POSITIVE ELECTRODE ACTIVE MATERIAL COMPRISING LITHIUM-RICH LITHIUM MANGANESE OXIDE HAVING FORMED THEREON COATING LAYER COMPRISING LITHIUM-DEFICIENT TRANSITION METAL OXIDE, AND LITHIUM SECONDARY BATTERY COMPRISING SAME

摘要

The present invention provides a positive electrode active material comprising lithium-rich lithium manganese oxide, and a method for preparing same, the lithium-rich lithium manganese oxide being represented by chemical formula (1), Li_1+aNi_xCo_yMn_zM_vO_2-bA_b (1), wherein: 0a≤0.2, 0x≤0.4, 0y≤0.4, 0.5≤z≤0.9, 0≤v≤0.2, a+x+y+z+v=1, 0≤b≤0.5; M is one or more element selected from the group consisting of Al, Zr, Zn, Ti, Mg, Ga, In, Ru, Nb and Sn; A is one or more element selected from the group consisting of P, N, F, S and Cl; and a coating layer is formed on the surface of the lithium-rich lithium manganese oxide, the coating layer comprising a lithium-deficient transition metal oxide that is deficient in lithium with lithium being included at a mole ratio of less than 1 relative to the transition metal, and the amount of the coating layer being 1-10 weight% with respect to the total weight% of the positive electrode active material.