A novel acetylene black/sulfur@graphene composite cathode with unique three-dimensional sandwich structure for lithium-sulfur batteries

A novel acetylene black/sulfur@graphene composite (AB/S@G) with unique three-dimensional sandwich structure was successfully prepared via an in situ sulfur deposition strategy and self-assembly. Acetylene black as conductive carbon skeleton and graphene nanosheets as physical shields played an extremely important role for improving the electrochemical performances of the AB/S@G cathode. Compared with the AB/S cathode, the AB/S@G cathode with a sulfur content of 54 wt% exhibited a high utilization of sulfur, an enhanced cyclical stability, and an excellent rate capability. The AB/S@G cathode came true a high sulfur utilization of 95.73% after undergoing a high initial discharge capacity of 1603.5 mAh g−1 at a current density of 200 mA g−1, much higher than that (71.78%) of the AB/S cathode. The excellent electrochemical performances were principally attributed to the combined effect of graphene nanosheets and acetylene black, which provided an improved electrical conductivity for the sulfur cathode, effective restraining for soluble polysulfides, and powerful buffer for the volume changes of sulfur during cycling.