Electrochemical behavior and discharge performance of Al-1Zn-0.4Mn-0.1Sn-xBi as anode alloys for Al-air battery in KOH solution

Al-1Zn-0.4Mn-0.1Sn-xBi (x = 0, 0.5, 0.10, 0.15, 0.20) alloys are prepared as anode materials in alkaline Al-air batteries by adding alloying elements to low-cost commercial purity aluminum to investigate their electrochemical behavior and discharge performance. The results show that among the five alloys, Al-1Zn-0.4Mn-0.1Sn-0.15Bi alloy has the best comprehensive corrosion resistance and discharge performance in 4 M KOH electrolyte at room temperature. Specifically, Al-1Zn-0.4Mn-0.1Sn-0.15Bi has the most negative corrosion potential of −1.484 V and the smallest corrosion current density of 42.80 mA cm⁻², which can be attributed to the largest protective film impedance. The hydrogen evolution rate of this alloy is as low as 0.244 ml cm⁻² min⁻¹. Upon discharge at a current density of 60 mA cm⁻², this anode alloy achieves an anode efficiency of 89.20 % and a specific capacity of 2656 Ah kg⁻¹. Furthermore, when the discharge current density is further increased to 90 mA cm⁻², it can still maintain a stable discharge at a high cell voltage of 1.01 V, and the power density reaches 90.9 mW cm⁻². Therefore, Al-1Zn-0.4Mn-0.1Sn-0.15Bi can be considered as a suitable anode alloy for high-power-density discharge in Al-air batteries.