Cathode active material, method for manufacturing same, and lithium secondary battery comprising same

A method for manufacturing a positive active material, the method comprising:

• forming a positive active material precursor including nickel;
• mixing and firing the positive active material precursor and a lithium salt to form a preliminary positive active material particle;
• forming a coating material including fluorine on the preliminary positive active material particle by dry-mixing the preliminary positive active material particle with a coating source including fluorine;
• and
• manufacturing a positive active material particle by thermally treating the preliminary positive active material particle on which the coating material is formed, at a temperature lower than a crystal structure changing temperature of the positive active material particle, said crystal structure changing temperature being a temperature where the fluorine included in the coating source permeates into a crystal lattice of the positive active material particle,
• wherein the positive active material particle comprises nickel, and
• wherein the crystal structure changing temperature decreases as a content of nickel included in the positive active material particle increases.