Activating discharge and inhibiting self-corrosion by adding indium to the anode of Mg–air battery

Self-corrosion and low practical voltage of anodes severely limit the usage of Mg-air batteries. Although many elements, including indium (In), have been used to enhance the discharge characteristics of Mg anodes, unclear mechanism of the action of a single element and lack of research on binary alloys as anodes have restricted the development of Mg-air batteries. Herein, Mg-<i>x</i>In (<i>x</i> = 0.5, 1, 2, 4) alloys were melted as anode materials for Mg-air batteries. The In element in the Mg-In binary alloy activated the discharge process of the anode and inhibited self-corrosion and chunk effect, thereby greatly improving the voltage and anodic efficiency of the batteries. Mg-air batteries assembled from Mg-1In anode reached voltages exceeding 1.5 V at low current density and over 1.1 V even at 40.0 mA cm^-2. The Mg-1In anode exhibited a discharge efficiency greater than 63.2% at all current densities and demonstrated a peak specific energy of 2100.2 mW h g^-1. Furthermore, the Mg-1In anode performed well in long-term, intermittent, and constant-power discharges. The simple design of binary alloy and the activation and inhibition mechanisms of the In element provide a new avenue for Mg anode development.