Nickel-based active material for lithium secondary battery, method of preparing the same, and lithium secondary battery including positive electrode including the nickel-based active material

A method of preparing a nickel-based active material for a lithium secondary battery, the method comprising:

• obtaining a nickel-based active material A by performing a first heat treatment on a mixture of a lithium precursor and metal hydroxide in an oxidative gas atmosphere;
• and
• mixing a raw material containing the nickel-based active material A and a hetero-element and performing a second heat treatment thereon,
• wherein a temperature at which the second heat treatment is performed is higher than a temperature at which the first heat treatment is performed, and
• the prepared nickel-based active material comprises at least one secondary particle comprising an aggregate of two or more primary particles, wherein at least a portion of the secondary particle has a radial alignment structure.