Proton Self‐Limiting Effect of Solid Acids Boosts Electrochemical Performance of Zinc‐ion Batteries

At present, aqueous rechargeable Zn–MnO2 batteries have attracted widespread attention as green potential application for renewable energy storage devices. MnO2 cathode has great potential for application, but its proton reaction results in side reactions of cathode, electrolyte consumption, and dramatic pH value changes, suffering from capacity degradation. To address the issues caused by proton deficit, a proton–limited domain strategy is proposed by integrating solid acids (Sulfonic acid type polystyrene–divinylbenzene, SATP) with proton exchange reactions into MnO2. SATP can act as a new proton source increasing the amount of H+ and reducing the generation of zinc hydroxide sulfate, by–product of proton at the cathode interface, via proton exchange reactions of ‐HSO3– group. As a result, Zn–MnO2/SATP battery delivered with excellent rate performance (218.4 mAh g–1 at 2 A g–1) and high cycling stability (the retained capacity of 115.8 mAh g–1 after 500 cycles at a current density of 1 A g–1. This work provides an innovative strategy for high performance aqueous Zn–MnO2 batteries. SATP employs the ion exchange reaction of sulfonic acid ions on their surface to reversibly adsorb and desorb protons. This process effectively restricts the partial proton reaction of manganese dioxide at the surface interface. SATP can substitute some zinc ions, supplying protons for the electrochemical reaction of MnO2 and reducing the generation of the byproduct ZHS. As a result, SATP significantly enhances the rate performance, cycle stability, and electrochemical reaction kinetics of zinc manganese batteries through its self‐limiting domain effect.