JP2023016676A - Positive electrode active material for non-aqueous electrolyte secondary battery and manufacturing method thereof - Google Patents

Abstract

To provide a positive electrode active material for a non-aqueous electrolyte secondary battery that exhibits excellent output characteristics in a non-aqueous electrolyte secondary battery.SOLUTION: A positive electrode active material for a non-aqueous electrolyte secondary battery includes particles containing a lithium-transition metal composite oxide and an aluminum compound having an average particle size of 1 nm or more and less than 500 nm. The positive electrode active material for the non-aqueous electrolyte secondary battery has a volume average particle size of 1 μm or more and 8 μm or less and a specific surface area of 1.4 m2/g or more.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a positive electrode active material for non-aqueous electrolyte secondary batteries and a method for producing the same.

High output characteristics are required for positive electrode active materials for non-aqueous electrolyte secondary batteries for use in large power equipment such as electric vehicles. A positive electrode active material having a secondary particle structure in which many primary particles are aggregated is considered effective for obtaining high output characteristics. In this regard, a lithium-containing transition metal composite oxide has been proposed in which the abundance ratio of lithium to oxygen differs between the surface and the interior of secondary particles (see, for example, Patent Document 1). A lithium transition metal oxide having an alumina coating layer on its surface has also been proposed (see, for example, Patent Document 2).

JP 2019-99410 A Japanese Patent Publication No. 2016-538694

An object of one aspect of the present disclosure is to provide a positive electrode active material for a non-aqueous electrolyte secondary battery that has excellent output characteristics in a non-aqueous electrolyte secondary battery, and a method for producing the same.

A first aspect is a positive electrode active material for a non-aqueous electrolyte secondary battery containing particles containing a lithium-transition metal composite oxide and an aluminum compound having an average particle size of 1 nm or more and less than 500 nm. The positive electrode active material for non-aqueous electrolyte secondary batteries has a volume average particle diameter of 1 μm or more and 8 μm or less and a specific surface area of 1.4 m ² /g or more.

In a second aspect, particles containing a lithium-transition metal composite oxide are prepared, and particles containing the lithium-transition metal composite oxide and an aluminum compound having an average particle size of 1 nm or more and less than 500 nm are mixed to obtain a mixture. and a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery. The particles containing the lithium-transition metal composite oxide have a volume average particle diameter of 1 μm or more and 8 μm or less and a specific surface area of 1.3 m ² /g or more.

According to one aspect of the present disclosure, it is possible to provide a positive electrode active material for a non-aqueous electrolyte secondary battery that exhibits excellent output characteristics in a non-aqueous electrolyte secondary battery, and a method for producing the same.

1 is an example of a scanning electron microscope (SEM) image of a positive electrode active material according to Example 1. FIG. 4 is an example of a SEM image of a positive electrode active material according to Reference Example 1. FIG.

In this specification, the term "process" is not only an independent process, but even if it cannot be clearly distinguished from other processes, it is included in this term as long as the intended purpose of the process is achieved. . In addition, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless otherwise specified when there are multiple substances corresponding to each component in the composition. Furthermore, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined. Embodiments of the present invention are described in detail herein below. However, the embodiments shown below exemplify the positive electrode active material for non-aqueous electrolyte secondary batteries and the method for producing the same for embodying the technical idea of the present invention. It is not limited to the positive electrode active material for non-aqueous electrolyte secondary batteries and the manufacturing method thereof.

Positive electrode active material for non-aqueous electrolyte secondary battery A positive electrode active material for non-aqueous electrolyte secondary battery contains particles containing a lithium transition metal composite oxide and an aluminum compound having an average particle size of 1 nm or more and less than 500 nm, and has a volume. It has an average particle size of 1 μm or more and 8 μm or less and a specific surface area of 1.4 m ² /g or more. The positive electrode active material for non-aqueous electrolyte secondary batteries can be efficiently produced, for example, by a method for producing a positive electrode active material for non-aqueous electrolyte secondary batteries, which will be described later.

The positive electrode active material for non-aqueous electrolyte secondary batteries (hereinafter also simply referred to as "positive electrode active material") has a relatively small particle size and a large specific surface area. Excellent output characteristics, such as reduced DC resistance in low temperature environments, can be achieved. In addition, by containing an aluminum compound, the fluidity as a powder is excellent in spite of the large specific surface area. It can be considered that this is because, for example, the inclusion of an aluminum compound increases steric hindrance between particles and suppresses agglomeration.

From the viewpoint of output characteristics in a nonaqueous electrolyte secondary battery, the positive electrode active material may have a volume average particle size of 1 μm or more and 8 μm or less, preferably 1.2 μm or more, 1.5 μm or more, 2 μm or more, and 2.5 μm. 3 μm or more, or 3.5 μm or more, and preferably 6 μm or less, 5 μm or less, 4.7 μm or less, or 4.5 μm or less. In one aspect, the volume average particle size may be 2 μm or more and 6 μm or less. The volume average particle diameter of the positive electrode active material is determined as the particle diameter corresponding to 50% of the cumulative volume from the small diameter side in the volume-based cumulative particle size distribution. The volume-based cumulative particle size distribution is measured by, for example, a laser diffraction particle size distribution analyzer.

From the viewpoint of output characteristics in a non-aqueous electrolyte secondary battery, the positive electrode active material may have a specific surface area of 1.4 m ² /g or more, preferably 1.7 m ² /g or more, as measured by the BET method. .9 m ² /g or greater, 2.0 m ² /g or greater, or 2.5 m ² /g or greater. Further, the specific surface area may be, for example, 4.0 m ² /g or less, preferably 3.8 m ² /g or less, 3.3 m ² /g or less, or 3.0 m ² /g or less. . In one aspect, the specific surface area of the positive electrode active material may be, for example, 1.7 m ² /g or more and 3.8 m ² /g or less, preferably 1.7 m ² /g or more and 3.3 m ² /g or less, or It may be 1.9 m ² /g or more and 3.0 m ² /g or less. The specific surface area measured by the BET method is measured by a one-point method using nitrogen gas based on the BET (Brunauer Emmett Teller) theory.

From the viewpoint of fluidity, the positive electrode active material may have an angle of repose as a powder of, for example, less than 70°, preferably 68° or less, or 67° or less. The lower limit of the angle of repose may be, for example, 50° or more, or 60° or more. In addition, from the viewpoint of fluidity, the positive electrode active material may have a powder collapse angle of, for example, less than 68°, preferably 66° or less, or 61° or less. The lower limit of the collapse angle may be, for example, 40° or more, or 45° or more. Furthermore, from the viewpoint of fluidity, the positive electrode active material may have a differential angle obtained by subtracting the collapse angle from the repose angle, for example, 3° or more, preferably 6° or more, or 8° or more. The upper limit of the difference angle may be, for example, 25° or less, or 20° or less.

Here, the “angle of repose (θ1)” means the angle of inclination when the positive electrode active material powder is deposited on the measurement table. As a method of depositing the powder of the positive electrode active material, a general injection method can be mentioned. Also, the “collapse angle (θ2)” means the tilt angle measured after applying a predetermined impact force to the measurement table after measuring the repose angle (θ1). For measuring the angle of repose (θ1) and the angle of collapse (θ2), for example, a powder property measuring instrument (for example, Powder Tester (registered trademark); manufactured by Hosokawa Micron Corporation) can be used.

Specific methods for measuring the angle of repose (θ1) and the angle of collapse (θ2) are as follows.

[Method for measuring angle of repose]
Drop the powder to be measured from a funnel of a predetermined height onto a horizontal substrate (measurement table), calculate the base angle from the diameter and height of the generated conical deposit, and rest this base angle angled. Generally, it can be measured based on JIS-R9301-2-2.

[Method for measuring collapse angle]
After collapsing the cone-shaped deposit whose repose angle was measured by applying a predetermined impact to the measurement table three times, the base angle was calculated from the diameter and height of the cone-shaped deposit, and this base angle was used as the collapse angle. and Here, the predetermined impact is the impact adopted in the measuring device used, and is unique and constant to the device.

[Method of measuring difference angle]
The difference angle was calculated by the following formula.
Angle of repose (°) - angle of collapse (°) = angle of difference (°)

Lithium transition metal composite oxide Particles containing a lithium transition metal composite oxide constituting a positive electrode active material (hereinafter also simply referred to as "lithium transition metal composite oxide particles") are, for example, primary lithium transition metal composite oxides containing Secondary particles may be formed by aggregating a plurality of particles. When the lithium-transition metal composite oxide particles have a predetermined volume-average particle size and specific surface area, output characteristics are improved in a non-aqueous electrolyte secondary battery constructed using a positive electrode active material containing this. Therefore, in one aspect, the positive electrode active material may consist of lithium-transition metal composite oxide particles having a predetermined volume-average particle size and specific surface area.

The volume average particle diameter (D50) of the lithium-transition metal composite oxide particles may be, for example, 1 μm or more and 8 μm or less, preferably 1.2 μm or more, 1.5 μm or more, 2 μm or more, 2.5 μm or more, 3 μm or more, or 3.5 μm or more, and preferably 6 μm or less, 5 μm or less, 4.7 μm or less, or 4.5 μm or less. In one aspect, the volume average particle size may be 2 μm or more and 6 μm or less. When the volume average particle diameter of the lithium-transition metal composite oxide particles is within the above range, the fluidity as a positive electrode active material is good, and the output characteristics may be further improved when constructing a non-aqueous electrolyte secondary battery. be. Here, the volume average particle diameter of the lithium-transition metal composite oxide particles is obtained as a particle diameter corresponding to 50% of the cumulative volume from the small diameter side in the volume-based cumulative particle size distribution, similarly to the positive electrode active material.

The positive electrode active material is composed of lithium-transition metal composite oxide particles and aluminum compound nanoparticles. Therefore, the volume average particle diameter of the lithium-transition metal composite oxide particles may be approximately the same as the volume average particle diameter of the positive electrode active material.

The lithium-transition metal composite oxide particles are formed by assembling a plurality of primary particles. The average particle diameter D _SEM of the primary particles based on electron microscopic observation is, for example, 0.1 μm or more and 1.5 μm or less, preferably 0.12 μm or more, more preferably 0.15 μm or more. Also, the average particle diameter D _SEM of the primary particles based on electron microscopic observation is preferably 1.2 μm or less, more preferably 1.0 μm or less. When the average particle diameter of the primary particles based on electron microscopic observation is within the above range, the output may be improved when constructing a non-aqueous electrolyte secondary battery.

The specific surface area of the lithium-transition metal composite oxide particles measured by the BET method may be 1.3 m ² /g or more, preferably 1.5 m ² /g, from the viewpoint of output characteristics in a non-aqueous electrolyte secondary battery. g or more, 1.7 m ² /g or more, or 1.9 m ² /g or more. Further, the specific surface area may be, for example, 3.9 m ² /g or less, preferably 3.5 m ² /g or less, 3.3 m ² /g or less, or 2.8 m ² /g or less. . When the specific surface area of the lithium-transition metal composite oxide particles is within the above range, the output characteristics may be further improved, and the fluidity-improving effect when the aluminum compound is added may be greater.

The positive electrode active material is composed of secondary particles, which are particles containing a lithium-transition metal composite oxide, and nanoparticles of an aluminum compound. Therefore, the specific surface area of the lithium-transition metal composite oxide particles is approximately the same as the specific surface area of the positive electrode active material, or 80% or more and 110% or less of the specific surface area of the positive electrode active material. good.

The lithium-transition metal composite oxide particles may be secondary particles formed by aggregating a plurality of primary particles and have voids therein. Thereby, a predetermined specific surface area can be easily achieved, and the output characteristics of the non-aqueous electrolyte secondary battery may be further improved. Whether the lithium-transition metal composite oxide particles have internal voids can be evaluated, for example, from a cross-sectional image thereof. Cross-sectional images of particles can be obtained, for example, using a scanning electron microscope (SEM).

When the lithium-transition metal composite oxide particles have voids inside, the degree of voids can be evaluated, for example, by porosity. The porosity is an index of the existence ratio of voids formed inside the secondary particles composed of the lithium-transition metal composite oxide, and is measured by cross-sectional observation of the secondary particles. The porosity of the lithium-transition metal composite oxide particles may be, for example, 15% or more and 50% or less, or 20% or more and 50% or less. By controlling the porosity within this range, even with the same specific surface area, the contact area with the electrolyte can be increased, making it possible to obtain a positive electrode active material with more excellent output characteristics. As a result, a secondary battery having an improved output density per volume can be obtained. The porosity of the lithium-transition metal composite oxide particles is preferably 25% or more and 45% or less, may be 27% or more, 29% or more, or 30% or more, and may be 40% or less, or 38% or less. can be

The porosity of the secondary particles can be measured by observing arbitrary cross sections of the secondary particles using a scanning electron microscope (SEM) and analyzing the images. Specifically, a plurality of secondary particles are embedded in resin or the like, a cross-sectional sample is prepared by cross-section polishing or the like, and the cross-sectional observation of the secondary particles is made possible with a scanning electron microscope. After that, 100 secondary particles whose cross-sectional size is within the volume average particle size (D50) of the lithium-transition metal composite oxide particles±1 μm are arbitrarily selected. For each secondary particle, image analysis software (e.g., HALCON; manufactured by MVTec) is used to detect the void portion (space portion) in the secondary particle in white, and the dense portion in the contour of the secondary particle in black. to detect. Calculate the total area of the white part and the total area of the black part of the selected 100 secondary particles, respectively, and the area ratio of the space part to the cross-sectional area of the secondary particle [white part / (white part + black part)] By calculating the porosity can be calculated. The porosity of the secondary particles of the positive electrode active material for a non-aqueous electrolyte secondary battery containing an aluminum compound is equivalent to the porosity of the secondary particles (base material) made of the lithium-transition metal composite oxide.

The lithium-transition metal composite oxide that constitutes the positive electrode active material may contain, for example, lithium (Li) and nickel (Ni) in its composition and have a layered structure. The lithium-transition metal composite oxide may contain at least lithium (Li) and nickel (Ni), and may further contain cobalt (Co). Also, the lithium-transition metal composite oxide may further contain at least one first metal element selected from the group consisting of aluminum (Al) and manganese (Mn). In addition to these, lithium transition metal composite oxides include magnesium (Mg), calcium (Ca), titanium (Ti), zirconium (Zr), niobium (Nb), tantalum (Ta), chromium (Cr), Molybdenum (Mo), Tungsten (W), Iron (Fe), Copper (Cu), Silicon (Si), Tin (Sn), Bismuth (Bi), Gallium (Ga), Yttrium (Y), Samarium (Sm), It may further contain at least one second metal element selected from the group consisting of erbium (Er), cerium (Ce), neodymium (Nd), lanthanum (La), cadmium (Cd) and lutetium (Lu). . The second metal element is at least one selected from the group consisting of zirconium (Zr), titanium (Ti), magnesium (Mg), tantalum (Ta), niobium (Nb), molybdenum (Mo) and tungsten (W). may be

In the lithium-transition metal composite oxide, the ratio of the number of moles of nickel to the total number of moles of metal elements other than lithium may be, for example, greater than 0, preferably 0.33 or more. The ratio of the number of moles of nickel to the total number of moles of metal elements other than lithium may be 0.4 or more and 0.45 or more. Also, the ratio of the number of moles of nickel to the total number of moles of metal elements other than lithium may be, for example, less than 1, preferably 0.95 or less, 0.8 or less, or 0.6 or less. When the molar ratio of nickel is within the range described above, it is possible to achieve both charge/discharge capacity and cycle characteristics at high voltage in the non-aqueous electrolyte secondary battery.

When the lithium-transition metal composite oxide contains cobalt, the ratio of the number of moles of cobalt to the total number of moles of metal elements other than lithium may be, for example, greater than 0, preferably 0.01, and more preferably 0. It may be .02 or greater, 0.05 or greater, 0.1 or greater, or 0.15 or greater. Also, the ratio of the number of moles of cobalt to the total number of moles of metal elements other than lithium may be, for example, less than 1, preferably 0.6 or less, 0.4 or less, or 0.35 or less. Also, the ratio of the number of moles of cobalt to the total number of moles of metal elements other than lithium may be 0.33 or less, 0.3 or less, or 0.25 or less. When the molar ratio of cobalt is within the above range, the non-aqueous electrolyte secondary battery can achieve sufficient charge/discharge capacity at high voltage.

When the lithium-transition metal composite oxide contains at least one of manganese and aluminum, the ratio of the total number of moles of manganese and aluminum to the total number of moles of metal elements other than lithium is, for example, greater than 0, preferably 0.01 or more. and more preferably 0.05 or more, 0.1 or more, or 0.15 or more. Also, the ratio of the total number of moles of manganese and aluminum to the total number of moles of metal elements other than lithium may be, for example, 0.6 or less, preferably 0.35 or less. Also, the ratio of the total number of moles of manganese and aluminum to the total number of moles of metal elements other than lithium may be 0.33 or less, or 0.3 or less. When the total molar ratio of manganese and aluminum is within the range described above, it is possible to achieve both charge/discharge capacity and safety in the non-aqueous electrolyte secondary battery.

In the lithium-transition metal composite oxide, the ratio of the number of moles of lithium to the total number of moles of metal elements other than lithium may be, for example, 0.95 or more, preferably 1.0 or more, 1.03 or more, or It may be 1.05 or more. Further, the ratio of the number of moles of lithium to the total number of moles of metal elements other than lithium may be, for example, 1.5 or less, preferably 1.3 or less, 1.25 or less, or 1.2 or less. . When the molar ratio of lithium is 0.95 or more, the resulting Since the interfacial resistance is suppressed, the output of the non-aqueous electrolyte secondary battery tends to improve. On the other hand, when the molar ratio of lithium is 1.5 or less, the initial discharge capacity tends to improve when the positive electrode active material is used for the positive electrode of a non-aqueous electrolyte secondary battery.

When the lithium-transition metal composite oxide contains cobalt and manganese in addition to nickel, the molar ratio of nickel, cobalt and manganese is, for example, nickel:cobalt:manganese=(0.33 to 0.95):( 0.02 to 0.6):(0.01 to 0.35), preferably (0.33 to 0.8):(0.05 to 0.35):(0.05 to 0.35). When the lithium-transition metal composite oxide contains cobalt and manganese and aluminum in addition to nickel, the molar ratio of nickel, cobalt and (manganese + aluminum) is, for example, nickel: cobalt: (manganese + aluminum) = ( 0.33 to 0.95):(0.02 to 0.6):(0.01 to 0.35), preferably (0.33 to 0.8):(0.05 to 0.35): (0.05 to 0.35).

When the lithium-transition metal composite oxide contains at least one second metal element, the ratio of the total number of moles of the second metal element to the total number of moles of the metal elements other than lithium may be, for example, greater than 0, preferably may be 0.001 or greater, or 0.003 or greater. Also, the ratio of the total number of moles of the second metal element to the total number of moles of the metal elements other than lithium may be, for example, 0.05 or less, preferably 0.02 or less, or 0.015 or less. When tungsten is particularly included as the second metal element, the ratio of the number of moles of tungsten to the total number of moles of metal elements other than lithium is 0.05 or more and 0.15 or less, so that the particles have a higher porosity. tend to be able to

The lithium-transition metal composite oxide may have, for example, a composition represented by the following formula (1). The lithium-transition metal composite oxide may have a layered structure and may have a hexagonal crystal structure.
_{LipNixCoyM1zM2wO2 + α} ^{( 1} _{) _ _}

Here, p, x, y, z, w and α are 1.0≤p≤1.3, 0≤x≤1, 0≤y≤1, 0≤z≤1, 0≤w≤0. 05, x+y+z+w=1, satisfies −0.1≦α≦0.1. x, y, z and w may satisfy 0<x<1, 0≤y≤0.6, 0≤z≤0.6, 0≤w≤0.05, and 0.33≤x≤0 .95, 0.01 ≤ y ≤ 0.6, 0 ≤ z ≤ 0.35, 0 ≤ w ≤ 0.05, 0.33 ≤ x ≤ 0.8, 0.02 ≤ y ≤ 0 .35, 0.05≤z≤0.35, 0≤w≤0.02.

M ¹ may represent at least one of Mn and Al. ^M2 is from Mg, Ca, Ti, Zr, Nb, Ta, Cr, Mo, W, Fe, Cu, Si, Sn, Bi, Ga, Y, Sm, Er, Ce, Nd, La, Cd and Lu At least one selected from the group consisting of Zr, Ti, Mg, Ta, Nb, Mo and W may be represented.

The content of the lithium-transition metal composite oxide particles in the positive electrode active material may be, for example, 80% by mass or more, preferably 90% by mass or more, or 95% by mass or more. The upper limit of the content of the lithium-transition metal composite oxide particles in the positive electrode active material may be, for example, less than 100% by mass, preferably 99% by mass or less, or 98% by mass or less.

Aluminum Compound The positive electrode active material may contain an aluminum compound in addition to the lithium-transition metal composite oxide particles. The aluminum compound in the positive electrode active material may exist as aluminum compound particles independently of the lithium-transition metal composite oxide particles, and at least a portion of the aluminum compound particles may be present on the surface of the lithium-transition metal composite oxide particles. may be attached to The adhesion of the aluminum compound particles to the surface of the lithium-transition metal composite oxide particles is preferably physical adsorption from the viewpoint of the fluidity of the powder of the positive electrode active material. Physical adsorption may be, for example, due to van der Waals forces and the like. In addition, the adhesion of the aluminum compound particles to the surface of the lithium-transition metal composite oxide particles is accompanied by a chemical reaction between the aluminum compound and the lithium-transition metal composite oxide from the viewpoint of the fluidity of the powder of the positive electrode active material. preferably not. The chemical reaction between the aluminum compound and the lithium-transition metal composite oxide is promoted, for example, by heat treatment, mechanochemical treatment, etc. of the mixture of the aluminum compound and the lithium-transition metal composite oxide. Therefore, the positive electrode active material may be a non-heat-treated material containing an aluminum compound and a lithium-transition metal composite oxide. Here, the non-heat-treated material refers to a mixture containing an aluminum compound and a lithium-transition metal composite oxide at a temperature of 300° C. or higher, or 200° C. or higher, for example, for 2 hours or longer, or 30 minutes or longer without heat treatment. It means what you get. When the positive electrode active material is a non-heat-treated material, the effect of improving the fluidity by mixing the aluminum compound may become greater.

Examples of the aluminum compound constituting the positive electrode active material include aluminum oxide (eg, Al ₂ O ₃ ), aluminum hydroxide, aluminum chloride, aluminum nitrate, and aluminum nitride. It is preferred that one species is included. By including a specific aluminum compound, the fluidity of the positive electrode active material as a powder may be further improved while reducing the influence on the output characteristics and the viscosity of the slurry containing the positive electrode active material.

The average particle diameter of the aluminum compound may be, for example, 1 nm or more and less than 500 nm, preferably 2 nm or more, 5 nm or more, or 10 nm or more, from the viewpoint of fluidity as powder of the positive electrode active material. Also, the average particle size may preferably be 300 nm or less, 100 nm or less, or 50 nm or less. When the average particle diameter of the aluminum compound is within the above range, there is a tendency that the process fluidity can be improved more efficiently.

The content of the aluminum compound in the positive electrode active material may be, for example, 2 mol% or less, preferably 1 mol% or less, relative to 1 mol of the lithium-transition metal composite oxide, from the viewpoint of the output characteristics of the non-aqueous electrolyte secondary battery. 0.8 mol % or less, or 1.5 mol % or less. In addition, the content of the aluminum compound in the positive electrode active material may be, for example, 0.01 mol% or more with respect to 1 mol of the lithium-transition metal composite oxide, from the viewpoint of the fluidity of the powder of the positive electrode active material. , preferably 0.05 mol % or more, or 0.1 mol % or more. In one aspect, the content of the aluminum compound in the positive electrode active material may be 0.01 mol % or more and 2 mol % or less with respect to 1 mol of the lithium-transition metal composite oxide.

Tungsten Compound The positive electrode active material may further contain a tungsten compound, and may contain particles of the tungsten compound. When the positive electrode active material contains a tungsten compound, it may be possible to effectively suppress, for example, an increase in the viscosity of the slurry containing the positive electrode active material. In particular, when the lithium-transition metal composite oxide particles have a volume average particle size of 4.7 μm or less and a specific surface area of 1.3 m ² /g or more, the effect of suppressing the viscosity increase tends to be greater. The tungsten compound in the positive electrode active material may exist independently of the lithium-transition metal composite oxide particles, or at least part of the tungsten compound may adhere to the surface of the lithium-transition metal composite oxide particles. Also, at least part of the tungsten compound may react with lithium and be contained in the positive electrode active material in the form of lithium tungstate. The adhesion of the tungsten compound to the surface of the lithium-transition metal composite oxide particles is preferably physical adsorption from the viewpoint of the fluidity of the slurry containing the positive electrode active material.

Tungsten oxide (for example, WO ₃ ) is preferable as the tungsten compound that constitutes the positive electrode active material. By including a specific tungsten compound, it may be possible to more effectively suppress an increase in the viscosity of the slurry containing the positive electrode active material.

The average particle diameter of the tungsten compound may be, for example, 0.05 μm or more and 2 μm or less, preferably 0.25 μm or more, or 0.50 μm or more, from the viewpoint of suppressing the viscosity increase of the slurry containing the positive electrode active material. . Also, the average particle size may preferably be 1.7 μm or less, or 1.5 μm or less. Here, the average particle size of the tungsten compound is measured as the volume average particle size with a laser diffraction particle size distribution analyzer (SALD-3100 manufactured by Shimadzu Corporation).

The content of the tungsten compound in the positive electrode active material may be, for example, 0.1 mol % or more and 2 mol % or less with respect to 1 mol of the lithium-transition metal composite oxide. The content of the tungsten compound in the positive electrode active material is preferably 1.8 mol% or less, or 1.5 mol% or less with respect to 1 mol of the lithium transition metal composite oxide, from the viewpoint of the output characteristics of the non-aqueous electrolyte secondary battery. It may be mol % or less. In addition, the content of the tungsten compound in the positive electrode active material is preferably 0.2 mol% or more, or 0, relative to 1 mol of the lithium transition metal composite oxide, from the viewpoint of suppressing the viscosity increase of the slurry containing the positive electrode active material. .3 mol % or more.

Metal Compound In one aspect, the positive electrode active material may contain another metal compound instead of the aluminum compound. Other metal compounds include tungsten compounds, titanium compounds, zirconium compounds, silicon compounds, magnesium compounds, etc., and may contain at least one selected from the group consisting of these. The other metal compound preferably contains at least one selected from the group consisting of a tungsten compound, a titanium compound, a silicon compound and a magnesium compound, from the viewpoint of achieving both fluidity and output characteristics. is more preferably included at least one tungsten compound. Other metal compounds may be, for example, oxides, hydroxides, nitrides, and the like. Also, the average particle size of the other metal compound may be, for example, 0.01 μm or more and 2 μm or less. The content of the other metal compound in the positive electrode active material may be, for example, 0.1 mol % or more and 2 mol % or less with respect to 1 mol of the lithium-transition metal composite oxide.

Method for producing positive electrode active material for non-aqueous electrolyte secondary battery A method for producing a positive electrode active material for non-aqueous electrolyte secondary battery includes a preparation step of preparing particles containing a lithium-transition metal composite oxide, and a lithium-transition metal composite oxide. and a mixing step of mixing particles containing and an aluminum compound having an average particle size of 1 nm or more and less than 500 nm to obtain a mixture. The prepared particles containing the lithium-transition metal composite oxide may have a volume average particle diameter of 1 μm or more and 8 μm or less and a specific surface area of 1.3 m ² /g or more.

Preparing Step In the preparing step, particles containing a desired lithium-transition metal composite oxide (hereinafter also simply referred to as “lithium-transition metal composite oxide particles”) are prepared. The lithium-transition metal composite oxide particles may be prepared by purchase or the like, or may be prepared by being produced by a method for producing a lithium-transition metal composite oxide, which will be described later. The details and preferred aspects of the prepared lithium-transition metal composite oxide particles are the same as those of the lithium-transition metal composite oxide particles described in the positive electrode active material for non-aqueous electrolyte secondary batteries.

Mixing Step In the mixing step, the lithium-transition metal composite oxide particles and the aluminum compound are mixed to obtain a mixture. The resulting mixture may be a positive electrode active material for non-aqueous electrolyte secondary batteries. Mixing of the lithium-transition metal composite oxide particles and the aluminum compound may be carried out, for example, by dry mixing using a high-speed shear mixer or the like. The temperature for mixing may be, for example, 10° C. or higher and 100° C. or lower, preferably 25° C. or higher and 60° C. or lower.

The average particle size of the aluminum compound used in the mixing step may be, for example, 1 nm or more and less than 500 nm. The details and preferred embodiments of the aluminum compound are as described above.

The amount of the aluminum compound mixed with the lithium-transition metal composite oxide particles in the mixing step may be, for example, 2 mol % or less, preferably 1.8 mol, relative to 1 mol of the lithium-transition metal composite oxide. % or less, or 1.5 mol % or less. The amount of the aluminum compound mixed in the mixing step may be, for example, 0.01 mol% or more, preferably 0.05 mol% or more, or 0.1 mol% or more, relative to 1 mol of the lithium-transition metal composite oxide. can be

The method for producing the positive electrode active material may further include mixing the lithium-transition metal composite oxide particles and the tungsten compound. Mixing of the lithium-transition metal composite oxide particles and the tungsten compound may be performed simultaneously with mixing of the lithium-transition metal composite oxide particles and the aluminum compound, or may be performed separately and sequentially. From the viewpoint of fluidity, it is preferable to mix with the tungsten compound after mixing with the aluminum compound. Mixing of the lithium-transition metal composite oxide particles and the tungsten compound may be carried out, for example, by dry mixing using a high-speed shear mixer or the like. The temperature for mixing may be, for example, 10° C. or higher and 100° C. or lower, preferably 25° C. or higher and 60° C. or lower.

The average particle size of the tungsten compound used for mixing with the lithium-transition metal composite oxide particles may be, for example, 0.05 μm or more and 2 μm or less. The details and preferred aspects of the tungsten compound are as described above.

The amount of the tungsten compound mixed with the lithium-transition metal composite oxide particles may be, for example, 0.1 mol % or more and 2 mol % or less with respect to 1 mol of the lithium-transition metal composite oxide. Preferably, the mixed amount of the tungsten compound may be 1.8 mol% or less, or 1.5 mol% or less, and may be 0.2 mol% or more, or 0 .3 mol % or more.

The method for producing the positive electrode active material may further include a drying step, a granule sizing step, and the like after the mixing step.

The method for producing the positive electrode active material preferably does not include a heat treatment step of heat-treating the mixture containing the lithium-transition metal composite oxide particles and the aluminum compound. Since the heat treatment step is not included, the fluidity of the positive electrode active material can be favorably maintained. Here, the heat treatment step refers to holding the mixture containing the lithium-transition metal composite oxide particles and the aluminum compound at a temperature of, for example, 300° C. or higher, or 200° C. or higher, for, for example, 2 hours or longer, or 30 minutes or longer. means. Therefore, obtaining a mixture at a temperature of, for example, 150° C. or less does not correspond to heat treatment in this specification.

Method for Producing Lithium-Transition Metal Composite Oxide The lithium-transition metal composite oxide particles used in the method for producing the positive electrode active material can be produced, for example, by the following production method. A method for producing a lithium-transition metal composite oxide comprises: a composite oxide preparation step of preparing a composite oxide containing nickel; mixing the composite oxide containing nickel and a lithium compound; and a synthesis step of obtaining a lithium-transition metal composite oxide having a layered structure comprising The lithium-transition metal composite oxide to be produced may contain secondary particles formed by aggregation of a plurality of primary particles containing the lithium-transition metal composite oxide.

Composite Oxide Preparing Step In the composite oxide preparing step, a composite oxide containing nickel (hereinafter also simply referred to as “nickel composite oxide”) is prepared. The prepared nickel composite oxide may contain secondary particles formed by aggregation of a plurality of primary particles containing the nickel composite oxide. The nickel composite oxide may be prepared by purchase or the like, or may be prepared by being manufactured by a nickel composite oxide manufacturing method described later. Details of the prepared nickel composite oxide will be described later.

Synthesis step In the synthesis step, the prepared nickel composite oxide and a lithium compound are mixed to obtain a lithium mixture, and the lithium mixture is heat-treated to obtain a lithium-transition metal composite oxide containing lithium and nickel and having a layered structure. including obtaining In the synthesis step, the lithium transition metal composite oxide may be obtained by diffusing lithium contained in the lithium compound into the nickel composite oxide.

As a method for mixing the nickel composite oxide and the lithium compound, for example, a method of dry-mixing the nickel composite oxide and the lithium compound with a stirring mixer or the like, a slurry of the nickel composite oxide is prepared and mixed with a mixer such as a ball mill. and a method of wet mixing. Examples of lithium compounds include lithium hydroxide, lithium nitrate, lithium carbonate, and mixtures thereof.

The ratio of the number of moles of lithium to the total number of moles of metal elements other than lithium in the lithium mixture (also referred to as the lithium ratio) may be, for example, 0.9 or more and 1.3 or less, preferably 1 or more and 1.2 or less. be. When the lithium ratio is 0.9 or more, the formation of by-products tends to be suppressed. When the lithium ratio is 1.3 or less, the amount of alkali components present on the surface of the lithium mixture is suppressed from increasing, and moisture adsorption due to deliquescence of the alkali components is suppressed, which tends to improve handling.

In mixing a nickel compound oxide and a lithium compound, in addition to the lithium compound, magnesium, calcium, titanium, zirconium, niobium, tantalum, chromium, molybdenum, tungsten, iron, copper, silicon, tin, bismuth, gallium, yttrium , samarium, erbium, cerium, neodymium, lanthanum, cadmium, and lutetium. Examples of compounds containing the second metal element include hydroxides, oxides, and carbonates. The second metal element may be at least one selected from the group consisting of zirconium, titanium, magnesium, tantalum, niobium, molybdenum and tungsten. In particular, when tungsten is contained as the second metal element, particles having a higher porosity can be obtained, and there is a tendency that a battery with high output characteristics can be constructed. Therefore, it is preferable to contain tungsten.

The heat treatment temperature in the synthesis step may be, for example, 650° C. or higher and 990° C. or lower, preferably 700° C. or higher, 730° C. or higher, or 760° C. or higher. Also, the heat treatment temperature may preferably be 960° C. or lower, 940° C. or lower, or 920° C. or lower. Heat treatment of the mixture may be performed at a single temperature, but is preferably performed at a plurality of temperatures from the viewpoint of particle control. When performing heat treatment at a plurality of temperatures, it is desirable, for example, to maintain the first temperature for a predetermined time, then further increase the temperature, and maintain the second temperature for a predetermined time. The first temperature is, for example, 650° C. or higher and 850° C. or lower, preferably 700° C. or higher and 820° C. or lower, and the second temperature is, for example, 730° C. or higher and 960° C. or lower, preferably 760° C. or higher and 920° C. or lower. When the heat treatment temperature is 650° C. or higher, there is a tendency that the increase in the amount of unreacted lithium is suppressed. When the heat treatment temperature is 990° C. or lower, decomposition of the lithium-transition metal composite oxide produced tends to be suppressed. In addition, from the viewpoint of obtaining a lithium-transition metal composite oxide with a high porosity, the heat treatment is preferably performed at a temperature of 800° C. or higher and 980° C. or lower for 8 hours or longer, and more preferably at a temperature of 810° C. or higher and 920° C. or lower for 8 hours or longer. Preferably, the heat treatment time may be, for example, 20 hours or less. The heat treatment time may be, for example, 2 hours or more, preferably 4 hours or more, or 6 hours or more, as the time to maintain the maximum temperature. The heat treatment time may be, for example, 20 hours or less, preferably 18 hours or less, or 12 hours or less. When heat treatment is performed at a plurality of temperatures, it may be 1 hour or more and 19 hours or less. The heat treatment atmosphere may be in the presence of oxygen, preferably an atmosphere containing 10% by volume or more and 100% by volume or less of oxygen.

In the method for producing the lithium-transition metal composite oxide, after the synthesis step, the heat-treated product obtained may be subjected to treatment such as coarse crushing, pulverization, dry sieving, etc., if necessary.

Method for producing nickel composite oxide A method for producing a nickel composite oxide includes, for example, a first solution preparation step of preparing a first solution containing nickel ions and, if necessary, cobalt ions, etc., and a first solution containing a complex ion-forming factor. a second solution preparation step of preparing two solutions; a liquid medium preparation step of preparing a liquid medium having a pH in the range of 10 or more and 13.5 or less; Simultaneously supplying the and a composite hydroxide heat treatment step of heat-treating the composite hydroxide to obtain a nickel composite oxide. For details of a method for obtaining such a composite oxide, see, for example, JP-A-2003-292322 and JP-A-2011-116580 (US Patent Application Publication No. 2012/270107). can.

First Solution Preparing Step In the first solution preparing step, a first solution containing nickel ions and optionally cobalt ions and the like is prepared. The first solution is prepared by dissolving a predetermined amount of salt containing each metal element in water according to the composition of the target nickel composite oxide. Types of salts include nitrates, sulfates, hydrochlorides, and the like. Also, an acidic substance (for example, an aqueous solution of sulfuric acid) may be added to water when preparing the first solution. This may facilitate dissolution of the salt containing each metal element. In the preparation of the first solution, a basic substance may be further added to adjust the pH. Also, the total number of moles of the metal elements such as nickel in the first solution may be appropriately set according to the target average particle size of the nickel composite oxide. Here, the total number of moles of the metal elements is the total number of moles of nickel and cobalt when the first solution contains nickel and cobalt, and the total number of moles of nickel, cobalt and manganese when it contains nickel, cobalt and manganese. means

The first solution may further contain at least one of cobalt ions, aluminum ions and manganese ions in addition to nickel ions. In addition to these, the first solution contains magnesium, calcium, titanium, zirconium, niobium, tantalum, chromium, molybdenum, tungsten, iron, copper, silicon, tin, bismuth, gallium, yttrium, samarium, erbium, cerium, It may further contain ions of at least one second metal element selected from the group consisting of neodymium, lanthanum, cadmium and lutetium. The second metal element may be at least one selected from the group consisting of zirconium, titanium, magnesium, tantalum, niobium, molybdenum and tungsten.

The total concentration of metal ions such as nickel and cobalt in the first solution may be, for example, 1.0 mol/L or more and 2.6 mol/L or less. The concentration of metal ions may preferably be 1.5 mol/L or higher, or 1.7 mol/L or higher. Also, the metal ion concentration may preferably be 2.2 mol/L or less, or 2.0 mol/L or less. When the concentration of metal ions in the first solution is 1.0 mol/L or more, a sufficient amount of crystallized product can be obtained per reaction vessel, thereby improving productivity. On the other hand, when the metal ion concentration of the first solution is 2.6 mol/L or less, exceeding the saturation concentration of the metal salt at room temperature is suppressed, and the metal ion concentration in the solution decreases due to precipitation of metal salt crystals. is suppressed.

Second Solution Preparing Step In the second solution preparing step, a second solution containing a complex ion-forming factor is prepared. The second solution contains a complex ion-forming factor capable of forming complex ions with the metal ions contained in the first solution. For example, when the complex ion forming agent is ammonia, an aqueous ammonia solution can be used as the second solution. The content of ammonia contained in the aqueous ammonia solution may be, for example, 5% by mass or more and 25% by mass or less. The content of ammonia may preferably be 10% by mass or more, or 12% by mass or more. The content of ammonia may preferably be 20% by weight or less, or 18% by weight or less.

Liquid Medium Preparing Step In the liquid medium preparing step, a liquid medium having a pH in the range of 10 or more and 13.5 or less is prepared. The liquid medium is prepared, for example, as a solution having a pH of 10 or more and 13.5 or less by using a predetermined amount of water and a basic solution such as an aqueous sodium hydroxide solution in a reaction vessel. By adjusting the pH of the solution to 10 or more and 13.5 or less, the pH fluctuation of the reaction solution at the initial stage of the reaction can be suppressed.

Crystallization Step In the crystallization step, the first solution and the second solution are separately and simultaneously supplied to the liquid medium while maintaining the pH of the formed reaction solution within the range of 10 or more and 13.5 or less. Thereby, composite hydroxide particles containing nickel can be obtained from the reaction solution. In addition to the first solution and the second solution, the basic solution may be supplied to the liquid medium at the same time. Thereby, the pH of the reaction solution can be easily maintained in the range of 10 or more and 13.5 or less.

In the crystallization step, each solution is preferably supplied such that the pH of the reaction solution is maintained within the range of 10 or more and 13.5 or less. For example, the pH of the reaction solution can be maintained in the range of 10 or more and 13.5 or less by adjusting the supply amount of the second solution according to the supply amount of the first solution. If the pH of the reaction solution is 10 or more, the amount of impurities contained in the obtained composite hydroxide (for example, sulfuric acid and nitric acid contents other than metals contained in the reaction solution) is sufficiently reduced, and the final product is There is a tendency to suppress the decrease in the capacity of certain non-aqueous electrolyte secondary batteries. Moreover, when the pH is 13.5 or less, the production of fine secondary particles is suppressed, and the resulting composite hydroxide may be improved in handleability. The pH of the reaction solution maintained may preferably be 10.5 or higher, or 10.9 or higher, and preferably 11.7 or lower, or 11.3 or lower. In addition, the temperature of the reaction solution may be controlled within the range of, for example, 25°C to 80°C, preferably 40°C to 75°C, or 50°C to 70°C. The atmosphere in the crystallization step can be a low-oxidizing atmosphere, and for example, the oxygen concentration can be maintained at 10% by volume or less.

In the crystallization step, the concentration of nickel ions in the reaction solution may be maintained, for example, in the range of 10 ppm to 1000 ppm, preferably in the range of 10 ppm to 100 ppm. When the concentration of nickel ions is 10 ppm or more, the composite hydroxide is sufficiently precipitated. If the concentration of nickel ions is 1000 ppm or less, the amount of eluted nickel is small, so deviation from the desired composition is suppressed. For example, when an aqueous ammonia solution is used as the second solution (complex ion forming solution), the nickel ion concentration is adjusted by supplying the second solution so that the ammonium ion concentration in the reaction solution is 1000 ppm or more and 15000 ppm or less. can do.

The time for supplying the first solution may be, for example, 6 hours or more and 60 hours or less, and the time for supplying the first solution may be preferably 8 hours or more, or 10 hours or more. Also, the time for supplying the first solution may preferably be 42 hours or less, 24 hours or less, or 18 hours or less. When the time is 6 hours or longer, the precipitation rate of the composite hydroxide becomes slow, so there is a tendency to obtain a nickel composite oxide with higher smoothness. Moreover, if it is 60 hours or less, productivity can be improved more.

A value in which the total number of moles of nickel or the like in the first solution supplied throughout the crystallization process is the denominator and the total number of moles of nickel or the like in the first solution supplied per hour is the numerator is, for example, 0. It may be 0.015 or more and 0.125 or less, preferably 0.020 or more, or 0.050 or more, and preferably 0.10 or less. If it is 0.015 or more, productivity can be further improved. Moreover, if it is 0.125 or less, there is a tendency that a nickel composite oxide having a larger specific surface area is obtained.

The method for producing a nickel composite oxide may include a seed generation step prior to the crystallization step. In the seed generation step, for example, a portion of the prepared first solution is supplied to the liquid medium to generate, for example, seed crystals of a composite hydroxide containing nickel in the liquid medium. That is, the liquid medium to be subjected to the crystallization step may be a seed solution containing composite hydroxide containing nickel. The temperature in the seed generation step can be, for example, 40°C to 80°C. The atmosphere in the seed generation step can be a low-oxidizing atmosphere, and for example, the oxygen concentration can be maintained at 10% by volume or less.

If the composite hydroxide particles are generated in advance in the liquid medium prior to the crystallization step, one particle of the composite hydroxide generated in advance is equal to one particle of the composite hydroxide obtained after the crystallization step. It becomes a seed crystal that constitutes the Thereby, the total number of secondary particles of composite hydroxide obtained after the crystallization step can be controlled by the number of composite hydroxide particles generated in advance. For example, if a large amount of the first solution is supplied in advance, the number of composite hydroxide particles generated increases, so that the secondary particles of the composite hydroxide after the crystallization step tend to have a smaller average particle size.

In the crystallization step, the first solution and the second solution may be supplied to the liquid medium continuously or intermittently. The first solution may be continuously supplied throughout the supply time of the first solution in the crystallization step. Here, "continuously throughout the supply time" means that there is almost no non-supply time throughout the supply time. Moreover, the phrase "almost no non-supply time exists" means that the non-supply time is less than 1% of the entire supply time.

Composite Hydroxide Recovery Step In the composite hydroxide recovery step, a composite hydroxide containing nickel is separated and recovered from the reaction solution. The composite hydroxide can be recovered from the reaction solution, for example, by separating the resulting precipitate by a commonly used separation means such as filtration or centrifugation. The obtained precipitate may be subjected to treatments such as washing with water, filtration and drying. The composition ratio of the metal elements in the composite hydroxide may substantially match the composition ratio of the metal elements other than lithium in the lithium-transition metal composite oxide obtained using these as raw materials.

Composite Hydroxide Heat Treatment Step In the composite hydroxide heat treatment step, the resulting composite hydroxide is heat treated to obtain a nickel composite oxide. The heat treatment dehydrates the composite hydroxide to produce a nickel composite oxide. The nickel composite oxide may be a precursor of a lithium transition metal composite oxide, and may be a positive electrode active material precursor.

The heat treatment temperature may be, for example, 105° C. or higher and 900° C. or lower, preferably 300° C. or higher and 500° C. or lower. The heat treatment time may be, for example, 5 hours or more and 30 hours or less, preferably 10 hours or more and 20 hours or less. The heat treatment atmosphere may be an atmosphere containing oxygen or an air atmosphere.

In the nickel composite oxide, the ratio of the number of moles of nickel to the total number of moles of metal elements contained in the nickel composite oxide may be greater than 0 and less than 1, for example. The ratio of the number of moles of nickel to the total number of moles of metal elements may preferably be 0.33 or more. The ratio of the number of moles of nickel to the total number of moles of metal elements may be 0.4 or more, or 0.45 or more. Also, the ratio of the number of moles of nickel to the total number of moles of the metal elements may be preferably 0.95 or less, 0.8 or less, or 0.6 or less.

The nickel composite oxide may contain cobalt in its composition. When the nickel composite oxide contains cobalt in its composition, the ratio of the number of moles of cobalt to the total number of moles of metal elements contained in the nickel composite oxide may be greater than 0 and less than 1. The ratio of the number of moles of cobalt to the total number of moles of the metal elements may preferably be 0.01 or more, 0.02 or more, 0.05 or more, 0.1 or more, or 0.15 or more. Also, the ratio of the number of moles of cobalt to the total number of moles of metal elements is preferably 0.6 or less. The ratio of the number of moles of cobalt to the total number of moles of the metal elements may be 0.4 or less, 0.35 or less, 0.33 or less, 0.3 or less, or 0.25 or less.

The nickel composite oxide may contain at least one of manganese and aluminum in its composition. When the nickel composite oxide contains at least one of manganese and aluminum in its composition, the ratio of the total number of moles of manganese and aluminum to the total number of moles of metal elements contained in the nickel composite oxide is, for example, greater than 0, It may be preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.1 or more, and particularly preferably 0.15 or more. Also, the ratio of the total number of moles of manganese and aluminum to the total number of moles of metal elements is, for example, 0.6 or less, preferably 0.35 or less. The ratio of the total number of moles of manganese and aluminum to the total number of moles of metal elements may be 0.33 or less, or 0.3 or less.

The nickel composite oxide may contain at least one second metal element in its composition. When the nickel composite oxide contains at least one second metal element in its composition, the ratio of the total number of moles of the second metal element to the total number of moles of the metal elements contained in the nickel composite oxide is, for example, 0. It may be greater, 0.001 or more, or 0.003 or more. Also, the ratio of the total number of moles of the second metal element to the total number of moles of the metal elements may be, for example, 0.05 or less, 0.02 or less, 0.015 or less, or 0.01 or less.

The nickel composite oxide may have, for example, a composition represented by the following formula (2).
_{NiqCorM1sM2tO2} ⁺ _{β (} ² _{) _}

In formula (2), M1 represents at least ^one of Mn and Al. ^M2 is from Mg, Ca, Ti, Zr, Nb, Ta, Cr, Mo, W, Fe, Cu, Si, Sn, Bi, Ga, Y, Sm, Er, Ce, Nd, La, Cd and Lu At least one selected from the group consisting of q, r, s, t and β are 0<q<1, 0≤r≤0.6, 0≤s≤0.6, 0≤t≤0.02, -0.1≤β≤1. 1, satisfies q+r+s+t=1. Preferably, 0.33≤q≤0.95, 0.02≤r≤0.35, 0.01≤s≤0.35, 0≤t≤0.015. Also preferably, ^M2 is at least one selected from the group consisting of Zr, Ti, Mg, Ta, Nb, Mo and W.

The nickel composite oxide may have a tap density of 1.3 g/cm ³ or less, preferably 1.15 g/cm ³ or less, more preferably 1 g/cm ³ or less, and even more preferably 0.96 g/cm ³ or less. can be Also, the tap density of the nickel composite oxide may be greater than 0 g/cm ³ , preferably 0.2 g/cm ³ or more, or 0.4 g/cm ³ or more. When the nickel composite oxide has a tap density of 1.3 g/cm ³ or less, the obtained lithium-transition metal composite oxide tends to be particles having a larger specific surface area. When the ratio of the number of moles of nickel to the total number of moles of metal elements contained in the nickel composite oxide is 0.5 or more, it is obtained by mixing and reacting the nickel composite oxide, the lithium compound, and the tungsten compound. The resulting lithium-transition metal composite oxide tends to be obtained as particles with a higher porosity, and the output characteristics tend to be further improved.

The particle size of the nickel composite oxide may be 1 μm or more and 8 μm or less, preferably 2 μm or more, 2.5 μm or more, or 3 μm or more. Also, the particle size of the nickel composite oxide may preferably be 6 μm or less, 5 μm or less, or 4 μm or less. When the particle size of the nickel composite oxide is 1 μm or more and 8 μm or less, the resulting lithium-transition metal composite oxide tends to have a larger specific surface area when the above range of tap density is satisfied.

Electrode for Nonaqueous Electrolyte Secondary Battery A nonaqueous electrolyte secondary battery electrode includes a current collector and a positive electrode active material layer disposed on the current collector and containing the above-described positive electrode active material. A non-aqueous electrolyte secondary battery having such an electrode can achieve excellent output characteristics.

The density of the positive electrode active material layer may be, for example, 2.6 g/cm ³ or more and 3.9 g/cm ³ or less, preferably 2.8 g/cm ³ or more and 3.8 g/cm ³ or less, and 3.1 g/cm 3 or less. ³ or more and 3.7 g/cm ³ or less, or 3.2 g/cm ³ or more and 3.6 g/cm ³ or less. The density of the positive electrode active material layer is calculated by dividing the mass of the positive electrode active material layer by the volume of the positive electrode active material layer. Here, the density of the positive electrode active material layer can be adjusted by applying an electrode composition, which will be described later, onto a current collector and then applying pressure.

Examples of the material of the current collector include aluminum, nickel, and stainless steel. The positive electrode active material layer is formed by applying an electrode composition obtained by mixing the above positive electrode active material, conductive aid, binder, etc. with a solvent onto a current collector, followed by drying treatment, pressure treatment, etc. can be formed with Examples of conductive aids include natural graphite, artificial graphite, acetylene black, and the like. Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, polyamide acrylic resins, and the like. Solvents include N-methyl-2-pyrrolidone (NMP) and the like.

Nonaqueous Electrolyte Secondary Battery A nonaqueous electrolyte secondary battery includes the electrode for a nonaqueous electrolyte secondary battery. A non-aqueous electrolyte secondary battery includes a non-aqueous electrolyte secondary battery electrode, a non-aqueous electrolyte secondary battery negative electrode, a non-aqueous electrolyte, a separator, and the like. Regarding the negative electrode, non-aqueous electrolyte, separator, etc. in the non-aqueous electrolyte secondary battery, for example, JP-A-2002-075367, JP-A-2011-146390, JP-A-2006-12433 (these are the disclosure contents The entirety of which is incorporated herein by reference), etc., for non-aqueous electrolyte secondary batteries can be used as appropriate.

Note that the present disclosure is not limited to the above embodiments. The above embodiment is an example, and any device that has substantially the same configuration as the technical idea described in the claims of the present disclosure and achieves the same effect is the present invention. Needless to say, it is included in the technical scope of the disclosure.

EXAMPLES The present invention will be specifically described below by way of examples, but the present invention is not limited to these examples. In the following, the volume average particle diameter was evaluated using a laser diffraction particle size distribution analyzer (SALD-3100 manufactured by Shimadzu Corporation). Further, the specific surface area was evaluated by the nitrogen gas adsorption method (one-point method) using a BET specific surface area measuring device (manufactured by Mountech; Macsorb). The porosity was evaluated by a method using the above-described scanning electron microscope (SEM) and image analysis software (for example, HALCON; manufactured by MVTec).

Example 1
Preparation of each solution A first solution (nickel ions, nickel ions, nickel ions, 1.7 mol/L) was prepared with a combined concentration of cobalt ions and manganese ions. The total number of moles of metal elements in the first solution was 350 moles. A 25% by weight sodium hydroxide aqueous solution was prepared as a basic solution. A 12.5% by weight ammonia aqueous solution was prepared as a second solution (complex ion forming solution).

Preparation of liquid medium 30 liters of water was prepared in a reaction vessel, and an aqueous sodium hydroxide solution was added to adjust the pH to 12.5. Nitrogen gas was introduced to replace the inside of the reaction vessel with nitrogen to prepare a liquid medium as a pre-reaction solution.

Seed Generation Step While stirring the liquid medium, the first solution was added to the liquid medium in an amount of 10 moles as the total number of moles of nickel and the like to precipitate a composite hydroxide containing nickel, cobalt and manganese.

Crystallization step The remaining 340 moles of the first solution, the sodium hydroxide aqueous solution, and the second solution are added to the reaction solution while the pH is maintained at about 10.9 to 11.3, and the ammonium ion concentration is about A mixed hydroxide containing nickel, cobalt and manganese was precipitated by supplying the reaction solution over 12 hours while stirring so that the concentration became 4000 ppm. The temperature of the reaction solution was controlled to be about 60°C. The precipitate was washed with water, filtered, separated and then dried to obtain a composite hydroxide containing nickel, cobalt and manganese (hereinafter also referred to as nickel-cobalt composite hydroxide). The nickel-cobalt composite hydroxide was heat-treated at 320° C. for 16 hours in an air atmosphere to recover a transition metal composite oxide containing nickel, cobalt, and manganese (hereinafter also referred to as composite oxide). A composite oxide having a volume average particle size of 4.7 μm and a tap density of 0.86 g/cm ³ was obtained.

Synthesis step Lithium carbonate, zirconium (IV) oxide, and tungsten (VI) oxide were added to the obtained composite oxide, Li: (Ni + Co + Mn): Zr: W = 1.19: 1: 0.005: 0.003 ( molar ratio) to obtain a lithium mixture. The resulting lithium mixture was heat-treated in an air atmosphere. The heat treatment was carried out at a first temperature of 780° C. for 2 hours and a second temperature of 910° C. for 4 hours to obtain a heat treated product. The obtained heat-treated product was pulverized and dry-sieved to obtain a lithium transition metal composite oxide represented by the composition formula Li _1.19 Ni _0.35 Co _0.35 Mn _0.30 Zr _0.005 W _0.003 O ₂ got stuff

The obtained lithium-transition metal composite oxide serving as the base material had a volume average particle size of 4.4 μm, a specific surface area of 2.06 m ² /g, and a porosity of 30%.

Mixing step To the lithium transition metal composite oxide obtained above, aluminum oxide (Al ₂ O ₃ : manufactured by CABOT; average particle size 20 to 30 nm) as an aluminum compound is added to the lithium transition metal composite oxide ( Ni+Co+Mn):Al=1:0.005 (molar ratio), and mixed with a high-speed shear mixer. After that, the positive electrode active material of Example 1 was obtained by dry sieving.

The positive electrode active material obtained in Example 1 had a volume average particle size of 4.4 μm, a specific surface area of 2.26 m ² /g, and a porosity of 30%.

The positive electrode active material obtained in Example 1 was observed using a scanning electron microscope (Hitachi High-Technologies SU8230) at an accelerating voltage of 1.5 kV to obtain scanning electron microscope (SEM) images. The results are shown in FIG.

Comparative example 1
In the crystallization step, the pH of the reaction solution was maintained at about 11.3 to 11.7, the ammonium ion concentration was adjusted to about 6000 ppm, the temperature of the reaction solution was controlled at about 45°C, A composite containing nickel, cobalt and manganese with a volume average particle diameter of 3.4 μm and a tap density of 1.46 g/cm ³ was repeated in the same manner as in Example 1 except that the supply time of the first solution in the precipitation step was 18 hours. An oxide was obtained. A lithium-transition metal composite oxide of Comparative Example 1 was obtained in the same manner as in the synthesis process of Example 1, except that the obtained composite oxide was used.

The obtained lithium-transition metal composite oxide was used as the positive electrode active material of Comparative Example 1. The positive electrode active material of Comparative Example 1 had a volume average particle size of 3.1 μm, a specific surface area of 1.09 m ² /g, and a porosity of 5%.

Example 2
In the mixing step, in addition to the aluminum compound, tungsten oxide (WO ₃ : manufactured by Nippon New Metal Co., Ltd.; average particle diameter 1000 nm) is further added as a tungsten compound, and (Ni + Co + Mn):Al:W is added to the lithium transition metal composite oxide. = 1:0.005:0.005 (molar ratio), the positive electrode active material of Example 2 was obtained in the same manner as in Example 1.

The positive electrode active material obtained in Example 2 had a volume average particle size of 4.4 μm, a specific surface area of 2.29 m ² /g, and a porosity of 30%.

Example 3
A lithium-transition metal composite oxide of Example 3 was obtained in the same manner as in Example 2, except that the second temperature of the heat treatment was changed from 910°C to 950°C in the synthesis step.

The positive electrode active material obtained in Example 3 had a volume average particle diameter of 4.3 μm, a specific surface area of 1.43 m ² /g, and a porosity of 17%.

Example 4
A lithium-transition metal composite oxide of Example 4 was obtained in the same manner as in Example 2, except that the second temperature of the heat treatment was changed from 910°C to 880°C in the synthesis step.

The positive electrode active material obtained in Example 4 had a volume average particle size of 3.9 μm, a specific surface area of 2.90 m ² /g, and a porosity of 31%.

Example 5
A lithium-transition metal composite oxide of Example 5 was obtained in the same manner as in Example 2, except that the second temperature of the heat treatment was changed from 910°C to 860°C in the synthesis step.

The positive electrode active material obtained in Example 5 had a volume average particle size of 3.9 μm, a specific surface area of 3.33 m ² /g, and a porosity of 31%.

Example 6
A lithium-transition metal composite oxide of Example 5 was obtained in the same manner as in Example 2, except that the second temperature of the heat treatment was changed from 910°C to 840°C in the synthesis step.

The positive electrode active material obtained in Example 6 had a volume average particle size of 3.9 μm, a specific surface area of 3.84 m ² /g, and a porosity of 32%.

Reference example 1
The lithium-transition metal composite oxide as the base material obtained in Example 1 was used as the positive electrode active material of Reference Example 1 in the same manner as in Example 1, except that the mixing step was not performed. Further, in the same manner as in Example 1, SEM images were acquired. The results are shown in FIG.

Reference example 2
In the mixing step, instead of the aluminum compound, tungsten oxide (WO ₃ : manufactured by Nippon New Metal Co., Ltd.; average particle diameter 1000 nm) as a tungsten compound is added to the lithium transition metal composite oxide (Ni + Co + Mn): W = 1: A positive electrode active material of Reference Example 2 was obtained in the same manner as in Example 1, except that the materials were blended so as to have a molar ratio of 0.005.

The obtained positive electrode active material of Reference Example 2 had a volume average particle size of 4.4 μm, a specific surface area of 2.07 m ² /g, and a porosity of 30%.

Reference example 3
In the mixing step, instead of the aluminum compound, titanium oxide (TiO ₂ : manufactured by Nippon Aerosil Co., Ltd.; average particle size of 20 to 40 nm) is used as a titanium compound with respect to the lithium transition metal composite oxide (Ni + Co + Mn): Ti = 1. A positive electrode active material of Reference Example 3 was obtained in the same manner as in Example 1, except that the ratio was 0.003 (molar ratio).

The obtained positive electrode active material of Reference Example 3 had a volume average particle size of 4.4 μm, a specific surface area of 2.13 m ² /g, and a porosity of 30%.

Reference example 4
In the mixing step, instead of the aluminum compound, zirconium oxide (ZrO ₂ : manufactured by TECNAN; average particle size of 20 to 30 nm) is used as a zirconium compound with respect to the lithium transition metal composite oxide (Ni + Co + Mn): Zr = 1: A positive electrode active material of Reference Example 4 was obtained in the same manner as in Example 1, except that the materials were blended so as to be 0.002 (molar ratio).

The obtained positive electrode active material of Reference Example 4 had a volume average particle diameter of 4.4 μm, a specific surface area of 2.21 m ² /g, and a porosity of 30%.

Reference example 5
In the mixing step, instead of the aluminum compound, silicon dioxide (SiO ₂ : manufactured by Nippon Aerosil Co., Ltd.; average particle size 40 to 50 nm) is used as a silicon compound with respect to the lithium transition metal composite oxide (Ni + Co + Mn): Si = 1. : A positive electrode active material of Reference Example 5 was obtained in the same manner as in Example 1, except that the ratio was 0.005 (molar ratio).

The obtained positive electrode active material of Reference Example 5 had a volume average particle size of 4.4 μm, a specific surface area of 2.16 m ² /g, and a porosity of 30%.

Example 7
In the mixing step, instead of aluminum oxide (Al ₂ O ₃ : manufactured by CABOT; average particle size 20 to 30 nm), aluminum oxide (Al ₂ O ₃ : manufactured by Aldrich; average particle size 200 to 300 nm) is used as an aluminum compound. , In the same manner as in Example 1, except that (Ni + Co + Mn): Al = 1: 0.005 (molar ratio) with respect to the lithium transition metal composite oxide, the positive electrode active material of Example 7 got

The positive electrode active material obtained in Example 7 had a volume average particle size of 4.4 μm, a specific surface area of 2.33 m ² /g, and a porosity of 30%.

Example 8
In the mixing step, instead of aluminum oxide (Al ₂ O ₃ : manufactured by CABOT; average particle size 20 to 30 nm), aluminum oxide (Al ₂ O ₃ : manufactured by Sumitomo Chemical Co., Ltd.; average particle size 500 nm) is used as an aluminum compound. The positive electrode active material of Example 8 was prepared in the same manner as in Example 1, except that (Ni + Co + Mn):Al = 1:0.005 (molar ratio) was added to the lithium transition metal composite oxide. Obtained.

The positive electrode active material obtained in Example 8 had a volume average particle size of 4.4 μm, a specific surface area of 2.07 m ² /g, and a porosity of 30%.

Reference example 6
A first solution (nickel ions, cobalt ions and manganese A composite oxide with a volume average particle size of 4.2 μm and a tap density of 1.05 g/cm ³ was obtained in the same manner as in Example 1, except that the combined concentration of ions was 1.7 mol / L). rice field. In addition, in the synthesis step, Li: (Ni + Co + Mn): Zr: W = 1.14: 1: 0.005: 0.003 (molar ratio) was mixed, and heat treatment was performed at 840 ° C. for 8 hours. In the same manner as in Example 1, as Reference Example 6, a lithium transition metal composite oxide represented by the composition formula Li _1.14 Ni _0.5 Co _0.2 Mn _0.3 Zr _0.005 W _0.003 O ₂ got The obtained lithium-transition metal composite oxide as the base material had a volume average particle diameter of 3.9 μm, a specific surface area of 2.09 m ² /g, and a porosity of 31%.

Example 9
In the lithium transition metal composite oxide obtained as Reference Example 6, aluminum oxide (Al ₂ O ₃ : manufactured by CABOT; average particle size 20 to 30 nm) as an aluminum compound, and tungsten oxide (WO ₃ : Nippon New Metals Co., Ltd.) as a tungsten compound Co., Ltd.; average particle size 1000 nm) was mixed with the lithium transition metal composite oxide so that (Ni + Co + Mn): Al: W = 1: 0.005: 0.005 (molar ratio). Mixed with a shear type mixer. After that, the positive electrode active material of Example 9 was obtained by dry sieving.

The positive electrode active material obtained in Example 9 had a volume average particle size of 4.1 μm, a specific surface area of 2.35 m ² /g, and a porosity of 31%.

Comparative example 2
A first solution (nickel ions, cobalt ions and manganese A composite oxide with a volume average particle diameter of 3.1 μm and a tap density of 1.33 g/cm ³ was obtained in the same manner as in Comparative Example 1, except that the combined concentration of ions was 1.7 mol / L). rice field. A positive electrode active material of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the obtained composite oxide was heat-treated at 860° C. for 8 hours in the synthesis step.

The positive electrode active material obtained in Comparative Example 2 had a volume average particle size of 3.0 μm, a specific surface area of 1.27 m ² /g, and a porosity of 5%.

Comparative example 3
Using the composite oxide obtained in Comparative Example 2, Li: (Ni + Co + Mn): Zr: W = 1.12: 1: Li: (Ni + Co + Mn): Zr: W = 1.12: 1: They were mixed at a molar ratio of _0.005 : _0.01 and heat-treated at ₉₂₀ ° C. for 8 hours in an air atmosphere. _{A lithium} transition metal composite _oxide represented by _{0.3Zr0.005W0.01O2} was obtained.

The obtained lithium-transition metal composite oxide of Comparative Example 3 had a volume average particle size of 3.3 μm, a specific surface area of 1.12 m ² /g, and a porosity of 5%.

Example 10
In Example 9, Li: (Ni + Co + Mn): Zr: W = 1.16: 1: 0.005: 0.01 (molar ratio) in the synthesis process, and heat treated at 860 ° C. for 8 hours. Except for this, the positive electrode active material of Example 10 was obtained in the same manner as in Example 9.

The obtained positive electrode active material of Example 10 had a volume average particle size of 3.7 μm, a specific surface area of 2.79 m ² /g, and a porosity of 36%.

Evaluation of Process Fluidity About 50 g of each of the positive electrode active materials obtained above was weighed and put into a powder property measuring device (Powder Tester (registered trademark); manufactured by Hosokawa Micron Corporation). After that, the repose angle and collapse angle were automatically measured, and the difference angle was calculated. Table 2 shows the results.

Evaluation of Positive Electrode Mixture Slurry Viscosity Using each of the positive electrode active materials obtained above, positive electrode mixture slurries were prepared as follows, and the viscosities of the positive electrode mixture slurries were evaluated.

Preparation of positive electrode mixture slurry 89.5 parts by mass of positive electrode active material, 5 parts by mass of acetylene black as a conductive agent, 5 parts by mass of polyvinylidene fluoride (PVDF) as a binder, and 0.5 parts by mass of polyvinylpyrrolidone (PVP) as a dispersant. A positive electrode mixture slurry was prepared by dispersing 5 parts by mass in N-methyl-2-pyrrolidone (NMP).

Evaluation of Relative Thickening Rate The viscosity of the positive electrode material mixture slurry prepared above was measured using an E-type viscometer (HAAKE Viscotester 550 manufactured by Thermo Scientific) immediately after slurry preparation and 6 hours after preparation. As shown in the following formula, the value obtained by dividing the viscosity of the positive electrode mixture slurry 6 hours after preparation by the viscosity immediately after preparation was taken as the viscosity increase rate.
(Slurry viscosity after 6 hours)/(Slurry viscosity immediately after preparation)

Regarding the obtained thickening ratios, Examples 1 to 8 and Reference Examples 1 to 5 were evaluated as relative thickening ratios when the thickening ratio of Comparative Example 1 was set to 1. Reference Example 6, Examples 9 and 10, and Comparative Example 3 were evaluated as a relative viscosity increase rate when the viscosity increase rate of Comparative Example 2 was set to 1. The results are shown in Tables 2 and 3.

Preparation of Battery for Evaluation Using the positive electrode active material obtained above, a battery for evaluation was prepared in the following procedure.

Preparation of Positive Electrode A positive electrode mixture slurry was prepared by dispersing 92 parts by mass of a positive electrode active material, 3 parts by mass of acetylene black, and 5 parts by mass of polyvinylidene fluoride (PVDF) in N-methyl-2-pyrrolidone (NMP). The obtained positive electrode mixture slurry was applied to an aluminum foil as a current collector, dried, compression-molded with a roll press, and cut into a predetermined size to prepare a positive electrode.

Preparation of Negative Electrode 97.5 parts by weight of artificial graphite, 1.5 parts by weight of carboxymethyl cellulose (CMC), and 1.0 parts by weight of SBR (styrene-butadiene rubber) were dispersed and dissolved in pure water to prepare a negative electrode slurry. The resulting negative electrode slurry was applied to a current collector made of copper foil, dried, compression molded with a roll press, and cut into a predetermined size to prepare a negative electrode.

After attaching lead electrodes to the current collectors of the positive electrode and the negative electrode, respectively, a separator was arranged between the positive electrode and the negative electrode, and they were housed in a bag-shaped laminate pack. Then, this was vacuum-dried at 65° C. to remove moisture adsorbed on each member. After that, an electrolytic solution was injected into the laminate pack under an argon atmosphere, and the laminate pack was sealed to prepare a battery for evaluation. As the electrolytic solution, ethylene carbonate (EC) and methyl ethyl carbonate (MEC) were mixed at a volume ratio of 3:7, and lithium hexafluorophosphate (LiPF ₆ ) was dissolved to a concentration of 1 mol/L. I used what I made. The battery for evaluation thus obtained was placed in a constant temperature bath at 25° C., aged with a weak electric current, and then evaluated as follows.

Evaluation of output characteristics (DC internal resistance measurement)
DC internal resistance was measured for the evaluation battery after aging. After performing constant current charging to a charge depth of 50% at a full charge voltage of 4.2 V, place the evaluation battery in an environment of -25 ° C., perform pulse discharge with a specific current i for 10 seconds, and the voltage at 10 seconds V was measured. The horizontal axis represents the current i and the vertical axis represents the voltage V. The points of intersection were plotted, and the slope of the straight line connecting the points of intersection was taken as the DC internal resistance (DC-IR). The current i was set to 0.02A, 0.04A, 0.06A, 0.08A and 0.10A. Low DC-IR means good output characteristics.

The obtained DC internal resistance was evaluated as a relative DC internal resistance when the DC internal resistance of Reference Example 1 was set to 1 for Examples 1 to 8, Comparative Example 1, and Reference Examples 2 to 5. Examples 9 and 10 and Comparative Examples 2 and 3 were evaluated as relative DC internal resistance when the DC internal resistance of Reference Example 6 was set to 1. The results are shown in Tables 2 and 3.

From Tables 1 to 3, it was confirmed that by increasing the specific surface area of particles having a volume average particle diameter of 4.4 μm or less, the output characteristics were improved. In addition, by mixing these particles with a metal compound, the process fluidity tends to be improved. It was confirmed that the handling performance was efficiently improved.

Claims (17)

Containing particles containing a lithium transition metal composite oxide and an aluminum compound having an average particle size of 1 nm or more and less than 500 nm,
A positive electrode active material for a non-aqueous electrolyte secondary battery having a volume average particle size of 1 μm or more and 8 μm or less and a specific surface area of 1.4 m ² /g or more. The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, further comprising a tungsten compound. 3. The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 2, wherein the content of said tungsten compound is 0.1 mol % or more and 2 mol % or less with respect to said lithium transition metal composite oxide. The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein the lithium-transition metal composite oxide contains lithium and nickel in its composition and has a layered structure. The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein the particles containing the lithium-transition metal composite oxide have internal voids. The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 5, wherein the specific surface area is 1.7 ^m2 /g or more and 3.3 ^m2 /g or less. The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 6, wherein the content of said aluminum compound is 2 mol% or less with respect to said lithium transition metal composite oxide. The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 7, wherein the content of said aluminum compound is 0.01 mol% or more relative to said lithium transition metal composite oxide. The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 8, wherein the volume average particle diameter is 2 µm or more and 6 µm or less. preparing particles comprising a lithium transition metal composite oxide;
obtaining a mixture by mixing particles containing the lithium-transition metal composite oxide and an aluminum compound having an average particle size of 1 nm or more and less than 500 nm;
The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, wherein the particles containing the lithium-transition metal composite oxide have a volume average particle size of 1 μm or more and 8 μm or less and a specific surface area of 1.3 m ² /g or more. 11. The manufacturing method according to claim 10, further comprising mixing the lithium transition metal composite oxide and the tungsten compound. The manufacturing method according to claim 11, wherein the tungsten compound has an average particle size of 0.05 µm or more and 2 µm or less. 13. The manufacturing method according to claim 11, wherein the mixed amount of the tungsten compound is 0.1 mol % or more and 2 mol % or less with respect to the lithium-transition metal composite oxide. 14. The production method according to any one of claims 10 to 13, wherein the lithium-transition metal composite oxide contains lithium and nickel in its composition and has a layered structure. 15. The production method according to any one of claims 10 to 14, wherein the amount of the aluminum compound mixed is 2 mol% or less with respect to the lithium-transition metal composite oxide. 16. The production method according to any one of claims 10 to 15, wherein the amount of the aluminum compound mixed is 0.01 mol% or more with respect to the lithium-transition metal composite oxide. 17. The production method according to any one of claims 10 to 16, wherein the particles containing the lithium-transition metal composite oxide have a volume average particle size of 2 µm or more and 6 µm or less.

Images