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

A method of preparing a positive active material, the method comprising:

• obtaining a precursor of a lithium transition metal oxide by mixing a Li-containing compound, a Na-containing compound, a W-containing compound, a Mg-containing compound, a Ti-containing compound, an M-containing compound, and an S-containing compound;
• and
• heat-treating the precursor to obtain a positive active material comprising a lithium transition metal oxide represented by Formula 1.
• Li1-xNaxM1-(α+β+γ)WαMgβTiyO2-aSa, Formula 1:
• wherein in Formula 1,
• M includes one or more elements selected from alkali metal elements, alkali earth metal elements, transition metal elements, metalloid elements, and non-metallic elements, other than W, Mg, Ti, Na, and S, and
• 0<x≤0.01, 0<α≤0.01, 0<β≤0.005, 0<γ≤0.005, 0<a≤0.01, and 0<α+β+γ≤0.02.