Three-dimensional dendrite-free and anti-corrosion aluminum foam anode via hetero-metallic bismuth interface engineering for high-performance aqueous batteries.

Metallic aluminum (Al) is a promising anode material for rechargeable aqueous batteries due to its abundance, low cost, and high theoretical capacity (8056 mAh cm-3). However, the practical application of aqueous Al metal batteries faces significant challenges, including side reactions such as self-corrosion, passivation, and hydrogen evolution reaction (HER), as well as irreversible Al plating/stripping and dendrite growth. To address these issues, we propose a strategy involving the modification of conventional planar Al foil anodes into three-dimensional (3D) Al foam structures, which can effectively modulate the Al3+ flux during plating/stripping. Furthermore, the introduction of a Bi metal layer onto the 3D Al foam (denoted as 3D Al/Bi) can inhibit the HER side reaction, reduce the Al electrodeposition nucleation potential energy barrier, and suppress dendrite growth. As a result, the 3D Al/Bi foam anode exhibits a low Al plating/stripping overpotential of approximately 150 mV, an extended cycling lifespan of around 800 h, and a high average Coulombic efficiency of 95.6%. Moreover, a fabricated Al/Bi||MnO₂ pouch cell demonstrated excellent electrochemical performance, retaining 89% of its initial capacity after 200 cycles at a current density of 200 mA g-1. The pouch cell also exhibited remarkable flexibility and mechanical robustness, maintaining stable performance without short-circuiting or combustion even when bent at 90° and 180°. These results highlight that 3D Al/Bi foam electrodes offer a promising alternative to conventional aluminum anodes in AAIBs, potentially enabling the development of high-performance aluminum-based energy storage systems.