Patent ID: 8728344

Claim:
An electrode active material comprising: a lithium-nickel-manganese-cobalt composite oxide having a hexagonal, layered rock-salt type crystal structure that belongs to the space group R3m, the lithium-nickel-manganese-cobalt composite oxide being represented by Li 1+α [Ni x Mn y Co z ]O 2 wherein α satisfies 0.1<α<0.3, and x, y, and z satisfy x+y+z=1, 0.075<z<0.250, and 0.50<x/y<0.90, and wherein, in a powder X-ray diffraction analysis of a powder of the lithium-nickel-manganese-cobalt composite oxide using a CuKα ray, a peak intensity ratio (A/B) of a diffraction peak intensity (A) observed near 2θ=18.6±0.2° to a diffraction peak intensity (B) observed near 2θ=44.3±1.0° is more than 0 and less than 1.0.