Mechanically Tough and Ionically Conductive Solid Polymer Electrolytes for Precise Motion Monitoring Applications

Flexible gel electrolyte materials, as promising candidates for the next generation of quasi-solid electrolytes in electrochemical devices, face two formidable challenges: low mechanical toughness and insufficient ionic conductivity. To overcome these hurdles, diverse methods for solidifying ionic liquids and fabricating mechanically robust and ionically conductive gel electrolytes have been proposed. In this study, we developed physically crosslinked ion gels by the phase separation of a semi-crystalline structure of poly(vinyl alcohol) (PVA) in an ionic liquid. In the PVA ion gels, phase-separated crystals serve as network junctions. When mechanical stress is applied, the non-covalent bonds formed among polymer chains dissipate a substantial amount of energy. The resulting ion gels exhibited outstanding mechanical properties, with an extremely high toughness of ~46.24 MJ m^-3 and remarkable stretchability of ~2135%. Moreover, the ion gels possessed excellent electrochemical performance, boasting a high ionic conductivity of approximately 20 mS cm^-1 and maintaining stable electrochemical windows of approximately 3 V. These ion gels were successfully employed as stretchable strain sensor and the devices exhibited outstanding linearity, sensitivity, and operational durability.