Flexible and Durable Meter‐Long Fiber‐Shaped Zn‐Ion Battery Enabled by Zincophilic, Tough Double‐Network Hydrogel Electrolytes

Abstract Flexible fiber‐shaped aqueous zinc‐ion batteries (FAZIBs) show great potential for next‐generation portable and body‐worn electronics due to their inherent safety and biocompatibility. However, the advancement of FAZIBs is significantly impeded by the limited lifespan of Zn fiber anodes. The high‐curvature Zn fiber anode exhibits uneven local electric fields, which exacerbate corrosion, dendrite growth, and mechanical damage from repeated bending or stretching, thereby reducing the device's operational lifetime. In this study, a zincophilic, durable PAAm/SA hydrogel polymer electrolyte (GPE) with a double‐network and strong adhesive interface is proposed to enhance Zn ²⁺ diffusion and electric field uniformity, effectively mitigating dendrite formation and parasitic side reactions. This innovation enables the fabrication of mechanically resilient, high‐performance FAZIBs. Stable Zn plating/stripping is demonstrated on Zn fibers for over 2250 h at 2 mA cm ⁻² and 3 mAh cm ⁻² , which is 28 times longer than conventional aqueous electrolytes. In a 100 cm‐long Zn fiber symmetric cell, reversible Zn plating/stripping is sustained for over 1900 h. The Zn fiber//MnO ₂ FAZIB, incorporating the developed GPE, exhibits exceptional cycling stability, retaining 80.7% capacity after 1400 cycles at 6 C. This work introduces a novel strategy for mitigating dendrite formation and side reactions in Zn fibers.