MOF-derived Co9S8/C hollow polyhedra grown on 3D graphene aerogel as efficient polysulfide mediator for long-life Li-S batteries

Abstract Lithium-sulfur (Li-S) batteries are considered as one of the most promising candidates for next-generation energy storage systems because of their high energy density. However, rapid capacity fade and low sulfur content caused by the shuttle effect of soluble lithium polysulfides (LiPSs) and the low conductivity of sulfur hinder the practical applications of Li-S batteries. In this regard, we synthesized metal-organic framework (MOF)-derived Co9S8/C hollow polyhedra grown on three-dimensional graphene aerogel (3D GA) as an efficient sulfur host material. The highly porous, conductive and free-standing 3D GA framework enables high sulfur content (77.3 wt%). The polar Co9S8/C provides strong chemical binding to immobilize polysulfides, and suppress the shuttling effect. Significantly, the Co9S8/C/GA/S cathode exhibits excellent long cycling stability with a low capacity decay rate of 0.0473% per cycle over 400 cycles.