Effect of Al Content on Corrosion and Discharge Properties of Extruded Mg-Al-Ca-Mn Alloys as Anode Material for Mg-air Batteries

The effect of Al content on the corrosion behavior and electrochemical performance of extruded Mg-Al-Ca-Mn alloy in 3.5%NaCl electrolyte was investigated. The results show that the AMX411 Mg-alloy exhibits excellent corrosion resistance and discharge performance. The measured hydrogen evolution results showed that the minimum hydrogen evolution and mass loss of AMX411 alloy during corrosion process for 72 h were (2.25 ± 0.07) mL·cm-2 and (2.83 ± 0.12) mg·cm-2, while the free corrosion potential (φcorr) and the corrosion current density (Jcorr) were -1.267 V and (67.9 ± 0.16) µA·cm-2 respectively, indicating its low electrochemical activity and best corrosion resistance. In addition, the results of a half-cell discharge test for 4 h revealed that AMX411 alloy maintained a negative and stable voltage regardless of the discharge current densities (5, 10, 20, and 30 mA·cm-2), and its discharge efficiency was as high as 61.36% and 65.35% at current densities 20 and 30 mA·cm-2, which was significantly better than that of AMX111 alloy (41.83% and 44.79%). The excellent performance of AMX411 alloy may be attributed to the existence of much smaller and uniformly distributed precipitations of Al-containing second phase, which effectively reduces the local potential difference and suppresses the micro galvanic corrosion effect, thus facilitating the best corrosion resistance, besides, it still exhibits high anode utilization under high current density, which are all favorable advantages for it to become the anode material for Mg-air batteries. © 2025 Chinese Journal of Materials Research. All rights reserved.