Nickel composite hydroxide, a cathode active material using the nickel composite hydroxide as a precursor, and a method for producing the same

Abstract

The purpose of the present invention is to provide a precursor of a positive electrode active material with which it is possible to obtain a positive electrode active material capable of exhibiting high charge capacity, high charge / discharge efficiency, and rate characteristics by being mounted in a secondary battery in which a non-aqueous electrolyte is used.　A nickel composite hydroxide that is a precursor of a positive electrode active material of a non-aqueous electrolyte secondary battery, the nickel composite hydroxide containing Ni, Co, and one or more additive metal elements M selected from the group consisting of Mn, Al, Fe, and Ti, wherein the value of β / α in the nickel composite hydroxide, which has a secondary particle size equal to or greater than the 90 vol% secondary particle size (D90) by cumulative volume percentage, is 13.0 or lower, where α is the peak intensity of the diffraction peak that appears in the 2θ = 8.0 ± 2.0° range in powder X-ray diffraction measurement using CuK α rays, and β is the peak intensity of the diffraction peak that appears in the 2θ = 19.0 ± 2.0° range in powder X-ray diffraction measurement using CuK α rays.

Description

Technical Field

[0001] The present invention relates to a nickel composite hydroxide, a positive electrode active material using the nickel composite hydroxide as a precursor, and a method for producing these. In particular, the present invention relates to a nickel composite hydroxide, a positive electrode active material using the nickel composite hydroxide as a precursor, and a method for producing these, which can obtain a non-aqueous electrolyte secondary battery excellent in discharge capacity, charge-discharge efficiency, and rate characteristics.

Background Art

[0002] In recent years, from the viewpoint of reducing environmental load, secondary batteries have been used in a wide range of fields such as portable devices and vehicles that use or use electricity as a power source. Examples of secondary batteries include secondary batteries using a non-aqueous electrolyte such as a lithium ion secondary battery. A secondary battery using a non-aqueous electrolyte such as a lithium ion secondary battery is suitable for miniaturization and weight reduction and has excellent characteristics such as high utilization rate.

[0003] In addition to the above-mentioned various characteristics, secondary batteries are also required to exhibit high capacity, high charge-discharge efficiency, rate characteristics, and excellent cycle characteristics in repeated charge and discharge. Therefore, as a positive electrode active material of a lithium ion secondary battery that exhibits excellent cycle characteristics, for example, lithium manganese composite oxide particles having a crystal structure of α-type MnO2 have been proposed (Patent Document 1).

[0004] In Patent Document 1, although the cycle characteristics are improved due to the high lithiation rate, there is room for improvement in terms of high discharge capacity, charge-discharge efficiency, and rate characteristics.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In view of the above circumstances, the present invention provides a precursor of a positive electrode active material, a positive electrode active material obtained from the precursor, and a method for producing the precursor and the positive electrode active material, which can exhibit high discharge capacity, high charge-discharge efficiency, and rate characteristics when mounted on a secondary battery using a non-aqueous electrolyte.

Means for Solving the Problems

[0007] The gist of the configuration of the present invention is as follows. [1] A nickel composite hydroxide which is a precursor of a positive electrode active material of a non-aqueous electrolyte secondary battery, comprising Ni, Co, and at least one additive metal element M selected from the group consisting of Mn, Al, Fe, and Ti. The nickel composite hydroxide having a secondary particle diameter of 90% by volume cumulative volume percentage (D90) or more, wherein the peak intensity of the diffraction peak appearing in the range of 2θ = 8.0 ± 2.0° in the powder X-ray diffraction measurement using CuKα rays is α, and the peak intensity of the diffraction peak appearing in the range of 2θ = 19.0 ± 2.0° in the powder X-ray diffraction measurement using CuKα rays is β. The nickel composite hydroxide in which the value of β / α is 13.0 or less. [2] The nickel composite hydroxide according to [1], having a tap density of 1.50 g / ml or more and 1.90 g / ml or less. [3] The BET specific surface area is 30 m 2 / g or more and 60 m 2 / g or less. The nickel composite hydroxide according to [1] or [2]. [4] The molar ratio of Ni:Co:M is 1-x-y:x:y (where 0 < x ≦ 0.2 and 0 < y ≦ 0.1). The nickel composite hydroxide according to any one of [1] to [3]. [5] A positive electrode active material of a non-aqueous electrolyte secondary battery, in which the nickel composite hydroxide according to any one of [1] to [4] is fired with a lithium compound. A method for producing a nickel composite hydroxide, which is a precursor of a positive electrode active material of a non-aqueous electrolyte secondary battery, comprising Ni and at least one additive metal element M selected from the group consisting of Co, Mn, Al, Fe, and Ti. A neutralization reaction step in which an aqueous solution containing at least a Ni salt, a Co salt, and a salt of the additive metal element and a pH adjuster are mixed with an aqueous solution containing an ammonium ion donor in a reaction vessel, and a coprecipitation reaction is carried out in the mixed solution to obtain a crude nickel composite hydroxide. In the neutralization reaction step, the ammonia concentration of the mixed solution and the pH based on a liquid temperature of 40 ° C are controlled such that the value of β´ / α´ is 13.0 or less, where α´ is the peak intensity of the diffraction peak appearing in the range of 2θ = 8.0 ± 2.0 ° in the powder X-ray diffraction measurement using CuKα rays, and β´ is the peak intensity of the diffraction peak appearing in the range of 2θ = 19.0 ± 2.0 ° in the powder X-ray diffraction measurement using CuKα rays. A solid-liquid separation step in which the crude nickel composite hydroxide obtained in the neutralization reaction step is washed with an alkaline aqueous solution and then solid-liquid separated to obtain the nickel composite hydroxide. A method for producing a nickel composite hydroxide, comprising the above steps. [7] The molar ratio of Ni:Co:M is 1-x-y:x:y (meaning 0 < x ≤ 0.2, 0 < y ≤ 0.1). The method for producing a nickel composite hydroxide according to [6]. [8] The method for producing a nickel composite hydroxide according to [6] or [7], wherein the ammonia concentration is less than 12.0 g / L and the pH based on a liquid temperature of 40 ° C is 11.0 or more and 12.5 or less. [9] The method for producing a nickel composite hydroxide according to any one of [6] to [8], wherein in the solid-liquid separation step, after the solid-liquid separation, the solid phase is washed with water.

[10] The method for producing a nickel composite hydroxide according to any one of [6] to [9], further comprising a drying step of drying the nickel composite hydroxide after the solid-liquid separation step.

[11] A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, which uses a nickel composite hydroxide containing Ni, Co, and at least one additive metal element M selected from the group consisting of Mn, Al, Fe, and Ti as a precursor, A neutralization reaction step in which an aqueous solution containing at least a Ni salt and a Co salt, an aqueous solution containing a salt of the additive metal element, an aqueous solution containing an ammonium ion donor, and a pH adjuster are mixed in a reaction vessel, and a coprecipitation reaction is carried out in the mixed solution to obtain a crude nickel composite hydroxide. In the powder X-ray diffraction measurement of the crude nickel composite hydroxide using CuKα radiation, when the peak intensity of the diffraction peak appearing in the range of 2θ = 8.0 ± 2.0° is α´ and the peak intensity of the diffraction peak appearing in the range of 2θ = 19.0 ± 2.0° is β´, the ammonia concentration of the mixed solution and the pH based on a liquid temperature of 40 °C are controlled so that the value of β´ / α´ is 13.0 or less. A solid-liquid separation step in which the crude nickel composite hydroxide obtained in the neutralization reaction step is washed with an alkaline aqueous solution and then solid-liquid separated to obtain the nickel composite hydroxide. A step of adding a lithium compound to the obtained nickel composite hydroxide to obtain a mixture of the lithium compound and the nickel composite hydroxide, or a step of subjecting the obtained nickel composite hydroxide to an oxidation treatment to prepare a nickel composite oxide, and then adding a lithium compound to obtain a mixture of the lithium compound and the nickel composite oxide. A step of firing the mixture. A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising the above steps.

[12] A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising a step of adding a nickel composite hydroxide and a lithium compound according to any one of [1] to [4] to obtain a mixture, or a step of subjecting the nickel composite hydroxide according to any one of [1] to [4] to an oxidation treatment to prepare a nickel composite oxide, then adding a lithium compound to obtain a mixture of the lithium compound and the nickel composite oxide, and a step of firing the mixture. [Effect of the Invention]

[0008] According to an aspect of the present invention, in the powder X-ray diffraction measurement using CuKα rays of nickel composite hydroxide having a secondary particle diameter (D90) of 90% by volume or more of the cumulative volume percentage, when the peak intensity of the diffraction peak appearing in the range of 2θ = 8.0 ± 2.0° is α, and the peak intensity of the diffraction peak appearing in the range of 2θ = 19.0 ± 2.0° is β, by the value of β / α being 13.0 or less, by mounting a positive electrode active material using this nickel composite hydroxide as a precursor in a secondary battery, high discharge capacity, high charge-discharge efficiency, and rate characteristics can be exhibited.

[0009] According to an aspect of the present invention, by the tap density being 1.50 g / ml or more and 1.90 g / ml or less, the filling degree of the positive electrode active material into the positive electrode and the contact property with the non-aqueous electrolyte can be improved in a well-balanced manner.

[0010] According to an aspect of the present invention, by the BET specific surface area being 30 m 2 / g or more and 60 m 2 / g or less, while ensuring the filling degree of the positive electrode active material into the positive electrode and the contact surface with the non-aqueous electrolyte, the crushing strength of the positive electrode active material can be improved.

[0011] According to an aspect of the present invention, in the neutralization reaction step, by adjusting the ammonia concentration to less than 12.0 g / L and the pH based on a liquid temperature of 40°C to 11.0 or more and 12.5 or less, surely, the value of β' / α' of the crude nickel composite hydroxide can be controlled to 13.0 or less, and as a result, the value of β / α of the nickel composite hydroxide having a secondary particle diameter (D90) of 90% by volume or more of the cumulative volume percentage can be controlled to 13.0 or less. By mounting a positive electrode active material using the nickel composite hydroxide as a precursor in a secondary battery, surely, high discharge capacity, high charge-discharge efficiency, and rate characteristics can be exhibited.

Brief Description of the Drawings

[0012]

Figure 1

Mode for Carrying Out the Invention

[0013] Hereinafter, the nickel composite hydroxide, which is a precursor of the positive electrode active material of the non-aqueous electrolyte secondary battery of the present invention, will be described in detail. The nickel composite hydroxide, which is a precursor of the positive electrode active material of the non-aqueous electrolyte secondary battery of the present invention (hereinafter, may be simply referred to as "the nickel composite hydroxide of the present invention"), contains nickel (Ni), cobalt (Co), and one or more additive metal elements (M) selected from the group consisting of manganese (Mn), aluminum (Al), iron (Fe), and titanium (Ti). That is, the nickel composite hydroxide of the present invention contains Ni and Co as essential metal components, and further contains one or more metal elements among Mn, Al, Fe, and Ti as the additive metal element (M). By adding the additive element (M), the value of β / α can be made 13.0 or less, and by mounting a positive electrode active material using this nickel composite hydroxide as a precursor in a secondary battery, high discharge capacity, high charge-discharge efficiency, and rate characteristics can be exhibited.

[0014] The nickel composite hydroxide of the present invention is secondary particles formed by aggregation of a plurality of primary particles. The particle shape of the nickel composite hydroxide of the present invention is not particularly limited and has a variety of shapes, and examples thereof include a substantially spherical shape and a substantially elliptical shape.

[0015] Regarding the nickel composite hydroxide of the present invention, for the nickel composite hydroxide having a secondary particle diameter with a cumulative volume percentage of 90% by volume or more (hereinafter sometimes simply referred to as "D90"), when the peak intensity of the diffraction peak appearing in the range of 2θ = 8.0 ± 2.0° in the powder X-ray diffraction measurement using CuKα rays is α, and the peak intensity of the diffraction peak appearing in the range of 2θ = 19.0 ± 2.0° in the powder X-ray diffraction measurement using CuKα rays is β, the value of β / α is controlled to be 13.0 or less. By controlling the value of β / α to be 13.0 or less and mounting a positive electrode active material using the nickel composite hydroxide of the present invention as a precursor in a secondary battery, the secondary battery can exhibit a high discharge capacity, high charge-discharge efficiency, and rate characteristics.

[0016] As long as the value of β / α is controlled to be 13.0 or less, its upper limit value is not particularly limited. However, from the viewpoint of further improving the discharge capacity, charge-discharge efficiency, and rate characteristics, it is more preferably 11.0 or less, and particularly preferably 9.0 or less. On the other hand, the lower limit value of the value of β / α is preferably 3.0 or more, for example, from the viewpoint of preventing the incorporation of impurities. The above-mentioned upper limit value and lower limit value can be arbitrarily combined.

[0017] In the nickel composite hydroxide of the present invention, the molar ratio of Ni:Co:M is not particularly limited and can be appropriately selected according to the usage conditions of the positive electrode active material obtained from the nickel composite hydroxide and the like. Examples of the molar ratio of Ni:Co:M include 1 - x - y:x:y (where 0 < x ≤ 0.2 and 0 < y ≤ 0.1).

[0018] As the added metal element, it is preferably included Al and Mn, and particularly preferably Al, in that it is easy to control the value of β / α to be 13.0 or less.

[0019] The tap density (TD) of the nickel composite hydroxide of the present invention is not particularly limited. For example, the lower limit value is preferably 1.50 g / ml or more, particularly preferably 1.60 g / ml or more, from the viewpoint of improving the filling degree of the positive electrode active material into the positive electrode. On the other hand, the upper limit value of the tap density of the nickel composite hydroxide of the present invention is preferably 1.90 g / ml or less, particularly preferably 1.80 g / ml or less, from the viewpoint of improving the contact property between the positive electrode active material and the non-aqueous electrolyte. It should be noted that the above upper limit value and lower limit value can be arbitrarily combined.

[0020] The BET specific surface area of the nickel composite hydroxide of the present invention is not particularly limited. For example, the lower limit value is preferably 30 m 2 / g or more, particularly preferably 35 m 2 / g or more, from the viewpoint of improving the filling degree of the positive electrode active material into the positive electrode and the contact area with the non-aqueous electrolyte. On the other hand, the upper limit value of the BET specific surface area of the nickel composite hydroxide of the present invention is preferably 60 m 2 / g or less, particularly preferably 50 m 2 / g or less, from the viewpoint of improving the crushing strength of the positive electrode active material. It should be noted that the above upper limit value and lower limit value can be arbitrarily combined.

[0021] The particle size of the nickel composite hydroxide of the present invention is not particularly limited. For example, the lower limit of the secondary particle size (hereinafter sometimes simply referred to as "D50") with a cumulative volume percentage of 50% by volume is preferably 5.0 μm or more, particularly preferably 8.0 μm or more, from the viewpoint of improving the density. On the other hand, the upper limit of D50 of the nickel composite hydroxide of the present invention is preferably 25.0 μm or less, particularly preferably 20.0 μm or less, from the viewpoint of improving the contact property with the non-aqueous electrolyte. Note that the above upper and lower limits can be arbitrarily combined. Further, the lower limit of D90 of the nickel composite hydroxide of the present invention is preferably 10.0 μm or more, particularly preferably 15.0 μm or more, from the viewpoint of improving the density. On the other hand, the upper limit of D90 of the nickel composite hydroxide of the present invention is preferably 40.0 μm or less, particularly preferably 35.0 μm or less, from the viewpoint of improving the contact property with the non-aqueous electrolyte. Note that the above upper and lower limits can be arbitrarily combined. Also, the lower limit of the secondary particle size (hereinafter sometimes simply referred to as "D10") with a cumulative volume percentage of 10% by volume of the nickel composite hydroxide of the present invention is preferably 1.0 μm or more, particularly preferably 5.0 μm or more, from the viewpoint of improving the density. On the other hand, the upper limit of D10 of the nickel composite hydroxide of the present invention is preferably 15.0 μm or less, particularly preferably 10.0 μm or less, from the viewpoint of improving the contact property with the non-aqueous electrolyte. Note that the above upper and lower limits can be arbitrarily combined. Note that D10, D50, and D90 mean the particle sizes measured by a particle size distribution measuring device using the laser diffraction / scattering method.

[0022] Also, the particle size distribution width of the nickel composite hydroxide of the present invention is not particularly limited. However, the lower limit of (D90 - D10) / D50 is preferably 0.40 or more, particularly preferably 0.70 or more, from the viewpoint of improving the loading density of the positive electrode active material. On the other hand, the upper limit of (D90 - D10) / D50 of the nickel composite hydroxide of the present invention is preferably 1.10 or less, particularly preferably 1.00 or less, from the viewpoint of homogenizing the various properties of the positive electrode active material regardless of the particle size of the nickel composite hydroxide. Note that the above upper and lower limits can be arbitrarily combined.

[0023] Next, the method for producing the nickel composite hydroxide of the present invention will be described. First, by the coprecipitation method, a solution containing a nickel salt (for example, sulfate), a cobalt salt (for example, sulfate), and a salt of an additive metal element (for example, sulfate), a complexing agent, and a pH adjuster are appropriately added to cause a neutralization reaction in a reaction tank to prepare a crude nickel composite hydroxide and obtain a slurry-like suspension containing the crude nickel composite hydroxide. As the solvent of the suspension, for example, water is used. Further, as the form of the crude nickel composite hydroxide, particulate form can be mentioned.

[0024] The complexing agent is not particularly limited as long as it can form a complex with ions of nickel, cobalt, and the additive metal element in an aqueous solution. For example, an ammonium ion donor can be mentioned. Examples of the ammonium ion donor include aqueous ammonia, ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium fluoride, and the like. In addition, during the neutralization reaction, an alkali metal hydroxide (for example, sodium hydroxide, potassium hydroxide) may be added as a pH adjuster as necessary to adjust the pH value of the aqueous solution.

[0025] A metal salt solution containing nickel, cobalt, and an added metal element, a pH adjuster, and an ammonium ion supplier are appropriately and continuously supplied to a reaction tank. When the substances in the reaction tank are appropriately stirred, the metals (nickel, cobalt, added metal element) in the metal salt solution undergo a coprecipitation reaction, and a crude nickel composite hydroxide is prepared. During the coprecipitation reaction, the temperature of the reaction tank is controlled within a range of, for example, 10°C to 80°C, preferably 20°C to 70°C. When the pH adjuster and the ammonium ion supplier are supplied to the reaction tank to cause the coprecipitation reaction, by controlling the ammonia concentration in the mixed solution in the reaction tank and the pH based on a liquid temperature of 40°C within a predetermined range, the value of β´ / α´ of the crude nickel composite hydroxide can be controlled to be 13.0 or less. By controlling the value of β´ / α´ of the crude nickel composite hydroxide to be 13.0 or less, it becomes easy to control the value of β / α of the purified nickel composite hydroxide, which will be described later, to be 13.0 or less and D90 or more. The preferable range of the ammonia concentration and the pH based on a liquid temperature of 40°C may need to be adjusted according to the component composition of the crude nickel composite hydroxide. For example, the ammonia concentration is preferably less than 12.0 g / L, and particularly preferably 7.0 g / L or more and 11.0 g / L or less. Also, the pH based on a liquid temperature of 40°C is preferably 11.0 or more and 12.5 or less, and particularly preferably 11.5 or more and 12.3 or less.

[0026] Examples of the reaction tank used in the method for producing the nickel composite hydroxide of the present invention include a continuous type in which the obtained crude nickel composite hydroxide is overflowed for separation and a batch type in which it is not discharged out of the system until the reaction is completed.

[0027] As described above, after the crude nickel composite hydroxide obtained in the neutralization reaction step is filtered from the suspension, it is washed with an alkaline aqueous solution to remove impurities contained in the crude nickel composite hydroxide, and a purified nickel composite hydroxide (the nickel composite hydroxide of the present invention) is obtained. Then, after solid-liquid separation, if necessary, the solid phase containing the nickel composite hydroxide is washed with water, and the nickel composite hydroxide is heat-treated and dried to obtain a powdery nickel composite hydroxide.

[0028] Next, the positive electrode active material of the non-aqueous electrolyte secondary battery using the nickel composite hydroxide of the present invention as a precursor (hereinafter, may be simply referred to as "the positive electrode active material of the present invention") will be described. The positive electrode active material of the present invention is in a state where the nickel composite hydroxide of the present invention as a precursor is fired with, for example, a lithium compound. The crystal structure of the positive electrode active material of the present invention is a layered structure, and from the viewpoint of obtaining a secondary battery with a high discharge capacity, it is more preferably a hexagonal crystal structure or a monoclinic crystal structure. The positive electrode active material of the present invention can be used, for example, as a positive electrode active material of a lithium ion secondary battery. When manufacturing the positive electrode active material of the present invention, a step of preparing a nickel composite hydroxide into a nickel composite oxide in advance may be carried out. Examples of the method for preparing a nickel composite oxide from a nickel composite hydroxide include an oxidation treatment of firing in an atmosphere where oxygen gas is present at a temperature of 300°C or higher and 800°C or lower for 1 hour or more and 10 hours or less.

[0029] Next, the manufacturing method of the positive electrode active material of the present invention will be described. For example, the manufacturing method of the positive electrode active material of the present invention first adds a lithium compound to a nickel composite hydroxide or a nickel composite oxide to prepare a mixture of the nickel composite hydroxide or the nickel composite oxide and the lithium compound. The lithium compound is not particularly limited as long as it is a compound containing lithium, and examples thereof include lithium carbonate and lithium hydroxide.

[0030] Next, the positive electrode active material can be manufactured by firing the obtained mixture. Examples of the firing conditions include a firing temperature of 700°C or higher and 1000°C or lower, a heating rate of 50°C / h or higher and 300°C / h or lower, and a firing time of 5 hours or more and 20 hours or less. The firing atmosphere is not particularly limited, and examples thereof include air and oxygen. Also, the firing furnace used for firing is not particularly limited, and examples thereof include a stationary box furnace and a roller hearth continuous furnace.

[0031] Incidentally, the fired product obtained as described above may be washed. For washing, pure water or an alkaline cleaning solution can be used. Examples of the alkaline cleaning solution include aqueous solutions of one or more anhydrides selected from the group consisting of LiOH (lithium hydroxide), NaOH (sodium hydroxide), KOH (potassium hydroxide), Li2CO3 (lithium carbonate), Na2CO3 (sodium carbonate), K2CO3 (potassium carbonate), and (NH4)2CO3 (ammonium carbonate) and their hydrates. Also, ammonia can be used as the alkaline cleaning solution.

[0032] In the washing step, as a method of bringing the cleaning solution into contact with the fired product, for example, a method of putting the fired product into an aqueous solution of each cleaning solution and stirring, a method of using the aqueous solution of each cleaning solution as shower water and spraying it on the fired product, a method of putting the fired product into the aqueous solution of the cleaning solution, stirring, separating the fired product from the aqueous solution of each cleaning solution, and then using the aqueous solution of each cleaning solution as shower water and spraying it on the separated fired product can be mentioned.

[0033] When performing the above washing, after washing, the washed product is separated from the cleaning solution by filtration or the like, and heat treatment is performed. Examples of the heat treatment conditions include a heat treatment temperature of 100°C or higher and 600°C or lower, and a heat treatment time of 1 hour or longer and 20 hours or shorter. The atmosphere for the heat treatment is not particularly limited, and examples include air, oxygen, and a vacuum atmosphere.

[0034] Next, the positive electrode using the positive electrode active material of the present invention will be described. The positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the surface of the positive electrode current collector and using the positive electrode active material of the present invention. The positive electrode active material layer contains the positive electrode active material of the present invention, a binder, and, if necessary, a conductive assistant. The conductive assistant is not particularly limited as long as it can be used for a non-aqueous electrolyte secondary battery, and a carbon material can be used. Examples of the carbon material include graphite powder, carbon black (e.g., acetylene black), and fibrous carbon materials. The binder is not particularly limited, but examples include polymer resins such as polyvinylidene fluoride (PVdF), butadiene rubber (BR), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), polytetrafluoroethylene (PTFE), and combinations thereof. The positive electrode current collector is not particularly limited, but a strip-shaped member formed of a metal material such as Al, Ni, or stainless steel can be used. Among them, Al is used as the forming material and processed into a thin film shape because it is easy to process and inexpensive.

[0035] As a method for manufacturing the positive electrode, for example, first, the positive electrode active material of the present invention, the conductive assistant, and the binder are mixed to prepare a positive electrode active material slurry. Next, the positive electrode active material slurry is applied to the positive electrode current collector by a known filling method, dried, pressed, and fixed to obtain a positive electrode.

[0036] By mounting a positive electrode using the positive electrode active material obtained as described above, a negative electrode including a negative electrode current collector and a negative electrode active material layer formed on the surface of the negative electrode current collector and containing a negative electrode active material, an electrolytic solution containing a predetermined electrolyte, and a separator by a known method, a non-aqueous electrolyte secondary battery can be assembled.

[0037] Examples of the electrolyte contained in the electrolytic solution include LiClO4, LiPF6, LiAsF6, LiSbF6, LiBF4, LiCF3SO3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(COCF3), Li(C4F9SO3), LiC(SO2CF3)3, Li2B 10 Cl10 , lithium salts such as LiBOB (where BOB is bis(oxalato)borate), LiFSI (where FSI is bis(fluorosulfonyl)imide), lithium lower aliphatic carboxylate salts, and LiAlCl4 can be mentioned. These can be used alone or in combination of two or more.

[0038] Also, as the dispersion medium of the electrolyte contained in the electrolytic solution, for example, carbonates such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one, 1,2-di(methoxycarbonyloxy)ethane; ethers such as 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropyl methyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran; esters such as methyl formate, methyl acetate, γ-butyrolactone; nitriles such as acetonitrile, butyronitrile; amides such as N,N-dimethylformamide, N,N-dimethylacetamide; carbamates such as 3-methyl-2-oxazolidone; sulfur-containing compounds such as sulfolane, dimethyl sulfoxide, 1,3-propane sultone, or those obtained by further introducing a fluoro group into these organic solvents (substituting one or more of the hydrogen atoms of the organic solvent with fluorine atoms) can be used. These can be used alone or in combination of two or more.

[0039] Alternatively, a solid electrolyte may be used instead of the above electrolytic solution. As the solid electrolyte, for example, an organic polymer electrolyte such as a polyethylene oxide-based polymer compound, a polymer compound containing at least one of a polyorganosiloxane chain or a polyoxyalkylene chain can be used. Also, a so-called gel type in which a non-aqueous electrolyte is held in a polymer compound can be used. Further, inorganic solid electrolytes containing sulfides such as Li2S-SiS2, Li2S-GeS2, Li2S-P2S5, Li2S-B2S3, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li2SO4, Li2S-GeS2-P2S5 can be mentioned. These may be used alone or in combination of two or more.

[0040] Examples of the separator include materials having forms such as porous membranes, non-woven fabrics, and woven fabrics made of materials such as polyolefin resins such as polyethylene and polypropylene, fluororesins, and nitrogen-containing aromatic polymers.

Examples

[0041] Next, examples of the nickel composite hydroxide of the present invention will be described, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

[0042] Production of nickel composite hydroxides in Examples and Comparative Examples Production of nickel composite hydroxide of Example 1 An aqueous solution in which nickel sulfate, cobalt sulfate, and aluminum sulfate are dissolved at a predetermined ratio, an aqueous ammonium sulfate solution (ammonium ion donor), and an aqueous sodium hydroxide solution were dropped into a reaction vessel, and the pH of the mixed solution in the reaction vessel was adjusted to 12.1 based on a liquid temperature of 40 °C, and the ammonia concentration was maintained at 9.5 g / L while continuously stirring with a stirrer. Also, the liquid temperature of the mixed solution in the reaction vessel was maintained at 40.0 °C. The crude nickel composite hydroxide produced by the neutralization reaction was retained in the reaction vessel for 10.2 hours, then overflowed from the overflow pipe of the reaction vessel, and taken out as a suspension. After filtering a part of the suspension, it was washed with pure water, subjected to solid-liquid separation, and dried to perform powder X-ray diffraction measurement of the above crude nickel composite hydroxide. At this point, it was confirmed that β´ / α´ of the above crude nickel composite hydroxide was 13.0 or less. The taken-out suspension of the crude nickel composite hydroxide was washed with an alkaline aqueous solution (8 mass% aqueous sodium hydroxide solution) after filtering, and subjected to solid-liquid separation. Then, the separated solid phase was washed with water, and further subjected to dehydration and drying treatments to obtain a powdered purified nickel composite hydroxide.

[0043] Production of Nickel Composite Hydroxide of Example 2 A powdered purified nickel composite hydroxide was obtained in the same manner as in Example 1, except that the ratios of nickel sulfate, cobalt sulfate, and aluminum sulfate were changed, and the pH of the mixed solution in the reaction vessel was maintained at 12.0 based on a liquid temperature of 40 °C and the ammonia concentration was maintained at 9.0 g / L.

[0044] Production of Nickel Composite Hydroxide of Comparative Example A powdered purified nickel composite hydroxide was obtained in the same manner as in Examples 1 and 2, except that the pH of the mixed solution in the reaction vessel was maintained at 12.7 based on a liquid temperature of 40 °C and the ammonia concentration was maintained at 12.0 g / L, and it was confirmed that β´ / α´ of the crude nickel composite hydroxide at the time of taking it out as a suspension was greater than 13.0.

[0045] The neutralization reaction conditions of the nickel composite hydroxides of Examples 1 and 2 and the comparative example are shown in Table 1 below.

[0046] The evaluation items of the physical properties of the nickel composite hydroxide in Examples 1 and 2 and the comparative example are as follows. (1) Composition analysis of nickel composite hydroxide For the composition analysis, after dissolving the obtained nickel composite hydroxide in hydrochloric acid, it was performed using an inductively coupled plasma optical emission spectrometer (manufactured by PerkinElmer Japan Co., Ltd., Optima 7300DV).

[0047] (2) D50, D90, D10 It was measured with a particle size distribution measuring device (manufactured by Horiba, Ltd., LA-950) (the principle is the laser diffraction / scattering method).

[0048] (3) Tap density Using a tap densitometer (manufactured by Seishin Co., Ltd., KYT-4000), the tap density was measured by the constant volume measurement method among the methods described in JIS R1628.

[0049] (4) BET specific surface area After drying 1 g of the nickel composite hydroxide in a nitrogen atmosphere at 105 °C for 30 minutes, it was measured by the one-point BET method using a specific surface area measuring device (manufactured by Mountech Co., Ltd., Macsorb).

[0050] The evaluation results of the physical properties of the nickel composite hydroxide in Examples 1 and 2 and the comparative example are shown in Table 1 below.

[0051]

Table 1

[0052] Peak intensity of the diffraction peak of the nickel composite hydroxide having a secondary particle diameter of D90 or more Of the nickel composite hydroxides of Examples 1 and 2 and the Comparative Example, nickel composite hydroxides having a secondary particle diameter of D90 or more were separated by air classification. The separated nickel composite hydroxides having a secondary particle diameter of D90 or more had D90 of 20.1 μm in Example 1, 22.5 μm in Example 2, and 22.6 μm in the Comparative Example, which were larger values than the D90 of the nickel composite hydroxide before separation. For the nickel composite hydroxides having a secondary particle diameter of D90 or more, the peak intensity of the diffraction peak appearing in the range of 2θ = 8.0 ± 2.0° in powder X-ray diffraction measurement using CuKα radiation, and the peak intensity of the diffraction peak appearing in the range of 2θ = 19.0 ± 2.0° in powder X-ray diffraction measurement using CuKα radiation were measured. Specifically, the powder X-ray diffraction measurement was performed using an X-ray diffractometer (Ultima IV, manufactured by Rigaku Corporation). A nickel composite hydroxide powder with a secondary particle diameter of D90 or more was packed onto a dedicated substrate, and measurements were performed using a Cu-Kα source (40 kV / 40 mA) under conditions of a diffraction angle 2θ = 5° to 80°, a sampling width of 0.03°, and a scan speed of 20° / min to obtain a powder X-ray diffraction pattern. Smoothing and background removal were performed using the integrated powder X-ray analysis software PDXL, and the peak intensity α of the diffraction peak appearing in the range of 8.0 ± 2.0° and the peak intensity β of the diffraction peak appearing in the range of 19.0 ± 2.0° were measured from the powder X-ray diffraction pattern, and the peak intensity ratio β / α was calculated.

[0053] The powder X-ray diffraction patterns of the nickel composite hydroxides having a secondary particle diameter of D90 or more of Example 1 and the comparative example are shown in FIG. 1 (in FIG. 1, they are respectively indicated as "Example 1" and "Comparative Example"), and the peak intensity α, peak intensity β, and peak intensity ratio β / α of Examples 1 and 2 and the comparative example are shown in Table 2 below.

[0054] [Table 2]

[0055] Production of positive electrode active material using nickel composite hydroxides of Examples and Comparative Examples as precursors Of the nickel composite hydroxides of Examples 1 and 2 and the comparative example, the nickel composite hydroxides of Example 1 and the comparative example were used to produce a positive electrode active material. When producing the positive electrode active material, a step of oxidizing the nickel composite hydroxide to prepare a nickel composite oxide was previously carried out. The oxidation treatment involved firing in an air atmosphere at a temperature of 690°C for 5 hours to prepare the nickel composite oxides of Example 1 and the comparative example. Thereafter, lithium hydroxide powder was added to and mixed with the nickel composite oxides of Example 1 and the comparative example so that the molar ratio of Li / (Ni+Co+Al) was 1.07, thereby obtaining a mixed powder of nickel composite hydroxide and lithium hydroxide. The obtained mixed powder was subjected to a firing treatment to obtain lithium metal composite oxide particles. The firing conditions were an oxygen atmosphere, a firing temperature of 700°C, a temperature rise rate of 200°C / h, and a firing time of 6 hours. A box furnace was used for firing.

[0056] The lithium metal composite oxide particles obtained as described above were washed with water by adding the lithium metal composite oxide to pure water, stirring the resulting slurry for 10 minutes, and dehydrating it.

[0057] Thereafter, the wet cake obtained by the above washing was subjected to a heat treatment at 150° C. for 12 hours in a vacuum atmosphere to obtain a positive electrode active material.

[0058] A positive electrode plate was prepared using the positive electrode active material obtained as described above, and a test battery was assembled using the prepared positive electrode plate. Specifically, the obtained positive electrode active material, a conductive agent (acetylene black), and a binder (polyvinylidene fluoride) were mixed in a weight ratio of 92:5:3, respectively, and N-methyl-2-pyrrolidone was added and kneaded to prepare a slurry. The obtained slurry was applied to aluminum foil using a Baker-type applicator and dried at 60°C for 3 hours and at 150°C for 12 hours. The dried electrode was roll-pressed and cut into 1.65 cm 2 The plate was punched out to an area of 100 mm to form a positive electrode plate.

[0059] In addition, the evaluation battery was fabricated as follows. The positive electrode plate obtained as described above was placed with the aluminum foil side facing down on the lower lid of the parts for a coin-type battery R2032 (manufactured by Hokuen Co., Ltd.), and a laminated film separator (a heat-resistant porous layer laminated on a porous polyethylene film (thickness 16 μm)) was placed thereon. 300 μl of an electrolytic solution was injected here. The electrolytic solution used was a solution in which LiPF6 was dissolved to a concentration of 1 mol / l in a 30:35:35 (volume ratio) mixture of ethylene carbonate (hereinafter sometimes referred to as EC), dimethyl carbonate (hereinafter sometimes referred to as DMC), and ethyl methyl carbonate (hereinafter sometimes referred to as EMC) (hereinafter sometimes referred to as LiPF6 / EC + DMC + EMC). Using lithium metal as the negative electrode, the negative electrode was placed on the upper side of the laminated film separator, the upper lid was attached via a gasket, and it was caulked with a caulking machine to fabricate a lithium secondary battery (coin-type battery R2032).

[0060] Evaluation Items of the Battery (1) Discharge Capacity Charge and discharge were performed under the following conditions, and the discharge capacity of the first charge and discharge was defined as the discharge capacity. The discharge capacity was evaluated at a ratio with the example set as 100. Test Temperature: 25°C Maximum Charge Voltage 4.3V, Charge Current 0.2C, Constant Current and Constant Voltage Charging Minimum Discharge Voltage 2.5V, Discharge Current 0.2C, Constant Current Discharge (2) Charge and Discharge Efficiency The charge and discharge efficiency was defined as the ratio of the first discharge capacity to the first charge capacity in the above charge and discharge test. The charge and discharge efficiency was evaluated at a ratio with the example set as 100. (3) Rate Performance For the rate performance, 1.0C was set to 200 mAh / g, charge and discharge were performed under the following conditions, and the discharge capacity at 3.0C was defined as the rate performance. The rate performance was evaluated at a ratio with the example set as 100. Test Temperature: 25°C Maximum Charge Voltage 4.3V, Charge Current 1.0C, Constant Current and Constant Voltage Charging Minimum Discharge Voltage 2.5V, Discharge Current 3.0C, Constant Current Discharge

[0061] The battery evaluation results are shown in Table 3 below.

[0062] [Table 3]

[0063] As can be seen from Tables 2 and 3, in Example 1, in which a positive electrode active material was prepared using a precursor having a peak intensity ratio (β / α) of 7.2, excellent discharge capacity, charge / discharge efficiency, and rate characteristics were obtained. Note that, as can be seen from Table 1, in Example 1, the tap density of the precursor was 1.75 g / ml and the BET specific surface area was 44 m 2 / g. In addition, it was found that in Example 2, in which the peak intensity ratio (β / α) was 9.8 and the peak intensity ratio (β / α) was 13.0 or less, similar to Example 1, excellent discharge capacity, charge / discharge efficiency, and rate characteristics could be obtained, similar to Example 1. Note that, from Table 1, in Example 2, the tap density of the precursor was 1.69 g / ml and the BET specific surface area was 50 m 2 / g. On the other hand, in the Comparative Example in which a positive electrode active material was produced using a precursor with a peak intensity ratio (β / α) of 14.9, as shown in Tables 2 and 3, the discharge capacity, charge / discharge efficiency, and rate characteristics all decreased compared to Example 1. Note that, as shown in Table 1, the tap density of the precursor in the Comparative Example was 1.98 g / ml and the BET specific surface area was 28 m 2 / g. [Industrial Applicability]

[0064] The nickel composite hydroxide of the present invention can be used as a precursor of a positive electrode active material, which can provide a positive electrode active material that can exhibit high discharge capacity, high charge / discharge efficiency, and rate characteristics by being installed in a secondary battery that uses a non-aqueous electrolyte, and therefore can be used in a wide range of fields, such as portable devices and vehicles.

Claims

1. A nickel composite hydroxide that is a precursor of a positive electrode active material for a non-aqueous electrolyte secondary battery, the nickel composite hydroxide comprising Ni, Co, and one or more additional metal elements M selected from the group consisting of Mn, Al, Fe, and Ti, In the nickel composite hydroxide having a secondary particle diameter equal to or greater than the secondary particle diameter (D90) at a cumulative volume percentage of 90% by volume, when the peak intensity of a diffraction peak appearing in a range of 2θ = 8.0 ± 2.0° in powder X-ray diffraction measurement using CuKα rays is defined as α, and when the peak intensity of a diffraction peak appearing in a range of 2θ = 19.0 ± 2.0° in powder X-ray diffraction measurement using CuKα rays is defined as β, the value of β / α is 7.2 or more and 9.8 or less, A nickel composite hydroxide in which the molar ratio of Ni:Co:M is 1-xy:x:y (meaning 0<x≦0.2, 0<y≦0.1).

2. 2. The nickel composite hydroxide according to claim 1, wherein (D90-D10) / D50 is 0.70 or more for a secondary particle diameter (D90) at a cumulative volume percentage of 90% by volume, a secondary particle diameter (D10) at a cumulative volume percentage of 10% by volume, and a secondary particle diameter (D50) at a cumulative volume percentage of 50% by volume.

3. The nickel composite hydroxide according to claim 1 or 2, having a tap density of 1.50 g / ml or more and 1.90 g / ml or less.

4. The BET specific surface area is 30 m ２ / g or more and 60 m ２ / g or less, and the nickel composite hydroxide according to any one of claims 1 to 3.

5. A positive electrode active material for a non-aqueous electrolyte secondary battery, comprising the nickel composite hydroxide according to claim 1 , baked with a lithium compound.

6. The method for producing the nickel composite hydroxide according to any one of claims 1 to 4, a neutralization reaction step of mixing an aqueous solution containing at least a Ni salt, a Co salt, and a salt of the added metal element, an aqueous solution containing an ammonium ion donor, and a pH adjuster in a reaction tank, and causing a coprecipitation reaction in the mixed solution to obtain a crude nickel composite hydroxide, in which the ammonia concentration and the pH at a standard solution temperature of 40°C are controlled so that the value of β' / α' is 13.0 or less, where α' is the peak intensity of a diffraction peak appearing in a range of 2θ = 8.0 ± 2.0° in powder X-ray diffraction measurement of the crude nickel composite hydroxide using CuKα rays, and β' is the peak intensity of a diffraction peak appearing in a range of 2θ = 19.0 ± 2.0° in powder X-ray diffraction measurement of the crude nickel composite hydroxide using CuKα rays; a solid-liquid separation step of washing the crude nickel composite hydroxide obtained in the neutralization reaction step with an alkaline aqueous solution and then performing solid-liquid separation to obtain the nickel composite hydroxide; A method for producing a nickel composite hydroxide, comprising:

7. 7. The method for producing a nickel composite hydroxide according to claim 6, wherein the ammonia concentration is less than 12.0 g / L, and the pH at a liquid temperature of 40°C is 11.0 or more and 12.5 or less.

8. The method for producing a nickel composite hydroxide according to claim 6 or 7, wherein, in the solid-liquid separation step, the solid phase is washed with water after the solid-liquid separation.

9. The method for producing a nickel composite hydroxide according to any one of claims 6 to 8, further comprising, after the solid-liquid separation step, a drying step of drying the nickel composite hydroxide.

10. A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery using the nickel composite hydroxide according to any one of claims 1 to 4 as a precursor, comprising: a neutralization reaction step of mixing an aqueous solution containing at least a Ni salt and a Co salt, an aqueous solution containing a salt of the added metal element, a pH adjuster, and an aqueous solution containing an ammonium ion donor in a reaction tank, and causing a coprecipitation reaction in the mixed solution to obtain a crude nickel composite hydroxide, in which the ammonia concentration and the pH at a standard solution temperature of 40°C are controlled in the mixed solution so that the value of β' / α' is 13.0 or less, where α' is the peak intensity of a diffraction peak appearing in a range of 2θ = 8.0 ± 2.0° in powder X-ray diffraction measurement of the crude nickel composite hydroxide using CuKα rays, and β' is the peak intensity of a diffraction peak appearing in a range of 2θ = 19.0 ± 2.0° in powder X-ray diffraction measurement of the crude nickel composite hydroxide using CuKα rays; a solid-liquid separation step of washing the crude nickel composite hydroxide obtained in the neutralization reaction step with an alkaline aqueous solution and then performing solid-liquid separation to obtain the nickel composite hydroxide; a step of adding a lithium compound to the obtained nickel composite hydroxide to obtain a mixture of the lithium compound and the nickel composite hydroxide, or a step of preparing a nickel composite oxide by oxidizing the obtained nickel composite hydroxide, and then adding a lithium compound to obtain a mixture of the lithium compound and the nickel composite oxide; calcining the mixture; A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising:

11. A step of adding a nickel composite hydroxide and a lithium compound according to any one of claims 1 to 4 to obtain a mixture, or a step of oxidizing the nickel composite hydroxide according to any one of claims 1 to 4 to prepare a nickel composite oxide, and then adding a lithium compound to obtain a mixture of the lithium compound and the nickel composite oxide, and a step of firing the mixture, a method for producing a positive electrode active material of a non-aqueous electrolyte secondary battery.

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