Supercritical CO2-assisted fabrication of CeO2 decorated porous carbon/sulfur composites for high-performance lithium sulfur batteries

Abstract

Alleviating shuttle effect is vital to improve the electrochemical performance of lithium–sulfur (Li–S) batteries. Herein a nanosheet-like porous carbon (NSPC) with unique hierarchically porous structure and excellent electrical conductivity was synthesized as a host material of cathode, and highly-dispersed, electrochemically active CeO2 nanoparticles as well as sulfur was deposited onto NSPC subsequently through supercritical CO2-assisted processing to fabrticate CeO2 decorated porous carbon/sulfur (C/CeO2/S) composites. In testing Li–S batteries, the C/CeO2/S material shows an initial capacity of 1538 mAh g−1 at 0.1 C, higher than that of C/S (1194 mAh g−1). The material also exhibits excellent cycling stability (~ 729 mAh g−1 at 0.5 C after 300 cycles). The gas-like viscosity, diffusivity and surface tension of supercritical CO2, facilitate highly dispersed loading of CeO2 and sulfur on porous carbon with less agglomeration and more intimate contact with carbon to achieve higher conductivity and utilization efficiency. Moreover the electrocatalytic material CeO2 promotes and stabilizes the redox reaction of polysulfide species.