The corrosion and discharge behavior of high-performance Mg-7Li-1Y alloy as anode for Mg-air batteries

Abstract

In this work, the microstructure, corrosion resistance and discharge properties of the as-extruded Mg-7Li-1Y alloy are systematically studied. The results show that the as-extruded Mg-7Li-1Y alloy is mainly composed of the α-Mg and β-Li phases with an obvious bimodal microstructure. Although the as-extruded Mg-7Li-1Y alloy exhibits relatively poor corrosion resistance with the impedance value of only 163.68 Ω·cm2 and the corrosion current density of 9.5 × 10−5 A/cm2 in 3.5% NaCl solution, it possesses an outstanding discharge performance with a discharge voltage of 1.35 V and a high anode utilization rate of 59% at the current density of 10 mA/cm2. Meanwhile, it has a high specific energy density with about 1870 mWh·g−1 at the current density of 10 mA/cm2. The analysis indicates that the β-Li phase, low hydrogen evolution reaction and the unique morphologies of discharge products are responsible for the improvement of the electrochemical activity and the discharge performance of the Mg-7Li-1Y alloy.