A heterogeneous FeP-CoP electrocatalyst for expediting sulfur redox in high-specific-energy lithium-sulfur batteries

Abstract Lithium-sulfur batteries (LSBs) with high theoretical energy density and low cost have become one of the competitive candidates for next-generation energy storage devices. Nevertheless, the shuttle effect of polysulfide leads to rapid capacity decay and hinders the practical application of LSBs. Herein, a composite of heterogeneous bimetallic phosphide and graphene oxide (FeP-CoP/GO) is devised as a high-efficiency catalyst. FeP-CoP not only promotes the deposition of Li2S to improve the utilization of sulfur, but also offers adequate active sites for anchoring and catalyzing the transformation of polysulfide to restrain the shuttle effect. And GO plays a role of auxiliary enhancement because of its big specific surface area and good conductivity. Therefore, FeP-CoP/GO/S with 79 wt.% sulfur content exhibits a high discharge capacity of 773 mAh g−1 at 0.5 C and displays favorable cycle stability of 481 mAh g−1 after 300 cycles with high coulombic efficiency of 96.6%. Bimetal phosphides as the catalyst offer a new perspective for high-specific-energy Li-S batteries.