Positive Electrolyte Active Material for Secondary Battery, Preparation Method Thereof, and Lithium Secondary Battery Including Same

A method for preparing a positive electrode active material for a secondary battery, the method comprising:

• mixing a positive electrode active material precursor including nickel (Ni), cobalt (Co), and manganese (Mn), a lithium raw material, and at least two kinds of first dopant raw materials selected from the group consisting of Zr, Al, V, Co, and Mg, and subjecting the mixture to primary firing;
• and
• after the primary firing, mixing at least two kinds of second dopant raw materials selected from the group consisting of Ti, Y, Sr, Nb, Ba, and Ca, and subjecting the mixture to secondary firing, wherein
• particles of a lithium composite transition metal oxide having a crystallite size of 170 nm to 300 nm are formed through the primary firing and the secondary firing.