Patent ID: 7056622

Claim:
A nonaqueous electrolyte secondary battery comprising a positive electrode containing a positive electrode active material capable of intercalating and deintercalating lithium ions, a negative electrode containing a negative electrode active material capable of intercalating and deintercalating lithium ions, a separator between the positive electrode from and the negative electrode, and a nonaqueous electrolyte, wherein the positive electrode active material comprises lithium containing composite oxide having a layer crystal structure represented by a general formula Li x Mn a Co b M c O 2 where 0.9≦x≦1.1, 0.45≦a≦0.55, 045≦b≦0.55, 0<c≦0.05 and 0.9<a+b+c≦1.1 and M is at least one element selected from Mg, Sn, Ti and Zr.