Positive electrode active material for nonaqueous electrolyte secondary battery and method for producing same

Abstract

The present application provides a positive electrode active material for a nonaqueous electrolyte secondary battery, which is excellent in output characteristics. The positive electrode active material for a nonaqueous electrolyte secondary battery contains particles containing a lithium transition metal complex oxide, and an aluminum compound having an average particle diameter of 1 nm or more and less than 500 nm. The positive electrode active material for a nonaqueous electrolyte secondary battery 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.

Description

Technical Field

[0001] This invention relates to the positive electrode active material for non-aqueous electrolyte secondary batteries and its manufacturing method. Background Technology

[0002] High output characteristics are required for positive electrode active materials used in non-aqueous electrolyte secondary batteries for high-power devices such as electric vehicles. To achieve high output characteristics, positive electrode active materials with a structure consisting of numerous primary particles aggregated into secondary particles are effective. In this regard, lithium-containing transition metal composite oxides with different lithium-to-oxygen ratios on the surface and inside the secondary particles have been proposed (see, for example, Japanese Patent Application Publication No. 2019-99410). Furthermore, lithium transition metal oxides with an alumina coating on the surface have been proposed (see, for example, Japanese Patent Application Publication No. 2016-538694). Summary of the Invention

[0003] The problem that the invention aims to solve

[0004] One objective of this invention is to provide a positive electrode active material for a non-aqueous electrolyte secondary battery with excellent output characteristics and a method for manufacturing the same.

[0005] Methods for solving problems

[0006] The first method is a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising: particles containing lithium transition metal composite oxides, and an aluminum compound with an average particle size of 1 nm or more and less than 500 nm. The volume average particle size of the positive electrode active material for the non-aqueous electrolyte secondary battery is 1 μm or more and less than 8 μm, and its specific surface area is 1.4 m². 2 / g or more.

[0007] The second method is a method for manufacturing a positive electrode active material for a non-aqueous electrolyte secondary battery. This method includes: preparing particles containing a lithium transition metal composite oxide; and mixing the particles containing the lithium transition metal composite oxide with an aluminum compound having an average particle size of 1 nm or more and less than 500 nm to obtain a mixture. 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 m². 2 / g or more.

[0008] The effects of the invention

[0009] According to one aspect of the present invention, a positive electrode active material for a non-aqueous electrolyte secondary battery with excellent output characteristics and a method thereof can be provided. Attached Figure Description

[0010] Figure 1This is an example of a scanning electron microscope (SEM) image of the positive electrode active material of Example 1.

[0011] Figure 2 This is an example of a SEM image of the positive electrode active material in Reference Example 1. Detailed Implementation

[0012] In this specification, the term "process" is not limited to an independent process. Where it cannot be clearly distinguished from other processes, any process that achieves its intended purpose is included in this terminology. Furthermore, when multiple substances equivalent to each component are present in the composition, unless otherwise specified, the content of each component in the composition refers to the total amount of those multiple substances present in the composition. Additionally, the upper and lower limits of the numerical ranges described in this specification can be arbitrarily selected and combined from the numerical range examples. In this specification, embodiments of the present invention will be described in detail below. However, the embodiments shown below are merely examples illustrating the technical concept of the present invention by demonstrating the positive electrode active material for non-aqueous electrolyte secondary batteries and its manufacturing method. The present invention is not limited to the positive electrode active material for non-aqueous electrolyte secondary batteries and its manufacturing method shown below.

[0013] Positive electrode active material for non-aqueous electrolyte secondary batteries

[0014] The positive electrode active material for non-aqueous electrolyte secondary batteries comprises particles containing lithium transition metal composite oxides and aluminum compounds with an average particle size of 1 nm or more and less than 500 nm. The volume average particle size of the positive electrode active material for non-aqueous electrolyte secondary batteries is 1 μm or more and less than 8 μm, and its specific surface area is 1.4 m². 2 / g or more. Positive electrode active materials for non-aqueous electrolyte secondary batteries can be efficiently manufactured, for example, by the manufacturing method of positive electrode active materials for non-aqueous electrolyte secondary batteries described later.

[0015] The positive electrode active material (hereinafter referred to as "positive electrode active material") used in non-aqueous electrolyte secondary batteries has a small particle size and a large specific surface area. When used in non-aqueous electrolyte secondary batteries, it can achieve excellent output characteristics, such as reduced DC resistance at low temperatures. Furthermore, by incorporating aluminum compounds, despite the large specific surface area, it exhibits excellent flowability as a powder, resulting in good flowability and excellent productivity in the manufacturing process. This can be attributed to, for example, the increased steric hindrance between particles due to the inclusion of aluminum compounds, which suppresses agglomeration.

[0016] From the viewpoint of output characteristics in non-aqueous electrolyte secondary batteries, the volume average particle size of the positive electrode active material can be 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 embodiment, the volume average particle size can be 2 μm or more and 6 μm or less. The volume average particle size of the positive electrode active material is obtained in the form of the particle size corresponding to 50% of the cumulative volume from the smallest particle size side in the volume-based cumulative particle size distribution. The volume-based cumulative particle size distribution can be measured by, for example, a laser diffraction particle size distribution measuring device.

[0017] From the perspective of the output characteristics of non-aqueous electrolyte secondary batteries, the specific surface area of ​​the positive electrode active material, as measured by the BET method, can be 1.4 m². 2 / g or higher, preferably 1.7m 2 / g or more, 1.9m 2 / g or more, 2.0m 2 / g or more, or 2.5m 2 / g or higher. Additionally, the specific surface area can be, for example, 4.0 m². 2 / g or less, preferably 3.8m 2 / g or less, 3.3m 2 / g or less, or 3.0m 2 / g or less. In one embodiment, the specific surface area of ​​the positive electrode active material can be, for example, 1.7m². 2 / g or more and 3.8m 2 / g or less, preferably 1.7m 2 / g or more and 3.3m 2 / g or less, or 1.9m 2 / g or more and 3.0m 2 / g or less. It should be noted that the specific surface area determined by the BET method is based on the BET (Brunauer Emmett Teller) theory and is determined using a one-point method with nitrogen gas.

[0018] From a flowability perspective, the angle of repose of the positive electrode active material as a powder can be less than 70°, preferably 68° or less, or 67° or less. The lower limit of the angle of repose can be 50° or more, or 60° or more. Furthermore, from a flowability perspective, the angle of collapse of the positive electrode active material as a powder can be less than 68°, preferably 66° or less, or 61° or less. The lower limit of the angle of collapse can be 40° or more, or 45° or more. Additionally, from a flowability perspective, the difference angle obtained by subtracting the angle of collapse from the angle of repose of the positive electrode active material can be 3° or more, preferably 6° or more, or 8° or more. The upper limit of the difference angle can be 25° or less, or 20° or less.

[0019] Here, "angle of repose (θ1)" refers to the tilt angle when the powder of the positive electrode active material is deposited on the measuring stage. A common method for depositing the powder of the positive electrode active material is the injection method. "Angle of collapse (θ2)" refers to the tilt angle measured after applying a given impact force to the measuring stage following the measurement of the angle of repose (θ1). The angle of repose (θ1) and the angle of collapse (θ2) can be measured using, for example, a powder property measuring instrument (e.g., Powder Tester (registered trademark); manufactured by Hosokawa Micron).

[0020] The specific methods for measuring the angle of repose (θ1) and the angle of collapse (θ2) are as follows.

[0021] [Methods for determining the angle of repose]

[0022] The powder to be measured is dropped from a funnel at a given height onto a horizontal substrate (measuring stage). The base angle is calculated based on the diameter and height of the resulting conical accumulation, and this base angle is used as the angle of repose. Generally, the measurement can be performed based on JIS-R9301-2-2.

[0023] [Method for measuring the angle of collapse]

[0024] After the conical deposit, whose angle of repose has been measured, collapses by applying three given impacts to the measuring platform, the base angle is calculated based on the diameter and height of the conical deposit, and this base angle is taken as the collapse angle. Here, the given impact refers to the impact used in the measuring device, which is an inherent and constant impact of the device.

[0025] [Methods for determining the difference angle]

[0026] The difference angle is calculated using the following formula.

[0027] Angle of repose (°) - Angle of collapse (°) = Difference angle (°)

[0028] Lithium transition metal composite oxide

[0029] The particles comprising lithium transition metal complex oxides (hereinafter also referred to as "lithium transition metal complex oxide particles") constituting the positive electrode active material can, for example, be secondary particles formed by the aggregation of multiple primary particles comprising lithium transition metal complex oxides. By giving the lithium transition metal complex oxide particles a given volume average particle size and specific surface area, the output characteristics are improved in a non-aqueous electrolyte secondary battery constructed using a positive electrode active material containing it. Therefore, in one embodiment, the positive electrode active material may comprise lithium transition metal complex oxide particles having a given volume average particle size and specific surface area.

[0030] The volume average particle size (D50) of the lithium transition metal composite oxide particles can 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 embodiment, the volume average particle size can be 2 μm or more and 6 μm or less. When the volume average particle size of the lithium transition metal composite oxide particles is within the above range, the flowability as a positive electrode active material is good, and the output characteristics are sometimes further improved when constructing a non-aqueous electrolyte secondary battery. Here, the volume average particle size of the lithium transition metal composite oxide particles is obtained, similar to that of the positive electrode active material, in the form of the particle size corresponding to 50% of the cumulative volume from the smallest particle size side in the cumulative particle size distribution based on volume.

[0031] The positive electrode active material is composed of lithium transition metal composite oxide particles and aluminum compound nanoparticles. Therefore, the volume average particle size of the lithium transition metal composite oxide particles can be substantially the same as the volume average particle size of the positive electrode active material.

[0032] Lithium transition metal composite oxide particles are formed by the aggregation of multiple primary particles. The average particle size of the primary particles, as observed by electron microscopy (DSEM), can be, for example, 0.1 μm or more and 1.5 μm or less, preferably 0.12 μm or more, and more preferably 0.15 μm or more. Furthermore, the average particle size D of the primary particles as observed by electron microscopy... SEM Preferably, the particle size is 1.2 μm or less, more preferably 1.0 μm or less. When the average particle size of the primary particles, as observed by electron microscopy, is within the above range, the output is sometimes improved when constructing a non-aqueous electrolyte secondary battery.

[0033] From the perspective of the output characteristics of non-aqueous electrolyte secondary batteries, the specific surface area of ​​lithium transition metal composite oxide particles, as measured by the BET method, can be 1.3 m². 2 / g or more, preferably 1.5m 2 / g or more, 1.7m 2 / g or more, or 1.9m 2 / g or higher. Additionally, the specific surface area can be, for example, 3.9m². 2 / g or less, preferably 3.5m 2 / g or less, 3.3m 2 / g or less, or 2.8m 2 / g or less. When the specific surface area of ​​lithium transition metal composite oxide particles is within the above range, the output characteristics are further improved, and the improvement in flowability is sometimes greater when aluminum compounds are added.

[0034] The positive electrode active material is composed of secondary particles, which are particles containing lithium transition metal composite oxides, and nanoparticles of aluminum compounds. Therefore, the specific surface area of ​​the lithium transition metal composite oxide particles can be a value that is substantially the same as the specific surface area of ​​the positive electrode active material, or it can be a value that is more than 80% and less than 110% of the specific surface area of ​​the positive electrode active material.

[0035] Lithium transition metal composite oxide particles are secondary particles composed of aggregates of multiple primary particles, and can contain voids within them. This allows for the easy achievement of a given specific surface area, and sometimes further improves the output characteristics of non-aqueous electrolyte secondary batteries. The voids within lithium transition metal composite oxide particles can be evaluated, for example, by examining their cross-sectional images. These cross-sectional images can be obtained, for example, using scanning electron microscopy (SEM).

[0036] When lithium transition metal composite oxide particles have internal voids, the degree of voids can be evaluated, for example, by porosity. Porosity is an indicator of the proportion of space formed inside the secondary particles composed of lithium transition metal composite oxides, and can be measured by observing the cross-section of the secondary particles. The porosity of lithium transition metal composite oxide particles can 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 further increased, resulting in a positive electrode active material with superior output characteristics. This leads to a secondary battery with further improved output density per unit volume. Preferably, the porosity of lithium transition metal composite oxide particles can be 25% or more and 45% or less, 27% or more, 29% or more, or 30% or more, and 40% or less or 38% or less.

[0037] The porosity of secondary particles can be determined by observing any cross-section of the secondary particles using a scanning electron microscope (SEM) and performing image analysis. Specifically, multiple secondary particles are embedded in resin or similar materials, and cross-sectional samples are prepared using a cross-section polishing machine to create a state suitable for observation under a scanning electron microscope. Then, 100 secondary particles with cross-sectional sizes within ±1 μm of the volume average particle size (D50) of the lithium transition metal composite oxide particles are randomly selected. For each secondary particle, image analysis software (e.g., HALCON; MVTec) is used to detect the void portion (space portion) of the secondary particle as white and the dense portion within the outline of the secondary particle as black. The total area of ​​the white portion and the total area of ​​the black portion of the selected 100 secondary particles are calculated, and the area ratio of the space portion to the cross-sectional area of ​​the secondary particle [white portion / (white portion + black portion)] is calculated, thereby allowing the calculation of the porosity. The porosity of the secondary particles of the positive electrode active material for non-aqueous electrolyte secondary batteries containing aluminum compounds is comparable to that of the secondary particles (matrix) containing lithium transition metal composite oxides.

[0038] The lithium transition metal composite oxide constituting the positive electrode active material may, for example, include 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). Additionally, the lithium transition metal composite oxide may further contain a first metal element, which includes at least one selected from aluminum (Al) and manganese (Mn). Furthermore, the lithium transition metal composite oxide may further contain a second metal element, which includes at least one selected from 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), erbium (Er), cerium (Ce), neodymium (Nd), lanthanum (La), cadmium (Cd), and lutetium (Lu). The second metallic element may be at least one selected from zirconium (Zr), titanium (Ti), magnesium (Mg), tantalum (Ta), niobium (Nb), molybdenum (Mo), and tungsten (W).

[0039] In lithium transition metal composite oxides, the ratio of the molar number of nickel to the total molar number of metal elements other than lithium can be greater than 0, preferably 0.33 or higher. The ratio of the molar number of nickel to the total molar number of metal elements other than lithium can be 0.4 or higher, or 0.45 or higher. Furthermore, the ratio of the molar number of nickel to the total molar number of metal elements other than lithium can be less than 1, preferably 0.95 or lower, 0.8 or lower, or 0.6 or lower. When the molar number ratio of nickel is within the above range, it is possible to achieve both high charge / discharge capacity and cycle characteristics at high voltages in non-aqueous electrolyte secondary batteries.

[0040] When the lithium transition metal composite oxide contains cobalt, the ratio of the molar number of cobalt to the total molar number of metal elements other than lithium can be greater than 0, preferably 0.01, more preferably 0.02 or more, 0.05 or more, 0.1 or more, or 0.15 or more. Conversely, the ratio of the molar number of cobalt to the total molar number of metal elements other than lithium can be less than 1, preferably 0.6 or less, 0.4 or less, or 0.35 or less. Furthermore, the ratio of the molar number of cobalt to the total molar number of metal elements other than lithium can be 0.33 or less, 0.3 or less, or 0.25 or less. When the molar number ratio of cobalt is within the above range, sufficient charge-discharge capacity at high voltage can be achieved in a non-aqueous electrolyte secondary battery.

[0041] When the lithium transition metal composite oxide includes at least one of manganese and aluminum, the ratio of the total molar number of manganese and aluminum to the total molar number of metal elements other than lithium can be greater than 0, preferably 0.01 or more, more preferably 0.05 or more, 0.1 or more, or 0.15 or more. Furthermore, the ratio of the total molar number of manganese and aluminum to the total molar number of metal elements other than lithium can be 0.6 or less, preferably 0.35 or less. Additionally, the ratio of the total molar number of manganese and aluminum to the total molar number of metal elements other than lithium can be 0.33 or less, or 0.3 or less. When the ratio of the total molar number of manganese and aluminum is within the above range, a balance between charge / discharge capacity and safety can be achieved in non-aqueous electrolyte secondary batteries.

[0042] The ratio of the molar number of lithium to the total molar number of metal elements other than lithium in the lithium transition metal composite oxide can be, for example, 0.95 or more, preferably 1.0 or more, 1.03 or more, or 1.05 or more. Conversely, the ratio of the molar number of lithium to the total molar number of metal elements other than lithium can be, for example, 1.5 or less, preferably 1.3 or less, 1.25 or less, or 1.2 or less. When the molar number ratio of lithium is 0.95 or more, the interfacial resistance at the interface between the positive electrode surface and the non-aqueous electrolyte in a non-aqueous electrolyte secondary battery using a positive electrode active material containing the obtained lithium transition metal composite oxide is suppressed, thus tending to improve the output of the non-aqueous electrolyte secondary battery. On the other hand, when the molar number ratio of lithium is 1.5 or less, there is a tendency to increase the initial discharge capacity when using a positive electrode active material in the positive electrode of a non-aqueous electrolyte secondary battery.

[0043] When the lithium transition metal composite oxide contains cobalt and manganese in addition to nickel, the molar ratio of nickel, cobalt, and manganese can be, for example, nickel:cobalt:manganese = (0.33-0.95):(0.02-0.6):(0.01-0.35), preferably (0.33-0.8):(0.05-0.35):(0.05-0.35). When the lithium transition metal composite oxide contains cobalt, manganese, and aluminum in addition to nickel, the molar ratio of nickel, cobalt, and (manganese + aluminum) can be, for example, nickel:cobalt:(manganese + aluminum) = (0.33-0.95):(0.02-0.6):(0.01-0.35), preferably (0.33-0.8):(0.05-0.35):(0.05-0.35).

[0044] When a lithium transition metal composite oxide contains at least one second metal element, the ratio of the total molar number of the second metal element to the total molar number of metal elements other than lithium can be greater than 0, preferably 0.001 or more, or 0.003 or more. Furthermore, the ratio of the total molar number of the second metal element to the total molar number of metal elements other than lithium can be 0.05 or less, preferably 0.02 or less, or 0.015 or less. Particularly when tungsten is included as the second metal element, by setting the ratio of the molar number of tungsten to the total molar number of metal elements other than lithium to 0.05 or more and 0.15 or less, it is desirable to obtain particles with higher porosity.

[0045] Lithium transition metal composite oxides can, for example, have the composition shown in formula (1). Lithium transition metal composite oxides can have a layered structure or a hexagonal crystal structure.

[0046] Li p Ni x Co y M 1z M 2 w O 2+α (1)

[0047] In the formula, p, x, y, z, w, and α satisfy 1.0≤p≤1.3, 0≤x≤1, 0≤y≤1, 0≤z≤1, 0≤w≤0.05, x+y+z+w=1, and -0.1≤α≤0.1. x, y, z, and w can satisfy 0<x<1, 0≤y≤0.6, 0≤z≤0.6, and 0≤w≤0.05, and can satisfy 0.33≤x≤0.95, 0.01≤y≤0.6, 0≤z≤0.35, and 0≤w≤0.05, and can satisfy 0.33≤x≤0.8, 0.02≤y≤0.35, 0.05≤z≤0.35, and 0≤w≤0.02.

[0048] M 1 It may contain at least one of Mn and Al. M 2 It may contain at least one selected 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, and may contain at least one selected from Zr, Ti, Mg, Ta, Nb, Mo and W.

[0049] The content of lithium transition metal composite oxide particles in the positive electrode active material can 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 lithium transition metal composite oxide particles in the positive electrode active material can be, for example, less than 100% by mass, preferably less than 99% by mass or less, or less than 98% by mass.

[0050] Aluminum compounds

[0051] In addition to lithium transition metal composite oxide particles, the positive electrode active material may also contain aluminum compounds. The aluminum compounds in the positive electrode active material can exist independently of the lithium transition metal composite oxide particles as aluminum compound particles, and at least a portion of the aluminum compound particles can adhere to the surface of the lithium transition metal composite oxide particles. From the viewpoint of the flowability of the positive electrode active material as a powder, the adhesion of the aluminum compound particles to the surface of the lithium transition metal composite oxide particles is preferably physical adsorption. Physical adsorption can be based, for example, on van der Waals forces. Furthermore, from the viewpoint of the flowability of the positive electrode active material as a powder, the adhesion of the aluminum compound particles to the surface of the lithium transition metal composite oxide particles preferably does not involve a chemical reaction between the aluminum compound and the lithium transition metal composite oxide. A chemical reaction between the aluminum compound and the lithium transition metal composite oxide can be promoted, for example, by heat treatment or mechanochemical treatment of the mixture of the aluminum compound and the lithium transition metal composite oxide. Therefore, the positive electrode active material can be a non-heat-treated material containing both aluminum compounds and lithium transition metal composite oxides. Here, "non-heat-treated material" refers to a substance obtained by not subjecting a mixture containing aluminum compounds and lithium transition metal composite oxides to heat treatment at temperatures above 300°C or 200°C for, for example, more than 2 hours or more or more than 30 minutes. By making the positive electrode active material a non-heat-treated material, the improved fluidity effect resulting from mixing in aluminum compounds is sometimes further enhanced.

[0052] Examples of aluminum compounds constituting the positive electrode active material include aluminum oxide (e.g., Al₂O₃), aluminum hydroxide, aluminum chloride, aluminum nitrate, aluminum nitride, etc., preferably at least one of them. By including specific aluminum compounds, the influence on output characteristics and viscosity of the slurry containing the positive electrode active material is sometimes reduced, and the flowability of the positive electrode active material as a powder is further improved.

[0053] From the viewpoint of the flowability of the positive electrode active material as a powder, the average particle size of the aluminum compound can 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. Furthermore, the average particle size is preferably 300 nm or less, 100 nm or less, or 50 nm or less. By making the average particle size of the aluminum compound within the above range, there is a tendency to more efficiently improve the flowability of the process.

[0054] From the viewpoint of the output characteristics of a non-aqueous electrolyte secondary battery, the content of aluminum compound in the positive electrode active material relative to 1 mole of lithium transition metal composite oxide can, for example, be 2 mol% or less, preferably 1.8 mol% or less, or 1.5 mol% or less. Furthermore, from the viewpoint of the flowability of the positive electrode active material as a powder, the content of aluminum compound in the positive electrode active material relative to 1 mole of lithium transition metal composite oxide can, for example, be 0.01 mol% or more, preferably 0.05 mol% or more, or 0.1 mol% or more. In one embodiment, the content of aluminum compound in the positive electrode active material relative to 1 mole of lithium transition metal composite oxide can be 0.01 mol% or more and 2 mol% or less.

[0055] Tungsten compounds

[0056] The positive electrode active material can further contain tungsten compounds, or particles containing tungsten compounds. By including tungsten compounds in the positive electrode active material, the viscosity increase of the slurry containing the positive electrode active material can sometimes be effectively suppressed, for example. This is especially true for lithium transition metal composite oxide particles with a volume average particle size of less than 4.7 μm and a specific surface area of ​​1.3 m². 2 At concentrations of / g or higher, there is a tendency for the inhibition effect on viscosity increase to further increase. The tungsten compound in the positive electrode active material can exist independently of the lithium transition metal composite oxide particles, and at least a portion of the tungsten compound can adhere to the surface of the lithium transition metal composite oxide particles. Furthermore, at least a portion of the tungsten compound can react with lithium, being contained in the positive electrode active material in the form of lithium tungstate. From the viewpoint of the flowability of the slurry containing the positive electrode active material, the adhesion of the tungsten compound to the surface of the lithium transition metal composite oxide particles is preferably physical adsorption.

[0057] The tungsten compound constituting the positive electrode active material is preferably tungsten oxide (e.g., WO3). By including a specific tungsten compound, it is sometimes possible to effectively suppress the viscosity increase of the slurry containing the positive electrode active material.

[0058] From the viewpoint of suppressing the viscosity increase of the slurry containing the positive electrode active material, the average particle size of the tungsten compound can 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. Furthermore, the average particle size is preferably 1.7 μm or less or 1.5 μm or less. Here, the average particle size of the tungsten compound can be measured in terms of volume average particle size using a laser diffraction particle size distribution measuring device (SALD-3100 manufactured by Shimadzu Corporation).

[0059] The content of tungsten compounds in the positive electrode active material can be, for example, 0.1 mol% or more and 2 mol% or less, relative to 1 mole of lithium transition metal composite oxide. From the viewpoint of the output characteristics of a non-aqueous electrolyte secondary battery, the content of tungsten compounds in the positive electrode active material is preferably 1.8 mol% or less, or 1.5 mol% or less, relative to 1 mole of lithium transition metal composite oxide. Furthermore, from the viewpoint of suppressing the viscosity increase of the slurry containing the positive electrode active material, the content of tungsten compounds in the positive electrode active material is preferably 0.2 mol% or more, or 0.3 mol% or more, relative to 1 mole of lithium transition metal composite oxide.

[0060] Metal compounds

[0061] In one embodiment, the positive electrode active material may contain other metal compounds instead of aluminum compounds. Examples of other metal compounds include tungsten compounds, titanium compounds, zirconium compounds, silicon compounds, magnesium compounds, etc., and at least one selected from these may be included. From the viewpoint of balancing flowability and output characteristics, it is preferable that the other metal compound includes at least one selected from tungsten compounds, titanium compounds, silicon compounds, and magnesium compounds; considering the slurry viscosity during positive electrode fabrication, it is more preferable to include at least one tungsten compound. Other metal compounds may be, for example, oxides, hydroxides, nitrides, etc. Furthermore, the average particle size of the other metal compounds may be, for example, 0.01 μm or more and 2 μm or less. The content of other metal compounds in the positive electrode active material may be, for example, 0.1 mol% or more and 2 mol% or less, relative to 1 mole of lithium transition metal composite oxide.

[0062] Method for manufacturing positive electrode active material for non-aqueous electrolyte secondary batteries

[0063] A method for manufacturing positive electrode active materials for non-aqueous electrolyte secondary batteries may include: a preparation step of preparing particles containing lithium transition metal composite oxides, and a mixing step of mixing the particles containing lithium transition metal composite oxides with an aluminum compound having an average particle size of 1 nm or more and less than 500 nm to obtain a mixture. The volume average particle size of the prepared lithium transition metal composite oxide particles may be 1 μm or more and 8 μm or less, and the specific surface area may be 1.3 m². 2 / g or more.

[0064] Preparation process

[0065] In the preparation process, desired particles containing lithium transition metal composite oxides (hereinafter sometimes simply referred to as "lithium transition metal composite oxide particles") are prepared. Lithium transition metal composite oxide particles can be prepared by purchasing, etc., or by manufacturing using the lithium transition metal composite oxide manufacturing method described later. The details and preferred methods for preparing the lithium transition metal composite oxide particles are the same as those described for lithium transition metal composite oxide particles in the section on positive electrode active materials for non-aqueous electrolyte secondary batteries.

[0066] Mixing process

[0067] In the mixing process, lithium transition metal composite oxide particles are mixed with an aluminum compound to obtain a mixture. The resulting mixture can be a positive electrode active material for non-aqueous electrolyte secondary batteries. The mixing of lithium transition metal composite oxide particles and aluminum compounds can be carried out, for example, by dry mixing using a high-speed shear mixer or the like. The mixing temperature can be, for example, 10°C or higher and 100°C or lower, preferably 25°C or higher and 60°C or lower.

[0068] The average particle size of the aluminum compound used in the mixing process can be, for example, greater than 1 nm and less than 500 nm. Details regarding the aluminum compound and preferred methods are as described above.

[0069] The amount of aluminum compound mixed with the lithium transition metal composite oxide particles in the mixing process can be, for example, 2 mol% or less relative to 1 mole of the lithium transition metal composite oxide, preferably 1.8 mol% or less or 1.5 mol% or less. The amount of aluminum compound mixed in the mixing process relative to 1 mole of the lithium transition metal composite oxide can be, for example, 0.01 mol% or more, preferably 0.05 mol% or more or 0.1 mol% or more.

[0070] The method for manufacturing the positive electrode active material may further include mixing lithium transition metal composite oxide particles and a tungsten compound. The mixing of the lithium transition metal composite oxide particles and the tungsten compound can be performed simultaneously with the mixing of the lithium transition metal composite oxide particles and the aluminum compound, or they can be performed separately and gradually. From a flowability perspective, it is preferable to mix the lithium transition metal composite oxide particles and the tungsten compound after mixing with the aluminum compound. The mixing of the lithium transition metal composite oxide particles and the tungsten compound can be carried out, for example, by dry mixing using a high-speed shear mixer or the like. The mixing temperature can be, for example, 10°C or higher and 100°C or lower, preferably 25°C or higher and 60°C or lower.

[0071] The average particle size of the tungsten compound used in the mixing with lithium transition metal composite oxide particles can be, for example, 0.05 μm or more and 2 μm or less. Details and preferred methods for the tungsten compound are as described above.

[0072] The amount of tungsten compound mixed with lithium transition metal composite oxide particles can be, for example, 0.1 mol% or more and 2 mol% or less relative to 1 mole of lithium transition metal composite oxide. The amount of tungsten compound mixed with 1 mole of lithium transition metal composite oxide is preferably 1.8 mol% or less, or 1.5 mol% or less, or 0.2 mol% or more, or 0.3 mol% or more.

[0073] The manufacturing method of positive electrode active material can further include drying process, granulation process, etc. after the mixing process.

[0074] The manufacturing method of the positive electrode active material preferably does not include a heat treatment step of heat-treating the mixture containing lithium transition metal composite oxide particles and aluminum compounds. By omitting the heat treatment step, the flowability of the positive electrode active material can be well maintained. Here, the heat treatment step refers to holding the mixture containing lithium transition metal composite oxide particles and aluminum compounds at a temperature of, for example, 300°C or higher, or 200°C or higher, for, for, for, at, for, 2 hours or higher, or 30 minutes or higher. Therefore, in this specification, obtaining the mixture at a temperature of, for example, 150°C or lower is not considered heat treatment.

[0075] Method for manufacturing lithium transition metal composite oxides

[0076] The lithium transition metal composite oxide particles used in the manufacturing method of the positive electrode active material can be manufactured, for example, by the following manufacturing method. The manufacturing method of the lithium transition metal composite oxide may include: a composite oxide preparation step of preparing a composite oxide containing nickel; and a synthesis step of mixing the nickel-containing composite oxide with a lithium compound and subjecting it to heat treatment to obtain a lithium transition metal composite oxide containing lithium and nickel and having a layered structure. The manufactured lithium transition metal composite oxide may contain secondary particles, which are aggregates of multiple primary particles containing lithium transition metal composite oxides.

[0077] Composite oxide preparation process

[0078] In the composite oxide preparation process, a nickel-containing composite oxide (hereinafter also referred to as "nickel composite oxide") is prepared. The prepared nickel composite oxide may contain secondary particles, which are aggregates of multiple primary particles containing nickel composite oxide. The nickel composite oxide can be prepared by purchasing, etc., or by manufacturing using the nickel composite oxide manufacturing method described later. Details regarding the prepared nickel composite oxide will be explained later.

[0079] Synthesis process

[0080] The synthesis process includes: mixing a prepared nickel composite oxide with a lithium compound to obtain a lithium mixture; and heat-treating the lithium mixture to obtain a lithium transition metal composite oxide containing lithium and nickel and having a layered structure. In this synthesis process, the lithium transition metal composite oxide is obtained by the diffusion of lithium contained in the lithium compound into the nickel composite oxide.

[0081] Examples of methods for mixing nickel composite oxides and lithium compounds include: dry mixing of nickel composite oxides and lithium compounds using a stirred mixer or similar equipment; and wet mixing of a nickel composite oxide slurry using a mixer such as a ball mill. Examples of lithium compounds include: lithium hydroxide, lithium nitrate, lithium carbonate, and mixtures thereof.

[0082] The ratio of the number of moles of lithium to the total number of moles of metal elements other than lithium in a lithium mixture (also known as the lithium ratio) can be, for example, 0.9 or more and 1.3 or less, preferably 1 or more and 1.2 or less. When the lithium ratio is 0.9 or more, the formation of byproducts tends to be suppressed. In addition, when the lithium ratio is 1.3 or less, the increase in the amount of alkaline components present on the surface of the lithium mixture is suppressed, and the water adsorption caused by the deliquescence of the alkaline components is suppressed, which tends to improve operability.

[0083] In the mixing of nickel composite oxide and lithium compound, in addition to the lithium compound, at least one elemental, alloy, or compound containing a second metal element selected from magnesium, calcium, titanium, zirconium, niobium, tantalum, chromium, molybdenum, tungsten, iron, copper, silicon, tin, bismuth, gallium, yttrium, samarium, erbium, cerium, neodymium, lanthanum, cadmium, and lutetium can be further mixed. Examples of compounds containing a second metal element include hydroxides, oxides, and carbonates. The second metal element can be at least one selected from zirconium, titanium, magnesium, tantalum, niobium, molybdenum, and tungsten. Particularly when tungsten is included as the second metal element, particles with higher porosity can be obtained, tending to form batteries with high output characteristics; therefore, the inclusion of tungsten is preferred.

[0084] The heat treatment temperature in the synthesis process can 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. Furthermore, the heat treatment temperature is preferably 960°C or lower, 940°C or lower, or 920°C or lower. The heat treatment of the mixture can be carried out at a single temperature, but from the viewpoint of particle control, it is preferable to carry it out at multiple temperatures. When heat treatment is carried out at multiple temperatures, for example, it is preferable to hold a first temperature for a given time, then further raise the temperature and hold it at a second temperature for a given 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 for the increase of unreacted lithium components to be suppressed. When the heat treatment temperature is 990°C or lower, there is a tendency for the decomposition of the generated lithium transition metal complex oxide to be suppressed. Furthermore, from the viewpoint of obtaining lithium transition metal composite oxides with high porosity, it is preferable to perform heat treatment at a temperature of 800°C or higher and 980°C or lower for 8 hours or more, more preferably at a temperature of 810°C or higher and 920°C or lower for 8 hours or more, and the heat treatment time can be, for example, 20 hours or less. The heat treatment time, in terms of the time spent holding the highest temperature, can be, for example, 2 hours or more, preferably 4 hours or more, or 6 hours or more. Additionally, the heat treatment time can be, for example, 20 hours or less, preferably 18 hours or less, or 12 hours or less; in the case of heat treatment at multiple temperatures, it can be set to 1 hour or more and 19 hours or less respectively. The gas atmosphere for heat treatment can be in the presence of oxygen, preferably a gas atmosphere containing 10% by volume or more and 100% by volume or less of oxygen.

[0085] In the manufacturing method of lithium transition metal composite oxides, after the synthesis process, the obtained heat-treated material can be subjected to coarse crushing, pulverizing, dry sieving, and other treatments as needed.

[0086] Method for manufacturing nickel composite oxides

[0087] A method for manufacturing nickel composite oxides may include, for example, a first solution preparation step of preparing a first solution containing nickel ions and, if necessary, cobalt ions; a second solution preparation step of preparing a second solution containing a complex ion forming factor; a liquid medium preparation step of preparing a liquid medium with a pH range of 10 or higher and 13.5 or lower; a crystallization step of supplying the first and second solutions separately and simultaneously to the liquid medium and obtaining a reaction solution with a pH range maintained at 10 or higher and 13.5 or lower; a composite hydroxide recovery step of obtaining a composite hydroxide containing nickel from the reaction solution; and a composite hydroxide heat treatment step of heat-treating the obtained composite hydroxide to obtain nickel composite oxides. For details of such methods for obtaining composite oxides, please refer to, for example, Japanese Patent Application Publication No. 2003-292322 and Japanese Patent Application Publication No. 2011-116580 (US Patent Application Publication No. 2012 / 270107).

[0088] Solution preparation step 1

[0089] In the first solution preparation step, a first solution containing nickel ions and, if necessary, cobalt ions is prepared. The first solution can be prepared by dissolving a given amount of salts containing each metal element in water, according to the composition of the target nickel composite oxide. Examples of salts include nitrates, sulfates, and hydrochlorides. Furthermore, an acidic substance (e.g., an aqueous sulfuric acid solution) can be added to the water during the preparation of the first solution. This sometimes facilitates the dissolution of salts containing each metal element. An alkaline substance can be further added to adjust the pH during the preparation of the first solution. Additionally, the total number of moles of metal elements such as nickel in the first solution can be appropriately set according to the average particle size of the target nickel composite oxide. Here, the total number of moles of metal elements refers to 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 the first solution contains nickel, cobalt, and manganese.

[0090] In addition to nickel ions, the first solution may also contain at least one of cobalt ions, aluminum ions, and manganese ions. Furthermore, in addition to the ions mentioned above, the first solution may also contain ions of at least one second metallic element selected from magnesium, calcium, titanium, zirconium, niobium, tantalum, chromium, molybdenum, tungsten, iron, copper, silicon, tin, bismuth, gallium, yttrium, samarium, erbium, cerium, neodymium, lanthanum, cadmium, and lutetium. The second metallic element may be at least one selected from zirconium, titanium, magnesium, tantalum, niobium, molybdenum, and tungsten.

[0091] The concentration of nickel, cobalt, and other metal ions in the first solution, in total, can be, for example, 1.0 mol / L or more and 2.6 mol / L or less. Preferably, the metal ion concentration is 1.5 mol / L or more, or 1.7 mol / L or more. Furthermore, the metal ion concentration is preferably 2.2 mol / L or less, or 2.0 mol / L or less. When the metal ion concentration in the first solution is 1.0 mol / L or more, each reaction vessel can obtain a sufficient amount of crystals, thus improving productivity. On the other hand, when the metal ion concentration in the first solution is 2.6 mol / L or less, the saturation concentration of the metal salt exceeding room temperature can be suppressed, and the decrease in the metal ion concentration in the solution caused by the precipitation of metal salt crystals is inhibited.

[0092] Second solution preparation process

[0093] In the second solution preparation step, a second solution containing a complex ion forming factor is prepared. The second solution contains a complex ion forming factor capable of forming a complex ion with the metal ions contained in the first solution. For example, if the complex ion forming factor is ammonia, an aqueous ammonia solution can be used as the second solution. The ammonia content in the aqueous ammonia solution can be, for example, 5% by mass or more and 25% by mass or less. Preferably, the ammonia content can be 10% by mass or more, or 12% by mass or more. Preferably, the ammonia content can be 20% by mass or less, or 18% by mass or less.

[0094] Liquid medium preparation process

[0095] In the liquid medium preparation step, a liquid medium with a pH range of 10 or higher and 13.5 or lower is prepared. For example, the liquid medium can be prepared in a reaction vessel using a given amount of alkaline solution such as water and an aqueous sodium hydroxide solution to achieve a pH of 10 or higher and 13.5 or lower. By adjusting the pH of the solution to 10 or higher and 13.5 or lower, pH fluctuations in the reaction solution during the initial stages of the reaction can be suppressed.

[0096] Crystallization process

[0097] In the crystallization process, the pH of the resulting reaction solution is maintained within a range of 10 or higher and 13.5 or lower, and the first and second solutions are supplied to the liquid medium separately and simultaneously. This allows the production of nickel-containing composite hydroxide particles from the reaction solution. In addition to the first and second solutions, an alkaline solution can also be supplied to the liquid medium simultaneously. This makes it easy to maintain the pH of the reaction solution within a range of 10 or higher and 13.5 or lower.

[0098] In the crystallization process, it is preferable to supply each solution with the pH of the reaction solution maintained in a range of 10 or higher and 13.5 or lower. For example, the pH of the reaction solution can be maintained in a range of 10 or higher and 13.5 or lower by adjusting the supply amount of the second solution based on the supply amount of the first solution. When the pH of the reaction solution is 10 or higher, the amount of impurities (e.g., sulfuric acid components other than metals or nitric acid components contained in the reaction solution) contained in the resulting composite hydroxide is sufficiently reduced, and the tendency to reduce the capacity of the non-aqueous electrolyte secondary battery as the final product is suppressed. In addition, when the pH is 13.5 or lower, the formation of small secondary particles is suppressed, and sometimes the operability of the resulting composite hydroxide is improved. The pH of the reaction solution maintained is preferably 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 is, for example, 25°C or higher and 80°C or lower, and preferably controlled in a range of 40°C or higher and 75°C or lower, or 50°C or higher and 70°C or lower. The gas atmosphere in the crystallization process can be set to a low-oxidizing gas atmosphere, for example, the oxygen concentration can be kept below 10% by volume.

[0099] In the crystallization process, the concentration of nickel ions in the reaction solution can 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 higher, the complex hydroxide is fully precipitated. When the concentration of nickel ions is 1000 ppm or lower, the amount of dissolved nickel is small, thus suppressing deviation from the target composition. Regarding the nickel ion concentration, for example, if an aqueous ammonia solution is used in the second solution (complex ion forming solution), it can be adjusted by supplying the second solution with an ammonium ion concentration in the reaction solution of 1000 ppm to 15000 ppm.

[0100] The time for supplying the first solution can be, for example, 6 hours or more and 60 hours or less, and preferably 8 hours or more or 10 hours or more. Furthermore, the time for supplying the first solution is preferably 42 hours or less, 24 hours or less, or 18 hours or less. When the time is 6 hours or more, the precipitation rate of the composite hydroxide slows down, thus tending to yield nickel composite oxides with higher smoothness. Furthermore, when the time is 60 hours or less, productivity can be further improved.

[0101] The value obtained by using the total number of moles of nickel, etc., supplied in the first solution throughout the entire crystallization process as the denominator and the total number of moles of nickel, etc., supplied in the first solution per hour as the numerator can be, for example, 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. A value of 0.015 or more can further improve productivity. Furthermore, a value of 0.125 or less tends to yield nickel composite oxides with a larger specific surface area.

[0102] The method for manufacturing nickel complex oxides may include a seed generation step prior to the crystallization step. In the seed generation step, for example, a portion of a prepared first solution is supplied to a liquid medium to generate, for example, seed crystals of a nickel-containing complex hydroxide in the liquid medium. That is, the liquid medium supplied to the crystallization step may be a seed solution containing a nickel-containing complex hydroxide. The temperature in the seed generation step may be set, for example, to 40°C to 80°C. The gas atmosphere in the seed generation step may be a low-oxidizing gas atmosphere, for example, the oxygen concentration may be maintained below 10% by volume.

[0103] If composite hydroxide particles are pre-generated in the liquid medium before the crystallization process, each pre-generated composite hydroxide particle will become a seed crystal for the composite hydroxide particles obtained after the crystallization process. Therefore, the total number of secondary particles in the composite hydroxide obtained after the crystallization process can be controlled by the number of pre-generated composite hydroxide particles. For example, when a large amount of the first solution is supplied beforehand, the number of generated composite hydroxide particles increases, thus tending to decrease the average particle size of the secondary particles in the composite hydroxide obtained after the crystallization process.

[0104] In the crystallization process, the first solution and the second solution can be supplied to the liquid medium continuously or intermittently. The first solution is supplied continuously throughout the entire supply time of the first solution in the crystallization process. Here, "continuously throughout the entire supply time" means that there is essentially no time without supply during the entire supply time. Furthermore, "no time without supply" means that the time without supply is less than 1% of the total supply time.

[0105] Complex hydroxide recovery process

[0106] In the complex hydroxide recovery process, nickel-containing complex hydroxides are separated from the reaction solution and recovered. Recovery of complex hydroxides from the reaction solution can be achieved through commonly used separation methods such as filtration to remove the generated precipitate and centrifugation. The obtained precipitate can be treated by washing, filtering, and drying. The metal element composition ratio in the complex hydroxide can be substantially consistent with the metal element composition ratio excluding lithium in the lithium transition metal complex oxide obtained using it as a raw material.

[0107] Composite hydroxide heat treatment process

[0108] In the heat treatment process of the composite hydroxide, the obtained composite hydroxide is heat-treated to obtain nickel composite oxide. Through heat treatment, the composite hydroxide is dehydrated to generate nickel composite oxide. Nickel composite oxide can be a precursor of lithium transition metal composite oxide or a precursor of positive electrode active material.

[0109] The heat treatment temperature can 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 can be, for example, 5 hours or higher and 30 hours or lower, preferably 10 hours or higher and 20 hours or lower. The gas atmosphere for heat treatment can be an oxygen-containing gas atmosphere or an atmospheric atmosphere.

[0110] For nickel composite oxides, the ratio of the number of moles of nickel to the total number of moles of metal elements contained in the nickel composite oxide can be, for example, greater than 0 and less than 1. Preferably, the ratio of the number of moles of nickel to the total number of moles of metal elements is 0.33 or more. The ratio of the number of moles of nickel to the total number of moles of metal elements can be 0.4 or more, or 0.45 or more. Furthermore, the ratio of the number of moles of nickel to the total number of moles of metal elements is preferably 0.95 or less, 0.8 or less, or 0.6 or less.

[0111] Nickel composite oxides may contain cobalt in their composition. When cobalt is included in the composition of a nickel composite oxide, the ratio of the molar number of cobalt to the total molar number of metal elements contained in the nickel composite oxide may be greater than 0 and less than 1. Preferably, the ratio of the molar number of cobalt to the total molar number of metal elements may be 0.01 or more, 0.02 or more, 0.05 or more, 0.1 or more, or 0.15 or more. Furthermore, the ratio of the molar number of cobalt to the total molar number of metal elements is preferably 0.6 or less. The ratio of the molar number of cobalt to the total molar number of 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.

[0112] Nickel composite oxides may contain at least one of manganese and aluminum in their composition. When a nickel composite oxide contains at least one of manganese and aluminum, the ratio of the total molar number of manganese and aluminum to the total molar number of the metal elements contained in the nickel composite oxide is, for example, greater than 0, preferably 0.01 or more, more preferably 0.05 or more, further preferably 0.1 or more, and particularly preferably 0.15 or more. Furthermore, the ratio of the total molar number of manganese and aluminum to the total molar number of the metal elements is, for example, 0.6 or less, preferably 0.35 or less. The ratio of the total molar number of manganese and aluminum to the total molar number of the metal elements may be 0.33 or less, or 0.3 or less.

[0113] Nickel composite oxides may contain at least one second metallic element in their composition. When a nickel composite oxide contains at least one second metallic element, the ratio of the total moles of the second metallic element to the total moles of the metallic elements contained in the nickel composite oxide may, for example, be greater than 0, greater than 0.001, or greater than 0.003. Alternatively, the ratio of the total moles of the second metallic element to the total moles of the metallic elements may, for example, be less than 0.05, less than 0.02, less than 0.015, or less than 0.01.

[0114] Nickel composite oxides can, for example, have the composition shown in formula (2).

[0115] Ni q Co r M 1 s M 2 t O 2+β (2)

[0116] In equation (2), M 1 It represents at least one of Mn and Al. M 2 The expression indicates that at least one of the following is selected 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. q, r, s, t, and β satisfy 0 < q < 1, 0 ≤ r ≤ 0.6, 0 ≤ s ≤ 0.6, 0 ≤ t ≤ 0.02, -0.1 ≤ β ≤ 1.1, and q + r + s + t = 1. Preferably, the values ​​are 0.33 ≤ q ≤ 0.95, 0.02 ≤ r ≤ 0.35, 0.01 ≤ s ≤ 0.35, and 0 ≤ t ≤ 0.015. Furthermore, M is preferred. 2 It is selected from at least one of Zr, Ti, Mg, Ta, Nb, Mo and W.

[0117] The tap density of nickel composite oxides can be 1.3 g / cm³. 3 The preferred value is 1.15 g / cm³. 3 The following, or more preferably, can be 1 g / cm 3 The following, and further preferred, value is 0.96 g / cm³. 3 The following is an explanation. Additionally, the tap density of nickel composite oxides can be greater than 0 g / cm³. 3 The preferred value is 0.2 g / cm³. 3 Above, or 0.4 g / cm 3 The above is the result of achieving a tap density of 1.3 g / cm³ for the nickel composite oxide. 3The following approach tends to produce lithium transition metal composite oxides with larger specific surface areas. When the ratio of the molar number of nickel to the total molar number of metal elements contained in the nickel composite oxide is 0.5 or more, lithium transition metal composite oxides obtained by reacting a mixture of nickel composite oxide, lithium compound, and tungsten compound tend to produce particles with higher porosity, and have a tendency to further improve output characteristics.

[0118] The particle size of the nickel composite oxide can 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. Furthermore, the particle size of the nickel composite oxide is preferably 6 μm or less, 5 μm or less, or 4 μm or less. By making the particle size of the nickel composite oxide 1 μm or more and 8 μm or less, while satisfying the above-mentioned tap density range, there is a tendency to produce lithium transition metal composite oxide particles with a larger specific surface area.

[0119] Electrodes for non-aqueous electrolyte secondary batteries

[0120] An electrode for a non-aqueous electrolyte secondary battery includes a current collector and a positive electrode active material layer, wherein the positive electrode active material layer is disposed on the current collector and contains the aforementioned positive electrode active material. A non-aqueous electrolyte secondary battery with this electrode can achieve excellent output characteristics.

[0121] The density of the positive electrode active material layer can be, for example, 2.6 g / cm³. 3 Above and 3.9g / cm 3 The preferred value is 2.8 g / cm³. 3 Above and 3.8g / cm 3 Below, 3.1g / cm 3 Above and 3.7g / cm 3 Below, or 3.2g / cm 3 Above and 3.6g / cm 3 The density of the positive electrode active material layer can be calculated by dividing the mass of the positive electrode active material layer by its volume. Here, the density of the positive electrode active material layer can be adjusted by applying pressure after applying the electrode composition (described later) to the current collector.

[0122] Examples of materials that can be used as current collectors include aluminum, nickel, and stainless steel. The positive electrode active material layer can be formed by coating an electrode composition obtained by mixing the aforementioned positive electrode active material, conductive additive, binder, etc., with a solvent onto the current collector, followed by drying and pressure treatment. Examples of conductive additives include natural graphite, artificial graphite, and acetylene black. Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, and polyamide acrylic resin. Examples of solvents include N-methyl-2-pyrrolidone (NMP).

[0123] Non-aqueous electrolyte secondary battery

[0124] The non-aqueous electrolyte secondary battery includes the electrodes described above. In addition to the electrodes, the non-aqueous electrolyte secondary battery also includes a negative electrode, a non-aqueous electrolyte, and a separator. For the negative electrode, non-aqueous electrolyte, and separator in the non-aqueous electrolyte secondary battery, the negative electrode, non-aqueous electrolyte, and separator described in, for example, Japanese Patent Application Publication No. 2002-075367, Japanese Patent Application Publication No. 2011-146390, and Japanese Patent Application Publication No. 2006-12433 (all of which are incorporated herein by reference in their entirety), can be appropriately used.

[0125] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are examples and have a structure that is substantially the same as the technical concept described in the claims of the present invention. Of course, any manner that achieves the same effect is included within the technical scope of the present invention.

[0126] Example

[0127] The present invention will be specifically described below through examples, but the present invention is not limited to these examples. The volume average particle size was evaluated using a laser diffraction particle size distribution measuring device (SALD-3100, manufactured by Shimadzu Corporation). The specific surface area was evaluated using a BET specific surface area measuring device (Macsorb, manufactured by MOUNTECH Corporation) via nitrogen adsorption (one-point method). The porosity was evaluated using the aforementioned scanning electron microscope (SEM) and image analysis software (e.g., HALCON, manufactured by MVTec Corporation).

[0128] Example 1

[0129] Preparation of each solution

[0130] Nickel sulfate, cobalt sulfate, and manganese sulfate solutions were dissolved in water in a molar ratio of 35:35:30 to prepare solution 1 (with a total concentration of 1.7 mol / L for nickel, cobalt, and manganese ions). It should be noted that the total molar number of metal elements in solution 1 was set at 350 mol. A 25% by weight sodium hydroxide aqueous solution was prepared as an alkaline solution. A 12.5% ​​by weight ammonia aqueous solution was prepared as solution 2 (complex ion formation solution).

[0131] Preparation of liquid media

[0132] Prepare 30 liters of water in the reaction vessel and add sodium hydroxide solution to bring the pH to 12.5. Introduce nitrogen gas to displace the contents of the reaction vessel, forming the initial solution and preparing the liquid medium.

[0133] Seed production process

[0134] While stirring the liquid medium, a first solution of 10 moles (based on the total moles of nickel, etc.) is added to the liquid medium, causing a complex hydroxide containing nickel, cobalt, and manganese to precipitate.

[0135] Crystallization process

[0136] The reaction solution was maintained at a pH of approximately 10.9–11.3 with an ammonium ion concentration of approximately 4000 ppm while stirring. Over 12 hours, 340 moles of the remaining first solution, an aqueous sodium hydroxide solution, and the second solution were supplied, causing a complex hydroxide containing nickel, cobalt, and manganese to precipitate. The temperature of the reaction solution was controlled at approximately 60°C. The precipitate was washed with water, filtered, separated, and dried to obtain a complex hydroxide containing nickel, cobalt, and manganese (hereinafter referred to as "nickel-cobalt complex hydroxide"). The nickel-cobalt complex hydroxide was then heat-treated at 320°C for 16 hours under atmospheric conditions to recover the transition metal complex oxide containing nickel, cobalt, and manganese (hereinafter referred to as "complex oxide"). A volume average particle size of 4.7 μm and a tap density of 0.86 g / cm³ were obtained. 3 Composite oxides.

[0137] Synthesis process

[0138] Lithium carbonate, zirconium oxide (IV), and tungsten oxide (VI) were mixed in a composite oxide to achieve a molar ratio of Li:(Ni+Co+Mn):Zr:W = 1.19:1:0.005:0.003, resulting in a lithium mixture. The lithium mixture was then heat-treated under atmospheric conditions. The heat treatment consisted of a first temperature of 780°C for 2 hours and a second temperature of 910°C for 4 hours, yielding a heat-treated product. This heat-treated product was pulverized and dry-sieved to obtain a lithium mixture with the composition Li... 1.19 Ni 0.35 Co 0.35 Mn 0.30 Zr 0.005 W 0.003 O2 represents lithium transition metal complex oxide.

[0139] The resulting lithium transition metal composite oxide, which served as the parent material, had a volume-average particle size of 4.4 μm and a specific surface area of ​​2.06 m². 2 / g, with a porosity of 30%.

[0140] Mixing process

[0141] For the lithium transition metal composite oxide, alumina (Al2O3: manufactured by CABOT; average particle size 20-30 nm) as an aluminum compound was incorporated into the lithium transition metal composite oxide obtained above at a molar ratio of (Ni+Co+Mn):Al = 1:0.005, and then mixed using a high-speed shear mixer. Then, the positive electrode active material of Example 1 was obtained by dry sieving.

[0142] The positive electrode active material obtained in Example 1 had a volume average particle size of 4.4 μm and a specific surface area of ​​2.26 m². 2 / g, with a porosity of 30%.

[0143] The positive electrode active material obtained in Example 1 was observed using a scanning electron microscope (Hitachi High-Tech SU8230) at an accelerating voltage of 1.5 kV, and scanning electron microscope (SEM) images were obtained. The results are shown below. Figure 1 .

[0144] Comparative Example 1

[0145] In the crystallization process, the pH of the reaction solution was maintained at approximately 11.3–11.7, resulting in an ammonium ion concentration of approximately 6000 ppm. The temperature of the reaction solution was controlled at approximately 45°C. The supply time of the first solution in the crystallization process was set to 18 hours. Otherwise, similar to Example 1, particles with a volume average particle size of 3.4 μm and a tap density of 1.46 g / cm³ were obtained. 3 A composite oxide containing nickel, cobalt, and manganese was obtained. The lithium transition metal composite oxide of Comparative Example 1 was obtained using the same synthesis process as in Example 1, except that the obtained composite oxide was used.

[0146] The obtained lithium transition metal composite oxide was used as the positive electrode active material in Comparative Example 1. The positive electrode active material of Comparative Example 1 had a volume average particle size of 3.1 μm and a specific surface area of ​​1.09 m². 2 / g, with a porosity of 5%.

[0147] Example 2

[0148] In the mixing process, in addition to the aluminum compound, tungsten oxide (WO3: manufactured by Nippon Shin-Metal Corporation; average particle size 1000 nm) as a tungsten compound was added. The lithium transition metal composite oxide was formulated in a molar ratio of (Ni+Co+Mn):Al:W = 1:0.005:0.005. Otherwise, the positive electrode active material of Example 2 was obtained in the same manner as in Example 1.

[0149] The positive electrode active material obtained in Example 2 had a volume average particle size of 4.4 μm and a specific surface area of ​​2.29 m². 2 / g, with a porosity of 30%.

[0150] Example 3

[0151] In the synthesis process, the second temperature of the heat treatment was set to 910°C to 950°C. Otherwise, the lithium transition metal composite oxide of Example 3 was obtained in the same manner as in Example 2.

[0152] The positive electrode active material obtained in Example 3 had a volume average particle size of 4.3 μm and a specific surface area of ​​1.43 m². 2 / g, with a porosity of 17%.

[0153] Example 4

[0154] In the synthesis process, the second temperature of the heat treatment was set to 910°C to 880°C. Otherwise, the lithium transition metal composite oxide of Example 4 was obtained in the same manner as in Example 2.

[0155] The positive electrode active material obtained in Example 4 had a volume average particle size of 3.9 μm and a specific surface area of ​​2.90 m². 2 / g, with a porosity of 31%.

[0156] Example 5

[0157] In the synthesis process, the second temperature of the heat treatment was set to 910°C to 860°C. Otherwise, the lithium transition metal composite oxide of Example 5 was obtained in the same manner as in Example 2.

[0158] The positive electrode active material obtained in Example 5 had a volume average particle size of 3.9 μm and a specific surface area of ​​3.33 m². 2 / g, with a porosity of 31%.

[0159] Example 6

[0160] In the synthesis process, the second temperature of the heat treatment was set to 910°C to 840°C. Otherwise, the lithium transition metal composite oxide of Example 5 was obtained in the same manner as in Example 2.

[0161] The positive electrode active material obtained in Example 6 had a volume average particle size of 3.9 μm and a specific surface area of ​​3.84 m². 2 / g, with a porosity of 32%.

[0162] Reference Example 1

[0163] Except for the absence of a mixing process, the lithium transition metal composite oxide obtained in Example 1, which served as the parent material, was used as the positive electrode active material in Reference Example 1, similar to Example 1. Furthermore, SEM images were obtained as in Example 1. The results are shown below. Figure 2 .

[0164] See Example 2

[0165] In the mixing process, for the lithium transition metal composite oxide, tungsten oxide (WO3: manufactured by Nippon Shin-Metal Corporation; average particle size 1000 nm) was used instead of aluminum compound to achieve a molar ratio of (Ni+Co+Mn):W = 1:0.005. Otherwise, the positive electrode active material of Reference Example 2 was obtained in the same manner as in Example 1.

[0166] The positive electrode active material obtained in Reference Example 2 had a volume average particle size of 4.4 μm and a specific surface area of ​​2.07 m². 2 / g, with a porosity of 30%.

[0167] See Example 3

[0168] In the mixing process, for the lithium transition metal composite oxide, titanium oxide (TiO2: manufactured by Nippon Aerosil; average particle size 20-40 nm) was used instead of aluminum compound to achieve a molar ratio of (Ni+Co+Mn):Ti = 1:0.003. Otherwise, the positive electrode active material of Reference Example 3 was obtained in the same manner as in Example 1.

[0169] The positive electrode active material obtained in Reference Example 3 had a volume average particle size of 4.4 μm and a specific surface area of ​​2.13 m². 2 / g, with a porosity of 30%.

[0170] See Example 4

[0171] In the mixing process, for the lithium transition metal composite oxide, zirconium oxide (ZrO2: manufactured by TECNAN Corporation; average particle size 20-30 nm) was used instead of aluminum compound to achieve a molar ratio of (Ni+Co+Mn):Zr = 1:0.002. Otherwise, the positive electrode active material of Reference Example 4 was obtained in the same manner as in Example 1.

[0172] The positive electrode active material obtained in Reference Example 4 had a volume average particle size of 4.4 μm and a specific surface area of ​​2.21 m². 2 / g, with a porosity of 30%.

[0173] See Example 5

[0174] In the mixing process, for the lithium transition metal composite oxide, silicon dioxide (SiO2: manufactured by Nippon Aerosil; average particle size 40-50 nm) as a silicon compound was used instead of aluminum compound in a manner that (Ni+Co+Mn)∶Si=1∶0.005 (molar ratio). Otherwise, the positive electrode active material of Reference Example 5 was obtained in the same manner as in Example 1.

[0175] The positive electrode active material obtained in Reference Example 5 had a volume average particle size of 4.4 μm and a specific surface area of ​​2.16 m². 2 / g, with a porosity of 30%.

[0176] Example 7

[0177] In the mixing process, for the lithium transition metal composite oxide, aluminum oxide (Al2O3: manufactured by Sigma-Aldrich; average particle size 200-300 nm) was used instead of aluminum oxide (Al2O3: manufactured by CABOT; average particle size 20-30 nm) to achieve a molar ratio of (Ni+Co+Mn):Al = 1:0.005. Otherwise, the positive electrode active material of Example 7 was obtained in the same manner as in Example 1.

[0178] The positive electrode active material obtained in Example 7 had a volume average particle size of 4.4 μm and a specific surface area of ​​2.33 m². 2 / g, with a porosity of 30%.

[0179] Example 8

[0180] In the mixing process, for the lithium transition metal composite oxide, aluminum oxide (Al2O3: manufactured by Sumitomo Chemical Co., Ltd.; average particle size 500 nm) was used instead of aluminum oxide (Al2O3: manufactured by CABOT Co., Ltd.; average particle size 20-30 nm) to achieve a molar ratio of (Ni+Co+Mn)∶Al=1∶0.005. Otherwise, the positive electrode active material of Example 8 was obtained in the same manner as in Example 1.

[0181] The positive electrode active material obtained in Example 8 had a volume average particle size of 4.4 μm and a specific surface area of ​​2.07 m². 2 / g, with a porosity of 30%.

[0182] See Example 6

[0183] Nickel sulfate solution, cobalt sulfate solution, and manganese sulfate solution were dissolved in water in a molar ratio of 50:20:30 for each metal element to prepare the first solution (with a total concentration of 1.7 mol / L for nickel, cobalt, and manganese ions). Otherwise, similar to Example 1, a volume average particle size of 4.2 μm and a tap density of 1.05 g / cm³ were obtained. 3 The composite oxide was obtained. Furthermore, in the synthesis process, the mixture was prepared in a molar ratio of Li:(Ni+Co+Mn):Zr:W = 1.14:1:0.005:0.003, and then heat-treated at 840°C for 8 hours. Otherwise, similar to Example 1, the composite oxide with the composition Li was obtained as Reference Example 6. 1.14 Ni 0.5 Co 0.2 Mn 0.3 Zr 0.005 W 0.003 The lithium transition metal composite oxide, represented by O2, was obtained as the parent material. The volume-average particle size of the resulting lithium transition metal composite oxide was 3.9 μm, and the specific surface area was 2.09 m². 2 / g, with a porosity of 31%.

[0184] Example 9

[0185] For the lithium transition metal composite oxide, aluminum oxide (Al₂O₃: manufactured by CABOT Corporation; average particle size 20-30 nm) as an aluminum compound and tungsten oxide (WO₃: manufactured by Nippon Shinkin Industries, Ltd.; average particle size 1000 nm) as a tungsten compound were mixed with the lithium transition metal composite oxide obtained in Reference Example 6 in a manner that achieved a molar ratio of (Ni+Co+Mn):Al:W = 1:0.005:0.005, and then mixed using a high-speed shear mixer. Then, by performing dry sieving, the positive electrode active material of Example 9 was obtained.

[0186] The positive electrode active material obtained in Example 9 had a volume average particle size of 4.1 μm and a specific surface area of ​​2.35 m². 2 / g, with a porosity of 31%.

[0187] Comparative Example 2

[0188] Nickel sulfate solution, cobalt sulfate solution, and manganese sulfate solution were dissolved in water in a molar ratio of 50:20:30 for each metal element to prepare solution 1 (total concentration of nickel, cobalt, and manganese ions was 1.7 mol / L). Similar to Comparative Example 1, this solution yielded a volume average particle size of 3.1 μm and a tap density of 1.33 g / cm³. 3The composite oxide was obtained. In addition, in the synthesis process, except that the obtained composite oxide was heat-treated at 860°C for 8 hours, the positive electrode active material of Comparative Example 2 was obtained in the same manner as Comparative Example 1.

[0189] The positive electrode active material of Comparative Example 2 had a volume average particle size of 3.0 μm and a specific surface area of ​​1.27 m². 2 / g, with a porosity of 5%.

[0190] Comparative Example 3

[0191] Using the composite oxide obtained in Comparative Example 2, in the synthesis process, lithium carbonate, zirconium oxide (IV), and tungsten oxide (VI) were mixed in a molar ratio of Li:(Ni+Co+Mn):Zr:W = 1.12:1:0.005:0.01, and then heat-treated at 920°C for 8 hours in an atmospheric atmosphere to obtain Comparative Example 3, which has the composition formula Li 1.12 Ni 0.5 Co 0.2 Mn 0.3 Zr 0.005 W 0.01 O2 represents lithium transition metal complex oxide.

[0192] The lithium transition metal composite oxide obtained in Comparative Example 3 had a volume average particle size of 3.3 μm and a specific surface area of ​​1.12 m². 2 / g, with a porosity of 5%.

[0193] Example 10

[0194] In Example 9, the mixture was prepared in a synthesis process with a molar ratio of Li:(Ni+Co+Mn):Zr:W = 1.16:1:0.005:0.01, and then heat-treated at 860°C for 8 hours. Otherwise, the positive electrode active material of Example 10 was obtained in the same manner as in Example 9.

[0195] The positive electrode active material obtained in Example 10 had a volume average particle size of 3.7 μm and a specific surface area of ​​2.79 m². 2 / g, with a porosity of 36%.

[0196] Table 1

[0197]

[0198] Evaluation of process flowability

[0199] Approximately 50g of the obtained positive electrode active material was weighed and placed into a powder property analyzer (PowderTester (registered trademark); manufactured by Hosokawa Micron). The angle of repose and angle of collapse were then automatically measured, and the difference angle was calculated. The results are shown in Table 2.

[0200] Evaluation of the viscosity of positive electrode mixture slurry

[0201] The positive electrode active material obtained above was used to prepare positive electrode slurries as described below, and the viscosity of the positive electrode slurries was evaluated.

[0202] Preparation of positive electrode mixture slurry

[0203] A positive electrode slurry was prepared by dispersing 89.5 parts by mass of positive electrode active material, 5 parts by mass of acetylene black as a conductive additive, 5 parts by mass of polyvinylidene fluoride (PVDF) as a binder, and 0.5 parts by mass of polyvinylpyrrolidone (PVP) as a dispersant in N-methyl-2-pyrrolidone (NMP).

[0204] Evaluation of relative viscosity increase rate

[0205] For the prepared positive electrode slurry, the viscosity was measured immediately after preparation and 6 hours after preparation using an E-type viscometer (Thermo Scientific; HAAKE Viscotester 550). The viscosity increase rate is calculated by dividing the viscosity of the positive electrode slurry 6 hours after preparation by the viscosity immediately after preparation, as shown in the following formula.

[0206] (Slurry viscosity after 6 hours) / (Slurry viscosity immediately after preparation)

[0207] Regarding the obtained viscosity increase rate, for Examples 1-8 and Reference Examples 1-5, the relative viscosity increase rate when the viscosity increase rate of Comparative Example 1 was set to 1 was evaluated. For Reference Examples 6, Examples 9 and 10 and Comparative Example 3, the relative viscosity increase rate when the viscosity increase rate of Comparative Example 2 was set to 1 was evaluated. The results are shown in Tables 2 and 3.

[0208] Evaluation of battery manufacturing

[0209] An evaluation battery was fabricated using the positive electrode active material obtained above, following the steps outlined below.

[0210] Positive electrode production

[0211] A positive electrode slurry was prepared by dispersing 92 parts by mass of 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 slurry was coated onto an aluminum foil serving as a current collector, dried, compressed and shaped using a roller press, and cut to a given size, thereby producing the positive electrode.

[0212] Negative electrode fabrication

[0213] A negative electrode slurry was prepared by dispersing and dissolving 97.5 parts by weight of artificial graphite, 1.5 parts by weight of carboxymethyl cellulose (CMC), and 1.0 part by weight of SBR (styrene-butadiene rubber) in pure water. The obtained negative electrode slurry was coated onto a current collector made of copper foil, dried, compressed and shaped using a roller press, and cut into a given size, thereby producing the negative electrode.

[0214] After attaching lead electrodes to the current collectors of both the positive and negative electrodes, a separator was placed between the positive and negative electrodes, and they were housed in a pouch-like laminated bag. Next, the bag was vacuum-dried at 65°C to remove moisture adsorbed on each component. Then, electrolyte was injected into the laminated bag under an argon atmosphere, and the bag was sealed to produce an evaluation battery. As the electrolyte, a solution of ethylene carbonate (EC) and methyl ethyl carbonate (MEC) mixed in a volume ratio of 3:7, with lithium hexafluorophosphate (LiPF6) dissolved at a concentration of 1 mol / L, was used. The resulting evaluation battery was placed in a 25°C constant-temperature bath and aged with a weak current, followed by the following evaluation.

[0215] Evaluation of output characteristics (DC internal resistance measurement)

[0216] The DC internal resistance (DC-IR) of the evaluation battery after aging was measured. After constant current charging to 50% depth of charge at the full charge voltage of 4.2V, the evaluation battery was placed in an environment of -25°C and pulsed discharged for 10 seconds using a specific current *i*. The voltage *V* at the 10th second was measured. The intersection of the line connecting the intersection points with current *i* on the horizontal axis and voltage *V* on the vertical axis was plotted, and the slope of the line connecting the intersection points was taken as the DC internal resistance (DC-IR). It should be noted that current *i* was set to 0.02A, 0.04A, 0.06A, 0.08A, and 0.10A. A low DC-IR indicates good output characteristics.

[0217] Regarding the obtained DC internal resistance, for Examples 1-8, Comparative Examples 1, and Reference Examples 2-5, the relative DC internal resistance when the DC internal resistance of Reference Example 1 was set to 1 was evaluated. Furthermore, for Examples 9 and 10, and Comparative Examples 2 and 3, the relative DC internal resistance when the DC internal resistance of Reference Example 6 was set to 1 was evaluated. The results are shown in Tables 2 and 3.

[0218] Table 2

[0219]

[0220] Table 3

[0221]

[0222] Tables 1-3 confirm that increasing the specific surface area in particles with a volume average particle size of 4.4 μm or less improves output characteristics. Furthermore, by mixing metal compounds into these particles, a tendency for improved process flowability was observed; in particular, the operation of the slurry, including the viscosity containing the positive electrode active material, was effectively improved when alumina and tungsten oxide were mixed in.

Claims

1. A positive electrode active material for a non-aqueous electrolyte secondary battery, comprising: Particles containing lithium transition metal complex oxides, and Aluminum compounds with an average particle size of 1 nm or more but less than 100 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 ​​1.7 m². 2 / g or more and 4.0m 2 / g or less The porosity of the particles containing lithium transition metal composite oxide is above 20% and below 50%.

2. 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 the tungsten compound relative to the lithium transition metal composite oxide is 0.1 mol% or more and 2 mol% or less.

4. 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.

5. The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein, The specific surface area is 1.7m². 2 / g or more and 3.3m 2 / g or less.

6. The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein, The content of the aluminum compound is less than 2 mol% relative to the lithium transition metal composite oxide.

7. The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein, The content of the aluminum compound relative to the lithium transition metal composite oxide is 0.01 mol% or more.

8. The positive electrode active material for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein, The volume average particle size is greater than 2 μm and less than 6 μm.

9. A method for manufacturing a positive electrode active material for a non-aqueous electrolyte secondary battery, the method comprising: Prepare particles containing lithium transition metal composite oxides, and A mixture is obtained by mixing the particles containing lithium transition metal composite oxides with an aluminum compound having an average particle size of 1 nm or more and 100 nm or less. The particles containing lithium transition metal composite oxides have a volume average particle size of 1 μm or more and 8 μm or less, and a specific surface area of ​​1.5 m². 2 / g or more and 3.9m 2 / g or less The porosity of the lithium transition metal composite oxide is above 20% and below 50%.

10. The manufacturing method according to claim 9, further comprising: The lithium transition metal composite oxide and tungsten compound are mixed.

11. The manufacturing method according to claim 10, wherein, The tungsten compound has an average particle size of 0.05 μm or more and 2 μm or less.

12. The manufacturing method according to claim 10, wherein, The amount of the tungsten compound mixed with the lithium transition metal composite oxide is more than 0.1 mol% and less than 2 mol%.

13. The manufacturing method according to any one of claims 9 to 12, wherein, The lithium transition metal composite oxide contains lithium and nickel in its composition and has a layered structure.

14. The manufacturing method according to any one of claims 9 to 12, wherein, The amount of the aluminum compound mixed is less than 2 mol% relative to the lithium transition metal composite oxide.

15. The manufacturing method according to any one of claims 9 to 12, wherein, The amount of the aluminum compound mixed relative to the lithium transition metal composite oxide is 0.01 mol% or more.

16. The manufacturing method according to any one of claims 9 to 12, wherein, The volume average particle size of the particles containing lithium transition metal composite oxide is greater than 2 μm and less than 6 μm.

Images