Positive electrode active material for lithium secondary battery and lithium secondary battery

A lithium secondary battery comprising:

• a positive electrode;
• a negative electrode;
• a separator interposed between the positive electrode and the negative electrode;
• and
• an electrolyte,
• wherein the positive electrode includes, as a positive electrode active material, a lithium composite transition metal oxide which has a layered structure,
• wherein the lithium composite transition metal oxide is represented by Chemical Formula 1:
• Lix[NiaCobMncMd]O2 [Chemical Formula 1]
• wherein, in Chemical Formula 1,
• M includes a first doping element and a second doping element,
• wherein the first doping element includes Ti and one or more elements selected from the group consisting of Cr, V, Fe, Zn, Cu and Mg, and
• the second doping element includes W and one or more elements selected from the group consisting of Nb, Ta, and Mo, and
• 0.98≤x≤1.2, 0.85≤a≤0.95, 0≤b<0.15, 0<c<0.15, and 0<d<0.15, and
• wherein the first doping element is included in an amount of 1,000 ppm to 3,000 ppm based on a total weight of the lithium composite transition metal oxide,
• wherein the second doping element is included in an amount of 1,000 ppm to 5,000 ppm based on a total weight of the lithium composite transition metal oxide,
• wherein the lithium composite transition metal oxide includes, on a surface thereof, a coating layer including one or more elements selected from the group consisting of Al, Ti, W, B, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si and S,
• wherein the positive electrode active material has a phase-transform temperature of 300° C. or more, wherein the phase-transform temperature is a temperature at which the layered structure is changed to a spinel structure in a fully charged state.