Lithium secondary battery

A cathode active material for a lithium secondary battery, comprising:

• a first cathode active material particle represented by the following Chemical Formula 1;
• LixM1aM2bM3cOy [Chemical Formula 1]
• wherein in Chemical Formula 1, M1, M2 and M3 independently include at least one element selected from a group consisting of Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga and B,
• 0<x≤1.1, 1.98≤y≤2.02, 0.6≤a≤0.95 and 0.05≤b+c≤0.4, and
• a second cathode active material particle represented by the following Chemical Formula 2 or Formula 3;
• LixNiaCobMncM4dM5eOy [Chemical Formula 2]
• wherein in Chemical Formula 2, M4 includes at least one element selected from a group consisting of Ti, Zr, Al, Mg, and Cr;
• and M5 includes at least one element selected from a group consisting of Sr, Y, W, and Mo;
• and
• 0<x<1.5, 1.98≤y≤2.02, 0.313≤a≤0.353, 0.313≤b≤0.353, 0.313≤c≤0.353, 0≤d≤0.03, 0≤e≤0.03, and 0.98≤a+b+c≤1.02,
• LixNiαCoβMnγM4δM5εOy [Chemical Formula 3]
• wherein in Chemical Formula 3, M4 includes at least one element selected from a group consisting of Ti, Zr, Al, Mg, and Cr;
• and M5 includes at least one element selected from a group consisting of Sr, Y, W, and Mo;
• and
• 0<x<1.1, 1.98≤y≤2.02, 0.48≤α≤0.52 0.18<β≤0.27, 0.24≤γ≤0.32, 0≤δ≤0.03, 0≤ε≤0.03, and 0.98≤α+β+γ≤1.02,
• wherein metal elements except for lithium included in the second cathode active material particle do not have a concentration gradient region between a central portion of the second cathode active material particle and a surface of second cathode active material particle,
• wherein the second cathode active material particle includes primary particles being aggregated with each other, the primary particles having different shapes or crystalline structures from each other,
• wherein the different shapes include a first shape including a granular shape or a spherical shape and a second shape including a rod shape or a needle shape,
• wherein the second cathode active material particle includes a first particle arranged in a central region and a second particle arranged in a peripheral region, and the first particle and the second particle have the different shapes or crystalline structures from each other.