Positive electrode for lithium secondary battery, preparation method thereof, and lithium secondary battery including same

A positive electrode for a lithium secondary battery, comprising:

• a first positive electrode active material including a lithium cobalt-based oxide;
• and
• a second positive electrode active material including a lithium composite transition metal oxide containing at least two selected from the group consisting of nickel (Ni), cobalt (Co), and manganese (Mn),
• wherein the second positive electrode active material has a single crystal size of 200 to 500 nm and is represented by Formula 2 below:
• Lia2Nix2Mny2COz2M2w2O2+δ [Formula 2]
• (in Formula 2, M2 includes at least one selected from the group consisting of Al, B, Ba, Ca, Zr, Ti, Mg, Ta, Nb, Sr, W, and Mo, and 0.9<a2≤1.1, 0.3≤x2≤0.95, 0<y2≤0.4, 0<z2≤0.5, 0≤w2≤0.1, 0≤δ≤0.02, and x2+y2+z2+w2=1) wherein, when the state of charge (SOC) of the first positive electrode active material in which the voltage of the lithium secondary battery reaches a constant voltage (CV) at 1 C-rate is referred to as SOC1, and the state of charge (SOC) of the second positive electrode active material in which the voltage of the battery reaches a constant voltage (CV) at 1 C-rate is referred to as SOC2, the SOC1 and the SOC2 satisfy the relationship represented by Equation 1 below:
• SOC1<SOC2<1.1×SOC1. [Equation 1]