Discharge performance of Mg-Y binary alloys as anodes for Mg-air batteries

In this work, the electrochemical properties and discharge performance of Mg-xY (x = 0, 0.5, 1, 2, 3, and 5 wt.%) binary alloys have been systematically investigated as anodes for Mg-air batteries, using electrochemical techniques and Mg-air battery tests. The results reveal that the Mg24Y5 and Y-rich phases in Mg-Y alloys play the micro-cathode and micro-anode roles, respectively. By adding a small amount of Y (0.5 and 1 wt.%), the electrochemical activity of the anode can be effectively enhanced, and hydrogen evolution during discharge can be inhibited. Among the investigated anodes, the Mg-1Y anode possesses the highest discharge voltage at all current densities. The Mg-0.5Y anode exhibits excellent comprehensive discharge performance, with the highest anodic efficiency, specific capacity, and energy density of 63%, 1376 mAh·g − 1, 1899 mWh·g − 1 at 10 mA·cm−2, respectively. The discharge voltage and anodic efficiency decrease as the Y content increase further, attributed to the excessive second phases accelerating the self-corrosion and causing the "chunk effect".