▎ 摘　　要

NOVELTY - A method of preparing a graphene-sulfur nanocomposite for a cathode in a rechargeable lithium-sulfur battery, the graphene-sulfur nanocomposite comprising graphene layers, the method involves thermally expanding graphite oxide to yield graphene layers; mixing the graphene layers with a first solution comprising sulfur and carbon disulfide; evaporating the carbon disulfide to yield a solid nanocomposite; and grinding the solid nanocomposite to yield the graphene-sulfur nanocomposite having sulfur particles with an average diameter less than 50 nm. USE - For preparing a graphene-sulfur nanocomposite for a cathode in a rechargeable lithium-sulfur battery (claimed). ADVANTAGE - The battery has a discharge capacity of at least 74% of an initial capacity after 50 cycles at 0.1 C. The rechargeable lithium-sulfur battery has a reversible capacity greater than 950 mAh. The graphene-sulfur nanocomposite has a sulfur loading greater than 70 wt.%. The applied polymer coating provides improved mechanical strength in addition to improved chemical and electrochemical stability. The sulfonated tetrafluoroethylene fluoropolymer-copolymer can form dense films to coat the surface of graphene-sulfur nanocomposites, which inhibit the polysulfide from diffusing into the electrolyte from the adsorbed sulfur particles. Since it is a cationic membrane with sulfonate ionic groups, Li ions readily diffuse through the membrane, while still suppressing polysulfide anion transport, most likely due to electrostatic repulsion. DETAILED DESCRIPTION - A method of preparing a graphene-sulfur nanocomposite for a cathode in a rechargeable lithium-sulfur battery, the graphene-sulfur nanocomposite comprising graphene layers, where the graphene layers have thicknesses of less than or equal to 10 nm, and with particles comprising sulfur adsorbed to the graphene layers, the method involves thermally expanding graphite oxide to yield graphene layers; mixing the graphene layers with a first solution comprising sulfur and carbon disulfide; evaporating the carbon disulfide to yield a solid nanocomposite; and grinding the solid nanocomposite to yield the graphene-sulfur nanocomposite having sulfur particles with an average diameter less than 50 nm.