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

A cathode active material for a lithium secondary battery includes a lithium-transition metal composite oxide particle having a lattice strain (η) of 0.18 or less, which is calculated. by applying Williamson-Hall method defined by Equation 1 to XRD peaks measured through XRD analysis, and having an XRD peak intensity ratio of 8.9% or less, which is defined by Equation 2. By controlling the lattice strain and XRD peak intensity ratio of the lithium-transition metal composite oxide particle, a lithium secondary battery with improved life-span characteristics as well as output characteristics is provided.