TW201633588A - Active material of positive electrode for lithium battery, positive electrode for lithium battery, and lithium battery - Google Patents

Abstract

The present invention provides an active material of positive electrode for lithium battery with good battery characteristics. The active material of positive electrode for lithium battery comprises transition metal composite oxides containing Li, and inorganic ceramics with average particle diameter of 0.02~1 <mu>m and 10~1000 wtppm. (Claim 2) The inorganic ceramics are the oxides, nitrides, or the combination of oxides and nitrides of more than one element selected from Al, Si, Mg, Zr, Y.

Description

Positive electrode active material for lithium ion battery, positive electrode for lithium ion battery, and lithium ion battery

The present invention relates to a positive electrode active material for a lithium ion battery, a positive electrode for a lithium ion battery, and a lithium ion battery.

A lithium-containing transition metal oxide is generally used as a positive electrode active material of a lithium ion battery. Specifically, it is lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), etc., in order to improve characteristics (high capacitance, cycle characteristics, storage characteristics, and reduction of internal resistance) , rate characteristics) or improve security, and promote these composites. Lithium-ion batteries for large-scale applications such as vehicle use or load leveling require different characteristics from previous mobile phones or computers.

Various studies and developments have been made in the past to improve the battery characteristics required for such lithium ion batteries. As means for improving the characteristics of the battery, for example, a material which increases the electrode density of the positive electrode material and mixes the particles of the size is proposed. This material is a structure in which small particles of the same material are filled in the gap of the large particles of the transition metal complex oxide containing Li.

As such a technique, for example, Patent Document 1 discloses a positive electrode active material characterized in that the average particle diameter of the lithium composite oxide particles is in the range of 0.1 to 50 μm, and the particle size distribution of the lithium composite oxide particles exists. More than 2 peaks. And, according to this record A positive electrode active material capable of providing a nonaqueous electrolyte secondary battery having excellent initial capacitance and capacitance retention can be obtained.

Further, Patent Document 2 discloses a positive electrode active material for a nonaqueous electrolyte secondary battery, characterized in that particles constituting a powder of a lithium metal composite oxide are mainly formed by a plurality of primary particles of a lithium metal composite oxide. The secondary particles are formed in a spherical shape or an ellipsoidal shape, and the particle diameter is substantially in the range of 1 to 40 μm, and the average particle diameter is 5 to 11 μm, and the distribution of the particle diameter is a regular distribution. The particles are composed of particles having a particle diameter of 1 μm or less mixed at a ratio of 0.5 to 3.5% by volume, and the specific surface area of the powder is larger than the powder having a particle diameter of 1 μm or less from the powder. At 0.3 m ² /g, the tap density of the powder is at most 0.2 g/cm ³ smaller than the tap density of the powder composed of particles having a particle diameter of 1 μm or less from the powder. In addition, it is described that it is possible to provide a secondary battery which does not cause manufacturing defects such as dust generation or the packing density when the powder of the positive electrode active material for a non-aqueous electrolyte secondary battery is micronized. The capacitance caused by the low voltage is lowered, and the contact area between the electrolytic solution and the positive electrode active material is increased, and the portion where the Li ion is diffused is increased, whereby high output can be achieved.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2000-82466

[Patent Document 2] Japanese Patent No. 4766840

However, when a positive electrode active material is produced by mixing a transition metal complex oxide containing Li having a large particle diameter and a small particle diameter, there are the following problems. In general, small particles Since the transition metal complex oxide containing Li in the diameter is charged and discharged, the area of the surface-deformed portion formed by the reaction of the electrolytic solution or the like is large with respect to the volume, so that the deterioration is rapid and the charge and discharge characteristics are extremely poor. Therefore, when a positive electrode active material containing a transition metal complex oxide containing Li having a large particle diameter and a small particle diameter is used, there is a possibility that the charge and discharge function of the battery is lowered. Further, since the transition metal complex oxide containing Li having a small particle diameter deteriorates the electrolytic solution in the vicinity thereof, the surface activity of the Li-containing transition metal composite oxide having a large particle diameter adjacent thereto is lowered, and as a result, the overall charge is lowered. The flaw in discharge characteristics.

An object of the present invention is to provide a positive electrode active material for a lithium ion battery having excellent battery characteristics.

The present inventors conducted various studies to solve such a problem, and as a result, it has been found that battery characteristics can be obtained by mixing a transition metal-containing composite oxide containing Li and a specific amount of inorganic ceramics as particles having a small particle diameter. A positive electrode active material for a lithium ion battery.

The present invention, which is completed based on the above findings, is a positive electrode active material for a lithium ion battery, which comprises a transition metal complex oxide containing Li and an inorganic ceramic having an average particle diameter of 0.02 to 1 μm and 10 to 1000 wtppm.

In one embodiment, the inorganic ceramic is an oxide, a nitride, or a carbide of one or more elements selected from the group consisting of Al, Si, Mg, Zr, and Y. A combination of the same.

In another embodiment, the inorganic ceramic material for a lithium ion battery of the present invention is selected from the group consisting of Al ₂ O ₃ , SiO ₂ , MgO, ZrO ₂ , SiC, and YSZ (yttria-stabilized zirconia). One or more of the group.

Further, the positive electrode active material for a lithium ion battery of the present invention is further embodied In the form, the Li-containing transition metal composite oxide has an average particle diameter of 4 to 12 μm.

In still another embodiment of the present invention, the Li-containing transition metal composite oxide is represented by a composition formula: Li _1+x Ni _1-y Me _y O _2+z .

(In the above formula, Me is any one of Mn, Co, Al, and Mg, x is -0.1 to 0.1, y is a total composition of metals represented by Me, and is 0.1 to 0.5, and z is -0.1 to 0.2) .

In still another aspect of the invention, the positive electrode for a lithium ion battery using the positive electrode active material for a lithium ion battery of the invention.

In still another aspect of the invention, a lithium ion battery using the positive electrode for a lithium ion battery of the invention is used.

According to the present invention, a positive electrode active material for a lithium ion battery having excellent battery characteristics can be provided.

(Composition of positive active material for lithium ion battery)

The positive electrode active material for a lithium ion battery of the present invention contains a transition metal complex oxide containing Li and an inorganic ceramic having an average particle diameter of 0.02 to 1 μm and 10 to 1000 wtppm. According to such a configuration, the inorganic ceramic functions as a particle having a small particle diameter, and promotes contact between the particles having a large particle diameter, that is, the transition metal complex oxide containing Li. Therefore, the rate of the battery using the positive electrode active material is particularly high. Sexual improvement. Further, since the transition metal complex oxide containing Li is not used as a particle having a small particle diameter as in the prior art, the deterioration of the particles having a small particle diameter is suppressed, so that the deterioration of the rate characteristic of the battery using the positive electrode active material is favorably suppressed.

When the average particle diameter of the inorganic ceramic is less than 0.02 μm, the effect of improving the rate characteristic is insufficient. When the average particle diameter exceeds 1 μm, the resistance is increased, so that the rate characteristics are lowered. Further, when the content of the inorganic ceramic is less than 10 wtppm, the effect of improving the rate characteristic is insufficient, and if it exceeds 1000 wtppm, the initial capacitance of the battery using the positive electrode active material is lowered. The average particle diameter of the inorganic ceramic is preferably from 0.1 to 1 μm, more preferably from 0.3 to 0.9 μm. Further, the content of the inorganic ceramic is preferably from 50 to 1,000 wtppm, more preferably from 100 to 500 wtppm.

In the positive electrode active material for a lithium ion battery of the present invention, the inorganic ceramic is preferably an oxide, a nitride, a carbide or a combination of one or more elements selected from the group consisting of Al, Si, Mg, Zr, and Y. It is preferably one or more selected from the group consisting of Al ₂ O ₃ , SiO ₂ , MgO, ZrO ₂ , SiC, and YSZ (yttria-stabilized zirconia).

In the positive electrode active material for a lithium ion battery of the present invention, the average particle diameter of the transition metal complex oxide containing Li is preferably 4 to 12 μm. When the average particle diameter of the transition metal-containing composite oxide containing Li is less than 4 μm, the particle size of the ceramic particles to be added is relatively increased as compared with the particle size of the transition metal-containing composite oxide containing Li, and thus the following effects are obtained. The ceramic particles added may hinder the contact of the transition metal complex oxide containing Li with each other. In addition, when the average particle diameter of the transition metal-containing composite oxide containing Li exceeds 12 μm, the gap between the transition metal-containing composite oxide particles containing Li becomes large, and in order to promote contact between the Li-containing transition metal composite oxide particles, it is necessary to add A large number of ceramic particles have the problem of reducing the discharge capacitance of the battery. The average particle diameter of the transition metal-containing composite oxide containing Li is more preferably 4 to 10 μm, and even more preferably 6 ~10μm.

In the positive electrode active material for a lithium ion battery of the present invention, the transition metal complex oxide containing Li is preferably represented by a composition formula: Li _1+x Ni _1-y Me _y O _2+z

(In the above formula, Me is any one of Mn, Co, Al, and Mg, x is -0.1 to 0.1, y is a total composition of metals represented by Me, and is 0.1 to 0.5, and z is -0.1 to 0.2) .

The ratio of lithium to the total metal in the positive electrode active material for a lithium ion battery is 0.9 to 1.1, which is because there is a concern that if it is less than 0.9, it is difficult to maintain a stable crystal structure, and if it exceeds 1.1, the battery cannot be secured. High capacitance. In addition, since the composition of nickel in the positive electrode active material for a lithium ion battery is 0.5 to 0.9, the capacitance, output, and safety of the lithium ion battery using the positive electrode active material for a lithium ion battery are improved in balance.

(Method for producing positive electrode active material for lithium ion battery)

A method for producing a positive electrode active material for a lithium battery according to an embodiment of the present invention will be described in detail.

- Production of transition metal composite oxide powder containing Li -

First, a metal salt solution obtained by dissolving nickel nitrate, optionally cobalt nitrate, manganese nitrate, aluminum nitrate, and magnesium nitrate in pure water so that the metal atom is a specific amount is prepared. Next, lithium carbonate is added to pure water so that the molar amount of lithium and the above-mentioned metal element is 0.9 to 1.1:1, and the solution is stirred, and the metal salt solution is added dropwise to prepare a Li-containing solution. , Ni, depending on the case, Co, Mn, Al, Mg slurry.

Next, the slurry is spray-dried using, for example, a micro-spray dryer having a three-fluid nozzle to obtain a powder containing Li, Ni, and optionally Co, Mn, Al, and Mg.

Next, the powder contains Ni in an amount of 70% or more and 90% or less with respect to the total amount of the metal. In this case, for example, the powder was fired at 880 ° C for 2 hours using a roller hearth kiln, and then cooled to 700 ° C for 1 hour and held for 2 hours, and then cooled to room temperature over 3 hours. Further, when the powder contains 50% or more of the total metal amount and less than 70% of Ni, the powder is fired at 900 ° C for 2 hours in a roller kiln, and then cooled to 1 hour. After maintaining at 700 ° C for 2 hours, it was cooled to room temperature over 3 hours.

Next, the obtained fired product is crushed using, for example, a roll mill and a pulverizer to obtain a transition metal complex oxide powder containing Li.

- Preparation of inorganic ceramic powder -

The inorganic ceramic powder is appropriately pulverized in advance using, for example, a jet mill to prepare an inorganic ceramic powder having a specific particle size.

-Preparation of positive active material -

The inorganic ceramic powder is added to the powder of the above-mentioned transition metal-containing composite oxide containing Li, and mixed with a ball mill, for example, to obtain a positive electrode active material for a lithium ion battery of the present invention.

(Construction of a positive electrode for a lithium ion battery and a lithium ion battery using the same)

The positive electrode for a lithium ion battery according to the embodiment of the present invention has a structure in which a positive electrode mixture prepared by mixing a positive electrode active material for a lithium ion battery, a conductive auxiliary agent, and a binder, which are configured as described above, is provided in an aluminum foil or the like. A single-sided or double-sided structure of the current collector. Further, the lithium ion battery according to the embodiment of the present invention includes the positive electrode for a lithium ion battery having such a configuration.

[Examples]

The following examples are provided to better understand the present invention and its advantages, but the invention is not limited by the examples.

- Production of transition metal composite oxide powder containing Li -

(Examples 1 to 23, Comparative Examples 1 to 14, Reference Examples 1 to 3)

First, a metal salt solution obtained by dissolving nickel nitrate, manganese nitrate, and cobalt nitrate in pure water in such a manner that the molar ratios of Ni, Mn, and Co atoms are 8:1:1 are prepared. Next, lithium carbonate is added to pure water in such a manner that the molar ratio of lithium to the above-mentioned metal element is 1.04:1, and the mixture is stirred, and the resulting metal salt solution is added dropwise while stirring to prepare Li, Ni. , Co and Mn slurry. Next, the slurry was spray-dried using a micro spray dryer having a three-fluid nozzle to obtain a powder containing Li, Ni, Co, and Mn. Next, the powder was heated from room temperature to 880 ° C for 1 hour using a roller kiln for 1 hour, and after cooling, it was cooled to 700 ° C for 1 hour and held for 2 hours, and then cooled to room for 3 hours. temperature. Next, the obtained calcined product was crushed by a roll mill and a pulverizer, and the crushing strength of the pulverizer was adjusted to obtain Li-containing transition metal composite oxide powder A having three kinds of particle sizes.

(Examples 24 to 25, Comparative Example 15, Reference Example 4)

A metal salt solution obtained by dissolving nickel nitrate and manganese nitrate in pure water so that the molar ratio of Ni and Mn atoms is 8:2, respectively. Next, lithium carbonate is added to pure water so that the molar ratio of lithium and the above-mentioned metal elements is 1.02:1, and the solution is stirred, and the metal salt solution is added dropwise thereto to prepare Li, Ni. , Mn slurry. Next, the slurry was spray-dried using a micro spray dryer having a three-fluid nozzle to obtain a powder containing Li, Ni, and Mn. Next, the powder was heated from room temperature to 880 ° C for 1 hour using a roller kiln for 1 hour, and after cooling, it was cooled to 700 ° C for 1 hour and held for 2 hours, and then cooled to room for 3 hours. temperature. Next, the obtained fired product was crushed using a roll mill and a pulverizer to obtain a transition metal composite oxide powder B containing Li.

(Examples 26 to 27, Comparative Example 16, Reference Example 5)

A metal salt solution obtained by dissolving nickel nitrate, cobalt nitrate, and aluminum nitrate in pure water in such a manner that the molar ratios of Ni, Co, and Al atoms were 8:1:1. Next, lithium carbonate is added to pure water so that the molar ratio of lithium and the above-mentioned metal elements is 1.00:1, and the solution is stirred, and the metal salt solution is added dropwise thereto to prepare Li, Ni. , Co, Al slurry. Next, the slurry was spray-dried using a micro spray dryer having a three-fluid nozzle to obtain a powder containing Li, Ni, Co, and Al. Next, the powder was heated from room temperature to 880 ° C for 1 hour using a roller kiln for 1 hour, and after cooling, it was cooled to 700 ° C for 1 hour and held for 2 hours, and then cooled to room for 3 hours. temperature. Next, the obtained fired product was crushed using a roll mill and a pulverizer to obtain a transition metal complex oxide powder C containing Li.

(Examples 28 to 29, Comparative Example 17, Reference Example 6)

A metal salt solution obtained by dissolving nickel nitrate, cobalt nitrate, and magnesium nitrate in pure water in such a manner that the molar ratios of Ni, Co, and Mg atoms were 8:1:1. Next, lithium carbonate is added to pure water in such a manner that the molar ratio of lithium to the above-mentioned metal element is 1.04:1, and the mixture is stirred, and the resulting metal salt solution is added dropwise while stirring to prepare Li, Ni. , Co, Mg slurry. Next, the slurry was spray-dried using a micro spray dryer having a three-fluid nozzle to obtain a powder containing Li, Ni, Co, and Mg. Next, the powder was heated from room temperature to 880 ° C for 1 hour using a roller kiln for 1 hour, and after cooling, it was cooled to 700 ° C for 1 hour and held for 2 hours, and then cooled to room for 3 hours. temperature. Next, the obtained fired product was crushed using a roll mill and a pulverizer to obtain a transition metal complex oxide powder D containing Li.

(Examples 30 to 31, Comparative Example 18, Reference Example 7)

Nickel nitrate is prepared in such a manner that the molar ratios of Ni, Mn, and Co atoms are 5:3:2, respectively. A metal salt solution in which manganese nitrate or cobalt nitrate is dissolved in pure water. Next, lithium carbonate is added to pure water in such a manner that the molar ratio of lithium to the above-mentioned metal element is 1.04:1, and the mixture is stirred, and the resulting metal salt solution is added dropwise while stirring to prepare Li, Ni. , Mn, Co slurry. Next, the slurry was spray-dried using a micro spray dryer having a three-fluid nozzle to obtain a powder containing Li, Ni, Mn, and Co. Next, the powder was heated from room temperature to 900 ° C for 1 hour using a roller kiln for 1 hour, and after cooling, it was cooled to 700 ° C for 1 hour and held for 2 hours, and then cooled to room for 3 hours. temperature. Next, the obtained fired product was crushed using a roll mill and a pulverizer to obtain a transition metal complex oxide powder E containing Li.

(Examples 32 to 33, Comparative Example 19, Reference Example 8)

A metal salt solution obtained by dissolving nickel nitrate, cobalt nitrate, aluminum nitrate, and magnesium nitrate in pure water in such a manner that the molar ratios of Ni, Co, Al, and Mg atoms are 5:3:1:1. Next, lithium carbonate is added to pure water in such a manner that the molar ratio of lithium to the above-mentioned metal element is 1.04:1, and the mixture is stirred, and the resulting metal salt solution is added dropwise while stirring to prepare Li, Ni. , Co, Al, Mg slurry. Next, the slurry was spray-dried using a micro spray dryer having a three-fluid nozzle to obtain a powder containing Li, Ni, Co, Al, and Mg. Next, the powder was heated from room temperature to 900 ° C for 1 hour using a roller kiln for 1 hour, and after cooling, it was cooled to 700 ° C for 1 hour and held for 2 hours, and then cooled to room for 3 hours. temperature. Next, the obtained fired product was crushed using a roll mill and a pulverizer to obtain a transition metal complex oxide powder F containing Li.

- Preparation of inorganic ceramic powder -

For the use in the examples, commercially available inorganic ceramic powders were appropriately pulverized by a jet mill to prepare inorganic ceramic powders having a specific particle size. The particle size was measured by a laser diffraction scattering type particle size distribution measuring apparatus (Microtrac manufactured by Nikkiso Co., Ltd.), and the particle size of the obtained particle size distribution curve having a volume cumulative frequency of 50% was defined as an average particle diameter. In addition, since Al ₂ O ₃ used in Comparative Example 3 was smaller than the measurement range in the present apparatus, it was observed by a scanning electron microscope and found to be about 0.01 μm.

- Production of a small particle size transition metal complex oxide containing Li -

In order to use it in the comparative example, the powder of the Li-containing transition metal composite oxide pulverized by the pulverizer was pulverized by a jet mill to prepare a Li-containing transition of a small particle diameter for use in the comparative example. Metal composite oxide.

(Evaluation)

- Evaluation of composition of transition metal composite oxide containing Li -

The metal content in each of the transition metal-containing composite oxides containing Li was measured by an inductively coupled plasma emission spectroscopic analyzer (ICP-OES), and the composition of each metal was measured. Further, the lithium content was measured by ion chromatography, and the oxygen content was measured by the LECO method.

The composition of the transition metal-containing composite oxide A containing Li used in Examples 1 to 23, Comparative Examples 1 to 14, and Reference Examples 1 to 3 was Li _1.04 Ni _0.80 Mn _0.10 Co _0.10 O _2.15 .

The composition of the transition metal-containing composite oxide B containing Li used in Examples 24 to 25, Comparative Example 15, and Reference Example 4 was Li _1.02 Ni _0.80 Mn _0.20 O _2.12 .

The compositions of the transition metal-containing composite oxide C containing Li used in Examples 26 to 27, Comparative Example 16, and Reference Example 5 were Li _1.00 Ni _0.80 Co _0.10 Al _0.10 O _2.04 .

The composition of the transition metal-containing composite oxide D containing Li used in Examples 28 to 29, Comparative Example 17, and Reference Example 6 was Li _1.04 Ni _0.80 Co _0.10 Mg _0.10 O _2.07 .

The composition of the transition metal-containing composite oxide E containing Li used in Examples 30 to 31, Comparative Example 18, and Reference Example 7 was Li _1.04 Ni _0.50 Mn _0.30 Co _0.20 O _2.12 .

The composition of the transition metal-containing composite oxide F containing Li used in Examples 32 to 33, Comparative Example 19, and Reference Example 8 was Li _1.04 Ni _0.50 Co _0.30 Al _0.10 Mg _0.10 O _2.16 .

- Evaluation of average particle size -

The particle size distribution of the large-sized Li-containing transition metal composite oxide and the Li-containing small particle diameter were measured by a laser diffraction scattering type particle size distribution measuring apparatus (Microtrac manufactured by Nikkiso Co., Ltd.), respectively. The particle size distribution of the transition metal composite oxide (comparative example only), and the particle diameter of the obtained particle size distribution curve of 50% by volume is set as the average particle diameter.

-Preparation of positive active material -

The above inorganic ceramic powder (Examples and Comparative Examples) or the above-described small-diameter Li-containing transition metal composite oxide (Comparative Example) is added to the powder of the Li-containing transition metal composite oxide, and mixed by using a ball mill. Thereby, a positive electrode active material for a lithium ion battery was produced.

- Evaluation of battery characteristics -

Weighing 96% by weight of the positive electrode active material, 1.6% by weight of PVDF, and 2.4% by weight of carbon black, and adding the positive electrode active material and carbon black by adding PVDF to N-methylpyrrolidone, the obtained is obtained. The slurry was applied to an Al foil, dried and then pressurized to prepare a positive electrode. A 2032 type coin cell for evaluation was prepared by using Li metal as a counter electrode and dissolving 1 M-LiPF ₆ in EC-DMC (1:1). In the 25 ° C constant temperature bath, the charge and discharge voltage range is set to 3.0V ~ 4.3V, charging is carried out at 0.1 C in all cycles, discharge is performed in the first cycle and the 21st cycle at 0.1 C, and other cycles are 1 C get on. The initial rate characteristic is calculated by dividing the discharge capacity of the second cycle 1 C by the discharge capacitance of 0.1 C in the first cycle, and dividing the discharge capacitance at the 22nd cycle 1 C by the 21st cycle of 0.1 C. The rate characteristic after the 21st cycle was calculated from the discharge capacitance.

These results are shown in Tables 1 and 2.

(Evaluation results)

Tables 1 and 2 are prepared according to the composition of the Li-containing transition metal composite oxide having a large particle diameter as a base. Further, Reference Examples 1 to 8 are samples of only large particles which are basic. The positive electrode active material usually has different characteristics depending on the composition. For example, a person with more Ni has the following characteristics: the capacitance is higher, but the rate and the rate after the cycle become worse.

When comparing the respective compositions of the Li-containing transition metal composite oxide having a large particle size as a base, it is found that the capacitance of the first cycle is substantially unchanged by the addition of the ceramic particles, and the rate is improved after the cycle. . Further, when a small-sized Li-containing transition metal composite oxide particle having the same composition was added, it was found that the initial rate was slightly improved, but after the cycle, it was largely deteriorated compared with the case where it was not added.

Further, each of Examples 1 to 33 contained a transition metal composite oxide containing Li and an inorganic ceramic having an average particle diameter of 0.02 to 1 μm and 10 to 1000 wtppm, so that the battery characteristics were good.

Further, in Comparative Examples 1 to 19, inorganic ceramics were not contained as small particles, or inorganic ceramics were contained as small particles, but at least one of battery characteristics was outside the range of 0.02 to 1 μm and 10 to 1000 wtppm. bad.

Claims (7)

A positive electrode active material for a lithium ion battery, comprising a transition metal composite oxide containing Li and an inorganic ceramic having an average particle diameter of 0.02 to 1 μm and 10 to 1000 wtppm. The positive electrode active material for a lithium ion battery according to the first aspect of the invention, wherein the inorganic ceramic is an oxide, a nitride, or a carbide of one or more elements selected from the group consisting of Al, Si, Mg, Zr, and Y. A combination of the same. The positive electrode active material for a lithium battery according to the second aspect of the invention, wherein the inorganic ceramic is a group selected from the group consisting of Al ₂ O ₃ , SiO ₂ , MgO, ZrO ₂ , SiC, and YSZ (yttria-stabilized zirconia) One or more of them. The positive electrode active material for a lithium ion battery according to the first aspect of the invention, wherein the Li-containing transition metal composite oxide has an average particle diameter of 4 to 12 μm. The positive electrode active material for a lithium ion battery according to the first aspect of the invention, wherein the Li-containing transition metal composite oxide is represented by a composition formula: Li _1+x Ni _1-y Me _y O _2+z (the above formula) In the above, Me is at least one of Mn, Co, Al, and Mg, x is -0.1 to 0.1, y is a total composition of metals represented by Me, and is 0.1 to 0.5, and z is -0.1 to 0.2). A positive electrode for a lithium ion battery, which uses the positive electrode active material for a lithium ion battery according to any one of claims 1 to 5. A lithium ion battery using the positive electrode for a lithium ion battery of claim 6 of the patent application.