Efficient Catalysis of Ultrathin Two‐Dimensional Fe₂O₃–CoP Heterostructure Nanosheets for Polysulfide Redox Reactions

Abstract

The “shuttle effect” and slow redox reactions of Li‐S batteries limit their practical application. To solve these problems, a judicious catalyst design for improved battery cycle life and rate performance is essential. Herein, this issue is addressed by modifying the Li‐S battery separator using a 2D Fe₂O₃–CoP heterostructure that combines the dual functions of polar Fe₂O₃ and high‐conductivity CoP. The synthesized ultrathin nanostructure exposes well‐dispersed active sites and shortens the ion diffusion paths. Theoretical calculations, electrochemical tests, and in situ Raman spectroscopy measurements reveal that the heterostructure facilitates the inhibition of polysulfide shuttling and enhances the electrode kinetics. A sulfur cathode constructed using the Fe₂O₃–CoP‐based separator provides an astonishing capacity of 1346 mAh g⁻¹ at 0.2 C and a high capacity retention of ≈84.5%. Even at a high sulfur loading of 5.42 mg cm⁻², it shows an area capacity of 5.90 mAh cm⁻². This study provides useful insights into the design of new catalytic materials for Li‐S batteries.