Positive electrode active material for secondary battery, and secondary battery

A positive electrode active material for secondary battery, comprising:

• a first composite oxide component represented by general formula Liα[LixMnyCozMe(1−x−y−z)]O2 where Me is at least one selected from Ni, Fe, Ti, Bi, Nb, W, Mo, and Ta, and 0.5<α<0.85, 0.05<x<0.2, 0.4<y<0.75, 0<z<0.25, and 1−x−y−z≥0 hold true, and having at least one crystal structure selected from O2 structure, T2 structure, and O6 structure;
• and
• a second composite oxide component represented by general formula LiaMObAc where M is at least one selected from Ni, Co, Mn, Fe, Cu, Ti, Nb, Al, Ga, Bi, Zr, Ce, Y, W, Ta, Sn, Ca, Ba, and Na;
• A includes at least one selected from F and Cl;
• and 1.3<a<7, 2>b<5, and 0<c>0.3 hold true,
• wherein the positive electrode active material includes a composite of the first composite oxide component and the second composite oxide component,
• the composite contains, within a single composite particle, a region having the first composite oxide component and a region having a second composite oxide composition.