Method of Preparing Positive Electrode Active Material for Lithium Secondary Battery and Positive Electrode Active Material Prepared Thereby

The present invention relates to a method of preparing a positive electrode active material for a lithium secondary battery and a positive electrode active material prepared thereby, wherein the preparation method includes a first step of preparing a lithium transition metal oxide by mixing a lithium raw material and a transition metal precursor containing 70 mol % or more of nickel based on the total number of moles of transition metals and sintering the mixture; and a second step of washing the lithium transition metal oxide with hot water of more than 90° C., wherein, after the second step, a result of EELS analysis of a particle surface of the lithium transition metal oxide satisfies Equation 1.