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

[Summary] A positive electrode active material is provided to contain: a solid solution lithium-containing transition metal oxide (A) represented by Li 1.5 [Ni a Co b Mn c [Li] d ]O 3 (where a, b, c and d satisfy the relations of 0.2‰¤a‰¤0.7, 0.1‰¤d‰¤0.4, a+b+c+d=1.5, 1.15a+b+c‰¤1.35, and 0