JP5811383B2 - Positive electrode active material for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery using the positive electrode active material - Google Patents

Description

  The present invention relates to a transition metal composite hydroxide that is a precursor of a positive electrode active material for a nonaqueous electrolyte secondary battery, a method for producing the same, a positive electrode active material for the nonaqueous electrolyte secondary battery, a method for producing the same, and the positive electrode active material. The present invention relates to a non-aqueous electrolyte secondary battery using a substance.

  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-power secondary battery is strongly desired as a battery for a motor drive power supply, particularly a power supply for transportation equipment.

As such a secondary battery, there is a lithium ion secondary battery.
A lithium ion secondary battery includes a negative electrode, a positive electrode, an electrolyte, and the like, and a material capable of desorbing and inserting lithium is used as an active material for the negative electrode and the positive electrode.
Such lithium ion secondary batteries are currently being actively researched and developed. Among them, lithium ion secondary batteries using a layered or spinel type lithium metal composite oxide as a positive electrode material are among them. Since a high voltage of 4V class can be obtained, practical use is progressing as a battery having a high energy density.

As materials mainly proposed so far, lithium-cobalt composite oxide (LiCoO ₂ ) that is relatively easy to synthesize, lithium-nickel composite oxide (LiNiO ₂ ) using nickel cheaper than cobalt, Examples thereof include lithium / nickel / cobalt / manganese composite oxide (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ), lithium / manganese composite oxide (LiMn ₂ O ₄ ) using manganese, and the like.
Among these, lithium / nickel / cobalt / manganese composite oxides are attracting attention as materials that have good cycle characteristics and can take out high output with low resistance.

In order to obtain the good performance, it is required to use a lithium composite oxide having a uniform particle size as the positive electrode active material.
This is because, when a complex oxide with a wide particle size distribution is used, the voltage applied to the particles in the electrode becomes non-uniform, and when charging and discharging are repeated, the fine particles are selectively deteriorated and cycle deterioration is likely to occur. This is because a defect occurs. Therefore, in order to improve the performance of the positive electrode material, it is important to manufacture the lithium composite oxide that is the positive electrode active material so that the particles have a small particle size and a uniform particle size.
That is, since lithium composite oxide is usually manufactured from composite hydroxide, the positive electrode material is used to improve the performance of the positive electrode material and to produce a high-performance lithium ion secondary battery as the final product. It is necessary to use a composite hydroxide composed of particles having a small particle size and a narrow particle size distribution as a composite hydroxide that is a raw material of the lithium composite oxide to be formed.

Regarding the particle size distribution of the lithium composite oxide, for example, in Patent Document 1, in the particle size distribution curve, the average particle size D ₅₀ which means a particle size having a cumulative frequency of 50% is 3 to 15 μm, and the minimum particle size is D ₁₀ / D ₅₀ is a particle having a particle size distribution of 0.5 μm or more and a maximum particle size of 50 μm or less, and a cumulative frequency of D ₁₀ of 90% and D _{90 of} 90%. A lithium composite oxide having 60 to 0.90 and D ₁₀ / D ₉₀ of 0.30 to 0.70 is disclosed. Since this lithium composite oxide has high filling properties, is excellent in charge / discharge capacity characteristics and high output characteristics, and is difficult to deteriorate even under conditions with a large charge / discharge load, this lithium composite oxide can be used. For example, there is a description that a lithium ion non-aqueous electrolyte secondary battery having excellent output characteristics and little deterioration in cycle characteristics can be obtained.

However, the lithium composite oxide disclosed in Patent Document 1 has a minimum particle size of 0.5 μm or more and a maximum particle size of 50 μm or less with respect to an average particle size of 3 to 15 μm. Coarse particles are included.
Then, the particle size distribution defined above _D 10 _{/ D 50} and _D 10 _{/ D 90,} it can not be said that a narrow range of particle size distribution.
That is, the lithium composite oxide of Patent Document 1 cannot be said to be a particle having sufficiently high particle size uniformity, and even if such a lithium composite oxide is employed, improvement in the performance of the positive electrode material cannot be expected. It is difficult to obtain a lithium ion non-aqueous electrolyte secondary battery having performance.

A proposal has also been made for a method for producing a composite hydroxide, which is a raw material for a composite oxide, for the purpose of improving the particle size distribution.
In Patent Document 2, in a method for producing a positive electrode active material for a non-aqueous electrolyte battery, an aqueous solution containing two or more transition metal salts, or two or more aqueous solutions of different transition metal salts and an alkaline solution are simultaneously used in a reaction vessel. There has been proposed a method of obtaining a precursor hydroxide or oxide by adding and coprecipitating with a reducing agent coexisting or aerated inert gas.

  However, since the technique of Patent Document 2 collects the generated crystals while classifying them, it is considered that manufacturing conditions must be strictly controlled in order to obtain a product having a uniform particle size. Industrial scale production is difficult. Moreover, it is difficult to obtain small-sized particles even though large-sized crystal particles can be obtained.

Furthermore, recently, various elements have been added to further improve the performance. Tungsten has the effect of lowering the reaction resistance, and can be expected to increase the output.
For example, in Patent Document 3, 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 a combination thereof A positive electrode active material coated with an intermetallic compound and / or oxide obtained by the above is 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.

  Further, in Patent Document 4, 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 primary particles and aggregates thereof. A non-aqueous electrolyte having a compound comprising at least one selected from the group consisting of molybdenum, vanadium, tungsten, boron and fluorine, present in the form of particles comprising one or both of secondary particles A positive electrode active material for secondary batteries has been proposed.

  As a result, 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, the surface of the particle is composed of molybdenum, vanadium, tungsten, boron and fluorine. 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.

JP 2008-147068 A JP 2003-86182 A Japanese Patent Laid-Open No. 11-16666 JP-A-2005-251716

In view of the problems, the present invention has an object to provide a transition metal composite hydroxide that, when used as a precursor, has a small particle size, high particle size uniformity, and provides a lithium transition metal composite oxide.
In addition to the positive electrode active material for a non-aqueous secondary battery that can reduce the value of the positive electrode resistance measured when used in a battery, the high capacity and thermal safety using the positive electrode active material is high. An object of the present invention is to provide a non-aqueous electrolyte secondary battery that can provide output.
It is another object of the present invention to provide an industrial method for producing a transition metal composite hydroxide and a positive electrode active material according to the present invention.

  As a result of intensive studies on lithium transition metal composite oxides that can exhibit excellent battery characteristics when used as a positive electrode material of a lithium ion secondary battery, the present inventors have found that a nucleation stage is achieved by pH control during crystallization. It was found that the particle size distribution of the transition metal composite hydroxide can be controlled by separating it at the particle growth stage. Further, by holding the crystallized substance in a slurry in which at least a tungsten compound is dissolved and controlling the pH, a composite hydroxide having a tungsten coating formed on the particle surface can be obtained, and the composite hydroxide is precursor. The knowledge that a positive electrode active material capable of realizing high capacity and high output of a battery can be obtained by using as a body. The present invention has been completed based on these findings.

The first aspect of the present invention have the general formula _{(2): Li 1 + u} M x W s A t O 2 (-0.05 ≦ u ≦ 0.50, x + s + t = 1,0 <s ≦ 0.05,0 <S + t ≦ 0.15, M is a transition metal including one or more selected from Ni, Co, and Mn, A is at least one selected from transition metal elements other than M and W, Group 2, Elements, or Group 13 elements A positive electrode active material for a non-aqueous electrolyte secondary battery comprising a hexagonal crystal structure having a layered structure and having an average particle size of 3 to 6 μm A positive electrode active material for a non-aqueous electrolyte secondary battery, wherein [(d ₉₀ -d ₁₀ ) / average particle size] of an index indicating the spread of the particle size distribution is 0.60 or less.

According to a second aspect of the present invention, the specific surface area of the positive electrode active material for a non-aqueous electrolyte secondary battery in the first aspect is 0.5 to 2.0 m ² / g. It is a positive electrode active material for secondary batteries.

  According to a third aspect of the present invention, the additive element in the first and second aspects is one selected from B, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, and Mo. In the positive electrode active material for a non-aqueous electrolyte secondary battery characterized by the above, it is more preferable that in the fourth invention, the additive element in the third invention contains at least Al.

  The fifth invention of the present invention is characterized in that M in the general formula (2) in the first to fourth inventions contains at least Ni and Co, and the sixth invention provides the first to fourth inventions. M of the general formula (2) in the invention is a positive electrode active material for a non-aqueous electrolyte secondary battery, characterized in that it contains at least Ni and Mn.

  According to a seventh aspect of the present invention, the positive electrode for a non-aqueous electrolyte secondary battery is characterized in that s + t in the general formula (2) in the first to sixth aspects is 0.02 <s + t ≦ 0.15 It is an active material.

  An eighth invention of the present invention is a nonaqueous electrolyte secondary battery characterized in that a positive electrode is formed by the positive electrode active material for a nonaqueous electrolyte secondary battery in the first to seventh inventions.

  According to the present invention, a monodisperse transition metal composite hydroxide having a small particle size and a narrow particle size distribution is obtained, and lithium transition metal composite oxidation obtained when the obtained transition metal composite hydroxide is used as a precursor. The positive electrode active material comprising a non-aqueous secondary battery is capable of increasing the capacity, stabilizing the heat, and increasing the output of the non-aqueous secondary battery. The non-aqueous secondary battery includes a positive electrode including the positive electrode active material. Is provided with excellent battery characteristics.

  The methods for producing the transition metal composite hydroxide and the positive electrode active material according to the present invention are both easy and suitable for large-scale production, and their industrial value is extremely large.

It is a schematic flowchart of the process of manufacturing the transition metal composite hydroxide of this invention. It is a schematic flowchart of the other process which manufactures the transition metal composite hydroxide of this invention. It is a schematic flowchart of the process of manufacturing lithium transition metal complex oxide from the transition metal complex hydroxide of this invention. It is a schematic flowchart after manufacturing the transition metal composite hydroxide of this invention until manufacturing a nonaqueous electrolyte secondary battery. It is a schematic sectional drawing of the coin-type battery B used for battery evaluation. It is the equivalent circuit used for the measurement example and analysis of alternating current impedance evaluation. It is a FE-SEM photograph (observation magnification 1000 times) of the lithium transition metal composite hydroxide (positive electrode active material) of the present invention.

The present invention relates to the following inventions.
1. A transition metal composite hydroxide serving as a precursor of a positive electrode active material for a non-aqueous electrolyte secondary battery and a method for producing the same.
2. A positive electrode active material for a non-aqueous electrolyte secondary battery using the transition metal composite hydroxide described in 1 above and a method for producing the same.
3. A non-aqueous electrolyte secondary battery using the positive electrode active material described in 2 above.

  The inventions 1 to 3 will be described in detail below. (1) After explaining the transition metal composite hydroxide and its production method, (2) a non-aqueous system using the transition metal composite hydroxide as a precursor A positive electrode active material for an electrolyte secondary battery and a manufacturing method thereof, and (3) a non-aqueous electrolyte secondary battery as a final product will be described.

1-1. Transition metal complex hydroxide transition metal composite hydroxide of the present invention (hereinafter, simply referred to as composite hydroxide of the present invention), the general formula _{(1): M x W s} A t (OH) 2 + α (x + s + t = 1 0 <s ≦ 0.05, 0 <s + t ≦ 0.15, 0 ≦ α ≦ 0.5, M is a transition metal containing one or more selected from Ni, Co, and Mn, A is other than M and W And at least one additional element selected from the group consisting of a transition metal element, a group 2 element, and a group 13 element, and a substantially spherical secondary particle formed by agglomerating a plurality of primary particles. The particles have an average particle diameter of 3 to 7 μm, and [(d ₉₀ −d ₁₀ ) / average particle diameter], which is an index indicating the spread of the particle size distribution, is 0.55 or less, and metal oxides of tungsten and additive elements Alternatively, a coating containing a metal hydroxide is formed on the surface.
The composite hydroxide of the present invention is particularly suitable as a precursor for the positive electrode active material of the present invention.
Below, it demonstrates on the assumption that it uses for the precursor of the positive electrode active material of this invention.

[Particle structure]
The composite hydroxide of the present invention is adjusted so as to be composed of substantially spherical particles, specifically, substantially spherical secondary particles formed by aggregation of a plurality of primary particles. With such a structure, in the sintering process for forming the positive electrode active material of the present invention, lithium is sufficiently diffused into the particles, and a good positive electrode active material with uniform lithium distribution is formed. The

Furthermore, it is more preferable if the primary particles are aggregated in a random direction to form secondary particles.
Since the primary particles aggregate in a random direction, voids are generated almost uniformly between the primary particles. Therefore, when the secondary particles are mixed with the lithium compound and fired, the molten lithium compound spreads into the secondary particles, Lithium is fully diffused.

[Particle size distribution]
The composite hydroxide of the present invention is adjusted so that [(d ₉₀ -d ₁₀ ) / average particle size], which is an index indicating the spread of the particle size distribution, is 0.55 or less.
Since the particle size distribution of the positive electrode active material is strongly influenced by the composite hydroxide as a raw material, if fine particles or coarse particles are mixed in the composite hydroxide, the same particle may be present in the positive electrode active material. become.
That is, when [(d ₉₀ −d ₁₀ ) / average particle size] exceeds 0.55 and the particle size distribution is wide, fine particles or coarse particles also exist in the positive electrode active material.

In addition, when a positive electrode is formed using a positive electrode active material in which a large amount of fine particles are present, heat may be generated due to a local reaction of the fine particles, which reduces safety and selectively deteriorates the fine particles. As a result, the cycle characteristics deteriorate.
On the other hand, when a positive electrode is formed using a positive electrode active material having a large number of large-diameter particles, a sufficient reaction area between the electrolytic solution and the positive electrode active material cannot be obtained, and the battery output decreases due to an increase in reaction resistance.
If the index [(d ₉₀ -d ₁₀ ) / average particle size] is adjusted to 0.55 or less in the composite hydroxide of the present invention, the composite hydroxide of the present invention can be obtained as a raw material. The positive electrode active material to be obtained also has a narrow particle size distribution range and can be made uniform in particle size.
That is, the particle size distribution of the obtained positive electrode active material can be such that the index [(d ₉₀ -d ₁₀ ) / average particle size] is 0.6 or less. Thus, a battery having an electrode formed of a positive electrode active material obtained using the composite hydroxide of the present invention as a raw material has good cycle characteristics and output.

Here, it is possible to classify the composite hydroxide particles having a wide normal distribution to obtain a composite hydroxide having a narrow particle size distribution, but with an average particle size such as the composite hydroxide particles of the present invention, There is no usable sieve, and classification by sieving is difficult. In addition, even with an apparatus such as a wet cyclone, it cannot be classified into a sufficiently narrow particle size distribution, and it is difficult to obtain a composite hydroxide having a uniform particle size and a narrow particle size distribution by an industrial classification method. It is.
As an example, using a cylindrical reaction vessel equipped with a stirrer and an overflow pipe, the pH is controlled to 11.5 to 12.0 while adding a mixed aqueous solution of nickel sulfate and cobalt sulfate and aqueous ammonia to the reaction vessel. After the inside became a steady state, composite hydroxide particles having a composition of Ni _0.85 Co _0.15 (OH) ₂ were continuously collected from the overflow pipe. The obtained composite hydroxide particles were wet cyclone (Hydrocyclone, manufactured by Nippon Chemical Machinery Co., Ltd., NHC-1), the supply pressure was increased to remove the coarse powder, and then the supply pressure was decreased again. Although the fine particles were removed, only composite hydroxide particles having an average particle size of 6.5 and [(d ₉₀ -d ₁₀ ) / average particle size] of 0.65 were obtained.

In the index [(d ₉₀ −d ₁₀ ) / average particle size] indicating the spread of the particle size distribution, d ₁₀ is the number of particles in each particle size accumulated from the smaller particle size side, and the accumulated volume is the total particle size. Means a particle size of 10% of the total volume of D ₉₀ means the particle size in which the number of particles is similarly accumulated and the accumulated volume is 90% of the total volume of all particles.
The method for obtaining the average particle diameter (d ₅₀ ), d ₉₀ , and d ₁₀ is not particularly limited, and for example, it can be obtained from the volume integrated value measured with a laser light diffraction / scattering particle size analyzer.

[Average particle size]
The composite hydroxide of the present invention has an average particle size adjusted to 3 to 7 μm.
By controlling the average particle size to 3 to 7 μm, the positive electrode active material formed using the composite hydroxide of the present invention as a precursor can also be adjusted to a predetermined average particle size (3 to 8 μm). A desired positive electrode active material can be formed.

Here, when the average particle size of the composite hydroxide is less than 3 μm, the average particle size of the formed positive electrode active material is also reduced, the packing density of the positive electrode is lowered, and the battery capacity per volume is lowered. Moreover, the specific surface area may become too large. Conversely, when the average particle size of the composite hydroxide exceeds 7 μm, the specific surface area of the positive electrode active material decreases and the interface with the electrolytic solution decreases, thereby increasing the resistance of the positive electrode and increasing the output characteristics of the battery. Invite the decline.
Therefore, the composite hydroxide of the present invention has an average particle size adjusted to 3 to 7 μm, and the positive electrode active material of the present invention can be formed using the adjusted composite hydroxide as a raw material. When a positive electrode using a substance is used for a battery, excellent battery characteristics can be obtained.

[Specific surface area]
The composite hydroxide of the present invention has a specific surface area adjusted to 5 to 30 m ² / g.
By controlling the specific surface area to 5 to 30 m ² / g, the specific surface area of the positive electrode active material formed using the composite hydroxide of the present invention as a precursor is within a predetermined range (0.5 to 2.0 m ² / g). ) Can be adjusted.

Here, when the specific surface area of the composite hydroxide is less than 5 m ² / g, the specific surface area of the formed positive electrode active material is also reduced, and the output characteristics of the battery may be deteriorated. In firing after mixing, the reaction may not sufficiently proceed.
On the other hand, if the specific surface area of the composite hydroxide exceeds 30 m ² / g, the specific surface area of the positive electrode active material becomes too large, and the thermal stability of the positive electrode active material may be reduced. Sintering proceeds and coarse particles may be formed.

[Composition of composite hydroxide]
The composite hydroxide of the present invention is adjusted so that its composition is represented by the following general formula (1).
With this composition, if this composite hydroxide is used as a precursor to produce a lithium transition metal composite oxide, measurement is performed when an electrode using this lithium transition metal composite oxide as a positive electrode active material is used in a battery. The value of the positive electrode resistance can be lowered, and the output characteristics of the battery can be improved.

  The composite hydroxide of the present invention can have a composition that can be a precursor of a lithium transition metal composite oxide, and is specifically represented by the following general formulas (1-1) and (1-2). It is preferable to use a composite hydroxide.

  Moreover, when a positive electrode active material is obtained using this composite hydroxide as a precursor, the composition ratio of the composite hydroxide is also maintained in the positive electrode active material. Therefore, the composition ratio of the composite hydroxide of the present invention is adjusted to be the same as that of the positive electrode active material to be obtained.

[Particle structure]
In the composite hydroxide of the present invention, a coating containing tungsten and an additive element metal oxide or metal hydroxide is formed on the surface of the particle.
Thereby, tungsten and an additive element can be uniformly contained in the positive electrode active material. For the purpose of containing tungsten and additive elements in the positive electrode active material, it is only necessary to partially form a coating on the surface of the composite hydroxide particles, but tungsten and additive elements between the individual particles of the positive electrode active material. In order to suppress fluctuations in the content of, it is preferable to form a thin coating layer by uniformly depositing a coating on the surface of the composite hydroxide particles.

Furthermore, when the total amount of tungsten and the additive element is small, a coating layer is formed as a metal oxide or metal hydroxide in which the transition metal contained as M in the general formula (1) and tungsten and the additive element are mixed. Also good.
Thereby, even if it is a small amount of tungsten and an additive element, the content can be uniformly controlled between individual particles.

  In addition, when aluminum is selected as the additive element in order to enhance the thermal stability, the coating is preferably a mixture containing tungsten oxide hydrate and aluminum hydroxide. Thereby, the output characteristics and thermal stability of the battery can be sufficiently improved by the synergistic effect of tungsten and aluminum.

1-2. Method for Producing Transition Metal Composite Hydroxide The composite hydroxide of the present invention having the above characteristics is produced by the following method.
The method for producing a composite hydroxide of the present invention is a method for producing a transition metal composite hydroxide particle obtained by crystallization reaction by forming a coating containing tungsten and an additive element on the surface,
(A-1) a nucleation stage for nucleation;
(A-2) (A) a composite hydroxide particle production process including a particle growth stage for growing nuclei generated in the nucleation stage;
(B) A coating step of forming a coating containing tungsten and the metal oxide or metal hydroxide of the additive element on the surface of the composite hydroxide particle.

That is, in the conventional continuous crystallization method, since the nucleation reaction and the particle growth reaction proceed at the same time in the same tank, the particle size distribution becomes wide. On the other hand, the method for producing a composite hydroxide of the present invention has a narrow particle size distribution by clearly separating mainly the time during which the nucleation reaction occurs (nucleation process) and the time during which the particle growth reaction mainly occurs (particle growth process). Is what you get.
Further, the composite hydroxide particles obtained in the above-described particle production process are characterized in that a coating containing tungsten and an additive element metal oxide or metal hydroxide is uniformly formed on the surface.

  First, an outline of the method for producing a composite hydroxide of the present invention will be described with reference to FIG. 1 and 2, the nucleation stage (A-1) and the particle growth stage (A-2) are combined to correspond to the (A) composite hydroxide particle production process.

(A) Composite hydroxide particle manufacturing process (A-1) Nucleation stage As shown in FIG. 1, first, a plurality of metal compounds containing a transition metal containing one or more selected from Ni, Co, and Mn Is dissolved in water at a predetermined ratio to prepare a mixed aqueous solution. In the method for producing a composite hydroxide of the present invention, the composition ratio of each metal in the obtained composite hydroxide particles is determined by the ratio of each metal in the mixed aqueous solution. The composition ratio is the same. Therefore, the ratio of the metal compound dissolved in water is adjusted so that the composition ratio of each metal in the mixed aqueous solution is the same as the composition ratio of each metal in the composite hydroxide of the present invention. A mixed aqueous solution is prepared.

On the other hand, an alkaline aqueous solution such as a sodium hydroxide aqueous solution, an ammonia aqueous solution containing an ammonium ion supplier, and water are supplied to the reaction tank and mixed to form an aqueous solution.
This aqueous solution (hereinafter referred to as pre-reaction aqueous solution) is adjusted so that the pH value of the aqueous solution is in the range of 12.0 to 14.0 based on the liquid temperature of 25 ° C. by adjusting the supply amount of the alkaline aqueous solution. In addition, the concentration of ammonium ions in the aqueous solution before reaction is adjusted to 3 to 25 g / L. Furthermore, it adjusts so that the temperature of the aqueous solution before reaction may be 20-60 degreeC. The pH value of the aqueous solution in the reaction tank and the concentration of ammonium ions are measured with a general pH meter and ion meter, respectively.

And if the temperature and pH value of aqueous solution before reaction are adjusted, mixed aqueous solution will be supplied in a reaction tank, stirring aqueous solution before reaction. As a result, an aqueous solution in which the pre-reaction aqueous solution and the mixed aqueous solution are mixed (hereinafter referred to as reaction aqueous solution) is formed in the reaction tank, and fine nuclei of the composite hydroxide particles of the present invention are generated in the reaction aqueous solution. Can be made. At this time, since the pH value of the reaction aqueous solution is in the above range, the produced nuclei hardly grow and the production of nuclei takes place preferentially.
In addition, since the pH value and ammonium ion concentration of the reaction aqueous solution change with the nucleation due to the supply of the mixed aqueous solution, an alkaline aqueous solution and an aqueous ammonia solution are supplied to the reaction aqueous solution together with the mixed aqueous solution. The pH value and the ammonium ion concentration are controlled to maintain predetermined values.

Thus, by supplying the mixed aqueous solution, the alkaline aqueous solution, and the aqueous ammonia solution to the reaction aqueous solution, new nuclei are continuously generated in the reaction aqueous solution. Then, when a predetermined amount of nuclei is generated in the reaction aqueous solution, the nucleation step is finished. Whether or not a predetermined amount of nuclei has been generated is determined by the amount of metal salt added to the aqueous reaction solution.
The reaction aqueous solution, that is, the aqueous solution mixed with the mixed aqueous solution, the alkaline aqueous solution and the aqueous ammonia solution, which is adjusted to have a pH in the range of 12.0 to 14.0, is nucleated in the claims. Aqueous solution.

(A-2) Particle growth stage After the completion of the nucleation stage, the pH value of the reaction aqueous solution is adjusted to a value lower than the pH value in the nucleation stage in the range of pH 10.5 to 12.0 on the basis of the liquid temperature of 25 ° C. Specifically, the pH value of the aqueous reaction solution is controlled by adjusting the supply amount of the aqueous alkaline solution.
By setting the pH value of the reaction aqueous solution within the above range, the nucleus growth reaction takes precedence over the nucleus formation reaction, so that almost no new nuclei are formed in the reaction aqueous solution, and the nuclei grow. Thus, the composite hydroxide particles of the present invention having a predetermined particle diameter are formed.

Thereafter, when the composite hydroxide particles have grown to a predetermined particle size, the particle growth stage is terminated. The particle size of the composite hydroxide particles can be determined by determining the relationship between the amount of metal salt added to the reaction aqueous solution in the nucleation stage and the particle growth stage and the resulting particles in the preliminary test results. It can be easily judged from the amount added.
The above-mentioned reaction aqueous solution, that is, a mixed aqueous solution, an aqueous solution of an alkali solution and an aqueous ammonia solution, the reaction aqueous solution adjusted to have a pH in the range of 10.5 to 12.0 Aqueous solution.

As described above, in the composite hydroxide particle manufacturing process, nucleation takes precedence in the nucleation stage and almost no nucleation occurs. Conversely, in the particle growth stage, only nucleation occurs and almost new nuclei are not produced. Not generated.
For this reason, in the nucleation stage, homogeneous nuclei with a narrow particle size distribution range can be formed, and in the grain growth stage, nuclei can be grown homogeneously. Therefore, in the composite hydroxide particle manufacturing process, uniform composite hydroxide particles having a narrow particle size distribution range can be obtained.

  In the case of the above production process, the metal ions are crystallized as nuclei or composite hydroxide particles in both stages, so that the ratio of the liquid component to the metal component in the reaction aqueous solution increases. When this liquid component increases, it appears that the concentration of the supplied mixed aqueous solution is lowered, and there is a possibility that the composite hydroxide particles do not grow sufficiently in the particle growth stage.

Therefore, in order to suppress the increase of the liquid component, it is necessary to discharge a part of the liquid component in the reaction aqueous solution to the outside of the reaction tank after the nucleation step or in the middle of the particle growth step.
Specifically, the supply and stirring of the mixed aqueous solution and the like to the reaction aqueous solution are stopped, the nucleus and the composite hydroxide particles are settled, and the supernatant of the reaction aqueous solution is discharged.
As a result, the relative concentration of the mixed aqueous solution in the reaction aqueous solution can be increased, and the composite hydroxide particles can be grown in a state where the relative concentration of the mixed aqueous solution is high. The distribution can be further narrowed, and the density in the secondary particles of the composite hydroxide particles can also be increased.

In the above embodiment, the pH value of the aqueous solution for nucleation after completion of the nucleation step is adjusted to form an aqueous solution for particle growth, and the particle growth step is performed subsequently from the nucleation step. There is an advantage that the transition to the stage can be performed quickly.
Furthermore, the transition from the nucleation stage to the particle growth stage can be performed only by adjusting the pH value of the reaction aqueous solution, and the pH value can also be easily adjusted by temporarily stopping the supply of the alkaline aqueous solution. There is an advantage. The pH value of the reaction aqueous solution can also be adjusted by adding an inorganic acid of the same kind as the acid constituting the metal compound, for example, sulfuric acid in the case of a sulfate to the reaction aqueous solution.

However, as another embodiment, as shown in FIG. 2, a component adjustment aqueous solution adjusted to a pH value and ammonium ion concentration suitable for the nucleation stage is formed separately from the nucleation aqueous solution, and this component adjustment is performed. An aqueous solution containing nuclei generated by performing a nucleation step in another reaction tank may be added to the aqueous solution to form a reaction aqueous solution, and the particle growth step may be performed in this reaction aqueous solution (that is, an aqueous solution for particle growth).
In this case, since the nucleation stage and the particle growth stage can be more reliably separated, the state of the reaction aqueous solution in each process can be set to an optimum condition for each process. In particular, the pH value of the aqueous reaction solution can be set to the optimum condition from the beginning of the beginning of the particle growth stage. Therefore, the composite hydroxide particles formed in the particle growth stage can be made narrower and more uniform in the range of particle size distribution.

Next, substances, solutions and reaction conditions used in each stage will be described in detail.
[PH value]
(Nucleation stage)
In the nucleation stage, the pH value of the aqueous reaction solution is controlled to be 12.0 to 14.0, preferably 12.5 to 13.0 on the basis of the liquid temperature of 25 ° C.
When the pH value exceeds 14.0, the produced nuclei become too fine and the reaction aqueous solution gels. On the other hand, when the pH value is less than 12.0, a nucleus growth reaction occurs together with nucleation, so that the range of the particle size distribution of the nuclei formed becomes wide and non-uniform.
Therefore, the pH value of the reaction aqueous solution in the nucleation step needs to be 12.0 to 14.0. If it is within this range, the nucleation step suppresses the growth of nuclei and causes almost only nucleation. The nuclei formed can also be homogeneous and have a narrow range of particle size distribution.

(Particle growth stage)
In the particle growth stage, the pH value of the reaction aqueous solution is controlled to be 10.5 to 12.0, preferably 11.0 to 12.0 based on the liquid temperature of 25 ° C.
When the pH value exceeds 12.0, hydroxide particles with many newly generated nuclei and good particle size distribution cannot be obtained. On the other hand, when the pH value is less than 10.5, the solubility by ammonia ions is high, and the metal ions remaining in the liquid without being precipitated increase, so that the production efficiency is deteriorated. In addition, when metal sulfate is used as a raw material, the amount of S (sulfur) remaining in the particles increases.
Therefore, the pH value of the reaction aqueous solution in the particle growth step needs to be 10.5 to 12.0, and within such a range, only the growth of nuclei generated in the nucleation stage is preferentially caused, New nucleation can be suppressed, and the resulting composite hydroxide particles can be homogeneous and have a narrow range of particle size distribution.

In both the nucleation stage and the particle growth stage, the fluctuation range of the pH value is preferably within 0.2 above and below the set value. When the fluctuation range of the pH value is large, nucleation and particle growth are not constant, and uniform composite hydroxide particles having a narrow particle size distribution range may not be obtained.
When the pH value is 12, it is a boundary condition between nucleation and nucleation, and therefore, it can be set as either a nucleation process or a particle growth process depending on the presence or absence of nuclei present in the reaction aqueous solution. .

That is, if the pH value in the nucleation stage is higher than 12 to cause a large amount of nucleation, and if the pH value is set to 12 in the particle growth stage, a large amount of nuclei are present in the reaction aqueous solution, so the growth of the nuclei takes priority Thus, the hydroxide particles having a narrow particle size distribution and a relatively large particle size can be obtained.
On the other hand, in the state where no nuclei exist in the reaction aqueous solution, that is, when the pH value is set to 12 in the nucleation stage, there is no growing nucleus, so nucleation occurs preferentially, and the pH value in the particle growth stage is 12 By making it smaller, the produced | generated nucleus grows and the said hydroxide particle | grains favorable are obtained.
In any case, the pH value in the particle growth stage may be controlled to a value lower than the pH value in the nucleation stage.

[Nucleation amount]
The amount of nuclei generated in the nucleation stage is not particularly limited, but in order to obtain composite hydroxide particles having a good particle size distribution, the total amount, that is, to obtain composite hydroxide particles. The total metal salt to be supplied is preferably 0.1% to 2%, more preferably 1.5% or less.

[Control of particle size of composite hydroxide particles]
Since the particle size of the composite hydroxide of the present invention hardly changes depending on the coating step, the desired particle size can be obtained by controlling the particle size of the particles in the composite hydroxide particle production step. Since the particle size of the composite hydroxide particles can be controlled by the time of the particle growth step, the composite hydroxide particles having the desired particle size can be obtained by continuing the particle growth step until the particles grow to the desired particle size. be able to.
Further, the particle size of the composite hydroxide particles can be controlled not only by the particle growth stage but also by the pH value in the nucleation stage and the amount of raw material charged for nucleation.
That is, by increasing the pH value at the time of nucleation to the high pH value side or by increasing the nucleation time, the amount of raw material to be added is increased, and the number of nuclei to be generated is increased. This makes it possible to reduce the particle size of the composite hydroxide particles even when the particle growth step is performed under the same conditions.

On the other hand, if the nucleation number is controlled to be small, the particle size of the obtained composite hydroxide particles can be increased.
Hereinafter, the conditions such as the metal compound, the ammonia concentration in the reaction aqueous solution, the reaction temperature, and the atmosphere will be described. The difference between the nucleation stage and the particle growth stage is only in the range in which the pH value of the reaction aqueous solution is controlled. The conditions such as the compound, the ammonia concentration in the reaction solution, the reaction temperature, and the atmosphere are substantially the same in both stages.

[Metal compounds]
As the metal compound, a compound containing the target metal is used.
As the compound to be used, a water-soluble compound is preferably used, and examples thereof include nitrates, sulfates and hydrochlorides. For example, nickel sulfate, cobalt sulfate, and manganese sulfate are preferably used.

[Additive elements]
As the additive element (at least one additive element selected from transition metal elements other than M and W, Group 2 element, or Group 13 element), a water-soluble compound is preferably used. For example, aluminum sulfate, titanium sulfate, Ammonium peroxotitanate, potassium potassium oxalate, vanadium sulfate, ammonium vanadate, chromium sulfate, potassium chromate, zirconium sulfate, zirconium nitrate, niobium oxalate, ammonium molybdate and the like can be used.

  In the case where the additive element is uniformly dispersed inside the composite hydroxide particles, an additive containing the additive element may be added to the mixed aqueous solution, and the additive element is uniformly distributed inside the composite hydroxide particles. It can be coprecipitated in a dispersed state.

[Concentration of mixed aqueous solution]
The concentration of the mixed aqueous solution is preferably 1 to 2.6 mol / L in total of the metal compounds. When the concentration of the mixed aqueous solution is less than 1 mol / L, the amount of crystallized product per reaction tank is decreased, and thus the productivity is not preferable.

On the other hand, when the salt concentration of the mixed aqueous solution exceeds 2.6 mol / L, there is a danger that the saturated concentration will be exceeded when the liquid temperature is lowered, and crystals will re-deposit and clog the equipment piping.
The metal compound does not necessarily have to be supplied to the reaction vessel as a mixed aqueous solution. For example, when a metal compound that reacts when mixed to produce a compound is used, the total concentration of all the metal compound aqueous solutions is within the above range. As described above, the metal compound aqueous solution may be prepared individually and supplied into the reaction vessel at a predetermined ratio simultaneously as an aqueous solution of each metal compound.

  Furthermore, the amount of the mixed aqueous solution or the aqueous solution of each metal compound supplied to the reaction vessel is desirably such that the crystallized substance concentration is approximately 30 to 200 g / L when the crystallization reaction is completed. This is because when the crystallized substance concentration is less than 30 g / L, the aggregation of primary particles may be insufficient, and when it exceeds 200 g / L, the mixed aqueous solution to be added is sufficiently diffused in the reaction vessel. This is because the grain growth may be biased.

[Ammonia concentration]
The ammonia concentration in the reaction aqueous solution is preferably kept constant within a range of 3 to 25 g / L.
Since ammonia acts as a complexing agent, if the ammonia concentration is less than 3 g / L, the solubility of metal ions cannot be kept constant, and plate-shaped hydroxide primary particles having a uniform shape and particle size are available. Is not formed, and gel-like nuclei are easily generated, so that the particle size distribution is likely to be widened.

On the other hand, when the ammonia concentration exceeds 25 g / L, the solubility of metal ions becomes too high, the amount of metal ions remaining in the aqueous reaction solution increases, and compositional deviation occurs. In addition, the crystallinity of the particles may increase, and the specific surface area may become too low.
Furthermore, when the ammonia concentration varies, the solubility of metal ions varies, and uniform hydroxide particles are not formed. Therefore, it is preferable to maintain a constant value. For example, the ammonia concentration is preferably maintained at a desired concentration by setting the upper and lower limits to about 5 g / L.
In addition, although an ammonium ion supply body is not specifically limited, For example, ammonia, ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium fluoride etc. can be used.

[Reaction atmosphere]
In the nucleation stage, from the viewpoint of stably producing particles by suppressing oxidation of transition metals, particularly cobalt and manganese, the oxygen concentration in the reaction vessel space is preferably 10% by volume or less, more preferably 5% by volume. While controlling below, it is preferable to perform crystallization reaction, controlling the dissolved oxygen concentration in the solution in a reaction tank to 2 mg / L or less. By carrying out in this way, unnecessary oxidation of particles can be suppressed, particles having a high density, a specific surface area can be controlled, and particles having a uniform particle size can be obtained.
On the other hand, oxidation control is important in the particle growth stage, and it is preferable to similarly control the oxygen concentration in the reaction vessel space.

  The oxygen concentration in the atmosphere can be adjusted using, for example, an inert gas such as nitrogen. As a means for adjusting the oxygen concentration in the atmosphere to be a predetermined concentration, for example, an inert gas such as nitrogen is always circulated in the atmosphere in the reaction vessel space.

[Reaction liquid temperature]
In the reaction vessel, the temperature of the reaction solution is preferably set to 20 ° C or higher, more preferably 20 to 60 ° C, and particularly preferably 35 to 60 ° C.
When the temperature of the reaction solution is less than 20 ° C., the solubility is low, so that nucleation is likely to occur and control becomes difficult. Moreover, the primary particles constituting the composite hydroxide particles become fine and the specific surface area may become too large. On the other hand, when it exceeds 60 ° C., ammonia for complex formation due to volatilization of ammonia becomes insufficient, and the solubility of metal ions tends to decrease as in the case where the temperature is less than 20 ° C.

[Alkaline aqueous solution]
The aqueous alkali solution for adjusting the pH value in the aqueous reaction solution is not particularly limited, and for example, an aqueous alkali metal hydroxide solution such as sodium hydroxide or potassium hydroxide can be used. In the case of such an alkali metal hydroxide, it may be supplied directly into the reaction aqueous solution, but it may be added to the reaction aqueous solution in the reaction vessel as an aqueous solution for ease of controlling the pH value of the reaction aqueous solution in the reaction vessel. preferable.
In addition, the method of adding the alkaline aqueous solution to the reaction tank is not particularly limited, and the pH value of the aqueous reaction solution is within a predetermined range with a pump capable of controlling the flow rate such as a metering pump while sufficiently stirring the mixed aqueous solution. It may be added so as to be retained.

[production equipment]
In the composite hydroxide production process, an apparatus that does not recover the product until the reaction is completed is used. For example, it is a normally used batch reactor equipped with a stirrer.
When such an apparatus is used, there is no problem that the growing particles are recovered at the same time as the overflow liquid unlike the continuous crystallization apparatus that recovers the product by overflow, so that the particle size distribution is narrow and the particle size is uniform. Particles can be obtained.

In order to control the reaction atmosphere, it is preferable to use an apparatus capable of controlling the atmosphere such as a hermetically sealed apparatus. By using such an apparatus, the nucleation reaction and the particle growth reaction can be progressed almost uniformly, and particles having an excellent particle size distribution (that is, particles having a narrow particle size distribution range) can be obtained.
After completion of the particle growth stage, the composite hydroxide particles are obtained by washing with water to remove the Na salt adhering to the particles.

(B) Coating step In the coating step, the composite hydroxide particles obtained in the particle production step are mixed with an aqueous solution containing at least a tungsten compound to form a slurry, and the pH of the slurry is 7 to 9 based on a liquid temperature of 25 ° C. Thus, a coating containing tungsten and a metal oxide or metal hydroxide of an additive element is formed on the surface of the composite hydroxide particle.

First, the composite hydroxide particles are slurried. In the slurrying, the aqueous solution containing the element to be coated and the composite hydroxide particles prepared in advance may be mixed, or after mixing the water and the composite hydroxide particles, the compound containing the element to be coated may be added. .
The concentration of the composite hydroxide particles in the slurry is preferably 100 to 300 g / L. A slurry concentration of less than 100 g / L is not preferable because the amount of liquid to be processed is too large and productivity is lowered. On the other hand, when the slurry concentration exceeds 300 g / L, it may not be possible to form a uniform coating on the composite hydroxide particles. Almost all of tungsten ions and additive element ions dissolved in the slurry are crystallized as oxides or hydroxides on the surface of the composite hydroxide particles.

  Therefore, the tungsten compound added to the slurry and the compound containing the additive element may be in the atomic ratio shown in the general formula (1). In addition, when the additive element is added to the above mixed aqueous solution, the atomic ratio of the metal ions of the composite hydroxide obtained is generally reduced by reducing the additive element added to the slurry by the amount added to the mixed aqueous solution. It can be made to coincide with the atomic ratio shown in the formula (1).

  After the slurry is prepared, the composite hydroxide particles are stirred so that the dissolved tungsten ions and additive element ions are uniformly mixed, and an acid such as sulfuric acid is added to adjust the pH value to 7 on the basis of the liquid temperature of 25 ° C. To 9, preferably 8-9. Tungsten precipitates even when the pH value is 7 or less, but if the pH value is too low, a problem arises in that the hydroxide dissolves. Moreover, since the amount of sulfuric acid used increases, the cost increases. On the other hand, when the pH value exceeds 9, precipitation of tungsten oxide hydrate on the surface of the composite hydroxide particles is not sufficiently performed.

As an additive element to be used, it is preferable to add aluminum in order to further increase the thermal stability of the positive electrode active material. By adding an aluminum compound into the slurry and simultaneously crystallizing tungsten and aluminum, the coating can be made into a mixture containing tungsten oxide hydrate and aluminum hydroxide.
The tungsten compound to be used is not particularly limited as long as it is stable as an aqueous solution, but it is preferable to use ammonium tungstate and / or sodium tungstate which is industrially easy to handle.
Although ammonium tungstate has a low solubility in water of about 30 g / L, once dissolved, it does not precipitate even when the pH is lowered to about 1. Moreover, even if ammonia is added to lower the solubility, it is difficult in the alkaline region. However, when sulfuric acid is added in the presence of ammonia, it precipitates by adjusting the pH value to 7-9, and further precipitates on the surface in the presence of the composite hydroxide particles serving as the nucleus, and the coating is uniformly crystallized. And a coating layer can be formed.

  In the case of using ammonium tungstate, it is preferable to add ammonia corresponding to 0.5 to 25% by volume with respect to the saturated aqueous solution of ammonium tungstate in a 25% aqueous ammonia solution in the slurry. If the amount of ammonia added is small, the tungsten oxide hydrate will be decomposed by sulfuric acid and will not precipitate. Moreover, even if it is too much, it is uneconomical just to waste sulfuric acid for adjusting the pH value. Preferably, 1 to 10% by volume of ammonia corresponding to a 25% aqueous ammonia solution is added to the saturated aqueous solution of ammonium tungstate, and the pH value is adjusted to 7 to 9, so that the surface of the composite hydroxide particles can be efficiently formed. A composite hydroxide coated with tungsten oxide hydrate is obtained.

  On the other hand, sodium tungstate has a high solubility of 100 g / L or more in water, and it does not precipitate by simple pH adjustment, but it can be deposited on the surface in the presence of complex hydroxide particles as a nucleus without addition of ammonia. And can be coated more uniformly in the presence of aluminum.

  The aluminum compound to be used is not particularly limited, but it is preferable to use sodium aluminate that can adjust the pH value by adding sulfuric acid to precipitate aluminum hydroxide. As a result, the pH is controlled by adding sulfuric acid to the slurry, and tungsten and aluminum are simultaneously precipitated as a compound, and the surface of the composite hydroxide particles is uniform with a mixture containing tungsten oxide hydrate and aluminum hydroxide. Can be coated.

  In this coating step, since a fine and uniform coating can be formed on the surface of the composite hydroxide particles, an increase in the specific surface area of the composite hydroxide can be suppressed. Moreover, since almost all of the tungsten in the slurry is deposited on the surface of the composite hydroxide particles, the amount of tungsten contained in the composite hydroxide can be stabilized, and fluctuations in the amount of tungsten between the particles can also be suppressed. .

2-1. Positive electrode active material for non-aqueous electrolyte secondary battery The positive electrode active material for non-aqueous electrolyte secondary battery of the present invention (hereinafter referred to as the positive electrode active material of the present invention) is suitable as a positive electrode material for non-aqueous electrolyte secondary batteries. It is.
The positive electrode active material of the present invention is a positive electrode active material composed of a lithium transition metal composite oxide having a layered structure represented by the following general formula (2) and having a hexagonal crystal structure, and has an average particle size of 3 It is ˜8 μm, and [(d ₉₀ −d ₁₀ ) / average particle diameter], which is an index indicating the spread of the particle size distribution, is 0.60 or less.

[Particle size distribution]
In the positive electrode active material of the present invention, [(d ₉₀ -d ₁₀ ) / average particle size], which is an index indicating the spread of the particle size distribution, is 0.6 or less.
When the particle size distribution is wide, there are many fine particles with a very small particle size relative to the average particle size and particles with a large particle size (coarse particles) with respect to the average particle size. Will do.
When a positive electrode is formed using a positive electrode active material in which a large amount of fine particles are present, heat may be generated due to a local reaction of the fine particles, which reduces safety and selectively deteriorates the fine particles. As a result, the cycle characteristics deteriorate. On the other hand, when a positive electrode is formed using a positive electrode active material having a large amount of coarse particles, a sufficient reaction area between the electrolytic solution and the positive electrode active material cannot be obtained, resulting in a decrease in battery output due to an increase in reaction resistance.

Therefore, by setting the particle size distribution of the positive electrode active material to 0.6 or less in the index [(d ₉₀ -d ₁₀ ) / average particle size], the ratio of fine particles and coarse particles is small. The used battery is excellent in safety and has good cycle characteristics and battery output.
The average particle diameter (d ₅₀ ) and d ₁₀ , d ₉₀ are the same as the above transition metal composite hydroxide, and can be determined by the same method.

[Average particle size]
The positive electrode active material of the present invention has an average particle size of 3 to 8 μm. When the average particle size is less than 3 μm, the packing density of the particles decreases when the positive electrode is formed, and the battery capacity per positive electrode volume decreases. On the other hand, when the average particle size exceeds 8 μm, the specific surface area of the positive electrode active material is decreased and the interface with the battery electrolyte is decreased, whereby the resistance of the positive electrode is increased and the output characteristics of the battery are decreased.

  Therefore, if the positive electrode active material of the present invention is adjusted to have an average particle size of 3 to 8 μm, preferably 3 to 6 μm, a battery using this positive electrode active material for the positive electrode has a battery capacity per volume. In addition to being able to be enlarged, excellent battery characteristics such as high safety and high output can be obtained.

[Specific surface area]
The positive electrode active material of the present invention preferably has a specific surface area of 0.5 to 2.0 m ² / g. When the specific surface area is less than 0.5 m ² / g, the contact area of the positive electrode active material with the electrolytic solution decreases, so that the reaction surface area decreases, the positive electrode resistance increases, and the output characteristics of the battery may deteriorate. On the other hand, if the specific surface area exceeds 2.0 m ² / g, the thermal stability may be deteriorated due to excessive contact with the electrolytic solution. In the present invention, since the composite hydroxide having a controlled specific surface area is used as a precursor, the specific surface area of the positive electrode active material is also stably controlled within the above range.

[Particle composition]
The positive electrode active material of the present invention has a composition represented by the above general formula (2), and the range of u indicating an excess amount of lithium is −0.05 ≦ u ≦ 0.50. When the excess amount u of lithium is less than −0.05, the reaction resistance of the positive electrode in the nonaqueous electrolyte secondary battery using the obtained positive electrode active material increases, and the output of the battery decreases. On the other hand, when the excessive amount u of lithium exceeds 0.50, the initial discharge capacity when this positive electrode active material is used for the positive electrode of the battery is lowered and the reaction resistance of the positive electrode is also increased.

Moreover, as represented by the general formula (2), the positive electrode active material of the present invention contains tungsten in the lithium transition metal composite oxide.
By including tungsten, the positive electrode resistance can be reduced, and the output characteristics of the battery used as the positive electrode active material can be improved. When the added amount of tungsten exceeds 0.05 in terms of the ratio to all metal elements other than lithium, the battery capacity decreases.

  The additive elements used to improve the durability and output characteristics of the battery used as the positive electrode active material are selected from B, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, and Mo. One or more of these are preferable, but at least Al is preferable. By adding Al, the thermal stability of the positive electrode active material can be improved.

When the atomic ratio s + t of tungsten and the additive element A to all metal elements other than lithium exceeds 0.15, the metal element contributing to the Redox reaction decreases, and the battery capacity decreases. On the other hand, if s + t is 0.02 or less, the effect of improving the battery output characteristics and thermal stability may not be sufficient. Therefore, the atomic ratio is preferably 0.02 <s + t ≦ 0.15.
In particular, since the tungsten and the additive element are uniformly distributed on the surface or inside of the particle, the above effect can be obtained over the entire particle, and the effect can be obtained with a small amount of addition and a decrease in battery capacity can be suppressed.

  The positive electrode active material of the present invention is preferably a composite oxide represented by the following general formula (2-1), wherein M in the general formula (2) contains at least Ni and Co. Is preferred.

  The composition of the general formula (2-1) is for the purpose of increasing the capacity of the battery, and the excess amount of lithium u is -0.05 ≦ u ≦ 0 in order to balance the capacity and output of the battery. .15 is preferable. The range of x indicating the atomic ratio of Co is preferably 0 ≦ x ≦ 0.2 from the viewpoint of battery capacity and thermal stability.

  In another embodiment, M preferably contains at least Ni and Mn, and specifically, a composite oxide represented by the following general formula (2-2) is preferable.

In the case of the composition of the general formula (2-2), the excessive amount u of lithium is preferably −0.05 ≦ u ≦ 0.15 in order to further reduce the reaction resistance.
The range of x indicating the atomic ratio of Ni is preferably set to 0.3 ≦ x ≦ 0.7 in order to obtain a sufficient capacity.
The range of y indicating the atomic ratio of Mn is preferably 0.1 ≦ y ≦ 0.55 in order to achieve both battery capacity and thermal stability.
The range of z indicating the atomic ratio of Co is preferably 0 ≦ z ≦ 0.4 from the viewpoint of battery capacity and thermal stability.

2-2. Method for producing positive electrode active material for non-aqueous electrolyte secondary battery As long as the method for producing a positive electrode active material of the present invention can produce a positive electrode active material so as to have the above average particle size, particle size distribution, specific surface area, and composition, Although not particularly limited, it is preferable to employ the following method because the positive electrode active material can be more reliably produced.

The method for producing a positive electrode active material of the present invention includes the following three steps as shown in FIG.
(A) A heat treatment step of the transition metal composite hydroxide used as a raw material of the positive electrode active material of the present invention.
(B) A mixing step in which a lithium compound is mixed with the composite hydroxide after the heat treatment to form a lithium mixture.
(C) A firing step of firing the lithium mixture formed in the mixing step.

Hereinafter, each process will be described.
(A) Heat treatment step The heat treatment step is a step of removing moisture contained in the composite hydroxide by heating and heat-treating the transition metal composite hydroxide (hereinafter simply referred to as composite hydroxide). The temperature is preferably 500 ° C to 750 ° C.

  In particular, by heating and heating to the above temperature, the composite hydroxide can be converted into a transition metal composite oxide (hereinafter simply referred to as composite oxide) along with moisture removal. It is possible to prevent variations in the number of metal atoms and the number of lithium atoms. However, by strictly performing the analysis before the firing step, performing the analysis after the mixing and correcting the analysis, the heat treatment step is omitted or the main purpose is to remove the contained water at 105 ° C. or higher, 500 ° C. Heat treatment can also be performed at a temperature of less than ° C.

  In the heat treatment step, when the heating temperature is less than 500 ° C., the composite hydroxide may not be sufficiently converted to the composite oxide, and when it exceeds 750 ° C., the particles are sintered to form a composite having a uniform particle size. Oxides may not be obtained.

The atmosphere in which the heat treatment is performed is not particularly limited and may be a non-reducing atmosphere, but is preferably performed in an air stream that can be easily performed.
Further, the heat treatment time is not particularly limited, but if it is less than 1 hour, the conversion of the composite hydroxide into composite oxide particles may not be sufficiently performed. Therefore, it is preferably at least 1 hour, more preferably 5 to 15 hours. preferable.
And the equipment used for the heat treatment is not particularly limited, as long as it is capable of heating the composite hydroxide in a non-reducing atmosphere, preferably in an air stream, such as an electric furnace that does not generate gas. Preferably used.

(B) Mixing step The mixing step is a step of obtaining a lithium mixture by mixing the composite hydroxide after the heat treatment and a substance containing lithium, for example, a lithium compound. The composite hydroxide after the heat treatment in the mixing step includes a composite hydroxide in which the heat treatment step is omitted, a composite hydroxide from which residual moisture has been removed in the heat treatment step, and a composite oxide converted in the heat treatment step.

The composite hydroxide after heat treatment and the substance containing lithium are the number of atoms of all metals other than lithium in the lithium mixture (that is, the sum of the number of atoms of M, W and additive elements (Me)), lithium Is mixed so that the ratio (Li / Me) to the number of atoms (Li) is 1: 0.95 to 1.50.
That is, Li / Me does not substantially change before and after the firing step, and Li / Me mixed in this mixing step becomes Li / Me in the positive electrode active material. Therefore, Li / Me in the lithium mixture becomes the positive electrode active to be obtained. Mixed to be the same as Li / Me in the material.

The lithium-containing substance used to form the lithium mixture is not particularly limited as long as it is a lithium compound. For example, lithium hydroxide, lithium nitrate, lithium carbonate, or a mixture thereof is preferable because it is easily available.
The lithium mixture is preferably mixed well before firing. If the mixing is not sufficient, Li / Me varies among individual particles, which may cause problems such as insufficient battery characteristics.

  Moreover, a general mixer can be used for mixing, for example, a shaker mixer, a Laedige mixer, a Julia mixer, a V blender, etc. can be used, and a complex object, such as composite oxide particles, is not destroyed. To the extent, the composite oxide particles and the substance containing lithium need only be sufficiently mixed.

(C) Firing step The firing step is a step of firing the lithium mixture obtained in the mixing step to form a lithium transition metal composite oxide. When the lithium mixture is fired in the firing step, lithium in the material containing lithium is diffused into the composite oxide particles, so that a lithium transition metal composite oxide is formed.

[Baking temperature]
Firing of the lithium mixture is performed at a temperature of 700 ° C to 1000 ° C.
When the firing temperature is less than 700 ° C., lithium is not sufficiently diffused into the composite oxide particles, and excess lithium and unreacted particles remain, the crystal structure is not sufficiently adjusted, and sufficient battery characteristics are obtained. The problem that it cannot be obtained arises.
In addition, when the firing temperature exceeds 1000 ° C., intense sintering occurs between the composite oxide particles, and abnormal grain growth may occur. As a result, the fired particles become coarse and have a particle morphology ([ The shape of the spherical secondary particles described in [0092] to [0097] may not be maintained.
Since such a positive electrode active material has a reduced specific surface area, when used in a battery, there arises a problem that the resistance of the positive electrode increases and the battery capacity decreases.

  Therefore, the lithium mixture is preferably fired at 700 to 800 ° C. when the atomic ratio of Ni is 0.7 or more. Moreover, when the said atomic ratio of Mn is 0.3 or more, it is preferable to carry out at 800-1000 degreeC.

[Baking time]
The firing time is preferably at least 3 hours or more, more preferably 6 to 24 hours. If it is less than 3 hours, the lithium transition metal composite oxide may not be sufficiently generated.

[Calcination]
In particular, when lithium hydroxide, lithium carbonate, or the like is used as the lithium-containing substance, it is temporarily maintained at a temperature lower than the firing temperature and 350 to 800 ° C. for about 1 to 10 hours before firing. It is preferable to bake.
That is, it is preferable to calcine at the reaction temperature of lithium hydroxide or lithium carbonate and the composite hydroxide after heat treatment. If the reaction temperature is maintained in the vicinity of the above reaction temperature of lithium hydroxide or lithium carbonate, lithium is sufficiently diffused into the composite hydroxide after the heat treatment, and a uniform lithium transition metal composite oxide can be obtained.

[Baking atmosphere]
The atmosphere during firing is preferably an oxidizing atmosphere, more preferably an oxygen concentration of 18 to 100% by volume, and particularly preferably a mixed atmosphere of oxygen and an inert gas.
That is, firing is preferably performed in the air or in an oxygen stream. If the oxygen concentration is less than 18% by volume, the lithium transition metal composite hydroxide may not have sufficient crystallinity. Considering battery characteristics in particular, it is preferably performed in an oxygen stream.
The furnace used for firing is not particularly limited as long as the lithium mixture can be heated in the atmosphere or an oxygen stream, but an electric furnace that does not generate gas is preferable, and a batch type or a continuous type may be used. Any furnace can be used.

[Crushing]
The lithium transition metal composite oxide obtained by firing may be agglomerated or slightly sintered. In this case, it may be crushed, whereby the positive electrode active material of the present invention can be obtained.
Note that pulverization means mechanical energy is applied to an aggregate composed of a plurality of secondary particles generated by sintering necking between secondary particles at the time of firing, and the secondary particles are hardly destroyed. This is an operation of separating the particles and loosening the aggregates.

3. Non-aqueous electrolyte secondary battery The non-aqueous electrolyte secondary battery of the present invention includes a transition metal composite hydroxide according to the present invention, lithium using the composite hydroxide as a precursor, according to the production flowchart shown in FIG. A positive electrode using a positive electrode active material for a non-aqueous electrolyte secondary battery made of a transition metal composite oxide is employed.

First, the structure of the nonaqueous electrolyte secondary battery of the present invention will be described.
The non-aqueous electrolyte secondary battery of the present invention (hereinafter sometimes simply referred to as the secondary battery of the present invention) is a general non-aqueous electrolyte except that the positive electrode active material of the present invention is used as the positive electrode material. It has substantially the same structure as a secondary battery.
Specifically, the secondary battery of the present invention has a structure including a case, and a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator accommodated in the case. More specifically, a positive electrode and a 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 a positive electrode current collector of the positive electrode and a positive electrode terminal connected to the outside are provided. And the negative electrode current collector of the negative electrode and the negative electrode terminal communicating with the outside using a current collecting lead or the like, and sealed in a case, the secondary battery of the present invention is formed and shaped Can be of various types such as a cylindrical type and a laminated type.
It should be noted that the structure of the secondary battery of the present invention is not limited to the above example, and can be implemented in various modifications and improvements based on the knowledge of those skilled in the art. Moreover, the use of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited.

Below, each part which comprises the secondary battery of this invention is demonstrated.
(1) Positive electrode First, the positive electrode which is the characteristic of the secondary battery of this invention is demonstrated.
The positive electrode is a sheet-like member, and is formed by applying and drying a positive electrode mixture paste containing the positive electrode active material of the present invention, for example, on the surface of a current collector made of aluminum foil.
In addition, a positive electrode is suitably processed according to the battery to be used. For example, a cutting process for forming an appropriate size according to a target battery, a pressure compression process using a roll press or the like to increase the electrode density, and the like are performed.

[Positive electrode paste]
The positive electrode mixture paste to be used is formed by adding a solvent to the positive electrode mixture and kneading.
The positive electrode mixture is formed by mixing the positive electrode active material of the present invention in a powder form, a conductive material, and a binder.
The conductive material is added to give an appropriate conductivity to the electrode. The conductive material is not particularly limited, and for example, graphite (natural graphite, artificial graphite, expanded graphite, and the like), and carbon black materials such as acetylene black and ketjen black can be used.

The binder plays a role of tethering the positive electrode active material particles.
The binder used for this positive electrode mixture is not particularly limited. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluorine rubber, ethylene propylene diene rubber, styrene butadiene, cellulosic resin and Polyacrylic acid can be used.
In addition, activated carbon etc. may be added to a positive electrode compound material, and the electric double layer capacity | capacitance of a positive electrode can be increased by adding activated carbon etc.

  The solvent dissolves the binder and disperses the positive electrode active material, the conductive material, activated carbon, and the like in the binder. The solvent is not particularly limited, and for example, an organic solvent such as N-methyl-2-pyrrolidone can be used.

  Moreover, the mixing ratio of each substance in the positive electrode mixture paste is not particularly limited. For example, when 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, the content of the conductive material is the same as the positive electrode of a general non-aqueous electrolyte secondary battery. The amount can be 1 to 20 parts by mass, and the content of the binder can be 1 to 20 parts by mass.

(2) Negative electrode A negative electrode is a sheet-like member formed by applying a negative electrode mixture paste to the surface of a metal foil current collector such as copper and drying it. The negative electrode is formed by substantially the same method as the positive electrode, although the components constituting the negative electrode mixture paste, the composition thereof, and the current collector material are different. Is done.

The negative electrode mixture paste is a paste obtained by adding an appropriate solvent to a negative electrode mixture in which a negative electrode active material and a binder are mixed.
As the negative electrode active material, for example, a material containing lithium, such as metallic lithium or a lithium alloy, or an occlusion material that can occlude and desorb lithium ions can be employed.
The occlusion material is not particularly limited, and for example, a fired organic compound such as natural graphite, artificial graphite and phenol resin, and a powdery material of carbon material such as coke can be used.
When such an occlusion material is employed as the negative electrode active material, a fluorine-containing resin such as PVDF can be used as a binder as in the positive electrode, and as a solvent for dispersing the negative electrode active material in the binder, N An organic solvent such as methyl-2-pyrrolidone can be used.

(3) Separator The separator is interposed between the positive electrode and the negative electrode and has a function of separating the positive electrode and the negative electrode and holding the electrolyte. As such a separator, for example, a thin film such as polyethylene or polypropylene and a film having a large number of fine pores can be used. However, the separator is not particularly limited as long as it has the above function.

(4) Non-aqueous electrolyte solution The non-aqueous electrolyte solution is obtained by dissolving a lithium salt of 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, ethylmethyl carbonate and dipropyl carbonate, tetrahydrofuran, 2- One kind selected from ether compounds such as methyltetrahydrofuran and dimethoxyethane, sulfur compounds such as ethylmethylsulfone and butanesultone, and phosphorus compounds such as triethyl phosphate and trioctyl phosphate 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 , and complex salts thereof can be used.
In addition, the non-aqueous electrolyte solution may contain a radical scavenger, a surfactant, a flame retardant, and the like for improving battery characteristics.

(5) Characteristics of non-aqueous electrolyte secondary battery The non-aqueous electrolyte secondary battery of the present invention has the above-described configuration and uses the positive electrode active material of the present invention. For example, in the case of a 2032 type coin, 150 mAh / g or more. High initial discharge capacity, low positive electrode resistance of 5Ω or less, high capacity and high output. Further, it can be said that the thermal stability is high and the safety is also excellent in comparison with a battery using a positive electrode active material of a conventional lithium / cobalt oxide or lithium / nickel oxide.

(6) Use of non-aqueous electrolyte secondary battery Since the non-aqueous electrolyte secondary battery of the present invention has the above properties, it is a small portable electronic device (such as a notebook personal computer or a mobile phone terminal) that always requires a high capacity. ) Is suitable for the power source.
The non-aqueous electrolyte secondary battery of the present invention is also suitable for a motor drive power source that requires high output. When a battery becomes large, it is difficult to ensure safety and an expensive protection circuit is indispensable. However, because it has excellent safety, it is not only easy to ensure safety but also expensive. The protection circuit can be simplified and the cost can be reduced. And since it can be reduced in size and increased in output, it is suitable as a power source for transportation equipment subject to restrictions on the mounting space.

Hereinafter, the present invention will be described in more detail with reference to examples.
In Examples, the average particle size and particle size distribution of the composite hydroxide produced by the method of the present invention and the positive electrode active material produced by the method of the present invention using this composite hydroxide as a precursor were confirmed.
Moreover, about the secondary battery which has a positive electrode manufactured using the positive electrode active material manufactured by the method of this invention, the performance (initial stage discharge capacity, positive electrode resistance, thermal stability) was confirmed.
The present invention is not limited in any way by these examples.

  “Measurement of average particle diameter”, “measurement of particle size distribution”, “identification and confirmation of crystal structure”, “composition analysis” and “production of secondary battery (including evaluation)” in the examples are performed as follows. It was.

[Measurement of average particle size and particle size distribution]
The average particle size and particle size distribution ([(d ₉₀ -d ₁₀ ) / average particle size] value) are volume integrated values measured using a laser diffraction scattering type particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., Microtrac HRA). Calculated from

[Identification and confirmation of crystal structure]
The crystal structure was identified and confirmed by X-ray diffraction measurement (“X'Pert PRO” manufactured by Panalical).

[Composition analysis]
The composition was analyzed by ICP emission spectroscopy after dissolving the sample.

[Manufacture of secondary batteries]
For the evaluation, a 2032 type coin battery (hereinafter referred to as a coin type battery B) shown in FIG. 5 was produced and used.
As shown in FIG. 5, the coin-type battery B includes a case (a positive electrode can 5 and a negative electrode can 6) and electrodes (a positive electrode 1 and a negative electrode 2) housed in the case.
The case includes a positive electrode can 5 that is hollow and open at one end, and a negative electrode can 6 that is disposed in the opening of the positive electrode can 5. When the negative electrode can 6 is disposed in the opening of the positive electrode can 5, the negative electrode can 6 A space for accommodating the electrode is formed between the positive electrode can 5 and the positive electrode can 5.
The electrode is composed of a positive electrode 1 and a negative electrode 2, and a separator 3 is inserted and stacked between the positive electrode 1 and the negative electrode 2, the positive electrode 1 contacts the inner surface of the positive electrode can 5, and the negative electrode 2 is the negative electrode can 6. It is accommodated in the case so as to be in contact with the inner surface.

  The case includes a gasket 4, and the gasket 4 fixes the positive electrode can 5 and the negative electrode can 6 so as to maintain an electrically insulated state. Further, the gasket 4 also has a function of sealing the gap between the positive electrode can 5 and the negative electrode can 6 to block the inside and outside of the case in an airtight and liquid-tight manner.

Such a coin-type battery B 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 1 was produced. Next, the produced positive electrode 1 was dried at 120 ° C. for 12 hours in a vacuum dryer.

Using this positive electrode 1, the negative electrode 2, the separator 3 and the electrolytic solution, a coin-type battery B was produced in a glove box in an Ar atmosphere in which the dew point was controlled at −80 ° C.
The negative electrode 2 was made of Li metal having a diameter of 17 mm and a thickness of 1 mm. The separator 3 was a polyethylene porous film having a film thickness of 25 μm.

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 performance evaluation of the manufactured coin-type battery B was defined as follows with respect to the initial discharge capacity, the positive electrode resistance, and the thermal stability.
-The initial discharge capacity is left for about 24 hours after the coin-type battery B is produced. 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. The capacity when the battery was charged to 4.3 V and discharged to a cut-off voltage of 3.5 V after a pause of 1 hour was defined as the initial discharge capacity.

The positive resistance was measured by the AC impedance method using a frequency response analyzer and a potentiogalvanostat (Solartron, 1255B) after charging the coin-type battery B at a charging potential of 4.1 V, and the Nyquist shown in FIG. Create a plot.
Since this Nyquist plot is expressed as the sum of the characteristic curve indicating the solution resistance, the negative electrode resistance and its capacity, and the positive electrode resistance and its capacity, fitting calculation is performed using an equivalent circuit based on this Nyquist plot, and the positive resistance The value of was calculated.

  ・ Thermal stability, after charging to a charging potential of 4.575 V, disassemble the coin cell, take out the positive electrode, measure the change in calorie at 80-400 ° C. with a differential scanning calorimeter (DSC3100SA, manufactured by MAC Science), Evaluation was made as an exothermic starting temperature.

[Composite hydroxide particle production process]
First, while putting water in the reaction tank (34L) to half the amount of the reaction tank and stirring, the temperature in the tank was set to 40 ° C., and nitrogen gas was passed through the reaction tank to form a nitrogen gas atmosphere. At this time, the oxygen concentration in the reaction vessel space was 2.0% by volume, and the dissolved oxygen concentration in the solution in the reaction vessel was 2 mg / L or less.
By adding appropriate amounts of 25% by mass aqueous sodium hydroxide and 25% by mass ammonia water to the water in the reaction vessel, the pH was adjusted to 12.6 based on a liquid temperature of 25 ° C. Further, the ammonium ion concentration in the reaction solution was adjusted to 15 g / L.

<Nucleation stage>
Next, nickel sulfate and cobalt sulfate were dissolved in water to obtain a 1.8 mol / L mixed aqueous solution. In this mixed aqueous solution, the element molar ratio of each metal was adjusted to be Ni: Co = 0.82: 0.15.
The mixed aqueous solution was added to the reaction solution in the reaction vessel at 88 ml / min. At the same time, 25% by mass ammonia water and 25% by mass sodium hydroxide aqueous solution are also added to the reaction solution in the reaction tank at a constant rate, and the ammonium ion concentration in the resulting aqueous solution for nucleation is maintained at the above value. In this state, crystallization was carried out for 2 minutes and 30 seconds while controlling the pH value to 12.6 (nucleation pH) on the basis of the liquid temperature of 25 ° C. to perform nucleation.

<Particle growth stage>
Thereafter, until the pH value of the aqueous solution for nucleation reached 11.6 (particle growth pH), only the supply of the 25% aqueous sodium hydroxide solution was temporarily stopped to obtain an aqueous solution for particle growth.
After the pH value of the obtained aqueous solution for particle growth reached 11.6 based on the liquid temperature of 25 ° C., the supply of the 25% by mass aqueous sodium hydroxide solution was resumed and the pH value was controlled to 11.6. Then, the particles were grown for 2 hours.
When the reaction tank became full, the supply of the sodium hydroxide solution was stopped and the stirring was stopped and the mixture was allowed to stand to promote precipitation of the product. Thereafter, after removing half of the supernatant from the reaction vessel, the supply of the sodium hydroxide solution was resumed, and after crystallization for 2 hours (4 hours in total), the particle growth was terminated. And the particle | grains were collect | recovered by washing with water, filtering, and drying the obtained product.

[Coating process]
The obtained particles are coated with tungsten and aluminum to have a molar ratio of Ni: Co: Al: W = 82: 15: 3: 0.5. In a 500 mL beaker, 100 g of hydroxide particles, water, sodium aluminate Then, 37 ml of a 30 g / L ammonium tungstate aqueous solution was mixed so that the slurry concentration at the end of coating was 200 g / L. After adding 3.7 ml of 25% by mass ammonia water as 10% by volume of the ammonium tungstate aqueous solution, coating is performed by adding 8% by mass sulfuric acid so that the final pH is 8.5 at room temperature (25-30 ° C.). It was.
Thereafter, the entire amount of the hydroxide slurry in the container was collected by filtration, washed with water and dried at 120 ° C. for 12 hours or more, and Ni _0.82 Co _0.15 Al _0.03 W _0.005 (OH) A composite hydroxide represented by _{2 + α} (0 ≦ α ≦ 0.5) was obtained.
The specific surface area as measured by the BET method was 8.6 m ² / g for the composite hydroxide.

[Positive electrode active material manufacturing process]
<Heat treatment process>
The composite hydroxide was heat-treated at 700 ° C. for 6 hours in an air stream (oxygen concentration: 21% by volume) to obtain a composite oxide.

<Mixing process>
Lithium hydroxide was weighed so that Li / Me = 1.02 (atomic ratio), and this lithium hydroxide was mixed with the composite oxide particles obtained above to obtain a lithium mixture. Mixing was performed using a shaker mixer apparatus (TURBULA Type T2C manufactured by Willy et Bacofen (WAB)).

<Baking process>
The obtained mixture was calcined at 500 ° C. for 4 hours in an oxygen stream (oxygen concentration: 100% by volume), then calcined at 730 ° C. for 24 hours, cooled, and crushed to obtain a positive electrode active material. . The composition of the positive electrode active material was Li _1.02 Ni _0.816 Co _0.149 Al _0.030 W _0.005 O ₂ . The specific surface area of the positive electrode active material as measured by the BET method was 0.67 m ² / g.
Table 1 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

  In the composite hydroxide particle manufacturing process, the mixed aqueous solution was prepared and crystallized so that the metal element had a molar ratio of Ni: Co: Ti = 82: 15: 1, and the molar ratio of Ni: Co: Ti: Al : W = 82: 15: 1: 2: A cathode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 1 except that the coating was performed so that the ratio was W: 82: 15: 1: 2: 0.5.

The composition of the positive electrode active material was Li _1.02 Ni _0.816 Co _0.149 Ti _0.010 Al _0.020 W _0.005 O ₂ .
Further, the BET specific surface area measurement, the composite hydroxide is 8.9 m ² / g, it was the positive electrode active material 0.72 m ² / g.
Table 1 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

  In the composite hydroxide manufacturing process, a mixed aqueous solution was prepared and crystallized so that the metal element had a molar ratio of Ni: Co: Zr = 82: 15: 0.5; Ni: Co: Zr: Al: W A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 1 except that the coating was performed so that the ratio was 82: 15: 0.5: 2: 0.5.

The composition of the positive electrode active material was Li _1.02 Ni _0.82 Co _0.15 Al _0.02 Zr _0.005 W _0.005 O ₂ .
The specific surface area as measured by the BET method was 9.0 m ² / g for the composite hydroxide and 0.77 m ² / g for the positive electrode active material.
Table 1 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

  The mixed aqueous solution was prepared and crystallized so that the metal element had a molar ratio of Ni: Co: Mn = 8: 1: 1 in the composite hydroxide production process, and the molar ratio of Ni: Co: Mn in the coating process. : W = 80: 10: 10: 0.5 In the positive electrode active material manufacturing process, the heat treatment temperature was set to 550 ° C., and Li / Me = 1.10 was mixed. A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 1 except that the firing temperature was 800 ° C.

The composition of the positive electrode active material was Li _1.10 Ni _0.796 Co _0.100 Mn _0.100 W _0.005 O _{2 The} specific surface area measured by the BET method was 12.1 m for the composite hydroxide. ^The positive electrode active material was 1.05 m ² / g.
Table 1 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

[Composite hydroxide particle production process]
The water temperature in the small reaction tank (5 L) was set to 40 ° C. while stirring the water up to half the volume of the reaction tank. By adding appropriate amounts of 25% by mass sodium hydroxide aqueous solution and 25% by mass ammonia water in the reaction vessel, the reaction solution was adjusted to 12.6 at a pH value based on a liquid temperature of 25 ° C., and the ammonium ion concentration in the reaction solution was reduced. Adjusted to 10 g / L.

<Nucleation stage>
Next, a mixed aqueous solution of 1.8 mol / L obtained by dissolving nickel sulfate, cobalt sulfate and (metal element molar ratio Ni: Co = 82: 15) in water, and 25% by mass ammonia water in the reaction solution. And 25 mass% aqueous sodium hydroxide solution was added at a constant rate, and the pH value was maintained at 12.6 based on the liquid temperature of 25 ° C. while maintaining the ammonium ion concentration in the resulting aqueous solution for nucleation to be the above value. Seed crystals were obtained by adding an aqueous sodium hydroxide solution for 2 minutes and 30 seconds while controlling to (nucleation pH).

<Particle growth stage>
While the water was added to another reaction tank (34 L) to half the amount of the reaction tank and stirred, the temperature in the tank was set to 40 ° C. and nitrogen gas was circulated to form a nitrogen atmosphere. At this time, the oxygen concentration in the reaction vessel space was 2.0% by volume.

  Appropriate amounts of 25% by mass aqueous sodium hydroxide and 25% by mass ammonia water were added to the water in the reaction vessel, and the pH value of the reaction solution in the reaction vessel was adjusted to 11.6 based on the liquid temperature of 25 ° C. . The ammonium ion concentration in the reaction solution was adjusted to 10 g / L. After the reaction solution containing seed crystals obtained in the small reaction vessel was charged into the reaction vessel, the pH value was controlled to 11.6 while maintaining the ammonium ion concentration in the aqueous solution for particle growth at the above value. The mixed aqueous solution, aqueous ammonia and aqueous sodium hydroxide solution were continuously added for 2 hours, and particle growth was performed.

  When the reaction tank was full, the supply of ammonia water and aqueous sodium hydroxide solution was stopped, and stirring was stopped and the mixture was allowed to stand to promote precipitation of the product. After the product precipitated, half of the supernatant was withdrawn from the reaction vessel, and then the supply of aqueous ammonia and aqueous sodium hydroxide was resumed. After supplying ammonia water and aqueous sodium hydroxide solution for another 2 hours (4 hours in total), the supply was terminated, and the obtained particles were washed with water, filtered and dried to recover.

[Coating process]
A composite hydroxide was obtained by coating in the same manner as in Example 1 except that the obtained particles were coated so that the molar ratio was Ni: Co: Al: W = 82: 15: 3: 1. It was.
Subsequent steps were performed in the same manner as in Example 1 to obtain and evaluate a positive electrode active material for a non-aqueous electrolyte secondary battery.
The composition of the positive electrode active material was Li _1.02 Ni _0.812 Co _0.149 Al _0.030 W _0.010 O ₂ .
Further, the BET specific surface area measurement, the composite hydroxide is 9.0 m ² / g, was positive active material 0.82m ² / g.
Table 1 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

(Comparative Example 1)
A positive electrode active material for a non-aqueous electrolyte secondary battery in the same manner as in Example 1 except that in the coating step, the aqueous ammonia solution was not added and coating was performed so that Ni: Co: Al = 82: 15: 3. And evaluated.
The composition of the positive electrode active material was Li _1.02 Ni _0.82 Co _0.15 Al _0.03 O ₂ .
Further, the BET specific surface area measurement, the composite hydroxide is 8.6 m ² / g, it was the positive electrode active material 0.70 m ² / g.
Table 1 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

(Evaluation)
Examples 1 to 5 having the average particle size and particle size distribution of the present invention and having added tungsten have high capacity and low positive electrode resistance, and are suitable as positive electrode active materials for non-aqueous electrolyte secondary batteries. I understand. On the other hand, Comparative Example 1 to which no tungsten is added has a high capacity but a high positive electrode resistance, indicating that the output characteristics are not sufficient.

[Hydroxide particle production process]
First, the water temperature was set to 40 ° C. while stirring by adding half the amount of water in the reaction tank, and nitrogen gas was circulated through the reaction tank to form a nitrogen gas atmosphere. At this time, the oxygen concentration in the reaction vessel space was 3.0% by volume, and the dissolved oxygen concentration in the solution in the reaction vessel was 2 mg / L or less. Thereto were added appropriate amounts of 25% by mass aqueous sodium hydroxide and 25% by mass ammonia water, and the pH value of the solution was adjusted to 12.6 based on the liquid temperature of 25 ° C., and the ammonia concentration in the solution was adjusted to 10 g / L. Here, a 2.0 mol / L aqueous solution obtained by dissolving nickel sulfate and manganese sulfate (metal element molar ratio Ni: Mn = 50: 50) in water, 25% by mass ammonia water and 25% by mass sodium hydroxide The aqueous solution was added at a constant rate, and crystallization was carried out for 2 minutes and 30 seconds while controlling the pH value to 12.6 (nucleation pH).

Thereafter, until the pH value reaches 11.6 (nuclear growth pH) based on the liquid temperature of 25 ° C., only the supply of the 25 mass% sodium hydroxide aqueous solution is temporarily stopped, and the pH value becomes 11.6 based on the liquid temperature of 25 ° C. Then, the supply of the 25 mass% sodium hydroxide aqueous solution was resumed. Crystallization is continued for 2 hours while controlling the pH value to 11.6 and the fluctuation range within the range of 0.2 above and below the set value. When the reaction layer is full, the crystallization is stopped and stirring is stopped. The product was allowed to settle to allow precipitation of the product. After extracting half of the supernatant, crystallization was resumed.
After further crystallization for 2 hours (4 hours in total), the crystallization was terminated, and the product was washed with water, filtered and dried. By the method described above, composite hydroxide particles represented by Ni _0.50 Mn _0.50 (OH) _{2 + α} (0 ≦ α ≦ 0.5) were obtained.

[Coating process]
In order to coat the obtained particles with tungsten and have a molar ratio of Ni: Mn: W = 49.75: 49.75: 0.5, 500 mL so that the slurry concentration at the end of coating is 200 g / L. In a beaker, 100 g of hydroxide particles, water, and 37 ml of a 30 g / L ammonium tungstate aqueous solution were mixed. After adding 3.7% of 25% by mass of ammonia water as 10% by volume of the aqueous solution of ammonium tungstate, coating was performed by adding 8% by mass of sulfuric acid so that the final pH value was 8.5 at room temperature.
Thereafter, the entire amount of the hydroxide slurry in the container was collected by filtration, washed with water and dried at 120 ° C. for 12 hours or more, and Ni _0.498 Mn _0.498 W _0.005 (OH) _{2 + α} (0 ≦ A composite hydroxide represented by α ≦ 0.5) was obtained. The specific surface area as measured by the BET method was 20.2 m ² / g.

[Positive electrode active material manufacturing process]
<Heat treatment process>
The composite hydroxide was heat-treated at 700 ° C. for 6 hours in an air stream (oxygen concentration: 21% by volume) to obtain a composite oxide.

<Mixing process>
Lithium carbonate was weighed so that the obtained composite oxide would have Li / Me = 1.35, and thoroughly mixed using a shaker mixer device (TURBULA Type T2C manufactured by Willy et Bacofen (WAB)). A mixture was obtained.

<Baking process>
The obtained lithium mixture was calcined in air (oxygen concentration: 21% by volume) at 400 ° C. for 4 hours, calcined at 980 ° C. for 10 hours, further pulverized, and positive electrode for non-aqueous electrolyte secondary battery An active material was obtained.
The composition of the positive electrode active material was Li _1.35 Ni _0.498 Mn _0.498 W _0.005 O ₂ .
Moreover, the specific surface area by BET method measurement was 1.4 m < ² > / g.
Table 2 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. FIG. 7 shows the results of observation of the positive electrode active material by SEM (scanning electron microscope JSM-6360LA, manufactured by JEOL Ltd.).

In the coating step, the mixture was mixed so that the molar ratio was Ni: Mn: W = 47.5: 47.5: 5, and 37 ml corresponding to 10% by volume of 370 ml of ammonium tungstate aqueous solution was added to 25 mass% ammonia water. Except for the above, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 6.
The composition of the obtained composite hydroxide is Ni _0.475 Mn _0.475 W _0.05 (OH) _{2 + α} (0 ≦ α ≦ 0.5), and the composition of the positive electrode active material is Li _1.35. It was _{Ni 0.475 Mn 0.475 W 0.05 O 2} .
The specific surface area as measured by the BET method was 21.9 m ² / g for the composite hydroxide and 1.5 m ² / g for the positive electrode active material.
Table 2 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

A positive electrode for a non-aqueous electrolyte secondary battery in the same manner as in Example 6 except that mixing was performed so that the molar ratio of Ni: Mn: Al: W = 48.3: 48.3: 3: 0.5 in the coating step. An active material was obtained and evaluated.
The composition of the obtained composite hydroxide is Ni _0.483 Mn _0.483 Al _0.03 W _0.005 (OH) _{2 + α} (0 ≦ α ≦ 0.5), and the composition of the positive electrode active material is was _{Li 1.35 Ni 0.483 Mn 0.483 Al 0.03} W 0.005 O 2.
The specific surface area as measured by the BET method was 26.3 m ² / g for the composite hydroxide and 1.4 m ² / g for the positive electrode active material.
Table 2 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

(Comparative Example 2)
A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 6 except for controlling so that the final pH value was 11 in the coating step.
No precipitation of tungsten occurs, the composition of the obtained composite hydroxide is Ni _0.50 Mn _0.50 (OH) _{2 + α} (0 ≦ α ≦ 0.5), and the composition of the positive electrode active material is Li _{It was 1.35} Ni _0.50 Mn _0.50 O ₂ .
Further, the BET specific surface area measurement, the composite hydroxide is 21.1m ² / g, was the positive electrode active material 1.3 m ² / g.
Table 2 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

(Comparative Example 3)
A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 6 except for controlling so that the final pH value was 5 in the coating step.
Since some of the hydroxide particles were dissolved in the coating step, the subsequent steps were interrupted. The specific surface area of the composite hydroxide as measured by the BET method after the coating step was 31.5 m ² / g.

(Evaluation)
Examples 6 to 8 having the average particle size and particle size distribution of the present invention and having tungsten added have high capacity and low positive electrode resistance, and are suitable as positive electrode active materials for nonaqueous electrolyte secondary batteries. I understand. On the other hand, it can be seen that Comparative Example 2 in which no tungsten was added had a significantly high positive electrode resistance and had a problem as a positive electrode active material for a non-aqueous electrolyte secondary battery.

  The mixed aqueous solution was prepared and crystallized so that the metal element had a molar ratio of Ni: Co: Mn = 33: 33: 33 in the composite hydroxide production process, and the molar ratio of Ni: Co: Mn in the coating process. : W = 33.1: 33.1: 33.1: Li / Me = 1.15 without performing the heat treatment step in the positive electrode active material manufacturing process. A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 6 except that the calcining temperature was 760 ° C. and the calcining temperature was 900 ° C.

The composition of the obtained composite hydroxide is Ni _0.331 Co _0.331 Mn _0.331 W _0.005 (OH) _{2 + α} (0 ≦ α ≦ 0.5), and the composition of the positive electrode active material is Li _1.15 Ni _0.331 Co _0.331 Mn _0.331 W _0.005 O ₂ .
The specific surface area as measured by the BET method was 19.1 m ² / g for the composite hydroxide and 1.0 m ² / g for the positive electrode active material.
Table 3 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

  In the coating step, the mixture was mixed so that the molar ratio of Ni: Co: Mn: W was 31.7: 31.7: 31.7: 5, and 25% by mass of ammonia water was added to 1% by volume of 370 ml of ammonium tungstate aqueous solution. A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 9 except that the corresponding 3.7 ml was added.

Since some amount of tungsten remained in the slurry, the composition of the obtained composite hydroxide was Ni _0.321 Co _0.321 Mn _0.321 W _0.036 (OH) _{2 + α} (0 ≦ α ≦ 0.5) The composition of the positive electrode active material was Li _1.15 Ni _0.321 Co _0.321 Mn _0.321 W _0.036 O ₂ .
Further, the BET specific surface area measurement, the composite hydroxide is 19.3 m ² / g, was the positive electrode active material 1.1 m ² / g.
Table 3 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

Non-aqueous system in the same manner as in Example 9 except that Ni: Co: Mn: Al: W in the coating step was mixed so as to be 32.2: 32.2: 32.2: 3: 0.5. A positive electrode active material for an electrolyte secondary battery was obtained and evaluated.
The composition of the obtained composite hydroxide is Ni _0.322 Co _0.322 Mn _0.322 Al _0.03 W _0.005 (OH) _{2 + α} (0 ≦ α ≦ 0.5), and the positive electrode active material The composition of was Li _1.15 Ni _0.322 Co _0.321 Mn _0.322 Al _0.03 W _0.005 O ₂ .
Further, the BET specific surface area measurement, the composite hydroxide is 18.2M ² / g, it was the positive electrode active material 0.97 m ² / g.
Table 3 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

In the coating step, sodium tungstate is used instead of ammonium tungstate and mixed so that the molar ratio of Ni: Co: Mn: Al: W is 32.2: 32.2: 32.2: 3: 0.5 Then, a positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 11 except that ammonia was not added.
The composition of the obtained composite hydroxide is Ni _0.322 Co _0.322 Mn _0.322 Al _0.03 W _0.005 (OH) _{2 + α} (0 ≦ α ≦ 0.5), and the positive electrode active material The composition of was Li _1.15 Ni _0.322 Co _0.322 Mn _0.322 Al _0.03 W _0.005 O ₂ .
The specific surface area as measured by the BET method was 19.5 m ² / g for the composite hydroxide and 1.1 m ² / g for the positive electrode active material.
Table 3 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

(Comparative Example 4)
Pure water and 25% by weight sodium hydroxide aqueous solution (reagent special grade, Wako Pure Chemical Industries, Ltd.) so that the pH becomes 11.3 in a 5 liter cylindrical reaction vessel (modified stainless steel cylindrical container) equipped with a stirrer and overflow pipe (Made by Co., Ltd.) was added, and the temperature was maintained at 35 ° C. and stirring was performed at a constant speed. Next, a nickel sulfate solution (reagent special grade, manufactured by Wako Pure Chemical Industries, Ltd.), sulfuric acid which is mixed so that the atomic ratio of Ni: Co: Mn is 1: 1: 1 and the total salt concentration is 2 mol / L, sulfuric acid A mixed solution of cobalt solution (reagent special grade, manufactured by Wako Pure Chemical Industries, Ltd.) and manganese sulfate solution (reagent special grade, manufactured by Wako Pure Chemical Industries, Ltd.) is added at a flow rate of 4 ml / min. 25% by mass aqueous ammonia (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was added to the reaction vessel at a flow rate of 0.4 ml / min. Furthermore, the nickel / cobalt / manganese composite hydroxide is controlled by intermittently adding a 25% by mass aqueous sodium hydroxide solution so that the pH value of the reaction solution becomes 11.5 to 12.0 based on the liquid temperature of 25 ° C. Particles were formed.

After the reaction vessel is in a steady state, nickel / cobalt / manganese composite hydroxide particles are continuously collected from the overflow pipe, washed with water, filtered, and air-dried at 120 ° C. for 24 hours to obtain nickel / cobalt. -Manganese composite hydroxide particles were obtained. As a result of measuring the pH of the aqueous solution after the reaction, it was 11.85 based on the liquid temperature of 25 ° C.
Subsequent steps were carried out in the same manner as in Example 9 to obtain and evaluate a positive electrode active material for a non-aqueous electrolyte secondary battery.

The composition of the obtained composite hydroxide is Ni _0.332 Co _0.332 Mn _0.332 W _0.005 (OH) _{2 + α} (0 ≦ α ≦ 0.5), and the composition of the positive electrode active material is It was Li _1.15 Ni _0.332 Co _0.332 Mn _0.332 W _0.005 O ₂ .
Further, the BET specific surface area measurement, the composite hydroxide is 31.8m ² / g, was the positive electrode active material 2.1 m ² / g.
Table 3 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

(Comparative Example 5)
A positive electrode active material for a non-aqueous electrolyte secondary battery was obtained and evaluated in the same manner as in Example 9 except that the coating step was not performed and the composite hydroxide particles were not coated with tungsten.
The composition of the obtained composite hydroxide is Ni _0.333 Co _0.333 Mn _0.333 (OH) _{2 + α} (0 ≦ α ≦ 0.5), and the composition of the positive electrode active material is Li _1.15. It was _{Ni 0.333 Co 0.333 Mn 0.333 O 2} .
The specific surface area as measured by the BET method was 19.7 m ² / g for the composite hydroxide and 1.5 m ² / g for the positive electrode active material.
Table 3 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

(Comparative Example 6)
In the coating step, the mixture was mixed so that the molar ratio of Ni: Co: Mn: Al = 32.3: 32.3: 32.3: 3 and non-ammonia water was not added. A positive electrode active material for an aqueous electrolyte secondary battery was obtained and evaluated.
The composition of the obtained composite hydroxide is Ni _0.323 Co _0.323 Mn _0.323 Al _0.03 (OH) _{2 + α} (0 ≦ α ≦ 0.5), and the composition of the positive electrode active material is It was Li _1.15 Ni _0.32 Co _0.32 Mn _0.32 Al _0.03 O ₂ .
Further, the BET specific surface area measurement, the composite hydroxide is 20.5 m ² / g, was the positive electrode active material 1.6 m ² / g.
Table 3 shows the average particle diameter, [(d ₉₀ -d ₁₀ ) / average particle diameter] value, positive electrode resistance value, and thermal stability of the obtained composite hydroxide and the positive electrode active material for a non-aqueous electrolyte secondary battery. Show.

(Evaluation)
Examples 9 to 12 having the average particle size and particle size distribution of the present invention and having tungsten added have high capacity and low positive electrode resistance, and are suitable as positive electrode active materials for non-aqueous electrolyte secondary batteries. I understand.
On the other hand, Comparative Example 4 having a large average particle size and a wide particle size distribution shows that although the battery capacity is similar, the positive electrode resistance is high and the output characteristics are not sufficient. Moreover, it turns out that the comparative examples 5 and 6 which do not add tungsten have a high positive electrode resistance significantly, and have a problem as a positive electrode active material for non-aqueous electrolyte secondary batteries.

B Coin type battery 1 Positive electrode 2 Negative electrode 3 Separator 4 Gasket 5 Positive electrode can 6 Negative electrode can

Claims (8)

Formula _{(2): Li 1 + u} M x W s A t O 2 (-0.05 ≦ u ≦ 0.50, x + s + t = 1,0 <s ≦ 0.05,0 <s + t ≦ 0.15, M is A transition metal containing one or more selected from Ni, Co, and Mn, A is represented by a transition metal element other than M and W, at least one additive element selected from group 2, element, or group 13 element), A positive electrode active material for a non-aqueous electrolyte secondary battery comprising a lithium transition metal composite oxide having a hexagonal crystal structure having a layered structure,
The positive electrode active for a non-aqueous electrolyte secondary battery, wherein the average particle size is 3 to 6 μm and the index [(d ₉₀ −d ₁₀ ) / average particle size] indicating the spread of the particle size distribution is 0.60 or less material. ^{2. The} positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the specific surface area is 0.5 to 2.0 m ² / g.   3. The additive element according to claim 1, wherein the additive element is at least one selected from B, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, and Mo. Positive electrode active material for non-aqueous electrolyte secondary battery.   The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 3, wherein the additive element is at least aluminum.   5. The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein M in the general formula (2) includes at least Ni and Co. 6.   5. The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein M in the general formula (2) contains at least Ni and Mn.   The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein s + t in the general formula (2) satisfies 0.02 <s + t ≦ 0.15.   A positive electrode is formed with the positive electrode active material for nonaqueous electrolyte secondary batteries of any one of Claims 1-7, The nonaqueous electrolyte secondary battery characterized by the above-mentioned.