Nonaqueous electrolyte secondary battery

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, said secondary battery being characterized in that said positive active material consists of a mixture of a lithium transition metal complex oxide A obtained by incorporating at least Zr and Mg into LiCoO2 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.

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, said secondary battery being characterized in that said positive active material consists of a mixture of a lithium transition metal complex oxide A obtained by incorporating at least Zr and Mg into LiCoO2 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 compound contained in said lithium transition metal complex oxide A existing in the form of particles adhered onto said 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.