Positive active material, method of preparing the same, and lithium secondary battery using the same

The present invention refers to a positive active material including a spinel lithium manganese oxide surface-coated with one or more types of nanoparticles selected from olivine-type lithium metal phosphate and metal oxide, a method of preparing the same and a lithium secondary battery using the same. The positive active material provides a lithium secondary battery having improved high-temperature cycle life characteristic and capacity per weight.