Sulfur covalently bonded graphene with large capacity and high rate for high-performance sodium-ion batteries anodes

Na-ion battery is playing an important role as a low-cost alternative power source to Li-ion battery. Developing novel carbonaceous anode materials is highly demanded for high performance and environmental benignity. We report, for the first time, the graphene sheets covalently bonded with sulfur atoms as Na-ion battery anode material with a large reversible capacity of 291 mA h g(-1) and an outstanding rate capability with 127 and 83 mA h g(-1) at 2.0 and 5.0 A g (charging/discharging in 3.8 and 1 min, respectively), and a long cycling stability as well. Both experiment and density functional theory calculation proves that the superior performance is mainly attributed to the unique nanoporous structure stemmed from the chemically S doping. This material holds great promise in future application of low cost, high-performance Na-ion batteries. (C) 2015 Elsevier Ltd. All rights reserved.