Positive electrode active material, method of preparing the same, positive electrode including the positive electrode active material, and secondary battery including the positive electrode

A method of preparing a positive electrode active material, the method comprising:

• preparing carbon-based particles, and disposing the carbon-based particles on a core,
• wherein the preparing of the carbon-based particles comprises preparing preliminary carbon-based particles, and modifying the preliminary carbon-based particles by an oxidation treatment,
• wherein the modifying of the preliminary carbon-based particles by the oxidation treatment comprises at least one of
• a) performing a first heat treatment of the preliminary carbon-based particles at a temperature of 200° C. to 800° C. in at least one atmosphere of an oxygen atmosphere and an air atmosphere;
• and
• b) reacting the preliminary carbon-based particles with an acidic vapor at 120° C. to 300° C., and
• the core comprises Li1+xMO2+y, wherein M is at least one element selected from the group consisting of nickel (Ni), cobalt (Co), and copper (Cu), and 1≤x≤5 and 0≤y≤2.