| abstract |
A positive electrode active material which is characterized by substantially consisting of a lithium-nickel-cobalt-manganese composite oxide, wherein the molar content ratio (Ni III /Ni II ) of a bivalent nickel atom (Ni II ) to a trivalent nickel atom (Ni III ) in the nickel atoms constituting the composite oxide is 0.15 to 0.95 inclusive (i.e., 0.15≤(Ni III /Ni II )≤0.95). |