Self-Reinforced Cathode Interface to Prolong the Cyclic Stability of Zn-MnO2 Batteries

Rechargeable aqueous zinc-ion batteries (RAZIBs) are attracting increasing attention due to their advantages in safety, cost, and energy density. However, the choice of electrode binders when using aqueous electrolytes faces many constraints, as nontoxic and low-cost hydrophilic binders, such as sodium alginate (SA), can lead to electrode damage due to excessive swelling in aqueous solution. Here, by employing double-network hydrogel electrolytes formed by poly(vinyl alcohol) and alginate, the content and activity of water molecules at the electrode–electrolyte interface are reduced, and the mechanical stability of the electrode is reinforced, thereby affording reliable protection to the cathode bonded with SA. The quasi-solid-state interface formed between SA and the gel electrolyte provides stable electrode architecture and smooth ion transport, thus enabling Zn||MnO2 cells to exhibit excellent electrochemical cycling performance even when using hydrophilic binders.