Method for Preparing Positive Electrode Active Material Precursor for Lithium Secondary Battery

A method for preparing a positive electrode active material precursor includes preparing a metal aqueous solution including a nickel raw material, a cobalt raw material, and a manganese raw material (step 1); adding the metal aqueous solution, an ammonium cation complex forming agent, and a basic aqueous solution into a reactor, co-precipitating the mixture at pH 11 to less than pH 12 to form nuclei of first positive electrode active material precursor particles and growing the nuclei (step 2); adjusting input amount of the basic aqueous solution to increase the pH in the reactor to a range of 0.8 to 1.5 compared to that of step 2; and adjusting input amount of the basic aqueous solution to change the pH in the reactor to pH 11 to less than pH 12 (step 4). A positive electrode active material precursor prepared by the above preparation method has an improved packing density.