▎ 摘　　要

NOVELTY - A thermally expanded reduced graphene oxide has specific surface area of 400-1200 m2/g. USE - Thermally expanded reduced graphene oxide used for forming sulfur-carbon complex for lithium secondary battery e.g. lithium sulfur battery (all claimed). ADVANTAGE - The thermally expanded reduced graphene oxide has improved reactivity of sulfur and excellent discharge capacity and lifetime service. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) preparation of the thermally expanded reduced graphene oxide, which involves thermally expanding (a) graphene oxide by heat treatment at temperature of 300-500 degrees C, and reducing (b) the heat-expanded graphene oxide by heat treatment at a temperature of 700-1200 degrees C; (2) sulfur-carbon complex, which comprises the thermally expanded reduced graphene oxide and sulfur on at least a portion of the interior and surface of the thermally expanded reduced graphene oxide; and (3) lithium secondary battery, which comprises an anode, a cathode, a separator interposed between the anode and the cathode and electrolyte.