Patent ID: 7955734

Claim:
A non-aqueous electrolyte secondary battery comprising: a positive electrode containing a positive electrode active material; a negative electrode containing a negative electrode active material; and a non-aqueous electrolyte, wherein the positive electrode active material comprises a lithium-nickel-manganese composite oxide having a hexagonal layered rock-salt structure that belongs to the space group R-3m and containing lithium in 3b sites that contain transition metals, the lithium-nickel-manganese composite oxide being represented by the molecular formula Li[Li x Ni y Mn z ]O 2-a where: 0.2<x<0.4, 0.12<y<0.5, 0.3<z<0.62, 0≦a<0.5; and the variables x, y, and z satisfy the expressions x>(1−2y)/3, ¼≦y/z≦1.0, and x+y+=1.0.