Lithium metal composite oxide powder, positive electrode active material for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery

Abstract

To provide: a lithium metal composite oxide having high powder fluidity and exhibiting high charge-discharge capacity when used as a positive electrode active material for a non-aqueous electrolyte secondary battery; a positive electrode active material employing the lithium metal composite oxide; and a non-aqueous electrolyte secondary battery employing the positive electrode active material.SOLUTION: A lithium metal composite oxide powder according to the present disclosure comprises a lithium metal composite oxide represented by the general formula: LiaNi1-x-y-zCoxMnyMzO2+α (where M represents an element other than Li, Ni, Co, Mn and O; and where 0.9≤a≤1.2, 0≤x≤0.4, 0≤y≤0.4, 0≤z≤0.1, and -0.5≤α≤0.5). The cumulative 50% particle diameter (D50) in volume-based particle size distribution is from 1 μm to 10 μm inclusive. The average circularity of secondary particles having particle diameters within the range of D50 (μm)±0.5 μm is 0.73 or more, and the coefficient of variation in circularity of the secondary particles having particle diameters within the range of D50 (μm)±0.5 μm is 0.09 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a lithium metal composite oxide powder, a positive electrode active material for a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery.

Background Art

[0002] Lithium-ion secondary batteries, which are used as driving power sources for electronic devices such as AV equipment and personal computers, have attracted attention because they are small, lightweight, have a high energy density, a high charge / discharge voltage, and a large charge / discharge capacity.

[0003] Among lithium-ion secondary batteries, lithium-ion secondary batteries using a layered or spinel-type lithium metal composite oxide as a positive electrode active material can obtain a voltage of about 4V, and thus, as a battery having a high energy density, research and development are currently being actively conducted, and in some cases, practical applications are also progressing.

[0004] As such positive electrode active materials for lithium-ion secondary batteries, lithium cobalt composite oxide (LiCoO2) that is relatively easy to synthesize, lithium nickel composite oxide (LiNiO2) using nickel that is cheaper than cobalt, lithium nickel cobalt manganese composite oxide (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2), lithium manganese composite oxide (LiMn2O4) using manganese, lithium nickel manganese composite oxide (LiNi 0.5 Mn 0.5 O2), and other lithium metal composite oxides have been proposed.

[0005] By the way, in order to further improve the output characteristics of a lithium-ion secondary battery, a method of increasing the specific surface area of the positive electrode active material is generally known. When the specific surface area of the positive electrode active material is increased, a sufficient reaction area with the electrolytic solution can be ensured when the positive electrode active material is incorporated into the secondary battery. Therefore, several techniques for improving the output characteristics by controlling the particle structure of the positive electrode active material have been proposed.

[0006] For example, Patent Document 1 proposes a method for manufacturing a positive electrode active material using a composite hydroxide obtained by a crystallization process carried out in two steps as a precursor. The positive electrode active material described in Patent Document 1 has a small particle size, a narrow particle size distribution, and a hollow structure or a space inside the particles, and thus has a high specific surface area and is excellent in charge-discharge capacity.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in the positive electrode active material of Patent Document 1, the primary particles aggregate irregularly to form amorphous secondary particles with unevenness and hollows on the surface. While such a shape is effective in ensuring a high specific surface area and improving output characteristics, fine powder may enter the concave portions of such secondary particles or cause a three-dimensional obstacle due to the convex portions, deteriorating the fluidity of the lithium metal composite oxide powder.

[0009] In the manufacturing process of the positive electrode active material for a non-aqueous secondary battery, such lithium metal composite oxide powder may be flowed and transported in a pipe. However, if the fluidity of the lithium metal composite oxide powder is poor, the inside of the pipe may be blocked, deteriorating the production efficiency or making it impossible to adjust the set supply amount and deteriorating the product characteristics.

[0010] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a lithium metal composite oxide having high powder fluidity and showing a high charge-discharge capacity when used as a positive electrode active material of a non-aqueous electrolyte secondary battery, a positive electrode active material using this lithium metal composite oxide, and a non-aqueous electrolyte secondary battery using this positive electrode active material.

Means for Solving the Problems

[0011] The inventors of the present invention have intensively studied to solve the above-described problems. As a result, a lithium metal composite oxide represented by the general formula Li 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, 0.9 ≦ a ≦ 1.2, 0 ≦ x ≦ 0.4, 0 ≦ y ≦ 0.4, 0 ≦ z ≦ 0.1, -0.5 ≦ α ≦ 0.5) is included, and the cumulative 50% particle diameter D50 in the volume-based particle size distribution is 1 μm or more and 10 μm or less, the average circularity of secondary particles having a particle diameter in the range of D50 (μm) ± 0.5 μm is 0.73 or more, and the coefficient of variation of the circularity of secondary particles having a particle diameter in the range of D50 (μm) ± 0.5 μm is 0.09 or less. It has been found that when used as a positive electrode active material of a non-aqueous secondary electrolyte, it exhibits a high charge-discharge capacity when used as a positive electrode active material of a non-aqueous electrolyte secondary battery. Specifically, the present disclosure provides the following.

[0012] (1) A lithium metal composite oxide represented by the general formula Li 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, 0.9 ≦ a ≦ 1.2, 0 ≦ x ≦ 0.4, 0 ≦ y ≦ 0.4, 0 ≦ z ≦ 0.1, -0.5 ≦ α ≦ 0.5) is included, the cumulative 50% particle diameter D50 in the volume-based particle size distribution is 1 μm or more and 10 μm or less, the average circularity of secondary particles having a particle diameter in the range of D50 (μm) ± 0.5 μm is 0.73 or more, the coefficient of variation of the circularity of secondary particles having a particle diameter in the range of D50 (μm) ± 0.5 μm is 0.09 or less lithium metal composite oxide powder.

[0013] (2) The BET specific surface area is 0.5 m 2 / g or more and 3 m 2The lithium metal composite oxide powder described in (1) below g or less.

[0014] (3) The lithium metal composite oxide powder described in (1) or (2) wherein the oil absorption amount of dibutyl phthalate per 100 g of the lithium metal composite oxide powder is 20 mL / 100 g or more and 60 mL / 100 g or less.

[0015] (4) A positive electrode active material for a non-aqueous electrolyte secondary battery containing the lithium metal composite oxide powder described in (1) or 2 Positive electrode active material for non-aqueous electrolyte secondary battery.

[0016] (5) A non-aqueous electrolyte secondary battery including a positive electrode containing the positive electrode active material for a non-aqueous electrolyte secondary battery described in (4).

Advantages of the Invention

[0017] According to the present disclosure, there can be provided a lithium metal composite oxide having high fluidity of powder and exhibiting a high charge-discharge capacity when used as a positive electrode active material of a non-aqueous electrolyte secondary battery, a positive electrode active material using this lithium metal composite oxide, and a non-aqueous electrolyte secondary battery using this positive electrode active material.

Embodiments for Carrying Out the Invention

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

[0019] ≪Lithium Metal Composite Oxide Powder≫ The lithium metal composite oxide powder according to an embodiment of the present disclosure has the general formula Li a Ni 1―x-y-z Co x Mn y M z O 2+α(In the formula, M is an element other than Li, Ni, Co, Mn, and O, 0.9 ≦ a ≦ 1.2, 0 ≦ x ≦ 0.4, 0 ≦ y ≦ 0.4, 0 ≦ z ≦ 0.1, -0.5 ≦ α ≦ 0.5), and it contains a lithium metal composite oxide represented thereby. And this lithium metal composite oxide powder has a cumulative 50% particle size D50 in the volume-based particle size distribution of 1 μm or more and 10 μm or less, and the average circularity of secondary particles having a particle size in the range of D50 (μm) ± 0.5 μm is 0.73 or more, and the coefficient of variation of the circularity of secondary particles having a particle size in the range of D50 (μm) ± 0.5 μm is 0.09 or less.

[0020] This lithium metal composite oxide powder has a cumulative 50% particle size D50 in the volume-based particle size distribution of 1 μm or more and 10 μm or less, and has a relatively small particle size. Further, since the average circularity of secondary particles having a particle size in the range of D50 (μm) ± 0.5 μm of the lithium metal composite oxide powder is 0.73 or more, and the coefficient of variation of the circularity of secondary particles having a particle size in the range of D50 (μm) ± 0.5 μm is 0.09 or less, the shape is close to spherical and there is little variation in the shape, so the fluidity of the powder is high. Also, since the packing property can be increased, when this is used as a positive electrode active material of a non-aqueous electrolyte secondary battery, it exhibits a high energy density.

[0021] The cumulative 50% particle size D50 in the volume-based particle size distribution is not particularly limited as long as it is 1 μm or more and 10 μm or less. For example, it is preferably 1.1 μm or more, 1.2 μm or more, 1.3 μm or more, 1.4 μm or more, 1.5 μm or more, 1.6 μm or more, 1.7 μm or more, 1.8 μm or more, 1.9 μm or more, 2 μm or more, 2.2 μm or more, 2.4 μm or more, 2.6 μm or more, 2.8 μm or more, 3 μm or more, 3.2 μm or more, 3.4 μm or more. On the other hand, the cumulative 50% particle size D50 in the volume-based particle size distribution is preferably 9.5 μm or less, 9 μm or less, 8.5 μm or less, 8 μm or less, 7.5 μm or less, 7 μm or less, 6.5 μm or less, 6 μm or less, 5.5 μm or less. Note that D50 is measured by the wet laser method using a laser-type particle size distribution measuring device (Microtrac HRA, manufactured by Nikkiso Co., Ltd.).

[0022] The BET specific surface area is not particularly limited, but for example, it is preferably 0.5 m 2 / g or more, 0.6 m 2 / g or more, 0.7 m 2 / g or more, 0.8 m 2 / g or more, 0.9 m 2 / g or more, 1 m 2 / g or more, 1.1 m 2 / g or more. The BET specific surface area is preferably 3 m 2 / g or less, 2.9 m 2 / g or less, 2.8 m 2 / g or less, 2.7 m 2 / g or less, 2.6 m 2 / g or less. The BET specific surface area is measured using a BET specific surface area measuring device (MONOSORB, manufactured by Yuasa Ionics Co., Ltd.) after drying and degassing the sample to be measured at 120 °C for 45 minutes under nitrogen gas.

[0023] The average circularity of secondary particles having a particle size in the range of D50 (μm) ± 0.5 μm is not particularly limited as long as it is 0.73 or more, but for example, it is preferably 0.74 or more, 0.75 or more, 0.76 or more, 0.77 or more. On the other hand, the average circularity of secondary particles having a particle size in the range of D50 (μm) ± 0.5 μm may be 1 or less, 0.99 or less, 0.98 or less.

[0024] The coefficient of variation of the circularity of secondary particles having a particle size in the range of D50 (μm) ± 0.5 μm is not particularly limited as long as it is 0.09 or less, but for example, it is preferably 0.085 or less, 0.08 or less, 0.075 or less, 0.07 or less. The coefficient of variation of the circularity of secondary particles having a particle size in the range of D50 (μm) ± 0.5 μm may be 0 or more, 0.0001 or more, 0.0002 or more, 0.0005 or more, 0.001 or more, 0.002 or more. The coefficient of variation of the circularity of secondary particles having a particle size in the range of D50 (μm) ± 0.5 μm is calculated by the method shown in the examples described later.

[0025] The oil absorption amount of dibutyl phthalate per 100 g of the lithium metal composite oxide powder is not particularly limited, but for example, it is preferably 20 mL / 100 g or more, 21 mL / 100 g or more, 22 mL / 100 g or more, 23 mL / 100 g or more, 24 mL / 100 g or more, 25 mL / 100 g or more. On the other hand, the oil absorption amount of dibutyl phthalate per 100 g of the lithium metal composite oxide powder is preferably 60 mL / 100 g or less, 55 mL / 100 g or less, 50 mL / 100 g or less, 45 mL / 100 g or less, 40 mL / 100 g or less. The oil absorption amount of dibutyl phthalate per 100 g of the lithium metal composite oxide powder is calculated by the method referring to JIS K5101-13-1 shown in the examples described later.

[0026] In the general formula of the lithium metal composite oxide, the value of a is not particularly limited as long as it is in the range of 0.90 ≦ a ≦ 1.2. For example, it is preferably 0.905 or more, 0.91 or more, 0.915 or more, 0.92 or more, 0.925 or more, 0.93 or more, 0.935 or more, 0.94 or more, 0.945 or more, 0.95 or more, 0.955 or more, 0.96 or more, 0.965 or more, 0.97 or more, 0.975 or more, 0.98 or more, 0.985 or more, 0.99 or more, 0.995 or more, 1 or more, 1.005 or more, 1.01 or more, 1.015 or more, 1.02 or more, 1.025 or more, 1.03 or more, 1.035 or more, 1.04 or more, 1.045 or more, 1.05 or more, 1.055 or more, 1.06 or more, 1.065 or more, 1.07 or more, 1.075 or more, 1.08 or more, 1.085 or more, 1.09 or more, 1.095 or more, 1.1 or more, 1.105 or more, 1.11 or more, 1.115 or more, 1.12 or more, 1.125 or more, 1.13 or more, 1.135 or more, 1.14 or more, 1.145 or more, 1.15 or more, 1.155 or more, 1.16 or more, 1.165 or more, 1.17 or more, 1.175 or more, 1.18 or more, 1.185 or more, 1.19 or more, 1.195 or more. On the other hand, the value of a is preferably 1.2 or less, 1.195 or less, 1.19 or less, 1.185 or less, 1.18 or less, 1.175 or less, 1.17 or less, 1.165 or less, 1.16 or less, 1.155 or less, 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.

[0027] In the general formula of the lithium metal composite oxide, the value of x is not particularly limited as long as it is within the range of 0 ≤ x ≤ 0.4. For example, greater 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.It is preferably 312 or more, 0.315 or more, 0.317 or more, 0.32 or more, 0.322 or more, 0.325 or more, 0.327 or more, 0.33 or more, 0.332 or more, 0.335 or more, 0.337 or more, 0.34 or more, 0.342 or more, 0.345 or more, 0.347 or more, 0.35 or more, 0.352 or more, 0.355 or more, 0.357 or more, 0.36 or more, 0.362 or more, 0.365 or more, 0.367 or more, 0.37 or more, 0.372 or more, 0.375 or more, 0.377 or more, 0.38 or more, 0.382 or more, 0.385 or more, 0.387 or more, 0.39 or more, 0.392 or more, 0.395 or more, 0.397 or more. On the other hand, as the value of x, it is 0.397 or less, 0.395 or less, 0.392 or less, 0.39 or less, 0.387 or less, 0.385 or less, 0.382 or less, 0.38 or less, 0.377 or less, 0.375 or less, 0.372 or less, 0.367 or less, 0.365 or less, 0.362 or less, 0.36 or less, 0.357 or less, 0.355 or less, 0.352 or less, 0.35 or less, 0.347 or less, 0.345 or less, 0.342 or less, 0.34 or less, 0.337 or less, 0.335 or less, 0.332 or less, 0.33 or less, 0.327 or less, 0.325 or less, 0.322 or less, 0.32 or less, 0.317 or less, 0.315 or less, 0.312 or less, 0.31 or less, 0.307 or less, 0.305 or less, 0.302 or less, 0.3 or less, 0.297 or less, 0.295 or less, 0.292 or less, 0.29 or less, 0.287 or less, 0.285 or less, 0.282 or less, 0.28 or less, 0.277 or less, 0.275 or less, 0.272 or less, 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, 0.175 or less, 0.172 or less, 0.17 or less, 0.167 or less, 0.It is preferably 165 or less, 0.162 or less, 0.16 or less, 0.155 or less, 0.152 or less, 0.15 or less, 0.147 or less, 0.145 or less, 0.142 or less, 0.14 or less, 0.137 or less, 0.135 or less, 0.132 or less, 0.13 or less, 0.127 or less, 0.125 or less, 0.122 or less, 0.12 or less, 0.117 or less, 0.115 or less, 0.112 or less, 0.11 or less, 0.107 or less, 0.105 or less, 0.102 or less, 0.1 or less, 0.095 or less, 0.09 or less, 0.085 or less, 0.08 or less, 0.075 or less, 0.07 or less, 0.065 or less, 0.06 or less, 0.055 or less, 0.05 or less, 0.045 or less, 0.04 or less, 0.035 or less, 0.03 or less, 0.025 or less, 0.02 or less, 0.015 or less, 0.01 or less, 0.0095 or less, 0.009 or less, 0.0085 or less, 0.008 or less, 0.0075 or less, 0.007 or less, 0.0065 or less, 0.006 or less, 0.0055 or less, 0.005 or less, 0.0045 or less, 0.004 or less, 0.0035 or less, 0.003 or less, 0.0025 or less, 0.002 or less, 0.0015 or less, 0.001 or less.

[0028] In the general formula of the lithium metal composite oxide, the value of y is not particularly limited as long as it is in the range of 0 ≦ y ≦ 0.4. For example, it can be 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.It is preferably 312 or more, 0.315 or more, 0.317 or more, 0.32 or more, 0.322 or more, 0.325 or more, 0.327 or more, 0.33 or more, 0.332 or more, 0.335 or more, 0.337 or more, 0.34 or more, 0.342 or more, 0.345 or more, 0.347 or more, 0.35 or more, 0.352 or more, 0.355 or more, 0.357 or more, 0.36 or more, 0.362 or more, 0.365 or more, 0.367 or more, 0.37 or more, 0.372 or more, 0.375 or more, 0.377 or more, 0.38 or more, 0.382 or more, 0.385 or more, 0.387 or more, 0.39 or more, 0.392 or more, 0.395 or more, 0.397 or more. On the other hand, as the value of y, it is 0.397 or less, 0.395 or less, 0.392 or less, 0.39 or less, 0.387 or less, 0.385 or less, 0.382 or less, 0.38 or less, 0.377 or less, 0.375 or less, 0.372 or less, 0.367 or less, 0.365 or less, 0.362 or less, 0.36 or less, 0.357 or less, 0.355 or less, 0.352 or less, 0.35 or less, 0.347 or less, 0.345 or less, 0.342 or less, 0.34 or less, 0.337 or less, 0.335 or less, 0.332 or less, 0.33 or less, 0.327 or less, 0.325 or less, 0.322 or less, 0.32 or less, 0.317 or less, 0.315 or less, 0.312 or less, 0.31 or less, 0.307 or less, 0.305 or less, 0.302 or less, 0.3 or less, 0.297 or less, 0.295 or less, 0.292 or less, 0.29 or less, 0.287 or less, 0.285 or less, 0.282 or less, 0.28 or less, 0.277 or less, 0.275 or less, 0.272 or less, 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, 0.175 or less, 0.172 or less, 0.17 or less, 0.167 or less, 0.It is preferably 165 or less, 0.162 or less, 0.16 or less, 0.155 or less, 0.152 or less, 0.15 or less, 0.147 or less, 0.145 or less, 0.142 or less, 0.14 or less, 0.137 or less, 0.135 or less, 0.132 or less, 0.13 or less, 0.127 or less, 0.125 or less, 0.122 or less, 0.12 or less, 0.117 or less, 0.115 or less, 0.112 or less, 0.11 or less, 0.107 or less, 0.105 or less, 0.102 or less, 0.1 or less, 0.095 or less, 0.09 or less, 0.085 or less, 0.08 or less, 0.075 or less, 0.07 or less, 0.065 or less, 0.06 or less, 0.055 or less, 0.05 or less, 0.045 or less, 0.04 or less, 0.035 or less, 0.03 or less, 0.025 or less, 0.02 or less, 0.015 or less, 0.01 or less, 0.0095 or less, 0.009 or less, 0.0085 or less, 0.008 or less, 0.0075 or less, 0.007 or less, 0.0065 or less, 0.006 or less, 0.0055 or less, 0.005 or less, 0.0045 or less, 0.004 or less, 0.0035 or less, 0.003 or less, 0.0025 or less, 0.002 or less, 0.0015 or less, 0.001 or less.

[0029] In the general formula of the lithium metal composite oxide, the value of z is not particularly limited as long as it is within the range of 0 ≦ z ≦ 0.1. For example, it is preferably 0.001 or more, 0.0012 or more, 0.0015 or more, 0.0017 or more, 0.002 or more, 0.0022 or more, 0.0025 or more, 0.0027 or more, 0.003 or more, 0.0032 or more, 0.0035 or more, 0.0037 or more, 0.004 or more, 0.0042 or more, 0.0045 or more, 0.0047 or more, 0.005 or more, 0.0052 or more, 0.0055 or more, 0.0057 or more, 0.006 or more, 0.0062 or more, 0.0065 or more, 0.0067 or more, 0.007 or more, 0.0072 or more, 0.0075 or more, 0.0077 or more, 0.008 or more, 0.0082 or more, 0.0085 or more, 0.0087 or more, 0.009 or more, 0.0092 or more, 0.0095 or more, 0.0097 or more, 0.01 or more, 0.012 or more, 0.015 or more, 0.017 or more, 0.02 or more, 0.022 or more, 0.025 or more, 0.027 or more, 0.03 or more, 0.032 or more, 0.035 or more, 0.037 or more, 0.04 or more, 0.042 or more, 0.045 or more, 0.047 or more, 0.05 or more, 0.052 or more, 0.055 or more, 0.057 or more, 0.06 or more, 0.062 or more, 0.065 or more, 0.067 or more, 0.07 or more, 0.072 or more, 0.075 or more, 0.077 or more, 0.08 or more, 0.082 or more, 0.085 or more, 0.087 or more, 0.09 or more, 0.092 or more, 0.095 or more, 0.097 or more.On the one hand, as the value of z, it is preferably 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 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, 0.0052 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.

[0030] In the general formula of the lithium metal composite oxide, the element M is not particularly limited as long as it is 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, B, etc. can be used. The type of element M may be selected according to the purpose of addition. Further, when the element M contains a plurality of elements, the value of w represents the total amount of the plurality of elements.

[0031] In the general formula of the lithium metal composite oxide, the value of α is not particularly limited as long as it is within the range of -0.5 ≤ α ≤ 0.5. For example, -0.5 or more, -0.45 or more, -0.4 or more, -0.35 or more, -0.30 or more, -0.25 or more, -0.2 or more, -0.15 or more, -0.1 or more, -0.075 or more, -0.05 or more, -0.025 or more, 0.001 or more, 0.0015 or more, 0.002 or more, 0.0025 or more, 0.003 or more, 0.0035 or more, 0.004 or more, 0.0045 or more, 0.005 or more, 0.0055 or more, 0.006 or more, 0.0065 or more, 0.007 or more, 0.0075 or more, 0.008 or more, 0.0085 or more, 0.009 or more, 0.0095 or more, 0.01 or more, 0.015 or more, 0.02 or more, 0.025 or more, 0.03 or more, 0.035 or more, 0.04 or more, 0.045 or more, 0.05 or more, 0.055 or more, 0.06 or more, 0.065 or more, 0.07 or more, 0.075 or more, 0.08 or more, 0.085 or more, 0.09 or more, 0.095 or more, 0.1 or more, 0.102 or more, 0.105 or more, 0.107 or more, 0.11 or more, 0.112 or more, 0.115 or more, 0.117 or more, 0.12 or more, 0.122 or more, 0.125 or more, 0.127 or more, 0.13 or more, 0.132 or more, 0.135 or more, 0.137 or more, 0.14 or more, 0.142 or more, 0.145 or more, 0.147 or more, 0.15 or more, 0.152 or more, 0.155 or more, 0.157 or more, 0.16 or more, 0.162 or more, 0.165 or more, 0.167 or more, 0.17 or more, 0.172 or more, 0.175 or more, 0.177 or more, 0.18 or more, 0.182 or more, 0.185 or more, 0.187 or more, 0.19 or more, 0.192 or more, 0.195 or more, 0.197 or more, 0.2 or more, 0.202 or more, 0.205 or more, 0.207 or more, 0.21 or more, 0.212 or more, 0.215 or more, 0.217 or more, 0.22 or more, 0.222 or more, 0.225 or more, 0.227 or more, 0.23 or more, 0.232 or more, 0.235 or more, 0.237 or more, 0.24 or more, 0.242 or more, 0.245 or more, 0.247 or more, 0.25 or more, 0.252 or more, 0.255 or more, 0.257 or more, 0.26 or more, 0.262 or more, 0.265 or more, 0.267 or more, 0.27 or more, 0.272 or more, 0.275 or more, 0.277 or more, 0.It is preferably 28 or more, 0.282 or more, 0.285 or more, 0.287 or more, 0.29 or more, 0.292 or more, 0.295 or more, 0.297 or more, 0.3 or more, 0.302 or more, 0.305 or more, 0.307 or more, 0.31 or more, 0.312 or more, 0.315 or more, 0.317 or more, 0.32 or more, 0.322 or more, 0.325 or more, 0.327 or more, 0.33 or more, 0.332 or more, 0.335 or more, 0.337 or more, 0.34 or more, 0.342 or more, 0.345 or more, 0.347 or more, 0.35 or more, 0.352 or more, 0.355 or more, 0.357 or more, 0.36 or more, 0.362 or more, 0.365 or more, 0.367 or more, 0.37 or more, 0.372 or more, 0.375 or more, 0.377 or more, 0.38 or more, 0.382 or more, 0.385 or more, 0.387 or more, 0.39 or more, 0.392 or more, 0.395 or more, 0.397 or more, 0.4 or more, 0.402 or more, 0.405 or more, 0.407 or more, 0.41 or more, 0.412 or more, 0.415 or more, 0.417 or more, 0.42 or more, 0.422 or more, 0.425 or more, 0.427 or more, 0.43 or more, 0.432 or more, 0.435 or more, 0.437 or more, 0.44 or more, 0.442 or more, 0.445 or more, 0.447 or more, 0.45 or more, 0.452 or more, 0.455 or more, 0.457 or more, 0.46 or more, 0.462 or more, 0.465 or more, 0.467 or more, 0.47 or more, 0.472 or more, 0.475 or more, 0.477 or more, 0.48 or more, 0.482 or more, 0.485 or more, 0.487 or more, 0.49 or more, 0.492 or more, 0.495 or more, 0.497 or more. On the other hand, as the value of α, it is 0.497 or less, 0.495 or less, 0.492 or less, 0.49 or less, 0.487 or less, 0.485 or less, 0.482 or less, 0.48 or less, 0.477 or less, 0.475 or less, 0.472 or less, 0.467 or less, 0.465 or less, 0.462 or less, 0.46 or less, 0.457 or less, 0.455 or less, 0.452 or less, 0.45 or less, 0.447 or less, 0.445 or less, 0.442 or less, 0.44 or less, 0.437 or less, 0.435 or less, 0.432 or less, 0.43 or less, 0.427 or less, 0.425 or less, 0.422 or less, 0.42 or less, 0.417 or less, 0.415 or less, 0.412 or less, 0.41 or less, 0.407 or less, 0.405 or less, 0.402 or less, 0.4 or less, 0.397 or less, 0.395 or less, 0.392 or less, 0.39 or less, 0.387 or less, 0.385 or less, 0.382 or less, 0.38 or less, 0.377 or less, 0.375 or less, 0.372 or less, 0.367 or less, 0.365 or less, 0.362 or less, 0.36 or less, 0.357 or less, 0.355 or less, 0.352 or less, 0.35 or less, 0.347 or less, 0.345 or less, 0.342 or less, 0.34 or less, 0.337 or less, 0.335 or less, 0.332 or less, 0.33 or less, 0.327 or less, 0.325 or less, 0.322 or less, 0.32 or less, 0.317 or less, 0.315 or less, 0.312 or less, 0.31 or less, 0.307 or less, 0.305 or less, 0.302 or less, 0.3 or less, 0.297 or less, 0.295 or less, 0.292 or less, 0.29 or less, 0.287 or less, 0.285 or less, 0.282 or less, 0.28 or less, 0.277 or less, 0.275 or less, 0.272 or less, 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, 0.175 or less, 0.172 or less, 0.17 or less, 0.167 or less, 0.165 or less, 0.162 or less, 0.16 or less, 0.155 or less, 0.152 or less, 0.15 or less, 0.147 or less, 0.145 or less, 0.142 or less, 0.14 or less, 0.137 or less, 0.135 or less, 0.132 or less, 0.13 or less, 0.127 or less, 0.125 or less, 0.122 or less, 0.12 or less, 0.117 or less, 0.115 or less, 0.112 or less, 0.11 or less, 0.107 or less, 0.105 or less, 0.102 or less, 0.1 or less, 0.095 or less, 0.09 or less, 0.085 or less, 0.08 or less, 0.075 or less, 0.07 or less, 0.065 or less, 0.06 or less, 0.055 or less, 0.05 or less, 0.045 or less, 0.04 or less, 0.It is preferably 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.

[0032] In addition, the lithium metal composite oxide powder has the general formula Li 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, 0.9 ≤ a ≤ 1.2, 0 ≤ x ≤ 0.4, 0 ≤ y ≤ 0.4, 0 ≤ z ≤ 0.1, -0.5 ≤ α ≤ 0.5), and one or more lithium metal composite oxides represented by the same formula may be contained. Also, compounds other than the lithium metal composite oxide represented by the same formula may be contained, for example, 0% or more (including the case where compounds other than metal composite hydroxides are not contained) on a mass basis, and may be contained at 10% or less, 5% or less, 2% or less, 1% or less.

[0033] The lithium metal composite oxide powder as described above can be preferably used as a positive electrode active material for a non-aqueous secondary electrolyte secondary battery. According to such a lithium metal composite oxide powder, the fluidity of the powder is high, and a non-aqueous electrolyte secondary battery using this as a positive electrode active material exhibits a high charge-discharge capacity.

[0034] <Manufacturing method of lithium metal composite oxide powder> The lithium metal composite oxide powder according to an embodiment of the present disclosure can be manufactured, for example, by performing the following steps in this order. Note that the lithium metal composite oxide powder according to the embodiment of the present disclosure cannot be manufactured in all categories of the manufacturing methods shown below. However, the lithium metal composite oxide powder according to the embodiment of the present disclosure can be manufactured by controlling each manufacturing condition from the category of the manufacturing methods shown below. Specific manufacturing conditions thereof are shown in the examples.

[0035] Precursor preparation step: Prepare a precursor composite compound containing at least a transition metal. Calcination step: Calcinate the precursor composite compound. Mixing step: Mix the precursor composite compound and a lithium compound to prepare a mixture. Firing step: Fire the mixture to obtain a lithium metal composite oxide powder. Water washing step: Perform a water washing treatment on the lithium metal composite oxide powder. Surface treatment step: Perform a surface treatment on the lithium metal composite oxide.

[0036] 〔Precursor preparation step〕 First, a precursor composite compound containing elements other than lithium and oxygen (hereinafter sometimes referred to as "constituent elements") among the elements constituting the lithium metal composite oxide powder is synthesized. The method for synthesizing the precursor composite compound is not particularly limited. For example, an aqueous solution of the constituent elements is dropped into a reaction tank in which an alkaline aqueous solution such as an aqueous sodium hydroxide solution or an ammonia solution is used as a mother liquor and stirred, and sodium hydroxide or the like is further dropped while monitoring and controlling so that the pH is within an appropriate range, and coprecipitated by a wet reaction to obtain a hydroxide, an oxide obtained by calcining the hydroxide, a carbonate, or the like.

[0037] In the reaction related to the synthesis, from the state where an alkaline aqueous solution serving as the mother liquor is prepared, it is preferable to make the inside of the reaction tank into a nitrogen atmosphere with an inert gas or preferably nitrogen gas industrially, and to make the oxygen concentration in the reaction tank system and the solution as low as possible. When the oxygen concentration is too high, there is a risk that the hydroxide coprecipitated by the remaining oxygen in a predetermined amount or more is oxidized too much, or there is a risk that the formation of aggregates by crystallization is hindered. However, by mixing 1 to 30 vol% of an oxidizing gas with the inert gas or nitrogen gas and introducing it during the crystallization reaction, it is also possible to locally promote the oxidation of the coprecipitate and control the aggregation form.

[0038] The aqueous solution of the constituent elements is not particularly limited, but for example, it is preferable to use an acidic aqueous solution, and it is more preferable to use an aqueous solution of a sulfate. Further, as the aqueous solution of the transition metal, one kind or two or more kinds can be used. Hereinafter, the elements that can be used as the constituent elements and their compounds will be described respectively, but the constituent elements and their compounds are not limited to those shown below.

[0039] The nickel compound is not particularly limited, and for example, one kind or two or more kinds selected from nickel sulfate, nickel oxide, nickel hydroxide, nickel nitrate, nickel carbonate, nickel chloride, nickel iodide, and metallic nickel can be used.

[0040] The cobalt compound is not particularly limited, and for example, one kind or two or more kinds selected from cobalt sulfate, cobalt oxide, cobalt hydroxide, cobalt nitrate, cobalt carbonate, cobalt chloride, cobalt iodide, and metallic cobalt can be used.

[0041] The manganese compound is not particularly limited, and for example, one kind or two or more kinds selected from manganese sulfate, manganese oxide, manganese hydroxide, manganese nitrate, manganese carbonate, manganese chloride, manganese iodide, and metallic manganese can be used.

[0042] The aluminum compound is not particularly limited, and for example, one or more selected from aluminum sulfate, aluminum oxide, aluminum hydroxide, aluminum nitrate, aluminum carbonate, aluminum chloride, aluminum iodide, sodium aluminate, and metallic aluminum can be used.

[0043] The titanium compound is not particularly limited, and for example, one or more selected from titanyl sulfate, titanium oxide, titanium hydroxide, titanium nitrate, titanium carbonate, titanium chloride, titanium iodide, and metallic titanium can be used.

[0044] The iron compound is not particularly limited, and for example, one or more selected from iron sulfate, iron oxide, iron hydroxide, iron nitrate, iron carbonate, iron chloride, iron iodide, and metallic iron can be used.

[0045] The niobium compound is not particularly limited, and for example, one or more selected from niobium oxide, niobium chloride, lithium niobate, and niobium iodide can be used.

[0046] The tungsten compound is not particularly limited, and for example, one or more selected from tungsten oxide, sodium tungstate, ammonium paratungstate, tungsten hexacarbonyl, and tungsten sulfide can be used.

[0047] The magnesium compound is not particularly limited, and for example, one or more selected from magnesium sulfate, magnesium oxide, magnesium hydroxide, magnesium nitrate, magnesium carbonate, magnesium chloride, magnesium iodide, and metallic magnesium can be used.

[0048] The zinc compound is not particularly limited, and for example, one or more selected from zinc sulfate, zinc oxide, zinc hydroxide, zinc nitrate, zinc carbonate, zinc chloride, zinc iodide, and metallic zinc can be used.

[0049] For other elements, one or more selected from sulfates, oxides, hydroxides, nitrates, carbonates, chlorides, iodides, metals, etc. can be used.

[0050] As the blending ratio of each compound, it may be adjusted so that the amount of each element becomes a desired ratio in consideration of the composition of the lithium metal composite oxide to be produced.

[0051] The appropriate pH range when synthesizing the precursor composite compound is not particularly limited and can be determined so as to obtain a desired shape such as a secondary particle diameter and a density. Generally, it may be 10 to 13.

[0052] The precursor composite compound obtained by the wet reaction is preferably subjected to a washing treatment and then a drying treatment after dehydration.

[0053] By subjecting the precursor composite compound to a washing treatment, impurities such as sulfate radicals, carbonate radicals, and sodium content that are incorporated into the aggregated particles or adhered to the surface layer during the reaction can be washed away. For the washing treatment, a method of performing Nutsche washing using a Buchner funnel if the amount is small, or a method of feeding the suspension after the reaction to a press filter, washing with water, and dehydrating can be used. In the washing treatment, for example, pure water, an aqueous sodium hydroxide solution, an aqueous sodium carbonate solution, etc. can be used, but industrially, it is preferable to use pure water. However, when there is a large amount of residual sulfate radicals, an aqueous sodium hydroxide solution with the pH controlled according to the residual amount may be used.

[0054] 〔Calcination step〕 The precursor composite compound obtained in the precursor preparation step may be calcined. Thus, by calcining the precursor composite compound before mixing it with the lithium compound, the metal composite hydroxide in the precursor composite compound can be decarbonated and dehydrated. Note that this step is not an essential step.

[0055] The calcination conditions are not particularly limited, but for example, it is preferably carried out under an oxidizing atmosphere at a heating temperature of 200 to 700 °C for a heating time of 1 to 6 hours. The heating temperature is the temperature of the part having the highest temperature in the precursor composite compound, and the heating time is the time during which the temperature of the part having the highest temperature maintains the above temperature range. By performing calcination, it is possible to appropriately remove impurities remaining in the precursor composite compound, and a calcined product can be obtained. The heating temperature is the temperature of the part having the highest temperature when the object to be heated is heated and rises, and the heating time is the time during which the temperature of the part having the highest temperature in the object to be heated maintains the above temperature range (the same applies in the following steps).

[0056] 〔Mixing step〕 Next, the precursor composite compound obtained in the precursor preparation step or the calcination step and the lithium compound are mixed at a predetermined ratio to prepare a mixture. The mixing may be a solvent-based mixing in which the precursor composite compound and the lithium compound are each made into a solution such as an aqueous solution and these solutions are mixed at a predetermined ratio, or a non-solvent-based mixing in which the powder of the precursor composite compound and the powder of the lithium compound are weighed so as to have a predetermined ratio and these are mixed dryly.

[0057] The lithium compound is not particularly limited, and various lithium salts can be used. Specifically, as the lithium compound, for example, one or more selected from anhydrous lithium hydroxide, lithium hydroxide hydrate, lithium nitrate, lithium carbonate, lithium acetate, lithium bromide, lithium chloride, lithium citrate, lithium fluoride, lithium iodide, lithium lactate, lithium oxalate, lithium phosphate, lithium pyruvate, lithium sulfate, and lithium oxide can be used. Among these, it is preferable to use one or more selected from lithium carbonate, anhydrous lithium hydroxide, and lithium hydroxide hydrate.

[0058] The mixing ratio of the lithium compound and the precursor composite compound is not particularly limited, but it may be appropriately adjusted so that the amount of lithium and the total amount of the amounts of the respective elements are in a desired ratio in consideration of the composition of the target composite oxide.

[0059] 〔Firing Process〕 As described above, when producing a lithium metal composite oxide containing at least a transition metal, a lithiation reaction and crystal growth occur during firing. Among these, the lithiation reaction requires a certain oxygen partial pressure. By the lithiation reaction, a lithium metal composite oxide is obtained. Thereafter, by raising the temperature to a predetermined temperature, crystal growth is promoted.

[0060] The firing temperature of the mixture in firing is preferably 650 to 1100 °C, 670 to 1000 °C, or 700 to 980 °C. Also, the firing time at the maximum temperature is preferably 1 to 24 hours, 1 to 20 hours, 1 to 15 hours, 1 to 10 hours, 2 to 9 hours, or 3 to 8 hours. By setting the firing temperature above the melting point of the lithium compound in the mixture and the firing temperature and time at which the composite oxide containing lithium achieves desired crystal growth and particle growth, a desired lithium metal composite compound can be obtained.

[0061] Firing is generally carried out by weighing a lithium compound, a precursor composite compound, and, if necessary, a compound of element M, mixing the resulting mixed powder in a mixer, and filling it into a container such as a crucible or a sagger. However, particularly in the lithiation reaction, as the vicinity of the lower part of the container filled with the mixed powder is approached, it becomes difficult to discharge the generated gas to the outside and to diffuse the necessary oxygen concentration. As a result, it becomes difficult to control the uniformity of the reaction and the primary particle size.

[0062] Therefore, when producing the composite oxide according to the embodiment of the present disclosure, it is preferable to use a method in which first pre-firing is performed under the following predetermined conditions and then main firing is performed under the predetermined conditions. However, pre-firing is not an essential step.

[0063] In the preliminary firing, it is preferable to adopt a firing method that particularly promotes the lithiation reaction. Specifically, a method can be mentioned in which the mixture is made to be more easily heated, the gas generated from the lithium compound is easily discharged, and a gas with a high oxygen partial pressure is diffused into the mixture (inside the particles). For example, the lithiation reaction can be promoted by reducing the amount of the mixture and performing preliminary firing, or by performing preliminary firing while flowing the mixture.

[0064] For the preliminary firing of the mixture, the mixture can be filled in a crucible or a pot and fired in a stationary furnace, a roller hearth kiln, or a pusher furnace, but a rotary kiln that fires while flowing the mixture can be used.

[0065] The firing temperature of the mixture to be preliminarily fired is not particularly limited, and it is preferably adjusted according to the type of lithium compound used in the preparation of the mixture. Thereby, the precursor composite compound and the lithium compound in the mixture can be reacted to advance the lithiation reaction and obtain a lithium metal composite oxide. Note that the "firing temperature" refers to the highest temperature that the mixture reaches when heated.

[0066] The atmosphere for the preliminary firing is not particularly limited, and an oxidizing atmosphere in which the lithiation reaction proceeds may be used. For example, it is preferable to use air (oxygen concentration: 21 vol%), 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.

[0067] The time for the preliminary firing is not particularly limited, and any time can be used as long as the lithiation reaction proceeds. For example, it is preferably 1 to 10 hours, 2 to 8 hours.

[0068] In order to further grow the crystals and particles of the preliminarily fired mixture at a higher temperature, the main firing is performed. At that time, it is necessary to advance the crystal growth to obtain a composite oxide having a desired crystal structure.

[0069] The atmosphere for this firing is not particularly limited, as long as it has an oxygen partial pressure that allows crystal growth to proceed and does not reduce the transition metals contained in the mixture to be fired. Preferably, it is an atmosphere with a low moisture content and a low carbon dioxide concentration. For example, a decarburized oxidizing gas atmosphere with a carbon dioxide concentration of 30 ppm or less, or preferably an oxygen atmosphere with an oxygen concentration of 80 vol% or more, 90 vol% or more, can be used.

[0070] The temperature for this firing is not particularly limited as long as it is higher than the temperature of the preliminary firing, and can be adjusted according to the composition of the composite oxide to be obtained. For example, it is preferable to adjust the firing temperature to be 700 - 1100 °C, 710 - 1000 °C, 720 - 980 °C. By having the firing temperature within the required range, a lithium metal composite oxide with reduced unreacted components can be obtained. Also, it is possible to prevent a decrease in the battery characteristics of a non-aqueous electrolyte secondary battery using the lithium metal composite oxide obtained by this method as the positive electrode. Further, for example, when obtaining a lithium metal composite oxide with a Ni content of 20 - 80 mol% among the elements other than Li, it is preferable to fire at a temperature where the maximum temperature of the mixture does not exceed 1100 °C.

[0071] The time for this firing is not particularly limited, as long as it is sufficient time for a composite oxide with a desired crystal structure to be formed. For example, it is preferably 1 - 15 hours, 2 - 12 hours, 2 - 10 hours.

[0072] 〔Water washing process〕 The lithium metal composite oxide obtained in the firing process may contain, as impurities, unreacted lithium compounds and lithium compounds that appear from the crystal structure to the particle surface layer during the firing process. Therefore, in order to remove and reduce these impurities, for example, it can be washed with water and heat-treated. Note that the water washing process is not an essential component.

[0073] 〔Surface treatment process〕 By adding and mixing a predetermined element compound to the composite oxide obtained in the firing process or the water washing process and performing heat treatment, it is possible to perform surface treatment on the surface of the primary particles and / or secondary particles of the composite oxide with a compound of lithium and the added element, and effects such as reduction of lithium compounds remaining in the particle surface layer, improvement of lithium ion conductivity, and reduction of reaction resistance can be obtained. Note that the surface treatment step is not an essential configuration.

[0074] The element compound added for the above-described surface treatment can be selected from, for example, 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 thereof can be used.

[0075] The use of the lithium metal composite oxide powder of this embodiment is not particularly limited, but for example, it can be used as a positive electrode active material for a non-aqueous electrolyte secondary battery containing this lithium metal composite oxide powder.

[0076] <Non-aqueous electrolyte secondary battery> The non-aqueous electrolyte secondary battery according to the embodiment of the present disclosure includes a positive electrode including a positive electrode active material for a non-aqueous electrolyte secondary battery containing the above-described lithium metal composite oxide powder. More specifically, the non-aqueous electrolyte secondary battery is composed of a positive electrode, a negative electrode, and an electrolytic solution containing an electrolyte.

[0077] When manufacturing the positive electrode, according to a conventional method, a conductive agent and a binder are added to and mixed with the lithium metal composite oxide according to the embodiment of the present disclosure. 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.

[0078] The negative electrode is not particularly limited. For example, not only negative electrode active materials such as lithium metal, graphite, and low-crystalline carbon materials, but also one or more non-metallic or metallic elements selected from Si, Al, Sn, Pb, Zn, Bi, and Cd, alloys containing the same, or chalcogen compounds containing the same can be used.

[0079] The solvent of the electrolytic solution is not particularly limited. 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 can be used.

[0080] As the electrolyte, in addition to lithium hexafluorophosphate (LiPF6), for example, one or more selected from lithium salts such as lithium perchlorate and lithium tetrafluoroborate can be dissolved in a solvent and used.

Examples

[0081] Hereinafter, the present disclosure will be described in more detail using examples, but the present disclosure is not limited by these examples.

[0082] <Evaluation Method> The samples obtained in the examples were evaluated by the methods shown below.

[0083] 〔Composition Analysis of Precursor Composite Compound Sample and Lithium Metal Composite Oxide Powder Sample〕 The compositions of the precursor composite compound sample and the lithium metal composite oxide powder sample were determined by the following method. 0.2 g of the precursor composite compound sample and the lithium metal composite oxide powder sample were heated and dissolved in 25 ml of a 20% hydrochloric acid solution, and after cooling, transferred to a 100 ml volumetric flask and adjusted with pure water to prepare an adjusted solution. For the obtained adjusted solution, elemental quantification was performed using ICP-AES (Optima8300, manufactured by PerkinElmer Japan Co., Ltd.).

[0084] 〔Average Particle Size (D50) of Lithium Metal Composite Oxide Powder Sample〕 The average particle size (D50) of the lithium metal composite oxide powder sample was measured on a volume basis by the wet laser method using a laser particle size distribution analyzer (Microtrac HRA, manufactured by Nikkiso Co., Ltd.).

[0085] 〔Specific surface area of the positive electrode active material〕 The BET specific surface area was measured using a BET specific surface area analyzer (MONOSORB, manufactured by Yuasa Ionics Co., Ltd.) after drying and degassing the sample under nitrogen gas at 120 °C for 45 minutes.

[0086] 〔Oil absorption of the lithium metal composite oxide powder sample〕 The oil absorption of the lithium metal composite oxide powder sample was measured with reference to JIS K5101-13-1:2004. Specifically, for the oil absorption of the lithium metal composite oxide powder sample, using an oil absorption measuring device (S500, manufactured by Asahi R & D Co., Ltd.), while stirring 45 g of the lithium metal composite oxide powder sample at 100 rpm, dibutyl phthalate (hereinafter sometimes referred to as DBP) was dropped at 2.0 ml / min, and the torque of the stirring part was measured. At this time, the change in torque with respect to the dropping amount of DBP had a peak, and the value obtained by dividing the dropping amount of DBP at the peak top (when the torque was maximum) by the mass of the lithium metal composite oxide powder sample was defined as the oil absorption (ml / 100 g) of the lithium metal composite oxide powder sample.

[0087] 〔Average circularity and coefficient of variation〕 The average circularity and coefficient of variation of the lithium metal composite oxide powder sample were measured as follows. Using a field emission scanning electron microscope (JSM-7100F, manufactured by JEOL Ltd.), with an acceleration voltage of 10 kV, scanning electron microscope photographs were taken of the secondary electron image of the lithium metal composite oxide powder material. For the scanning electron microscope photography, the magnification was adjusted to 500 - 3000 times so that the number of secondary particles per field of view was 100 or more, and scanning electron microscope photographs of multiple fields of view of 2 or more fields were obtained so that the total number of secondary particles was 400 - 4000.

[0088] For the scanning electron micrographs of multiple fields of view of two or more fields of view obtained, binarization processing was performed using image processing software (ImageJ). For the processed images, segmentation was performed by Watershed (ImageJ plugin) in ImageJ to clarify the contours of the secondary particles in the binarized images. Then, by using Analyze in ImageJ, the circularity (formula: 4×pi×secondary particle area / (secondary particle perimeter length) 2 is calculated. If it is a perfect circle, it becomes 1.) and the equivalent circle diameter of each secondary particle (for the area of each secondary particle, (4×secondary particle area / pi) 1 / 2 is calculated. It corresponds to the diameter when the area of the secondary particle is a perfect circle.) were calculated.

[0089] After that, a graph was created with the equivalent circle diameter of the secondary particles on the horizontal axis and the circularity based on the number on the vertical axis. For the secondary particles having a particle diameter in the range of (D50 (μm) - 0.5 μm) or more and (D50 (μm) + 0.5 μm) or less with respect to the average particle diameter D50 (μm) obtained by laser particle size distribution measurement, the average circularity and standard deviation corresponding to the equivalent diameter were obtained. The coefficient of variation was calculated by (standard deviation / average circularity).

[0090] 〔Evaluation of the fluidity of the lithium metal composite oxide powder sample〕 When performing sieving treatment with an ultrasonic vibrating sieve having a diameter of 500 mm and a mesh opening of 38 μm, the ratio of the mass of 1 kg of the lithium metal composite oxide powder sample passing through the sieve in a treatment time of 3 minutes was calculated, and the ratio was judged according to the following criteria. A: 40% or more B: 35% or more and less than 40% C: Less than 35%

[0091] 〔Evaluation of output characteristics using a coin cell with a positive electrode active material sample〕 The 2032-type coin cells using the positive electrode active material particles obtained by lithiating the precursor composite compound in this specification were manufactured using the positive electrode, negative electrode, and electrolyte prepared by the following methods, respectively.

[0092] (Positive electrode) Acetylene black and graphite were used as conductive agents at a weight ratio of acetylene black:graphite = 1:1. Polyvinylidene fluoride was used as a binder. The positive electrode active material, conductive agent, and binder were blended so that the ratio of positive electrode active material:conductive agent:binder was 90:5:5 (weight ratio). A mixture of these in N-methylpyrrolidone was applied to an aluminum foil. This was dried at 110 °C to produce a sheet, which was punched out to 15 mm Φ and then rolled at 2.8 t / cm 2 to obtain the positive electrode.

[0093] (Negative electrode) A lithium foil with a thickness of 500 μm punched out to 16 mm Φ was used as the negative electrode.

[0094] (Electrolyte) A mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) was prepared so that the volume ratio of EC:DMC was 1:2. A solution obtained by mixing 1 mol / L of LiPF6 in the electrolyte was used as the electrolyte.

[0095] (Separator) A separator (Celgard#2400, manufactured by Celgard) with a thickness of 0.5 mm punched out to 20 mm Φ was used.

[0096] Using the coin cell manufactured by the method described above, under an environment of 25 °C, after constant current charging at a current density of 0.1C up to 4.3V (upper limit voltage), constant voltage charging was performed until the current became 0.01C. Then, after a 5-minute pause, under the same environment, constant current discharging was performed at a current density of 0.1C up to 3.0V, and a 5-minute pause was made. This operation was repeated twice, and again, charging was performed up to 4.3V under the same conditions.

[0097] Thereafter, after 1 hour in an environment of -10°C, based on the discharge capacity in the discharge after the second charge, constant current discharge was performed at a current density of 0.1C so as to obtain a voltage corresponding to SOC 20%. Thereafter, after a 5-minute pause, discharge was performed at a current value corresponding to SOC 10%, and the DC resistance (DCR) was measured by measuring the voltage difference at that time. Evaluation was performed according to the following criteria based on the value of the DC resistance. A: Less than 60 Ω B: 60 Ω or more and less than 80 Ω C: 80 Ω or more

[0098] <Sample Preparation> 〔Example 1〕 An aqueous nickel sulfate solution, cobalt sulfate, and an aqueous manganese sulfate solution were mixed so that the ratio (molar ratio) of Ni, Co, and Mn was Ni:Co:Mn = 34:33:33 to obtain a mixed aqueous solution. In the reaction tank, 10 L of pure water to which 20 g of 6N sodium hydroxide aqueous solution and 120 g of 25 wt% aqueous ammonia had been added in advance was prepared as a mother liquor, and during the reaction, a mixed gas in which air:nitrogen was adjusted to a volume ratio of 2:8 was continuously introduced into the reaction tank at a flow rate of 0.7 mL / min.

[0099] Thereafter, while rotating the stirring blade at 900 rpm, the temperature of the reaction solution was maintained at 40°C, and the above-mentioned mixed aqueous solution and a mixed alkali solution of sodium hydroxide aqueous solution and aqueous ammonia were simultaneously dropped using metering pumps, respectively. Specifically, the dropping amount of the mixed alkali solution was adjusted so that the pH became 11.5, and a crystallization reaction was performed. During the crystallization reaction, the slurry solution in the reaction tank was filtered by a filtration device in a pipe installed from the lower part of the reaction tank to the outside, and then circulated and filtered back to the upper part of the reaction tank. Sampling was performed as appropriate, and the raw materials were dropped and the reaction was continued until the average particle size reached 3.6 μm. Thereafter, the dropping of the raw materials was terminated, and the reaction slurry was recovered.

[0100] After recovering the reaction slurry, solid-liquid separation was performed, washing was performed using a 6N sodium hydroxide solution, and further washing with pure water was performed to reduce residual impurities. Then, the coprecipitate in a cake state was dried at 90°C for 12 hours in an air environment to obtain a precursor composite compound sample.

[0101] The obtained composite hydroxide sample and lithium carbonate were weighed and mixed so that the finally obtained lithium metal composite oxide sample had a Li / (Ni + Co + Mn) ratio of 1.13. Thereafter, the mixture was calcined at 940 °C for 4 hours in an air atmosphere (oxygen concentration: 21 vol%), and the obtained calcined product was pulverized to obtain a lithium metal composite oxide sample. When the fluidity was confirmed by sieving, 45% passed through.

[0102] [Example 2] An aqueous solution of nickel sulfate, cobalt sulfate, and an aqueous solution of manganese sulfate were mixed so that the ratio (molar ratio) of Ni, Co, and Mn was Ni:Co:Mn = 34:33:33 to obtain a mixed aqueous solution. In the reaction tank, 10 L of pure water to which 20 g of 6N sodium hydroxide aqueous solution and 120 g of 25 mass% aqueous ammonia had been previously added was prepared as a mother liquor, and nitrogen gas was continuously introduced into the reaction tank at a flow rate of 0.7 mL / min during the reaction.

[0103] Thereafter, while rotating the stirring blade at 900 rpm, the temperature of the reaction solution was maintained at 40 °C, and the above-mentioned mixed aqueous solution, sodium hydroxide aqueous solution, and aqueous ammonia were simultaneously dropped using metering pumps, respectively, and the dropping amount of the alkaline solution was adjusted so that the pH became 11.5 to perform a crystallization reaction. During the crystallization reaction, the slurry solution in the reaction tank was filtered through a filtration device in a pipe installed from the lower part of the reaction tank to the outside, and then circulated and filtered back to the upper part of the reaction tank. Sampling was performed as appropriate, and the raw materials were dropped until the average particle size reached 3.5 μm, and the reaction was continued. Thereafter, the dropping of the raw materials was terminated, and the reaction slurry was recovered.

[0104] After the reaction slurry was recovered, solid-liquid separation was performed, washing was carried out using a 6N sodium hydroxide solution, and further washing with pure water was performed to reduce residual impurities. Then, the co-precipitate in a cake state was dried at 90 °C for 12 hours in an air environment to obtain a precursor composite compound sample.

[0105] The obtained precursor composite hydroxide sample and lithium carbonate were weighed and mixed so that the resulting lithium metal composite oxide sample had a Li / (Ni+Co+Mn) ratio of 1.13. Then, it was fired at 940 °C for 4 hours in an air atmosphere (oxygen concentration: 21 vol%), and the obtained fired product was pulverized to obtain a lithium metal composite oxide sample. When the fluidity was confirmed by sieving, 53% passed through.

[0106] Example 3 An aqueous nickel sulfate solution, cobalt sulfate, and an aqueous manganese sulfate solution were mixed so that the ratio (molar ratio) of Ni, Co, and Mn was Ni:Co:Mn = 34:33:33 to obtain a mixed aqueous solution. In the reaction tank, 10 L of pure water to which 20 g of a 6N sodium hydroxide aqueous solution and 120 g of 25 mass% aqueous ammonia had been previously added was prepared as the mother liquor, and during the reaction, nitrogen gas was continuously introduced into the reaction tank at a flow rate of 0.7 mL / min.

[0107] Thereafter, while rotating the stirring blade at 700 rpm, the temperature of the reaction solution was maintained at 40 °C, and the mixed aqueous solution, the sodium hydroxide aqueous solution, and the aqueous ammonia were simultaneously dropped using metering pumps, respectively, and the dropping amount of the alkaline solution was adjusted so that the pH became 11.3 to perform a crystallization reaction. During the crystallization reaction, the slurry solution in the reaction tank was filtered by a filtration device in a pipe installed from the lower part to the outside of the reaction tank and then refluxed to the upper part of the reaction tank for circulation filtration. Sampling was performed as appropriate, and the raw materials were dropped and the reaction was continued until the average particle size reached 4.2 μm. Thereafter, the dropping of the raw materials was terminated and the reaction slurry was recovered.

[0108] After recovering the reaction slurry, solid-liquid separation was performed, washing was carried out using a 6N sodium hydroxide solution, and further washing with pure water was performed to reduce residual impurities. Then, the coprecipitate in the cake state was dried at 90 °C for 12 hours in an air environment to obtain a precursor composite compound sample.

[0109] The obtained composite hydroxide sample and lithium carbonate were weighed and mixed so that the resulting lithium metal composite oxide sample had a Li / (Ni + Co + Mn) ratio of 1.14. Then, it was fired at 940 °C for 4 hours in an air atmosphere (oxygen concentration: 21 vol%), and the obtained fired product was pulverized to obtain a lithium metal composite oxide sample. When the fluidity was confirmed by sieving, 48% passed through.

[0110] [Comparative Example 1] An aqueous nickel sulfate solution, cobalt sulfate, and an aqueous manganese sulfate solution were mixed so that the ratio (molar ratio) of Ni, Co, and Mn was Ni:Co:Mn = 34:33:33 to obtain a mixed aqueous solution. In the reaction tank, 3 L of pure water to which 6 g of 6N sodium hydroxide aqueous solution and 40 g of 25 mass% aqueous ammonia had been added in advance was prepared as the mother liquor, and during the reaction, it was continuously introduced into the reaction tank at a flow rate of 0.7 mL / min of nitrogen gas.

[0111] Thereafter, while rotating the stirring blade at 900 rpm, the temperature of the reaction solution was maintained at 40 °C, and the above-mentioned mixed aqueous solution, sodium hydroxide aqueous solution, and aqueous ammonia were simultaneously dropped using metering pumps, and the dropping amount of the alkaline solution was adjusted so that the pH became 11.4 to carry out a crystallization reaction. During the crystallization reaction, sampling was appropriately performed, and the raw materials were dropped until the average particle size reached 3 μm, and the reaction was continued. Thereafter, the dropping of the raw materials was terminated, and the reaction slurry was recovered.

[0112] After the reaction slurry was recovered, solid-liquid separation was performed, washing was carried out using a 6N sodium hydroxide solution, and further washing with pure water was performed to reduce residual impurities. Then, the coprecipitate in the cake state was dried at 90 °C for 12 hours in an air environment to obtain a precursor composite compound sample.

[0113] The obtained composite hydroxide sample and lithium carbonate were weighed and mixed so that the resulting lithium metal composite oxide sample had a Li / (Ni + Co + Mn) ratio of 1.13. Then, it was fired at 940 °C for 4 hours in an air atmosphere (oxygen concentration: 21 vol%), and the obtained fired product was pulverized to obtain a lithium metal composite oxide sample. When the fluidity was confirmed by sieving, 28% passed through.

[0114] [Comparative Example 2] An aqueous nickel sulfate solution, cobalt sulfate, and an aqueous manganese sulfate solution were mixed so that the ratio (molar ratio) of Ni, Co, and Mn was Ni:Co:Mn = 34:33:33 to obtain a mixed aqueous solution. In the reaction tank, 10 L of pure water to which 100 g of an aqueous sodium hydroxide solution and 500 g of 25 mass% aqueous ammonia had been added in advance was prepared as a mother liquor, and during the reaction, a mixed gas in which air:nitrogen was adjusted to a volume ratio of 2:8 was continuously introduced into the reaction tank at a flow rate of 0.7 mL / min.

[0115] Thereafter, while rotating the stirring blade at 1000 rpm, the above-mentioned mixed aqueous solution, the aqueous sodium hydroxide solution, and aqueous ammonia were simultaneously dropped using a metering pump, and the dropping amount of the alkaline solution was adjusted so that the pH became 11.5 to conduct a crystallization reaction. During the crystallization reaction, the reaction slurry was appropriately sampled from the overflow pipe installed at the upper part of the reaction tank. After confirming that the particle diameter of the reaction slurry was stable at 3.5 μm, the slurry was recovered.

[0116] After recovering the reaction slurry, solid-liquid separation was performed, washing was carried out using a 6N sodium hydroxide solution, and further washing with pure water was performed to reduce residual impurities. Then, the co-precipitate in a cake state was dried at 90 °C for 12 hours in an air environment to obtain a precursor composite compound sample.

[0117] The obtained composite hydroxide sample and lithium carbonate were weighed and mixed so that the resulting lithium metal composite oxide sample had a Li / (Ni + Co + Mn) ratio of 1.14. Then, under an air atmosphere (oxygen concentration: 21 vol%), it was fired at a maximum temperature of 940 °C for 4 hours, and the obtained fired product was pulverized to obtain a lithium metal composite oxide sample. When the fluidity was confirmed by sieving, 21% passed through.

[0118] [Comparative Example 3] An aqueous nickel sulfate solution, cobalt sulfate, and an aqueous manganese sulfate solution were mixed so that the ratio (molar ratio) of Ni, Co, and Mn was Ni:Co:Mn = 34:33:33 to obtain a mixed aqueous solution. In the reaction tank, 10 L of pure water to which 220 g of 25 wt% aqueous ammonia had been previously added was prepared as a mother liquor and continuously introduced into the reaction tank at a flow rate of 0.7 L / min during the reaction.

[0119] Thereafter, while rotating the stirring blade at 500 rpm, the temperature of the reaction solution was set to 50 °C, and the above-mentioned mixed aqueous solution, sodium hydroxide aqueous solution, and aqueous ammonia were simultaneously dropped using metering pumps, and the dropping amount of the alkaline solution was adjusted so that the pH became 11.2 to conduct a crystallization reaction. During the crystallization reaction, the slurry solution in the reaction tank was filtered by a filtration device in a pipe installed from the lower part of the reaction tank to the outside and then subjected to circulating filtration to be refluxed to the upper part of the reaction tank. Sampling was appropriately performed, and the raw materials were dropped until the average particle size reached 11 μm, and the reaction was continued. Thereafter, the dropping of the raw materials was terminated and the reaction slurry was recovered.

[0120] After recovering the reaction slurry, solid-liquid separation was performed, washing was carried out using a 6N sodium hydroxide solution, and further washing with pure water was performed to reduce residual impurities. Then, the coprecipitate in the cake state was dried at 90 °C for 12 hours in an air environment to obtain a precursor composite compound sample.

[0121] The obtained precursor composite hydroxide sample and lithium carbonate were weighed and mixed so that the finally obtained lithium metal composite oxide sample had Li / (Ni + Co + Mn) = 1.13. Then, it was fired for 4 hours at a maximum temperature of 930°C in an air atmosphere (oxygen concentration: 21 vol%), and the obtained fired product was pulverized to obtain a lithium metal composite oxide sample. When the fluidity was confirmed by sieving, 86% passed through.

[0122] Table 1 shows the average particle size, specific surface area, dibutyl phthalate oil absorption, roundness in the range of D50 ± 0.5 μm, coefficient of variation of roundness, evaluation results of fluidity, and evaluation results of output characteristics for each sample.

[0123]

Table 1

Claims

1. General formula Li 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, 0.9 ≦ a ≦ 1.2, 0 ≦ x ≦ 0.4, 0 ≦ y ≦ 0.4, 0 ≦ z ≦ 0.1, -0.5 ≦ α ≦ 0.5), and contains a lithium metal composite oxide represented by The cumulative 50% particle diameter D50 in the volume-based particle size distribution is 1 μm or more and 10 μm or less, The average circularity of secondary particles having a particle diameter in the range of D50 (μm) ± 0.5 μm is 0.73 or more, The coefficient of variation of the circularity of secondary particles having a particle diameter in the range of D50 (μm) ± 0.5 μm is 0.09 or less Lithium metal composite oxide powder.

2. The BET specific surface area is 0.5 m ２ / g or more and 3 m ２ / g or less The lithium metal composite oxide powder according to Claim 1.

3. The oil absorption amount of dibutyl phthalate per 100 g of the lithium metal composite oxide powder is 20 mL / 100 g or more and 60 mL / 100 g or less The lithium metal composite oxide powder according to Claim 1 or 2.

4. Including the lithium metal composite oxide powder according to Claim 1 or 2 Positive electrode active material for non-aqueous electrolyte secondary battery.

5. A non-aqueous electrolyte secondary battery comprising a positive electrode including the positive electrode active material for non-aqueous electrolyte secondary battery according to Claim 4 Non-aqueous electrolyte secondary battery.

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