Scalable production of hydrogen evolution corrosion resistant Zn-Al alloy anode for electrolytic MnO2/Zn batteries

Abstract

Electrolytic MnO2/Zn battery has attracted significant attention for large-scale energy storage due to its advantages of high energy density and low cost. However, the acidic electrolyte used to maintain the Mn2+/MnO2 chemistry causes severe and irreversible hydrogen evolution corrosion (HEC) on the Zn anode. Herein, we present a scalable, metallurgical Al alloying approach to mitigate the HEC of Zn and prolong the battery's cycle life. Through various in situ and ex situ characterizations, it is demonstrated that the HEC on Zn-Al alloy electrode is effectively inhibited in the acidic electrolyte with and without the electric field effect. The outstanding anti-HEC capability of the Zn-Al alloy anode enables the electrolytic MnO2/Zn-Al battery with a high discharge voltage of more than 1.9 V at 1 C, a more stable cycle performance, and an enhanced cycle life comparing with the MnO2/Zn battery. Meanwhile, the experimental and COMSOL simulation results also reveal that the preferential but with slow corrosion speed of Al matrix in Zn-Al alloy is the key factor to improve the anti-HEC capability. This work exhibits the practicality of alloying strategy to produce scalable and robust Zn alloy anodes for the electrolytic MnO2/Zn battery in the large-scale energy storage field.