Effects of Gd and Nd on microstructure, corrosion behavior, and electrochemical performance of Mg-Y-based anodes for magnesium air batteries

As-cast Mg-3Y-8Gd (VW83) and Mg-4Y-3(Gd/Nd) (WE43) alloys were used as anodes for Mg–air batteries in this study. The discharge behaviors of the anodes were investigated and compared with the anodes that made of AZ91D and MB15 alloys. The microstructure evolution, electrochemical behaviors, and surface morphologies after discharge were determined. The results indicate that the VW83 is an outstanding candidate for anode of Mg–air batteries, which has high cell voltage, stable discharge curves, good specific capacity, as well as excellent anodic efficiency. The VW83 anode exhibits the highest value of 54.11%, 1149.4 mAh g −1 , and 1088.4 mWh g −1 , respectively, for anodic efficiency, specific capacity, and energy, which are 12.94%, 15.90%, and 13.42% higher than that of WE43 anode. These excellent discharge properties are considered to be highly correlated to the Mg 5 Gd phase in VW83 anode. The amplified potential difference between the Mg 5 Gd and the α -Mg phase enhances the discharge activity of the anode. In particular, the tiny second phases in VW83 anode are beneficial for facilitating the self-peeling of discharge products by generating a so-called “layered structure” on the alloy surface during the discharge process. In addition, since Gd has a higher solid solubility in Mg than Nd, VW83 anode has the most negative self-corrosion potential (− 1.651 V) and lower R t (312.9 Ω cm 2 ) value while compared with WE43, AZ91D, and MB15 alloy anodes. In summary, both Gd and Nd are believed to play a positive role in improving the discharge properties of Mg–Y-based anode. What’s more, Gd plays a greater role than Nd. Graphical abstract