The effect of lithium content on the discharge and electrochemical performance of Mg–Li–Zn–Y alloys for primary Mg–air batteries†

Abstract

In this work, the microstructure, corrosion resistance, and discharge performance of two hot-extruded Mg alloys with different lithium contents were thoroughly investigated. The electrochemical performance of the Mg anode is closely related to its microstructure. The Mg–11Li–6Zn–2Y (ML11) alloy, primarily composed of a singular β-Li phase and smaller, fewer W phases, enables uniform discharge reactions in magnesium–air batteries (Mg–air batteries), thereby significantly suppressing the “chunk effect”. Moreover, the Li₂CO₃ film formed in the discharge products helps inhibit the hydrogen evolution side reaction. In contrast, the Mg–8Li–6Zn–2Y (ML8) alloy is mainly composed of α-Mg and β-Li phases, with larger and more numerous W phases, resulting in inferior discharge performance. Battery tests indicate that the ML11 anode has a discharge voltage of 1.211 V, an anode utilization rate of 62.6%, and a high specific energy density of 1727 mW h g⁻¹ at a current density of 20 mA cm⁻². This study provides a new perspective for the development of anode materials for Mg–air batteries.