Antifreeze high stretch ion-conducting hydrogels and their application in flexible devices

Abstract

Ion-conducting hydrogels (ICHs) represent ideal candidates for flexible electronic devices due to their excellent flexibility and conductivity. However, challenges such as inherently weak mechanical properties and susceptibility to freezing in low-temperature environments limit their practical applications.This study successfully prepared an ion-conductive hydrogel with an interpenetrating network structure by dissolving zinc chloride (ZnCl₂ ) in ethylene glycol (EG) solution to form a eutectic solvent (DESs), and adding hydroxyethyl cellulose (HEC), acrylamide (AM), acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS).The resulting hydrogel exhibited exceptional mechanical properties, achieving a tensile strain of 1923% and a tensile stress of 0.36 MPa. Moreover, the hydrogel demonstrated both high conductivity (1.07 S m⁻¹ at -18 °C) and anti-freezing properties, fulfilling the requirements for flexible sensors and supercapacitors. The presence of EG as a hydrogen bond donor, combined with the ZnCl2-based DES, was identified as a critical factor in enhancing the hydrogel’s mechanical strength and frost resistance. Additionally, ZnCl2 is added as a conductive filler. Using this material, a supercapacitor was successfully constructed, with a specific capacitance of 70.5 F g⁻¹ at a current density of 1 A g⁻¹ in the voltage range of 0 - 0.8 V. As a result, the hydrogel strain sensor exhibited enhanced wearable motion detection capability, attributed to its superior mechanical robustness, conductivity, and low-temperature tolerance.