Ultratough and Freezing-Tolerant PVA–PAA-PANI Hybrid Hydrogel for Supercapacitors and Flexible Sensors

Inherent defects such as poor mechanical strength and low-temperature tolerance have seriously hindered further practical applications of hydrogels in electronic devices. Hence, a polyaniline sandwiched poly(vinyl alcohol)/poly(acrylic acid) (PVA–PAA-PANI) hybrid hydrogel with high strength and ideal low-temperature resistance was constructed by combining the Hofmeister effect and in situ polymerization. This PVA–PAA-PANI hydrogel can provide amazing comprehensive mechanical properties, including 3.5 MPa of breaking strength, 700% of elongation at break, and 11.5 MJ/m3 of toughness, and shows good fatigue resistance. Notably, the hybrid hydrogel-based supercapacitor has a satisfactory specific capacitance of 32.4 mF/cm2 and can withstand 5000 continuous charge/discharge cycles even under harsh cold environments of −20 °C. Moreover, the hybrid hydrogel also exhibits high conductivity and distinct linear sensing behavior, allowing it to accurately monitor various body motions. This work develops new strategies for the preparation of strong hydrogels for electronic devices and promotes their application in real-life applications.