Facile synthesis of triple-network organo-hydrogel for all-temperature flexible supercapacitors

A new triple-network organo-hydrogel with high anti-freezing and thermally-stable performance is prepared for application in all-temperature flexible supercapacitor. It is composed of boric acid/graphene/polyvinyl alcohol matrix and H2SO4/dimethyl sulfoxide mixing solution. The incorporation of graphene and boric acid into polymer matrix can improve thermal stability and ionic conductivity of organo-hydrogel. The H2SO4 and dimethyl sulfoxide are key roles for improving anti-freezing of organo-hydrogel. The organo-hydrogel exhibits high ionic conductivity of 1.6 and 3.1 S/m at -80 and 90 degrees C, respectively. As a result, the assembled supercapacitor delivers a high capacitance retention of 84.5% and 113.3% at ultra-low temperature (-80.0 degrees C) and high temperature (90.0 degrees C), respectively. The work provides a new route to design and prepare flexible supercapacitor with wide temperature range.