Positive Electrode Active Material For Secondary Battery, Method Of Preparing The Same, And Lithium Secondary Battery Including The Same

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

• a lithium composite transition metal oxide including nickel (Ni), cobalt (Co), and manganese (Mn), and
• at least one particle growth-promoting element selected from the group consisting of strontium (Sr), zirconium (Zr), magnesium (Mg), yttrium (Y), and aluminum (Al),
• wherein the lithium composite transition metal oxide comprises the nickel (Ni) in an amount of 65 mol % or more and the manganese (Mn) in an amount of 5 mol % or more based on a total amount of transition metals, and
• wherein the positive electrode active material comprises a single particle.