Zwitterionic Poly(ionic liquid) Hydrogel Electrolytes with High-Speed Ion Conduction Channels for Dendrite-Free, Long-Enduring Zinc-Ion Batteries and Flexible Electronics

Abstract

Flexible zinc-ion batteries (ZIBs) based on hydrogel electrolytes are an important power source for the next generation of soft electronics. However, dendrite growth, intense parasitic reactions and sluggish zinc-ion conduction pose challenges to their practical application. Herein, a zwitterionic poly(ionic liquid) hydrogel electrolyte (PICZ) is proposed to fabricate high-performance and stable ZIBs. The interaction between zwitterionic liquid (CAVIm) and chitosan builds a unique ion migration channel to facilitate the high-speed Zn²⁺ transport kinetics. The hydrogel electrolyte with abundant hydrophilic groups immobilizes water molecules to reduce side reactions and corrosion. The carboxyl groups of CAVIm are inserted into the primary solvation sheath of Zn²⁺ to reduce the desolvation energy barrier and enhance ion transport kinetics. Zn²⁺ is uniformly deposited onto the (002) crystal plane to inhibit dendrite growth. The symmetric cells assembled with PICZ exhibit an ultra-long cycling life exceeding 7000 h, and excellent cycling stability in both AC supercapacitors and NVO full cells. Furthermore, the hydrogel electrolyte is applied as flexible electronics that are integrated with the assembled ZIBs to realize self-powered sensing. This study will offer an efficient strategy for developing ZIBs with high flexibility and stability.