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 2+ and suppresses the formation of undesirable zinc dendrite, thereby enhancing the ion conductivity (18.46 +/- 0.39 mS cm-1 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-2 . Furthermore, the corresponding flexible zinc-ion hybrid capacitor retains a 90.3 % capacity over 100,000 cycles at 10 A g-1 , while remaining functional across various folding angles. Hence, this biomass-derived hydrogel electrolyte holds promise for flexible energy storage device applications.