Rechargeable lithium battery positive electrode active material and rechargeable lithium battery including the same

Abstract

The present invention relates to a positive electrode active material for a rechargeable lithium battery and a rechargeable lithium battery including the same. The positive electrode active material includes a lithium nickel-based composite oxide, wherein the positive electrode active material is in the form of secondary particles in which a plurality of primary particles are aggregated, and at least a portion of the primary particles are radially arranged, in a cross-section of the secondary particle, a cross-sectional area of less than about 0.1 μm 2 The number ratio of the primary particles is greater than or equal to about 65%, and a full width at half maximum (FWHM) of a peak corresponding to a (003) plane in an X-ray diffraction analysis of the positive electrode active material is less than or equal to about 0.125.