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

A method of preparing a positive electrode material is provided. The method includes mixing a first positive electrode active material precursor having an average particle diameter (D) of 10 μm to 30 μm with a lithium-containing raw material and pre-sintering the mixture to obtain a first pre-sintered product, mixing a second positive electrode active material precursor having an average particle diameter (D) different from that of the first positive electrode active material precursor with a lithium-containing raw material and pre-sintering the mixture to obtain a second pre-sintered product, disintegrating each of the first pre-sintered product and the second pre-sintered product, and mixing the disintegrated first pre-sintered product and the disintegrated second pre-sintered product and main-sintering the mixture to obtain a positive electrode material.