Tough and Ultrastretchable Liquid‐Free Ion Conductor Strengthened by Deep Eutectic Solvent Hydrolyzed Cellulose Microfibers

Abstract Ion conductors (ICs) have gained extensive research interest in various advanced application scenarios including sensors, batteries, and supercapacitors. However, stretchable, tough, and long‐term stable ICs are still hard to achieve yet highly demanded. In this study, the authors propose a one‐pot green and sustainable fabrication of cellulose based ICs through polymerizable deep eutectic solvents treated cellulose followed by an in situ photo‐polymerization. The obtained ICs exhibit extremely high stretchability (3210 ± 302%), high toughness (13.17 ± 2.32 MJ m −3 ), high transparency, and self‐healing ability. Notably, the introduction of cellulose fibers greatly enhances the mechanical properties of ICs while eliminating the environmental concerns of traditional nanocellulose fabrication process. More importantly, the ICs possess good long‐term performance stability after 1 month storage. Due to these outstanding properties, the feasibility of applying ICs in human motion sensing and physiological signal detecting is demonstrated. This simple and green method will contribute to the development of tough, self‐healing, transparent, and long‐term stable ICs.