Discharge Properties and Electrochemical Behaviors of Mg-Zn-xSr Magnesium Anodes for Mg–Air Batteries

In this work, the electrochemical and discharge properties of Mg-Zn-<i>x</i>Sr (<i>x</i> = 0, 0.2, 0.5, 1, 2, and 4 wt.%) alloys used as anodes for Mg-air batteries were systematically studied via microstructure characterization, electrochemical techniques, and Mg-air battery test methods. The addition of Sr refines the grain size, changes the composition and morphology of the passivation film and discharge products, and enhances the electrochemical properties of the alloy. Excessive Sr addition breaks the grain boundaries and precipitates a large number of Sr-rich phases, resulting in microgalvanic corrosion and the 'chunk effect'. The anode efficiency of Mg-Zn-1Sr is the highest at a current density of 10 mA cm^-2, reaching 61.86%, and the energy density is 2019 mW h g^-1. Therefore, Sr is a microalloying element that can optimize the electrochemical performance of Mg-air battery alloy anodes.