Hydrogel electrolytes for multifunctional zinc ion batteries

Abstract

Hydrogels, a class of filled-water hydrophilic crosslinked network polymers, are considered to be one of the most prospective candidates for future electrolytes because of their excellent water absorption and flexibility, which meet the essential demands for flexible zinc-ion batteries (ZIBs). Moreover, a wide range of properties, including self-healing ability, broad temperature tolerance, anti-freezing capability, thermal runaway prevention, and degradability, can be achieved by modifying the chemical structure. This potential opens up the possibility for multifunctional ZIBs to be developed. This review begins with a concise introduction to hydrogels, discussing their formation, structure, and the characterization of internal water and ions. The design methods for the electrochemical performance of hydrogel electrolytes in multifunctional ZIBs are then described on the basis of different functionalities. Finally, current research challenges are summarized, and guidelines for future studies are offered to accelerate the development and practical application of multifunctional ZIBs.