Positive electrode active material for lithium secondary battery, preparation method therefor, and lithium secondary battery comprising same

Abstract

The present invention comprises, in lithium composite oxide particles, an overlithiated oxide having a layered crystal structure and represented by chemical formula 1 below, and comprises a lithium manganese oxide represented by chemical formula 2 below outside the lithium composite oxide particles, wherein the overlithiated oxide included in the particles and the lithium manganese oxide included outside the particles have different Li/IM values. [Chemical formula 1] rLiMnO·(1-)LiNiCoMnM1O(wherein, in chemical formula 1, 0<r≤0.6, 0<a≤1, 0≤x≤1, 0≤y<1, 0≤z<1, and 0<x+y+z≤1, and M1 is at least any one selected from Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Mg, Gd, Sin, Ca, Ce, Fe, Al, Ta, Mo, Se, Zn, Nb, Cu, in, S, B, and Bi) [Chemical formula 2] LiMnO(wherein, in chemical formula 2, 0.1≤b/p≤2.5 and 0<q≤15).