Cryoprotective Hydrogel Electrolyte With Dynamic Hydrogen Bonds for All‐Climate Zinc–Iodine Batteries

ABSTRACT Aqueous zinc–iodine batteries (AZIBs) possess significant potential for energy storage owing to their high theoretical capacity and remarkable cycling stability. Nevertheless, their practical deployment is severely constrained by a shortened life resulting from uncontrollable parasitic reactions and poor temperature adaptability. Herein, we design a multifunctional dual‐network hydrogel electrolyte PHEAA‐CMC‐ Zn(CF 3 SO 3 ) 2 (HCZ) composed of rigid carboxymethyl cellulose (CMC) and flexible poly (N‐hydroxyethyl acrylamide) (PHEAA) featuring abundant dynamic intra/intermolecular hydrogen bonds. Intriguingly, the rich hydrophilic groups in the electrolyte form hydrogen bonds with water molecules, effectively regulating water‐induced side reactions at the electrode–electrolyte interfaces and enabling excellent temperature tolerance across a wide range from −30°C to 50°C. Moreover, the polar amide groups and oxygen‐containing functionalities within the hydrogel can coordinate with Zn 2+ to promote Zn 2+ migration at the anode, while simultaneously providing electrostatic adsorption of polyiodide species to mitigate the shuttle effect at the cathode. Therefore, Zn‖Zn symmetric cells equipped with this engineered electrolyte exhibit prolonged cycling stability exceeding 3000 h at both 20 and −30°C. Moreover, AZIBs with this hydrogel deliver long‐term cycling durability over 20 000 cycles at −30°C and 30 000 cycles at 50°C. This electrolyte provides new insights for AZIBs capable of stable operation across broad temperature.