There is provided a method for collecting and reusing an active material from positive electrode scrap. The method of reusing a positive electrode active material of the present disclosure includes (a-1) immersing a positive electrode scrap comprising an active material layer on a current collector into a basic solution to separate the active material layer from the current collector, (a-2) thermally treating the active material layer in air for thermal decomposition of a binder and a conductive material in the active material layer, and collecting an active material in the active material layer, (b) washing the active material collected from the step (a-2) with a lithium compound solution which is basic in an aqueous solution and drying, and (c) annealing the active material washed from the step (b) with a lithium precursor to obtain a reusable active material.

A positive-electrode material for a lithium ion secondary battery contains a lithium complex compound that is represented by the formula: Li.sub.1+aNi.sub.bMn.sub.cCo.sub.dTi.sub.eM.sub.fO.sub.2+α, and has an atomic ratio Ti.sup.3+/Ti.sup.4+ between Ti.sup.3+ and Ti.sup.4+, as determined through X-ray photoelectron spectroscopy, of greater than or equal to 1.5 and less than or equal to 20. In the formula, M is at least one element selected from the group consisting of Mg, Al, Zr, Mo, and Nb, and a, b, c, d, e, f, and a are numbers satisfying −0.1≤a≤0.2, 0.7<b≤0.9, 0≤c<0.3, 0≤d<0.3, 0<e≤0.25, 0≤f<0.3, b+c+d+e+f=1, and −0.2≤α≤0.2.

Provided are a cobalt-free positive electrode material for a lithium ion battery, a preparation method therefor and a lithium ion battery. The method for preparing the cobalt-free positive electrode material for the lithium ion battery comprises: mixing lithium nickel manganese oxide with sulfate, so as to obtain a first mixture; and reacting the first mixture at a predetermined temperature, so as to obtain the cobalt-free positive electrode material. The cobalt-free positive electrode material comprises lithium nickel manganese oxide and a cladding layer of an outer surface thereof, and the cladding layer comprises lithium sulphate. The lithium ion battery comprises the cobalt-free positive electrode material. The cobalt-free positive electrode material has a relatively high electrical performance and a relatively low alkali content.

Provided by the present disclosure are a carbonate precursor that has a high-nickel and low-cobalt sandwich structure, a preparation method therefor and an application thereof. The precursor comprises an inner core and an outer shell layer, wherein the outer shell layer covers at least a part of the outer surface of the inner core. The carbonate precursor having the sandwich structure has the advantages of narrow particle size distribution, good fluidity, and an excellent electrochemical performance, and may be stably produced in both an ammonia-free system and an ammonia-containing system.

A cathode active material for a lithium secondary battery according to an embodiment of the present invention includes a lithium metal oxide particle that contains tungsten and has a secondary shape in which a plurality of primary particles are aggregated. The lithium metal oxide particle includes a sulfur-containing portion formed between the primary particles in an inner region of the lithium metal oxide particle.

A layered-oxide positive electrode active material may have a molecular formula of Na.sub.xMn.sub.aFe.sub.bNi.sub.cM.sub.dN.sub.eO.sub.2-δQ.sub.f, where a doping element M is selected from at least one of Cu, Li, Ti, Zr, K, Sb, Nb, Mg, Ca, Mo, Zn, Cr, W, Bi, Sn, Ge, or Al, a doping element N is selected from at least one of Si, P, B, S, or Se, a doping element Q is selected from at least one of F, Cl, or N, 0.66≤x≤1, 0<a≤0.70, 0<b≤0.70, 0<c≤0.23, 0≤d<0.30, 0≤e≤0.30, 0≤f≤0.30, 0≤δ≤0.30, a+b+c+d+e=1, 0<e+f≤0.30, 0<(e+f)/a≤0.30, 0.20≤d+e+f≤0.30, and (b+c)/a≤1.5.

The present invention provides a method of preparing an MOF-coated monocrystal ternary positive electrode material. Firstly, a solution A of nickel, cobalt and manganese metal salts, an ammonia complexing agent solution and a caustic soda liquid are added to a reactor for reaction to obtain a precursor core; then, an organic carboxylate is dissolved in an amount of an organic solvent to obtain a solution B; the solution B and a manganese metal salt solution with a given concentration are added to the reactor and aged to obtain an MOF-coated core-shell structure precursor; the core-shell structure precursor is pre-sintered at a low temperature to obtain a nickel-cobalt-manganese oxide with monocrystal structure; the nickel-cobalt-manganese oxide with monocrystal structure is uniformly mixed with LiOH.Math.H.sub.2O in a mortar and then calcined at a high temperature to obtain an MOF-coated monocrystal ternary positive electrode material.

A method includes sintering a lithium-rich metal oxide (LRMO) material at a sintering temperature to form a sintered LRMO material and quenching the sintered LRMO material from the sintering temperature to room temperature in less than 500 milliseconds to form a quenched LRMO material represented by a chemical formula Li.sub.x(Mn.sub.yNi.sub.1-y).sub.2-xO.sub.2, where x is greater than 1.05 and less than 1.25, and y ranges from 0.95 to 0.1.

The positive electrode active material with lithium composite oxide A containing W and Ni and W-free lithium composite oxide B containing Ni. Regarding the lithium composite oxide A, the proportion of Ni relative to the total moles of metal elements except for lithium is 30 to 60 mol %, 50% particle size D50 is 2 to 6 μm, 10% particle size D10 is 1.0 μm or more, and 90% particle size D90 is 6.8 μm or less. Regarding the lithium composite oxide B, the proportion of Ni relative to the total moles of metal elements except for lithium is 50 to 95 mol %, 50% particle size D50 is 10 to 22 μm, 10% particle size D10 is 7.0 μm or more, and 90% particle size D90 is 22.5 μm or less. The mass ratio of the lithium composite oxide B to the lithium composite oxide A is 1:1 to 5.7:1.

The cathode active material is capable of reducing cathode resistance of a secondary battery by enhancing electron conductivity thereof without reducing discharge capacity of the secondary battery. The method for manufacturing a cathode active material includes: mixing transition metal-containing composite compound particles containing lanthanum with a lithium compound to obtain a lithium mixture; calcinating the lithium mixture at a temperature equal to or lower than the melting point of the lithium compound; and then subjecting the lithium mixture to main firing at a firing temperature within a range of 725° C. to 1000° C. Lithium carbonate is preferably used as the lithium compound, and in this case, the calcination temperature is within a range of 600° C. to 723° C. It is preferable to obtain the transition metal-containing composite compound particles containing lanthanum by a coprecipitation method and to uniformly disperse a lanthanum element in the particles.