High-Nickel Positive Electrode Active Material, Producing Method Thereof, Positive Electrode and Lithium Secondary Battery Comprising the Same

A method for producing a positive electrode active material, a positive electrode active material produced thereby, and a positive electrode and a lithium secondary battery including the same are provided. The method includes preparing a nickel-manganese-aluminum precursor having an atomic fraction of nickel of 90 atm % or greater in all transition metals, and mixing the nickel-manganese-aluminum precursor, a cobalt raw material, and a lithium raw material and heat treating the mixture.