Positive electrode active material and method for preparing the same

A method for preparing a positive electrode active material comprising:

• reacting a coating precursor preparation solution comprising a metal solution containing metal ions and a chelating agent to prepare a coating precursor, wherein the coating precursor is a complex in which the metal ions and the chelating agent are combined;
• and
• dry-mixing particles having the composition of Formula 1 or Formula 2 below and the coating precursor to obtain a mixture, followed by firing the mixture to form a coating layer having the composition of Formula 3 below on surfaces of the particles:
• Li[Co1-aM1a]O2 [Formula 1]
• wherein, in Formula 1 above,
• M1 is one or more selected from the group consisting of B, Mg, Ca, Al, Ti, V, Cr, Fe, Zn, Ga, Y, Zr, Nb, Mo, Ta, and W, and 0≤a<0.1,
• Li[NibCocMndM2e]O2 [Formula 2]
• wherein, in Formula 2 above,
• M2 is one or more selected from the group consisting of B, Mg, Ca, Al, Ti, V, Cr, Fe, Zn, Ga, Y, Zr, Nb, Mo, Ta, and W, and 0.8≤b<1, 0<c<0.2, 0<d<0.2, 0≤e<0.1, and b+c+d+e=1,
• Li[NifCogMnhM3i]O2 [Formula 3]
• wherein, in Formula 3 above, M3 is one or more selected from the group consisting of B, Mg, Ca, Al, Ti, V, Cr, Fe, Zn, Ga, Y, Zr, Nb, Mo, Ta, and W, and 0<f≤0.4, 0≤g≤0.6, 0≤h≤0.6, 0≤i<0.1, and f+g+h+i=1.