An Ultrahigh‐Modulus Hydrogel Electrolyte for Dendrite‐Free Zinc Ion Batteries

Abstract Quasi‐solid‐state aqueous zinc ion batteries suffer from anodic zinc dendrite growth during plating/stripping processes, impeding their commercial application. The inhibition of zinc dendrites by high‐modulus electrolytes has been proven to be effective. However, hydrogel electrolytes are difficult to achieve high modulus owing to their inherent high water contents. This work reports a hydrogel electrolyte with ultrahigh modulus that can overcome the growth stress of zinc dendrites through mechanical suppression effect. By combining wet‐annealing, solvent‐exchange, and salting‐out processes and tuning the hydrophobic and crystalline domains, a hydrogel electrolyte is obtained with substantial water content (≈70%), high modulus (198.5 MPa), high toughness (274.3 MJ m −3 ), and high zinc‐ion conductivity (28.9 mS cm −1 ), which significantly outperforms the previously reported poly(vinyl alcohol)‐based hydrogels. As a result, the hydrogel electrolyte exhibits excellent dendrite‐suppression effect and achieves stable performance in Zn||Zn symmetric batteries (1800 h of cycle life at 1 mA cm −2 ). Moreover, the Zn||V 2 O 5 pouch batteries display excellent cycling life and operate stably even under extreme conditions, such as large bending angle (180°) and automotive crushing. This work provides a promising approach for designing mechanically reliable hydrogel electrolytes for advanced aqueous zinc ion batteries.