Tough, Anti‐Fatigue, Self‐Adhesive, and Anti‐Freezing Hydrogel Electrolytes for Dendrite‐Free Flexible Zinc Ion Batteries and Strain Sensors

Abstract

Abstract Quasi‐solid aqueous zinc ion batteries (AZIBs) based on flexible hydrogel electrolytes are promising substitutions of lithium‐ion batteries owing to their intrinsic safety, low cost, eco‐friendliness and wearability. However, it remains a challenge to lower the freezing point without sacrificing the fundamental advantages of hydrogel electrolytes such as conductivity and mechanical properties. Herein, an all‐around hydrogel electrolyte is constructed through a convenient energy dissipation strategy via the rapid and reversible intramolecular/intermolecular ligand exchanges between Zn 2+ and alterdentate ligands. The as‐obtained hydrogel exhibits excellent mechanical properties, fatigue resistance, high Zn‐ion conductivity (38.2 mS cm −1 ), good adhesion (19.1 kPa), and ultra‐low freezing point (−97 °C). Due to the alterdentate ligands help to improve the zinc ion solvation structure and guide uniform Zn deposition, the Zn||Zn symmetric cells show stable plating/stripping behavior and long‐term cycle stability. The Zn||V 2 O 5 full cells exhibit large capacity of 230.6 mAh g −1 and high capacity retention of 75.2% after 1000 cycles. Furthermore, flexible AZIBs operate stably even under extreme conditions including low temperature (−40 °C) and large bending angle (180°). The mechanically damage‐resistant hydrogel can also be utilized in flexible strain sensors. This work offers a facile strategy for developing mechanically deformation‐resistant, dendrite‐free, and environmentally adaptable AZIBs.