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 Al³⁺ migration process, thereby facilitating homogeneous Al³⁺ 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.