Phase‐Behavior‐Driven Hydrogen‐Bond Engineering Enables Temperature‐Resilient Fibrous Zinc‐Ion Batteries

ABSTRACT Fibrous energy‐storage systems serve as a core component in the next‐generation flexible and wearable electronics, yet their practical application is hindered by the limited temperature resilience of aqueous electrolytes and the mechanically fragile electrolyte‐electrode interfaces. Herein, we design an in situ deep‐eutectic hydrogel electrolyte based on a hydroxyl‐rich glycerol‐ethylene glycol‐H 2 O system, in which the hydrogen‐bond network is engineered to modulate the chemical potential of water and the free‐energy landscape governing phase transitions. Strong H 2 O‐H 2 O H‐bonds are converted into a more uniformly distributed weak H‐bond network in the electrolyte, thereby reducing the thermodynamic driving force for ice formation at low temperatures while suppressing H 2 O volatilization at elevated temperatures. Meanwhile, in situ photopolymerization enables the direct formation of a conformal hydrogel layer on the electrode surface, improving interfacial adhesion and mitigating parasitic reactions such as hydrogen evolution and Zn corrosion. Benefiting from the coupled thermodynamic and interfacial regulation, Zn||PANI coin cell exhibits stable operation over an ultrawide temperature range of −50°C–100°C and delivers a cycling life exceeding 10 000 cycles with 86.71% capacity retention at 25°C. A fibrous Zn||PANI cell further maintains reliable cycling for over 500 cycles at −25°C, demonstrating the applicability of this strategy for temperature‐resilient wearable energy‐storage systems.