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
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G53/00—Compounds of nickel
  • C01G53/40—Complex oxides containing nickel and at least one other metal element
  • C01G53/42—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2
  • C01G53/44—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese
  • C01G53/50—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G53/00—Compounds of nickel
  • C01G53/40—Complex oxides containing nickel and at least one other metal element
  • C01G53/42—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2
  • C01G53/44—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese
  • C01G53/50—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2
  • C01G53/502—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2 containing lithium and cobalt
  • C01G53/504—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2 containing lithium and cobalt with the molar ratio of nickel with respect to all the metals other than alkali metals higher than or equal to 0.5, e.g. Li(MzNixCoyMn1-x-y-z)O2 with x ≥ 0.5
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G53/00—Compounds of nickel
  • C01G53/80—Compounds containing nickel, with or without oxygen or hydrogen, and containing one or more other elements
  • C01G53/82—Compounds containing nickel, with or without oxygen or hydrogen, and containing two or more other elements
• • 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
  • 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
• • 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
  • H01M2004/021—Physical characteristics, e.g. porosity, surface area
• • 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 method for producing a metal composite hydroxide and a positive electrode active material for lithium secondary batteries.
• a method for producing a positive electrode active material for a lithium secondary battery for example, there is a method in which a lithium compound and a metal composite compound containing a metal element other than Li are mixed and fired.
• Patent Document 1 describes secondary particles formed by aggregating a plurality of plate-shaped primary particles and fine primary particles smaller than the plate-shaped primary particles as a precursor of a positive electrode active material for a lithium ion secondary battery.
• a nickel manganese cobalt-containing composite hydroxide is disclosed. It has been disclosed that a lithium ion secondary battery manufactured using a positive electrode active material for a lithium ion secondary battery using the nickel manganese cobalt-containing composite hydroxide as a precursor has high durability and excellent output characteristics. There is.
• the present invention has been made in view of the above circumstances, and provides a metal composite hydroxide used as a precursor of a positive electrode active material for a lithium secondary battery, which can provide a lithium secondary battery with high initial efficiency, and a metal composite hydroxide of the metal.
• An object of the present invention is to provide a method for producing a positive electrode active material for a lithium secondary battery using a composite hydroxide.
• the present invention includes the following [1] to [4].
• a metal composite hydroxide used as a precursor of a positive electrode active material for lithium secondary batteries which contains Ni, Co, and Mn and satisfies all of the following requirements (1) to (4). oxide.
• (1) Average particle strength is 10 MPa or more and less than 45 MPa.
• (2) The molar ratio of manganese to cobalt (Mn/Co) is more than 1.0.
• BET specific surface area is less than 40 m 2 /g.
• Average particle diameter D50 is 4.0 ⁇ m or less.
• the metal composite hydroxide according to [1] which is represented by the following compositional formula (I).
• a method for producing a positive electrode active material for a lithium secondary battery which includes a firing step of firing at a temperature of °C or less.
• a metal composite hydroxide used as a precursor of a positive electrode active material for a lithium secondary battery and a lithium secondary battery using the metal composite hydroxide, which provides a lithium secondary battery with high initial efficiency.
• a method for producing a positive electrode active material for a next battery can be provided.
• MCH Metal Composite Hydroxide
• CAM cathode active material for lithium secondary batteries
• Ni indicates not nickel metal alone but the Ni element. The same applies to other elements such as Co and Mn.
• Primary particles refer to particles that do not have grain boundaries in their appearance when observed using a scanning electron microscope or the like with a field of view of 10,000 times or more and 30,000 times or less.
• Secondary particles are particles in which the primary particles are aggregated. That is, the secondary particles are aggregates of primary particles.
• a or more and B or less is written as “A to B”. For example, when a numerical range is described as “1 to 10 MPa”, it means a range from 1 MPa to 10 MPa, and a numerical range including a lower limit of 1 MPa and an upper limit of 10 MPa.
• the average particle strength (unit: MPa) of MCH can be measured and calculated as follows. First, 20 secondary particles are randomly selected from the MCH. The particle size and particle strength of each of the selected secondary particles are measured using a micro compression tester (for example, MCT-510, manufactured by Shimadzu Corporation).
• the particle strength Cs (unit: MPa) is determined by the following formula (A).
• P is the test force (unit: N)
• d is the particle diameter (unit: mm).
• P is a pressure value at which the amount of displacement becomes maximum while the test pressure remains approximately constant when the test pressure is gradually increased.
• d is a value obtained by measuring the diameters in the X direction and Y direction in the observation image of the micro compression tester, and calculating the average value thereof.
• Cs 2.8P/ ⁇ d 2 ...(A)
• the average value of Cs of the obtained 20 secondary particles is the average particle strength. Since particle strength is standardized by particle diameter, if each particle has the same structure, particles with different particle diameters will have the same particle strength (average particle strength ⁇ 5%). On the other hand, if the particle strengths differ between particles, it can be said that the structures of the respective particles differ.
• the standard deviation of the particle strength of MCH can be calculated from the average particle strength determined above (average particle strength) and Cs of the 20 secondary particles.
• the average particle diameter D 50 (unit: ⁇ m) of MCH or CAM can be determined from the particle size distribution of MCH or CAM measured by laser diffraction scattering method. Specifically, 0.1 g of powder of the object to be measured, for example, MCH or CAM, is added to 50 mL of a 0.2% by mass sodium hexametaphosphate aqueous solution to obtain a dispersion in which the powder is dispersed. Next, the particle size distribution of the obtained dispersion liquid is measured using a laser diffraction scattering particle size distribution measuring device (for example, Microtrac MT3300EXII manufactured by Microtrac Bell Co., Ltd.) to obtain a volume-based cumulative particle size distribution curve. . In the obtained cumulative particle size distribution curve, the value of the particle size at the time of 50% accumulation from the fine particle side is the average particle size (hereinafter sometimes referred to as D50 ).
• D50 Average particle size
• the BET specific surface area (unit: m 2 /g) of MCH can be measured by the BET (Brunauer, Emmett, Teller) method.
• nitrogen gas is used as the adsorption gas.
• the measurement can be performed using a BET specific surface area meter (for example, Macsorb (registered trademark) manufactured by Mountech).
• composition The composition of each metal element in MCH can be measured by inductively coupled plasma emission spectrometry (ICP). For example, after dissolving MCH in hydrochloric acid, the amount of each metal element can be measured using an inductively coupled plasma emission spectrometer (for example, SPS3000, manufactured by SII Nano Technology Co., Ltd.).
• ICP inductively coupled plasma emission spectrometry
• the evaluation method of CAM in this specification is as follows.
• MCH ⁇ Metal composite hydroxide ⁇ MCH of this embodiment can be used as a precursor of CAM.
• MCH contains Ni, Co, and Mn, and satisfies all of the following requirements (1) to (4).
• Average particle strength is 10 MPa or more and less than 45 MPa.
• the molar ratio of manganese to cobalt (Mn/Co) is more than 1.0.
• BET specific surface area is less than 40 m 2 /g.
• Average particle diameter D50 is 4.0 ⁇ m or less.
• MCH is an aggregate of multiple particles.
• MCH is in powder form.
• the aggregate of a plurality of particles may contain only secondary particles, or may be a mixture of primary particles and secondary particles.
• the average particle strength of MCH is 10 MPa or more and less than 45 MPa.
• the average particle strength is 10 MPa or more, preferably 15 MPa or more, and more preferably 20 MPa or more.
• the average particle strength is less than 45 MPa, preferably 44 MPa or less.
• the lower limit value and upper limit value can be arbitrarily combined.
• the average particle strength is preferably 15 to 44 MPa, more preferably 20 to 44 MPa.
• the ratio of D 50 of CAM to D 50 of MCH is preferably 0.8 or more, more preferably 0.9 or more, and even more preferably 1.0 or more.
• the ratio of D 50 of CAM to D 50 of MCH is preferably 1.4 or less, more preferably 1.3 or less, and even more preferably 1.2 or less.
• the lower limit value and upper limit value can be arbitrarily combined.
• the ratio of D 50 of CAM to D 50 of MCH is preferably 0.8 to 1.4, more preferably 0.9 to 1.3, and 1.0 to 1.2. It is even more preferable that there be.
• An MCH that satisfies requirement (1) is an MCH with low particle strength.
• Particle strength is determined by multiple factors related to the state of agglomeration of primary particles, such as the density of primary particles in secondary particles, orientation of primary particles, contact area between primary particles, and strength of adhesion between primary particles. it is conceivable that. Further, the above factors are also influenced by characteristics derived from the primary particles, such as the size and shape of the primary particles. For example, even if MCH has a low density of primary particles in secondary particles, depending on the other factors mentioned above, the average particle strength of MCH will be 45 MPa or more, and it is considered that the above requirement (1) will not be satisfied.
• primary particles having a sufficiently grown anisotropic shape are preferred.
• "Anisotropic shape” means a shape obtained as a result of growth biased toward at least one of the a-axis, b-axis, and c-axis crystal axes.
• An example of an anisotropic shape is a rod-like shape obtained as a result of growth biased toward one axis.
• the density of the primary particles in the secondary particles becomes lower than that of the primary particles that have an isotropic shape.
• "Isotropic shape” means a shape obtained as a result of growth that is relatively uniform in the directions of the a-axis, b-axis, and c-axis crystal axes.
• the aggregation state of primary particles in secondary particles is that the density of the primary particles is low, the orientation of the primary particles is uniform, the contact area between the primary particles is small, and the strength of adhesion between the primary particles is small. is preferred.
• Such secondary particles tend to have low particle strength and easily satisfy the requirement (1).
• the primary particles are aligned with each other.
• cracks in the secondary particles are likely to occur due to sliding between adjacent primary particles. Therefore, such secondary particles tend to have low particle strength and easily satisfy the requirement (1).
• the primary particles and the aggregation state of the primary particles in the secondary particles can be confirmed by observation using a scanning electron microscope.
• Mn/Co The molar ratio of manganese to cobalt in MCH (hereinafter also referred to as "Mn/Co") is more than 1.0, preferably 1.1 or more, and more preferably 1.2 or more. . Mn/Co may be 4.0 or less, 3.0 or less, or 2.0 or less. The lower limit value and upper limit value can be arbitrarily combined. Mn/Co is preferably more than 1.0 and 4.0 or less, more preferably 1.1 to 3.0, and even more preferably 1.2 to 2.0. When Mn/Co exceeds (or exceeds) the lower limit value, it is possible to reduce the amount of cobalt, which is relatively expensive, compared to manganese, which is relatively cheap, which is economical.
• Mn/Co is more than (or more than) the lower limit value
• the initial efficiency of the obtained lithium secondary battery is likely to be improved.
• Mn/Co is within the above range, changes in the average particle diameter are suppressed when producing CAM from MCH.
• the BET specific surface area of MCH is less than 40 m 2 /g, preferably 38 m 2 /g or less, more preferably 30 m 2 /g or less, even more preferably 20 m 2 /g or less.
• the BET specific surface area may be 5 m 2 /g or more, 7 m 2 /g or more, or 9 m 2 /g or more.
• the lower limit value and upper limit value can be arbitrarily combined.
• the BET specific surface area of MCH is preferably 5 m 2 /g or more and less than 40 m 2 /g, more preferably 5 to 38 m 2 /g, even more preferably 7 to 30 m 2 /g, and 9 It is particularly preferred that the area is 20 m 2 /g.
• the BET specific surface area is equal to or greater than the lower limit value, the crystallinity is prevented from becoming excessively high and the requirement (1) is easily satisfied.
• the BET specific surface area is less than or equal to the upper limit value, a change in the average particle diameter is suppressed when producing CAM from MCH.
• the D 50 of MCH is 4.0 ⁇ m or less, preferably 1.0 to 4.0 ⁇ m, more preferably 1.5 to 4.0 ⁇ m, and 2.0 to 4.0 ⁇ m. is even more preferable.
• D50 is at least the lower limit of the above range, when producing CAM from MCH, an increase in the BET specific surface area can be suppressed, and gas generation due to side reactions with the electrolytic solution can be suppressed.
• D50 is below the upper limit of the above range, changes in the average particle diameter are suppressed when CAM is produced from MCH.
• MCH preferably satisfies the following physical properties.
• the standard deviation of the particle strength of MCH is preferably 2 to 12 MPa.
• the standard deviation is preferably 2 MPa or more, more preferably 3 MPa or more, and even more preferably 4 MPa or more.
• the standard deviation is preferably 12 MPa or less, more preferably 11 MPa or less.
• the lower limit value and upper limit value can be arbitrarily combined.
• the standard deviation is more preferably 3 to 11 MPa, and even more preferably 4 to 11 MPa.
• the standard deviation of the particle strength is at least the lower limit of the above range, particle cracking due to contact between particles is less likely to occur and handling properties tend to be improved. If the standard deviation of the particle strength is below the upper limit of the above range, the uniformity of the precursor will be high, and the cycle characteristics of the resulting battery using the CAM will tend to be high.
• the MCH of this embodiment has Mn/Co of more than 1.0. It is known that MCH with an Mn/Co ratio of more than 1.0 is easily oxidized during MCH production, and the crystallinity decreases accordingly. In the MCH of this embodiment, by optimizing the manufacturing conditions as described below, the crystallinity is maintained at a high level even when Mn/Co exceeds 1.0. The inventors of the present application have discovered that when the crystallinity of MCH with an Mn/Co ratio of more than 1.0 increases, the primary particles grow into a rod-like shape.
• the density of the primary particles in the secondary particles is considered to be lower than that of a primary particle having an isotropic shape.
• the high degree of crystallinity is considered to be one of the factors that satisfies the requirement (1).
• compositional formula ⁇ MCH is preferably a compound represented by the following compositional formula (I). Ni 1-x-y-w Co x Mn y M w (OH) 2+ ⁇ ...Formula (I) In the compositional formula (I), 0 ⁇ x ⁇ 0.5, 0 ⁇ y ⁇ 0.5, 0 ⁇ w ⁇ 0.5, x ⁇ y, 0 ⁇ x+y+w ⁇ 1, 0 ⁇ , and M is One or more elements selected from the group consisting of Fe, Cu, Ti, Mg, Al, Zn, Sn, Zr, Nb, Ga, W, Mo, B, and Si.
• M is selected from the group consisting of Ti, Mg, Al, Zr, Nb, W, Mo, B, and Si, from the viewpoint that the cycle characteristics of the battery using the obtained CAM tend to be high. It is preferably one or more elements, and more preferably one or more elements selected from the group consisting of Al, Zr, Nb, and W.
• x is preferably 0.01 or more, more preferably 0.02 or more, particularly preferably 0.03 or more. x is preferably 0.44 or less, more preferably 0.42 or less, particularly preferably 0.40 or less.
• the above upper limit value and lower limit value of x can be arbitrarily combined.
• the above compositional formula (I) preferably satisfies 0.01 ⁇ x ⁇ 0.44, more preferably satisfies 0.02 ⁇ x ⁇ 0.42, and satisfies 0.03 ⁇ x ⁇ 0.40. It is particularly preferable.
• y is preferably 0.02 or more, more preferably 0.03 or more, and particularly preferably 0.04 or more. y is preferably 0.45 or less, more preferably 0.43 or less, particularly preferably 0.41 or less.
• the above upper limit value and lower limit value of y can be arbitrarily combined.
• the above compositional formula (I) preferably satisfies 0.02 ⁇ y ⁇ 0.45, more preferably satisfies 0.03 ⁇ y ⁇ 0.43, and satisfies 0.04 ⁇ y ⁇ 0.41. It is particularly preferable.
• x+y+w is preferably 0.20 or more, more preferably 0.30 or more, and particularly preferably 0.40 or more.
• x+y+w is preferably 0.70 or less, more preferably 0.66 or less, particularly preferably 0.60 or less.
• the above upper limit value and lower limit value of x+y+w can be arbitrarily combined.
• compositional formula (I) preferably satisfies 0 ⁇ 1.2.
• the above ⁇ is appropriately adjusted depending on the chemical composition that the hydroxide of each metal element can have.
• the method for manufacturing MCH of the present embodiment includes supplying a solution of a metal salt of Ni, a solution of a metal salt of Co, a solution of a metal salt of Mn, a complexing agent, and an alkaline solution to a reaction tank. It includes a reaction step of performing a coprecipitation reaction.
• MCH can be produced by a known batch coprecipitation method or continuous coprecipitation method.
• MCH containing Ni, Co, and Mn a method for manufacturing MCH containing Ni, Co, and Mn will be described as an example.
• a nickel salt solution, a cobalt salt solution, a manganese salt solution, a complexing agent, and an alkaline solution are reacted to form Ni (1-x MCH represented by '-y') Cox'Mny ' (OH) 2 is produced.
• x' and y' correspond to x and y in the compositional formula (I), respectively.
• the nickel salt that is the solute of the nickel salt solution is not particularly limited, but for example, at least one of nickel sulfate, nickel nitrate, nickel chloride, and nickel acetate can be used.
• cobalt salt that is the solute of the cobalt salt solution
• at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, and cobalt acetate can be used.
• manganese salt that is the solute of the manganese salt solution
• at least one of manganese sulfate, manganese nitrate, manganese chloride, and manganese acetate can be used.
• MCH containing a metal other than Ni, Co, and Mn a sulfate, nitrate, chloride, or acetate of the metal can be used as a solute.
• the metal salt is used in a proportion corresponding to the composition ratio of Ni (1-x'-y') C x' Mn y' (OH) 2 . That is, the amount of each metal salt is adjusted so that the molar ratio of Ni, Co, and Mn in the mixed solution containing the metal salts corresponds to (1-x'-y'):x':y' of the composition formula. stipulates. Also, water is used as a solvent.
• the complexing agent is one that can form a complex with nickel ions, cobalt ions, and manganese ions in an aqueous solution, such as ammonium ions such as ammonium hydroxide, ammonium sulfate, ammonium chloride, ammonium carbonate, or ammonium fluoride.
• the donors include hydrazine, ethylenediaminetetraacetic acid, nitrilotriacetic acid and uracil diacetic acid and glycine, with ammonium ion donors being preferred.
• the amount of the complexing agent contained in a mixed solution containing a nickel salt solution, a cobalt salt solution, a manganese salt solution, and a complexing agent is, for example, the amount of the complexing agent based on the total number of moles of the metal salts (nickel salt, cobalt salt, and manganese salt). It is preferable that the ratio is greater than 0 and less than or equal to 2.0.
• the ammonia concentration relative to the total volume of the solution in the reaction tank is preferably 0.8 to 3.9 g/L, and 1.0 to 3.9 g/L. It is more preferably L, and even more preferably 1.0 to 3.0 g/L.
• the ammonia concentration is within the above range, requirements (1) and (4) are easily satisfied.
• the mixed solution in order to adjust the pH value of the mixed solution containing the nickel salt solution, cobalt salt solution, manganese salt solution, and complexing agent, the mixed solution should be adjusted before the pH of the mixed solution changes from alkaline to neutral.
• alkaline solution examples include aqueous solutions of alkali metal hydroxides.
• alkali metal hydroxide examples include sodium hydroxide and potassium hydroxide.
• the pH value in this specification is defined as a value measured when the temperature of the liquid mixture is 40°C.
• the pH of the mixed solution is measured when the temperature of the mixed solution sampled from the reaction tank reaches 40°C. If the temperature of the sampled liquid mixture is lower than 40°C, the mixed liquid is heated to 40°C and the pH is measured. If the temperature of the sampled mixed liquid exceeds 40°C, the mixed liquid is cooled to 40°C and the pH is measured.
• Ni, Co, and Mn react, and Ni (1-x'-y') Co x ' Mny ' (OH) 2 is generated.
• the reaction temperature is preferably 50 to 80°C, more preferably 50 to 75°C, even more preferably 65 to 75°C.
• the reaction temperature is equal to or higher than the lower limit, MCH crystals grow easily, crystallinity improves, and as a result, the requirement (1) is easily satisfied.
• the reaction temperature is below the upper limit value, the reaction can be easily controlled.
• the pH value in the reaction tank is preferably pH 10.0 to 12.1, more preferably pH 10.0 to 11.9, even more preferably pH 11.5 to 11.9, and pH 11. More preferably, it is between .5 and 11.8.
• the pH is within the above range, the crystallinity and crystal anisotropy of MCH are controlled, and as a result, the above requirement (1) is easily satisfied.
• the time for neutralizing the reaction precipitate is, for example, 1 to 24 hours.
• an overflow type reaction tank can be used to separate the formed reaction precipitate.
• the reaction tank When producing MCH by the batch co-precipitation method, the reaction tank is equipped with a reaction tank without an overflow pipe and a concentration tank connected to the overflow pipe, and the overflowing reaction precipitate is concentrated in the concentration tank and then recycled again.
• Examples include devices having a mechanism for circulating to a reaction tank.
• a gas containing oxygen it is preferable to supply a gas containing oxygen to the solution in the reaction tank.
• a gas containing oxygen is supplied to the solution in the reaction tank, primary particles grow while part of the MCH is oxidized. It is known that primary particles of MCH generally grow isotropically, but when primary particles grow while a part of MCH is oxidized, the primary particles grow anisotropically.
• the oxygen concentration relative to the total volume of the oxygen-containing gas is preferably 0.01 to 1.0% by volume. When the oxygen concentration is equal to or higher than the lower limit, anisotropic growth of primary particles is promoted. When the oxygen concentration is below the upper limit value, a decrease in crystallinity is suppressed. As a result, it becomes easier to satisfy the above requirement (1).
• This effect is particularly large when the composition satisfies requirement (2). Therefore, in order to satisfy the requirements (1), (3), and (4), it is preferable to adjust various conditions as appropriate.
• the composition satisfies requirement (2) the crystallinity of MCH decreases as described above. When the crystallinity decreases, it becomes particularly difficult to satisfy the above requirement (1).
• the manufacturing method of this embodiment by optimizing various conditions, the crystallinity and anisotropy are maintained high even when the composition satisfies the requirement (2), and as a result, the requirement (1) is satisfied. It becomes easier.
• the reaction temperature is 50 to 80°C
• the pH is 10.0 to 11.9
• the ammonia concentration is 0.8 to 3.9 g/L with respect to the total volume of the solution in the reaction tank
• the reaction temperature is 50 to 80°C.
• the oxygen concentration of the gas containing oxygen gas supplied to the solution in the tank is 0.01 to 1.0% by volume
• the reaction temperature is 65 to 75°C
• the pH is 11.5 to 11.8.
• the ammonia concentration relative to the total volume of the solution in the reaction tank is 1.0 to 3.0 g/L
• the oxygen concentration of the gas containing oxygen gas supplied to the solution in the reaction tank is 0.02 to 0.05% by volume. It is more preferable that Such reaction conditions make it easier to obtain MCH that satisfies the requirements (1), (3), and (4).
• reaction precipitate is washed and isolated.
• a method is used in which, for example, a slurry containing a reaction precipitate (that is, a coprecipitate slurry) is dehydrated by centrifugation, suction filtration, or the like.
• the isolated reaction precipitate is washed, dehydrated, dried and sieved to obtain MCH containing Ni, Co and Mn.
• the reaction precipitate is preferably washed with water, weakly acidic water, or alkaline washing liquid.
• it is preferable to wash with an alkaline cleaning liquid, and more preferably to wash with an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution.
• the temperature of the water, weakly acidic water, and alkaline cleaning liquid used is preferably 30°C or higher. Furthermore, it is preferable to perform washing one or more times. Note that after washing with a solution other than water, it is preferable to further wash with water so that compounds derived from the solution do not remain in the reaction precipitate.
• the drying temperature is preferably 80 to 250°C, more preferably 90 to 230°C.
• the drying time is preferably 0.5 to 30 hours, preferably 1 to 25 hours.
• the drying pressure may be normal pressure or reduced pressure.
• MCH can be manufactured.
• the method for manufacturing CAM includes a mixing step of mixing MCH and a lithium compound, and a firing step of firing the resulting mixture at a temperature of 500° C. or higher and 1000° C. or lower in an oxygen-containing atmosphere.
• CAM which is a lithium metal composite oxide, can be manufactured by the method described above.
• the above-mentioned MCH is used in the CAM manufacturing method.
• [Mixing process] Mix MCH and a lithium compound.
• the lithium compound used in this embodiment at least one of lithium carbonate, lithium nitrate, lithium acetate, lithium hydroxide (including hydrates), lithium oxide, lithium chloride, and lithium fluoride can be used. .
• lithium hydroxide or lithium carbonate or a mixture thereof is preferred.
• the content of lithium carbonate in the lithium hydroxide is preferably 5% by mass or less.
• a lithium compound and MCH are mixed in consideration of the composition ratio of the final target product to obtain a mixture of the lithium compound and MCH.
• the amount (molar ratio) of lithium to the total amount of metals contained in MCH is preferably 0.98 to 1.20, more preferably 1.04 to 1.10, particularly preferably 1.05 to 1.10. .
• the obtained mixture is fired at a firing temperature of 500°C or more and 1000°C or less in an oxygen-containing atmosphere. By firing the mixture, crystals of the lithium metal composite oxide grow.
• the firing temperature in this specification is the temperature of the atmosphere in the firing furnace, and means the highest temperature of the holding temperature (maximum holding temperature).
• the firing temperature means the temperature at which heating is performed at the highest holding temperature of each firing stage.
• the firing temperature is, for example, preferably 650 to 900°C, more preferably 680 to 850°C, and particularly preferably 700 to 820°C.
• the firing temperature is equal to or higher than the lower limit of the above range, a CAM having a strong crystal structure can be obtained. Further, when the firing temperature is below the upper limit of the above range, volatilization of lithium on the surface of the CAM particles can be reduced.
• the holding time during firing is preferably 3 to 50 hours, more preferably 4 to 20 hours.
• the retention time during firing is equal to or less than the upper limit of the above range, volatilization of lithium is suppressed and deterioration of battery performance is suppressed.
• the holding time during firing is at least the lower limit of the above range, crystal growth is promoted and deterioration in battery performance is suppressed.
• the temperature increase rate in the firing step to reach the maximum holding temperature is preferably 80°C/hour or more, more preferably 100°C/hour or more, and particularly preferably 150°C/hour or more.
• the rate of temperature increase in the heating step at which the maximum holding temperature is reached is calculated from the time from when the temperature rise starts until the holding temperature is reached in the baking device.
• the firing process has a plurality of firing stages at different firing temperatures.
• the firing atmosphere air, oxygen, nitrogen, argon, or a mixed gas thereof is used depending on the desired composition, and if necessary, multiple firing steps are performed.
• the firing atmosphere is preferably an oxygen-containing atmosphere.
• the mixture of MCH and lithium compound may be calcined in the presence of an inert melting agent.
• the inert melting agent is added to an extent that does not impair the initial capacity of a battery using CAM, and may remain in the fired product.
• the inert melting agent for example, those described in WO2019/177032A1 can be used.
• the firing device used during firing is not particularly limited, and for example, either a continuous firing furnace or a fluidized fluidized firing furnace may be used.
• Continuous firing furnaces include tunnel furnaces and roller hearth kilns.
• a rotary kiln may be used as the fluidized firing furnace.
• CAM is obtained by firing the mixture of MCH and lithium compound as described above.
• the D 50 of the CAM is preferably 3.0 to 6.0 ⁇ m, more preferably 3.0 to 5.0 ⁇ m, and even more preferably 3.5 to 5.0 ⁇ m.
• Measurements of various parameters of MCH and CAM produced by the method described below are as follows: (average particle strength), (standard deviation of particle strength), (average particle diameter D 50 ), (composition), (BET specific surface area) This was carried out using the measurement method described in .
• the obtained positive electrode mixture was applied to a 40 ⁇ m thick Al foil serving as a current collector and vacuum dried at 150° C. for 8 hours to obtain a positive electrode for a lithium secondary battery.
• the electrode area of this positive electrode for a lithium secondary battery was 1.65 cm 2 .
• the electrolytic solution used was a liquid obtained by dissolving LiPF 6 at 1 mol/l in a mixture of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate at a ratio of 30:35:35 (volume ratio).
• metal lithium is used as the negative electrode, placed on top of the separator, covered with a gasket, and crimped with a crimping machine to form a lithium secondary battery (coin-shaped half cell R2032.
• coin-shaped half cell coin-shaped half cell
• Example 1 After putting water into a reaction tank equipped with a stirrer and an overflow pipe, an aqueous sodium hydroxide solution was added and the liquid temperature was maintained at 70°C.
• Mixed raw material liquid 1 was prepared by mixing a nickel sulfate aqueous solution, a cobalt sulfate aqueous solution, and a manganese sulfate aqueous solution so that the molar ratio of Ni:Co:Mn was 0.5:0.2:0.3.
• the reaction precipitate 1 was washed using a 5% by mass aqueous sodium hydroxide solution that was 20 times the mass of the reaction precipitate 1. After washing, it was dehydrated with a centrifuge, washed with water, dehydrated, isolated, and dried at 105° C. for 20 hours to obtain MCH1 containing Ni, Co, and Mn.
• MCH1 containing Ni, Co, and Mn.
• Table 1 Various parameters of MCH1 are shown in Table 1 (hereinafter, Examples 2 and 3 and Comparative Examples 1 and 2 are also shown in the same way). Note that 1-x-y-w, x, y, and w in the composition in Table 1 are values corresponding to the above formula (I).
• Lithium carbonate was weighed so that the amount of Li (molar ratio) to the total amount of Ni, Co, and Mn contained in MCH1 was 1.07.
• Mixture 1 was obtained by mixing MCH1 and lithium carbonate.
• the obtained mixture 1 was fired at 750° C. for 6 hours in an oxygen atmosphere to obtain a lithium metal composite oxide powder.
• the obtained powder and pure water whose liquid temperature was adjusted to 5°C were mixed so that the ratio of the mass of the powder to the total amount was 0.3, and the slurry was stirred for 20 minutes and then dehydrated.
• CAM1 was obtained by rinsing with twice the mass of the above powder in pure water whose temperature was adjusted to 5°C, isolation, and drying at 150°C.
• Table 1 hereinafter, Examples 2 and 3 and Comparative Examples 1 and 2 are also shown in the same way).
• a lithium secondary battery was produced using the obtained CAM1, and the initial efficiency was measured.
• the results are shown in Table 1 (hereinafter, Examples 2 and 3 and Comparative Examples 1 and 2 are also shown in the same manner).
• Example 2 MCH2 and CAM2 were prepared in the same manner as in Example 1, except that the pH of the solution in the reaction tank during MCH production was 11.55 (measurement temperature: 40°C) and the ammonium concentration in the tank was 1.1 g/L. I got it. A lithium secondary battery was produced using the obtained CAM2, and the initial efficiency was measured.
• Example 3 During MCH production, a nickel sulfate aqueous solution, a cobalt sulfate aqueous solution, a manganese sulfate aqueous solution, and a zirconium sulfate aqueous solution are mixed with a Ni:Co:Mn:Zr molar ratio of 0.548:0.199:0.248:0.005. Except that the liquid temperature in the reaction tank was 50°C, the pH of the solution in the reaction tank was 11.94 (measurement temperature: 40°C), and the ammonium concentration in the tank was 2.6 g/L. MCH3 and CAM3 were obtained in the same manner as in Example 1. A lithium secondary battery was produced using the obtained CAM3, and the initial efficiency was measured.
• Example 1 Example 1 except that the liquid temperature in the reaction tank during MCH production was 30°C, the pH in the reaction tank was 11.95 (measurement temperature: 40°C), and the ammonium concentration in the tank was 4.0g/L. MCH4 and CAM4 were obtained in the same manner as above. A lithium secondary battery was produced using the obtained CAM4, and the initial efficiency was measured.
• lithium secondary batteries using CAMs for lithium secondary batteries in which MCH of Examples 1 to 3, which satisfies requirements (1) to (4), is a precursor have high initial efficiency. Furthermore, in Examples 1 to 3, D 50 (CAM)/D 50 (MCH) was within the range of 1.1 to 1.2, and the change in average particle diameter was suppressed when producing CAM from MCH. It turns out that

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