Decorating CoSe₂ hollow nanospheres on reduced graphene oxide as advanced sulfur host material for performance enhanced lithium-sulfur batteries

Although lithium-sulfur batteries are one of promising rechargeable energy storage devices, their wide applications are impeded by the lithium polysulfides shuttle effect, low electronic conductivity of the cathode, and sluggish redox reaction kinetics of lithium polysulfides. In this work, reduced graphene oxide was decorated with CoSe₂ hollow nanospheres to form an RGO-CoSe₂ composite that was used as a host material to support S in the cathode. The RGO-CoSe₂ composite has the following superiorities: (1) enhanced electronic conductivity, (2) accommodation of the volumetric change of cathode materials, (3) effective confinement of numerous lithium polysulfides species due to chemisorption, (4) expedition of the redox kinetics of lithium polysulfides. As expected, the RGO-CoSe₂-based cathode exhibited the reversible specific capacity of 1, 044.7 mAh/g at 0.2C and 695.7 mAh/g at 2C, together with excellent cycling stability of 0.071% average capacity decay per cycle over 400 cycles at 1C.