Positive Electrode Material Powder, Positive Electrode and Lithium Secondary Battery Including the Same

A positive electrode material powder including a lithium nickel-based oxide represented by Chemical Formula 1 (LiNiCoMMO) and having a degree of single-particle formation, represented by the following Equation (1), of 0.3 to 0.8: In Equation (1), Ris a radius of the igrain as measured by subjecting an electrode manufactured using the positive electrode material powder to ion milling and then analyzing the cross section of the electrode by electron backscatter diffraction (EBSD), n is the total number of grains as measured by the EBSD analysis and ranges from 350 to 450, and Dis a volume-cumulative average particle diameter of the positive electrode material powder as measured using a laser diffraction particle size analyzer.