Patent ID: 8227113

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 M b ]O 2-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 element selected from the group consisting of Mg, Al, Zr, Ti, Nb, W and Mo; and the variables x, y, z, and b satisfy the expressions x>(1−2y)/3, 1/4≦y/z≦1.0, 0<b/(y+z)≦0.1, and 1.0≦x+y+z+b≦1.1.