Precise Proton Redistribution for Two‐Electron Redox in Aqueous Zinc/Manganese Dioxide Batteries

Abstract

AbstractThe liquid electrolyte in conventional zinc/manganese dioxide (Zn/MnO2) batteries conduces to the capacity limitation of one‐electron redox from MnO2 to MnOOH, as well as undesired Mn loss with capacity deterioration. Herein, to conquer these challenges, a new idea is proposed on the precise proton redistribution in the hydrogel electrolyte for the preferred two‐electron redox reaction. Specifically, an acidic layer in the hydrogel adjoins the MnO2 cathode to maintain the two‐electron redox, a neutral layer adjoins the zinc anode to inhibit the dendrite growth, which is separated by a mildly alkaline layer to immobilize the proton distribution. The two‐electron redox of MnO2/Mn2+ and anode protection are demonstrated to play key roles in battery performance. Such a battery presents specific capacities of 516 mA h g−1 at 0.05 A g−1, as well as a capacity retention of 93.18% at 5 A g−1 after 5000 cycles without extra Mn2+ addition in the electrolyte. More importantly, fibrous Zn/MnO2 batteries using the tri‐layer electrolyte can sustain 2000 cycles with high initial capacity of 235 mAh g−1 at 1 A g−1. After 6000 times folding in 180°, it can maintain 99.54% capacity. When integrated into user's clothing or portable accessories, the fibrous battery is demonstrated as a great potential in wearable electronics.