Highly Impact‐Resistant and Anti‐Freezing Hydrogel Electrolyte for Flexible Supercapacitors

ABSTRACT Conventional hydrogel electrolytes, limited by their molecular network design, fail to meet the comprehensive requirements for both mechanical stability and electrochemical performance at low temperatures for flexible energy storage. Herein, we design a dynamically cross‐linked hydrogel electrolyte based on polyvinyl alcohol and hyperbranched polysaccharide via synergistic molecular network regulation strategies, including co‐nonsolvency effect, freeze‐induced crystallization, and a dual‑salt salting‑out effect. The resulting material achieves exceptional performance across impact resistance, freezing resistance, and ionic conductivity. The hydrogel withstands high‑strain‑rate impacts up to 10000 s −1 , achieving an impact stress of 675.94 MPa and a toughness of 200.96 MJ m −3 , which is attributed to its dynamically cross‑linked network and nanocrystalline domains. The incorporation of a dual‐salt system endows the material with exceptional freezing resistance, retaining a high tensile toughness of 16.04 MJ m −3 even at −80°C. Moreover, the optimized hydrogel electrolyte retains a considerable ionic conductivity of 1.12 mS cm −1 at −60°C, enabling a supercapacitor with a 1.8 V operating window and 94.6% capacitance retention over 10 000 cycles under the same harsh condition. This work therefore presents a distinct strategy and design pathway for developing safe and reliable flexible energy storage devices capable of operating under extreme conditions.