A supramolecular hydrogel electrolyte for high-performance supercapacitors

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.