Liquid-phase exfoliated-graphene-supporting nanostructural sulfur as high-performance lithium–sulfur batteries cathode

Abstract

Abstract Lithium-sulfur (Li–S) batteries with high energy density are promising candidates to satisfy emerging energystorage demands. Nevertheless, the poor conductivity of sulfur and fast capacity decay of the sulfur-based electrodes restrict its practical applications. Here, we report a facile and simple titration method to synthesize nano-sulfur@liquid-phase exfoliated graphene (Nano-S@LEGr) composites by in situ growth of nanostructural sulfur on the LEGr surface. The as-prepared Nano-S@LEGr with tunable sulfur morphologies exhibited excellent electrochemical performance as the cathode material for Li–S batteries. In particular, the spherical Nano-S@LEGr composites with 68 wt% sulfur displayed a reversible capacity of 552.8 mAh g −1 after 100 cycles at a current density of 0.5C. Even at a high current density of 1C, a discharge capacity of 532.8 mAh g−1 could be delivered. Compared to rod-like Nano-S@LEGr and the graphene oxide derived cathode, the as-prepared spherical Nano-S@LEGr showed higher specific capacity, superior cycling stability and rate capability.