High voltage, asymmetric EDLCs based on xerogel carbon and hydrophobic IL electrolytes

EDLCs Based on Solvent‐Free Ionic Liquids

“…ESWs that are exploitable for high-voltage supercapacitors with such ILs are thus 3.7 V for EMITFSI, 4.2 V for PYR 14 TFSI and PYR 14 Tf and 4.0 V for PYR 1(2O1) TFSI. Given that the typical potential of the discharged carbon electrodes is about −0.1 V versus Fc/Fc + , the maximum potential excursion of the positive electrode ( V + ) upon charge is 1.7 V. This value is narrower than that feasible with the negative electrode ( V − ), which is 2.0 V in EMITFSI, 2.5 V in PYR 14 TFSI and PYR 14 Tf and 2.3 V in PYR 1(2O1) TFSI [11,12]. Thus, if we assume the same specific capacitance for the positive and negative electrodes in a symmetric configuration of EDLC, where the two electrodes have the same carbon loading, the maximum potential excursion for the negative electrode with these ILs would be limited by that of the positive, as is shown by Eq.…”

“…Materials such as activated carbons, cryo/xerogel carbons, carbon fibers, template carbons, and carbon nanotubes (CNTs) have been investigated in different ILs [11,12,23,35,[51][52][53][54][55][56][57]. While the capacitance values of high-surface-area, microporous activated carbons are all significantly higher than 100 F g −1 , the data are not of straightforward comparison because they are referred to different operational conditions.…”

“…While the capacitance values of high-surface-area, microporous activated carbons are all significantly higher than 100 F g −1 , the data are not of straightforward comparison because they are referred to different operational conditions. Mesoporous cryo/xerogel carbons featuring tunable pore-size distribution by chemical synthesis display relatively high specific surface areas and hydrophobic surfaces as well as specific capacitance values >100 F g −1 in EMITFSI and PYR 14 TFSI even at a sweep rate as high as 20 mV s −1 [11]. Template synthesis of mesoporous carbons enables very good control of carbon porosity.…”

“…AEDLCs featuring different carbon electrodes and ILs were tested. PYR 14 TFSIbased AEDLCs with xerogel carbon electrodes featuring capacitance responses of 110-120 F g −1 were cycled at 60 • C over more than 13 000 galvanostatic charge-discharge cycles with V max ≥ 3 V and up to 3.9 V with low capacitance ESW width, IL reduction and oxidation limits, potential of the discharged carbon electrode and maximum feasible potential excursion for the negative ( V − ) and positive electrodes ( V + ) are indicated [11,12].…”

Ionic Liquids Containing 1,1-Dicyano-1-acetylmethanide Anion as Potential Electrolytes

“…For this reason, ILs have been considered as promising electrolyte candidates for constructing safe electrochemical devices including EDLC compared with volatile aqueous and organic electrolytes. [10][11][12][13][14][15] Generally, large surface area of electrode is considered as the necessity to obtain the high capacitance in EDLC. For example, Denshchikov et ).…”