The Origin of Capacity Degradation and Regulation Strategy in Aqueous Zn-MnO 2 Battery with Manganese Acetate

Abstract

MnO 2 -based rechargeable aqueous zinc-ion batteries (ZIBs) have attracted wide attention as the next-generation large-scale, safe energy storage technology. However, the capacity decay process of Zn-MnO 2 batteries remains poorly understood because of the complicated reaction mechanism, which may lead to incorrect interpretations and methods to improve the cycle stability. In this study, the capacity decay mechanism was demonstrated for Zn-MnO 2 batteries with manganese acetate as an electrolyte additive. It is found that zinc hydroxide sulfate has a beneficial effect on the battery capacity, but the product ZnMn 3 O 7 ·2H 2 O being converted from basic zinc sulfate is an irreversibility inert material and leads to a rapid capacity fading. Notably, with the increased low cutoff voltage (1.0 to 1.35 V), it exhibited a high capacity of 231 mA h g −1 at 200 mA g −1 and an excellent stability of 90.11% retention after 1000 cycles at 1000 mA g −1 . Our results of the reaction mechanism and the strategy provide a new perspective for the development of fundamental science and applications for Zn-MnO 2 battery.