POSITIVE ELECTRODE ACTIVE MATERIAL FOR SECONDARY BATTERY, METHOD OF PREPARING THE SAME, AND LITHIUM SECONDARY BATTERY INCLUDING THE POSITIVE ELECTRODE ACTIVE MATERIAL

The present invention relates to a positive electrode active material for a secondary battery which includes a lithium composite transition metal oxide including nickel (Ni), cobalt (Co), and manganese (Mn), wherein the lithium composite transition metal oxide includes 60 mol% or more of the nickel (Ni) among metals excluding lithium, and a coating layer is formed on surfaces of particles of the lithium composite transition metal oxide, wherein the coating layer includes a lithium-polymer compound which is formed by a reaction of a lithium by-product with a polymer.