Cathode active material for lithium secondary battery and lithium secondary battery including the same

A method of preparing a cathode active material for a lithium secondary battery, comprising:

• mixing a transition metal precursor, a lithium precursor and a phosphorus source to form a mixture;
• and
• firing the mixture to form a lithium-transition metal oxide particle containing phosphorus introduced into the particle and a coating formed on at least a portion of a surface of the lithium-transition metal oxide particle, the coating containing a phosphorus-containing compound,
• wherein a content of phosphorus introduced into the lithium-transition metal oxide particle is in a range from 15 wt % to 30 wt % based on a sum of a weight of phosphorus introduced into the lithium-transition metal oxide particle and a weight of phosphorus contained in the coating measured by an ICP-OES analysis.