WO2017164237A1 - Positive-electrode active material for non-aqueous-electrolyte secondary cell and method for manufacturing same, positive-electrode material paste for non-aqueous-electrolyte secondary cell, and non-aqueous-electrolyte secondary cell - Google Patents
Positive-electrode active material for non-aqueous-electrolyte secondary cell and method for manufacturing same, positive-electrode material paste for non-aqueous-electrolyte secondary cell, and non-aqueous-electrolyte secondary cell Download PDFInfo
- Publication number
- WO2017164237A1 WO2017164237A1 PCT/JP2017/011450 JP2017011450W WO2017164237A1 WO 2017164237 A1 WO2017164237 A1 WO 2017164237A1 JP 2017011450 W JP2017011450 W JP 2017011450W WO 2017164237 A1 WO2017164237 A1 WO 2017164237A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- positive electrode
- active material
- electrode active
- electrolyte secondary
- aqueous electrolyte
- Prior art date
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the present invention relates to a positive electrode active material for a non-aqueous electrolyte secondary battery and a method for producing the same, a positive electrode mixture paste for a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery.
- a non-aqueous electrolyte secondary battery can be cited, and a lithium ion secondary battery can be cited as a typical non-aqueous electrolyte secondary battery.
- a lithium ion secondary battery is composed of a negative electrode, a positive electrode, an electrolyte, and the like, and an active material for the negative electrode and the positive electrode is made of a material that can desorb and insert lithium.
- Lithium ion secondary batteries are currently being actively researched and developed. Among them, lithium ion secondary batteries using a layered or spinel type lithium metal composite oxide as a positive electrode material have a high 4V class. Since a voltage can be obtained, the practical application is progressing as a battery having a high energy density.
- lithium cobalt composite oxide LiCoO 2
- lithium metal composite oxide LiNiO 2
- lithium nickel cobalt manganese composite oxide LiNi 1/3 Co 1/3 Mn 1/3 O 2
- lithium manganese composite oxide LiMn 2 O 4
- it is effective to contain lithium in excess of the stoichiometric composition with respect to metal elements such as nickel, cobalt, and manganese.
- the positive electrode of the nonaqueous electrolyte secondary battery is, for example, a positive electrode obtained by mixing a positive electrode active material, a binder such as polyvinylidene fluoride (PVDF), and a solvent such as normal methyl-2-pyrrolidone (NMP). It is formed by applying a composite paste to a current collector such as an aluminum foil. At this time, lithium liberated from the positive electrode active material in the positive electrode mixture paste may react with moisture contained in the binder to generate lithium hydroxide. The generated lithium hydroxide and the binder may react to cause gelation of the positive electrode mixture paste. Gelation of the positive electrode mixture paste causes poor operability and yield. This tendency becomes remarkable when the lithium in the positive electrode active material is in excess of the stoichiometric ratio and the ratio of nickel is high.
- PVDF polyvinylidene fluoride
- NMP normal methyl-2-pyrrolidone
- Patent Document 1 discloses Li x Ni 1-y A y O 2 (0.98 ⁇ x ⁇ 1.06, 0.05 ⁇ y ⁇ 0.30, A is at least one of Co and Al).
- the positive electrode active material for a non-aqueous electrolyte secondary battery in which 5 g is stirred and mixed in 100 g of pure water for 120 minutes and then left to stand for 30 seconds, and the pH of the supernatant is 12.7 or less at 25 ° C. has been proposed. It is described that this positive electrode active material has fluidity and excellent gelation resistance even after 24 hours have passed since the slurry (positive electrode mixture paste) was produced.
- Patent Document 2 proposes a positive electrode composition for a non-aqueous electrolyte secondary battery including a positive electrode active material composed of a lithium transition metal composite oxide and additive particles composed of particles composed of acidic oxide particles. Yes.
- a positive electrode active material composed of a lithium transition metal composite oxide
- additive particles composed of particles composed of acidic oxide particles.
- lithium hydroxide generated by reacting with moisture contained in the binder preferentially reacts with the acidic oxide, suppressing the reaction between the generated lithium hydroxide and the binder, It is described that gelation is suppressed.
- the acidic oxide plays a role as a conductive agent in the positive electrode, lowers the resistance of the whole positive electrode, and contributes to the improvement of the output characteristics of the battery.
- Patent Document 3 also provides a lithium transition metal oxide containing LiOH outside the composition as the positive electrode active material; grasping the molar amount P of LiOH contained per gram of the positive electrode active material; Prepare 0.05 mol or more of tungsten oxide in terms of tungsten atom per mol of LiOH with respect to the amount P; and knead the positive electrode active material and tungsten oxide together with the conductive material and the binder in an organic solvent.
- a method for producing a lithium ion secondary battery has been proposed.
- the positive electrode active material is excellent in output characteristics and charge / discharge cycle characteristics by being composed of particles having a small particle size and a narrow particle size distribution. This is because particles having a small particle size have a large specific surface area, and when used as a positive electrode active material, a sufficient reaction area with the electrolytic solution can be secured, and the positive electrode is made thin, This is because the movement distance between the positive electrode and the negative electrode can be shortened, so that the positive electrode resistance can be reduced.
- the particles having a narrow particle size distribution can equalize the voltage applied to the particles in the electrode, and therefore it is possible to suppress a decrease in battery capacity due to the selective deterioration of the fine particles.
- the positive electrode active material In order to further improve the output characteristics and charge / discharge cycle characteristics, for example, it has been reported that it is effective to make the positive electrode active material have a hollow structure. Since such a positive electrode active material can increase the reaction area with the electrolyte compared to a solid positive electrode active material having the same particle size, the positive electrode resistance can be greatly reduced. .
- transition metal composite hydroxide particles serving as a precursor of a positive electrode active material are mainly divided into two stages: a nucleation process for mainly nucleation and a particle growth process for mainly particle growth.
- a method for producing by a crystallized reaction clearly separated.
- the pH value of the aqueous reaction solution is adjusted to a particle temperature within a range of 12 or more (for example, 12.0 to 13.4 or 12.0 to 14.0) in the nucleation step, based on a liquid temperature of 25 ° C. In the process, it is controlled to be lower than the nucleation process and 12 or less (for example, 10.5 to 12.0).
- the reaction atmosphere is an oxidizing atmosphere at the initial stage of the nucleation step and the particle growth step, and is switched to a non-oxidizing atmosphere at a predetermined timing.
- the obtained transition metal composite hydroxide particles have a small particle size, a narrow particle size distribution, a low-density central portion composed of fine primary particles, and a high density composed of plate-like or needle-like primary particles. And the outer shell. Therefore, when such transition metal composite hydroxide particles are fired, the low density center portion is greatly contracted, and a space portion is formed inside.
- the particle properties of the composite hydroxide particles are inherited by the positive electrode active material. It is said that secondary batteries using these positive electrode active materials can improve capacity characteristics, output characteristics, and charge / discharge cycle characteristics.
- Patent Document 6 discloses an alkaline solution in which a tungsten compound is dissolved in a lithium metal composite oxide powder composed of primary particles and secondary particles formed by aggregation of the primary particles. Adding and mixing the first step of dispersing W on the surface of the lithium metal composite oxide powder or the primary particles of the powder, the alkali solution in which the mixed tungsten compound is dissolved, and the lithium metal composite A positive electrode for a non-aqueous electrolyte secondary battery comprising a second step of forming fine particles containing W and Li on the surface of the lithium metal composite oxide powder or the surface of primary particles of the powder by heat-treating the oxide powder. A method for producing an active material has been proposed.
- the proposal of the above-mentioned Patent Document 1 merely provides a condition that allows a positive electrode active material for a lithium secondary battery that is stable for a long time in a slurry (positive electrode mixture paste) to be practically determined. It is insufficient as a measure for suppressing gelation of the composite paste. Moreover, in the proposal of the above-mentioned patent document 2, there is a fear that the separator is damaged and the safety is lowered due to the remaining acidic oxide particles. Moreover, it cannot be said that gelation suppression is sufficient. Further, even in the proposal of the above-mentioned Patent Document 3, it cannot be said that the problem regarding the breakage of the separator due to the remaining acidic oxide (for example, tungsten oxide) and the suppression of gelation are not solved.
- the remaining acidic oxide for example, tungsten oxide
- Patent Document 4 and Patent Document 5 above when the reaction area with the electrolyte is increased in order to improve output characteristics and charge / discharge cycle characteristics, gelation of the positive electrode mixture paste is promoted. New problems may arise. Furthermore, in the proposal of the above-mentioned Patent Document 6, although the output characteristics have been studied, no study has been made on the gelation suppression of the positive electrode mixture paste. Therefore, although some of the above proposals have been examined with regard to the suppression of gelation of the positive electrode mixture paste and the improvement of battery characteristics, it cannot be said that the problem has been sufficiently solved.
- the present invention improves the stability of the positive electrode mixture paste when producing a non-aqueous electrolyte secondary battery, and satisfies the output characteristics and cycle characteristics when the secondary battery is configured. It aims at providing the positive electrode active material for nonaqueous electrolyte secondary batteries which can improve discharge capacity simultaneously, and its manufacturing method. Another object of the present invention is to provide a positive electrode mixture paste using such a positive electrode active material and a non-aqueous electrolyte secondary battery.
- the present inventor has intensively studied on the gelation suppression and output characteristics of the positive electrode mixture paste for the non-aqueous electrolyte secondary battery.
- the present inventors used the positive electrode mixture paste as a positive electrode active material.
- the lithium metal composite oxide is greatly influenced by the pH of the lithium metal composite oxide and the form of the compound in which excess lithium is formed on the surface of the lithium metal composite oxide particles. It was found that the pH can be controlled and the reaction resistance of the positive electrode active material can be reduced to improve the output characteristics.
- the present invention was completed by obtaining the knowledge that the form of the compound formed by excess lithium can be controlled by mixing and drying water in the lithium metal composite oxide.
- the method comprises mixing a fired powder made of a lithium metal composite oxide having a layered crystal structure and water, and drying the mixture obtained by the mixing.
- baking powder formula (1): Li s Ni 1 -x-y-z Co x Mn y M 1 z O 2 ( however, 0.05 ⁇ x ⁇ 0.35,0 ⁇ y ⁇ 0.35 , 0 ⁇ z ⁇ 0.10, 0.95 ⁇ s ⁇ 1.50
- M 1 is represented by at least one element selected from V, Mg, Mo, Nb, Ti, W and Al), and primary
- the secondary particles formed by agglomeration of the particles contain water, and 5 g of the obtained positive electrode active material is dispersed in 100 ml of pure water, and the pH at 25 ° C. when measuring the supernatant after standing for 10 minutes is 25 ° C.
- the water when mixing the calcined powder and water, it is preferable to add the water by spraying it to a droplet size of 1 to 2000 ⁇ m. Moreover, it is preferable to mix water in the range of 1 mass% or more and 35 mass% or less with respect to baked powder. Moreover, it is preferable to mix water in the range of 0.003 g / m 2 or more and 0.025 g / m 2 or less with respect to the surface area of the fired powder. Moreover, it is preferable to mix water in 1 mass% or more and 6 mass% or less with respect to baked powder.
- the fired powder preferably has an average particle size in the range of 3 ⁇ m to 15 ⁇ m, and [(d90 ⁇ d10) / average particle size], which is an index indicating the spread of the particle size distribution, is 0.7 or less.
- gap measured by cross-sectional observation occupies is 4.5% or more and 60% or less with respect to the whole cross-sectional area of baked powder.
- the firing powder has the general formula (2): Li s Ni 1 -x-y-z-t Co x Mn y M 2 z W t O 2 ( however, 0.05 ⁇ x ⁇ 0.35,0 ⁇ y ⁇ 0.35, 0 ⁇ z ⁇ 0.10, 0.95 ⁇ s ⁇ 1.50, 0.0001 ⁇ t ⁇ 0.03, 0.0001 ⁇ z + t ⁇ 0.10, M 2 is V, It is preferably represented by at least one element selected from Mg, Mo, Nb, Ti and Al.
- a positive electrode active material for a non-aqueous electrolyte secondary battery comprising a lithium metal composite oxide powder having a layered crystal structure, wherein the lithium metal composite oxide powder has the general formula Li s.
- M 1 is represented by at least one element selected from V, Mg, Mo, Nb, Ti, W and Al), and includes secondary particles formed by aggregation of primary particles
- 5 g of the positive electrode active material is dispersed in 100 ml of pure water, and the pH at 25 ° C.
- the positive electrode active material for a non-aqueous electrolyte secondary battery is provided.
- the positive electrode active material preferably has a ratio of the amount of excess LiOH to excess Li 2 CO 3 of 0.3 or less. Further, the ratio of the amount of surplus LiOH and surplus Li 2 CO 3 is 0.18 or more, and the amount of surplus Li 2 CO 3 is 0.157 ⁇ 10 ⁇ 2 g / m 2 with respect to the surface area of the positive electrode active material. The following is preferable.
- the positive electrode active material has an average particle size in the range of 3 ⁇ m or more and 15 ⁇ m or less, and [(d90 ⁇ d10) / average particle size], which is an index indicating the spread of the particle size distribution, is 0.7 or less. preferable.
- gap which is measured in the cross-sectional observation of lithium metal complex oxide powder occupies 4.5% or more and 60% or less with respect to the cross-sectional area of this lithium metal complex oxide particle whole.
- the lithium metal composite oxide powder represented by the general formula Li s Ni 1-x-y -z-t Co x Mn y M 2 z W t O 2 ( however, 0.05 ⁇ x ⁇ 0.35,0 ⁇ y ⁇ 0.35, 0 ⁇ z ⁇ 0.10, 0.95 ⁇ ⁇ s ⁇ 1.50, 0.0001 ⁇ t ⁇ 0.03, 0.0001 ⁇ z + t ⁇ 0.10, M 2 is V And at least one element selected from Mg, Mo, Nb, Ti and Al.
- the positive electrode mixture paste for a non-aqueous electrolyte secondary battery includes the positive electrode active material for a non-aqueous electrolyte secondary battery.
- a non-aqueous electrolyte secondary battery has a positive electrode containing the positive electrode active material for a non-aqueous electrolyte secondary battery.
- a positive electrode mixture slurry with high gel stability and high stability is obtained, and excellent output characteristics and cycle characteristics when used for a positive electrode material of a battery, and excellent charge / discharge capacity, It is possible to provide a positive electrode active material for a non-aqueous electrolyte secondary battery. Furthermore, the manufacturing method is easy and suitable for production on an industrial scale, and its industrial value is extremely large.
- FIG. 1 is a figure showing an example of a manufacturing method of a cathode active material for nonaqueous system electrolyte rechargeable batteries of an embodiment.
- FIG. 2 is a schematic explanatory diagram of an impedance evaluation measurement example and an equivalent circuit used for analysis.
- FIG. 3 is a schematic cross-sectional view of a coin-type battery used for battery evaluation.
- FIG. 4 is a schematic explanatory diagram of a laminate cell used for battery evaluation.
- FIG. 5 is an example of a measurement result of ⁇ V by the current pause method used for low-temperature output evaluation.
- Positive electrode active material for non-aqueous electrolyte secondary battery The non-aqueous electrolyte positive electrode active material of the present embodiment (hereinafter also referred to as “positive electrode active material”) is a lithium metal composite oxide powder having a layered crystal structure.
- the lithium metal composite oxide powder has the general formula (1): Li s Ni 1-xyZ Co x Mn y M 1 z O 2 ( However, 0.05 ⁇ x ⁇ 0.35, 0 ⁇ y ⁇ 0.35, 0 ⁇ z ⁇ 0.10, 0.95 ⁇ s ⁇ 1.50, M 1 is V, Mg, Mo, Nb, And at least one element selected from Ti, W, and Al), and includes secondary particles formed by aggregation of primary particles. Further, 5 g of the positive electrode active material is dispersed in 100 ml of pure water, and the pH at 25 ° C. when measuring the supernatant after standing for 10 minutes is 11 to 11.9, and excess LiOH determined by titration And the mass of surplus Li 2 CO 3 (surplus LiOH / surplus Li 2 CO 3 ) is 0.45 or less.
- s represents the atomic ratio of Li to the total of Ni, Co, Mn and M 1 in the lithium metal composite oxide powder (Li / Me), and production of the lithium metal composite oxide powder The amount of Li added in the process is reflected.
- s satisfies 0.95 ⁇ s ⁇ 1.50, and preferably satisfies 1.00 ⁇ s ⁇ 1.30.
- the amount of Li is in the range of s, the battery capacity and output characteristics of the lithium metal composite oxide itself can be improved.
- Composite oxide powder obtained by a normal production method (for example, lithium nickel composite oxide powder obtained by firing nickel composite hydroxide or nickel composite oxide and lithium compound) is a secondary particle.
- unreacted lithium compounds (surplus lithium compounds) exist on the surfaces of the primary particles.
- the surplus lithium compound may elute in the positive electrode mixture paste (hereinafter also referred to as “paste”) to raise the pH and cause the paste to gel. It is also conceivable that excess lithium is present inside the lithium metal composite oxide powder and is eluted into the paste to cause the paste to gel.
- the present inventors consider that it is important to suppress elution of excess lithium into the paste, and unreacted particles present on the surfaces of secondary particles and primary particles. We focused on the form of the lithium compound.
- surplus lithium compound existing on the surfaces of the secondary particles and the primary particles examples include unreacted LiOH (surplus LiOH) and unreacted Li 2 CO 3 (surplus Li 2 CO 3 ).
- Recess LiOH easily elutes into the paste and raises the pH of the paste to promote gelation.
- excessive lithium (Li) in the composite oxide powder may elute into the paste to form LiOH and raise the pH of the paste to cause gelation.
- surplus LiOH refers to a lithium source that can be in the form of LiOH during paste preparation, and includes secondary particles, unreacted LiOH on the surface of the primary particles, excess lithium inside the composite oxide powder, and the like.
- surplus Li 2 CO 3 is less likely to elute into the paste than LiOH and has a small effect of gelling the paste.
- the present inventors convert surplus LiOH into Li 2 CO 3 and immobilize it as surplus Li 2 CO 3 , thereby reducing elution of LiOH into the paste and suppressing paste gelation.
- the present invention has been completed on the basis of a novel idea that it may be possible. That is, the positive electrode active material of this embodiment has a mass ratio (LiOH / Li 2 CO 3 ) of surplus LiOH and surplus Li 2 CO 3 determined by a titration method of 0.45 or less, preferably 0.3. It is as follows.
- reaction resistance of the positive electrode active material (hereinafter referred to as “positive electrode resistance”) ) Can be brought into a lower state, exhibiting better output and cycle characteristics and higher initial charge / discharge capacity.
- the positive electrode active material of the present embodiment exhibits excellent characteristics not only at room temperature but also at a low temperature (eg, ⁇ 20 ° C.).
- the lower limit of LiOH / Li 2 CO 3 is preferably 0.10 or more, and more preferably 0.18 or more.
- the surface of the primary particle means not only the surface of the primary particle exposed on the outer surface of the secondary particle, but also the space near and inside the surface of the secondary particle through which the electrolyte can penetrate through the outside of the secondary particle. It also includes the surface of the primary particles exposed to the surface. Furthermore, even if it is a grain boundary between primary particles, if the primary particle bonding is incomplete and the electrolyte solution can permeate, it is included in the primary particle surface.
- excess LiOH present on the surface of the primary particles inhibits Li movement between the complex oxide crystal and the electrolytic solution. Therefore, by converting excess LiOH to excess Li 2 CO 3 and immobilizing it on the primary particle surface, by reducing the amount of excess LiOH, excess LiOH present on the primary surface or secondary particle surface is removed, and Li Is not hindered, and the charge / discharge capacity (hereinafter also referred to as “battery capacity”) when used in a battery can be improved.
- excess LiOH present on the primary particle surface is fixed as excess Li 2 CO 3 , it is once removed from the primary particle surface and eluted in the added water, and then as excess Li 2 CO 3 as the primary Li 2 CO 3. It is thought that it aggregates on the particle surface. Therefore, the area of the surplus lithium compound (including surplus LiOH and surplus Li 2 CO 3 ) that covers the primary particle surface is reduced, the contact surface between the electrolyte and the primary particle surface is secured, and the movement of Li is promoted. Therefore, the positive electrode resistance is reduced, and further, the internal resistance of the secondary battery is reduced.
- the positive electrode active material of the present embodiment exhibits excellent characteristics not only at room temperature but also at a low temperature (eg, ⁇ 20 ° C.). Further, since the voltage applied to the load side is increased, the insertion and extraction of lithium at the positive electrode is sufficiently performed, so that the battery capacity and cycle characteristics are improved. Furthermore, since the movement of Li becomes easy and the load received by the positive electrode active material during charge / discharge is reduced, the charge / discharge cycle characteristics are also excellent.
- the amount of excess LiOH in the positive electrode active material is preferably 0.15% by mass or less, and more preferably 0.12% by mass or less with respect to the entire positive electrode active material.
- the lower limit of the amount of excess LiOH is preferably 0.05% by mass or more with respect to the total amount of the positive electrode active material, from the viewpoint of suppressing deterioration of battery characteristics.
- the excess LiOH becomes too small, it indicates that excessive lithium is extracted from the crystal of the lithium metal composite oxide particles when the excess LiOH is fixed as Li 2 CO 3 .
- the amount of excess Li 2 CO 3 in the positive electrode active material is preferably 0.200 ⁇ 10 ⁇ 2 g / m 2 or less with respect to the surface area of the positive electrode active material, preferably 0.157 ⁇ 10 ⁇ 2 g / m 2. It is more preferably 2 or less, and further preferably 0.155 ⁇ 10 ⁇ 2 g / m 2 or less.
- the lower limit of the amount of excess Li 2 CO 3 with respect to the surface area of the positive electrode active material is not particularly limited, and is, for example, 0.100 ⁇ 10 ⁇ 2 g / m 2 or more.
- the positive electrode active material of this embodiment has a pH of 11 or more and 11.9 or less at 25 ° C. when 5 g of the positive electrode active material is dispersed in 100 ml of pure water and the supernatant is measured after standing for 10 minutes. The degree of elution of the lithium into the paste is evaluated by dispersing 5 g of the positive electrode active material in 100 ml of pure water and measuring the pH of the supernatant after standing for 10 minutes.
- the pH of the supernatant liquid at 25 ° C. (hereinafter, also simply referred to as “pH value of the positive electrode active material”) is controlled in the range of 11 or more and 11.9 or less, so that the paste becomes very gelled. To be suppressed.
- pH value of the positive electrode active material When the pH is less than 11, a large amount of excess Li 2 CO 3 is formed, and when lithium is extracted from the lithium metal composite oxide more than necessary, it is charged and discharged when used for the positive electrode of the battery. The capacity may decrease and the reaction resistance of the positive electrode may increase.
- the lower limit of the pH value of the positive electrode active material is preferably 11.5 or more.
- the upper limit of the pH value of the positive electrode active material is preferably 11.8 or less.
- the lithium metal composite oxide particles include secondary particles composed of aggregated primary particles. Further, the positive electrode active material may include primary particles present alone.
- the composite oxide particles can form lithium tungstate (LW compound) described later on the primary particle surfaces. Thereby, it is possible to improve the output characteristics while maintaining the charge / discharge capacity, and to obtain better cycle characteristics.
- t represents the amount of tungsten (W) added to the lithium metal composite oxide.
- W is 0.0001 ⁇ t ⁇ 0.03, preferably 0.0003 ⁇ t ⁇ 0.02, and more preferably 0.0003 ⁇ t ⁇ 0.012. .
- W is included in the above range t, in addition to improving the battery capacity and output characteristics of the lithium metal composite oxide itself, excess LiOH is converted to Li 2 CO 3 and immobilized on the surface of the primary particles. In this case, W eluted in the added water reacts with excess lithium eluted in the water, and lithium tungstate is formed, so that the positive electrode resistance can be reduced.
- s represents the atomic ratio of Li to the total of Ni, Co, Mn, M 2 and W (Li / Me) in the lithium metal composite oxide powder, and the lithium metal composite oxide powder This reflects the amount of Li added in the manufacturing process.
- S in the general formula (2) is preferably in the same range as s in the general formula (1).
- the powder characteristics and particle structure of the positive electrode active material can also be selected from known lithium metal composite oxides according to the characteristics required for the battery.
- the average particle diameter of the positive electrode active material is in the range of 3 ⁇ m or more and 15 ⁇ m or less, and [(d90 ⁇ d10) / average particle diameter], which is an index indicating the spread of the particle size distribution, is preferably 0.7 or less.
- filling property can be improved and the battery capacity per volume of a battery can be made higher.
- the applied voltage between the lithium metal composite oxide particles can be made uniform, the load between the particles can be made uniform, and the cycle characteristics can be further improved.
- the d10 means a particle size in which the number of particles in each particle size is accumulated from the smaller particle size side and the accumulated volume becomes 10% of the total volume of all particles.
- D90 means a particle diameter in which the number of particles is similarly accumulated and the accumulated volume is 90% of the total volume of all particles.
- the average particle diameter, d10 and d90 can be obtained from the volume integrated value measured with a laser light diffraction / scattering particle size analyzer.
- the average particle diameter Mv can be used as the average particle diameter, and can be determined using a laser light diffraction / scattering particle size analyzer in the same manner as d10 and d90.
- the area ratio (porosity) occupied by the voids measured in the cross-sectional observation of the composite oxide powder is preferably 4.5% or more and 60% or less of the entire cross-sectional area of the secondary particles.
- the porosity is in the above range, the positive electrode resistance reduction effect can be further increased while suppressing gelation of the paste.
- the porosity is less than 4.5% of the entire cross-sectional area, a higher reduction effect of the positive electrode resistance may not be obtained.
- the porosity exceeds 60%, the packing density may decrease, and the battery capacity per battery volume may not be sufficiently obtained.
- the whole cross-sectional area of a secondary particle is a cross-sectional area including the space
- the porosity can be measured by observing an arbitrary cross section of the secondary particles using a scanning electron microscope and analyzing the image. Specifically, a plurality of composite oxide particles are embedded in a resin, a cross-section polisher is used to prepare a cross-section sample, and the secondary electron cross-section can be observed with a scanning electron microscope, followed by image analysis. With software (for example, WinRoof 6.1.1 etc.), the void part in the secondary particle is detected in black for any 20 or more secondary particles, and the dense part in the contour of the secondary particle Is detected in white, the total area of the black part and the white part of the 20 or more secondary particles is measured, and the porosity is calculated by calculating the area ratio of [black part / (black part + white part)]. It can be calculated.
- the specific surface area of the positive electrode active material is preferably 1 m 2 / g or more and 50 m 2 / g or less. When the specific surface area is less than 1 m 2 / g, there is little contact with the electrolytic solution, and high output characteristics may not be obtained. Moreover, when a specific surface area exceeds 50 m ⁇ 2 > / g, contact with electrolyte solution increases too much and suppression of gelatinization may not be enough.
- the specific surface area can be determined by the BET method using nitrogen gas adsorption.
- the moisture content of the positive electrode active material is preferably 0.5% by mass or less, and more preferably 0.3% by mass or less.
- the moisture content of the positive electrode active material is preferably 0.5% by mass or less, and more preferably 0.3% by mass or less.
- the method for producing the positive electrode active material comprises mixing a fired powder made of a lithium metal composite oxide having a layered crystal structure and water (Step S1) and drying the mixture obtained by the mixing (Step S2).
- Step S1 a fired powder made of a lithium metal composite oxide having a layered crystal structure and water
- Step S2 drying the mixture obtained by the mixing
- FIG. 1 is a view showing an example of a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to the present embodiment (hereinafter also simply referred to as “a method for producing a positive electrode active material”).
- a method for producing a positive electrode active material hereinafter also simply referred to as “a method for producing a positive electrode active material”.
- the following description is an example of a manufacturing method, Comprising: It does not limit to this method.
- a fired powder made of a lithium metal composite oxide having a layered crystal structure and water are mixed (step S1).
- 5 g of the obtained positive electrode active material was dispersed in 100 ml of pure water, and the pH at 25 ° C. when the supernatant liquid after standing for 10 minutes was measured (hereinafter also simply referred to as “pH value of the positive electrode active material”).
- pH value of the positive electrode active material Is mixed with an amount of water in the range of 11 to 11.9.
- step S1 the fired powder and water are mixed so that the positive electrode active material has a pH value in the range of 11 to 11.9.
- step S2 by mixing a predetermined amount of water, elution of lithium into the paste is suppressed in the paste using the obtained positive electrode active material.
- step S2 surplus LiOH eluted in water reacts with carbon dioxide in the atmosphere to convert surplus LiOH in the fired powder into Li 2 CO 3 .
- the excess LiOH-derived lithium is immobilized on the surface of the primary particles.
- the lower limit of the pH value of the positive electrode active material is 11.5 or more.
- the upper limit of the pH value is 11.8 or less.
- the mixing of the fired powder and water can be performed, for example, by adding water to the fired powder and mixing.
- the amount of water added can be easily determined by collecting a small amount of the fired powder in advance and conducting a preliminary test to confirm the amount of water added.
- the pH value of the positive electrode active material can be controlled within the above-described range by the addition amount determined in the preliminary test.
- the method for adding water is not particularly limited, and water may be added dropwise to the fired powder, or water may be added to the fired powder by spraying.
- water by spraying the fired powder it is preferable to add water by spraying the fired powder to a droplet size of 1 ⁇ m to 2000 ⁇ m.
- water by spraying with fine droplets water can be added uniformly by the calcined powder, the reaction between excess LiOH and carbon dioxide in the atmosphere can be made more uniform, and a higher output improvement effect and It becomes possible to obtain the gelation suppressing effect.
- Various sprays and ultrasonic humidifiers can be used as the water spraying method.
- the droplet size of water when spraying is preferably 1 ⁇ m or more and 2000 ⁇ m or less, and more preferably 5 ⁇ m or more and 1000 ⁇ m or less.
- the mixture of the baked powder and water may be mixed after adding the baked powder water, or may be mixed while adding water, but in order to make the addition of water more uniform, water is added. It is more preferable to mix them.
- the surplus LiOH amount varies depending on the atomic ratio of Li to the total of Ni, Co, Mn, and M (Li / Me) in the sintered powder of lithium metal composite oxide, or the production conditions of the sintered powder.
- the amount of water added may be an amount that allows the pH value of the positive electrode active material to be controlled within the above range by immobilizing these excess LiOH. Therefore, water may be added in a range where the pH value of the positive electrode active material is 11 or more and 11.9 or less.
- the amount of water to be mixed in the mixing step (step S1) can be appropriately adjusted according to the powder characteristics and particle structure of the fired powder. It is preferable that Thereby, excess LiOH can be fixed and the elution of lithium can be further reduced. Further, with sufficient amount of water, the lithium metal composite oxide particles can be sufficiently permeated to the surface of primary particles inside the lithium metal composite oxide particles, and the fixation of surplus LiOH can be promoted uniformly between the lithium metal composite oxide particles. Capacity and output characteristics can be further improved.
- the amount of water mixed is more preferably 1% by mass or more and 6% by mass or less with respect to the fired powder. By optimizing the amount of water to be mixed, it is possible to further prevent lithium from being pulled out excessively while fixing excess LiOH, and to maximize the effect of improving the output characteristics at room temperature and low temperature. Is possible.
- the surface area of the fired powder may vary depending on the composition of the fired powder and the manufacturing conditions. Accordingly, the surface area of the calcined powder to supply desired amounts of water may vary, it is more preferable to mix the water with 0.003 g / m 2 or more 0.025 g / m 2 or less of the range of the surface area.
- the calcined powder has the general formula (1): Li s Ni 1-xyz Co x Mn y M 1 z O 2 (where 0.05 ⁇ x ⁇ 0.35, 0 ⁇ y ⁇ 0.35, 0 ⁇ z ⁇ 0.10, 0.95 ⁇ s ⁇ 1.50, M is represented by at least one element selected from V, Mg, Mo, Nb, Ti, W and Al), and the primary particles are Secondary particles formed by aggregation are included. Since the powder characteristics and particle structure of the fired powder are inherited up to the positive electrode active material, the composition, powder characteristics, particle structure and the like of the fired powder can be the same as those of the positive electrode active material described above. Further, the fired powder is selected according to the positive electrode active material to be obtained.
- t indicating the amount of tungsten (W) is 0.0001 ⁇ t ⁇ 0.03, preferably 0.0003 ⁇ t ⁇ 0.02, and more preferably 0.00.
- W added to the calcined powder is eluted in the water added in the mixing step and similarly reacts with lithium eluted in the water in the drying step to form lithium tungstate on the surface of the primary particles.
- Lithium tungstate reduces the positive electrode resistance and further improves the output characteristics.
- the average particle diameter is in the range of 3 ⁇ m to 15 ⁇ m, and is an index indicating the spread of the particle size distribution [(d90 ⁇ d10) / average particle diameter] is 0. .7 or less can be selected.
- the lower limit of [(d90 ⁇ d10) / average particle diameter] is not particularly limited, but is about 0.25 or more.
- gap measured in the cross-sectional observation of baking powder occupies is 4.5% or more and 60% or less of the cross-sectional area of this lithium metal complex oxide particle.
- An apparatus used for mixing the baked powder and water is not particularly limited, and a known apparatus can be used.
- the mixing is performed using a mixer such as a shaker mixer, a Laedige mixer, a Julia mixer, or a V blender. It is only necessary that the calcined powder and moisture be sufficiently mixed.
- step S2 the mixture obtained by mixing is dried (step S2).
- This step dries the mixture of water and calcined powder, and removes excess LiOH (including excess lithium in the lithium metal composite oxide particles) dissolved in water in the mixture on the surface of the primary particles.
- surplus LiOH reacts with carbon dioxide gas (CO 2 ) in the atmosphere to become Li 2 CO 3 and is immobilized on the primary particle surface as surplus Li 2 CO 3 .
- the surplus LiOH changes from a thin and widely distributed state on the primary particle surface to a state where surplus Li 2 CO 3 forms fine aggregates and is scattered, the primary particle surface and the electrolyte solution are changed. And the reaction field of Li ion intercalation reaction is increased.
- the removal of excess LiOH due to the dispersion of excess Li 2 CO 3 is confirmed by an increase in the specific surface area of the lithium metal composite oxide particles.
- the drying temperature is preferably 450 ° C. or lower. When it exceeds 450 ° C., lithium may further be liberated from the crystal of the lithium metal composite oxide, and the gelation of the paste may not be sufficiently suppressed. From the viewpoint of drying more sufficiently and preventing the liberation of lithium from the lithium metal composite oxide, the drying temperature is more preferably 100 ° C. or higher and 300 ° C. or lower.
- the drying time is not particularly limited, but can be 1 hour or more and 24 hours or less.
- the atmosphere during drying is decarboxylated air in which the content of carbon dioxide gas is controlled as necessary in order to avoid excessive reaction of moisture in the atmosphere and carbon and lithium on the surface of the lithium metal composite oxide particles, An inert gas or a vacuum atmosphere can be used, but an air atmosphere is preferable.
- the content of carbon dioxide gas is preferably 100 ppm to 500 ppm by volume.
- the pressure of the atmosphere during drying is preferably 1 atm or less. When the atmospheric pressure is higher than 1 atm, the water content of the positive electrode active material may not be sufficiently lowered.
- the pressure of the atmosphere at the time of drying is a reduced pressure atmosphere (for example, about ⁇ 90 kPa), the moisture content of the positive electrode active material can be further reduced, and the positive electrode resistance of the obtained secondary battery can be reduced.
- Positive electrode mixture paste for non-aqueous electrolyte secondary battery In the positive electrode mixture paste of this embodiment, elution of lithium from the positive electrode active material is reduced, and gelation of the paste is suppressed. Therefore, the positive electrode mixture paste has a high stability with little change in the viscosity of the paste even after long-term storage. By producing a positive electrode using such a paste, the positive electrode also has stable and excellent characteristics, and the characteristics of the finally obtained battery can be made stable and high.
- the positive electrode mixture paste is characterized by containing the positive electrode active material, and the other constituent materials are the same as those of a normal positive electrode mixture paste.
- the content of the positive electrode active material is 60 to 95 parts by mass in the same manner as the positive electrode of a general non-aqueous electrolyte secondary battery, It is preferable that the content of the conductive agent is 1 to 20 parts by mass and the content of the binder is 1 to 20 parts by mass.
- the conductive agent for example, graphite (natural graphite, artificial graphite, expanded graphite, etc.), carbon black materials such as acetylene black, ketjen black, and the like can be used.
- the binder plays a role of anchoring the active material particles.
- PVDF polyvinylidene fluoride
- PTFE polytetrafluoroethylene
- fluorine rubber ethylene propylene diene rubber
- styrene butadiene cellulose resin
- polyacrylic polyacrylic, and the like.
- An acid or the like can be used.
- a positive electrode active material, a conductive agent, and activated carbon are dispersed, and a solvent that dissolves the binder is added to the positive electrode mixture.
- a solvent that dissolves the binder is added to the positive electrode mixture.
- an organic solvent such as N-methyl-2-pyrrolidone can be used as the solvent.
- Activated carbon can be added to the positive electrode mixture in order to increase the electric double layer capacity.
- a powdered positive electrode active material, a conductive agent, and a binder are mixed, and, if necessary, a target solvent such as activated carbon and viscosity adjustment is added and kneaded to prepare a positive electrode mixture paste.
- Non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, a non-aqueous electrolyte, and the like, and includes the same components as those of a general non-aqueous electrolyte secondary battery. .
- the embodiment described below is merely an example, and the nonaqueous electrolyte secondary battery of the present embodiment can be variously modified based on the knowledge of those skilled in the art based on the embodiment described in the present specification. It can be implemented in an improved form. Further, the use of the nonaqueous electrolyte secondary battery of the present embodiment is not particularly limited.
- the positive electrode mixture paste is applied to, for example, the surface of a current collector made of aluminum foil and dried to disperse the solvent. If necessary, pressurization may be performed by a roll press or the like to increase the electrode density. In this way, a sheet-like positive electrode can be produced.
- the sheet-like positive electrode can be cut into an appropriate size or the like according to the target battery and used for battery production.
- the method for manufacturing the positive electrode is not limited to the illustrated one, and other methods may be used.
- Negative electrode A negative electrode mixture in which a negative electrode active material capable of occluding and desorbing lithium ions is mixed with a binder and an appropriate solvent is added to the negative electrode. Is applied to the surface of a metal foil current collector such as copper, dried, and compressed to increase the electrode density as necessary.
- the negative electrode active material for example, natural graphite, artificial graphite, a fired organic compound such as phenol resin, and a powdery carbon material such as coke can be used.
- a fluorine-containing resin such as PVDF can be used as the negative electrode binder, as in the case of the positive electrode, and a solvent for dispersing these active materials and the binder can be N-methyl-2-pyrrolidone or the like.
- Organic solvents can be used.
- (C) Separator A separator is interposed between the positive electrode and the negative electrode.
- the separator separates the positive electrode and the negative electrode and retains the electrolyte, and a thin film such as polyethylene or polypropylene and a film having many minute holes can be used.
- Non-aqueous electrolyte The non-aqueous electrolyte is obtained by dissolving a lithium salt as a supporting salt in an organic solvent.
- the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate, chain carbonates such as diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, and dipropyl carbonate, tetrahydrofuran, 2- One kind selected from ether compounds such as methyltetrahydrofuran and dimethoxyethane, sulfur compounds such as ethylmethylsulfone and butanesultone, phosphorus compounds such as triethyl phosphate and trioctyl phosphate, etc. are used alone or in admixture of two or more. be able to.
- the non-aqueous electrolyte solution may contain a radical scavenger, a surfactant, a flame retardant, and the like.
- the shape of the non-aqueous electrolyte secondary battery of the present embodiment constituted by the positive electrode, the negative electrode, the separator and the non-aqueous electrolyte described above is a cylindrical type, a laminated type, etc. It can be various.
- the positive electrode and the negative electrode are laminated via a separator to form an electrode body, and the obtained electrode body is impregnated with a non-aqueous electrolyte and communicated with the positive electrode current collector and the outside.
- the positive electrode terminal and the negative electrode current collector and the negative electrode terminal communicating with the outside are connected using a current collecting lead or the like and sealed in a battery case to complete a non-aqueous electrolyte secondary battery. .
- the nonaqueous electrolyte secondary battery using the positive electrode active material of the present embodiment has a high capacity and a high output.
- the non-aqueous electrolyte secondary battery using the positive electrode active material according to the present embodiment obtained in a more preferable form has a high value of 150 mAh / g or more when used for the positive electrode of the 2032 type coin battery described in the examples. An initial discharge capacity and a low positive electrode resistance are obtained.
- the battery reaction at the electrode consists of a resistance component accompanying the charge transfer and a capacity component due to the electric double layer. When these are expressed as an electric circuit, it becomes a parallel circuit of resistance and capacity. It is represented by an equivalent circuit in which circuits are connected in series. Fitting calculation is performed on the Nyquist diagram measured using this equivalent circuit, and each resistance component and capacitance component can be estimated.
- the positive electrode resistance is equal to the diameter of the semicircle on the low frequency side of the obtained Nyquist diagram.
- the positive electrode resistance can be estimated by performing AC impedance measurement on the manufactured positive electrode and performing fitting calculation with the equivalent circuit on the obtained Nyquist diagram.
- the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
- the performance (stability of paste, initial discharge capacity, positive electrode resistance, internal resistance, discharge)
- the capacity retention ratio was evaluated by the following method.
- a negative electrode sheet in which a graphite powder punched into a disk shape with a diameter of 14 mm and an average particle diameter of about 20 ⁇ m and polyvinylidene fluoride are applied to a copper foil is used, and 1 M LiPF 6 is used as the electrolyte for the electrolyte.
- An equivalent mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (manufactured by Toyama Pharmaceutical Co., Ltd.) was used.
- As the separator 3 a polyethylene porous film having a film thickness of 25 ⁇ m was used.
- the coin-type battery B has a gasket 4 and a wave washer 5, and the positive electrode can 6 and the negative electrode can 7 are assembled into a coin-shaped battery.
- the initial discharge capacity, the positive electrode resistance, and the cycle characteristics showing the performance of the manufactured coin battery B were evaluated as follows.
- the initial discharge capacity is left for about 24 hours after the coin-type battery B is manufactured, and after the open circuit voltage OCV (Open Circuit Voltage) is stabilized, the current density with respect to the positive electrode is set to 0.1 mA / cm 2 and the cut-off voltage 4
- OCV Open Circuit Voltage
- the positive electrode resistance is obtained by charging the coin-type battery B at 25 ° C. with a charging potential of 4.1 V and measuring the positive electrode resistance by the AC impedance method using a frequency response analyzer and a potentiogalvanostat (manufactured by Solartron, 1255B).
- the Nyquist plot shown in FIG. Since this Nyquist plot is represented as the sum of the solution resistance, the negative electrode resistance and its capacity, and the characteristic curve indicating the positive electrode resistance and its capacity, the fitting calculation was performed using an equivalent circuit based on this Nyquist plot, and the positive resistance The value of was calculated.
- cycle characteristics discharge capacity maintenance rate
- discharge capacity maintenance rate discharge capacity maintenance rate
- the evaluation of the cycle characteristics was performed based on the capacity maintenance rate after the cycle test.
- the cycle test was held at 60 ° C. and paused for 10 minutes after the initial discharge capacity measurement, and the charge / discharge cycle was repeated 500 cycles (charge / discharge) including the initial discharge capacity measurement in the same manner as the initial discharge capacity measurement.
- the discharge capacity at the 500th cycle was measured, and the percentage of the discharge capacity at the 500th cycle with respect to the discharge capacity at the first cycle (initial discharge capacity) was determined as the capacity retention rate (%).
- a laminate cell C used for evaluation was produced as follows. After mixing a positive electrode active material, a conductive material (acetylene black), and a binder (PVDF) at a mass ratio of 85: 10: 5 to an aluminum current collector foil (thickness 0.02 mm), a solvent (NMP) was added.
- a solvent NMP
- the positive electrode active material was made into a paste, applied while leaving a conductive part connected to the outside, and dried to prepare a positive electrode sheet 8 on which a positive electrode active material layer having a basis weight of 7 mg / cm 2 was formed.
- carbon powder acetylene black
- a negative electrode sheet 9 was produced.
- a laminated sheet was formed between the produced positive electrode sheet 8 and negative electrode sheet 9 with a separator 10 made of a polypropylene microporous film (thickness 20.7 ⁇ m, porosity density 43.9%) interposed therebetween. Then, the laminated sheet is sandwiched between two aluminum laminate sheets 11 (thickness 0.55 mm), and the three sides of the aluminum laminate sheet 11 are heat-sealed to form a heat-sealed portion HS, which is sealed. 4 was assembled. Thereafter, 260 ⁇ l of an electrolyte made by Ube Industries, Ltd.
- the difference in ⁇ V can be interpreted as a resistance difference as it is, that is, the smaller the ⁇ V, the lower the resistance, so the value of ⁇ V was evaluated as a direct current resistance under low temperature conditions.
- An example of the measurement result of the current pause method is shown in FIG.
- the obtained paste was stored for 76 hours, and the viscosity ratio before and after storage (paste viscosity after storage for 76 hours / paste viscosity immediately after preparation) was evaluated.
- the viscosity was measured with a vibration viscometer (VM10A manufactured by Seconic).
- the excess lithium amount was evaluated by titrating Li eluted from the positive electrode active material. After adding 10 ml of pure water to 1 g of the obtained positive electrode active material and stirring for 1 minute, the lithium elution from the neutralization point appearing by adding 1 mol / liter hydrochloric acid while measuring the pH of the filtered filtrate was performed. The compound state was analyzed to evaluate the excess lithium amount.
- the first neutralization point (shoulder) from the high alkali side indicates the LiOH amount
- the second neutralization point indicates the Li 2 CO 3 amount.
- Example 1 Lithium metal composite represented by Li 1.20 Ni 0.35 Co 0.35 Mn 0.30 O 2 obtained by a known technique of mixing and baking oxide powder containing Ni as a main component and lithium hydroxide Baked oxide powder (average particle size: 5.07 ⁇ m, [(d90-d10) / average particle size]: 0.42, porosity: 14.2%: specific surface area 2.50 g / m 2 ) It was. Water was added to the calcined powder used as a base material in an amount of 1.5% by mass with respect to the calcined powder, and further mixed. Then, the positive electrode active material was obtained by drying at 150 degreeC for 12 hours in an atmospheric condition. The production conditions of the positive electrode active material and the following measurement / evaluation results are shown in Tables 1 and 2.
- the specific surface area of the positive electrode active material was determined by a BET method using nitrogen gas adsorption.
- PH measurement 5 g of the obtained positive electrode active material was dispersed in 100 ml of pure water, allowed to stand for 10 minutes, and the pH of the supernatant liquid at 25 ° C. was measured.
- Prositive electrode paste Using the obtained positive electrode active material, the viscosity of the positive electrode mixture paste produced by the above method was measured.
- Battery evaluation Using the obtained positive electrode active material, the battery characteristics of the coin-type battery B and the laminate cell C having the positive electrode prepared by the above method were evaluated.
- Example 2 A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 3% by mass. The evaluation results are shown in Tables 1 and 2.
- Example 3 A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 5% by mass. The evaluation results are shown in Tables 1 and 2.
- Example 4 A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 7% by mass. The evaluation results are shown in Tables 1 and 2.
- Example 5 A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 14% by mass. The evaluation results are shown in Tables 1 and 2.
- Example 6 A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 30% by mass. The evaluation results are shown in Tables 1 and 2.
- Example 7 The fired powder used as a base material is put in a vat, and 3% by mass of water is sprayed on the lithium metal composite oxide powder under the condition that the average droplet diameter is about 300 ⁇ m using a spray bottle.
- a positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that mixing was performed while adding. The evaluation results are shown in Tables 1 and 2.
- Example 8 Put the calcined powder as the base material into a Henschel mixer (FM20C / I manufactured by Nippon Coke Co., Ltd.) and stir and mix the calcined powder with stirring blades in the tank so that the average droplet diameter is about 300 ⁇ m. Under the conditions, 3 mass% water is sprayed and added to the lithium metal composite oxide powder using a spray, and then mixed, and then dried at 130 ° C. for 2 hours in a reduced pressure atmosphere of about ⁇ 90 kPa. In the same manner as in Example 1, a positive electrode active material was obtained and evaluated. The evaluation results are shown in Tables 1 and 2.
- Example 9 A calcined powder of a lithium metal composite oxide having a composition of Li 1.20 (Ni 0.35 Co 0.35 Mn 0.30 ) 0.995 W 0.005 O 2 (average particle size: 4) A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that it was set to .97 ⁇ m, [(d90-d10) / average particle diameter] 0.41, and porosity: 15.6%). The evaluation results are shown in Tables 1 and 2.
- the above composition of the base material is such that the molar ratio of Ni, Co, and Mn (Ni: Co: Mn) is 0.35: 0.35: 0.30, and the sum of Ni, Co, and Mn, and W
- the molar ratio (Ni + Co + Mn: W) is 0.995: 0.005
- the molar ratio (Li: Me) of Li to Me (total of Ni, Co, Mn and W) is 1.20: 1.
- Example 11 A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 5% by mass. The evaluation results are shown in Tables 1 and 2.
- Example 12 A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 7% by mass. The evaluation results are shown in Tables 1 and 2.
- Example 13 A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 14% by mass. The evaluation results are shown in Tables 1 and 2.
- Example 14 A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 30% by mass. The evaluation results are shown in Tables 1 and 2.
- Example 15 The fired powder used as a base material is put in a vat, and 3% by mass of water is sprayed on the lithium metal composite oxide powder under the condition that the average droplet diameter is about 300 ⁇ m using a spray bottle.
- a positive electrode active material was obtained and evaluated in the same manner as in Example 9 except that mixing was performed while adding. The evaluation results are shown in Tables 1 and 2.
- Example 16 Put the calcined powder as the base material into a Henschel mixer (FM20C / I manufactured by Nippon Coke Co., Ltd.) and stir and mix the calcined powder with stirring blades in the tank so that the average droplet diameter is about 300 ⁇ m.
- a Henschel mixer FM20C / I manufactured by Nippon Coke Co., Ltd.
- Example 1 A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the base material was directly used as the positive electrode active material. The evaluation results are shown in Tables 1 and 2.
- Example 2 A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the base material was directly used as the positive electrode active material. The evaluation results are shown in Tables 1 and 2.
- the secondary battery using the positive electrode active material of the example has an initial discharge capacity, a positive electrode resistance, a battery internal resistance, and a capacity maintenance ratio as compared with the secondary battery using the positive electrode active material of the comparative example in which water is not mixed. In either case, good results were obtained.
- the positive electrode resistance and the battery internal resistance were further reduced. In particular, the internal resistance of the battery showing output characteristics at low temperatures was significantly reduced.
- Examples 1 to 3, 7, 8, 9 to 11, 15 and 16 in which the amount of water to be mixed was optimized had a lithium extraction amount as compared with Examples 4 to 6 and 12 to 14 having the same composition.
- the output characteristics are improved as compared with the examples of the same composition while maintaining the low viscosity ratio of the positive electrode mixture paste.
- the output characteristics of Examples 7, 8, 15, and 16 to which water was added by spraying are further improved.
- the content of surplus LiOH was reduced while the content of surplus Li 2 CO 3 was increased as compared with Comparative Examples 1 and 2 in which water was not mixed.
- LiOH / Li 2 CO 3 was 0.45 or less. This is presumably because excess LiOH in the fired powder was converted to Li 2 CO 3 in the step of adding water and subsequent drying.
- the positive electrode mixture paste using the positive electrode active material of the example has a lower viscosity ratio value and excellent viscosity stability than the positive electrode mixture paste of the comparative example.
Landscapes
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The purpose of the present invention is to provide a positive-electrode active material for a non-aqueous-electrolyte secondary cell with which it is possible to improve the stability of a positive-electrode material paste when manufacturing a non-aqueous-electrolyte secondary cell, and with which it is possible to improve the cell capacity and output characteristics when configuring a secondary cell. The problem is addressed using a method for manufacturing a positive-electrode active material for a non-aqueous-electrolyte secondary cell, etc. provided with mixing of water with a firing powder comprising a lithium composite metal oxide having a layered structure crystalline structure, and drying of the mixture obtained by mixing; and for which the firing powder contains secondary particles formed by agglomerating primary particles, and the water is mixed in an amount such that when 5 g of the obtained positive-electrode active material is dispersed in 100 ml of purified water, and the supernatant liquid after standing still for 10 minutes is measured, the pH at 25°C is in the range of 11-11.9.
Description
本発明は、非水系電解質二次電池用正極活物質とその製造方法、非水系電解質二次電池用正極合材ペーストおよび非水系電解質二次電池に関する。
The present invention relates to a positive electrode active material for a non-aqueous electrolyte secondary battery and a method for producing the same, a positive electrode mixture paste for a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery.
近年、携帯電話やノート型パソコンなどの携帯電子機器の普及に伴い、高いエネルギー密度を有する小型で軽量な二次電池の開発が強く望まれている。また、ハイブリット自動車を始めとする電気自動車用の電池として出力特性と充放電サイクル特性が優れた二次電池の開発が強く望まれている。
In recent years, with the widespread use of portable electronic devices such as mobile phones and notebook computers, the development of small and lightweight secondary batteries with high energy density is strongly desired. In addition, development of secondary batteries having excellent output characteristics and charge / discharge cycle characteristics is strongly desired as batteries for electric vehicles including hybrid cars.
このような要求を満たす二次電池として、非水系電解質二次電池が挙げられ、代表的な非水系電解質二次電池としてリチウムイオン二次電池が挙げられる。リチウムイオン二次電池は、負極および正極と電解液等で構成され、負極および正極の活物質は、リチウムを脱離および挿入することの可能な材料が用いられている。
As a secondary battery satisfying such requirements, a non-aqueous electrolyte secondary battery can be cited, and a lithium ion secondary battery can be cited as a typical non-aqueous electrolyte secondary battery. A lithium ion secondary battery is composed of a negative electrode, a positive electrode, an electrolyte, and the like, and an active material for the negative electrode and the positive electrode is made of a material that can desorb and insert lithium.
リチウムイオン二次電池は、現在、研究開発が盛んに行われているところであり、中でも、層状またはスピネル型のリチウム金属複合酸化物を正極材料に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、高いエネルギー密度を有する電池として実用化が進んでいる。
Lithium ion secondary batteries are currently being actively researched and developed. Among them, lithium ion secondary batteries using a layered or spinel type lithium metal composite oxide as a positive electrode material have a high 4V class. Since a voltage can be obtained, the practical application is progressing as a battery having a high energy density.
これまで主に提案されている正極活物質としては、合成が比較的容易なリチウムコバルト複合酸化物(LiCoO2)や、コバルトよりも安価なニッケルを用いたリチウム金属複合酸化物(LiNiO2)、リチウムニッケルコバルトマンガン複合酸化物(LiNi1/3Co1/3Mn1/3O2)、マンガンを用いたリチウムマンガン複合酸化物(LiMn2O4)などを挙げることができる。充放電サイクル特性のさらなる改善を図るためには、例えば、ニッケル、コバルト、マンガンなどの金属元素に対してリチウムを化学両論組成よりも過剰に含有させることが有効である。
As positive electrode active materials that have been mainly proposed so far, lithium cobalt composite oxide (LiCoO 2 ) that is relatively easy to synthesize, lithium metal composite oxide (LiNiO 2 ) using nickel that is cheaper than cobalt, Examples thereof include lithium nickel cobalt manganese composite oxide (LiNi 1/3 Co 1/3 Mn 1/3 O 2 ) and lithium manganese composite oxide (LiMn 2 O 4 ) using manganese. In order to further improve the charge / discharge cycle characteristics, for example, it is effective to contain lithium in excess of the stoichiometric composition with respect to metal elements such as nickel, cobalt, and manganese.
ところで、非水系電解質二次電池の正極は、例えば、正極活物質と、ポリフッ化ビニリデン(PVDF)などのバインダーと、ノルマルメチル-2-ピロリドン(NMP)などの溶剤とを混合して得られる正極合材ペーストを、アルミ箔などの集電体に塗布することで形成される。このとき、正極合材ペースト中において正極活物質から遊離したリチウムが、バインダーに含まれる水分と反応して、水酸化リチウムが生成されることがある。この生成された水酸化リチウムとバインダーとが反応して、正極合材ペーストのゲル化を生じることがある。正極合材ペーストのゲル化は、操作性の悪さ、歩留まりの悪化を招く。この傾向は、正極活物質におけるリチウムが化学量論比よりも過剰で、且つニッケルの割合が高い場合に顕著となる。
By the way, the positive electrode of the nonaqueous electrolyte secondary battery is, for example, a positive electrode obtained by mixing a positive electrode active material, a binder such as polyvinylidene fluoride (PVDF), and a solvent such as normal methyl-2-pyrrolidone (NMP). It is formed by applying a composite paste to a current collector such as an aluminum foil. At this time, lithium liberated from the positive electrode active material in the positive electrode mixture paste may react with moisture contained in the binder to generate lithium hydroxide. The generated lithium hydroxide and the binder may react to cause gelation of the positive electrode mixture paste. Gelation of the positive electrode mixture paste causes poor operability and yield. This tendency becomes remarkable when the lithium in the positive electrode active material is in excess of the stoichiometric ratio and the ratio of nickel is high.
正極合材ペーストのゲル化を抑制する試みがいくつかなされている。例えば、特許文献1には、LixNi1-yAyO2(0.98≦x≦1.06、0.05≦y≦0.30、AはCo、Alのうち少なくとも1種)で与えられ、5gを純水100g中に120分間撹拌混合した後、30秒間静置して得られる上澄みのpHが、25℃において12.7以下である非水系電解質二次電池用正極活物質が提案されている。この正極活物質は、スラリ(正極合材ペースト)を作製後、24時間経過しても流動性があり、耐ゲル化性に優れていることが記載されている。
Some attempts have been made to suppress gelation of the positive electrode composite paste. For example, Patent Document 1 discloses Li x Ni 1-y A y O 2 (0.98 ≦ x ≦ 1.06, 0.05 ≦ y ≦ 0.30, A is at least one of Co and Al). The positive electrode active material for a non-aqueous electrolyte secondary battery in which 5 g is stirred and mixed in 100 g of pure water for 120 minutes and then left to stand for 30 seconds, and the pH of the supernatant is 12.7 or less at 25 ° C. Has been proposed. It is described that this positive electrode active material has fluidity and excellent gelation resistance even after 24 hours have passed since the slurry (positive electrode mixture paste) was produced.
また、特許文献2には、リチウム遷移金属複合酸化物からなる正極活物質と、酸性酸化物粒子からなる粒子からなる添加粒子とを含む非水電解液二次電池用正極組成物が提案されている。この正極組成物は、バインダーに含まれる水分と反応して生成した水酸化リチウムが酸性酸化物と優先的に反応し、生成した水酸化リチウムとバインダーとの反応を抑制し、正極合材ペーストのゲル化を抑制することが記載されている。また、酸性酸化物は、正極内で導電剤としての役割を果たし、正極全体の抵抗を下げ、電池の出力特性向上に寄与するとしている。
Patent Document 2 proposes a positive electrode composition for a non-aqueous electrolyte secondary battery including a positive electrode active material composed of a lithium transition metal composite oxide and additive particles composed of particles composed of acidic oxide particles. Yes. In this positive electrode composition, lithium hydroxide generated by reacting with moisture contained in the binder preferentially reacts with the acidic oxide, suppressing the reaction between the generated lithium hydroxide and the binder, It is described that gelation is suppressed. Further, the acidic oxide plays a role as a conductive agent in the positive electrode, lowers the resistance of the whole positive electrode, and contributes to the improvement of the output characteristics of the battery.
また、特許文献3には、正極活物質として、組成外にLiOHを含むリチウム遷移金属酸化物を用意すること;正極活物質1g当たりに含まれるLiOHのモル量Pを把握すること;LiOHのモル量Pに対して、LiOH1モル当たり、タングステン原子換算で0.05モル以上の酸化タングステンを用意すること;および、正極活物質と酸化タングステンとを、導電材および結着剤とともに有機溶媒で混練して正極ペーストを調製すること;を包含する、リチウムイオン二次電池製造方法が提案されている。
Patent Document 3 also provides a lithium transition metal oxide containing LiOH outside the composition as the positive electrode active material; grasping the molar amount P of LiOH contained per gram of the positive electrode active material; Prepare 0.05 mol or more of tungsten oxide in terms of tungsten atom per mol of LiOH with respect to the amount P; and knead the positive electrode active material and tungsten oxide together with the conductive material and the binder in an organic solvent. A method for producing a lithium ion secondary battery has been proposed.
一方、出力特性と充放電サイクル特性に優れたリチウムイオン二次電池を得る試みもいくつかなされている。例えば、正極活物質を、小粒径であり、かつ、粒度分布が狭い粒子によって構成することにより、出力特性と充放電サイクル特性に優れることが知られている。これは、粒径が小さい粒子は、比表面積が大きく、正極活物質として用いた場合に電解液との反応面積を十分に確保することができるばかりでなく、正極を薄く構成し、リチウムイオンの正極-負極間の移動距離を短くすることができるため、正極抵抗の低減が可能だからである。また、粒度分布が狭い粒子は、電極内で粒子に印加される電圧を均一化できるため、微粒子が選択的に劣化することによる電池容量の低下を抑制することが可能となるためである
On the other hand, some attempts have been made to obtain lithium ion secondary batteries excellent in output characteristics and charge / discharge cycle characteristics. For example, it is known that the positive electrode active material is excellent in output characteristics and charge / discharge cycle characteristics by being composed of particles having a small particle size and a narrow particle size distribution. This is because particles having a small particle size have a large specific surface area, and when used as a positive electrode active material, a sufficient reaction area with the electrolytic solution can be secured, and the positive electrode is made thin, This is because the movement distance between the positive electrode and the negative electrode can be shortened, so that the positive electrode resistance can be reduced. In addition, the particles having a narrow particle size distribution can equalize the voltage applied to the particles in the electrode, and therefore it is possible to suppress a decrease in battery capacity due to the selective deterioration of the fine particles.
さらに出力特性と充放電サイクル特性のさらなる改善を図るためには、例えば、正極活物質を中空構造とすることが有効であることが報告されている。このような正極活物質は、粒径が同程度である中実構造の正極活物質と比べて、電解液との反応面積を大きくすることができるため、正極抵抗を大幅に低減することができる。
In order to further improve the output characteristics and charge / discharge cycle characteristics, for example, it has been reported that it is effective to make the positive electrode active material have a hollow structure. Since such a positive electrode active material can increase the reaction area with the electrolyte compared to a solid positive electrode active material having the same particle size, the positive electrode resistance can be greatly reduced. .
例えば、特許文献4及び特許文献5には、正極活物質の前駆体となる遷移金属複合水酸化物粒子を、主として核生成を行う核生成工程と、主として粒子成長を行う粒子成長工程の2段階に明確に分離した晶析反応により、製造する方法が開示されている。これらの方法では、反応水溶液のpH値を、液温25℃基準で、核生成工程では12以上(例えば、12.0~13.4または12.0~14.0)の範囲に、粒子成長工程では、核生成工程より低く、かつ12以下(例えば、10.5~12.0)の範囲に制御している。また、反応雰囲気を、核生成工程および粒子成長工程の初期では酸化性雰囲気とするとともに、所定のタイミングで、非酸化性雰囲気に切り替えている。
For example, in Patent Document 4 and Patent Document 5, transition metal composite hydroxide particles serving as a precursor of a positive electrode active material are mainly divided into two stages: a nucleation process for mainly nucleation and a particle growth process for mainly particle growth. Discloses a method for producing by a crystallized reaction clearly separated. In these methods, the pH value of the aqueous reaction solution is adjusted to a particle temperature within a range of 12 or more (for example, 12.0 to 13.4 or 12.0 to 14.0) in the nucleation step, based on a liquid temperature of 25 ° C. In the process, it is controlled to be lower than the nucleation process and 12 or less (for example, 10.5 to 12.0). The reaction atmosphere is an oxidizing atmosphere at the initial stage of the nucleation step and the particle growth step, and is switched to a non-oxidizing atmosphere at a predetermined timing.
これらの方法により、得られる遷移金属複合水酸化物粒子は、小粒径で粒度分布が狭く、かつ、微細一次粒子からなる低密度の中心部と、板状または針状一次粒子からなる高密度の外殻部とから構成される。したがって、このような遷移金属複合水酸化物粒子を焼成した場合、低密度の中心部が大きく収縮し、内部に空間部が形成される。そして、複合水酸化物粒子の粒子性状は、正極活物質に引き継がれる。これらの正極活物質を用いた二次電池では、容量特性、出力特性と充放電サイクル特性とを改善できるとされている。
By these methods, the obtained transition metal composite hydroxide particles have a small particle size, a narrow particle size distribution, a low-density central portion composed of fine primary particles, and a high density composed of plate-like or needle-like primary particles. And the outer shell. Therefore, when such transition metal composite hydroxide particles are fired, the low density center portion is greatly contracted, and a space portion is formed inside. The particle properties of the composite hydroxide particles are inherited by the positive electrode active material. It is said that secondary batteries using these positive electrode active materials can improve capacity characteristics, output characteristics, and charge / discharge cycle characteristics.
さらに出力特性の向上に関しては、例えば、特許文献6には、一次粒子および前記一次粒子が凝集して構成された二次粒子からなるリチウム金属複合酸化物粉末に、タングステン化合物を溶解させたアルカリ溶液を添加、混合することにより、前記リチウム金属複合酸化物粉末の表面もしくは該粉末の一次粒子の表面にWを分散させる第1工程と、混合した前記タングステン化合物を溶解させたアルカリ溶液とリチウム金属複合酸化物粉末を、熱処理することによりWおよびLiを含む微粒子を、前記リチウム金属複合酸化物粉末の表面もしくは該粉末の一次粒子の表面に形成する第2工程を有する非水系電解質二次電池用正極活物質の製造方法が提案されている。
Regarding the improvement of output characteristics, for example, Patent Document 6 discloses an alkaline solution in which a tungsten compound is dissolved in a lithium metal composite oxide powder composed of primary particles and secondary particles formed by aggregation of the primary particles. Adding and mixing the first step of dispersing W on the surface of the lithium metal composite oxide powder or the primary particles of the powder, the alkali solution in which the mixed tungsten compound is dissolved, and the lithium metal composite A positive electrode for a non-aqueous electrolyte secondary battery comprising a second step of forming fine particles containing W and Li on the surface of the lithium metal composite oxide powder or the surface of primary particles of the powder by heat-treating the oxide powder. A method for producing an active material has been proposed.
この提案によれば、電池の正極材に用いられた場合に高容量とともに高出力が実現可能な非水系電解質二次電池用正極活物質が得られるとされている。しかしながら、高出力化に関しては検討されているものの、正極合材ペーストのゲル化抑制については何ら検討されていない。
According to this proposal, it is said that a positive electrode active material for a non-aqueous electrolyte secondary battery capable of realizing high capacity and high output when used as a positive electrode material of a battery is obtained. However, although high power output has been studied, no investigation has been made on gelation suppression of the positive electrode mixture paste.
しかしながら、上記特許文献1の提案では、スラリー(正極合材ペースト)中で長時間安定なリチウム二次電池用正極活物質を実用的に判定可能とする条件が提供されているに過ぎず、正極合材ペーストのゲル化抑制対策としては不十分である。また、上記特許文献2の提案では、酸性酸化物の粒子が残留することによってセパレータの破損およびそれにともなう安全性低下の恐れがある。また、ゲル化抑制が十分であるとはいえない。さらに、上記特許文献3の提案においても、酸性酸化物(例えば、酸化タングステン)の残留によるセパレータの破損、さらには、ゲル化の抑制に関する問題点が解消されているとはいえない。
However, the proposal of the above-mentioned Patent Document 1 merely provides a condition that allows a positive electrode active material for a lithium secondary battery that is stable for a long time in a slurry (positive electrode mixture paste) to be practically determined. It is insufficient as a measure for suppressing gelation of the composite paste. Moreover, in the proposal of the above-mentioned patent document 2, there is a fear that the separator is damaged and the safety is lowered due to the remaining acidic oxide particles. Moreover, it cannot be said that gelation suppression is sufficient. Further, even in the proposal of the above-mentioned Patent Document 3, it cannot be said that the problem regarding the breakage of the separator due to the remaining acidic oxide (for example, tungsten oxide) and the suppression of gelation are not solved.
また、上記特許文献4及び特許文献5の提案のように、出力特性と充放電サイクル特性を向上させるため、電解液との反応面積を大きくすると、正極合材ペーストのゲル化が促進されるという新たな問題点が生じることがある。さらに、上記特許文献6の提案では、出力特性に関しては検討されているものの、正極合材ペーストのゲル化抑制については何ら検討されていない。よって、上記いくつかの提案では正極合材ペーストのゲル化抑制及び電池特性の向上に関して検討されているものの、問題点が十分に解消されているとは言えない。
Further, as proposed in Patent Document 4 and Patent Document 5 above, when the reaction area with the electrolyte is increased in order to improve output characteristics and charge / discharge cycle characteristics, gelation of the positive electrode mixture paste is promoted. New problems may arise. Furthermore, in the proposal of the above-mentioned Patent Document 6, although the output characteristics have been studied, no study has been made on the gelation suppression of the positive electrode mixture paste. Therefore, although some of the above proposals have been examined with regard to the suppression of gelation of the positive electrode mixture paste and the improvement of battery characteristics, it cannot be said that the problem has been sufficiently solved.
本発明は、上述の問題に鑑みて、非水系電解質二次電池を製造する場合の正極合材ペーストの安定性を向上させ、かつ、二次電池を構成した場合の出力特性及びサイクル特性と充放電容量とを同時に向上させることができる非水系電解質二次電池用正極活物質、および、その製造方法を提供することを目的とする。また、本発明は、このような正極活物質を用いた正極合材ペーストと非水系電解質二次電池を提供することを目的とする。
In view of the above-mentioned problems, the present invention improves the stability of the positive electrode mixture paste when producing a non-aqueous electrolyte secondary battery, and satisfies the output characteristics and cycle characteristics when the secondary battery is configured. It aims at providing the positive electrode active material for nonaqueous electrolyte secondary batteries which can improve discharge capacity simultaneously, and its manufacturing method. Another object of the present invention is to provide a positive electrode mixture paste using such a positive electrode active material and a non-aqueous electrolyte secondary battery.
本発明者は、上記課題を解決するため、非水系電解質二次電池用正極合材ペーストのゲル化抑制と出力特性に関して鋭意研究した結果、正極合材ペーストのゲル化には正極活物質として用いられているリチウム金属複合酸化物のpHが大きく影響していること、及びリチウム金属複合酸化物の粒子の表面に余剰リチウムが形成している化合物の形態を制御することで、リチウム金属複合酸化物のpHの制御が可能であるとともに正極活物質の反応抵抗を低減して出力特性を向上させることができるとの知見を得た。さらに、リチウム金属複合酸化物に水を混合して乾燥させることで、余剰リチウムが形成している化合物の形態を制御することができるとの知見を得て、本発明を完成させた。
In order to solve the above-mentioned problems, the present inventor has intensively studied on the gelation suppression and output characteristics of the positive electrode mixture paste for the non-aqueous electrolyte secondary battery. As a result, the present inventors used the positive electrode mixture paste as a positive electrode active material. The lithium metal composite oxide is greatly influenced by the pH of the lithium metal composite oxide and the form of the compound in which excess lithium is formed on the surface of the lithium metal composite oxide particles. It was found that the pH can be controlled and the reaction resistance of the positive electrode active material can be reduced to improve the output characteristics. Furthermore, the present invention was completed by obtaining the knowledge that the form of the compound formed by excess lithium can be controlled by mixing and drying water in the lithium metal composite oxide.
本発明の第1の態様では、層状構造の結晶構造を有するリチウム金属複合酸化物からなる焼成粉末と水とを混合することと、前記混合して得られた混合物を乾燥することと、を備え、焼成粉末は、一般式(1):LisNi1-x-y-zCoxMnyM1
zO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、M1は、V、Mg、Mo、Nb、Ti、WおよびAlから選ばれる少なくとも1種の元素)で表され、一次粒子が凝集して形成された二次粒子を含み、水は、得られる正極活物質5gを100mlの純水に分散させ、10分間静置後の上澄み液を測定した際の25℃におけるpHが11以上11.9以下の範囲となる量を混合する、非水系電解質二次電池用正極活物質の製造方法が提供される。
In a first aspect of the present invention, the method comprises mixing a fired powder made of a lithium metal composite oxide having a layered crystal structure and water, and drying the mixture obtained by the mixing. , baking powder, formula (1): Li s Ni 1 -x-y-z Co x Mn y M 1 z O 2 ( however, 0.05 ≦ x ≦ 0.35,0 ≦ y ≦ 0.35 , 0 ≦ z ≦ 0.10, 0.95 ≦ s ≦ 1.50, M 1 is represented by at least one element selected from V, Mg, Mo, Nb, Ti, W and Al), and primary The secondary particles formed by agglomeration of the particles contain water, and 5 g of the obtained positive electrode active material is dispersed in 100 ml of pure water, and the pH at 25 ° C. when measuring the supernatant after standing for 10 minutes is 25 ° C. A positive electrode active for a non-aqueous electrolyte secondary battery, in which an amount in the range of 11 to 11.9 is mixed. Method of manufacturing quality is provided.
また、焼成粉末と水とを混合する際、水を1~2000μmの液滴サイズに噴霧して添加することが好ましい。また、水を、焼成粉末に対して1質量%以上35質量%以下の範囲で混合することが好ましい。また、水を、焼成粉末の表面積に対して0.003g/m2以上0.025g/m2以下の範囲で混合することが好ましい。また、水を、焼成粉末に対して1質量%以上6質量%以下の範囲で混合することが好ましい。また、焼成粉末は、平均粒径が3μm以上15μm以下で範囲にあり、粒度分布の広がりを示す指標である〔(d90-d10)/平均粒径〕が0.7以下であることが好ましい。また、焼成粉末は、断面観察により計測される空隙が占める面積割合が、焼成粉末の断面積全体に対して4.5%以上60%以下であることが好ましい。また、乾燥は、100℃以上300℃以下で行うことが好ましい。また、焼成粉末は、一般式(2):LisNi1-x-y-z-tCoxMnyM2
zWtO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、0.0001≦t≦0.03、0.0001≦z+t≦0.10、M2は、V、Mg、Mo、Nb、TiおよびAlから選ばれる少なくとも1種の元素)で表されることが好ましい。
Further, when mixing the calcined powder and water, it is preferable to add the water by spraying it to a droplet size of 1 to 2000 μm. Moreover, it is preferable to mix water in the range of 1 mass% or more and 35 mass% or less with respect to baked powder. Moreover, it is preferable to mix water in the range of 0.003 g / m 2 or more and 0.025 g / m 2 or less with respect to the surface area of the fired powder. Moreover, it is preferable to mix water in 1 mass% or more and 6 mass% or less with respect to baked powder. The fired powder preferably has an average particle size in the range of 3 μm to 15 μm, and [(d90−d10) / average particle size], which is an index indicating the spread of the particle size distribution, is 0.7 or less. Moreover, as for the baked powder, it is preferable that the area ratio which the space | gap measured by cross-sectional observation occupies is 4.5% or more and 60% or less with respect to the whole cross-sectional area of baked powder. Moreover, it is preferable to perform drying at 100 degreeC or more and 300 degrees C or less. The firing powder has the general formula (2): Li s Ni 1 -x-y-z-t Co x Mn y M 2 z W t O 2 ( however, 0.05 ≦ x ≦ 0.35,0 ≦ y ≦ 0.35, 0 ≦ z ≦ 0.10, 0.95 ≦ s ≦ 1.50, 0.0001 ≦ t ≦ 0.03, 0.0001 ≦ z + t ≦ 0.10, M 2 is V, It is preferably represented by at least one element selected from Mg, Mo, Nb, Ti and Al.
本発明の第2の態様では、層状構造の結晶構造を有するリチウム金属複合酸化物粉末からなる非水系電解質二次電池用正極活物質であって、リチウム金属複合酸化物粉末は、一般式LisNi1-x-y-zCoxMnyM1
zO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、M1は、V、Mg、Mo、Nb、Ti、WおよびAlから選ばれる少なくとも1種の元素)で表され、一次粒子が凝集して形成された二次粒子を含み、正極活物質5gを100mlの純水に分散させ、10分間静置後の上澄み液を測定した際の25℃におけるpHが11以上11.9以下であり、滴定法によって定量される余剰LiOHと余剰Li2CO3の質量の比(余剰LiOH/余剰Li2CO3)が0.45以下である、非水系電解質二次電池用正極活物質が提供される。
According to a second aspect of the present invention, there is provided a positive electrode active material for a non-aqueous electrolyte secondary battery comprising a lithium metal composite oxide powder having a layered crystal structure, wherein the lithium metal composite oxide powder has the general formula Li s. Ni 1-xyz Co x Mn y M 1 z O 2 (where 0.05 ≦ x ≦ 0.35, 0 ≦ y ≦ 0.35, 0 ≦ z ≦ 0.10, 0.95 ≦ s ≦ 1.50, M 1 is represented by at least one element selected from V, Mg, Mo, Nb, Ti, W and Al), and includes secondary particles formed by aggregation of primary particles In addition, 5 g of the positive electrode active material is dispersed in 100 ml of pure water, and the pH at 25 ° C. when measuring the supernatant after standing for 10 minutes is 11 to 11.9, and the excess LiOH determined by the titration method mass ratio of excess Li 2 CO 3 (excess LiOH / surplus L 2 CO 3) is 0.45 or less, the positive electrode active material for a non-aqueous electrolyte secondary battery is provided.
また、上記正極活物質は、余剰LiOHと余剰Li2CO3の量の比が0.3以下であることが好ましい。また、余剰LiOHと余剰Li2CO3の量の比が0.18以上であり、余剰Li2CO3の量が前記正極活物質の表面積に対して0.157×10-2g/m2以下であることが好ましい。また、上記正極活物質は、平均粒径が3μm以上15μm以下の範囲にあり、粒度分布の広がりを示す指標である〔(d90-d10)/平均粒径〕が0.7以下であることが好ましい。また、リチウム金属複合酸化物粉末の断面観察において計測される空隙が占める面積割合が、該リチウム金属複合酸化物粒子全体の断面積に対して4.5%以上60%以下あることが好ましい。また、リチウム金属複合酸化物粉末は、一般式LisNi1-x-y-z-tCoxMnyM2
zWtO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦<s≦1.50、0.0001≦t≦0.03、0.0001≦z+t≦0.10、M2は、V、Mg、Mo、Nb、TiおよびAlから選ばれる少なくとも1種の元素)で表されることが好ましい。
The positive electrode active material preferably has a ratio of the amount of excess LiOH to excess Li 2 CO 3 of 0.3 or less. Further, the ratio of the amount of surplus LiOH and surplus Li 2 CO 3 is 0.18 or more, and the amount of surplus Li 2 CO 3 is 0.157 × 10 −2 g / m 2 with respect to the surface area of the positive electrode active material. The following is preferable. The positive electrode active material has an average particle size in the range of 3 μm or more and 15 μm or less, and [(d90−d10) / average particle size], which is an index indicating the spread of the particle size distribution, is 0.7 or less. preferable. Moreover, it is preferable that the area ratio which the space | gap which is measured in the cross-sectional observation of lithium metal complex oxide powder occupies 4.5% or more and 60% or less with respect to the cross-sectional area of this lithium metal complex oxide particle whole. Further, the lithium metal composite oxide powder represented by the general formula Li s Ni 1-x-y -z-t Co x Mn y M 2 z W t O 2 ( however, 0.05 ≦ x ≦ 0.35,0 ≦ y ≦ 0.35, 0 ≦ z ≦ 0.10, 0.95 ≦ <s ≦ 1.50, 0.0001 ≦ t ≦ 0.03, 0.0001 ≦ z + t ≦ 0.10, M 2 is V And at least one element selected from Mg, Mo, Nb, Ti and Al.
本発明の第3の態様では、非水系電解質二次電池用正極合材ペーストは、上記非水系電解質二次電池用正極活物質を含む。
In the third aspect of the present invention, the positive electrode mixture paste for a non-aqueous electrolyte secondary battery includes the positive electrode active material for a non-aqueous electrolyte secondary battery.
本発明の第4の態様では、非水系電解質二次電池は、上記非水系電解質二次電池用正極活物質を含む正極を有する。
In the fourth aspect of the present invention, a non-aqueous electrolyte secondary battery has a positive electrode containing the positive electrode active material for a non-aqueous electrolyte secondary battery.
本発明によれば、ゲル化が抑制され安定性が高い正極合材スラリーが得られ、かつ、電池の正極材に用いられた場合に優れた出力特性及びサイクル特性と、優れた充放電容量とが得られる非水系電解質二次電池用正極活物質を提供することができる。さらに、その製造方法は、容易で工業的規模での生産に適したものであり、その工業的価値は極めて大きい。
According to the present invention, a positive electrode mixture slurry with high gel stability and high stability is obtained, and excellent output characteristics and cycle characteristics when used for a positive electrode material of a battery, and excellent charge / discharge capacity, It is possible to provide a positive electrode active material for a non-aqueous electrolyte secondary battery. Furthermore, the manufacturing method is easy and suitable for production on an industrial scale, and its industrial value is extremely large.
以下、本実施形態について、(1)非水系電解質二次電池用正極活物質と(2)その製造方法、さらに該正極活物質を用いた(3)非水系電解質二次電池用正極合材ペーストおよび(4)非水系電解質二次電池について説明する。
Hereinafter, regarding the present embodiment, (1) a positive electrode active material for a non-aqueous electrolyte secondary battery, (2) a manufacturing method thereof, and (3) a positive electrode mixture paste for a non-aqueous electrolyte secondary battery using the positive electrode active material And (4) the non-aqueous electrolyte secondary battery will be described.
(1)非水系電解質二次電池用正極活物質
本実施形態の非水系電解質正極活物質(以下、「正極活物質」ともいう。)は、層状構造の結晶構造を有するリチウム金属複合酸化物粉末(以下、「複合酸化物粉末」ともいう。)からなり、リチウム金属複合酸化物粉末は、一般式(1):LisNi1-x-y-zCoxMnyM1 zO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、M1は、V、Mg、Mo、Nb、Ti、WおよびAlから選ばれる少なくとも1種の元素)で表され、一次粒子が凝集して形成された二次粒子を含む。また、正極活物質5gを100mlの純水に分散させ、10分間静置後の上澄み液を測定した際の25℃におけるpHが11以上11.9以下であり、滴定法によって定量される余剰LiOHと余剰Li2CO3の質量との比(余剰LiOH/余剰Li2CO3)が0.45以下である。 (1) Positive electrode active material for non-aqueous electrolyte secondary battery The non-aqueous electrolyte positive electrode active material of the present embodiment (hereinafter also referred to as “positive electrode active material”) is a lithium metal composite oxide powder having a layered crystal structure. (Hereinafter also referred to as “composite oxide powder”), and the lithium metal composite oxide powder has the general formula (1): Li s Ni 1-xyZ Co x Mn y M 1 z O 2 ( However, 0.05 ≦ x ≦ 0.35, 0 ≦ y ≦ 0.35, 0 ≦ z ≦ 0.10, 0.95 ≦ s ≦ 1.50, M 1 is V, Mg, Mo, Nb, And at least one element selected from Ti, W, and Al), and includes secondary particles formed by aggregation of primary particles. Further, 5 g of the positive electrode active material is dispersed in 100 ml of pure water, and the pH at 25 ° C. when measuring the supernatant after standing for 10 minutes is 11 to 11.9, and excess LiOH determined by titration And the mass of surplus Li 2 CO 3 (surplus LiOH / surplus Li 2 CO 3 ) is 0.45 or less.
本実施形態の非水系電解質正極活物質(以下、「正極活物質」ともいう。)は、層状構造の結晶構造を有するリチウム金属複合酸化物粉末(以下、「複合酸化物粉末」ともいう。)からなり、リチウム金属複合酸化物粉末は、一般式(1):LisNi1-x-y-zCoxMnyM1 zO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、M1は、V、Mg、Mo、Nb、Ti、WおよびAlから選ばれる少なくとも1種の元素)で表され、一次粒子が凝集して形成された二次粒子を含む。また、正極活物質5gを100mlの純水に分散させ、10分間静置後の上澄み液を測定した際の25℃におけるpHが11以上11.9以下であり、滴定法によって定量される余剰LiOHと余剰Li2CO3の質量との比(余剰LiOH/余剰Li2CO3)が0.45以下である。 (1) Positive electrode active material for non-aqueous electrolyte secondary battery The non-aqueous electrolyte positive electrode active material of the present embodiment (hereinafter also referred to as “positive electrode active material”) is a lithium metal composite oxide powder having a layered crystal structure. (Hereinafter also referred to as “composite oxide powder”), and the lithium metal composite oxide powder has the general formula (1): Li s Ni 1-xyZ Co x Mn y M 1 z O 2 ( However, 0.05 ≦ x ≦ 0.35, 0 ≦ y ≦ 0.35, 0 ≦ z ≦ 0.10, 0.95 ≦ s ≦ 1.50, M 1 is V, Mg, Mo, Nb, And at least one element selected from Ti, W, and Al), and includes secondary particles formed by aggregation of primary particles. Further, 5 g of the positive electrode active material is dispersed in 100 ml of pure water, and the pH at 25 ° C. when measuring the supernatant after standing for 10 minutes is 11 to 11.9, and excess LiOH determined by titration And the mass of surplus Li 2 CO 3 (surplus LiOH / surplus Li 2 CO 3 ) is 0.45 or less.
上記一般式(1)中、sは、リチウム金属複合酸化物粉末中のNi、Co、MnおよびM1の合計に対するLiの原子比(Li/Me)を示し、リチウム金属複合酸化物粉末の製造工程における、Li添加量を反映する。一般式(1)中、sは、0.95≦s≦1.50であり、好ましくは1.00<s<1.30である。Li量が上記sの範囲である場合、リチウム金属複合酸化物自体の電池容量や出力特性を向上させることができる。
In the above general formula (1), s represents the atomic ratio of Li to the total of Ni, Co, Mn and M 1 in the lithium metal composite oxide powder (Li / Me), and production of the lithium metal composite oxide powder The amount of Li added in the process is reflected. In the general formula (1), s satisfies 0.95 ≦ s ≦ 1.50, and preferably satisfies 1.00 <s <1.30. When the amount of Li is in the range of s, the battery capacity and output characteristics of the lithium metal composite oxide itself can be improved.
通常の製造方法で得られた複合酸化物粉末(例えば、ニッケル複合水酸化物又はニッケル複合酸化物と、リチウム化合物と、を焼成して得られたリチウムニッケル複合酸化物粉末)は、二次粒子や一次粒子の表面に、未反応のリチウム化合物(余剰リチウム化合物)が存在する。余剰リチウム化合物は、正極合材ペースト(以下、「ペースト」ともいう。)中に溶出してpHを上昇させ、ペーストをゲル化させることがある。また、リチウム金属複合酸化物粉末の内部にも余剰リチウムが存在し、ペースト中に溶出してペーストをゲル化させることも考えられる。本発明者らは、ペーストのゲル化を抑制するためには、ペースト中への余剰リチウムの溶出を抑制することが重要であると考え、二次粒子や一次粒子の表面に存在する未反応のリチウム化合物の形態に着目した。
Composite oxide powder obtained by a normal production method (for example, lithium nickel composite oxide powder obtained by firing nickel composite hydroxide or nickel composite oxide and lithium compound) is a secondary particle. In addition, unreacted lithium compounds (surplus lithium compounds) exist on the surfaces of the primary particles. The surplus lithium compound may elute in the positive electrode mixture paste (hereinafter also referred to as “paste”) to raise the pH and cause the paste to gel. It is also conceivable that excess lithium is present inside the lithium metal composite oxide powder and is eluted into the paste to cause the paste to gel. In order to suppress gelation of the paste, the present inventors consider that it is important to suppress elution of excess lithium into the paste, and unreacted particles present on the surfaces of secondary particles and primary particles. We focused on the form of the lithium compound.
二次粒子や一次粒子の表面に存在する余剰リチウム化合物としては、例えば、未反応のLiOH(余剰LiOH)と未反応のLi2CO3(余剰Li2CO3)と、が含まれる。余剰LiOHは、ペースト中へ溶出しやすく、ペーストのpHを上昇させてゲル化を進行させる。また、複合酸化物粉末中の過剰のリチウム(Li)がペースト中へ溶出して、LiOHの形態となってペーストのpHを上昇させてゲル化を進行させることもある。したがって、余剰LiOHとは、ペースト作製時にLiOHの形態となりうるリチウム源をいい、二次粒子や一次粒子の表面の未反応のLiOHや、複合酸化物粉末内部の過剰のリチウムなどを含むものである。一方、余剰Li2CO3は、LiOHよりペースト中へ溶出しにくく、ペーストをゲル化させる作用も小さい。
Examples of the surplus lithium compound existing on the surfaces of the secondary particles and the primary particles include unreacted LiOH (surplus LiOH) and unreacted Li 2 CO 3 (surplus Li 2 CO 3 ). Excess LiOH easily elutes into the paste and raises the pH of the paste to promote gelation. In addition, excessive lithium (Li) in the composite oxide powder may elute into the paste to form LiOH and raise the pH of the paste to cause gelation. Accordingly, surplus LiOH refers to a lithium source that can be in the form of LiOH during paste preparation, and includes secondary particles, unreacted LiOH on the surface of the primary particles, excess lithium inside the composite oxide powder, and the like. On the other hand, surplus Li 2 CO 3 is less likely to elute into the paste than LiOH and has a small effect of gelling the paste.
そこで、本発明者らは、余剰LiOHをLi2CO3に転換して、余剰Li2CO3として固定化することで、ペースト中へのLiOHの溶出を低減し、ペーストのゲル化を抑制することができるのではないかという新規の着想を基に、本発明を完成した。すなわち、本実施形態の正極活物質は、滴定法によって定量される余剰LiOHと余剰Li2CO3の質量の比(LiOH/Li2CO3)が0.45以下であり、好ましくは0.3以下である。LiOH/Li2CO3が上記範囲である場合、ペースト中へのリチウムの溶出が低減され、ペーストのゲル化が抑制され、かつ、正極活物質の反応抵抗(以下、「正極抵抗」ということがある。)をより低い状態にすることができ、より優れた出力特性及びサイクル特性とより高い初期充放電容量とを示す。なお、本実施形態の正極活物質は、常温だけでなく、低温(例えば、-20℃)においても、優れた特性を示す。また、LiOH/Li2CO3の下限は、0.10以上であることが好ましく、0.18以上であることがより好ましい。下限が上記範囲である場合、過度にLiOHが引き抜かれて余剰Li2CO3が生成され過ぎた状態ではないことを示しており、出力特性やサイクル特性を向上させ、特に低温時の出力特性をより向上させることができる。余剰LiOHをLi2CO3に転換して、余剰Li2CO3として固定化することにより、上記のように電池特性を向上させる理由は、限定されないが、以下のように考えられる。
Therefore, the present inventors convert surplus LiOH into Li 2 CO 3 and immobilize it as surplus Li 2 CO 3 , thereby reducing elution of LiOH into the paste and suppressing paste gelation. The present invention has been completed on the basis of a novel idea that it may be possible. That is, the positive electrode active material of this embodiment has a mass ratio (LiOH / Li 2 CO 3 ) of surplus LiOH and surplus Li 2 CO 3 determined by a titration method of 0.45 or less, preferably 0.3. It is as follows. When LiOH / Li 2 CO 3 is in the above range, elution of lithium into the paste is reduced, gelation of the paste is suppressed, and reaction resistance of the positive electrode active material (hereinafter referred to as “positive electrode resistance”) ) Can be brought into a lower state, exhibiting better output and cycle characteristics and higher initial charge / discharge capacity. Note that the positive electrode active material of the present embodiment exhibits excellent characteristics not only at room temperature but also at a low temperature (eg, −20 ° C.). Further, the lower limit of LiOH / Li 2 CO 3 is preferably 0.10 or more, and more preferably 0.18 or more. When the lower limit is in the above range, it indicates that the LiOH is not excessively extracted and excessive Li 2 CO 3 is not generated, and the output characteristics and cycle characteristics are improved. It can be improved further. The reason for improving the battery characteristics as described above by converting surplus LiOH to Li 2 CO 3 and immobilizing it as surplus Li 2 CO 3 is not limited, but is considered as follows.
余剰LiOHは、通常、複合酸化物の二次粒子表面や一次粒子表面に薄く分布している。ここで、一次粒子表面とは、二次粒子の外面で露出している一次粒子の表面だけでなく、二次粒子外部と通じて電解液が浸透可能な二次粒子の表面近傍及び内部の空隙に露出している一次粒子の表面も含むものである。さらに、一次粒子間の粒界であっても一次粒子の結合が不完全で電解液が浸透可能な状態となっていれば一次粒子表面に含まれる。
Surplus LiOH is normally thinly distributed on the secondary particle surface and primary particle surface of the composite oxide. Here, the surface of the primary particle means not only the surface of the primary particle exposed on the outer surface of the secondary particle, but also the space near and inside the surface of the secondary particle through which the electrolyte can penetrate through the outside of the secondary particle. It also includes the surface of the primary particles exposed to the surface. Furthermore, even if it is a grain boundary between primary particles, if the primary particle bonding is incomplete and the electrolyte solution can permeate, it is included in the primary particle surface.
余剰LiOHからのLiの溶出は、電解液との接触面(一次粒子表面)で生じるため、一次粒子表面の余剰LiOHを、余剰Li2CO3へ変換し、固定化することで、Liの溶出を抑制し、ペーストのゲル化を抑制することができる。
Since elution of Li from surplus LiOH occurs at the contact surface (primary particle surface) with the electrolyte, the excess LiOH on the primary particle surface is converted to surplus Li 2 CO 3 and immobilized, thereby elution of Li. And the gelation of the paste can be suppressed.
また、一次粒子表面に存在する余剰LiOHは、複合酸化物の結晶中と電解液の間のLiの移動を阻害する。そこで、余剰LiOHを余剰Li2CO3に変換して一次粒子表面に固定化することにより、余剰LiOH量を減少させることで、一次表面又は二次粒子表面に存在する余剰LiOHが除去され、Liの移動が阻害されなくなり、電池に用いられた際の充放電容量(以下、「電池容量」ともいう。)を向上させることができる。
In addition, excess LiOH present on the surface of the primary particles inhibits Li movement between the complex oxide crystal and the electrolytic solution. Therefore, by converting excess LiOH to excess Li 2 CO 3 and immobilizing it on the primary particle surface, by reducing the amount of excess LiOH, excess LiOH present on the primary surface or secondary particle surface is removed, and Li Is not hindered, and the charge / discharge capacity (hereinafter also referred to as “battery capacity”) when used in a battery can be improved.
さらに、一次粒子表面に存在する余剰LiOHは、余剰Li2CO3として固定化される際、一次粒子表面から一旦除去されて、添加した水分中に溶出した後、余剰Li2CO3として、一次粒子表面に凝集すると考えられる。よって、一次粒子表面を覆う余剰リチウム化合物(余剰LiOH及び余剰Li2CO3を含む)の面積が減少し、電解液と一次粒子表面との接触面が確保されて、Liの移動が促進されることから、正極抵抗を低減し、さらには二次電池の内部抵抗を低減する。
Further, when the excess LiOH present on the primary particle surface is fixed as excess Li 2 CO 3 , it is once removed from the primary particle surface and eluted in the added water, and then as excess Li 2 CO 3 as the primary Li 2 CO 3. It is thought that it aggregates on the particle surface. Therefore, the area of the surplus lithium compound (including surplus LiOH and surplus Li 2 CO 3 ) that covers the primary particle surface is reduced, the contact surface between the electrolyte and the primary particle surface is secured, and the movement of Li is promoted. Therefore, the positive electrode resistance is reduced, and further, the internal resistance of the secondary battery is reduced.
二次電池内の抵抗が低減されることにより、電池内で損失される電圧が減少し、実際に負荷側に印加される電圧が相対的に高くなるため、高出力が得られ、出力特性を向上させることができる。なお、本実施形態の正極活物質は、常温だけでなく、低温(例えば、-20℃)においても、優れた特性を示す。また、負荷側への印加電圧が高くなることにより、正極でのリチウムの挿抜が十分に行われるため、電池容量及びサイクル特性が向上する。さらに、Liの移動が容易になり充放電時に正極活物質が受ける負荷が減少するため、充放電サイクル特性にも優れる。
By reducing the resistance in the secondary battery, the voltage lost in the battery is reduced, and the voltage actually applied to the load side becomes relatively high, so a high output is obtained and the output characteristics are reduced. Can be improved. Note that the positive electrode active material of the present embodiment exhibits excellent characteristics not only at room temperature but also at a low temperature (eg, −20 ° C.). Further, since the voltage applied to the load side is increased, the insertion and extraction of lithium at the positive electrode is sufficiently performed, so that the battery capacity and cycle characteristics are improved. Furthermore, since the movement of Li becomes easy and the load received by the positive electrode active material during charge / discharge is reduced, the charge / discharge cycle characteristics are also excellent.
正極活物質中の余剰LiOHの量は、正極活物質全体に対して0.15質量%以下であることが好ましく、0.12質量%以下であることがより好ましい。余剰LiOHの量が少なくなることで、さらにペーストのゲル化を抑制することができるとともに電池容量をさらに向上させることができる。
The amount of excess LiOH in the positive electrode active material is preferably 0.15% by mass or less, and more preferably 0.12% by mass or less with respect to the entire positive electrode active material. By reducing the amount of excess LiOH, gelation of the paste can be further suppressed and the battery capacity can be further improved.
余剰LiOHの量の下限は、電池特性の低下を抑制するという観点から、正極活物質の全量に対して0.05質量%以上であることが好ましい。余剰LiOHが少なくなり過ぎることは、余剰LiOHがLi2CO3として固定化される際にリチウム金属複合酸化物粒子の結晶中から過剰にリチウムが引き抜かれていることを示す。
The lower limit of the amount of excess LiOH is preferably 0.05% by mass or more with respect to the total amount of the positive electrode active material, from the viewpoint of suppressing deterioration of battery characteristics. When the excess LiOH becomes too small, it indicates that excessive lithium is extracted from the crystal of the lithium metal composite oxide particles when the excess LiOH is fixed as Li 2 CO 3 .
正極活物質中の余剰Li2CO3の量は、正極活物質の表面積に対して0.200×10-2g/m2以下であることが好ましく、0.157×10-2g/m2以下であることがより好ましく、0.155×10-2g/m2以下であることがさらに好ましい。余剰Li2CO3の量が少なくなることで、電解液と一次粒子表面との接触面が増加してLiの移動がより促進され、正極抵抗をさらに低減することができる。なお、正極活物質の表面積に対する余剰Li2CO3の量の下限は、特に限定されず、例えば、0.100×10-2g/m2以上である。
The amount of excess Li 2 CO 3 in the positive electrode active material is preferably 0.200 × 10 −2 g / m 2 or less with respect to the surface area of the positive electrode active material, preferably 0.157 × 10 −2 g / m 2. It is more preferably 2 or less, and further preferably 0.155 × 10 −2 g / m 2 or less. By reducing the amount of surplus Li 2 CO 3 , the contact surface between the electrolytic solution and the primary particle surface is increased, the movement of Li is further promoted, and the positive electrode resistance can be further reduced. The lower limit of the amount of excess Li 2 CO 3 with respect to the surface area of the positive electrode active material is not particularly limited, and is, for example, 0.100 × 10 −2 g / m 2 or more.
本実施形態の正極活物質は、正極活物質5gを100mlの純水に分散させ、10分間静置後の上澄み液を測定した際の25℃におけるpHが11以上11.9以下である。正極活物質5gを100mlの純水に分散させ、10分間静置後の上澄み液のpHを測定することにより、ペースト中へ上記リチウムの溶出の度合いについて評価する。
The positive electrode active material of this embodiment has a pH of 11 or more and 11.9 or less at 25 ° C. when 5 g of the positive electrode active material is dispersed in 100 ml of pure water and the supernatant is measured after standing for 10 minutes. The degree of elution of the lithium into the paste is evaluated by dispersing 5 g of the positive electrode active material in 100 ml of pure water and measuring the pH of the supernatant after standing for 10 minutes.
正極活物質は、上澄み液の25℃におけるpH(以下、単に「正極活物質のpH値」ともいう。)を11以上11.9以下の範囲に制御されることで、ペーストのゲル化が非常に抑制される。pHが11未満である場合、余剰Li2CO3が多く形成され過ぎ、必要以上にリチウム金属複合酸化物中からリチウムが引き抜かれた状態になって、電池の正極に用いられた際に充放電容量の低下や正極の反応抵抗の上昇が生じることがある。リチウムの引き抜きをより低減して正極抵抗をさらに低減させるという観点から、正極活物質のpH値の下限は11.5以上とすることが好ましい。一方、pHが11.9を超えた場合、ペーストとした際のリチウムの溶出が多い状態であり、ペーストのゲル化を抑制することが難しい。リチウムの溶出をより抑制し、ペーストのゲル化をさらに抑制するという観点から、正極活物質のpH値の上限は11.8以下とすることが好ましい。
In the positive electrode active material, the pH of the supernatant liquid at 25 ° C. (hereinafter, also simply referred to as “pH value of the positive electrode active material”) is controlled in the range of 11 or more and 11.9 or less, so that the paste becomes very gelled. To be suppressed. When the pH is less than 11, a large amount of excess Li 2 CO 3 is formed, and when lithium is extracted from the lithium metal composite oxide more than necessary, it is charged and discharged when used for the positive electrode of the battery. The capacity may decrease and the reaction resistance of the positive electrode may increase. From the viewpoint of further reducing lithium extraction and further reducing the positive electrode resistance, the lower limit of the pH value of the positive electrode active material is preferably 11.5 or more. On the other hand, when pH exceeds 11.9, it is in the state where there is much elution of lithium at the time of setting it as a paste, and it is difficult to suppress gelation of a paste. From the viewpoint of further suppressing elution of lithium and further suppressing gelation of the paste, the upper limit of the pH value of the positive electrode active material is preferably 11.8 or less.
リチウム金属複合酸化物粒子は、一次粒子が凝集して構成された二次粒子を含む。また、正極活物質は、単独で存在する一次粒子を含んでもよい。複合酸化物粒子は、一次粒子表面上に、後述するタングステン酸リチウム(LW化合物)を形成させることができる。これにより、充放電容量を維持しながら出力特性を向上させ、さらに良好なサイクル特性を得ることができる。
The lithium metal composite oxide particles include secondary particles composed of aggregated primary particles. Further, the positive electrode active material may include primary particles present alone. The composite oxide particles can form lithium tungstate (LW compound) described later on the primary particle surfaces. Thereby, it is possible to improve the output characteristics while maintaining the charge / discharge capacity, and to obtain better cycle characteristics.
リチウム金属複合酸化物粉末は、一般式(2):LisNi1-x-y-z-tCoxMnyM2
zWtO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、0.0001≦t≦0.03、0.0001≦z+t≦0.10、M2は、V、Mg、Mo、Nb、Ti、およびAlから選ばれる少なくとも1種の元素)で表されるものであることが好ましい。
Lithium metal composite oxide powder represented by the general formula (2): Li s Ni 1 -x-y-z-t Co x Mn y M 2 z W t O 2 ( however, 0.05 ≦ x ≦ 0.35, 0 ≦ y ≦ 0.35, 0 ≦ z ≦ 0.10, 0.95 ≦ s ≦ 1.50, 0.0001 ≦ t ≦ 0.03, 0.0001 ≦ z + t ≦ 0.10, M 2 is It is preferable that it is represented by at least one element selected from V, Mg, Mo, Nb, Ti, and Al.
上記一般式(2)中、tは、リチウム金属複合酸化物に添加されたタングステン(W)量を示す。一般式(2)中、tは、0.0001≦t≦0.03であり、好ましくは0.0003≦t≦0.02であり、より好ましくは0.0003≦t≦0.012である。Wを上記tの範囲で含む場合、リチウム金属複合酸化物自体の電池容量や出力特性を向上させることができることに加え、余剰LiOHがLi2CO3に変換されて一次粒子の表面に固定化される際に、添加した水に溶出したWが、水に溶出した余剰リチウムと反応し、タングステン酸リチウムが形成されて正極抵抗を低減することができる。
In the general formula (2), t represents the amount of tungsten (W) added to the lithium metal composite oxide. In the general formula (2), t is 0.0001 ≦ t ≦ 0.03, preferably 0.0003 ≦ t ≦ 0.02, and more preferably 0.0003 ≦ t ≦ 0.012. . When W is included in the above range t, in addition to improving the battery capacity and output characteristics of the lithium metal composite oxide itself, excess LiOH is converted to Li 2 CO 3 and immobilized on the surface of the primary particles. In this case, W eluted in the added water reacts with excess lithium eluted in the water, and lithium tungstate is formed, so that the positive electrode resistance can be reduced.
上記一般式(2)中、sは、リチウム金属複合酸化物粉末中のNi、Co、Mn、M2およびWの合計に対するLiの原子比(Li/Me)を示し、リチウム金属複合酸化物粉末の製造工程における、Li添加量を反映する。上記一般式(2)中のsは、上述の一般式(1)中のsと同様の範囲とすることが好ましい。
In the general formula (2), s represents the atomic ratio of Li to the total of Ni, Co, Mn, M 2 and W (Li / Me) in the lithium metal composite oxide powder, and the lithium metal composite oxide powder This reflects the amount of Li added in the manufacturing process. S in the general formula (2) is preferably in the same range as s in the general formula (1).
正極活物質の粉体特性及び粒子構造も電池に要求される特性に応じて公知のリチウム金属複合酸化物から選択できる。例えば、正極活物質の平均粒径は3μm以上15μm以下の範囲にあり、粒度分布の広がりを示す指標である〔(d90-d10)/平均粒径〕は0.7以下であることが好ましい。これにより、充填性を高めて、電池の容積当たりの電池容量をより高いものとすることができる。また、リチウム金属複合酸化物粒子間の印加電圧を均一化し、粒子間での負荷を均一化してサイクル特性をさらに高めることができる。
The powder characteristics and particle structure of the positive electrode active material can also be selected from known lithium metal composite oxides according to the characteristics required for the battery. For example, the average particle diameter of the positive electrode active material is in the range of 3 μm or more and 15 μm or less, and [(d90−d10) / average particle diameter], which is an index indicating the spread of the particle size distribution, is preferably 0.7 or less. Thereby, filling property can be improved and the battery capacity per volume of a battery can be made higher. Further, the applied voltage between the lithium metal composite oxide particles can be made uniform, the load between the particles can be made uniform, and the cycle characteristics can be further improved.
なお、上記d10は、各粒径における粒子数を粒径の小さい側から累積し、その累積体積が全粒子の合計体積の10%となる粒径を意味している。また、上記d90は、同様に粒子数を累積し、その累積体積が全粒子の合計体積の90%となる粒径を意味している。平均粒径や、d10及びd90は、レーザー光回折散乱式粒度分析計で測定した体積積算値から求めることができる。平均粒径としては体積基準平均径Mvを用い、d10及びd90と同様にレーザー光回折散乱式粒度分析計を用いて求めることができる。
The d10 means a particle size in which the number of particles in each particle size is accumulated from the smaller particle size side and the accumulated volume becomes 10% of the total volume of all particles. D90 means a particle diameter in which the number of particles is similarly accumulated and the accumulated volume is 90% of the total volume of all particles. The average particle diameter, d10 and d90 can be obtained from the volume integrated value measured with a laser light diffraction / scattering particle size analyzer. The average particle diameter Mv can be used as the average particle diameter, and can be determined using a laser light diffraction / scattering particle size analyzer in the same manner as d10 and d90.
また、複合酸化物粉末の断面観察において計測される空隙が占める面積割合(空隙率)は、二次粒子の断面積全体の4.5%以上60%以下であることが好ましい。空隙率が上記範囲である場合、ペーストのゲル化を抑制しながら、正極抵抗の低減効果をより高くすることができる。空隙率が断面積全体の4.5%未満である場合、正極抵抗のより高い低減効果が得られないことがある。一方、空隙率が60%を超える場合、充填密度が低下して、電池の容積当たりの電池容量が十分に得られないことがある。なお、二次粒子の断面積全体とは、二次粒子中の空隙を含む断面積である。
In addition, the area ratio (porosity) occupied by the voids measured in the cross-sectional observation of the composite oxide powder is preferably 4.5% or more and 60% or less of the entire cross-sectional area of the secondary particles. When the porosity is in the above range, the positive electrode resistance reduction effect can be further increased while suppressing gelation of the paste. When the porosity is less than 4.5% of the entire cross-sectional area, a higher reduction effect of the positive electrode resistance may not be obtained. On the other hand, when the porosity exceeds 60%, the packing density may decrease, and the battery capacity per battery volume may not be sufficiently obtained. In addition, the whole cross-sectional area of a secondary particle is a cross-sectional area including the space | gap in a secondary particle.
空隙率は、二次粒子の任意断面を、走査型電子顕微鏡を用いて観察し、画像解析することによって測定できる。具体的には、複数の複合酸化物粒子を樹脂などに埋め込み、クロスセクションポリッシャ加工などにより断面試料を作製し、走査型電子顕微鏡により二次粒子の断面観察が可能な状態とした後、画像解析ソフト(例えば、WinRoof 6.1.1等)により、任意の20個以上の二次粒子に対して、二次粒子中の空隙の部分を黒で検出し、二次粒子の輪郭内の緻密部を白で検出し、上記20個以上の二次粒子の黒部分および白部分の合計面積を測定し、[黒部分/(黒部分+白部分)]の面積比を計算することで空隙率を算出できる。
The porosity can be measured by observing an arbitrary cross section of the secondary particles using a scanning electron microscope and analyzing the image. Specifically, a plurality of composite oxide particles are embedded in a resin, a cross-section polisher is used to prepare a cross-section sample, and the secondary electron cross-section can be observed with a scanning electron microscope, followed by image analysis. With software (for example, WinRoof 6.1.1 etc.), the void part in the secondary particle is detected in black for any 20 or more secondary particles, and the dense part in the contour of the secondary particle Is detected in white, the total area of the black part and the white part of the 20 or more secondary particles is measured, and the porosity is calculated by calculating the area ratio of [black part / (black part + white part)]. It can be calculated.
正極活物質の比表面積は、1m2/g以上50m2/g以下であることが好ましい。比表面積が1m2/g未満では、電解液との接触が少なく、高い出力特性が得られないことがある。また、比表面積が50m2/gを超えると、電解液との接触が多くなり過ぎ、ゲル化の抑制が十分でないことがある。なお、比表面積は、窒素ガス吸着によるBET法で求めることができる。
The specific surface area of the positive electrode active material is preferably 1 m 2 / g or more and 50 m 2 / g or less. When the specific surface area is less than 1 m 2 / g, there is little contact with the electrolytic solution, and high output characteristics may not be obtained. Moreover, when a specific surface area exceeds 50 m < 2 > / g, contact with electrolyte solution increases too much and suppression of gelatinization may not be enough. The specific surface area can be determined by the BET method using nitrogen gas adsorption.
正極活物質の水分率は、0.5質量%以下が好ましく、0.3質量%以下がより好ましい。正極活物質の水分率を0.5質量%以下とすることで、大気中の炭素、硫黄を含むガス成分を吸収して表面に膜状のリチウム化合物を生成することを抑制し、優れた電池特性を得ることができる。なお、上記水分率の測定値は、気化温度300℃の条件においてカールフィッシャー水分計で測定した場合の測定値である。なお、水分率の下限は、0.01質量%以上である。
The moisture content of the positive electrode active material is preferably 0.5% by mass or less, and more preferably 0.3% by mass or less. By controlling the moisture content of the positive electrode active material to 0.5% by mass or less, it is possible to suppress the formation of a film-like lithium compound on the surface by absorbing gas components including carbon and sulfur in the atmosphere, and an excellent battery. Characteristics can be obtained. In addition, the measured value of the said moisture rate is a measured value at the time of measuring with a Karl Fischer moisture meter on condition of vaporization temperature of 300 degreeC. In addition, the minimum of a moisture content is 0.01 mass% or more.
(2)非水系電解質二次電池用正極活物質の製造方法
正極活物質の製造方法は、層状構造の結晶構造を有するリチウム金属複合酸化物からなる焼成粉末と、水と、を混合すること(ステップS1)と、前記混合して得られた混合物を乾燥すること(ステップS2)と、を備える。以下、各ステップについて図面を参照して説明する。 (2) Method for Producing Positive Electrode Active Material for Nonaqueous Electrolyte Secondary Battery The method for producing the positive electrode active material comprises mixing a fired powder made of a lithium metal composite oxide having a layered crystal structure and water ( Step S1) and drying the mixture obtained by the mixing (Step S2). Hereinafter, each step will be described with reference to the drawings.
正極活物質の製造方法は、層状構造の結晶構造を有するリチウム金属複合酸化物からなる焼成粉末と、水と、を混合すること(ステップS1)と、前記混合して得られた混合物を乾燥すること(ステップS2)と、を備える。以下、各ステップについて図面を参照して説明する。 (2) Method for Producing Positive Electrode Active Material for Nonaqueous Electrolyte Secondary Battery The method for producing the positive electrode active material comprises mixing a fired powder made of a lithium metal composite oxide having a layered crystal structure and water ( Step S1) and drying the mixture obtained by the mixing (Step S2). Hereinafter, each step will be described with reference to the drawings.
図1は、本実施形態の非水系電解質二次電池用正極活物質の製造方法(以下、単に「正極活物質の製造方法」ともいう。)の一例を示す図である。なお、以下の説明は、製造方法の一例であって、この方法に限定するものではない。
FIG. 1 is a view showing an example of a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to the present embodiment (hereinafter also simply referred to as “a method for producing a positive electrode active material”). In addition, the following description is an example of a manufacturing method, Comprising: It does not limit to this method.
図1に示すように、正極活物質の製造方法は、まず、層状構造の結晶構造を有するリチウム金属複合酸化物からなる焼成粉末と、水と、を混合する(ステップS1)。この際、得られる正極活物質5gを100mlの純水に分散させ、10分間静置後の上澄み液を測定した際の25℃におけるpH(以下、単に「正極活物質のpH値」ともいう。)が11以上11.9以下の範囲となる量の水を、混合する。
As shown in FIG. 1, in the method for producing a positive electrode active material, first, a fired powder made of a lithium metal composite oxide having a layered crystal structure and water are mixed (step S1). At this time, 5 g of the obtained positive electrode active material was dispersed in 100 ml of pure water, and the pH at 25 ° C. when the supernatant liquid after standing for 10 minutes was measured (hereinafter also simply referred to as “pH value of the positive electrode active material”). ) Is mixed with an amount of water in the range of 11 to 11.9.
混合工程(ステップS1)では、正極活物質のpH値が11以上11.9以下の範囲となるように焼成粉末と水とを混合する。混合工程において、所定量の水を混合することにより、得られた正極活物質を用いたペーストにおいて、ペースト中へのリチウムの溶出が抑制される。この理由は、限定されないが、後述する乾燥工程(ステップS2)において、水に溶出された余剰LiOHと雰囲気中の炭酸ガスとが反応し、焼成粉末中の余剰LiOHをLi2CO3へ変換することにより、余剰LiOH由来のリチウムが一次粒子表面への固定化されることが一因と考えられる。
In the mixing step (step S1), the fired powder and water are mixed so that the positive electrode active material has a pH value in the range of 11 to 11.9. In the mixing step, by mixing a predetermined amount of water, elution of lithium into the paste is suppressed in the paste using the obtained positive electrode active material. Although this reason is not limited, in the drying process (step S2) described later, surplus LiOH eluted in water reacts with carbon dioxide in the atmosphere to convert surplus LiOH in the fired powder into Li 2 CO 3 . Thus, it is considered that the excess LiOH-derived lithium is immobilized on the surface of the primary particles.
また、リチウムの引き抜きをより低減して正極抵抗をさらに低減させるという観点から、正極活物質のpH値の下限は、11.5以上となるように水を混合することが好ましい。一方、リチウムの溶出をより抑制し、ペーストのゲル化をさらに抑制するという観点から、pH値の上限は、11.8以下となるように水を混合することが好ましい。
Further, from the viewpoint of further reducing lithium extraction and further reducing the positive electrode resistance, it is preferable to mix water so that the lower limit of the pH value of the positive electrode active material is 11.5 or more. On the other hand, from the viewpoint of further suppressing the elution of lithium and further suppressing the gelation of the paste, it is preferable to mix water so that the upper limit of the pH value is 11.8 or less.
焼成粉末と水との混合は、例えば、焼成粉末に水を添加して、混合することにより行うことができる。水の添加量については、予め少量の焼成粉末を分取して予備試験を行って水の添加量を確認することで、容易に決めることができる。また、Li/Meや焼成粉の製造条件が安定すれば、予備試験で決めた添加量により上述の範囲に正極活物質のpH値を制御することができる。
The mixing of the fired powder and water can be performed, for example, by adding water to the fired powder and mixing. The amount of water added can be easily determined by collecting a small amount of the fired powder in advance and conducting a preliminary test to confirm the amount of water added. Moreover, if the manufacturing conditions of Li / Me and baked powder are stabilized, the pH value of the positive electrode active material can be controlled within the above-described range by the addition amount determined in the preliminary test.
水の添加の方法は、特に限定されず、焼成粉末に水を滴下してもよく、焼成粉末に水を噴霧により添加してもよい。中でも、焼成粉末に水を1μm以上2000μm以下の液滴サイズに噴霧して添加することが好ましい。水を微細な液滴で噴霧して添加することにより、焼成粉末により均一に水を添加することができ、余剰LiOHと雰囲気中の炭酸ガスの反応をより均一化でき、より高い出力向上効果及びゲル化抑制効果を得ることが可能となる。水の噴霧方法としては、各種スプレーや超音波加湿装置を用いることができる。噴霧する際の水の液滴サイズは、1μm以上2000μm以下であること好ましく、5μm以上1000μm以下であることがより好ましい。
The method for adding water is not particularly limited, and water may be added dropwise to the fired powder, or water may be added to the fired powder by spraying. In particular, it is preferable to add water by spraying the fired powder to a droplet size of 1 μm to 2000 μm. By adding water by spraying with fine droplets, water can be added uniformly by the calcined powder, the reaction between excess LiOH and carbon dioxide in the atmosphere can be made more uniform, and a higher output improvement effect and It becomes possible to obtain the gelation suppressing effect. Various sprays and ultrasonic humidifiers can be used as the water spraying method. The droplet size of water when spraying is preferably 1 μm or more and 2000 μm or less, and more preferably 5 μm or more and 1000 μm or less.
また、焼成粉末と水との混合は、焼成粉末水を添加した後、混合してもよく、水を添加しながら混合してもよいが、水の添加をより均一化するため、水を添加しながら混合することがより好ましい。
In addition, the mixture of the baked powder and water may be mixed after adding the baked powder water, or may be mixed while adding water, but in order to make the addition of water more uniform, water is added. It is more preferable to mix them.
なお、余剰LiOH量は、リチウム金属複合酸化物の焼成粉末におけるNi、Co、MnおよびMの合計に対するLiの原子比(Li/Me)、あるいは該焼成粉末の製造条件によって変動する。水の添加量は、これらの余剰LiOHを固定化して正極活物質のpH値が上述の範囲に制御できる量とすればよい。したがって、正極活物質のpH値が11以上11.9以下となる範囲で水を添加すればよい。
The surplus LiOH amount varies depending on the atomic ratio of Li to the total of Ni, Co, Mn, and M (Li / Me) in the sintered powder of lithium metal composite oxide, or the production conditions of the sintered powder. The amount of water added may be an amount that allows the pH value of the positive electrode active material to be controlled within the above range by immobilizing these excess LiOH. Therefore, water may be added in a range where the pH value of the positive electrode active material is 11 or more and 11.9 or less.
混合工程(ステップS1)において混合する水の量は、焼成粉末の粉体特性や粒子構造に応じて、適宜調整することができるが、例えば、焼成粉末に対して1質量%以上35質量%以下とすることが好ましい。これにより、余剰LiOHを固定化して、リチウムの溶出をさらに低減することができる。また、水を十分な量として、リチウム金属複合酸化物粒子の内部の一次粒子表面まで十分に浸透させるとともにリチウム金属複合酸化物粒子間でも余剰LiOHの固定化を均一に進行させることができ、電池容量や出力特性をさらに向上させることができる。また、水を混合する量は、焼成粉末に対して1質量%以上6質量%以下とすることがさらに好ましい。水を混合する量を最適化することで、余剰LiOHを固定化しながら、過剰にリチウムが引き抜かれた状態になることをさらに防止し、常温及び低温時の出力特性向上の効果を最大化することが可能となる。
The amount of water to be mixed in the mixing step (step S1) can be appropriately adjusted according to the powder characteristics and particle structure of the fired powder. It is preferable that Thereby, excess LiOH can be fixed and the elution of lithium can be further reduced. Further, with sufficient amount of water, the lithium metal composite oxide particles can be sufficiently permeated to the surface of primary particles inside the lithium metal composite oxide particles, and the fixation of surplus LiOH can be promoted uniformly between the lithium metal composite oxide particles. Capacity and output characteristics can be further improved. The amount of water mixed is more preferably 1% by mass or more and 6% by mass or less with respect to the fired powder. By optimizing the amount of water to be mixed, it is possible to further prevent lithium from being pulled out excessively while fixing excess LiOH, and to maximize the effect of improving the output characteristics at room temperature and low temperature. Is possible.
なお、焼成粉末は、該焼成粉末の組成や製造条件によって表面積が変動することがある。したがって、焼成粉末の表面積が変動しても好ましい量の水を供給するため、表面積に対して0.003g/m2以上0.025g/m2以下の範囲で水を混合することがより好ましい。
The surface area of the fired powder may vary depending on the composition of the fired powder and the manufacturing conditions. Accordingly, the surface area of the calcined powder to supply desired amounts of water may vary, it is more preferable to mix the water with 0.003 g / m 2 or more 0.025 g / m 2 or less of the range of the surface area.
なお、リチウム金属複合酸化物の焼成粉末の上記pH値が11以上11.9以下である場合においても、水を混合することにより、一次粒子表面でLi2CO3化による凝集が進み、上記ペーストの安定化及び電池容量や出力特性の向上という効果を得ることができる。この場合、水は、得られる正極活物質のpHが11以上11.9以下の範囲となる量を混合すればよく、その混合量は特に限定されないが、例えば、焼成粉末に対して1質量%以上の水を混合することができる。
Even when the pH value of the fired powder of the lithium metal composite oxide is 11 or more and 11.9 or less, by mixing water, aggregation by Li 2 CO 3 formation proceeds on the primary particle surface, and the paste The effect of stabilizing the battery capacity and improving the battery capacity and output characteristics can be obtained. In this case, water should just mix the quantity from which the pH of the positive electrode active material obtained becomes the range of 11-11. The mixing amount is not specifically limited, For example, 1 mass% with respect to baked powder, for example The above water can be mixed.
焼成粉末は、一般式(1):LisNi1-x-y-zCoxMnyM1
zO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、Mは、V、Mg、Mo、Nb、Ti、WおよびAlから選ばれる少なくとも1種の元素)で表され、一次粒子が凝集して形成された二次粒子を含む。焼成粉末の粉体特性や粒子構造は、正極活物質まで継承されるため、焼成粉末の組成、粉体特性及び粒子構造などは、上述した正極活物質と同様のものとすることができる。また、焼成粉末は、得ようとする正極活物質に合わせて選択される。
The calcined powder has the general formula (1): Li s Ni 1-xyz Co x Mn y M 1 z O 2 (where 0.05 ≦ x ≦ 0.35, 0 ≦ y ≦ 0.35, 0 ≦ z ≦ 0.10, 0.95 ≦ s ≦ 1.50, M is represented by at least one element selected from V, Mg, Mo, Nb, Ti, W and Al), and the primary particles are Secondary particles formed by aggregation are included. Since the powder characteristics and particle structure of the fired powder are inherited up to the positive electrode active material, the composition, powder characteristics, particle structure and the like of the fired powder can be the same as those of the positive electrode active material described above. Further, the fired powder is selected according to the positive electrode active material to be obtained.
焼成粉末は、一般式(2):LisNi1-x-y-z-tCoxMnyM2
zWtO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、0.0001≦t≦0.03、0.0001≦z+t≦0.10、Mは、V、Mg、Mo、Nb、TiおよびAlから選ばれる少なくとも1種の元素)で表されるものであることが好ましい。また、一般式(2)中、タングステン(W)量を示すtは、0.0001≦t≦0.03であり、好ましくは0.0003≦t≦0.02であり、より好ましくは0.0003≦t≦0.012である。焼成粉末に添加されたWは、混合工程において添加された水に溶出し、同様に水に溶出しているリチウムと乾燥工程において反応して一次粒子表面上にタングステン酸リチウムを形成する。タングステン酸リチウムによって、正極抵抗が低減され、出力特性がさらに向上する。
Baking powder, formula (2): Li s Ni 1 -x-y-z-t Co x Mn y M 2 z W t O 2 ( however, 0.05 ≦ x ≦ 0.35,0 ≦ y ≦ 0.35, 0 ≦ z ≦ 0.10, 0.95 ≦ s ≦ 1.50, 0.0001 ≦ t ≦ 0.03, 0.0001 ≦ z + t ≦ 0.10, M is V, Mg, Mo And at least one element selected from Nb, Ti, and Al). In the general formula (2), t indicating the amount of tungsten (W) is 0.0001 ≦ t ≦ 0.03, preferably 0.0003 ≦ t ≦ 0.02, and more preferably 0.00. 0003 ≦ t ≦ 0.012. W added to the calcined powder is eluted in the water added in the mixing step and similarly reacts with lithium eluted in the water in the drying step to form lithium tungstate on the surface of the primary particles. Lithium tungstate reduces the positive electrode resistance and further improves the output characteristics.
焼成粉末の好ましい態様として、上記正極活物質と同様に、平均粒径は3μm以上15μm以下の範囲にあり、粒度分布の広がりを示す指標である〔(d90-d10)/平均粒径〕は0.7以下が選択できる。なお、〔(d90-d10)/平均粒径〕の下限は特に限定されないが、0.25以上程度である。また、焼成粉末の断面観察において計測される空隙が占める面積割合(空隙率)が該リチウム金属複合酸化物粒子の断面積の4.5%以上60%以下であることが好ましい。
As a preferred embodiment of the fired powder, like the positive electrode active material, the average particle diameter is in the range of 3 μm to 15 μm, and is an index indicating the spread of the particle size distribution [(d90−d10) / average particle diameter] is 0. .7 or less can be selected. The lower limit of [(d90−d10) / average particle diameter] is not particularly limited, but is about 0.25 or more. Moreover, it is preferable that the area ratio (void ratio) which the space | gap measured in the cross-sectional observation of baking powder occupies is 4.5% or more and 60% or less of the cross-sectional area of this lithium metal complex oxide particle.
焼成粉末と水との混合に用いられる装置は、特に限定されず、公知の装置を用いることができ、例えばシェーカーミキサーやレーディゲミキサー、ジュリアミキサー、Vブレンダーなどの混合機を用いて混合することができ、焼成粉末と水分とが十分に混合されればよい。
An apparatus used for mixing the baked powder and water is not particularly limited, and a known apparatus can be used. For example, the mixing is performed using a mixer such as a shaker mixer, a Laedige mixer, a Julia mixer, or a V blender. It is only necessary that the calcined powder and moisture be sufficiently mixed.
次いで、混合して得られた混合物を乾燥する(ステップS2)。このステップは、水と焼成粉末とを混合した混合物を乾燥させ、この混合物中の水に溶解している余剰LiOH(リチウム金属複合酸化物粒子中の過剰なリチウムを含む)を、一次粒子表面上に微細な凝集物として形成させる。この過程において、余剰LiOHは、雰囲気中の炭酸ガス(CO2)と反応してLi2CO3となり、余剰Li2CO3として、一次粒子表面上に固定化される。さらに、余剰LiOHが一次粒子表面上に薄く広範囲に分布している状態から、余剰Li2CO3が微細な凝集物を形成して点在する状態に変化することから、一次粒子表面と電解液との接触が確保され、Liイオンのインターカレーション反応の反応場が増加する。余剰Li2CO3の点在化による余剰LiOHの除去は、リチウム金属複合酸化物粒子の比表面積が増加により確認される。
Next, the mixture obtained by mixing is dried (step S2). This step dries the mixture of water and calcined powder, and removes excess LiOH (including excess lithium in the lithium metal composite oxide particles) dissolved in water in the mixture on the surface of the primary particles. To form fine aggregates. In this process, surplus LiOH reacts with carbon dioxide gas (CO 2 ) in the atmosphere to become Li 2 CO 3 and is immobilized on the primary particle surface as surplus Li 2 CO 3 . Furthermore, since the surplus LiOH changes from a thin and widely distributed state on the primary particle surface to a state where surplus Li 2 CO 3 forms fine aggregates and is scattered, the primary particle surface and the electrolyte solution are changed. And the reaction field of Li ion intercalation reaction is increased. The removal of excess LiOH due to the dispersion of excess Li 2 CO 3 is confirmed by an increase in the specific surface area of the lithium metal composite oxide particles.
乾燥温度は、450℃以下とすることが好ましい。450℃を超えると、リチウム金属複合酸化物の結晶内から、さらにリチウムが遊離してペーストのゲル化抑制が十分でない場合がある。より十分に乾燥させ、リチウム金属複合酸化物からのリチウムの遊離を防止するという観点から、乾燥温度は100℃以上300℃以下とすることがより好ましい。乾燥時間は、特に限定されないが、1時間以上24時間以下とすることができる。
The drying temperature is preferably 450 ° C. or lower. When it exceeds 450 ° C., lithium may further be liberated from the crystal of the lithium metal composite oxide, and the gelation of the paste may not be sufficiently suppressed. From the viewpoint of drying more sufficiently and preventing the liberation of lithium from the lithium metal composite oxide, the drying temperature is more preferably 100 ° C. or higher and 300 ° C. or lower. The drying time is not particularly limited, but can be 1 hour or more and 24 hours or less.
また、乾燥時の雰囲気は、雰囲気中の水分や炭酸とリチウム金属複合酸化物粒子の表面のリチウムの過剰な反応を避けるため、必要に応じて炭酸ガスの含有量が制御された脱炭酸空気、不活性ガスまたは真空雰囲気とすることができるが、大気雰囲気とすることが好ましい。炭酸ガスの含有量としては、100容量ppm以上、500容量ppm以下とすることが好ましい。さらに、乾燥時の雰囲気の圧力は1気圧以下とすることが好ましい。1気圧よりも気圧が高い場合には、正極活物質の水の含有量が十分に下がらない恐れがある。乾燥時の雰囲気の圧力を、減圧雰囲気とした場合(例えば、-90kPa程度)、より正極活物質の水分率を低下させることができ、得られる二次電池の正極抵抗を減少させることができる。
In addition, the atmosphere during drying is decarboxylated air in which the content of carbon dioxide gas is controlled as necessary in order to avoid excessive reaction of moisture in the atmosphere and carbon and lithium on the surface of the lithium metal composite oxide particles, An inert gas or a vacuum atmosphere can be used, but an air atmosphere is preferable. The content of carbon dioxide gas is preferably 100 ppm to 500 ppm by volume. Furthermore, the pressure of the atmosphere during drying is preferably 1 atm or less. When the atmospheric pressure is higher than 1 atm, the water content of the positive electrode active material may not be sufficiently lowered. When the pressure of the atmosphere at the time of drying is a reduced pressure atmosphere (for example, about −90 kPa), the moisture content of the positive electrode active material can be further reduced, and the positive electrode resistance of the obtained secondary battery can be reduced.
(3)非水系電解質二次電池用正極合材ペースト
本実施形態の正極合材ペースト中では、正極活物質からのリチウムの溶出が低減され、ペーストのゲル化が抑制される。したがって、正極合材ペーストは、長期間の保存でもペーストの粘度変化が少なく、高い安定性を有する。このようなペーストを用いて正極を製造することで、正極も安定して優れた特性を有するものとなり、最終的に得られる電池の特性を安定して高いものとすることができる。 (3) Positive electrode mixture paste for non-aqueous electrolyte secondary battery In the positive electrode mixture paste of this embodiment, elution of lithium from the positive electrode active material is reduced, and gelation of the paste is suppressed. Therefore, the positive electrode mixture paste has a high stability with little change in the viscosity of the paste even after long-term storage. By producing a positive electrode using such a paste, the positive electrode also has stable and excellent characteristics, and the characteristics of the finally obtained battery can be made stable and high.
本実施形態の正極合材ペースト中では、正極活物質からのリチウムの溶出が低減され、ペーストのゲル化が抑制される。したがって、正極合材ペーストは、長期間の保存でもペーストの粘度変化が少なく、高い安定性を有する。このようなペーストを用いて正極を製造することで、正極も安定して優れた特性を有するものとなり、最終的に得られる電池の特性を安定して高いものとすることができる。 (3) Positive electrode mixture paste for non-aqueous electrolyte secondary battery In the positive electrode mixture paste of this embodiment, elution of lithium from the positive electrode active material is reduced, and gelation of the paste is suppressed. Therefore, the positive electrode mixture paste has a high stability with little change in the viscosity of the paste even after long-term storage. By producing a positive electrode using such a paste, the positive electrode also has stable and excellent characteristics, and the characteristics of the finally obtained battery can be made stable and high.
正極合材ペーストは、上記正極活物質を含むことが特徴であり、他の構成材料は通常の正極合材ペーストと同等のものが用いられる。例えば、溶剤を除いた正極合材の固形分の全質量を100質量部とした場合、一般の非水系電解質二次電池の正極と同様、正極活物質の含有量を60~95質量部とし、導電剤の含有量を1~20質量部とし、結着剤の含有量を1~20質量部とすることが好ましい。
The positive electrode mixture paste is characterized by containing the positive electrode active material, and the other constituent materials are the same as those of a normal positive electrode mixture paste. For example, when the total mass of the solid content of the positive electrode mixture excluding the solvent is 100 parts by mass, the content of the positive electrode active material is 60 to 95 parts by mass in the same manner as the positive electrode of a general non-aqueous electrolyte secondary battery, It is preferable that the content of the conductive agent is 1 to 20 parts by mass and the content of the binder is 1 to 20 parts by mass.
また、導電剤としては、例えば、黒鉛(天然黒鉛、人造黒鉛、膨張黒鉛など)や、アセチレンブラック、ケッチェンブラックなどのカーボンブラック系材料などを用いることができる。
Further, as the conductive agent, for example, graphite (natural graphite, artificial graphite, expanded graphite, etc.), carbon black materials such as acetylene black, ketjen black, and the like can be used.
結着剤は、活物質粒子をつなぎ止める役割を果たすもので、例えば、ポリフッ化ビニリデン(PVDF)、ポリテトラフルオロエチレン(PTFE)、フッ素ゴム、エチレンプロピレンジエンゴム、スチレンブタジエン、セルロース系樹脂、ポリアクリル酸などを用いることができる。
The binder plays a role of anchoring the active material particles. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluorine rubber, ethylene propylene diene rubber, styrene butadiene, cellulose resin, polyacrylic, and the like. An acid or the like can be used.
なお、必要に応じ、正極活物質、導電剤、活性炭を分散させ、結着剤を溶解する溶剤を正極合材に添加する。溶剤としては、具体的には、N-メチル-2-ピロリドン等の有機溶剤を用いることができる。また、正極合材には、電気二重層容量を増加させるために、活性炭を添加することができる。
If necessary, a positive electrode active material, a conductive agent, and activated carbon are dispersed, and a solvent that dissolves the binder is added to the positive electrode mixture. Specifically, an organic solvent such as N-methyl-2-pyrrolidone can be used as the solvent. Activated carbon can be added to the positive electrode mixture in order to increase the electric double layer capacity.
粉末状の正極活物質、導電剤、結着剤を混合し、さらに必要に応じて活性炭、粘度調整等の目的の溶剤を添加し、これを混練して正極合材ペーストを作製する。
A powdered positive electrode active material, a conductive agent, and a binder are mixed, and, if necessary, a target solvent such as activated carbon and viscosity adjustment is added and kneaded to prepare a positive electrode mixture paste.
(4)非水系電解質二次電池
本実施形態の非水系電解質二次電池は、正極、負極および非水系電解液などからなり、一般の非水系電解質二次電池と同様の構成要素により構成される。なお、以下で説明する実施形態は例示に過ぎず、本実施形態の非水系電解質二次電池は、本明細書に記載されている実施形態を基に、当業者の知識に基づいて種々の変更、改良を施した形態で実施することができる。また、本実施形態の非水系電解質二次電池は、その用途を特に限定するものではない。 (4) Non-aqueous electrolyte secondary battery The non-aqueous electrolyte secondary battery according to the present embodiment includes a positive electrode, a negative electrode, a non-aqueous electrolyte, and the like, and includes the same components as those of a general non-aqueous electrolyte secondary battery. . Note that the embodiment described below is merely an example, and the nonaqueous electrolyte secondary battery of the present embodiment can be variously modified based on the knowledge of those skilled in the art based on the embodiment described in the present specification. It can be implemented in an improved form. Further, the use of the nonaqueous electrolyte secondary battery of the present embodiment is not particularly limited.
本実施形態の非水系電解質二次電池は、正極、負極および非水系電解液などからなり、一般の非水系電解質二次電池と同様の構成要素により構成される。なお、以下で説明する実施形態は例示に過ぎず、本実施形態の非水系電解質二次電池は、本明細書に記載されている実施形態を基に、当業者の知識に基づいて種々の変更、改良を施した形態で実施することができる。また、本実施形態の非水系電解質二次電池は、その用途を特に限定するものではない。 (4) Non-aqueous electrolyte secondary battery The non-aqueous electrolyte secondary battery according to the present embodiment includes a positive electrode, a negative electrode, a non-aqueous electrolyte, and the like, and includes the same components as those of a general non-aqueous electrolyte secondary battery. . Note that the embodiment described below is merely an example, and the nonaqueous electrolyte secondary battery of the present embodiment can be variously modified based on the knowledge of those skilled in the art based on the embodiment described in the present specification. It can be implemented in an improved form. Further, the use of the nonaqueous electrolyte secondary battery of the present embodiment is not particularly limited.
(a)正極
先に述べた非水系電解質二次電池用正極活物質、さらに正極合材ペーストを用いて、例えば、以下のようにして、非水系電解質二次電池の正極を作製する。 (A) Positive electrode Using the positive electrode active material for a non-aqueous electrolyte secondary battery described above and the positive electrode mixture paste, for example, a positive electrode of a non-aqueous electrolyte secondary battery is produced as follows.
先に述べた非水系電解質二次電池用正極活物質、さらに正極合材ペーストを用いて、例えば、以下のようにして、非水系電解質二次電池の正極を作製する。 (A) Positive electrode Using the positive electrode active material for a non-aqueous electrolyte secondary battery described above and the positive electrode mixture paste, for example, a positive electrode of a non-aqueous electrolyte secondary battery is produced as follows.
正極合材ペーストを、例えば、アルミニウム箔製の集電体の表面に塗布し、乾燥して、溶剤を飛散させる。必要に応じ、電極密度を高めるべく、ロールプレス等により加圧することもある。このようにして、シート状の正極を作製することができる。シート状の正極は、目的とする電池に応じて適当な大きさに裁断等をして、電池の作製に供することができる。ただし、正極の作製方法は、例示のものに限られることなく、他の方法によってもよい。
The positive electrode mixture paste is applied to, for example, the surface of a current collector made of aluminum foil and dried to disperse the solvent. If necessary, pressurization may be performed by a roll press or the like to increase the electrode density. In this way, a sheet-like positive electrode can be produced. The sheet-like positive electrode can be cut into an appropriate size or the like according to the target battery and used for battery production. However, the method for manufacturing the positive electrode is not limited to the illustrated one, and other methods may be used.
(b)負極
負極には、金属リチウムやリチウム合金等、あるいは、リチウムイオンを吸蔵および脱離できる負極活物質に、結着剤を混合し、適当な溶剤を加えてペースト状にした負極合材を、銅等の金属箔集電体の表面に塗布し、乾燥し、必要に応じて電極密度を高めるべく圧縮して形成したものを使用する。 (B) Negative electrode A negative electrode mixture in which a negative electrode active material capable of occluding and desorbing lithium ions is mixed with a binder and an appropriate solvent is added to the negative electrode. Is applied to the surface of a metal foil current collector such as copper, dried, and compressed to increase the electrode density as necessary.
負極には、金属リチウムやリチウム合金等、あるいは、リチウムイオンを吸蔵および脱離できる負極活物質に、結着剤を混合し、適当な溶剤を加えてペースト状にした負極合材を、銅等の金属箔集電体の表面に塗布し、乾燥し、必要に応じて電極密度を高めるべく圧縮して形成したものを使用する。 (B) Negative electrode A negative electrode mixture in which a negative electrode active material capable of occluding and desorbing lithium ions is mixed with a binder and an appropriate solvent is added to the negative electrode. Is applied to the surface of a metal foil current collector such as copper, dried, and compressed to increase the electrode density as necessary.
負極活物質としては、例えば、天然黒鉛、人造黒鉛、フェノール樹脂等の有機化合物焼成体、コークス等の炭素物質の粉状体を用いることができる。この場合、負極結着剤としては、正極同様、PVDF等の含フッ素樹脂等を用いることができ、これらの活物質および結着剤を分散させる溶剤としては、N-メチル-2-ピロリドン等の有機溶剤を用いることができる。
As the negative electrode active material, for example, natural graphite, artificial graphite, a fired organic compound such as phenol resin, and a powdery carbon material such as coke can be used. In this case, a fluorine-containing resin such as PVDF can be used as the negative electrode binder, as in the case of the positive electrode, and a solvent for dispersing these active materials and the binder can be N-methyl-2-pyrrolidone or the like. Organic solvents can be used.
(c)セパレータ
正極と負極との間には、セパレータを挟み込んで配置する。セパレータは、正極と負極とを分離し、電解質を保持するものであり、ポリエチレン、ポリプロピレン等の薄い膜で、微少な孔を多数有する膜を用いることができる。 (C) Separator A separator is interposed between the positive electrode and the negative electrode. The separator separates the positive electrode and the negative electrode and retains the electrolyte, and a thin film such as polyethylene or polypropylene and a film having many minute holes can be used.
正極と負極との間には、セパレータを挟み込んで配置する。セパレータは、正極と負極とを分離し、電解質を保持するものであり、ポリエチレン、ポリプロピレン等の薄い膜で、微少な孔を多数有する膜を用いることができる。 (C) Separator A separator is interposed between the positive electrode and the negative electrode. The separator separates the positive electrode and the negative electrode and retains the electrolyte, and a thin film such as polyethylene or polypropylene and a film having many minute holes can be used.
(d)非水系電解液
非水系電解液は、支持塩としてのリチウム塩を有機溶媒に溶解したものである。
有機溶媒としては、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、トリフルオロプロピレンカーボネート等の環状カーボネート、また、ジエチルカーボネート、ジメチルカーボネート、エチルメチルカーボネート、ジプロピルカーボネート等の鎖状カーボネート、さらに、テトラヒドロフラン、2-メチルテトラヒドロフラン、ジメトキシエタン等のエーテル化合物、エチルメチルスルホン、ブタンスルトン等の硫黄化合物、リン酸トリエチル、リン酸トリオクチル等のリン化合物等から選ばれる1種を単独で、あるいは2種以上を混合して用いることができる。 (D) Non-aqueous electrolyte The non-aqueous electrolyte is obtained by dissolving a lithium salt as a supporting salt in an organic solvent.
Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate, chain carbonates such as diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, and dipropyl carbonate, tetrahydrofuran, 2- One kind selected from ether compounds such as methyltetrahydrofuran and dimethoxyethane, sulfur compounds such as ethylmethylsulfone and butanesultone, phosphorus compounds such as triethyl phosphate and trioctyl phosphate, etc. are used alone or in admixture of two or more. be able to.
非水系電解液は、支持塩としてのリチウム塩を有機溶媒に溶解したものである。
有機溶媒としては、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、トリフルオロプロピレンカーボネート等の環状カーボネート、また、ジエチルカーボネート、ジメチルカーボネート、エチルメチルカーボネート、ジプロピルカーボネート等の鎖状カーボネート、さらに、テトラヒドロフラン、2-メチルテトラヒドロフラン、ジメトキシエタン等のエーテル化合物、エチルメチルスルホン、ブタンスルトン等の硫黄化合物、リン酸トリエチル、リン酸トリオクチル等のリン化合物等から選ばれる1種を単独で、あるいは2種以上を混合して用いることができる。 (D) Non-aqueous electrolyte The non-aqueous electrolyte is obtained by dissolving a lithium salt as a supporting salt in an organic solvent.
Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate, chain carbonates such as diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, and dipropyl carbonate, tetrahydrofuran, 2- One kind selected from ether compounds such as methyltetrahydrofuran and dimethoxyethane, sulfur compounds such as ethylmethylsulfone and butanesultone, phosphorus compounds such as triethyl phosphate and trioctyl phosphate, etc. are used alone or in admixture of two or more. be able to.
支持塩としては、LiPF6、LiBF4、LiClO4、LiAsF6、LiN(CF3SO2)2等、およびそれらの複合塩を用いることができる。さらに、非水系電解液は、ラジカル捕捉剤、界面活性剤および難燃剤等を含んでいてもよい。
As the supporting salt, LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , LiN (CF 3 SO 2 ) 2 , or a composite salt thereof can be used. Furthermore, the non-aqueous electrolyte solution may contain a radical scavenger, a surfactant, a flame retardant, and the like.
(e)電池の形状、構成
以上のように説明してきた正極、負極、セパレータおよび非水系電解液で構成される本実施形態の非水系電解質二次電池の形状は、円筒型、積層型等、種々のものとすることができる。 (E) Battery shape and configuration The shape of the non-aqueous electrolyte secondary battery of the present embodiment constituted by the positive electrode, the negative electrode, the separator and the non-aqueous electrolyte described above is a cylindrical type, a laminated type, etc. It can be various.
以上のように説明してきた正極、負極、セパレータおよび非水系電解液で構成される本実施形態の非水系電解質二次電池の形状は、円筒型、積層型等、種々のものとすることができる。 (E) Battery shape and configuration The shape of the non-aqueous electrolyte secondary battery of the present embodiment constituted by the positive electrode, the negative electrode, the separator and the non-aqueous electrolyte described above is a cylindrical type, a laminated type, etc. It can be various.
いずれの形状を採る場合であっても、正極および負極を、セパレータを介して積層させて電極体とし、得られた電極体に、非水系電解液を含浸させ、正極集電体と外部に通ずる正極端子との間、および、負極集電体と外部に通ずる負極端子との間を、集電用リード等を用いて接続し、電池ケースに密閉して、非水系電解質二次電池を完成させる。
In any case, the positive electrode and the negative electrode are laminated via a separator to form an electrode body, and the obtained electrode body is impregnated with a non-aqueous electrolyte and communicated with the positive electrode current collector and the outside. The positive electrode terminal and the negative electrode current collector and the negative electrode terminal communicating with the outside are connected using a current collecting lead or the like and sealed in a battery case to complete a non-aqueous electrolyte secondary battery. .
(f)特性
本実施形態の正極活物質を用いた非水系電解質二次電池は、高容量で高出力となる。
特により好ましい形態で得られた本実施形態による正極活物質を用いた非水系電解質二次電池は、例えば、実施例に記載の2032型コイン電池の正極に用いた場合、150mAh/g以上の高い初期放電容量と低い正極抵抗が得られる。 (F) Characteristics The nonaqueous electrolyte secondary battery using the positive electrode active material of the present embodiment has a high capacity and a high output.
In particular, the non-aqueous electrolyte secondary battery using the positive electrode active material according to the present embodiment obtained in a more preferable form has a high value of 150 mAh / g or more when used for the positive electrode of the 2032 type coin battery described in the examples. An initial discharge capacity and a low positive electrode resistance are obtained.
本実施形態の正極活物質を用いた非水系電解質二次電池は、高容量で高出力となる。
特により好ましい形態で得られた本実施形態による正極活物質を用いた非水系電解質二次電池は、例えば、実施例に記載の2032型コイン電池の正極に用いた場合、150mAh/g以上の高い初期放電容量と低い正極抵抗が得られる。 (F) Characteristics The nonaqueous electrolyte secondary battery using the positive electrode active material of the present embodiment has a high capacity and a high output.
In particular, the non-aqueous electrolyte secondary battery using the positive electrode active material according to the present embodiment obtained in a more preferable form has a high value of 150 mAh / g or more when used for the positive electrode of the 2032 type coin battery described in the examples. An initial discharge capacity and a low positive electrode resistance are obtained.
なお、本実施形態における正極抵抗の測定方法を例示すれば、次のようになる。電気化学的評価手法として一般的な交流インピーダンス法にて電池反応の周波数依存性について測定を行うと、溶液抵抗、負極抵抗と負極容量、および正極抵抗と正極容量に基づくナイキスト線図が図2のように得られる。
In addition, it will be as follows if the measuring method of the positive electrode resistance in this embodiment is illustrated. When the frequency dependence of the battery reaction is measured by a general AC impedance method as an electrochemical evaluation method, the Nyquist diagram based on the solution resistance, the negative electrode resistance and the negative electrode capacity, and the positive electrode resistance and the positive electrode capacity is shown in FIG. Is obtained as follows.
電極における電池反応は、電荷移動に伴う抵抗成分と電気二重層による容量成分とからなり、これらを電気回路で表すと抵抗と容量の並列回路となり、電池全体としては溶液抵抗と負極、正極の並列回路を直列に接続した等価回路で表される。この等価回路を用いて測定したナイキスト線図に対してフィッティング計算を行い、各抵抗成分、容量成分を見積もることができる。正極抵抗は、得られるナイキスト線図の低周波数側の半円の直径と等しい。
The battery reaction at the electrode consists of a resistance component accompanying the charge transfer and a capacity component due to the electric double layer. When these are expressed as an electric circuit, it becomes a parallel circuit of resistance and capacity. It is represented by an equivalent circuit in which circuits are connected in series. Fitting calculation is performed on the Nyquist diagram measured using this equivalent circuit, and each resistance component and capacitance component can be estimated. The positive electrode resistance is equal to the diameter of the semicircle on the low frequency side of the obtained Nyquist diagram.
以上のことから、作製される正極について、交流インピーダンス測定を行い、得られたナイキスト線図に対し等価回路でフィッティング計算することで、正極抵抗を見積もることができる。
From the above, the positive electrode resistance can be estimated by performing AC impedance measurement on the manufactured positive electrode and performing fitting calculation with the equivalent circuit on the obtained Nyquist diagram.
以下、本発明の実施例を用いて具体的に説明するが、本発明は、これらの実施例によって何ら限定されるものではない。本実施例により得られた正極活物質およびこの正極活物質を用いた正極合材ペースト、非水系電解質二次電池について、その性能(ペーストの安定性、初期放電容量、正極抵抗、内部抵抗、放電容量維持率)を下記の方法で評価した。
Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. About the positive electrode active material obtained in this example, the positive electrode mixture paste using this positive electrode active material, and the non-aqueous electrolyte secondary battery, the performance (stability of paste, initial discharge capacity, positive electrode resistance, internal resistance, discharge) The capacity retention ratio was evaluated by the following method.
(コイン型電池の製造および電池特性の評価)
非水系電解質二次電池用正極活物質52.5mg、アセチレンブラック15mg、およびポリテトラフッ化エチレン樹脂(PTFE)7.5mgを混合し、100MPaの圧力で直径11mm、厚さ100μmにプレス成形して図3に示す正極1(評価用電極)を作製した。その作製した正極1を真空乾燥機中120℃で12時間乾燥した。そして、この正極1を用いて2032型のコイン型電池Bを、露点が-80℃に管理されたAr雰囲気のグローブボックス内で作製した。
負極2には、直径14mmの円盤状に打ち抜かれた平均粒径20μm程度の黒鉛粉末とポリフッ化ビニリデンが銅箔に塗布された負極シートを用い、電解液には、1MのLiPF6を支持電解質とするエチレンカーボネート(EC)とジエチルカーボネート(DEC)の等量混合液(富山薬品工業株式会社製)を用いた。セパレータ3には膜厚25μmのポリエチレン多孔膜を用いた。また、コイン型電池Bは、ガスケット4とウェーブワッシャー5を有し、正極缶6と負極缶7とでコイン状の電池に組み立てられた。製造したコイン型電池Bの性能を示す初期放電容量、正極抵抗、サイクル特性は、以下のように評価した。 (Manufacture of coin-type battery and evaluation of battery characteristics)
32.5 mg of a positive electrode active material for a non-aqueous electrolyte secondary battery, 15 mg of acetylene black, and 7.5 mg of polytetrafluoroethylene resin (PTFE) were mixed and press-molded to a diameter of 11 mm and a thickness of 100 μm at a pressure of 100 MPa. The positive electrode 1 (electrode for evaluation) shown in FIG. The producedpositive electrode 1 was dried at 120 ° C. for 12 hours in a vacuum dryer. Using this positive electrode 1, a 2032 type coin-type battery B was produced in a glove box in an Ar atmosphere in which the dew point was controlled at −80 ° C.
For thenegative electrode 2, a negative electrode sheet in which a graphite powder punched into a disk shape with a diameter of 14 mm and an average particle diameter of about 20 μm and polyvinylidene fluoride are applied to a copper foil is used, and 1 M LiPF 6 is used as the electrolyte for the electrolyte. An equivalent mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (manufactured by Toyama Pharmaceutical Co., Ltd.) was used. As the separator 3, a polyethylene porous film having a film thickness of 25 μm was used. The coin-type battery B has a gasket 4 and a wave washer 5, and the positive electrode can 6 and the negative electrode can 7 are assembled into a coin-shaped battery. The initial discharge capacity, the positive electrode resistance, and the cycle characteristics showing the performance of the manufactured coin battery B were evaluated as follows.
非水系電解質二次電池用正極活物質52.5mg、アセチレンブラック15mg、およびポリテトラフッ化エチレン樹脂(PTFE)7.5mgを混合し、100MPaの圧力で直径11mm、厚さ100μmにプレス成形して図3に示す正極1(評価用電極)を作製した。その作製した正極1を真空乾燥機中120℃で12時間乾燥した。そして、この正極1を用いて2032型のコイン型電池Bを、露点が-80℃に管理されたAr雰囲気のグローブボックス内で作製した。
負極2には、直径14mmの円盤状に打ち抜かれた平均粒径20μm程度の黒鉛粉末とポリフッ化ビニリデンが銅箔に塗布された負極シートを用い、電解液には、1MのLiPF6を支持電解質とするエチレンカーボネート(EC)とジエチルカーボネート(DEC)の等量混合液(富山薬品工業株式会社製)を用いた。セパレータ3には膜厚25μmのポリエチレン多孔膜を用いた。また、コイン型電池Bは、ガスケット4とウェーブワッシャー5を有し、正極缶6と負極缶7とでコイン状の電池に組み立てられた。製造したコイン型電池Bの性能を示す初期放電容量、正極抵抗、サイクル特性は、以下のように評価した。 (Manufacture of coin-type battery and evaluation of battery characteristics)
32.5 mg of a positive electrode active material for a non-aqueous electrolyte secondary battery, 15 mg of acetylene black, and 7.5 mg of polytetrafluoroethylene resin (PTFE) were mixed and press-molded to a diameter of 11 mm and a thickness of 100 μm at a pressure of 100 MPa. The positive electrode 1 (electrode for evaluation) shown in FIG. The produced
For the
(初期放電容量)
初期放電容量は、コイン型電池Bを製作してから24時間程度放置し、開回路電圧OCV(Open Circuit Voltage)が安定した後、正極に対する電流密度を0.1mA/cm2としてカットオフ電圧4.3Vまで充電し、1時間の休止後、カットオフ電圧3.0Vまで放電したときの容量を初期放電容量とした。 (Initial discharge capacity)
The initial discharge capacity is left for about 24 hours after the coin-type battery B is manufactured, and after the open circuit voltage OCV (Open Circuit Voltage) is stabilized, the current density with respect to the positive electrode is set to 0.1 mA / cm 2 and the cut-offvoltage 4 The capacity when the battery was charged to 3 V, discharged after a pause of 1 hour to a cutoff voltage of 3.0 V was defined as the initial discharge capacity.
初期放電容量は、コイン型電池Bを製作してから24時間程度放置し、開回路電圧OCV(Open Circuit Voltage)が安定した後、正極に対する電流密度を0.1mA/cm2としてカットオフ電圧4.3Vまで充電し、1時間の休止後、カットオフ電圧3.0Vまで放電したときの容量を初期放電容量とした。 (Initial discharge capacity)
The initial discharge capacity is left for about 24 hours after the coin-type battery B is manufactured, and after the open circuit voltage OCV (Open Circuit Voltage) is stabilized, the current density with respect to the positive electrode is set to 0.1 mA / cm 2 and the cut-off
(正極抵抗)
また、正極抵抗は、コイン型電池Bを25℃で充電電位4.1Vで充電して、周波数応答アナライザおよびポテンショガルバノスタット(ソーラトロン製、1255B)を使用して交流インピーダンス法により測定すると、図2に示すナイキストプロットが得られる。このナイキストプロットは、溶液抵抗、負極抵抗とその容量、および、正極抵抗とその容量を示す特性曲線の和として表しているため、このナイキストプロットに基づき等価回路を用いてフィッティング計算を行い、正極抵抗の値を算出した。
(サイクル特性)
サイクル特性(放電容量維持率)の評価は、サイクル試験後の容量維持率により行った。サイクル試験は、60℃に保持して初期放電容量測定後、10分間休止し、初期放電容量測定と同様に充放電サイクルを、初期放電容量測定も含めて500サイクル(充放電)繰り返した。500サイクル目の放電容量を測定して、1サイクル目の放電容量(初期放電容量)に対する500サイクル目の放電容量の百分率を容量維持率(%)として求めた。 (Positive electrode resistance)
Further, the positive electrode resistance is obtained by charging the coin-type battery B at 25 ° C. with a charging potential of 4.1 V and measuring the positive electrode resistance by the AC impedance method using a frequency response analyzer and a potentiogalvanostat (manufactured by Solartron, 1255B). The Nyquist plot shown in FIG. Since this Nyquist plot is represented as the sum of the solution resistance, the negative electrode resistance and its capacity, and the characteristic curve indicating the positive electrode resistance and its capacity, the fitting calculation was performed using an equivalent circuit based on this Nyquist plot, and the positive resistance The value of was calculated.
(Cycle characteristics)
The evaluation of the cycle characteristics (discharge capacity maintenance rate) was performed based on the capacity maintenance rate after the cycle test. The cycle test was held at 60 ° C. and paused for 10 minutes after the initial discharge capacity measurement, and the charge / discharge cycle was repeated 500 cycles (charge / discharge) including the initial discharge capacity measurement in the same manner as the initial discharge capacity measurement. The discharge capacity at the 500th cycle was measured, and the percentage of the discharge capacity at the 500th cycle with respect to the discharge capacity at the first cycle (initial discharge capacity) was determined as the capacity retention rate (%).
また、正極抵抗は、コイン型電池Bを25℃で充電電位4.1Vで充電して、周波数応答アナライザおよびポテンショガルバノスタット(ソーラトロン製、1255B)を使用して交流インピーダンス法により測定すると、図2に示すナイキストプロットが得られる。このナイキストプロットは、溶液抵抗、負極抵抗とその容量、および、正極抵抗とその容量を示す特性曲線の和として表しているため、このナイキストプロットに基づき等価回路を用いてフィッティング計算を行い、正極抵抗の値を算出した。
(サイクル特性)
サイクル特性(放電容量維持率)の評価は、サイクル試験後の容量維持率により行った。サイクル試験は、60℃に保持して初期放電容量測定後、10分間休止し、初期放電容量測定と同様に充放電サイクルを、初期放電容量測定も含めて500サイクル(充放電)繰り返した。500サイクル目の放電容量を測定して、1サイクル目の放電容量(初期放電容量)に対する500サイクル目の放電容量の百分率を容量維持率(%)として求めた。 (Positive electrode resistance)
Further, the positive electrode resistance is obtained by charging the coin-type battery B at 25 ° C. with a charging potential of 4.1 V and measuring the positive electrode resistance by the AC impedance method using a frequency response analyzer and a potentiogalvanostat (manufactured by Solartron, 1255B). The Nyquist plot shown in FIG. Since this Nyquist plot is represented as the sum of the solution resistance, the negative electrode resistance and its capacity, and the characteristic curve indicating the positive electrode resistance and its capacity, the fitting calculation was performed using an equivalent circuit based on this Nyquist plot, and the positive resistance The value of was calculated.
(Cycle characteristics)
The evaluation of the cycle characteristics (discharge capacity maintenance rate) was performed based on the capacity maintenance rate after the cycle test. The cycle test was held at 60 ° C. and paused for 10 minutes after the initial discharge capacity measurement, and the charge / discharge cycle was repeated 500 cycles (charge / discharge) including the initial discharge capacity measurement in the same manner as the initial discharge capacity measurement. The discharge capacity at the 500th cycle was measured, and the percentage of the discharge capacity at the 500th cycle with respect to the discharge capacity at the first cycle (initial discharge capacity) was determined as the capacity retention rate (%).
(低温出力特性の評価)
ラミネートセルCを用いて、低温時の電池内部抵抗ΔVを電流休止法によって測定することにより、低温出力特性を評価した。評価方法は次のようになる。
評価に用いたラミネートセルCを以下のように作製した。アルミニウム製集電箔(厚さ0.02mm)に、正極活物質と導電材(アセチレンブラック)と結着剤(PVDF)を85:10:5の質量比で混合した後、溶剤(NMP)を加え正極活物質をペースト化し、外部と接続する導電部を残して塗布し、乾燥させ、正極活物質の目付が7mg/cm2の正極活物質層が形成された正極シート8を作製した。
また、銅製集電箔(厚さ0.02mm)に負極活物質としてカーボン粉(アセチレンブラック)をペースト化し、同様にして負極活物質の目付が5mg/cm2の負極活物質層が形成された負極シート9を作製した。
作製された正極シート8および負極シート9の間に、ポリプロピレン製微多孔膜(厚さ20.7μm、空孔率密度43.9%)からなるセパレータ10を介挿して積層シートを形成した。そして、この積層シートを2枚のアルミラミネートシート11(厚さ0.55mm)によって挟み、アルミラミネートシート11の3辺を熱融着して熱融着部HSを形成することにより密封し、図4に示すような構成のラミネートセルを組み立てた。
その後、エチレンカーボネートとエチルメチルカーボネートとジメチルカーボネートとの混合溶媒(容量比3:3:4)にLiPF6(1mol/L)を溶解した宇部興産株式会社製の電解液を260μl注入し、残りの一辺を熱融着して、図4に示すラミネートセルCを作製した。
作製したラミネートセルCを-20℃の温度下で4.2Vまで充電後、0.2Cで2.5Vまで放電させ、開回路にして、600秒間電圧緩和させた前後の電圧変化(ΔV)を算出した。放電時の電流が同じ場合、ΔVの差はそのまま抵抗の差と解釈でき、すなわちΔVが小さいほど抵抗が低いと解釈できるため、ΔVの値を低温条件での直流抵抗として評価した。電流休止法測定結果の例を図5に示す。 (Evaluation of low temperature output characteristics)
Using the laminate cell C, the low-temperature output characteristics were evaluated by measuring the battery internal resistance ΔV at low temperatures by the current pause method. The evaluation method is as follows.
A laminate cell C used for evaluation was produced as follows. After mixing a positive electrode active material, a conductive material (acetylene black), and a binder (PVDF) at a mass ratio of 85: 10: 5 to an aluminum current collector foil (thickness 0.02 mm), a solvent (NMP) was added. In addition, the positive electrode active material was made into a paste, applied while leaving a conductive part connected to the outside, and dried to prepare apositive electrode sheet 8 on which a positive electrode active material layer having a basis weight of 7 mg / cm 2 was formed.
Also, carbon powder (acetylene black) was pasted as a negative electrode active material on a copper current collector foil (thickness 0.02 mm), and a negative electrode active material layer having a negative electrode active material weight of 5 mg / cm 2 was formed in the same manner. Anegative electrode sheet 9 was produced.
A laminated sheet was formed between the producedpositive electrode sheet 8 and negative electrode sheet 9 with a separator 10 made of a polypropylene microporous film (thickness 20.7 μm, porosity density 43.9%) interposed therebetween. Then, the laminated sheet is sandwiched between two aluminum laminate sheets 11 (thickness 0.55 mm), and the three sides of the aluminum laminate sheet 11 are heat-sealed to form a heat-sealed portion HS, which is sealed. 4 was assembled.
Thereafter, 260 μl of an electrolyte made by Ube Industries, Ltd. in which LiPF 6 (1 mol / L) was dissolved in a mixed solvent of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate (volume ratio 3: 3: 4) was injected, and the rest One side was heat-sealed to produce a laminate cell C shown in FIG.
The manufactured laminate cell C was charged to 4.2 V at a temperature of −20 ° C., then discharged to 0.2 V at 0.2 C, and the voltage change (ΔV) before and after the voltage was relaxed for 600 seconds was made open circuit. Calculated. When the current during discharge is the same, the difference in ΔV can be interpreted as a resistance difference as it is, that is, the smaller the ΔV, the lower the resistance, so the value of ΔV was evaluated as a direct current resistance under low temperature conditions. An example of the measurement result of the current pause method is shown in FIG.
ラミネートセルCを用いて、低温時の電池内部抵抗ΔVを電流休止法によって測定することにより、低温出力特性を評価した。評価方法は次のようになる。
評価に用いたラミネートセルCを以下のように作製した。アルミニウム製集電箔(厚さ0.02mm)に、正極活物質と導電材(アセチレンブラック)と結着剤(PVDF)を85:10:5の質量比で混合した後、溶剤(NMP)を加え正極活物質をペースト化し、外部と接続する導電部を残して塗布し、乾燥させ、正極活物質の目付が7mg/cm2の正極活物質層が形成された正極シート8を作製した。
また、銅製集電箔(厚さ0.02mm)に負極活物質としてカーボン粉(アセチレンブラック)をペースト化し、同様にして負極活物質の目付が5mg/cm2の負極活物質層が形成された負極シート9を作製した。
作製された正極シート8および負極シート9の間に、ポリプロピレン製微多孔膜(厚さ20.7μm、空孔率密度43.9%)からなるセパレータ10を介挿して積層シートを形成した。そして、この積層シートを2枚のアルミラミネートシート11(厚さ0.55mm)によって挟み、アルミラミネートシート11の3辺を熱融着して熱融着部HSを形成することにより密封し、図4に示すような構成のラミネートセルを組み立てた。
その後、エチレンカーボネートとエチルメチルカーボネートとジメチルカーボネートとの混合溶媒(容量比3:3:4)にLiPF6(1mol/L)を溶解した宇部興産株式会社製の電解液を260μl注入し、残りの一辺を熱融着して、図4に示すラミネートセルCを作製した。
作製したラミネートセルCを-20℃の温度下で4.2Vまで充電後、0.2Cで2.5Vまで放電させ、開回路にして、600秒間電圧緩和させた前後の電圧変化(ΔV)を算出した。放電時の電流が同じ場合、ΔVの差はそのまま抵抗の差と解釈でき、すなわちΔVが小さいほど抵抗が低いと解釈できるため、ΔVの値を低温条件での直流抵抗として評価した。電流休止法測定結果の例を図5に示す。 (Evaluation of low temperature output characteristics)
Using the laminate cell C, the low-temperature output characteristics were evaluated by measuring the battery internal resistance ΔV at low temperatures by the current pause method. The evaluation method is as follows.
A laminate cell C used for evaluation was produced as follows. After mixing a positive electrode active material, a conductive material (acetylene black), and a binder (PVDF) at a mass ratio of 85: 10: 5 to an aluminum current collector foil (thickness 0.02 mm), a solvent (NMP) was added. In addition, the positive electrode active material was made into a paste, applied while leaving a conductive part connected to the outside, and dried to prepare a
Also, carbon powder (acetylene black) was pasted as a negative electrode active material on a copper current collector foil (thickness 0.02 mm), and a negative electrode active material layer having a negative electrode active material weight of 5 mg / cm 2 was formed in the same manner. A
A laminated sheet was formed between the produced
Thereafter, 260 μl of an electrolyte made by Ube Industries, Ltd. in which LiPF 6 (1 mol / L) was dissolved in a mixed solvent of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate (volume ratio 3: 3: 4) was injected, and the rest One side was heat-sealed to produce a laminate cell C shown in FIG.
The manufactured laminate cell C was charged to 4.2 V at a temperature of −20 ° C., then discharged to 0.2 V at 0.2 C, and the voltage change (ΔV) before and after the voltage was relaxed for 600 seconds was made open circuit. Calculated. When the current during discharge is the same, the difference in ΔV can be interpreted as a resistance difference as it is, that is, the smaller the ΔV, the lower the resistance, so the value of ΔV was evaluated as a direct current resistance under low temperature conditions. An example of the measurement result of the current pause method is shown in FIG.
(正極合材ペーストの粘度安定性)
正極活物質25.0gと、導電材のカーボン粉1.5gと、ポリフッ化ビニリデン(PVDF)2.9gと、N-メチル-2ピロリドン(NMP)とを遊星運動混練機により混合し正極合材ペーストを得た。N-メチル-2ピロリドン(NMP)は、JIS Z 8803:2011に規定される振動粘度計による粘度測定方法により、粘度が1.5~2.5Pa・sとなるように添加量を調整した。得られたペーストを76時間保管して、保管前後の粘度比(76時間保管後のペースト粘度/作製直後のペースト粘度)を評価した。粘度は、振動式粘度計(セコニック社製VM10A)にて測定した。 (Viscosity stability of positive electrode mixture paste)
Positive electrode active material 25.0 g, carbon powder 1.5 g of conductive material, 2.9 g of polyvinylidene fluoride (PVDF), and N-methyl-2-pyrrolidone (NMP) were mixed by a planetary motion kneader. A paste was obtained. The amount of N-methyl-2pyrrolidone (NMP) added was adjusted so that the viscosity would be 1.5 to 2.5 Pa · s by a viscosity measurement method using a vibration viscometer specified in JIS Z 8803: 2011. The obtained paste was stored for 76 hours, and the viscosity ratio before and after storage (paste viscosity after storage for 76 hours / paste viscosity immediately after preparation) was evaluated. The viscosity was measured with a vibration viscometer (VM10A manufactured by Seconic).
正極活物質25.0gと、導電材のカーボン粉1.5gと、ポリフッ化ビニリデン(PVDF)2.9gと、N-メチル-2ピロリドン(NMP)とを遊星運動混練機により混合し正極合材ペーストを得た。N-メチル-2ピロリドン(NMP)は、JIS Z 8803:2011に規定される振動粘度計による粘度測定方法により、粘度が1.5~2.5Pa・sとなるように添加量を調整した。得られたペーストを76時間保管して、保管前後の粘度比(76時間保管後のペースト粘度/作製直後のペースト粘度)を評価した。粘度は、振動式粘度計(セコニック社製VM10A)にて測定した。 (Viscosity stability of positive electrode mixture paste)
Positive electrode active material 25.0 g, carbon powder 1.5 g of conductive material, 2.9 g of polyvinylidene fluoride (PVDF), and N-methyl-2-pyrrolidone (NMP) were mixed by a planetary motion kneader. A paste was obtained. The amount of N-methyl-2pyrrolidone (NMP) added was adjusted so that the viscosity would be 1.5 to 2.5 Pa · s by a viscosity measurement method using a vibration viscometer specified in JIS Z 8803: 2011. The obtained paste was stored for 76 hours, and the viscosity ratio before and after storage (paste viscosity after storage for 76 hours / paste viscosity immediately after preparation) was evaluated. The viscosity was measured with a vibration viscometer (VM10A manufactured by Seconic).
(水分率)
気化温度300℃の条件においてカールフィッシャー水分計で測定した。 (Moisture percentage)
The measurement was performed with a Karl Fischer moisture meter under the condition of a vaporization temperature of 300 ° C.
気化温度300℃の条件においてカールフィッシャー水分計で測定した。 (Moisture percentage)
The measurement was performed with a Karl Fischer moisture meter under the condition of a vaporization temperature of 300 ° C.
(余剰LiOH量及び余剰Li2CO3量の測定)
余剰リチウム量は、正極活物質から溶出してくるLiを滴定することにより評価した。得られた正極活物質1gに純水10mlを加えて1分間攪拌後、ろ過したろ液のpHを測定しながら1mol/リットルの塩酸を加えていくことにより出現する中和点から溶出するリチウムの化合物状態を分析して余剰リチウム量を評価した。ここで、高アルカリ側からの1段目の中和点(ショルダー)がLiOH量を示し、2段目の中和点がLi2CO3量を示す。 (Measurement of surplus LiOH amount and surplus Li 2 CO 3 amount)
The excess lithium amount was evaluated by titrating Li eluted from the positive electrode active material. After adding 10 ml of pure water to 1 g of the obtained positive electrode active material and stirring for 1 minute, the lithium elution from the neutralization point appearing by adding 1 mol / liter hydrochloric acid while measuring the pH of the filtered filtrate was performed. The compound state was analyzed to evaluate the excess lithium amount. Here, the first neutralization point (shoulder) from the high alkali side indicates the LiOH amount, and the second neutralization point indicates the Li 2 CO 3 amount.
余剰リチウム量は、正極活物質から溶出してくるLiを滴定することにより評価した。得られた正極活物質1gに純水10mlを加えて1分間攪拌後、ろ過したろ液のpHを測定しながら1mol/リットルの塩酸を加えていくことにより出現する中和点から溶出するリチウムの化合物状態を分析して余剰リチウム量を評価した。ここで、高アルカリ側からの1段目の中和点(ショルダー)がLiOH量を示し、2段目の中和点がLi2CO3量を示す。 (Measurement of surplus LiOH amount and surplus Li 2 CO 3 amount)
The excess lithium amount was evaluated by titrating Li eluted from the positive electrode active material. After adding 10 ml of pure water to 1 g of the obtained positive electrode active material and stirring for 1 minute, the lithium elution from the neutralization point appearing by adding 1 mol / liter hydrochloric acid while measuring the pH of the filtered filtrate was performed. The compound state was analyzed to evaluate the excess lithium amount. Here, the first neutralization point (shoulder) from the high alkali side indicates the LiOH amount, and the second neutralization point indicates the Li 2 CO 3 amount.
(実施例1)
Niを主成分とする酸化物粉末と水酸化リチウムを混合して焼成する公知技術で得られたLi1.20Ni0.35Co0.35Mn0.30O2で表されるリチウム金属複合酸化物の焼成粉末(平均粒径:5.07μm、〔(d90-d10)/平均粒径〕:0.42、空隙率:14.2%:比表面積2.50g/m2)を母材とした。母材とする焼成粉末に水を、焼成粉末に対して1.5質量%添加してさらに混合した。その後、大気雰囲気中において150℃で12時間乾燥することによって正極活物質を得た。正極活物質の製造条件及び下記測定・評価結果を表1及び表2に示す。なお、正極活物質の比表面積は、窒素ガス吸着によるBET法で求めた。
[pH測定]
得られた正極活物質5gを100mlの純水に分散させた後、10分間静置し、上澄み液の25℃におけるpHを測定した。
[正極合材ペースト]
得られた正極活物質を使用して上記方法で作製された正極合材ペーストの粘度を測定した。
[電池評価]
得られた正極活物質を使用して上記方法で作製された正極を有するコイン型電池BおよびラミネートセルCの電池特性を評価した。 Example 1
Lithium metal composite represented by Li 1.20 Ni 0.35 Co 0.35 Mn 0.30 O 2 obtained by a known technique of mixing and baking oxide powder containing Ni as a main component and lithium hydroxide Baked oxide powder (average particle size: 5.07 μm, [(d90-d10) / average particle size]: 0.42, porosity: 14.2%: specific surface area 2.50 g / m 2 ) It was. Water was added to the calcined powder used as a base material in an amount of 1.5% by mass with respect to the calcined powder, and further mixed. Then, the positive electrode active material was obtained by drying at 150 degreeC for 12 hours in an atmospheric condition. The production conditions of the positive electrode active material and the following measurement / evaluation results are shown in Tables 1 and 2. The specific surface area of the positive electrode active material was determined by a BET method using nitrogen gas adsorption.
[PH measurement]
5 g of the obtained positive electrode active material was dispersed in 100 ml of pure water, allowed to stand for 10 minutes, and the pH of the supernatant liquid at 25 ° C. was measured.
[Positive electrode paste]
Using the obtained positive electrode active material, the viscosity of the positive electrode mixture paste produced by the above method was measured.
[Battery evaluation]
Using the obtained positive electrode active material, the battery characteristics of the coin-type battery B and the laminate cell C having the positive electrode prepared by the above method were evaluated.
Niを主成分とする酸化物粉末と水酸化リチウムを混合して焼成する公知技術で得られたLi1.20Ni0.35Co0.35Mn0.30O2で表されるリチウム金属複合酸化物の焼成粉末(平均粒径:5.07μm、〔(d90-d10)/平均粒径〕:0.42、空隙率:14.2%:比表面積2.50g/m2)を母材とした。母材とする焼成粉末に水を、焼成粉末に対して1.5質量%添加してさらに混合した。その後、大気雰囲気中において150℃で12時間乾燥することによって正極活物質を得た。正極活物質の製造条件及び下記測定・評価結果を表1及び表2に示す。なお、正極活物質の比表面積は、窒素ガス吸着によるBET法で求めた。
[pH測定]
得られた正極活物質5gを100mlの純水に分散させた後、10分間静置し、上澄み液の25℃におけるpHを測定した。
[正極合材ペースト]
得られた正極活物質を使用して上記方法で作製された正極合材ペーストの粘度を測定した。
[電池評価]
得られた正極活物質を使用して上記方法で作製された正極を有するコイン型電池BおよびラミネートセルCの電池特性を評価した。 Example 1
Lithium metal composite represented by Li 1.20 Ni 0.35 Co 0.35 Mn 0.30 O 2 obtained by a known technique of mixing and baking oxide powder containing Ni as a main component and lithium hydroxide Baked oxide powder (average particle size: 5.07 μm, [(d90-d10) / average particle size]: 0.42, porosity: 14.2%: specific surface area 2.50 g / m 2 ) It was. Water was added to the calcined powder used as a base material in an amount of 1.5% by mass with respect to the calcined powder, and further mixed. Then, the positive electrode active material was obtained by drying at 150 degreeC for 12 hours in an atmospheric condition. The production conditions of the positive electrode active material and the following measurement / evaluation results are shown in Tables 1 and 2. The specific surface area of the positive electrode active material was determined by a BET method using nitrogen gas adsorption.
[PH measurement]
5 g of the obtained positive electrode active material was dispersed in 100 ml of pure water, allowed to stand for 10 minutes, and the pH of the supernatant liquid at 25 ° C. was measured.
[Positive electrode paste]
Using the obtained positive electrode active material, the viscosity of the positive electrode mixture paste produced by the above method was measured.
[Battery evaluation]
Using the obtained positive electrode active material, the battery characteristics of the coin-type battery B and the laminate cell C having the positive electrode prepared by the above method were evaluated.
(実施例2)
水の添加量を3質量%とした以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例3)
水の添加量を5質量%とした以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例4)
水の添加量を7質量%とした以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例5)
水の添加量を14質量%とした以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例6)
水の添加量を30質量%とした以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例7)
母材とする焼成粉末をバットに入れ、スプレーボトルを用いて、平均の液滴径が約300μmになるような条件で、リチウム金属複合酸化物粉末に対して3質量%の水を噴霧して添加しながら混合した以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例8)
母材とする焼成粉末をヘンシェルミキサー(日本コークス(株)製FM20C/I)に入れ、タンク内で撹拌羽を用いて焼成粉末を撹拌混合しながら、平均の液滴径が約300μmになるような条件で、スプレーを用いてリチウム金属複合酸化物粉末に対して3質量%の水を噴霧して添加しながら混合し、その後、約-90kPaの減圧雰囲気中において130℃で2時間乾燥する以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。 (Example 2)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 3% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 3)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 5% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 4)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 7% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 5)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 14% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 6)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 30% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 7)
The fired powder used as a base material is put in a vat, and 3% by mass of water is sprayed on the lithium metal composite oxide powder under the condition that the average droplet diameter is about 300 μm using a spray bottle. A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that mixing was performed while adding. The evaluation results are shown in Tables 1 and 2.
(Example 8)
Put the calcined powder as the base material into a Henschel mixer (FM20C / I manufactured by Nippon Coke Co., Ltd.) and stir and mix the calcined powder with stirring blades in the tank so that the average droplet diameter is about 300 μm. Under the conditions, 3 mass% water is sprayed and added to the lithium metal composite oxide powder using a spray, and then mixed, and then dried at 130 ° C. for 2 hours in a reduced pressure atmosphere of about −90 kPa. In the same manner as in Example 1, a positive electrode active material was obtained and evaluated. The evaluation results are shown in Tables 1 and 2.
水の添加量を3質量%とした以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例3)
水の添加量を5質量%とした以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例4)
水の添加量を7質量%とした以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例5)
水の添加量を14質量%とした以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例6)
水の添加量を30質量%とした以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例7)
母材とする焼成粉末をバットに入れ、スプレーボトルを用いて、平均の液滴径が約300μmになるような条件で、リチウム金属複合酸化物粉末に対して3質量%の水を噴霧して添加しながら混合した以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例8)
母材とする焼成粉末をヘンシェルミキサー(日本コークス(株)製FM20C/I)に入れ、タンク内で撹拌羽を用いて焼成粉末を撹拌混合しながら、平均の液滴径が約300μmになるような条件で、スプレーを用いてリチウム金属複合酸化物粉末に対して3質量%の水を噴霧して添加しながら混合し、その後、約-90kPaの減圧雰囲気中において130℃で2時間乾燥する以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。 (Example 2)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 3% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 3)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 5% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 4)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 7% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 5)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 14% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 6)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the amount of water added was 30% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 7)
The fired powder used as a base material is put in a vat, and 3% by mass of water is sprayed on the lithium metal composite oxide powder under the condition that the average droplet diameter is about 300 μm using a spray bottle. A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that mixing was performed while adding. The evaluation results are shown in Tables 1 and 2.
(Example 8)
Put the calcined powder as the base material into a Henschel mixer (FM20C / I manufactured by Nippon Coke Co., Ltd.) and stir and mix the calcined powder with stirring blades in the tank so that the average droplet diameter is about 300 μm. Under the conditions, 3 mass% water is sprayed and added to the lithium metal composite oxide powder using a spray, and then mixed, and then dried at 130 ° C. for 2 hours in a reduced pressure atmosphere of about −90 kPa. In the same manner as in Example 1, a positive electrode active material was obtained and evaluated. The evaluation results are shown in Tables 1 and 2.
(実施例9)
母材を組成がLi1.20(Ni0.35Co0.35Mn0.30)0.995W0.005O2で表されるリチウム金属複合酸化物の焼成粉末(平均粒径:4.97μm、〔(d90-d10)/平均粒径〕0.41、空隙率:15.6%)とした以外は実施例1と同様にして、正極活物質を得るとともに評した。評価結果を表1及び表2に示す。なお、母材の上記組成は、NiとCoとMnとのモル比(Ni:Co:Mn)が0.35:0.35:0.30であり、Ni、Co及びMnの合計とWとのモル比(Ni+Co+Mn:W)が0.995:0.005であり、かつ、LiとMe(Ni、Co、Mn及びWの合計)とのモル比(Li:Me)が1.20:1であることを示す。
(実施例10)
水の添加量を3質量%とした以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例11)
水の添加量を5質量%とした以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例12)
水の添加量を7質量%とした以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例13)
水の添加量を14質量%とした以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例14)
水の添加量を30質量%とした以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例15)
母材とする焼成粉末をバットに入れ、スプレーボトルを用いて、平均の液滴径が約300μmになるような条件で、リチウム金属複合酸化物粉末に対して3質量%の水を噴霧して添加しながら混合した以外は実施例9と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例16)
母材とする焼成粉末をヘンシェルミキサー(日本コークス(株)製FM20C/I)に入れ、タンク内で撹拌羽を用いて焼成粉末を撹拌混合しながら、平均の液滴径が約300μmになるような条件で、スプレーを用いてリチウム金属複合酸化物粉末に対して3質量%の水を噴霧して添加しながら混合し、その後、約-90kPaの減圧雰囲気中において130℃で2時間乾燥する以外は実施例9と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。 Example 9
A calcined powder of a lithium metal composite oxide having a composition of Li 1.20 (Ni 0.35 Co 0.35 Mn 0.30 ) 0.995 W 0.005 O 2 (average particle size: 4) A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that it was set to .97 μm, [(d90-d10) / average particle diameter] 0.41, and porosity: 15.6%). The evaluation results are shown in Tables 1 and 2. The above composition of the base material is such that the molar ratio of Ni, Co, and Mn (Ni: Co: Mn) is 0.35: 0.35: 0.30, and the sum of Ni, Co, and Mn, and W The molar ratio (Ni + Co + Mn: W) is 0.995: 0.005, and the molar ratio (Li: Me) of Li to Me (total of Ni, Co, Mn and W) is 1.20: 1. Indicates that
(Example 10)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 3% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 11)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 5% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 12)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 7% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 13)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 14% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 14)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 30% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 15)
The fired powder used as a base material is put in a vat, and 3% by mass of water is sprayed on the lithium metal composite oxide powder under the condition that the average droplet diameter is about 300 μm using a spray bottle. A positive electrode active material was obtained and evaluated in the same manner as in Example 9 except that mixing was performed while adding. The evaluation results are shown in Tables 1 and 2.
(Example 16)
Put the calcined powder as the base material into a Henschel mixer (FM20C / I manufactured by Nippon Coke Co., Ltd.) and stir and mix the calcined powder with stirring blades in the tank so that the average droplet diameter is about 300 μm. Under the conditions, 3 mass% water is sprayed and added to the lithium metal composite oxide powder using a spray, and then mixed, and then dried at 130 ° C. for 2 hours in a reduced pressure atmosphere of about −90 kPa. Were evaluated in the same manner as in Example 9 while obtaining a positive electrode active material. The evaluation results are shown in Tables 1 and 2.
母材を組成がLi1.20(Ni0.35Co0.35Mn0.30)0.995W0.005O2で表されるリチウム金属複合酸化物の焼成粉末(平均粒径:4.97μm、〔(d90-d10)/平均粒径〕0.41、空隙率:15.6%)とした以外は実施例1と同様にして、正極活物質を得るとともに評した。評価結果を表1及び表2に示す。なお、母材の上記組成は、NiとCoとMnとのモル比(Ni:Co:Mn)が0.35:0.35:0.30であり、Ni、Co及びMnの合計とWとのモル比(Ni+Co+Mn:W)が0.995:0.005であり、かつ、LiとMe(Ni、Co、Mn及びWの合計)とのモル比(Li:Me)が1.20:1であることを示す。
(実施例10)
水の添加量を3質量%とした以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例11)
水の添加量を5質量%とした以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例12)
水の添加量を7質量%とした以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例13)
水の添加量を14質量%とした以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例14)
水の添加量を30質量%とした以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例15)
母材とする焼成粉末をバットに入れ、スプレーボトルを用いて、平均の液滴径が約300μmになるような条件で、リチウム金属複合酸化物粉末に対して3質量%の水を噴霧して添加しながら混合した以外は実施例9と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。
(実施例16)
母材とする焼成粉末をヘンシェルミキサー(日本コークス(株)製FM20C/I)に入れ、タンク内で撹拌羽を用いて焼成粉末を撹拌混合しながら、平均の液滴径が約300μmになるような条件で、スプレーを用いてリチウム金属複合酸化物粉末に対して3質量%の水を噴霧して添加しながら混合し、その後、約-90kPaの減圧雰囲気中において130℃で2時間乾燥する以外は実施例9と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。 Example 9
A calcined powder of a lithium metal composite oxide having a composition of Li 1.20 (Ni 0.35 Co 0.35 Mn 0.30 ) 0.995 W 0.005 O 2 (average particle size: 4) A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that it was set to .97 μm, [(d90-d10) / average particle diameter] 0.41, and porosity: 15.6%). The evaluation results are shown in Tables 1 and 2. The above composition of the base material is such that the molar ratio of Ni, Co, and Mn (Ni: Co: Mn) is 0.35: 0.35: 0.30, and the sum of Ni, Co, and Mn, and W The molar ratio (Ni + Co + Mn: W) is 0.995: 0.005, and the molar ratio (Li: Me) of Li to Me (total of Ni, Co, Mn and W) is 1.20: 1. Indicates that
(Example 10)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 3% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 11)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 5% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 12)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 7% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 13)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 14% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 14)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the amount of water added was 30% by mass. The evaluation results are shown in Tables 1 and 2.
(Example 15)
The fired powder used as a base material is put in a vat, and 3% by mass of water is sprayed on the lithium metal composite oxide powder under the condition that the average droplet diameter is about 300 μm using a spray bottle. A positive electrode active material was obtained and evaluated in the same manner as in Example 9 except that mixing was performed while adding. The evaluation results are shown in Tables 1 and 2.
(Example 16)
Put the calcined powder as the base material into a Henschel mixer (FM20C / I manufactured by Nippon Coke Co., Ltd.) and stir and mix the calcined powder with stirring blades in the tank so that the average droplet diameter is about 300 μm. Under the conditions, 3 mass% water is sprayed and added to the lithium metal composite oxide powder using a spray, and then mixed, and then dried at 130 ° C. for 2 hours in a reduced pressure atmosphere of about −90 kPa. Were evaluated in the same manner as in Example 9 while obtaining a positive electrode active material. The evaluation results are shown in Tables 1 and 2.
(比較例1)
母材をそのまま正極活物質として用いた以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。 (Comparative Example 1)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the base material was directly used as the positive electrode active material. The evaluation results are shown in Tables 1 and 2.
母材をそのまま正極活物質として用いた以外は実施例1と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。 (Comparative Example 1)
A positive electrode active material was obtained and evaluated in the same manner as in Example 1 except that the base material was directly used as the positive electrode active material. The evaluation results are shown in Tables 1 and 2.
(比較例2)
母材をそのまま正極活物質として用いた以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。 (Comparative Example 2)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the base material was directly used as the positive electrode active material. The evaluation results are shown in Tables 1 and 2.
母材をそのまま正極活物質として用いた以外は実施例7と同様にして、正極活物質を得るとともに評価した。評価結果を表1及び表2に示す。 (Comparative Example 2)
A positive electrode active material was obtained and evaluated in the same manner as in Example 7 except that the base material was directly used as the positive electrode active material. The evaluation results are shown in Tables 1 and 2.
(評価結果)
実施例の正極活物質を用いた二次電池は、水を混合しない比較例の正極活物質を用いた二次電池と比較して、初期放電容量、正極抵抗、電池内部抵抗及び容量維持率のいずれも良好な結果が得られた。また、焼成粉末としてWを含むリチウム金属複合酸化物を用いた実施例9~16では、正極抵抗及び電池内部抵抗がより低減された。特に低温時の出力特性を示す電池内部抵抗が顕著に低下した。
さらに、混合する水の量を最適化した実施例1~3、7、8、9~11、15、16は、組成が同じ実施例4~6、12~14と比べてリチウムの引き抜き量が適正化され、正極合材ペーストの低い粘度比を維持しながら、同組成の実施例より出力特性が向上している。特に、水を噴霧して添加した実施例7、8、15、16は、さらに出力特性が向上している。
また、水を混合した実施例1~16では、水を混合しない比較例1、2と比較して、余剰LiOHの含有量が低減する一方、余剰Li2CO3の含有量が増加しており、LiOH/Li2CO3が0.45以下となった。これは、焼成粉末中の余剰LiOHが水の添加及びその後の乾燥する工程においてLi2CO3へ変換されたためと考えられる。
また、実施例の正極活物質を用いた正極合材ペーストは、比較例の正極合材ペーストと比較して、粘度比の値が低く、粘度安定性に優れる。 (Evaluation results)
The secondary battery using the positive electrode active material of the example has an initial discharge capacity, a positive electrode resistance, a battery internal resistance, and a capacity maintenance ratio as compared with the secondary battery using the positive electrode active material of the comparative example in which water is not mixed. In either case, good results were obtained. In Examples 9 to 16 in which the lithium metal composite oxide containing W was used as the fired powder, the positive electrode resistance and the battery internal resistance were further reduced. In particular, the internal resistance of the battery showing output characteristics at low temperatures was significantly reduced.
Further, Examples 1 to 3, 7, 8, 9 to 11, 15 and 16 in which the amount of water to be mixed was optimized had a lithium extraction amount as compared with Examples 4 to 6 and 12 to 14 having the same composition. The output characteristics are improved as compared with the examples of the same composition while maintaining the low viscosity ratio of the positive electrode mixture paste. In particular, the output characteristics of Examples 7, 8, 15, and 16 to which water was added by spraying are further improved.
Further, in Examples 1 to 16 in which water was mixed, the content of surplus LiOH was reduced while the content of surplus Li 2 CO 3 was increased as compared with Comparative Examples 1 and 2 in which water was not mixed. , LiOH / Li 2 CO 3 was 0.45 or less. This is presumably because excess LiOH in the fired powder was converted to Li 2 CO 3 in the step of adding water and subsequent drying.
In addition, the positive electrode mixture paste using the positive electrode active material of the example has a lower viscosity ratio value and excellent viscosity stability than the positive electrode mixture paste of the comparative example.
実施例の正極活物質を用いた二次電池は、水を混合しない比較例の正極活物質を用いた二次電池と比較して、初期放電容量、正極抵抗、電池内部抵抗及び容量維持率のいずれも良好な結果が得られた。また、焼成粉末としてWを含むリチウム金属複合酸化物を用いた実施例9~16では、正極抵抗及び電池内部抵抗がより低減された。特に低温時の出力特性を示す電池内部抵抗が顕著に低下した。
さらに、混合する水の量を最適化した実施例1~3、7、8、9~11、15、16は、組成が同じ実施例4~6、12~14と比べてリチウムの引き抜き量が適正化され、正極合材ペーストの低い粘度比を維持しながら、同組成の実施例より出力特性が向上している。特に、水を噴霧して添加した実施例7、8、15、16は、さらに出力特性が向上している。
また、水を混合した実施例1~16では、水を混合しない比較例1、2と比較して、余剰LiOHの含有量が低減する一方、余剰Li2CO3の含有量が増加しており、LiOH/Li2CO3が0.45以下となった。これは、焼成粉末中の余剰LiOHが水の添加及びその後の乾燥する工程においてLi2CO3へ変換されたためと考えられる。
また、実施例の正極活物質を用いた正極合材ペーストは、比較例の正極合材ペーストと比較して、粘度比の値が低く、粘度安定性に優れる。 (Evaluation results)
The secondary battery using the positive electrode active material of the example has an initial discharge capacity, a positive electrode resistance, a battery internal resistance, and a capacity maintenance ratio as compared with the secondary battery using the positive electrode active material of the comparative example in which water is not mixed. In either case, good results were obtained. In Examples 9 to 16 in which the lithium metal composite oxide containing W was used as the fired powder, the positive electrode resistance and the battery internal resistance were further reduced. In particular, the internal resistance of the battery showing output characteristics at low temperatures was significantly reduced.
Further, Examples 1 to 3, 7, 8, 9 to 11, 15 and 16 in which the amount of water to be mixed was optimized had a lithium extraction amount as compared with Examples 4 to 6 and 12 to 14 having the same composition. The output characteristics are improved as compared with the examples of the same composition while maintaining the low viscosity ratio of the positive electrode mixture paste. In particular, the output characteristics of Examples 7, 8, 15, and 16 to which water was added by spraying are further improved.
Further, in Examples 1 to 16 in which water was mixed, the content of surplus LiOH was reduced while the content of surplus Li 2 CO 3 was increased as compared with Comparative Examples 1 and 2 in which water was not mixed. , LiOH / Li 2 CO 3 was 0.45 or less. This is presumably because excess LiOH in the fired powder was converted to Li 2 CO 3 in the step of adding water and subsequent drying.
In addition, the positive electrode mixture paste using the positive electrode active material of the example has a lower viscosity ratio value and excellent viscosity stability than the positive electrode mixture paste of the comparative example.
なお、法令で許容される限りにおいて、日本特許出願である特願2016-060745、特願2016-118644、特願2016-248296、及び上述の実施形態などで引用した全ての文献、の内容を援用して本文の記載の一部とする。
As far as permitted by law, the contents of Japanese Patent Application Nos. 2016-060745, 2016-118644, 2016-248296, and all the references cited in the above-described embodiments are incorporated. As a part of the description of the text.
B……コイン型電池
1……正極(評価用電極)
2……負極
3……セパレータ
4……ガスケット
5……ウェーブワッシャー
6……正極缶
7……負極缶
C……ラミネートセル
8……正極シート
9……負極シート
10……セパレータ
11……アルミラミネートシート
HS……熱融着部 B …… Coin-type battery 1 …… Positive electrode (Evaluation electrode)
2 ...Negative electrode 3 ... Separator 4 ... Gasket 5 ... Wave washer 6 ... Positive electrode can 7 ... Negative electrode can C ... Laminate cell 8 ... Positive electrode sheet 9 ... Negative electrode sheet 10 ... Separator 11 ... Aluminum Laminate sheet HS ... Heat seal
1……正極(評価用電極)
2……負極
3……セパレータ
4……ガスケット
5……ウェーブワッシャー
6……正極缶
7……負極缶
C……ラミネートセル
8……正極シート
9……負極シート
10……セパレータ
11……アルミラミネートシート
HS……熱融着部 B …… Coin-
2 ...
Claims (17)
- 層状構造の結晶構造を有するリチウム金属複合酸化物からなる焼成粉末と水とを混合することと、前記混合して得られた混合物を乾燥することと、を備え、
前記焼成粉末は、一般式(1):LisNi1-x-y-zCoxMnyM1 zO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、M1は、V、Mg、Mo、Nb、Ti、WおよびAlから選ばれる少なくとも1種の元素)で表され、一次粒子が凝集して形成された二次粒子を含み、
前記水は、得られる正極活物質5gを100mlの純水に分散させ、10分間静置後の上澄み液を測定した際の25℃におけるpHが11以上11.9以下の範囲となる量を混合する、ことを特徴とする非水系電解質二次電池用正極活物質の製造方法。 Mixing a fired powder composed of a lithium metal composite oxide having a layered crystal structure and water, and drying the mixture obtained by mixing,
The calcined powder has the general formula (1): Li s Ni 1-xyz Co x Mn y M 1 z O 2 (where 0.05 ≦ x ≦ 0.35, 0 ≦ y ≦ 0.35 , 0 ≦ z ≦ 0.10, 0.95 ≦ s ≦ 1.50, M 1 is represented by at least one element selected from V, Mg, Mo, Nb, Ti, W and Al), and primary Including secondary particles formed by aggregation of particles,
In the water, 5 g of the obtained positive electrode active material is dispersed in 100 ml of pure water and mixed in such an amount that the pH at 25 ° C. is in the range of 11 to 11.9 when the supernatant liquid after standing for 10 minutes is measured. The manufacturing method of the positive electrode active material for non-aqueous electrolyte secondary batteries characterized by the above-mentioned. - 前記焼成粉末と水とを混合する際に、前記焼成粉末に、水を1μm以上2000μm以下の液滴サイズに噴霧して混合する、ことを特徴とする請求項1に記載の非水系電解質二次電池用正極活物質の製造方法。 2. The non-aqueous electrolyte secondary according to claim 1, wherein when the fired powder and water are mixed, the fired powder is mixed by spraying water to a droplet size of 1 μm or more and 2000 μm or less. A method for producing a positive electrode active material for a battery.
- 前記水を、前記焼成粉末に対して1質量%以上35質量%以下の範囲で混合する、請求項1または請求項2に記載の非水系電解質二次電池用正極活物質の製造方法。 The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the water is mixed in a range of 1% by mass to 35% by mass with respect to the fired powder.
- 前記水を、前記焼成粉末の表面積に対して0.003g/m2以上0.025g/m2以下の範囲で混合する、請求項1~請求項3のいずれか一項に記載の非水系電解質二次電池用正極活物質の製造方法。 The water, mixed with 0.003 g / m 2 or more 0.025 g / m 2 or less in the range of the surface area of the calcined powder, a non-aqueous electrolyte according to any one of claims 1 to 3 A method for producing a positive electrode active material for a secondary battery.
- 前記水を、前記焼成粉末に対して1質量%以上6質量%以下の範囲で混合する、請求項1~請求項4のいずれか一項に記載の非水系電解質二次電池用正極活物質の製造方法。 The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein the water is mixed in a range of 1% by mass to 6% by mass with respect to the fired powder. Production method.
- 前記焼成粉末は、平均粒径が3μm以上15μm以下の範囲にあり、粒度分布の広がりを示す指標である〔(d90-d10)/平均粒径〕が0.7以下である、請求項1~請求項5のいずれか一項に記載の非水系電解質二次電池用正極活物質の製造方法。 The fired powder has an average particle diameter in the range of 3 μm to 15 μm, and an index indicating the spread of the particle size distribution [(d90−d10) / average particle diameter] is 0.7 or less. The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries as described in any one of Claims 5.
- 前記焼成粉末は、断面観察により計測される空隙が占める面積割合が、該焼成粉末の断面積全体に対して4.5%以上60%以下である請求項1~請求項6のいずれか一項に記載の非水系電解質二次電池用正極活物質の製造方法。 The area ratio of voids measured by cross-sectional observation of the fired powder is 4.5% or more and 60% or less with respect to the entire cross-sectional area of the fired powder. The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries as described in any one of.
- 前記乾燥は、100℃以上300℃以下で行う、請求項1~請求項7のいずれか一項に記載の非水系電解質二次電池用正極活物質の製造方法。 The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 7, wherein the drying is performed at 100 ° C or higher and 300 ° C or lower.
- 前記焼成粉末は、一般式(2):LisNi1-x-y-z-tCoxMnyM2 zWtO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、0.0001≦t≦0.03、0.0001≦z+t≦0.10、M2は、V、Mg、Mo、Nb、TiおよびAlから選ばれる少なくとも1種の元素)で表される、請求項1~請求項8のいずれか一項に記載の非水系電解質二次電池用正極活物質の製造方法。 The calcined powder has the general formula (2): Li s Ni 1- xyzt Co x Mn y M 2 z W t O 2 (where 0.05 ≦ x ≦ 0.35, 0 ≦ y ≦ 0.35,0 ≦ z ≦ 0.10,0.95 ≦ s ≦ 1.50,0.0001 ≦ t ≦ 0.03,0.0001 ≦ z + t ≦ 0.10, M 2 is, V, Mg The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 8, represented by: at least one element selected from Mo, Nb, Ti and Al) .
- 層状構造の結晶構造を有するリチウム金属複合酸化物粉末からなる非水系電解質二次電池用正極活物質であって、
前記リチウム金属複合酸化物粉末は、一般式(1):LisNi1-x-y-zCoxMnyM1 zO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、M1は、V、Mg、Mo、Nb、Ti、WおよびAlから選ばれる少なくとも1種の元素)で表され、一次粒子が凝集して形成された二次粒子を含み、
前記正極活物質5gを100mlの純水に分散させ、10分間静置後の上澄み液を測定した際の25℃におけるpHが11~11.9であり、
滴定法によって定量される余剰LiOHと余剰Li2CO3の質量の比(余剰LiOH/余剰Li2CO3)が0.45以下である、非水系電解質二次電池用正極活物質。 A positive electrode active material for a non-aqueous electrolyte secondary battery comprising a lithium metal composite oxide powder having a layered crystal structure,
The lithium metal composite oxide powder has the general formula (1): Li s Ni 1-xyz Co x Mn y M 1 z O 2 (where 0.05 ≦ x ≦ 0.35, 0 ≦ y ≦ 0.35, 0 ≦ z ≦ 0.10, 0.95 ≦ s ≦ 1.50, M 1 is at least one element selected from V, Mg, Mo, Nb, Ti, W and Al) Including secondary particles formed by aggregation of primary particles,
5 g of the positive electrode active material was dispersed in 100 ml of pure water, and the pH at 25 ° C. when measuring the supernatant after standing for 10 minutes was 11 to 11.9,
A positive electrode active material for a non-aqueous electrolyte secondary battery, wherein a mass ratio of surplus LiOH and surplus Li 2 CO 3 (surplus LiOH / surplus Li 2 CO 3 ) determined by a titration method is 0.45 or less. - 前記余剰LiOHと余剰Li2CO3の量の比(余剰LiOH/余剰Li2CO3)が0.3以下である、請求項10に記載の非水系電解質二次電池用正極活物質。 The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 10, wherein a ratio of the amount of surplus LiOH to surplus Li 2 CO 3 (surplus LiOH / surplus Li 2 CO 3 ) is 0.3 or less.
- 前記余剰LiOHと余剰Li2CO3の量の比(余剰LiOH/余剰Li2CO3)が0.18以上であり、余剰Li2CO3の量が前記正極活物質の表面積に対して0.157×10-2g/m2以下である、請求項10または請求項11に記載の非水系電解質二次電池用正極活物質。 The ratio of the amount of surplus LiOH to surplus Li 2 CO 3 (surplus LiOH / surplus Li 2 CO 3 ) is 0.18 or more, and the amount of surplus Li 2 CO 3 is 0. 0 relative to the surface area of the positive electrode active material. The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 10 or 11, wherein the positive electrode active material is 157 × 10 −2 g / m 2 or less.
- 平均粒径が3μm以上15μm以下の範囲にあり、粒度分布の広がりを示す指標である〔(d90-d10)/平均粒径〕が0.7以下である、請求項10~請求項12のいずれか一項に記載の非水系電解質二次電池用正極活物質。 The average particle diameter is in the range of 3 μm or more and 15 μm or less, and [(d90−d10) / average particle diameter], which is an index showing the spread of the particle size distribution, is 0.7 or less. A positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1.
- 前記リチウム金属複合酸化物粉末の断面観察において計測される空隙が占める面積割合が、該リチウム金属複合酸化物粒子全体の断面積に対して4.5%以上60%以下ある、請求項10~請求項13のいずれか一項に記載の非水系電解質二次電池用正極活物質。 The area ratio occupied by voids measured in cross-sectional observation of the lithium metal composite oxide powder is 4.5% or more and 60% or less with respect to the cross-sectional area of the entire lithium metal composite oxide particle. Item 14. The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of Items 13.
- 前記リチウム金属複合酸化物粉末は、一般式(2):LisNi1-x-y-z-tCoxMnyM2 zWtO2(ただし、0.05≦x≦0.35、0≦y≦0.35、0≦z≦0.10、0.95≦s≦1.50、0.0001≦t≦0.03、0.0001≦z+t≦0.10、M2は、V、Mg、Mo、Nb、TiおよびAlから選ばれる少なくとも1種の元素)で表される、請求項10~請求項14のいずれか一項に記載の非水系電解質二次電池用正極活物質。 The lithium metal composite oxide powder represented by the general formula (2): Li s Ni 1 -x-y-z-t Co x Mn y M 2 z W t O 2 ( however, 0.05 ≦ x ≦ 0.35 , 0 ≦ y ≦ 0.35, 0 ≦ z ≦ 0.10, 0.95 ≦ s ≦ 1.50, 0.0001 ≦ t ≦ 0.03, 0.0001 ≦ z + t ≦ 0.10, M 2 is The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 10 to 14, represented by: at least one element selected from V, Mg, Mo, Nb, Ti and Al). material.
- 請求項10~請求項15のいずれか一項に記載の非水系電解質二次電池用正極活物質を含む、非水系電解質二次電池用正極合材ペースト。 A positive electrode mixture paste for a non-aqueous electrolyte secondary battery, comprising the positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 10 to 15.
- 請求項10~請求項15のいずれか一項に記載の非水系電解質二次電池用正極活物質を含む正極を有する、非水系電解質二次電池。 A non-aqueous electrolyte secondary battery having a positive electrode comprising the positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 10 to 15.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201780030656.XA CN109155413B (en) | 2016-03-24 | 2017-03-22 | Positive electrode active material, method for producing same, paste, and secondary battery |
US16/086,746 US20190051929A1 (en) | 2016-03-24 | 2017-03-22 | Positive electrode active material for non-aqueous electrolyte secondary battery and method for manufacturing the same, positive electrode mixed material paste for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2016-060745 | 2016-03-24 | ||
JP2016060745 | 2016-03-24 | ||
JP2016118644 | 2016-06-15 | ||
JP2016-118644 | 2016-06-15 | ||
JP2016-248296 | 2016-12-21 | ||
JP2016248296A JP7135269B2 (en) | 2016-03-24 | 2016-12-21 | Positive electrode active material for non-aqueous electrolyte secondary battery and its manufacturing method, positive electrode mixture paste for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2017164237A1 true WO2017164237A1 (en) | 2017-09-28 |
Family
ID=59900238
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2017/011450 WO2017164237A1 (en) | 2016-03-24 | 2017-03-22 | Positive-electrode active material for non-aqueous-electrolyte secondary cell and method for manufacturing same, positive-electrode material paste for non-aqueous-electrolyte secondary cell, and non-aqueous-electrolyte secondary cell |
Country Status (1)
Country | Link |
---|---|
WO (1) | WO2017164237A1 (en) |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH10302779A (en) * | 1997-04-25 | 1998-11-13 | Sony Corp | Production of positive electrode active material |
JPH10340726A (en) * | 1997-06-04 | 1998-12-22 | Mitsui Mining & Smelting Co Ltd | Manufacture of positive active material for lithium secondary battery and battery using the same |
JP2010080394A (en) * | 2008-09-29 | 2010-04-08 | Sumitomo Metal Mining Co Ltd | Positive electrode active material for nonaqueous electrolyte secondary battery and manufacturing method therefor, and nonaqueous electrolyte secondary battery |
JP2011023121A (en) * | 2009-07-13 | 2011-02-03 | Nippon Chem Ind Co Ltd | Positive active material for lithium secondary battery, method of manufacturing the same, and lithium secondary battery |
JP2012003891A (en) * | 2010-06-15 | 2012-01-05 | Nissan Motor Co Ltd | Method for producing active material |
JP2012252844A (en) * | 2011-06-01 | 2012-12-20 | Sumitomo Metal Mining Co Ltd | Transition metal complex hydroxide suitable for precursor of positive electrode active material for nonaqueous electrolyte secondary battery and method for manufacturing the same, positive electrode active material for nonaqueous electrolyte secondary battery and method for manufacturing the same, and nonaqueous electrolyte secondary battery comprising the positive electrode active material |
JP2012256435A (en) * | 2011-06-07 | 2012-12-27 | Sumitomo Metal Mining Co Ltd | Nickel manganese composite hydroxide particle and production method thereof, positive electrode active material for nonaqueous electrolyte secondary battery and production method thereof, and nonaqueous electrolyte secondary battery |
JP2015130340A (en) * | 2014-01-06 | 2015-07-16 | 深▲セン▼市貝特瑞新能源材料股▲ふん▼有限公司 | Lithium nickel cobalt aluminum oxide composite positive electrode material, method for producing the same, and lithium ion secondary battery |
-
2017
- 2017-03-22 WO PCT/JP2017/011450 patent/WO2017164237A1/en active Application Filing
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH10302779A (en) * | 1997-04-25 | 1998-11-13 | Sony Corp | Production of positive electrode active material |
JPH10340726A (en) * | 1997-06-04 | 1998-12-22 | Mitsui Mining & Smelting Co Ltd | Manufacture of positive active material for lithium secondary battery and battery using the same |
JP2010080394A (en) * | 2008-09-29 | 2010-04-08 | Sumitomo Metal Mining Co Ltd | Positive electrode active material for nonaqueous electrolyte secondary battery and manufacturing method therefor, and nonaqueous electrolyte secondary battery |
JP2011023121A (en) * | 2009-07-13 | 2011-02-03 | Nippon Chem Ind Co Ltd | Positive active material for lithium secondary battery, method of manufacturing the same, and lithium secondary battery |
JP2012003891A (en) * | 2010-06-15 | 2012-01-05 | Nissan Motor Co Ltd | Method for producing active material |
JP2012252844A (en) * | 2011-06-01 | 2012-12-20 | Sumitomo Metal Mining Co Ltd | Transition metal complex hydroxide suitable for precursor of positive electrode active material for nonaqueous electrolyte secondary battery and method for manufacturing the same, positive electrode active material for nonaqueous electrolyte secondary battery and method for manufacturing the same, and nonaqueous electrolyte secondary battery comprising the positive electrode active material |
JP2012256435A (en) * | 2011-06-07 | 2012-12-27 | Sumitomo Metal Mining Co Ltd | Nickel manganese composite hydroxide particle and production method thereof, positive electrode active material for nonaqueous electrolyte secondary battery and production method thereof, and nonaqueous electrolyte secondary battery |
JP2015130340A (en) * | 2014-01-06 | 2015-07-16 | 深▲セン▼市貝特瑞新能源材料股▲ふん▼有限公司 | Lithium nickel cobalt aluminum oxide composite positive electrode material, method for producing the same, and lithium ion secondary battery |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP7077943B2 (en) | Positive electrode active material for non-aqueous electrolyte secondary battery and its manufacturing method, positive electrode mixture paste for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery | |
JP6777081B2 (en) | Positive electrode active material for non-aqueous electrolyte secondary batteries and non-aqueous electrolyte secondary batteries | |
JP7013871B2 (en) | Positive electrode active material for non-aqueous electrolyte secondary battery and its manufacturing method, positive electrode mixture paste for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery | |
JP7135269B2 (en) | Positive electrode active material for non-aqueous electrolyte secondary battery and its manufacturing method, positive electrode mixture paste for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery | |
JP7024292B2 (en) | Positive electrode active material for non-aqueous electrolyte secondary battery and its manufacturing method, and non-aqueous electrolyte secondary battery | |
CN111295786B (en) | Positive electrode active material for nonaqueous electrolyte secondary battery, method for producing same, and nonaqueous electrolyte secondary battery using positive electrode active material | |
WO2018043515A1 (en) | Positive electrode active substance for non-aqueous electrolyte secondary battery and method for producing same, positive electrode mixture paste for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery | |
CN111295785B (en) | Positive electrode active material for nonaqueous electrolyte secondary battery, method for producing same, and nonaqueous electrolyte secondary battery using positive electrode active material | |
KR20130051012A (en) | Positive electrode active material for nonaqueous electrolyte secondary batteries, method for manufacturing the same, and nonaqueous electrolyte secondary battery using said positive electrode active material | |
JP2017134996A (en) | Positive electrode active material for nonaqueous electrolyte secondary battery and method of producing the same, and nonaqueous electrolyte secondary battery including the positive electrode active material | |
US11967713B2 (en) | Positive electrode active material for non-aqueous electrolyte secondary battery comprising tungsten coating film, and non-aqueous electrolyte secondary battery | |
JP2019046716A (en) | Positive electrode active material for nonaqueous electrolyte secondary battery, method for manufacturing the same, and nonaqueous electrolyte secondary battery | |
JP2021005474A (en) | Cathode active material for lithium ion secondary battery, manufacturing method of the same, and the lithium ion secondary battery | |
WO2016104305A1 (en) | Positive electrode active material for nonaqueous electrolyte secondary cell, method for manufacturing said material, and nonaqueous electrolyte secondary cell in which said material is used | |
WO2017034000A1 (en) | Positive electrode active material for non-aqueous electrolyte secondary cell and method for manufacturing said material, and non-aqueous electrolyte secondary cell | |
JP2018032543A (en) | Positive electrode active material for nonaqueous electrolyte secondary battery, method for manufacturing the same, and nonaqueous electrolyte secondary battery | |
JP6848199B2 (en) | A method for producing a positive electrode material for a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte secondary battery using the positive electrode material, and a positive electrode material for a non-aqueous electrolyte secondary battery. | |
JP2018195419A (en) | Positive electrode material for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery arranged by use thereof, and method for manufacturing positive electrode material for nonaqueous electrolyte secondary battery | |
JP6819859B2 (en) | A method for producing a positive electrode material for a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte secondary battery using the positive electrode material, and a positive electrode material for a non-aqueous electrolyte secondary battery. | |
JP2019212365A (en) | Positive electrode active material for lithium ion secondary battery and manufacturing method thereof, and lithium ion secondary battery using the same | |
JP7276323B2 (en) | Positive electrode active material for non-aqueous electrolyte secondary batteries | |
JP7143593B2 (en) | Method for producing positive electrode active material for non-aqueous electrolyte secondary battery | |
JP7020101B2 (en) | Positive active material for non-aqueous electrolyte secondary battery, manufacturing method of positive positive active material for non-aqueous electrolyte secondary battery, non-aqueous electrolyte secondary battery | |
JP6969239B2 (en) | Positive electrode active material for non-aqueous electrolyte secondary batteries and its manufacturing method | |
WO2017164237A1 (en) | Positive-electrode active material for non-aqueous-electrolyte secondary cell and method for manufacturing same, positive-electrode material paste for non-aqueous-electrolyte secondary cell, and non-aqueous-electrolyte secondary cell |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 17770277 Country of ref document: EP Kind code of ref document: A1 |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 17770277 Country of ref document: EP Kind code of ref document: A1 |