Dual cross-linked cellulose-based hydrogel for dendrites-inhibited flexible zinc-ion energy storage devices with ultra-long cycles and high energy density.

Hydrogel electrolytes, renowned for their mechanical robustness and versatility, are crucial in ensuring stable energy output in flexible energy storage devices. This work presents a dual cross-linked cellulose-based hydrogel electrolyte with chemical cross-linking from covalent bonding and physical cross-linking from hydrogen bonding. This electrolyte demonstrated outstanding mechanical strength and porous structure with abundant hydroxyl groups, which facilitates the migration of Zn and suppresses the formation of undesirable zinc dendrite, thereby enhancing the ion conductivity (18.46 ± 0.39 mS cm at room temperature) and extending electrochemical stability window (0-2.23 V). Zn||Zn symmetric cells based on this electrolyte demonstrated stable stripping/plating cycles of 3000 h at a current density of 1 mA cm. Furthermore, the corresponding flexible zinc-ion hybrid capacitor retains a 90.3 % capacity over 100,000 cycles at 10 A g, while remaining functional across various folding angles. Hence, this biomass-derived hydrogel electrolyte holds promise for flexible energy storage device applications.