High temperature solid-state supercapacitor designed with ionogel electrolyte

To date, the design of high temperature electrochemical double layer capacitors (EDLCs) remains a challenge more specifically related to the electrolyte. The electrochemical performance of EDLC can be tuned by the temperature, and a better performance can be achieved at higher temperature if all the components are well suited to this purpose. Subsequently, an all solid-state EDLC operated at high temperature using porous carbon electrodes and a solid-like electrolyte was fabricated. Such an approach opens the route towards safer and flexible devices. An ionogel was used as the solid electrolyte and concomitantly as separator in this all-solid EDLC. The synthetized ionogel exhibits a high ionic conductivity over a wide temperature range, from 4 mS cm−1 at 20 °C up to 26 mS cm−1 cm at 100 °C. The all solid state EDLC thus prepared was able to withstand operating temperature as high as 100 °C, under a 2.5 V cell voltage. Long term galvanostatic charge−discharge cycling over 25 000 cycles were achieved at 100 °C, thus demonstrating very good capacitance retention. The ionogel-based EDLCs therefore appear to be suitable for high temperature environments.