Effect of Lithium on the Discharge and Corrosion Behavior of Mg-3 wt.% Al Alloy as the Anode for Seawater Activated Battery

The discharge and corrosion behavior of Mg-3 wt.% Al alloys added with different contents of lithium in 3.5 wt.% NaCl aqueous solution is studied by electrochemical methods and microstructure characterization. The results indicate that adding 4 wt.% lithium severely promotes the self-corrosion and the addition of 12 wt.% lithium is not valuable to the spalling of discharge products. In contrast, doping Mg-3 wt.% Al with 8 wt.% lithium negatively shifts the discharge potentials and inhibits the self-discharge, attributed to the dual-phase structure of α-Mg plus β-Li that removes the discharge products and favors the uniform dissolution in the course of discharge. Moreover, the multi-pass rolling with 40% reduction could tailor the microstructure of Mg-3 wt.% Al-8 wt.% Li alloy and further enhance its discharge activity, even though the corrosion resistance is slightly reduced. This means that the rolled Mg-3 wt.% Al-8 wt.% Li sheet is suitable to serve as the anode for seawater activated battery.