One-pot in situ chemical reduction of graphene oxide and recombination of sulphur as a cathode material for a Li-S battery

摘要

Li-S batteries with a high theoretical specific capacity and energy density are poised to be one of the most promising next generation systems; however, the complex preparation process of the cathode material and low cyclic stability, particularly at high current density, have limited their practical applications. Herein, we report a facile and eco-friendly one-pot strategy for the chemical reduction of graphene oxide and recombination of sulphur as the cathode material for a Li-S battery. The optimized rGO/S-3 composite material possesses a porous morphology with pore walls made of the rGO and sulphur composite. The sulphur content is about 73.5 wt%, the particle size is about 8-15 nm, and the particles are distributed evenly on the layer of rGO, wherein the thickness of rGO is about 3-4 nm, corresponding to 8-10 monolayer graphenes. The rGO/S-3 composite electrode presents a high initial discharge capacity of 1012 and 474 mA h g(-1) at 1C and 10C, respectively. The discharge capacity of 451 mA h g(-1) was preserved after 1200 cycles at 1C. Even though the current density increased to 10C, a discharge capacity of 237 mA h g(-1) may be obtained after 400 cycles.