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

A lithium composite transition metal oxide includes nickel (Ni), cobalt (Co), and manganese (Mn), wherein the lithium composite transition metal oxide includes two or more elements selected from the group consisting of Zr, Al, V, Co, and Mg and additional two or more elements selected from the group consisting of Ti, Y, Sr, Nb, Ba, and Ca, and the lithium composite transition metal oxide is in a form of a particle having a crystallite size of 170-300 nm.