Regulating Ion Migration and Deposition Through a Cellulose Hydrogel Electrolyte Enabled by Anion‐Reinforced Effect for Zinc‐Ion Batteries

Abstract Polysaccharide‐based hydrogel electrolytes have tremendous advantages in addressing the intractable issues faced by aqueous zinc‐ion batteries, i.e., uncontrollable Zn dendrites, hydrogen evolution reaction, and corrosion, owing to their dynamic 3D hydrogen bonding network and high water content. However, these hydrogel electrolytes suffer from inferior mechanical properties and ionic conductivity. Herein, a sustainable dual‐crosslinked cellulose hydrogel electrolyte is developed that enhances mechanical strength and ionic conductivity through a reconstructed hydrogen‐bonding network. Inspired by the anion‐reinforced effect, SO 4 2− effectively captures bound water molecules within the cellulose network, promoting intermolecular hydrogen bonding and thus improving mechanical properties. Additionally, the SO 4 2− ‐mediated cellulose network structure with abundant strong anion‐H bonds facilitates rapid ion transport to realize the reversible Zn plating/stripping by homogenizing Zn 2+ flux, thus effectively inhibiting the Zn dendrites growth and eliminating side reactions. Consequently, the hydrogel electrolyte demonstrates reversible plating/stripping performance in Zn//Zn symmetric cells, achieves a reversible capacity of 194.3 mAh g −1 at 2 A g −1 after 2000 cycles, in Zn//MnO 2 batteries, and renders the flexible pouch cells with stable cycling under harsh conditions. Furthermore, this biodegradable cellulose‐based hydrogel electrolyte presents promising prospects for the development of green batteries, paving the way for sustainable hydrogel electrolytes in flexible and wearable devices.