Improving the electrochemical behaviors and discharge performance of as-rolled Mg-4Li alloys through multicomponent alloying

Abstract

The effects of microalloying on the microstructure, electrochemical behavior and discharge properties of as-rolled Mg-4Li alloys are investigated. The addition of Al and Y elements result in the regulation of grain size and second phase, and a significant increase in corrosion resistance. Conversely, the Si element is detrimental to the corrosion resistance due to the more negative potential of the Mg2Si phase. The oxidation products mainly consist of Mg(OH)2 and Li2CO3, which effectively protect the substrate. The Mg2Si phase crack during the discharge process, effectively weakening the adsorption effect of the discharge product layer with the substrate and optimizing the material discharge activity. Compared with L4 (Mg-4Li) anode, LASW4310 (Mg-4Li-3Al-1Si-0.5Y) anode has a lower self-corrosion rate (15.71 mm/year). At the same time, LASW4310 anode has a high discharge capacity and anode efficiency of 1333 mAh.g−1 and 57.78%, and provides a specific energy of up to 1504 mWh.g−1. The refined microstructure and dense surface film can effectively slow down the corrosion and “chunk effect” of the substrate. The smooth discharge surface also facilitates the detachment of the discharge products from the substrate.