Elucidating the dependence of electrochemical behavior and discharge performance on the grain structure of lean Mg-0.3Bi-0.3Ag-0.3In anodes in primary Mg-air battery

In this work, the role of grain structures in tailoring the electrochemical behaviors and discharge performances of extruded lean Mg-0.3Bi-0.3Ag-0.3In (wt.%) alloys with different extrusion ratios (ER) of 9 and 36 is systemically investigated. Results indicate the ER9 sample exhibits a typical bimodal microstructure comprising equiaxed grains and elongated deformed grains, whereas the ER36 sample shows a fully dynamic recrystallized grain structure. The fine-equiaxed grain structure with low kernel average misorientation and texture intensity values in the ER36 anode is conducive to increase the kinetics of anode dissolution and promote the formation of loose and thin discharge products layer, resulting in a higher and steadier cell voltage. The Mg-air battery assumed by the ER36 anode presents a high cell voltage, considerable anodic efficiency, and specific energy of 1.3676 V, 60.63%, and 1807.79 mW h g(-1) respectively, at 10 mA cm(-2), which are attributed to the even dissolution of the anode as well as the suppression of the chunk effect and hydrogen evolution, thereby making the ER36 alloy as a potential anode material for primary Mg-air batteries.