POSITIVE ELECTRODE ACTIVE MATERIAL, METHOD FOR PRODUCING SAME AND NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

A positive electrode active material includes, as a main phase, an O2-type layered structure attributable to space group P6mc, and has a composition represented by a composition formula LiNaMnMO (in the composition formula, M represents one or more additive elements selected from the group consisting of Ni, Al, Ti, Sn, Zr, Nb, W, and Mo, the additive elements including at least Ni, and a to d and α satisfy 0.7 ≤ a ≤ 1.33, 0 < b < 0.1, 0.7 < c < 0.9, 0.9 < c + d