High‐Voltage Deep Eutectic Solvent Electrolyte with Fluorine‐Substituted Acetamide Additive for Aluminum‐ion Battery

Abstract The high‐voltage stability of electrolytes profoundly determines electrochemical reactions, which is still one of the major obstacles for developing advanced Al‐ion batteries (AIBs). Herein, a fluorine‐adjustment strategy is proposed to improve the high‐voltage stability of a low‐cost AlCl₃/acetamide (AcA) deep eutectic solvent electrolyte. By using a fluorine‐substituted AcA additive, the AlCl₃/AcA electrolyte exhibits a lifted oxidation onset potential from 2.21 to 2.78 V versus Al³⁺/Al. Based on a series of structural investigations, it is found that the additive can adjust the coordination configurations and improve the anti‐oxidation capability of electrolytes. Moreover, the additive induces an F‐rich interphase layer, which can stabilize the plating/stripping reactions of Al electrode with accelerated kinetics. Based on the optimized electrolyte, a high‐voltage Al–S battery relying on the S cationic redox shows good performance with little voltage fading for 300 cycles. This study provides important insights into the exploration of high‐performance and low‐cost electrolytes for AIBs.