Nitrogen and Sulfur Co-doped Two-Dimensional Highly Porous Carbon Nanosheets for High-Performance Lithium–Sulfur Batteries

The multiple electron redox reactions of lithium (Li) and sulfur (S), concomitantly producing a series of lithium polysulfide intermediates, generally exhibit an insufficient cycle life and poor rate performance of lithium–sulfur (Li–S) batteries. This work reports a single-step and facile synthetic strategy for fabricating uniform, micro- and mesoporous, nitrogen–sulfur co-doped carbon nanosheets anchored on the surface of reduced graphene oxide (denoted as CNS@rGO). The composite was prepared by polymerizing m-aminobenzene sulfonic acid on the surface of graphene oxide (GO) and subsequent carbonization. The obtained CNS@rGO contains uniform micro- and mesopores for better sulfur loading and further accommodation of the discharged polysulfides. Such a free-standing electrode exhibits a stable specific capacity of 1355 mA h/g at 0.1 C (100 mA g^–1) and good rate performance. CNS@rGO shows promising characteristics as a high-performance cathode material for Li–S batteries. Furthermore, even at a high current density of 1 C (1 A g^–1), it exhibits high storage with a capacity of 476 mA h g^–1 over 300 cycles with a decay of 16.8%, which outperforms all previously reported carbon-based materials for Li–S batteries.