Corrosion and discharge behavior of Mg−Zn−Mn−Nd alloys as primary Mg−air batteries anode

Abstract

The optical microscopy, X-ray diffraction, scanning electron microscopy equipped with energy dispersive spectrometry, electrochemical tests and galvanostatic discharge tests were employed to characterize the microstructure, corrosion resistance and discharge performance of the as-extruded and solution-aged Mg−6Zn−Mn−xNd (ZM61, x=0, 0.2, 0.6, 0.8, 1.0, wt.%) alloys. The results indicate that the micro-alloying with Nd can promote the grain refinement of ZM61 alloys, and the as-extruded and solution-aged ZM61−0.6Nd alloys have the best corrosion resistance and discharge performance. However, the heat treatment deteriorates the comprehensive performance of as-extruded alloys. Among all the investigated alloys, the corrosion current density of the as-extruded ZM61−0.6Nd alloy is 1.611×10−5 A/cm2, and the discharge potentials are −1.517 and −1.336 V vs SCE at current density of 1 and 10 mA/cm2, respectively, during long-time discharge up to 24 h with the anode efficiency of above 36%, which shows the best comprehensive performance. The good discharge performance can be attributed to the improvement of corrosion resistance and cracking effect of the discharge products.