Non-aqueous electrolyte secondary battery

Abstract

A non-aqueous electrolyte secondary battery has a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, and a non-aqueous electrolyte. The positive electrode active material includes a lithium-nickel-manganese composite oxide having a hexagonal layered rock-salt structure that belongs to the space group R-3m, and contains lithium in 3b sites that contain transition metals. The lithium-nickel-manganese composite oxide is represented by the molecular formula Li[LixNiyMnzMb]O2−a where: 0<x<0.4, 0.12<y<0.5, 0.3<z<0.62, and 0≦a<0.5; M is at least one metal element having a valency of from 2 to 6; and the variables x, y, z, and b satisfy the expressions x>(1−2y)/3, ¼≦y/z≦1.0, 0<b/(y+z)≦0.1, and 1.0≦x+y+z+b≦1.1.

Dependencies are inferred from the claim text.