Nitrogen and Sulfur Co-doped Two-Dimensional Highly\nPorous Carbon Nanosheets for High-Performance Lithium–Sulfur\nBatteries

Abstract

The multiple electron redox reactions\nof lithium (Li) and sulfur\n(S), concomitantly producing a series of lithium polysulfide intermediates,\ngenerally exhibit an insufficient cycle life and poor rate performance\nof lithium–sulfur (Li–S) batteries. This work reports\na single-step and facile synthetic strategy for fabricating uniform,\nmicro- and mesoporous, nitrogen–sulfur co-doped carbon nanosheets\nanchored on the surface of reduced graphene oxide (denoted as CNS@rGO).\nThe composite was prepared by polymerizing m-aminobenzene sulfonic\nacid on the surface of graphene oxide (GO) and subsequent carbonization.\nThe obtained CNS@rGO contains uniform micro- and mesopores for better\nsulfur loading and further accommodation of the discharged polysulfides.\nSuch a free-standing electrode exhibits a stable specific capacity\nof 1355 mA h/g at 0.1 C (100 mA g^–1) and good rate\nperformance. CNS@rGO shows promising characteristics as a high-performance\ncathode material for Li–S batteries. Furthermore, even at a\nhigh current density of 1 C (1 A g^–1), it exhibits\nhigh storage with a capacity of 476 mA h g^–1 over\n300 cycles with a decay of 16.8%, which outperforms all previously\nreported carbon-based materials for Li–S batteries.