POSITIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY, METHOD FOR PRODUCING SAME, AND LITHIUM SECONDARY BATTERY COMPRISING SAME

The present invention relates to a positive electrode active material having a core/shell structure, which comprises a sulfur-carbon composite containing thermally expanded-reduced graphene oxide, a carbon material as a core, and carbon nanotube as a shell, and a preparation method thereof and a lithium secondary battery comprising the same.