MOF‐Derived MoC/WC Heterostructure as Bidirectional Catalyst for Lithium Polysulfide Enables High‐Performance Lithium‐Sulfur Batteries

Abstract Since lithium‐sulfur (Li‐S) batteries have high energy density and environmental friendliness, they have garnered a lot of attention as a new type of energy storage technology. However, the shuttle effect of lithium polysulfides (LiPSs) and low utilization of sulfur (S) in Li‐S batteries reduce the cycle stability and energy efficiency and limit their practical application. Therefore, it is urgent to achieve simultaneous immobilization and conversion of LiPSs utilizing catalysts. Herein, a metal–organic framework (MOF)‐derived MoC/WC@NC heterojunction is synthesized as a bidirectional catalyst for LiPSs in high‐performance Li‐S batteries. Experimental and theoretical calculations indicate that the catalyst is expected to improve the catalytic activity for reduction and oxidation reactions of LiPSs, thereby accelerating the kinetics of Li‐S batteries. In conclusion, with the incorporation of the novel catalyst between the cathodes and separators in Li‐S batteries, the assembled batteries demonstrate excellent rate performance, with an initial discharge capacity of 1752.1 mAh g −1 at 0.1 C, and a discharge‐specific capacity of 783.2 mAh g −1 even at 2 C. More significantly, the coulombic efficiency stayed above 99% and the capacity of 589.1 mAh g −1 after 1000 cycles at 1 C with a decay rate of only 0.062% each cycle.