The influence of Sn content on the electrochemical performance and discharge characteristics of Al-0.2Mg-0.02In-xSn-0.02Bi alloy anodes in aluminum-air batteries

This study examines the impact of varying Sn content on the microstructure, electrochemical performance, and discharge characteristics of the Al-0.2 Mg-0.02In-xSn-0.02Bi aluminum anode in an alkaline electrolyte. The purpose of this study is to examine the best quantity of Sn element addition to enhance the discharge performance of aluminum alloy anodes. The study utilized scanning electron microscopy (SEM), EPMA to analyze the characteristics of the alloy’s secondary phase and the morphology of corrosion. In addition, the electrochemical performance and discharge properties of the alloy anode were assessed using various methods, including self-corrosion rate, open-circuit potential, potentiodynamic polarization, alternating current impedance, and constant current discharge tests. Incorporating Sn elements, where Sn atoms are dissolved in the aluminum matrix, results in a significant increase in the overpotential for hydrogen evolution. This leads to a reduction in self-corrosion rates and an improvement in discharge performance. Nevertheless, as the tin (Sn) content rises, the greater amount and larger size of tin-rich phases create galvanic cells with the aluminum matrix, resulting in higher rates of self-corrosion and reduced discharge performance. When the Sn content in the alloy anode is 0.03%, the overall performance is optimal. Its anode utilization rate and energy density are 91% and 4213 mWh g⁻¹ (at 50 mA cm⁻²), respectively. Compared to the Sn-free aluminum alloy anode, they have been improved by 33.6% and 1626 mWh g⁻¹, respectively.