Provided is a method of preparing an irreversible positive electrode additive for a secondary battery, which includes mixing Li.sub.2O, NiO, and NH.sub.4VO.sub.3 and performing thermal treatment to prepare a lithium nickel composite oxide represented by Chemical Formula 1 below, wherein the NH.sub.4VO.sub.3 is mixed in an amount of 1.5 to 6.5 parts by weight with respect to a total of 100 parts by weight of the Li.sub.2O, NiO, and NH.sub.4VO.sub.3.

Li.sub.2+aNi.sub.1−b−cM.sup.1.sub.bV.sub.cO.sub.2−dA.sub.d  [Chemical Formula 1]

In Chemical Formula 1,

M.sup.1 is at least one selected from the group consisting of Cu, Mg, Pt, Al, Co, P, W, Zr, Nb, and B, A is at least one selected from the group consisting of F, S, Cl, and Br, and 0≤a≤0.2, 0≤b≤0.5, 0.01≤c≤0.065, and 0≤d≤0.2 are satisfied.

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer includes a lithium-nickel composite oxide of a layered rock-salt type.

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer includes a lithium-nickel composite oxide of a layered rock-salt type.

The present invention discloses a quaternary cathode material, an cathode and a battery. Particularly, the present invention provides the quaternary cathode material with a chemical structural formula: Li.sub.xNi.sub.a′Co.sub.bMn.sub.c′Al.sub.dM.sub.yO.sub.2, wherein 1x1.05,0<y0.025.0.3a′0.95,0.03b01.0.01c′0.05,0.01d0.005 and a′+b+c′+d=1; M is a dopant selecting from at least one of Zr, Al, B, Ti, Mg, Nb, Ba, Si, P, W, Sr and F. The quaternary cathode material has an α-NaFeO.sub.2 ty

A positive electrode active material to be used in a non-aqueous electrolyte secondary battery and containing a lithium transition metal compound which contains Ni in a proportion constituting 80-94 mol %, inclusive, relative to the total mole number of the metal elements other than Li, and also contains Nb in a proportion constituting 0.1-0.6 mol %, inclusive, relative thereto, the positive electrode active material being characterized in that the Nb amount n1 in a first sample solution obtained by adding 0.2 g of the lithium transition metal compound to a hydrochloric acid aqueous solution comprising 5 mL of pure water/5 mL of 35% hydrochloric acid, and the Nb amount n2 in a second sample solution obtained by immersing a filter used to filter the first sample solution in a fluonitric acid comprising 5 mL of 46% hydrofluoric acid/5 mL of 63% nitric acid satisfy the condition of 50%≤n1/(n1+n2)<75% when converted to molar quantities.

A composite metal oxide material and a preparation method thereof, a positive electrode plate, a secondary battery, a battery module, a battery pack and an electrical device are provided. The composite metal oxide material includes a central core and a coating layer on the surface of the central core, in which the central core material has a chemical formula of Li.sub.5Fe.sub.xM.sub.1-xO.sub.4, 0.6≤x≤1; the coating layer material has a chemical formula of LiMO2, M is one or more metal elements with +3 valence, and the absolute value of the difference between the +3-valence ion radius of Fe and the +3-valence ion radius of M is ≤0.02 nm. The composite metal oxide material of the present disclosure makes the secondary battery have high charge capacity, high discharge capacity and long cycle life.

A positive electrode active material includes a lithium transition metal oxide having a spinel crystal structure, and a coating layer positioned on the surface of the lithium transition metal oxide, wherein the coating layer has an orthorhombic structure, and includes an oxide represented by Formula 1. A method for producing the positive electrode active material, a positive electrode including the positive electrode active material, and a lithium secondary battery, the positive electrode active material.

A layered double hydroxide is represented by the following formula (I): Ni.sup.2+.sub.1−(x+y+z)Fe.sup.3+.sub.xV.sup.3+.sub.yCo.sup.3+.sub.z(OH).sub.2A.sup.n−.sub.(x+y+z)/n.Math.mH.sub.2O . . . (I). In one embodiment, in the formula (I), (x+y+z) is from 0.2 to 0.5, “x” represents more than 0 and 0.3 or less, “y” represents from 0.04 to 0.49, and “z” represents more than 0 and 0.2 or less.

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.

A positive electrode active material for a non-aqueous electrolyte secondary battery according to an embodiment of the present disclosure is represented by a general formula of Li.sub.xNi.sub.yM.sub.1-yO.sub.2 (where M includes at least one metal element selected from Co and Mn, 0.1≤x≤1.2, 0.3<y<1), has a volumetric average particle size (D50) of 7 μm or more and 30 μm or less, and has an average surface roughness of 4%, or less.