3D Hyperbranched Hollow Carbon Nanorod Encapsulated Sulfur Composites for Lithium-Sulfur Batteries with Superior Electrochemical Performance

Lithium-sulfur batteries have been plagued for a long time by the low Coulombic efficiency, fast capacity loss and poor high rate performance. Herein, we report the synthesis of graphitic hyperbranched hollow carbon nanorods encapsulated sulfur composites as cathode materials for lithium-sulfur batteries. The sulfur composite cathodes, approximate 1 mg for each electrode, deliver a high specific capacity of 1378 mAh/g at 0.1C current rate and exhibit stable cycling performance. The as-prepared cathode materials also achieve excellent high rate capacities and cyclability, such as 990 mAh/g at 1C, 861 mAh/g at 5C and 663 mAh/g at 10C, extending to more than 500 cycles. The superior electrochemical performances could be ascribed to the unique graphitic hyperbranched hollow carbon nanorods architecture and high length/radius aspect ratio of carbon nanorods, which can effectively prevent the dissolution of polysulfides, decrease self-discharge and confine the volume expansion on cycling. High capacity, excellent high-rate performance and long cycle life render the as-developed sulfur/carbon nanorod composites as a promising cathode material for lithium-sulfur batteries.