Investigation into the Effect of Bismuth Addition on the Discharge Behavior of Al-Mg-Sn-Ga-Based Alloy Anodes in Al-Air Batteries with NaOH Electrolyte

This study investigates the effects of bismuth (Bi) addition on the discharge behavior of Al-Mg-Sn-Ga-based alloy anodes in NaOH electrolyte through self-corrosion tests, electrochemical measurements, full-cell evaluations, and surface morphology analysis. The results demonstrate that an optimal Bi content (0.10%) significantly enhances the high current density performance of aluminum-air batteries by refining grains and forming Bi precipitates, which balance corrosion uniformity and reaction activity. Excessive Bi (≥0.25%) or trace Bi (0.05%) induces grain coarsening. Specifically, trace Bi promotes segregation of Bi precipitates at corrosion cracks, triggering uneven intergranular corrosion, while excessive Bi leads to localized aggregation of Bi precipitates in corrosion pits, forming galvanic corrosion cells that degrade battery efficiency. Discharge tests reveal that the alloy achieves a capacity density of 2768.17 mAh g⁻¹ and an energy density of 3393.77 mWh g⁻¹ at a high discharge current density (80 mA cm⁻²), with an anode utilization rate of 92.89%. The developed aluminum alloy demonstrates promising potential as a high-performance anode material for aluminum-air batteries, meeting the demands of high-power/energy applications.