Method of producing lithium metal composite oxide and metal composite hydroxyde powder

Abstract

The present invention provides a method of producing a lithium metal composite oxide comprising a process of calcining a mixture of a metal composite hydroxide powder and a lithium source at a temperature of from 700°C to 950°C, wherein the metal composite hydroxide powder contains at least nickel and secondary particles consisting of agglomerated primary particles when the particle diameter corresponding to the largest peak top of the volume-based particle size distribution of the secondary particles is Dt, at least 30% of the secondary particles with a particle diameter between Dt and 1.2 Dt have a long axis of at least 1 μm in the reflected electron image of the cross section obtained using SEM (scanning electron microscope), and at least 10% of the primary particles have pore size of 0.06μm or less and pore volume of 0.15mL / g or less.

Description

[0001] METHOD OF PRODUCING LITHIUM METAL COMPOSITE OXIDE AND METAL COMPOSITE HYDROXYDE POWDER

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a method for producing lithium metal composite oxides and metal composite hydroxide powder.

[0004] BACKGROUND

[0005] In recent years, portable and cordless electronic devices such as cell phones and notebook PCs have rapidly become popular, and nonaqueous rechargeable batteries that are compact, lightweight, and have high energy density are used as power sources to drive these devices. Among them, lithium-ion secondary batteries that use lithium metal composite oxides such as lithium cobaltate and lithium nickelate for the positive electrode are widely used.

[0006] Lithium cobaltate is an excellent material with high voltage and high battery capacity, and is indispensable as a cathode material for small electronic devices, but it is expensive because it is made from cobalt compounds, which are rare and expensive.

[0007] However, it is expensive because it is made from cobalt compounds, which are rare and expensive. In recent years, research has been conducted on ternary cathode active material particles with a layered rock salt structure (basic composition Li(NiCoMn)C>2), which is a solid solution of Ni, Co, and Mn, and lithium-nickel composite compounds (basic composition Li(NiCoAI)O2) in which Al is introduced into lithium nickelate, reducing the amount of cobalt used. O2), in which Al is introduced into lithium nickelate to reduce the use of cobalt.

[0008] The cathode material is expected to exhibit high battery voltage as well as high chargedischarge capacity similar to lithium cobalt composite oxide, and is expected to expand the range of application of lithium-ion secondary batteries for electric vehicles and stationary storage batteries, and further research and development is being actively carried out.

[0009] However, lithium-ion secondary batteries are subject to repeated charge / discharge cycles and storage in a charged state in a high-temperature environment, resulting in reduced battery capacity. This is believed to be due to the fact that the cathode material, which has a layered rock-salt structure, undergoes changes in crystal structure and expansion and contraction as a result of repeated charge / discharge cycles and the state of charge.

[0010] To achieve high stability in lithium-ion batteries, it is considered important to suppress instability of the crystal structure, especially in lithium-nickel composite oxides, for example. Methods to control the composition balance, crystallite size, and grain size distribution, to obtain powder by controlling the sintering temperature, to strengthen the bonding power in the crystal structure by adding different elements, and to prevent structural destruction and reaction from the electrolyte by surface treatment have been employed as means to achieve this.

[0011] For example, in JP2011-023335, a lithium metal composite oxide is proposed in which the basic composition is UMO2 and M is a group of four or more elements including at least three elements selected from Co, Mn, Al, Mg, and Ti and Ni. According to JP2011-023335, in a lithium-containing composite oxide, the metallic site is substituted with Al, and the metallic and Li sites are substituted with Mg, thereby reducing the expansion and contraction rate of the crystal structure due to Li deinsertion during charging / discharging, and as a result, mitigating irreversible reactions As a result, irreversible reactions can be mitigated and cycle characteristics can be improved.

[0012] However, the lithium metal composite oxide described in JP2011-023335 does not have sufficient cycle characteristics for practical use, and there is still room for improvement.

[0013] SUMMARY OF THE INVENTION

[0014] The purpose of this disclosure is to provide a method for producing a lithium metal composite oxide that exhibits high cycle characteristics and charge-discharge capacity when used as a cathode active material in a nonaqueous electrolyte secondary battery, and a metal composite hydroxide for use in the production of the method.

[0015] The inventors of the present invention have made a series of diligent examinations in order to solve the above-mentioned problems. As a result, they found that the process includes calcination of a mixture of a metal complex hydroxide powder and a lithium source at 700°C to 950°C. The metal complex hydroxide powder contains at least nickel and secondary particles consisting of agglomerated primary particles, and when the particle diameter corresponding to the largest peak top of the volume-based particle diameter frequency distribution of the secondary particles is Dt When the diameter is Dt, more than 30% of the secondary particles with a particle diameter between Dt and 1.2 Dt have primary particles with a major axis length of at least 1 pm in the electron reflection image of the cross-section obtained using SEM (scanning electron microscope), and a pore volume of no more than 0.15 mL / g and a pore diameter of no more than 0.06 pm. The lithium metal composite hydroxide produced by the production method in which the pore volume is 0.15 mL / g or less, we have found that it is possible to provide a production method for lithium metal composite oxides and metal composite hydroxides used in the production method, in which a non-aqueous electrolyte secondary battery using the same as a positive active material shows high cycle characteristics and charge-discharge capacity.

[0016] The present disclosure provides a method for producing lithium metal composite oxide, which, when used as a cathode active material, exhibits high cycle characteristics and chargedischarge capacity in nonaqueous electrolyte secondary batteries using the same, and a metal composite hydroxide for use in the production of the same.

[0017] The method of producing lithium metal composite hydroxide and the method of producing lithium metal composite hydroxide for use in the production thereof.

[0018] DETAILED DESCRIPTION OF THE INVENTION

[0019] The method of producing a lithium metal composite oxide according to the first embodiment of the present disclosure includes the process of calcining a mixture of a metal composite hydroxide powder and a lithium source at 700°C or more and 950°C or less (calcination process). The method of producing the lithium metal composite oxide according to the first embodiment of the present disclosure is such that the metal composite hydroxide powder contains at least nickel and includes secondary particles made of agglomerated primary particles, and when the particle diameter corresponding to the largest peak top of the volumebased particle diameter frequency distribution of the secondary particles is Dt, the particle diameter is between Dt and 1 ,5Dt. When 30% or more of the secondary particles of Dt 2Dt or less on a number basis are primary particles whose major axis length is 1 pm or more in the reflection electron image of the cross section obtained using a scanning electron microscope, and whose pore volume is 0.15 mL / g or less with a pore size of 0.06 pm or less.

[0020] The method of producing lithium metal composite oxide according to the second embodiment of the present disclosure includes the process of temporarily sintering the metal composite hydroxide powder at 200°C or more but less than 700°C to obtain a temporarily sintered product (temporarily sintering process) and sintering the mixture of the temporarily sintered product and lithium source at 700°C or more but less than 950°C (sintering process). The method of producing a lithium metal composite hydroxide according to the second embodiment of the present disclosure, wherein the metal composite hydroxide powder contains at least nickel, includes secondary particles made of agglomerated primary particles, and when the particle diameter corresponding to the largest peak top of the volume-based particle diameter frequency distribution of the secondary particles is Dt, the particle diameter is between Dt and 1.5Dt.

[0021] When 30% or more of the secondary particles of Dt 2Dt or less in number standard are primary particles of which the length of the major axis is 1 pm or more in number standard in the reflection electron image of the cross section obtained using a scanning electron microscope, and the pore volume of which is 0.15 ml_ / g or less with a pore diameter of 0.06 pm or less is used.

[0022] According to the method for producing the lithium metal composite oxide according to the embodiment of the present disclosure, it is possible to produce a lithium metal composite oxide that, when used as a cathode active material, a nonaqueous electrolyte secondary battery using it exhibits high cycle characteristics and charge-discharge capacity.

[0023] The following is a process-by-process description of an example of a manufacturing method of a lithium metal composite oxide according to an embodiment of the present disclosure. Specifically, an example of the manufacturing method of the lithium metal composite oxide pertaining to an embodiment of the present disclosure is as follows:

[0024] (1) Precursor preparation process: If necessary, a metal composite hydroxide (precursor material) containing at least nickel is prepared.

[0025] (2) Tempering process: If necessary, the metal composite hydroxide powder is temporarily baked.

[0026] (3) Mixing process: If necessary, a mixture is prepared by mixing the metal composite hydroxide powder prepared in the precursor material preparation process and / or the sintering material prepared in the sintering process with a lithium compound.

[0027] (4) Firing process: The mixture prepared in the mixing process is fired.

[0028] (5) Washing process: If necessary, the lithium metal composite oxide obtained by the sintering process is washed with water. (6) Surface treatment process: If necessary, surface treatment is performed on the lithium metal composite oxide obtained in the calcination or washing process.

[0029] (1) Precursor preparation process

[0030] In the raw material preparation process, the metal composite hydroxide is synthesized as an aggregate consisting of primary particles of lithium metal composite oxide. The precursor preparation process is not an essential process for the lithium metal composite oxide production method of the embodiment of the present disclosure.

[0031] Here, the metal composite hydroxide powder used in the method for producing the lithium metal composite oxide according to an embodiment of the present disclosure (i.e. , prepared in this process) contains at least nickel, contains secondary particles consisting of agglomerated primary particles, and when the particle diameter corresponding to the largest peak top of the volume-based particle diameter frequency distribution of the secondary particles is When Dt is taken as the particle diameter, 30% or more of the secondary particles with a particle diameter between Dt and 1.2 Dt on a number basis have primary particles with a major axis length of 1 pm or longer accounting for 10% or more on a number basis in the reflection electron image of a cross-section obtained using a scanning electron microscope, and a pore volume of 0.15 mL / g or less with a pore size of 0.06 pm or less mL / g or less.

[0032] The metal composite hydroxide powder has particles that have grown to a length of at least 1 pm in at least one direction, as seen in the cross section of the secondary particles. Since primary particles of metal composite hydroxide powder tend to grow in a plate-like shape, they should be selectively grown in the direction perpendicular to the flat surface. Specifically, in the above manufacturing method, the production of metal composite hydroxide powder should be divided into a nucleation stage and a crystallization stage. In the nucleation stage, conditions should be selected so that the generated nuclei do not grow too much, and in the crystallization process, conditions should be selected so that the nuclei grow selectively in the direction perpendicular to the plane surface. The conditions of the nucleation and crystallization stages may vary depending on the elemental composition of the metal composite hydroxide powder and the mutual relationship between the conditions of the nucleation stage and the crystallization stage, but at least the conditions of the examples described below can be used to produce the metal composite hydroxide powder of the embodiment of the present disclosure. However, at least under the conditions of the examples described below, it is possible to produce the metal composite hydroxide powder of the embodiment of this disclosure.

[0033] Surprisingly, the inventors found that the lithium metal composite oxide obtained by sintering such metal composite hydroxide powder exhibits high cycle characteristics and chargedischarge capacity of the nonaqueous electrolyte secondary battery using it. The reason for this is not necessarily clear, but the inventors believe the following. The metal composite hydroxide powder described above has a void space inside the secondary particles. This space is maintained at an appropriate size even after being calcined and converted into lithium metal composite oxide, and is thought to absorb the expansion and contraction of volume due to charging and discharging of lithium, thereby exhibiting high cycle characteristics. The chemical composition of the metal composite hydroxide contained in the metal composite hydroxide powder is not limited as long as it contains nickel, for example, the general formula Nii.x-y-zCOxMnyMz(OH)2+a(in the formula, M is For example, the general formula Nii-x-y- zCOxMnyMz(OH)2+a(where M is an element other than Li, Ni, Co, Mn and O, 0<x<0.4, 0<y<0.4, 0<z<0.1, -0.5<a<0.5) is preferable.

[0034] The value of “x” in the general formula is not limited as long as it is within the range of 0 < x < 0.4, for example, 0.001 or more, 0.0015 or more, 0.002 or more, 0.0025 or more, 0.003 or more, 0.0035 or more, 0.004 or more, 0.0045 or more, 0.005 or more, 0.0055 or more, 0.006 or more, 0.0065 or more, 0.007 or more, 0.0075 or more, 0.008 or more, 0.0085 or more, 0.009 or more, 0.0095 or more, 0.01 or more, 0.015 or more, 0.02 or more, 0.025 or more, 0.03 or more, 0.035 or more, 0.04 or more, 0.045 or more, 0.05 or more, 0.055 or more, 0.06 or more, 0.065 or more, 0.07 or more, 0.075 or more, 0.08 or more, 0.085 or more, 0.09 or more, 0.095 or more, 0.1 or more, 0.102 or more, 0.105 or more, 0.107 or more, 0.11 or more, 0.112 or more, 0.115 or more, 0.117 or more, 0.12 or more, 0.122 or more, 0.125 or more, 0.127 or more, 0.13 or more, 0.132 or more, 0.135 or more, 0.137 or more, 0.14 or more, 0.142 or more, 0.145 or more, 0.147 or more, 0.15 or more, 0.152 or more, 0.155 or more, 0.157 or more, 0.16 or more, 0.162 or more, 0.165 or more, 0.167 or more, 0.17 or more, 0.172 or more, 0.175 or more, 0.177 or more, 0.18 or more, 0.182 or more, 0.185 or more, 0.187 or more, 0.19 or more, 0.192 or more, 0.195 or more, 0.197 or more, 0.2 or more, 0.202 or more, 0.205 or more, 0.207 or more, 0.21 or more, 0.212 or more, 0.215 or more, 0.217 or more, 0.22 or more, 0.222 or more, 0.225 or more, 0.227 or more, 0.23 or more, 0.232 or more, 0.235 or more, 0.237 or more, 0.24 or more, 0.242 or more, 0.245 or more, 0.247 or more, 0.25 or more, 0.252 or more, 0.255 or more, 0.257 or more, 0.26 or more, 0.262 or more, 0.265 or more, 0.267 or more, 0.27 or more, 0.272 or more, 0.275 or more, 0.277 or more, 0.28 or more, 0.282 or more, 0.285 or more, 0.287 or more, 0.29 or more, 0.292 or more, 0.295 or more, 0.297 or more, 0.3 or more, 0.302 or more, 0.305 or more, 0.307 or more, 0.31 or more, 0.312 or more, 0.315 or more, 0.317 or more, 0.32 or more, 0.322 or more, 0.325 or more, 0.327 or more, 0.33 or more, 0.332 or more, 0.335 or more, 0.337 or more, 0.34 or more, 0.342 or more, 0.345 or more, 0.347 or more, 0.35 or more, 0.352 or more, 0.355 or more, 0.357 or more, 0.36 or more, 0.362 or more, 0.365 or more, 0.367 or more, 0.37 or more, 0.372 or more, 0.375 or more, 0.377 or more, 0.38 or more, 0.382 or more, 0.385 or more, 0.387 or more, 0.39 or more, 0.392 or more, 0.395 or more, 0.397 or more is preferable. On the other hand, the value of “x” is preferably 0.397 or less, 0.395 or less, 0.392 or less, 0.39 or less, 0.387 or less, 0.385 or less, 0.382 or less, 0.38 or less, 0.377 or less, 0.375 or less, 0.372 or less, 0.367 or less, 0.365 or less, 0.362 or less, 0.36 or less, 0.357 or less, 0.355 or less, 0.352 or less, 0.35 or less, 0.347 or less, 0.345 or less, 0.342 or less, 0.34 or less, 0.337 or less, 0.335 or less, 0.332 or less, 0.33 or less, 0.327 or less, 0.325 or less, 0.322 or less, 0.32 or less, 0.317 or less, 0.315 or less, 0.312 or less, 0.31 or less, 0.307 or less, 0.305 or less, 0.302 or less, 0.3 or less, 0.297 or less, 0.295 or less, 0.292 or less, 0.29 or less, 0.287 or less, 0.285 or less, 0.282 or less, 0.28 or less, 0.277 or less, 0.275 or less,

[0035] 0.272 or less, 0.27 or less, 0.267 or less, 0.265 or less, 0.26 or less, 0.257 or less, 0.255 or less,

[0036] 0.252 or less, 0.25 or less, 0.247 or less, 0.245 or less, 0.242 or less, 0.24 or less, 0.237 or less,

[0037] 0.235 or less, 0.232 or less, 0.23 or less, 0.227 or less, 0.225 or less, 0.222 or less, 0.22 or less,

[0038] 0.217 or less, 0.215 or less, 0.212 or less, 0.21 or less, 0.207 or less, 0.205 or less, 0.202 or less, 0.2 or less, 0.197 or less, 0.195 or less, 0.192 or less, 0.19 or less, 0.187 or less, 0.185 or less, 0.182 or less, 0.18 or less, 0.177 or less, 0.175 or less, 0.172 or less, 0.17 or less, 0.167 or less, 0.165 or less, 0.162 or less, 0.16 or less, 0.155 or less, 0.152 or less, 0.15 or less, 0.147 or less, 0.145 or less, 0.142 or less, 0.14 or less, 0.137 or less, 0.135 or less, 0.132 or less, 0.13 or less, 0.127 or less, 0.125 or less, 0.122 or less, 0.12 or less, 0.117 or less, 0.115 or less, 0.112 or less, 0.11 or less, 0.107 or less, 0.105 or less, 0.102 or less, 0.1 or less, 0.095 or less, 0.09 or less, 0.085 or less, 0.08 or less, 0.075 or less, 0.07 or less, 0.065 or less, 0.06 or less, 0.055 or less, 0.05 or less, 0.045 or less, 0.04 or less, 0.035 or less, 0.03 or less, 0.025 or less, 0.02 or less, 0.015 or less, 0.01 or less, 0.0095 or less, 0.009 or less, 0.0085 or less,

[0039] 0.008 or less, 0.0075 or less, 0.007 or less, 0.0065 or less, 0.006 or less, 0.0055 or less, 0.005 or less, 0.0045 or less, 0.004 or less, 0.0035 or less, 0.003 or less, 0.0025 or less, 0.002 or less, 0.0015 or less, 0.001 or less.

[0040] The value of “y” in the general formula is not limited as long as it is within the range of 0 < y < 0.4, for example, 0.001 or more, 0.0015 or more, 0.002 or more, 0.0025 or more, 0.003 or more, 0.0035 or more, 0.004 or more, 0.0045 or more, 0.005 or more, 0.0055 or more, 0.006 or more, 0.0065 or more, 0.007 or more, 0.0075 or more, 0.008 or more, 0.0085 or more, 0.009 or more, 0.0095 or more, 0.01 or more, 0.015 or more, 0.02 or more, 0.025 or more, 0.03 or more, 0.035 or more, 0.04 or more, 0.045 or more, 0.05 or more, 0.055 or more, 0.06 or more, 0.065 or more, 0.07 or more, 0.075 or more, 0.08 or more, 0.085 or more, 0.09 or more, 0.095 or more, 0.1 or more, 0.102 or more, 0.105 or more, 0.107 or more, 0.11 or more, 0.112 or more, 0.115 or more, 0.117 or more, 0.12 or more, 0.122 or more, 0.125 or more, 0.127 or more, 0.13 or more, 0.132 or more, 0.135 or more, 0.137 or more, 0.14 or more, 0.142 or more, 0.145 or more, 0.147 or more, 0.15 or more, 0.152 or more, 0.155 or more, 0.157 or more, 0.16 or more, 0.162 or more, 0.165 or more, 0.167 or more, 0.17 or more, 0.172 or more, 0.175 or more, 0.177 or more, 0.18 or more, 0.182 or more, 0.185 or more, 0.187 or more, 0.19 or more, 0.192 or more, 0.195 or more, 0.197 or more, 0.2 or more, 0.202 or more, 0.205 or more, 0.207 or more, 0.21 or more, 0.212 or more, 0.215 or more, 0.217 or more, 0.22 or more, 0.222 or more, 0.225 or more, 0.227 or more, 0.23 or more, 0.232 or more, 0.235 or more, 0.237 or more, 0.24 or more, 0.242 or more, 0.245 or more, 0.247 or more, 0.25 or more, 0.252 or more, 0.255 or more, 0.257 or more, 0.26 or more, 0.262 or more, 0.265 or more, 0.267 or more, 0.27 or more, 0.272 or more, 0.275 or more, 0.277 or more, 0.28 or more, 0.282 or more, 0.285 or more, 0.287 or more, 0.29 or more, 0.292 or more, 0.295 or more, 0.297 or more, 0.3 or more, 0.302 or more, 0.305 or more, 0.307 or more, 0.31 or more, 0.312 or more, 0.315 or more, 0.317 or more, 0.32 or more, 0.322 or more, 0.325 or more, 0.327 or more, 0.33 or more, 0.332 or more, 0.335 or more, 0.337 or more, 0.34 or more, 0.342 or more, 0.345 or more, 0.347 or more, 0.35 or more, 0.352 or more, 0.355 or more, 0.357 or more, 0.36 or more, 0.362 or more, 0.365 or more, 0.367 or more, 0.37 or more, 0.372 or more, 0.375 or more, 0.377 or more, 0.38 or more, 0.382 or more, 0.385 or more, 0.387 or more, 0.39 or more, 0.392 or more, 0.395 or more, 0.397 or more is preferred. On the other hand, the value of “y” is preferably 0.397 or less, 0.395 or less, 0.392 or less, 0.39 or less, 0.387 or less, 0.385 or less, 0.382 or less, 0.38 or less, 0.377 or less, 0.375 or less, 0.372 or less, 0.367 or less, 0.365 or less, 0.362 or less, 0.36 or less, 0.357 or less, 0.355 or less, 0.352 or less, 0.35 or less, 0.347 or less, 0.345 or less, 0.342 or less, 0.34 or less, 0.337 or less, 0.335 or less, 0.332 or less, 0.33 or less, 0.327 or less, 0.325 or less, 0.322 or less, 0.32 or less, 0.317 or less, 0.315 or less, 0.312 or less, 0.31 or less, 0.307 or less, 0.305 or less, 0.302 or less, 0.3 or less, 0.297 or less, 0.295 or less, 0.292 or less, 0.29 or less, 0.287 or less, 0.285 or less, 0.282 or less, 0.28 or less, 0.277 or less, 0.275 or less, 0.272 or less,

[0041] 0.27 or less, 0.267 or less, 0.265 or less, 0.26 or less, 0.257 or less, 0.255 or less, 0.252 or less,

[0042] 0.25 or less, 0.247 or less, 0.245 or less, 0.242 or less, 0.24 or less, 0.237 or less, 0.235 or less,

[0043] 0.232 or less, 0.23 or less, 0.227 or less, 0.225 or less, 0.222 or less, 0.22 or less, 0.217 or less,

[0044] 0.215 or less, 0.212 or less, 0.21 or less, 0.207 or less, 0.205 or less, 0.202 or less, 0.2 or less,

[0045] 0.197 or less, 0.195 or less, 0.192 or less, 0.19 or less, 0.187 or less, 0.185 or less, 0.182 or less, 0.18 or less, 0.177 or less, 0.175 or less, 0.172 or less, 0.17 or less, 0.167 or less, 0.165 or less, 0.162 or less, 0.16 or less, 0.155 or less, 0.152 or less, 0.15 or less, 0.147 or less, 0.145 or less, 0.142 or less, 0.14 or less, 0.137 or less, 0.135 or less, 0.132 or less, 0.13 or less,

[0046] 0.127 or less, 0.125 or less, 0.122 or less, 0.12 or less, 0.117 or less, 0.115 or less, 0.112 or less, 0.11 or less, 0.107 or less, 0.105 or less, 0.102 or less, 0.1 or less, 0.095 or less, 0.09 or less, 0.085 or less, 0.08 or less, 0.075 or less, 0.07 or less, 0.065 or less, 0.06 or less, 0.055 or less, 0.05 or less, 0.045 or less, 0.04 or less, 0.035 or less, 0.03 or less, 0.025 or less, 0.02 or less, 0.015 or less, 0.01 or less, 0.0095 or less, 0.009 or less, 0.0085 or less, 0.008 or less,

[0047] 0.0075 or less, 0.007 or less, 0.0065 or less, 0.006 or less, 0.0055 or less, 0.005 or less, 0.0045 or less, 0.004 or less, 0.0035 or less, 0.003 or less, 0.0025 or less, 0.002 or less, 0.0015 or less, 0.001 or less.

[0048] The value of “z” in the general formula is not limited as long as it is within the range 0 < z < 0.1, for example, 0.001 or more, 0.0012 or more, 0.0015 or more, 0.0017 or more, 0.002 or more, 0.0022 or more, 0.0025 or more, 0.0027 or more, 0.003 or more, 0.0032 or more, 0.0035 or more, 0.0037 or more, 0.004 or more, 0.0042 or more, 0.0045 or more, 0.0047 or more, 0.005 or more, 0.0052 or more, 0.0055 or more, 0.0057 or more, 0.006 or more, 0.0062 or more, 0.0065 or more, 0.0067 or more, 0.007 or more, 0.0072 or more, 0.0075 or more, 0.0077 or more, 0.008 or more, 0.0082 or more, 0.0085 or more, 0.0087 or more, 0.009 or more, 0.0092 or more, 0.0095 or more, 0.0097 or more, 0.01 or more, 0.012 or more, 0.015 or more, 0.017 or more, 0.02 or more, 0.022 or more, 0.025 or more, 0.027 or more, 0.03 or more, 0.032 or more, 0.035 or more, 0.037 or more, 0.04 or more, 0.042 or more, 0.045 or more, 0.047 or more, 0.05 or more, 0.052 or more, 0.055 or more, 0.057 or more, 0.06 or more, 0.062 or more, 0.065 or more, 0.067 or more, 0.07 or more, 0.072 or more, 0.075 or more, 0.077 or more, 0.08 or more,

[0049] 0.082 or more, 0.085 or more, 0.087 or more, 0.09 or more, 0.092 or more, 0.095 or more,

[0050] 0.097 or more is preferred. On the other hand, the value of “z” is preferably 097 or less, 0.095 or less, 0.092 or less, 0.09 or less, 0.087 or less, 0.085 or less, 0.082 or less, 0.08 or less, 0.077 or less, 0.075 or less, 0.072 or less, 0.07 or less, 0.067 or less, 0.065 or less, 0.062 or less, 0.06 or less, 0.057 or less, 0.055 or less, 0.052 or less, 0.05 or less, 0.047 or less, 0.045 or less, 0.042 or less, 0.04 or less, 0.037 or less, 0.035 or less, 0.032 or less, 0.03 or less, 0.027 or less, 0.025 or less, 0.022 or less, 0.02 or less, 0.017 or less, 0.015 or less, 0.012 or less, 0.01 or less, 0.0097 or less, 0.0095 or less, 0.0092 or less, 0.009 or less, 0.0087 or less, 0.0085 or less,

[0051] 0.0082 or less, 0.008 or less, 0.0077 or less, 0.0075 or less, 0.0072 or less, 0.007 or less,

[0052] 0.0067 or less, 0.0065 or less, 0.0062 or less, 0.006 or less, 0.0057 or less, 0.0055 or less,

[0053] 0.0052 or less, 0.005 or less, 0.0047 or less, 0.0045 or less, 0.0042 or less, 0.004 or less,

[0054] 0.0037 or less, 0.0035 or less, 0.0032 or less, 0.003 or less, 0.0027 or less, 0.0025 or less,

[0055] 0.0022 or less, 0.002 or less, 0.0017 or less, 0.0015 or less, 0.0012 or less, 0.001 or less. In the general formula, element M is not limited to one or more elements other than Li, Ni, Co, Mn, and O. For example, Al, Ti, Mg, Zn, Nb, W, Mo, Sb, V, Cr, Ca, Fe, Ga, Sr, Y, Ru, In, Sn, Ta, Bi, Zr, and B can be used. The type of element M is determined by the type of the element. The type of element M should be selected according to the purpose of addition. When multiple elements are included as element M, the value of “w” represents the total amount of the multiple elements.

[0056] The value of “a” in the general formula is not limited as long as it is within the range of -0.5 < a < 0.5, for example, -0.5 or more, -0.45 or more, -0.4 or more, -0.35 or more, -0.30 or more, -0.25 or more, -0.2 or more, -0.15 or more, -0.1 or more, -0.075 or more, -0.05 or more, -0.025 or more, 0.001 or more, 0.0015 or more, 0.002 or more, 0.0025 or more, 0.003 or more, 0.0035 or more, 0.004 or more, 0.0045 or more, 0.005 or more, 0.0055 or more, 0.006 or more, 0.0065 or more, 0.007 or more, 0.0075 or more, 0.008 or more, 0.0085 or more, 0.009 or more, 0.0095 or more, 0.01 or more, 0.015 or more, 0.02 or more, 0.025 or more, 0.03 or more, 0.035 or more, 0.04 or more, 0.045 or more, 0.05 or more, 0.055 or more, 0.06 or more, 0.065 or more, 0.07 or more, 0.075 or more, 0.08 or more, 0.085 or more, 0.09 or more, 0.095 or more, 0.1 or more, 0.102 or more, 0.105 or more, 0.107 or more, 0.11 or more, 0.112 or more, 0.115 or more, 0.117 or more, 0.12 or more, 0.122 or more, 0.125 or more, 0.127 or more, 0.13 or more, 0.132 or more, 0.135 or more, 0.137 or more, 0.14 or more, 0.142 or more, 0.145 or more, 0.147 or more, 0.15 or more, 0.152 or more, 0.155 or more, 0.157 or more, 0.16 or more, 0.162 or more, 0.165 or more, 0.167 or more, 0.17 or more, 0.172 or more, 0.175 or more, 0.177 or more, 0.18 or more, 0.182 or more, 0.185 or more, 0.187 or more, 0.19 or more, 0.192 or more, 0.195 or more, 0.197 or more, 0.2 or more, 0.202 or more, 0.205 or more, 0.207 or more, 0.21 or more, 0.212 or more, 0.215 or more, 0.217 or more, 0.22 or more, 0.222 or more, 0.225 or more, 0.227 or more, 0.23 or more, 0.232 or more, 0.235 or more, 0.237 or more, 0.24 or more, 0.242 or more, 0.245 or more, 0.247 or more, 0.25 or more, 0.252 or more, 0.255 or more, 0.257 or more, 0.26 or more, 0.262 or more, 0.265 or more, 0.267 or more, 0.27 or more, 0.272 or more,

[0057] 0.275 or more, 0.277 or more, 0.28 or more, 0.282 or more, 0.285 or more, 0.287 or more, 0.29 or more, 0.292 or more, 0.295 or more, 0.297 or more, 0.3 or more, 0.302 or more, 0.305 or more, 0.307 or more, 0.31 or more, 0.312 or more, 0.315 or more, 0.317 or more, 0.32 or more, 0.322 or more, 0.325 or more, 0.327 or more, 0.33 or more, 0.332 or more, 0.335 or more, 0.337 or more, 0.34 or more, 0.342 or more, 0.345 or more, 0.347 or more, 0.35 or more, 0.352 or more, 0.355 or more, 0.357 or more, 0.36 or more, 0.362 or more, 0.365 or more, 0.367 or more, 0.37 or more, 0.372 or more, 0.375 or more, 0.377 or more, 0.38 or more, 0.382 or more, 0.385 or more, 0.387 or more, 0.39 or more, 0.392 or more, 0.395 or more, 0.397 or more, 0.4 or more, 0.402 or more, 0.405 or more, 0.407 or more, 0.41 or more, 0.412 or more, 0.415 or more, 0.417 or more, 0.42 or more, 0.422 or more, 0.425 or more, 0.427 or more, 0.43 or more, 0.432 or more, 0.435 or more, 0.437 or more, 0.44 or more, 0.442 or more, 0.445 or more, 0.447 or more, 0.45 or more, 0.452 or more, 0.455 or more, 0.457 or more, 0.46 or more, 0.462 or more, 0.465 or more, 0.467 or more, 0.47 or more, 0.472 or more, 0.475 or more, 0.477 or more, 0.48 or more, 0.482 or more, 0.485 or more, 0.487 or more, 0.49 or more, 0.492 or more, 0.495 or more, 0.497 or more is preferred. On the other hand, the value of “a” is preferably 0.497 or less, 0.495 or less, 0.492 or less, 0.49 or less, 0.487 or less, 0.485 or less, 0.482 or less, 0.48 or less, 0.477 or less, 0.475 or less, 0.472 or less, 0.467 or less, 0.465 or less, 0.462 or less, 0.46 or less, 0.457 or less, 0.455 or less, 0.452 or less, 0.45 or less, 0.447 or less, 0.445 or less, 0.442 or less, 0.44 or less, 0.437 or less, 0.435 or less, 0.432 or less, 0.43 or less,

[0058] 0.427 or less, 0.425 or less, 0.422 or less, 0.42 or less, 0.417 or less, 0.415 or less, 0.412 or less, 0.41 or less, 0.407 or less, 0.405 or less, 0.402 or less, 0.4 or less, 0.397 or less, 0.395 or less, 0.392 or less, 0.39 or less, 0.387 or less, 0.385 or less, 0.382 or less, 0.38 or less, 0.377 or less, 0.375 or less, 0.372 or less, 0.367 or less, 0.365 or less, 0.362 or less, 0.36 or less,

[0059] 0.357 or less, 0.355 or less, 0.352 or less, 0.35 or less, 0.347 or less, 0.345 or less, 0.342 or less, 0.34 or less, 0.337 or less, 0.335 or less, 0.332 or less, 0.33 or less, 0.327 or less, 0.325 or less, 0.322 or less, 0.32 or less, 0.317 or less, 0.315 or less, 0.312 or less, 0.31 or less, 0.307 or less, 0.305 or less, 0.302 or less, 0.3 or less, 0.297 or less, 0.295 or less, 0.292 or less, 0.29 or less, 0.287 or less, 0.285 or less, 0.282 or less, 0.28 or less, 0.277 or less, 0.275 or less,

[0060] 0.272 or less, 0.27 or less, 0.267 or less, 0.265 or less, 0.26 or less, 0.257 or less, 0.255 or less,

[0061] 0.252 or less, 0.25 or less, 0.247 or less, 0.245 or less, 0.242 or less, 0.24 or less, 0.237 or less,

[0062] 0.235 or less, 0.232 or less, 0.23 or less, 0.227 or less, 0.225 or less, 0.222 or less, 0.22 or less,

[0063] 0.217 or less, 0.215 or less, 0.212 or less, 0.21 or less, 0.207 or less, 0.205 or less, 0.202 or less, 0.2 or less, 0.197 or less, 0.195 or less, 0.192 or less, 0.19 or less, 0.187 or less, 0.185 or less, 0.182 or less, 0.18 or less, 0.177 or less, 0.175 or less, 0.172 or less, 0.17 or less, 0.167 or less, 0.165 or less, 0.162 or less, 0.16 or less, 0.155 or less, 0.152 or less, 0.15 or less, 0.147 or less, 0.145 or less, 0.142 or less, 0.14 or less, 0.137 or less, 0.135 or less, 0.132 or less, 0.13 or less, 0.127 or less, 0.125 or less, 0.122 or less, 0.12 or less, 0.117 or less, 0.115 or less, 0.112 or less, 0.11 or less, 0.107 or less, 0.105 or less, 0.102 or less, 0.1 or less, 0.095 or less, 0.09 or less, 0.085 or less, 0.08 or less, 0.075 or less, 0.07 or less, 0.065 or less, 0.06 or less, 0.055 or less, 0.05 or less, 0.045 or less, 0.04 or less, 0.035 or less, 0.03 or less, 0.025 or less, 0.02 or less, 0.015 or less, 0.01 or less, 0.0095 or less, 0.009 or less, 0.0085 or less, 0.008 or less, 0.0075 or less, 0.007 or less, 0.0065 or less, 0.006 or less, 0.0055 or less, 0.005 or less, 0.0045 or less, 0.004 or less, 0.0035 or less, 0.003 or less, 0.0025 or less, 0.002 or less, 0.0015 or less, 0.001 or less.

[0064] The metal composite hydroxide powder may contain one or two or more metal composite hydroxides represented by the general formula Nii-x-y-zCoxMnyMz(OH)2+a (in the formula, M is an element other than Li, Ni, Co, Mn and O, 0<x<0.4, 0<y<0.4, 0<z<0.1 , -0.5<a<0.5). One or two or more metal complex hydroxides represented by the above formula (-0.5 < a < 0.5, -0.5 < a < 0.5) may be contained, and compounds other than metal complex hydroxides represented by the above formula may be contained, for example, 0% or more (including cases where compounds other than metal complex hydroxides are not contained) on a mass basis), 10% or less, 5% or less, 2% or less, 1% or less may be contained.

[0065] The BET specific surface area of metal complex hydroxide powder is not limited, but should be 1 m2 / g or more, 2 m2 / g or more, 3 m2 / g or more, or 4 m2 / g or more. On the other hand, the BET specific surface area of the metal complex hydroxide powder should be 15 m2 / g or less, 14 m2 / g or less, 13 m2 / g or less, 12 m2 / g or less, 11 m2 / g or less, 10 m2 / g or less, 9 m2 / g or less, 8 m2 / g or less, 7 m2 / g or less, 6 m2 / g or less.

[0066] When the particle diameter corresponding to the largest peak top of the particle size frequency distribution on a volume basis of secondary particles is Dt, among the secondary particles with a particle diameter of Dtor morel .2 Dtor less, the primary particles with a major axis length of 1 pmor more on a number basis in the reflection electron image of the cross section obtained using a scanning electron microscope 10% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more.

[0067] When the particle diameter corresponding to the largest peak top of the particle size frequency distribution on a volume basis of secondary particles is Dt, among the secondary particles with a particle diameter of Dtor more 1.2 Dtor less, the primary particles with a major axis length of 2pmor more on a number basis in the reflection electron image of the cross section obtained using scanning electron microscope 8% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more on a number basis should be accounted for.

[0068] The particle diameter Dt corresponding to the largest peak top is determined by creating a volume-based particle size distribution by the wet laser method using a laser particle size analyzer (Microtrac HRA, Nikkiso Co., Ltd.) and determining the particle diameter corresponding to the largest peak top.

[0069] The length of the primary particles of the metal complex hydroxide sample is measured as shown below. First, the metal composite hydroxide sample is hardened with epoxy resin, and the particle cross section is formed by ion beam using a cross-section polisher (IB-19530CP: JEOL Ltd.). Then, a field emission scanning electron microscope (JSM-7100F: JEOL Ltd.) is used to take images at an acceleration voltage of 3 kV and magnification of 3000 to 2000 times. For the secondary particles, 100 particles are extracted whose diameters are in the range of Dtor more than 1.2 Dtor less with respect to the particle diameter Dt corresponding to the largest peak top obtained by particle size distribution measurement based on a volume standard.

[0070] For all particles for which the outline of the primary particle can be seen in the secondary particles in the electron micrograph obtained by reflection electron image, the grain boundary of the primary particle within the secondary particle is depicted using Paint, which is included in Microsoft Windows, and image processing software (e.g., Imaged) is used on the image depicting the grain boundary. The image of the grain boundary is binarized using image processing software (e.g., Imaged, etc.), and the length of the particle in the major axis direction is calculated. From the obtained length data of particles in the long axis direction, a kernel density distribution (based on the number of particles) is calculated using the standard normal distribution as the kernel function.

[0071] The pore volume of the metal composite hydroxide powder with a pore diameter of 0.06 pmor less is not limited as long as it is 0.15 mL / g or less, for example, 0.14 mL / g or less, 0.13 mL / g or less, 0.12 mL / g or less, 0.11 mL / g or less, 0.1 mL / g or less, and 0.2 mL / g or less. 0 ml_ / g or less is preferred. The pore volume of the metal composite hydroxide powder with a pore diameter of 0.06 pmor less should be 0 mL / g or more, 0.01 mL / g or more, and 0.02 mL / g or more. As for the tap density of the metal composite hydroxide powder, it is not particularly limited, but for example, 1 g / cc or more, 1.1 g / cc or more, 1.2 g / cc or more, 1.3 g / cc or more, 1.4 g / cc or more, 1.5 g / cc or more, 1.6 g / cc or more, 1.7 g / cc or more, 1.8 g / cc or more, and 1.9 g / cc or more. On the other hand, the tapped density of the metal composite hydroxide powder is not limited, but should be 4 g / cc or less, 3.5 g / cc or less, 3 g / cc or less, 2.7 g / cc or less, 2.5 g / cc or less, 2.4 g / cc or less, and 2.3 g / cc or less. The following is a list of the most preferable.

[0072] The full width at half maximum (FWHM) of the (001) plane in the X-ray diffraction pattern of the metal complex hydroxide powder obtained by X-ray diffraction measurement is not particularly limited, but is preferably 0.2°or more, 0.25°or more, 0.3°or more. On the other hand, the full width at half maximum (FWHM) of the (001) plane is preferably 0.7° or less, 0.65° or less, 0.6° or less, 0.55° or less, 0.5° or less, 0.45° or less, 0.4° or less, 0.39° or less, 0.38° or less, 0.37° or less, 0.36° or less and 0.35°or less.

[0073] The full width at half maximum (FWHM) of the (100) plane in the X-ray diffraction pattern of the metal complex hydroxide powder obtained by X-ray diffraction measurement is not particularly limited, but 0.3° or more, 0.35° or more, and 0.4° or more are preferred. On the other hand, the full width at half maximum (FWHM) of the (100) plane should be 0.75° or less, 0.7° or less, 0.69° or less, 0.68° or less, 0.67° or less, 0.66° or less, 0.65° or less.

[0074] The full width at half maximum (FWHM) of the (101) plane in the X-ray diffraction pattern of the metal complex hydroxide powder obtained by X-ray diffraction measurement is not limited, but is preferably 0.5° or more, 0.55° or more, 0.6° or more, and 0.65° or more. On the other hand, the full width at half maximum (FWHM) of the (101) plane should be 1.5° or less, 1.4° or less, 1.3° or less, 1.2° or less, 1.1° or less, 1.0° or less, 0.97° or less, 0.95° or less, 0.9° or less is preferred.

[0075] The manufacturing method of the metal composite hydroxide powder is described below.

[0076] < Production method of metal composite hydroxide powder>

[0077] For example, an aqueous solution containing various metal elements and aqueous solutions of compounds containing other elements according to the composition of the composite oxide to be produced is dropped into a reaction tank in which an alkaline solution such as a sodium hydroxide solution and an ammonia solution is stirred as the mother solution. The method of coprecipitation by wet reaction can be used. Even if metal composite hydroxide powder is produced by a method other than this method, as long as it has the composition described above, the issues of the present disclosure can be solved.

[0078] In the production of metal composite hydroxide powder, it is preferable to make the oxygen concentration in the reaction tank system and solution as low as possible by introducing an inert gas (preferably nitrogen gas industrially) to create a nitrogen atmosphere in the reaction tank from the state where the alkaline solution as the mother liquor is prepared. If the oxygen concentration is too high, there is a risk that the coprecipitated hydroxide may be over-oxidized by the remaining predetermined amount or more of oxygen, or the formation of agglomerates may be hindered by crystallization. As an aqueous solution of an element as a source of an element constituting a metal composite hydroxide powder, there is no particular limitation, but it is preferable to use, for example, an acidic aqueous solution, and it is more preferable to use a sulfuric acid solution. One or two or more aqueous solutions of this element can be used.

[0079] The elemental source should be adjusted to the type and stoichiometric ratio of the element according to the composition of the lithium metal oxide to be produced, and is not limited to any particular type.

[0080] As a nickel compound, one or two types or more selected from nickel sulfate, nickel oxide, nickel hydroxide, nickel nitrate, nickel carbonate, nickel chloride, nickel iodide, and metallic nickel, etc., can be used, although there is no particular limitation.

[0081] As cobalt compounds, one or two or more of the following can be used: cobalt sulfate, cobalt oxide, cobalt hydroxide, cobalt nitrate, cobalt carbonate, cobalt chloride, cobalt iodide, and cobalt metal.

[0082] As manganese compounds, one or two or more of the following may be used: manganese sulfate, manganese oxide, manganese hydroxide, manganese nitrate, manganese carbonate, manganese chloride, manganese iodide, and manganese metal.

[0083] As aluminum compounds, although not particularly limited, one or two or more of the following can be used: aluminum sulfate, aluminum oxide, aluminum hydroxide, aluminum nitrate, aluminum carbonate, aluminum chloride, aluminum iodide, sodium aluminate, and metallic aluminum, etc. More can be used.

[0084] As titanium compounds, one or two or more of the following can be used: titanyl sulfate, titanium oxide, titanium hydroxide, titanium nitrate, titanium carbonate, titanium chloride, titanium iodide, and metallic titanium.

[0085] As iron compounds, one or two or more of the following can be used: iron sulfate, iron oxide, iron hydroxide, iron nitrate, iron carbonate, iron chloride, iron iodide, and metallic iron.

[0086] As niobium compounds, one or more of niobium oxide, niobium chloride, lithium niobate, niobium iodide, etc. can be used, although there is no particular limitation.

[0087] As tungsten compounds, although not particularly limited, one or two or more of the following may be used, selected from tungsten oxide, sodium tungstate, ammonium paratungstate, hexacarbonyl tungsten, tungsten sulfide, etc.

[0088] As magnesium compounds, one or two or more of magnesium sulfate, magnesium oxide, magnesium hydroxide, magnesium nitrate, magnesium carbonate, magnesium chloride, magnesium iodide, and metallic magnesium, etc., can be used, although there is no particular limitation. Magnesium nitrate, magnesium chloride, magnesium iodide, and magnesium metal. As zinc compounds, one or two or more of the following can be used: zinc sulfate, zinc oxide, zinc hydroxide, zinc nitrate, zinc carbonate, zinc chloride, zinc iodide, and metallic zinc, among others.

[0089] For other elements, one or two or more of the following can also be used: sulfate, oxide, hydroxide, nitrate, carbonate, chloride, iodide, and metal.

[0090] As for the proportion of each compound, the amount of each element should be adjusted according to the composition of the lithium metal composite oxide to be produced.

[0091] The appropriate pH range for producing metal composite hydroxide powder is not particularly limited and should be determined so as to obtain the secondary particle diameter, degree of sparseness, and other shapes to be produced, and should generally be in the range of 10 to 13.

[0092] The metal composite hydroxide powder obtained by the wet reaction should be washed, dehydrated, and then dried.

[0093] By applying washing treatment to the metal composite hydroxide powder, impurities such as sulfate roots, carbonate roots, and sodium content that are incorporated into the agglomerated particles or adhered to the surface layer during the reaction can be washed away. The washing process can be performed by Nutsche washing using a Buchner funnel if the amount is small, or by pumping the post-reaction suspension through a press filter, washing with water, and dehydrating. In the washing process, for example, pure water, sodium hydroxide solution, sodium carbonate solution, etc. can be used, but from an industrial standpoint, pure water is preferred. However, if there is a large amount of residual sulfate root, a sodium hydroxide solution with a pH controlled according to the residual amount may be used.

[0094] (2) Temporary Baking Process

[0095] The pre-sintering process is a process to pre-sinter the metal composite hydroxide powder. The provisional sintering process is not an essential process for the lithium metal composite oxide production method of the present disclosure.

[0096] Thus, the metal composite hydroxide powder can be calcined and dehydrated by provisional sintering before mixing with the lithium compound.

[0097] Although the provisional sintering conditions are not particularly limited, for example, it is preferable to perform the process under an oxidizing atmosphere, at a heating temperature of 200°C to 700°C, and a heating time of 1 to 6 hours. The heating temperature is the temperature of the portion having the highest temperature in the metal composite hydroxide powder, and the heating time is the time during which the temperature of the portion having the highest temperature is maintained in the temperature range described above. By undergoing the temporary sintering process, impurities remaining in the metal composite hydroxide powder can be adequately removed, and a temporary sintered product can be obtained. The heating temperature is the temperature of the portion having the highest temperature in the heated object when the object is heated and rises, and the heating time is the time in which the temperature of the portion having the highest temperature in the heated object is maintained in the temperature range described above (the same shall apply in the or less process).

[0098] (3) Mixing process

[0099] A mixture is prepared by mixing the composite metal hydroxide powder prepared in the precursor preparation process and / or the tentative calcination product prepared in the tentative calcination process with the lithium source in a predetermined ratio. The mixing method is not limited, but for example, weighing the composite metal hydroxide and / or sintered powder and the lithium compound powder as the lithium source to a predetermined ratio and mixing them in a dry process, or mixing the composite metal hydroxide and / or sintered powder and the lithium source solution in a predetermined ratio. The method may be to dry all of the suspension obtained by mixing the metal composite hydroxide and / or pseudo-sinter with an aqueous solution of the lithium source in a predetermined ratio. The mixing process is not an essential process for the method of producing the lithium metal composite oxide of the embodiment of the present disclosure.

[0100] As lithium compounds, various lithium salts can be used without any particular limitation. Specifically, one or more of the following lithium compounds can be used: anhydrous lithium hydroxide, lithium hydroxide hydrate, lithium nitrate, lithium carbonate, lithium acetate, lithium bromide, lithium chloride, lithium citrate, lithium fluoride, lithium iodide, lithium lactate, lithium oxalate, lithium phosphate, lithium pyruvate One or more of the following can be used: lithium chloride, lithium citrate, lithium fluoride, lithium iodide, lithium lactate, lithium oxalate, lithium phosphate, lithium pyruvate, lithium sulfate and lithium oxide. Among these, one or more selected from anhydrous lithium hydroxide and lithium hydroxide hydrate is preferred.

[0101] The blending ratio of the lithium source to the metal composite hydroxide powder and / or the pseudosintered product is not particularly limited, but should be adjusted so that the total amount of each element and the total amount of each element become the desired ratio, depending on the composition of the lithium metal composite oxide to be produced.

[0102] (4) Calcination process

[0103] The calcination process is a process in which the mixture of the metal composite hydroxide powder and / or metal composite compound and the lithium source is calcined at a temperature between 700°C and 950°C.

[0104] In the calcination process for producing lithium metal composite oxides containing at least nickel, lithiation reaction and crystal growth take place. The lithiation reaction requires a certain oxygen partial pressure. The lithiation reaction lithiates the metal composite hydroxide as a raw material to obtain lithium metal composite oxide. The temperature is then increased to a predetermined temperature to promote crystal growth of the lithium metal composite oxide.

[0105] The heating temperature in calcination is not particularly limited, but is preferably 700°C to 950°C, 700°C to 930°C, and 710°C to 900°C. The firing time should be, for example, 1 to 24 hours, 1 to 20 hours, 1 to 15 hours, 1 to 10 hours, 2 to 9 hours, and 3 to 8 hours. <Pre-firing>

[0106] Calcination is generally performed by filling a vessel such as a crucible or a saggar with the mixture obtained by mixing the metal composite hydroxide powder and / or the composite metal compound and the lithium source in a mixing machine in the mixing process. Especially in the lithiation reaction, as the mixed powder gets closer to the bottom of the vessel in which it is filled, it becomes more difficult to discharge the gases generated to the outside and diffuse the required oxygen concentration. As a result, uniformity of reaction and control of primary particle size may become difficult.

[0107] Therefore, when producing the lithium metal composite oxide of the embodiment of the present disclosure, it is preferable to use a two-step calcination method in which pre-calcination is performed under or less predetermined conditions, followed by main calcination under predetermined conditions. However, the pre-firing is not an essential process.

[0108] In this pre-firing, it is especially desirable to incorporate a firing method that accelerates the lithiation reaction. Specifically, a method that makes the mixture more susceptible to heat, easily expels gases produced from the lithium source, and diffuses gases with high oxygen partial pressure into the mixture (within the particles) can be cited. For example, it is possible to achieve the desired properties by pre-firing a smaller amount of the mixture or by pre-firing while flowing.

[0109] For pre-firing the mixture, the mixture can be filled into a saggars or crucibles and fired using a static furnace, roller hearth kiln, or pusher furnace, or a rotary kiln that fires the mixture while it is flowing can be used.

[0110] The heating temperature in the pre-firing is not limited as long as it is lower than the heating temperature in the main firing described below, and should be adjusted according to the type of lithium compound used to prepare the mixture. This ensures that the metal composite hydroxide and / or composite metal compound in the mixture reacts with the lithium compound, and that the lithiation reaction proceeds reliably and uniformly to obtain the desired lithium metal composite oxide without generating different phases.

[0111] The atmosphere for pre-firing is not limited, and can be any oxidizing atmosphere in which the lithiation reaction progresses reliably and uniformly. For example, it is preferable to use an atmosphere (oxygen concentration: 21 vol%), a calcined oxidizing gas atmosphere with a carbon dioxide concentration of 30 ppmor less, or an oxygen atmosphere with an oxygen concentration of 80 vol% or more or 90 vol% or more.

[0112] The time for pre-calcination is not limited and should be such that the lithiation reaction proceeds reliably and uniformly. Specifically, for example, 1 to 10 hours and 2 to 8 hours are preferred.

[0113] <Main firing> The pre-fired mixture is subjected to main firing to allow crystal and particle growth at a higher temperature. In this process, it is necessary to reliably and uniformly promote crystal growth to obtain a lithium metal composite oxide with the desired crystal structure.

[0114] The atmosphere for the main calcination is not particularly limited, and should be an atmosphere with an oxygen partial pressure that ensures reliable and uniform crystal growth and does not reduce the transition metal contained in the mixture to be calcined, and preferably with a low moisture content and low carbon dioxide gas concentration. For example, it is preferable to use an oxidizing gas atmosphere of calcination where the atmosphere (oxygen concentration: 21 vol%) and carbon dioxide concentration is 30 ppmor less, or an oxygen atmosphere where the oxygen concentration is preferably 80 vol%or more, 90 vol% or more.

[0115] The temperature of the main calcination process is not limited as long as it is higher than the temperature of the pre-calcination process, and can be adjusted depending on the composition of the lithium metal composite oxide to be obtained. For example, it is preferable to adjust the maximum temperature to a range of 700°C-950°C, 700°C-930°C, or 710°C-900°C. By keeping the maximum temperature within the required range, a lithium metal composite oxide with a desired crystal structure with reduced unreacted components can be obtained, and the reduction of battery characteristics of a nonaqueous electrolyte secondary battery using the obtained lithium metal composite oxide as a cathode can be prevented. For example, when obtaining a lithium metal composite oxide with Ni content of 20 to 80 mol% in elements other than Li, it is preferable to sinter the mixture at a temperature where the maximum temperature of the mixture does not exceed 950°C.

[0116] The time for this calcination is not limited and should be sufficient to form a lithium metal composite oxide with the desired crystal structure. For example, 1-15 hours, 2-12 hours, and 2- 10 hours are preferred.

[0117] (5) Washing process

[0118] The washing process is a process in which the lithium metal composite oxide obtained by calcination in the sintering process is washed with water. The washing process is not an essential component.

[0119] The lithium metal composite oxide obtained in the calcination process may contain unreacted lithium compounds or lithium compounds that appear on the particle surface layer from the crystal structure during the calcination process as impurities. Therefore, in order to remove or reduce these impurities, for example, they can be washed with water and heat-treated.

[0120] (6) Surface treatment process

[0121] The surface treatment process is a process in which the lithium metal composite oxide obtained in the calcination process or washing process is subjected to surface treatment. The surface treatment process is not an essential component.

[0122] By adding and mixing a predetermined elemental compound to the composite oxide obtained in the calcination or washing process and applying heat treatment, the surface of the primary and / or secondary particles of the lithium metal composite oxide can be surface treated with a compound of lithium and the added element, and the lithium compound remaining on the surface layer of the particles can be reduced. The surface treatment can reduce the lithium compounds remaining on the surface layer of the particles, improve the lithium ion conductivity, and reduce the reaction resistance.

[0123] The elemental compounds added for the surface treatment described above can be selected from aluminum compounds, boron compounds, tungsten compounds, manganese compounds, cobalt compounds, phosphorus compounds, niobium compounds, strontium compounds, antimony compounds, zirconium compounds, titanium compounds, etc., and one type or more can be used.

[0124] The lithium metal composite oxide produced by the or more process has, for example, the general formula LiaNi1-x-y-zCoxMnyMzO2+a (in the formula, M is one or more elements other than Li, Ni, Co, Mn, and O) M is 0.90 < a < 1.15, 0 < x < 0.4, 0 < y < 0.4, 0 < z < 0.1 , and -0.5 < a

[0125] < 0.5). The numerical values of x, y, and z and the type of element M are the same as for the metal composite hydroxides described above, and are therefore omitted here.

[0126] The value of “a” in the general formula is not limited as long as it is within the range of 0.90 < a

[0127] < 1.15, for example, 0.905 or more, 0.91 or more, 0.915 or more, 0.92 or more, 0.925 or more, 0.93 or more, 0.935 or more, 0.94 or more, 0.945 or more, 0.95 or more, 0.955 or more, 0.96 or more, 0.965 or more, 0.97 or more, 0.975 or more, 0.98 or more, 0.985 or more, 0.99 or more, 0.995 or more, 1 or more, 1.005 or more, 1.01 or more, 1.015 or more, 1.02 or more, 1.025 or more, 1.03 or more, 1.035 or more, 1.04 or more, 1.045 or more, 1.05 or more, 1.055 or more,

[0128] 1.06 or more, 1.065 or more, 1.07 or more, 1 .075 or more, 1.08 or more, 1 .085 or more, 1.09 or more, 1.095 or more, 1.1 or more, 1.105 or more, 1.11 or more, 1.115 or more, 1.12 or more, 1.125 or more, 1.13 or more, 1.135 or more, 1.14 or more, 1.145 or more, 1.15 or more is preferred. On the other hand, the value of “a” is preferably 1.15 or less, 1.145 or less, 1.14 or less, 1.135 or less, 1.13 or less, 1.125 or less, 1.12 or less, 1.115 or less, 1.11 or less, 1.105 or less, 1.1 or less, 1.095 or less, 1.09 or less, 1.085 or less, 1.08 or less, 1.075 or less, 1.07 or less, 1.065 or less, 1.06 or less, 1.055 or less, 1.05 or less, 1.045 or less, 1 .04 or less, 1.035 or less, 1.03 or less, 1.025 or less, 1.02 or less, 1.015 or less, 1.01 or less, 1.005 or less, 1 or less, 0.995 or less, 0.99 or less, 0.985 or less, 0.98 or less, 0.975 or less, 0.97 or less, 0.965 or less, 0.96 or less, 0.955 or less, 0.95 or less, 0.945 or less, 0.94 or less, 0.935 or less, 0.93 or less, 0.925 or less, 0.92 or less, 0.915 or less, 0.91 or less, 0.905 or less.

[0129] The lithium metal composite oxide produced by the manufacturing method of the embodiment of the present disclosure can be used as a cathode active material for a non-aqueous electrolyte secondary battery. Here, we describe a non-aqueous electrolyte secondary battery using lithium metal composite oxide. This non-aqueous electrolyte secondary battery is equipped with a positive electrode containing the above-mentioned lithium metal composite oxide as a positive active material, and the non-aqueous electrolyte secondary battery consists of a positive electrode, a negative electrode, and an electrolyte solution containing electrolyte. In manufacturing the cathode, a conductive agent and a binder are added to the lithium metal composite oxide of the embodiment of the present disclosure and mixed according to the usual method. As the conductive agent, acetylene black, carbon black, graphite, etc. are preferably used, for example. Polytetrafluoroethylene, polyvinylidene fluoride, etc., for example, are preferred as the binder.

[0130] As the negative electrode, although not particularly limited, one or more non-metallic or metallic elements selected from Si, Al, Sn, Pb, Zn, Bi, and Cd, alloys containing them, or chalcogen compounds containing them, as well as negative electrode active materials such as lithium metal, graphite, low crystallinity carbon materials, etc. can be used. The use of chalcogenide compounds containing them is also possible.

[0131] The solvent of the electrolytic solution is not limited, but an organic solvent containing one or more of carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, or ethers such as dimethoxyethane can be used.

[0132] As an electrolyte, in addition to lithium hexafluorophosphate (LiPF6), one or more of lithium salts such as lithium perchlorate and lithium tetrafluoroborate can be used by dissolving them in a solvent.

[0133] EMBODIMENT

[0134] The following describes an embodiment of the present disclosure. The disclosure is not limited in any way by the description of the embodiment, but may be implemented with appropriate changes.

[0135] Embodiment 1

[0136] A method for producing a lithium metal composite oxide, the method comprising a step for firing a mixture of a metal composite hydroxide powder and a lithium source at 700°C-950°C, wherein: the metal composite hydroxide powder contains at least nickel, and includes secondary particles that are formed by aggregation of primary particles; and when a particle diameter corresponding to a maximum peak top of the volume-based particle diameter frequency distribution of the secondary particles is defined as Dt, in a backscattered electron image of a cross section obtained using a scanning electron microscope, primary particles having a major axis length of 1 pm or more account for 10% or more, in terms of number of particles, of at least 30%, in terms of number of particles, of secondary particles having a particle diameter of Dt-1.2Dt, and the volume of pores having a pore diameter of 0.06 pm or less is 0.15 ml_ / g or less.

[0137] Embodiment 2

[0138] A method for producing a lithium metal composite oxide, the method comprising a step for calcining a metal composite hydroxide powder at from 200°C or more to less than 700°C to obtain a calcination product, and a step for firing a mixture of the calcination product and a lithium source at 700°C-950°C, wherein: the metal composite hydroxide powder contains at least nickel, and includes secondary particles that are formed by aggregation of primary particles; and when a particle diameter corresponding to a maximum peak top of the volume- based particle diameter frequency distribution of the secondary particles is defined as Dt, in a backscattered electron image of a cross section obtained using a scanning electron microscope, primary particles having a major axis length of 1 pm or more account for 10% or more, in terms of number of particles, of at least 30%, in terms of number of particles, of secondary particles having a particle diameter of Dt-1.2Dt, and the volume of pores having a pore diameter of 0.06 pm or less is 0.15 ml_ / g or less.

[0139] Embodiment 3

[0140] The method for producing a lithium metal composite oxide according to either of embodiments 1 and 2, wherein the metal composite hydroxide powder includes a metal composite hydroxide represented by the general formula Nii.x.y.zCox nyz(OH)2+a (where M is an element other than Li, Ni, Co, Mn and O, and the relationships 0 < x < 0.4, 0 < y < 0.4, 0 < z < 0.1, and -0.5 < a < 0.5 are satisfied).

[0141] Embodiment 4

[0142] The method for producing a lithium metal composite oxide according to either of embodiments 1 and 2, wherein in a backscattered electron image of a cross section obtained using a scanning electron microscope, primary particles having a major axis length of 2 pm or more account for 8% or more, in terms of number of particles, of at least 30%, in terms of number of particles, of secondary particles having a particle diameter of Dt-1.2Dt.

[0143] Embodiment 5

[0144] The method for producing a lithium metal composite oxide according to either of embodiments 1 and 2, wherein the BET specific surface area of the metal composite hydroxide powder is 1 m2 / g-15 m2 / g.

[0145] Embodiment 6

[0146] A metal composite hydroxide powder containing at least nickel, and including secondary particles that are formed by aggregation of primary particles, wherein, when a particle diameter corresponding to a maximum peak top of the volume-based particle diameter frequency distribution of the secondary particles is defined as Dt, in a backscattered electron image of a cross section obtained using a scanning electron microscope, primary particles having a major axis length of 1 pm or more account for 10% or more, in terms of number of particles, of at least 30%, in terms of number of particles, of secondary particles having a particle diameter of Dt-1.2Dt, and the volume of pores having a pore diameter of 0.06 pm or less is 0.15 ml_ / g or less.

[0147] EXAMPLE

[0148] The disclosure is not limited by these examples.

[0149] Example 1

[0150] Nucleation stage: Nickel sulfate solution, cobalt sulfate solution, and manganese sulfate solution were mixed so that the ratio of Ni to Co to Mn (molar ratio) was Ni:Co:Mn = 55:20:25 to obtain a mixed solution. Ten liters of pure water was added to the reaction tank, and 200 g of ammonia water was added. Sodium hydroxide solution was then added to the reaction tank so that the pH was 12, and prepared as the reaction matrix. The reaction tank was purged with nitrogen gas at a flow rate of 0.7 L / min to create a nitrogen atmosphere in the reaction tank. The nitrogen atmosphere was maintained until the reaction was completed. While stirring the solution in the reaction tank, the prepared mixed aqueous solution was added dropwise to prepare the liquid medium containing the seed crystals.

[0151] Crystallization stage: After the seed formation stage, sodium hydroxide, aqueous ammonia, and the mixed aqueous solution were fed into the reaction tank in the prescribed proportions to carry out the crystallization reaction. During the reaction, the volume of the reaction tank was controlled to be constant. During the crystallization stage, the pH in the reaction tank was controlled to be maintained at 11.7.

[0152] During the reaction, the drop rate of raw material was kept constant and the average particle diameter D50 was kept at 17 pm, while confirming that no secondary nuclei (seed nuclei) were generated by measuring the particle size distribution and BET specific surface area by sampling over time.

[0153] After the drop of raw materials was completed, the reaction was stirred for 1 hour to obtain coprecipitates in which Ni, Co, and Mn crystallized to form agglomerated particles. The slurry in the reactor was then washed with pure water using a Buchner funnel to reduce residual impurities by Nutsche washing, followed by solid-liquid separation, and the coprecipitates in a cake state were dried at 110°C for 12 hours under air environment to obtain a metal composite hydroxide sample. The average particle diameter D50 of the obtained metal complex hydroxide on a volume basis was 16.6 pm.

[0154] The metal composite hydroxide obtained as described in or more above was subjected to a temporary sintering process in which it was heat-treated at 300°C for 4 hours under an atmospheric environment to obtain a metal composite compound. The obtained metal composite compound, lithium carbonate, and zirconium oxide were weighed and mixed so that Li / (Ni + Co + Mn) = 1.035 and Zr / (Ni + Co + Mn + Zr) = 0.45 mol% in the final lithium metal composite oxide to be produced. The mixture was then heat-treated at 780°C for 3 hours under atmospheric conditions (oxygen concentration: 21 vol%), and further calcined at 880°C for 6 hours under atmospheric conditions (oxygen concentration: 21 vol%). The resulting calcined product was pulverized to obtain lithium-nickel composite oxide.

[0155] The obtained lithium metal composite oxide was mixed with boric acid powder so that the amount of B in the final lithium metal composite oxide sample was 1000 ppm, and heat-treated at 350°C for 2 hours under an oxygen atmosphere (oxygen concentration: 92 vol%) to obtain a cathode active material sample.

[0156] Example 2

[0157] In Example 1 , during the crystallization stage, the pH in the reaction tank was controlled to be maintained at 11.5 at all times during the crystallization stage. During the reaction, it was confirmed that no secondary nuclei (seed nuclei) were generated by sampling and measuring the particle size distribution and BET specific surface area over time. The drop rate was reduced step by step as the particle size grew by checking the surface morphology with SEM images, and finally the rate was set to 1 / 5 of the rate at the start of the drop. The reaction was carried out so that the average particle diameter D50 was 17 pm or more, the lithium metal composite oxide sample was obtained in the same way as in Example 1. The average particle diameter D50 of the obtained metal composite hydroxide on a volume basis was 17.0 pm.

[0158] The metal composite hydroxide obtained as described in or more above was subjected to a temporary sintering process in which it was heat-treated at 300°C for 4 hours under an atmospheric environment to obtain a metal composite compound. The composite oxide sample of Example 2 was obtained in the same manner as in Example 1 , except that the obtained metal composite compound was weighed and mixed with lithium carbonate and zirconium oxide so that the final cathode active material was Li / (Ni + Co + Mn) = 1.050 and Zr / (Ni + Co + Mn + Zr) = 0.45 mol%. Example 2 composite oxide sample was obtained in the same manner as in Example 1.

[0159] Comparative Example 1

[0160] A metal composite hydroxide sample was obtained in the same manner as in Example 1, except that the pH was raised to 0.25 and the material dropping rate was increased in steps during the crystallization stage in Example 1. The average particle diameter D50 of the obtained metal composite hydroxide on a volume basis was 16.2 pm.

[0161] The subsequent operations were performed in the same manner as in Example 1 to obtain lithium metal composite oxide.

[0162] The samples of Examples 1 and 2 and Comparative Example 1 were evaluated by the method as follows.

[0163] Composition analysis of the metal composite hydroxide sample and the lithium metal composite oxide sample: The composition of the metal complex hydroxide and lithium metal complex oxide samples was determined by the following method. 0.2 g of each sample was dissolved in 25 ml of 20% hydrochloric acid solution by heating, and after cooling, the solution was transferred to a 100 ml measuring flask and pure water was added to make a conditioned solution. The obtained adjustment solution was subjected to ICP-AES (Optima 8300, Perkin Elmer Japan Co., Ltd.) for elemental determination.

[0164] Tap density of metal composite hydroxide samples was measured by tapping 500 times using a tap denser.

[0165] Particle diameter (Dt) corresponding to the largest peak top of the metal composite hydroxide sample was determined using a laser particle size distribution analyzer (Microtrac HRA, Nikkiso Co., Ltd.), and a wet laser method to create a volume-based particle size distribution.

[0166] Full width at half maximum (FWHM) of metal composite hydroxide samples by XRD diffraction were obtained using an X-ray diffractometer [SmartLab, Rigaku Corporation] under or less X-ray diffraction conditions, and then the XRD diffraction data were used to calculate the FWHM of the metal complex hydroxide samples using the "R. A. Young, ed.", Oxford University Press (1992)" and performed Rietveld analysis. For the FWHM (full width at half maximum), the values at the (001), (100) and (101) peaks were used when the obtained XRD diffraction was indexed as the space group: P-3m1 .

[0167] (X-ray diffraction conditions)

[0168] X-ray source: Cu-Ka

[0169] Accelerating voltage and current: 45 kV and 200 mA

[0170] Sampling width: 0.02 deg.

[0171] Scanning width: 5deg. to 80deg.

[0172] Scanning speed: 1.0 step / sec.

[0173] Divergence slit: 2 / 3deg.

[0174] Receiving slit width: 0.15mm

[0175] Scattering slit: 2 / 3deg.

[0176] Scattering slit width: 2 / 3deg.

[0177] Pore distribution of metal complex hydroxide samples was measured by the mercury injection method using Autopore V9620 (Micromeritics).

[0178] Conditions for mercury injection method:

[0179] Pretreatment: No pretreatment.

[0180] Measurement: Pore distribution was obtained for pore diameters from about 0.0036 to 200 pm.

[0181] Pore diameter was calculated using Washburn's formula shown in or less.

[0182] PD = -4ocos0

[0183] (In the formula, P: pressure, o: surface tension of mercury, D: pore diameter, 0: contact angle between mercury and sample)

[0184] Measurement conditions:

[0185] Surface tension of mercury: 480 dynes / cm

[0186] Contact angle between mercury and sample: 140 deg.

[0187] Method for measuring the length of the primary particles of a metal composite hydroxide sample: The length of the primary particles of the metal complex hydroxide sample was measured as shown below. First, the metal composite hydroxide sample was hardened with epoxy resin, and the particle cross section was formed by ion beam using a cross-section polisher (IB-19530CP, JEOL Ltd.). The images were then taken using a field emission scanning electron microscope (JSM-7100F, JEOL Ltd.) at an acceleration voltage of 3 kV and magnification of 3000 to 2000 times. For the secondary particles, 100 particles were selected whose diameters were in the range of Dt more than 1.2 Dt less than the particle diameter Dt corresponding to the largest peak top obtained by the particle size distribution measurement based on the volume standard.

[0188] For all particles for which the outline of the primary particle can be seen in the secondary particles in the electron micrographs obtained from the reflection electron images, the grain boundaries of the primary particles within the secondary particles were depicted using Paint, which is included with Microsoft Windows, and image processing software (e.g., Imaged) was used for the images depicting the grain boundaries. The length of the particle in the long axis direction was calculated by binarizing the image of the grain boundary using image processing software (e.g., Imaged). From the obtained length data of particles in the longitudinal direction, a kernel density distribution (based on the number of particles) was calculated using the standard normal distribution as the kernel function.

[0189] Evaluation using a coin cell with a cathode active material sample: The 2032-type coin cell using cathode active material particles obtained by lithiation of lithium metal composite oxide was manufactured using a cathode, an anode, and electrolyte prepared by the following methods, respectively.

[0190] < Positive Electrode>

[0191] Cathode: Acetylene black and graphite were used as conductive agents in the ratio of acetylene black:graphite = 1 :1 (by weight), and polyvinylidene fluoride was used as a binding agent, were mixed in N-methylpyrrolidone and coated on aluminum foil. The sheet was dried at 110°C, punched out to 15mm<b, and rolled at 3t / cm2 to make a cathode.

[0192] Anode: A 500 pm thick lithium foil punched to 16 mm <t> was used as the negative electrode.

[0193] Electrolyte: A mixed solvent of EC and DMC was prepared so that EC:DMC = 1:2 (volume ratio), and a solution of 1 mol / L LiPF6 mixed with electrolyte was used as the electrolyte.

[0194] Separator: A separator (Celgard #2400, manufactured by Celgard) with a thickness of 0.5 mm punched out to 20 mm<J> was used.

[0195] < Initial charge capacity and initial charge-discharge efficiency>

[0196] Using coin cells manufactured by the method described above, constant-current charging was conducted at a current density of 0.2C up to 4.35V (upper voltage limit) under 25°C, followed by constant-voltage charging until the current reached 0.05C. The capacity at this time was taken as the initial charge capacity (mAh / g).

[0197] Next, after a 10-minute pause, a constant-current discharge was conducted at a current density of 0.1 C up to 2.50V under the same environment, and the initial discharge capacity (mAh / g) was measured after a 10-minute pause.

[0198] Using the measured values of initial charge capacity and initial discharge capacity, the initial charge / discharge efficiency was calculated based on the following formula.

[0199] Initial charge / discharge efficiency (%) = (Initial discharge capacity / Initial charge capacity) x 100%

[0200] <Cycle maintenance rate>

[0201] Using coin cells manufactured by the method described above, 104 cycles of charge-discharge were performed under the conditions shown or less in a 60°C environment.

[0202] 1 , 2, and 104th cycle:

[0203] After charging at a constant current of 0.2C up to 4.3V, charge at a constant voltage until it reaches 0.01 C. Pause for 5 minutes

[0204] 0.2C constant-current discharge up to 3.0V

[0205] Pause for 5 minutes

[0206] 3rd to 103rd cycle: 0.5C constant current charge to 4.3V, then constant voltage charge until 0.01 C

[0207] Pause for 5 minutes

[0208] 1C constant-current discharge up to 3.0V

[0209] Pause for 5 minutes

[0210] The cycle maintenance rate at 60°C was calculated using the measured discharge capacity at the 30th cycle and the measured discharge capacity at the 103rd cycle based on the following formula.

[0211] Cycle maintenance rate (%)

[0212] = (Discharge capacity at 103rd cycle / Discharge capacity at 30th cycle) x 100% The evaluation results are shown in Table 1.

[0213] Table 1:

Claims

CLAIM1. A method for producing a lithium metal composite oxide, the method comprising a step for firing a mixture of a metal composite hydroxide powder and a lithium source at 700°C-950°C, wherein: the metal composite hydroxide powder contains at least nickel, and includes secondary particles that are formed by aggregation of primary particles; and when a particle diameter corresponding to a maximum peak top of the volume-based particle diameter frequency distribution of the secondary particles is defined as Dt, in a backscattered electron image of a cross section obtained using a scanning electron microscope, primary particles having a major axis length of 1 pm or more account for 10% or more, in terms of number of particles, of at least 30%, in terms of number of particles, of secondary particles having a particle diameter of Dt-1.2Dt, and the volume of pores having a pore diameter of 0.06 pm or less is 0.15 mL / g or less.

2. A method for producing a lithium metal composite oxide, the method comprising a step for calcining a metal composite hydroxide powder at from 200°C or more to less than 700°C to obtain a calcination product, and a step for firing a mixture of the calcination product and a lithium source at 700°C-950°C, wherein: the metal composite hydroxide powder contains at least nickel, and includes secondary particles that are formed by aggregation of primary particles; and when a particle diameter corresponding to a maximum peak top of the volume-based particle diameter frequency distribution of the secondary particles is defined as Dt, in a backscattered electron image of a cross section obtained using a scanning electron microscope, primary particles having a major axis length of 1 pm or more account for 10% or more, in terms of number of particles, of at least 30%, in terms of number of particles, of secondary particles having a particle diameter of Dt-1.2Dt, and the volume of pores having a pore diameter of 0.06 pm or less is 0.15 ml_ / g or less.

3. The method for producing a lithium metal composite oxide according to either of claims 1 and 2, wherein the metal composite hydroxide powder includes a metal composite hydroxide represented by the general formula Nii-x-y-zCoxMnyMz(OH)2+a(where M is an element other than Li, Ni, Co, Mn and O, and the relationships 0 < x < 0.4, 0 < y < 0.4, 0 < z < 0.1 , and -0.5 < a < 0.5 are satisfied).

4. The method for producing a lithium metal composite oxide according to either of claims 1 and 2, wherein in a backscattered electron image of a cross section obtained using a scanning electron microscope, primary particles having a major axis length of 2 pm or more account for 8% or more, in terms of number of particles, of at least 30%, in terms of number of particles, of secondary particles having a particle diameter of Dt-1.2Dt.

5. The method for producing a lithium metal composite oxide according to either of claims 1 and 2, wherein the BET specific surface area of the metal composite hydroxide powder is 1 m2 / g-15 m2 / g.

6. A metal composite hydroxide powder containing at least nickel, and including secondary particles that are formed by aggregation of primary particles, wherein, when a particlediameter corresponding to a maximum peak top of the volume-based particle diameter frequency distribution of the secondary particles is defined as Dt, in a backscattered electron image of a cross section obtained using a scanning electron microscope, primary particles having a major axis length of 1 pm or more account for 10% or more, in terms of number of particles, of at least 30%, in terms of number of particles, of secondary particles having a particle diameter of Dt-1.2Dt, and the volume of pores having a pore diameter of 0.06 pm or less is 0.15 mL / g or less.

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