Patent ID: 7179565

Claim:
A lithium ion secondary battery comprising: a positive electrode; a negative electrode; and a non-aqueous electrolyte, said positive electrode comprising a positive electrode active material and a binder, said positive electrode active material comprising a lithium-containing composite oxide represented by the chemical formula: Li a (Co 1-x-y Mg x M y ) b O c wherein M is at least one selected from Ni, Mn and Al, 0<a≦105, 0.005≦x≦0.025, 0≦y≦0.25, 0.85≦b≦1.1, and 1.8≦c≦2.1, and said positive electrode comprises not more than 3 parts by weight of a conductive agent per 100 parts by weight of said positive electrode active material, wherein said negative electrode comprises a carbon particle, said carbon particle comprises a core particle and an amorphous carbon which covers at least part of the surface of said core particle, and said core particle comprises graphite.