Patent ID: 7670722

Claim:
A cathode active material for a lithium secondary battery, consisting of a mixture of a lithium/manganese spinel oxide represented by Formula I and a lithium/nickel/cobalt/manganese composite oxide represented by Formula II, wherein the lithium/manganese spinel oxide of Formula I and the lithium/nickel/cobalt/manganese composite oxide of Formula II have an average particle diameter of 15 μm to 30 μm, respectively: Li 1+x Mn 2−z M z O 4 (I) Li 1+y Ni b Mn c Co 1−(b+c) O 2 (II) wherein, M is a metal having an oxidation number of 2 or 3; 0≦x≦0.2; 0≦y≦0.1; 0<z≦0.2; 0.2≦b≦0.7; 0.2≦c≦0.7; and b+c<1 and wherein the mixture of the lithium/manganese spinel oxide of Formula I and the lithium/nickel/cobalt/manganese composite oxide of Formula II is in the ratio of 30:70 to 70:30 by weight.