WO2009099156A1 - Method for producing granular powder for positive electrode active material of lithium ion secondary battery - Google Patents

Method for producing granular powder for positive electrode active material of lithium ion secondary battery Download PDF

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WO2009099156A1
WO2009099156A1 PCT/JP2009/051994 JP2009051994W WO2009099156A1 WO 2009099156 A1 WO2009099156 A1 WO 2009099156A1 JP 2009051994 W JP2009051994 W JP 2009051994W WO 2009099156 A1 WO2009099156 A1 WO 2009099156A1
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lithium
granulated powder
slurry
particles
positive electrode
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PCT/JP2009/051994
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French (fr)
Japanese (ja)
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Kenji Yamada
Koji Tatsumi
Yuki Nagura
Kazuya Hiratsuka
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Agc Seimi Chemical Co., Ltd.
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Priority to JP2009552520A priority Critical patent/JPWO2009099156A1/en
Publication of WO2009099156A1 publication Critical patent/WO2009099156A1/en

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    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/006—Compounds containing, besides nickel, two or more other elements, with the exception of oxygen or hydrogen
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G45/00—Compounds of manganese
    • C01G45/12—Manganates manganites or permanganates
    • C01G45/1221—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof
    • C01G45/1228—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof of the type [MnO2]n-, e.g. LiMnO2, Li[MxMn1-x]O2
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G51/00—Compounds of cobalt
    • C01G51/40—Cobaltates
    • C01G51/42—Cobaltates containing alkali metals, e.g. LiCoO2
    • C01G51/44—Cobaltates containing alkali metals, e.g. LiCoO2 containing manganese
    • C01G51/50—Cobaltates containing alkali metals, e.g. LiCoO2 containing manganese of the type [MnO2]n-, e.g. Li(CoxMn1-x)O2, Li(MyCoxMn1-x-y)O2
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
    • C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
    • C01G53/50—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese of the type [MnO2]n-, e.g. Li(NixMn1-x)O2, Li(MyNixMn1-x-y)O2
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/50—Solid solutions
    • C01P2002/52—Solid solutions containing elements as dopants
    • C01P2002/54—Solid solutions containing elements as dopants one element only
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
    • C—CHEMISTRY; METALLURGY
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    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/51—Particles with a specific particle size distribution
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • C—CHEMISTRY; METALLURGY
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    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P2006/40—Electric properties
    • C—CHEMISTRY; METALLURGY
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    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/42—Magnetic properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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

  • the present invention provides a method for producing a granulated powder useful as a raw material for a positive electrode active material of a lithium ion secondary battery having high volume capacity density, filling density and safety, and excellent charge / discharge cycle durability.
  • a lithium-containing composite oxide for a positive electrode active material of a lithium ion secondary battery using the obtained granulated powder as a raw material, and a positive electrode for a lithium ion secondary battery and the lithium ion secondary containing the lithium-containing composite oxide It relates to batteries.
  • non-aqueous electrolyte secondary batteries such as lithium-ion secondary batteries that are small, lightweight, and have high energy density
  • the positive electrode active material for the non-aqueous electrolyte secondary battery include LiCoO 2 , LiNiO 2 , LiNi 0.8 Co 0.2 O 2 , LiMn 2 O 4, LiNi 1/3 Co 1/3 Mn 1/3.
  • a composite oxide of lithium and a transition metal such as O 2 is known.
  • a lithium ion secondary battery using lithium cobalt composite oxide (LiCoO 2 ) as a positive electrode active material and using lithium alloy, graphite, or carbon such as carbon fiber as a negative electrode has a high voltage of 4V. Therefore, it is widely used as a battery having a high energy density.
  • the lithium-containing composite oxide is manufactured by preparing particles of a raw material compound having predetermined physical properties, including nickel, cobalt, manganese, and the like, mixing this with a lithium compound, and firing. . This is because, when a raw material compound having a predetermined average particle size is used, a lithium-containing composite oxide having a particle size suitable as a positive electrode active material can be produced. Further, when the particles and the lithium compound are mixed, This is because the process is easy.
  • an alkaline solution is dropped into a solution in which a compound containing an element such as nickel, cobalt, or manganese is dissolved, and the crystallized crystallized particles are filtered, washed, and dried.
  • a method has been proposed. At this time, it has been proposed to obtain crystallized particles in which several elements are co-precipitated by simultaneously crystallizing several elements (see Patent Documents 1 to 3).
  • a sodium hydroxide aqueous solution is added to a solution in which a compound containing a cobalt atom is dissolved to precipitate cobalt hydroxide particles, followed by filtration, washing, and water.
  • a method of obtaining a crystallized particle of cobalt oxide, then dispersing the crystallized particle of cobalt hydroxide, and spray-drying the resulting slurry to produce a granulated body Patent Document 7). reference). JP 2004047437 A Japanese Patent Laid-Open No. 2005-129489 JP 2007-070205 A JP 2005-123180 A Japanese Patent Laid-Open No. 2005-141983 JP 2005-251717 A JP 2002-060225 A
  • the positive electrode for a lithium ion secondary battery using the lithium-containing composite oxide produced using the above-mentioned raw material compound particles obtained by a conventional production method has a filling density, a volume capacity density, Not all of the characteristics such as heat stability (sometimes referred to as safety in the present invention) and charge / discharge cycle durability were necessarily satisfied.
  • the resulting lithium-containing composite oxide may be short-circuited due to the formation of nickel, cobalt, or manganese metal atoms, and charge / discharge may be hindered due to the presence of impurities, resulting in deterioration of battery characteristics.
  • a lithium-containing composite oxide having excellent properties could not be obtained.
  • the coprecipitation method in which additive elements such as magnesium, aluminum, zirconium and titanium are simultaneously crystallized is known as a useful means for uniformly adding each element.
  • additive elements such as magnesium, aluminum, zirconium and titanium
  • the additive elements tend to be unevenly distributed in the particles.
  • lithium-containing composite oxides are synthesized from co-precipitated particles with a large particle size, it is difficult to make the additive elements uniformly present inside the particles, so charge / discharge cycle durability and safety are high, and sufficient performance is achieved. It was not possible to obtain a lithium-containing composite oxide having
  • a granulated body obtained by spray drying has a sparse and dense portion inside the particle, and a granulated body having many voids inside is obtained.
  • the lithium-containing composite oxide synthesized by using the granulated material as a raw material also has voids, it was impossible to obtain a lithium-containing composite oxide that was dense and had a high volume capacity density.
  • the method of preparing a slurry having a high solid content concentration by adding a dispersant to the slurry in which the raw material compound is dispersed it is necessary to add a large amount of the dispersant. Further, during firing, a gas such as carbon dioxide or water vapor is generated due to decomposition of the dispersant, and voids are formed in the resulting lithium-containing composite oxide particles, so that the volume capacity density tends to be low.
  • the additive element is dispersed in a slurry in which nickel, cobalt, manganese, and the like are dispersed and spray-dried.
  • the viscosity of the slurry becomes very high, and many voids are formed inside the particles. A granulated body having the following is obtained.
  • the spray nozzle may be blocked and spray drying may not be possible. Therefore, a lithium-containing composite oxide that is dense and has a high volume capacity density cannot be obtained.
  • a method for producing a granulated powder for a lithium ion secondary battery positive electrode active material having high volumetric capacity density, filling density and safety, and excellent charge / discharge cycle durability is obtained by the production method.
  • Another object of the present invention is to provide a method for producing a lithium-containing composite oxide, a positive electrode for a lithium ion secondary battery including the lithium-containing composite oxide obtained by the production method, and a lithium ion secondary battery.
  • N element is at least one element selected from the group consisting of Co, Mn and Ni
  • M element is a transition metal element other than N element, Al, Sn, Zn and alkali
  • N element and M element are prepared by mixing an aqueous solution in which at least one element selected from the group consisting of earth metal elements is dissolved and an alkaline aqueous solution and adjusting the pH to a range of 9-14.
  • the manufacturing method of the lithium containing complex oxide for lithium ion secondary battery positive electrode active materials baked at ° C. The lithium-containing composite oxide has a general formula Li p N x M y O z (where N is at least one element selected from the group consisting of Co, Mn, and Ni. M is an N element) Other than transition metal elements, Al, Sn, Zn and at least one element selected from the group consisting of alkaline ion earth metal elements 0.9 ⁇ p ⁇ 1.5, 0.96 ⁇ x ⁇ 2. 00, 0 ⁇ y ⁇ 0.04, 1.9 ⁇ z ⁇ 4.2).
  • a positive electrode for a lithium ion secondary battery comprising a positive electrode active material containing a lithium-containing composite oxide obtained by the production method according to (13) or (14), a conductive material, and a binder.
  • a lithium ion secondary battery comprising a positive electrode, a negative electrode, a nonaqueous electrolyte, and an electrolytic solution, wherein the positive electrode is a positive electrode for a lithium ion secondary battery according to (15).
  • a granulated powder useful as a raw material for a lithium-containing composite oxide for a positive electrode active material of a lithium ion secondary battery having high volumetric capacity density, filling density and safety, and excellent charge / discharge cycle durability A method for producing a lithium-containing composite oxide using the granulated powder obtained by the production method, a positive electrode for a lithium ion secondary battery comprising the lithium-containing composite oxide produced by the production method, and A lithium ion secondary battery is provided.
  • the lithium-containing composite oxide suitable for a positive electrode of a lithium ion secondary battery which is high in volume capacity density, high in safety, and excellent in charge / discharge cycle durability, is not necessarily obtained by the production method of the present invention. Although it is not clear, it is estimated as follows.
  • a coprecipitation slurry containing N element and M element in a uniform state can be obtained by using the coprecipitation method.
  • the coprecipitation slurry is spray-dried after the desalting treatment.
  • impurities such as sulfate ions, chloride ions, nitrate ions and ammonium ions derived from the raw material compound containing N element and the raw material compound containing M element can be efficiently removed from the coprecipitation slurry.
  • the slurry containing these impurities reacts preferentially with the lithium compound in the subsequent firing process with the lithium compound, and the formation reaction of the lithium-containing composite oxide does not proceed uniformly or causes a reduction reaction to cause lithium.
  • Step 2 of the present invention since the slurry in which small particles uniformly containing the element are dispersed is spray-dried, granulated particles containing the element in a very uniform state can be obtained. Therefore, battery characteristics such as safety and charge / discharge cycle durability are improved.
  • the average particle size of the primary particles contained in the slurry obtained by the coprecipitation method is preferably a uniform and small particle of 3 ⁇ m or less, and the slurry is spray-dried and granulated.
  • the average particle diameter (D50) of the secondary particles of the granules preferably a large particle diameter of 10 to 40 ⁇ m, there is no sparse part inside the particles, and each element is present uniformly in the particles.
  • a powder is obtained. When this granulated powder is mixed with a lithium compound and fired, it is believed that it can be uniformly and densely baked without unevenness, and a lithium-containing composite oxide having a high volume capacity density and a high packing density can be obtained. It is.
  • FIG. 4 is an SEM image obtained by photographing a particle cross section of the granulated particles obtained in Example 3.
  • FIG. 4 The SEM image which image
  • FIG. 4 is an SEM image obtained by photographing a particle cross section of the lithium-containing composite oxide obtained in Example 3.
  • FIG. 4 is an SEM image obtained by photographing a particle cross section of the lithium-containing composite oxide obtained in Example 3.
  • the N element is at least one element selected from the group consisting of Co, Mn and Ni.
  • the N element is preferably Co alone, a combination of Ni and Co, a combination of Ni and Mn, or a combination of Co, Ni and Mn, and particularly preferably Co.
  • the Co: Ni: Mn (atomic ratio) is preferably 10 to 80:10 to 80:10 to 80, and more preferably 15 to 70:15 to 70:15. Is more preferably 70, and particularly preferably 20-60: 20-50: 20-60.
  • the M element represents at least one element selected from the group consisting of transition metal elements other than N element, Al, Sn, Zn, and alkaline earth metal elements.
  • the M element is preferably at least one selected from the group consisting of Ti, Zr, Hf, V, Nb, W, Ta, Mo, Sn, Zn, Mg, Ca, Ba, and Al, From the viewpoint of safety and charge / discharge cycle characteristics, at least one selected from the group consisting of Ti, Zr, Hf, Mg and Al is more preferable, and at least one selected from the group consisting of Ti, Zr, Mg and Al is Particularly preferred.
  • the M element is sometimes referred to as an additive element.
  • an aqueous solution in which an N element and an M element are dissolved and an alkaline aqueous solution are mixed, and the pH is adjusted to a range of 9 to 14, thereby uniformly co-precipitating particles containing the N element and the M element.
  • a coprecipitation slurry in which coprecipitate particles containing N element and M element are dispersed is obtained (in the present invention, this step is referred to as step 1).
  • the pH range is more preferably 10-13. Furthermore, it is desirable to adjust the fine range of pH according to the combination of elements to be coprecipitated.
  • the compound serving as the N element source is not particularly limited as long as it is water-soluble, and examples thereof include inorganic salts such as sulfates, chlorides, nitrates, and ammonium salts. More specifically, cobalt sulfate, cobalt chloride, cobalt nitrate, cobalt ammonium sulfate, nickel sulfate, nickel chloride, nickel nitrate, nickel ammonium sulfate, manganese sulfate, manganese chloride, manganese nitrate, manganese ammonium sulfate and the like are exemplified.
  • the compound serving as the M element source is not particularly limited as long as it is water-soluble, and examples thereof include inorganic salts such as sulfates, chlorides, nitrates, and ammonium salts. More specifically, magnesium sulfate, magnesium chloride, magnesium nitrate, aluminum sulfate, aluminum chloride, aluminum nitrate, zirconium sulfate, zirconium chloride, zirconyl nitrate, titanium sulfate, titanium chloride and the like are exemplified.
  • alkaline aqueous solution aqueous solutions of hydroxides such as sodium hydroxide, lithium hydroxide, potassium hydroxide, and ammonium hydroxide are preferable, and aqueous solutions of alkali metal hydroxides are particularly preferable. Of these, an aqueous sodium hydroxide solution or an aqueous lithium hydroxide solution is preferred.
  • the alkaline aqueous solution is preferably introduced so as to co-precipitate the N element and the M element and at the same time keep the pH in the system constant. By coprecipitating the particles while keeping the pH constant, the primary particle size, secondary particle size and other powder physical properties of the coprecipitated particles can be made uniform. Moreover, when coprecipitating each element, an aqueous solution such as an aqueous ammonia solution, ammonium sulfate, or ammonium chloride can be added in order to keep the pH constant and to provide a buffering effect.
  • the coprecipitation slurry obtained in Step 1 is desalted (in the present invention, this step is referred to as Step 2).
  • the coprecipitation slurry contains impurities such as sulfate ion, chloride ion, nitrate ion and ammonium ion derived from the compound containing N element and the compound containing M element used as raw materials. These impurities in the settling slurry are removed.
  • Lithium-containing composite oxides using the resulting granulated product as a raw material by spray drying the coprecipitation slurry containing these impurities are low in safety and charge / discharge cycle durability, thus solving the problems of the present invention. It is not possible. This is because the lithium compound reacts preferentially with these impurities in the subsequent baking with the lithium compound, and the formation reaction of the lithium-containing composite oxide does not proceed uniformly, or the reduction reaction proceeds, and the lithium-containing composite This is probably because a side reaction occurs in which impurities other than oxides are generated.
  • the means for desalting is not particularly limited.
  • a method using an ultrafiltration membrane, a method using a pressure filter, and a belt filter are used. Examples thereof include a method and a method using a filter press. Of these, filter press, belt filter, and ultrafiltration are preferable, and ultrafiltration is particularly preferable.
  • the coprecipitation slurry is supplied to the raw water tank, and then the coprecipitation slurry is circulated through the ultrafiltration apparatus while applying pressure by a pump.
  • pure water is preferably added so as to keep the liquid amount constant while discharging impurity ion-containing water.
  • impurities such as ions in the coprecipitation slurry can be sufficiently removed by circulating the slurry until the conductivity of the discharged ion-containing water is sufficiently lowered.
  • various types such as a hollow fiber type and a flat membrane type, can be used for the ultrafiltration membrane, a general-purpose hollow fiber type is more preferable.
  • the hollow fiber type ultrafiltration membrane include “Microza SIP-1053” (manufactured by Asahi Kasei Corporation).
  • desalting is performed by ultrafiltration, a concentrated desalting slurry can be obtained.
  • a centrifugal separation As a means for desalting, a centrifugal separation, a vacuum drying filter, a filter press or a belt filter can be used.
  • a centrifugal separation filter presses or belt filters are used, if the solid content concentration of the desalted slurry is 30 to 60% by weight, it becomes a wet cake slurry and is easy to handle.
  • the solids concentration can be adjusted by diluting the desalted slurry. Moreover, at the time of this dilution, you may disperse
  • the degree of the desalting treatment to be obtained can be evaluated by the conductivity of discharged ion-containing water.
  • the conductivity of the discharged ion-containing water is preferably 100 ⁇ S / cm or less, more preferably 50 ⁇ S / cm or less, It is especially preferable that it is 15 ⁇ S / cm or less.
  • step 3 the desalted slurry obtained from step 2 is spray-dried to obtain a dry granulated powder containing N element and M element uniformly (in the present invention, this step is referred to as step 3).
  • a spray drying method it is preferable to use a spray dryer.
  • the particle size can be divided by adjusting the operating conditions.
  • the spray dryer it is preferable to use a four-fluid nozzle that can easily make a particle size depending on the amount of air to be sprayed.
  • the average particle diameter of primary particles of coprecipitated particles dispersed in the desalting slurry used for spray drying is preferably 3 ⁇ m or less, more preferably 2 ⁇ m or less, even more preferably 1 ⁇ m or less, and particularly preferably 0.5 ⁇ m or less. preferable. Further, the average particle diameter of primary particles of the coprecipitated particles is preferably 0.005 ⁇ m or more, and more preferably 0.01 ⁇ m or more. In the present invention, the average particle diameter of the primary particles of the coprecipitated particles can be obtained by observation with a scanning electron microscope (sometimes referred to as SEM in the present invention).
  • an ultra-high-resolution field emission scanning electron microscope (sometimes referred to as FE-SEM in the present invention).
  • the surface of the granulated particles is observed with an SEM, or the granulated particles are embedded in a thermosetting resin such as an epoxy resin, polished, and the cross section of the particles is observed with an SEM. It can be obtained by doing.
  • the magnification of SEM can be easily selected depending on the primary particle size, but it is preferable to use an image observed at a magnification of 10,000 to 50,000 times. From the observed image, image analysis software (for example, image analysis software Macview ver3.5 manufactured by Mountec Co., Ltd.) is used to measure 100 to 300 particles, and the equivalent circle diameter is obtained to obtain the particle size of the primary particles. It is done.
  • the solid concentration in the desalting slurry used for spray drying is preferably 10% by weight or more, more preferably 20% by weight or more, still more preferably 30% by weight or more, and particularly preferably 40% by weight or more. Further, the solid content concentration in the desalting slurry is preferably 70% by weight or less, and more preferably 60% by weight or less. When the solid content concentration is within this range, the size of droplets to be sprayed can be easily adjusted, and the particle size of the granulated particles can be easily adjusted. Furthermore, inside the particles, the particles are uniformly distributed without being sparsely or densely biased. Further, it is preferable that the solid content concentration is high because productivity and production efficiency are high, and since water in the slurry is small, energy required for spray drying is also reduced.
  • the solid content concentration is less than 10% by weight, it becomes difficult to increase the particle size, the voids inside the granulated body increase, and the volume capacity density of the lithium-containing composite oxide obtained using the granulated body as a raw material Tends to be low, which is not preferable. Furthermore, the productivity is low and the energy required for spray drying increases, which is not preferable.
  • the solid content concentration is determined as follows. First, a part of the desalted slurry is taken and the weight of the taken slurry is measured, and then the taken slurry is dried at 100 ° C. to measure the weight of the dry powder. The solid content concentration can be determined by dividing the weight of the measured dry powder by the weight of the collected slurry.
  • the viscosity of the desalted slurry used for spray drying is preferably 2 to 1000 mPa ⁇ s, more preferably 2 to 500 mPa ⁇ s, still more preferably 4 to 300 mPa ⁇ s, and particularly preferably 6 to 100 mPa ⁇ s.
  • the viscosity is lower than 2 mPa ⁇ s, the solid content concentration of the desalting slurry is low, or the particle size of the dispersed coprecipitated particles is large, so it becomes impossible to obtain a spherical uniform granulated product, It is not preferable.
  • the viscosity is higher than 1000 mPa ⁇ s, the fluidity of the slurry is poor, and it is not preferable because the solution cannot be transported or transported to the nozzle of the spray dryer or the nozzle is blocked. This is particularly noticeable in a slurry having a high solid content concentration of 60% by weight or more.
  • the viscosity of the desalted slurry is generally measured by a rotary viscometer or a vibration viscometer, but may vary depending on the type of viscometer and measurement conditions.
  • a Brookfield digital rotational viscometer DV-II + LV type is used with a small sample unit and measured under conditions of 25 ° C. and 30 rpm.
  • the viscosity is 100 mPa ⁇ s or less, the spindle no. 18 is used, and in the case of 100 mPa ⁇ s or more, the spindle No. 31 is 1000 mPa ⁇ s or higher, the spindle no. It is preferable to measure using 34.
  • a dispersant can be appropriately added to the slurry in order to increase the solid content concentration and lower the viscosity.
  • the dispersant general dispersants such as polycarboxylic acid type polymer surfactants, ammonium salts of polycarboxylic acid type polymer surfactants, and polyacrylates can be used.
  • gas is generated during firing, voids are formed inside the particles of the obtained lithium-containing composite oxide, and the packing density and volume capacity density may be lowered. Therefore, when adding a dispersant, it is preferable to add an appropriate amount of the dispersant.
  • the average particle size (D50) of the granulated powder obtained by spray drying is preferably 10 to 40 ⁇ m, more preferably 13 to 30 ⁇ m, and even more preferably 15 to 25 ⁇ m.
  • the average particle size is smaller than 10 ⁇ m, the synthesized lithium-containing composite oxide has a small particle size and a low packing density, which is not preferable.
  • the average particle diameter is more than 40 ⁇ m, it becomes difficult to apply the coating to the current collector such as aluminum foil, the coated electrode is scratched, or the positive electrode active material is peeled off from the current collector. It is difficult to make a battery.
  • the average particle size (D50) is a cumulative 50% value of the volume particle size distribution obtained by a laser scattering particle size distribution measuring apparatus (for example, using Microtrack HRAX-100 manufactured by Nikkiso Co., Ltd.). means.
  • the average particle size (D50) may be simply referred to as an average particle size.
  • D10 described later means a cumulative value of 10%
  • D90 means a cumulative value of 90%.
  • the solvent needs to be selected so that the granulated material dissolves into the solvent and does not redisperse.
  • acetone is used as the solvent.
  • the D10 of the granulated powder is preferably 3 to 13 ⁇ m, more preferably 5 to 11 ⁇ m.
  • the granulated powder maintains its shape and becomes a lithium-containing composite oxide having a particle size distribution that is easy to be filled in firing with a lithium compound. This is preferable because a lithium-containing composite oxide is obtained.
  • D10 is smaller than 3 ⁇ m, a plurality of small particles are collected and burnt into a rugged shape, which is not preferable because the packing density of the lithium-containing composite oxide is lowered.
  • D10 exceeds 13 ⁇ m, there is no small particle in the particle size distribution of the lithium-containing composite oxide, which is not preferable because the packing density is lowered.
  • D90 of the granulated powder in the present invention is preferably 70 ⁇ m or less, more preferably 60 ⁇ m or less, and further preferably 50 ⁇ m or less. It is preferable that D90 is 70 ⁇ m or less because the application of the positive electrode active material to the electrode is facilitated.
  • the porosity of the granulated powder obtained in step 3 is preferably 60% or more, more preferably 65% or more, and further preferably 70% or more.
  • the porosity is preferably 90% or less, more preferably 85% or less.
  • the reaction can be biased on the surface and inside during the production of the lithium-containing composite oxide, and the densification of the particles does not progress uniformly,
  • the filling density of the lithium-containing composite oxide is low, and the volume capacity density is low, which is not preferable.
  • the porosity is determined by measuring the pore distribution by injecting mercury at a pressure of 0.1 kPa to 400 MPa by a mercury intrusion method using a mercury porosimeter, and the pore diameter which is half of the cumulative pore volume. Means the numerical value of
  • the upper limit of the average pore diameter of the granulated powder is preferably 1 ⁇ m, more preferably 0.8 ⁇ m, further preferably 0.5 ⁇ m, and particularly preferably 0.3 ⁇ m.
  • the lower limit of the average pore diameter of the granulated powder is preferably 0.01 ⁇ m, more preferably 0.05 ⁇ m, and particularly preferably 0.1 ⁇ m.
  • the average pore diameter means the average value of the distribution obtained by measuring the size of pores formed in the gaps between the particles constituting the granulated powder.
  • the average pore diameter can be measured by a mercury intrusion method using a mercury porosimeter.
  • FIG. 1 it can be seen from FIG. 1 that the primary particles forming the granulated particles are very small particles, and as described above, the porosity of the granulated particles of the present invention is high and the average pore diameter is small. .
  • the granulated powder in the present invention is substantially spherical.
  • the substantially spherical shape does not necessarily need to be a true sphere, and includes those having a high sphericity and those having a substantially spherical shape.
  • the aspect ratio is preferably 1.20 or less, more preferably 1.15 or less, and particularly preferably 1.10 or less.
  • the aspect ratio is preferably 1 or more.
  • the aspect ratio of the granulated powder can be determined by observing a photograph with an SEM. Specifically, the granulated particles are embedded in an epoxy thermosetting resin, the particle cross section is cut and polished, and the cross section of the particles is observed. 100 to 300 granule particle cross sections are measured with a SEM at a magnification of 500 times. At this time, all particles appearing in the image are to be subjected to particle size measurement.
  • the aspect ratio is a value obtained by dividing the longest diameter of each particle by the vertical diameter of the longest diameter, and the average value thereof is the aspect ratio in the present invention. In the examples, measurement was performed using image analysis software Macview ver3.5 manufactured by Mountec. 1 and 2, it can be seen that the granulated particles obtained by the present invention have high sphericity. Further, FIG. 3 shows that the lithium-containing composite oxide obtained using this granulated powder as a raw material has high sphericity.
  • the granulated powder has high fluidity and preferably has an angle of repose of 60 ° or less, more preferably 55 ° or less, and further preferably 50 ° or less.
  • the angle of repose is more than 60 °, the lithium-containing composite oxide tends to have a low packing density and a low volume capacity density.
  • the lower limit of the angle of repose is preferably 30 °, more preferably 40 °.
  • a lithium-containing composite oxide synthesized from a granulated powder having high fluidity is preferable because it has a high packing density and volume capacity density.
  • the granulated powder is preferably a hydroxide, oxyhydroxide, oxide, or sulfate, more preferably a hydroxide or oxyhydroxide, and more preferably a hydroxide. Particularly preferred.
  • the granulated powder uniformly containing the N element and M element obtained in the step 3 is then mixed with the lithium compound powder, and then preferably at 600 to 1100 ° C. in an oxygen-containing atmosphere.
  • the lithium-containing composite oxide can be obtained by firing.
  • the lithium compound powder lithium carbonate, lithium hydroxide, lithium nitrate, or the like can be used. Among them, lithium carbonate that is easy to handle and inexpensive is preferable.
  • the mixture obtained by mixing the granulated powder and the lithium compound is fired at 600 to 1100 ° C., but the lower limit is preferably 700 ° C., more preferably 800 ° C., more preferably 1000 ° C., then 1010 ° C., Preferred in the order of 1030 ° C.
  • the upper limit of the firing temperature is preferably 1070 ° C and more preferably 1050 ° C.
  • the lithium-containing composite oxide for a lithium ion secondary battery positive electrode active material obtained as described above is preferably represented by the formula Li p N x M y O z .
  • p, x, y, and z are as follows. 0.9 ⁇ p ⁇ 1.5, preferably 0.95 ⁇ p ⁇ 1.45, 0.96 ⁇ x ⁇ 2.00, preferably 0.98 ⁇ x ⁇ 1.10, 0 ⁇ y ⁇ 0. 04, preferably 0 ⁇ y ⁇ 0.03, 1.9 ⁇ z ⁇ 4.2, preferably 1.95 ⁇ z ⁇ 2.05.
  • N and M in a formula mean the N element and M element which were used when manufacturing the granulated body of this invention, respectively.
  • the lithium-containing composite oxide of the present invention preferably has a press density of 3.1 g / cm 3 or more, more preferably 3.2 g / cm 3 or more, particularly 3 .3 g / cm or more is preferable.
  • the upper limit is preferably 3.6 g / cm 3 , particularly preferably 3.5 g / cm 3 .
  • the press density in the present invention refers to the apparent press density when 5 g of the particle powder is pressed at a pressure of 0.32 t / cm 2 . From the value of the press density and FIG. 3, it can be seen that the filling property of the lithium-containing composite oxide of the present invention is high.
  • the method of obtaining the positive electrode for lithium ion secondary batteries using the lithium containing complex oxide of this invention can be implemented in accordance with a conventional method.
  • the positive electrode mixture is formed by mixing the positive electrode active material powder of the present invention with a carbon-based conductive material such as acetylene black, graphite, or ketjen black and a binder.
  • a carbon-based conductive material such as acetylene black, graphite, or ketjen black
  • a binder polyvinylidene fluoride, polytetrafluoroethylene, polyamide, carboxymethyl cellulose, acrylic resin, or the like is used.
  • a slurry in which the above positive electrode mixture is dispersed in a dispersion medium such as N-methylpyrrolidone is applied to a positive electrode current collector such as an aluminum foil, dried, and press-rolled to form a positive electrode active material layer on the positive electrode current collector.
  • the solute of the electrolyte solution is ClO 4 ⁇ , CF 3 SO 3 ⁇ , BF 4 ⁇ , PF 6 ⁇ , AsF 6 ⁇ , SbF 6 ⁇ . It is preferable to use any one or more of lithium salts having CF 3 CO 2 ⁇ , (CF 3 SO 2 ) 2 N ⁇ and the like as anions.
  • an electrolyte containing a lithium salt is preferably added to the solvent or solvent-containing polymer at a concentration of 0.2 to 2.0 mol / L.
  • the ionic conductivity is lowered and the electrical conductivity of the electrolyte is lowered. More preferably, 0.5 to 1.5 mol / L is selected.
  • porous polyethylene or porous polypropylene film is used for the separator.
  • a carbonate ester is preferable as the solvent of the electrolyte solution.
  • the carbonate ester can be either cyclic or chain.
  • cyclic carbonates include propylene carbonate and ethylene carbonate (EC).
  • chain carbonate include dimethyl carbonate, diethyl carbonate (DEC), ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate and the like.
  • the carbonate ester may be used alone or in combination of two or more. Moreover, you may mix and use with another solvent.
  • discharge characteristics, cycle durability, and charge / discharge efficiency may be improved.
  • the negative electrode active material of a lithium ion secondary battery using the positive electrode active material of the present invention for the positive electrode is a material that can occlude and release lithium ions.
  • the material for forming the negative electrode active material is not particularly limited. For example, lithium metal, lithium alloy, carbon material, carbon compound, silicon carbide compound, silicon oxide compound, titanium sulfide, boron carbide compound, periodic table 14, and group 15 metal are used. The main oxides are listed.
  • the carbon material those obtained by pyrolyzing organic substances under various pyrolysis conditions, artificial graphite, natural graphite, soil graphite, expanded graphite, scale-like graphite, and the like can be used.
  • the oxide a compound mainly composed of tin oxide can be used.
  • the negative electrode current collector a copper foil, a nickel foil or the like is used.
  • a sheet shape (so-called film shape), a folded shape, a wound-type bottomed cylindrical shape, a button shape, or the like is selected depending on the application.
  • Example 1 (Example) 112.47 g of cobalt sulfate heptahydrate having a cobalt content of 20.96 wt%, 105.23 g of nickel sulfate hexahydrate having a nickel content of 22.31 wt%, and manganese sulfate pentahydrate having a manganese content of 22.71 wt% Cobalt, nickel, manganese and zirconium in which cobalt, nickel, manganese and zirconium were uniformly dissolved by dissolving 5.80 g of zirconium sulfate tetrahydrate having a zirconium content of 19.05% by weight in 96 g of distilled water.
  • a containing aqueous solution was prepared. 1 L of distilled water was put into a 2 L glass reactor, and the above-mentioned aqueous solution containing cobalt, nickel, manganese and zirconium was added at a feed rate of 10 g / min, and 48 weight was maintained so that the pH in the system was maintained at 11.5. % Sodium hydroxide aqueous solution and distilled water were intermittently added to precipitate a hydroxide containing cobalt, nickel, manganese and zirconium, thereby preparing 2.2 kg of a slurry of the hydroxide powder. At this time, the concentration of hydroxide present in the slurry was 5% by weight.
  • the slurry was supplied to the raw water tank of the ultrafiltration device.
  • the slurry is circulated in the ultrafiltration device and the water content is kept constant so that the solid content concentration of the slurry becomes 10% by weight while discharging the ion-containing water.
  • Distilled water was added to maintain. While maintaining this state, the slurry was continuously circulated in the ultrafiltration device until the conductivity of the discharged ion-containing water reached 15 ⁇ S / cm. Desalination was performed by performing a desalting operation to remove impurities such as ions in the slurry. Further, the addition of distilled water was stopped, and the slurry was concentrated to obtain a desalted slurry.
  • the ultrafiltration membrane As the ultrafiltration membrane, “Microza SIP-1053” manufactured by Asahi Kasei Co., Ltd. was used.
  • the desalting slurry had a viscosity of 42 mPa ⁇ s, and the solid concentration measured by separating the slurry and drying at 100 ° C. was 15% by weight.
  • a spray dryer 500 g of the desalted slurry was dried while granulating to obtain a granulated powder composed of hydroxides containing cobalt, nickel, manganese and zirconium elements.
  • a spray dryer “GB22” manufactured by Yamato Scientific Co., Ltd. was used. The operating conditions were a slurry supply rate of 10 g / min, a spray gas pressure of 0.15 MPa, and a gas temperature of 180 ° C.
  • the granulated powder When the granulated powder was observed by SEM, it was found that primary particles of 0.02 to 0.75 ⁇ m aggregated to form substantially spherical secondary particles. Moreover, the average particle diameter of the primary particles of the coprecipitated particles measured by using image analysis software Macview ver3.5 manufactured by Mountec was 0.25 ⁇ m. The average particle size of the secondary particles was 16.0 ⁇ m, D10 was 5.5 ⁇ m, and D90 was 36.5 ⁇ m. The granulated powder has a porosity of 83%, an average pore diameter of 0.13 ⁇ m, an aspect ratio of 1.07, an angle of repose of 55 °, and a total content of nickel, cobalt, manganese and zirconium of 60. It was 8% by weight.
  • the obtained lithium-containing composite oxide powder was observed with an SEM, it was found that primary particles of 0.5 to 3 ⁇ m aggregated to form substantially spherical secondary particles.
  • the average particle size of the lithium-containing composite oxide particles was 12.5 ⁇ m, D10 was 5.5 ⁇ m, and D90 was 25.2 ⁇ m.
  • the specific surface area was 0.61 m 2 / g.
  • the lithium-containing composite oxide powder, acetylene black, and polyvinylidene fluoride powder were mixed at a weight ratio of 90/5/5, and N-methylpyrrolidone was added to prepare a slurry, with a thickness of 20 ⁇ m.
  • the aluminum foil was coated on one side using a doctor blade. Subsequently, it dried and the positive electrode sheet
  • a punched sheet of the positive electrode body is used as the positive electrode
  • a metal lithium foil having a thickness of 500 ⁇ m is used as the negative electrode
  • a nickel foil of 20 ⁇ m is used as the negative electrode current collector
  • a porous material having a thickness of 25 ⁇ m is used as the separator.
  • Polypropylene is used, and the electrolyte solution is a LiPF 6 / EC + DEC (1: 1) solution having a concentration of 1 M (meaning a mixed solution of EC and DEC in a weight ratio (1: 1) containing LiPF 6 as a solute).
  • Two similar stainless-cell closed cell type lithium batteries were assembled in an argon glove box using the same solvent.
  • the one battery is charged to 4.3 V at a load current of 30 mA per 1 g of the positive electrode active material at 25 ° C., and discharged to 2.5 V at a load current of 30 mA per 1 g of the positive electrode active material. Asked. Moreover, about this battery, the charging / discharging cycle test was performed 30 times continuously. As a result, the initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 152 mAh / g, and the capacity retention rate after 30 charge / discharge cycles was 95.1%.
  • the volume capacity density which can be calculated by multiplying the press density and the initial weight capacity density, was 444 mAh / cm 3 .
  • the positive electrode sheet after charging was taken out, the positive electrode sheet was washed, punched to a diameter of 3 mm, and aluminum together with EC. It sealed in the capsule made from a product, and heated at a rate of 5 ° C./min with a scanning differential calorimeter to measure the heat generation start temperature. As a result, the heat generation start temperature of the heat generation curve was 231 ° C.
  • Example 2 (Example) 337.41 g of cobalt sulfate heptahydrate having a cobalt content of 20.96 wt%, 0.21 g of aluminum sulfate having an aluminum content of 15.6 wt%, 0.29 g of magnesium sulfate heptahydrate having a magnesium content of 10.1 wt%, An aqueous solution containing cobalt, aluminum, magnesium and zirconium in which 0.29 g of zirconium sulfate tetrahydrate having a zirconium content of 19.05% by weight was dissolved in 500 g of distilled water and cobalt, aluminum, magnesium and zirconium were uniformly dissolved. Prepared.
  • the slurry was supplied to the raw water tank of the ultrafiltration apparatus, and ultrafiltration was performed in the same manner as in Example 1 until the conductivity of the discharged ion-containing water reached 15 ⁇ S / cm. Further, the addition of distilled water was stopped and the slurry was concentrated to obtain a desalted slurry.
  • the desalted slurry had a viscosity of 57 mPa ⁇ s and a solid content concentration of 13% by weight.
  • Example 2 The same operation as in Example 1 was performed to obtain a granulated powder composed of cobalt, aluminum, magnesium and zirconium.
  • the granulated powder was observed by SEM, it was found that primary particles of 0.02 to 0.75 ⁇ m aggregated to form substantially spherical secondary particles.
  • the average particle diameter of the primary particles of the coprecipitated particles was 0.22 ⁇ m.
  • the average particle size was 22.5 ⁇ m, D10 was 9.4 ⁇ m, and D90 was 41.1 ⁇ m.
  • the granulated powder has a porosity of 81%, an average pore diameter of 0.17 ⁇ m, an aspect ratio of 1.07, an angle of repose of 48 °, and a total content of cobalt, aluminum, magnesium and zirconium of 62. It was 0% by weight.
  • the obtained lithium-containing composite oxide powder had an average particle size of 15.6 ⁇ m, D10 of 7.4 ⁇ m, and D90 of 27.4 ⁇ m.
  • the specific surface area was 0.41 m 2 / g.
  • the initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 161 mAh / g, and the volume capacity density was 530 mAh / cm 3 .
  • the capacity retention rate after 30 charge / discharge cycles was 98.8%.
  • the heat generation start temperature of the heat generation curve was 162 ° C.
  • Example 3 (Example) 337.41 g of cobalt sulfate heptahydrate with a cobalt content of 20.96 wt%, 2.12 g of aluminum sulfate with an aluminum content of 15.6 wt%, 2.95 g of magnesium sulfate heptahydrate with a magnesium content of 10.1 wt%, An aqueous solution containing cobalt, aluminum, magnesium and zirconium in which 0.29 g of zirconium sulfate tetrahydrate having a zirconium content of 19.05% by weight was dissolved in 500 g of distilled water and cobalt, aluminum, magnesium and zirconium were uniformly dissolved. Prepared.
  • the slurry was supplied to the raw water tank of the ultrafiltration apparatus, and ultrafiltration was performed in the same manner as in Example 1 until the conductivity of the discharged ion-containing water reached 15 ⁇ S / cm. Further, the addition of distilled water was stopped and the slurry was concentrated to obtain a desalted slurry.
  • the desalted slurry had a viscosity of 130 mPa ⁇ s and a solid content concentration of 40% by weight.
  • Example 2 The same operation as in Example 1 was performed to obtain a granulated powder composed of cobalt, aluminum, magnesium and zirconium.
  • An SEM image obtained by photographing the particle cross section of this granulated body is shown in FIG. 1, and an SEM image obtained by photographing the granulated particle powder is shown in FIG. 1 and 2, it can be seen that the granulated particles obtained by the present invention have high sphericity.
  • the granulated powder was observed by SEM, it was found that primary particles of 0.02 to 0.75 ⁇ m aggregated to form substantially spherical secondary particles.
  • the average particle diameter of primary particles of the coprecipitated particles was 0.38 ⁇ m.
  • the average particle diameter of the secondary particles was 22.5 ⁇ m, D10 was 10.9 ⁇ m, and D90 was 53.6 ⁇ m.
  • the granulated powder has a porosity of 78%, an average pore diameter of 0.27 ⁇ m, an aspect ratio of 1.10, an angle of repose of 51 °, and a total content of cobalt, aluminum, magnesium and zirconium of 61. It was 2% by weight.
  • 30 g of the granulated powder was mixed with 12.1 g of lithium carbonate having a lithium content of 18.7% by weight, and the obtained lithium mixed powder was fired at 1030 ° C. for 15 hours in an oxygen-containing atmosphere. Thereafter, the mixture was pulverized to obtain a substantially spherical lithium-containing composite oxide powder having a composition of Li 1.0099 Co 0.9698 Al 0.0099 Mg 0.0099 Zr 0.0005 O 2 .
  • the obtained lithium-containing composite oxide powder had an average particle size of 17.4 ⁇ m, D10 of 7.7 ⁇ m, and D90 of 35.3 ⁇ m.
  • the specific surface area was 0.39 m 2 / g.
  • the initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 155 mAh / g, and the volume capacity density was 521 mAh / cm 3 .
  • the capacity retention rate after 30 charge / discharge cycles was 95.4%. Further, the heat generation start temperature of the heat generation curve was 164 ° C.
  • Example 4 (Example) 67.25 g of cobalt sulfate heptahydrate with a cobalt content of 20.96% by weight, 188.79 g of nickel sulfate hexahydrate with a nickel content of 22.31% by weight, manganese sulfate pentahydrate with a manganese content of 22.71% by weight Cobalt, nickel, manganese and zirconium in which cobalt, nickel, manganese and zirconium are uniformly dissolved by dissolving 5.78 g of zirconium sulfate tetrahydrate having a zirconium content of 19.05% by weight in 500 g of distilled water. A containing aqueous solution was prepared.
  • Example 2 Except that the concentration of hydroxide present in the slurry was 5% by weight, the same operation as in Example 1 was performed, and a granulated powder was obtained through a desalting slurry.
  • the viscosity of the desalted slurry obtained along the way was 40 mPa ⁇ s, and the solid content concentration was 35% by weight.
  • the obtained granulated powder was observed with an SEM, it was found that primary particles of 0.05 to 1.0 ⁇ m aggregated to form substantially spherical secondary particles.
  • the average particle diameter of the primary particles of the coprecipitated particles was 0.52 ⁇ m.
  • the average particle diameter of the secondary particles was 15.2 ⁇ m, D10 was 5.3 ⁇ m, and D90 was 32.5 ⁇ m.
  • the granulated powder has a porosity of 78%, an average pore diameter of 0.14 ⁇ m, an aspect ratio of 1.13 and an angle of repose of 58 °, and the total content of nickel, cobalt, manganese and zirconium is 60. It was 4% by weight.
  • the granulated powder was mixed with 8.07 g of lithium carbonate having a lithium content of 18.7% by weight, and the obtained mixture powder was fired at 900 ° C. for 16 hours in an oxygen-containing atmosphere. Thereafter, the mixture was pulverized to obtain a substantially spherical lithium-containing composite oxide powder having a composition of Li 1.024 Ni 0.580 Co 0.193 Mn 0.193 Zr 0.01 O 2 .
  • the obtained lithium-containing composite oxide powder was evaluated in the same manner as in Example 1.
  • the half value width of the diffraction peak of (110) plane was 0.178 °, and the press density was 2.95 g / cm 3 .
  • the obtained lithium-containing composite oxide powder was observed with an SEM, it was found that primary particles of 0.5 to 3 ⁇ m aggregated to form substantially spherical secondary particles.
  • the average particle size was 12.6 ⁇ m
  • D10 was 5.9 ⁇ m
  • D90 was 24.9 ⁇ m.
  • the specific surface area is 0.59 m 2 / g
  • the initial weight capacity density of the positive electrode is 160 mAh / g
  • the capacity retention ratio is 95.8%
  • the volume capacity density is 472 mAh / cm 3
  • heat generation starts.
  • Example 5 (Example) 312.1 g of cobalt sulfate heptahydrate with a cobalt content of 20.96 wt%, 0.20 g of aluminum sulfate with an aluminum content of 15.6 wt%, 0.29 g of magnesium sulfate heptahydrate with a magnesium content of 10.1 wt%, An aqueous solution containing cobalt, aluminum, magnesium and titanium in which 0.47 g of titanium sulfate aqueous solution having a titanium content of 6.0% by weight was dissolved in 500 g of distilled water and cobalt, aluminum, magnesium and titanium were uniformly dissolved was prepared.
  • the slurry was supplied to the raw water tank of the ultrafiltration apparatus, and ultrafiltration was performed in the same manner as in Example 1 until the conductivity of the discharged ion-containing water reached 15 ⁇ S / cm. Further, the addition of steamed water was stopped and the slurry was concentrated to obtain a desalted slurry.
  • the desalted slurry had a viscosity of 110 mPa ⁇ s and a solid content concentration of 35% by weight.
  • Example 2 The same operation as in Example 1 was performed to obtain a granulated powder composed of cobalt, aluminum, magnesium and titanium.
  • the granulated powder was observed by SEM, it was found that primary particles of 0.02 to 0.75 ⁇ m aggregated to form substantially spherical secondary particles.
  • the average particle size of the primary particles of the coprecipitated particles was 0.29 ⁇ m.
  • the average particle diameter of the secondary particles was 20.6 ⁇ m, D10 was 8.2 ⁇ m, and D90 was 36.7 ⁇ m.
  • the granulated powder has a porosity of 80%, an average pore diameter of 0.14 ⁇ m, an aspect ratio of 1.09, an angle of repose of 54 °, and a total content of cobalt, aluminum, magnesium and titanium of 60.
  • the obtained lithium-containing composite oxide powder had an average particle size of 16.2 ⁇ m, D10 of 7.9 ⁇ m, and D90 of 26.2 ⁇ m.
  • the specific surface area was 0.40 m 2 / g.
  • the initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 160 mAh / g, and the volume capacity density was 528 mAh / cm 3 .
  • the capacity retention rate after 30 charge / discharge cycles was 97.5%.
  • the heat generation start temperature of the heat generation curve was 160 ° C.
  • Example 6 (Comparative example) 337.41 g of cobalt sulfate heptahydrate with a cobalt content of 20.96 wt%, 2.12 g of aluminum sulfate with an aluminum content of 15.6 wt%, 2.95 g of magnesium sulfate heptahydrate with a magnesium content of 10.1 wt%, An aqueous solution containing cobalt, aluminum, magnesium and zirconium in which 0.29 g of zirconium sulfate tetrahydrate having a zirconium content of 19.05% by weight was dissolved in 500 g of distilled water and cobalt, aluminum, magnesium and zirconium were uniformly dissolved. Prepared.
  • distilled water 1 L was put into a 2 L glass reactor, and the aqueous solution was added at a feed rate of 0.5 g / min, and a 48 wt% aqueous sodium hydroxide solution was maintained so that the pH in the system was maintained at 9.5. And distilled water were intermittently added to precipitate a hydroxide containing cobalt, aluminum, magnesium and zirconium, thereby preparing 2.2 kg of a hydroxide powder slurry. At this time, the concentration of hydroxide present in the slurry was 5% by weight.
  • the filtered cake is repeatedly dispersed in pure water again, and the same operation is repeated until the filtrate has a conductivity of 15 ⁇ S / cm, followed by desalting. did.
  • the desalted cake was dried at 120 ° C. to obtain a coprecipitated cobalt hydroxide powder doped with aluminum, magnesium and zirconium.
  • the average particle diameter of the obtained coprecipitated cobalt hydroxide powder was 18.6 ⁇ m, D10 was 14.3 ⁇ m, and D90 was 25.0 ⁇ m.
  • the coprecipitated cobalt hydroxide powder has a porosity of 53%, an average pore diameter of 2.5 ⁇ m, an aspect ratio of 1.23, an angle of repose of 50 °, and a total content of cobalt, aluminum, magnesium and zirconium of 62. .4% by weight. Further, 30 g of this coprecipitated cobalt hydroxide powder was mixed with 12.0 g of lithium carbonate having a lithium content of 18.7% by weight, and the resultant mixture powder was fired at 1030 ° C. for 15 hours in an oxygen-containing atmosphere. Then, to obtain a lithium-containing composite oxide powder having a composition of LiCo 0.9975 Al 0.001 Mg 0.001 Zr 0.0005 O 2 was pulverized.
  • an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation).
  • RINT 2100 type manufactured by Rigaku Corporation
  • the press density was 2.88 g / cm 3 .
  • the average particle size was 18.6 ⁇ m, D10 was 14.3 ⁇ m, and D90 was 25.0 ⁇ m.
  • the specific surface area was 0.47 m 2 / g.
  • the initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 148 mAh / g, and the volume capacity density was 452 mAh / cm 3 .
  • the capacity retention rate after 30 charge / discharge cycles was 99.5%.
  • the heat generation start temperature of the heat generation curve was 157 ° C.
  • Example 7 (Comparative Example) A cobalt-containing aqueous solution was prepared by dissolving 328.0 g of cobalt sulfate heptahydrate having a cobalt content of 20.96 wt% in 500 g of distilled water. 1 L of distilled water was placed in a 2 L glass reactor, and the above cobalt-containing aqueous solution was added at a feed rate of 0.15 g / min, and 48 wt% hydroxylation was maintained so that the pH in the system was maintained at 9.5. Sodium aqueous solution and distilled water were intermittently added to precipitate cobalt hydroxide, thereby preparing 2.2 kg of cobalt hydroxide powder slurry. At this time, the concentration of hydroxide present in the slurry was 5% by weight.
  • the slurry was then filtered and washed to obtain cobalt hydroxide.
  • This cobalt hydroxide was dispersed again in the slurry to prepare a slurry.
  • This re-dispersed slurry was spray-dried using a disk rotary dryer to obtain a cobalt hydroxide granule.
  • the cobalt hydroxide granulated powder was observed with an SEM, it was found that primary particles of 0.02 to 0.75 ⁇ m aggregated to form substantially spherical secondary particles.
  • the average particle diameter of the primary particles of the coprecipitated particles was 0.32 ⁇ m.
  • the average particle diameter of the secondary particles was 24.5 ⁇ m, D10 was 8.5 ⁇ m, and D90 was 48.4 ⁇ m.
  • the granulated powder had a porosity of 78%, an average pore diameter of 0.14 ⁇ m, an aspect ratio of 1.10, an angle of repose of 55 °, and a cobalt content of 62.5% by weight. Further, 30 g of the granulated powder was mixed with 11.8 g of lithium carbonate having a lithium content of 18.7% by weight, and the obtained lithium mixed powder was fired at 900 ° C. for 15 hours in an oxygen-containing atmosphere. Then, to obtain a lithium-containing composite oxide powder having a composition of LiCoO 2 was pulverized.
  • the obtained lithium-containing composite oxide powder was observed with an SEM, it was found that primary particles of 0.5 to 2 ⁇ m aggregated to form substantially spherical secondary particles.
  • the average particle size was 17.9 ⁇ m
  • D10 was 5.8 ⁇ m
  • D90 was 37.5 ⁇ m.
  • the specific surface area was 0.85 m 2 / g.
  • the initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 162 mAh / g, and the volume capacity density was 446 mAh / cm 3 .
  • the capacity retention rate after 30 charge / discharge cycles was 87.5%.
  • the heat generation start temperature of the heat generation curve was 154 ° C.
  • Example 8 (Comparative example) 30 g of the cobalt hydroxide granulate prepared in Example 7 and 11.8 g of lithium carbonate having a lithium content of 18.7 wt% were mixed, and the resulting lithium mixed powder was fired at 1030 ° C. for 15 hours in an oxygen-containing atmosphere. . Then, to obtain a lithium-containing composite oxide powder having a composition of LiCoO 2 was pulverized. With respect to the obtained powder of lithium-containing composite oxide, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation).
  • the obtained lithium-containing composite oxide powder had an average particle size of 15.8 ⁇ m, D10 of 7.0 ⁇ m, and D90 of 29.5 ⁇ m.
  • the specific surface area was 0.38 m 2 / g.
  • the initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 160 mAh / g, and the volume capacity density was 493 mAh / cm 3 .
  • the capacity retention rate after 30 charge / discharge cycles was 89.0%.
  • the heat generation start temperature of the heat generation curve was 156 ° C.
  • Example 9 (Comparative Example) 103.48 g of cobalt hydroxide having a cobalt content of 62.3% by weight, 0.87 g of aluminum hydroxide having an aluminum content of 34.55% by weight, 0.65 g of magnesium hydroxide having a magnesium content of 41.64% by weight, Were mixed, and water was added and stirred to obtain 300 g of a slurry. Subsequently, each raw material particle dispersed in the slurry was wet-pulverized using a circulating medium agitation type wet bead mill until the average particle diameter became 0.3 ⁇ m, thereby obtaining a pulverized slurry. The pulverized slurry had a viscosity of 780 mPa ⁇ s and a solid content concentration of 35% by weight.
  • Example 2 The same operation as in Example 1 was performed to obtain a granulated powder composed of cobalt hydroxide.
  • the average particle diameter of the primary particles of the coprecipitated particles was 0.52 ⁇ m.
  • the average particle diameter of the secondary particles was 15.3 ⁇ m, D10 was 5.4 ⁇ m, and D90 was 32.5 ⁇ m.
  • the granulated powder has a porosity of 68%, an average pore diameter of 0.17 ⁇ m, an aspect ratio of 1.22, an angle of repose of 62 °, and a total content of cobalt, aluminum and magnesium of 60.4 wt. %Met.
  • the average particle size was 13.3 ⁇ m, D10 was 5.3 ⁇ m, and D90 was 28.5 ⁇ m. Further, when the zirconium content of this lithium-containing composite oxide powder was measured, it was confirmed that 150 ppm of zirconium was mixed as an impurity. This is probably because zirconium contained in the bead mill as a medium was mixed as an impurity.
  • the specific surface area was 0.54 m 2 / g.
  • the initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 158 mAh / g, and the volume capacity density was 483 mAh / cm 3 .
  • the capacity retention rate after 30 charge / discharge cycles was 95.2%.
  • the heat generation start temperature of the heat generation curve was 158 ° C.
  • Example 10 (Comparative Example) 40.30 g of cobalt hydroxide having a cobalt content of 62.3 wt%, 31.97 g of nickel oxide (NiO) having a nickel content of 78.2 wt%, manganese oxide having a manganese content of 71.5 wt% (Mn 3 Water was mixed with 32.73 g of O 4 ) and stirred to obtain a 300 g slurry. Subsequently, each raw material particle dispersed in the slurry was wet-pulverized using a circulating medium agitation type wet bead mill until the average particle diameter became 0.3 ⁇ m, thereby obtaining a pulverized slurry.
  • NiO nickel oxide
  • Mn 3 Water manganese oxide having a manganese content of 71.5 wt%
  • the viscosity of this pulverized slurry was 900 mPa ⁇ s, and the solid content concentration measured by separating the slurry and drying it at 100 ° C. was 35% by weight.
  • This pulverized slurry was subjected to the same operation as in Example 1 to obtain a granulated body containing cobalt, nickel and manganese.
  • the obtained granulated powder was observed with an SEM, it was found that secondary particles in which primary particles of 0.02 to 3 ⁇ m were aggregated were formed.
  • the average particle diameter of the primary particles of the coprecipitated particles was 0.59 ⁇ m.
  • the average particle diameter of the secondary particles was 15.5 ⁇ m, D10 was 5.1 ⁇ m, and D90 was 45.5 ⁇ m.
  • the granulated powder has a porosity of 73%, an average pore diameter of 0.21 ⁇ m, an aspect ratio of 1.22, an angle of repose of 63 °, and a total content of nickel, cobalt and manganese of 60.4 wt. %was.
  • the obtained lithium-containing composite oxide powder was evaluated in the same manner as in Example 1.
  • the (110) plane had a diffraction peak half width of 0.195 ° and a press density of 2.70 g / cm 3 .
  • the obtained lithium-containing composite oxide powder was observed with an SEM, it was found that primary particles of 0.5 to 3 ⁇ m aggregated to form substantially spherical secondary particles.
  • the average particle size was 14.3 ⁇ m
  • D10 was 5.3 ⁇ m
  • D90 was 30.3 ⁇ m.
  • the zirconium content of this lithium-containing composite oxide powder was measured, it was confirmed that 200 ppm of zirconium was mixed as an impurity.
  • the specific surface area is 0.66 m 2 / g
  • the initial weight capacity density of the positive electrode is 151 mAh / g
  • the capacity retention is 94.5%
  • the volume capacity density is 408 mAh / cm 3 .
  • the heat generation starting temperature was 225 ° C.
  • a method for producing a granulated powder useful as a raw material for a lithium ion secondary battery positive electrode active material having high volumetric capacity density, filling density and safety, and excellent charge / discharge cycle durability there can be provided a method for producing a lithium-containing composite oxide obtained by the production method, a positive electrode for a lithium ion secondary battery and a lithium ion secondary battery comprising the lithium-containing composite oxide obtained by the production method.

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Abstract

Disclosed is a highly safe positive electrode active material for lithium ion secondary batteries, which has high volumetric capacity and packing density, while exhibiting excellent charge/discharge cycle durability. A method for producing a granular powder which is useful as a raw material for the positive electrode active material is also disclosed. The method for producing a granular powder is characterized in that granules having a substantially spherical shape are obtained by having particles coprecipitated from an aqueous solution, in which an element N (which is at least one element selected from the group consisting of Co, Mn and Ni) and an element M (which is at least one element selected from the group consisting of transition metal elements other than the element N, Al, Sn, Zn and alkaline earth metal elements) are dissolved, then desalting and spray-drying the coprecipitated particles.

Description

リチウムイオン二次電池正極活物質用の造粒体粉末の製造方法Method for producing granulated powder for positive electrode active material of lithium ion secondary battery
　本発明は体積容量密度、充填密度及び安全性が高く、充放電サイクル耐久性に優れたリチウムイオン二次電池正極活物質用の原料として有用な造粒体粉末の製造方法、該製造方法で得られる造粒体粉末を原料に用いたリチウムイオン二次電池正極活物質用のリチウム含有複合酸化物の製造方法、及び該リチウム含有複合酸化物を含むリチウムイオン二次電池用正極及びリチウムイオン二次電池に関する。 The present invention provides a method for producing a granulated powder useful as a raw material for a positive electrode active material of a lithium ion secondary battery having high volume capacity density, filling density and safety, and excellent charge / discharge cycle durability. For producing a lithium-containing composite oxide for a positive electrode active material of a lithium ion secondary battery using the obtained granulated powder as a raw material, and a positive electrode for a lithium ion secondary battery and the lithium ion secondary containing the lithium-containing composite oxide It relates to batteries.
　近年、パソコン、携帯電話等の情報関連機器や通信機器の急速な発達が進むにつれて、小型、軽量でかつ高エネルギー密度を有するリチウムイオン二次電池等の非水電解液二次電池に対する要求が高まっている。かかる非水電解液二次電池用の正極活物質には、ＬｉＣｏＯ２、ＬｉＮｉＯ２、ＬｉＮｉ０．８Ｃｏ０．２Ｏ２、ＬｉＭｎ２Ｏ４、ＬｉＮｉ１／３Ｃｏ１／３Ｍｎ１／３Ｏ２などのリチウムと遷移金属の複合酸化物（本発明において、リチウム含有複合酸化物ということがある）が知られている。 In recent years, with the rapid development of information-related equipment and communication equipment such as personal computers and mobile phones, the demand for non-aqueous electrolyte secondary batteries such as lithium-ion secondary batteries that are small, lightweight, and have high energy density has increased. ing. Examples of the positive electrode active material for the non-aqueous electrolyte secondary battery include LiCoO 2 , LiNiO 2 , LiNi 0.8 Co 0.2 O 2 , LiMn 2 O 4, LiNi 1/3 Co 1/3 Mn 1/3. A composite oxide of lithium and a transition metal such as O 2 (in the present invention, sometimes referred to as a lithium-containing composite oxide) is known.
　なかでも、リチウムコバルト複合酸化物（ＬｉＣｏＯ２）を正極活物質として用い、リチウム合金、又はグラファイトも若しくはカーボンファイバー等のカーボンを負極として用いたリチウムイオン二次電池は、４Ｖ級の高い電圧が得られるため、高エネルギー密度を有する電池として広く使用されている。 Among them, a lithium ion secondary battery using lithium cobalt composite oxide (LiCoO 2 ) as a positive electrode active material and using lithium alloy, graphite, or carbon such as carbon fiber as a negative electrode has a high voltage of 4V. Therefore, it is widely used as a battery having a high energy density.
　上記のリチウム含有複合酸化物は、所定の物性を有する、ニッケル、コバルト及びマンガンなどを含む原料化合物の粒子を予め調製して、これをリチウム化合物と混合して、焼成することにより製造されている。これは、所定の平均粒子径を有する原料化合物を用いると、正極活物質として適した粒径であるリチウム含有複合酸化物を作製することができるためであり、さらに該粒子とリチウム化合物を混合すると、工程として容易であるためである。 The lithium-containing composite oxide is manufactured by preparing particles of a raw material compound having predetermined physical properties, including nickel, cobalt, manganese, and the like, mixing this with a lithium compound, and firing. . This is because, when a raw material compound having a predetermined average particle size is used, a lithium-containing composite oxide having a particle size suitable as a positive electrode active material can be produced. Further, when the particles and the lithium compound are mixed, This is because the process is easy.
　上記の原料化合物の粒子の製造方法として、ニッケル、コバルト、マンガンなどの元素を含む化合物が溶解した溶液に、アルカリ溶液を滴下して、晶析させた晶析粒子を、ろ過、洗浄、乾燥させる方法が提案されている。また、この際に数種の元素を同時に晶析させることで、数種の元素を共沈させた晶析粒子を得ることが提案されている（特許文献１～３参照）。 As a method for producing the raw material compound particles, an alkaline solution is dropped into a solution in which a compound containing an element such as nickel, cobalt, or manganese is dissolved, and the crystallized crystallized particles are filtered, washed, and dried. A method has been proposed. At this time, it has been proposed to obtain crystallized particles in which several elements are co-precipitated by simultaneously crystallizing several elements (see Patent Documents 1 to 3).
　また、上記の原料化合物の他の製造方法としては、ニッケル、コバルト及びマンガンなどの元素を含む化合物を分散させたスラリーを湿式粉砕した後、スプレードライヤーなどで噴霧乾燥して、造粒体を作製する方法が提案されている（特許文献４～６参照）。 In addition, as another production method of the above raw material compound, a slurry in which a compound containing elements such as nickel, cobalt and manganese is dispersed is wet-pulverized and then spray-dried with a spray dryer or the like to produce a granulated body. Have been proposed (see Patent Documents 4 to 6).
　さらに、上記の原料化合物の他の製造方法として、コバルト原子を含む化合物が溶解した溶液に、水酸化ナトリウム水溶液を添加して、水酸化コバルト粒子を析出させた後、ろ過、洗浄して、水酸化コバルトの晶析粒子を得て、次いでこの水酸化コバルトの晶析粒子を分散させて、得られるスラリーを、噴霧乾燥して、造粒体を作製する方法が提案されている（特許文献７参照）。
特開２００４－０４７４３７号公報 特開２００５－１２９４８９号公報 特開２００７－０７０２０５号公報 特開２００５－１２３１８０号公報 特開２００５－１４１９８３号公報 特開２００５－２５１７１７号公報 特開２００２－０６０２２５号公報 Furthermore, as another method for producing the above raw material compound, a sodium hydroxide aqueous solution is added to a solution in which a compound containing a cobalt atom is dissolved to precipitate cobalt hydroxide particles, followed by filtration, washing, and water. There has been proposed a method of obtaining a crystallized particle of cobalt oxide, then dispersing the crystallized particle of cobalt hydroxide, and spray-drying the resulting slurry to produce a granulated body (Patent Document 7). reference).
JP 2004047437 A Japanese Patent Laid-Open No. 2005-129489 JP 2007-070205 A JP 2005-123180 A Japanese Patent Laid-Open No. 2005-141983 JP 2005-251717 A JP 2002-060225 A
　しかしながら、従来の製造方法で得られる上記の原料化合物の粒子を使用して製造されるリチウム含有複合酸化物を用いたリチウムイオン二次電池用正極は、充填密度、体積容量密度、過熱した際の熱に対する安定性（本発明において、安全性ということがある）、充放電サイクル耐久性などの各特性の全てを必ずしも満足するものではなかった。 However, the positive electrode for a lithium ion secondary battery using the lithium-containing composite oxide produced using the above-mentioned raw material compound particles obtained by a conventional production method has a filling density, a volume capacity density, Not all of the characteristics such as heat stability (sometimes referred to as safety in the present invention) and charge / discharge cycle durability were necessarily satisfied.
　例えば、特許文献１～３に記載の方法では、粒径が大きい晶析粒子を作製するのに、粒子を成長させる必要があるため、長い時間が必要である。また長い時間をかけて粒子を成長させると、粒子形状がいびつになり球状の晶析粒子を得ることが非常に難しい。さらに、粒径が大きい晶析粒子を作製する場合、粒子を成長させた際に、硫酸イオン、塩化物イオン、炭酸イオンなどの不純物が粒子内部に取り込まれ、洗浄しても完全に除去できないため、不純物が粒子内部に残存する。このような不純物を含む晶析粒子を原料に用いて、リチウム含有複合酸化物を製造すると、組成を厳密に制御することが困難になる。また、得られるリチウム含有複合酸化物にニッケル、コバルト又はマンガンの金属原子の生成によりショートしたり、不純物の存在により充放電が妨害され電池特性の悪化したりするため、安全性及び充放電サイクル耐久性に優れるリチウム含有複合酸化物を得ることはできなかった。 For example, in the methods described in Patent Documents 1 to 3, a long time is required because it is necessary to grow the particles in order to produce crystallized particles having a large particle size. Further, when the particles are grown over a long time, the particle shape becomes distorted and it is very difficult to obtain spherical crystallized particles. Furthermore, when preparing crystallized particles with a large particle size, impurities such as sulfate ions, chloride ions, and carbonate ions are incorporated into the particles when they are grown and cannot be completely removed by washing. Impurities remain inside the particles. When a lithium-containing composite oxide is produced using crystallization particles containing such impurities as raw materials, it becomes difficult to strictly control the composition. In addition, the resulting lithium-containing composite oxide may be short-circuited due to the formation of nickel, cobalt, or manganese metal atoms, and charge / discharge may be hindered due to the presence of impurities, resulting in deterioration of battery characteristics. A lithium-containing composite oxide having excellent properties could not be obtained.
　また、マグネシウム、アルミニウム、ジルコニウム、チタニウムなどの添加元素を同時に晶析させる共沈法は、各元素を均一に添加する方法として有用な手段として知られている。しかし、特に結晶を成長させて、粒径が大きい共沈粒子を作製する場合、粒子内部に添加元素が不均一に偏って分布する傾向が見られるようになる。その結果、粒径の大きな共沈粒子からリチウム含有複合酸化物を合成すると、粒子内部に添加元素を均一に存在させることが難しくなるため、充放電サイクル耐久性や安全性が高く、十分な性能を有するリチウム含有複合酸化物を得ることはできなかった。 Further, the coprecipitation method in which additive elements such as magnesium, aluminum, zirconium and titanium are simultaneously crystallized is known as a useful means for uniformly adding each element. However, particularly when coprecipitated particles having a large particle size are produced by growing crystals, the additive elements tend to be unevenly distributed in the particles. As a result, when lithium-containing composite oxides are synthesized from co-precipitated particles with a large particle size, it is difficult to make the additive elements uniformly present inside the particles, so charge / discharge cycle durability and safety are high, and sufficient performance is achieved. It was not possible to obtain a lithium-containing composite oxide having
　特許文献４～６に記載の方法では、噴霧乾燥して得られる造粒体は、粒子内部に疎や密な部分ができ、内部に多くの空隙を有する造粒体が得られる。また、該造粒体を原料に用いて、合成したリチウム含有複合酸化物も空隙が残るため、緻密で、体積容量密度が高い、リチウム含有複合酸化物を得ることはできなかった。 In the methods described in Patent Documents 4 to 6, a granulated body obtained by spray drying has a sparse and dense portion inside the particle, and a granulated body having many voids inside is obtained. Moreover, since the lithium-containing composite oxide synthesized by using the granulated material as a raw material also has voids, it was impossible to obtain a lithium-containing composite oxide that was dense and had a high volume capacity density.
　また、原料化合物を分散させたスラリーに分散剤を含有させることで、固形分濃度が高いスラリーを作製する方法では、多量の分散剤を加える必要がある。また焼成の際に、分散剤の分解により二酸化炭素や水蒸気などの気体が発生して、得られるリチウム含有複合酸化物の粒子中に空隙ができるため、体積容量密度が低くなる傾向が見られる。 Further, in the method of preparing a slurry having a high solid content concentration by adding a dispersant to the slurry in which the raw material compound is dispersed, it is necessary to add a large amount of the dispersant. Further, during firing, a gas such as carbon dioxide or water vapor is generated due to decomposition of the dispersant, and voids are formed in the resulting lithium-containing composite oxide particles, so that the volume capacity density tends to be low.
　さらに、ビーズミルなどを用いて、スラリー中の原料化合物を湿式粉砕する工程を含む場合、分散メディア由来の不純物が混入して、かつスラリーの粘度が高くなる。不純物の混入により、放電容量や充放電サイクル耐久性が悪化する。また粘度の高いスラリーを噴霧乾燥するため、粒子内部に多くの空隙を有する造粒体が得られる。さらに該造粒体を原料に用いて、合成したリチウム含有複合酸化物も空隙が残るため、緻密で、体積容量密度が高いリチウム含有複合酸化物を得ることはできなかった。 Furthermore, when a process of wet-grinding the raw material compound in the slurry using a bead mill or the like is included, impurities derived from the dispersion medium are mixed and the viscosity of the slurry is increased. Due to the mixing of impurities, discharge capacity and charge / discharge cycle durability deteriorate. Moreover, since the slurry with high viscosity is spray-dried, a granulated body having many voids inside the particles can be obtained. Further, since the lithium-containing composite oxide synthesized using the granulated material as a raw material also has voids, it was impossible to obtain a lithium-containing composite oxide that was dense and had a high volume capacity density.
　また、ニッケル、コバルト及びマンガンなどを分散させたスラリーに、添加元素を分散させ、噴霧乾燥することが示唆されているが、この場合、スラリーの粘度が非常に高くなり、粒子内部に多くの空隙を有する造粒体が得られる。また、粘度が高すぎるため、スプレーノズルが閉塞し、噴霧乾燥できない場合がある。そのため、緻密で、体積容量密度が高いリチウム含有複合酸化物を得ることはできなかった。 In addition, it has been suggested that the additive element is dispersed in a slurry in which nickel, cobalt, manganese, and the like are dispersed and spray-dried. In this case, however, the viscosity of the slurry becomes very high, and many voids are formed inside the particles. A granulated body having the following is obtained. Moreover, since the viscosity is too high, the spray nozzle may be blocked and spray drying may not be possible. Therefore, a lithium-containing composite oxide that is dense and has a high volume capacity density cannot be obtained.
　特許文献７に記載の方法では、水酸化コバルトを原料として、リチウム含有複合酸化物を合成しているが、添加元素を含まないため、安全性及び充放電サイクル耐久性が劣るため、十分な電池性能を有するリチウム含有複合酸化物を得ることはできなかった。また、特許文献７に記載の方法を参考にしたとしても、各元素を均一に共沈させる条件や共沈粒子が分散するスラリーの取り扱いが非常に複雑であり、単純に各元素を共沈させるだけでは、ニッケル、コバルト、マンガン及び添加元素を均一に存在させた造粒体を得ることはできなかった。また原料に由来する不純物の除去が不十分であるという問題もあった。すなわち、緻密で、充填容量密度が高く、充放電サイクル耐久性や安全性といった電池特性に優れたリチウム含有複合酸化物を得ることはできなかった。 In the method described in Patent Document 7, a lithium-containing composite oxide is synthesized using cobalt hydroxide as a raw material. However, since it does not contain an additive element, safety and charge / discharge cycle durability are inferior. A lithium-containing composite oxide having performance could not be obtained. Even if the method described in Patent Document 7 is referred to, the conditions for uniformly coprecipitation of each element and the handling of the slurry in which the coprecipitated particles are dispersed are very complicated, and each element is simply coprecipitated. It was not possible to obtain a granulated body in which nickel, cobalt, manganese and additive elements were uniformly present. There is also a problem that impurities derived from the raw material are not sufficiently removed. That is, it was impossible to obtain a lithium-containing composite oxide that was dense, had a high filling capacity density, and had excellent battery characteristics such as charge / discharge cycle durability and safety.
　そこで、本発明では、体積容量密度、充填密度及び安全性が高く、充放電サイクル耐久性に優れたリチウムイオン二次電池正極活物質用の造粒体粉末の製造方法、該製造方法によって得られたリチウム含有複合酸化物の製造方法、該製造方法によって得られたリチウム含有複合酸化物を含むリチウムイオン二次電池用正極、及びリチウムイオン二次電池の提供を目的とする。 Therefore, in the present invention, a method for producing a granulated powder for a lithium ion secondary battery positive electrode active material having high volumetric capacity density, filling density and safety, and excellent charge / discharge cycle durability, is obtained by the production method. Another object of the present invention is to provide a method for producing a lithium-containing composite oxide, a positive electrode for a lithium ion secondary battery including the lithium-containing composite oxide obtained by the production method, and a lithium ion secondary battery.
　本発明者らは、鋭意研究を続けたところ、上記目的を達成する本発明に到達した。本発明は以下の構成を要旨とするものである。
（１）Ｎ元素（Ｎは、Ｃｏ、Ｍｎ及びＮｉからなる群から選ばれる少なくとも１種の元素である）及びＭ元素（Ｍは、Ｎ元素以外の遷移金属元素、Ａｌ、Ｓｎ、Ｚｎ及びアルカリ土類金属元素からなる群から選ばれる少なくとも１種の元素である）が少なくとも溶解した水溶液とアルカリ水溶液とを混合して、ｐＨを９～１４の範囲に調節することにより、Ｎ元素及びＭ元素を含む共沈粒子を析出させ、該共沈粒子が分散する共沈スラリーを得る工程１と；前記共沈スラリーを脱塩処理せしめて脱塩スラリーを得る工程２と；前記脱塩スラリーを噴霧乾燥してＮ元素及びＭ元素を含有する実質上球状の造粒体粉末を得る工程３とを、この順番で含むことを特徴とするリチウムイオン二次電池正極活物質用の造粒体粉末の製造方法。
（２）工程１で得られる共沈スラリー中に分散する共沈粒子の一次粒子の平均粒子径が０．０１～３μｍである上記（１）に記載の造粒体粉末の製造方法。
（３）共沈スラリーの固形分濃度が１０重量％のときに、工程２の脱塩処理で排出されるイオン含有水の伝導度が１００μＳ／ｃｍ以下である上記（１）に記載の造粒体粉末の製造方法。
（４）工程３で噴霧乾燥に用いる脱塩スラリーの固形分濃度が１０重量％以上であり、脱塩スラリーの粘度が２～１０００ｍＰａ・ｓである上記（１）～（３）のいずれかに記載の造粒体粉末の製造方法。
（５）工程３で得られる造粒体粉末の平均粒子径（Ｄ５０）が１０～４０μｍである上記（１）～（４）のいずれかに記載の造粒体粉末の製造方法。
（６）工程３で得られる造粒体粉末の気孔率が６０％以上である上記（１）～（５）のいずれかに記載の造粒体粉末の製造方法。
（７）工程３で得られる造粒体粉末の平均細孔径が１μｍ以下である上記（１）～（６）のいずれかに記載の造粒体粉末の製造方法。
（８）工程３で得られる造粒体粉末のアスペクト比が１．２以下である上記（１）～（７）のいずれかに記載の造粒体粉末の製造方法。
（９）工程３で得られる造粒体粉末の安息角が６０°以下である上記（１）～（８）のいずれかに記載の造粒体粉末の製造方法。
（１０）工程３で得られる造粒体粉末のＤ１０が３～１２μｍである上記（１）～（９）のいずれかに記載の造粒体粉末の製造方法。
（１１）工程３で得られる造粒体粉末のＤ９０が７０μｍ以下である上記（１）～（１０）のいずれかに記載の造粒体粉末の製造方法。
（１２）Ｎ元素がＣｏである上記（１）～（１１）のいずれかに記載の造粒体粉末の製造方法。
（１３）上記（１）～（１２）のいずれかに記載の造粒体粉末の製造方法で得られた造粒体粉末と、リチウム化合物粉末とを混合した後、酸素含有雰囲気において６００～１１００℃で焼成するリチウムイオン二次電池正極活物質用のリチウム含有複合酸化物の製造方法。
（１４）リチウム含有複合酸化物が、一般式ＬｉｐＮｘＭｙＯｚ（但し、Ｎは、Ｃｏ、Ｍｎ及びＮｉからなる群から選ばれる少なくとも１種の元素である。Ｍは、Ｎ元素以外の遷移金属元素、Ａｌ、Ｓｎ、Ｚｎ及びアルカリイオン土類金属元素からなる群から選ばれる少なくとも１種の元素である。０．９≦ｐ≦１．５、０．９６≦ｘ＜２．００、０＜ｙ≦０．０４、１．９≦ｚ≦４．２）で表される上記（１３）に記載のリチウム含有複合酸化物の製造方法。
（１５）上記（１３）又は（１４）に記載の製造方法により得られるリチウム含有複合酸化物を含む正極活物質と導電材とバインダーとを含むリチウムイオン二次電池用正極。
（１６）正極、負極、非水電解質及び電解液を含み、かつ該正極が上記（１５）に記載のリチウムイオン二次電池用正極であるリチウムイオン二次電池。 As a result of intensive studies, the present inventors have arrived at the present invention that achieves the above object. The gist of the present invention is as follows.
(1) N element (N is at least one element selected from the group consisting of Co, Mn and Ni) and M element (M is a transition metal element other than N element, Al, Sn, Zn and alkali) N element and M element are prepared by mixing an aqueous solution in which at least one element selected from the group consisting of earth metal elements is dissolved and an alkaline aqueous solution and adjusting the pH to a range of 9-14. A coprecipitation slurry in which the coprecipitation particles are dispersed to obtain a coprecipitation slurry; and a desalination slurry obtained by subjecting the coprecipitation slurry to a desalination treatment; and spraying the desalination slurry. Step 3 of drying to obtain a substantially spherical granulated powder containing N element and M element in this order, and a granulated powder for a positive electrode active material for a lithium ion secondary battery, Production method.
(2) The method for producing a granulated powder according to the above (1), wherein the primary particles of the coprecipitated particles dispersed in the coprecipitation slurry obtained in step 1 have an average particle diameter of 0.01 to 3 μm.
(3) The granulation according to (1), wherein the conductivity of the ion-containing water discharged by the desalting treatment in step 2 is 100 μS / cm or less when the solid content concentration of the coprecipitation slurry is 10% by weight. A method for producing body powder.
(4) Any of the above (1) to (3), wherein the desalting slurry used for spray drying in step 3 has a solid content concentration of 10% by weight or more and the desalting slurry has a viscosity of 2 to 1000 mPa · s. The manufacturing method of the granulated powder of description.
(5) The method for producing a granulated powder according to any one of (1) to (4), wherein the granulated powder obtained in step 3 has an average particle diameter (D50) of 10 to 40 μm.
(6) The method for producing a granulated powder according to any one of the above (1) to (5), wherein the porosity of the granulated powder obtained in step 3 is 60% or more.
(7) The method for producing a granulated powder according to any one of the above (1) to (6), wherein the granulated powder obtained in step 3 has an average pore diameter of 1 μm or less.
(8) The method for producing a granulated powder according to any one of the above (1) to (7), wherein the granulated powder obtained in step 3 has an aspect ratio of 1.2 or less.
(9) The method for producing a granulated powder according to any one of the above (1) to (8), wherein the angle of repose of the granulated powder obtained in step 3 is 60 ° or less.
(10) The method for producing a granulated powder according to any one of (1) to (9), wherein D10 of the granulated powder obtained in step 3 is 3 to 12 μm.
(11) The method for producing a granulated powder according to any one of the above (1) to (10), wherein D90 of the granulated powder obtained in Step 3 is 70 μm or less.
(12) The method for producing a granulated powder according to any one of (1) to (11), wherein the N element is Co.
(13) The granulated powder obtained by the method for producing a granulated powder according to any one of (1) to (12) above and a lithium compound powder are mixed and then mixed in an oxygen-containing atmosphere at 600 to 1100. The manufacturing method of the lithium containing complex oxide for lithium ion secondary battery positive electrode active materials baked at ° C.
(14) The lithium-containing composite oxide has a general formula Li p N x M y O z (where N is at least one element selected from the group consisting of Co, Mn, and Ni. M is an N element) Other than transition metal elements, Al, Sn, Zn and at least one element selected from the group consisting of alkaline ion earth metal elements 0.9 ≦ p ≦ 1.5, 0.96 ≦ x <2. 00, 0 <y ≦ 0.04, 1.9 ≦ z ≦ 4.2). The method for producing a lithium-containing composite oxide according to the above (13).
(15) A positive electrode for a lithium ion secondary battery comprising a positive electrode active material containing a lithium-containing composite oxide obtained by the production method according to (13) or (14), a conductive material, and a binder.
(16) A lithium ion secondary battery comprising a positive electrode, a negative electrode, a nonaqueous electrolyte, and an electrolytic solution, wherein the positive electrode is a positive electrode for a lithium ion secondary battery according to (15).
　本発明によれば、体積容量密度、充填密度及び安全性が高く、充放電サイクル耐久性に優れたリチウムイオン二次電池正極活物質用のリチウム含有複合酸化物の原料として有用な造粒体粉末の製造方法、該製造方法によって得られた造粒体粉末を用いたリチウム含有複合酸化物の製造方法、該製造方法により製造されたリチウム含有複合酸化物を含むリチウムイオン二次電池用正極、及びリチウムイオン二次電池が提供される。 According to the present invention, a granulated powder useful as a raw material for a lithium-containing composite oxide for a positive electrode active material of a lithium ion secondary battery having high volumetric capacity density, filling density and safety, and excellent charge / discharge cycle durability. A method for producing a lithium-containing composite oxide using the granulated powder obtained by the production method, a positive electrode for a lithium ion secondary battery comprising the lithium-containing composite oxide produced by the production method, and A lithium ion secondary battery is provided.
　本発明の製造方法により、何故に体積容量密度が高く、安全性が高く、充放電サイクル耐久性に優れた、リチウムイオン二次電池正極に適したリチウム含有複合酸化物が得られるのかは、必ずしも明確ではないが、ほぼ以下のように推定される。 The reason why the lithium-containing composite oxide suitable for a positive electrode of a lithium ion secondary battery, which is high in volume capacity density, high in safety, and excellent in charge / discharge cycle durability, is not necessarily obtained by the production method of the present invention. Although it is not clear, it is estimated as follows.
　すなわち、本発明の製造方法によると、共沈法を用いることにより、Ｎ元素とＭ元素とを均一な状態で含む共沈スラリーが得られるが、該共沈スラリーは脱塩処理後に噴霧乾燥することにより、Ｎ元素を含む原料化合物及びＭ元素を含む原料化合物に由来する硫酸イオン、塩化物イオン、硝酸イオン、アンモニウムイオンなどの不純物を共沈スラリーから効率良く除去できる。これらの不純物が含有するスラリーは、後に行われるリチウム化合物との焼成過程において、リチウム化合物と優先的に反応し、リチウム含有複合酸化物の生成反応が均一に進行しない、又は還元反応を起こしてリチウム含有複合酸化物以外の物質が生成する副反応が起こるため、得られるリチウム含有複合酸化物は、安全性及び充放電サイクル耐久性が低くなる。また、本発明の工程２では、元素を均一に含有する小さな粒子が分散したスラリーを噴霧乾燥するため、非常に均一な状態で元素を含む造粒体粒子が得られる。そのため、安全性及び充放電サイクル耐久性といった電池特性が向上する。 That is, according to the production method of the present invention, a coprecipitation slurry containing N element and M element in a uniform state can be obtained by using the coprecipitation method. The coprecipitation slurry is spray-dried after the desalting treatment. Thus, impurities such as sulfate ions, chloride ions, nitrate ions and ammonium ions derived from the raw material compound containing N element and the raw material compound containing M element can be efficiently removed from the coprecipitation slurry. The slurry containing these impurities reacts preferentially with the lithium compound in the subsequent firing process with the lithium compound, and the formation reaction of the lithium-containing composite oxide does not proceed uniformly or causes a reduction reaction to cause lithium. Since a side reaction in which a substance other than the contained composite oxide is generated occurs, the obtained lithium-containing composite oxide has low safety and charge / discharge cycle durability. In Step 2 of the present invention, since the slurry in which small particles uniformly containing the element are dispersed is spray-dried, granulated particles containing the element in a very uniform state can be obtained. Therefore, battery characteristics such as safety and charge / discharge cycle durability are improved.
　また、本発明では、共沈法により得られるスラリー中に含まれる一次粒子の平均粒子径は好ましくは３μｍ以下という均一で小さな粒子であり、該スラリーを噴霧乾燥して造粒し、また、造粒体の二次粒子の平均粒子径（Ｄ５０）を好ましくは１０～４０μｍという大きな粒子径にすることにより、粒子内部に疎な部分がなく、粒子内部に均一に各元素が存在する造粒体粉末が得られる。この造粒体粉末をリチウム化合物と混合し、焼成した場合、偏りなく均一に、かつ緻密に焼きしまり、高い体積容量密度、高い充填密度を有するリチウム含有複合酸化物を得ることができるものと思われる。 In the present invention, the average particle size of the primary particles contained in the slurry obtained by the coprecipitation method is preferably a uniform and small particle of 3 μm or less, and the slurry is spray-dried and granulated. By making the average particle diameter (D50) of the secondary particles of the granules preferably a large particle diameter of 10 to 40 μm, there is no sparse part inside the particles, and each element is present uniformly in the particles. A powder is obtained. When this granulated powder is mixed with a lithium compound and fired, it is believed that it can be uniformly and densely baked without unevenness, and a lithium-containing composite oxide having a high volume capacity density and a high packing density can be obtained. It is.
例３で得られた造粒体粒子の粒子断面を撮影したＳＥＭ像。4 is an SEM image obtained by photographing a particle cross section of the granulated particles obtained in Example 3. FIG. 例３で得られた造粒体粉末を撮影したＳＥＭ像。The SEM image which image | photographed the granulated body powder obtained in Example 3. FIG. 例３で得られたリチウム含有複合酸化物の粒子断面を撮影したＳＥＭ像。4 is an SEM image obtained by photographing a particle cross section of the lithium-containing composite oxide obtained in Example 3. FIG.
　本発明において、Ｎ元素は、Ｃｏ、Ｍｎ及びＮｉからなる群から選ばれる少なくとも１種の元素である。なかでも、Ｎ元素は、Ｃｏ単独、Ｎｉ及びＣｏの組み合わせ、Ｎｉ及びＭｎの組み合わせ、又はＣｏ、Ｎｉ及びＭｎの組み合わせが好ましく、Ｃｏが特に好ましい。Ｎ元素が、Ｃｏ、Ｎｉ及びＭｎの組み合わせである場合、Ｃｏ：Ｎｉ：Ｍｎ（原子比）は１０～８０：１０～８０：１０～８０が好ましく、なかでも１５～７０：１５～７０：１５～７０であるとより好ましく、特に２０～６０：２０～５０：２０～６０が好ましい。 In the present invention, the N element is at least one element selected from the group consisting of Co, Mn and Ni. Among these, the N element is preferably Co alone, a combination of Ni and Co, a combination of Ni and Mn, or a combination of Co, Ni and Mn, and particularly preferably Co. When the N element is a combination of Co, Ni and Mn, the Co: Ni: Mn (atomic ratio) is preferably 10 to 80:10 to 80:10 to 80, and more preferably 15 to 70:15 to 70:15. Is more preferably 70, and particularly preferably 20-60: 20-50: 20-60.
　また、Ｍ元素は、Ｎ元素以外の遷移金属元素、Ａｌ、Ｓｎ、Ｚｎ及びアルカリ土類金属元素からなる群から選ばれる少なくとも１種類の元素を表す。なかでも、Ｍ元素は、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｗ、Ｔａ、Ｍｏ、Ｓｎ、Ｚｎ、Ｍｇ、Ｃａ、Ｂａ及びＡｌからなる群から選ばれる少なくとも１種が好ましく、容量発現性、安全性、充放電サイクル特性などの見地よりＴｉ、Ｚｒ、Ｈｆ、Ｍｇ及びＡｌからなる群から選ばれる少なくとも１種がより好ましく、Ｔｉ、Ｚｒ、Ｍｇ及びＡｌからなる群から選ばれる少なくとも１種が特に好ましい。なお、本発明において、Ｍ元素を添加元素ということがある。 The M element represents at least one element selected from the group consisting of transition metal elements other than N element, Al, Sn, Zn, and alkaline earth metal elements. Among them, the M element is preferably at least one selected from the group consisting of Ti, Zr, Hf, V, Nb, W, Ta, Mo, Sn, Zn, Mg, Ca, Ba, and Al, From the viewpoint of safety and charge / discharge cycle characteristics, at least one selected from the group consisting of Ti, Zr, Hf, Mg and Al is more preferable, and at least one selected from the group consisting of Ti, Zr, Mg and Al is Particularly preferred. In the present invention, the M element is sometimes referred to as an additive element.
　本発明においては、まず、Ｎ元素及びＭ元素が溶解した水溶液とアルカリ水溶液とを混合して、ｐＨを９～１４の範囲に調節することで、Ｎ元素及びＭ元素を均一に含む共沈粒子を析出でき、Ｎ元素及びＭ元素を含む共沈粒子が分散する共沈スラリーが得られる（本発明において、この工程を工程１という）。上記したｐＨの範囲は、１０～１３がより好ましい。さらにｐＨの細かい範囲については、共沈させる元素の組み合わせに合わせて、調節することが望ましい。 In the present invention, first, an aqueous solution in which an N element and an M element are dissolved and an alkaline aqueous solution are mixed, and the pH is adjusted to a range of 9 to 14, thereby uniformly co-precipitating particles containing the N element and the M element. And a coprecipitation slurry in which coprecipitate particles containing N element and M element are dispersed is obtained (in the present invention, this step is referred to as step 1). The pH range is more preferably 10-13. Furthermore, it is desirable to adjust the fine range of pH according to the combination of elements to be coprecipitated.
　Ｎ元素源となる化合物としては、水溶性であれば特に限定されないが、硫酸塩、塩化物、硝酸塩、アンモニウム塩などの無機塩が例示される。より具体的には、硫酸コバルト、塩化コバルト、硝酸コバルト、硫酸コバルトアンモニウム、硫酸ニッケル、塩化ニッケル、硝酸ニッケル、硫酸ニッケルアンモニウム、硫酸マンガン、塩化マンガン、硝酸マンガン、硫酸マンガンアンモニウムなどが例示される。Ｍ元素源となる化合物としては、水溶性であれば特に限定されないが、硫酸塩、塩化物、硝酸塩、アンモニウム塩などの無機塩が例示される。より具体的には、硫酸マグネシウム、塩化マグネシウム、硝酸マグネシウム、硫酸アルミニウム、塩化アルミニウム、硝酸アルミニウム、硫酸ジルコニウム、塩化ジルコニウム、硝酸ジルコニル、硫酸チタン、塩化チタンなどが例示される。 The compound serving as the N element source is not particularly limited as long as it is water-soluble, and examples thereof include inorganic salts such as sulfates, chlorides, nitrates, and ammonium salts. More specifically, cobalt sulfate, cobalt chloride, cobalt nitrate, cobalt ammonium sulfate, nickel sulfate, nickel chloride, nickel nitrate, nickel ammonium sulfate, manganese sulfate, manganese chloride, manganese nitrate, manganese ammonium sulfate and the like are exemplified. The compound serving as the M element source is not particularly limited as long as it is water-soluble, and examples thereof include inorganic salts such as sulfates, chlorides, nitrates, and ammonium salts. More specifically, magnesium sulfate, magnesium chloride, magnesium nitrate, aluminum sulfate, aluminum chloride, aluminum nitrate, zirconium sulfate, zirconium chloride, zirconyl nitrate, titanium sulfate, titanium chloride and the like are exemplified.
　アルカリ水溶液としては、水酸化ナトリウム、水酸化リチウム、水酸化カリウム、水酸化アンモニウムなどの水酸化物の水溶液が好ましく、特にアルカリ金属の水酸化物の水溶液が特に好ましい。なかでも水酸化ナトリウム水溶液、又は水酸化リチウム水溶液が好ましい。アルカリ水溶液は、Ｎ元素及びＭ元素を共沈させると同時に、系中のｐＨを一定に保つように導入するのが好ましい。ｐＨを一定に保ちながら、粒子を共沈させることで、共沈粒子の一次粒子径、二次粒子径やその他の粉体物性を、均一に揃えることができる。また各元素を共沈させる際に、ｐＨを一定に保ち、緩衝効果を加えるために、アンモニア水溶液、硫酸アンモニウム又は塩化アンモニウムなどの水溶液を添加することもできる。 As the alkaline aqueous solution, aqueous solutions of hydroxides such as sodium hydroxide, lithium hydroxide, potassium hydroxide, and ammonium hydroxide are preferable, and aqueous solutions of alkali metal hydroxides are particularly preferable. Of these, an aqueous sodium hydroxide solution or an aqueous lithium hydroxide solution is preferred. The alkaline aqueous solution is preferably introduced so as to co-precipitate the N element and the M element and at the same time keep the pH in the system constant. By coprecipitating the particles while keeping the pH constant, the primary particle size, secondary particle size and other powder physical properties of the coprecipitated particles can be made uniform. Moreover, when coprecipitating each element, an aqueous solution such as an aqueous ammonia solution, ammonium sulfate, or ammonium chloride can be added in order to keep the pH constant and to provide a buffering effect.
　次いで、本発明では、工程１で得られた共沈スラリーを脱塩処理する（本発明において、この工程を工程２という）。共沈スラリーには、原料に用いたＮ元素を含む化合物及びＭ元素を含む化合物由来の硫酸イオン、塩化物イオン、硝酸イオン、アンモニウムイオンなどの不純物が含有されるが、脱塩処理により、共沈スラリー中のこれらの不純物が除去せしめられる。 Next, in the present invention, the coprecipitation slurry obtained in Step 1 is desalted (in the present invention, this step is referred to as Step 2). The coprecipitation slurry contains impurities such as sulfate ion, chloride ion, nitrate ion and ammonium ion derived from the compound containing N element and the compound containing M element used as raw materials. These impurities in the settling slurry are removed.
　これらの不純物が含有する共沈スラリーを噴霧乾燥して、得られる造粒体を原料に用いたリチウム含有複合酸化物は、安全性、及び充放電サイクル耐久性が低く、本発明の課題を解決できるものではない。これは、後に行われる、リチウム化合物との焼成において、リチウム化合物がこれらの不純物と優先的に反応し、リチウム含有複合酸化物の生成反応が均一に進行しない、又は還元反応が進み、リチウム含有複合酸化物以外の不純物が生成する副反応が起こるためと考えられる。 Lithium-containing composite oxides using the resulting granulated product as a raw material by spray drying the coprecipitation slurry containing these impurities are low in safety and charge / discharge cycle durability, thus solving the problems of the present invention. It is not possible. This is because the lithium compound reacts preferentially with these impurities in the subsequent baking with the lithium compound, and the formation reaction of the lithium-containing composite oxide does not proceed uniformly, or the reduction reaction proceeds, and the lithium-containing composite This is probably because a side reaction occurs in which impurities other than oxides are generated.
　本発明で、共沈スラリー中の上記不純物が除去できる限り、脱塩処理の手段は特に限定されず、限外ろ過膜を使用する方法、加圧ろ過機を使用する方法、ベルトフィルターを使用する方法、フィルタープレスを使用する方法などの手段が挙げられる。なかでも、フィルタープレス、ベルトフィルター、限外ろ過が好ましく、特に限外ろ過が好ましい。限外ろ過の場合、共沈スラリーを原水タンクに供給し、次に、ポンプで圧力をかけながら、限外ろ過装置を通じて共沈スラリーを循環させる。限外ろ過装置では、不純物イオン含有水を排出させつつ、好ましくは液量を一定に維持するように純水を添加する。 In the present invention, as long as the impurities in the coprecipitation slurry can be removed, the means for desalting is not particularly limited. A method using an ultrafiltration membrane, a method using a pressure filter, and a belt filter are used. Examples thereof include a method and a method using a filter press. Of these, filter press, belt filter, and ultrafiltration are preferable, and ultrafiltration is particularly preferable. In the case of ultrafiltration, the coprecipitation slurry is supplied to the raw water tank, and then the coprecipitation slurry is circulated through the ultrafiltration apparatus while applying pressure by a pump. In the ultrafiltration device, pure water is preferably added so as to keep the liquid amount constant while discharging impurity ion-containing water.
　限外ろ過は、排出されるイオン含有水の伝導度が十分に下がるまで、スラリーを循環させることによって、共沈スラリー中のイオンなどの不純物を十分に除去することができる。限外ろ過膜は、中空糸タイプ、平膜タイプなどの種々のタイプが使用できるが、汎用的な中空糸タイプがより好ましい。中空糸タイプの限外ろ過膜として、例えば、「マイクローザ　ＳＩＰ－１０５３」（旭化成社製）が例示される。なお、限外ろ過により脱塩処理する場合、濃縮した脱塩スラリーを得ることができる。 In ultrafiltration, impurities such as ions in the coprecipitation slurry can be sufficiently removed by circulating the slurry until the conductivity of the discharged ion-containing water is sufficiently lowered. Although various types, such as a hollow fiber type and a flat membrane type, can be used for the ultrafiltration membrane, a general-purpose hollow fiber type is more preferable. Examples of the hollow fiber type ultrafiltration membrane include “Microza SIP-1053” (manufactured by Asahi Kasei Corporation). In addition, when desalting is performed by ultrafiltration, a concentrated desalting slurry can be obtained.
　また、脱塩処理の手段として、遠心分離、真空乾燥ろ過機、フィルタープレス又はベルトフィルターを用いることもできる。これらの遠心分離、フィルタープレス又はベルトフィルターを用いた場合、脱塩スラリーの固形分濃度が３０～６０重量％であると、ウェットケーキ状のスラリーとなり、取り扱いやすい。 Further, as a means for desalting, a centrifugal separation, a vacuum drying filter, a filter press or a belt filter can be used. When these centrifugal separations, filter presses or belt filters are used, if the solid content concentration of the desalted slurry is 30 to 60% by weight, it becomes a wet cake slurry and is easy to handle.
　脱塩スラリーは、希釈することで、固形分濃度を調節することができる。また、この希釈の際に、必要に応じて、攪拌したり、超音波を照射したりすることで、粒子を効率良く分散させてもよい。しかし、粒子を分散させるために、ビーズミルやボールミルなどの比較的強度の強い方法を用いると、粒子の粒径が変化したり、スラリーの粘度が高くなり流動性が失われたりするため好ましくない。 The solids concentration can be adjusted by diluting the desalted slurry. Moreover, at the time of this dilution, you may disperse | distribute particle | grains efficiently by stirring or irradiating an ultrasonic wave as needed. However, it is not preferable to use a relatively strong method such as a bead mill or a ball mill to disperse the particles because the particle size of the particles changes or the viscosity of the slurry increases and the fluidity is lost.
　脱塩処理として、いずれの手段を使用した場合でも、得られる脱塩処理の程度は、排出されるイオン含有水の伝導度により評価することができる。具体的には、スラリーの固形分濃度を１０重量％に調製した際に、排出されるイオン含有水の伝導度は、１００μＳ／ｃｍ以下が好ましく、より好ましくは５０μＳ／ｃｍ以下であり、さらには１５μＳ／ｃｍ以下であると特に好ましい。 In any case, as a desalting treatment, the degree of the desalting treatment to be obtained can be evaluated by the conductivity of discharged ion-containing water. Specifically, when the solid content concentration of the slurry is adjusted to 10% by weight, the conductivity of the discharged ion-containing water is preferably 100 μS / cm or less, more preferably 50 μS / cm or less, It is especially preferable that it is 15 μS / cm or less.
　次いで、工程２から得られた脱塩スラリーを噴霧乾燥することにより、Ｎ元素及びＭ元素を均一に含有する乾燥造粒粉末を得ることができる（本発明において、この工程を工程３という）。噴霧乾燥する方法としては、スプレードライヤーを用いることが好ましい。この場合、運転条件を調整することによって、粒径の作りわけを行うことができる。スプレードライヤーとしては、噴霧するエア量により粒径の作り分けが容易な四流体ノズルの使用が好ましい。 Then, the desalted slurry obtained from step 2 is spray-dried to obtain a dry granulated powder containing N element and M element uniformly (in the present invention, this step is referred to as step 3). As a spray drying method, it is preferable to use a spray dryer. In this case, the particle size can be divided by adjusting the operating conditions. As the spray dryer, it is preferable to use a four-fluid nozzle that can easily make a particle size depending on the amount of air to be sprayed.
　噴霧乾燥に用いる脱塩スラリー中に分散する共沈粒子の一次粒子の平均粒子径は３μｍ以下であることが好ましく、なかでも２μｍ以下がより好ましく、１μｍ以下がさらに好ましく、０．５μｍ以下が特に好ましい。また、共沈粒子の一次粒子の平均粒子径は、０．００５μｍ以上が好ましく、０．０１μｍ以上がより好ましい。なお、本発明において、共沈粒子の一次粒子の平均粒子径は走査型電子顕微鏡（本発明においてＳＥＭということがある）で観察により求めることができる。より高解像度の画像が得られるので、超高分解能電界放出形走査電子顕微鏡（本発明においてＦＥ－ＳＥＭということがある）を用いるとより好ましい。造粒体粒子の表面をＳＥＭで観察したり、また造粒体をエポキシ樹脂などの熱硬化性樹脂に造粒体粒子を包埋して、それを研磨して、粒子の断面をＳＥＭで観察したりすることによって求めることができる。ＳＥＭの倍率は一次粒子の粒径によって観察しやすい倍率を選ぶことができるが、１万倍～５万倍の倍率で観察した画像を用いると好ましい。観察した画像から、画像解析ソフト（例えば、マウンテック社製画像解析ソフトＭａｃｖｉｅｗ　ｖｅｒ３．５）を用い、１００～３００個の粒子を計測し、その円相当径をして、一次粒子の粒子径が得られる。 The average particle diameter of primary particles of coprecipitated particles dispersed in the desalting slurry used for spray drying is preferably 3 μm or less, more preferably 2 μm or less, even more preferably 1 μm or less, and particularly preferably 0.5 μm or less. preferable. Further, the average particle diameter of primary particles of the coprecipitated particles is preferably 0.005 μm or more, and more preferably 0.01 μm or more. In the present invention, the average particle diameter of the primary particles of the coprecipitated particles can be obtained by observation with a scanning electron microscope (sometimes referred to as SEM in the present invention). Since a higher-resolution image can be obtained, it is more preferable to use an ultra-high-resolution field emission scanning electron microscope (sometimes referred to as FE-SEM in the present invention). The surface of the granulated particles is observed with an SEM, or the granulated particles are embedded in a thermosetting resin such as an epoxy resin, polished, and the cross section of the particles is observed with an SEM. It can be obtained by doing. The magnification of SEM can be easily selected depending on the primary particle size, but it is preferable to use an image observed at a magnification of 10,000 to 50,000 times. From the observed image, image analysis software (for example, image analysis software Macview ver3.5 manufactured by Mountec Co., Ltd.) is used to measure 100 to 300 particles, and the equivalent circle diameter is obtained to obtain the particle size of the primary particles. It is done.
　噴霧乾燥に用いる脱塩スラリー中の固形分濃度は１０重量％以上が好ましく、より好ましくは２０重量％以上、さらに好ましくは３０重量％以上、特には４０重量％以上が好ましい。また、脱塩スラリー中の固形分濃度は、７０重量％以下が好ましく、６０重量％以下がより好ましい。固形分濃度がこの範囲にある場合、噴霧する液滴のサイズを容易に調整することができ、造粒体粒子の粒径を容易に調整できる。さらに粒子の内部において、粒子が疎や密に偏ることなく均一に分布する。また、固形分濃度が高い方が生産性及び生産効率が高いことはもちろんのこと、スラリー中の水分が少ないため、噴霧乾燥に必要なエネルギーも少なくなるため好ましい。固形分濃度が１０重量％未満である場合、粒径を大きくすることが難しくなり、さらに造粒体内部の空隙が増え、該造粒体を原料として得られるリチウム含有複合酸化物の体積容量密度が低くなる傾向があり、好ましくない。さらに、生産性が低く、噴霧乾燥の際に必要なエネルギーが多くなり、好ましくない。 The solid concentration in the desalting slurry used for spray drying is preferably 10% by weight or more, more preferably 20% by weight or more, still more preferably 30% by weight or more, and particularly preferably 40% by weight or more. Further, the solid content concentration in the desalting slurry is preferably 70% by weight or less, and more preferably 60% by weight or less. When the solid content concentration is within this range, the size of droplets to be sprayed can be easily adjusted, and the particle size of the granulated particles can be easily adjusted. Furthermore, inside the particles, the particles are uniformly distributed without being sparsely or densely biased. Further, it is preferable that the solid content concentration is high because productivity and production efficiency are high, and since water in the slurry is small, energy required for spray drying is also reduced. When the solid content concentration is less than 10% by weight, it becomes difficult to increase the particle size, the voids inside the granulated body increase, and the volume capacity density of the lithium-containing composite oxide obtained using the granulated body as a raw material Tends to be low, which is not preferable. Furthermore, the productivity is low and the energy required for spray drying increases, which is not preferable.
　なお、本発明において、固形分濃度は次のようにして求める。まず脱塩スラリーの一部を分取して、分取したスラリーの重量を測定した後、その分取したスラリーを１００℃で乾燥して、乾燥粉末の重量を測定する。測定した乾燥粉末の重量を分取したスラリーの重量で除すことで、固形分濃度を求めることができる。 In the present invention, the solid content concentration is determined as follows. First, a part of the desalted slurry is taken and the weight of the taken slurry is measured, and then the taken slurry is dried at 100 ° C. to measure the weight of the dry powder. The solid content concentration can be determined by dividing the weight of the measured dry powder by the weight of the collected slurry.
　また、噴霧乾燥に用いる脱塩スラリーの粘度は２～１０００ｍＰａ・ｓが好ましく、より好ましくは２～５００ｍＰａ・ｓ、さらに好ましくは４～３００ｍＰａ・ｓ、特には６～１００ｍＰａ・ｓが好ましい。２ｍＰａ・ｓよりも粘度が低い場合、脱塩スラリーの固形分濃度が低かったり、又は分散した共沈粒子の粒径が大きかったりするため、球状の均一な造粒体を得ることができなくなり、好ましくない。１０００ｍＰａ・ｓよりも粘度が高い場合、スラリーの流動性が乏しく、溶液の搬送や、噴霧乾燥機のノズルへの搬送ができなくなったり、ノズルが閉塞したりするため、好ましくない。特に、６０重量％以上の固形分濃度が高いスラリーでは顕著である。 The viscosity of the desalted slurry used for spray drying is preferably 2 to 1000 mPa · s, more preferably 2 to 500 mPa · s, still more preferably 4 to 300 mPa · s, and particularly preferably 6 to 100 mPa · s. When the viscosity is lower than 2 mPa · s, the solid content concentration of the desalting slurry is low, or the particle size of the dispersed coprecipitated particles is large, so it becomes impossible to obtain a spherical uniform granulated product, It is not preferable. When the viscosity is higher than 1000 mPa · s, the fluidity of the slurry is poor, and it is not preferable because the solution cannot be transported or transported to the nozzle of the spray dryer or the nozzle is blocked. This is particularly noticeable in a slurry having a high solid content concentration of 60% by weight or more.
　本発明において、脱塩スラリーの粘度は、一般に回転式粘度計や振動式粘度計によって測定されるが、粘度計の形式、測定条件により変わる場合がある。本発明においては、ブルックフィールド社製デジタル回転粘度計ＤＶ－II＋のＬＶ型で少量サンプルユニットを用い、２５℃、３０ｒｐｍの条件にて測定し、粘度が１００ｍＰａ・ｓ以下の場合にはスピンドルＮｏ．１８を用い、１００ｍＰａ・ｓ以上の場合にはスピンドルＮｏ．３１を、１０００ｍＰａ・ｓ以上の場合にはスピンドルＮｏ．３４を用いて測定することが好ましい。 In the present invention, the viscosity of the desalted slurry is generally measured by a rotary viscometer or a vibration viscometer, but may vary depending on the type of viscometer and measurement conditions. In the present invention, a Brookfield digital rotational viscometer DV-II + LV type is used with a small sample unit and measured under conditions of 25 ° C. and 30 rpm. When the viscosity is 100 mPa · s or less, the spindle no. 18 is used, and in the case of 100 mPa · s or more, the spindle No. 31 is 1000 mPa · s or higher, the spindle no. It is preferable to measure using 34.
　なお、本発明に係る脱塩スラリーにおいて、固形分濃度をより高く、粘度をより低くするために、適宜、スラリーに分散剤を加えることができる。分散剤としては、ポリカルボン酸型高分子界面活性剤、ポリカルボン酸型高分子界面活性剤のアンモニウム塩、ポリアクリル酸塩など、一般的な分散剤を用いることができる。ただし、分散剤を過剰に加えると、焼成の際に、気体が発生して、得られるリチウム含有複合酸化物の粒子内部に空隙ができ、充填密度及び体積容量密度が低くなることがある。そのため、分散剤を添加する際は、適切な量の分散剤を添加することが好ましい。 In the desalted slurry according to the present invention, a dispersant can be appropriately added to the slurry in order to increase the solid content concentration and lower the viscosity. As the dispersant, general dispersants such as polycarboxylic acid type polymer surfactants, ammonium salts of polycarboxylic acid type polymer surfactants, and polyacrylates can be used. However, if an excessive amount of the dispersant is added, gas is generated during firing, voids are formed inside the particles of the obtained lithium-containing composite oxide, and the packing density and volume capacity density may be lowered. Therefore, when adding a dispersant, it is preferable to add an appropriate amount of the dispersant.
　噴霧乾燥して得られる造粒体粉末の平均粒子径（Ｄ５０）は１０～４０μｍであることが好ましく、より好ましくは１３～３０μｍ、さらには１５～２５μｍが好ましい。平均粒子径が１０μｍより小さいと、合成したリチウム含有複合酸化物の粒径が小さく、充填密度が低くなり、好ましくない。平均粒子径が４０μｍ超の場合、アルミニウム箔などの集電体への塗工が難しくなり、塗工した電極に傷が入ったり、もしくは正極活物質が集電体から剥離したりし、二次電池を作製することが難しい。 The average particle size (D50) of the granulated powder obtained by spray drying is preferably 10 to 40 μm, more preferably 13 to 30 μm, and even more preferably 15 to 25 μm. When the average particle size is smaller than 10 μm, the synthesized lithium-containing composite oxide has a small particle size and a low packing density, which is not preferable. When the average particle diameter is more than 40 μm, it becomes difficult to apply the coating to the current collector such as aluminum foil, the coated electrode is scratched, or the positive electrode active material is peeled off from the current collector. It is difficult to make a battery.
　なお、本発明において、平均粒子径（Ｄ５０）とは、レーザー散乱粒度分布測定装置（例えば、日機装社製マイクロトラックＨＲＡＸ－１００などを用いる）により得られた体積粒度分布の累積５０％の値を意味する。なお本発明において、平均粒子径（Ｄ５０）を、単に平均粒子径ということがある。また、後述するＤ１０は累積１０％、Ｄ９０は累積９０％の値を意味する。このとき、溶媒は造粒体が溶媒に解けて再分散しないような溶媒を選択する必要がある。本発明においては、溶媒にアセトンが使用される。 In the present invention, the average particle size (D50) is a cumulative 50% value of the volume particle size distribution obtained by a laser scattering particle size distribution measuring apparatus (for example, using Microtrack HRAX-100 manufactured by Nikkiso Co., Ltd.). means. In the present invention, the average particle size (D50) may be simply referred to as an average particle size. Further, D10 described later means a cumulative value of 10%, and D90 means a cumulative value of 90%. At this time, the solvent needs to be selected so that the granulated material dissolves into the solvent and does not redisperse. In the present invention, acetone is used as the solvent.
　また、本発明において、造粒体粉末のＤ１０は３～１３μｍが好ましく、５～１１μｍがより好ましい。Ｄ１０がこの範囲にある場合、リチウム化合物との焼成において、造粒体粉末がその形状を保ち、かつ充填されやすい粒径分布のリチウム含有複合酸化物になるため、高い充填密度、体積容量密度を有するリチウム含有複合酸化物が得られるため好ましい。Ｄ１０が３μｍよりも小さい場合、小さな粒子が複数集まっていびつな形に焼きあがってしまい、リチウム含有複合酸化物の充填密度が低下するため、好ましくない。また、Ｄ１０が１３μｍ超の場合、リチウム含有複合酸化物の粒径分布に小さな粒子がなくなるため充填密度が低下し、好ましくない。 In the present invention, the D10 of the granulated powder is preferably 3 to 13 μm, more preferably 5 to 11 μm. When D10 is in this range, the granulated powder maintains its shape and becomes a lithium-containing composite oxide having a particle size distribution that is easy to be filled in firing with a lithium compound. This is preferable because a lithium-containing composite oxide is obtained. When D10 is smaller than 3 μm, a plurality of small particles are collected and burnt into a rugged shape, which is not preferable because the packing density of the lithium-containing composite oxide is lowered. Further, when D10 exceeds 13 μm, there is no small particle in the particle size distribution of the lithium-containing composite oxide, which is not preferable because the packing density is lowered.
　また、本発明における造粒体粉末のＤ９０は、７０μｍ以下が好ましく、より好ましくは６０μｍ以下、さらには５０μｍ以下が好ましい。Ｄ９０が７０μｍ以下であると、正極活物質の電極への塗工が容易になり好ましい。 In addition, D90 of the granulated powder in the present invention is preferably 70 μm or less, more preferably 60 μm or less, and further preferably 50 μm or less. It is preferable that D90 is 70 μm or less because the application of the positive electrode active material to the electrode is facilitated.
　本発明において工程３で得られる造粒体粉末の気孔率は、６０％以上であることが好ましく、より好ましくは６５％以上であり、さらには７０％以上が好ましい。また気孔率は９０％以下が好ましく、８５％以下がより好ましい。高い気孔率を有する場合、リチウム原子が造粒体内部に浸透しやすく、均一に反応を進めることができ、粒子全体が緻密なリチウム含有複合酸化物を得ることができる。一方、気孔率が低く、６０％未満の場合には、粒子内の空隙が少なく、リチウム含有複合酸化物の作製時に表面と内部で反応に偏りができ、粒子の緻密化が均一に進まず、リチウム含有複合酸化物の充填密度が低く、体積容量密度が低くなり、好ましくない。 In the present invention, the porosity of the granulated powder obtained in step 3 is preferably 60% or more, more preferably 65% or more, and further preferably 70% or more. The porosity is preferably 90% or less, more preferably 85% or less. When it has a high porosity, lithium atoms can easily permeate into the granulated body, the reaction can be promoted uniformly, and a lithium-containing composite oxide with a dense particle as a whole can be obtained. On the other hand, when the porosity is low and less than 60%, there are few voids in the particles, the reaction can be biased on the surface and inside during the production of the lithium-containing composite oxide, and the densification of the particles does not progress uniformly, The filling density of the lithium-containing composite oxide is low, and the volume capacity density is low, which is not preferable.
　本発明において、気孔率は、水銀ポロシメーターを用いて、水銀圧入法によって、０．１ｋＰａ～４００ＭＰａの圧力で水銀を圧入して細孔分布を測定し、その累積細孔体積の半数となる細孔径の数値を意味する。 In the present invention, the porosity is determined by measuring the pore distribution by injecting mercury at a pressure of 0.1 kPa to 400 MPa by a mercury intrusion method using a mercury porosimeter, and the pore diameter which is half of the cumulative pore volume. Means the numerical value of
　また、本発明においては、造粒体粉末の平均細孔径の上限は、１μｍであることが好ましく、０．８μｍがより好ましく、０．５μｍがさらに好ましく、０．３μｍが特に好ましい。また、造粒体粉末の平均細孔径の下限は、０．０１μｍが好ましく、０．０５μｍがより好ましく、０．１μｍが特に好ましい。平均細孔径が上記範囲であると、焼成時に、粒子の緻密化が進むため、特に充填密度が高く、体積容量密度の高いリチウム含有複合酸化物が得られる。平均細孔径が１μｍよりも大きいと、リチウム含有複合酸化物の合成時に、粒子の緻密化が進まず、リチウム含有複合酸化物の充填密度が低く、体積容量密度が低くなり、好ましくない。 In the present invention, the upper limit of the average pore diameter of the granulated powder is preferably 1 μm, more preferably 0.8 μm, further preferably 0.5 μm, and particularly preferably 0.3 μm. The lower limit of the average pore diameter of the granulated powder is preferably 0.01 μm, more preferably 0.05 μm, and particularly preferably 0.1 μm. When the average pore diameter is in the above range, densification of the particles proceeds during firing, so that a lithium-containing composite oxide having a particularly high packing density and a high volume capacity density can be obtained. When the average pore diameter is larger than 1 μm, the densification of the particles does not proceed during the synthesis of the lithium-containing composite oxide, the packing density of the lithium-containing composite oxide is low, and the volume capacity density is low, which is not preferable.
　なお、本発明においては、平均細孔径とは、造粒体粉末を構成する粒子と粒子の隙間にできる細孔のサイズを測定し、その分布の平均値を意味する。平均細孔径は、水銀ポロシメーターによる、水銀圧入法で測定することができる。
　なお、図１から、造粒体粒子を形成する一次粒子が極めて小さな粒子であり、上記のとおり、本発明の造粒体粒子の気孔率が高いこと、及びその平均細孔径が小さいことがわかる。 In the present invention, the average pore diameter means the average value of the distribution obtained by measuring the size of pores formed in the gaps between the particles constituting the granulated powder. The average pore diameter can be measured by a mercury intrusion method using a mercury porosimeter.
In addition, it can be seen from FIG. 1 that the primary particles forming the granulated particles are very small particles, and as described above, the porosity of the granulated particles of the present invention is high and the average pore diameter is small. .
　本発明における造粒体粉末は実質上球状である。実質上球状とは、必ずしも真球である必要はなく、高い球状性を有するものや略球状のものも含まれる。このため、アスペクト比は１．２０以下が好ましく、１．１５以下がより好ましく、１．１０以下が特に好ましい。アスペクト比が１．２０を超える場合、合成したリチウム含有複合酸化物の球状性が悪く、充填密度が低く、体積容量密度が低くなる傾向がある。またアスペクト比は１以上が好ましい。 The granulated powder in the present invention is substantially spherical. The substantially spherical shape does not necessarily need to be a true sphere, and includes those having a high sphericity and those having a substantially spherical shape. For this reason, the aspect ratio is preferably 1.20 or less, more preferably 1.15 or less, and particularly preferably 1.10 or less. When the aspect ratio exceeds 1.20, the spherical shape of the synthesized lithium-containing composite oxide is poor, the packing density tends to be low, and the volume capacity density tends to be low. The aspect ratio is preferably 1 or more.
　なお、造粒体粉末のアスペクト比はＳＥＭで写真観察して求めることができる。具体的には、造粒体粒子を、エポキシ熱硬化性樹脂に包埋して、粒子断面を切断、研磨して粒子の断面を観察する。ＳＥＭで５００倍の倍率で１００～３００個の造粒体粒子断面を測定する。このとき画像に写る全ての粒子が粒径測定の対象となるようにする。アスペクト比とは各々の粒子の最長径を最長径の垂直径で割った値であり、それらの平均値が本発明におけるアスペクト比である。実施例では、マウンテック社製画像解析ソフトＭａｃｖｉｅｗ　ｖｅｒ３．５　を使用して測定した。図１及び図２から、本発明により得られる造粒体粒子が、高い球状性を有することがわかる。また、図３から、この造粒体粉末を原料にして、得られたリチウム含有複合酸化物が、高い球状性を有することがわかる。 The aspect ratio of the granulated powder can be determined by observing a photograph with an SEM. Specifically, the granulated particles are embedded in an epoxy thermosetting resin, the particle cross section is cut and polished, and the cross section of the particles is observed. 100 to 300 granule particle cross sections are measured with a SEM at a magnification of 500 times. At this time, all particles appearing in the image are to be subjected to particle size measurement. The aspect ratio is a value obtained by dividing the longest diameter of each particle by the vertical diameter of the longest diameter, and the average value thereof is the aspect ratio in the present invention. In the examples, measurement was performed using image analysis software Macview ver3.5 manufactured by Mountec. 1 and 2, it can be seen that the granulated particles obtained by the present invention have high sphericity. Further, FIG. 3 shows that the lithium-containing composite oxide obtained using this granulated powder as a raw material has high sphericity.
　造粒体粉末は、高い流動性を有しており、安息角が６０°以下であることが好ましく、５５°以下がより好ましく、５０°以下がさらに好ましい。安息角が６０°超であると、リチウム含有複合酸化物は充填密度が低く、体積容量密度が低くなる傾向がある。一方、安息角の下限は、３０°が好ましく、４０°がより好ましい。上記した範囲に造粒体の安息角が含まれる場合、高い流動性を有する造粒体粉末から合成されたリチウム含有複合酸化物は高い充填密度、体積容量密度を有するので好ましい。
　また、本発明において、造粒体粉末は、水酸化物、オキシ水酸化物、酸化物、硫酸塩であることが好ましく、なかでも水酸化物、オキシ水酸化物がより好ましく、水酸化物であると特に好ましい。 The granulated powder has high fluidity and preferably has an angle of repose of 60 ° or less, more preferably 55 ° or less, and further preferably 50 ° or less. When the angle of repose is more than 60 °, the lithium-containing composite oxide tends to have a low packing density and a low volume capacity density. On the other hand, the lower limit of the angle of repose is preferably 30 °, more preferably 40 °. When the angle of repose of the granule is included in the above range, a lithium-containing composite oxide synthesized from a granulated powder having high fluidity is preferable because it has a high packing density and volume capacity density.
In the present invention, the granulated powder is preferably a hydroxide, oxyhydroxide, oxide, or sulfate, more preferably a hydroxide or oxyhydroxide, and more preferably a hydroxide. Particularly preferred.
　本発明においては、工程３で得られた、Ｎ元素及びＭ元素を均一に含有する造粒体粉末は、次いで、リチウム化合物粉末と混合した後、酸素含有雰囲気中において好ましくは６００～１１００℃で焼成することによりリチウム含有複合酸化物を得ることができる。リチウム化合物粉末としては、炭酸リチウム、水酸化リチウム、硝酸リチウムなどを使用できるが、なかでも、取り扱いが容易で安価な炭酸リチウムが好ましい。 In the present invention, the granulated powder uniformly containing the N element and M element obtained in the step 3 is then mixed with the lithium compound powder, and then preferably at 600 to 1100 ° C. in an oxygen-containing atmosphere. The lithium-containing composite oxide can be obtained by firing. As the lithium compound powder, lithium carbonate, lithium hydroxide, lithium nitrate, or the like can be used. Among them, lithium carbonate that is easy to handle and inexpensive is preferable.
　上記造粒体粉末とリチウム化合物とを混合して得られる混合物は６００～１１００℃で焼成するが、下限について、好ましくは７００℃、より好ましくは８００℃、さらに好ましくは１０００℃、次いで１０１０℃、１０３０℃の順番に好ましい。一方、焼成温度の上限は、１０７０℃が好ましく、１０５０℃がより好ましい。 The mixture obtained by mixing the granulated powder and the lithium compound is fired at 600 to 1100 ° C., but the lower limit is preferably 700 ° C., more preferably 800 ° C., more preferably 1000 ° C., then 1010 ° C., Preferred in the order of 1030 ° C. On the other hand, the upper limit of the firing temperature is preferably 1070 ° C and more preferably 1050 ° C.
　上記のようにして得られるリチウムイオン二次電池正極活物質用のリチウム含有複合酸化物は、好ましくは、式ＬｉｐＮｘＭｙＯｚで表される。この式において、ｐ、ｘ、ｙ、ｚは、以下のとおりである。０．９≦ｐ≦１．５、好ましくは０．９５≦ｐ≦１．４５、０．９６≦ｘ≦２．００、好ましくは０．９８≦ｘ≦１．１０、０＜ｙ≦０．０４、好ましくは０＜ｙ≦０．０３、１．９≦ｚ≦４．２、好ましくは１．９５≦ｚ≦２．０５。なお、式中のＮ及びＭは、本発明の造粒体を製造する際に用いた、Ｎ元素及びＭ元素をそれぞれ意味している。 The lithium-containing composite oxide for a lithium ion secondary battery positive electrode active material obtained as described above is preferably represented by the formula Li p N x M y O z . In this formula, p, x, y, and z are as follows. 0.9 ≦ p ≦ 1.5, preferably 0.95 ≦ p ≦ 1.45, 0.96 ≦ x ≦ 2.00, preferably 0.98 ≦ x ≦ 1.10, 0 <y ≦ 0. 04, preferably 0 <y ≦ 0.03, 1.9 ≦ z ≦ 4.2, preferably 1.95 ≦ z ≦ 2.05. In addition, N and M in a formula mean the N element and M element which were used when manufacturing the granulated body of this invention, respectively.
　本発明のリチウム含有複合酸化物は、遷移金属がコバルトを主体とする場合、そのプレス密度は好ましくは３．１ｇ／ｃｍ３以上であり、より好ましくは３．２ｇ／ｃｍ３以上、特には３．３ｇ／ｃｍ以上が好ましい。また、上限は３．６ｇ／ｃｍ３が好ましく、特に好ましくは３．５ｇ／ｃｍ３である。なお、本発明におけるプレス密度は、粒子粉末５ｇを０．３２ｔ／ｃｍ２の圧力でプレスしたときの見かけのプレス密度をいう。プレス密度の値及び図３から、本発明のリチウム含有複合酸化物の充填性が高いことがわかる。 When the transition metal is mainly composed of cobalt, the lithium-containing composite oxide of the present invention preferably has a press density of 3.1 g / cm 3 or more, more preferably 3.2 g / cm 3 or more, particularly 3 .3 g / cm or more is preferable. The upper limit is preferably 3.6 g / cm 3 , particularly preferably 3.5 g / cm 3 . The press density in the present invention refers to the apparent press density when 5 g of the particle powder is pressed at a pressure of 0.32 t / cm 2 . From the value of the press density and FIG. 3, it can be seen that the filling property of the lithium-containing composite oxide of the present invention is high.
　本発明のリチウム含有複合酸化物を用いて、リチウムイオン二次電池用正極を得る方法は、常法に従って実施できる。例えば、本発明の正極活物質の粉末に、アセチレンブラック、黒鉛、ケッチェンブラック等のカーボン系導電材と、結合材とを混合することにより正極合剤が形成される。結合材には、ポリフッ化ビニリデン、ポリテトラフルオロエチレン、ポリアミド、カルボキシメチルセルロース、アクリル樹脂等が用いられる。
　上記の正極合剤を、Ｎ－メチルピロリドンなどの分散媒に分散させたスラリーをアルミニウム箔等の正極集電体に塗工・乾燥及びプレス圧延せしめて正極活物質層を正極集電体上に形成する。 The method of obtaining the positive electrode for lithium ion secondary batteries using the lithium containing complex oxide of this invention can be implemented in accordance with a conventional method. For example, the positive electrode mixture is formed by mixing the positive electrode active material powder of the present invention with a carbon-based conductive material such as acetylene black, graphite, or ketjen black and a binder. As the binder, polyvinylidene fluoride, polytetrafluoroethylene, polyamide, carboxymethyl cellulose, acrylic resin, or the like is used.
A slurry in which the above positive electrode mixture is dispersed in a dispersion medium such as N-methylpyrrolidone is applied to a positive electrode current collector such as an aluminum foil, dried, and press-rolled to form a positive electrode active material layer on the positive electrode current collector. Form.
　本発明の正極活物質を正極に使用するリチウムイオン二次電池において、電解質溶液の溶質としては、ＣｌＯ4 －、ＣＦ3ＳＯ3 －、ＢＦ4 －、ＰＦ6 －、ＡｓＦ6 －、ＳｂＦ6 －、ＣＦ3ＣＯ2 －、（ＣＦ3ＳＯ2）2Ｎ－等をアニオンとするリチウム塩のいずれか１種以上を使用することが好ましい。上記の電解質溶液又はポリマー電解質は、リチウム塩を含む電解質を前記溶媒又は溶媒含有ポリマーに０．２～２．０ｍｏｌ／Ｌの濃度で添加するのが好ましい。この範囲を逸脱すると、イオン伝導度が低下し、電解質の電気伝導度が低下する。より好ましくは０．５～１．５ｍｏｌ／Ｌが選定される。セパレータには多孔質ポリエチレン、多孔質ポリプロピレンフィルムが使用される。 In the lithium ion secondary battery using the positive electrode active material of the present invention for the positive electrode, the solute of the electrolyte solution is ClO 4 − , CF 3 SO 3 − , BF 4 − , PF 6 − , AsF 6 − , SbF 6 −. It is preferable to use any one or more of lithium salts having CF 3 CO 2 − , (CF 3 SO 2 ) 2 N − and the like as anions. In the above electrolyte solution or polymer electrolyte, an electrolyte containing a lithium salt is preferably added to the solvent or solvent-containing polymer at a concentration of 0.2 to 2.0 mol / L. If it deviates from this range, the ionic conductivity is lowered and the electrical conductivity of the electrolyte is lowered. More preferably, 0.5 to 1.5 mol / L is selected. For the separator, porous polyethylene or porous polypropylene film is used.
　また、電解質溶液の溶媒としては炭酸エステルが好ましい。炭酸エステルは環状、鎖状いずれも使用できる。環状炭酸エステルとしては、プロピレンカーボネート、エチレンカーボネート（ＥＣ）等が例示される。鎖状炭酸エステルとしては、ジメチルカーボネート、ジエチルカーボネート（ＤＥＣ）、エチルメチルカーボネート、メチルプロピルカーボネート、メチルイソプロピルカーボネート等が例示される。
　上記炭酸エステルは単独でも２種以上を混合して使用してもよい。また、他の溶媒と混合して使用してもよい。また、負極活物質の材料によっては、鎖状炭酸エステルと環状炭酸エステルを併用すると、放電特性、サイクル耐久性、充放電効率が改良できる場合がある。 Further, as the solvent of the electrolyte solution, a carbonate ester is preferable. The carbonate ester can be either cyclic or chain. Examples of cyclic carbonates include propylene carbonate and ethylene carbonate (EC). Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate (DEC), ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate and the like.
The carbonate ester may be used alone or in combination of two or more. Moreover, you may mix and use with another solvent. Moreover, depending on the material of the negative electrode active material, when a chain carbonate ester and a cyclic carbonate ester are used in combination, discharge characteristics, cycle durability, and charge / discharge efficiency may be improved.
　また、これらの有機溶媒にフッ化ビニリデン－ヘキサフルオロプロピレン共重合体（例えばアトケム社製カイナー）又はフッ化ビニリデン－パーフルオロプロピルビニルエーテル共重合体を添加し、下記の溶質を加えることによりゲルポリマー電解質としても良い。
　本発明の正極活物質を正極に使用するリチウムイオン二次電池の負極活物質は、リチウムイオンを吸蔵、放出可能な材料である。負極活物質を形成する材料は特に限定されないが、例えばリチウム金属、リチウム合金、炭素材料、炭素化合物、炭化ケイ素化合物、酸化ケイ素化合物、硫化チタン、炭化ホウ素化合物、周期表１４、１５族の金属を主体とした酸化物等が挙げられる。 Further, by adding a vinylidene fluoride-hexafluoropropylene copolymer (for example, Kyner manufactured by Atchem Co.) or a vinylidene fluoride-perfluoropropyl vinyl ether copolymer to these organic solvents, and adding the following solute, the gel polymer electrolyte is added. It is also good.
The negative electrode active material of a lithium ion secondary battery using the positive electrode active material of the present invention for the positive electrode is a material that can occlude and release lithium ions. The material for forming the negative electrode active material is not particularly limited. For example, lithium metal, lithium alloy, carbon material, carbon compound, silicon carbide compound, silicon oxide compound, titanium sulfide, boron carbide compound, periodic table 14, and group 15 metal are used. The main oxides are listed.
　炭素材料としては、様々な熱分解条件で有機物を熱分解したものや人造黒鉛、天然黒鉛、土壌黒鉛、膨張黒鉛、鱗片状黒鉛等を使用できる。また、酸化物としては、酸化スズを主体とする化合物が使用できる。負極集電体としては、銅箔、ニッケル箔等が用いられる。
　本発明における正極活物質を使用するリチウムイオン二次電池の形状には、特に制約はない。シート状（いわゆるフイルム状）、折り畳み状、巻回型有底円筒形、ボタン形等が用途に応じて選択される。 As the carbon material, those obtained by pyrolyzing organic substances under various pyrolysis conditions, artificial graphite, natural graphite, soil graphite, expanded graphite, scale-like graphite, and the like can be used. As the oxide, a compound mainly composed of tin oxide can be used. As the negative electrode current collector, a copper foil, a nickel foil or the like is used.
There is no restriction | limiting in particular in the shape of the lithium ion secondary battery which uses the positive electrode active material in this invention. A sheet shape (so-called film shape), a folded shape, a wound-type bottomed cylindrical shape, a button shape, or the like is selected depending on the application.
　以下に本発明を具体的に説明するが、本発明はこれらの実施例に限定されないことはもちろんである。
［例１］（実施例）
　コバルト含量２０．９６重量％の硫酸コバルト７水和物１１２．４７ｇ、ニッケル含量２２．３１重量％の硫酸ニッケル６水和物１０５．２３ｇ、マンガン含量２２．７１重量％の硫酸マンガン５水和物９６．７６ｇ、ジルコニウム含有量１９．０５重量％の硫酸ジルコニウム４水和物５．８０ｇを蒸留水５００ｇに溶解し、コバルト、ニッケル、マンガン及びジルコニウムが均一に溶解した、コバルト、ニッケル、マンガン及びジルコニウム含有水溶液を調製した。２Ｌガラス反応器に蒸留水を１Ｌ入れ、前記のコバルト、ニッケル、マンガン及びジルコニウム含有水溶液を１０ｇ／ｍｉｎの供給速度で添加しつつ、かつ系内のｐＨが１１．５を維持するように４８重量％の水酸化ナトリウム水溶液と蒸留水を断続的に添加し、コバルト、ニッケル、マンガン及びジルコニウムを含有する水酸化物を析出させ、当該水酸化物粉末のスラリー２．２ｋｇを作製した。この時、スラリー中に存在する水酸化物の濃度は５重量％であった。 The present invention will be specifically described below, but the present invention is of course not limited to these examples.
[Example 1] (Example)
112.47 g of cobalt sulfate heptahydrate having a cobalt content of 20.96 wt%, 105.23 g of nickel sulfate hexahydrate having a nickel content of 22.31 wt%, and manganese sulfate pentahydrate having a manganese content of 22.71 wt% Cobalt, nickel, manganese and zirconium in which cobalt, nickel, manganese and zirconium were uniformly dissolved by dissolving 5.80 g of zirconium sulfate tetrahydrate having a zirconium content of 19.05% by weight in 96 g of distilled water. A containing aqueous solution was prepared. 1 L of distilled water was put into a 2 L glass reactor, and the above-mentioned aqueous solution containing cobalt, nickel, manganese and zirconium was added at a feed rate of 10 g / min, and 48 weight was maintained so that the pH in the system was maintained at 11.5. % Sodium hydroxide aqueous solution and distilled water were intermittently added to precipitate a hydroxide containing cobalt, nickel, manganese and zirconium, thereby preparing 2.2 kg of a slurry of the hydroxide powder. At this time, the concentration of hydroxide present in the slurry was 5% by weight.
　次いで、前記スラリーを限外ろ過装置の原水タンクに供給した。次に、ポンプで圧力をかけながら、限外ろ過装置中でスラリーを循環させるとともに、イオン含有水を排出させつつ、スラリーの固形分濃度が１０重量％になるように、かつ液量を一定に維持するように蒸留水を添加した。この状態を維持しつつ、排出されるイオン含有水の伝導度が１５μＳ／ｃｍになるまで、限外ろ過装置中でスラリーを循環させ続けた。スラリー中のイオンなどの不純物を取り除く脱塩の操作をすることにより、脱塩を行った。さらに蒸留水の添加を止め、スラリーを濃縮して脱塩スラリーを得た。なお限外ろ過膜には旭化成社製「マイクローザ　ＳＩＰ－１０５３」を使用した。この脱塩スラリーの粘度は４２ｍＰａ・ｓ、スラリーを分取して、１００℃で乾燥して測定した固形分濃度は１５重量％であった。 Next, the slurry was supplied to the raw water tank of the ultrafiltration device. Next, while applying pressure with a pump, the slurry is circulated in the ultrafiltration device and the water content is kept constant so that the solid content concentration of the slurry becomes 10% by weight while discharging the ion-containing water. Distilled water was added to maintain. While maintaining this state, the slurry was continuously circulated in the ultrafiltration device until the conductivity of the discharged ion-containing water reached 15 μS / cm. Desalination was performed by performing a desalting operation to remove impurities such as ions in the slurry. Further, the addition of distilled water was stopped, and the slurry was concentrated to obtain a desalted slurry. As the ultrafiltration membrane, “Microza SIP-1053” manufactured by Asahi Kasei Co., Ltd. was used. The desalting slurry had a viscosity of 42 mPa · s, and the solid concentration measured by separating the slurry and drying at 100 ° C. was 15% by weight.
　次いで、スプレードライヤーを用いて、前記の脱塩スラリーの５００ｇを造粒しながら乾燥して、コバルト、ニッケル、マンガン、ジルコニウムの各元素を含有する水酸化物からなる造粒体粉末を得た。なおスプレードライヤーには、ヤマト科学社製「ＧＢ２２」を使用した。運転条件は、スラリー供給速度１０ｇ／ｍｉｎ、噴霧ガス圧力０．１５ＭＰａ、ガス温度１８０℃であった。 Next, using a spray dryer, 500 g of the desalted slurry was dried while granulating to obtain a granulated powder composed of hydroxides containing cobalt, nickel, manganese and zirconium elements. As a spray dryer, “GB22” manufactured by Yamato Scientific Co., Ltd. was used. The operating conditions were a slurry supply rate of 10 g / min, a spray gas pressure of 0.15 MPa, and a gas temperature of 180 ° C.
　前記の造粒体粉末を、ＳＥＭで観察したところ、０．０２～０．７５μｍの一次粒子が凝集して略球状の二次粒子を形成していることがわかった。また、マウンテック社製画像解析ソフトＭａｃｖｉｅｗ　ｖｅｒ３．５を用いて測定した共沈粒子の一次粒子の平均粒子径は０．２５μｍであった。また二次粒子の平均粒子径は１６．０μｍであり、Ｄ１０は５．５μｍ、Ｄ９０は３６．５μｍであった。また、造粒体粉末の気孔率は８３％、平均細孔径は０．１３μｍ、アスペクト比は１．０７、安息角は５５°であり、ニッケル、コバルト、マンガン及びジルコニウムを合計した含量は６０．８重量％であった。 When the granulated powder was observed by SEM, it was found that primary particles of 0.02 to 0.75 μm aggregated to form substantially spherical secondary particles. Moreover, the average particle diameter of the primary particles of the coprecipitated particles measured by using image analysis software Macview ver3.5 manufactured by Mountec was 0.25 μm. The average particle size of the secondary particles was 16.0 μm, D10 was 5.5 μm, and D90 was 36.5 μm. The granulated powder has a porosity of 83%, an average pore diameter of 0.13 μm, an aspect ratio of 1.07, an angle of repose of 55 °, and a total content of nickel, cobalt, manganese and zirconium of 60. It was 8% by weight.
　さらに前記の造粒体粉末２０ｇを、リチウム含量１８．７重量％の炭酸リチウム８．１９ｇとを混合して、得られたリチウム混合粉末を酸素含有雰囲気下１０００℃で１６時間焼成した。その後、粉砕してＬｉ１．０２４Ｎｉ０．３２２Ｃｏ０．３２２Ｍｎ０．３２２Ｚｒ０．０１Ｏ２の組成を有する略球状のリチウム含有複合酸化物粉末を得た。
　得られたリチウム含有複合酸化物の粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ　２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６５．１±１°の（１１０）面の回折ピーク半値幅は０．１７８°であった。この粉末を０．３２トン／ｃｍ２の圧力でプレスしたときのプレス密度は２．９２ｇ／ｃｍ３であった。 Further, 20 g of the granulated powder was mixed with 8.19 g of lithium carbonate having a lithium content of 18.7% by weight, and the resulting lithium mixed powder was fired at 1000 ° C. for 16 hours in an oxygen-containing atmosphere. Thereafter, the mixture was pulverized to obtain a substantially spherical lithium-containing composite oxide powder having a composition of Li 1.024 Ni 0.322 Co 0.322 Mn 0.322 Zr 0.01 O 2 .
With respect to the obtained powder of lithium-containing composite oxide, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα ray, the half value width of the diffraction peak of (110) plane at 2θ = 65.1 ± 1 ° was 0.178 °. When this powder was pressed at a pressure of 0.32 ton / cm 2 , the press density was 2.92 g / cm 3 .
　また、得られたリチウム含有複合酸化物粉末を、ＳＥＭで観察したところ、０．５～３μｍの一次粒子が凝集して略球状の二次粒子を形成していることがわかった。リチウム含有複合酸化物粒子の平均粒子径は１２．５μｍ、Ｄ１０は５．５μｍ、Ｄ９０は２５．２μｍであった。比表面積は０．６１ｍ２／ｇであった。 Further, when the obtained lithium-containing composite oxide powder was observed with an SEM, it was found that primary particles of 0.5 to 3 μm aggregated to form substantially spherical secondary particles. The average particle size of the lithium-containing composite oxide particles was 12.5 μm, D10 was 5.5 μm, and D90 was 25.2 μm. The specific surface area was 0.61 m 2 / g.
　次に、前記リチウム含有複合酸化物粉末と、アセチレンブラックと、ポリフッ化ビニリデン粉末とを９０／５／５の重量比で混合し、Ｎ－メチルピロリドンを添加してスラリーを作製し、厚さ２０μｍのアルミニウム箔にドクターブレードを用いて片面塗工した。次いで乾燥し、ロールプレス圧延を３回行うことによりリチウム電池用の正極体シートを作製した。 Next, the lithium-containing composite oxide powder, acetylene black, and polyvinylidene fluoride powder were mixed at a weight ratio of 90/5/5, and N-methylpyrrolidone was added to prepare a slurry, with a thickness of 20 μm. The aluminum foil was coated on one side using a doctor blade. Subsequently, it dried and the positive electrode sheet | seat for lithium batteries was produced by performing roll press rolling 3 times.
　次に、前記の正極体シートを打ち抜いたものを正極に用い、厚さ５００μｍの金属リチウム箔を負極に用い、負極集電体にニッケル箔２０μｍを使用し、セパレータには厚さ２５μｍの多孔質ポリプロピレンを用い、さらに電解液には、濃度１ＭのＬｉＰＦ６／ＥＣ＋ＤＥＣ（１：１）溶液（ＬｉＰＦ６を溶質とするＥＣとＤＥＣとの重量比（１：１）の混合溶液を意味する。後記する溶媒もこれに準じる）を用いてステンレス製簡易密閉セル型リチウム電池をアルゴングローブボックス内で２個組み立てた。 Next, a punched sheet of the positive electrode body is used as the positive electrode, a metal lithium foil having a thickness of 500 μm is used as the negative electrode, a nickel foil of 20 μm is used as the negative electrode current collector, and a porous material having a thickness of 25 μm is used as the separator. Polypropylene is used, and the electrolyte solution is a LiPF 6 / EC + DEC (1: 1) solution having a concentration of 1 M (meaning a mixed solution of EC and DEC in a weight ratio (1: 1) containing LiPF 6 as a solute). Two similar stainless-cell closed cell type lithium batteries were assembled in an argon glove box using the same solvent.
　前記１個の電池については、２５℃にて正極活物質１ｇにつき３０ｍＡの負荷電流で４．３Ｖまで充電し、正極活物質１ｇにつき３０ｍＡの負荷電流にて２．５Ｖまで放電して初期放電容量を求めた。また、この電池について、引き続き充放電サイクル試験を３０回行った。その結果、２５℃、２．５～４．３Ｖにおける正極の初期重量容量密度は、１５２ｍＡｈ／ｇであり、３０回充放電サイクル後の容量維持率は９５．１％であった。プレス密度と初期重量容量密度をかけあわせることで計算できる、体積容量密度は４４４ｍＡｈ／ｃｍ３であった。さらにもう一つの電池については、４．３Ｖで１０時間充電し、アルゴングローブボックス内で解体し、充電後の正極体シートを取り出し、その正極体シートを洗浄後、直径３ｍｍに打ち抜き、ＥＣとともにアルミニウム製カプセルに密閉し、走査型差動熱量計にて５℃／分の速度で昇温して発熱開始温度を測定した。その結果、発熱曲線の発熱開始温度は２３１℃であった。 The one battery is charged to 4.3 V at a load current of 30 mA per 1 g of the positive electrode active material at 25 ° C., and discharged to 2.5 V at a load current of 30 mA per 1 g of the positive electrode active material. Asked. Moreover, about this battery, the charging / discharging cycle test was performed 30 times continuously. As a result, the initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 152 mAh / g, and the capacity retention rate after 30 charge / discharge cycles was 95.1%. The volume capacity density, which can be calculated by multiplying the press density and the initial weight capacity density, was 444 mAh / cm 3 . For another battery, it was charged at 4.3 V for 10 hours, disassembled in an argon glove box, the positive electrode sheet after charging was taken out, the positive electrode sheet was washed, punched to a diameter of 3 mm, and aluminum together with EC. It sealed in the capsule made from a product, and heated at a rate of 5 ° C./min with a scanning differential calorimeter to measure the heat generation start temperature. As a result, the heat generation start temperature of the heat generation curve was 231 ° C.
［例２］（実施例）
　コバルト含量２０．９６重量％の硫酸コバルト７水和物３３７．４１ｇ、アルミニウム含量１５．６重量％の硫酸アルミニウム０．２１ｇ、マグネシウム含量１０．１重量％の硫酸マグネシウム７水和物０．２９ｇ、ジルコニウム含有量１９．０５重量％の硫酸ジルコニウム４水和物０．２９ｇをそれぞれ蒸留水５００ｇに溶解し、コバルト、アルミニウム、マグネシウム及びジルコニウムが均一に溶解した、コバルト、アルミニウム、マグネシウム及びジルコニウム含有水溶液を調製した。２Ｌガラス反応器に蒸留水を１Ｌ入れ、前記のコバルト、アルミニウム、マグネシウム及びジルコニウム含有水溶液を１０ｇ／ｍｉｎの供給速度で添加しつつ、かつ系内のｐＨが１０．５を維持するように４８重量％の水酸化ナトリウム水溶液と蒸留水を断続的に添加し、コバルト、アルミニウム、マグネシウム及びジルコニウムを含有する水酸化物を析出させ、当該水酸化物粉末のスラリー２．２ｋｇを作製した。この時、スラリー中に存在する水酸化物の濃度は５重量％であった。 [Example 2] (Example)
337.41 g of cobalt sulfate heptahydrate having a cobalt content of 20.96 wt%, 0.21 g of aluminum sulfate having an aluminum content of 15.6 wt%, 0.29 g of magnesium sulfate heptahydrate having a magnesium content of 10.1 wt%, An aqueous solution containing cobalt, aluminum, magnesium and zirconium in which 0.29 g of zirconium sulfate tetrahydrate having a zirconium content of 19.05% by weight was dissolved in 500 g of distilled water and cobalt, aluminum, magnesium and zirconium were uniformly dissolved. Prepared. 1 L of distilled water is put into a 2 L glass reactor, and the above-mentioned aqueous solution containing cobalt, aluminum, magnesium and zirconium is added at a feed rate of 10 g / min, and 48 weight is maintained so that the pH in the system is maintained at 10.5. % Aqueous sodium hydroxide solution and distilled water were intermittently added to precipitate a hydroxide containing cobalt, aluminum, magnesium and zirconium, thereby preparing 2.2 kg of the slurry of the hydroxide powder. At this time, the concentration of hydroxide present in the slurry was 5% by weight.
　次いで、前記スラリーを限外ろ過装置の原水タンクに供給し、例１と同様に、排出されるイオン含有水の伝導度が１５μＳ／ｃｍになるまで、限外ろ過を行った。さらに蒸留水の添加を止め運転し、スラリーを濃縮して脱塩スラリーを得た。この脱塩スラリーの粘度は５７ｍＰａ・ｓ、固形分濃度は１３重量％であった。 Next, the slurry was supplied to the raw water tank of the ultrafiltration apparatus, and ultrafiltration was performed in the same manner as in Example 1 until the conductivity of the discharged ion-containing water reached 15 μS / cm. Further, the addition of distilled water was stopped and the slurry was concentrated to obtain a desalted slurry. The desalted slurry had a viscosity of 57 mPa · s and a solid content concentration of 13% by weight.
　例１と同様の操作を行って、コバルト、アルミニウム、マグネシウム及びジルコニウムからなる造粒体粉末を得た。前記の造粒体粉末を、ＳＥＭで観察したところ、０．０２～０．７５μｍの一次粒子が凝集して略球状の二次粒子を形成していることがわかった。また、共沈粒子の一次粒子の平均粒子径は０．２２μｍであった。また平均粒子径は２２．５μｍであり、Ｄ１０は９．４μｍ、Ｄ９０は４１．１μｍであった。また、造粒体粉末の気孔率は８１％、平均細孔径は０．１７μｍ、アスペクト比は１．０７、安息角は４８°であり、コバルト、アルミニウム、マグネシウム及びジルコニウムを合計した含量が６２．０重量％であった。 The same operation as in Example 1 was performed to obtain a granulated powder composed of cobalt, aluminum, magnesium and zirconium. When the granulated powder was observed by SEM, it was found that primary particles of 0.02 to 0.75 μm aggregated to form substantially spherical secondary particles. Moreover, the average particle diameter of the primary particles of the coprecipitated particles was 0.22 μm. The average particle size was 22.5 μm, D10 was 9.4 μm, and D90 was 41.1 μm. The granulated powder has a porosity of 81%, an average pore diameter of 0.17 μm, an aspect ratio of 1.07, an angle of repose of 48 °, and a total content of cobalt, aluminum, magnesium and zirconium of 62. It was 0% by weight.
　さらに前記の造粒体粉末３０ｇを、リチウム含量１８．７重量％の炭酸リチウム１１．７ｇとを混合して、得られたリチウム混合粉末を酸素含有雰囲気下１０３０℃で１５時間焼成した。その後、粉砕してＬｉＣｏ０．９９７５Ａｌ０．００１Ｍｇ０．００１Ｚｒ０．０００５Ｏ２の組成を有する略球状のリチウム含有複合酸化物粉末を得た。
　得られたリチウム含有複合酸化物の粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ　２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６５．１±１°の（１１０）面の回折ピークの積分幅は０．１２２°であった。この粉末を０．３２トン／ｃｍ２の圧力でプレスしたときのプレス密度は３．３０ｇ／ｃｍ３であった。 Further, 30 g of the granulated powder was mixed with 11.7 g of lithium carbonate having a lithium content of 18.7% by weight, and the obtained lithium mixed powder was fired at 1030 ° C. for 15 hours in an oxygen-containing atmosphere. Thereafter, the mixture was pulverized to obtain a substantially spherical lithium-containing composite oxide powder having a composition of LiCo 0.9975 Al 0.001 Mg 0.001 Zr 0.0005 O 2 .
With respect to the obtained powder of lithium-containing composite oxide, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα rays, the integral width of the diffraction peak on the (110) plane at 2θ = 65.1 ± 1 ° was 0.122 °. When this powder was pressed at a pressure of 0.32 ton / cm 2 , the press density was 3.30 g / cm 3 .
　また、得られたリチウム含有複合酸化物粉末の平均粒子径は１５．６μｍ、Ｄ１０は７．４μｍ、Ｄ９０は２７．４μｍであった。比表面積は０．４１ｍ２／ｇであった。２５℃、２．５～４．３Ｖにおける正極の初期重量容量密度は、１６１ｍＡｈ／ｇであり、体積容量密度は５３０ｍＡｈ／ｃｍ３であった。３０回充放電サイクル後の容量維持率は９８．８％であった。また、発熱曲線の発熱開始温度は１６２℃であった。 The obtained lithium-containing composite oxide powder had an average particle size of 15.6 μm, D10 of 7.4 μm, and D90 of 27.4 μm. The specific surface area was 0.41 m 2 / g. The initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 161 mAh / g, and the volume capacity density was 530 mAh / cm 3 . The capacity retention rate after 30 charge / discharge cycles was 98.8%. The heat generation start temperature of the heat generation curve was 162 ° C.
［例３］（実施例）
　コバルト含量２０．９６重量％の硫酸コバルト７水和物３３７．４１ｇ、アルミニウム含量１５．６重量％の硫酸アルミニウム２．１２ｇ、マグネシウム含量１０．１重量％の硫酸マグネシウム７水和物２．９５ｇ、ジルコニウム含有量１９．０５重量％の硫酸ジルコニウム４水和物０．２９ｇをそれぞれ蒸留水５００ｇに溶解し、コバルト、アルミニウム、マグネシウム及びジルコニウムが均一に溶解した、コバルト、アルミニウム、マグネシウム及びジルコニウム含有水溶液を調製した。２Ｌガラス反応器に蒸留水を１Ｌ入れ、前記のコバルト、アルミニウム、マグネシウム及びジルコニウム含有水溶液を１０ｇ／ｍｉｎの供給速度で添加しつつ、かつ系内のｐＨが１０．５を維持するように４８重量％の水酸化ナトリウム水溶液と蒸留水を断続的に添加し、コバルト、アルミニウム、マグネシウム及びジルコニウムを含有する水酸化物を析出させ、当該水酸化物粉末のスラリー２．２ｋｇを作製した。この時、スラリー中に存在する水酸化物の濃度は５重量％であった。 [Example 3] (Example)
337.41 g of cobalt sulfate heptahydrate with a cobalt content of 20.96 wt%, 2.12 g of aluminum sulfate with an aluminum content of 15.6 wt%, 2.95 g of magnesium sulfate heptahydrate with a magnesium content of 10.1 wt%, An aqueous solution containing cobalt, aluminum, magnesium and zirconium in which 0.29 g of zirconium sulfate tetrahydrate having a zirconium content of 19.05% by weight was dissolved in 500 g of distilled water and cobalt, aluminum, magnesium and zirconium were uniformly dissolved. Prepared. 1 L of distilled water is put into a 2 L glass reactor, and the above-mentioned aqueous solution containing cobalt, aluminum, magnesium and zirconium is added at a feed rate of 10 g / min, and 48 weight is maintained so that the pH in the system is maintained at 10.5. % Aqueous sodium hydroxide solution and distilled water were intermittently added to precipitate a hydroxide containing cobalt, aluminum, magnesium and zirconium, thereby preparing 2.2 kg of the slurry of the hydroxide powder. At this time, the concentration of hydroxide present in the slurry was 5% by weight.
　次いで、前記スラリーを限外ろ過装置の原水タンクに供給し、例１と同様に、排出されるイオン含有水の伝導度が１５μＳ／ｃｍになるまで、限外ろ過を行った。さらに蒸留水の添加を止め運転し、スラリーを濃縮して脱塩スラリーを得た。この脱塩スラリーの粘度は１３０ｍＰａ・ｓ、固形分濃度は４０重量％であった。 Next, the slurry was supplied to the raw water tank of the ultrafiltration apparatus, and ultrafiltration was performed in the same manner as in Example 1 until the conductivity of the discharged ion-containing water reached 15 μS / cm. Further, the addition of distilled water was stopped and the slurry was concentrated to obtain a desalted slurry. The desalted slurry had a viscosity of 130 mPa · s and a solid content concentration of 40% by weight.
　例１と同様の操作を行って、コバルト、アルミニウム、マグネシウム及びジルコニウムからなる造粒体粉末を得た。この造粒体の粒子断面を撮影したＳＥＭ像を図１に、造粒体粒子粉末を撮影したＳＥＭ像を図２に示す。図１及び図２から、本発明により得られる造粒体粒子が、高い球状性を有することがわかる。前記の造粒体粉末を、ＳＥＭで観察したところ、０．０２～０．７５μｍの一次粒子が凝集して略球状の二次粒子を形成していることがわかった。また、共沈粒子の一次粒子の平均粒子径は０．３８μｍであった。また二次粒子の平均粒子径は２２．５μｍであり、Ｄ１０は１０．９μｍ、Ｄ９０は５３．６μｍであった。また、造粒体粉末の気孔率は７８％、平均細孔径は０．２７μｍ、アスペクト比は１．１０、安息角は５１°であり、コバルト、アルミニウム、マグネシウム及びジルコニウムを合計した含量が６１．２重量％であった。さらに前記の造粒体粉末３０ｇを、リチウム含量１８．７重量％の炭酸リチウム１２．１ｇとを混合して、得られたリチウム混合粉末を酸素含有雰囲気下１０３０℃で１５時間焼成した。その後、粉砕してＬｉ１．００９９Ｃｏ０．９６９８Ａｌ０．００９９Ｍｇ０．００９９Ｚｒ０．０００５Ｏ２の組成を有する略球状のリチウム含有複合酸化物粉末を得た。 The same operation as in Example 1 was performed to obtain a granulated powder composed of cobalt, aluminum, magnesium and zirconium. An SEM image obtained by photographing the particle cross section of this granulated body is shown in FIG. 1, and an SEM image obtained by photographing the granulated particle powder is shown in FIG. 1 and 2, it can be seen that the granulated particles obtained by the present invention have high sphericity. When the granulated powder was observed by SEM, it was found that primary particles of 0.02 to 0.75 μm aggregated to form substantially spherical secondary particles. The average particle diameter of primary particles of the coprecipitated particles was 0.38 μm. The average particle diameter of the secondary particles was 22.5 μm, D10 was 10.9 μm, and D90 was 53.6 μm. The granulated powder has a porosity of 78%, an average pore diameter of 0.27 μm, an aspect ratio of 1.10, an angle of repose of 51 °, and a total content of cobalt, aluminum, magnesium and zirconium of 61. It was 2% by weight. Further, 30 g of the granulated powder was mixed with 12.1 g of lithium carbonate having a lithium content of 18.7% by weight, and the obtained lithium mixed powder was fired at 1030 ° C. for 15 hours in an oxygen-containing atmosphere. Thereafter, the mixture was pulverized to obtain a substantially spherical lithium-containing composite oxide powder having a composition of Li 1.0099 Co 0.9698 Al 0.0099 Mg 0.0099 Zr 0.0005 O 2 .
　得られたリチウム含有複合酸化物の粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ　２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６５．１±１°の（１１０）面の回折ピークの積分幅は０．１１３°であった。この粉末を０．３２トン／ｃｍ２の圧力でプレスしたときのプレス密度は３．３６ｇ／ｃｍ３であった。得られたリチウム含有複合酸化物の粒子断面を撮影したＳＥＭ像を図３に示す。図３から、この造粒体粉末を原料にして、得られたリチウム含有複合酸化物が、高い球状性を有することがわかる。 With respect to the obtained powder of lithium-containing composite oxide, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα rays, the integral width of the diffraction peak on the (110) plane at 2θ = 65.1 ± 1 ° was 0.113 °. When this powder was pressed at a pressure of 0.32 ton / cm 2 , the press density was 3.36 g / cm 3 . The SEM image which image | photographed the particle | grain cross section of the obtained lithium containing complex oxide is shown in FIG. FIG. 3 shows that the lithium-containing composite oxide obtained using this granulated powder as a raw material has high sphericity.
　また、得られたリチウム含有複合酸化物粉末の平均粒子径は１７．４μｍ、Ｄ１０は７．７μｍ、Ｄ９０は３５．３μｍであった。比表面積は０．３９ｍ２／ｇであった。２５℃、２．５～４．３Ｖにおける正極の初期重量容量密度は、１５５ｍＡｈ／ｇであり、体積容量密度は５２１ｍＡｈ／ｃｍ３であった。３０回充放電サイクル後の容量維持率は９５．４％であった。また、発熱曲線の発熱開始温度は１６４℃であった。
［例４］（実施例）
　コバルト含量２０．９６重量％の硫酸コバルト７水和物６７．２５ｇ、ニッケル含量２２．３１重量％の硫酸ニッケル６水和物１８８．７９ｇ、マンガン含量２２．７１重量％の硫酸マンガン５水和物５７．８７ｇ、ジルコニウム含有量１９．０５重量％の硫酸ジルコニウム４水和物５．７８ｇを蒸留水５００ｇに溶解し、コバルト、ニッケル、マンガン及びジルコニウムが均一に溶解した、コバルト、ニッケル、マンガン及びジルコニウム含有水溶液を調製した。２Ｌガラス反応器に蒸留水を１Ｌ入れ、前記のコバルト、ニッケル、マンガン及びジルコニウム含有水溶液を１０ｇ／ｍｉｎの供給速度で添加しつつ、かつ系内のｐＨが１２．２を維持するように４８重量％の水酸化ナトリウム水溶液と蒸留水を断続的に添加し、コバルト、ニッケル、マンガン及びジルコニウムを含有する水酸化物を析出させ、当該水酸化物粉末のスラリー２．２ｋｇを作製した。この時、スラリー中に存在する水酸化物の濃度は５重量％であった他は例１と同様の操作を行い、脱塩スラリーを経て、造粒体粉末を得た。途中で得られた脱塩スラリーの粘度は４０ｍＰａ・ｓ、固形分濃度は３５重量％であった。 The obtained lithium-containing composite oxide powder had an average particle size of 17.4 μm, D10 of 7.7 μm, and D90 of 35.3 μm. The specific surface area was 0.39 m 2 / g. The initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 155 mAh / g, and the volume capacity density was 521 mAh / cm 3 . The capacity retention rate after 30 charge / discharge cycles was 95.4%. Further, the heat generation start temperature of the heat generation curve was 164 ° C.
[Example 4] (Example)
67.25 g of cobalt sulfate heptahydrate with a cobalt content of 20.96% by weight, 188.79 g of nickel sulfate hexahydrate with a nickel content of 22.31% by weight, manganese sulfate pentahydrate with a manganese content of 22.71% by weight Cobalt, nickel, manganese and zirconium in which cobalt, nickel, manganese and zirconium are uniformly dissolved by dissolving 5.78 g of zirconium sulfate tetrahydrate having a zirconium content of 19.05% by weight in 500 g of distilled water. A containing aqueous solution was prepared. 1 L of distilled water was put into a 2 L glass reactor, and the above-mentioned aqueous solution containing cobalt, nickel, manganese and zirconium was added at a feed rate of 10 g / min, and 48 wt. So that the pH in the system was maintained at 12.2. % Sodium hydroxide aqueous solution and distilled water were intermittently added to precipitate a hydroxide containing cobalt, nickel, manganese and zirconium, thereby preparing 2.2 kg of a slurry of the hydroxide powder. At this time, except that the concentration of hydroxide present in the slurry was 5% by weight, the same operation as in Example 1 was performed, and a granulated powder was obtained through a desalting slurry. The viscosity of the desalted slurry obtained along the way was 40 mPa · s, and the solid content concentration was 35% by weight.
　得られた造粒体粉末を、ＳＥＭで観察したところ、０．０５～１．０μｍの一次粒子が凝集して略球状の二次粒子を形成していることがわかった。また、共沈粒子の一次粒子の平均粒子径は０．５２μｍであった。また二次粒子の平均粒子径は１５．２μｍであり、Ｄ１０は５．３μｍ、Ｄ９０は３２．５μmであった。また、造粒体粉末の気孔率は７８％、平均細孔径は０．１４μm、アスペクト比は１．１３、安息角は５８°であり、ニッケル、コバルト、マンガン及びジルコニウムを合計した含量は６０．４重量％であった。 When the obtained granulated powder was observed with an SEM, it was found that primary particles of 0.05 to 1.0 μm aggregated to form substantially spherical secondary particles. The average particle diameter of the primary particles of the coprecipitated particles was 0.52 μm. The average particle diameter of the secondary particles was 15.2 μm, D10 was 5.3 μm, and D90 was 32.5 μm. The granulated powder has a porosity of 78%, an average pore diameter of 0.14 μm, an aspect ratio of 1.13 and an angle of repose of 58 °, and the total content of nickel, cobalt, manganese and zirconium is 60. It was 4% by weight.
　さらに前記の造粒体粉末２０ｇを、リチウム含量１８．７重量％の炭酸リチウム８．０７ｇとを混合して、得られた混合物粉末を酸素含有雰囲気下９００℃で１６時間焼成した。その後、粉砕してＬｉ１．０２４Ｎｉ０．５８０Ｃｏ０．１９３Ｍｎ０．１９３Ｚｒ０．０１Ｏ２の組成を有する略球状のリチウム含有複合酸化物粉末を得た。 Further, 20 g of the granulated powder was mixed with 8.07 g of lithium carbonate having a lithium content of 18.7% by weight, and the obtained mixture powder was fired at 900 ° C. for 16 hours in an oxygen-containing atmosphere. Thereafter, the mixture was pulverized to obtain a substantially spherical lithium-containing composite oxide powder having a composition of Li 1.024 Ni 0.580 Co 0.193 Mn 0.193 Zr 0.01 O 2 .
　得られたリチウム含有複合酸化物の粉末について、例１と同様の操作を行って評価した。（１１０）面の回折ピーク半値幅は０．１７８°であり、プレス密度は２．９５ｇ／ｃｍ３であった。また、得られたリチウム含有複合酸化物粉末を、ＳＥＭで観察したところ、０．５～３μｍの一次粒子が凝集して略球状の二次粒子を形成していることがわかった。平均粒子径は１２．６μｍ、Ｄ１０は５．９μｍ、Ｄ９０は２４．９μｍであった。比表面積は０．５９ｍ２／ｇであり、正極の初期重量容量密度は、１６０ｍＡｈ／ｇであり、容量維持率は９５．８％であり、体積容量密度は４７２ｍＡｈ／ｃｍ３であり、発熱開始温度は２１８℃であった。
［例５］（実施例）
　コバルト含量２０．９６重量％の硫酸コバルト７水和物３１２．１ｇ、アルミニウム含量１５．６重量％の硫酸アルミニウム０．２０ｇ、マグネシウム含量１０．１重量％の硫酸マグネシウム７水和物０．２９ｇ、チタン含有量６．０重量％の硫酸チタン水溶液０．４７ｇをそれぞれ蒸留水５００ｇに溶解し、コバルト、アルミニウム、マグネシウム及びチタンが均一に溶解した、コバルト、アルミニウム、マグネシウム及びチタン含有水溶液を調製した。２Ｌガラス反応器に蒸留水を１Ｌ入れ、前記のコバルト、アルミニウム、マグネシウム及びチタン含有水溶液を１０ｇ／ｍｉｎの供給速度で添加しつつ、かつ系内のｐＨが１０．５を維持するように４８重量％の水酸化ナトリウム水溶液と蒸留水を断続的に添加し、コバルト、アルミニウム、マグネシウム及びチタンを含有する水酸化物を析出させ、当該水酸化物粉末のスラリー２．２ｋｇを作製した。この時、スラリー中に存在する水酸化物の濃度は５重量％であった。 The obtained lithium-containing composite oxide powder was evaluated in the same manner as in Example 1. The half value width of the diffraction peak of (110) plane was 0.178 °, and the press density was 2.95 g / cm 3 . Further, when the obtained lithium-containing composite oxide powder was observed with an SEM, it was found that primary particles of 0.5 to 3 μm aggregated to form substantially spherical secondary particles. The average particle size was 12.6 μm, D10 was 5.9 μm, and D90 was 24.9 μm. The specific surface area is 0.59 m 2 / g, the initial weight capacity density of the positive electrode is 160 mAh / g, the capacity retention ratio is 95.8%, the volume capacity density is 472 mAh / cm 3 , and heat generation starts. The temperature was 218 ° C.
[Example 5] (Example)
312.1 g of cobalt sulfate heptahydrate with a cobalt content of 20.96 wt%, 0.20 g of aluminum sulfate with an aluminum content of 15.6 wt%, 0.29 g of magnesium sulfate heptahydrate with a magnesium content of 10.1 wt%, An aqueous solution containing cobalt, aluminum, magnesium and titanium in which 0.47 g of titanium sulfate aqueous solution having a titanium content of 6.0% by weight was dissolved in 500 g of distilled water and cobalt, aluminum, magnesium and titanium were uniformly dissolved was prepared. 1 L of distilled water was put into a 2 L glass reactor, and the above-mentioned aqueous solution containing cobalt, aluminum, magnesium and titanium was added at a feed rate of 10 g / min, and 48 weight was maintained so that the pH in the system was maintained at 10.5. % Sodium hydroxide aqueous solution and distilled water were intermittently added to precipitate a hydroxide containing cobalt, aluminum, magnesium and titanium, thereby preparing 2.2 kg of a slurry of the hydroxide powder. At this time, the concentration of hydroxide present in the slurry was 5% by weight.
　次いで、前記スラリーを限外ろ過装置の原水タンクに供給し、例１と同様に、排出されるイオン含有水の伝導度が１５μＳ／ｃｍになるまで、限外ろ過を行った。さらに蒸ｎ留水の添加を止め運転し、スラリーを濃縮して脱塩スラリーを得た。この脱塩スラリーの粘度は１１０ｍＰａ・ｓ、固形分濃度は３５重量％であった。 Next, the slurry was supplied to the raw water tank of the ultrafiltration apparatus, and ultrafiltration was performed in the same manner as in Example 1 until the conductivity of the discharged ion-containing water reached 15 μS / cm. Further, the addition of steamed water was stopped and the slurry was concentrated to obtain a desalted slurry. The desalted slurry had a viscosity of 110 mPa · s and a solid content concentration of 35% by weight.
　例１と同様の操作を行って、コバルト、アルミニウム、マグネシウム及びチタンからなる造粒体粉末を得た。前記の造粒体粉末を、ＳＥＭで観察したところ、０．０２～０．７５μｍの一次粒子が凝集して略球状の二次粒子を形成していることがわかった。また、共沈粒子の一次粒子の平均粒子径は０．２９μｍであった。また二次粒子の平均粒子径は２０．６μｍであり、Ｄ１０は８．２μｍ、Ｄ９０は３６．７μｍであった。また、造粒体粉末の気孔率は８０％、平均細孔径は０．１４μｍ、アスペクト比は１．０９、安息角は５４°であり、コバルト、アルミニウム、マグネシウム及びチタンを合計した含量が６０．８重量％であった。さらに前記の造粒体粉末３０ｇを、リチウム含量１８．７重量％の炭酸リチウム１２．１ｇとを混合して、得られたリチウム混合粉末を酸素含有雰囲気下１０３０℃で１５時間焼成した。その後、粉砕してＬｉＣｏ０．９９７５Ａｌ０．００１Ｍｇ０．００１Ｔｉ０．０００５Ｏ２の組成を有する略球状のリチウム含有複合酸化物粉末を得た。 The same operation as in Example 1 was performed to obtain a granulated powder composed of cobalt, aluminum, magnesium and titanium. When the granulated powder was observed by SEM, it was found that primary particles of 0.02 to 0.75 μm aggregated to form substantially spherical secondary particles. The average particle size of the primary particles of the coprecipitated particles was 0.29 μm. The average particle diameter of the secondary particles was 20.6 μm, D10 was 8.2 μm, and D90 was 36.7 μm. The granulated powder has a porosity of 80%, an average pore diameter of 0.14 μm, an aspect ratio of 1.09, an angle of repose of 54 °, and a total content of cobalt, aluminum, magnesium and titanium of 60. It was 8% by weight. Further, 30 g of the granulated powder was mixed with 12.1 g of lithium carbonate having a lithium content of 18.7% by weight, and the obtained lithium mixed powder was fired at 1030 ° C. for 15 hours in an oxygen-containing atmosphere. Thereafter, the mixture was pulverized to obtain a substantially spherical lithium-containing composite oxide powder having a composition of LiCo 0.9975 Al 0.001 Mg 0.001 Ti 0.0005 O 2 .
　得られたリチウム含有複合酸化物の粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ　２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６５．１±１°の（１１０）面の回折ピークの積分幅は０．１１９°であった。この粉末を０．３２トン／ｃｍ２の圧力でプレスしたときのプレス密度は３．３０ｇ／ｃｍ３であった。 With respect to the obtained powder of lithium-containing composite oxide, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα rays, the integral width of the diffraction peak on the (110) plane at 2θ = 65.1 ± 1 ° was 0.119 °. When this powder was pressed at a pressure of 0.32 ton / cm 2 , the press density was 3.30 g / cm 3 .
　また、得られたリチウム含有複合酸化物粉末の平均粒子径は１６．２μｍ、Ｄ１０は７．９μｍ、Ｄ９０は２６．２μｍであった。比表面積は０．４０ｍ２／ｇであった。２５℃、２．５～４．３Ｖにおける正極の初期重量容量密度は、１６０ｍＡｈ／ｇであり、体積容量密度は５２８ｍＡｈ／ｃｍ３であった。３０回充放電サイクル後の容量維持率は９７．５％であった。また、発熱曲線の発熱開始温度は１６０℃であった。 The obtained lithium-containing composite oxide powder had an average particle size of 16.2 μm, D10 of 7.9 μm, and D90 of 26.2 μm. The specific surface area was 0.40 m 2 / g. The initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 160 mAh / g, and the volume capacity density was 528 mAh / cm 3 . The capacity retention rate after 30 charge / discharge cycles was 97.5%. The heat generation start temperature of the heat generation curve was 160 ° C.
［例６］（比較例）
　コバルト含量２０．９６重量％の硫酸コバルト７水和物３３７．４１ｇ、アルミニウム含量１５．６重量％の硫酸アルミニウム２．１２ｇ、マグネシウム含量１０．１重量％の硫酸マグネシウム７水和物２．９５ｇ、ジルコニウム含有量１９．０５重量％の硫酸ジルコニウム４水和物０．２９ｇをそれぞれ蒸留水５００ｇに溶解し、コバルト、アルミニウム、マグネシウム及びジルコニウムが均一に溶解した、コバルト、アルミニウム、マグネシウム及びジルコニウム含有水溶液を調製した。２Ｌガラス反応器に蒸留水を１Ｌ入れ、前記の水溶液を０．５ｇ／ｍｉｎの供給速度で添加しつつ、かつ系内のｐＨが９．５を維持するように４８重量％の水酸化ナトリウム水溶液と蒸留水を断続的に添加し、コバルト、アルミニウム、マグネシウム及びジルコニウムを含有する水酸化物を析出させ、水酸化物粉末のスラリー２．２ｋｇを作製した。この時、スラリー中に存在する水酸化物の濃度は５重量％であった。 [Example 6] (Comparative example)
337.41 g of cobalt sulfate heptahydrate with a cobalt content of 20.96 wt%, 2.12 g of aluminum sulfate with an aluminum content of 15.6 wt%, 2.95 g of magnesium sulfate heptahydrate with a magnesium content of 10.1 wt%, An aqueous solution containing cobalt, aluminum, magnesium and zirconium in which 0.29 g of zirconium sulfate tetrahydrate having a zirconium content of 19.05% by weight was dissolved in 500 g of distilled water and cobalt, aluminum, magnesium and zirconium were uniformly dissolved. Prepared. 1 L of distilled water was put into a 2 L glass reactor, and the aqueous solution was added at a feed rate of 0.5 g / min, and a 48 wt% aqueous sodium hydroxide solution was maintained so that the pH in the system was maintained at 9.5. And distilled water were intermittently added to precipitate a hydroxide containing cobalt, aluminum, magnesium and zirconium, thereby preparing 2.2 kg of a hydroxide powder slurry. At this time, the concentration of hydroxide present in the slurry was 5% by weight.
　次いで、前記スラリーを、吸引ろ過した後、ろ過後のケーキを再び純水への分散することを繰り返し、ろ過後のろ液の伝導度が１５μＳ／ｃｍになるまで、同じ操作を繰り返し、脱塩した。脱塩後のケーキを１２０℃で乾燥して、アルミニウム、マグネシウム及びジルコニウムをドープした共沈水酸化コバルト粉末を得た。得られた共沈水酸化コバルト粉末の平均粒子径は１８．６μｍであり、Ｄ１０は１４．３μｍ、Ｄ９０は２５．０μｍであった。また、共沈水酸化コバルト粉末の気孔率は５３％、平均細孔径は２．５μｍ、アスペクト比は１．２３、安息角は５０°であり、コバルト、アルミニウム、マグネシウム及びジルコニウムを合計した含量が６２．４重量％であった。さらに、この共沈水酸化コバルト粉末３０ｇを、リチウム含量１８．７重量％の炭酸リチウム１２．０ｇとを混合して、得られた混合物粉末を酸素含有雰囲気下１０３０℃で１５時間焼成した。その後、粉砕してＬｉＣｏ０．９９７５Ａｌ０．００１Ｍｇ０．００１Ｚｒ０．０００５Ｏ２の組成を有するリチウム含有複合酸化物粉末を得た。 Next, after the slurry is suction filtered, the filtered cake is repeatedly dispersed in pure water again, and the same operation is repeated until the filtrate has a conductivity of 15 μS / cm, followed by desalting. did. The desalted cake was dried at 120 ° C. to obtain a coprecipitated cobalt hydroxide powder doped with aluminum, magnesium and zirconium. The average particle diameter of the obtained coprecipitated cobalt hydroxide powder was 18.6 μm, D10 was 14.3 μm, and D90 was 25.0 μm. The coprecipitated cobalt hydroxide powder has a porosity of 53%, an average pore diameter of 2.5 μm, an aspect ratio of 1.23, an angle of repose of 50 °, and a total content of cobalt, aluminum, magnesium and zirconium of 62. .4% by weight. Further, 30 g of this coprecipitated cobalt hydroxide powder was mixed with 12.0 g of lithium carbonate having a lithium content of 18.7% by weight, and the resultant mixture powder was fired at 1030 ° C. for 15 hours in an oxygen-containing atmosphere. Then, to obtain a lithium-containing composite oxide powder having a composition of LiCo 0.9975 Al 0.001 Mg 0.001 Zr 0.0005 O 2 was pulverized.
　得られたリチウム含有複合酸化物の粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ　２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６５．１±１°の（１１０）面の回折ピークの積分幅は０．１２０°であった。この粉末を０．３２トン/ｃｍ２の圧力でプレスしたときのプレス密度は２．８８ｇ／ｃｍ３であった。平均粒子径は１８．６μｍ、Ｄ１０は１４．３μｍ、Ｄ９０は２５．０μｍであった。比表面積は０．４７ｍ２／ｇであった。２５℃、２．５～４．３Ｖにおける正極の初期重量容量密度は、１４８ｍＡｈ／ｇであり、体積容量密度は４５２ｍＡｈ／ｃｍ３であった。３０回充放電サイクル後の容量維持率は９９．５％であった。また、発熱曲線の発熱開始温度は１５７℃であった。 With respect to the obtained powder of lithium-containing composite oxide, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα rays, the integral width of the diffraction peak on the (110) plane at 2θ = 65.1 ± 1 ° was 0.120 °. When this powder was pressed at a pressure of 0.32 ton / cm 2 , the press density was 2.88 g / cm 3 . The average particle size was 18.6 μm, D10 was 14.3 μm, and D90 was 25.0 μm. The specific surface area was 0.47 m 2 / g. The initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 148 mAh / g, and the volume capacity density was 452 mAh / cm 3 . The capacity retention rate after 30 charge / discharge cycles was 99.5%. The heat generation start temperature of the heat generation curve was 157 ° C.
［例７］（比較例）
　コバルト含量２０．９６重量％の硫酸コバルト７水和物３２８．０ｇを蒸留水５００ｇに溶解し、コバルト含有水溶液を作製した。２Ｌガラス反応器に蒸留水を１Ｌ入れ、前記のコバルト含有水溶液を０．１５ｇ／ｍｉｎの供給速度で添加しつつ、かつ系内のｐＨが９．５を維持するように４８重量％の水酸化ナトリウム水溶液と蒸留水を断続的に添加し、水酸化コバルトを析出させ、水酸化コバルト粉末のスラリー２．２ｋｇを作製した。この時、スラリー中に存在する水酸化物の濃度は５重量％であった。 [Example 7] (Comparative Example)
A cobalt-containing aqueous solution was prepared by dissolving 328.0 g of cobalt sulfate heptahydrate having a cobalt content of 20.96 wt% in 500 g of distilled water. 1 L of distilled water was placed in a 2 L glass reactor, and the above cobalt-containing aqueous solution was added at a feed rate of 0.15 g / min, and 48 wt% hydroxylation was maintained so that the pH in the system was maintained at 9.5. Sodium aqueous solution and distilled water were intermittently added to precipitate cobalt hydroxide, thereby preparing 2.2 kg of cobalt hydroxide powder slurry. At this time, the concentration of hydroxide present in the slurry was 5% by weight.
　次いで、このスラリーをろ過して、洗浄することで、水酸化コバルトを得た。この水酸化コバルトを、スラリーに再び分散して、スラリーを作製した。この再分散したスラリーを、ディスク回転式乾燥機を用いて噴霧乾燥して、水酸化コバルト造粒体を得た。前記の水酸化コバルト造粒体の粉末を、ＳＥＭで観察したところ、０．０２～０．７５μｍの一次粒子が凝集して略球状の二次粒子を形成していることがわかった。また、共沈粒子の一次粒子の平均粒子径は０．３２μｍであった。また二次粒子の平均粒子径は２４．５μｍであり、Ｄ１０は８．５μｍ、Ｄ９０は４８．４μｍであった。また、造粒体粉末の気孔率は７８％、平均細孔径は０．１４μｍ、アスペクト比は１．１０、安息角は５５°であり、コバルトの含量が６２．５重量％であった。さらに前記の造粒体粉末３０ｇを、リチウム含量１８．７重量％の炭酸リチウム１１．８ｇとを混合して、得られたリチウム混合粉末を酸素含有雰囲気下９００℃で１５時間焼成した。その後、粉砕してＬｉＣｏＯ２の組成を有するリチウム含有複合酸化物粉末を得た。 The slurry was then filtered and washed to obtain cobalt hydroxide. This cobalt hydroxide was dispersed again in the slurry to prepare a slurry. This re-dispersed slurry was spray-dried using a disk rotary dryer to obtain a cobalt hydroxide granule. When the cobalt hydroxide granulated powder was observed with an SEM, it was found that primary particles of 0.02 to 0.75 μm aggregated to form substantially spherical secondary particles. Moreover, the average particle diameter of the primary particles of the coprecipitated particles was 0.32 μm. The average particle diameter of the secondary particles was 24.5 μm, D10 was 8.5 μm, and D90 was 48.4 μm. The granulated powder had a porosity of 78%, an average pore diameter of 0.14 μm, an aspect ratio of 1.10, an angle of repose of 55 °, and a cobalt content of 62.5% by weight. Further, 30 g of the granulated powder was mixed with 11.8 g of lithium carbonate having a lithium content of 18.7% by weight, and the obtained lithium mixed powder was fired at 900 ° C. for 15 hours in an oxygen-containing atmosphere. Then, to obtain a lithium-containing composite oxide powder having a composition of LiCoO 2 was pulverized.
　得られたリチウム含有複合酸化物の粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ　２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６５．１±１°の（１１０）面の回折ピークの積分幅は０．１６８°であった。この粉末を０．３２トン／ｃｍ２の圧力でプレスしたときのプレス密度は２．７５ｇ／ｃｍ３であった。 With respect to the obtained powder of lithium-containing composite oxide, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα rays, the integral width of the diffraction peak on the (110) plane at 2θ = 65.1 ± 1 ° was 0.168 °. When this powder was pressed at a pressure of 0.32 ton / cm 2 , the press density was 2.75 g / cm 3 .
　また、得られたリチウム含有複合酸化物粉末を、ＳＥＭで観察したところ、０．５～２μｍの一次粒子が凝集して略球状の二次粒子を形成していることがわかった。平均粒子径は１７．９μｍ、Ｄ１０は５．８μｍ、Ｄ９０は３７．５μｍであった。比表面積は０．８５ｍ２／ｇであった。２５℃、２．５～４．３Ｖにおける正極の初期重量容量密度は、１６２ｍＡｈ／ｇであり、体積容量密度は４４６ｍＡｈ／ｃｍ３であった。３０回充放電サイクル後の容量維持率は８７．５％であった。また、発熱曲線の発熱開始温度は１５４℃であった。 Further, when the obtained lithium-containing composite oxide powder was observed with an SEM, it was found that primary particles of 0.5 to 2 μm aggregated to form substantially spherical secondary particles. The average particle size was 17.9 μm, D10 was 5.8 μm, and D90 was 37.5 μm. The specific surface area was 0.85 m 2 / g. The initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 162 mAh / g, and the volume capacity density was 446 mAh / cm 3 . The capacity retention rate after 30 charge / discharge cycles was 87.5%. The heat generation start temperature of the heat generation curve was 154 ° C.
［例８］（比較例）
　例７で作製した水酸化コバルト造粒体３０ｇとリチウム含量１８．７重量％の炭酸リチウム１１．８ｇとを混合して、得られたリチウム混合粉末を酸素含有雰囲気下１０３０℃で１５時間焼成した。その後、粉砕してＬｉＣｏＯ２の組成を有するリチウム含有複合酸化物粉末を得た。得られたリチウム含有複合酸化物の粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ　２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６５．１±１°の（１１０）面の回折ピークの積分幅は０．１２０°であった。この粉末を０．３２トン／ｃｍ２の圧力でプレスしたときのプレス密度は３．０８ｇ／ｃｍ３であった。 [Example 8] (Comparative example)
30 g of the cobalt hydroxide granulate prepared in Example 7 and 11.8 g of lithium carbonate having a lithium content of 18.7 wt% were mixed, and the resulting lithium mixed powder was fired at 1030 ° C. for 15 hours in an oxygen-containing atmosphere. . Then, to obtain a lithium-containing composite oxide powder having a composition of LiCoO 2 was pulverized. With respect to the obtained powder of lithium-containing composite oxide, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα rays, the integral width of the diffraction peak on the (110) plane at 2θ = 65.1 ± 1 ° was 0.120 °. When this powder was pressed at a pressure of 0.32 ton / cm 2 , the press density was 3.08 g / cm 3 .
　また、得られたリチウム含有複合酸化物粉末の平均粒子径は１５．８μｍ、Ｄ１０は７．０μｍ、Ｄ９０は２９．５μｍであった。比表面積は０．３８ｍ２／ｇであった。２５℃、２．５～４．３Ｖにおける正極の初期重量容量密度は、１６０ｍＡｈ／ｇであり、体積容量密度は４９３ｍＡｈ／ｃｍ３であった。３０回充放電サイクル後の容量維持率は８９．０％であった。また、発熱曲線の発熱開始温度は１５６℃であった。 The obtained lithium-containing composite oxide powder had an average particle size of 15.8 μm, D10 of 7.0 μm, and D90 of 29.5 μm. The specific surface area was 0.38 m 2 / g. The initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 160 mAh / g, and the volume capacity density was 493 mAh / cm 3 . The capacity retention rate after 30 charge / discharge cycles was 89.0%. Moreover, the heat generation start temperature of the heat generation curve was 156 ° C.
［例９］（比較例）
　コバルト含量が６２．３重量％の水酸化コバルト１０３．４８ｇと、アルミニウム含量が３４．５５重量％の水酸化アルミニウム０．８７ｇと、マグネシウム含量が４１．６４重量％の水酸化マグネシウム０．６５ｇとを混合し、水を加えて攪拌し、３００ｇのスラリーとした。次いで、循環式媒体攪拌型湿式ビーズミルを用いて、このスラリーに分散する各原料粒子を、平均粒子径が０．３μｍになるまで、湿式粉砕して、粉砕スラリーを得た。この粉砕スラリーの粘度は７８０ｍＰａ・ｓ、固形分濃度は３５重量％であった。 [Example 9] (Comparative Example)
103.48 g of cobalt hydroxide having a cobalt content of 62.3% by weight, 0.87 g of aluminum hydroxide having an aluminum content of 34.55% by weight, 0.65 g of magnesium hydroxide having a magnesium content of 41.64% by weight, Were mixed, and water was added and stirred to obtain 300 g of a slurry. Subsequently, each raw material particle dispersed in the slurry was wet-pulverized using a circulating medium agitation type wet bead mill until the average particle diameter became 0.3 μm, thereby obtaining a pulverized slurry. The pulverized slurry had a viscosity of 780 mPa · s and a solid content concentration of 35% by weight.
　例１と同様の操作を行って、水酸化コバルトからなる造粒体粉末を得た。前記の造粒体粉末を、ＳＥＭで観察したところ、０．０２～３μｍの粒子が凝集した二次粒子を形成していることがわかった。また、共沈粒子の一次粒子の平均粒子径は０．５２μｍであった。また二次粒子の平均粒子径は１５．３μｍであり、Ｄ１０は５．４μｍ、Ｄ９０は３２．５μｍであった。また、造粒体粉末の気孔率は６８％、平均細孔径は０．１７μｍ、アスペクト比は１．２２、安息角は６２°であり、コバルト、アルミニウム及びマグネシウムを合計した含量が６０．４重量％であった。さらに前記の造粒体粉末３０ｇを、リチウム含量１８．７重量％の炭酸リチウム１１．５ｇとを混合して、得られたリチウム混合粉末を酸素含有雰囲気下１０３０℃で１５時間焼成した。その後、粉砕してＬｉＣｏ０．９８Ａｌ０．０１Ｍｇ０．０１Ｏ２の組成を有するリチウム含有複合酸化物粉末を得た。 The same operation as in Example 1 was performed to obtain a granulated powder composed of cobalt hydroxide. When the granulated powder was observed with an SEM, it was found that secondary particles in which 0.02 to 3 μm particles were aggregated were formed. The average particle diameter of the primary particles of the coprecipitated particles was 0.52 μm. The average particle diameter of the secondary particles was 15.3 μm, D10 was 5.4 μm, and D90 was 32.5 μm. The granulated powder has a porosity of 68%, an average pore diameter of 0.17 μm, an aspect ratio of 1.22, an angle of repose of 62 °, and a total content of cobalt, aluminum and magnesium of 60.4 wt. %Met. Further, 30 g of the granulated powder was mixed with 11.5 g of lithium carbonate having a lithium content of 18.7% by weight, and the obtained lithium mixed powder was fired at 1030 ° C. for 15 hours in an oxygen-containing atmosphere. Then, to obtain a lithium-containing composite oxide powder having a composition of LiCo 0.98 Al 0.01 Mg 0.01 O 2 was pulverized.
　得られたリチウム含有複合酸化物の粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ　２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６５．１±１°の（１１０）面の回折ピークの積分幅は０．１１９°であった。この粉末を０．３２トン／ｃｍ２の圧力でプレスしたときのプレス密度は３．０６ｇ／ｃｍ３であった。 With respect to the obtained powder of lithium-containing composite oxide, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα rays, the integral width of the diffraction peak on the (110) plane at 2θ = 65.1 ± 1 ° was 0.119 °. When this powder was pressed at a pressure of 0.32 ton / cm 2 , the press density was 3.06 g / cm 3 .
　また、平均粒子径は１３．３μｍ、Ｄ１０は５．３μｍ、Ｄ９０は２８．５μｍであった。また、このリチウム含有複合酸化物粉末について、ジルコニウムの含量を測定したところ、１５０ｐｐｍのジルコニウムが不純物として混入していることが確認できた。これはメディアとしてビーズミルに含まれるジルコニウムが不純物として混入したためと考えられる。比表面積は０．５４ｍ２／ｇであった。２５℃、２．５～４．３Ｖにおける正極の初期重量容量密度は、１５８ｍＡｈ／ｇであり、体積容量密度は４８３ｍＡｈ／ｃｍ３であった。３０回充放電サイクル後の容量維持率は９５．２％であった。また、発熱曲線の発熱開始温度は１５８℃であった。 The average particle size was 13.3 μm, D10 was 5.3 μm, and D90 was 28.5 μm. Further, when the zirconium content of this lithium-containing composite oxide powder was measured, it was confirmed that 150 ppm of zirconium was mixed as an impurity. This is probably because zirconium contained in the bead mill as a medium was mixed as an impurity. The specific surface area was 0.54 m 2 / g. The initial weight capacity density of the positive electrode at 25 ° C. and 2.5 to 4.3 V was 158 mAh / g, and the volume capacity density was 483 mAh / cm 3 . The capacity retention rate after 30 charge / discharge cycles was 95.2%. The heat generation start temperature of the heat generation curve was 158 ° C.
［例１０］（比較例）
　コバルト含量が６２．３重量％の水酸化コバルト４０．３０ｇと、ニッケル含量が７８．２重量％の酸化ニッケル（ＮｉＯ）３１．９７ｇと、マンガン含量が７１．５重量％の酸化マンガン（Ｍｎ３Ｏ４）３２．７３ｇに、水を混合して攪拌し３００ｇのスラリーとした。次いで、循環式媒体攪拌型湿式ビーズミルを用いて、このスラリーに分散する各原料粒子を、平均粒子径が０．３μｍになるまで、湿式粉砕して、粉砕スラリーを得た。 [Example 10] (Comparative Example)
40.30 g of cobalt hydroxide having a cobalt content of 62.3 wt%, 31.97 g of nickel oxide (NiO) having a nickel content of 78.2 wt%, manganese oxide having a manganese content of 71.5 wt% (Mn 3 Water was mixed with 32.73 g of O 4 ) and stirred to obtain a 300 g slurry. Subsequently, each raw material particle dispersed in the slurry was wet-pulverized using a circulating medium agitation type wet bead mill until the average particle diameter became 0.3 μm, thereby obtaining a pulverized slurry.
　この粉砕スラリーの粘度は９００ｍＰａ・ｓ、スラリーを分取して、１００℃で乾燥して測定した固形分濃度は３５重量％であった。
　この粉砕スラリーを例１と同様の操作を行ってコバルト、ニッケル、マンガンを含む造粒体を得た。得られた造粒体粉末を、ＳＥＭで観察したところ、０．０２～３μｍの一次粒子が凝集した二次粒子を形成していることがわかった。また、共沈粒子の一次粒子の平均粒子径は０．５９μｍであった。また二次粒子の平均粒子径は１５．５μｍであり、Ｄ１０は５．１μｍ、Ｄ９０は４５．５μｍであった。また、造粒体粉末の気孔率は７３％、平均細孔径は０．２１μｍ、アスペクト比は１．２２、安息角は６３°であり、ニッケル、コバルト及びマンガンの合計の含量は６０．４重量％だった。 The viscosity of this pulverized slurry was 900 mPa · s, and the solid content concentration measured by separating the slurry and drying it at 100 ° C. was 35% by weight.
This pulverized slurry was subjected to the same operation as in Example 1 to obtain a granulated body containing cobalt, nickel and manganese. When the obtained granulated powder was observed with an SEM, it was found that secondary particles in which primary particles of 0.02 to 3 μm were aggregated were formed. Moreover, the average particle diameter of the primary particles of the coprecipitated particles was 0.59 μm. The average particle diameter of the secondary particles was 15.5 μm, D10 was 5.1 μm, and D90 was 45.5 μm. The granulated powder has a porosity of 73%, an average pore diameter of 0.21 μm, an aspect ratio of 1.22, an angle of repose of 63 °, and a total content of nickel, cobalt and manganese of 60.4 wt. %was.
　さらに前記の造粒体粉末２０ｇを、リチウム含量１８．７重量％の炭酸リチウム８．５６ｇとを混合して、得られた混合物粉末を酸素含有雰囲気下１０００℃で１６時間焼成した。その後、粉砕してＬｉ１．０４７５Ｎｉ０．３１７５Ｃｏ０．３１７５Ｍｎ０．３１７５Ｏ２の組成を有するリチウム含有複合酸化物粉末を得た。 Furthermore, 20 g of the granulated powder was mixed with 8.56 g of lithium carbonate having a lithium content of 18.7% by weight, and the resulting mixture powder was fired at 1000 ° C. for 16 hours in an oxygen-containing atmosphere. Then, to obtain a lithium-containing composite oxide powder having a composition of Li 1.0475 Ni 0.3175 Co 0.3175 Mn 0.3175 O 2 was pulverized.
　得られたリチウム含有複合酸化物の粉末について、例１と同様の操作を行って評価した。（１１０）面の回折ピーク半値幅は０．１９５°でありプレス密度は２．７０ｇ／ｃｍ３であった。また、得られたリチウム含有複合酸化物粉末を、ＳＥＭで観察したところ、０．５～３μｍの一次粒子が凝集して略球状の二次粒子を形成していることがわかった。平均粒子径は１４．３μｍ、Ｄ１０は５．３μｍ、Ｄ９０は３０．３μｍであった。また、このリチウム含有複合酸化物粉末について、ジルコニウムの含量を測定したところ、２００ｐｐｍのジルコニウムが不純物として混入していることが確認できた。これはメディアとしてビーズミルに含まれるジルコニウムが不純物として混入したためと考えられる。また、比表面積は０．６６ｍ２／ｇであり、正極の初期重量容量密度は、１５１ｍＡｈ／ｇであり、容量維持率は９４．５％であり、体積容量密度は４０８ｍＡｈ／ｃｍ３であり、発熱開始温度は２２５℃であった。 The obtained lithium-containing composite oxide powder was evaluated in the same manner as in Example 1. The (110) plane had a diffraction peak half width of 0.195 ° and a press density of 2.70 g / cm 3 . Further, when the obtained lithium-containing composite oxide powder was observed with an SEM, it was found that primary particles of 0.5 to 3 μm aggregated to form substantially spherical secondary particles. The average particle size was 14.3 μm, D10 was 5.3 μm, and D90 was 30.3 μm. Further, when the zirconium content of this lithium-containing composite oxide powder was measured, it was confirmed that 200 ppm of zirconium was mixed as an impurity. This is probably because zirconium contained in the bead mill as a medium was mixed as an impurity. The specific surface area is 0.66 m 2 / g, the initial weight capacity density of the positive electrode is 151 mAh / g, the capacity retention is 94.5%, and the volume capacity density is 408 mAh / cm 3 . The heat generation starting temperature was 225 ° C.
　本発明によれば、体積容量密度、充填密度及び安全性が高く、充放電サイクル耐久性に優れたリチウムイオン二次電池正極活物質用の原料として有用な造粒体粉末の製造方法と、該製造方法によって得られたリチウム含有複合酸化物の製造方法と、該製造方法によって得られたリチウム含有複合酸化物を含むリチウムイオン二次電池用正極及びリチウムイオン二次電池を提供できる。

　なお、２００８年２月６日に出願された日本特許出願２００８－０２７０２０号の明細書、特許請求の範囲、図面及び要約書の全内容をここに引用し、本発明の明細書の開示として、取り入れるものである。 According to the present invention, a method for producing a granulated powder useful as a raw material for a lithium ion secondary battery positive electrode active material having high volumetric capacity density, filling density and safety, and excellent charge / discharge cycle durability, There can be provided a method for producing a lithium-containing composite oxide obtained by the production method, a positive electrode for a lithium ion secondary battery and a lithium ion secondary battery comprising the lithium-containing composite oxide obtained by the production method.

It should be noted that the entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2008-027020 filed on February 6, 2008 are cited herein as disclosure of the specification of the present invention. Incorporated.

Claims (16)

  1. 　Ｎ元素（Ｎは、Ｃｏ、Ｍｎ及びＮｉからなる群から選ばれる少なくとも１種の元素である）及びＭ元素（Ｍは、Ｎ元素以外の遷移金属元素、Ａｌ、Ｓｎ、Ｚｎ及びアルカリ土類金属元素からなる群から選ばれる少なくとも１種の元素である）が少なくとも溶解した水溶液とアルカリ水溶液とを混合して、ｐＨを９～１４の範囲に調節することにより、Ｎ元素及びＭ元素を含む共沈粒子を析出させ、該共沈粒子が分散する共沈スラリーを得る工程１と；前記共沈スラリーを脱塩処理せしめて脱塩スラリーを得る工程２と；前記脱塩スラリーを噴霧乾燥してＮ元素及びＭ元素を含有する実質上球状の造粒体粉末を得る工程３とを、この順番で含むことを特徴とするリチウムイオン二次電池正極活物質用の造粒体粉末の製造方法。 N element (N is at least one element selected from the group consisting of Co, Mn and Ni) and M element (M is a transition metal element other than N element, Al, Sn, Zn and alkaline earth metal) An aqueous solution in which at least one element selected from the group consisting of elements is dissolved and an alkaline aqueous solution are mixed and the pH is adjusted to a range of 9 to 14, whereby the elements including N element and M element are mixed. Step 1 for precipitating precipitated particles and obtaining a coprecipitation slurry in which the coprecipitation particles are dispersed; Step 2 for obtaining a desalination slurry by subjecting the coprecipitation slurry to desalination; and spray drying the desalination slurry. And a step 3 of obtaining a substantially spherical granulated powder containing an N element and an M element in this order.
  2. 　工程１で得られる共沈スラリー中に分散する共沈粒子の一次粒子の平均粒子径が０．０１～３μｍである請求項１に記載の造粒体粉末の製造方法。 The method for producing a granulated powder according to claim 1, wherein the primary particles of the coprecipitated particles dispersed in the coprecipitation slurry obtained in step 1 have an average particle diameter of 0.01 to 3 µm.
  3. 　共沈スラリーの固形分濃度が１０重量％のときに、工程２の脱塩処理で排出されるイオン含有水の伝導度が１００μＳ／ｃｍ以下である請求項１に記載の造粒体粉末の製造方法。 The granulated powder according to claim 1, wherein the conductivity of the ion-containing water discharged by the desalting treatment in step 2 is 100 µS / cm or less when the solid content concentration of the coprecipitation slurry is 10 wt%. Method.
  4. 　工程３で噴霧乾燥に用いる脱塩スラリーの固形分濃度が１０重量％以上であり、脱塩スラリーの粘度が２～１０００ｍＰａ・ｓである請求項１～３のいずれかに記載の造粒体粉末の製造方法。 The granulated powder according to any one of claims 1 to 3, wherein the desalting slurry used for spray drying in step 3 has a solid content concentration of 10 wt% or more and the desalting slurry has a viscosity of 2 to 1000 mPa · s. Manufacturing method.
  5. 　工程３で得られる造粒体粉末の平均粒子径（Ｄ５０）が１０～４０μｍである請求項１～４のいずれかに記載の造粒体粉末の製造方法。 The method for producing a granulated powder according to any one of claims 1 to 4, wherein the average particle diameter (D50) of the granulated powder obtained in Step 3 is 10 to 40 µm.
  6. 　工程３で得られる造粒体粉末の気孔率が６０％以上である請求項１～５のいずれかに記載の造粒体粉末の製造方法。 6. The method for producing a granulated powder according to claim 1, wherein the porosity of the granulated powder obtained in step 3 is 60% or more.
  7. 　工程３で得られる造粒体粉末の平均細孔径が１μｍ以下である請求項１～６のいずれかに記載の造粒体粉末の製造方法。 The method for producing a granulated powder according to any one of claims 1 to 6, wherein the average pore diameter of the granulated powder obtained in step 3 is 1 µm or less.
  8. 　工程３で得られる造粒体粉末のアスペクト比が１．２以下である請求項１～７のいずれかに記載の造粒体粉末の製造方法。 The method for producing a granulated powder according to any one of claims 1 to 7, wherein an aspect ratio of the granulated powder obtained in step 3 is 1.2 or less.
  9. 　工程３で得られる造粒体粉末の安息角が６０°以下である請求項１～８のいずれかに記載の造粒体粉末の製造方法。 The method for producing a granulated powder according to any one of claims 1 to 8, wherein the angle of repose of the granulated powder obtained in step 3 is 60 ° or less.
  10. 　工程３で得られる造粒体粉末のＤ１０が３～１２μｍである請求項１～９のいずれかに記載の造粒体粉末の製造方法。 10. The method for producing a granulated powder according to claim 1, wherein D10 of the granulated powder obtained in step 3 is 3 to 12 μm.
  11. 　工程３で得られる造粒体粉末のＤ９０が７０μｍ以下である請求項１～１０のいずれかに記載の造粒体粉末の製造方法。 The method for producing a granulated powder according to any one of claims 1 to 10, wherein D90 of the granulated powder obtained in Step 3 is 70 µm or less.
  12. 　Ｎ元素がＣｏである請求項１～１１のいずれかに記載の造粒体粉末の製造方法。 The method for producing a granulated powder according to any one of claims 1 to 11, wherein the N element is Co.
  13. 　請求項１～１２のいずれかに記載の造粒体粉末の製造方法で得られた造粒体粉末と、リチウム化合物粉末とを混合した後、酸素含有雰囲気において６００～１１００℃で焼成するリチウムイオン二次電池正極活物質用のリチウム含有複合酸化物の製造方法。 Lithium ions which are calcined at 600 to 1100 ° C in an oxygen-containing atmosphere after mixing the granulated powder obtained by the method for producing a granulated powder according to any one of claims 1 to 12 and a lithium compound powder The manufacturing method of the lithium containing complex oxide for secondary battery positive electrode active materials.
  14. 　リチウム含有複合酸化物が、一般式ＬｉｐＮｘＭｙＯｚ（但し、Ｎは、Ｃｏ、Ｍｎ及びＮｉからなる群から選ばれる少なくとも１種の元素である。Ｍは、Ｎ元素以外の遷移金属元素、Ａｌ、Ｓｎ、Ｚｎ及びアルカリイオン土類金属元素からなる群から選ばれる少なくとも１種の元素である。０．９≦ｐ≦１．５、０．９６≦ｘ＜２．００、０＜ｙ≦０．０４、１．９≦ｚ≦４．２）で表される請求項１３に記載のリチウム含有複合酸化物の製造方法。 The lithium-containing composite oxide has the general formula Li p N x M y O z (where N is at least one element selected from the group consisting of Co, Mn and Ni. M is a transition other than the N element) It is at least one element selected from the group consisting of metal elements, Al, Sn, Zn, and alkali ion earth metal elements: 0.9 ≦ p ≦ 1.5, 0.96 ≦ x <2.00, 0 The method for producing a lithium-containing composite oxide according to claim 13, represented by <y ≦ 0.04, 1.9 ≦ z ≦ 4.2).
  15. 　請求項１３又は１４に記載の製造方法により得られるリチウム含有複合酸化物を含む正極活物質と導電材とバインダーとを含むリチウムイオン二次電池用正極。 The positive electrode for lithium ion secondary batteries containing the positive electrode active material containing the lithium containing complex oxide obtained by the manufacturing method of Claim 13 or 14, a electrically conductive material, and a binder.
  16. 　正極、負極、非水電解質及び電解液を含み、かつ該正極が請求項１５に記載のリチウムイオン二次電池用正極であるリチウムイオン二次電池。 A lithium ion secondary battery comprising a positive electrode, a negative electrode, a nonaqueous electrolyte, and an electrolytic solution, wherein the positive electrode is a positive electrode for a lithium ion secondary battery according to claim 15.
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JP2012004097A (en) * 2010-06-13 2012-01-05 Samsung Sdi Co Ltd Positive electrode active material precursor for lithium secondary battery, positive electrode active material prepared using the same, and lithium secondary battery including positive electrode active material
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JP2017520506A (en) * 2014-05-16 2017-07-27 厦門厦▲う▼新能源材料有限公司 Multi-component complex oxide material, production method and use thereof
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