A Bismuth Surface Layer Enables Uniform Aluminum Electrodeposition for Reversible Aluminum Metal Anodes

Metallic aluminum (Al) is an attractive anode material for Al‐ion batteries owing to its high theoretical capacity and low cost. However, Al metal anodes suffer from surface passivation, dendrite growth, and parasitic reactions, hindering the practical applications of Al‐ion batteries. Herein, a modified Al metal anode with a bismuth (Bi) artificial surface layer (Bi@Al) is developed by a facile in‐situ substitution reaction method. The Bi layer accelerates the desolvation, nucleation, and Al 3+ migration process, thereby facilitating homogeneous Al 3+ distribution and rapid Al plating/stripping. Therefore, the modified Al metal anode achieves high reversibility and stability even under high current densities and capacities. As a result, Bi@Al symmetric cells exhibit a lifespan over 500 h at 10 mA cm −2 and 10 mAh cm −2 . Furthermore, combined with the graphite cathode, the Bi‐modified Al metal full cell delivers a capacity of 80.1 mAh g −1 after 1000 cycles at 1.0 A g −1 . This work provides a valuable method to modify the Al metal anode for developing high‐performance non‐aqueous Al‐ion batteries.