JP2013152866A - Positive electrode active material for nonaqueous electrolytic secondary battery and method of manufacturing the same, and nonaqueous electrolytic secondary battery with the positive electrode active material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive electrode active material for a nonaqueous electrolytic secondary battery which allows a high capacity and high output to be achieved when it is used as a positive electrode material.SOLUTION: The method of manufacturing a positive electrode active material for a nonaqueous electrolytic secondary battery comprises: a first step in which a tungsten acid compound solution with a W compound dissolved therein is added to and mixed with Li metal complex oxide powder including primary particles expressed by a general formula of LiNiCoMO(where 0.10≤x≤0.35, 0≤y≤0.35, 0.97≤z≤1.20, M is at least one element selected from Mn, V, Mg, Mo, Nb, Ti and Al), and secondary particles each composed of an agglomeration of the primary particles, thereby distributing W over the surfaces of the primary particles; and a second step in which a heat treatment is performed on the resultant mixture of the tungsten acid compound solution and the Li metal complex oxide powder, thereby forming fine particles including W and Li on the surfaces of the primary particles.

Description

  The present invention relates to a positive electrode active material for a non-aqueous electrolyte secondary battery, a method for producing the same, and a non-aqueous electrolyte secondary battery using the positive electrode active material.

In recent years, with the widespread use of portable electronic devices such as mobile phones and laptop computers, development of small and lightweight non-aqueous electrolyte secondary batteries having high energy density is strongly desired. In addition, development of a high output secondary battery is strongly desired as a battery for electric vehicles including hybrid vehicles.
As a secondary battery satisfying such requirements, there is a lithium ion secondary battery. This lithium ion secondary battery is composed of a negative electrode, a positive electrode, an electrolyte, and the like, and a material capable of desorbing and inserting lithium is used as the active material of the negative electrode and the positive electrode.
This lithium ion secondary battery is currently under active research and development. Among them, a lithium ion secondary battery using a layered or spinel type lithium metal composite oxide as a positive electrode material is 4V class. As a battery having a high energy density is being put into practical use, a high voltage can be obtained.

The materials mainly proposed so far include lithium cobalt composite oxide (LiCoO ₂ ), which is relatively easy to synthesize, lithium nickel composite oxide (LiNiO ₂ ) using nickel, which is cheaper than cobalt, and lithium nickel. Examples thereof include cobalt manganese composite oxide (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ) and lithium manganese composite oxide (LiMn ₂ O ₄ ) using manganese.
Among these, lithium nickel composite oxide and lithium nickel cobalt manganese composite oxide are attracting attention as materials that have good cycle characteristics and can provide high output with low resistance. In recent years, it is important to reduce resistance required for high output. Is being viewed.

Therefore, the addition of foreign elements is used as a method for realizing the low resistance, and transition metals that can take high numbers such as W, Mo, Nb, Ta, and Re are particularly useful.
For example, Patent Document 1 contains one or more elements selected from Mo, W, Nb, Ta, and Re in an amount of 0.1 to 5 mol% with respect to the total molar amount of Mn, Ni, and Co. Lithium transition metal compound powder for a lithium secondary battery positive electrode material has been proposed, and Mo, W, Nb, Ta, and Li in the surface portion of primary particles and the total of metal elements other than Mo, W, Nb, Ta, and Re The total atomic ratio of Re is preferably 5 times or more of the atomic ratio of the entire primary particle.

  According to this proposal, it is said that it is possible to achieve both low cost and high safety of lithium transition metal-based compound powder for lithium secondary battery positive electrode material, high load characteristics, and improved powder handleability. . However, the lithium transition metal-based compound powder is obtained by pulverizing raw materials in a liquid medium, spray-drying a slurry in which these are uniformly dispersed, and firing the resulting spray-dried body. Therefore, a part of different elements such as Mo, W, Nb, Ta, and Re is replaced with Ni arranged in a layer, and there is a problem that battery characteristics such as battery capacity and cycle characteristics are deteriorated. It was.

  Patent Document 2 discloses a positive electrode active material for a non-aqueous electrolyte secondary battery having at least a layered lithium transition metal composite oxide, the lithium transition metal composite oxide being composed of primary particles and aggregates thereof. A non-aqueous electrolyte having a compound which is present in the form of a particle composed of one or both of secondary particles and has at least one selected from the group consisting of molybdenum, vanadium, tungsten, boron and fluorine on at least the surface of the particle A positive electrode active material for a secondary battery has been proposed.

In this proposal, it is said that a positive electrode active material for a non-aqueous electrolyte secondary battery having excellent battery characteristics even under a more severe use environment can be obtained, and in particular, molybdenum, vanadium, tungsten, boron and fluorine are used on the particle surface. By having a compound having at least one selected from the group, the initial characteristics are improved without impairing the improvement of thermal stability, load characteristics and output characteristics.
However, the effect of at least one additive element selected from the group consisting of molybdenum, vanadium, tungsten, boron and fluorine is considered to be an improvement in initial characteristics, that is, initial discharge capacity and initial efficiency, and refers to output characteristics. is not. Further, according to the disclosed manufacturing method, since the additive element is mixed with the hydroxide that has been heat-treated at the same time as the lithium compound and fired, a part of the additive element is replaced with nickel arranged in layers. There was a problem that caused the battery characteristics to deteriorate.

Further, Patent Document 3 discloses a metal including at least one selected from Ti, Al, Sn, Bi, Cu, Si, Ga, W, Zr, B, and Mo around the positive electrode active material and / or a plurality of these. A positive electrode active material coated with an intermetallic compound and / or oxide obtained by a combination has been proposed.
Such a coating can absorb oxygen gas and ensure safety, but no output characteristics are disclosed. Further, the disclosed manufacturing method is a method of coating using a planetary ball mill, and such a coating method causes physical damage to the positive electrode active material, resulting in deterioration of battery characteristics.

In Patent Document 4, a composite oxide particle mainly composed of lithium nickelate is subjected to heat treatment by adhering a tungstic acid compound, and the content of carbonate ions is 0.15% by weight or less. A positive electrode active material has been proposed.
According to this proposal, there is a tungstic acid compound or a decomposition product of the tungstic acid compound on the surface of the positive electrode active material, and the oxidation activity on the surface of the composite oxide particles in a charged state is suppressed. Although gas generation can be suppressed, the output characteristics are not disclosed at all.

  Furthermore, the disclosed production method preferably comprises a composite oxide particle heated to a boiling point or higher of a solution in which an adherent component is dissolved, and a sulfuric acid compound, a nitric acid compound, a boric acid compound, or a phosphoric acid compound as well as a tungstate compound. A solution dissolved in a solvent is applied as an adsorbing component. Since the solvent is removed in a short time, the tungsten compound is not sufficiently dispersed on the surface of the composite oxide particles and is uniformly applied. It is difficult.

Patent Document 5 has a surface layer containing at least one element selected from the group consisting of Mo and W and Li on the surface of the lithium composite oxide powder capable of inserting and extracting Li ions. A positive electrode active material for a lithium secondary battery has been proposed.
According to this proposal, a positive electrode active material for a lithium secondary battery having better thermal stability than a conventionally proposed positive electrode active material can be provided without greatly degrading a high initial discharge capacity. No properties are disclosed at all.
Further, the disclosed manufacturing method is a method in which a mixture of a lithium composite oxide powder and a composite oxide containing Li and at least one element selected from the group consisting of Mo and W is about 650 to about 950 ° C. Since the heat treatment is performed at a temperature of 5 ° C. and the solids are mixed with each other, it is difficult to uniformly disperse the additive element on the surface of the lithium composite oxide powder.

In addition, as a method for adding W to the lithium composite oxide powder, for example, Patent Document 6 provides an active material main body powder made of spinel type lithium manganese composite oxide, while iron, vanadium, tungsten, molybdenum, A compound containing at least one element selected from rhenium and an alkali metal element is dissolved in a solvent to prepare a solution, and the active material body powder is added to and mixed in the solution, and the resulting mixture is obtained. A method for producing a positive electrode active material that is heat-treated after drying is proposed.
This proposal aims to minimize the decrease in initial capacity and to effectively suppress the decrease in capacity accompanying the progress of charge / discharge cycles at high temperatures. Not disclosed. Furthermore, the disclosed manufacturing method is a method in which a solution and an active material body powder are mixed, but no consideration is given to deterioration of battery characteristics due to elution of lithium from the active material into the solvent.

  As described above, a lithium metal composite oxide having improved output characteristics while maintaining a high initial discharge capacity and good cycle characteristics is not disclosed, and its development is desired.

JP 2009-289726 A JP 2005-251716 A Japanese Patent Laid-Open No. 11-16566 JP 2010-40383 A JP 2002-75367 A JP 2000-149948 A

  In view of such problems, the present invention has an object to provide a positive electrode active material for a non-aqueous electrolyte secondary battery that, when used as a positive electrode material, provides high capacity and high output.

  In order to solve the above problems, the present inventors have conducted intensive research on the powder properties of lithium metal composite oxides used as the positive electrode active material for non-aqueous electrolyte secondary batteries and the effect on the positive electrode resistance of the battery. And found that it is possible to reduce the positive electrode resistance of the battery and improve the output characteristics by forming lithium tungstate and its hydrate on the surface of the primary particles constituting the lithium metal composite oxide powder. It was.

  Furthermore, as a manufacturing method thereof, lithium tungstate can be formed on the entire primary particle surface by mixing and heat-treating a tungstic acid compound solution capable of reacting with lithium contained in the positive electrode active material and a lithium metal composite oxide. It has been found that this is possible, and the present invention has been completed.

That is, the first invention of the present invention is a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, the general formula _{Li z Ni 1-x-y} Co x M y O 2 ( where 0.10 ≦ x ≦ 0.35, 0 ≦ y ≦ 0.35, 0.97 ≦ z ≦ 1.20, M is at least one element selected from Mn, V, Mg, Mo, Nb, Ti and Al) The primary particles of the lithium metal composite oxide powder are prepared by adding a tungstic acid compound solution to the lithium metal composite oxide powder composed of the primary particles and the secondary particles formed by aggregation of the primary particles. The first step in which a tungstic acid compound is dispersed on the surface of the particles, and the lithium metal composite oxide powder in which the tungstic compound is dispersed are heat-treated to convert lithium tungstate into one of the lithium metal composite oxide powders. And having a second step of forming by crystal growth on the surface of the particles.

  The manufacturing method according to the second invention of the present invention is characterized by having a step of washing the lithium metal composite oxide powder with water before performing the first step in the first invention.

  According to a third aspect of the present invention, the amount of tungsten contained in the tungstic acid compound solution in the first and second inventions includes Ni, Co and M contained in the lithium metal composite oxide powder mixed with the tungstic acid compound solution. The total number of atoms is 0.1 to 3.0 mol%, and the tungsten concentration in the tungstic acid compound solution is 0.05 to 4 mol / L.

  According to a fourth aspect of the present invention, the tungstic acid compound solution according to the first to third aspects is an aqueous solution of a water-soluble tungstic acid compound, and the aqueous solution of the water-soluble tungstic acid compound is an aqueous solution of ammonium metatungstate. , At least one selected from an aqueous solution of ammonium paratungstate, an aqueous solution of ammonium tungstate, and an aqueous solution of phosphotungstic acid.

  The fifth invention of the present invention is characterized in that the heat treatment of the second step in the first to fourth inventions is performed at a heat treatment temperature of 100 to 900 ° C. in an oxygen atmosphere and a vacuum atmosphere. It is.

Sixth aspect of the present invention, the positive electrode active material for a non-aqueous electrolyte secondary battery, the general formula _{Li z Ni 1-x-y} Co x M y O 2 ( however, 0.10 ≦ x ≦ 0.35, Primary particles represented by 0 ≦ y ≦ 0.35, 0.97 ≦ z ≦ 1.20, and M is at least one element selected from Mn, V, Mg, Mo, Nb, Ti, and Al), And a layered or island-shaped lithium tungstate or a hydrate thereof on the surface of the primary particle of the lithium metal composite oxide powder composed of secondary particles formed by aggregation of the primary particles It is.

  In a seventh aspect of the present invention, the amount of tungsten contained in the lithium tungstate compound according to the sixth aspect is W relative to the total number of Ni, Co and M atoms contained in the lithium metal composite oxide powder. The number of atoms is 0.1 to 3.0 mol%.

Furthermore, according to an eighth aspect of the present invention, the form of lithium tungstate in the sixth and seventh aspects is Li ₂ WO ₄ , Li ₄ WO ₅ , Li ₆ WO ₆ , Li ₂ W ₄ O ₁₃ , Li _2. W ₂ O ₇ , Li ₆ W ₂ O ₉ , Li ₂ W ₂ O ₇ , Li ₂ W ₅ O ₁₆ , Li ₉ W ₁₉ O ₅₅ , Li ₃ W ₁₀ O ₃₀ , Li ₁₈ W ₅ O ₁₅ , or these It is present in at least one form selected from hydrates.

  According to a ninth aspect of the present invention, a non-aqueous electrolyte secondary battery has a positive electrode containing the positive electrode active material according to any one of the sixth to eighth aspects.

ADVANTAGE OF THE INVENTION According to this invention, when used for the positive electrode material of a battery, the positive electrode active material for nonaqueous electrolyte secondary batteries which can implement | achieve high output with a high capacity | capacitance is obtained.
Furthermore, the manufacturing method is easy and suitable for production on an industrial scale, and its industrial value is extremely large.

It is a schematic explanatory drawing of the measurement example of impedance evaluation, and the equivalent circuit used for analysis. It is a cross-sectional SEM photograph (observation magnification 5000 times) of the lithium metal complex oxide of this invention. It is a schematic sectional drawing of the coin-type battery 1 used for battery evaluation.

Hereinafter, after describing the positive electrode active material of the present invention, the non-aqueous electrolyte secondary battery using the production method and the positive electrode active material according to the present invention will be described.
(1) the positive electrode active material the positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention have the general formula _{Li z Ni 1-x-y} Co x M y O 2 ( however, 0.10 ≦ x ≦ 0.35, 0 ≦ y ≦ 0.35, 0.97 ≦ z ≦ 1.20, and M is at least one element selected from Mn, V, Mg, Mo, Nb, Ti and Al) The surface of the primary particles of the lithium metal composite oxide powder composed of secondary particles formed by agglomeration of the primary particles has layered or island-shaped lithium tungstate or a hydrate thereof. It is.

In the present invention, the general formula _{Li z Ni 1-x-y} Co x M y O 2 as the base material ((where, 0.10 ≦ x ≦ 0.35,0 ≦ y ≦ 0.35,0.97 ≦ z ≦ 1.20, where M is a lithium metal composite oxide represented by (at least one element selected from Mn, V, Mg, Mo, Nb, Ti, and Al). In addition, lithium tungstate or hydrates formed in layers or islands on the surface of primary particles of lithium metal composite oxide powder improve output characteristics while maintaining charge / discharge capacity. It is.

In general, when the surface of the positive electrode active material is completely covered with a different compound, the movement (intercalation) of lithium ions is greatly limited, resulting in a high capacity of the lithium nickel composite oxide. The advantages are erased.
On the other hand, in the present invention, lithium tungstate or a hydrate thereof (hereinafter sometimes referred to as surface formation) is formed on the surface of the primary particles of the lithium metal composite oxide powder. The formed material has a high lithium ion conductivity and has an effect of promoting the movement of lithium ions. Therefore, by forming the above compounds in the form of islands or extremely thin layers on the surface of the primary particles of the lithium metal composite oxide powder, a lithium ion conduction path is secured at the interface with the electrolyte, and the reaction resistance of the active material To improve the output characteristics.

When such a surface formed product has an island shape, the particle diameter is preferably 1 to 100 nm. When forming a layer, the thickness of the layer is desirably 1 to 30 nm.
If the particle diameter is less than 1 nm, the surface formation may not have sufficient lithium ion conductivity. Further, when the particle diameter exceeds 100 nm, the coverage with the surface-formed product is lowered, and the reaction resistance reduction effect may not be sufficiently obtained.
In the case of forming in a layered form, if the layer thickness is less than 1 nm, the lithium ion conductivity may not be sufficient, and if it exceeds 30 nm, the specific surface area of the whole particle is reduced, and the reaction area with the electrolyte is sufficient. The characteristics may deteriorate without being removed.
By forming such a shape of the surface formed product, the reaction resistance of the active material can be reduced while maintaining a high capacity, and the output characteristics can be sufficiently improved.

Furthermore, since the contact with the electrolytic solution occurs on the surface of the primary particles (hereinafter sometimes referred to as the primary particle surface), lithium tungstate or a hydrate thereof may be formed on the primary particle surface. is important.
Here, the primary particle surface in the present invention refers to the primary particle surface exposed on the outer surface of the secondary particle and the void in the vicinity of the inner surface of the secondary particle through which the electrolyte solution can penetrate through the outer surface of the secondary particle. It includes exposed primary particle surfaces. Furthermore, even a grain boundary between primary particles is included as long as the primary particles are not completely bonded and the electrolyte solution can penetrate.

  This contact with the electrolytic solution occurs not only on the outer surface of the secondary particles constituted by aggregation of primary particles, but also in the vicinity of the surface of the secondary particles and in the internal voids, and also on the incomplete grain boundaries. It is necessary to promote lithium ion migration by forming lithium tungstate or a hydrate thereof on the surface of the primary particles. Therefore, by forming lithium tungstate or a hydrate thereof on the primary particle surface, it becomes possible to further reduce the reaction resistance of the lithium metal composite oxide particles.

  Note that the lithium tungstate or its hydrate need not be completely formed on the entire surface of the primary particles, and may be in the form of islands scattered or partially formed in layers. It may be in a state. Even if the lithium metal composite oxide particles are scattered, the reaction resistance can be reduced if lithium tungstate or its hydrate is formed on the outer surfaces of the lithium metal composite oxide particles and the primary particle surfaces exposed on the internal voids. can get. In particular, a greater effect can be obtained if the particle diameter or the layer thickness is within the above range.

The property of the primary particle surface of such a lithium metal composite oxide powder can be judged by observing with a field emission scanning electron microscope, for example. For the positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention, lithium It has been confirmed that lithium tungstate or a hydrate thereof is formed on the primary particle surface of the powder made of the metal composite oxide.
On the other hand, when lithium tungstate or its hydrate is formed non-uniformly between lithium metal composite oxide powders, the movement of lithium ions between lithium metal composite oxide powders becomes non-uniform. A load is applied to the lithium metal composite oxide powder, which tends to deteriorate cycle characteristics and increase reaction resistance. Therefore, it is preferable that lithium tungstate or a hydrate thereof is uniformly formed between the lithium metal composite oxide powders.

The amount of tungsten contained in the lithium metal composite oxide formed with lithium tungstate or its hydrate is 0.1 to 0.1 with respect to the total number of Ni, Co and M atoms contained in the lithium metal composite oxide. It is preferable to set it as 3.0 atomic%. Thereby, it is possible to achieve both high charge / discharge capacity and output characteristics.
When the amount of tungsten is less than 0.1 atomic%, the effect of improving the output characteristics may not be sufficiently obtained. When the amount of tungsten exceeds 3.0 atomic%, the lithium tungstate formed or hydrate thereof is formed. As a result, the lithium conduction between the lithium metal composite oxide and the electrolyte may be inhibited, and the charge / discharge capacity may be reduced.

Tungstic acid lithium or hydrates thereof, but are not particularly _{limited, Li 2 WO 4, Li 4} WO 5, Li 6 WO 6, Li 2 W 4 O 13, Li 2 W 2 O 7, Li 6 At least selected from W ₂ O ₉ , Li ₂ W ₂ O ₇ , Li ₂ W ₅ O ₁₆ , Li ₉ W ₁₉ O ₅₅ , Li ₃ W ₁₀ O ₃₀ , Li ₁₈ W ₅ O ₁₅ or a hydrate thereof. One form is preferred. These forms of lithium tungstate or its hydrate have high lithium ion conductivity, and can sufficiently reduce the reaction resistance of the active material while maintaining a high capacity.

  Further, the total amount of lithium in the positive electrode active material is such that the ratio “Li / M” of the number of atoms of Ni, Co and Mo in the positive electrode active material (M) to the number of Li atoms is 0.95 to 1. 20 is preferable. When the Li / M is less than 0.95, the reaction resistance of the positive electrode in the non-aqueous electrolyte secondary battery using the obtained positive electrode active material increases, and the output of the battery decreases. On the other hand, if Li / M exceeds 1.20, the initial discharge capacity of the positive electrode active material is reduced and the reaction resistance of the positive electrode is also increased. Usually, surplus lithium is present on the surface of the lithium metal composite oxide, and during the heat treatment after mixing with the tungstate compound solution, lithium tungstate can be formed by the surplus lithium. “Li / M” By making the above range, sufficient lithium tungstate can be formed, and the effect of improving lithium ion conductivity can be obtained.

The positive electrode active material of the present invention has improved output characteristics by forming lithium tungstate or a hydrate thereof on the primary particle surface of the lithium metal composite oxide powder. The particle size and tap density as the positive electrode active material The powder characteristics such as may be within the range of a positive electrode active material usually used.
The effect of forming lithium tungstate or its hydrate on the primary particle surface of the lithium metal composite oxide powder is, for example, lithium cobalt composite oxide, lithium manganese composite oxide, lithium nickel cobalt manganese composite The present invention can be applied not only to powders such as oxides, but also to positive electrode active materials for lithium secondary batteries that are generally used as well as the positive electrode active materials listed in the present invention.

(2) Method for Producing Positive Electrode Active Material Hereinafter, the method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention will be described in detail for each step.
[First step]
The first step is a step of adding and mixing a tungstic acid compound solution to a lithium metal composite oxide powder composed of primary particles and secondary particles formed by aggregation of the primary particles.
By this step, the tungstic acid compound can be uniformly dispersed between the lithium metal composite oxide powders on the primary particle surfaces of the lithium metal composite oxide powder that can come into contact with the electrolytic solution.
The tungstic acid compound solution used is preferably an aqueous solution of a water-soluble tungstic acid compound, and is at least one selected from an aqueous solution of ammonium metatungstate, an aqueous solution of ammonium paratungstate, an aqueous solution of ammonium tungstate, and an aqueous solution of phosphotungstic acid. More preferred is an aqueous ammonium metatungstate solution.

The amount of tungsten contained in the tungstic acid compound solution is preferably 0.1 to 3.0 mol% with respect to the total number of nickel, cobalt and M atoms contained in the lithium metal composite oxide to be mixed.
Moreover, it is preferable that the tungsten concentration of a tungstic acid compound solution is 0.05-4 mol / L. If it is less than 0.05 mol / L, since the tungsten concentration is low and a large amount of solution is required, it is slurried when mixed with the lithium metal composite oxide. Slurry causes the elution of Li contained in the crystal structure of the lithium metal composite oxide, which leads to a decrease in battery characteristics. On the other hand, if the tungsten concentration exceeds 4 mol / L, the solution may be small and the tungstic acid compound may not be uniformly dispersed on the primary particle surface.

The amount of the tungstic acid compound solution to be mixed with the lithium metal composite oxide is 0.5 to 150 ml, preferably 2 to 150 ml, more preferably 3 to 100 ml, and still more preferably 100 g of the lithium metal composite oxide powder. What is necessary is just to set it as the liquid quantity which is 5-60 ml and can dissolve a tungstic acid compound. If the tungstic acid compound solution is less than 0.5 ml with respect to 100 g of the lithium metal composite oxide powder, the amount of the solution is small and the tungstic acid compound cannot be uniformly dispersed on the surface of the primary particles.
On the other hand, when the tungstic acid compound solution exceeds 150 ml, the amount of the solution becomes too large and becomes a slurry when mixed with the lithium metal composite oxide. When the slurry is formed, Li contained in the layered lattice of the lithium metal composite oxide is eluted, which causes a decrease in battery characteristics. Therefore, by setting the tungstic acid compound solution to 0.5 to 150 ml with respect to 100 g of the lithium metal composite oxide powder, the elution of Li contained in the layered lattice is suppressed and the tungstic acid compound is uniformly formed on the surface of the primary particles. Can be dispersed.

In the production method of the present invention, the change in the composition of the positive electrode active material obtained is only an increase in the amount of tungsten added as a tungstate compound solution from the composition of the lithium metal composite oxide as the base material. Therefore, the lithium-metal composite oxide as a base material used, from the viewpoint of high capacity and low reaction resistance, generally known type _{Li z Ni 1-x-y} Co x M y O 2 ( however, 0.10 ≦ x ≦ 0.35, 0 ≦ y ≦ 0.35, 0.97 ≦ z ≦ 1.20, M is at least one element selected from Mn, V, Mg, Mo, Nb, Ti, and Al) The lithium metal composite oxide represented is used.
In addition, increasing the contact area with the electrolytic solution is advantageous for improving the output characteristics. Therefore, the primary particles and the secondary particles are formed by agglomeration of the primary particles. It is preferable to use a lithium metal composite oxide powder having voids and grain boundaries that can penetrate.

  Next, a tungstic acid compound solution is added to the lithium metal composite oxide powder to disperse the tungstic acid compound on the surface of the powder particles. In order to make the dispersion uniform, methods such as mixing well after addition, spraying the tungstate compound solution while stirring the powder, spraying the tungstate compound solution while flowing the powder, etc. may be used. it can.

  In the case of dispersing by sufficient mixing, a general mixer can be used. For example, the lithium metal composite oxide powder and the tungstic acid compound solution may be sufficiently mixed using a shaker mixer, a Laedige mixer, a Julia mixer, a V blender, or the like. A fluidized bed coating apparatus can also be used. As a result, the tungstic acid compound can be uniformly dispersed on the primary particle surface of the lithium metal composite oxide powder.

Furthermore, in the production method of the present invention, in order to improve the battery capacity and safety of the positive electrode active material, the lithium metal composite oxide powder as a base material may be washed with water before the first step.
This washing with water may be performed by a known method and conditions as long as lithium is not excessively eluted from the lithium metal composite oxide powder and the battery characteristics are not deteriorated. In the case of washing with water, either the method of mixing with the tungstic acid compound solution after drying or the method of mixing with the tungstic acid compound solution without drying only by solid-liquid separation may be used. In this case, it is necessary to adjust the amount of the tungstic acid compound solution so that the elution of Li due to the slurrying can be suppressed.

[Second step]
The second step is a step of heat-treating the lithium metal composite oxide powder in which the tungstic acid compound solution is dispersed on the surface.
As a result, the reaction between the tungstic acid compound supplied from the tungstic acid compound solution and the lithium ions contained in the lithium metal composite oxide is promoted to form the surface formation on the primary particle surface of the lithium metal composite oxide powder. Can do. Moreover, although the surface formation immediately after heat processing is a lithium tungstate, it may become a thing containing a hydrate by subsequent water | moisture-content adsorption | suction.

The heat treatment method is not particularly limited, but in order to prevent deterioration of electrical characteristics when used as a positive electrode active material for a non-aqueous electrolyte secondary battery, 100 to 900, more preferably 800 ° C. in an oxygen atmosphere or a vacuum atmosphere. More preferably, heat treatment is preferably performed at a temperature of 750 ° C.
When the heat treatment temperature is less than 100 ° C., the evaporation of moisture is not sufficient, and the surface formed product may not be sufficiently formed. On the other hand, when the heat treatment temperature exceeds 900 ° C., primary particles of the lithium metal composite oxide are sintered and tungsten ions are excessively dissolved in the layered structure of the lithium metal composite oxide. The discharge capacity may decrease.
The atmosphere during the heat treatment is preferably an oxidizing atmosphere such as an oxygen atmosphere or a vacuum atmosphere in order to avoid a reaction with moisture or carbonic acid in the atmosphere.
The heat treatment time is not particularly limited, but it is preferably 5 to 15 hours in order to sufficiently evaporate the water in the solution to form the surface formation product.

(3) Non-aqueous electrolyte secondary battery The non-aqueous electrolyte secondary battery of the present invention includes a positive electrode, a negative electrode, a non-aqueous electrolyte solution, and the like, and includes the same components as those of a general non-aqueous electrolyte secondary battery. The embodiment described below is merely an example, and the nonaqueous electrolyte secondary battery of the present invention can be variously modified based on the knowledge of those skilled in the art based on the embodiment described in the present specification. It can be implemented in an improved form. Moreover, the use of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited.

(A) Positive electrode Using the positive electrode active material for a non-aqueous electrolyte secondary battery described above, for example, a positive electrode of a non-aqueous electrolyte secondary battery is produced as follows.
First, a powdered positive electrode active material, a conductive material, and a binder are mixed, and, if necessary, a target solvent such as activated carbon and viscosity adjustment is added and kneaded to prepare a positive electrode mixture paste.
Each mixing ratio in the positive electrode mixture paste is also an important factor for determining the performance of the non-aqueous electrolyte secondary battery. When the total mass of the solid content of the positive electrode mixture excluding the solvent is 100 parts by mass, the content of the positive electrode active material is 60 to 95 parts by mass in the same manner as the positive electrode of a general non-aqueous electrolyte secondary battery, and the conductive material It is desirable to set the content of 1 to 20 parts by mass and the content of the binder to 1 to 20 parts by mass.

  The obtained positive electrode mixture paste is applied to the surface of a current collector made of, for example, an aluminum foil and dried to disperse the solvent. If necessary, pressurization may be performed by a roll press or the like to increase the electrode density. In this way, a sheet-like positive electrode can be produced. The sheet-like positive electrode can be cut into an appropriate size or the like according to the target battery and used for battery production. However, the method for manufacturing the positive electrode is not limited to the illustrated one, and other methods may be used.

In producing the positive electrode, as the conductive agent, for example, graphite (natural graphite, artificial graphite, expanded graphite, etc.), carbon black materials such as acetylene black, ketjen black, and the like can be used.
The binder plays a role of anchoring the active material particles. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluorine rubber, ethylene propylene diene rubber, styrene butadiene, cellulosic resin, polyacrylic. An acid or the like can be used.
If necessary, a positive electrode active material, a conductive material, and activated carbon are dispersed, and a solvent that dissolves the binder is added to the positive electrode mixture. Specifically, an organic solvent such as N-methyl-2-pyrrolidone can be used as the solvent. Activated carbon can be added to the positive electrode mixture in order to increase the electric double layer capacity.

(B) Negative electrode A negative electrode mixture in which a negative electrode active material capable of occluding and desorbing lithium ions is mixed with a binder and an appropriate solvent is added to the negative electrode. Is applied to the surface of a metal foil current collector such as copper, dried, and compressed to increase the electrode density as necessary.

  As the negative electrode active material, for example, natural graphite, artificial graphite, a fired organic compound such as phenol resin, or a powdery carbon material such as coke can be used. In this case, as the negative electrode binder, a fluorine-containing resin such as PVDF can be used as in the case of the positive electrode, and as a solvent for dispersing these active materials and the binder, N-methyl-2-pyrrolidone or the like can be used. Organic solvents can be used.

(C) Separator A separator is interposed between the positive electrode and the negative electrode. The separator separates the positive electrode and the negative electrode and retains the electrolyte, and a thin film such as polyethylene or polypropylene and a film having many minute holes can be used.

(D) Non-aqueous electrolyte The non-aqueous electrolyte is obtained by dissolving a lithium salt as a supporting salt in an organic solvent.
Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate; chain carbonates such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, and dipropyl carbonate; and tetrahydrofuran, 2- One kind selected from ether compounds such as methyltetrahydrofuran and dimethoxyethane, sulfur compounds such as ethylmethylsulfone and butanesultone, phosphorus compounds such as triethyl phosphate and trioctyl phosphate, etc. are used alone or in admixture of two or more. be able to.
As the supporting salt, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiN (CF ₃ SO ₂ ) ₂ , or a composite salt thereof can be used.
Furthermore, the non-aqueous electrolyte solution may contain a radical scavenger, a surfactant, a flame retardant, and the like.

(E) Battery shape and configuration The shape of the non-aqueous electrolyte secondary battery of the present invention composed of the positive electrode, negative electrode, separator and non-aqueous electrolyte described above can be various, such as a cylindrical type and a laminated type. Can be.
In any case, the positive electrode and the negative electrode are laminated via a separator to form an electrode body, and the obtained electrode body is impregnated with a non-aqueous electrolyte and communicated with the positive electrode current collector and the outside. The positive electrode terminal and the negative electrode current collector and the negative electrode terminal communicating with the outside are connected using a current collecting lead or the like and sealed in a battery case to complete a non-aqueous electrolyte secondary battery. .

(F) Characteristics The nonaqueous electrolyte secondary battery using the positive electrode active material of the present invention has a high capacity and a high output.
The non-aqueous electrolyte secondary battery using the positive electrode active material according to the present invention obtained in a particularly preferred form is, for example, a high initial discharge capacity of 165 mAh / g or more and a low positive electrode when used for the positive electrode of a 2032 type coin battery. Resistance is obtained, and further, high capacity and high output. Moreover, it can be said that it has high thermal stability and is excellent in safety.

In addition, if the measuring method of the positive electrode resistance in this invention is illustrated, it will become as follows. When the frequency dependence of the battery reaction is measured by a general AC impedance method as an electrochemical evaluation method, the Nyquist diagram based on the solution resistance, the negative electrode resistance and the negative electrode capacity, and the positive electrode resistance and the positive electrode capacity is shown in FIG. Is obtained as follows.
The battery reaction at the electrode consists of a resistance component accompanying the charge transfer and a capacity component due to the electric double layer. When these are expressed as an electric circuit, it becomes a parallel circuit of resistance and capacity. It is represented by an equivalent circuit in which circuits are connected in series. Fitting calculation is performed on the Nyquist diagram measured using this equivalent circuit, and each resistance component and capacitance component can be estimated. The positive electrode resistance is equal to the diameter of the semicircle on the low frequency side of the obtained Nyquist diagram.

  From the above, the positive electrode resistance can be estimated by performing AC impedance measurement on the manufactured positive electrode and performing fitting calculation on the obtained Nyquist diagram with an equivalent circuit.

About the secondary battery which has a positive electrode using the positive electrode active material obtained by this invention, the performance (initial stage discharge capacity, positive electrode resistance) was measured.
Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

(Battery manufacture and evaluation)
For the evaluation of the positive electrode active material, a 2032 type coin battery 1 (hereinafter referred to as a coin type battery) shown in FIG. 3 was used.
As shown in FIG. 3, the coin battery 1 includes a case 2 and an electrode 3 accommodated in the case 2.
The case 2 has a positive electrode can 2a that is hollow and open at one end, and a negative electrode can 2b that is disposed in the opening of the positive electrode can 2a. When the negative electrode can 2b is disposed in the opening of the positive electrode can 2a, A space for accommodating the electrode 3 is formed between the negative electrode can 2b and the positive electrode can 2a.
The electrode 3 includes a positive electrode 3a, a separator 3c, and a negative electrode 3b, which are stacked in this order. The positive electrode 3a contacts the inner surface of the positive electrode can 2a, and the negative electrode 3b contacts the inner surface of the negative electrode can 2b. As shown in FIG.

  The case 2 includes a gasket 2c, and relative movement is fixed by the gasket 2c so as to maintain a non-contact state between the positive electrode can 2a and the negative electrode can 2b. Further, the gasket 2c also has a function of sealing a gap between the positive electrode can 2a and the negative electrode can 2b to block the inside and outside of the case 2 in an airtight and liquid tight manner.

The coin battery 1 shown in FIG. 3 was manufactured as follows.
First, 52.5 mg of a positive electrode active material for a non-aqueous electrolyte secondary battery, 15 mg of acetylene black, and 7.5 mg of polytetrafluoroethylene resin (PTFE) are mixed, and press-molded to a diameter of 11 mm and a thickness of 100 μm at a pressure of 100 MPa. A positive electrode 3a was produced. The produced positive electrode 3a was dried at 120 ° C. for 12 hours in a vacuum dryer.

Using the positive electrode 3a, the negative electrode 3b, the separator 3c, and the electrolytic solution, the coin-type battery 1 described above was produced in a glove box in an Ar atmosphere in which the dew point was controlled at −80 ° C.
As the negative electrode 3b, a negative electrode sheet in which graphite powder having an average particle diameter of about 20 μm punched into a disk shape with a diameter of 14 mm and polyvinylidene fluoride were applied to a copper foil was used.
As the separator 3c, a polyethylene porous film having a film thickness of 25 μm was used. As the electrolytic solution, an equivalent mixed solution (manufactured by Toyama Pharmaceutical Co., Ltd.) of ethylene carbonate (EC) and diethyl carbonate (DEC) using 1M LiClO ₄ as a supporting electrolyte was used.

The initial discharge capacity and positive electrode resistance showing the performance of the manufactured coin-type battery 1 were evaluated by the following methods.
The initial discharge capacity is left for about 24 hours after the coin-type battery 1 is manufactured, and after the open circuit voltage OCV (Open Circuit Voltage) is stabilized, the current density with respect to the positive electrode is set to 0.1 mA / cm ² and the cut-off voltage 4 The capacity when the battery was charged to 3 V, discharged after a pause of 1 hour to a cutoff voltage of 3.0 V was defined as the initial discharge capacity.

The positive electrode resistance was measured by the AC impedance method using a frequency response analyzer and a potento-galvanostat (manufactured by Solartron, 1255B) after charging the coin-type battery 1 at a charging potential of 4.1 V, and the Nyquist plot shown in FIG. Obtained. Since this Nyquist plot is represented as the sum of the solution resistance, the negative electrode resistance and its capacity, and the characteristic curve indicating the positive electrode resistance and its capacity, the fitting calculation was performed using an equivalent circuit based on this Nyquist plot, and the positive resistance The value of was calculated.
Note that, in this example, Wako Pure Chemical Industries, Ltd. reagent grade samples were used for the production of composite hydroxide, the production of the positive electrode active material, and the secondary battery.

A lithium metal composite represented by Li _1.060 Ni _0.76 Co _0.14 Al _0.03 O ₂ obtained by a known technique of mixing and baking oxide powder containing Ni as a main component and lithium hydroxide Oxide powder was used as a base material. The lithium metal composite oxide powder had an average particle size of 11 μm and a specific surface area of 0.3 m ² / g. In addition, the average particle diameter was evaluated using the volume integrated average value in the laser diffraction scattering method, and the specific surface area was evaluated using the BET method based on nitrogen gas adsorption.

To 50 g of lithium metal composite oxide powder used as a base material, 0.68 ml of ammonium metatungstate solution having a tungsten concentration of 3.88 mol / L in an ammonium metatungstate solution (MW-2, manufactured by Nippon Inorganic Chemical Industry Co., Ltd.) The mixture was further mixed well using Awatori Rentaro (Shinky Corp., ARE-250) to obtain a mixture of ammonium metatungstate solution and lithium metal composite oxide powder.
The obtained mixture was put in a magnesia baking vessel, heat-treated in a vacuum atmosphere at 200 ° C. for 14 hours, and then cooled to room temperature.
Finally, a positive active material having lithium tungstate on the primary particle surface was prepared by crushing through a sieve having an opening of 38 μm.

  When the tungsten content and Li / M of the positive electrode active material were analyzed by the ICP method, the tungsten content was 0.50 mol% and Li / M was 1.018. From this, it was confirmed that the mixture of the ammonium metatungstate solution and the lithium metal composite oxide powder and the composition after the heat treatment were equivalent.

[Battery evaluation]
Next, a coin-type battery 1 shown in FIG. 3 having a positive electrode using the positive electrode active material of Example 1 was produced, and its battery characteristics were evaluated. In addition, the positive electrode resistance used the relative value which set Example 1 as 100 as the evaluation value. The initial discharge capacity was 191.2 mAh / g.
Hereinafter, for Examples 2 to 11 and Comparative Example 1, only the substances and conditions changed from those in Example 1 are shown. Table 1 shows the initial discharge capacity and positive electrode resistance evaluation values of Examples 1 to 11 and Comparative Example 1.

  A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and the battery characteristics were evaluated in the same manner as in Example 1 except that the ammonium metatungstate solution used was changed to 1.36 ml. Table 1 shows the results. .

  A positive electrode active material for a nonaqueous electrolyte secondary battery is obtained in the same manner as in Example 1 except that the tungsten concentration in the used ammonium metatungstate solution is 0.78 mol / L and the addition amount is 3.40 ml. In addition, the battery characteristics were evaluated, and the results are shown in Table 1.

  A positive electrode active material for a nonaqueous electrolyte secondary battery is obtained in the same manner as in Example 1 except that the tungsten concentration in the ammonium metatungstate solution used is 0.10 mol / L and the addition amount is 26.4 ml. In addition, the battery characteristics were evaluated, and the results are shown in Table 1.

Lithium metal having a composition represented by Li _1.060 Ni _0.82 Co _0.15 Al _0.10 O ₂ as a base material, an average particle size of 5.0 μm, and a specific surface area of 0.9 m ² / g A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that the composite oxide powder was used, and the battery characteristics were evaluated. The results are shown in Table 1.

Lithium metal having a composition represented by Li _1.060 Ni _0.34 Co _0.33 Mn _0.33 O ₂ as a base material, an average particle diameter of 4.1 μm, and a specific surface area of 1.0 m ² / g A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that the composite oxide powder was used, and the battery characteristics were evaluated. The results are shown in Table 1.

  The non-aqueous electrolyte secondary battery was treated in the same manner as in Example 1 except that the heat treatment after mixing was performed in a 100% oxygen stream at a temperature rise of 2.8 ° C./min up to 700 ° C. and heat-treated for 10 hours. A positive electrode active material was obtained and the battery characteristics were evaluated. The results are shown in Table 1.

  Lithium metal composite oxide as a base material is stirred for 1 minute as a slurry of 1.5 g / cc concentration with pure water before mixing with the tungstic acid compound solution, solid-liquid separated, then vacuum dried at 200 ° C. and washed with water The positive electrode active material for non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that the battery characteristics were evaluated, and the results are shown in Table 1.

  A positive electrode active material for a nonaqueous electrolyte secondary battery was obtained and the battery characteristics were evaluated in the same manner as in Example 1 except that the ammonium metatungstate solution used was changed to 4.76 ml. The results are shown in Table 1. .

  A positive electrode active material for a nonaqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that the concentration of the ammonium metatungstate solution used was 0.04 mol / L and the addition amount was 129 ml. Evaluation was performed and the results are shown in Table 1.

  The non-aqueous electrolyte secondary battery was treated in the same manner as in Example 1 except that the heat treatment after mixing was performed in a 100% oxygen stream at a temperature increase of 2.8 ° C./minute up to 900 ° C. for 10 hours. A positive electrode active material was obtained and the battery characteristics were evaluated. The results are shown in Table 1.

(Comparative Example 1)
The lithium metal composite oxide used as a base material in Example 1 was used as Comparative Example 1 without forming lithium tungstate, and the battery characteristics were evaluated. The results are shown in Table 1.

(Conventional example)
Using a method similar to the example disclosed in Patent Document 4, nickel sulfate, cobalt sulfate, and sodium aluminate are dissolved in water, and a sodium hydroxide solution is added to the mixture while stirring sufficiently. The nickel-cobalt-aluminum composite coprecipitated hydroxide coprecipitate produced so that the molar ratio of Al to Al was Ni: Co: Al = 77: 20: 3 was washed with water and dried, and then lithium hydroxide was added. A precursor was prepared by adding a monohydrate salt and adjusting the molar ratio to be Li: (Ni + Co + Al) = 105: 100.

Next, these precursors were calcined at 700 ° C. for 10 hours in an oxygen stream, cooled to room temperature, and then pulverized to be represented by the composition formula Li _1.03 Ni _0.77 Co _0.20 Al _0.03 O ₂ . Composite oxide particles mainly composed of lithium nickelate were prepared.
This composite oxide particles 100 parts by weight of ammonium paratungstate and _{((NH 4) 10 W 12} O 41 · 5H 2 O), added 1.632 parts by weight, the mixture was thoroughly mixed in a mortar, oxygen stream After firing at 700 ° C. for 4 hours and cooling to room temperature, it was taken out and pulverized to produce a conventional positive electrode active material.

  The battery characteristics of the coin-type battery 1 shown in FIG. 3 having a positive electrode produced using the obtained positive electrode active material were evaluated. The results are shown in Table 1.

[Evaluation]
As is clear from Table 1, the composite hydroxide particles and positive electrode active materials of Examples 1 to 11 were manufactured according to the present invention, and therefore, the initial discharge capacity was higher and the positive electrode resistance was lower than that of the conventional example. Thus, the battery has excellent characteristics.
In particular, Examples 1 to 8, which were carried out under the preferable conditions of the added tungsten amount, the tungsten concentration of the tungstate compound solution, and the heat treatment temperature, had even better initial discharge capacity and positive electrode resistance, and positive electrode for non-aqueous electrolyte secondary battery. It is more suitable as an active material.

FIG. 2 shows an example of the result of cross-sectional SEM observation (magnification: 5,000 times) of the positive electrode active material obtained in the example of the present invention. In the obtained positive electrode active material, primary particles and primary particles are aggregated. From the results of X-ray diffraction analysis, it was confirmed that island-shaped or layered lithium tungstate (Li ₄ WO ₅ ) as indicated by “arrows” was formed on the primary particle surface. confirmed.

In Example 9 where the amount of added tungsten is large, the amount of lithium tungstate compound formed is large. For this reason, compared with Examples 1-8, initial stage discharge capacity falls and positive electrode resistance is high.
In Example 10, although the addition amount is within the range of the present invention, the concentration of the ammonium metatungstate solution is low, so the amount of liquid used is large, and it is considered that lithium in the lithium metal composite oxide was eluted. Compared with 1-8, the positive electrode resistance is higher.
Moreover, in Example 11, since the heat treatment temperature after mixing the tungstate compound solution and the lithium metal composite oxide was as high as 900 ° C., it is considered that tungsten was dissolved in the nickel site of the layered structure of the positive electrode active material. The discharge capacity and the positive electrode resistance are lower than those in Examples 1-8.

In Comparative Example 1, since the fine particles containing W and Li according to the present invention are not formed on the surface of the primary particles, the positive electrode resistance is significantly high, and it is difficult to meet the demand for higher output.
Since the conventional example was mixed with a solid tungsten compound, the dispersion of W was not sufficient and the supply of Li into the fine particles was not achieved, resulting in a significantly high positive electrode resistance.

  From the above results, it can be confirmed that the nonaqueous electrolyte secondary battery using the positive electrode active material of the present invention has a high initial discharge capacity and a low positive electrode resistance, and is a battery having excellent characteristics.

  The non-aqueous electrolyte secondary battery of the present invention is suitable for a power source of a small portable electronic device (such as a notebook personal computer or a mobile phone terminal) that always requires a high capacity, and an electric vehicle battery that requires a high output. Also suitable.

  In addition, the nonaqueous electrolyte secondary battery of the present invention has excellent safety, and can be downsized and increased in output, and thus is suitable as a power source for an electric vehicle subject to restrictions on mounting space. The present invention can be used not only as a power source for an electric vehicle driven purely by electric energy but also as a power source for a so-called hybrid vehicle used in combination with a combustion engine such as a gasoline engine or a diesel engine.

DESCRIPTION OF SYMBOLS 1 Coin type battery 2 Case 2a Positive electrode can 2b Negative electrode can 2c Gasket 3 Electrode 3a Positive electrode 3b Negative electrode 3c Separator

Claims (11)

Formula _{Li z Ni 1-x-y} Co x M y O 2 ( however, 0.10 ≦ x ≦ 0.35,0 ≦ y ≦ 0.35,0.97 ≦ z ≦ 1.20, M is Lithium metal composite oxide powder comprising primary particles represented by (Mn, V, Mg, Mo, Nb, Ti and Al) and secondary particles formed by aggregation of the primary particles First step of dispersing the tungstic acid compound on the surface of the primary particles of the lithium metal composite oxide powder by adding and mixing the tungstic acid compound solution,
The lithium metal composite oxide powder in which the tungstic acid compound is dispersed has a second step of heat-treating and forming lithium tungstate on the surface of the primary particles of the lithium metal composite oxide powder. A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery.   The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, further comprising a step of washing the lithium metal composite oxide powder with water before performing the first step.   The amount of tungsten contained in the tungstic acid compound solution is 0.1 to 3.0 mol% with respect to the total number of Ni, Co and M atoms contained in the lithium metal composite oxide powder to be mixed. The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries of Claim 1 or 2 characterized by the above-mentioned.   4. The production of a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the tungsten concentration in the tungstic acid compound solution is 0.05 to 4 mol / L. 5. Method.   The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein the tungstic acid compound solution is an aqueous solution of a water-soluble tungstic acid compound.   6. The aqueous solution of the water-soluble tungstic acid compound is at least one selected from an aqueous solution of ammonium metatungstate, an aqueous solution of ammonium paratungstate, an aqueous solution of ammonium tungstate, and an aqueous solution of phosphotungstic acid. The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries of any one of these.   The non-aqueous electrolyte 2 according to any one of claims 1 to 6, wherein the heat treatment in the second step is performed at a heat treatment temperature of 100 to 900 ° C in an oxygen atmosphere or a vacuum atmosphere. A method for producing a positive electrode active material for a secondary battery. Formula _{Li z Ni 1-x-y} Co x M y O 2 ( however, 0.10 ≦ x ≦ 0.35,0 ≦ y ≦ 0.35,0.97 ≦ z ≦ 1.20, M is A lithium metal composite oxide comprising primary particles represented by at least one element selected from Mn, V, Mg, Mo, Nb, Ti and Al) and secondary particles formed by aggregation of the primary particles. There,
A positive electrode active material for a non-aqueous electrolyte secondary battery comprising a layered or island-shaped lithium tungstate compound or a hydrate thereof on the surface of primary particles of the lithium metal composite oxide.   The amount of tungsten contained in the lithium tungstate compound is 0.1 to 3.0 mol% of W atoms with respect to the total number of Ni, Co and M atoms contained in the lithium metal composite oxide. The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 8. The lithium tungstate is Li ₂ WO ₄ , Li ₄ WO ₅ , Li ₆ WO ₆ , Li ₂ W ₄ O ₁₃ , Li ₂ W ₂ O ₇ , Li ₆ W ₂ O ₉ , Li ₂ W ₂ O ₇ , Li _The present invention exists in at least one form selected from ₂ W ₅ O ₁₆ , Li ₉ W ₁₉ O ₅₅ , Li ₃ W ₁₀ O ₃₀ , Li ₁₈ W ₅ O ₁₅ or a hydrate thereof. The positive electrode active material for non-aqueous electrolyte secondary batteries according to 8 or 9.   It has a positive electrode containing the positive electrode active material for nonaqueous electrolyte secondary batteries of any one of Claims 8-10, The nonaqueous electrolyte secondary battery characterized by the above-mentioned.