POSITIVE ELECTRODE ACTIVE MATERIAL AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a positive electrode active material including an overlithiated lithium manganese-based oxide, and capable of preventing the degradation in electrochemical properties of a lithium secondary battery, including rate characteristics, caused by an excess of lithium and manganese in the lithium manganese-based oxide, and particularly reducing side reactions between the lithium manganese-based oxide and a liquid electrolyte during high-voltage operation, and a lithium secondary battery including the same.