Revealing the impact of microstructure on corrosion and discharge behaviors of Mg-1Er alloy anodes for Mg-air batteries

Developing magnesium (Mg) alloy anodes with high discharge activity and controlled self-corrosion has high significance for Mg-air batteries. Microstructural optimization of the alloy anode is a straightforward strategy to enhance the discharge performance. In this study, we investigated the corrosion and discharge behaviors of extruded Mg-1Er (wt%) alloy anodes with varying microstructural features. Our results indicate that the Mg-1Er alloy with (10−10) and (11−20) orientated grains exhibits higher surface electrochemical activity than (0001) orientated grains, which are more prone to corrosion, whereas they exhibit better performance. The small grain size implies a large number of grain boundaries distributed on the surface, which can improve the surface electrochemical activity, but also reduce the corrosion resistance. Mg-1Er (TS) alloy machining along the vertical extrusion direction exhibits superior discharge performance with a discharge voltage of 1.333 V and an anodic efficiency of 51.9 % at 10 mA/cm². This is attributed to the high surface electrochemical activity and the facile shedding of discharge products.