The cathode active material for a lithium secondary battery according to embodiments of the present invention includes a lithium-transition metal composite oxide particle including a plurality of primary particles, and the lithium-transition metal composite oxide particle includes a lithium-sulfur-containing portion formed between the primary particles. Thereby, it is possible to improve life-span properties and capacity properties by preventing the layer structure deformation of the primary particles and removing residual lithium.

Cathode material from exhausted lithium ion batteries are dissolved in a solution for extracting the useful elements Co (cobalt), Ni (nickel), Al (Aluminum) and Mn (manganese) to produce active cathode materials for new batteries. The solution includes compounds of desirable materials such as cobalt, nickel, aluminum and manganese dissolved as compounds from the exhausted cathode material of spent cells. Depending on a desired proportion, or ratio, of the desired materials, raw materials are added to the solution to achieve the desired ratio of the commingled compounds for the recycled cathode material for new cells. The desired materials precipitate out of solution without extensive heating or separation of the desired materials into individual compounds or elements. The resulting active cathode material has the predetermined ratio for use in new cells, and avoids high heat typically required to separate the useful elements because the desired materials remain commingled in solution.

A positive electrode active material for a lithium secondary battery, including secondary particles formed by aggregation of primary particles capable of being doped and undoped with lithium ions, said positive electrode active material having: an α-NaFeO.sub.2 type crystal structure represented by formula: Li[Li.sub.x(Ni.sub.aCo.sub.bMn.sub.cM.sub.d).sub.1-x]O.sub.2 (I), wherein 0≦x≦0.1, 0.7<a<1, 0<b<0.2, 0≦c<0.2, 0<d<0.1, a+b+c+d=1, and M is at least one metal element selected from the group consisting of Fe, Cr, Ti, Mg, Al, Zr, Ca, Sc, V, Cr, Cu, Zn, Ga, Ge, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In and Sn; and a crystallite size α/crystallite size β ratio (α/β) of 1.60 to 2.40, wherein the crystallite size α is within a peak region of 2θ=18.7±1° and the crystallite size β is within a peak region of 2θ=44.4±1°, each determined by a powder X-ray diffraction measurement using Cu-Kα radiation.

A composite cathode active material, includes a first metal oxide having a first layered crystal structure; and a second metal oxide having a second layered crystal structure, wherein the second metal oxide includes a layered double oxide (LDO). Also a cathode and a lithium battery including the composite cathode active material.

Provided are electrochemically active secondary particles that provide excellent capacity and improved cycle life. The particles are characterized by a plurality of nanocrystals with small average crystallite size. The reduced crystallite size reduces impedance generation during cycling thereby improving capacity and cycle life. Also provided are methods of forming electrochemically active materials, as well as electrodes and electrochemical cells employing the secondary particles.

A lithium-cobalt-based composite oxide used for a positive electrode active material of an electrochemical device, wherein the lithium-cobalt-based composite oxide has elutable fluoride ions, the elutable fluoride ions being eluted to an eluate when the lithium-cobalt-based composite oxide is dispersed to ultrapure water, in a mass ratio of 500 ppm or more and 15000 ppm or less in comparison with the lithium-cobalt-based composite oxide, and the lithium-cobalt-based composite oxide has a composition shown by the following general formula (1): Li.sub.1-xCo.sub.1-zM.sub.zO.sub.2-aF.sub.a (−0.1≦x<1, 0≦z<1, 0≦a<2) . . . (1) (wherein, M represents one or more kinds of metal element selected from the group of Mn, Ni, Fe, V, Cr, Al, Nb, Ti, Cu, and Zn).

Provided is a method for producing a positive electrode active material for nonaqueous electrolyte secondary batteries, including: a water-washing step of mixing, with water, Li—Ni composite oxide particles represented by the formula: Li.sub.zNi.sub.1-x-yCo.sub.xM.sub.yO.sub.2 and composed of primary particles and secondary particles formed by aggregation of the primary particles to water-wash it, and performing solid-liquid separation to obtain a washed cake; a mixing step of mixing a W compound powder free from Li with the washed cake to obtain a W-containing mixture; and a heat treatment step of heating the W-containing mixture, the heat treatment step including: a first heat treatment step of heating the W-containing mixture to disperse W on the surface of the primary particles; and subsequently, a second heat treatment step of heating it at a higher temperature than in the first heat treatment step to form a lithium tungstate compound on the surface of the primary particles.

A method for fabricating a composite material includes forming an emulsion mixture of active material particles and graphene emulsion droplets containing immiscible first and second solvents and a solid-state emulsifier of graphene, wherein the first and second solvents are adapted such that the second solvent resides in an interior of the graphene emulsion droplets with the first solvent as an exterior solvent, and the active material particles reside in the interior of the emulsion droplets; wherein a boiling point of the second solvent is lower than that of the first solvent; and drying the emulsion mixture with subsequent evaporation of the second solvent and the first solvent through fractional distillation to form the composite material having each surface of the active material particles conformally coated with said graphene.

This positive electrode material comprises a lithium transition metal complex oxide which contains at least 80 mol % Ni in terms of the total mol number of metal elements excluding Li, and which has a total Co content of less than 5 mol %. The lithium transition metal complex oxide is formed as secondary particles obtained by aggregating primary particles, wherein at least one element A selected from Ca and Sr is present on the surface of the primary particles in the amount of 0.01-1 mol %, inclusive, in terms of the total mol number of the metal elements excluding Li. In addition, at least one element B selected from B, Zr, W, Al, Nb, Mo, and Ti is present on the surface of the secondary particles in the amount of 0.05-2 mol %, inclusive, in terms of the total mol number of the Ni in the complex oxide.

A positive electrode active material for a lithium ion secondary battery including a coating layer, wherein, a substance quantity ratio is represented by Li:Ni:Co:M=t:1−x−y:x:y (wherein, M is at least one element selected from Mg and else, 0.95≤t≤1.20, 0<x≤0.22, and 0≤y≤0.15), the coating layer includes a lithium zirconium compound, and a ratio of a sum of substance quantities of Ni, Co, Zr and a substance quantity of Zr existing on a surface of the positive electrode active material is 0.80 or more and 0.97 or less.