Antifreezing and stretchable all-gel-state supercapacitor with enhanced capacitances established by graphene/PEDOT-polyvinyl alcohol hydrogel fibers with dual networks

Abstract

Although aqueous fibrous supercapacitor is one of the most advantageous energy storage devices for powering wearable electronics due to its excellent flexibility, outstanding cycling stability and high safety, it is still a challenge for its electroactive components to be cold-tolerant and stretchable for adapting fluctuating climate environments. Herein, a graphene/PEDOT:PSS hydrogel fiber with a continuous rose flower-like network is firstly constructed, and an antifreezing polyvinyl alcohol (PVA) network is subsequently taken into the hydrogel fiber via solvent replacement to generate an antifreezing and stretchable graphene/PEDOT-PVA hydrogel fiber with dual networks. Benefiting from superior interface compatibility of the hydrogel fiber with a PVA electrolyte, the assembled all-gel-state supercapacitor delivers a high capacitance of 281.2 F g−1 (0.1 A g−1) at 25 °C, more than twice higher than that of an aerogel fiber-based supercapacitor. Furthermore, this supercapacitor exhibits stable subzero-temperature electrochemical performances due to the smooth ion-transport channels and good conductivity of the antifreezing hydrogel fiber electrode, evidenced by the high specific capacitance of 212.6 F g−1 and the excellent capacitance retention of 91% after 5000 charge/discharge cycles at −20 °C. Finally, a highly stretchable spring-like supercapacitor exhibits an excellent capacitance retention of 92% after 5000 stretching cycles at a strain of 500%.