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

AbstractThe 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 Co3Fe7 bimetallic alloy hybrids are fabricated via a one‐pot molten salt etching strategy. The Ti3AlC2 precursor can be directly converted to Co3Fe7‐MXene using this environmentally friendly approach, eliminating the need for acid/alkaline treatments and complex procedures. Meanwhile, the ultrasmall Co3Fe7 alloy particles are in situ formed and tightly anchored on the MXene substrate. By simple coating, Co3Fe7‐MXene modified separator functions as a barrier to effectively inhibit the shuttle effect. Furthermore, electrochemical tests and theoretical calculations demonstrate that Co3Fe7‐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 Co3Fe7‐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.