Patent ID: 7214449

Claim:
A cathode active material comprising a mixture of: a first cathode active material having a formula: Li t CoM s O 2 , where M represents a metal, 0≦s≦0.03, and 0.05≦t≦1.15; and a second cathode active material having a formula: Li x Ni (l-y-z) Co y Mn z A a O 2 , where A represents a metal, 0.05≦x≦1.15, 0.15≦y+z≦0.70, 0.05≦z≦0.40, and 0≦a≦0.10; and where the second cathode material is composed of secondary particles formed from an aggregate of primary particles; and wherein the content of the second cathode active material in the cathode active material ranges from about 10% to about 40% by weight.