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

Abstract The liquid electrolyte in conventional zinc/manganese dioxide (Zn/MnO 2 ) batteries conduces to the capacity limitation of one‐electron redox from MnO 2 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 MnO 2 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 MnO 2 /Mn 2+ 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 Mn 2+ addition in the electrolyte. More importantly, fibrous Zn/MnO 2 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.