Facile Fabrication of Sulfur/Graphene Composite for High‐Rate Lithium‐Sulfur Batteries

Abstract

Abstract A sulfur‐graphene composite (SG) is obtained by hydrothermally treating elemental sulfur powder with graphene oxide under alkaline condition. Structural and morphological analysis indicates a highly dispersed non‐crystalline state of sulfur throughout the material. Raman theoretical calculation reveals sulfur molecules in SG are identical to calculated S 8 allotrope. The resulting SG cathode provides high sulfur utilization of 97.67% as it delivers an extremely high initial capacity of 1636.1 mAh g −1 at 0.2 C. Even at high rates such as 1 C and 3 C, SG still delivers excellent performance. Moreover their capacity retention is high around 64.84% and 67.86% after 50 cycles at 1 C and 3 C, respectively. It exhibits outstanding stable cycling capability, with an initial capacity at 866.9 mAh g −1 at 5 C with a remaining capacity of 385.4 mAh g −1 after 250 cycles. Such exceptional performance lay in the highly dispersed nature of amorphous sulfur, the unique three dimensional architecture of graphene coupled to its strong intimate contact with sulfur. The presented design is extremely simple, scalable and promising for future commercialization of Li−S cells.