Carboxylic Acid‐Functionalized Cellulose Hydrogel Electrolyte for Dual‐Interface Stabilization in Aqueous Zinc‐Organic Batteries

Aqueous zinc batteries (AZBs) are considered one of the most promising candidates for grid-scale energy storage. However, achieving a stable electrode-electrolyte interface remains a challenge for developing high-performance AZBs. Herein, taking the Zn||phenazine (PNZ) system as a prototype, where the proton uptake/removal mechanism dominates in the cathode, a carboxylic acid-functionalized cellulose hydrogel electrolyte is designed to simultaneously solve the issues at both the anode and cathode interfaces. Specifically, the hydrogel electrolyte can not only regulate Zn²⁺ ions at the Zn anode side but also supply H⁺ ions at the PNZ cathode side to avoid the unfavored deposition of zinc sulfate hydroxides. Benefiting from the unique one-gel-for-two-electrodes strategy, the dendrite-free and side reaction-suppressed aqueous Zn||PNZ cells are developed with a high specific capacity (311 mAh g^-1, 99% utilization of the theoretical capacity) and a long cycle life (over 1500 cycles within 2 months). This study proposes a facile and low-cost electrolyte strategy for stabilizing AZBs.