Positive active material for lithium secondary battery, method of preparing the same, and lithium secondary battery including positive active material

A positive active material for a lithium secondary battery (30), a method of preparing the same, and a lithium secondary battery (30) including the positive active material. The positive active material includes a core part and a shell part that include a nickel-based composite oxide. The content of nickel in the core part is larger than the content of nickel in the shell part.