Method for producing lithium metal composite oxide and metal composite hydroxide powder

Abstract

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

Description

Technical Field

[0001] This disclosure relates to a method for producing lithium metal composite oxide and metal composite hydroxide powders. Background Technology

[0002] In recent years, portable and wireless electronic devices (such as mobile phones and laptops) have become rapidly popular, and compact, lightweight, and high-energy-density non-aqueous rechargeable batteries have been used as the power source for these devices. Among them, lithium-ion secondary batteries using lithium metal composite oxides such as lithium cobalt oxide and lithium nickel oxide as the positive electrode are widely used.

[0003] Lithium cobalt oxide is an excellent material with high voltage and high battery capacity, and is essential as a cathode material for small electronic devices. However, it is expensive because it is made from rare and expensive cobalt compounds.

[0004] However, it is expensive because it is made from rare and costly cobalt compounds. In recent years, ternary cathode active material particles with a layered rock salt structure (basic composition Li(NiCoMn)O2, a solid solution of Ni, Co, and Mn) and lithium-nickel composite compounds (basic composition Li(NiCoAl)O2) have been studied, in which Al is introduced into lithium nickelate to reduce the amount of cobalt used.

[0005] This cathode material is expected to exhibit high battery voltage and high charge / discharge capacity similar to lithium cobalt composite oxides, and is expected to expand the application range of lithium-ion secondary batteries for electric vehicles and stationary batteries. Further research and development are underway.

[0006] However, lithium-ion secondary batteries undergo repeated charge / discharge cycles in high-temperature environments and are stored in a charged state, resulting in a decrease in battery capacity. This is believed to be due to the fact that cathode materials with layered rock-salt structures undergo changes in crystal structure, as well as expansion and contraction, due to repeated charge / discharge cycles and charging states.

[0007] To achieve high stability in lithium-ion batteries, it is considered important to suppress crystal structure instability, particularly in lithium-nickel composite oxides. Methods employed to achieve this include controlling compositional balance, crystallite size and grain size distribution; controlling sintering temperature to obtain powders; adding different elements to enhance bonding forces in the crystal structure; and surface treatment to prevent structural damage and reactions with the electrolyte.

[0008] For example, JP2011-023335 proposes a lithium metal composite oxide, wherein the basic composition is LiMO2, and M is a group of four or more elements, including at least three elements selected from Co, Mn, Al, Mg, Ti, and Ni. According to JP2011-023335, in the lithium-containing composite oxide, Al is used to replace metal sites, and Mg is used to replace both metal and Li sites, thereby reducing the expansion and contraction rates of the crystal structure due to Li insertion / extraction during charge / discharge. This results in mitigation of irreversible reactions, thus improving cycling characteristics.

[0009] However, the lithium metal composite oxide described in JP2011-023335 does not have sufficient cycling characteristics for practical use, and there is still room for improvement. Summary of the Invention

[0010] The purpose of this disclosure is to provide a method for producing lithium metal composite oxides and a metal composite hydroxide for use in the production method, the lithium metal composite oxide exhibiting high cycle characteristics and charge / discharge capacity when used as a cathode active material in a non-aqueous electrolyte secondary battery.

[0011] To address the aforementioned problems, the inventors of this invention have conducted a series of diligent studies. As a result, they discovered that the method involves calcining a mixture of metal composite hydroxide powder and a lithium source at 700°C to 950°C. The metal composite hydroxide powder contains at least nickel and secondary particles composed of agglomerated primary particles, and when the particle size corresponding to the maximum peak of the volume-based particle size frequency distribution of the secondary particles is Dt, when the diameter is Dt, in the electron reflectance image of the cross-section obtained using SEM (scanning electron microscopy), more than 30% of the secondary particles with particle sizes between Dt and 1.2 Dt have primary particles with a long axis length of at least 1 μm, a pore volume not exceeding 0.15 mL / g, and a pore size not exceeding 0.06 μm. The lithium metal composite hydroxide produced by this production method has a pore volume of 0.15 mL / g or less. We have found that a method for producing lithium metal composite oxides and the metal composite hydroxides used in this production method can be provided, wherein non-aqueous electrolyte secondary batteries using the lithium metal composite oxide as the positive electrode active material exhibit high cycle characteristics and charge / discharge capacity.

[0012] This disclosure provides a method for producing lithium metal composite oxides and a metal composite hydroxide for use in the production of lithium metal composite oxides, wherein the lithium metal composite oxides, when used as cathode active materials, result in non-aqueous electrolyte secondary batteries exhibiting high cycle characteristics and charge / discharge capacity.

[0013] Methods for producing lithium metal complex hydroxides and methods for producing lithium metal complex hydroxides for use in their production. Detailed Implementation

[0014] The method for producing lithium metal composite oxide according to a first embodiment of this disclosure includes a process (calcination process) of calcining a mixture of metal composite hydroxide powder and a lithium source at 700°C or higher and 950°C or lower. The method for producing lithium metal composite oxide according to a first embodiment of this disclosure causes the metal composite hydroxide powder to contain at least nickel and to include secondary particles made of agglomerated primary particles, wherein the particle size is between Dt and 1.5Dt when the particle size at the maximum peak of the volume-based particle size frequency distribution corresponding to the secondary particles is Dt. In a cross-sectional reflected electron image obtained using a scanning electron microscope, based on a number of 30% or more of the secondary particles (Dt, 2Dt, or less), the primary particles have a long axis length of 1 μm or greater, a pore volume of 0.15 mL / g or less, and a pore size of 0.06 μm or less.

[0015] The method for producing lithium metal composite oxides according to a second embodiment of this disclosure includes a process of temporarily sintering metal composite hydroxide powder at 200°C or higher but less than 700°C to obtain a temporarily sintered product (temporary sintering process), and sintering a mixture of the temporarily sintered product and a lithium source at 700°C or higher but less than 950°C (sintering process). In the method for producing lithium metal composite oxides according to a second embodiment of this disclosure, the metal composite hydroxide powder contains at least nickel, comprises secondary particles made of agglomerated primary particles, and the particle size is between Dt and 1.5Dt when the particle size corresponding to the maximum peak of the volume-based particle size frequency distribution of the secondary particles is Dt. The secondary particles used are those in which, in a cross-sectional reflected electron image obtained using a scanning electron microscope, 30% or more of the secondary particles with a Dt, 2Dt, or less are primary particles with a major axis of 1 μm or greater, and a pore volume of 0.15 mL / g or less, and a pore size of 0.06 μm or less.

[0016] The method for producing lithium metal composite oxides according to embodiments of this disclosure can produce lithium metal composite oxides, which, when used as cathode active materials, result in non-aqueous electrolyte secondary batteries exhibiting high cycle characteristics and charge / discharge capacity.

[0017] The following is a process-by-process description of an example of a method for manufacturing lithium metal composite oxides according to embodiments of this disclosure. Specifically, examples of methods for manufacturing lithium metal composite oxides according to embodiments of this disclosure are as follows:

[0018] (1) Precursor preparation process: If necessary, prepare a metal composite hydroxide (precursor material) containing at least nickel.

[0019] (2) Tempering process: If necessary, the metal composite hydroxide powder is temporarily baked.

[0020] (3) Mixing process: If necessary, the mixture is prepared by mixing the metal composite hydroxide powder prepared in the precursor material preparation process and / or the sintered material prepared in the sintering process with the lithium compound.

[0021] (4) Firing process: The mixture prepared in the mixing process is fired.

[0022] (5) Washing process: If necessary, the lithium metal composite oxide obtained by the sintering process shall be washed with water.

[0023] (6) Surface treatment process: If necessary, the lithium metal composite oxide obtained in the calcination or washing process shall be surface treated.

[0024] (1) Precursor preparation process

[0025] In the raw material preparation process, the metal composite hydroxide is synthesized into an aggregate composed of primary particles of lithium metal composite oxide. The precursor preparation process is not a necessary process for the lithium metal composite oxide production method of the embodiments disclosed herein.

[0026] Here, the metal composite hydroxide powder used in the method for producing lithium metal composite oxide according to the embodiments of this disclosure (i.e., the process prepared in this process) contains at least nickel, contains secondary particles consisting of agglomerated primary particles, and when the particle size Dt is taken as the particle size corresponding to the maximum peak of the volume-based particle size frequency distribution of the secondary particles, in the cross-sectional reflected electron image obtained using a scanning electron microscope, based on the number of secondary particles with a particle size between Dt and 1.2 Dt, 30% or more of the secondary particles have a primary particle with a long axis length of 1 μm or greater, based on the number of primary particles with a long axis length of 1 μm or greater, and a pore volume of 0.15 mL / g or less, and a pore size of 0.06 μm or less.

[0027] As seen in the cross-section of the secondary particles, the metal composite hydroxide powder has particles that have grown to a length of at least 1 μm in at least one direction. Since the primary particles of the metal composite hydroxide powder tend to grow in a plate-like shape, they should be selectively grown in a direction perpendicular to the flat surface. Specifically, in the above manufacturing method, the production of the metal composite hydroxide powder should be divided into a nucleation stage and a crystallization stage. In the nucleation stage, conditions should be selected such that the generated nuclei do not grow excessively, and during the crystallization process, conditions should be selected such that the nuclei selectively grow in a direction perpendicular to the planar surface. The conditions for the nucleation and crystallization stages can vary depending on the elemental composition of the metal composite hydroxide powder and the relationship between the conditions of the nucleation and crystallization stages; however, the conditions of at least the examples described below can be used to produce the metal composite hydroxide powder of the embodiments disclosed herein. However, the metal composite hydroxide powder of the embodiments disclosed herein can be produced under the conditions of at least the examples described below.

[0028] Surprisingly, the inventors discovered that non-aqueous electrolyte secondary batteries using lithium metal composite oxides obtained by sintering this type of metal composite hydroxide powder exhibit high cycle characteristics and charge / discharge capacity. The reason for this is not necessarily clear, but the inventors believe it to be as follows: The aforementioned metal composite hydroxide powder has void spaces within the secondary particles. Even after calcination and conversion to lithium metal composite oxide, these spaces remain at an appropriate size, and it is believed that these spaces absorb the volume expansion and contraction caused by lithium charging and discharging, thus exhibiting high cycle characteristics.

[0029] The chemical composition of the metal complex hydroxide powder is not limited, as long as it contains nickel, for example, Ni. 1-x-y-z Co x Mn y M z (OH) 2+α (In this formula, M is, for example, the general formula Ni) 1-x-y-z Co x Mn y M z (OH) 2+α Where M is an element other than Li, Ni, Co, Mn and O, and 0 ≤ x ≤ 0.4, 0 ≤ y ≤ 0.4, 0 ≤ z ≤ 0.1, -0.5 ≤ α ≤ 0.5 are preferred.

[0030] The value of "x" in the general formula is unrestricted, as long as it is within the range of 0 ≤ x ≤ 0.4. For example, 0.001 or greater, 0.0015 or greater, 0.002 or greater, 0.0025 or greater, 0.003 or greater, 0.0035 or greater, 0.004 or greater, 0.0045 or greater, 0.005 or greater, 0.0055 or greater, 0.006 or greater, 0.0065 or greater, 0.007 or greater, 0.0075 or greater, 0.008 or greater, 0.0085 or greater, 0.009 or greater, 0.0095 or greater, 0.01 or greater, 0.015 or greater, 0.02 or greater, 0.025 or greater, 0.03 or greater, 0.035 or greater, 0.04 or greater, 0. 0.45 or greater, 0.05 or greater, 0.055 or greater, 0.06 or greater, 0.065 or greater, 0.07 or greater, 0.075 or greater, 0.08 or greater, 0.085 or greater, 0.09 or greater, 0.095 or greater, 0.1 or greater, 0.102 or greater, 0.105 or greater, 0.107 or greater, 0.11 or greater, 0.112 or greater, 0.115 or greater, 0.117 or greater, 0.12 or greater, 0.122 or greater, 0.125 or greater, 0.127 or greater, 0.13 or greater, 0.132 or greater, 0.135 or greater, 0.137 or greater, 0.14 or greater, 0.14 2 or greater, 0.145 or greater, 0.147 or greater, 0.15 or greater, 0.152 or greater, 0.155 or greater, 0.157 or greater, 0.16 or greater, 0.162 or greater, 0.165 or greater, 0.167 or greater, 0.17 or greater, 0.172 or greater, 0.175 or greater, 0.177 or greater, 0.18 or greater, 0.182 or greater, 0.185 or greater, 0.187 or greater, 0.19 or greater, 0.192 or greater, 0.195 or greater, 0.197 or greater, 0.2 or greater, 0.202 or greater, 0.205 or greater, 0.207 or greater, 0.21 or greater, 0.2 12 or greater, 0.215 or greater, 0.217 or greater, 0.22 or greater, 0.222 or greater, 0.225 or greater, 0.227 or greater, 0.23 or greater, 0.232 or greater, 0.235 or greater, 0.237 or greater, 0.24 or greater, 0.242 or greater, 0.245 or greater, 0.247 or greater, 0.25 or greater, 0.252 or greater, 0.255 or greater, 0.257 or greater, 0.26 or greater, 0.262 or greater, 0.265 or greater, 0.267 or greater, 0.27 or greater, 0.272 or greater, 0.275 or greater, 0.277 or greater, 0.28 or greater, 0.282 or greater, 0.285 or greater, 0.287 or greater, 0.29 or greater, 0.292 or greater, 0.295 or greater, 0.297 or greater, 0.3 or greater, 0.302 or greater, 0.305 or greater, 0.307 or greater, 0.31 or greater, 0.312 or greater, 0.315 or greater, 0.317 or greater, 0.32 or greater, 0.322 or greater, 0.325 or greater, 0.327 or greater, 0.33 or greater, 0.332 or greater, 0.335 or greater, 0.337 or greater, 0.34 or greater 0.342 or greater, 0.345 or greater, 0.347 or greater, 0.35 or greater, 0.352 or greater, 0.355 or greater, 0.357 or greater, 0.36 or greater, 0.362 or greater, 0.365 or greater, 0.367 or greater, 0.37 or greater, 0.372 or greater, 0.375 or greater, 0.377 or greater, 0.38 or greater, 0.382 or greater, 0.385 or greater, 0.387 or greater, 0.39 or greater, 0.392 or greater, 0.395 or greater, and 0.397 or greater are preferred. 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, or 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 Smaller, 0.315 or smaller, 0.312 or smaller, 0.31 or smaller, 0.307 or smaller, 0.305 or smaller, 0.302 or smaller, 0.3 or smaller, 0.297 or smaller, 0.295 or smaller, 0.292 or smaller, 0.29 or smaller, 0.287 or smaller, 0.285 or smaller, 0.282 or smaller, 0.28 or smaller, 0.277 or smaller, 0.27 5 or less, 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, 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, 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, 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, 0.17 5 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 Smaller, 0.115 or smaller, 0.112 or smaller, 0.11 or smaller, 0.107 or smaller, 0.105 or smaller, 0.102 or smaller, 0.1 or smaller, 0.095 or smaller, 0.09 or smaller, 0.085 or smaller, 0.08 or smaller, 0.075 or smaller, 0.07 or smaller, 0.065 or smaller, 0.06 or smaller, 0.055 or smaller, 0.05 or smaller, 0.045 or smaller, 0.04 or smaller, 0.035 or smaller, 0.03 or smaller, 0.025 or smaller, 0. 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.

[0031] The value of "y" in the general formula is unrestricted, as long as it is within the range of 0 ≤ y ≤ 0.4. For example, 0.001 or greater, 0.0015 or greater, 0.002 or greater, 0.0025 or greater, 0.003 or greater, 0.0035 or greater, 0.004 or greater, 0.0045 or greater, 0.005 or greater, 0.0055 or greater, 0.006 or greater, 0.0065 or greater, 0.007 or greater, 0.0075 or greater, 0.008 or greater, 0.0085 or greater, 0.009 or greater, 0.0095 or greater, 0.01 or greater, 0.015 or greater, 0.02 or greater, 0.025 or greater, 0.03 or greater, 0.035 or greater, 0.04 or greater, 0. 0.45 or greater, 0.05 or greater, 0.055 or greater, 0.06 or greater, 0.065 or greater, 0.07 or greater, 0.075 or greater, 0.08 or greater, 0.085 or greater, 0.09 or greater, 0.095 or greater, 0.1 or greater, 0.102 or greater, 0.105 or greater, 0.107 or greater, 0.11 or greater, 0.112 or greater, 0.115 or greater, 0.117 or greater, 0.12 or greater, 0.122 or greater, 0.125 or greater, 0.127 or greater, 0.13 or greater, 0.132 or greater, 0.135 or greater, 0.137 or greater, 0.14 or greater, 0.14 2 or greater, 0.145 or greater, 0.147 or greater, 0.15 or greater, 0.152 or greater, 0.155 or greater, 0.157 or greater, 0.16 or greater, 0.162 or greater, 0.165 or greater, 0.167 or greater, 0.17 or greater, 0.172 or greater, 0.175 or greater, 0.177 or greater, 0.18 or greater, 0.182 or greater, 0.185 or greater, 0.187 or greater, 0.19 or greater, 0.192 or greater, 0.195 or greater, 0.197 or greater, 0.2 or greater, 0.202 or greater, 0.205 or greater, 0.207 or greater, 0.21 or greater, 0.2 12 or greater, 0.215 or greater, 0.217 or greater, 0.22 or greater, 0.222 or greater, 0.225 or greater, 0.227 or greater, 0.23 or greater, 0.232 or greater, 0.235 or greater, 0.237 or greater, 0.24 or greater, 0.242 or greater, 0.245 or greater, 0.247 or greater, 0.25 or greater, 0.252 or greater, 0.255 or greater, 0.257 or greater, 0.26 or greater, 0.262 or greater, 0.265 or greater, 0.267 or greater, 0.27 or greater, 0.272 or greater, 0.275 or greater, 0.277 or greater, 0.28 or greater, 0.282 or greater, 0.285 or greater, 0.287 or greater, 0.29 or greater, 0.292 or greater, 0.295 or greater, 0.297 or greater, 0.3 or greater, 0.302 or greater, 0.305 or greater, 0.307 or greater, 0.31 or greater, 0.312 or greater, 0.315 or greater, 0.317 or greater, 0.32 or greater, 0.322 or greater, 0.325 or greater, 0.327 or greater, 0.33 or greater, 0.332 or greater, 0.335 or greater, 0.337 or greater, 0.34 or greater 0.342 or greater, 0.345 or greater, 0.347 or greater, 0.35 or greater, 0.352 or greater, 0.355 or greater, 0.357 or greater, 0.36 or greater, 0.362 or greater, 0.365 or greater, 0.367 or greater, 0.37 or greater, 0.372 or greater, 0.375 or greater, 0.377 or greater, 0.38 or greater, 0.382 or greater, 0.385 or greater, 0.387 or greater, 0.39 or greater, 0.392 or greater, 0.395 or greater, and 0.397 or greater are 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, or 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 Smaller, 0.315 or smaller, 0.312 or smaller, 0.31 or smaller, 0.307 or smaller, 0.305 or smaller, 0.302 or smaller, 0.3 or smaller, 0.297 or smaller, 0.295 or smaller, 0.292 or smaller, 0.29 or smaller, 0.287 or smaller, 0.285 or smaller, 0.282 or smaller, 0.28 or smaller, 0.277 or smaller, 0.27 5 or less, 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, 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, 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, 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, 0.17 5 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 Smaller, 0.115 or smaller, 0.112 or smaller, 0.11 or smaller, 0.107 or smaller, 0.105 or smaller, 0.102 or smaller, 0.1 or smaller, 0.095 or smaller, 0.09 or smaller, 0.085 or smaller, 0.08 or smaller, 0.075 or smaller, 0.07 or smaller, 0.065 or smaller, 0.06 or smaller, 0.055 or smaller, 0.05 or smaller, 0.045 or smaller, 0.04 or smaller, 0.035 or smaller, 0.03 or smaller, 0.025 or smaller, 0. 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.

[0032] The value of "z" in the general formula is unrestricted, as long as it is within the range of 0 ≤ z ≤ 0.1. For example, 0.001 or greater, 0.0012 or greater, 0.0015 or greater, 0.0017 or greater, 0.002 or greater, 0.0022 or greater, 0.0025 or greater, 0.0027 or greater, 0.003 or greater, 0.0032 or greater, 0.0035 or greater, 0.0037 or greater, 0.004 or greater, 0.0042 or greater, 0.0045 or greater, 0.0047 or greater, 0.0 0.05 or greater, 0.0052 or greater, 0.0055 or greater, 0.0057 or greater, 0.006 or greater, 0.0062 or greater, 0.0065 or greater, 0.0067 or greater, 0.007 or greater, 0.0072 or greater, 0.0075 or greater, 0.0077 or greater, 0.008 or greater, 0.0082 or greater, 0.0085 or greater, 0.0087 or greater, 0.009 or greater, 0.0092 or greater Large, 0.0095 or larger, 0.0097 or larger, 0.01 or larger, 0.012 or larger, 0.015 or larger, 0.017 or larger, 0.02 or larger, 0.022 or larger, 0.025 or larger, 0.027 or larger, 0.03 or larger, 0.032 or larger, 0.035 or larger, 0.037 or larger, 0.04 or larger, 0.042 or larger, 0.045 or larger, 0.047 or larger, 0.05 or larger 0.052 or greater, 0.055 or greater, 0.057 or greater, 0.06 or greater, 0.062 or greater, 0.065 or greater, 0.067 or greater, 0.07 or greater, 0.072 or greater, 0.075 or greater, 0.077 or greater, 0.08 or greater, 0.082 or greater, 0.085 or greater, 0.087 or greater, 0.09 or greater, 0.092 or greater, 0.095 or greater, and 0.097 or greater are preferred.On the other hand, the value of "z" is preferably 0.97 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 Small, 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 0.0095 or less, 0.0092 or less, 0.009 or less, 0.0087 or less, 0.0085 or less, 0.0082 or less, 0.008 or less, 0.0077 or less, 0.0075 or less, 0.0072 or less, 0.007 or less, 0.0067 or less, 0.0065 or less, 0.0062 or less, 0.006 or less, 0.0057 or less, 0.0055 or less, 0.005 2 or less, 0.005 or less, 0.0047 or less, 0.0045 or less, 0.0042 or less, 0.004 or less, 0.0037 or less, 0.0035 or less, 0.0032 or less, 0.003 or less, 0.0027 or less, 0.0025 or less, 0.0022 or less, 0.002 or less, 0.0017 or less, 0.0015 or less, 0.0012 or less, 0.001 or less.

[0033] 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 element. The type of element M should be selected according to the purpose of its addition. When multiple elements are included as element M, the value of "w" represents the total amount of the multiple elements.

[0034] The value of "α" in the general formula is unrestricted, as long as it is within the range of -0.5 ≤ α ≤ 0.5. For example, -0.5 or greater, -0.45 or greater, -0.4 or greater, -0.35 or greater, -0.30 or greater, -0.25 or greater, -0.2 or greater, -0.15 or greater, -0.1 or greater, -0.075 or greater, -0.05 or greater, -0.025 or greater, 0.001 or greater, 0.0015 or greater, 0.002 or greater, 0.0025 or greater, 0.003 or greater, 0.0035 or greater, 0.004 or greater, 0.0045 or greater, 0.005 or greater, 0.0055 or greater, 0.006 or greater, 0.0065 or greater, 0.007 or greater, 0 .0075 or greater, 0.008 or greater, 0.0085 or greater, 0.009 or greater, 0.0095 or greater, 0.01 or greater, 0.015 or greater, 0.02 or greater, 0.025 or greater, 0.03 or greater, 0.035 or greater, 0.04 or greater, 0.045 or greater, 0.05 or greater, 0.055 or greater, 0.06 or greater, 0.065 or greater, 0.07 or greater, 0.075 or greater, 0.08 or greater, 0.085 or greater, 0.09 or greater, 0.095 or greater, 0.1 or greater, 0.102 or greater, 0.105 or greater, 0.107 or greater, 0.11 or greater. 0.112 or greater, 0.115 or greater, 0.117 or greater, 0.12 or greater, 0.122 or greater, 0.125 or greater, 0.127 or greater, 0.13 or greater, 0.132 or greater, 0.135 or greater, 0.137 or greater, 0.14 or greater, 0.142 or greater, 0.145 or greater, 0.147 or greater, 0.15 or greater, 0.152 or greater, 0.155 or greater, 0.157 or greater, 0.16 or greater, 0.162 or greater, 0.165 or greater, 0.167 or greater, 0.17 or greater, 0.172 or greater, 0.175 or greater, 0.177 or greater, 0.18 Or greater, 0.182 or greater, 0.185 or greater, 0.187 or greater, 0.19 or greater, 0.192 or greater, 0.195 or greater, 0.197 or greater, 0.2 or greater, 0.202 or greater, 0.205 or greater, 0.207 or greater, 0.21 or greater, 0.212 or greater, 0.215 or greater, 0.217 or greater, 0.22 or greater, 0.222 or greater, 0.225 or greater, 0.227 or greater, 0.23 or greater, 0.232 or greater, 0.235 or greater, 0.237 or greater, 0.24 or greater, 0.242 or greater, 0.245 or greater, 0.247 or greater, 0.25 or greater, 0.252 or greater, 0.255 or greater, 0.257 or greater, 0.26 or greater, 0.262 or greater, 0.265 or greater, 0.267 or greater, 0.27 or greater, 0.272 or greater, 0.275 or greater, 0.277 or greater, 0.28 or greater, 0.282 or greater, 0.285 or greater, 0.287 or greater, 0.29 or greater, 0.292 or greater, 0.295 or greater, 0.297 or greater, 0.3 or greater, 0.302 or greater, 0.305 or greater, 0.307 or greater, 0.31 or greater, 0.3 12 or greater, 0.315 or greater, 0.317 or greater, 0.32 or greater, 0.322 or greater, 0.325 or greater, 0.327 or greater, 0.33 or greater, 0.332 or greater, 0.335 or greater, 0.337 or greater, 0.34 or greater, 0.342 or greater, 0.345 or greater, 0.347 or greater, 0.35 or greater, 0.352 or greater, 0.355 or greater, 0.357 or greater, 0.36 or greater, 0.362 or greater, 0.365 or greater, 0.367 or greater, 0.37 or greater, 0.372 or greater, 0.3 75 or greater, 0.377 or greater, 0.38 or greater, 0.382 or greater, 0.385 or greater, 0.387 or greater, 0.39 or greater, 0.392 or greater, 0.395 or greater, 0.397 or greater, 0.4 or greater, 0.402 or greater, 0.405 or greater, 0.407 or greater, 0.41 or greater, 0.412 or greater, 0.415 or greater, 0.417 or greater, 0.42 or greater, 0.422 or greater, 0.425 or greater, 0.427 or greater, 0.43 or greater, 0.432 or greater, 0.435 or greater, 0.43 7 or greater, 0.44 or greater, 0.442 or greater, 0.445 or greater, 0.447 or greater, 0.45 or greater, 0.452 or greater, 0.455 or greater, 0.457 or greater, 0.46 or greater, 0.462 or greater, 0.465 or greater, 0.467 or greater, 0.47 or greater, 0.472 or greater, 0.475 or greater, 0.477 or greater, 0.48 or greater, 0.482 or greater, 0.485 or greater, 0.487 or greater, 0.49 or greater, 0.492 or greater, 0.495 or greater, 0.497 or greater are preferred. On the other hand, the value of "α" 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, or 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, 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 Smaller, 0.392 or smaller, 0.39 or smaller, 0.387 or smaller, 0.385 or smaller, 0.382 or smaller, 0.38 or smaller, 0.377 or smaller, 0.375 or smaller, 0.372 or smaller, 0.367 or smaller, 0.365 or smaller, 0.362 or smaller, 0.36 or smaller, 0.357 or smaller, 0.355 or smaller, 0.352 or smaller, 0.35 or smaller, 0.347 or smaller, 0.345 or smaller, 0.342 or smaller, 0.34 or smaller, 0.337 or smaller, 0.335 or smaller, 0.332 or smaller, 0.33 or smaller, 0.327 or smaller, 0.325 or smaller, 0.322 or smaller 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, 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, 0.25 or less, 0.247 or Smaller, 0.245 or smaller, 0.242 or smaller, 0.24 or smaller, 0.237 or smaller, 0.235 or smaller, 0.232 or smaller, 0.23 or smaller, 0.227 or smaller, 0.225 or smaller, 0.222 or smaller, 0.22 or smaller, 0.217 or smaller, 0.215 or smaller, 0.212 or smaller, 0.21 or smaller, 0.207 or smaller, 0.205 or smaller, 0.202 or smaller, 0.2 or smaller, 0.197 or smaller, 0.195 or smaller, 0.192 or smaller, 0.19 or smaller, 0.187 or smaller, 0.185 or smaller, 0.182 or smaller, 0.18 or smaller, 0.177 or smaller, 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 Small, 0.13 or smaller, 0.127 or smaller, 0.125 or smaller, 0.122 or smaller, 0.12 or smaller, 0.117 or smaller, 0.115 or smaller, 0.112 or smaller, 0.11 or smaller, 0.107 or smaller, 0.105 or smaller, 0.102 or smaller, 0.1 or smaller, 0.095 or smaller, 0.09 or smaller, 0.085 or smaller, 0.08 or smaller Small, 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.

[0035] Metal composite hydroxide powder may contain one or two or more compounds of the general formula Ni 1-x-y-z Co x Mn y M z (OH) 2+α (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 ≤ α ≤ 0.5) It may contain one or more metal complex hydroxides represented by the above formula (-0.5 ≤ α ≤ 0.5, -0.5 ≤ α ≤ 0.5), and may contain compounds other than those represented by the above formula, for example, it may contain (based on mass) 0% or more (including cases where no compounds other than metal complex hydroxides are contained), 10% or less, 5% or less, 2% or less, 1% or less.

[0036] The BET specific surface area of ​​metal composite hydroxide powder is not limited, but should be 1 m². 2 / g or larger, 2 m 2 / g or larger, 3 m 2 / g or larger, or 4 m 2 / g or greater. On the other hand, the BET specific surface area of ​​the metal composite hydroxide powder should be 15 m². 2 / g or less, 14 m 2 / g or less, 13 m 2 / g or less, 12 m 2 / g or less, 11 m 2 / g or less, 10 m 2 / g or less, 9 m 2 / g or less, 8 m 2 / g or less, 7 m 2 / g or less, 6 m 2 / g or less.

[0037] When the particle size at the maximum peak of the volume-based particle size frequency distribution corresponding to the secondary particles is Dt, in secondary particles with particle sizes of Dt or larger, 1.2Dt or smaller, in the cross-sectional reflected electron image obtained using a scanning electron microscope, the primary particles with a major axis length of 1 μm or larger are based on a number of 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.

[0038] When the particle size at the maximum peak of the volume-based particle size frequency distribution corresponding to the secondary particles is Dt, in secondary particles with a particle size of Dt or larger, 1.2Dt or smaller, in the cross-sectional reflected electron image obtained using a scanning electron microscope, primary particles with a major axis length of 2 μm or larger should account for 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 based on the number.

[0039] The particle size Dt corresponding to the maximum peak was determined by using a laser particle size analyzer (Microtrac HRA, Nikkiso Co., Ltd.) to generate a volume-based particle size distribution and determine the particle size corresponding to the maximum peak using a wet laser method.

[0040] The lengths of the primary particles in the metal composite hydroxide samples were measured as follows. First, the metal composite hydroxide samples were cured with epoxy resin, and particle cross-sections were formed using an ion beam through a cross-section polisher (IB-19530CP: JEOLLtd.). Then, images were captured using a field emission scanning electron microscope (JSM-7100F: JEOLLtd.) at an accelerating voltage of 3 kV and magnifications ranging from 3000 to 2000x. For secondary particles, 100 particles with diameters ranging from Dt or larger to 1.2 Dt or smaller were extracted relative to the particle size Dt corresponding to the maximum peak obtained through particle size distribution measurements based on volume standards.

[0041] For all particles in which the outline of primary particles within secondary particles is visible in electron micrographs obtained via reflection electron microscopy, the grain boundaries of primary particles within secondary particles are depicted using Paint, a tool included in Microsoft Windows, and image processing software (e.g., ImageJ) is used on the image depicting the grain boundaries. The image of the grain boundaries is binarized using image processing software (e.g., ImageJ, etc.), and the length of the particles along their long axis is calculated. Based on the obtained length data of the particles along their long axis, a kernel density distribution (based on the number of particles) is calculated using a standard normal distribution as the kernel function.

[0042] The pore volume of metal composite hydroxide powders with a pore size of 0.06 μm or smaller is not limited, as long as it is 0.15 mL / g or smaller, for example, 0.14 mL / g or smaller, 0.13 mL / g or smaller, 0.12 mL / g or smaller, 0.11 mL / g or smaller, 0.1 mL / g or smaller, and 0.2 mL / g or smaller. 0 mL / g or smaller is preferred. The pore volume of metal composite hydroxide powders with a pore size of 0.06 μm or smaller should be 0 mL / g or larger, 0.01 mL / g or larger, and 0.02 mL / g or larger.

[0043] The tap density of the metal composite hydroxide powder is not particularly limited, but is, for example, 1 g / cc or greater, 1.1 g / cc or greater, 1.2 g / cc or greater, 1.3 g / cc or greater, 1.4 g / cc or greater, 1.5 g / cc or greater, 1.6 g / cc or greater, 1.7 g / cc or greater, 1.8 g / cc or greater, and 1.9 g / cc or greater. On the other hand, the tap 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 preferred values.

[0044] The full width at half maximum (FWHM) of the (001) plane in the X-ray diffraction pattern of the metal composite hydroxide obtained by X-ray diffraction measurement is not particularly limited, but is preferably 0.2° or greater, 0.25° or greater, or 0.3° or greater. On the other hand, the 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.

[0045] The full width at half maximum (FWHM) of the (100) plane in the X-ray diffraction pattern of the metal-containing hydroxide obtained by X-ray diffraction measurement is not particularly limited, but 0.3° or greater, 0.35° or greater, and 0.4° or greater are preferred. On the other hand, the 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, and 0.65° or less.

[0046] The full width at half maximum (FWHM) of the (101) plane in the X-ray diffraction pattern of the metal composite hydroxide obtained by X-ray diffraction measurement is not limited, but is preferably 0.5° or greater, 0.55° or greater, 0.6° or greater, and 0.65° or greater. On the other hand, it is preferred that the FWHM of the (101) plane 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, or 0.9° or less.

[0047] The method for manufacturing metal composite hydroxide powder is described below.

[0048] <Production Method of Metal Composite Hydroxide Powder>

[0049] For example, depending on the composition of the composite oxide to be produced, aqueous solutions containing various metal elements and aqueous solutions containing compounds of other elements are added dropwise to a reaction vessel, while an alkaline solution such as sodium hydroxide solution and ammonia solution, serving as the mother liquor, is stirred in the reaction vessel. A co-precipitation method via wet reaction can be used. Even if the metal composite hydroxide powder is produced by a method different from this one, as long as it has the above-described composition, the problems disclosed herein can be solved.

[0050] In the production of metal composite hydroxide powders, it is preferable to start from the state of preparing an alkaline solution as the mother liquor, and then introduce an inert gas (industrially preferably nitrogen) to generate a nitrogen atmosphere in the reaction tank, so as to keep the oxygen concentration in the reaction tank system and the solution as low as possible. If the oxygen concentration is too high, there is a risk that the co-precipitated hydroxide may be over-oxidized by the remaining predetermined amount or more oxygen, or that crystallization may hinder the formation of agglomerates.

[0051] There are no particular limitations on the aqueous solution of the element used as the source of the element constituting the metal composite hydroxide powder, but an acidic aqueous solution, for example, is preferred, and a sulfuric acid solution is even more preferred. One or more aqueous solutions of this element may be used.

[0052] The source of elements should be adjusted according to the composition of the lithium metal oxide to be produced, including the type and stoichiometry of the elements, and is not limited to any particular type.

[0053] As nickel compounds, although there are no particular restrictions, one or more types selected from the following can be used: nickel sulfate, nickel oxide, nickel hydroxide, nickel nitrate, nickel carbonate, nickel chloride, nickel iodide, and metallic nickel, etc.

[0054] As cobalt compounds, one or more of the following can be used: cobalt sulfate, cobalt oxide, cobalt hydroxide, cobalt nitrate, cobalt carbonate, cobalt chloride, cobalt iodide, and metallic cobalt.

[0055] As manganese compounds, one or more of the following can be used: manganese sulfate, manganese oxide, manganese hydroxide, manganese nitrate, manganese carbonate, manganese chloride, manganese iodide, and metallic manganese.

[0056] As aluminum compounds, although there are no particular restrictions, one 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.

[0057] As titanium compounds, one or more of the following can be used: titanium oxysulfate, titanium oxide, titanium hydroxide, titanium nitrate, titanium carbonate, titanium chloride, titanium iodide, and metallic titanium.

[0058] As iron compounds, one or more of the following can be used: ferric sulfate, ferric oxide, ferric hydroxide, ferric nitrate, ferric carbonate, ferric chloride, ferric iodide, and metallic iron.

[0059] As a niobium compound, although there are no particular restrictions, one or more of the following can be used: niobium oxide, niobium chloride, lithium niobate, niobium iodide, etc.

[0060] As a tungsten compound, although there are no particular restrictions, one or more of the following can be used: tungsten oxide, sodium tungstate, ammonium paratungstate, tungsten hexacarbonyl, tungsten sulfide, etc.

[0061] Although there are no particular restrictions, one or more of the following can be used as magnesium compounds: magnesium sulfate, magnesium oxide, magnesium hydroxide, magnesium nitrate, magnesium carbonate, magnesium chloride, magnesium iodide, and metallic magnesium. Magnesium nitrate, magnesium chloride, magnesium iodide, and metallic magnesium are also acceptable.

[0062] As zinc compounds, one 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, etc.

[0063] For other elements, one or more of the following may also be used: sulfates, oxides, hydroxides, nitrates, carbonates, chlorides, iodides, and metals.

[0064] The proportions of each compound and the amount of each element should be adjusted according to the composition of the lithium metal composite oxide to be produced.

[0065] The appropriate pH range for producing metal composite hydroxide powders is not particularly limited and should be determined in order to obtain the secondary particle diameter, sparsity, and other shapes to be produced, and should generally be in the range of 10 to 13.

[0066] The metal complex hydroxide powder obtained by wet reaction should be washed, dehydrated, and then dried.

[0067] By washing the metal composite hydroxide powder, impurities such as sulfate, carbonate, and sodium components that were incorporated into the agglomerated particles or adhered to the surface layer during the reaction can be washed away. The washing process can be carried out using a Buchner funnel via Nutsche washing (if the amount is small), or by pumping the post-reaction suspension through a filter press, washing with water, and then dehydrating. In the washing process, for example, pure water, sodium hydroxide solution, or sodium carbonate solution can be used, but from an industrial point of view, pure water is preferred. However, if a large amount of residual sulfate is present, a sodium hydroxide solution with a pH controlled according to the residual amount can be used.

[0068] (2) Temporary baking process

[0069] The pre-sintering process is a process of pre-sintering metal composite hydroxide powder. The temporary sintering process is not a necessary process for the lithium metal composite oxide production method disclosed herein.

[0070] Therefore, the metal composite hydroxide powder can be calcined and dehydrated by temporary sintering before being mixed with lithium compounds.

[0071] Although temporary sintering conditions are not particularly limited, it is preferred, for example, to perform the process in an oxidizing atmosphere, at a heating temperature of 200°C to 700°C, and for a heating time of 1 to 6 hours. The heating temperature is the temperature of the portion of the metal composite hydroxide powder with the highest temperature, and the heating time is the time during which the temperature of the portion with the highest temperature is maintained within the aforementioned temperature range. By performing the temporary sintering process, impurities remaining in the metal composite hydroxide powder can be sufficiently removed, and a temporary sintered product can be obtained. The heating temperature is the temperature of the portion of the heated object with the highest temperature when the object is heated and its temperature rises, and the heating time is the time during which the temperature of the portion of the heated object with the highest temperature is maintained within the aforementioned temperature range (this also applies to this process).

[0072] (3) Mixing process

[0073] The mixture is prepared by mixing a composite metal hydroxide powder prepared in a precursor preparation process and / or a temporarily calcined product prepared in a temporary calcination process with a lithium source at a predetermined ratio. The mixing method is not limited, but for example, the composite metal hydroxide and / or sintered powder and the lithium compound powder as the lithium source may be weighed to a predetermined ratio and mixed in a dry process, or the composite metal hydroxide and / or sintered powder and a lithium source solution may be mixed at a predetermined ratio. This method may involve drying all suspensions obtained by mixing the metal composite hydroxide and / or pseudo-sintered product with an aqueous solution of the lithium source at a predetermined ratio. The mixing process is not a necessary process for the method of producing lithium metal composite oxides according to the embodiments of this disclosure.

[0074] Various lithium salts can be used as lithium compounds 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, and lithium pyruvate. One or more of the following can also 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 are preferred.

[0075] The blending ratio of lithium source with metal composite hydroxide powder and / or pseudo-sintered product is not particularly limited, but should be adjusted according to the composition of the lithium metal composite oxide to be produced so that the total amount of each element and the total amount of each element are in the desired ratio.

[0076] (4) Calcination process

[0077] The calcination process is a process in which a mixture of metal composite hydroxide powder and / or metal composite compound and lithium source is calcined at a temperature between 700°C and 950°C.

[0078] In the calcination process used to produce lithium metal composite oxides containing at least nickel, a lithiation reaction and crystal growth occur. The lithiation reaction requires a certain oxygen partial pressure. The lithiation reaction lithiates the metal composite hydroxide used as a feedstock to obtain the lithium metal composite oxide. The temperature is then raised to a predetermined temperature to promote the crystal growth of the lithium metal composite oxide.

[0079] The heating temperature during 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 calcination 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.

[0080] <Pre-firing>

[0081] Calcination is typically carried out in a mixing process by filling a container (such as a crucible or sagger) with a mixture obtained by mixing metal composite hydroxide powder and / or composite metal compound with a lithium source in a mixer. Especially in lithiation reactions, as the mixed powder is closer to the bottom of the container it fills, the oxygen concentration required to vent and diffuse the generated gases becomes more difficult. As a result, the uniformity of the reaction and the control of the primary particle size can become challenging.

[0082] Therefore, when producing the lithium metal composite oxide of the embodiments disclosed herein, a two-step calcination method is preferred, wherein pre-calcination is performed under predetermined conditions, followed by main calcination under predetermined conditions. However, pre-calcination is not a necessary process.

[0083] In such pre-firing, it is particularly desirable to combine firing methods that accelerate the lithiation reaction. Specifically, methods that make the mixture more easily heated, facilitate the removal of gases generated from the lithium source, and diffuse gases with high oxygen partial pressure into the mixture (within the particles) can be cited. For example, the desired properties can be achieved by pre-firing a small amount of the mixture or by pre-firing while the mixture is flowing.

[0084] To pre-fire the mixture, it can be filled into a sagger or crucible and fired using a static furnace, roller hearth furnace, or pusher furnace, or a rotary kiln can be used to fire it while it is flowing.

[0085] The heating temperature during pre-firing is not limited, as long as it is lower than the heating temperature during 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 complex hydroxides and / or complex metal compounds in the mixture react with the lithium compound, and that the lithiation reaction proceeds reliably and uniformly to obtain the desired lithium metal complex oxide without producing dissimilar phases.

[0086] The atmosphere used for pre-calcination is not limited and can be any oxidizing atmosphere in which the lithiation reaction can proceed reliably and uniformly. For example, preferred atmospheres include atmospheric (oxygen concentration: 21 vol%), calcination oxidizing gas atmospheres with carbon dioxide concentrations of 30 ppm or lower, or oxygen atmospheres with oxygen concentrations of 80 vol% or higher or 90 vol% or higher.

[0087] The pre-calcination time is not limited, and it should ensure that the lithiation reaction proceeds reliably and uniformly. Specifically, for example, 1 to 10 hours and 2 to 8 hours are preferred.

[0088] <Main Firing>

[0089] The pre-fired mixture is subjected to a main firing to allow crystal and particle growth at higher temperatures. In this process, it is essential to promote reliable and uniform crystal growth to obtain lithium metal composite oxides with the desired crystal structure.

[0090] The atmosphere used for the primary calcination is not particularly limited, but should have an oxygen partial pressure that ensures reliable and uniform crystal growth and does not reduce transition metals contained in the mixture to be calcined, and preferably has a low moisture content and a low carbon dioxide gas concentration. For example, it is preferred to use an atmospheric calcination oxidizing gas atmosphere (oxygen concentration: 21 vol%) and a carbon dioxide concentration of 30 ppm or lower, or an oxygen atmosphere with an oxygen concentration preferably of 80 vol% or higher, or 90 vol% or higher.

[0091] 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 according to 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 maintaining the maximum temperature within the desired range, lithium metal composite oxides with the desired crystal structure and reduced unreacted components can be obtained, and the degradation of battery characteristics in non-aqueous electrolyte secondary batteries using the obtained lithium metal composite oxide as the cathode can be prevented. For example, when obtaining a lithium metal composite oxide with a Ni content of 20 to 80 mol% based on 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.

[0092] The calcination time 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.

[0093] (5) Washing process

[0094] The washing process involves washing the lithium metal composite oxide obtained through calcination during the sintering process with water. The washing process is not a necessary component.

[0095] The lithium metal composite oxides obtained in the calcination process may contain unreacted lithium compounds as impurities or lithium compounds that appear on the surface layer of the particles from the crystal structure during the calcination process. Therefore, in order to remove or reduce these impurities, they can be washed with water and subjected to heat treatment, for example.

[0096] (6) Surface treatment process

[0097] Surface treatment is a process that subjectes lithium metal composite oxides obtained during calcination or washing to surface treatment. Surface treatment is not a necessary component.

[0098] By adding predetermined elemental compounds to the composite oxide obtained through calcination or washing processes, mixing, and applying heat treatment, the surface of primary and / or secondary particles of lithium metal composite oxides can be surface-treated with lithium and compounds of the added elements, thereby reducing the amount of lithium compounds remaining on the particle surface layer. Surface treatment can reduce the amount of lithium compounds remaining on the particle surface layer, improve lithium-ion conductivity, and reduce reaction resistance.

[0099] The added elemental compounds used for the above surface treatment 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 or more types can be used.

[0100] Lithium metal composite oxides produced by this process or a combination of processes have, for example, the general formula LiaNi1-xy-zCoxMnyMzO2+α (in which M is one or more elements other than Li, Ni, Co, Mn, and O). M is such that 0.90 ≤ a ≤ 1.15, 0 ≤ x ≤ 0.4, 0 ≤ y ≤ 0.4, 0 ≤ z ≤ 0.1, and -0.5 ≤ α ≤ 0.5. The values ​​of x, y, and z, as well as the type of element M, are the same as those for the metal composite hydroxides described above, and are therefore omitted here.

[0101] The value of "a" in the general formula is unrestricted, as long as it falls within the range of 0.90 ≤ a ≤ 1.15. For example, values ​​of 0.905 or greater, 0.91 or greater, 0.915 or greater, 0.92 or greater, 0.925 or greater, 0.93 or greater, 0.935 or greater, 0.94 or greater, 0.945 or greater, 0.95 or greater, 0.955 or greater, 0.96 or greater, 0.965 or greater, 0.97 or greater, 0.975 or greater, 0.98 or greater, 0.985 or greater, 0.99 or greater, 0.995 or greater, 1 or greater, 1.005 or greater, 1.01 or greater, 1.015 or greater, 1.02 or greater, 1.025, etc. Values ​​of 1.03 or greater, 1.035 or greater, 1.04 or greater, 1.045 or greater, 1.05 or greater, 1.055 or greater, 1.06 or greater, 1.065 or greater, 1.07 or greater, 1.075 or greater, 1.08 or greater, 1.085 or greater, 1.09 or greater, 1.095 or greater, 1.1 or greater, 1.105 or greater, 1.11 or greater, 1.115 or greater, 1.12 or greater, 1.125 or greater, 1.13 or greater, 1.135 or greater, 1.14 or greater, 1.145 or greater, and 1.15 or greater are 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.

[0102] The lithium metal composite oxide produced by the manufacturing method of the embodiments disclosed herein can be used as the cathode active material of a non-aqueous electrolyte secondary battery. Hereinafter, a non-aqueous electrolyte secondary battery using a lithium metal composite oxide is described. This non-aqueous electrolyte secondary battery is equipped with a positive electrode containing the aforementioned lithium metal composite oxide as the positive electrode active material, and the non-aqueous electrolyte secondary battery consists of a positive electrode, a negative electrode, and an electrolyte solution containing an electrolyte.

[0103] In manufacturing the cathode, a conductive agent and a binder are added to and mixed with the lithium metal composite oxide of the embodiments disclosed herein using conventional methods. For example, acetylene black, carbon black, graphite, etc., are preferably used as conductive agents. For example, polytetrafluoroethylene, polyvinylidene fluoride, etc., are preferably used as binders.

[0104] As the negative electrode, although not particularly restricted, one or more non-metallic or metallic elements selected from Si, Al, Sn, Pb, Zn, Bi, and Cd, alloys containing them, or chalcogenides containing them, as well as negative electrode active materials such as lithium metal, graphite, and low-crystallinity carbon materials, can be used. The use of chalcogenides containing them is also possible.

[0105] The solvent for the electrolyte is not restricted, but organic solvents containing one or more of carbonates (such as ethylene carbonate, propylene carbonate, dimethyl carbonate, and diethyl carbonate) or ethers (such as dimethoxyethane) can be used.

[0106] As electrolytes, in addition to lithium hexafluorophosphate (LiPF6), one or more of them can be used by dissolving lithium salts such as lithium perchlorate and lithium tetrafluoroborate in a solvent. Example

[0107] Embodiments of this disclosure are described below. This disclosure is not to be limited in any way by the description of the embodiments, but may be implemented with appropriate changes.

[0108] Example 1

[0109] A method for producing lithium metal composite oxide, the method comprising a step of calcining a mixture of 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 formed by the aggregation of primary particles; and when the particle size corresponding to the maximum peak of the volume-based particle size 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, among the secondary particles having a particle size of at least 30% having a particle size of Dt-1.2Dt, primary particles having a major axis length of 1 μm or greater account for 10% or more of the particle size, and the pore volume having a pore size of 0.06 μm or less is 0.15 mL / g or less.

[0110] Example 2

[0111] A method for producing lithium metal composite oxides, the method comprising the steps of calcining a metal composite hydroxide powder at 200°C or higher and less than 700°C to obtain a calcined product, and calcining a mixture of the calcined product and a lithium source at 700°C-950°C, wherein: the metal composite hydroxide powder contains at least nickel and includes secondary particles formed by the aggregation of primary particles; and when the particle size corresponding to the maximum peak of the volume-based particle size 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, in at least 30% of the secondary particles having a particle size of Dt-1.2Dt, primary particles having a major axis length of 1 μm or greater account for 10% or more of the particle number, and pores having a pore size of 0.06 μm or less have a pore volume of 0.15 mL / g or less.

[0112] Example 3

[0113] The method for producing lithium metal composite oxide according to any one of Examples 1 and 2, wherein the metal composite hydroxide powder comprises Ni 1-x-y-z Co x Mn y M z (OH) 2+α (where M is an element other than Li, Ni, Co, Mn and O, and satisfies the relations 0 ≤ x ≤ 0.4, 0 ≤ y ≤ 0.4, 0 ≤ z ≤ 0.1, and -0.5 ≤ α ≤ 0.5) represents a metal complex hydroxide.

[0114] Example 4

[0115] The method for producing lithium metal composite oxide according to any one of Examples 1 and 2, wherein, in the backscattered electron image of the cross section obtained using a scanning electron microscope, primary particles having a major axis length of 2 μm or greater account for 8% or more of the secondary particles having a particle size of Dt-1.2Dt, which constitute at least 30% of the particle number.

[0116] Example 5

[0117] The method for producing lithium metal composite oxide according to any one of Examples 1 and 2, wherein the BET specific surface area of ​​the metal composite hydroxide powder is 1 m². 2 / g-15 m 2 / g.

[0118] Example 6

[0119] A metal composite hydroxide powder containing at least nickel and comprising secondary particles formed by the aggregation of primary particles, wherein, when the particle size corresponding to the maximum peak of the volume-based particle size frequency distribution of the secondary particles is defined as Dt, in a backscattered electron image of the cross section obtained using a scanning electron microscope, among the secondary particles having a particle size of at least 30% having a particle size of Dt-1.2Dt, primary particles having a major axis length of 1 μm or greater account for 10% or more of the particle number, and the volume of pores having a pore size of 0.06 μm or less is 0.15 mL / g or less. Example

[0120] This disclosure is not limited to these examples.

[0121] Example 1

[0122] Nucleation stage: Nickel sulfate solution, cobalt sulfate solution, and manganese sulfate solution are mixed to obtain a Ni:Co:Mn molar ratio of Ni:Co:Mn = 55:20:25, thus obtaining a mixed solution. Ten liters of pure water are added to the reaction vessel, along with 200 g of ammonia. Then, sodium hydroxide solution is added to the reaction vessel to adjust the pH to 12, preparing the reaction matrix. The reaction vessel is purged with nitrogen at a flow rate of 0.7 L / min to generate a nitrogen atmosphere. The nitrogen atmosphere is maintained until the reaction is complete. While stirring the solution in the reaction vessel, the prepared mixed aqueous solution is added dropwise to prepare a liquid medium containing seed crystals.

[0123] Crystallization Stage: Following the seed crystal formation stage, sodium hydroxide, ammonia, and a mixed aqueous solution are fed into the reaction tank in a prescribed ratio to initiate the crystallization reaction. During the reaction, the volume of the reaction tank is maintained at a constant level. During the crystallization stage, the pH in the reaction tank is maintained at 11.7.

[0124] During the reaction, the drop rate of the feedstock remained constant, and the average particle size D50 remained at 17 μm. Meanwhile, the absence of secondary nuclei (seed nuclei) was confirmed by sampling and measuring the particle size distribution and BET surface area over time.

[0125] After the raw materials were added dropwise, the reaction was stirred for 1 hour to obtain a coprecipitate 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. Solid-liquid separation was then performed, and the coprecipitate, in cake form, was dried in air at 110°C for 12 hours to obtain a metal composite hydroxide sample. The volume-based average particle size D50 of the obtained metal composite hydroxide was 16.6 μm.

[0126] The metal composite hydroxide obtained as described above was subjected to a temporary sintering process, wherein it was heat-treated at 300°C for 4 hours under atmospheric conditions to obtain a metal composite compound. The obtained metal composite compound, lithium carbonate, and zirconium oxide were weighed and mixed such 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 a lithium-nickel composite oxide.

[0127] The obtained lithium metal composite oxide was mixed with boric acid powder to make the amount of B in the final lithium metal composite oxide sample 1000 ppm, and then heat-treated at 350°C for 2 hours in an oxygen atmosphere (oxygen concentration: 92 vol%) to obtain a cathode active material sample.

[0128] Example 2

[0129] In Example 1, the pH in the reaction vessel was maintained at 11.5 throughout the crystallization phase. During the reaction, the absence of secondary nuclei (seed nuclei) was confirmed by sampling and measuring particle size distribution and BET surface area over time. Surface morphology was examined using SEM images, and the dropping rate was gradually reduced as the particle size increased, eventually set to 1 / 5 of the initial dropping rate. The reaction was carried out to obtain lithium metal composite oxide samples with an average particle size D50 of 17 μm or greater, in the same manner as in Example 1. The obtained metal composite hydroxide had a volume-based average particle size D50 of 17.0 μm.

[0130] The metal composite hydroxide obtained as described above was subjected to a temporary sintering process, wherein it was heat-treated at 300°C for 4 hours in an atmospheric environment to obtain the 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, such that the final cathode active material had Li / (Ni + Co + Mn) = 1.050 and Zr / (Ni + Co + Mn + Zr) = 0.45 mol%. The composite oxide sample of Example 2 was obtained in the same manner as in Example 1.

[0131] Comparison Example 1

[0132] The metal composite hydroxide sample was obtained in the same manner as in Example 1, except that the pH was increased to 0.25 during the crystallization stage in Example 1 and the material droplet acceleration rate was increased stepwise. The volume-based average particle size D50 of the obtained metal composite hydroxide was 16.2 μm.

[0133] The subsequent operations were performed in the same manner as in Example 1 to obtain lithium metal composite oxide.

[0134] The samples from Examples 1 and 2, as well as the comparative example 1, were evaluated using the following method.

[0135] Compositional analysis of metal complex hydroxide and lithium metal complex oxide samples: 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 volumetric flask and purified water was added to prepare a conditioned solution. The obtained conditioned solution was subjected to ICP-AES (Optima 8300, Perkin Elmer Japan Co., Ltd.) for elemental determination.

[0136] The tap density of the metal composite hydroxide sample was measured by tapping it 500 times using a tap density meter.

[0137] The particle size (Dt) corresponding to the maximum peak apex of the metal complex hydroxide sample was determined by using a laser particle size distribution analyzer (Microtrac HRA, Nikkiso Corporation) and wet laser method to generate a volume-based particle size distribution.

[0138] The full width at half maximum (FWHM) of the metal-composite hydroxide samples was obtained by XRD diffraction under X-ray diffraction conditions using an X-ray diffractometer [SmartLab, Rigaku Corporation, Japan]. The XRD diffraction data were then used to calculate the FWHM of the metal-composite hydroxide samples and to perform Rietveld analysis using “RA Young, ed.”, Oxford University Press (1992). 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 to space group P-3m1.

[0139] (X-ray diffraction conditions)

[0140] X-ray source: Cu-Kα

[0141] Accelerating voltage and current: 45 kV and 200 mA

[0142] Sampling width: 0.02 degrees

[0143] Scan width: 5 degrees to 80 degrees

[0144] Scanning speed: 1.0 step / second

[0145] Diverging slit: 2 / 3 degree

[0146] Receiving slit width: 0.15 mm

[0147] Scattering slit: 2 / 3 degree

[0148] Scattering slit width: 2 / 3 degree

[0149] The pore distribution of metal-composite hydroxide samples was measured using an Autopore V9620 (Micromeritics) via mercury porosimetry.

[0150] Conditions for mercury porosimetry:

[0151] Preprocessing: No preprocessing.

[0152] Measurement: Pore distribution was obtained for pore sizes ranging from approximately 0.0036 to 200 μm.

[0153] Calculate the aperture using the Washburn formula shown below.

[0154] PD = -4σcosθ

[0155] (In the formula, P: pressure, σ: surface tension of mercury, D: pore size, θ: contact angle between mercury and sample)

[0156] Measurement conditions:

[0157] Surface tension of mercury: 480 dynes / cm

[0158] Contact angle between mercury and sample: 140 degrees

[0159] Method for measuring the length of primary particles in metal composite hydroxide samples: The length of primary particles in metal composite hydroxide samples was measured as follows. First, the metal composite hydroxide sample was cured with epoxy resin, and particle cross-sections were formed using an ion beam through a cross-section polisher (IB-19530CP, NEC Corporation). Then, images were captured using a field emission scanning electron microscope (JSM-7100F: NEC Corporation) at an accelerating voltage of 3 kV and a magnification of 3000 to 2000x. For secondary particles, 100 particles with diameters greater than Dt and less than 1.2 Dt were selected relative to the particle size Dt corresponding to the maximum peak obtained by particle size distribution measurement based on volume standards.

[0160] For all particles in which the outline of primary particles within secondary particles is visible in electron micrographs obtained from reflected electron images, the grain boundaries of primary particles within secondary particles are depicted using Paint, included in Microsoft Windows, and image processing software (e.g., ImageJ) is used to depict the images of the grain boundaries. The length of the particles in the long axis direction is calculated by binarizing the images of the grain boundaries using image processing software (e.g., ImageJ). Based on the obtained particle length data in the longitudinal direction, a kernel density distribution (based on particle number) is calculated using a standard normal distribution as the kernel function.

[0161] Evaluation was conducted using coin cells with cathode active material samples: 2032-type coin cells using cathode active material particles obtained by lithiation of lithium metal composite oxides were manufactured using cathodes, anodes, and electrolytes prepared by the following methods.

[0162] Positive electrode

[0163] Cathode: Acetylene black and graphite in a 1:1 ratio (by weight) were used as conductive agents, and polyvinylidene fluoride was used as a binder. These were mixed in N-methylpyrrolidone and coated onto aluminum foil. The sheet was dried at 110°C, punched to 15 mm Φ, and rolled at 3 t / cm² to form the cathode.

[0164] Anode: A 500 µm thick lithium foil with a punched diameter of 16 mm is used as the negative electrode.

[0165] Electrolyte: A mixed solvent of EC and DMC was prepared such that EC : DMC = 1 : 2 (volume ratio), and a 1 mol / L LiPF6 solution mixed with the electrolyte was used as the electrolyte.

[0166] Diaphragm: A diaphragm with a thickness of 0.5 mm and a die cut to 20 mm Φ is used (Celgard #2400, manufactured by Celgard).

[0167] Initial charge capacity and initial charge / discharge efficiency

[0168] Using the button cell manufactured by the above method, constant current charging was performed at 25°C with a current density of 0.2 C until 4.35 V (upper limit voltage), followed by constant voltage charging until the current reached 0.05 C. The capacity at this point was taken as the initial charge capacity (mAh / g).

[0169] Next, after a 10-minute pause, a constant current discharge was performed at a current density of 0.1 C to 2.50 V under the same conditions, and the initial discharge capacity (mAh / g) was measured after a 10-minute pause.

[0170] The initial charge / discharge efficiency is calculated using measurements of the initial charge capacity and initial discharge capacity, based on the following formula.

[0171] Initial charge / discharge efficiency (%) = (Initial discharge capacity / Initial charge capacity) × 100%

[0172] <Cycle Retention Rate>

[0173] Using the button cell manufactured by the method described above, 104 charge-discharge cycles were performed in a 60°C environment under the conditions shown below.

[0174] The 1st, 2nd, and 104th cycles:

[0175] After being charged to 4.3 V at a constant current of 0.2 C, it is then charged at a constant voltage until it reaches 0.01 C.

[0176] Pause for 5 minutes

[0177] Discharge at a constant current of 0.2 C to 3.0 V

[0178] Pause for 5 minutes

[0179] Cycles 3 through 103:

[0180] Charge at a constant current of 0.5 C to 4.3 V, then charge at a constant voltage until 0.01 C.

[0181] Pause for 5 minutes

[0182] 1 C constant current discharge to 3.0 V

[0183] Pause for 5 minutes

[0184] The cycle retention rate at 60°C is calculated using the discharge capacity measured at the 30th cycle and the discharge capacity measured at the 103rd cycle, based on the following formula.

[0185] Cycle retention rate (%)

[0186] = (Discharge capacity at the 103rd cycle / Discharge capacity at the 30th cycle) × 100%

[0187] The evaluation results are shown in Table 1.

[0188] .

Claims

1. A method for producing lithium metal composite oxides, the method comprising a step of calcining a mixture of 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 formed by the aggregation of primary particles; and when the particle size corresponding to the maximum peak of the volume-based particle size frequency distribution of the secondary particles is defined as Dt, in the backscattered electron image of the cross section obtained using a scanning electron microscope, in the secondary particles having a particle size of at least 30% having a particle size of Dt-1.2Dt, primary particles having a major axis length of 1 μm or greater account for 10% or more in terms of particle number, and the pore volume having a pore size of 0.06 μm or less is 0.15 mL / g or less.

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

3. The method for producing lithium metal composite oxides according to any one of claims 1 and 2, wherein, This metal composite hydroxide powder contains Ni... 1-x-y-z Co x Mn y M z (OH) 2+α (where M is an element other than Li, Ni, Co, Mn and O, and satisfies the relations 0 ≤ x ≤ 0.4, 0 ≤ y ≤ 0.4, 0 ≤ z ≤ 0.1, and -0.5 ≤ α ≤ 0.5) represents a metal complex hydroxide.

4. The method for producing lithium metal composite oxides according to any one of claims 1 and 2, wherein, In the backscattered electron images of the cross section obtained using a scanning electron microscope, primary particles with a diameter of Dt-1.2Dt account for 8% or more of the number of secondary particles, which constitute at least 30% of the total number of particles. Primary particles with a major axis length of 2 μm or greater account for 8% or more of the total number of particles.

5. The method for producing lithium metal composite oxides according to any one of claims 1 and 2, wherein, The BET specific surface area of ​​this metal composite hydroxide powder is 1 m². 2 / g-15 m 2 / g.

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