High‐Performance Lithium‐Sulfur Batteries: Medium‐Entropy Alloys Embedded in CeO 2 for Polysulfide/Sulfide Bidirectional Catalysis

Abstract The slow kinetics of the sulfur reduction reaction (SRR) and Li 2 S oxidation reaction (SOR) in lithium‐sulfur batteries (LSBs) seriously affect their practical applications. Herein, we prepared a functional interlayer for LSBs consisting of hydroxylated carbon nanotubes dispersed with NiCoMoIr medium‐entropy alloys embedded in CeO 2 surface materials. Experimental results revealed a bidirectional catalytic mechanism involving different elements, verifying that Ir and Ni promote the SRR of Li 2 S 6 to Li 2 S. Meanwhile, Co and Mo were found to primarily promote the conversion process of Li 2 S to Li 2 S 6 . CeO 2 exhibits a bidirectional synergistic effect on enhancing the kinetics of the SRR and SOR. The battery exhibits a specific capacity of 1535.7 mAh g −1 at 0.2 C, and the decay rate is only 0.051% for per‐cycle of 1000 cycles at 1 C. More importantly, a 2 Ah‐level pouch cell with an energy density of 436.4 Wh kg −1 and the capacity decay rate was 0.039% per‐cycle after 800 cycles.