Role of textural properties and surface functionalities of selected carbons on the electrochemical behaviour of ionic liquid based-supercapacitors

In the present study, five different activated carbons are used as active electrode materials in Ionic Liquid based-Supercapacitors (IL-SCs). Selection of carbons was made according to their different textural and surface properties and includes microporous, microporous–mesoporous and mesoporous carbons with specific surface areas (SDFT) ranging from 1400 to 2200 m2 g−1 and pore lengths (Lo) ranging from 0.7 to 2.8 nm. These carbons are used to build IL-SCs using the ionic liquid N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) as the electrolyte. IL-SCs are electrochemically characterized by electrochemical impedance spectroscopy (EIS) and by galvanostatic charge/discharge (C/D) methods at 25 °C and at 60 °C. The effect of increasing the temperature and the voltage window on electrochemical performance is analysed. The performance of IL-SCs in terms of specific capacitance (Cs) and specific energy (Ereal) strongly increased with temperature and with maximum voltage (Vmax) reaching values as high as 245 F g−1 and 58 Wh kg−1 at 60 °C and 3.5 V. The influence of both textural properties and surface chemistry of the carbons on the performance of IL-SCs is analysed in detail.