Fe2O3/rGO/CNT composite sulfur hosts with physical and chemical dual-encapsulation for high performance lithium–sulfur batteries

Abstract

Lithium–sulfur batteries are one of the promising alternatives to the traditional lithium-ion batteries, but the dissolution of polysulfides and the low conductivity of cathode materials are two important factors limiting their rapid development. In this paper, a novel sulfur-host material was synthesized by a simple method. The sulfur-host material used reduced graphene oxide (rGO) and carbon nanotubes (CNTs) as the synergistic conductive skeleton and nano-Fe₂O₃ as the adsorbent of lithium polysulfides. Finally, the as-prepared Fe₂O₃/rGO/CNT/S cathode material exhibits stable cycling performance and excellent ionic and electronic conductivities. The initial specific capacity of Fe₂O₃/rGO/CNT/S is 963 mA h g⁻¹ at 0.5C, and the capacity remains to be 758 mA h g⁻¹ after 100 cycles. The average specific capacities of Fe₂O₃/rGO/CNT/S are 999 mA h g⁻¹, 901 mA h g⁻¹ and 825 mA h g⁻¹, respectively, at different rates of 0.2C, 0.5C and 1C, with good rate performance. The initial specific capacity of Fe₂O₃/rGO/CNT/S is 899 mA h g⁻¹ at 2C. After 400 cycles, the capacity remains to be 521 mA h g⁻¹, and the capacity decay rate is only 0.1% per cycle. This structure provides a reference for developing lithium–sulfur battery cathode materials with excellent performance.