Provided is a positive electrode active material for a nonaqueous electrolyte secondary battery including a LiNi composite oxide having low internal resistance and excellent thermal stability. The positive electrode active material is obtained by performing a water washing process using a water spray on a LiNi composite oxide powder obtained by a firing step until the filtrate has an electric conductivity of 30 to 60 mS/cm, and then dried, where the LiNi composite oxide is represented by the composition formula (1): Li.sub.bNi.sub.1-aM1.sub.aO.sub.2, where M1 represents at least one kind of element selected from transition metal elements other than Ni, group 2 elements, and group 13 elements, and 0.01≤a≤0.5, and 0.85≤b≤1.05.

The present invention relates to a lithium composite metal oxide which satisfies the requirements (1) and (2) described below. Requirement (1): The ratio of the half width A of the diffraction peak within the range of 2θ=64.5±1° to the half width B of the diffraction peak within the range of 2θ=44.4±1°, namely A/B is from 1.39 to 1.75 (inclusive) in powder X-ray diffractometry using a Cu-Kα ray. Requirement (2): The ratio of the volume-based 90% cumulative particle size (D.sub.90) to the volume-based 10% cumulative particle size (D.sub.10), namely D.sub.90/D.sub.10 is 3 or more.

A lithium metal complex oxide powder satisfies requirements (1) to (3): Requirement (1): Composition Formula (I) is satisfied, Li[Li.sub.x(Ni.sub.(1−y−z−w)Co.sub.yMn.sub.zM.sub.w).sub.1−x]O.sub.2 . . . (I) (where M is one or more elements selected from the group consisting of Fe, Cu, Ti, Mg, Al, W, B, Mo, Nb, Zn, Sn, Zr, Ga, La, and V, and −0.1≤x≤0.2, 0≤y≤0.4, 0≤z≤0.4, and 0≤w≤0.1 are satisfied). Requirement (2): an average primary particle diameter is 1 μm or more and 7 μm or less. Requirement (3): R1/Ra, which is a ratio of the average primary particle diameter represented by R1 to an average crystallite diameter represented by Ra, is more than 5.0 and 20 or less.

A carbonate precursor compound for manufacturing a lithium metal (M)-oxide powder usable as an active positive electrode material in lithium-ion batteries, M comprising 20 to 90 mol % Ni, 10 to 70 mol % Mn and 10 to 40 mol % Co, the precursor further comprising a sodium and sulfur impurity, wherein the sodium to sulfur molar ratio (Na/S) is 0.4<Na/S<2. Theslithium metal (M)-oxide powder has a particle size distribution with 10 μm≦D50≦20 μm, a specific surface with 0.9≦BET≦5, the BET being expressed in g/cm2, the powder further comprises a sodium and sulfur impurity, wherein the sum (2* Nawt)+Swt of the sodium (Nawt) and sulfur (S wt) content expressed in wt % is more than 0.4 wt % and less than 1.6 wt %, and wherein the sodium to sulfur molar ratio (Na/S) is 0.4<Na/S<2.

This disclosure relates to the electrochemical field, and in particular, to a positive electrode material and a preparation method and usage thereof. The positive electrode material of this disclosure includes a substrate, where a general formula of the substrate is Li.sub.xNi.sub.yCo.sub.zM.sub.kMe.sub.pO.sub.rA.sub.m, where 0.95≤x≤1.05, 0.5≤y≤1, 0≤z≤1, 0≤k≤1, 0≤p≤0.1, 1≤r≤5.2, 0≤m≤2, m+r≤2, M is selected from one or more of Mn and Al, Me is selected from one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, and Nb, and A is selected from one or more of N, F, S, and Cl; and an oxygen defect level of the positive electrode material satisfies at least one of condition (1) or condition (2): (1) 1.77≤OD1≤1.90; or (2) 0.69≤OD2≤0.74.

A method for producing a M-carbonate precursor of a Li-M oxide cathode material in a continuous reactor, wherein M=NixMnyCozAn, A being a dopant, with x>0, y>0, 0≦z≦0.35, 0≦n≦0.02 and x+y+z+n=1, the method comprising the steps of: —providing a feed solution comprising Ni-, Mn-, Co- and A-ions, and having a molar metal content M″ feed, —providing an ionic solution comprising either one or both of a carbonate and a bicarbonate solution, the ionic solution further comprising either one or both of Na- and K-ions, —providing a slurry comprising seeds comprising M′-ions and having a molar metal content M′ seeds, wherein M′=Nix′Mny′Coz′A′n′, A′ being a dopant, with 0≦x′≦1, 0≦y′≦1, 0≦z′≦1, 0≦n′≦1 and x′+y′+z′+n′=1, and wherein the molar ratio M′ seeds/M″ feed is between 0.001 and 0.1, —mixing the feed solution, the ionic solution and the slurry in the reactor, thereby obtaining a reactive liquid mixture, —precipitating a carbonate onto the seeds in the reactive liquid mixture, thereby obtaining a reacted liquid mixture and the M-carbonate precursor, and —separating the M-carbonate precursor from the reacted liquid mixture.

A nickel composite hydroxide containing reduced amounts of sulfate radicals and chlorine as impurities. The nickel composite hydroxide is represented by Ni.sub.1-x-yCo.sub.xAl.sub.y(OH).sub.2+α(0.05≦x≦0.01≦y≦0.2, x+y<0.4, and 0≦α<0.5), and includes spherical secondary particles formed by aggregation of plurality of plate-shaped primary particles, secondary particles have an average particle diameter of 3-20 μm, sulfate radical content of 1.0 mass % or less, chlorine content of 0.5 mass % or less, and carbonate radical content of 1.0-2.5 mass %. The nickel composite hydroxide is obtained by a process including a crystallization step in which crystallization is performed in reaction solution obtained by adding alkali solution to aqueous solution containing mixed aqueous solution containing nickel and cobalt, ammonium ion supplier, and aluminum source. The alkali solution is mixed aqueous solution of alkali metal hydroxide and carbonate, and ratio of carbonate to alkali metal hydroxide in mixed aqueous solution represented by [C0.sub.3.sup.2−]/[OH.sup.−]=0.002 or more but 0.050 or less.

A cathode active material precursor according to embodiments of the present invention includes a composite hydroxide particle in which primary precursor particles are aggregated. The primary precursor particles include a particle having a triangular shape in which a minimum interior angle is 300 or more and a ratio of a length of a short side relative to a length of a long side is 0.5 or more. A cathode active material and a lithium secondary having improved high temperature stability is provided using the cathode active material precursor.

Spherical particles comprising (A) at least one mixed transition metal hydroxide or mixed transition metal carbonate of at least 3 different transition metals selected from nickel, cobalt, manganese, iron, chromium and vanadium, (B) at least one fluoride, oxide or hydroxide of Ba, Al, Zr or Ti,
where the transition metals in transition metal hydroxide (A) or transition metal carbonate (A) are predominantly in the +2 oxidation state,
where fluoride (B) or oxide (B) or hydroxide (B) is present to an extent of at least 75% in an outer shell of the spherical particles in the form of domains and is encased to an extent of at least 90% by transition metal hydroxide (A) or transition metal carbonate (A).

Provided herein is a precursor of a transition metal oxide, including a core unit and a shell unit, wherein the core unit includes a compound of chemical formula 1 below, and the shell unit includes a compound of chemical formula 2 below.

Ni.sub.aMn.sub.bCo.sub.1−(a+b+c)M.sub.c[OH.sub.(1−x)2−y]A.sub.(y/n)   [Chemical formula 1]

Ni.sub.a′Mn.sub.b′Co.sub.1−(a′+b′+c′)M′.sub.c′[OH.sub.(1−x′)2−y′]A.sub.(y′/n)   [Chemical formula 2]