Organic polysulfanes grafted on porous graphene as an electrode for high-performance lithium organosulfur batteries

The performance of Li–S batteries is limited largely by the properties of the available sulfur electrodes. Here we report a novel composite sulfur electrode composed of organic polysulfane grafted directly on mesoporous graphene. Compared with sulfur chain based conventional organosulfur electrodes, the well-defined organic polysulfane with carbon skeleton has excellent structural stability during electrochemical cycling. Further, the mesopores on graphene sheets in this unique architecture can serve as channels to effectively facilitate rapid ion transport, leading to excellent battery performance. When tested as a free-standing electrode in a Li–S battery, the composite electrode demonstrates high capacity (1045 mAh/g at 1 C), superior rate capability (723 mAh/g at 20 C), excellent cycling stability (capacity retention of 95.3% after 1000 cycles at 5 C). The electrode materials still present good electrochemical performance even under high mass loading of sulfur (up to 20.3 mg/cm2). The remarkable electrochemical performance is attributed to the high structural stability and excellent electrical conductivity of the carbon skeleton and to the porous architecture of electrode that promotes fast ion transport. The greatly enhanced capacity and durability of the composite electrode make it ideally suited for the next-generation high-performance Li–S batteries. [Display omitted] •Organic polysulfane was grafted directly on mesoporous graphene.•The organic polysulfane has excellent structural stability.•The mesopores on graphene can facilitate rapid ion transport.•The battery has greatly enhanced capacity and durability.