Insights into complexing effects in acetate-based Zn-MnO2 batteries and performance enhancement by all-round strategies

Aqueous Zn-MnO2 batteries with Mn2+/MnO2 conversion reaction have attracted enormous attentions in these years, in which the proposal of acetate-based electrolyte further boosts the redox chemistry and achieves the two-electron reaction with mitigated anode corrosion. However, the lower redox potential, the generation of dead MnO2, and MnO2 suspension in acetate-based Zn-MnO2 batteries inhibit their commercialization. Herein, the acetate-based electrolyte is optimized by introducing electrolyte modification and manageable Cr2+/Cr3+ reaction, contributing to higher cathodic potential and longer lifetime. Additionally, the dead MnO2 with incompact morphology is found to facilitate the further deposition in the initial stage. Based on the above discussions, we proposed the all-round optimizations, which additionally include a pre-cycling process and a simple ultrasonic treatment, achieving a triple lifetime and the record-large accumulated capacity of 10 Ah cm−2 with the power density higher than 75 mW cm−2. Moreover, the sources of the above issues and their relations to complexing effects are elaborated. This work may be instructive and pioneering for the future development of complexes-based Zn-MnO2 batteries.