Highly stretchable, anti-freezing, self-adhesion and self-healing zwitterionic hydrogel electrolytes for flexible electronic devices

Hydrogel electrolytes, with high ionic conductivity, flexibility, and tunable mechanical properties, are widely applied in flexible strain sensors and supercapacitors. However, the fabrication of hydrogel electrolytes with anti-freezing, self-healing and adhesion in extreme environmental condition remains a challenge. In this study, a zwitterionic hydrogel electrolyte is prepared by introducing betaine, borax, and zinc ions into a poly(vinyl alcohol) and polyacrylic acid double-network hydrogel. The prepared multifunctional hydrogel electrolytes exhibit excellent stretchability (980.0 %), anti-freezing capacity (−28.9 °C), self-healing ability, self-adhesion (22.5 kPa for metal), and ionic conductivity (4.56 S m −1 ). Under applied strain, the resistance of the hydrogel changes, which can be monitored as a variation in the electrical signal to detect strain. Moreover, the flexible strain sensor assembled from the hydrogels is capable of monitoring human movement and transmitting information. Impressively, the zinc-ion supercapacitor based on zwitterionic hydrogel electrolytes demonstrates a high energy density of 19.5 Wh kg −1 , and a high power density of 696.0 W kg −1 . This work offers an effective strategy to design hydrogel electrolytes for flexible electronic devices toward wearable sensing, power supply, and energy storage.