A supramolecular hydrogel electrolyte for high-performance supercapacitors

Abstract

With the development of flexible supercapacitors, aqueous gel polymer electrolytes with high ionic conductivity, wide voltage window, good mechanical performance and enough security are drawing great attention. Herein, a series of novel supramolecular hydrogel electrolytes are proposed and fabricated by a facile process at room temperature. They show good elongation at break and moderate ultimate tensile strength. The optimum hydrogel electrolyte exhibits an ionic conductivity of 81.27 mS cm−1, which endows a carbon-based supercapacitor with a stable voltage window of 2 V. The carbon-based supercapacitor can deliver a specific capacitance of 24.0 F g−1, a specific energy of 12.6 Wh kg−1 and a capacitance retention of 110% after 5000 charge-discharge cycles. After introducing a redox additive into the hydrogel electrolyte, the specific capacitance and specific energy of the resultant supercapacitor can be further increased to 32.7 F g−1 and 18.2 Wh kg−1, respectively. This work may provide a universal strategy to explore aqueous gel polymer electrolytes with high voltage window for applications in flexible energy storage devices.