WO2021045025A1 - リチウムイオン二次電池用正極活物質、及びその製造方法、並びにリチウムイオン二次電池 - Google Patents
リチウムイオン二次電池用正極活物質、及びその製造方法、並びにリチウムイオン二次電池 Download PDFInfo
- Publication number
- WO2021045025A1 WO2021045025A1 PCT/JP2020/032980 JP2020032980W WO2021045025A1 WO 2021045025 A1 WO2021045025 A1 WO 2021045025A1 JP 2020032980 W JP2020032980 W JP 2020032980W WO 2021045025 A1 WO2021045025 A1 WO 2021045025A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- positive electrode
- active material
- electrode active
- lithium
- heat treatment
- 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
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G53/00—Compounds of nickel
- C01G53/006—Compounds containing, besides nickel, two or more other elements, with the exception of oxygen or hydrogen
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G53/00—Compounds of nickel
- C01G53/40—Nickelates
- C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G53/00—Compounds of nickel
- C01G53/40—Nickelates
- C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
- C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
- C01G53/50—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese of the type [MnO2]n-, e.g. Li(NixMn1-x)O2, Li(MyNixMn1-x-y)O2
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/50—Solid solutions
- C01P2002/52—Solid solutions containing elements as dopants
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- 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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
-
- 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 lithium ion secondary battery, a method for producing the same, and a lithium ion secondary battery using the positive electrode active material.
- Lithium-ion secondary batteries are widely used as lightweight secondary batteries having a high energy density.
- the positive electrode active material which greatly affects the battery characteristics, studies have been made on the establishment of high capacity and mass productivity, reduction of lithium ion resistance, stabilization of the crystal structure, and the like.
- a positive electrode active material for a lithium ion secondary battery a lithium transition metal composite oxide having an ⁇ -NaFeO type 2 crystal structure (hereinafter, may be referred to as a layered structure) is widely known.
- nickel-based ones are composed of nickel, which is cheaper than cobalt and the like, and exhibit a relatively high capacity, so that they are expected to be applied to various applications.
- expectations are rising as a positive electrode active material for lithium ion secondary batteries in which the ratio of nickel per metal (Ni, Co, Mn, etc.) excluding lithium is increased.
- a lithium transition metal composite oxide with a high proportion of nickel is used, the slurry for positive electrode coating tends to gel. When gelled, there is a problem that the viscosity of the positive electrode mixture slurry increases and it becomes difficult to coat the electrode.
- a lithium transition metal composite oxide having a high nickel content is a residual alkaline component containing lithium such as lithium hydroxide and lithium carbonate, which remains on the surface of oxide particles as compared with those having a low nickel content.
- a positive electrode mixture slurry is prepared by mixing with a binder or the like. At this time, the binder is easily denatured due to the residual alkaline component, and the positive electrode mixture slurry is easily gelled.
- Patent Document 1 As a means for reducing the residual alkaline component, in Patent Document 1, in the positive electrode active material particles made of a lithium composite oxide, the firing temperature is set to 850 ° C. or higher, and the particles are held in the air atmosphere for the set firing temperature and a predetermined time. , The atmosphere during lowering the set firing temperature is switched from the atmospheric atmosphere to a low carbon dioxide gas atmosphere in which the carbon dioxide concentration is 1/60 or less of the carbon dioxide concentration in the atmospheric atmosphere, and a precursor containing Ni, Co and Mn. A method for reducing the amount of residual lithium in the positive electrode active material particles is shown, which comprises at least a step of calcining a mixture of the body compound and the lithium compound to prepare a lithium composite oxide.
- a non-aqueous electrolyte secondary battery comprising a step of forming, washing the slurry with water by stirring, filtering, and then heat-treating at a temperature of 120 ° C. or higher and 550 ° C. or lower in an oxygen atmosphere having an oxygen concentration of 80% by volume or more.
- a method for producing a positive electrode active material for use is shown.
- Patent Document 1 after holding at a predetermined firing temperature in an atmospheric atmosphere for a predetermined time, the atmosphere is switched from the atmospheric atmosphere to a low carbon dioxide gas atmosphere to lower the temperature, thereby reducing the amount of residual lithium carbonate generated in the temperature lowering process. ing.
- a high nickel type having a nickel content of 80% or more lithium is contained even when the carbon dioxide gas contained in the atmosphere is maintained for a predetermined time (about 3 to 10 hours) at the firing temperature. The reaction to produce lithium carbonate from the transition metal composite oxide proceeds. Therefore, it has been difficult to sufficiently reduce the residual alkaline component.
- Patent Document 2 the residual alkaline component is reduced by washing the lithium nickel composite oxide with water. At this time, by defining the amounts of the lithium nickel composite oxide and water, the extraction of lithium from the lithium nickel composite oxide particles is suppressed. However, when the particles are washed with water, lithium is extracted in the vicinity of the surface layer of the particles to a considerable extent, so that capacity reduction and increase in positive electrode resistance due to lithium deficiency are likely to occur. Further, washing with water itself increases the number of processes, which is not preferable in terms of production efficiency.
- An object of the present invention is to provide an ion secondary battery.
- the positive electrode active material for a lithium ion secondary battery according to the present invention has the following composition formula (1); Li 1 + a Ni b Co c M d X e O 2 + ⁇ ... (1)
- M represents at least one selected from Al and Mn
- X represents one or more metal elements other than Li, Ni, Co, Al and Mn
- a and b , C, d, e and ⁇ are ⁇ 0.04 ⁇ a ⁇ 0.04, 0.80 ⁇ b ⁇ 1.0, 0 ⁇ c ⁇ 0.15, 0 ⁇ d ⁇ 0.20, 0, respectively.
- the ratio L2 / L1 of the residual lithium hydroxide amount (L2) calculated by neutralization titration after compressing the positive electrode active material at a pressure of 160 MPa and the ratio L2 / L1 to the L1 is 1.10 or less. It is a positive electrode active material for a lithium ion secondary battery.
- composition formula (1) Li 1 + a Ni b Co c M d X e O 2 + ⁇ ...
- M represents at least one selected from Al and Mn
- X represents one or more metal elements other than Li, Ni, Co, Al and Mn
- a and b C, d, e and ⁇ are ⁇ 0.04 ⁇ a ⁇ 0.04, 0.80 ⁇ b ⁇ 1.0, 0 ⁇ c ⁇ 0.15, 0 ⁇ d ⁇ 0.2, 0, respectively.
- the granulated body comprises a firing step of obtaining a lithium transition metal composite oxide represented by the composition formula (1), and the firing step sets the heat treatment temperature to at least 600 ° C. or higher and lower than 750 ° C.
- the present invention is a lithium ion secondary battery including a positive electrode containing the above-mentioned positive electrode active material for a lithium ion secondary battery.
- a positive electrode active material for a lithium ion secondary battery having a high Ni ratio of 80% or more of nickel as in the present invention (hereinafter, may be simply referred to as “positive electrode active material”)
- positive electrode active material In the firing step, Most of Ni changes from a stable +2 valence to an unstable +3 valence. Therefore, the crystal structure is unstable, and a part of Li is not taken into the positive electrode active material, or Li near the surface of the positive electrode active material is extracted after firing, and a residual alkaline component is left on the surface of the positive electrode active material. Exists.
- the residual alkali component derived from the high Ni ratio remains inside the secondary particles, and not only the residual alkali component on the surface of the positive electrode active material is reduced, but also the residual alkali inside the secondary particles is reduced. It is characterized by reducing the components as well. Specifically, in the firing step, after the main firing, an annealing treatment was added in which the temperature was lowered over a predetermined time in a temperature range of 700 ° C. or higher and 800 ° C. or lower. By performing the annealing treatment, the residual alkaline component on the surface of the primary particle is reacted and incorporated into the primary particle, and as a result, the residual alkaline component inside the secondary particle can be reduced.
- the positive electrode active material is compressed to break the secondary particles and the inside of the secondary particles is exposed during the coating of the mixture, the residual alkaline component does not increase. Therefore, it is possible to provide a positive electrode active material that suppresses gelation of the positive electrode mixture slurry and satisfies high capacity and high cycle characteristics.
- a positive electrode active material having a nickel content of 80% or more and a high Ni ratio it is possible to obtain a good positive electrode mixture slurry in which gelation during coating of the mixture is suppressed. Further, a positive electrode active material for a lithium ion secondary battery having a high discharge capacity and good charge / discharge cycle characteristics can be provided by a highly productive manufacturing method. Then, a lithium ion secondary battery using this positive electrode active material can be provided.
- the positive electrode active material according to the present embodiment has an ⁇ -NaFeO type 2 crystal structure exhibiting a layered structure, and contains a lithium transition metal composite oxide composed of lithium and a transition metal.
- the positive electrode active material is mainly composed of primary particles of a lithium transition metal composite oxide and secondary particles formed by aggregating a plurality of primary particles. Further, the lithium transition metal composite oxide has a layered structure as a main phase capable of inserting and removing lithium ions.
- the positive electrode active material according to the present embodiment includes a lithium transition metal composite oxide as a main component, unavoidable impurities derived from a raw material and a manufacturing process, and other components that coat particles of the lithium transition metal composite oxide, for example. It may contain a boron component, a phosphorus component, a sulfur component, a fluorine component, an organic substance, and other components mixed with particles of a lithium transition metal composite oxide.
- the lithium transition metal composite oxide according to this embodiment is represented by the following composition formula (1).
- M represents at least one selected from Al and Mn
- X represents one or more metal elements other than Li, Ni, Co, Al and Mn
- the lithium transition metal composite oxide represented by the composition formula (1) has a nickel ratio of 80% or more per metal excluding lithium. That is, Ni is contained in an amount of 80% or more in terms of the atomic number fraction with respect to the total of Ni, Co, M and X. Since the nickel content is high, it is a nickel-based oxide that can realize a high discharge capacity. Further, since the nickel content is high, the raw material cost is low as compared with LiCoO 2 and the like, and it is also excellent from the viewpoint of productivity including the raw material cost.
- a in the composition formula (1) is ⁇ 0.04 or more and 0.04 or less.
- a represents the excess or deficiency of lithium with respect to Li (Ni, Co, M, X) O 2 in the stoichiometric ratio. a is not the value charged at the time of raw material synthesis, but the value in the lithium transition metal composite oxide obtained by firing.
- the excess or deficiency of lithium in the composition formula (1) is excessive, that is, when the composition has an excessively small amount of lithium or an excessively large amount of lithium with respect to the total of Ni, Co, M and X, at the time of firing.
- the synthesis reaction does not proceed properly, and it remains as a residual alkaline component on the surface of the positive electrode active material, cation mixing in which nickel is mixed in the lithium site is likely to occur, and the crystallinity is likely to be lowered.
- the proportion of nickel is increased to 80% or more, the occurrence of such residual alkaline components and cation mixing and the decrease in crystallinity are likely to be remarkable, and the positive electrode mixture slurry gels or the discharge capacity is increased.
- the charge / discharge cycle characteristics are likely to be impaired.
- the residual alkaline component and cation mixing are reduced, and the performance of various batteries can be improved. Therefore, even in a composition having a high nickel content, gelation of the positive electrode mixture slurry can be suppressed, and a high discharge capacity and good charge / discharge cycle characteristics can be obtained.
- A is preferably 0.00 or more and 0.04 or less.
- a is 0.00 or more, lithium is not insufficient with respect to the stoichiometric ratio, so that the synthetic reaction proceeds appropriately at the time of firing, and cation mixing is less likely to occur. Therefore, a layered structure with fewer defects is formed, and high discharge capacity and good charge / discharge cycle characteristics can be obtained. Further, when a is 0.04 or less, the amount of excess lithium is small with respect to the chemical quantity theory ratio, the residual alkaline component on the surface of the positive electrode active material is small, and the positive electrode mixture slurry is difficult to gel.
- the atomic concentration (number of moles) of lithium contained in the positive electrode active material and the metal elements other than lithium are also used.
- the ratio to the total atomic concentration (number of moles) is preferably 0.96 or more and 1.04 or less, and more preferably 1.00 or more and 1.04 or less.
- Other components may be mixed in the calcination precursor fired by the heat treatment, and the reaction ratio at the time of calcination may deviate from the stoichiometric ratio.
- the preferred range of a in the powder state produced as the positive electrode active material has been described above, but when the positive electrode active material represented by the composition formula (1) is incorporated in the positive electrode of the lithium ion secondary battery. Is preferably in the range of ⁇ 0.9 to 0.04 for a because charging / discharging accompanied by insertion / removal of Li is carried out.
- the nickel coefficient b in the composition formula (1) is 0.80 or more and 1.00 or less.
- b is 0.80 or more, the nickel content is low, which is higher than other nickel-based oxides and ternary oxides represented by Li (Ni, Co, M) O 2.
- the discharge capacity can be obtained.
- the amount of transition metal, which is rarer than nickel can be reduced, the raw material cost can be reduced.
- the nickel coefficient b may be 0.85 or more, 0.90 or more, or 0.92 or more.
- the nickel coefficient b may be 0.95 or less, 0.90 or less, or 0.85 or less.
- the cobalt coefficient c in the composition formula (1) is 0 or more and 0.15 or less.
- Cobalt may be added positively or may have a composition ratio corresponding to unavoidable impurities.
- the crystal structure becomes more stable, and effects such as suppression of cation mixing in which nickel is mixed in lithium sites can be obtained. Therefore, high discharge capacity and good charge / discharge cycle characteristics can be obtained.
- the amount of cobalt is excessive, the raw material cost of the positive electrode active material becomes high.
- the proportion of other transition metals such as nickel becomes low, and there is a risk that the discharge capacity becomes low and the effect of the metal element represented by M becomes low.
- the raw material cost of the lithium transition metal composite oxide exhibiting high discharge capacity, good rate characteristics and charge / discharge cycle characteristics can be reduced.
- the cobalt coefficient c is preferably 0.01 or more and 0.10 or less from the viewpoint of reducing raw material costs and conserving resources. More preferably, it is 0.02 or more and 0.07 or less. The smaller c is, the more the raw material cost can be reduced.
- M in the composition formula (1) is at least one kind of metal element selected from Al and Mn. These elements can be replaced with Nisite, and since Al is a main group element, it exists stably without changing its valence during charging and discharging. Although Mn is a transition metal, it remains stable at +4 valence during charging and discharging. It is believed to exist. Therefore, when these metal elements are used, the effect of stabilizing the crystal structure during charging and discharging can be obtained.
- the coefficient d of M in the composition formula (1) is 0 or more and 0.20 or less. If the metal element represented by M is excessive, the proportion of other transition metals such as nickel becomes low, and the discharge capacity of the positive electrode active material may become low. On the other hand, when d is in the above numerical range, higher discharge capacity, good rate characteristics and charge / discharge cycle characteristics tend to be obtained.
- X in the composition formula (1) is one or more metal elements other than Li, Ni, Co, Al and Mn (hereinafter, may be referred to as X element or element X).
- X is an element capable of forming an ⁇ -NaFeO type 2 crystal structure exhibiting a layered structure, and can be selected according to the required properties. For example, in the case of a metal element that reacts with Li to form a concentrated layer after forming an ⁇ -NaFeO type 2 crystal structure that exhibits a layered structure by reacting Li and Ni, the reaction between Li and Ni starts.
- Element X is present on the surface of the primary particles of the positive electrode active material in the relatively low-temperature firing step, and the element X tends to form a concentrated layer on the surface of the primary particles in the subsequent high-temperature firing step.
- the X element can be distributed on the surface of the primary particles inside the secondary particles.
- the element X capable of forming such a concentrated layer is preferably at least one element selected from the group consisting of Ti, Ga, Mg, Zr, and Zn. Of these, it is more preferable to contain at least Ti.
- Ti can be tetravalent, it has a strong bond with O and has a great effect of stabilizing the crystal structure. This is also because the atomic weight is relatively small and the decrease in the theoretical capacity of the positive electrode active material when added is small. When these metal elements X are used, the effect of suppressing the deterioration of the crystal structure from the vicinity of the surface of the positive electrode active material during charging / discharging can be obtained.
- the coefficient e of X in the composition formula (1) is 0 or more and 0.05 or less.
- X When X is added, the crystal structure near the surface of the positive electrode active material becomes more stable as described above, and good charge / discharge cycle characteristics can be obtained.
- X if X is excessive, the proportion of other transition metals such as nickel becomes low, and there is a possibility that the discharge capacity becomes low or the effect of the metal element represented by M becomes low.
- e when e is in the above numerical range, a lithium transition metal composite oxide exhibiting high discharge capacity and good charge / discharge cycle characteristics can be obtained.
- the coefficient e of X is preferably 0.01 or more and 0.03 or less.
- the ratio of Ni on the surface of the primary particles is low, and the change in crystal structure near the surface of the primary particles is reduced. Therefore, a layered structure with fewer defects is formed, and high discharge capacity and good charge / discharge cycle characteristics can be obtained.
- ⁇ in the composition formula (1) is more than ⁇ 0.2 and less than 0.2.
- ⁇ represents the excess or deficiency of oxygen with respect to Li (Ni, Co, M, X) O 2 in the stoichiometric ratio.
- ⁇ is in the above numerical range, there are few defects in the crystal structure, and a high discharge capacity, good rate characteristics, and charge / discharge cycle characteristics can be obtained by an appropriate crystal structure.
- the value of ⁇ can be measured by the Inert gas melting-infrared absorption method.
- the average particle size of the primary particles of the positive electrode active material is preferably 0.05 ⁇ m or more and 2 ⁇ m or less. By setting the average particle size of the primary particles of the positive electrode active material to 2 ⁇ m or less, it is possible to secure a reaction field in which lithium ions of the positive electrode active material are inserted and desorbed, and high discharge capacity and good charge / discharge cycle characteristics can be obtained. It is more preferably 1.5 ⁇ m or less, still more preferably 1.0 ⁇ m or less.
- the average particle size of the secondary particles of the positive electrode active material is preferably, for example, 3 ⁇ m or more and 50 ⁇ m or less.
- the secondary particles (granular material) of the positive electrode active material can be obtained by granulating the primary particles produced by the method for producing the positive electrode active material described later by dry granulation or wet granulation.
- a granulator such as a spray dryer or a rolling fluidized bed device can be used.
- the lithium transition metal composite oxide represented by the composition formula (1) has a BET specific surface area of preferably 0.2 m 2 / g or more, more preferably 0.4 m 2 / g or more, and further preferably 0.6 m 2 / G or more.
- the BET specific surface area is preferably 1.5 m 2 / g or less, more preferably 1.2 m 2 / g or less.
- the BET specific surface area is 0.2 m 2 / g or more, a positive electrode having a sufficiently high molding density and filling rate of the positive electrode active material can be obtained. Further, when the BET specific surface area is 1.5 m 2 / g or less, fracture, deformation, falling off of particles, etc.
- the positive electrode active material of the embodiment of the present invention contains a residual alkaline component.
- the residual alkaline component contains lithium and is not a compound capable of reversibly inserting and removing Li, but contains at least lithium hydroxide and lithium carbonate.
- the amount of residual lithium hydroxide (L1) was 0.8% by mass or less with respect to the positive electrode active material, and the positive electrode active material was compressed at a pressure of 160 MPa ( ⁇ 16,327 N / cm 2). Later, the ratio of the amount of residual lithium hydroxide (L2) to L1 (L2 / L1) is 1.10 or less.
- the residual alkaline component can be confirmed by neutralization titration.
- the amount of residual lithium hydroxide and the amount of residual lithium carbonate can be calculated from the amount of hydrochloric acid dropped.
- the amount of residual lithium hydroxide is preferably 0.8% by mass or less, preferably 0.77% by mass or less, and more preferably 0.6% by mass or less with respect to the positive electrode active material.
- the amount of residual lithium hydroxide measured by neutralization titration is limited to the surface of secondary particles of the positive electrode active material that comes into contact with water and the surface of voids in the secondary particles into which water can penetrate.
- the ratio of compressed L2 to the amount of residual lithium hydroxide L1, L2 / L1, is preferably 1.10 or less.
- L2 / L1 is 1.10 or less, it is possible to maintain a state in which the amount of residual lithium hydroxide is sufficiently small even when a part of the secondary particles is disintegrated, and the gelation of the positive electrode mixture slurry is suppressed. be able to.
- the following aspects can be used as the pressure for compression.
- the viscosity of positive electrode mixture slurry In order to properly apply and form the positive electrode mixture slurry containing the conductive material, binder, solvent and positive electrode active material on the surface of the positive electrode current collector (for example, Al foil), gelation of the positive electrode mixture slurry is suppressed. More specifically, it is required that the viscosity of the positive electrode mixture slurry is stable. That is, it is preferable that the slurry viscosity ⁇ 0 immediately after producing the positive electrode mixture slurry and the slurry viscosity ⁇ 5 measured after standing and storing for 5 days from the production date are equal, and the ratio of slurry viscosity ( ⁇ 5 / ⁇ 0) is. If it is 0.80 or more and 1.2 or less, it can be applied properly.
- the positive electrode active material in the positive electrode mixture slurry is shared in the adjustment process of the mixture coating process, and a part of the secondary particles is destroyed. Therefore, in order to simulate the state of the positive electrode active material in the positive electrode mixture slurry, the positive electrode active material was compressed to destroy a part of the secondary particles. Specifically, after 1 g of positive electrode powder is placed in a die having an area of 0.49 cm 2 , a load of 8 kN, that is, a pressure of 16, per unit area, is used using an autograph device "AGS-1kNX" (manufactured by Shimadzu Corporation). The positive electrode active material was recovered by compressing at 327 N / cm 2 (160 MPa in the SI unit system). Although the compressive force is calculated to be 16,327 N / cm 2 , it is set to 16.0 kN / cm 2 for convenience, and is further converted into a pressure notation of 160 MPa.
- the positive electrode active material of the embodiment of the present invention has a half-value width of E g vibration of 68 cm -1 or less and a half-value width of A 1 g vibration of 50 cm -1 or less. preferable.
- the A 1g vibration is derived from the expansion and contraction vibration of Ni—O and has a peak at a wave number of about 545 to 555 cm -1. If E g FWHM of vibration 68cm -1 or less, can be crystalline of the positive electrode active material near the surface is sufficiently high to obtain a high discharge capacity and excellent charge-discharge cycle characteristics. Further, when the half width of A 1 g vibration is 50 cm -1 or less, the crystallinity is sufficiently high, and a high discharge capacity and good charge / discharge cycle characteristics can be obtained.
- the average composition of the particles of the positive electrode active material can be confirmed by high frequency inductively coupled plasma (ICP), atomic absorption spectroscopy (AAS), or the like.
- the average particle size of the primary particles of the positive electrode active material is the cross-sectional line length when a straight line is drawn in the predetermined direction of the cross-sectional observation image of the secondary particles using a scanning electron microscope (SEM).
- SEM scanning electron microscope
- the straight line in the predetermined direction is a straight line until the connection of the primary particles is interrupted in consideration of the case where the cross section of the secondary particles has voids or the like, and is described as a transversal line.
- the average particle size of the particles in the raw material slurry and the secondary particles of the positive electrode active material can be measured by, for example, a laser diffraction type particle size distribution measuring device or the like.
- the BET specific surface area can be calculated by the gas adsorption method using an automatic specific surface area measuring device.
- the residual alkaline component of the positive electrode active material can be calculated by neutralization titration.
- the positive electrode active material can be compressed by a press machine, an autograph, or the like as described above.
- the positive electrode active material according to the present embodiment includes lithium, nickel, cobalt, etc. under appropriate firing conditions under a raw material ratio such that the lithium transition metal composite oxide has a chemical composition represented by the composition formula (1). It can be produced by surely proceeding with the synthesis reaction with.
- the solid phase method described below is used as a method for producing the positive electrode active material according to the embodiment of the present invention.
- FIG. 1 is a flow chart of a method for producing a positive electrode active material for a lithium ion secondary battery according to an embodiment of the present invention.
- the method for producing a positive electrode active material for a lithium ion secondary battery according to the present embodiment includes a mixing step S10, a granulation step S20, and a firing step S30 in this order.
- the granulation process includes granulation drying by a spray dryer and chemical synthesis by a coprecipitation method.
- steps other than these steps may be added.
- the mixing step S10 and the granulation step S20 the compound containing a metal other than Li is treated, then the Li compound is added, mixed in the second mixing step S11, and then fired in the firing step S30.
- the manufacturing method is also possible.
- the compounds containing the metal elements of Li, Ni, Co, M, and X in the composition formula (1) are mixed.
- a powdery mixture in which the raw materials are uniformly mixed can be obtained.
- a general precision crusher such as a ball mill, a jet mill, a rod mill, or a sand mill can be used.
- the raw material may be pulverized by dry pulverization or wet pulverization.
- a solvent such as water may be added to form a slurry composed of a raw material and a solvent, or a solvent such as water may be added to the raw material in advance to form a slurry and then wet pulverization may be performed.
- a medium such as water.
- a solid phase is used, and the raw materials are crushed at the same time as other raw materials in the step of mixing the raw materials, and the average particle size is 0.3 ⁇ m or less. It is important to mix in the form of a uniform and fine powder.
- lithium-containing compound examples include lithium carbonate, lithium acetate, lithium nitrate, lithium hydroxide, lithium chloride, lithium sulfate and the like.
- Lithium carbonate has a supply stability as compared with other compounds containing lithium. It is excellent and inexpensive, so it can be easily obtained. Further, since lithium carbonate is weakly alkaline, there is little damage to the manufacturing equipment, and it is excellent in industrial usability and practicality.
- Examples of the compound containing a metal element other than Li include a compound containing nickel, a compound containing cobalt, a compound containing a metal element represented by M, and a metal represented by X, depending on the composition of the lithium transition metal composite oxide. Mix the compounds containing the elements.
- Compounds containing metal elements other than Li include compounds composed of C, H, O, and N such as carbonates, hydroxides, oxyhydroxides, sulfates, acetates, citrates, and oxides. It is preferably used. Carbonates, hydroxides, or oxides are particularly preferable from the viewpoint of ease of pulverization and the amount of gas released by thermal decomposition.
- the firing precursor used in the firing step S30 has a chemical composition represented by the composition formula (1).
- the atomic concentration ratio (molar ratio) of the atomic concentration (molar number) of lithium contained in the calcined precursor and the total atomic concentration (molar number) of metal elements other than lithium contained in the calcined precursor. is preferably adjusted to 0.96 or more and 1.04 or less.
- the atomic concentration ratio (molar ratio) of lithium and the total of the metal elements other than lithium in the second mixing step S11. ) Is adjusted.
- the mixing step of mixing the compounds containing the metal elements of Li, Ni, Co, M, and X in the composition formula (1) is the mixing step S10 of FIG. 1A and the second mixing step S11 shown in FIG. 1B. Including the case of.
- lithium transition metal composite oxide in which lattice distortion or crystal structure change due to insertion or desorption of lithium ions is reduced, it is necessary to sufficiently suppress cation mixing in which divalent nickel is likely to occur. From the viewpoint of sufficiently suppressing cation mixing during firing, it is necessary to surely proceed with the synthesis reaction of lithium and nickel, etc., so lithium and nickel, etc. are approximately 1 according to the stoichiometric ratio. It is more desirable to react at a ratio of 1.
- the atomic concentration ratio (molar ratio) of the atomic concentration (molar number) of lithium contained in the firing precursor and the total atomic concentration (molar number) of metal elements other than lithium is more preferable. Is 1.00 or more and 1.04 or less.
- lithium contained in the firing precursor may react with the firing container or volatilize. Considering that a part of lithium is lost due to the reaction between the container used for firing and lithium and the evaporation of lithium during firing, it is not prevented that excessive lithium is added at the time of preparation.
- lithium transition metal composite oxide in which lattice distortion or crystal structure change due to insertion or desorption of lithium ions is reduced, after the mixing step S10 and before the firing step S30, other than lithium. It is preferable not to mix metal elements such as unavoidable impurities derived from the manufacturing process, other components that coat the particles of the lithium transition metal composite oxide, and other components that are mixed with the particles of the lithium transition metal composite oxide.
- the mixture obtained in the mixing step S10 is granulated to obtain secondary particles (granular material) in which the particles are agglomerated with each other.
- the granulation of the mixture may be carried out by using either dry granulation or wet granulation.
- an appropriate granulation method such as a rolling granulation method, a fluidized bed granulation method, a compression granulation method, or a spray granulation method can be used.
- chemical particle synthesis such as the coprecipitation method may be carried out.
- a spray granulation method is particularly preferable.
- various methods such as a two-fluid nozzle type, a four-fluid nozzle type, and a disk type can be used.
- the spray granulation method a mixture (raw material slurry) precisely mixed and pulverized by wet pulverization can be granulated while drying.
- the particle size of secondary particles can be precisely controlled within a predetermined range by adjusting the concentration of raw material slurry, spray pressure, disk rotation speed, etc., and granulation is close to a true sphere and has a uniform chemical composition. You can get the body efficiently.
- the granulation step S20 it is preferable to granulate the mixture obtained in the mixing step S10 so that the average particle size (D 50 ) is 3 ⁇ m or more and 50 ⁇ m or less.
- the firing step S30 the granulated material granulated in the granulation step S20 is heat-treated to fire the lithium transition metal composite oxide represented by the composition formula (1).
- the firing step S30 may be a step of simply firing the lithium transition metal composite oxide to obtain a positive electrode active material, but it is preferably performed by a plurality of stages of heat treatment in which the heat treatment temperatures are controlled in different ranges. As shown in FIG. 1, the firing step S30 is at least the first heat treatment step from the viewpoint of obtaining a lithium transition metal composite oxide having high crystal purity, high discharge capacity, good rate characteristics and charge / discharge cycle characteristics. It is preferable to have a multi-stage heat treatment step having S31, a second heat treatment step S32, and an annealing treatment step S33, each of which satisfies a predetermined condition.
- first heat treatment step S31 the heat treatment temperature is controlled to 600 ° C. or higher and lower than 750 ° C., and the granulated material obtained in the granulation step S20 is heat-treated to obtain a first precursor.
- the main purpose of the first heat treatment step S31 is to remove carbon dioxide components and hydroxyl components by reacting a lithium compound with a nickel compound or the like, and to generate crystals of a lithium transition metal composite oxide.
- Nickel in the calcination precursor is sufficiently oxidized to suppress cation mixing in which nickel is mixed in lithium sites, and to suppress the formation of cubic domains by nickel.
- the metal element represented by M is sufficiently oxidized to make the composition of the layer composed of MeO 2 uniform.
- the time of the first heat treatment step S31 can be 2 hours or more and 50 hours or less.
- the lithium compound is lithium carbonate
- carbon dioxide gas (CO 2 gas) generated as a reaction by-product may hinder the progress of the firing reaction.
- CO 2 gas carbon dioxide gas
- a multi-stage heat treatment capable of gradually discharging CO 2 gas is preferable.
- the unreacted lithium carbonate remaining in the first precursor is preferably reduced to 0.3% by mass or more and 3% by mass or less based on the total mass of the charged granules. , 0.5% by mass or more and 2% by mass or less is more preferable. If the residual amount of lithium carbonate remaining in the first precursor is too large, the lithium carbonate may melt in the second heat treatment step S32 to form a liquid phase.
- the heat treatment temperature when the heat treatment temperature is 600 ° C. or higher, crystals are formed by the reaction between lithium carbonate and a nickel compound or the like, so that it is possible to avoid leaving a large amount of unreacted lithium carbonate. .. Therefore, it becomes difficult for lithium carbonate to form a liquid phase in the subsequent heat treatment, coarsening of crystal grains is suppressed, good output characteristics and the like can be obtained, oxygen is easily distributed to the first precursor, and cation mixing is performed. Is more likely to be suppressed. Further, if the heat treatment temperature is less than 750 ° C., the grain growth does not proceed excessively in the second heat treatment step S31, and manganese and the like are sufficiently oxidized to form a layer composed of MeO 2. The uniformity can be increased.
- the heat treatment temperature in the first heat treatment step S31 is preferably 620 ° C. or higher, more preferably 650 ° C. or higher, and even more preferably 680 ° C. or higher.
- the heat treatment temperature in the first heat treatment step S31 is preferably less than 750 ° C.
- the heat treatment temperature is 750 ° C. or higher, unreacted lithium carbonate forms a liquid phase and the crystal grains become coarse.
- the heat treatment time in the first heat treatment step S31 means that the heat treatment time is maintained at a predetermined temperature, and is more preferably 4 hours or more. Further, the heat treatment time is more preferably 15 hours or less. When the heat treatment time is within this range, the reaction of lithium carbonate proceeds sufficiently, so that the carbonic acid component can be reliably removed. In addition, the time required for heat treatment is shortened, and the productivity of the lithium transition metal composite oxide is improved.
- the first heat treatment step S31 is preferably performed in an oxidizing atmosphere.
- the oxygen concentration in the atmosphere is preferably 50% or more, more preferably 60% or more, and even more preferably 80% or more.
- the carbon dioxide (CO 2 ) concentration in the atmosphere is preferably 5% or less, and more preferably 2% or less.
- the first heat treatment step S31 is preferably performed under an air flow of an oxidizing gas. When the heat treatment is performed under an air flow of an oxidizing gas, nickel can be reliably oxidized and carbon dioxide released into the atmosphere can be reliably eliminated.
- the heat treatment temperature is maintained at 750 ° C. or higher and 900 ° C. or lower, and the first precursor obtained in the first heat treatment step S31 is heat-treated to obtain a second precursor.
- the main purpose of the second heat treatment step S32 is to grow the crystal grains of the lithium transition metal composite oxide having a layered structure to an appropriate particle size and specific surface area.
- the time of the second heat treatment step S32 means that the time is maintained at a predetermined temperature like the heat treatment time of the first heat treatment step S31, and can be 0.5 hours or more and 15 hours or less.
- the heat treatment temperature when the heat treatment temperature is 750 ° C. or higher, nickel is sufficiently oxidized to suppress cation mixing, and the crystal grains of the lithium transition metal composite oxide grow to an appropriate particle size and specific surface area. Can be made to. Further, since a main phase in which lattice distortion or crystal structure change due to insertion or desorption of lithium ions is reduced is formed, high discharge capacity and good charge / discharge cycle characteristics can be obtained. Further, when the heat treatment temperature is 900 ° C. or lower, lithium is less likely to volatilize, the crystal purity is high, and a lithium transition metal composite oxide having good discharge capacity, charge / discharge cycle characteristics, etc. can be obtained.
- the heat treatment temperature in the second heat treatment step S32 is preferably 760 ° C. or higher, more preferably 780 ° C. or higher, and even more preferably 800 ° C. or higher.
- the heat treatment temperature in the second heat treatment step S32 is preferably 880 ° C. or lower, more preferably 860 ° C. or lower.
- the lower the heat treatment temperature the more difficult it is for lithium to volatilize. Therefore, the decomposition of the lithium transition metal composite oxide is surely prevented, and the lithium transition metal composite oxide having good discharge capacity, charge / discharge cycle characteristics, etc. Can be obtained.
- the heat treatment time (holding time) in the second heat treatment step S32 is preferably 0.5 hours or more.
- the heat treatment time is preferably 15 hours or less.
- nickel and the like can be sufficiently oxidized to obtain a lithium transition metal composite oxide in which lattice distortion or crystal structure change due to insertion or desorption of lithium ions is reduced.
- the productivity of the lithium transition metal composite oxide can be improved.
- the second heat treatment step S32 is preferably performed in an oxidizing atmosphere.
- the oxygen concentration in the atmosphere is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.
- the carbon dioxide concentration in the atmosphere is preferably 2% or less, more preferably 0.5% or less.
- the second heat treatment step S32 is preferably performed under an air flow of an oxidizing gas. When the heat treatment is performed under an air flow of an oxidizing gas, nickel and the like can be reliably oxidized, and carbon dioxide released into the atmosphere can be reliably eliminated.
- (Annealing process) At least two or more heat treatment steps of a step of controlling the heat treatment temperature of 600 ° C. or higher and lower than 750 ° C. (first heat treatment step S31) and a step of controlling the heat treatment temperature of 750 ° C. or higher and 900 ° C. or lower (second heat treatment step S32). Later, in the cooling process from the maximum temperature (for example, 840 ° C.), the annealing treatment step S33 for obtaining a lithium transition metal composite oxide is carried out by holding the mixture in a temperature range of 700 ° C. or higher and 800 ° C. or lower for 1.5 hours or longer.
- the residual alkali component remaining inside the secondary particles of the lithium transition metal composite oxide having a layered structure is incorporated into the lithium transition metal composite oxide, and the residual alkali component is small.
- the main purpose is to obtain a positive electrode active material with high crystallinity.
- first heat treatment step S31 layered compound formation can be promoted without advancing the grain growth of the primary particles.
- the crystallinity of the layered compound can be sufficiently improved along with the grain growth of the primary particles.
- An annealing treatment step S33 that holds the film for 5 hours or longer is provided.
- the annealing temperature is within this range, the residual lithium that could not be crystallized in the second heat treatment step is layered from the surface of the secondary particles of the positive electrode active material and the surface of the primary particles inside the secondary particles, resulting in crystals.
- a lithium transition metal composite oxide having high properties can be obtained.
- the above annealing treatment forms a main phase in which the lattice distortion or crystal structure change due to the insertion and desorption of lithium ions is reduced while suppressing the residual alkaline component in the secondary particles of the positive electrode active material. It is possible to obtain excellent gelation resistance of the positive electrode mixture slurry, high discharge capacity, and good charge / discharge cycle characteristics.
- the residual alkaline component tends to remain inside the secondary particles of the positive electrode active material, and the residual alkaline component is calculated by neutralization titration after compressing the positive electrode active material. The amount of residual lithium hydroxide increases.
- the temperature lowering rate when the temperature is lowered from the maximum temperature is adjusted to set the temperature range of 700 ° C. or higher and 800 ° C. or lower. . It is better to cool it for 5 hours or more.
- the temperature may be maintained at a constant temperature within the range of 700 ° C. or higher and 800 ° C. or lower during the cooling process for a predetermined time, or the temperature may be lowered to less than 700 ° C. and then heated again to the temperature range of 700 ° C. or higher and 800 ° C. or lower.
- the upper limit annealing temperature is preferably 790 ° C. or lower, and more preferably 780 ° C. or lower.
- the lower limit annealing temperature is preferably 720 ° C. or higher, and more preferably 740 ° C. or higher.
- the heat treatment time in the annealing step S33 is preferably 1.5 hours or more.
- the heat treatment time is 1.5 hours or more, the lithium carbonate remaining in the secondary particles of the positive electrode active material is sufficiently reacted with the positive electrode active material to obtain a highly crystalline lithium transition metal composite oxide. be able to.
- the heat treatment time does not change even if it is carried out for more than 10 hours, preferably 2 hours or more and 8 hours or less, and more preferably 3 hours or more and 6 hours or less. When the heat treatment time is within this range, it is possible to reduce the residual alkaline component and improve the productivity of the lithium transition metal composite oxide at the same time.
- the annealing treatment step S33 is preferably performed in an oxidizing atmosphere.
- the oxygen concentration in the atmosphere is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.
- the carbon dioxide concentration in the atmosphere is preferably 0.5% or less, more preferably 0.1% or less.
- the annealing treatment step S33 is preferably performed under an air flow of an oxidizing gas. When the heat treatment is performed under an air flow of an oxidizing gas, the carbon dioxide released into the atmosphere due to the reaction of lithium carbonate can be reliably eliminated.
- the maximum CO 2 concentration in the atmosphere of the first heat treatment step S31 is higher than the maximum CO 2 concentration of the second heat treatment step S32, and the maximum CO 2 concentration of the second heat treatment step S32 is the highest of the annealing process. Higher than CO 2 concentration.
- One of the purposes of the first heat treatment step S31 is to decarboxylate the gas, and the CO 2 generated by the heat treatment causes the maximum CO 2 concentration to be higher than that of the second heat treatment step S32 and the annealing step S33.
- the second heat treatment step S32 it is preferably less environmental maximum CO 2 concentration for improving the crystallinity of the positive electrode active material in the annealing step S33, it is preferably the maximum CO 2 concentration is lower than the first heat treatment step S31.
- the annealing step S33 an environment in which the maximum CO 2 concentration is lower than that in the first heat treatment step S31 and the second heat treatment step S32 is preferable in order to reduce the residual alkaline component in the secondary particles of the positive electrode active material.
- an appropriate heat treatment apparatus such as a rotary furnace such as a rotary kiln, a continuous furnace such as a roller herculen, a tunnel furnace, a pusher furnace, or a batch furnace can be used.
- the first heat treatment step S31, the second heat treatment step S32, and the annealing treatment step S33 may be performed using the same heat treatment apparatus, or may be performed using different heat treatment apparatus. Further, each heat treatment step may be performed intermittently by changing the atmosphere, or may be performed continuously when the heat treatment is performed while exhausting the gas in the atmosphere.
- a positive electrode active material composed of the lithium transition metal composite oxide represented by the composition formula (1) can be produced.
- the amount of residual lithium hydroxide and the specific surface area are mainly determined by the method for producing a precursor before heat treatment, the composition ratio of a metal element such as nickel, and the residual unreacted lithium carbonate remaining in the first precursor.
- the amount can be controlled by adjusting the conditions of the temporary firing, the main firing, and the annealing treatment in the firing step S30, for example, the heat treatment temperature and the heat treatment time of the first heat treatment step S31, the second heat treatment step S32, and the annealing step S33.
- the positive electrode mixture slurry is prepared.
- the synthesized lithium transition metal composite oxide has a crushing step of crushing the lithium transition metal composite oxide and a predetermined particle size of the lithium transition metal composite oxide for the purpose of controlling the particle size of the secondary particles. It may have a classification process or the like for classifying into.
- Lithium-ion secondary battery using the positive electrode active material containing the lithium transition metal composite oxide (positive electrode active material for a lithium ion secondary battery) as the positive electrode will be described.
- FIG. 2 is a partial cross-sectional view schematically showing an example of a lithium ion secondary battery.
- the lithium ion secondary battery 100 includes a bottomed cylindrical battery can 101 containing a non-aqueous electrolyte solution, a wound electrode group 110 housed inside the battery can 101, and a battery can. It includes a disk-shaped battery lid 102 that seals the opening at the top of 101.
- the battery can 101 and the battery lid 102 are formed of, for example, a metal material such as stainless steel or aluminum.
- the positive electrode 111 includes a positive electrode current collector 111a and a positive electrode mixture layer 111b formed on the surface of the positive electrode current collector 111a.
- the negative electrode 112 includes a negative electrode current collector 112a and a negative electrode mixture layer 112b formed on the surface of the negative electrode current collector 112a.
- the positive electrode current collector 111a is formed of, for example, a metal foil such as aluminum or an aluminum alloy, an expanded metal, a punching metal, or the like.
- the metal foil can have a thickness of, for example, about 15 ⁇ m or more and 25 ⁇ m or less.
- the positive electrode mixture layer 111b contains a positive electrode active material containing the above-mentioned lithium transition metal composite oxide.
- the positive electrode mixture layer 111b is formed of, for example, a positive electrode mixture in which a positive electrode active material is mixed with a conductive material, a binder, or the like.
- the negative electrode current collector 112a is formed of a metal foil such as copper, copper alloy, nickel, nickel alloy, expanded metal, punching metal, or the like.
- the metal foil can have a thickness of, for example, about 7 ⁇ m or more and 10 ⁇ m or less.
- the negative electrode mixture layer 112b contains a negative electrode active material for a lithium ion secondary battery.
- the negative electrode mixture layer 112b is formed of, for example, a negative electrode mixture in which a negative electrode active material is mixed with a conductive material, a binder, or the like.
- the negative electrode active material an appropriate type used for a general lithium ion secondary battery can be used.
- Specific examples of the negative electrode active material include an easily graphitized material obtained from natural graphite, petroleum coke, pitch coke, etc. treated at a high temperature of 2500 ° C. or higher, mesophase carbon, amorphous carbon, and non-crystallized on the surface of graphite.
- Material coated with quality carbon carbon material whose surface crystallity is reduced by mechanically treating the surface of natural graphite or artificial graphite, material in which organic substances such as polymers are coated and adsorbed on the carbon surface, carbon fiber , Lithium metal, alloy of lithium with aluminum, tin, silicon, indium, gallium, magnesium, etc., material supporting metal on the surface of silicon particles or carbon particles, oxides of tin, silicon, lithium, titanium, etc. Be done.
- the metal to be supported include lithium, aluminum, tin, indium, gallium, magnesium, alloys thereof and the like.
- the conductive material an appropriate type used for a general lithium ion secondary battery can be used.
- the conductive material include carbon particles such as graphite, acetylene black, furnace black, thermal black and channel black, and carbon fibers such as pitch type and polyacrylonitrile (PAN) type. These conductive materials may be used alone or in combination of two or more.
- the amount of the conductive material can be, for example, 3% by mass or more and 10% by mass or less with respect to the entire mixture.
- the binder an appropriate type used for a general lithium ion secondary battery can be used.
- the binder include PVDF, polytetrafluoroethylene, polyhexafluoropropylene, styrene-butadiene rubber, polyacrylonitrile, modified polyacrylonitrile, and the like. These binders may be used alone or in combination of two or more. Further, a thickening binder such as carboxymethyl cellulose may be used in combination.
- the amount of the binder can be, for example, 2% by mass or more and 10% by mass or less with respect to the entire mixture.
- the positive electrode 111 and the negative electrode 112 can be manufactured according to a general method for manufacturing electrodes for lithium ion secondary batteries. For example, a mixture preparation step of mixing an active material with a conductive material, a binder, etc. in a solvent to prepare an electrode mixture, and applying the prepared electrode mixture onto a substrate such as a current collector. After that, it can be produced through a mixture coating step of drying to form an electrode mixture layer and a molding step of pressure molding the electrode mixture layer.
- a mixing means for mixing the materials for example, an appropriate mixing device such as a planetary mixer, a dispermixer, or a rotation / revolution mixer can be used.
- the solvent for example, N-methylpyrrolidone, water, N, N-dimethylformamide, N, N-dimethylacetamide, methanol, ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, glycerin, dimethyl sulfoxide, tetrahydrofuran and the like are used. Can be done.
- the viscosity of the electrode mixture (positive electrode mixture slurry) is, for example, in the range of 100 to 500 mPa ⁇ s, proper coating can be performed, and it is important from the viewpoint of stable production that the viscosity does not fluctuate after the slurry is prepared. ..
- the cause of the fluctuation in viscosity is mainly that the alkaline component eluted from the positive electrode active material polymerizes the binder and gels. In determining the positive electrode active material capable of suppressing this gelation, it is appropriate to use the change in slurry viscosity as an index.
- an appropriate coating device such as a bar coater, a doctor blade, or a roll transfer machine can be used.
- an appropriate drying device such as a hot air heating device or a radiant heating device can be used.
- an appropriate pressure device such as a roll press can be used as a means for pressure molding the electrode mixture layer.
- the thickness of the positive electrode mixture layer 111b can be, for example, about 100 ⁇ m or more and 300 ⁇ m or less.
- the negative electrode mixture layer 112b can have a thickness of, for example, about 20 ⁇ m or more and 150 ⁇ m or less.
- the pressure-molded electrode mixture layer can be cut together with the positive electrode current collector, if necessary, to obtain an electrode for a lithium ion secondary battery having a desired shape.
- the wound electrode group 110 is formed by winding a strip-shaped positive electrode 111 and a negative electrode 112 with a separator 113 interposed therebetween.
- the wound electrode group 110 is wound around an axial center formed of, for example, polypropylene, polyphenylene sulfide, or the like, and is housed inside the battery can 101.
- the separator 113 includes a polyolefin resin such as polyethylene, polypropylene, and a polyethylene-polypropylene copolymer, a microporous film such as a polyamide resin and an aramid resin, and heat resistance of alumina particles or the like on the surface of such a microporous film.
- a film or the like coated with a substance can be used.
- the positive electrode current collector 111a is electrically connected to the battery lid 102 via the positive electrode lead piece 103.
- the negative electrode current collector 112a is electrically connected to the bottom of the battery can 101 via the negative electrode lead piece 104.
- An insulating plate 105 for preventing a short circuit is arranged between the wound electrode group 110 and the battery lid 102, and between the wound electrode group 110 and the bottom of the battery can 101.
- the positive electrode lead piece 103 and the negative electrode lead piece 104 are formed of the same material as the positive electrode current collector 111a and the negative electrode current collector 112a, respectively, and are spot-welded and ultrasonically bonded to the positive electrode current collector 111a and the negative electrode current collector 112a, respectively. It is joined by pressure welding or the like.
- a non-aqueous electrolytic solution is injected into the battery can 101.
- the method of injecting the non-aqueous electrolyte solution may be a method of directly injecting the non-aqueous electrolyte solution with the battery lid 102 open, a method of injecting the non-aqueous electrolyte solution from the injection port provided in the battery lid 102 with the battery lid 102 closed, or the like. There may be.
- the battery can 101 is sealed with the battery lid 102 fixed by caulking or the like.
- a sealing material 106 made of an insulating resin material is sandwiched between the battery can 101 and the battery lid 102, and the battery can 101 and the battery lid 102 are electrically insulated from each other.
- the non-aqueous electrolyte solution is composed of an electrolyte and a non-aqueous solvent.
- the electrolyte for example, various lithium salts such as LiPF 6 , LiBF 4 , and LiClO 4 can be used.
- the non-aqueous solvent include chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, cyclic carbonates such as ethylene carbonate, propylene carbonate and vinylene carbonate, and methyl acetate, ethyl methyl carbonate and methyl propyl carbonate.
- Chain carboxylic acid esters cyclic carboxylic acid esters such as ⁇ -butyrolactone and ⁇ -valerolactone, ethers and the like can be used.
- concentration of the electrolyte can be, for example, 0.6 M or more and 1.8 M or less.
- additives are added for the purpose of suppressing oxidative decomposition and reductive decomposition of the electrolytic solution, preventing precipitation of metal elements, improving ionic conductivity, improving flame retardancy, etc.
- the additive include organic phosphorus compounds such as trimethyl phosphate and trimethyl phosphate, organic sulfur compounds such as 1,3-propanesulton and 1,4-butansalton, polyadipic anhydride, and hexahydrophthalic anhydride.
- Phthalic anhydrides such as, trimethyl borate, boron compounds such as lithium bisoxalate borate and the like can be mentioned.
- the battery lid 102 is used as a positive electrode external terminal and the bottom of the battery can 101 is used as a negative electrode external terminal, and electric power supplied from the outside can be stored in the wound electrode group 110. .. Further, the electric power stored in the wound electrode group 110 can be supplied to an external device or the like.
- the lithium ion secondary battery 100 has a cylindrical shape, the shape and battery structure of the lithium ion secondary battery are not particularly limited, and for example, a square shape, a button shape, a laminated sheet shape, or the like is appropriately used. It may have the shape of the above and other battery structures.
- the lithium ion secondary battery according to this embodiment can be used for various purposes.
- Applications include, for example, small power sources such as portable electronic devices and household electric devices, stationary power sources such as power storage devices, non-interruption power supply devices, and power leveling devices, ships, railroad vehicles, hybrid railroad vehicles, and hybrids. Examples include, but are not limited to, drive power sources for automobiles, electric vehicles, and the like.
- the lithium transition metal composite oxide has a high nickel content, exhibits a high discharge capacity, and has good charge / discharge cycle characteristics. Therefore, a small power source or an in-vehicle device that requires high energy density and long life is required. It can be particularly preferably used as an application.
- the chemical composition of the positive electrode active material used in the lithium ion secondary battery is determined by disassembling the battery, collecting the positive electrode active material that constitutes the positive electrode, and performing high-frequency induction-coupled plasma emission spectroscopic analysis, atomic absorption spectroscopy, etc. You can check. Further, since the composition ratio of lithium (1 + a in the composition formula (1)) depends on the charging state, it is based on whether or not the coefficient a of lithium after charging and discharging satisfies ⁇ 0.9 ⁇ a ⁇ 0.04. , The chemical composition of the positive electrode active material can also be determined.
- the positive electrode active material according to the examples of the present invention was synthesized, and the composition, the amount of residual alkali, the discharge capacity, and the charge / discharge cycle characteristics (capacity retention rate) were evaluated.
- the positive electrode active material according to the comparative example in which the chemical composition was changed was synthesized and evaluated in the same manner.
- the present invention will be specifically described with reference to Examples and Comparative Examples, but the technical scope of the present invention is not limited thereto.
- Example 1 The positive electrode active material of Example 1 was produced. Lithium carbonate, nickel hydroxide, cobalt carbonate, and manganese carbonate are prepared as raw materials, and each raw material has a molar ratio of metal elements of Li: Ni: Co: Mn of 1.04: 0.80: 0.15: 0. Weighed to be 0.05, and pure water was added so that the solid content ratio was 50% by mass. Then, a raw material slurry was prepared by wet pulverization (wet mixing) with a pulverizer (mixing step S10). The average particle size D 50 of the raw material slurry was 0.15 ⁇ m.
- the raw material slurry obtained through the mixing step was spray-dried using a nozzle-type spray dryer (manufactured by Okawara Kakoki Co., Ltd., ODL-20 type) at a spray pressure of 0.21 MPa and a spray amount of 260 g / min.
- a granulated body was obtained (granulation step S20).
- the average particle diameter D 50 of the granulated material was 12 [mu] m.
- the granulated material was calcined to obtain a lithium transition metal composite oxide (calcination step S30). Specifically, in the firing step, the granulated body was heat-treated (temporarily fired) at 650 ° C.
- Step S31 The maximum CO 2 concentration in the exhaust gas of the rotary kiln was 8500 ppm.
- the first precursor was heat-treated (mainly fired) at 800 ° C. for 10 hours in an oxygen stream in a tunnel furnace replaced with an oxygen gas atmosphere (second heat treatment step S32).
- the CO 2 concentration in the exhaust gas of the tunnel furnace in the second heat treatment step S32 was 200 ppm at the maximum.
- the temperature is continuously lowered from 800 ° C., adjusted to a temperature lowering rate of 0.5 ° C./min to 700 ° C., and held (annealed) in the temperature range of 800 ° C. to 700 ° C. for 3 hours and 20 minutes to form a lithium transition metal composite.
- An oxide was obtained (annealing step S33).
- the maximum CO 2 concentration in the exhaust gas of the tunnel furnace in the annealing step S33 was 40 ppm.
- FIG. 3A shows an annealing process diagram showing a temperature drop temperature zone on the vertical axis and a temperature drop time on the horizontal axis. Then, the calcined powder obtained by calcining was classified using a sieve having a mesh size of 53 ⁇ m, and the powder under the sieve was used as the positive electrode active material of the sample.
- the chemical composition of Li: Ni: Co: Mn of the obtained positive electrode active material was measured by high-frequency inductively coupled plasma emission spectroscopy and confirmed to be 1.03: 0.80: 0.15: 0.05. did. Further, ⁇ of the positive electrode active material obtained in Example 1 was also measured by the inert gas melting-infrared absorption method, and it was confirmed that ⁇ 0.2 ⁇ ⁇ 0.2. It was confirmed that ⁇ 0.2 ⁇ ⁇ 0.2 also in Example 2 and subsequent examples.
- the main firing temperature was 820 ° C.
- the annealing time was in the temperature range of 700 ° C. or higher and 800 ° C. or lower, and was 3 hours and 20 minutes.
- a positive electrode active material was obtained in the same manner as in Example 1 except for the above.
- a positive electrode active material was obtained in the same manner as in Example 1 except for the above. The maximum concentration of CO 2 calcination 11000Ppm, maximum CO 2 concentration of the firing 160 ppm, the highest concentration of CO 2 annealing was 50 ppm.
- the temporary firing temperature was 700 ° C.
- the main firing temperature was 840 ° C.
- a positive electrode active material was obtained in the same manner as in Example 1 except for the above. Therefore, the total annealing time in the temperature range of 700 ° C. or higher and 800 ° C. or lower was 3 hours and 20 minutes.
- the temporary firing temperature was 700 ° C., and the main firing temperature was 840 ° C.
- a positive electrode active material was obtained in the same manner as in Example 1 except for the above. Therefore, the annealing time was 3 hours and 20 minutes.
- the temporary firing temperature was 700 ° C., and the main firing temperature was 820 ° C.
- a positive electrode active material was obtained in the same manner as in Example 1 except for the above. Therefore, the annealing time was 3 hours and 20 minutes.
- Comparative Examples 1 to 3 In Comparative Example 1, the annealing treatment was almost eliminated. After the main firing, the temperature was lowered to room temperature at 5 ° C./min. A positive electrode active material was obtained in the same manner as in Example 1 except for the above. Therefore, the time for which the temperature was lowered from the maximum temperature of the main firing and kept in the temperature range of 700 ° C. or higher and 800 ° C. or lower was 20 minutes. The maximum concentration of CO 2 calcination 8600Ppm, maximum CO 2 concentration of the firing 210 ppm, the highest concentration of CO 2 annealing was 20 ppm.
- a positive electrode active material was obtained in the same manner as in Example 1 except for the above. The maximum concentration of CO 2 calcination 11000Ppm, maximum CO 2 concentration of the firing 160 ppm, the highest concentration of CO 2 annealing was 20 ppm.
- FIG. 4 shows the particle size distribution of the positive electrode active material before and after compression in Example 1. Before compression, the average particle size was 13.5 ⁇ m, but after compression, the number of particles smaller than 5 ⁇ m, which was not seen before compression, increased to 8.5 ⁇ m.
- the residual alkaline component of the positive electrode active material was measured by the following procedure using an automatic titrator "COM-1700A" (manufactured by Hiranuma Sangyo).
- 0.5 g of positive electrode powder was placed in 30 ml of pure water, the inside of the container was replaced with Ar, and the mixture was stirred for 1 hour to extract the Li component, and an extract was obtained by suction filtration.
- 25 ml of the obtained extract was diluted with pure water to about 40 ml, titrated with 0.02 M hydrochloric acid, and the amounts of lithium carbonate component and lithium hydroxide component in the extract were analyzed.
- the peak of the titration curve has two stages, and the titration amount between the equivalence point of the first stage and the equivalence point of the second stage is the lithium carbonate amount, and the lithium carbonate amount is subtracted from the titration amount up to the equivalence point of the first stage.
- the amount was taken as the amount of lithium hydroxide.
- Table 1-2 The results are shown in Table 1-2.
- the positive electrode active material, the carbon-based conductive material, and the binder (PVdF) previously dissolved in N-methyl-2-pyrrolidone (NMP) are weighed so as to have a mass ratio of 96: 2: 2 and kneaded.
- a positive electrode mixture slurry was prepared using the machine "Hibismix 2P-03" (manufactured by Primix Corporation).
- the viscosity of the obtained positive electrode mixture slurry was measured at a rotation speed of 0.5 rpm using a B-type viscometer "TVB10" (manufactured by Toki Sangyo Co., Ltd.).
- the positive electrode mixture slurry was placed in a plastic container and stored in an air atmosphere at 25 ° C. and 50% RH, and the viscosity was measured every day. In this way, the viscosity of the positive electrode mixture slurry having a positive electrode active material ratio of 96% or more was measured.
- the ratio ( ⁇ d / ⁇ 0) of the positive electrode mixture slurry viscosity ⁇ 0 on the slurry preparation day and the positive electrode mixture slurry viscosity ⁇ d stored statically for d days after the slurry preparation day is maintained at 0.80 or more and 1.2 or less. It was defined as gelation resistance (day). The results are shown in Table 1-2.
- the positive electrode mixture slurry viscosity ⁇ 0 on the day of slurry preparation and the positive electrode mixture stored statically for 5 days after the day of slurry preparation.
- the ratio of slurry viscosity ⁇ 5 ( ⁇ 5 / ⁇ 0) is also shown in Table 1-2.
- a lithium ion secondary battery was produced using the synthesized positive electrode active material as the material for the positive electrode. After that, the discharge capacity and capacity retention rate of the lithium ion secondary battery were determined. First, the uniformly mixed positive electrode mixture slurry was applied onto a positive electrode current collector of an aluminum foil having a thickness of 20 ⁇ m so that the coating amount was 10 mg / cm 2 . Next, the positive electrode mixture slurry applied to the positive electrode current collector was heat-treated at 120 ° C. to distill off the solvent to form a positive electrode mixture layer. Then, the positive electrode mixture layer was pressure-molded by hot pressing and punched into a circular shape having a diameter of 15 mm to obtain a positive electrode.
- a lithium ion secondary battery was produced using the produced positive electrode, negative electrode, and separator.
- the negative electrode metallic lithium punched into a circular shape having a diameter of 16 mm was used.
- the separator a polypropylene porous separator having a thickness of 30 ⁇ m was used.
- the positive electrode and the negative electrode were opposed to each other in the non-aqueous electrolytic solution via the separator, and the lithium ion secondary battery was assembled.
- the non-aqueous electrolytic solution a solution in which LiPF 6 was dissolved so as to be 1.0 mol / L in a solvent in which ethylene carbonate and dimethyl carbonate were mixed so as to have a volume ratio of 3: 7 was used.
- the prepared lithium ion secondary battery was charged in an environment of 25 ° C. at a constant current / constant voltage of 40 A / kg and an upper limit potential of 4.3 V based on the mass of the positive electrode mixture. Then, the discharge capacity (initial capacity) was measured by discharging to the lower limit potential of 2.5 V at a constant current of 40 A / kg based on the mass of the positive electrode mixture. Subsequently, the lithium secondary battery whose initial capacity was measured was charged in an environment of 25 ° C. at a constant current / constant voltage of 100 A / kg and an upper limit potential of 4.3 V based on the mass of the positive electrode mixture.
- the results shown in Table 1 will be considered below.
- the chemical composition represented by the composition formula (1) the residual lithium hydroxide amount L1 before compression is 0.8% by mass or less, and is compressed by an autograph.
- the ratio L2 / L1 of the residual lithium hydroxide amount L2 and L1 after the above is 1.10 or less.
- the positive electrode mixture slurry is maintained for at least 5 days or more until it gels, and in some cases, it can be maintained for 10 days or more. Therefore, it was confirmed that the gel resistance was excellent.
- the discharge capacity showed a high value of more than 190 Ah / kg, and a high capacity retention rate of 90% or more was obtained.
- Comparative Example 1 since there was almost no annealing treatment, the residual lithium hydroxide amount L1 was large, and L2 / L1 was also high. As a result, it took less than a day to gel, which was inconvenient. Further, in Comparative Example 2, the annealing treatment was as short as 1 hour or less, the residual lithium hydroxide amounts L1 and L2 / L1 were both slightly larger than in Examples, and the positive electrode mixture slurry gelled in 3 days. Although there is a tolerance in the manufacturing process, gel resistance is usually required to be 5 days or more, which is an inconvenient result. Further, in Comparative Example 3, although there was no annealing treatment, the residual alkaline component was removed by washing with water.
- the amount of residual lithium hydroxide L1 was very small, and L2 / L1 was larger than that of the examples. It took 30 days for the positive electrode mixture slurry to gel, which was good. However, the capacity retention rate was as low as 79%. It is considered that this is because Li on the surface layer of the positive electrode active material was partially eluted in addition to the residual alkaline component by washing with water. In addition, since a washing step and a subsequent drying step are added, it is considered that the productivity is also inferior.
- FIG. 5 shows the relationship between the amount of residual lithium hydroxide and the number of days of gelation
- FIG. 6 shows the relationship between the amount of residual lithium hydroxide and the capacity retention rate.
- the discharge capacity also shows a characteristic of about 190 Ah / Kg or more. From the above, when the amount of residual lithium hydroxide is 0.8% by mass or less, the progress of gelation of the binder is suppressed, and a positive electrode active material having high crystallinity can be obtained to maintain the capacity. It is considered that the decrease was suppressed. In Comparative Example 3, although the amount of residual lithium hydroxide was 0.8% by mass or less, the capacity retention rate was low because, as described above, the residual lithium hydroxide was washed together with the residual lithium hydroxide near the surface layer of the positive electrode active material. It is probable that lithium extraction occurred, the crystallinity and the structural stability of the crystal decreased, and the capacity retention rate decreased.
- FIG. 7 shows the relationship between L2 / L1 and the number of days of gelation
- FIG. 8 shows the relationship between L2 / L1 and the capacity retention rate.
- L2 / L1 there is a correlation between L2 / L1 and the number of days of gelation and between L2 / L1 and the volume retention rate. That is, when L2 / L1 is 1.10 or less, it can be said that the number of gelling days is 5 days or more and the volume retention rate is 90% or more.
- L2 / L1 is 1.10 or less, even if a part of the secondary particles of the positive electrode active material is cracked in the mixture coating step and the interface inside the secondary particles is newly exposed, residual hydroxide is formed. It is considered that the increase in the amount of lithium and the decrease in crystallinity are small, and the progress of gelation of the binder and the decrease in volume are suppressed.
Abstract
Description
Li1+aNibCocMdXeO2+α ・・・(1)
[但し、組成式(1)において、Mは、Al及びMnから選ばれる少なくとも1種を表し、XはLi、Ni、Co、Al及びMn以外の1種以上の金属元素を表し、a、b、c、d、e及びαは、それぞれ、-0.04≦a≦0.04、0.80≦b≦1.0、0≦c≦0.15、0≦d≦0.20、0≦e≦0.05、b+c+d+e=1、及び、-0.2<α<0.2を満たす数である。]で表されるリチウム遷移金属複合酸化物を含むリチウムイオン二次電池用正極活物質であって、中和滴定で算出される前記正極活物質の残存水酸化リチウム量(L1)が0.8質量%以下であり、かつ前記正極活物質を圧力160MPaで圧縮した後に中和滴定で算出される残存水酸化リチウム量(L2)と前記L1との比L2/L1が1.10以下であることを特徴とするリチウムイオン二次電池用正極活物質である。
Li1+aNibCocMdXeO2+α ・・・(1)
[但し、組成式(1)において、Mは、Al及びMnから選ばれる少なくとも1種を表し、XはLi、Ni、Co、Al及びMn以外の1種以上の金属元素を表し、a、b、c、d、e及びαは、それぞれ、-0.04≦a≦0.04、0.80≦b≦1.0、0≦c≦0.15、0≦d≦0.2、0≦e≦0.05、b+c+d+e=1、及び、-0.2<α<0.2を満たす数である。]で表されるリチウム遷移金属複合酸化物を含むリチウムイオン二次電池用正極活物質の製造方法であって、
前記組成式(1)中のLi、Ni、Co、M、Xの金属元素を含む化合物を混合する混合工程と、前記混合工程を経て得られた原料スラリーから造粒体を得る造粒工程と、前記造粒体を焼成して組成式(1)で表されるリチウム遷移金属複合酸化物を得る焼成工程と、を有し、前記焼成工程は、少なくとも、熱処理温度を600℃以上750℃未満に保持する第1熱処理工程と、熱処理温度を750℃以上900℃以下に保持する第2熱処理工程とを含む、多段熱処理工程であり、その後、最高温度から降温し、700℃以上800℃以下の温度帯に1.5時間以上保持するアニール処理工程を有することを特徴とするリチウムイオン二次電池用正極活物質の製造方法である。
本実施形態に係る正極活物質は、層状構造を呈するα-NaFeO2型の結晶構造を有し、リチウムと遷移金属とを含んで組成されるリチウム遷移金属複合酸化物を含む。この正極活物質は、リチウム遷移金属複合酸化物の一次粒子や一次粒子が複数個凝集して構成された二次粒子を主成分としている。また、リチウム遷移金属複合酸化物は、リチウムイオンの挿入及び脱離が可能な層状構造を主相として有する。
Li1+aNibCocMdXeO2+α ・・・(1)
[但し、組成式(1)において、Mは、Al及びMnから選ばれる少なくとも1種を表し、XはLi、Ni、Co、Al及びMn以外の1種以上の金属元素を表し、a、b、c、d、e及びαは、それぞれ、-0.04≦a≦0.04、0.80≦b≦1.0、0≦c≦0.15、0≦d≦0.20、0≦e≦0.05、b+c+d+e=1、及び、-0.2<α<0.2を満たす数である。]
ここで、組成式(1)で表される化学組成の意義について説明する。
Xの係数eは、0.01以上0.03以下であることが好ましい。eが0.01以上0.03以下であると、一次粒子表面のNiの比率が低くなり、一次粒子の表面近傍の結晶構造変化が低減される。そのため、より欠陥が少ない層状構造が形成されて、高い放電容量、良好な充放電サイクル特性を得ることができる。
正極活物質の一次粒子の平均粒径は、0.05μm以上2μm以下であることが好ましい。正極活物質の一次粒子の平均粒径を2μm以下とすることで、正極活物質のリチウムイオンが挿入脱離する反応場を確保でき、高い放電容量、良好な充放電サイクル特性が得られる。より好ましくは1.5μm以下、更に好ましくは1.0μm以下である。また、正極活物質の二次粒子の平均粒径は、例えば、3μm以上50μm以下であることが好ましい。
本発明の実施形態の正極活物質は、残存アルカリ成分を含む。残存アルカリ成分は、リチウムを含み、可逆的にLiを挿入脱離できる化合物ではなく、少なくとも水酸化リチウムと炭酸リチウムを含む。この残存アルカリ成分のうち、残存水酸化リチウム量(L1)が正極活物質に対して0.8質量%以下であり、かつ正極活物質を圧力160MPa(≒16,327N/cm2)で圧縮した後における残存水酸化リチウム量(L2)とL1の比(L2/L1)が1.10以下としたものである。ここで、残存アルカリ成分は中和滴定で確認することができる。
LiOH + HCl → LiCl + H2O
Li2CO3 + HCl → LiHCO3 + LiCl
LiHCO3 + HCl → LiCl + H2O + CO2
よって、塩酸の滴下量から残存水酸化リチウム量と残存炭酸リチウム量を算出することができる。残存水酸化リチウム量は正極活物質に対して0.8質量%以下、好ましくは0.77質量%以下、より好ましくは0.6質量%以下であることが良い。残存水酸化リチウム量が0.8質量%以下であれば、結着剤として汎用性の高いポリフッ化ビニリデン(PVDF)を用いた場合でも、塩基性化合物に不安定なPVDFの脱フッ酸反応が進行することなく、正極合剤スラリーのゲル化を抑制することができる。
導電材、結着剤、溶媒と正極活物質を含有する正極合剤スラリーを適正に正極集電体(例えばAl箔)の表面に塗布形成するためには、正極合剤スラリーのゲル化が抑制されていること、より具体的には正極合剤スラリーの粘度が安定であることが求められる。すなわち正極合剤スラリーを作製した直後のスラリー粘度η0と、前記作製日から5日間静置保管した後に測定したスラリー粘度η5とが同等であることが好ましく、スラリー粘度の比(η5/η0)が0.80以上1.2以下であれば適正に塗布ができる。
正極合剤スラリー中の正極活物質は、合剤塗工工程の調整過程でシェアがかかって二次粒子の一部が破壊される。そこで、正極合剤スラリー中の正極活物質の状態を模擬するため、正極活物質を圧縮して二次粒子の一部を破壊した。
具体的には、正極粉1gを面積0.49cm2のダイスに入れた後、オートグラフ装置「AGS-1kNX」(島津製作所製)を使用して8kNの荷重、すなわち単位面積当たりの圧力16,327N/cm2(SI単位系では160MPa)で圧縮して正極活物質を回収した。尚、計算上は16,327N/cm2の圧縮力となるが、ここでは便宜上16.0kN/cm2とし、さらに160MPaの圧力表記に換算したものである。
正極活物質表面は残存アルカリ成分が存在したり、製造工程において表面近傍のリチウムが欠損したりするため、正極活物質内部と比較して結晶性が低下しやすい。正極活物質表面近傍の結晶性は、ラマン分光で分析することが可能である。本発明の実施形態の正極活物質は、正極活物質のラマンスペクトル分析において、Eg振動の半値幅が68cm-1以下であり、かつA1g振動の半値幅が50cm-1以下であることが好ましい。Eg振動はNi-Oの変角振動に由来し、波数472~482cm-1にピークを有する。A1g振動はNi-Oの伸縮振動に由来し、波数約545~555cm-1にピークを有する。Eg振動の半値幅が68cm-1以下であれば、正極活物質表面近傍の結晶性が十分高く、高い放電容量や良好な充放電サイクル特性を得ることができる。また、A1g振動の半値幅が50cm-1以下であれば、結晶性が十分高く、高い放電容量や良好な充放電サイクル特性を得ることができる。
正極活物質の粒子の平均組成は、高周波誘導結合プラズマ(Inductively Coupled Plasma;ICP)、原子吸光分析(Atomic Absorption Spectrometry;AAS)等によって確認することができる。正極活物質の一次粒子の平均粒径は、走査電子顕微鏡(Scanning Electron Microscope;SEM)を用い、二次粒子の断面観察像の所定方向に直線を引いたときの横断線長を、横断直線中に含まれる一次粒子の数で除して一次粒子の粒径を算出し、二次粒子10個を用いた平均値を一次粒子の平均粒径とした。なお、前記所定方向の直線とは、二次粒子の断面に空隙などがある場合を考慮して、一次粒子の連なりが途切れるまでの直線とし横断線と記した。原料スラリー中の粒子や正極活物質の二次粒子の平均粒径は、例えば、レーザー回折式粒度分布測定器等によって測定できる。BET比表面積は、自動比表面積測定装置を用いてガス吸着法で算出することができる。正極活物質の残存アルカリ成分は、中和滴定で算出することができる。正極活物質の圧縮は、上述のようにプレス機やオートグラフ等によって実施することができる。
本実施形態に係る正極活物質は、リチウム遷移金属複合酸化物が組成式(1)で表される化学組成となるような原料比の下、適切な焼成条件によって、リチウムと、ニッケル、コバルト等との合成反応を確実に進行させることにより製造できる。本発明の実施形態に係る正極活物質の製造方法としては、以下に説明する固相法を用いるものである。
図1Aに示すように、本実施形態に係るリチウムイオン二次電池用正極活物質の製造方法は、混合工程S10と、造粒工程S20と、焼成工程S30と、をこの順に含む。ここで造粒工程はスプレードライヤーによる造粒乾燥や共沈法による化学合成も含める。なお、これらの工程以外の工程が加わっても良い。例えば、造粒工程S20で得られた造粒粉に水分が多く残留している場合は、焼成工程S30で水蒸気が大量に発生するため、造粒工程S20に引き続き、加熱による脱水工程を追加して、造粒粉の水分量を低減させることができる。また図1Bに示すように、混合工程S10と造粒工程S20ではLi以外の金属を含む化合物について処理した後、Li化合物を加えて第2の混合工程S11で混合した後に焼成工程S30で焼成する製法も可能である。
本実施形態において、X元素を二次粒子内部の一次粒子表面近傍で濃化させるには、固相を用い、原料を混合する工程でその他の原料と同時に粉砕し、平均粒径0.3μm以下の均一で微細な粉末となして混合することが重要である。
第1熱処理工程S31では、熱処理温度を600℃以上750℃未満に制御して、造粒工程S20で得られた造粒体を熱処理して第1前駆体を得る。第1熱処理工程S31は、リチウム化合物とニッケル化合物等との反応により、炭酸成分や水酸化成分を除去すると共に、リチウム遷移金属複合酸化物の結晶を生成させることを主な目的とする。焼成前駆体中のニッケルを十分に酸化させて、リチウムサイトにニッケルが混入するカチオンミキシングを抑制し、ニッケルによる立方晶ドメインの生成を抑制する。また、リチウムイオンの挿入や脱離に伴う格子歪みないし結晶構造変化を小さくするために、Mで表される金属元素を十分に酸化させて、MeO2で構成される層の組成の均一性を高くすることができる。例えば、第1熱処理工程S31の時間は、2時間以上50時間以下にすることができる。
第2熱処理工程S32では、熱処理温度を750℃以上900℃以下に保持して、第1熱処理工程S31で得られた第1前駆体を熱処理して第2前駆体を得る。第2熱処理工程S32は、層状構造を有するリチウム遷移金属複合酸化物の結晶粒を、適切な粒径や比表面積まで粒成長させることを主な目的とする。例えば、第2熱処理工程S32の時間は第一熱処理工程S31の熱処理時間と同様に所定温度で保持することを意味しており、0.5時間以上15時間以下にすることができる。
上述した熱処理温度を600℃以上750℃未満に制御する段階(第1熱処理工程S31)と、750℃以上900℃以下に制御する段階(第2熱処理工程S32)の、少なくとも2以上の熱処理段階の後に、最高温度(例えば840℃)からの冷却過程で700℃以上800℃以下の温度帯に1.5時間以上保持してリチウム遷移金属複合酸化物を得るアニール処理工程S33を実施する。アニール処理工程S33は、以下に述べるように、層状構造を有するリチウム遷移金属複合酸化物の二次粒子の内部に残留する残存アルカリ成分をリチウム遷移金属複合酸化物内に取り込み、残存アルカリ成分が少なく、かつ結晶性の高い正極活物質を得ることを主な目的とする。
以上のアニール処理により正極活物質の二次粒子内の残存アルカリ成分を抑制しつつ、リチウムイオンの挿入や脱離に伴う格子歪みないし結晶構造変化が低減されている主相が形成されるため、正極合剤スラリーの耐ゲル化性に優れ、かつ高い放電容量、良好な充放電サイクル特性を得ることができる。なお、このようなアニール処理工程を有しない場合は、正極活物質の二次粒子内部で残存アルカリ成分の残留が多くなりやすく、正極活物質を圧縮した後に中和滴定で残存アルカリ成分を算出すると残存水酸化リチウム量が多くなる。
焼成工程S30において、第1熱処理工程S31の雰囲気の最高CO2濃度は、第2熱処理工程S32の最高CO2濃度より高く、前記第2熱処理工程S32の最高CO2濃度は、アニール処理工程の最高CO2濃度より高い。第1熱処理工程S31では脱炭酸ガスが目的の一つであり、熱処理によって発生したCO2によって第2熱処理工程S32、アニール処理工程S33より最高CO2濃度が高くなる。一方、第2熱処理工程S32、アニール処理工程S33では正極活物質の結晶性向上のためには最高CO2濃度が低い環境が好ましく、第1熱処理工程S31より最高CO2濃度が低いことが好ましい。特に、アニール処理工程S33では、正極活物質の二次粒子内の残存アルカリ成分低減のため、第1熱処理工程S31と第2熱処理工程S32よりも最高CO2濃度が低い環境が好ましい。
焼成工程S30においては、熱処理の手段として、ロータリーキルン等の回転炉、ローラーハースキルン、トンネル炉、プッシャー炉等の連続炉、バッチ炉等の適宜の熱処理装置を用いることができる。第1熱処理工程S31、第2熱処理工程S32、及び、アニール処理工程S33は、それぞれ、同一の熱処理装置を用いて行ってもよいし、互いに異なる熱処理装置を用いて行ってもよい。また、各熱処理工程は、雰囲気を入れ替えて断続的に行ってもよいし、雰囲気中のガスを排気しながら熱処理を行う場合は、連続的に行ってもよい。
また、正極活物質が電池に組み込まれ充放電された後でも本発明の特徴は保持されているが、Li量についてはLiが抜けてaの値は-0.9~0程度まで変化していると考えられる。
次に、前記のリチウム遷移金属複合酸化物を含む正極活物質(リチウムイオン二次電池用正極活物質)を正極に用いたリチウムイオン二次電池について説明する。
図2に示すように、リチウムイオン二次電池100は、非水電解液を収容する有底円筒状の電池缶101と、電池缶101の内部に収容された捲回電極群110と、電池缶101の上部の開口を封止する円板状の電池蓋102と、を備えている。
前記電極合剤(正極合剤スラリー)の粘度は例えば100~500mPa・sの範囲であれば適正な塗工ができ、スラリー作成後の粘度の変動が少ないことが安定生産の観点で重要である。粘度が変動する原因は主に正極活物質から溶出したアルカリ成分が結着剤を重合させてゲル化することである。このゲル化を抑制できる正極活物質を判定するにあたり、スラリー粘度の変化分を指標とするのが相応しい。すなわち正極合剤スラリーを作製した日のスラリー粘度をη0とし、前記作製日から5日間静置保管した正極合剤スラリーの粘度η5とした時、η5/η0は0.80以上1.2以下であることが好ましい。
以下、実施例、比較例を示して本発明について具体的に説明するが、本発明の技術的範囲はこれに限定されるものではない。
実施例1の正極活物質を製造した。原料として、炭酸リチウム、水酸化ニッケル、炭酸コバルト、炭酸マンガンを用意し、各原料を金属元素のモル比でLi:Ni:Co:Mnが、1.04:0.80:0.15:0.05となるように秤量し、固形分比が50質量%となるように純水を加えた。そして、粉砕機で湿式粉砕(湿式混合)して原料スラリーを調製した(混合工程S10)。原料スラリーの平均粒径D50は0.15μmだった。
混合工程を経て得られた原料スラリーをノズル式のスプレードライヤー(大川原化工機社製、ODL-20型)を用いて、噴霧圧は0.21MPa、噴霧量は260g/分で噴霧乾燥させて、造粒体を得た(造粒工程S20)。造粒体の平均粒径D50は12μmだった。そして、造粒体を焼成してリチウム遷移金属複合酸化物を得た(焼成工程S30)。焼成工程は具体的には、造粒体を、酸素ガス雰囲気に置換したロータリーキルンで、酸素気流中、650℃で6時間にわたって熱処理(仮焼成)して第1前駆体を得た(第1熱処理工程S31)。ロータリーキルンの排ガス中のCO2濃度は最高8500ppmだった。その後、第1前駆体を、酸素ガス雰囲気に置換したトンネル炉で、酸素気流中、800℃で10時間にわたって熱処理(本焼成)した(第2熱処理工程S32)。第2熱処理工程S32におけるトンネル炉の排ガス中のCO2濃度は最高200ppmだった。引き続き800℃から降温に移り、700℃まで0.5℃/分の降温速度となるように調整し、800℃から700℃の温度帯に3時間20分保持(アニール)してリチウム遷移金属複合酸化物を得た(アニール処理工程S33)。アニール処理工程S33におけるトンネル炉の排ガス中のCO2濃度は最高40ppmだった。図3(a)に縦軸に降温温度帯、横軸に降温時間を示すアニール処理工程図を示す。
そして、焼成によって得られた焼成粉は、目開き53μmの篩を用いて分級し、篩下の粉体を試料の正極活物質とした。
比較例1では、アニール処理をほぼ無しにした。本焼成後、室温まで5℃/分で降温させた。それ以外は実施例1と同様にして正極活物質を得た。よって、本焼成の最高温度から降温し、700℃以上800℃以下の温度帯に保持された時間は20分となった。なお、仮焼成の最高CO2濃度は8600ppm、本焼成の最高CO2濃度は210ppm、アニールの最高CO2濃度は20ppmだった。
合成した正極活物質の化学組成を、ICP-AES発光分光分析装置「OPTIMA8300」(パーキンエルマー社製)を使用して分析した。その結果、実施例1~19に係る正極活物質、比較例1~3に係る正極活物質は、表1-1に示す化学組成を有することが確認された。
正極合剤スラリー中の正極活物質は合剤塗工工程の調整過程でシェアがかかって二次粒子の一部が破壊されるため、正極活物質に荷重をかけて正極合剤スラリー中の正極活物質の状態を模擬した。正極粉1gを面積0.49cm2のダイスに入れた後、オートグラフ装置「AGS-1kNX」(島津製作所製)を使用して8kNの荷重、すなわち単位面積当たりの圧力160MPa(≒16,327N/cm2)で圧縮して正極活物質を回収した。図4に実施例1の圧縮前後の正極活物質の粒度分布を示す。圧縮前は平均粒径13.5μmを示していたのに対し、圧縮後は圧縮前には見られなかった5μm未満の粒子が増加して平均粒径8.5μmとなった。
正極活物質の残存アルカリ成分を、自動滴定装置「COM-1700A」(平沼産業製)を使用して次の手順で測定した。正極粉0.5gを純水30mlに入れ、Arで容器内を置換した後、1時間撹拌してLi成分を抽出し、吸引ろ過により、抽出液を得た。得られた抽出液25mlを純水で約40mlに薄め、0.02M塩酸を用いて滴定し、抽出液中の炭酸リチウム成分と水酸化リチウム成分の量を分析した。滴定曲線のピークは2段階となり、1段目の当量点と2段目の当量点の間の滴定量を炭酸リチウム量とし、1段目の当量点までの滴定量から前記炭酸リチウム量を差し引いた量を水酸化リチウム量とした。
上記した中和滴定で算出される正極活物質の残存水酸化リチウム量L1(質量%)と、正極活物質を上記にて圧縮した後に中和滴定で算出される残存水酸化リチウム量L2(質量%)と、をそれぞれ測定し、L1に対するL2の比L2/L1を得た。その結果を表1-2に示す。
正極活物質を、レーザーラマン顕微鏡「RAMANforce」(ナノフォトン製)を使用し、波長532nm、径0.36μmの条件で413×373μmの範囲のラマン分光スペクトルを取得した。取得したスペクトルを用い、ローレンツ分布関数によるフィッティング解析を経て、Eg及びA1gの振動ピークの半値幅(cm-1)を算出した。その結果を表1-2に示す。
正極活物質と、炭素系の導電材と、N-メチル-2-ピロリドン(NMP)に予め溶解させた結着剤(PVdF)とを質量比で96:2:2となるよう秤量し、混練機「ハイビスミックス2P-03」(プライミクス製)を使用して正極合剤スラリーを作製した。得られた正極合剤スラリーはB形粘度計「TVB10」(東機産業製)を使用して回転数0.5rpmで粘度を測定した。また、正極合剤スラリーをポリ容器に入れて25℃、50%RHの大気雰囲気で静置保管し、1日毎に粘度を測定した。このように正極活物質比率が96%以上の正極合剤スラリーの粘度を測定した。
スラリー作製日の正極合剤スラリー粘度η0と、スラリー作製日後にd日間静置保管した正極合剤スラリー粘度ηdの比(ηd/η0)が0.80以上1.2以下が維持される日数をもってゲル化耐性(日)とした。その結果を表1-2に示す。また、ゲル化耐性が異なる代表例として、実施例1、実施例5、実施例11については、スラリー作製日の正極合剤スラリー粘度η0と、スラリー作製日後に5日間静置保管した正極合剤スラリー粘度η5 の比(η5/η0)も併せて表1-2に示した。
合成した正極活物質を正極の材料として用いてリチウムイオン二次電池を作製した。その後、リチウムイオン二次電池の放電容量、容量維持率を求めた。
まず、均一に混合した正極合剤スラリーを、厚さ20μmのアルミニウム箔の正極集電体上に、塗布量が10mg/cm2となるように塗布した。次いで、正極集電体に塗布された正極合剤スラリーを120℃で熱処理し、溶媒を留去することによって正極合剤層を形成した。その後、正極合剤層を熱プレスで加圧成形し、直径15mmの円形状に打ち抜いて正極とした。
以上で測定した放電容量(Ah/Kg)と100サイクル容量維持率(%)を表1-2に示す。
まず、実施例1~19は、組成式(1)で表される化学組成が満たされており、圧縮前の残存水酸化リチウム量L1が0.8質量%以下であり、かつオートグラフで圧縮した後の残存水酸化リチウム量L2とL1の比率L2/L1が1.10以下である。その結果、正極合剤スラリーがゲル化するまで最低でも5日以上は保っており、また10日以上を保持できているものもある。よって、耐ゲル化性に優れていることが確認できた。また、電極特性についても、放電容量は概ね190Ah/kgを超える高い値を示し、且つ90%以上の高い容量維持率が得られた。
また、比較例2は、アニール処理が1時間以下と短く、残存水酸化リチウム量L1とL2/L1がいずれも実施例よりやや大きく、3日で正極合剤スラリーがゲル化した。製造工程上の許容差はあるものの、通常、耐ゲル化は5日以上が求められており不都合な結果であった。
また、比較例3は、アニール処理は無かったものの水洗で残存アルカリ成分を除去したものである。そのため残存水酸化リチウム量L1は非常に少なく、L2/L1は実施例より大きいものとなった。そして正極合剤スラリーがゲル化するまで30日かかり良好なものであった。しかしながら、容量維持率が79%と低かった。これは、水洗によって残存アルカリ成分に加えて正極活物質表層のLiも一部溶出したためと考えられる。また、水洗工程と、その後の乾燥工程が追加されるため、生産性の面でも劣るものと考えられる。
以上のことより、残存水酸化リチウム量が0.8質量%以下であれば、結着剤のゲル化の進行が抑制されると共に、結晶性の高い正極活物質が得られて容量維持率の低下が抑制されたものと考えられる。尚、比較例3は残存水酸化リチウム量が0.8質量%以下であるにも関わらず容量維持率が低かったのは、上述の通り水洗によって残存水酸化リチウムと共に正極活物質の表層近傍のリチウム引抜きが生じて、結晶性や結晶の構造安定性が低下して容量維持率が低下したものと考えられる。
101 電池缶
102 電池蓋
103 正極リード片
104 負極リード片
105 絶縁板
106 シール材
110 捲回電極群
111 正極
111a 正極集電体
111b 正極合剤層
112 負極
112a 負極集電体
112b 負極合剤層
113 セパレータ
Claims (7)
- 下記組成式(1);
Li1+aNibCocMdXeO2+α ・・・(1)
[但し、組成式(1)において、Mは、Al及びMnから選ばれる少なくとも1種を表し、XはLi、Ni、Co、Al及びMn以外の1種以上の金属元素を表し、a、b、c、d、e及びαは、それぞれ、-0.04≦a≦0.04、0.80≦b≦1.0、0≦c≦0.15、0≦d≦0.20、0≦e≦0.05、b+c+d+e=1、及び、-0.2<α<0.2を満たす数である。]で表されるリチウム遷移金属複合酸化物を含むリチウムイオン二次電池用正極活物質であって、中和滴定で算出される前記正極活物質の残存水酸化リチウム量(L1)が0.8質量%以下であり、かつ前記正極活物質を圧力160MPaで圧縮した後に中和滴定で算出される残存水酸化リチウム量(L2)と前記L1との比L2/L1が1.10以下であるリチウムイオン二次電池用正極活物質。 - 前記中和滴定で算出される前記正極活物質の残存水酸化リチウム量(L1)が0.6質量%以下である請求項1に記載のリチウムイオン二次電池用正極活物質。
- 前記XがTi、Ga、Mg、Zr、Znからなる群から選択される一つ以上の元素である請求項1または請求項2に記載のリチウムイオン二次電池用正極活物質。
- 前記リチウムイオン二次電池用正極活物質を含有する正極合剤スラリーを、作製日後に5日間静置保管したとき、作製日の正極合剤スラリー粘度η0と、前記作製日後に5日間静置保管した正極合剤スラリー粘度η5の比(η5/η0)が0.80以上1.2以下である請求項1~請求項3のいずれか一項に記載のリチウムイオン二次電池用正極活物質。
- 下記組成式(1);
Li1+aNibCocMdXeO2+α ・・・(1)
[但し、組成式(1)において、Mは、Al及びMnから選ばれる少なくとも1種を表し、XはLi、Ni、Co、Al及びMn以外の1種以上の金属元素を表し、a、b、c、d、e及びαは、それぞれ、-0.04≦a≦0.04、0.80≦b≦1.0、0≦c≦0.15、0≦d≦0.2、0≦e≦0.05、b+c+d+e=1、及び、-0.2<α<0.2を満たす数である。]で表されるリチウム遷移金属複合酸化物を含むリチウムイオン二次電池用正極活物質の製造方法であって、
前記組成式(1)中のLi、Ni、Co、M、Xの金属元素を含む化合物を混合する混合工程と、
前記混合工程を経て得られた原料スラリーから造粒体を得る造粒工程と、
前記造粒体を焼成して組成式(1)で表されるリチウム遷移金属複合酸化物を得る焼成工程と、を有し、
前記焼成工程は、熱処理温度を600℃以上750℃未満に保持する第1熱処理工程と、750℃以上900℃以下に保持する第2熱処理工程の、少なくとも2以上の熱処理段階を含み、前記焼成工程は、少なくとも、熱処理温度を600℃以上750℃未満に保持する第1熱処理工程と、熱処理温度を750℃以上900℃以下に保持する第2熱処理工程とを含む、多段熱処理工程であり、
その後、最高温度から降温し、700℃以上800℃以下の温度帯に1.5時間以上保持するアニール処理工程を、有するリチウムイオン二次電池用正極活物質の製造方法。 - 前記焼成工程において、前記第2熱処理工程の雰囲気の最高CO2濃度は、前記第1熱処理工程の最高CO2濃度より低く、前記アニール処理工程の最高CO2濃度は、前記第2熱処理工程の最高CO2濃度より低い、請求項5に記載のリチウムイオン二次電池用正極活物質の製造方法。
- 請求項1~請求項4のいずれか一項に記載のリチウムイオン二次電池用正極活物質を含有する正極を備えるリチウムイオン二次電池。
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020227004356A KR20220032592A (ko) | 2019-09-06 | 2020-09-01 | 리튬 이온 2차 전지용 양극 활물질 및 그 제조 방법과 리튬 이온 2차 전지 |
CN202080056812.1A CN114270567A (zh) | 2019-09-06 | 2020-09-01 | 锂离子二次电池用正极活性物质及其制造方法以及锂离子二次电池 |
EP20860305.0A EP4027410A4 (en) | 2019-09-06 | 2020-09-01 | POSITIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM-ION SECONDARY BATTERIES, METHOD FOR PRODUCING THE SAME AND LITHIUM-ION SECONDARY BATTERY |
JP2021543764A JP7082760B2 (ja) | 2019-09-06 | 2020-09-01 | リチウムイオン二次電池用正極活物質、及びその製造方法、並びにリチウムイオン二次電池 |
US17/670,097 US20220166019A1 (en) | 2019-09-06 | 2022-02-11 | Positive electrode active material for lithium-ion secondary batteries, method for producing same, and lithium-ion secondary battery |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2019-162759 | 2019-09-06 | ||
JP2019162759 | 2019-09-06 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US17/670,097 Continuation US20220166019A1 (en) | 2019-09-06 | 2022-02-11 | Positive electrode active material for lithium-ion secondary batteries, method for producing same, and lithium-ion secondary battery |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2021045025A1 true WO2021045025A1 (ja) | 2021-03-11 |
Family
ID=74853248
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2020/032980 WO2021045025A1 (ja) | 2019-09-06 | 2020-09-01 | リチウムイオン二次電池用正極活物質、及びその製造方法、並びにリチウムイオン二次電池 |
Country Status (6)
Country | Link |
---|---|
US (1) | US20220166019A1 (ja) |
EP (1) | EP4027410A4 (ja) |
JP (1) | JP7082760B2 (ja) |
KR (1) | KR20220032592A (ja) |
CN (1) | CN114270567A (ja) |
WO (1) | WO2021045025A1 (ja) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2022209988A1 (ja) * | 2021-03-30 | 2022-10-06 | 日立金属株式会社 | リチウムイオン二次電池用正極活物質の製造方法 |
JP2023008932A (ja) * | 2021-06-29 | 2023-01-19 | 三星エスディアイ株式会社 | リチウム二次電池用正極活物質、その製造方法、それを含むリチウム二次電池用正極、及びリチウム二次電池 |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN114062188B (zh) * | 2021-11-16 | 2022-08-12 | 中南大学 | 一种三元正极材料晶格锂溶出量的测定方法 |
CN117308550B (zh) * | 2023-11-29 | 2024-02-13 | 山东信泰节能科技股份有限公司 | 一种保温板生产用烘干装置 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0223508B2 (ja) * | 1985-10-22 | 1990-05-24 | Mabuchi Fusakichi | |
JP2005029424A (ja) * | 2003-07-14 | 2005-02-03 | Tosoh Corp | リチウムマンガン複合酸化物顆粒体の製造方法 |
JP2008521196A (ja) * | 2004-12-31 | 2008-06-19 | アイユーシーエフ−エイチワイユー(インダストリー−ユニバーシティー コーオペレイション ファウンデーション ハンヤン ユニバーシティー) | 二重層構造を有するリチウム二次電池用正極活物質、その製造方法及びそれを用いたリチウム二次電池 |
WO2019103046A1 (ja) * | 2017-11-21 | 2019-05-31 | 日立金属株式会社 | リチウムイオン二次電池用正極活物質の製造方法及び熱処理装置 |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5152456B2 (ja) * | 2006-11-10 | 2013-02-27 | 戸田工業株式会社 | 正極活物質及びその製造法、並びに非水電解質二次電池 |
WO2014189108A1 (ja) | 2013-05-22 | 2014-11-27 | 住友金属鉱山株式会社 | 非水系電解質二次電池用正極活物質とその製造方法 |
JP6657607B2 (ja) * | 2014-10-20 | 2020-03-04 | 日立金属株式会社 | リチウムイオン二次電池用正極活物質、その製造方法及びリチウムイオン二次電池 |
JP7041620B2 (ja) * | 2016-07-22 | 2022-03-24 | ユミコア | リチウム金属複合酸化物粉末 |
JP6826447B2 (ja) | 2016-10-14 | 2021-02-03 | Basf戸田バッテリーマテリアルズ合同会社 | 正極活物質粒子中の残存リチウム量の低減方法 |
JP6855752B2 (ja) * | 2016-10-31 | 2021-04-07 | 住友金属鉱山株式会社 | ニッケルマンガン複合水酸化物とその製造方法、非水系電解質二次電池用正極活物質とその製造方法、および非水系電解質二次電池 |
JP7110611B2 (ja) * | 2018-02-06 | 2022-08-02 | 住友金属鉱山株式会社 | 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活物質の評価方法、および非水系電解質二次電池 |
JP6523508B1 (ja) * | 2018-03-30 | 2019-06-05 | 住友化学株式会社 | リチウム複合金属化合物、リチウム二次電池用正極活物質、リチウム二次電池用正極、リチウム二次電池、及びリチウム複合金属化合物の製造方法 |
-
2020
- 2020-09-01 CN CN202080056812.1A patent/CN114270567A/zh active Pending
- 2020-09-01 JP JP2021543764A patent/JP7082760B2/ja active Active
- 2020-09-01 EP EP20860305.0A patent/EP4027410A4/en active Pending
- 2020-09-01 KR KR1020227004356A patent/KR20220032592A/ko unknown
- 2020-09-01 WO PCT/JP2020/032980 patent/WO2021045025A1/ja unknown
-
2022
- 2022-02-11 US US17/670,097 patent/US20220166019A1/en active Pending
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0223508B2 (ja) * | 1985-10-22 | 1990-05-24 | Mabuchi Fusakichi | |
JP2005029424A (ja) * | 2003-07-14 | 2005-02-03 | Tosoh Corp | リチウムマンガン複合酸化物顆粒体の製造方法 |
JP2008521196A (ja) * | 2004-12-31 | 2008-06-19 | アイユーシーエフ−エイチワイユー(インダストリー−ユニバーシティー コーオペレイション ファウンデーション ハンヤン ユニバーシティー) | 二重層構造を有するリチウム二次電池用正極活物質、その製造方法及びそれを用いたリチウム二次電池 |
WO2019103046A1 (ja) * | 2017-11-21 | 2019-05-31 | 日立金属株式会社 | リチウムイオン二次電池用正極活物質の製造方法及び熱処理装置 |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2022209988A1 (ja) * | 2021-03-30 | 2022-10-06 | 日立金属株式会社 | リチウムイオン二次電池用正極活物質の製造方法 |
JP2023008932A (ja) * | 2021-06-29 | 2023-01-19 | 三星エスディアイ株式会社 | リチウム二次電池用正極活物質、その製造方法、それを含むリチウム二次電池用正極、及びリチウム二次電池 |
Also Published As
Publication number | Publication date |
---|---|
CN114270567A (zh) | 2022-04-01 |
EP4027410A1 (en) | 2022-07-13 |
KR20220032592A (ko) | 2022-03-15 |
JP7082760B2 (ja) | 2022-06-09 |
EP4027410A4 (en) | 2023-10-25 |
US20220166019A1 (en) | 2022-05-26 |
JPWO2021045025A1 (ja) | 2021-03-11 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP7180532B2 (ja) | リチウムイオン二次電池用正極活物質及びリチウムイオン二次電池 | |
KR101852792B1 (ko) | 양극 활물질의 제조 방법 | |
WO2021045025A1 (ja) | リチウムイオン二次電池用正極活物質、及びその製造方法、並びにリチウムイオン二次電池 | |
JP7272345B2 (ja) | リチウムイオン二次電池用正極活物質及びリチウムイオン二次電池 | |
US11764356B2 (en) | Method for producing positive electrode active material for lithium ion secondary batteries | |
CN111052463B (zh) | 锂离子二次电池、正极活性物质和其制造方法 | |
WO2020195790A1 (ja) | リチウムイオン二次電池用正極活物質、及びその製造方法、並びにリチウムイオン二次電池 | |
JP6476776B2 (ja) | 正極活物質、正極、及びリチウムイオン二次電池 | |
JP2018060759A (ja) | ニッケルコバルトマンガン含有複合水酸化物の製造方法、非水電解質二次電池用正極活物質とその製造方法、および該正極活物質を用いた非水電解質二次電池 | |
JP2022177291A (ja) | 高強度リチウムイオン二次電池用正極活物質、及び、該正極活物質を用いたリチウムイオン二次電池 | |
WO2023047974A1 (ja) | リチウムイオン二次電池用正極活物質およびリチウムイオン二次電池 | |
Ju et al. | Synthesis and electrochemical characterization of nano-sized LiMn1. 5Ni0. 5O4 cathode materials for lithium-ion batteries |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 20860305 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 20227004356 Country of ref document: KR Kind code of ref document: A |
|
ENP | Entry into the national phase |
Ref document number: 2021543764 Country of ref document: JP Kind code of ref document: A |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
ENP | Entry into the national phase |
Ref document number: 2020860305 Country of ref document: EP Effective date: 20220406 |