POSITIVE ELECTRODE ACTIVE MATERIAL FOR RECHARGEABLE LITHIUM BATTERY, POSITIVE ELECTRODE INCLUDING THE SAME, AND RECHARGEABLE LITHIUM BATTERY INCLUDING THE SAME

A positive electrode active material includes: (a) a first particle of a lithium iron phosphate-based compound having an olivine crystal structure and a first average particle diameter; (b) a second particle of a lithium iron phosphate-based compound having an olivine crystal structure and a second average particle diameter smaller than the first average particle diameter; and (c) a third particle of a lithium nickel-cobalt-based oxide compound having a layered crystal structure, the first particle being in the form of a spherical secondary particle formed from aggregation of a plurality of primary particles, and the second particle being in the form of a single particle. Also disclosed is a positive electrode including the positive electrode active material, and a rechargeable lithium battery including the positive electrode.