Patent ID: 7858237

Claim:
A nonaqueous electrolyte secondary battery which has a positive electrode containing a positive active material, a negative electrode containing a negative active material and a nonaqueous electrolyte comprising a mixed solvent of a cyclic carbonate and a chain carbonate, said secondary battery being characterized in that said positive active material comprises a mixture of a lithium transition metal complex oxide A obtained by incorporating at least Zr and Mg into LiCoO 2 and a lithium transition metal complex oxide B having a layered structure and containing at least Ni and Mn as the transition metal, the Zr contained in said lithium transition metal complex oxide A existing in the form of a compound adhered onto a surface of the lithium transition metal complex oxide A with at least 80% of the surface of said lithium transition metal complex oxide A being left exposed without being covered with said Zr compound.