Hierarchically‐Structured and Mechanically‐Robust Hydrogel Electrolytes for Flexible Zinc‐Iodine Batteries

Abstract Hydrogel electrolytes have been widely explored in aqueous zinc‐iodine batteries (AZIBs), in light of their intrinsic strong water‐retention capability and superior flexibility of hydrogel network. However, hydrogel‐based AZIBs are still facing challenges due to the inferior ionic conductivity, dendrite formation, and corresponding fatigue‐induced damage. Herein, a hydrogel electrolyte is designed and engineered with preferentially aligned porous structures, where Zn²⁺ can promptly transport along the pores. AZIBs fabricated from the hydrogel electrolyte exhibited distinct cycling stability over 1,000 h (500 cycles) at 0.5 mA cm⁻². Moreover, in light of the substantially improved mechanical robustness, the hydrogel electrolyte network remained intact over a 27,000‐cycle charging/discharging test at 5 A g⁻¹, with a slight change in capacity, surpassing most previously reported AZIBs. Such kind of hydrogel electrolyte‐based AZIBs can be further explored as the flexible power system for wearable devices, enabling significantly accelerated wound healing through electrical stimulation over the epidermal wounds. This work sheds light on hydrogel electrolytes design for long‐life aqueous zinc‐based batteries, with great potential as power systems for wearable and implantable devices.