The method includes a delithiation step of deintercalating a part of lithium of a Li-rich metal oxide represented by [Formula 1] below and having a layered structure, and a heat-treatment step of heat-treating the delithiated Li-rich metal oxide, thereby allowing dispersion to be achieved through diffusion of M′ and/or M elements constituting the Li-rich metal oxide:

a{Li.sub.2M′O.sub.3}.Math.(1−a){LiMO.sub.2} or Li.sub.1+x(M′M).sub.1−xO.sub.2  [Formula 1]

(wherein 0<a<1.0, M′ and M are one or more selected from 3d, 4d, 5d transition metals or non-transition metals including Al, Mg, Mn, Ni, Co, Cr, V and Fe, and satisfy electrical neutrality according to the type and oxidation number of M′ and M and an amount of lithium in a layered structure of a material.

A cathode active material precursor for a lithium secondary battery is provided according to embodiments of the present invention. The cathode active material precursor for a lithium secondary battery includes a core including a first transition metal composite hydroxide, and a shell which is formed on the core and includes a second transition metal composite hydroxide in which the first transition metal composite hydroxide is doped with a doping metal including at least one of Group 4 to Group 12 metals, wherein the cathode active material precursor has a particle size distribution degree of 0.8 to 1.6 defined by Equation 1. Thereby, it is possible to suppress capacity degradation of the secondary battery due to doping while improving the structural stability of the cathode active material precursor.

The present invention relates to a positive electrode active material, wherein the positive electrode active material is a lithium transition metal oxide including a first doping element (A) and a second doping element (B), wherein the first doping element is one or more selected from the group consisting of Zr, La, Ce, Nb, Gd, Y, Sc, Ge, Ba, Sn, Sr, Cr, Mg, Sb, Bi, Zn, and Yb, the second doping element is one or more selected from the group consisting of Al, Ta, Mn, Se, Be, As, Mo, V, W, Si, and Co, and a weight ratio (A/B ratio) of the first doping element to the second doping element is 0.5 to 5.

In one embodiment, the present disclosure relates to a method of preparing a positive electrode active material, which includes mixing a nickel cobalt manganese hydroxide precursor containing nickel in an amount of 60 mol % or more based on a total number of moles of transition metals in the precursor, a lithium-containing raw material, and a doping raw material represented by Formula 2 (set forth herein), and sintering the mixture to prepare a positive electrode active material represented by Formula 1 (set forth herein).

The present invention relates to a lithium metal composite oxide with a layered structure wherein: at least Li, Ni, and an element X are included; the element X is at least one element selected from the group consisting of Co, Mn, Mg, Ca, Sr, Ba, Zn, B, Al, Ga, Ti, Zr, Ge, Fe, Cu, Cr, V, W, Mo, Sc, Y, Nb, La, Ta, Tc, Ru, Rh, Pd, Ag, Cd, In, and Sn; and an average three-dimensional particle unevenness of primary particles with an equivalent spherical diameter of at least 1.0 μm is at least 1.91 and less than 2.9.

The present disclosure provides: a method for preparing a cathode active material precursor material by using a high-nickel-content waste lithium secondary battery; a method for preparing a cathode active material for a lithium secondary battery, including a cathode active material precursor material prepared by the method for preparing a cathode active material precursor material; and a cathode active material for a lithium secondary battery, prepared according to the method for preparing a cathode active material for a lithium secondary battery.

Process for making a particulate lithiated transition metal oxide comprising the steps of: (a) Providing a particulate transition metal precursor comprising Ni, (b) mixing said precursor with at least one compound of lithium and at least one processing additive selected from NaCl, KCl, CuCl.sub.2, B.sub.2O.sub.3, MoO.sub.3, Bi.sub.2O.sub.3, Na.sub.2SO.sub.4, and K.sub.2SO.sub.4 in an amount of from 0.1 to 5% by weight, referring to the entire mixture obtained in step (b), (c) thermally treating the mixture obtained according to step (b) in at least two steps, (c1) at 300 to 500° C. under an atmosphere that may comprise oxygen, (c2) at 650 to 850° C. under an atmosphere of oxygen.

Particulate electrode active material with an average particle diameter in the range of from 2 to 20 μm (D50) having a general formula Li.sub.1+xTM.sub.1−xO.sub.2 wherein TM is a combination of Ni, Co and Al, and, optionally, at least one more metal selected from Mg, Ti, Zr, Nb, Ta, Mo, Mn, and W, with at least 80 mole-% of TM being Ni, and wherein x is in the range of from zero to 0.2, wherein the Co content at the outer surface of the secondary particles is higher than at the center of the secondary particles by a factor of at most 5 or by at most 30 mol-%, referring to TM.

A method of forming an active material for a positive electrode of a lithium-ion battery includes quenching a powder of the active material in water. The active material may include layered lithium rich nickel manganese oxide.

A cathode active material for a lithium secondary battery includes a lithium-transition metal composite oxide particle having a lattice strain (η) of 0.18 or less, which is calculated by applying Williamson-Hall method defined by Equation 1 to XRD peaks measured through XRD analysis, and having an XRD peak intensity ratio of 8.9% or less, which is defined by Equation 2. By controlling the lattice strain and XRD peak intensity ratio of the lithium-transition metal composite oxide particle, a lithium secondary battery with improved life-span characteristics as well as output characteristics is provided.