Ultrasmall CoFe Bimetallic Alloy Anchored on Fluoride‐Free MXene by One‐Pot Etching Strategy for the Barrier‐Adsorption‐Catalyst Functions of Polysulfides in Lithium‐Sulfur Batteries

Abstract

Abstract The rational construction of electrocatalysts has sparked a growing interest in accelerating redox kinetics of polysulfide and effectively restricting the “shuttle effect” in Li‐S batteries. In this work, a novel MXene‐supported ultrasmall Co 3 Fe 7 bimetallic alloy hybrids are fabricated via a one‐pot molten salt etching strategy. The Ti 3 AlC 2 precursor can be directly converted to Co 3 Fe 7 ‐MXene using this environmentally friendly approach, eliminating the need for acid/alkaline treatments and complex procedures. Meanwhile, the ultrasmall Co 3 Fe 7 alloy particles are in situ formed and tightly anchored on the MXene substrate. By simple coating, Co 3 Fe 7 ‐MXene modified separator functions as a barrier to effectively inhibit the shuttle effect. Furthermore, electrochemical tests and theoretical calculations demonstrate that Co 3 Fe 7 ‐MXene exhibits exceptional adsorption capacity and remarkable catalytic ability toward polysulfides, owing to the synergistic effect of bimetallic alloy. Consequently, Li‐S cells assembled with Co 3 Fe 7 ‐MXene modified separator achieve a high capacity, excellent rate performance, and superior cycle stability. This study provides a comprehensive insight into the design of MXene with bimetallic alloys as efficient electrocatalysts for LiPSs in high‐performance and long‐life Li‐S batteries.