CATHODE ACTIVE MATERIAL, AND A LITHIUM SECONDARY BATTERY COMPRISING THE SAME

摘要

The present invention relates to a lithium nickel-cobalt composite oxide represented by chemical formula 1. [chemical formula 1] Li_1_+_aNi_bCo_cMe_dO_2 In chemical formula 1, -0.02 <= a <= 0.2, 0.4 <= b <= 0.6, 0.4 <= c <= 0.5, 0.0 <= d <= 0.1, and a + b + c + d = 1 are satisfied. Average oxidation numbers of transition metal of nickel-cobalt oxide represented by the chemical formula 1 are Ni = +3, Co = +3, and Me = +3. A trivalent transition metal (Me) may be one or more selected from the group consisting of SC, Y, La, Rh, Ir, Al, Ga, In, and Ta. A secondary battery including the positive electrode active material of the present invention can improve lifespan characteristics by suppressing an elution volume of nickel in the positive electrode active material.