Patent ID: 7838148

Claim:
A lithium nickel manganese cobalt composite oxide used as a cathode active material for a lithium rechargeable battery, the composite oxide shown by the below general formula (1): Li x Ni 1−y−z Mn y Co z O 2 (1), (wherein 0.9≦x≦1.3, 0<y<1.0, and 0<z<1.0; and wherein y+z<1), the lithium nickel manganese cobalt composite oxide having an average particle size of 5-40 μm, a BET ratio surface area of 5-25 m 2 /g, and a tap density of equal to or higher than 1.70 g/ml, and a ratio (A/B) of BET ratio surface area (A) against theoretical ratio surface area (B) of 5-50.