Reconfigurable Poly(Ionic Liquid) Hydrogel Electrolytes for Ultrawide‐Temperature, Damage‐Tolerant Hybrid Supercapacitors

Hydrogel electrolytes for flexible energy storage devices commonly suffer from limited temperature tolerance and irreversible damage in chemical cross‐linked networks. Herein, a hydroxyl‐functionalized poly(ionic liquid) hydrogel electrolyte (M‐C/HIL‐PAM) is synthesized via one‐step γ‐ray‐induced copolymerization of acrylamide and 1‐(2,3‐dihydroxypropyl)‐3‐vinylimidazolium chloride in an aqueous NaClO 4 /Mg(ClO 4 ) 2 solution. Reversible hydrogen bonding and electrostatic interactions from hydroxyl and imidazolium groups create a dynamically reconfigurable network, endowing high toughness (tensile strength ~390 kPa, elongation at break ~2025%), strong adhesion, and efficient self‐healing. Meanwhile, the synergistic hydration effect of Na + and Mg 2+ disrupts the hydrogen‐bond network of water molecules, enabling stable ion transport at −70 to 60 °C. Benefiting from these properties, the resulting activated carbon || δ‐MnO 2 hybrid supercapacitor fabricated by in situ radiation polymerization operates across this wide temperature range. The device exhibits no capacity decay after 2000 cycles at −60 °C, retains good performance after 5000 cycles at room temperature and 60 °C, and withstands 3000 bending cycles without significant loss. Furthermore, the pouch supercapacitor shows negligible capacity decay after physical damage and rejoining, demonstrating intrinsic self‐healing ability. This work offers a promising strategy for designing wide‐temperature, mechanically robust, and self‐healable hydrogel electrolytes for flexible energy storage devices under extreme conditions.