Corrosion and discharge properties of Ca/Ge micro-alloyed Mg anodes for primary aqueous Mg batteries

Abstract

Ge is evaluated as a micro-alloying element for newly-developed Mg-Ca anodes. The combination of Ca/Ge is effective for suppressing cathodic HER kinetics, resulting in highly negative OCP and a low corrosion rate (0.2 mm y–1). For air battery, Mg-0.1 %Ca-0.1 %Ge (wt%) anode exhibits similar voltage to Mg-0.1 %Ca in NaCl solution, but the highly negative OCP enables it with enhanced voltage in salicylate-containing electrolyte (1.7 V at 1 mA cm–2 versus 1.63 V of Mg-0.1 %Ca). Beside, all micro-alloyed Mg-Ca, Mg-Ge and Mg-Ca-Ge anodes show similar self-discharge rates and high utilization efficiency (∼60 % at 10 mA cm–2).