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

Abstract

Provided are a nickel composite hydroxide that makes it possible to reduce the firing temperature when producing a positive electrode active material, a positive electrode active material having the nickel composite hydroxide as a precursor, and methods for the production thereof.　In this nickel composite hydroxide, which is for a precursor of a positive electrode active material of a non-aqueous electrolyte secondary battery, the value of α / β is 0.75-0.95 (inclusive), where α is the peak intensity of the diffraction peak appearing on the (200) plane in powder X-ray diffraction measurement using CuKα rays, and β is the peak intensity of the diffraction peak appearing on the (013) plane in powder X-ray diffraction measurement using CuKα rays. The nickel composite hydroxide contains Ni, Co, Mn, and one or more additive elements M selected from the group consisting of Al, Fe, Ti, and Zr.

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 the same, and in particular to a nickel composite hydroxide that can reduce the firing temperature when producing a positive electrode active material, and a method for producing the same. [Background technology]

[0002] In recent years, in order to reduce environmental impact, secondary batteries have been used in a wide range of fields, such as portable devices and vehicles that use or combine electricity as a power source. Examples of secondary batteries include secondary batteries that use non-aqueous electrolytes, such as lithium-ion secondary batteries. Secondary batteries that use non-aqueous electrolytes, such as lithium-ion secondary batteries, are suitable for miniaturization and weight reduction, and have properties such as high utilization rate and high cycle characteristics.

[0003] On the other hand, when producing a positive electrode active material by calcining the precursor nickel composite hydroxide, it is necessary to reduce the calcination temperature as much as possible from the viewpoints of further improving various properties such as high utilization rate and high cycle characteristics, improving production efficiency, and energy conservation. In particular, nickel composite hydroxide does not have excellent reactivity with lithium compounds, so a high calcination temperature is required when calcining a mixture of nickel composite hydroxide and lithium compound to produce lithium-nickel composite oxide, which is used as a positive electrode active material in lithium-ion secondary batteries.

[0004] In order to reduce the calcination temperature, a nickel-cobalt-manganese composite oxide has been proposed in which, in an XRD pattern obtained by XRD measurement using CuKα radiation as a radiation source, the XRD peak intensity at 2θ=18.3±0.5° and the XRD peak intensity at 2θ=37.1±1.5° are equivalent, or the 18.3° peak intensity is equal to or less than the 37.1° peak intensity (Patent Document 1). In Patent Document 1, the calcination temperature is reduced by imparting a unique crystal structure having the above-mentioned peak intensities to the nickel-cobalt-manganese composite oxide.

[0005] However, with the precursor of Patent Document 1, the preferred firing temperature is still in the range of 800° C. to 1000° C., which is not significantly different from conventional firing temperatures, and there is room for improvement in reducing the firing temperature. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-139119 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above circumstances, an object of the present invention is to provide a nickel composite hydroxide that can reduce the firing temperature when producing a positive electrode active material, a positive electrode active material that uses the nickel composite hydroxide as a precursor, and methods for producing the same. [Means for solving the problem]

[0008] The gist of the configuration of the present invention is as follows. [1] In a nickel composite hydroxide, when the peak intensity of a diffraction peak of a (200) plane in powder X-ray diffraction measurement using CuKα rays is defined as α and the peak intensity of a diffraction peak of a (013) plane in powder X-ray diffraction measurement using CuKα rays is defined as β, the value of α / β is 0.75 or more and 0.95 or less, and the nickel composite hydroxide is composed of Ni, Co, Mn, duty The element of will, and one or more additional elements M selected from the group consisting of Al, Fe, Ti, and Zr. [2] In the nickel composite hydroxide, the diffraction peak of the (200) plane is a diffraction peak that appears in the range of 2θ = 69.2 ± 0.1°, and the diffraction peak of the (013) plane is a diffraction peak that appears in the range of 2θ = 70.4 ± 0.1°, and when the peak intensity of the diffraction peak that appears in the range of 2θ = 69.2 ± 0.1° in powder X-ray diffraction measurement using CuKα rays is defined as α and the peak intensity of the diffraction peak that appears in the range of 2θ = 70.4 ± 0.1° in powder X-ray diffraction measurement using CuKα rays is defined as β, the value of α / β is 0.75 or more and 0.95 or less, and the nickel composite hydroxide is composed of Ni, Co, Mn, is an optional element, and one or more additional elements M selected from the group consisting of Al, Fe, Ti, and Zr. [3] In the nickel composite hydroxide, the diffraction peak of the (200) plane is a diffraction peak that appears in the range of 2θ = 69.5 ± 0.3°, and the diffraction peak of the (013) plane is a diffraction peak that appears in the range of 2θ = 70.5 ± 0.3°, and when the peak intensity of the diffraction peak that appears in the range of 2θ = 69.5 ± 0.3° in powder X-ray diffraction measurement using CuKα rays is α and the peak intensity of the diffraction peak that appears in the range of 2θ = 70.5 ± 0.3° in powder X-ray diffraction measurement using CuKα rays is β, the value of α / β is 0.75 or more and 0.95 or less, and the nickel composite hydroxide is composed of Ni, Co, Mn, is an optional element, and one or more additional elements M selected from the group consisting of Al, Fe, Ti, and Zr. [4] The nickel composite hydroxide has a molar ratio of Ni:Co:Mn:M of 1-xyz :x:y:z(0 <x≦0.15、0<y≦0.15、0≦z≦0.05、MはAl、F The nickel composite hydroxide according to any one of [1] to [3], wherein the nickel composite hydroxide is represented by the formula (1), wherein the nickel composite hydroxide is one or more additive elements selected from the group consisting of e, Ti, and Zr. [5] The nickel composite hydroxide according to any one of [1] to [4], wherein the secondary particle diameter (D50) at a cumulative volume percentage of 50% by volume is 6.0 μm or more and 16.0 μm or less. [6] The nickel composite hydroxide according to any one of [1] to [5], wherein a value of [secondary particle diameter at a cumulative volume percentage of 90 volume% (D90) - secondary particle diameter at a cumulative volume percentage of 10 volume% (D10)] / secondary particle diameter at a cumulative volume percentage of 50 volume% (D50) is 0.80 or more and 1.2 or less. [7] A positive electrode active material for a non-aqueous electrolyte secondary battery, obtained by baking the nickel composite hydroxide according to any one of [1] to [6] with a lithium compound. [8] a crystallization step of mixing an aqueous solution containing a nickel salt, a cobalt salt, and a manganese salt with a pH adjuster in a reaction vessel and causing a coprecipitation reaction in the mixed solution to obtain crude nickel-cobalt-manganese hydroxide; a solid-liquid separation step of washing the crude nickel composite hydroxide obtained in the crystallization step with an alkaline aqueous solution and then performing solid-liquid separation; Including, ammonia concentration in the mixed liquid in the crystallization step is 0.0 g / L or more and 3.5 g / L or less, and pH in the mixed liquid at a liquid temperature of 40°C is 10.4 or more and 11.5 or less. [9] The method for producing a nickel composite hydroxide according to [8], wherein the aqueous solution containing a nickel salt, a cobalt salt, and a manganese salt, an ammonium ion donor, and the pH adjuster are mixed in the reaction tank.

[10] a crystallization step of mixing an aqueous solution containing a nickel salt, a cobalt salt, and a manganese salt with a pH adjuster in a reaction vessel and causing a coprecipitation reaction in the mixed solution to obtain crude nickel-cobalt-manganese hydroxide; a solid-liquid separation step of washing the crude nickel composite hydroxide obtained in the crystallization step with an alkaline aqueous solution and then performing solid-liquid separation; Including, a step of obtaining a nickel composite hydroxide by controlling the ammonia concentration in the mixed liquid in the crystallization step to 0.0 g / L or more and 3.5 g / L or less and the pH of the mixed liquid at a liquid temperature of 40°C to 10.4 or more and 11.5 or less; 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; firing the mixture at a firing temperature of 500°C or higher and 650°C or lower; A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising:

[11] The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to

[10] , wherein the aqueous solution containing a nickel salt, a cobalt salt, and a manganese salt, an ammonium ion donor, and the pH adjuster are mixed in the reaction vessel.

[0009] In this specification, the terms "(200) plane in powder X-ray diffraction measurement" and "(013) plane in powder X-ray diffraction measurement" refer to the planes obtained by measuring a powder of nickel composite hydroxide using a CuKα radiation 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, and then performing smoothing processing and background removal processing using the integrated powder X-ray analysis software PDXL, thereby selecting and identifying "Theophrastite,syn Ni(OH)2." [Effects of the Invention]

[0010] According to an embodiment of the nickel composite hydroxide of the present invention, when the peak intensity of the diffraction peak of the (200) plane in powder X-ray diffraction measurement using CuKα rays is defined as α and the peak intensity of the diffraction peak of the (013) plane in powder X-ray diffraction measurement using CuKα rays is defined as β, the value of α / β is 0.75 or more and 0.95 or less, and this makes it possible to reduce the firing temperature when producing a positive electrode active material from the nickel composite hydroxide that is a precursor.

[0011] Furthermore, according to an embodiment of the nickel composite hydroxide of the present invention, when the peak intensity of a diffraction peak appearing in the range of 2θ = 69.2 ± 0.1° in powder X-ray diffraction measurement using CuKα radiation is defined as α and the peak intensity of a diffraction peak appearing in the range of 2θ = 70.4 ± 0.1° in powder X-ray diffraction measurement using CuKα radiation is defined as β, the value of α / β is 0.75 or more and 0.95 or less, thereby making it possible to reduce the firing temperature when producing a positive electrode active material from the nickel composite hydroxide precursor. Furthermore, according to an embodiment of the nickel composite hydroxide of the present invention, when the peak intensity of a diffraction peak appearing in the range of 2θ = 69.5 ± 0.3° in powder X-ray diffraction measurement using CuKα radiation is defined as α and the peak intensity of a diffraction peak appearing in the range of 2θ = 70.5 ± 0.3° in powder X-ray diffraction measurement using CuKα radiation is defined as β, the value of α / β is 0.75 or more and 0.95 or less, thereby making it possible to reduce the firing temperature when producing a positive electrode active material from the nickel composite hydroxide precursor.

[0012] According to an embodiment of the nickel composite hydroxide of the present invention, the secondary particle diameter (D50) at a cumulative volume percentage of 50% by volume is 6.0 μm or more and 16.0 μm or less, thereby making it possible to improve the loading density of the positive electrode active material and also improve contact with the non-aqueous electrolyte.

[0013] According to an embodiment of the nickel composite hydroxide of the present invention, the value of [secondary particle diameter at a cumulative volume percentage of 90 volume% (D90) - secondary particle diameter at a cumulative volume percentage of 10 volume% (D10)] / secondary particle diameter at a cumulative volume percentage of 50 volume% (D50) is 0.80 or more and 1.2 or less, and therefore it is possible to improve the loading density of the positive electrode active material and to uniformize the various properties of the positive electrode active material regardless of the particle diameter of the nickel composite hydroxide.

[0014] According to an embodiment of the method for producing a nickel composite hydroxide of the present invention, the ammonia concentration in the mixed liquid in the crystallization step is 0.0 g / L or more and 3.5 g / L or less, and the pH at a liquid temperature of 40°C is 10.4 or more and 11.5 or less, whereby a nickel composite hydroxide can be obtained that can reduce the firing temperature when producing a positive electrode active material. [Brief explanation of the drawings]

[0015] [Figure 1] Figure (a) is a powder X-ray diffraction pattern of the nickel composite hydroxides of Examples 1 and 2 and Comparative Example 1, Figure (b) is an enlarged view of the powder X-ray diffraction pattern shown in Figure (a), Figure (c) is a powder X-ray diffraction pattern of the nickel composite hydroxides of Examples 3 to 5, and Figure (d) is an enlarged view of the powder X-ray diffraction pattern shown in Figure (c). [Figure 2] Graph (a) shows the TG measurement results of Comparative Example 1, graph (b) shows the TG measurement results of Example 1, and graph (c) shows the TG measurement results of Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0016] The nickel composite hydroxide of the present invention, which is a precursor of the positive electrode active material of a non-aqueous electrolyte secondary battery, will be described in detail below. The nickel composite hydroxide of the present invention, which is a precursor of the positive electrode active material of a non-aqueous electrolyte secondary battery (hereinafter, sometimes simply referred to as the "nickel composite hydroxide of the present invention"), contains nickel (Ni), cobalt (Co), and manganese (Mn). That is, the nickel composite hydroxide of the present invention contains Ni, Co, and Mn as essential metal components.

[0017] The nickel composite hydroxide of the present invention is a secondary particle 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 may be a wide variety of shapes, such as a substantially spherical shape or a substantially elliptical shape.

[0018] The nickel composite hydroxide of the present invention is configured to include a structure belonging to the hexagonal space group P-3m1 in powder X-ray diffraction measurement using CuKα radiation, and the range of 2θ = 69.2 ± 0.1° was selected and identified as "Theophrastite, syn Ni(OH)2" and can be expressed as the (200) plane, and the peak intensity of the diffraction peak is α, and the range of 2θ = 70.4 ± 0.1° in powder X-ray diffraction measurement using CuKα radiation was selected and identified as "Theophrastite, syn Ni(OH)2" and can be expressed as the (013) plane, and the peak intensity of the diffraction peak is β, and the value of α / β, which is the ratio of peak intensity α to peak intensity β, is 0.75 or more and 0.95 or less. By having the value of α / β be 0.75 or more and 0.95 or less, it is possible to reduce the firing temperature when producing a positive electrode active material from the nickel composite hydroxide of the present invention, which is a precursor. Therefore, by using the nickel composite hydroxide of the present invention as a precursor of a positive electrode active material, it is possible to obtain a positive electrode active material with further improved properties such as high utilization rate and high cycle characteristics, and also, when producing a positive electrode active material from the nickel composite hydroxide of the present invention, production efficiency is improved and energy can be saved.

[0019] Furthermore, the nickel composite hydroxide of the present invention is configured to include a structure belonging to the hexagonal space group P-3m1 in powder X-ray diffraction measurement using CuKα radiation, and the range of 2θ = 69.5 ± 0.3 ° was selected and identified as "Theophrastite, syn Ni(OH)2", which can be expressed as the (200) plane, and the peak intensity of the diffraction peak is α, and the range of 2θ = 70.5 ± 0.3 ° in powder X-ray diffraction measurement using CuKα radiation was selected and identified as "Theophrastite, syn Ni(OH)2", which can be expressed as the (013) plane, and the peak intensity of the diffraction peak is β, and the value of α / β, which is the ratio of peak intensity α to peak intensity β, is 0.75 or more and 0.95 or less. By having the value of α / β be 0.75 or more and 0.95 or less, it is possible to reduce the firing temperature when producing a positive electrode active material from the nickel composite hydroxide of the present invention, which is a precursor. Therefore, by using the nickel composite hydroxide of the present invention as a precursor of a positive electrode active material, it is possible to obtain a positive electrode active material with further improved properties such as high utilization rate and high cycle characteristics, and also, when producing a positive electrode active material from the nickel composite hydroxide of the present invention, production efficiency is improved and energy can be saved.

[0020] It is believed that the peak with peak intensity α is derived from the crystalline structure of nickel hydroxide, and the peak with peak intensity β is derived from the crystalline structure of nickel hydroxide.

[0021] The value of α / β is not particularly limited as long as it is 0.75 or more and 0.95 or less, but the lower limit is more preferably 0.78 and particularly preferably 0.80 in order to further reduce the firing temperature when producing the positive electrode active material. On the other hand, the upper limit of α / β is more preferably 0.93 and particularly preferably 0.91 in order to further reduce the firing temperature when producing the positive electrode active material. The above upper and lower limit values ​​can be combined arbitrarily.

[0022] Examples of the composition of the nickel composite hydroxide of the present invention include nickel composite hydroxides represented by a molar ratio of Ni:Co:Mn:M of 1 - x - y - z:x:y:z (0 < x ≤ 0.15, 0 < y ≤ 0.15, 0 ≤ z ≤ 0.05, where M means one or more additive elements selected from the group consisting of Al, Fe, Ti, and Zr).

[0023] 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 with a cumulative volume percentage of 50% (hereinafter sometimes simply referred to as "D50") is preferably 5.5 μm, particularly preferably 6.0 μm, from the viewpoint of improving the loading density of the positive electrode active material on the positive electrode. On the other hand, the upper limit of D50 of the nickel composite hydroxide of the present invention is preferably 16.5 μm, particularly preferably 16.0 μm, from the viewpoint of improving the contact with the electrolyte. The above upper and lower limits can be arbitrarily combined. Also, the lower limit of the secondary particle size with a cumulative volume percentage of 90% (hereinafter sometimes simply referred to as "D90") of the nickel composite hydroxide of the present invention is preferably 15.0 μm, particularly preferably 17.0 μm, from the viewpoint of improving the loading density of the positive electrode active material on the positive electrode. On the other hand, the upper limit of D90 of the nickel composite hydroxide of the present invention is preferably 27.0 μm, particularly preferably 25.0 μm, from the viewpoint of improving the contact with the non-aqueous electrolyte. The above upper and lower limits can be arbitrarily combined. Also, the lower limit of the secondary particle size with a cumulative volume percentage of 10% (hereinafter sometimes simply referred to as "D10") of the nickel composite hydroxide of the present invention is preferably 4.5 μm, particularly preferably 5.5 μm, from the viewpoint of improving the loading density of the positive electrode active material on the positive electrode. On the other hand, the upper limit of D10 of the nickel composite hydroxide of the present invention is preferably 8.5 μm, particularly preferably 7.5 μm, from the viewpoint of improving the contact with the non-aqueous electrolyte. 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.

[0024] Furthermore, the particle size distribution width of the nickel composite hydroxide of the present invention is not particularly limited, but the lower limit of (D90-D10) / D50 is preferably 0.65, and particularly preferably 0.80, from the viewpoint of improving the loading density of the positive electrode active material on the positive electrode. On the other hand, the upper limit of (D90-D10) / D50 of the nickel composite hydroxide of the present invention is preferably 1.60, and particularly preferably 1.20, from the viewpoint of uniforming the various properties of the positive electrode active material, regardless of the particle diameter of the nickel composite hydroxide. The above-mentioned upper and lower limit values ​​can be combined in any desired manner.

[0025] The tap density (TD) of the nickel composite hydroxide of the present invention is not particularly limited, but for example, the lower limit is preferably 1.40 g / ml and particularly preferably 1.50 g / ml from the viewpoint of improving the filling degree of the positive electrode active material in the positive electrode. On the other hand, the upper limit of the tap density of the nickel composite hydroxide of the present invention is preferably 2.40 g / ml and particularly preferably 2.30 g / ml from the viewpoint of improving the contact between the positive electrode active material and the non-aqueous electrolyte. The above upper limit and lower limit can be combined arbitrarily.

[0026] The bulk density (BD) of the nickel composite hydroxide of the present invention is not particularly limited, but for example, the lower limit is preferably 1.00 g / ml and particularly preferably 1.10 g / ml from the viewpoint of improving the filling degree of the positive electrode active material in the positive electrode. On the other hand, the upper limit of the bulk density of the nickel composite hydroxide of the present invention is preferably 1.80 g / ml and particularly preferably 1.75 g / ml from the viewpoint of improving the contact between the positive electrode active material and the non-aqueous electrolyte. The above upper limit and lower limit can be combined in any manner.

[0027] The BET specific surface area of ​​the nickel composite hydroxide of the present invention is not particularly limited, but for example, the lower limit thereof is 5.0 m from the viewpoint of improving the degree of filling of the positive electrode active material into the positive electrode and the contact area with the non-aqueous electrolyte. 2 / g is preferred, 6.0m 2 On the other hand, the upper limit of the BET specific surface area of ​​the nickel composite hydroxide of the present invention is 40 m / g from the viewpoint of improving the crushing strength of the positive electrode active material. 2 / g is preferred, 30m2 The above upper and lower limits can be combined in any desired manner.

[0028] Next, a method for producing the nickel composite hydroxide of the present invention will be described. First, a crude nickel composite hydroxide is prepared by a coprecipitation method, by appropriately adding a solution containing a nickel salt (for example, a sulfate), a cobalt salt (for example, a sulfate), and a manganese salt (for example, a sulfate), and, if necessary, a complexing agent and a pH adjuster, and then causing a neutralization reaction and crystallization in a reaction tank, thereby obtaining a slurry-like suspension containing the crude nickel composite hydroxide. Water, for example, is used as the solvent for the suspension. The crude nickel composite hydroxide may be in the form of particles.

[0029] The complexing agent is not particularly limited as long as it can form a complex with nickel ions, cobalt ions, and manganese ions in an aqueous solution, and examples thereof include ammonium ion donors. Examples of ammonium ion donors include ammonium sulfate, ammonium chloride, ammonium carbonate, and ammonium fluoride. During the neutralization reaction, an alkali metal hydroxide (e.g., sodium hydroxide or potassium hydroxide) is added as a pH adjuster to adjust the pH value of the aqueous solution.

[0030] A pH adjuster and, if necessary, an ammonium ion donor are continuously supplied to a reaction vessel to the metal salt solution containing nickel, cobalt, and manganese, and the mixture in the reaction vessel is appropriately stirred. The metals (nickel, cobalt, and manganese) in the metal salt solution are co-precipitated by a neutralization reaction, resulting in the crystallization of a crude nickel composite hydroxide. During the neutralization reaction, the temperature of the reaction vessel is controlled, for example, within a range of 10°C to 90°C, preferably 20°C to 80°C. When the pH adjuster and, if necessary, an ammonium ion donor are supplied to the reaction vessel to carry out the neutralization reaction, the ammonia concentration of the mixture in the reaction vessel is controlled to 0.0 g / L to 3.5 g / L, preferably 1.8 g / L to 3.0 g / L, and the pH of the mixture at a liquid temperature of 40°C is controlled to 10.8 to 11.5, preferably 11.0 to 11.2, thereby producing a nickel composite hydroxide having an α / β value of 0.75 to 0.95.

[0031] Examples of the reaction tank used in the method for producing a nickel composite hydroxide of the present invention include a continuous type in which the obtained crude nickel composite hydroxide is overflowed to separate it, and a batch type in which the reaction tank is not discharged outside the system until the end of the reaction.

[0032] As described above, the crude nickel composite hydroxide obtained in the crystallization step is filtered from the suspension and then washed with an alkaline aqueous solution to remove impurities contained in the crude nickel composite hydroxide, thereby obtaining a purified nickel composite hydroxide (the nickel composite hydroxide of the present invention). Thereafter, solid-liquid separation is performed, and the solid phase containing the nickel composite hydroxide is washed with water as necessary, and the nickel composite hydroxide is heat-treated and dried, thereby obtaining a powdery nickel composite hydroxide.

[0033] Next, a positive electrode active material for a non-aqueous electrolyte secondary battery using the nickel composite hydroxide of the present invention as a precursor (hereinafter, sometimes 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 form in which the nickel composite hydroxide of the present invention, which is a precursor, is calcined 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 preferable that the crystal structure be a trigonal crystal structure, 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 for a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery.

[0034] In addition, when producing the positive electrode active material of the present invention, a step of converting a nickel composite hydroxide into a nickel composite oxide may be carried out in advance, and the nickel composite oxide may be used as a precursor. A method for preparing a nickel composite oxide from a nickel composite hydroxide can include an oxidation treatment in which the nickel composite hydroxide is calcined in an atmosphere containing oxygen gas at a temperature of 300°C to 800°C for 1 hour to 10 hours.

[0035] Next, a method for producing the positive electrode active material of the present invention will be described. For example, in the method for producing the positive electrode active material of the present invention, a lithium compound is first added 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.

[0036] Next, the resulting mixture is calcined to produce a positive electrode active material. With the nickel composite hydroxide of the present invention, the calcination temperature when producing a positive electrode active material can be reduced. While conventional calcination temperatures are approximately 800°C or higher and 1000°C or lower, with the nickel composite hydroxide of the present invention, the precursor and the lithium compound react sufficiently even at a calcination temperature of 500°C or higher and 650°C or lower, making it possible to produce a positive electrode active material that has excellent properties such as high utilization rate and high cycle characteristics.

[0037] The temperature rise rate when firing the resulting mixture can be from 50°C / h to 300°C / h, and the firing time can be from 5 hours to 20 hours. The firing atmosphere is not particularly limited, but examples include air and oxygen. The firing furnace used for firing is not particularly limited, but examples include a stationary box furnace and a roller hearth continuous furnace.

[0038] Next, a 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 additive. The conductive additive is not particularly limited as long as it can be used for non-aqueous electrolyte secondary batteries, and for example, a carbon-based material can be used. Examples of carbon-based materials include graphite powder, carbon black (e.g., acetylene black), and fibrous carbon materials. Examples of binders include, but are not limited to, polymer resins such as polyvinylidene fluoride (PVdF), butadiene rubber (BR), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), and polytetrafluoroethylene (PTFE), as well as combinations thereof. The positive electrode current collector is not particularly limited, but for example, a strip-shaped member made of a metal material such as Al, Ni, or stainless steel can be used. Among these, Al is preferred as a forming material and is processed into a thin film because it is easy to process and inexpensive.

[0039] In a method for producing a positive electrode, for example, the positive electrode active material of the present invention, a conductive additive, and a binder are mixed together to prepare a positive electrode active material slurry, which is then applied to a positive electrode current collector by a known filling method, dried, and pressed to bond the slurry, thereby obtaining a positive electrode.

[0040] A nonaqueous electrolyte secondary battery can be assembled 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 containing the negative electrode active material formed on the surface of the negative electrode current collector, an electrolytic solution containing a predetermined electrolyte, and a separator by a known method.

[0041] The electrolytes contained in non-aqueous electrolytes include LiClO4, LiPF6, LiAsF6, LiSbF6, LiBF4, LiCF3SO3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(COCF3), Li(C4F9SO3), LiC(SO2CF3)3, Li2B 10 Cl 10 Examples of the lithium salt include LiBOB (here, BOB is bis(oxalato)borate), LiFSI (here, FSI is bis(fluorosulfonyl)imide), lithium salts of lower aliphatic carboxylic acids, and lithium salts such as LiAlCl4. These may be used alone or in combination of two or more.

[0042] Examples of the dispersion medium for the electrolyte include carbonates such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one, and 1,2-di(methoxycarbonyloxy)ethane; 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropyl methyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, tetrahydrofuran, and 2-methyltetrahydrofuran. Examples of suitable organic solvents include ethers such as methyl formate, methyl acetate, and γ-butyrolactone; nitriles such as acetonitrile and butyronitrile; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; carbamates such as 3-methyl-2-oxazolidone; sulfur-containing compounds such as sulfolane, dimethyl sulfoxide, and 1,3-propane sultone; and organic solvents containing fluoro groups (organic solvents in which one or more hydrogen atoms have been replaced with fluorine atoms). These may be used alone or in combination of two or more.

[0043] Alternatively, a solid electrolyte may be used instead of an electrolyte-containing electrolytic solution. Examples of solid electrolytes that can be used include organic polymer electrolytes such as polyethylene oxide polymer compounds, polymer compounds containing at least one of a polyorganosiloxane chain and a polyoxyalkylene chain. Also usable are so-called gel-type solid electrolytes in which a nonaqueous electrolytic solution is held in a polymer compound. Examples of inorganic solid electrolytes that contain sulfides include Li2S-SiS2, Li2S-GeS2, Li2S-P2S5, Li2S-B2S3, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li2SO4, and Li2S-GeS2-P2S5. These may be used alone or in combination of two or more.

[0044] Examples of the separator include members in the form of porous films, nonwoven fabrics, woven fabrics, etc., made of materials such as polyolefin resins, such as polyethylene and polypropylene, fluororesins, and nitrogen-containing aromatic polymers. [Example]

[0045] 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 they do not depart from the spirit of the present invention.

[0046] Production of nickel composite hydroxides in examples and comparative examples Production of nickel composite hydroxide in Example 1 An aqueous solution of nickel sulfate, cobalt sulfate, and manganese sulfate dissolved in a predetermined molar ratio of nickel:cobalt:manganese, an aqueous ammonium sulfate solution (ammonium ion donor), and an aqueous sodium hydroxide solution were added dropwise to a reaction vessel having a predetermined volume. The mixed solution in the reaction vessel was continuously stirred with a stirrer equipped with a stirring blade while maintaining the pH of the mixed solution in the reaction vessel at 11.2 at a liquid temperature of 40°C and the ammonia concentration at 2.2 g / L. A nitrogen atmosphere was created inside the reaction vessel. The liquid temperature of the mixed solution in the reaction vessel was maintained at 70.0°C. The crude nickel composite hydroxide crystallized by the neutralization reaction was retained in the reaction vessel for 20 hours, and then overflowed from the overflow pipe of the reaction vessel and removed as a suspension. The removed suspension of the crude nickel composite hydroxide was filtered and washed with an alkaline aqueous solution (8 mass% aqueous sodium hydroxide solution) to perform solid-liquid separation. Thereafter, the separated solid phase was washed with water, and further subjected to treatments of dehydration and drying, to obtain a powdery purified nickel composite hydroxide.

[0047] Production of nickel composite hydroxide in Example 2 A purified nickel composite hydroxide was produced in the same manner as in Example 1, except that aqueous solutions with different molar ratios of nickel:cobalt:manganese were used and the pH of the mixed solution in the reaction tank was maintained at 11.1 at a liquid temperature of 40°C.

[0048] Production of nickel composite hydroxide in Example 3 A purified nickel composite hydroxide was produced in the same manner as in Example 1, except that aqueous solutions with different molar ratios of nickel:cobalt:manganese were used and the pH of the mixed solution in the reaction tank was maintained at 11.3 at a liquid temperature of 40°C.

[0049] Production of nickel composite hydroxide in Example 4 A purified nickel composite hydroxide was produced in the same manner as in Example 1, except that the pH of the mixed liquid in the reaction tank was maintained at 10.2 at a liquid temperature of 40°C as a reference, and the ammonia concentration was maintained at 0.0 g / L without adding an ammonium ion donor, which is a complexing agent.

[0050] Production of nickel composite hydroxide in Example 5 A purified nickel composite hydroxide was produced in the same manner as in Example 1, except that aqueous solutions in which the molar ratio of nickel:cobalt:manganese was changed were used, the pH of the mixed solution in the reaction tank was maintained at 10.2 at a standard liquid temperature of 40°C, and the ammonia concentration was maintained at 0.0 g / L without adding an ammonium ion donor, which was a complexing agent.

[0051] Preparation of nickel composite hydroxide of Comparative Example 1 A purified nickel composite hydroxide was produced in the same manner as in Example 1, except that aqueous solutions in which the molar ratio of nickel:cobalt:manganese was changed were used, and the pH of the mixed solution in the reaction tank was maintained at 11.7 at a liquid temperature of 40°C, and the ammonia concentration was maintained at 3.8 g / L.

[0052] The neutralization reaction (crystallization) conditions for the nickel composite hydroxides of the examples and comparative examples are shown in Table 1 below.

[0053] The evaluation items for the physical properties of the nickel composite hydroxides of the examples and comparative examples are as follows. (1) Composition analysis of nickel composite hydroxide The composition analysis was carried out by dissolving the obtained nickel composite hydroxide in hydrochloric acid and then using an inductively coupled plasma emission spectrometer (Optima7300DV, manufactured by PerkinElmer Japan Co., Ltd.).

[0054] (2) D10, D50, D90 Measurements were made using a particle size distribution analyzer (MT3300, manufactured by Nikkiso Co., Ltd.) (based on the laser diffraction and scattering method). Measurement conditions included water as the solvent, 1 mL of sodium hexametaphosphate as the dispersant, a transmittance of 85±3% after sample addition, and no ultrasonic waves. The refractive index of the solvent used during analysis was 1.333, the refractive index of water. In the obtained cumulative particle size distribution curve, the particle diameter value at the point where the cumulative volume from the small particle side is 10% was defined as D10 (μm), the particle diameter value at the point where the cumulative volume is 50% was defined as D50 (μm), and the particle diameter value at the point where the cumulative volume is 90% was defined as D90 (μm).

[0055] The evaluation results of the physical properties of the nickel composite hydroxides of the examples and comparative examples are shown in Table 1 below.

[0056] [Table 1]

[0057] Peak intensities of diffraction peaks of nickel composite hydroxides of Examples and Comparative Examples In Examples 1 and 2 and Comparative Example 1, the nickel composite hydroxide was measured for powder X-ray diffraction using CuKα radiation, and the peak intensity of a diffraction peak that can be expressed as (200) and that appears in the range of 2θ = 69.2 ± 0.1° was measured. The peak intensity of a diffraction peak that can be expressed as (013) and that appears in the range of 2θ = 70.4 ± 0.1° was measured. Specifically, the powder X-ray diffraction measurement was performed using an X-ray diffractometer (Ultima IV, manufactured by Rigaku Corporation). The nickel composite hydroxide powder was filled into a dedicated substrate, and a CuKα radiation source (40 kV / 40 mA) was used to measure the powder X-ray diffraction pattern under the conditions of a diffraction angle 2θ = 5° to 80°, a sampling width of 0.03°, and a scan speed of 20° / min. The obtained powder X-ray diffraction pattern was subjected to smoothing and background removal processing using the integrated powder X-ray analysis software PDXL, and "Theophrastite,syn Ni(OH)2" was selected and identified. As a result, the peak intensity α of the diffraction peak appearing in the range of 2θ = 69.2 ± 0.1 ° from the powder X-ray diffraction pattern, and the peak intensity β of the diffraction peak appearing in the range of 2θ = 70.4 ± 0.1 ° were measured, and the peak intensity ratio α / β was calculated. In addition, in Examples 3 to 5, in the nickel composite hydroxide, the peak intensity of the diffraction peak that can be expressed as (200) appearing in the range of 2θ = 69.5 ± 0.3 ° in powder X-ray diffraction measurement using CuKα radiation was measured, and the peak intensity of the diffraction peak that can be expressed as (013) appearing in the range of 2θ = 70.5 ± 0.3 ° in powder X-ray diffraction measurement using CuKα radiation was measured. The specific method for measuring the peak intensities of the diffraction peaks was the same as in Examples 1 and 2. The peak intensity α of the diffraction peak appearing in the range of 2θ=69.5±0.3° and the peak intensity β of the diffraction peak appearing in the range of 2θ=70.5±0.3° were measured, and the peak intensity ratio α / β was calculated.

[0058] The powder X-ray diffraction patterns of the nickel composite hydroxides of Examples 1 and 2 and Comparative Example 1 are shown in Figure 1(a), with an enlarged view of each shown in Figure 1(b), and the powder X-ray diffraction patterns of the nickel composite hydroxides of Examples 3 to 5 are shown in Figure 1(c), with an enlarged view of each shown in Figure 1(d). The peak intensity ratios α / β are also shown in Table 1 above. Note that, as shown in Figures 1(a) and 1(b), in Comparative Example 1, the peak intensity β of the diffraction peak appearing in the range of 2θ = 70.4 ± 0.1° could not be detected, and therefore it was evaluated that the peak intensity ratio α / β could not be calculated.

[0059] TG measurement (thermogravimetry) of nickel composite hydroxides of Examples and Comparative Examples Lithium hydroxide was mixed with each of the nickel composite hydroxides of Examples 1 to 5 and Comparative Example 1 so that the lithium / (nickel + cobalt + manganese) molar ratio was 1.03 to prepare mixtures. TG measurements were performed on the resulting mixtures at a maximum temperature of 900°C, a heating rate of 10°C / min, a sampling frequency of once per second, and a dry air supply rate of 200 ml / min. A Hitachi "TG / DTA6300" TG measurement device was used. The TG measurement results for Comparative Example 1 are shown in FIG. 2(a), those for Example 1 in FIG. 2(b), and those for Example 2 in FIG. 2(c). The DTG peak positions (°C) in the range of 300 to 600°C obtained from the TG measurement results measured from 30 to 900°C are shown in Table 2 below. Although not shown, TG measurements were also performed on Examples 3 to 5 in the same manner as in Examples 1 and 2, and the DTG peak positions (°C) were measured.

[0060] [Table 2]

[0061] From Tables 1 and 2, in Comparative Example 1, in which the peak intensity ratio α / β could not be calculated, the DTG peak position was 462.1°C, whereas in Example 1, in which the peak intensity ratio α / β was 0.84, the DTG peak position was 441.3°C, and in Example 2, in which the molar ratio of nickel:cobalt:manganese was different from that of Example 1 and the peak intensity ratio α / β was 0.90, the DTG peak position was reduced to 445.3°C. From the above, the nickel composite hydroxides of Examples 1 and 2 reacted with the lithium compound at a lower temperature than the nickel composite hydroxide of Comparative Example 1. Therefore, it was found that the nickel composite hydroxides of Examples 1 and 2 could reduce the firing temperature when producing a positive electrode active material compared to the nickel composite hydroxide of Comparative Example 1.

[0062] In Example 3, in which the molar ratio of nickel:cobalt:manganese was different from Examples 1 and 2 and the peak intensity ratio α / β was 0.83, the DTG peak position was 439.5°C; in Example 4, in which the peak intensity ratio α / β was 0.90 when the pH of the mixed solution in the reaction vessel was 10.2 based on a liquid temperature of 40°C and the ammonia concentration was 0.0 g / L, the DTG peak position was 458.0°C; and in Example 5, in which the molar ratio of nickel:cobalt:manganese was different from Examples 1, 3, and 4 and the peak intensity ratio α / β was 0.88 when the pH of the mixed solution in the reaction vessel was 10.2 based on a liquid temperature of 40°C and the ammonia concentration was 0.0 g / L, the DTG peak position was reduced to 457.8°C. From the above, the nickel composite hydroxides of Examples 3 to 5 reacted with a lithium compound at a lower temperature than the nickel composite hydroxide of Comparative Example 1. Therefore, it was found that the nickel composite hydroxides of Examples 3 to 5 were able to reduce the firing temperature when producing a positive electrode active material compared to the nickel composite hydroxide of Comparative Example 1. [Industrial Applicability]

[0063] The nickel composite hydroxide of the present invention can reduce the firing temperature when producing a positive electrode active material, and therefore can be used in a wide range of fields, such as portable devices and vehicles.

Claims

1. In the nickel composite hydroxide, when the peak intensity of a diffraction peak of a (200) plane in powder X-ray diffraction measurement using CuKα rays is defined as α and the peak intensity of a diffraction peak of a (013) plane in powder X-ray diffraction measurement using CuKα rays is defined as β, the value of α / β is 0.83 or more and 0.90 or less, and the nickel composite hydroxide contains Ni, Co, and Mn. The nickel composite hydroxide is a precursor for a positive electrode active material of a non-aqueous electrolyte secondary battery, and the molar ratio of Ni:Co:Mn:M in the nickel composite hydroxide is expressed as 1-x-y-z:x:y:z (0.090<x≦0.15, 0.025<y≦0.100, z=0, M represents one or more added elements selected from the group consisting of Al, Fe, Ti, and Zr).

2. 2. The nickel composite hydroxide according to claim 1, wherein, in the nickel composite hydroxide, a diffraction peak of the (200) plane is a diffraction peak that appears in the range of 2θ = 69.2 ± 0.1°, and a diffraction peak of the (013) plane is a diffraction peak that appears in the range of 2θ = 70.4 ± 0.1°, and when a peak intensity of the diffraction peak that appears in the range of 2θ = 69.2 ± 0.1° in powder X-ray diffraction measurement using CuKα rays is defined as α and a peak intensity of the diffraction peak that appears in the range of 2θ = 70.4 ± 0.1° in powder X-ray diffraction measurement using CuKα rays is defined as β, the value of α / β is 0.84 or more and 0.90 or less, and the nickel composite hydroxide contains Ni, Co, and Mn.

3. 2. The nickel composite hydroxide according to claim 1, wherein, in the nickel composite hydroxide, a diffraction peak of the (200) plane is a diffraction peak that appears in the range of 2θ = 69.5 ± 0.3°, and a diffraction peak of the (013) plane is a diffraction peak that appears in the range of 2θ = 70.5 ± 0.3°, and when a peak intensity of the diffraction peak that appears in the range of 2θ = 69.5 ± 0.3° in powder X-ray diffraction measurement using CuKα rays is defined as α and a peak intensity of the diffraction peak that appears in the range of 2θ = 70.5 ± 0.3° in powder X-ray diffraction measurement using CuKα rays is defined as β, the value of α / β is 0.83 or more and 0.90 or less, and the nickel composite hydroxide contains Ni, Co, and Mn.

4. The nickel composite hydroxide according to any one of claims 1 to 3, wherein a secondary particle diameter (D50) at a cumulative volume percentage of 50% by volume is 6.0 µm or more and 16.0 µm or less.

5. 5. The nickel composite hydroxide according to any one of claims 1 to 4, wherein a value of [secondary particle diameter at a cumulative volume percentage of 90 volume% (D90) - secondary particle diameter at a cumulative volume percentage of 10 volume% (D10)] / secondary particle diameter at a cumulative volume percentage of 50 volume% (D50) is 0.80 or more and 1.2 or less.

6. 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.

7. a crystallization step of mixing an aqueous solution containing a nickel salt, a cobalt salt, and a manganese salt with a pH adjuster in a reaction tank and causing a coprecipitation reaction in the mixed liquid to obtain a crude nickel composite hydroxide; a solid-liquid separation step of washing the crude nickel composite hydroxide obtained in the crystallization step with an alkaline aqueous solution and then performing solid-liquid separation; Including, 6. The method for producing a nickel composite hydroxide according to any one of claims 1 to 5, wherein an ammonia concentration in the mixed liquid in the crystallization step is 0.0 g / L or more and 3.5 g / L or less, and a pH of the mixed liquid at a liquid temperature of 40°C is 10.4 or more and 11.5 or less, The nickel composite hydroxide has a molar ratio of Ni:Co:Mn:M expressed as 1-x-y-z:x:y:z (0.090<x≦0.15, 0.025<y≦0.100, z=0, and M represents one or more added elements selected from the group consisting of Al, Fe, Ti, and Zr).

8. 8. The method for producing a nickel composite hydroxide according to claim 7, wherein the aqueous solution containing a nickel salt, a cobalt salt, and a manganese salt, an ammonium ion donor, and the pH adjuster are mixed in the reaction tank.

9. a crystallization step of mixing an aqueous solution containing a nickel salt, a cobalt salt, and a manganese salt with a pH adjuster in a reaction tank and causing a coprecipitation reaction in the mixed liquid to obtain a crude nickel composite hydroxide; a solid-liquid separation step of washing the crude nickel composite hydroxide obtained in the crystallization step with an alkaline aqueous solution and then performing solid-liquid separation; Including, a step of obtaining the nickel composite hydroxide according to any one of claims 1 to 5 by controlling the ammonia concentration in the mixed liquid in the crystallization step to 0.0 g / L or more and 3.5 g / L or less, and the pH of the mixed liquid at a liquid temperature of 40°C to 10.4 or more and 11.5 or less; 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; firing the mixture at a firing temperature of 500°C or higher and 650°C or lower; A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising:

10. 10. The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 9, wherein the aqueous solution containing a nickel salt, a cobalt salt, and a manganese salt, an ammonium ion donor, and the pH adjuster are mixed in the reaction vessel.

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