteristics is required. By using a secondary battery in which the positive electrode active material 101 described in Embodiments 1 to 3 is used as a positive electrode, a secondary battery having stable battery characteristics can be manufactured, and from the viewpoint of yield, it can be manufactured in large quantities at low cost. Production is possible. Further, except for the difference in the number of secondary batteries constituting the secondary battery module of the battery pack 2202, etc., it has the same functions as those in FIG. 17A, so a description thereof will be omitted.
　図１８Ｄは、一例として燃料を燃焼するエンジンを有した航空機２００４を示している。図１８Ｄに示す航空機２００４は、離着陸用の車輪を有しているため、輸送車両の一部とも言え、複数の二次電池を接続させて二次電池モジュールを構成し、二次電池モジュールと充電制御装置とを含む電池パック２２０３を有している。 FIG. 18D shows an example aircraft 2004 with an engine that burns fuel. Since the aircraft 2004 shown in FIG. 18D has wheels for takeoff and landing, it can be said to be part of a transportation vehicle, and a secondary battery module is configured by connecting a plurality of secondary batteries, and the aircraft 2004 is connected to a secondary battery module and charged. The battery pack 2203 includes a control device.
　航空機２００４の二次電池モジュールは、例えば４Ｖの二次電池を８個直列に接続した３２Ｖの最大電圧とする。電池パック２２０３の二次電池モジュールを構成する二次電池の数などが異なる以外は、図１８Ａと同様な機能を備えているので説明は省略する。 The secondary battery module of the aircraft 2004 has a maximum voltage of 32V, for example, by connecting eight 4V secondary batteries in series. Except for the difference in the number of secondary batteries constituting the secondary battery module of the battery pack 2203, etc., it has the same functions as those in FIG. 18A, so a description thereof will be omitted.
　図１８Ｅは、一例として二次電池２２０４を備えた人工衛星２００５を示している。人工衛星２００５は宇宙空間で使用されるため、発火による故障のないことが望まれ、安全性に優れた本発明の一態様である二次電池２２０４を備えることが好ましい。また、人工衛星２００５の内部において、保温部材に覆われた状態で二次電池２２０４が搭載されることがさらに好ましい。 FIG. 18E shows an artificial satellite 2005 equipped with a secondary battery 2204 as an example. Since the artificial satellite 2005 is used in outer space, it is desired that there be no failure due to ignition, and it is preferable to include the secondary battery 2204, which is an aspect of the present invention and has excellent safety. Furthermore, it is more preferable that the secondary battery 2204 is mounted inside the artificial satellite 2005 while being covered with a heat insulating member.
（実施の形態４）
　本実施の形態では、二次電池を車両に搭載する一例として、二輪車、自転車に本発明の一態様であるリチウムイオン電池を搭載する例を示す。 (Embodiment 4)
In this embodiment, as an example of mounting a secondary battery on a vehicle, an example will be shown in which a lithium ion battery, which is an embodiment of the present invention, is mounted on a two-wheeled vehicle or a bicycle.
　図１９Ａは、本発明の一態様の蓄電装置を用いた電動自転車の一例である。図１９Ａに示す電動自転車８７００に、本発明の一態様の蓄電装置を適用することができる。本発明の一態様の蓄電装置は例えば、複数の蓄電池と、保護回路と、を有する。 FIG. 19A is an example of an electric bicycle using the power storage device of one embodiment of the present invention. The power storage device of one embodiment of the present invention can be applied to an electric bicycle 8700 illustrated in FIG. 19A. A power storage device according to one embodiment of the present invention includes, for example, a plurality of storage batteries and a protection circuit.
　電動自転車８７００は、蓄電装置８７０２を備える。蓄電装置８７０２は、運転者をアシストするモータに電気を供給することができる。また、蓄電装置８７０２は、持ち運びができ、図１９Ｂに自転車から取り外した状態を示している。また、蓄電装置８７０２は、本発明の一態様の蓄電装置が有する蓄電池８７０１が複数内蔵されており、そのバッテリ残量などを表示部８７０３で表示できるようにしている。また蓄電装置８７０２は、実施の形態６に一例を示した二次電池の充電制御または異常検知が可能な制御回路８７０４を有する。制御回路８７０４は、蓄電池８７０１の正極及び負極と電気的に接続されている。また、実施の形態１で得られる正極活物質１０１を正極に用いた二次電池と組み合わせることで、安全性についての相乗効果が得られる。実施の形態１で得られる正極活物質１０１を正極に用いた二次電池及び制御回路８７０４は、安全性が高く二次電池による火災等の事故撲滅に大きく寄与することができる。 The electric bicycle 8700 includes a power storage device 8702. The power storage device 8702 can supply electricity to a motor that assists the driver. Further, the power storage device 8702 is portable, and FIG. 19B shows a state in which it has been removed from the bicycle. Further, the power storage device 8702 includes a plurality of built-in storage batteries 8701 included in the power storage device of one embodiment of the present invention, and can display the remaining battery level and the like on a display portion 8703. Power storage device 8702 also includes a control circuit 8704 that can control charging or detect abnormality of a secondary battery, an example of which is shown in Embodiment 6. The control circuit 8704 is electrically connected to the positive and negative electrodes of the storage battery 8701. Further, by combining the positive electrode active material 101 obtained in Embodiment 1 with a secondary battery using the positive electrode as the positive electrode, a synergistic effect regarding safety can be obtained. The secondary battery and control circuit 8704 using the positive electrode active material 101 obtained in Embodiment 1 as a positive electrode are highly safe and can greatly contribute to eradicating accidents such as fires caused by secondary batteries.
　図１９Ｃは、本発明の一態様の蓄電装置を用いた二輪車の一例である。図１９Ｃに示すスクータ８６００は、蓄電装置８６０２、サイドミラー８６０１、方向指示灯８６０３を備える。蓄電装置８６０２は、方向指示灯８６０３に電気を供給することができる。また、実施の形態１で得られる正極活物質１０１を正極に用いた二次電池を複数収納された蓄電装置８６０２は高容量とすることができ、小型化に寄与することができる。 FIG. 19C is an example of a two-wheeled vehicle using the power storage device of one embodiment of the present invention. A scooter 8600 shown in FIG. 19C includes a power storage device 8602, a side mirror 8601, and a direction indicator light 8603. The power storage device 8602 can supply electricity to the direction indicator light 8603. Further, the power storage device 8602 that houses a plurality of secondary batteries using the positive electrode active material 101 obtained in Embodiment 1 as a positive electrode can have a high capacity and can contribute to miniaturization.
　また、図１９Ｃに示すスクータ８６００は、座席下収納８６０４に、蓄電装置８６０２を収納することができる。蓄電装置８６０２は、座席下収納８６０４が小型であっても、座席下収納８６０４に収納することができる。 Furthermore, the scooter 8600 shown in FIG. 19C can store a power storage device 8602 in an under-seat storage 8604. The power storage device 8602 can be stored in the under-seat storage 8604 even if the under-seat storage 8604 is small.
（実施の形態５）
　本実施の形態では、本発明の一態様である二次電池を電子機器に実装する例について説明する。二次電池を実装する電子機器として、例えば、テレビジョン装置（テレビ、又はテレビジョン受信機ともいう）、コンピュータ用などのモニタ、デジタルカメラ、デジタルビデオカメラ、デジタルフォトフレーム、携帯電話機（携帯電話、携帯電話装置ともいう）、携帯型ゲーム機、携帯情報端末、音響再生装置、パチンコ機などの大型ゲーム機などが挙げられる。携帯情報端末としてはノート型パーソナルコンピュータ、タブレット型端末、電子書籍端末、携帯電話機などがある。 (Embodiment 5)
In this embodiment, an example in which a secondary battery, which is one embodiment of the present invention, is mounted in an electronic device will be described. Examples of electronic devices incorporating secondary batteries include television devices (also called televisions or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (mobile phones, Examples include mobile phone devices (also referred to as mobile phone devices), portable game machines, personal digital assistants, audio playback devices, and large game machines such as pachinko machines. Examples of portable information terminals include notebook personal computers, tablet terminals, electronic book terminals, and mobile phones.
　図２０Ａは、携帯電話機の一例を示している。携帯電話機２１００は、筐体２１０１に組み込まれた表示部２１０２の他、操作ボタン２１０３、外部接続ポート２１０４、スピーカ２１０５、マイク２１０６などを備えている。なお、携帯電話機２１００は、二次電池２１０７を有している。実施の形態１で説明した正極活物質１０１を正極に用いた二次電池２１０７を備えることで高容量とすることができ、筐体の小型化に伴う省スペース化に対応できる構成を実現することができる。 FIG. 20A shows an example of a mobile phone. The mobile phone 2100 includes a display section 2102 built into a housing 2101, as well as operation buttons 2103, an external connection port 2104, a speaker 2105, a microphone 2106, and the like. Note that the mobile phone 2100 includes a secondary battery 2107. By providing a secondary battery 2107 in which the positive electrode active material 101 described in Embodiment 1 is used as a positive electrode, a high capacity can be achieved, and a configuration can be realized that can accommodate space saving due to downsizing of the housing. Can be done.
　携帯電話機２１００は、移動電話、電子メール、文章閲覧及び作成、音楽再生、インターネット通信、コンピュータゲームなどの種々のアプリケーションを実行することができる。 The mobile phone 2100 can execute various applications such as mobile phone calls, e-mail, text viewing and creation, music playback, Internet communication, computer games, etc.
　操作ボタン２１０３は、時刻設定のほか、電源のオン、オフ動作、無線通信のオン、オフ動作、マナーモードの実行及び解除、省電力モードの実行及び解除など、様々な機能を持たせることができる。例えば、携帯電話機２１００に組み込まれたオペレーティングシステムにより、操作ボタン２１０３の機能を自由に設定することもできる。 In addition to setting the time, the operation button 2103 can have various functions such as turning on and off the power, turning on and off wireless communication, executing and canceling silent mode, and executing and canceling power saving mode. . For example, the functions of the operation buttons 2103 can be freely set using the operating system built into the mobile phone 2100.
　また、携帯電話機２１００は、通信規格された近距離無線通信を実行することが可能である。例えば無線通信可能なヘッドセットと相互通信することによって、ハンズフリーで通話することもできる。 Furthermore, the mobile phone 2100 is capable of performing short-range wireless communication according to communication standards. For example, by communicating with a headset capable of wireless communication, it is also possible to make hands-free calls.
　また、携帯電話機２１００は、外部接続ポート２１０４を備え、他の情報端末とコネクタを介して直接データのやりとりを行うことができる。また外部接続ポート２１０４を介して充電を行うこともできる。なお、充電動作は外部接続ポート２１０４を介さずに無線給電により行ってもよい。 Furthermore, the mobile phone 2100 is equipped with an external connection port 2104, and can directly exchange data with other information terminals via a connector. Charging can also be performed via the external connection port 2104. Note that the charging operation may be performed by wireless power supply without using the external connection port 2104.
　また、携帯電話機２１００は、センサを有することが好ましい。センサとしては、例えば、指紋センサ、脈拍センサ、体温センサ等の人体センサ、タッチセンサ、加圧センサ、または加速度センサ等が搭載されることが好ましい。 Furthermore, it is preferable that the mobile phone 2100 has a sensor. As the sensor, it is preferable to include, for example, a human body sensor such as a fingerprint sensor, a pulse sensor, a body temperature sensor, a touch sensor, a pressure sensor, an acceleration sensor, or the like.
　また、携帯電話機２１００は外部バッテリ２１５０を有する構成としてもよい。外部バッテリ２１５０は二次電池と、複数の端子２１５１を有する。外部バッテリ２１５０はケーブル２１５２等を介して携帯電話機２１００等への充電が可能である。本発明の一態様の正極活物質を外部バッテリ２１５０が有する二次電池に用いることで、高性能な外部バッテリ２１５０とすることができる。また携帯電話機２１００本体が有する二次電池２１０７の容量が小さくても、外部バッテリ２１５０から充電することで長時間の使用が可能となる。そのため携帯電話機２１００本体を小型化および／または軽量化し、かつ安全性を向上させることが可能となる。また外部バッテリ２１５０のみの製品としてもよい。外部バッテリ２１５０は携帯電話機２１００以外にも、各種の携帯情報端末に充電をすることが可能である。 Additionally, the mobile phone 2100 may be configured to include an external battery 2150. External battery 2150 has a secondary battery and a plurality of terminals 2151. The external battery 2150 can charge a mobile phone 2100 or the like via a cable 2152 or the like. By using the positive electrode active material of one embodiment of the present invention for a secondary battery included in the external battery 2150, the external battery 2150 can have high performance. Furthermore, even if the capacity of the secondary battery 2107 included in the main body of the mobile phone 2100 is small, it can be used for a long time by charging from the external battery 2150. Therefore, it is possible to make the main body of the mobile phone 2100 smaller and/or lighter, and to improve safety. Alternatively, the product may include only the external battery 2150. The external battery 2150 can charge various types of portable information terminals in addition to the mobile phone 2100.
　図２０Ｂは、複数のローター２３０２を有する無人航空機２３００である。無人航空機２３００はドローンと呼ばれることもある。無人航空機２３００は、本発明の一態様である二次電池２３０１と、カメラ２３０３と、アンテナ（図示しない）を有する。無人航空機２３００はアンテナを介して遠隔操作することができる。実施の形態１で得られる正極活物質１０１を正極に用いた二次電池は高エネルギー密度であり、安全性が高いため、長期間に渡って長時間の安全な使用ができ、無人航空機２３００に搭載する二次電池として好適である。 FIG. 20B is an unmanned aircraft 2300 with multiple rotors 2302. Unmanned aerial vehicle 2300 is sometimes called a drone. Unmanned aircraft 2300 includes a secondary battery 2301, which is one embodiment of the present invention, a camera 2303, and an antenna (not shown). Unmanned aerial vehicle 2300 can be remotely controlled via an antenna. A secondary battery using the positive electrode active material 101 obtained in Embodiment 1 as a positive electrode has a high energy density and is highly safe, so it can be used safely for a long time and is suitable for use in the unmanned aerial vehicle 2300. It is suitable as a secondary battery to be mounted.
　図２０Ｃは、ロボットの一例を示している。図２０Ｃに示すロボット６４００は、二次電池６４０９、照度センサ６４０１、マイクロフォン６４０２、上部カメラ６４０３、スピーカ６４０４、表示部６４０５、下部カメラ６４０６及び障害物センサ６４０７、移動機構６４０８、演算装置等を備える。 FIG. 20C shows an example of a robot. The robot 6400 shown in FIG. 20C includes a secondary battery 6409, an illuminance sensor 6401, a microphone 6402, an upper camera 6403, a speaker 6404, a display section 6405, a lower camera 6406, an obstacle sensor 6407, a movement mechanism 6408, a calculation device, and the like.
　マイクロフォン６４０２は、使用者の話し声及び環境音等を検知する機能を有する。また、スピーカ６４０４は、音声を発する機能を有する。ロボット６４００は、マイクロフォン６４０２及びスピーカ６４０４を用いて、使用者とコミュニケーションをとることが可能である。 The microphone 6402 has a function of detecting the user's speaking voice, environmental sounds, and the like. Furthermore, the speaker 6404 has a function of emitting sound. The robot 6400 can communicate with a user using a microphone 6402 and a speaker 6404.
　表示部６４０５は、種々の情報の表示を行う機能を有する。ロボット６４００は、使用者の望みの情報を表示部６４０５に表示することが可能である。表示部６４０５は、タッチパネルを搭載していてもよい。また、表示部６４０５は取り外しのできる情報端末であっても良く、ロボット６４００の定位置に設置することで、充電及びデータの受け渡しを可能とする。 The display unit 6405 has a function of displaying various information. The robot 6400 can display information desired by the user on the display section 6405. The display unit 6405 may include a touch panel. Further, the display unit 6405 may be a removable information terminal, and by installing it at a fixed position on the robot 6400, charging and data exchange are possible.
　上部カメラ６４０３及び下部カメラ６４０６は、ロボット６４００の周囲を撮像する機能を有する。また、障害物センサ６４０７は、移動機構６４０８を用いてロボット６４００が前進する際の進行方向における障害物の有無を察知することができる。ロボット６４００は、上部カメラ６４０３、下部カメラ６４０６及び障害物センサ６４０７を用いて、周囲の環境を認識し、安全に移動することが可能である。 The upper camera 6403 and the lower camera 6406 have a function of capturing images around the robot 6400. Further, the obstacle sensor 6407 can detect the presence or absence of an obstacle in the direction of movement of the robot 6400 when the robot 6400 moves forward using the moving mechanism 6408. The robot 6400 uses an upper camera 6403, a lower camera 6406, and an obstacle sensor 6407 to recognize the surrounding environment and can move safely.
　ロボット６４００は、その内部領域に本発明の一態様に係る二次電池６４０９と、半導体装置または電子部品を備える。実施の形態１で得られる正極活物質１０１を正極に用いた二次電池は高エネルギー密度であり、安全性が高いため、長期間に渡って長時間の安全な使用ができ、ロボット６４００に搭載する二次電池６４０９として好適である。 The robot 6400 includes a secondary battery 6409 according to one embodiment of the present invention and a semiconductor device or electronic component in its internal area. A secondary battery using the cathode active material 101 obtained in Embodiment 1 as a cathode has high energy density and is highly safe, so it can be used safely for a long time and can be mounted on the robot 6400. It is suitable as the secondary battery 6409.
　図２０Ｄは、掃除ロボットの一例を示している。掃除ロボット６３００は、筐体６３０１上面に配置された表示部６３０２、側面に配置された複数のカメラ６３０３、ブラシ６３０４、操作ボタン６３０５、二次電池６３０６、各種センサなどを有する。図示されていないが、掃除ロボット６３００には、タイヤ、吸い込み口等が備えられている。掃除ロボット６３００は自走し、ゴミ６３１０を検知し、下面に設けられた吸い込み口からゴミを吸引することができる。 FIG. 20D shows an example of a cleaning robot. The cleaning robot 6300 includes a display portion 6302 placed on the top surface of a housing 6301, a plurality of cameras 6303 placed on the side, a brush 6304, an operation button 6305, a secondary battery 6306, various sensors, and the like. Although not shown, the cleaning robot 6300 is equipped with tires, a suction port, and the like. The cleaning robot 6300 is self-propelled, detects dirt 6310, and can suck the dirt from a suction port provided on the bottom surface.
　掃除ロボット６３００は、カメラ６３０３が撮影した画像を解析し、壁、家具または段差などの障害物の有無を判断することができる。また、画像解析により、配線などブラシ６３０４に絡まりそうな物体を検知した場合は、ブラシ６３０４の回転を止めることができる。掃除ロボット６３００は、その内部領域に本発明の一態様に係る二次電池６３０６と、半導体装置または電子部品を備える。実施の形態１で得られる正極活物質１０１を正極に用いた二次電池は高エネルギー密度であり、安全性が高いため、長期間に渡って長時間の安全な使用ができ、掃除ロボット６３００に搭載する二次電池６３０６として好適である。 The cleaning robot 6300 can analyze the image taken by the camera 6303 and determine the presence or absence of obstacles such as walls, furniture, or steps. Furthermore, if an object such as wiring that is likely to become entangled with the brush 6304 is detected through image analysis, the rotation of the brush 6304 can be stopped. The cleaning robot 6300 includes a secondary battery 6306 according to one embodiment of the present invention and a semiconductor device or an electronic component in its internal area. A secondary battery using the positive electrode active material 101 obtained in Embodiment 1 as a positive electrode has a high energy density and is highly safe, so it can be used safely for a long time and is suitable for the cleaning robot 6300. This is suitable as the secondary battery 6306 to be mounted.
（実施の形態６）
　本実施の形態では、二次電池の熱暴走、及び釘刺し試験等について説明し、本発明の一形態である正極活物質１０１を用いた二次電池に対して釘刺し試験を実施すると発火に至りにくい原理等を説明する。 (Embodiment 6)
In this embodiment, thermal runaway of a secondary battery, a nail penetration test, etc. will be explained, and it will be explained that when a nail penetration test is performed on a secondary battery using the positive electrode active material 101 which is one embodiment of the present invention, ignition occurs. Explain the principles behind this.
＜二次電池の熱暴走＞
　非特許文献４の第６９頁［図２−１１］に示したグラフを引用し、一部を修正して図２１に示す。図２１は時間に対する二次電池の内部温度（以下、単に温度と記す）のグラフであり、温度が上昇すると、いくつかの状態を経て熱暴走に至ることを示している。 <Thermal runaway of secondary batteries>
The graph shown on page 69 [FIG. 2-11] of Non-Patent Document 4 is quoted and shown in FIG. 21 with some modifications. FIG. 21 is a graph of the internal temperature of the secondary battery (hereinafter simply referred to as temperature) versus time, and shows that as the temperature rises, thermal runaway occurs through several states.
　二次電池の温度が１００℃及びその近傍になると、（１）負極のＳＥＩ（Ｓｏｌｉｄ　Ｅｌｅｃｔｒｏｌｙｔｅ　Ｉｎｔｅｒｐｈａｓｅ）の崩壊と発熱が生じる。また二次電池の温度１００℃を超えると（２）負極（黒鉛を用いた場合、負極はＣ６Ｌｉとなる）による電解液の還元と発熱が生じ、（３）正極による電解液の酸化と発熱が生じる。そして、二次電池の温度が１８０℃及びその近傍になると（４）電解液の熱分解が生じ、（５）正極からの酸素放出と熱分解（当該熱分解には正極活物質の構造変化が含まれる）が生じる。その後、二次電池の温度が２００℃を超えると（６）負極の分解が生じ、最後に（７）正極と負極の直接接触となる。上述した（５）の状態、（６）の状態、又は（７）の状態等を経て、二次電池は熱暴走に至る。すなわち熱暴走に至らないようにするためには、二次電池の温度上昇を抑制すること、および負極、正極及び／又は電解液が１００℃を超えるような高温時に安定な状態が保つことが求められる。 When the temperature of the secondary battery reaches 100° C. or around 100° C., (1) SEI (Solid Electrolyte Interphase) of the negative electrode collapses and heat is generated. Furthermore, if the temperature of the secondary battery exceeds 100°C, (2) the negative electrode (if graphite is used, the negative electrode becomes C 6 Li) will reduce the electrolyte and generate heat, and (3) the positive electrode will oxidize the electrolyte and generate heat. Fever occurs. When the temperature of the secondary battery reaches 180°C or around 180°C, (4) thermal decomposition of the electrolyte occurs, and (5) oxygen is released from the positive electrode and thermal decomposition occurs (the thermal decomposition involves a structural change in the positive electrode active material). ) occurs. Thereafter, when the temperature of the secondary battery exceeds 200° C., (6) the negative electrode decomposes, and finally (7) the positive electrode and negative electrode come into direct contact. The secondary battery reaches thermal runaway after going through the above-mentioned state (5), (6), or (7). In other words, in order to prevent thermal runaway, it is necessary to suppress the temperature rise of the secondary battery, and to maintain a stable state at high temperatures of the negative electrode, positive electrode and/or electrolyte exceeding 100°C. It will be done.
　本発明の一形態である正極活物質１０１は、安定な結晶構造を有しており、さらに酸素脱離が抑制されるといった効果を奏する。そのため正極活物質１０１を用いた二次電池は、少なくとも上記（５）以降の状態に至らず二次電池の温度上昇が抑制されると考えられ、熱暴走に至りにくいという顕著な効果を奏する。 The positive electrode active material 101, which is one embodiment of the present invention, has a stable crystal structure and has the effect of suppressing oxygen desorption. Therefore, it is thought that the secondary battery using the positive electrode active material 101 does not reach at least the state after the above (5), and the temperature rise of the secondary battery is suppressed, and has the remarkable effect of being less likely to cause thermal runaway.
＜釘刺し試験＞
　次に、釘刺し試験について、図２２Ａ乃至図２２Ｃ等を用いて説明する。釘刺し試験とは、二次電池５００に、２ｍｍ以上１０ｍｍ以下から選ばれた所定の直径を満たす釘１００３を、１ｍｍ／ｓ以上２０ｍｍ／ｓ以下等から選ばれた所定の速度で刺しこむ試験である。本実施の形態および後述する本実施例等では、二次電池５００を満充電（Ｓｔａｔｅｓ　Ｏｆ　Ｃｈａｒｇｅ：ＳＯＣ１００％の状態）として行うこととする。図２２Ａは二次電池５００に釘１００３を刺した状態の断面図を示す。二次電池５００は、正極５０３、セパレータ５０７、負極５０６、及び電解液５３０が外装体５３１に収容された構造を有する。正極５０３は正極集電体５０１と、その両面に形成された正極活物質層５０２を有し、負極５０６は負極集電体５０４と、その片面または両面に形成された負極活物質層５０５を有する。また図２２Ｂは釘１００３及び正極集電体５０１の拡大図を示しており、正極活物質層５０２が有する本発明の一形態である正極活物質１０１、及び導電材５５３を明示する。また図２２Ｃは正極活物質１０１の拡大図を示す。正極活物質１０１は上記実施の形態で説明したとおりの特徴を有する。 <Nail penetration test>
Next, the nail penetration test will be explained using FIGS. 22A to 22C and the like. The nail penetration test is a test in which a nail 1003 satisfying a predetermined diameter selected from 2 mm or more and 10 mm or less is inserted into the secondary battery 500 at a predetermined speed selected from 1 mm/s or more and 20 mm/s or less. be. In this embodiment and the examples described below, the secondary battery 500 is fully charged (States of Charge: SOC 100%). FIG. 22A shows a cross-sectional view of the secondary battery 500 with a nail 1003 inserted therein. The secondary battery 500 has a structure in which a positive electrode 503, a separator 507, a negative electrode 506, and an electrolyte 530 are housed in an exterior body 531. The positive electrode 503 has a positive electrode current collector 501 and a positive electrode active material layer 502 formed on both sides thereof, and the negative electrode 506 has a negative electrode current collector 504 and a negative electrode active material layer 505 formed on one or both sides thereof. . Further, FIG. 22B shows an enlarged view of the nail 1003 and the positive electrode current collector 501, and clearly shows the positive electrode active material 101, which is one embodiment of the present invention, and the conductive material 553, which the positive electrode active material layer 502 has. Moreover, FIG. 22C shows an enlarged view of the positive electrode active material 101. The positive electrode active material 101 has the characteristics as described in the above embodiment.
　図２２Ａ及び図２２Ｂに示すように、釘１００３が正極５０３、及び負極５０６を貫通すると、内部短絡が生じる。すると釘１００３の電位が負極の電位と等しくなり、釘１００３等を介して、矢印で示したように電子（ｅ−）が正極５０３へ流れ、内部短絡箇所及びその近傍にはジュール熱が発生する。また内部短絡により、負極５０６から脱離したキャリアイオン、代表的にはリチウムイオン（Ｌｉ＋）は白抜き矢印のように電解液へ放出される。ここで、電解液５３０のアニオンが不足している場合、負極５０６から電解液５３０へとリチウムイオンが放出されると、電解液５３０の電気的中性が保たれなくなるため、電解液５３０は電気的中性を保つように分解し始める。これは負極による電解液の還元反応と呼ぶ。そして、正極５０３に流れてきた電子（ｅ−）により、充電状態のＮＣＭにおいて４価であった遷移金属Ｍは還元されて３価又は２価にとなり、この還元反応によりＮＣＭから酸素が脱離し、さらに電解液５３０は脱離した酸素等によって分解される。これは正極による電解液の酸化反応と呼ぶ。 As shown in FIGS. 22A and 22B, when the nail 1003 penetrates the positive electrode 503 and the negative electrode 506, an internal short circuit occurs. Then, the potential of the nail 1003 becomes equal to the potential of the negative electrode, and electrons (e − ) flow through the nail 1003 and the like to the positive electrode 503 as shown by the arrow, and Joule heat is generated at the internal short circuit and its vicinity. . Furthermore, due to the internal short circuit, carrier ions, typically lithium ions (Li + ), released from the negative electrode 506 are released into the electrolytic solution as indicated by the white arrow. Here, if there is a shortage of anions in the electrolytic solution 530 and lithium ions are released from the negative electrode 506 to the electrolytic solution 530, the electrical neutrality of the electrolytic solution 530 will no longer be maintained. Start disassembling it to keep it accurate. This is called a reduction reaction of the electrolyte by the negative electrode. Then, the transition metal M, which was tetravalent in the charged NCM, is reduced to trivalent or divalent by the electrons (e − ) flowing to the positive electrode 503, and oxygen is desorbed from the NCM by this reduction reaction. Furthermore, the electrolytic solution 530 is decomposed by the released oxygen and the like. This is called an oxidation reaction of the electrolyte by the positive electrode.
　また、二次電池の内部短絡が生じると、温度が図２３に示すグラフのように変化する。図２３は、非特許文献４の第７０頁［図２−１２］に示したグラフを引用し、一部修正した図であり、時間に対する二次電池の温度のグラフであり、（Ｐ０）で内部短絡が生じると、時間とともに二次電池の温度が上昇することを示している。具体的には（Ｐ１）に示すようにジュール熱による発熱が続き、二次電池の温度が１００℃及びその近傍になると、二次電池の基準温度（Ｔｓ）を超えてしまう。すると（Ｐ２）では負極（黒鉛を用いた場合、負極はＣ６Ｌｉとなる）による電解液の還元と発熱が生じ、（Ｐ３）では正極による電解液の酸化と発熱が生じ、（Ｐ４）では電解液の熱分解による発熱が生じる。そして二次電池は熱暴走し、発火等に至る。 Further, when an internal short circuit occurs in the secondary battery, the temperature changes as shown in the graph shown in FIG. 23. FIG. 23 is a partially revised graph based on the graph shown on page 70 [FIG. 2-12] of Non-Patent Document 4, and is a graph of the temperature of the secondary battery against time, and is a graph of the temperature of the secondary battery with respect to time. This shows that when an internal short circuit occurs, the temperature of the secondary battery increases over time. Specifically, as shown in (P1), when heat generation due to Joule heat continues and the temperature of the secondary battery reaches or near 100°C, it exceeds the standard temperature (Ts) of the secondary battery. Then, in (P2), the electrolyte is reduced and heat is generated by the negative electrode (when graphite is used, the negative electrode becomes C 6 Li), in (P3), the electrolyte is oxidized and heat is generated by the positive electrode, and in (P4), the electrolyte is oxidized and heat is generated by the positive electrode. Heat generation occurs due to thermal decomposition of the electrolyte. The secondary battery then undergoes thermal runaway, leading to fire, etc.
　このとき正極活物質では、急激に正極活物質に流入する電子により、遷移金属Ｍが還元され（たとえばコバルトがＣｏ４＋からＣｏ２＋になり）、正極活物質から酸素が放出される反応が生じている。この反応は発熱反応であるため、熱暴走に正のフィードバックがかかってしまう。すなわちこの反応を抑制できれば熱暴走しにくい正極活物質とすることができる。 At this time, in the positive electrode active material, the transition metal M is reduced by the electrons rapidly flowing into the positive electrode active material (for example, cobalt changes from Co 4+ to Co 2+ ), and a reaction occurs in which oxygen is released from the positive electrode active material. There is. Since this reaction is exothermic, positive feedback is applied to thermal runaway. That is, if this reaction can be suppressed, a positive electrode active material that is less likely to undergo thermal runaway can be obtained.
　そのため上記反応の場となりやすい正極活物質の表層部は、酸素を放出しにくい結晶構造であることが好ましい。または酸素を放出しにくい金属の濃度が高いことが好ましい。正極活物質から酸素が放出されにくければ、上記還元反応（たとえばＣｏ４＋からＣｏ２＋になる反応）も抑制される。酸素を放出しにくい金属とは、安定な金属酸化物を形成する金属であり、たとえばマグネシウム、アルミニウム等が挙げられる。またニッケルも、リチウムサイトに存在する場合は酸素放出を抑制する効果があると考えられる。また、正極集電体に用いられたアルミニウム箔と、正極活物質とのテルミット反応を抑制する効果があると考えられる。 Therefore, it is preferable that the surface layer portion of the positive electrode active material, which tends to become a site for the above-mentioned reaction, has a crystal structure that makes it difficult to release oxygen. Alternatively, it is preferable that the concentration of a metal that is difficult to release oxygen is high. If oxygen is difficult to be released from the positive electrode active material, the above-mentioned reduction reaction (for example, the reaction from Co 4+ to Co 2+ ) is also suppressed. The metal that does not easily release oxygen is a metal that forms a stable metal oxide, such as magnesium and aluminum. Nickel is also considered to have the effect of suppressing oxygen release when present at the lithium site. It is also thought to have the effect of suppressing thermite reaction between the aluminum foil used for the positive electrode current collector and the positive electrode active material.
　本発明の一形態である正極活物質１０１を用いた二次電池に釘刺し試験を実施すると、上記正極活物質１０１は上述したバリア膜を有するため酸素放出が抑制されるという特異な効果を奏し、電解液の酸化反応が抑制され発熱も抑えられると考えられる。さらに正極活物質１０１によれば、表層部のバリア膜が絶縁体に近い特性であるため内部短絡時に正極へ流れ込む電流の速度が緩やかになると考えられる。さすれば熱暴走しづらく、発火等に至りにくいという顕著な効果が期待される。 When a nail penetration test was performed on a secondary battery using the positive electrode active material 101 which is one embodiment of the present invention, it was found that the positive electrode active material 101 had the unique effect of suppressing oxygen release because it had the above-mentioned barrier film. It is thought that the oxidation reaction of the electrolytic solution is suppressed and heat generation is also suppressed. Further, according to the positive electrode active material 101, since the barrier film in the surface layer has characteristics similar to an insulator, it is thought that the speed of current flowing into the positive electrode at the time of an internal short circuit becomes slow. It is expected that this will have the remarkable effect of making it difficult for thermal runaway to occur and for fires to occur.
　また、コバルト等の遷移金属Ｍが還元されても、酸素放出に至る前にリチウムイオンを正極活物質に挿入できれば電気的中性が保たれるため、酸素放出を伴う発熱反応には至らない。そのため、正極活物質に急激に電子が流入しても、リチウムイオンが負極から電解液を経て正極活物質内部に挿入されるまで、正極活物質の結晶構造が安定に保たれていればよい。 Furthermore, even if the transition metal M such as cobalt is reduced, if lithium ions can be inserted into the positive electrode active material before oxygen is released, electrical neutrality is maintained, so an exothermic reaction accompanied by oxygen release does not occur. Therefore, even if electrons suddenly flow into the positive electrode active material, the crystal structure of the positive electrode active material only needs to be kept stable until the lithium ions are inserted from the negative electrode into the positive electrode active material via the electrolyte.
　本実施例では、添加元素を有する正極活物質と、有さない正極活物質を作製し、その安全性を評価した。 In this example, positive electrode active materials with and without additive elements were prepared, and their safety was evaluated.
＜正極活物質の作製＞
　図６Ａおよび図７を参照しながら本実施例における正極活物質について説明する。 <Preparation of positive electrode active material>
The positive electrode active material in this example will be described with reference to FIGS. 6A and 7.
　図６ＡのステップＳ１１１のニッケル源、コバルト源およびマンガン源として硫酸ニッケル、硫酸コバルトおよび硫酸マンガン、キレート剤Ｓ１１３として第１のグリシンを用意した。ステップＳ１１４において水と共にこれらを混合し、酸溶液を得た。該酸溶液において、硫酸コバルト、硫酸ニッケルおよび硫酸マンガンを合わせた濃度が２ｍｏｌ／Ｌとなるようにし、第１のグリシンの濃度は０．１００ｍｏｌ／Ｌとなるようにした。 Nickel sulfate, cobalt sulfate, and manganese sulfate were prepared as the nickel source, cobalt source, and manganese source in step S111 of FIG. 6A, and first glycine was prepared as the chelating agent S113. In step S114, these were mixed with water to obtain an acid solution. In the acid solution, the combined concentration of cobalt sulfate, nickel sulfate, and manganese sulfate was 2 mol/L, and the concentration of the first glycine was 0.100 mol/L.
　図６Ａのアルカリ溶液Ｓ１２１として、純水に溶解させた水酸化ナトリウム（水酸化ナトリウム水溶液）を用意した。水酸化ナトリウムの濃度は５ｍｏｌ／Ｌとなるように調整した。 As the alkaline solution S121 in FIG. 6A, sodium hydroxide dissolved in pure water (sodium hydroxide aqueous solution) was prepared. The concentration of sodium hydroxide was adjusted to 5 mol/L.
　また図６ＡのＳ１２２に示す水は第２のグリシンを含む水溶液とした。これは第２のグリシンの濃度が０．１００ｍｏｌ／Ｌとなるように調整した。第２のグリシンを含む水溶液を張込液ともいう。 In addition, the water shown in S122 of FIG. 6A was an aqueous solution containing the second glycine. This was adjusted so that the second glycine concentration was 0.100 mol/L. The aqueous solution containing the second glycine is also referred to as a filling solution.
　共沈装置の反応容器にバッフル板を設け、張込液を張り、スターラーで回転数１０００ｒｐｍとなるように攪拌し、温度が５０℃、ｐＨが１１．０を維持するように調整し、反応容器上部から窒素を１Ｌ／分となるように供給し、上記ｐＨを維持するように水酸化ナトリウム水溶液を滴下するよう準備した。酸溶液を加える速度は０．１０ｍＬ／分とした。反応容器では共沈反応が進んだ。滴下終了後は、液温を２５℃に保持した。共沈装置には、ＯｐｔｉＭａｘ（メトラー・トレド社製）を用いた（ステップＳ１３１）。 A baffle plate is installed in the reaction container of the coprecipitation device, the charging solution is filled, the stirring is done with a stirrer at a rotation speed of 1000 rpm, the temperature is adjusted to maintain 50°C and the pH is 11.0, and the reaction container is heated. Nitrogen was supplied from the top at a rate of 1 L/min, and preparations were made to drop an aqueous sodium hydroxide solution to maintain the above pH. The rate of addition of the acid solution was 0.10 mL/min. Co-precipitation reaction proceeded in the reaction vessel. After the dropwise addition was completed, the liquid temperature was maintained at 25°C. OptiMax (manufactured by Mettler Toledo) was used as a coprecipitation device (step S131).
　図６ＡのステップＳ１３２として、共沈反応で生成した懸濁液を純水で吸引濾過し、その後アセトンで吸引濾過して、沈殿物を得た。その後ステップＳ１３３に従い沈殿物を真空乾燥炉で２００℃、１２時間乾燥し、複合水酸化物９８を得た。複合水酸化物９８を前駆体と呼ぶことがある。 As step S132 in FIG. 6A, the suspension produced by the coprecipitation reaction was suction-filtered with pure water, and then suction-filtered with acetone to obtain a precipitate. Thereafter, according to step S133, the precipitate was dried in a vacuum drying oven at 200° C. for 12 hours to obtain composite hydroxide 98. The composite hydroxide 98 may be called a precursor.
　次に図７のＳ１４１のリチウム源として水酸化リチウムを用意した。水酸化リチウムは流動層式ジェットミルで１００００ｒｐｍ、５０分以上解砕した。本実施例ではＳ１４１では添加元素源を混合しなかった。ステップＳ１４２において、上記前駆体に対する水酸化リチウムのｍｏｌ比（これをＬｉ／ＣｏまたはＬｉ／（Ｎｉ＋Ｃｏ＋Ｍｎ）と記す）が、１．０１となるように調整し混合した。混合には自転・公転ミキサーを用いて１５００ｒｐｍの混合を３回行った。 Next, lithium hydroxide was prepared as a lithium source in S141 of FIG. Lithium hydroxide was crushed in a fluidized bed jet mill at 10,000 rpm for 50 minutes or more. In this example, no additional element source was mixed in S141. In step S142, the molar ratio of lithium hydroxide to the precursor (hereinafter referred to as Li/Co or Li/(Ni+Co+Mn)) was adjusted and mixed to be 1.01. Mixing was performed three times at 1500 rpm using an autorotating/revolving mixer.
　図７のステップＳ１４３として上記で得た混合物を加熱した。ステップＳ１４３の加熱条件は７００℃で１０時間とした。加熱炉にはローラーハースキルンシミュレーター炉（株式会社ノリタケカンパニー製）を用い、流量１０Ｌ／分で酸素を流した。その後室温まで冷却し、ステップＳ１４４として解砕し、ステップＳ１４５として再び加熱した。ステップＳ１４５の加熱条件は８００℃で１０時間とした他は、ステップＳ１４３と同様に行った。その後室温まで冷却し、ステップＳ１４６として解砕し、複合酸化物９９を得た。複合酸化物９９はこの段階でも正極活物質として機能することができる。またこのような工程を経て得られた正極活物質の原子数比は、原料の秤量時に調整したｍｏｌ比と等しくならない場合もある。 As step S143 in FIG. 7, the mixture obtained above was heated. The heating conditions in step S143 were 700° C. for 10 hours. A roller hearth kiln simulator furnace (manufactured by Noritake Company) was used as the heating furnace, and oxygen was flowed at a flow rate of 10 L/min. Thereafter, it was cooled to room temperature, crushed in step S144, and heated again in step S145. The heating conditions in step S145 were the same as in step S143, except that the heating conditions were 800° C. for 10 hours. Thereafter, it was cooled to room temperature and crushed in step S146 to obtain composite oxide 99. The composite oxide 99 can function as a positive electrode active material even at this stage. Further, the atomic ratio of the positive electrode active material obtained through such a process may not be equal to the molar ratio adjusted at the time of weighing the raw materials.
　図７のステップＳ１５１として添加元素源を用意した。本実施例では添加元素源として炭酸カルシウムを用いた。複合酸化物９９に対して炭酸カルシウムが１モル％となるように調整し、混合した（ステップＳ１５２）。 An additive element source was prepared as step S151 in FIG. In this example, calcium carbonate was used as the additive element source. Calcium carbonate was adjusted to be 1 mol% of composite oxide 99 and mixed (step S152).
　図７のステップＳ１５３として上記で得た混合物を加熱した。ステップＳ１５３の加熱条件は８００℃、２時間とした他は、ステップＳ１４３と同様に行った。その後室温まで冷却し、ステップＳ１５４として解砕し、正極活物質１０１を得た（ステップＳ１７５）。これをサンプル１とした。 As step S153 in FIG. 7, the mixture obtained above was heated. The heating conditions in step S153 were the same as in step S143, except that the heating conditions were 800° C. for 2 hours. Thereafter, it was cooled to room temperature and crushed in step S154 to obtain the positive electrode active material 101 (step S175). This was designated as sample 1.
　ステップＳ１５１以降の工程を行わず、添加元素を加えなかった他はサンプル１と同様に作製したものをサンプル２とした。 Sample 2 was prepared in the same manner as Sample 1, except that the steps after step S151 were not performed and no additional elements were added.
　サンプル１およびサンプル２の作製条件を抜粋して表３に示す。 Table 3 shows an excerpt of the manufacturing conditions for Sample 1 and Sample 2.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
＜二次電池の作製と釘刺し試験＞
　次に正極活物質として上記サンプル１またはサンプル２を有し、負極活物質として黒鉛を有する二次電池を作製し、その安全性試験として釘刺し試験を行った。 <Preparation of secondary battery and nail penetration test>
Next, a secondary battery having Sample 1 or Sample 2 as the positive electrode active material and graphite as the negative electrode active material was produced, and a nail penetration test was conducted as a safety test.
　正極活物質として上記サンプル１またはサンプル２を用意し、導電材としてアセチレンブラック（ＡＢ）を用意し、結着剤としてポリフッ化ビニリデン（ＰＶＤＦ）を用意した。ＰＶＤＦはあらかじめＮ−メチル−２−ピロリドン（ＮＭＰ）に対して重量比で５％の割合で溶解したものを用意した。次に、正極活物質：ＡＢ：ＰＶＤＦ＝９５：３：２（重量比）で混合してスラリーを作製し、当該スラリーを正極集電体に塗工した。正極集電体には厚さ２０μｍのアルミニウム箔（両鏡面）を用いた。スラリーの溶媒としてＮＭＰを用いた。正極集電体にスラリーを塗工した後、溶媒を揮発させた。 The above sample 1 or sample 2 was prepared as a positive electrode active material, acetylene black (AB) was prepared as a conductive material, and polyvinylidene fluoride (PVDF) was prepared as a binder. PVDF was prepared in advance by dissolving it in N-methyl-2-pyrrolidone (NMP) at a weight ratio of 5%. Next, a positive electrode active material: AB:PVDF was mixed at a ratio of 95:3:2 (weight ratio) to prepare a slurry, and the slurry was applied to a positive electrode current collector. Aluminum foil (both mirror surfaces) with a thickness of 20 μm was used as the positive electrode current collector. NMP was used as a solvent for the slurry. After applying the slurry to the positive electrode current collector, the solvent was evaporated.
　その後、上記の正極集電体上の正極活物質層の密度を高めるため、ロールプレス機によってプレス処理を行った。プレス処理の条件は、線圧２１０ｋＮ／ｍとした。なお、ロールプレス機の上部ロール及び下部ロールは、いずれも１２０℃とした。以上の工程により、正極を得た。正極の活物質担持量は、サンプル１は１０．６ｍｇ／ｃｍ２、サンプル２は９．６ｍｇ／ｃｍ２であった。 Thereafter, in order to increase the density of the positive electrode active material layer on the positive electrode current collector, pressing treatment was performed using a roll press machine. The conditions for the press treatment were a linear pressure of 210 kN/m. In addition, both the upper roll and lower roll of the roll press machine were set to 120 degreeC. Through the above steps, a positive electrode was obtained. The amount of active material supported on the positive electrode was 10.6 mg/cm 2 for Sample 1 and 9.6 mg/cm 2 for Sample 2.
　負極活物質として黒鉛を用意した。結着剤としてＣＭＣ及びＳＢＲを用意した。導電材として炭素繊維（昭和電工株式会社製、ＶＧＣＦ（登録商標））を用意した。次に、黒鉛：ＶＧＣＦ：ＣＭＣ：ＳＢＲ＝９７：１：１：１（重量比）で混合してスラリーを作製し、該スラリーを銅の負極集電体に塗工した。スラリーの溶媒として水を用いた。 Graphite was prepared as a negative electrode active material. CMC and SBR were prepared as binders. Carbon fiber (manufactured by Showa Denko K.K., VGCF (registered trademark)) was prepared as a conductive material. Next, a slurry was prepared by mixing graphite:VGCF:CMC:SBR=97:1:1:1 (weight ratio), and the slurry was applied to a copper negative electrode current collector. Water was used as the solvent for the slurry.
　負極集電体にスラリーを塗工した後、溶媒を揮発させた。以上の工程により、負極を得た。 After applying the slurry to the negative electrode current collector, the solvent was evaporated. Through the above steps, a negative electrode was obtained.
　セパレータとしては、厚さ２５μｍの多孔質ポリプロピレンフィルムを用いた。 A porous polypropylene film with a thickness of 25 μm was used as the separator.
　外装体にはナイロン、アルミニウムおよびポリプロピレンが積層されたアルミラミネートフィルムを用いた。 An aluminum laminate film in which nylon, aluminum, and polypropylene were laminated was used for the exterior body.
　上記材料を用いて作製した二次電池の作製条件を表４に示す。 Table 4 shows the manufacturing conditions for the secondary battery manufactured using the above materials.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　これらの二次電池について初期充放電を行った。初期充放電のことを、エージング又はコンディショニングと呼ぶことがある。 Initial charging and discharging were performed for these secondary batteries. Initial charging and discharging is sometimes called aging or conditioning.
　初期充放電の後、サンプル１またはサンプル２を有するセルの釘刺し試験を行った。釘刺し試験機にはエスペック株式会社製、アドバンストセーフティーテスターを用いた。直径３ｍｍの釘を用いた。釘刺し動作の速度は１ｍｍ／ｓとした。釘刺し量はセルの厚みに＋６ｍｍとした。これ以外の点については、ＳＡＥ　Ｊ２４６４「電気・ハイブリッド自動車の蓄電システムに関する安全性・乱用試験」の記載に従って釘刺し試験を行った。 After initial charging and discharging, a nail penetration test was conducted on the cell containing Sample 1 or Sample 2. The nail penetration tester used was Advanced Safety Tester manufactured by ESPEC Co., Ltd. A nail with a diameter of 3 mm was used. The speed of the nail piercing operation was 1 mm/s. The amount of nail penetration was set to the cell thickness plus 6 mm. Regarding other points, the nail penetration test was conducted in accordance with the description of SAE J2464 "Safety and abuse test for electric/hybrid vehicle power storage system".
　図２４Ａはサンプル１、図２４Ｂはサンプル２を有する二次電池の釘刺し試験の様子を示す写真である。いずれも発火はみられなかった。 FIG. 24A is a photograph showing a nail penetration test of a secondary battery having Sample 1, and FIG. 24B is a photograph showing a state of a nail penetration test of a secondary battery having Sample 2. No ignition was observed in either case.
　図２５Ａは釘刺し試験における、サンプル１またはサンプル２を有する二次電池の電圧変化を示すグラフである。添加元素を有するサンプル１では、釘を刺した直後に電圧が急激に低下し、まもなく３．５Ｖ以上まで戻った後、ゆるやかに再び低下した。一方添加元素を有さないサンプル２では、釘を刺した直後に電圧が急激に低下し、まもなく電圧が戻ったものの２．５Ｖ以上には回復しなかった。 FIG. 25A is a graph showing voltage changes of a secondary battery having Sample 1 or Sample 2 in a nail penetration test. In Sample 1 containing the additive element, the voltage suddenly decreased immediately after the nail was inserted, returned to 3.5 V or higher, and then slowly decreased again. On the other hand, in Sample 2, which did not contain any additive elements, the voltage suddenly decreased immediately after the nail was inserted, and although the voltage returned soon after, it did not recover to 2.5V or higher.
　図２５Ｂは釘刺し試験における、サンプル１またはサンプル２を有する二次電池の温度変化を示すグラフである。添加元素を有するサンプル１を用いた二次電池では温度上昇は１５℃以下であった。一方添加元素を有さないサンプル２を用いた二次電池では温度上昇が３０℃以上であった。 FIG. 25B is a graph showing the temperature change of the secondary battery having Sample 1 or Sample 2 in the nail penetration test. In the secondary battery using Sample 1 containing the additive element, the temperature increase was 15° C. or less. On the other hand, in the secondary battery using Sample 2 without additive elements, the temperature rise was 30° C. or more.
　以上から、添加元素を有するサンプル１を有する二次電池は、添加元素を有さないサンプル２を有する二次電池よりも安全性が向上したことが確認された。 From the above, it was confirmed that the secondary battery having Sample 1 with the additive element had improved safety than the secondary battery having Sample 2 without the additive element.
９８：複合水酸化物、９９：複合酸化物、１００ｍ　添加元素を多く含む層、１００：一次粒子、１０１：正極活物質、１０１ａ　正極活物質、１０１ｂ　正極活物質 98: Composite hydroxide, 99: Composite oxide, 100m layer containing a large amount of additive elements, 100: primary particles, 101: positive electrode active material, 101a positive electrode active material, 101b positive electrode active material

Claims (5)

  1. 　正極を有するリチウムイオン二次電池であって、
    　前記正極は正極活物質を有し、
    　前記正極活物質は、
    　ニッケル、コバルト、マンガン、酸素および添加元素を有し、
    　前記添加元素はフッ素、アルミニウム、マグネシウム、チタンから選ばれる一または二以上であり、
    　前記正極活物質は、前記添加元素を多く含む層と、内部と、を有し、
    　前記添加元素を多く含む層は、前記内部よりも添加元素から選ばれる一以上の検出量が多い、二次電池。     A lithium ion secondary battery having a positive electrode,
    The positive electrode has a positive electrode active material,
    The positive electrode active material is
    Contains nickel, cobalt, manganese, oxygen and additional elements,
    The additive element is one or more selected from fluorine, aluminum, magnesium, and titanium,
    The positive electrode active material has a layer containing a large amount of the additive element and an interior,
    A secondary battery, wherein the layer containing a large amount of the additive element has a higher detected amount of one or more of the additive elements than the inside.
  2. 　請求項１において、
    　前記添加元素はフッ素およびアルミニウムから選ばれる一以上または二であり、
    　前記添加元素を多く含む層および前記内部は、フッ素およびアルミニウムから選ばれる一以上また二を有し、
    　前記添加元素を多く含む層は、前記内部よりもフッ素およびアルミニウムから選ばれる一以上または二の検出量が多い、二次電池。     In claim 1,
    The additive element is one or more or two selected from fluorine and aluminum,
    The layer containing a large amount of additive elements and the interior have one or more or two selected from fluorine and aluminum,
    A secondary battery, wherein the layer containing a large amount of additive elements detects a larger amount of one or more or two selected from fluorine and aluminum than the inside.
  3. 　ニッケルの水溶性塩、コバルトの水溶性塩、及びマンガンの水溶性塩を含む水溶液と、アルカリ溶液と、を反応槽に供給し、前記反応槽の内部で混合して少なくともニッケル、コバルト、マンガン、を含む複合水酸化物を析出させ、
    　前記複合水酸化物と、リチウム化合物と、添加元素源と、を混合した混合物に第１の加熱を行い、解砕または粉砕した後、
    　さらに第２の加熱を行い、解砕または粉砕する、正極活物質の作製方法。     An aqueous solution containing a water-soluble salt of nickel, a water-soluble salt of cobalt, and a water-soluble salt of manganese and an alkaline solution are supplied to a reaction tank, and mixed inside the reaction tank to produce at least nickel, cobalt, manganese, Precipitate a composite hydroxide containing
    After performing first heating on the mixture of the composite hydroxide, the lithium compound, and the additive element source and crushing or pulverizing the mixture,
    A method for producing a positive electrode active material, which further performs second heating to crush or crush.
  4. 　請求項３において、
    　前記添加元素源は、フッ素源、アルミニウム源、マグネシウム源、チタン源、カルシウム源から選ばれる一または二以上である、正極活物質の作製方法。     In claim 3,
    The method for producing a positive electrode active material, wherein the additive element source is one or more selected from a fluorine source, an aluminum source, a magnesium source, a titanium source, and a calcium source.
  5. 　請求項４において、
    　前記ニッケルの水溶性塩、前記コバルトの水溶性塩、及び前記マンガンの水溶性塩が有するニッケル、コバルトおよびマンガンの原子数比は、Ｎｉ：Ｃｏ：Ｍｎ＝６：２：２またはその近傍である、正極活物質の作製方法。     In claim 4,
    The atomic ratio of nickel, cobalt and manganese in the water-soluble nickel salt, the cobalt water-soluble salt, and the manganese water-soluble salt is Ni:Co:Mn=6:2:2 or in the vicinity thereof. , a method for producing a positive electrode active material.
PCT/IB2023/056234 2022-06-29 2023-06-16 Secondary battery and method for producing positive electrode active material WO2024003662A1 (en)

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Citations (4)

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JP2013232438A (en) * 2013-08-05 2013-11-14 Toda Kogyo Corp Lithium composite compound particle powder and production method therefor, nonaqueous electrolyte secondary battery
JP2015530721A (en) * 2013-08-29 2015-10-15 エルジー・ケム・リミテッド Lithium transition metal composite particles, production method thereof, and positive electrode active material including the same
JP2021516434A (en) * 2018-04-04 2021-07-01 エルジー・ケム・リミテッド Method for manufacturing positive electrode active material for lithium secondary battery, positive electrode active material for lithium secondary battery, positive electrode for lithium secondary battery and lithium secondary battery containing this
JP2022501789A (en) * 2018-10-26 2022-01-06 エルジー・ケム・リミテッド Positive electrode active material for secondary batteries, its manufacturing method and lithium secondary batteries containing it

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013232438A (en) * 2013-08-05 2013-11-14 Toda Kogyo Corp Lithium composite compound particle powder and production method therefor, nonaqueous electrolyte secondary battery
JP2015530721A (en) * 2013-08-29 2015-10-15 エルジー・ケム・リミテッド Lithium transition metal composite particles, production method thereof, and positive electrode active material including the same
JP2021516434A (en) * 2018-04-04 2021-07-01 エルジー・ケム・リミテッド Method for manufacturing positive electrode active material for lithium secondary battery, positive electrode active material for lithium secondary battery, positive electrode for lithium secondary battery and lithium secondary battery containing this
JP2022501789A (en) * 2018-10-26 2022-01-06 エルジー・ケム・リミテッド Positive electrode active material for secondary batteries, its manufacturing method and lithium secondary batteries containing it

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