Supported Ionic Liquid Gel Membrane Electrolytes for Flexible Supercapacitors

In this work, a novel and easy-to-use methodology is developed to prepare supported ionic liquid gel membranes (SILGMs) by incorporating ionogels into commercial porous supports, to use as both electrolytes and separators for supercapacitors. Macroscopic sol-gel transition temperature, Fourier transform infrared spectra, and thermal behaviors of the ionogels are systematically investigated. Ionic conductivities of the ionogels and SILGMs are measured from 25 to 100 °C. The ionic conductivities of the ionogels are lower by one order of magnitude once they are incorporated into the supports. Nonetheless, the ionic conductivity of the SILGMs has reached the practical application level required for energy storage and conversion devices. Furthermore, the stability and flexibility of SILGMs are investigated as flexible electrolytes for supercapacitor devices (see Video in the Supporting Information). Charge-discharge cycling of symmetric supercapacitors based on the SILGMs reveal specific capacitance as high as 153 F g^-1 at 0.1 A g^-1, and remain at 101 F g^-1 at 10 A g^-1. The capacitance retention after 10 000 charge-discharge cycles at 5.0 A g^-1 is as high as 97%, demonstrating excellent cycle stability of the device. The studies suggest that SILGMs are promising candidates for stable, high performance, and flexible energy storage and conversion devices that could be made by high volume roll-to-roll processing.