Positive Electrode Active Material For Lithium Secondary Battery And Preparation Method Thereof

A positive electrode active material in the form of a single particle and a lithium secondary battery containing the positive electrode active material thereof are provided. The positive electrode active material has a nickel-based lithium composite metal oxide single particle. The single particle includes a metal doped in the crystal lattice thereof. The single particle includes, in the crystal lattice, a surface part having a rock salt structure, a spinel structure, or a mixed structure thereof from a surface of the single particle to a depth of 0.13% to 5.26% of a radius of the single particle, and a central part having a layered structure from an interface with the surface part thereof to the center part of the single particle.