Triethylammonium bis(tetrafluoromethylsulfonyl)amide protic ionic liquid as an electrolyte for electrical double-layer capacitors

Abstract

This study describes the preparation, characterization and application of [Et(3)NH][TFSA], either neat or mixed with acetonitrile, as an electrolyte for supercapacitors. Thermal and transport properties were evaluated for the neat [Et(3)NH][TFSA], and the temperature dependence of viscosity and conductivity can be described by the VTF equation. The evolution of conductivity with the addition of acetonitrile rendered it possible to determine the optimal mixture at 25 °C, with a weight fraction of acetonitrile of 0.5. This mixture was also evaluated for transport properties, and showed a Newtonian behavior, as the neat PIL. An electrochemical study demonstrated, at first, a passivation on Al after the second cyclic voltammogram. Subsequently, the electrochemical window was estimated using a three-electrode cell to 4 V on a platinum electrode, and to 2.5 V on activated carbon. Finally, the neat PIL was found to exhibit good performances as promising electrolyte for supercapacitor applications.

Influence of Temperature on Supercapacitor Components

“…For instance, after adding ACN solvent to Triethylammonium bis(tetrafluoromethylsulfonyl)amide ([Et 3 NH]-[TFSA] PIL), the conductivity at room temperature reaches its highest for a weight fraction of w ACN = 0.5-50 mS cm −1 [17]. However, as mentioned in foregoing sections, improved ionic conductivity is achieved in this situation at a cost of the thermal stability of the IL-based electrolytes.…”

“…The ionic conductivity of an electrolyte is related to its diffusion coefficient by the Nernst-Einstein relation, The diffusion coefficient (D) of an ideal solution containing spherical species of an effective radius r is related to the viscosity by the Stokes-Einstein rule, The ionic conductivity and viscosity of various ionic liquids and polymer electrolytes have been measured and fitted to the VTF equation in broad studies [5,[16][17][18]. 7.…”

Room-Temperature Molten Salts: Protic Ionic Liquids and Deep Eutectic Solvents as Media for Electrochemical Application

“…− -based PILs [120]. Figure 7.17 shows cyclic voltammograms of an aluminum electrode in [HN 222 ][N(Tf) 2 ] from the first to the fourth cycle [120]. The first cycle illustrates a hysteresis loop initiated at about 0.25 V vs. Ag with a large irreversible current peak (1 mA cm −2 ) at about 1.1 V vs. Ag.…”

“…7.19) demonstrate that PIL-based . Reproduced from [120] 2 ] is able to feature stable performance in the temperature range from 10 to 60 °C. At the same time, when PILs with low-water content are used in combination with AC containing few surface groups, such supercapacitors do not exhibit any evident pseudo-capacitive behavior in comparison with phosphonium-based PILs, as shown in Fig.…”

“…Considering these results, each DES appears to display an electrochemical stability window (ESW) large enough to be used as an electrolyte for the energy storage systems as described below. − -based PILs [120]. Figure 7.17 shows cyclic voltammograms of an aluminum electrode in [HN 222 ][N(Tf) 2 ] from the first to the fourth cycle [120].…”