The electrochemical behaviors of the Mg-7.5Li-3.5Al and Mg-7.5Li-3.5Al-1Y electrodes in sodium chloride solution

Abstract

Mg-7.5Li-3.5Al and Mg-7.5Li-3.5Al-1Y alloys are prepared, and their electrochemical performances are investigated by potentiodynamic polarization, potentiostatic current-time curves, electrochemical impedance spectroscopy, scanning electron microscopy (SEM), varying load performances, and utilization efficiencies. The performances of the Mg-H2O2 semi-fuel cells with the above alloy anodes are also determined. It is found that the Mg-7.5Li-3.5Al-1Y electrode has higher discharge activity and better corrosion resistance than Mg-7.5Li-3.5Al electrode in 0.7 mol L−1 NaCl solution. SEM studies indicate that the alloying element Y prevents the formation of dense oxide film on the alloy surface and facilitates peeling off of the oxidation products. The utilization efficiencies of the alloys increase in the order: Mg-7.5Li-3.5Al < Mg-7.5Li-3.5Al-1Y. The Mg-H2O2 semi-fuel cell with Mg-7.5Li-3.5Al-1Y alloy as the anode presents a maximum power density of 92 mW cm−2 at room temperature, which is higher than that with Mg-7.5Li-3.5Al anode (85 mW cm−2). Y is a “promotion element” in the alloy, and the Mg-7.5Li-3.5Al-1Y alloy electrode exhibits better performances comparing to the Mg-7.5Li-3.5Al alloy electrode.