One-pot self-assembly of graphene/carbon nanotube/sulfur hybrid with three dimensionally interconnected structure for lithium-sulfur batteries

A graphene/carbon nanotube (CNT)/sulfur (denoted GCS) hybrid with interconnected structure is prepared through a one-pot self-assembly approach initiated by L-ascorbic acid reduction under a mild condition. In such a solution-based assembly process, the formation of an interconnected graphene/CNT conductive network is accompanied by the uniform loading of sulfur, whose fraction is as high as of 70 wt%. The as-prepared GCS hybrid delivers an initial capacity of '1008 mAh g-1 at 03C and maintains 704 mAh g(-1), after 100 cycles. Remarkably, at a high rate of 1.0C, the cathode shows an excellent cyclic performance with a capacity of 657 mAh g(-1) after 450 ycles and the capacity decay is only 0.04% per cycle. Moreover, the superior rate performance of GCS hybrid is attributed to the conductive network formed by interconnected graphene sheets and CNT, which supply an unimpeded and continuous path for electron and Li ion transfer and accommodate the volume variation of sulfur during charge/discharge cycling. In addition, the residual functional groups on GCS can retain intimate contact of the conducting matrix with sulfur and effectively confine the diffusion of polysulfides. This study gives an eco-friendly and highly effective solution-based approach for carbon sulfur electrode for lithium sulfur battery. (C) 2015 Elsevier B.V. All rights reserved.