Positive electrode active material, positive electrode including the same, and nonaqueous electrolyte secondary battery including positive electrode

Abstract

To provide a positive electrode active material that enables provision of a nonaqueous electrolyte secondary battery having an excellent capacity retention rate in charge-discharge cycles and capable of suppressing a decrease in discharge capacity.SOLUTION: The positive electrode active material includes secondary particles in which primary particles are aggregated, and the secondary particles are a lithium transition-metal composite oxide having a layered crystal structure. The lithium transition-metal composite oxide includes Li, Ni, Mn, Co, and M, and the molar ratio of Li, Ni, Mn, Co, and M is Li:Ni:Mn:Co:M=a:x:y:z:t [M, a, x, y, z, and t are as defined in the claims]. The integrated intensity ratio (I003 / I104) of diffraction peaks in X-ray diffraction of the secondary particles is 1.05 to 1.19. The crystallite size L003 of the secondary particles is at least 1000 Å.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a positive electrode active material, a positive electrode including the same, and a nonaqueous electrolyte secondary battery including the positive electrode. [Background technology]

[0002] The lithium transition metal composite oxide used as the positive electrode active material of non-aqueous electrolyte secondary batteries significantly affects battery performance. It is known that good battery performance can be achieved by adjusting the crystal structure of the lithium transition metal composite oxide (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-160801 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure aims to provide a positive electrode active material, a positive electrode, and a nonaqueous electrolyte secondary battery that can provide a nonaqueous electrolyte secondary battery that is excellent in capacity retention rate during charge / discharge cycles and can suppress a decrease in discharge capacity. [Means for solving the problem]

[0005] [1] Contains secondary particles formed by aggregation of primary particles, the secondary particles are lithium transition metal composite oxides having a layered crystal structure, The lithium transition metal composite oxide is Li, Ni, Mn, Co, and M (M is one or more metallic elements selected from the group consisting of Mg, Ca, Al, Ti, V, Cr, Fe, Cu, Zn, Zr, Nb, Mo, Ta, and W), and The molar ratios of Li, Ni, Mn, Co, and M are Li:Ni:Mn:Co:M = a:x:y:z:t [where a, x, y, z, and t satisfy 1.0 ≤ a ≤ 1.3, x + y + z = 1, 0.25 ≤ x ≤ 0.9, 0 < y ≤ 0.6, 0 < z ≤ 0.6, and 0 < t ≤ 0.1]. The integrated intensity ratio (I 003 / I 104 ) of the diffraction peaks in the X-ray diffraction method of the secondary particles is 1.05 to 1.19, The crystallite size L 003 of the secondary particles is 1000 Å or more, a positive electrode active material. 〔2〕 The integrated intensity ratio (I 003 / I 104 ) is 1.16 or less, the positive electrode active material according to 〔1〕. 〔3〕 M contains W, the positive electrode active material according to 〔1〕 or 〔2〕. 〔4〕 The average particle diameter (D50) of the secondary particles is 3 to 20 μm, the positive electrode active material according to any one of 〔1〕 to 〔3〕. 〔5〕 The secondary particles are aggregated with 50 or more of the primary particles, the positive electrode active material according to any one of 〔1〕 to 〔4〕. 〔6〕 A positive electrode using the positive electrode active material according to any one of 〔1〕 to 〔5〕. 〔7〕 A non-aqueous electrolyte secondary battery including the positive electrode according to 〔6〕.

Advantages of the Invention

[0006] According to the positive electrode active material of the present disclosure, a non-aqueous electrolyte secondary battery excellent in the capacity retention rate in the charge-discharge cycle and capable of suppressing the decrease in the discharge capacity can be provided.

Modes for Carrying Out the Invention

[0007] In this specification, a numerical range such as "x to y" includes the upper limit value and the lower limit value unless otherwise specified. That is, "x to y" represents a numerical range of "x or more and y or less". A numerical value arbitrarily selected from within the numerical range may be used as a new upper limit value or lower limit value. For example, a new numerical range may be set by arbitrarily combining a numerical value within the numerical range with a numerical value described in another part of this specification, in a table, or in a figure, etc.

[0008] (Positive electrode active material) The positive electrode active material of this embodiment is used for the positive electrode of a non-aqueous electrolyte secondary battery such as a lithium-ion battery (hereinafter also referred to as a "secondary battery").

[0009] The positive electrode active material contains secondary particles in which primary particles are aggregated. The secondary particles are a lithium transition metal composite oxide having a layered crystal structure (hereinafter also referred to as a "composite oxide"). The composite oxide contains Li, Ni, Mn, Co, and M [M is one or more metal elements selected from the group consisting of Mg, Ca, Al, Ti, V, Cr, Fe, Cu, Zn, Zr, Nb, Mo, Ta, and W.], and the molar ratio of Li, Ni, Mn, Co, and M is Li:Ni:Mn:Co:M = a:x:y:z:t (a, x, y, z, and t are 1.0 ≦ a ≦ 1.3, x + y + z = 1, 0.25 ≦ x ≦ 0.9, 0 < y ≦ 0.6, 0 < z ≦ 0.6, and 0 < t ≦ 0.1).

[0010] That the composite oxide contains Li, Ni, Mn, and Co means that it contains a lithium element, a nickel element, a manganese element, and a cobalt element.

[0011] In the positive electrode active material, the integrated intensity ratio (I 003 / I 104 ) of the diffraction peaks in the X-ray diffraction method (hereinafter also referred to as the "XRD method") of the secondary particles is 1.05 to 1.19, and the crystallite size L 003 of the secondary particles is 1000 Å or more.

[0012] The secondary particles contained in the positive electrode active material (hereinafter also referred to as "the present secondary particles") are aggregated particles formed by aggregation of primary particles. The aggregation number of the primary particles in the present secondary particles is preferably 50 or more, may be 100 or more, or may be 1000 or more, and is usually 5 × 10 6 5 x 10 or less 5 The agglomeration number of the secondary particles can be adjusted by adjusting the production conditions, such as the firing conditions (firing temperature, number of firings, firing time, etc.) when producing the secondary particles. The agglomeration number of the primary particles contained in the secondary particles can be confirmed, for example, by a scanning electron microscope (hereinafter also referred to as "SEM") image obtained by SEM.

[0013] The secondary particles are composite oxides, and it can be confirmed that the composite oxides have a layered crystal structure, for example, by X-ray diffraction measurement. Examples of the layered crystal structure of composite oxides include a hexagonal crystal structure (layered rock salt type) and a monoclinic crystal structure. Composite oxides with a layered crystal structure can easily insert and extract lithium ions smoothly.

[0014] The metal element M contained in the composite oxide may contain one or more of the above-mentioned metal elements, but preferably contains at least W (tungsten). When the metal element M contains W, the integrated intensity ratio (I 003 / I 104 ) and crystallite size L 003 It becomes easier to obtain a composite oxide having the above structure.

[0015] The molar ratio of Li is 1.0 ≤ a ≤ 1.3, and it may also be 1.0 ≤ a ≤ 1.25, 1.01 ≤ a ≤ 1.2, 1.03 ≤ a ≤ 1.15, or 1.04 ≤ a ≤ 1.1. The molar ratio of Ni is 0.25 ≤ x ≤ 0.9, and it may also be 0.3 ≤ x ≤ 0.9, 0.4 ≤ x ≤ 0.88, or 0.5 ≤ x ≤ 0.85. The molar ratio of Mn is 0 < y ≤ 0.6, and it may also be 0.05 ≤ y ≤ 0.5, 0.08 ≤ y ≤ 0.3, or 0.10 ≤ y ≤ 0.2. The molar ratio of Co is 0 < z ≤ 0.6, and it may also be 0 < z ≤ 0.5, 0.01 ≤ z ≤ 0.3, or 0.02 ≤ z ≤ 0.1. The molar ratio of M is 0 < t ≤ 0.1, and it may also be 0 < t ≤ 0.08, 0.001 ≤ t ≤ 0.05, or 0.002 ≤ t ≤ 0.01. When the composite oxide contains two or more metal elements M, the molar ratio of M refers to the total amount of two or more metal elements.

[0016] The composition of the composite oxide can be adjusted by the types of raw materials and the blending amounts of the raw materials used in manufacturing the composite oxide. The composition of the composite oxide can be determined by inductively coupled plasma (ICP) optical emission spectrometry (ICP-AES). More specifically, it can be measured in accordance with JIS K 0116:2014 General Rules for Optical Emission Spectrometry. For example, using a high-resolution ICP optical emission spectrometer (PS3500DDII manufactured by Hitachi High-Technologies Corporation), the composite oxide is dissolved by an alkali fusion method and diluted to a predetermined amount with ultrapure water, tartaric acid, or hydrochloric acid for analysis. The measurement wavelengths of each element by ICP-AES can be set as Li: 670.784 nm, Co: 238.892 nm, Mn: 257.61 nm, and Ni: 231.604 nm.

[0017] The integrated intensity ratio (I 003 / I 104 ) of the diffraction peaks of the present secondary particles is 1.05 to 1.19, and it may also be 1.06 to 1.18, 1.08 to 1.17, or 1.10 to 1.15. The integrated intensity ratio (I 003 / I 104The integrated intensity ratio (I 003 / I 104 If the integrated intensity ratio (I 003 / I 104 ) is within the above range, the secondary particles are less likely to break. Therefore, by using the secondary particles, a secondary battery having an excellent capacity retention rate during charge-discharge cycles can be easily obtained.

[0018] Integrated intensity of diffraction peaks in XRD method for secondary particles I 003 and I 104 are the integrated intensities of the diffraction peaks on the (003) and (104) planes of the secondary particles measured by the XRD method, respectively, and can be measured by the method described in the Examples below. 003 / I 104 ) can be adjusted by, for example, the amount of lithium added (compound ratio) when producing the secondary particles, the raw material composition, and production conditions such as firing conditions (firing temperature, number of firings, firing time, etc.).

[0019] The crystallite size of the secondary particles, L 003 is 1000 Å or more, may be 1010 Å or more, may be 1020 Å or more, may be 1000 to 3000 Å, may be 1010 to 2500 Å, may be 1020 to 2000 Å, or may be 1020 to 1500 Å. 003 / I 104 If the crystallite size L of the secondary particles is within the above range, the Li site occupancy rate in the transition metal layer of the secondary particles tends to be large, and the discharge capacity of the secondary battery tends to decrease. 003 By setting the value within the above range, the Li site occupancy rate can be reduced, and therefore, a decrease in the discharge capacity of the secondary battery can be suppressed.

[0020] The crystallite size of the secondary particles, L 003The crystallite size L of the secondary particles can be calculated from the half-width of the diffraction peak of the (003) plane measured by the XRD method, and can be calculated by the method described in the examples below. 003 can be adjusted by the amount of lithium added (compound ratio), the raw material composition, and manufacturing conditions such as firing conditions (firing temperature, number of firings, firing time, etc.) when manufacturing the secondary particles.

[0021] The average particle diameter (D50) of the secondary particles is preferably 3 to 20 μm, and may be 5 to 18 μm, or 8 to 15 μm. When the average particle diameter (D50) of the secondary particles is within the above range, a secondary battery that is excellent in capacity retention rate during charge / discharge cycles and can suppress a decrease in discharge capacity is easily obtained. In this specification, the average particle diameter is the particle diameter (D50) at which the cumulative frequency from the smallest particle diameter in the volume-based particle size distribution becomes 50%. The volume-based particle size distribution can be measured using a laser diffraction particle size distribution analyzer.

[0022] The positive electrode active material may contain the present secondary particles. For example, it may contain only the present secondary particles, or it may contain particles other than the present secondary particles (hereinafter also referred to as "other particles"). The content of the present secondary particles in the positive electrode active material is, for example, 70 to 100 mass%, 85 to 98 mass%, or 90 to 95 mass%, when the total amount of the positive electrode active material is 100 mass%. The other particles that the positive electrode active material may contain may be single particles or secondary particles other than the present secondary particles (hereinafter also referred to as "other secondary particles"). The single particles may be a lithium transition metal composite oxide having a layered crystal structure, and their composition may be within the range of the composition described for the present secondary particles, or may be outside this range. The other secondary particles may be secondary particles having a composition outside the range of the composition described for the present secondary particles, and may have a composition that satisfies the above-mentioned integrated intensity ratio (I 003 / I 104 ) may be secondary particles outside the range of the crystallite size L 003 Secondary particles outside this range may also be used.

[0023] The secondary particles can be obtained, for example, by mixing a compound containing Ni, Mn, and Co (hereinafter also referred to as a "NiMnCo-containing precursor"), a lithium compound, and, if necessary, an M-containing compound containing the metal element M to obtain a mixture, and then firing this mixture. Alternatively, the secondary particles may be obtained by mixing a Ni-containing compound containing Ni, a Mn-containing compound containing Mn, a Co-containing compound containing Co, a lithium compound, and an M-containing compound containing the metal element M to obtain a mixture, and then firing this mixture. The Ni-containing compound, Mn-containing compound, and Co-containing compound may contain the metal element M.

[0024] Examples of NiMnCo precursors include composite oxides or composite hydroxides containing Ni, Mn, and Co. Examples of lithium compounds include lithium hydroxide and lithium carbonate. Examples of M-containing compounds include ammonium compounds containing the metal element M.

[0025] (positive electrode) The positive electrode of this embodiment is formed using the above-described positive electrode active material. The positive electrode of this embodiment can provide a nonaqueous electrolyte secondary battery that is excellent in capacity retention rate during charge-discharge cycles and can suppress a decrease in discharge capacity.

[0026] The positive electrode may have a positive electrode current collector foil and a positive electrode active material formed on one or both sides of the positive electrode current collector foil. The positive electrode active material is contained in a positive electrode active material layer, and the positive electrode active material layer may further contain at least one of a binder and a conductive additive. The positive electrode active material layer may be formed by adding a solvent such as N-methyl-2-pyrrolidone (NMP) to materials that form the positive electrode active material layer, such as the positive electrode active material, binder, and conductive additive, to form a positive electrode slurry, applying the slurry to the positive electrode current collector foil, drying, and compressing the slurry.

[0027] The positive electrode current collector foil is, for example, a metal foil made of an Al material such as Al or an Al alloy. Examples of binders include fluororesins such as polyvinylidene fluoride and polytetrafluoroethylene; cellulose-based resins such as carboxymethyl cellulose, methyl cellulose, and hydroxypropyl cellulose; and styrene butadiene rubber, and one or more of these can be used. Examples of conductive additives include carbon materials. Examples of carbon materials include fibrous carbon such as carbon nanotubes and carbon black, and one or more of these can be used.

[0028] (Nonaqueous electrolyte secondary battery) The nonaqueous electrolyte secondary battery of this embodiment (hereinafter also referred to as "the battery") has the above-described positive electrode. The battery can include an electrode assembly including the positive electrode and a nonaqueous electrolyte, and may have a battery case that houses the electrode assembly and the nonaqueous electrolyte. The battery case may include an exterior body having an opening and a sealing plate that seals the opening. The exterior body and the sealing plate are preferably made of metal and can be formed using aluminum, an aluminum alloy, iron, an iron alloy, or the like. A resin sheet serving as an electrode holder may be disposed between the electrode assembly and the exterior body. The battery case may also be a laminate film. The laminate film has a layered structure in which, for example, a metal layer and a resin layer are stacked. A pouch-shaped battery case can be formed by overlapping and welding the edges of the laminate film.

[0029] The electrode body may include the above-described positive electrode, negative electrode, and separator. In the electrode body, a positive electrode active material layer of the positive electrode and a negative electrode active material layer of the negative electrode face each other via the separator. The electrode body may be a laminated type in which a positive electrode, a negative electrode, and a separator are laminated, or a wound type in which a strip-shaped laminate in which a strip-shaped positive electrode, a strip-shaped negative electrode, and a strip-shaped separator are laminated is wound. The wound type electrode body may have a flat shape that is pressed after winding the laminate.

[0030] A negative electrode typically includes a negative electrode current collector foil and a negative electrode active material layer. The negative electrode current collector foil is a metal foil made of, for example, copper or a copper alloy. The negative electrode active material layer contains a negative electrode active material and may further contain a conductive additive, a binder, and the like. The negative electrode active material layer can be formed by applying a negative electrode slurry to the negative electrode current collector foil, drying, and compressing the slurry. The negative electrode active material layer contains a negative electrode active material, a binder, a conductive additive, and other materials that form the negative electrode active material layer, and may further contain a conductive additive, a binder, and other materials. The negative electrode active material layer can be formed by applying a negative electrode slurry to the negative electrode current collector foil, drying, and compressing the slurry.

[0031] Examples of the negative electrode active material include carbon-based active materials such as graphite, and metal-based active materials such as Si, SiOx, a composite of Si and C, and Sn, and one or more of these can be used. Examples of the binder include the above-mentioned cellulose-based resin, polyacrylic acid, styrene-butadiene rubber, and one or more of these can be used. Examples of the conductive additive include those mentioned above.

[0032] The separator may have a substrate and a functional layer on at least one side of the substrate. The substrate may be a film or a porous sheet such as a nonwoven fabric made of a resin such as a polyolefin (e.g., polyethylene or polypropylene), polyester, cellulose, or polyamide. The substrate may have a single-layer structure or a multilayer structure, and in the case of a multilayer structure, the materials of the layers may be the same or different. Examples of the functional layer include an adhesive layer formed with an adhesive and a heat-resistant layer containing an inorganic filler, a binder, etc.

[0033] The non-aqueous electrolyte solution is preferably a non-aqueous solvent such as an organic solvent containing an electrolyte. Examples of the electrolyte include LiPF6, LiBF4, LiClO4, LiFSO3, and LiBOB, and one or more of these can be used. Examples of the non-aqueous solvent include ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, propylene carbonate, butylene carbonate, and diethyl carbonate, and one or more of these can be used. [Example]

[0034] Hereinafter, the present disclosure will be described more specifically with reference to examples and comparative examples.

[0035] [Examples 1 to 4, Comparative Examples 1 to 6] (Production of lithium transition metal composite oxide) A mixture was obtained by mixing a NiMnCo-containing precursor containing Ni, Mn, and Co in a molar ratio of Ni:Mn:Co = 83:12:5 with lithium hydroxide monohydrate and ammonium paratungstate. The lithium hydroxide monohydrate and ammonium paratungstate were mixed so that the moles of Li and W were as shown in Table 1 per mole of the total of Ni, Mn, and Co in the NiMnCo-containing precursor (i.e., Ni: 0.83 mol, Mn: 0.12 mol, Co: 0.05 mol). The mixture was filled into an alumina crucible, and the crucible was placed in an electric furnace to fire the mixture, thereby obtaining a lithium transition metal composite oxide. The mixture was fired by first heating to 500°C at an oxygen flow rate of 4 L / min and a heating rate of 5°C / min while measuring the temperature with an alumina-coated K-type thermocouple inserted into the mixture in the crucible, and then holding at 500°C for 3 hours. After that, the mixture was heated at a heating rate of 5°C / min to the temperature Tmax shown in Table 1 and held at this temperature Tmax for 10 hours. When the lithium transition metal composite oxides were observed with a scanning electron microscope, they were all found to be secondary particles with an agglomeration number of 50 or more of primary particles.

[0036] [Table 1]

[0037] (Preparation of positive electrode) A positive electrode was fabricated using the lithium transition metal composite oxide obtained above as the positive electrode active material. The positive electrode active material, acetylene black (AB) as a conductive additive, and polyvinylidene fluoride (PVdF) as a binder were prepared in a mass ratio of positive electrode active material:AB:PVdF = 100:1:1. These were then mixed with N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode slurry. The positive electrode slurry was applied to aluminum foil as a positive electrode current collector foil, dried, compressed, and cut to the specified size to obtain a positive electrode.

[0038] (Preparation of negative electrode) A negative electrode active material was prepared as a mixture of graphite and SiO. Styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) were used as binders. The negative electrode active material, SBR, and CMC were prepared in a mass ratio of 100:1:1 (negative electrode active material:SBR:CMC), and these were mixed with water to prepare a negative electrode slurry. The negative electrode slurry was applied to copper foil as a negative electrode current collector foil, dried, compressed, and then cut to the specified size to obtain a negative electrode.

[0039] (Fabrication of non-aqueous electrolyte secondary battery) A separator with a three-layer structure of polypropylene / polyethylene / polypropylene was prepared. A positive electrode and a negative electrode were stacked with the separator interposed therebetween to obtain an electrode assembly. A positive electrode tab formed of aluminum foil in the region of the positive electrode current collector foil where the positive electrode active material layer was not formed, and a negative electrode tab formed of copper foil in the region of the negative electrode current collector foil where the negative electrode active material layer was not formed, were exposed at both ends of the electrode assembly. The positive electrode tab was welded to an aluminum plate serving as an external positive electrode current collector, and the negative electrode tab was welded to a copper plate serving as an external negative electrode current collector. The electrode assembly was then inserted into an exterior body of an aluminum laminate film, and the film was welded to form a liquid injection port. A nonaqueous electrolyte was injected through the liquid injection port, and the liquid injection port was sealed to obtain a battery.

[0040] The non-aqueous electrolyte was prepared by dissolving lithium hexafluorophosphate (LiPF) as an electrolyte at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume ratio of EC:EMC = 1:3.

[0041] [X-ray diffraction measurements of lithium transition metal composite oxides] The lithium transition metal composite oxides obtained in the examples and comparative examples were roughly crushed in an agate mortar to an average particle size (D50) of 43 μm or less, and then subjected to X-ray diffraction measurement using an X-ray diffractometer (Rigaku "SmartLab"). The XRD profile obtained by the X-ray diffraction measurement confirmed that the lithium transition metal composite oxides had a layered crystal structure.

[0042] The integrated intensity ratio (I 003 / I 104 The results are shown in Table 2.

[0043] Intensity of the diffraction peak on the (003) plane in the XRD profile I 003 The value of the half-width of the diffraction peak is used as the broadening B of the diffraction peak in the Scherrer formula below, and the crystallite size L on the (003) plane is calculated. 003 The results are shown in Table 2. L 003 =Kλ / Bcosθ [In the formula, K is the Scherrer constant, λ is the wavelength of the X-ray [nm], B is the broadening of the diffraction peak [rad], and θ is the Flag angle [rad].]

[0044] [Measurement of the average particle size (D50) of lithium transition metal composite oxide] The lithium transition metal composite oxides obtained in the examples and comparative examples were roughly crushed in an agate mortar to an average particle size (D50) of 43 μm or less, and the average particle size (D50) of the lithium transition metal composite oxides was measured in accordance with JIS Z 8825:2022 Particle size analysis - laser diffraction and scattering method. A Microtrac "MT3000II" laser diffraction particle size distribution analyzer was used. Isopropyl alcohol (IPA) was used as the solvent for wet dispersion. The results are shown in Table 2.

[0045] [Measurement of discharge capacity and calculation of capacity retention rate during charge / discharge cycles] As an activation charge treatment for the batteries obtained in the Examples and Comparative Examples, they were charged to 4.2 V at a current rate of 0.1 C. Thereafter, they were discharged to 3.0 V at 0.1 C, and the discharge capacity [mAh / g] at this time was measured. The results are shown in Table 2.

[0046] The battery was then charged to 4.2 V at a current rate of 1 C, then discharged to 3.0 V at 1 C, and then rested for 10 minutes. This cycle was repeated 10 times. The discharge capacities obtained in the first and tenth charge / discharge cycles were measured, and the capacity retention rate [%] was calculated using the following formula. The results are shown in Table 2. Capacity retention rate [%] = (10th cycle discharge capacity / 1st cycle discharge capacity) x 100

[0047] [Table 2]

Claims

1. It contains secondary particles formed by aggregation of primary particles, the secondary particles are lithium transition metal composite oxides having a layered crystal structure, The lithium transition metal composite oxide is Li, Ni, Mn, Co, and M (M is one or more metal elements selected from the group consisting of Mg, Ca, Al, Ti, V, Cr, Fe, Cu, Zn, Zr, Nb, Mo, Ta, and W), and the molar ratios of Li, Ni, Mn, Co, and M are Li:Ni:Mn:Co:M=a:x:y:z:t, where a, x, y, z, and t are 1.0≦a≦1.3, x+y+z=1, 0.25≦x≦0.9, 0<y≦0.6, 0<z≦0.6, and 0<t≦0.1; The integrated intensity ratio (I ００３ / I １０４ ) is 1.05 to 1.19, The crystallite size L of the secondary particles ００３ is 1000 Å or more.

2. The integrated intensity ratio (I ００３ / I １０４ 2. The positive electrode active material according to claim 1, wherein the σ is 1.16 or less.

3. The positive electrode active material according to claim 1 , wherein the M comprises W.

4. 2. The positive electrode active material according to claim 1, wherein the secondary particles have an average particle diameter (D50) of 3 to 20 μm.

5. The positive electrode active material according to claim 1 , wherein the secondary particles are aggregates of 50 or more of the primary particles.

6. A positive electrode using the positive electrode active material according to any one of claims 1 to 5.

7. A non-aqueous electrolyte secondary battery comprising the positive electrode according to claim 6.

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