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

The present disclosure relates to a positive electrode material powder, and a positive electrode and a lithium secondary battery including the same. The positive electrode material powder includes a lithium nickel-based oxide having a nickel content of 80 mol % or more among metals excluding lithium is 80 mol % or more, has a Dof 4 μm or more, and has a degree of single-particle formation represented by Equation in a range of about 35% to 60%. In Equation, A (unit: μm) is a median of primary particle areas of the positive electrode material powder measured through SEM image analysis, and the D(unit: μm) is a volumetric cumulative average of the positive electrode material powder measured using a particle size analyzer.