POSITIVE ELECTRODE ACTIVE MATERIAL, POSITIVE ELECTRODE FOR ELECTRIC DEVICE, AND ELECTRIC DEVICE

[Summary] A positive electrode active material is provided to contain: a solid solution lithium-containing transition metal oxide (A) represented by Li[NiaCoMn[Li]]O(where a, b, c and d satisfy the relations of 0.1≤d≤0.4, a+b+c+d=1.5, and 1.1≤a+b+c≤1.4.); and a lithium-containing transition metal oxide (B) represented by LiNiMn