Method for manufacturing lithium metal complex oxide

Abstract

To provide a method for reducing the amount of lithium carbonate contained in the produced lithium metal complex oxide in the case of manufacturing a lithium metal complex oxide using a metal complex hydroxide as a raw material.SOLUTION: A method for manufacturing a lithium metal complex oxide according to the present disclosure comprises: a mixing step of preparing a mixture by mixing at least lithium hydroxide, a hydroxide containing a transition metal, and an additive compound which is a compound of an additive metal other than a transition metal and other than a carbonate; a first calcination step of calcination of the mixture at 500°C or higher and 650°C or lower to form a first calcined product as a lithium metal complex oxide containing at least lithium and a transition metal; and a second calcination step of calcination of the first calcined product above 650°C, wherein the carbonate of the additive metal has a solubility lower than that of lithium carbonate and a melting point higher than the calcination temperature of the second calcination step.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for producing a lithium metal composite oxide. [Background technology]

[0002] Lithium ion secondary batteries, which are small, lightweight, have high energy density, high charge / discharge voltage, and large charge / discharge capacity, have been attracting attention as power sources for electronic devices such as AV equipment and personal computers. Examples of positive electrode active materials useful for such lithium ion secondary batteries include those with the composition formula Li a (Ni x Co y M z A positive electrode active material made of a lithium metal composite oxide (wherein M is a metal such as Mn, Mg, or Al) having a basic composition represented by the formula:

[0003] Fig. 3 is a flow diagram of a conventional method for producing a lithium metal composite oxide. As shown in Fig. 3, the lithium metal composite oxide is usually obtained by preparing a metal composite hydroxide from a nickel compound, a cobalt compound, and a compound of a metal such as Mn, Mg, or Al, and then calcining the metal composite oxide to obtain a precursor metal composite oxide, and further calcining a mixture of the metal composite oxide and a lithium compound (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-198195 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the method disclosed in Patent Document 1, lithium and a metal composite hydroxide react to form a metal composite oxide for the first time in the calcination process, and the bulkiness of the resulting mixture decreases to about 70% of its original size before and after the reaction. This decrease in bulkiness is a factor that reduces productivity.

[0006] Therefore, the inventors have focused on a method of using a metal composite hydroxide as a precursor as it is, mixing it with lithium hydroxide and performing pre-calcination to form a lithium metal composite oxide in advance, and then performing main calcination. According to this method, since the metal composite oxide is formed before the main calcination, there is almost no change in bulkiness before and after the main calcination, and there is no loss of productivity due to the change in bulkiness.

[0007] However, it was found that the lithium metal composite oxide obtained through such a calcination process contains a large amount of lithium carbonate. This is thought to be mainly formed by the reaction of carbonate ions contained in the metal composite hydroxide with lithium hydroxide. In the above-mentioned conventional method, a heat treatment is performed when changing the metal composite hydroxide into the metal composite oxide, and many of the carbonate ions are released by this heating, so the carbonate ions contained in the metal composite oxide are very small, and even if this is reacted with lithium hydroxide, the amount of lithium carbonate produced is small. However, when the metal composite hydroxide is reacted directly with lithium hydroxide, the carbonate ions are not released before the reaction and lithium carbonate is formed.

[0008] Here, lithium metal composite oxides containing a large amount of lithium carbonate can cause gelation during the preparation of electrodes using the same as a positive electrode active material. In addition, in lithium ion secondary batteries using a positive electrode containing the same as a positive electrode active material, the amount of carbon dioxide gas generated increases due to a reaction inside the battery during high-temperature storage, causing the battery to expand. Therefore, it is required to reduce the lithium carbonate content in lithium metal composite oxides.

[0009] The present disclosure has been made in consideration of the above-mentioned circumstances, and has an object to provide a method for producing a lithium metal composite oxide using a metal composite hydroxide as a raw material, which can reduce the amount of lithium carbonate contained in the produced lithium metal composite oxide. [Means for solving the problem]

[0010] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, the present inventors have found a method for producing a lithium metal composite oxide, comprising: a mixing step of mixing at least lithium hydroxide, a hydroxide containing a transition metal, and an additive compound, which is a compound other than a carbonate of an additive metal other than the transition metal, to prepare a mixture; a first firing step of firing the mixture at 500° C. to 650° C. to form a first fired product as a lithium metal composite oxide containing at least lithium and the transition metal; and a second firing step of firing the first fired product at a temperature higher than 650° C., in which the carbonate of the additive metal has a lower solubility than that of lithium carbonate and a melting point higher than the firing temperature of the second firing step; or a first mixing step of mixing at least lithium hydroxide and a hydroxide containing a transition metal to prepare a first mixture; The inventors have found that a method for producing a lithium metal composite oxide, which includes a first firing step of firing the above-mentioned mixture at 500° C. to 650° C. to form a first fired product as a lithium metal composite oxide containing at least lithium and a transition metal, a second mixing step of mixing at least the first fired product with an additive compound that is a compound other than a carbonate of an additive metal other than a transition metal to prepare a second mixture, and a second firing step of firing the second mixture at a temperature higher than 650° C., in which the carbonate of the additive metal has a lower solubility than that of lithium carbonate and a melting point higher than the firing temperature of the second firing step, can reduce the amount of lithium carbonate contained in a lithium metal composite oxide used as a positive electrode active material for a non-aqueous electrolyte secondary battery, and have invented the method of the present disclosure. Specifically, the present disclosure provides the following.

[0011] (1) a mixing step of mixing at least lithium hydroxide, a hydroxide containing a transition metal, and an additive compound that is a compound other than a carbonate of an additive metal other than the transition metal to prepare a mixture; a first firing step of firing the mixture at 500° C. or more and 650° C. or less to form a first fired product as a lithium metal composite oxide containing at least lithium and the transition metal; A second firing step of firing the first fired product at a temperature of more than 650°C; The carbonate of the added metal has a solubility lower than that of lithium carbonate and a melting point higher than the firing temperature of the second firing step. A method for producing a lithium metal composite oxide.

[0012] (2) a first mixing step of mixing at least lithium hydroxide and a hydroxide containing a transition metal to prepare a first mixture; a first firing step of firing the first mixture at 500° C. or more and 650° C. or less to form a first fired product as a lithium metal composite oxide containing at least lithium and the transition metal; a second mixing step of mixing at least the first fired product with an additive compound that is a compound other than a carbonate of an additive metal other than a transition metal to prepare a second mixture; A second firing step of firing the second mixture at above 650°C; Including, The carbonate of the added metal has a solubility lower than that of lithium carbonate and a melting point higher than the firing temperature of the second firing step. A method for producing a lithium metal composite oxide.

[0013] (3) The method for producing a lithium metal composite oxide according to (1) or (2), wherein the additive compound is a hydroxide or an oxide.

[0014] (4) The method for producing a lithium metal composite oxide according to (1) or (2), wherein the transition metal includes nickel.

[0015] (5) The method for producing a lithium metal composite oxide according to (4), wherein the content of the nickel in the produced lithium metal composite oxide is 80 mol % or more based on the elements excluding lithium and oxygen. Effect of the Invention

[0016] According to the present disclosure, when a lithium metal composite oxide is produced using a metal composite hydroxide as a raw material, a method can be provided that can reduce the amount of lithium carbonate contained in the produced lithium metal composite oxide. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a flow diagram of a method for producing a lithium metal composite oxide according to a first embodiment. [Diagram 2] FIG. 4 is a flow diagram of a method for producing a lithium metal composite oxide according to a second embodiment. [Diagram 3] FIG. 1 is a flow diagram of a conventional method for producing a lithium metal composite oxide. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, embodiments of the present disclosure will be described, however, the present disclosure is not limited in any way to the description of the following embodiments and can be implemented with appropriate modifications.

[0019] <<Method for producing lithium metal composite oxide according to the first embodiment>> The method for producing a lithium metal composite oxide according to the first embodiment of the present disclosure includes at least a mixing step of mixing lithium hydroxide, a hydroxide containing a transition metal, and an additive compound, which is a compound other than a carbonate of an additive metal other than the transition metal, to prepare a mixture; a first firing step of firing the mixture at 500° C. or higher and 650° C. or lower to form a first fired product as a lithium metal composite oxide containing at least lithium and the transition metal; and a second firing step of firing the first fired product at a temperature higher than 650° C., wherein the carbonate of the additive metal has a solubility lower than that of lithium carbonate and a melting point higher than the firing temperature in the second firing step.

[0020] According to this manufacturing method, the lithium hydroxide reacts with the hydroxide containing the transition metal in the first firing step to form a lithium metal composite oxide. Therefore, the bulkiness hardly changes in the second firing step in which firing is performed at a high temperature, and the production efficiency of the second firing step can be improved. If the bulkiness decreases in the high-temperature firing, the amount of raw material that can be filled in the furnace will decrease by the amount of the decrease.

[0021] In addition, in such a manufacturing method with improved productivity, an additive compound that is a compound other than a carbonate of an additive metal other than a transition metal is used as a raw material other than each metal source of the lithium metal composite oxide. In this additive compound, the carbonate of the additive metal has a lower solubility than that of lithium carbonate and a melting point higher than the heating temperature of the second baking step. Here, since the solubility of the carbonate of the additive metal is lower than that of lithium carbonate, the compound of the additive metal easily absorbs carbonate ions and suppresses the formation of lithium carbonate. In addition, since the melting point of the carbonate of the additive metal is higher than the heating temperature of the second baking step, once the carbonate is absorbed, carbon dioxide is not released again. This makes it possible to reduce the content of lithium carbonate contained in the lithium metal composite oxide produced, and to suppress the adverse effects caused by lithium carbonate.

[0022] [Lithium metal composite oxide] The lithium metal composite oxide produced by the production method of this embodiment is not particularly limited as long as it contains a transition metal, but in one embodiment, the nickel content is preferably 80 mol % or more, and more preferably 85 mol % or more, based on the elements excluding lithium and oxygen. a Ni 1-x-y-z Co x Mn y M z O 2+α (wherein M is an element other than Li, Ni, Co, Mn, and O, and 0.95≦a≦1.15, 0≦x≦0.4, 0≦y≦0.4, 0≦z≦0.1, −0.5≦α≦0.5, and 1-xyz≧0.8).

[0023] In the general formula, the value of x is not particularly limited as long as it is within the range of 0≦x≦0.4, and examples thereof include: more than 0, 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.It is preferable that the molecular weight is 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, or 0.397 or more. On the other hand, the values ​​of x are 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 Below, 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, 0.3 12 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 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 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, 0.19 2 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 It is preferable that the ratio is 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, 0.0055 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, or 0.001 or less.

[0024] In the general formula, the value of y is not particularly limited as long as it is within the range of 0≦y≦0.4, and may be, 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, 0.235 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, 0.282 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.It is preferable that the molecular weight is 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, or 0.397 or more. On the other hand, the values ​​of y are 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 Below, 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, 0.3 12 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 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 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, 0.19 2 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 It is preferable that the ratio is 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, 0.0055 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, or 0.001 or less.

[0025] In the general formula, the value of z is not particularly limited as long as it is within the range of 0≦z≦0.1, and may be, 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, above,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, 0.0 It is preferable that the ratio is 5 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, 0.082 or more, 0.085 or more, 0.087 or more, 0.09 or more, 0.092 or more, 0.095 or more, or 0.097 or more.On the other hand, the values ​​of z are 0.097 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, 0.0082 or less, 0.008 or less, 0.0077 or less, 0.0075 or less, 0.0072 less than or equal to 0.007, less than or equal to 0.0067, less than or equal to 0.0065, less than or equal to 0.0062, less than or equal to 0.006, less than or equal to 0.0057, less than or equal to 0.0055, less than or equal to 0.0052, 0.00 It is preferable that the above-mentioned range is 5 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, or 0.001 or less.

[0026] In the general formula, the element M is not particularly limited as long as it is one or more elements other than Li, Ni, Co, Mn, and O, and examples of the element M that can be used include Al, Ti, Mg, Zn, Nb, W, Mo, Sb, V, Cr, Ca, Fe, Ga, Sr, Y, Ru, In, Sn, Ta, Bi, Zr, and B. The type of element M may be selected depending on the purpose of addition. When the element M contains multiple elements, the value of z represents the total amount of the multiple elements.

[0027] 1 is a flow diagram of the method for producing a lithium metal composite oxide according to the first embodiment. Each step will be described below.

[0028] [Mixing process] The mixing step S11 is a step of mixing at least lithium hydroxide, a hydroxide containing a transition metal, and an additive compound that is a compound other than a carbonate of an additive metal other than a transition metal to prepare a mixture.

[0029] (hydroxides containing transition metals) The hydroxide containing a transition metal is a precursor compound of the lithium metal composite oxide to be produced. The transition metal contained in the hydroxide containing a transition metal is not particularly limited as long as it is a transition metal that constitutes the lithium metal composite oxide to be produced, and for example, one or more selected from Ni, Co, Mn, Ti, Nb, W, Mo, V, Cr, Fe, Y, Ta, Zr, etc. can be used. In one embodiment, the transition metal preferably contains nickel.

[0030] In one embodiment, the hydroxide containing a transition metal may have the same ratio of hydrogen, oxygen, and elements other than lithium (transition metals and elements described below) as the lithium metal composite oxide to be produced. When multiple elements other than hydrogen, oxygen, and lithium are contained, a metal composite hydroxide containing multiple elements may be formed.

[0031] In addition, the hydroxide containing a transition metal may be used as a metal composite hydroxide containing elements such as Al, Mg, Zn, Sb, Ga, Ru, In, Sn, Bi, and B in addition to the transition metal, so long as it contains one or more transition metals.

[0032] (additional compound) The additive compound is a compound other than a carbonate among compounds of additive metals other than transition metals. Here, the additive metal is one whose solubility of carbonate is lower than that of lithium carbonate and whose melting point is higher than the firing temperature of the second firing step. Examples of metal elements whose solubility of carbonate is higher than that of lithium carbonate (175 mmol / L) and whose melting point is higher than the firing temperature of the second firing step (over 650°C) include Sr (solubility 0.07 mmol / L, melting point 1497°C), Ca (solubility 0.15 mmol / L, melting point 825°C), Ba (solubility 0.12 mmol / L, melting point 811°C), etc. Here, the solubility refers to the solubility in water at 25°C, and the high and low solubility are compared in terms of molar amount. The melting point of the carbonate is not particularly limited as long as it is higher than the firing temperature in the second firing step, but is preferably higher than the firing temperature in the second firing step by, for example, 5° C. or more, 10° C. or more, 15° C. or more, 20° C. or more, 25° C. or more, 30° C. or more, 35° C. or more, 40° C. or more, 45° C. or more, or 50° C. or more. The melting point of the carbonate may be, for example, 1500° C. or less, 1000° C. or less, relative to the firing temperature in the second firing step.

[0033] The calcium compound is not particularly limited, but examples of the calcium compound that can be used include calcium hydroxide, calcium oxide, calcium chloride, calcium phosphite, calcium monohydrogen phosphate, calcium dihydrogen phosphate, calcium hypochlorite, and calcium fluoride.

[0034] The strontium compound is not particularly limited, but for example, strontium hydroxide, strontium oxide, strontium chloride, strontium fluoride, strontium phosphate, etc. can be used.

[0035] The barium compound is not particularly limited, but for example, barium hydroxide, barium oxide, barium chloride, barium phosphate, etc. can be used.

[0036] Among the above-mentioned additive compounds, the hydroxide or oxide is preferable. Specifically, the additive compound is preferably one or more selected from the group consisting of calcium hydroxide, calcium oxide, strontium hydroxide, strontium oxide, barium hydroxide, and barium oxide.

[0037] (Compounds of other elements) As the transition metal source, in addition to the above-mentioned hydroxides containing a transition metal, oxides, nitrates, chlorides, iodides, pure metals, etc. containing a transition metal may be used.

[0038] A doping source compound may also be added. Specifically, the doping source compound may be at least one selected from the group consisting of cobalt oxide, cobalt hydroxide, manganese oxide, manganese hydroxide, manganese carbonate, magnesium oxide, magnesium hydroxide, aluminum oxide, aluminum hydroxide, aluminum chloride, aluminum fluoride, titanium oxide, titanium hydroxide, titanium chloride, zinc oxide, niobium oxide, niobium hydroxide, niobium chloride, tungsten oxide, tungsten chloride, molybdenum oxide, vanadium oxide, chromium oxide, iron oxide, iron hydroxide, and zirconium oxide.

[0039] A coating source compound may also be added. Specifically, the coating source compound may be at least one selected from the group consisting of gallium oxide, potassium oxide, potassium hydroxide, barium oxide, barium hydroxide, barium chloride, calcium oxide, calcium hydroxide, gallium oxide hydroxide, strontium oxide, strontium hydroxide, yttrium oxide, ruthenium oxide, indium oxide, tin oxide, tantalum oxide, bismuth oxide, boric acid, boron oxide, boron carbide, phosphoric acid, and ammonium hydrogen phosphate.

[0040] It is preferable to thoroughly mix the above-mentioned raw materials. If the mixing is insufficient, the ratio of lithium to other metals may vary depending on the part, and sufficient battery characteristics may not be obtained. A general mixer may be used for mixing. For example, a shaker mixer, a Lödige mixer, a Julia mixer, a V blender, etc. may be used.

[0041] The ratio of each raw material is not particularly limited, but may usually be set according to the element ratio in the lithium metal composite oxide to be produced. However, if there is an increase or decrease in these ratios in a later process, the ratio may be set taking such increase or decrease into consideration.

[0042] [First firing step] The first firing step S12 is a step of firing the mixture at 500° C. or more and 650° C. or less to form a first fired product as a composite oxide containing at least lithium and a transition metal.

[0043] By this first firing step S12, a lithium metal composite oxide containing at least lithium and a transition metal is formed from the mixture.

[0044] In the first calcination step S12, it is preferable to adopt a calcination method that promotes the lithiation of the composite oxide. Specifically, a method can be mentioned in which the mixture is made more susceptible to heat, gas generated from the lithium source is easily discharged, and gas with a high oxygen partial pressure is diffused in the mixture (particles).

[0045] In the first firing step S12, the mixture can be filled into a sagger or crucible and fired using a stationary furnace, roller hearth kiln, pusher furnace, etc., but a rotary kiln in which the mixture is fired while flowing can also be used.

[0046] The firing temperature in the first firing step S12 is not particularly limited as long as it is 500°C or more and 650°C or less. By setting the firing temperature in the above range, the lithium hydroxide and the metal composite hydroxide in the mixture can be reacted, and the generation of a different phase can be suppressed to obtain a lithium metal composite oxide. The firing temperature in the first firing step S12 is preferably 510°C or more and 520°C or more. In addition, the firing temperature in the first firing step S12 is preferably 630°C or less, 610°C or less, 590°C or less, or 580°C or less. Note that the firing temperature in the present disclosure is the maximum temperature when the object to be heated (in this step, firing) is heated. The maximum temperature refers to the temperature of the hottest part of the object to be heated. In the following, the term maximum temperature has the same definition.

[0047] The gas atmosphere in the first firing step S12 is not particularly limited as long as it is an oxidizing atmosphere that reliably advances the lithium conversion reaction and oxidation reaction of the metal composite oxide. For example, it is preferable to use a decarbonated oxidizing gas atmosphere with a carbon dioxide gas concentration of 30 ppm or less, or an oxygen atmosphere with an oxygen concentration of 80 vol% or more, 90 vol% or more.

[0048] The calcination time in the first calcination step S12 is not particularly limited as long as it is a time that allows the lithiation reaction of the metal composite oxide to proceed, and is preferably, for example, 1 hour or more, 2 hours or more, or 3 hours or more. On the other hand, the calcination time in the first calcination step S12 is preferably, for example, 10 hours or less, 9 hours or less, or 8 hours or less. The calcination time refers to the time during which the maximum temperature is maintained within the above-mentioned temperature range. Hereinafter, the term calcination time has the same definition.

[0049] [Second firing step] The second firing step S13 is a step of firing the first fired product at a temperature of more than 650°C.

[0050] In the second firing step S13, the lithium metal composite oxide formed in the above-mentioned first firing step S13 is heated at a higher temperature to cause crystal growth, thereby obtaining a second fired product which is a lithium metal composite oxide with high crystallinity.

[0051] The gas atmosphere in the second firing step S13 is not particularly limited as long as it is a non-reducing atmosphere in which crystal growth occurs and the transition metal contained in the lithium metal composite oxide is not reduced, and preferably has a low moisture content and carbon dioxide concentration. For example, it is preferable to use a decarbonated oxidizing gas atmosphere with a carbon dioxide concentration of 30 ppm or less, or an oxygen atmosphere with an oxygen concentration of 80 vol% or more, 90 vol% or more.

[0052] The firing temperature in the second firing step S13 is not particularly limited as long as it is over 650°C, but is preferably, for example, 660°C or higher, 670°C or higher, 680°C or higher, 690°C or higher, or 700°C or higher. On the other hand, the firing temperature in the second firing step S13 is preferably 1100°C or lower, 1050°C or lower, 1000°C or lower, 980°C or lower, 950°C or lower, 920°C or lower, 880°C or lower, 850°C or lower, 820°C or lower, 810°C or lower, 800°C or lower, 790°C or lower, or 780°C or lower. By setting the firing temperature within the required range, it is possible to reduce the unreacted portion and obtain a lithium metal composite oxide with high crystallinity, and therefore it is also possible to prevent a decrease in the battery characteristics of a nonaqueous electrolyte secondary battery using the obtained lithium metal composite oxide as a positive electrode.

[0053] The calcination time in the second calcination step S13 is not particularly limited as long as it is a time that allows the crystal growth of the metal composite oxide to proceed, and is preferably, for example, 1 hour or more, 2 hours or more, or 3 hours or more. On the other hand, the calcination time in the second calcination step S13 is preferably, for example, 15 hours or less, 14 hours or less, 13 hours or less, 12 hours or less, 11 hours or less, 10 hours or less, 9 hours or less, or 8 hours or less.

[0054] [Cleaning process] Although not shown, the method for producing the lithium metal composite oxide according to the first embodiment may include a washing step. The washing step is a step for washing the lithium metal composite oxide obtained in the second calcination step S13. In the lithium metal composite oxide obtained in the second calcination step S13, carbonate ions are absorbed by the action of the additive compound, and the production of lithium carbonate is suppressed, but a small amount of lithium carbonate may still be generated. In addition, unreacted lithium hydroxide and lithium compounds generated by the movement of lithium ions from the crystal to the particle surface during the calcination process may be present. Therefore, in order to remove and reduce these impurities, for example, washing with water and heat treatment drying can be performed. Note that the washing step is not an essential configuration.

[0055] [Surface treatment process] Although not shown, the method for producing a lithium metal composite oxide according to the first embodiment may include a surface treatment step. The surface treatment step is a step of performing a surface treatment on the lithium metal composite oxide obtained in the second firing step or washing step. The lithium metal composite oxide obtained in the second firing step or washing step is mixed with a compound of a predetermined element and subjected to a heat treatment, whereby the surface of the primary particles and / or secondary particles of the lithium metal composite oxide can be surface-treated with a compound of lithium and the added element. This can provide effects such as reducing the amount of lithium compounds remaining on the particle surface layer, improving lithium ion conductivity, and reducing reaction resistance. The surface treatment step is not an essential configuration.

[0056] The element compound added for the above-mentioned surface treatment can be, for example, one or more of an aluminum compound, a boron compound, a tungsten compound, a manganese compound, a cobalt compound, a phosphorus compound, a niobium compound, a strontium compound, an antimony compound, a zirconium compound, a titanium compound, and the like.

[0057] <<Method for producing lithium metal composite oxide according to the second embodiment>> A method for producing a lithium metal composite oxide according to a second embodiment of the present disclosure includes a first mixing step of mixing lithium hydroxide and a hydroxide containing a transition metal to prepare a first mixture, a first firing step of firing the first mixture at 500° C. or more and 650° C. or less to form a first fired product as a lithium metal composite oxide containing at least lithium and a transition metal, a second mixing step of mixing at least the first fired product with an additive compound that is a compound other than a carbonate of an additive metal other than the transition metal to prepare a second mixture, and a second firing step of firing the second mixture at a temperature higher than 650° C., wherein the carbonate of the additive metal has a lower solubility than that of lithium carbonate and a melting point higher than the firing temperature of the second firing step.

[0058] As described above, the additive compound easily absorbs carbonate ions and suppresses the formation of lithium carbonate. If the additive compound is added to the raw material before the second calcination step in which the raw material is heated at a high temperature, the additive compound can absorb many carbonate ions, including carbonate ions that have already formed lithium carbonate. Therefore, unlike the method for producing a lithium metal composite oxide of the first embodiment, the content of lithium carbonate in the produced lithium metal composite oxide can be reduced by adding the additive compound after calcination at 500°C or more and 650°C or less, in the same way as in the method for producing a lithium metal composite oxide of the first embodiment.

[0059] 2 is a flow diagram of the method for producing a lithium metal composite oxide according to the second embodiment. Each step will be described below.

[0060] [First mixing step] The first mixing step S21 is a step of mixing at least lithium hydroxide and a hydroxide containing a transition metal to prepare a first mixture.

[0061] The first mixing step S21 is the same as the mixing step S11 in the method for producing a lithium metal composite oxide according to the first embodiment except that no additive compound is mixed, and therefore the description of the mixing step S11 in the method for producing a lithium metal composite oxide according to the first embodiment can be cited, and therefore a detailed description here is omitted.

[0062] [First firing step] The first firing step S22 is a step of firing the first mixture at 500° C. or more and 650° C. or less to form a first fired product as a composite oxide containing at least lithium and a transition metal.

[0063] The first firing step S22 is similar to the first firing step S12 of the method for producing a lithium metal composite oxide of the first embodiment, except that the first mixture does not contain an additive compound, and therefore the description of the first firing step S12 of the method for producing a lithium metal composite oxide of the first embodiment can be cited, and therefore a detailed description here is omitted.

[0064] [Second mixing step] The second mixing step S23 is a step of mixing at least the first fired product and an additive compound to prepare a second mixture.

[0065] The second mixing step S23 is similar to the first mixing step S21 except that the first fired product and the additive compound are mixed (the objects to be mixed), and therefore the description of the first mixing step S21 can be cited. Therefore, a detailed description here is omitted.

[0066] [Second firing step] The second firing step S24 is a step of firing the second fired product at a temperature of more than 650°C.

[0067] The second calcination step S24 is similar to the second calcination step S13 of the method for producing a lithium metal composite oxide of the first embodiment, except that the second calcined product (object of calcination) is used, and therefore the description of the second calcination step S23 of the method for producing a lithium metal composite oxide of the first embodiment can be cited, and therefore a detailed description here is omitted.

[0068] [Cleaning process] Although not shown, a washing step may be provided in the method for producing a lithium metal composite oxide according to the second embodiment. The washing step is also similar to that in the method for producing a lithium metal composite oxide according to the first embodiment, and therefore the description of the washing step in the method for producing a lithium metal composite oxide according to the first embodiment can be cited. Therefore, a detailed description here is omitted.

[0069] [Surface treatment process] Although not shown, a surface treatment step may be provided in the method for producing a lithium metal composite oxide according to the second embodiment. The surface treatment step is similar to the surface treatment step in the method for producing a lithium metal composite oxide according to the first embodiment, and the description of the surface treatment step in the method for producing a lithium metal composite oxide according to the first embodiment can be cited. Therefore, a detailed description here is omitted.

[0070] <Nonaqueous electrolyte secondary battery> The nonaqueous electrolyte secondary battery according to the embodiment of the present disclosure includes a positive electrode containing the above-described composite oxide as a positive electrode active material, and the nonaqueous electrolyte secondary battery is composed of a positive electrode, a negative electrode, and an electrolyte solution containing an electrolyte.

[0071] When manufacturing a positive electrode, a conductive agent and a binder are added to the composite oxide according to the embodiment of the present disclosure and mixed according to a conventional method. As the conductive agent, for example, acetylene black, carbon black, graphite, etc. are preferably used. As the binder, for example, polytetrafluoroethylene, polyvinylidene fluoride, etc. are preferably used.

[0072] The negative electrode is not particularly limited, but may be, for example, not only a negative electrode active material such as lithium metal, graphite, or a low-crystalline carbon material, but also one or more nonmetallic or metallic elements selected from Si, Al, Sn, Pb, Zn, Bi, and Cd, an alloy containing the same, or a chalcogen compound containing the same.

[0073] The solvent for the electrolyte is not particularly limited, but may be, for example, an organic solvent containing one or more selected from carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, and diethyl carbonate, and ethers such as dimethoxyethane.

[0074] As the electrolyte, in addition to lithium hexafluorophosphate (LiPF6), one or more selected from lithium salts such as lithium perchlorate and lithium tetrafluoroborate can be dissolved in a solvent and used. EXAMPLES

[0075] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0076] <Evaluation> The obtained samples were evaluated by the methods described below.

[0077] [Composition analysis of metal composite hydroxides and lithium metal composite oxides] The composition of the metal composite hydroxide and the lithium metal composite oxide was determined by the following method. 0.2 g of the metal composite hydroxide and the lithium metal composite oxide sample was dissolved by heating in 25 ml of 20% hydrochloric acid solution, cooled, transferred to a 100 ml measuring flask, and pure water was added to prepare an adjusted solution. The elements of the obtained adjusted solution were quantified using ICP-AES (Optima 8300, manufactured by PerkinElmer Japan Co., Ltd.).

[0078] [Measurement of remaining lithium carbonate amount] The amount of remaining lithium carbonate in the lithium metal composite oxide samples of the examples and comparative examples was measured and calculated based on the Warder method in neutralization titration. Specifically, 20 g of the particle powder of the sample was added to 100 mL of water, stirred at room temperature for 20 minutes, and then the solid content was filtered and removed to obtain a supernatant, which was titrated with 0.2 N hydrochloric acid to obtain the amount of lithium carbonate. On a pH curve plotted with the titration amount (mL) on the horizontal axis and the pH of the supernatant on the vertical axis, pH=8.4 was set as the first titration point and pH=4.9 as the second titration point, and the amount of lithium carbonate was calculated using a formula from the titration amounts at these points.

[0079] <Preparation of lithium metal composite oxide samples> The composite oxide samples of Examples 1 to 5 and Comparative Examples 1 to 6 were prepared by the methods described below.

[0080] [Preparation of metal composite hydroxide] First, a method for preparing the metal composite hydroxide used as a raw material for the lithium metal composite oxide in each of the examples and comparative examples will be described.

[0081] A mixed aqueous solution was obtained by mixing an aqueous nickel sulfate solution, an aqueous cobalt sulfate solution, and an aqueous aluminum sulfate solution so that the ratio (molar ratio) of Ni, Co, and Al was Ni:Co:Al = 90:6:4. 10 L of pure water to which 300 g of an aqueous sodium hydroxide solution and 500 g of an aqueous ammonia solution had been added was prepared in advance in the reaction tank as a mother liquid, and a nitrogen atmosphere was created in the reaction tank by adding nitrogen gas at a flow rate of 0.7 L / min, and the reaction was also carried out in a nitrogen atmosphere.

[0082] Thereafter, while rotating the stirring blade at 1000 rpm, the mixed aqueous solution, sodium hydroxide aqueous solution, and ammonia water were simultaneously dropped at a predetermined rate, and the amount of the alkaline solution dropped was adjusted so that the pH became 11.7. Through a crystallization reaction, Ni, Co, and Al were crystallized and coprecipitated to form agglomerated particles, thereby obtaining a coprecipitate.

[0083] After that, the slurry in the reactor was separated into solid and liquid, and further washed with pure water to reduce residual impurities. The coprecipitate cake was then dried at 100°C for 10 hours in an air environment to obtain the product with the formula Ni 0.90 Co 0.06 Al 0.04 A nickel-cobalt-aluminum composite hydroxide represented by (OH)2 was obtained.

[0084] [Preparation of lithium metal composite oxide sample by the manufacturing method of the first embodiment] The lithium metal composite oxide samples of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3 were prepared by the following method.

[0085] (Example 1-1) A mixture was obtained by weighing and mixing the metal composite hydroxide, anhydrous lithium hydroxide, and calcium hydroxide (Ca(OH)2) so that the molar ratios were Li / (Ni+Co+Al) = 1.035 and Ca / (Ni+Co+Al) = 0.005. The resulting mixture was pre-baked in an oxygen atmosphere (oxygen concentration: 97 vol%) at 500° C. for 1 hour.

[0086] Next, the mixture was sintered in an oxygen atmosphere (oxygen concentration: 97 vol%) at a maximum temperature of 750° C. for 4.5 hours, and the sintered product was pulverized to obtain a sintered lithium nickel composite oxide sample.

[0087] The obtained lithium nickel composite oxide powder was mixed with pure water adjusted to a liquid temperature of 25°C so that the ratio was 1250g / L to prepare a slurry, which was stirred for 10 minutes and then dehydrated to obtain a cake-like compound. The cake-like compound was dried in a vacuum dryer at 70°C for 2 hours and at 185°C for 10 hours to obtain a lithium metal composite oxide sample.

[0088] (Example 1-2) A lithium metal composite oxide sample was obtained in the same manner as in Example 1, except that the precursor composite hydroxide, anhydrous lithium hydroxide, and anhydrous strontium hydroxide (Sr(OH)2) were weighed and mixed to obtain a mixture with a molar ratio of Li / (Ni+Co+Al) = 1.035 and Sr / (Ni+Co+Al) = 0.005.

[0089] (Examples 1-3) A lithium metal composite oxide sample was obtained in the same manner as in Example 1, except that the precursor composite hydroxide, anhydrous lithium hydroxide, and anhydrous barium hydroxide (Ba(OH)2) were weighed and mixed to obtain a mixture with a molar ratio of Li / (Ni+Co+Al) = 1.035 and Sr / (Ni+Co+Al) = 0.005.

[0090] (Comparative Example 1-1) The precursor composite hydroxide and anhydrous lithium hydroxide were weighed out and mixed so as to give a molar ratio of Li / (Ni+Co+Al)=1.035 to obtain a mixture. The resulting mixture was subjected to a first firing in an oxygen atmosphere (oxygen concentration: 97 vol%) at 500° C. for 1 hour.

[0091] Next, a second firing was carried out in an oxygen atmosphere (oxygen concentration: 97 vol%) at a maximum temperature of 750° C. for 4.5 hours, and the resulting fired product was pulverized to obtain a fired lithium metal composite oxide sample.

[0092] The obtained lithium metal composite oxide powder was mixed with pure water adjusted to a liquid temperature of 25°C so that the ratio was 1250 g / L to prepare a slurry, which was stirred for 10 minutes and then dehydrated to obtain a cake-like compound. The cake-like compound was dried in a vacuum dryer at 70°C for 2 hours and at 185°C for 10 hours to obtain a lithium metal composite oxide sample.

[0093] (Comparative Example 1-2) A lithium metal composite oxide sample was obtained in the same manner as in Example 1, except that the precursor composite hydroxide, anhydrous lithium hydroxide, and magnesium hydroxide (Mg(OH)2) were weighed and mixed to obtain a mixture with a molar ratio of Li / (Ni+Co+Al) = 1.035 and Mg / (Ni+Co+Al) = 0.005.

[0094] (Comparative Example 1-3) A lithium metal composite oxide sample was obtained in the same manner as in Example 1, except that the precursor composite hydroxide, anhydrous lithium hydroxide, and sodium hydroxide (NaOH) were weighed and mixed to obtain a mixture with a molar ratio of Li / (Ni+Co+Al) = 1.035 and Mg / (Ni+Co+Al) = 0.005.

[0095] [Preparation of lithium metal composite oxide sample by the manufacturing method of the second embodiment] The lithium metal composite oxide samples of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3 were prepared by the following method.

[0096] (Example 2-1) A mixture was obtained by weighing and mixing the metal composite hydroxide and anhydrous lithium hydroxide so that the molar ratio was Li / (Ni+Co+Al) = 1.035. The mixture was subjected to a first firing at 500°C for 1 hour in an oxygen atmosphere (oxygen concentration: 97 vol%).

[0097] Calcium hydroxide (Ca(OH)2) was weighed out and mixed with the calcined powder obtained by the first calcination so that the molar ratio was Ca / (Ni+Co+Al) = 0.005 to obtain a mixture, and the second calcination was carried out in an oxygen atmosphere (oxygen concentration: 97 vol%) at a maximum temperature of 750°C for 4.5 hours. The resulting calcined product was pulverized to obtain a lithium metal composite oxide calcined sample.

[0098] The obtained lithium metal composite oxide powder was mixed with pure water adjusted to a liquid temperature of 25°C so that the ratio was 1250 g / L to prepare a slurry, which was stirred for 10 minutes and then dehydrated to obtain a cake-like compound. The cake-like compound was dried in a vacuum dryer at 70°C for 2 hours and at 185°C for 10 hours to obtain a lithium metal composite oxide sample.

[0099] (Example 2-2) A lithium nickel composite oxide sample was obtained in the same manner as in Example 2-1, except that anhydrous strontium hydroxide (Sr(OH)2) was weighed and mixed with the fired powder after the first firing so as to obtain a mixture with a molar ratio of Sr / (Ni+Co+Al) = 0.005.

[0100] (Comparative Example 2-1) A lithium metal composite oxide sample was obtained in the same manner as in Example 2-1, except that magnesium hydroxide (Mg(OH)2) was weighed and mixed with the fired mixed powder after the first firing so that the molar ratio was Mg / (Ni+Co+Al) = 0.005 to obtain a mixture.

[0101] (Comparative Example 2-2) A lithium metal composite oxide sample was obtained in the same manner as in Example 2-1, except that sodium hydroxide (NaOH) was weighed and mixed with the pre-calcined calcined mixed powder so that the molar ratio was Na / (Ni+Co+Al) = 0.005 to obtain a mixture.

[0102] (Comparative Example 2-3) A lithium metal composite oxide sample was obtained in the same manner as in Example 2-1, except that potassium hydroxide (KOH) was weighed and mixed with the calcined mixed powder after the pre-calcination so that the molar ratio was K / (Ni+Co+Al) = 0.005 to obtain a mixture.

[0103] Table 1 shows the amounts of remaining lithium carbonate after firing and washing with water in Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3, and the reduction rates of the remaining lithium carbonate relative to Comparative Example 1-1.

[0104] [Table 1]

[0105] Table 2 shows the amounts of remaining lithium carbonate after firing and washing with water in Examples 2-1 to 2-2 and Comparative Examples 2-1 to 2-3, and the reduction rates of the remaining lithium carbonate relative to Comparative Example 1-1.

[0106] [Table 2]

Claims

1. A mixing step of mixing at least lithium hydroxide, a hydroxide containing a transition metal, and an additive compound that is a compound other than a carbonate of an additive metal other than the transition metal to prepare a mixture; a first firing step of firing the mixture at 500° C. or more and 650° C. or less to form a first fired product as a lithium metal composite oxide containing at least lithium and the transition metal; A second firing step of firing the first fired product at a temperature of more than 650 ° C.; The carbonate of the additive metal has a solubility lower than that of lithium carbonate and a melting point higher than the firing temperature of the second firing step. A method for producing a lithium metal composite oxide.

2. A first mixing step of mixing at least lithium hydroxide and a hydroxide containing a transition metal to prepare a first mixture; a first firing step of firing the first mixture at 500° C. or more and 650° C. or less to form a first fired product as a lithium metal composite oxide containing at least lithium and the transition metal; a second mixing step of mixing at least the first fired product with an additive compound that is a compound other than a carbonate of an additive metal other than a transition metal to prepare a second mixture; A second firing step of firing the second mixture at above 650°C; Including, The carbonate of the additive metal has a solubility lower than that of lithium carbonate and a melting point higher than the firing temperature of the second firing step. A method for producing a lithium metal composite oxide.

3. The additive compound is a hydroxide or an oxide. The method for producing the lithium metal composite oxide according to claim 1 or 2.

4. The transition metal includes nickel. The method for producing the lithium metal composite oxide according to claim 1 or 2.

5. The nickel content in the lithium metal composite oxide produced is 80 mol % or more based on elements other than lithium and oxygen. The method for producing the lithium metal composite oxide according to claim 1 or 2.

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