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.