Dense integration of graphene and sulfur through the soft approach for compact lithium/sulfur battery cathode

The main challenge for the lithium/sulfur battery is the significant capacity decay over cycling, as the result of the diffusion of lithium polysulfide and volume/morphology changes of sulfur electrode. Porous graphene monoliths have been widely used to alleviate these problems with its confined frameworks of porous structures and strong mechanical property; however, bulk graphene materials were normally loosely packed, leading to the low utilization efficiency of pores and unsatisfactory frustration in suppressing polysulfide dissolution/shuttle owing to their large and highly open pores. Herein, we report the dense integration of sulfur and graphene (S-G) gel through the soft approach to prepare a compact sulfur cathode with dense but porous structure. The compact S-G structures could better increase the bonding between sulfur and graphene, immobilize sulfur and restrain the polysulfide diffusion within the more closed pores than loose counterpart, and thus achieve improved volumetric discharge capacities, high rate and long-term cycling performance. (C) 2015 Elsevier Ltd. All rights reserved