Reduced graphene oxide coated Fe-soc as a cathode material for high-performance lithium-sulfur batteries

Abstract

To solve the problem of the rapid decrease in capacity caused by poor conductivity, polysulfide shuttling, and the volume expansion associated with the reaction process, we attempt to use metal-organic framework (MOF) Fe-soc coated with reduced graphene oxide through electrostatic adsorption as a sulfur carrier material for lithium sulfur batteries. The research results show that S/Fe-soc@rGO has a high initial discharge specific capacity of 1634.3 mA h g−1 with a stable specific capacity retention rate of 865.3 mA h g−1 after 80 cycles and displays enhanced rate performance with high discharge specific capacities of 638.8 and 334.3 mA h g−1 after 200 cycles at 0.5 and 1 C, respectively. Fe-soc has unsaturated metal sites can adsorb sulfur and polysulfide, effectively bind polysulfide, symmetrical stable structure is conducive to speed up the electron and ion transmission efficiency while buffering the volume expansion during charge and discharge. In addition, reduced graphene oxide as a coating layer can better assist Fe-soc to increase the utilization rate of sulfur, and improve the conductivity of the cathode material, thereby improving the cycle performance and rate performance of lithium-sulfur batteries. This article is also expected to stimulate the application of MOF derivatives in energy storage materials.