CATHODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY INCLUDING THE SAME

A cathode active material for a lithium secondary battery has a structure of a lithium-nickel-based metal oxide. A crystal size in a (104) plane defined by Equation 1 is less than 200 nm. A thickness of a TM slab measured by a Rietveld method in a crystal structure of a space group R-3m by an X-ray diffraction (XRD) analysis is 2.15 Å or less. A thickness of a Li slab thickness measured by the Rietveld method in the crystal structure of the space group R-3m by the XRD analysis is 2.585 Å or more.