The Carbon/Iodide Interface in Protic Ionic Liquid Medium for Application in Supercapacitors
The ILs selected were triethylammonium bis(tetrafluoromethylsulfonyl)imide [Et3NH]-[TFSI] and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide [Emim]-[FSI]. Two iodides, triethylammonium iodide [Et3NH]-[I] or tetraethylammonium iodide [Et4N]-[I], were introduced in the ionic liquid at a concentration of 0.25 mol L-1. The electrochemical experiments as cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy were conducted using a two-electrode cell construction. In some experiments, a silver wire was added as pseudo-reference to monitor the potential of individual electrodes. Activated carbon (AC) with high microporosity coated on aluminum foil from Batscap (France) was used as working and counter electrode. Glass microfiber paper (Whatman) was utilized as separator. Galvanostatic (0.2 A·g-1) cycling up to 1.8 V in two-electrode cell (Figure 1B) demonstrates a remarkable increase of capacitance when [Et3NH]-[I] is added to [Et3NH]-[TFSI], from 78 to 157 F·g-1. The voltammogram of figure 1A shows clearly that the increase of capacitance is caused by the positive electrode where faradaic processes occur.
Acknowledgements:The Foundation for Polish Science is acknowledged for supporting the ECOLCAP Project realized within the WELCOME Program, co-financed from European Union Regional Development Fund.