SECONDARY BATTERY POSITIVE ELECTRODE ACTIVE MATERIAL, AND SECONDARY BATTERY

This lithium transition metal composite oxide, which configures a secondary battery positive electrode active material, is a composite oxide represented by general formula Liα[LixMnyCozMe(1-x-y-z)]O2 (in the formula, Me is at least one species selected from Ni, Fe, Ti, Bi and Nb, and 0.5 < α < 1, 0.05 < x < 0.25, 0.4 < y < 0.7, and 0 < z < 0.25), and has at least one crystal structure selected from the O2 structure, the T2 structure and the O6 structure. The ratio (Co2/Co1) of the Co molar fraction (Co2) in the surface of the oxide to the Co molar fraction (Co1) in the entire lithium transition metal composite oxide is 1.2 < (Co2/Co1) < 6.0.