POSITIVE ACTIVE MATERIAL FOR RECHARGEABLE LITHIUM BATTERY, METHOD OF PREPARING THE SAME, AND RECHARGEABLE LITHIUM BATTERY INCLUDING THE SAME

Disclosed is a positive active material for a rechargeable lithium battery including secondary particles of a nickel-based transition metal oxide composed of an inner portion and an outer portion, wherein the inner portion has a dense structure having a higher density than the outer portion, the secondary particles of the nickel-based transition metal oxide have a plurality of protruding portions on the surface thereof, and the positive active material has an area ratio of 25% to 30% occupied by the protruding portions calculated by Equation 1 based on a cross-section of the secondary particles of the nickel-based transition metal oxide.