4. Fibrous Hybrid of Graphene and Sulfur Nanocrystals for High-Performance Lithium–Sulfur Batteries

Graphene–sulfur (G–S) hybrid materials with sulfur nanocrystals anchored on interconnected fibrous graphene are obtained by a facile one pot strategy using a sulfur/carbon disulfide/alcohol mixed solution. The reduction of graphene oxide and the formation/binding of sulfur nanocrystals were integrated. The G–S hybrids exhibit a highly porous network structure constructed by fibrous graphene, many electrically conducting pathways and easily tunable sulfur content, which can be cut and pressed to pellets to be directly used as lithium–sulfur battery cathodes without using metal current-collector, binder and conductive additive. The porous network and sulfur nanocrystals enable rapid ion transport and short Li⁺ diffuse distance, the interconnected fibrous graphene provides highly conductive electron transport pathways, and the oxygen-containing (mainly hydroxyl/epoxide) groups show strong binding with polysulfides preventing their dissolution into electrolyte based on first-principles calculations. As a result, the G–S hybrids show a high capacity, an excellent high-rate performance and a long life over 100 cycles. These results demonstrate the great potential of this unique hybrid structure as cathodes for high performance lithium-sulfur batteries.