In situ reduction strategy towards high conductivity, anti-freezing and super-stretchable rGO based hydrogel for diverse flexible electronics

Hydrogels electrolytes with flexibility and high conductivity have been widely used in kinds of flexible electronics. However, hydrogels always suffer from the inevitable freezing of water at subzero temperatures, which results in the sacrificing of their electrical properties. Herein, an anti-freezing, flexible hydrogel based on in situ reduction of graphene oxide (GO) and laponite has been developed as electrolyte for high performance supercapacitor and sensitive sensors. The crosslinked GO and laponite in polyacrylamide (PAM) resulted in an enhanced mechanical property, while the in-situ reduction of GO in the hydrogel enhanced the conductivity and diminishes the aggregated of GO. These features guarantee a reliable electro signal as sensor and a high performance of the supercapacitor. Besides, in the process of preparation of reduced graphene oxide (rGO) hydrogel, the addition of ethylene glycol (EG) and KOH, endows the hydrogel antifreeze properties. This anti-freezing electrolyte can be stretched to a strain of 1600% and maintained a specific capacitance of 37.38 F·g−1 at −20 °C. In addition, the photothermal conversion character of rGO in the hydrogel, endows it's the potential application in wound healing. The overall merits of the hydrogel will open up a new avenue for sensitive sensor and energy storage device in practical applications.