Temperature-Dependent Electrochemical Stability Window of Bis(trifluoromethanesulfonyl)imide and Bis(fluorosulfonyl)imide Anion Based Ionic Liquids

Abstract

The electrochemical stability of 22 commercially available hydrophobic ionic liquids was measured at different temperatures (288.15, 298.15, 313.15, 333.15 and 358.15 K), to systematically investigate ionic liquids towards electrolytes for supercapacitors in harsh weather conditions. Bis(trifluoromethanesulfonyl)imide and bis(fluorosulfonyl)imide anions in combination with 1-Butyl-1-methylpyrrolidinium, 1-Ethyl-3-methylimidazolium, N-Ethyl-N, N-dimethyl-N(2methoxyethyl)ammonium, 1-Methyl-1-(2-methoxyethyl)pyrrolidinium, N-Pentyl-N-methylpyrrolidinium, N, N-Diethyl-N-methyl-N-propylammonium, N, N-Dimethyl-N-ethyl-N-benzyl ammonium, N, N-Dimethyl-N-Ethyl-N-phenylethylammonium, N-Butyl-N-methylpiperidinium, 1-Methyl-1-propylpiperidinium, N-Tributyl-N-methylammonium, N-Trimethyl-N-butylammonium, N-Trimethyl-N-butylammonium, N-Trimethyl-N-propylammonium, N-Propyl-N-methylpyrrolidinium cations were selected for the study. Linear regression with a numerical model was used in combination with voltammetry experiments to deduce the temperature sensitivity of both anodic and cathodic potential limits (defining the electrochemical stability window), in addition to extrapolating results to 283.15 and 363.15 K. We evaluated the influence of the cations, anions, and the presence of functional groups on the observed electrochemical stability window which ranged from 4.1 to 6.1 V.

Mechanisms of Hysteresis and Reversibility across the Voltage-Driven Perovskite–Brownmillerite Transformation in Electrolyte-Gated Ultrathin La0.5Sr0.5CoO3−δ

“…Large negative V g instead likely overoxidizes x = 0.5 LSCO to the point that the mean Co valence reaches the limits of stability of a 10-unit-cell film at ambient conditions, , making V O formation spontaneous as the V g sweep direction is reversed, as in the blue and purple curves in Figure (g). This is the same phenomenon detected in earlier work through cruder voltage-step measurements. , Another possible cause, however, could be electrochemical degradation of anions in the ion gel (TFSI – in this case), which may break down at lower V g magnitudes than the cations (EMI + ). , This would result in a shift of the charge neutral point to lower (i.e., negative) V g ; further study is needed to deconvolute these effects.…”

“…18,67 Another possible cause, however, could be electrochemical degradation of anions in the ion gel (TFSI − in this case), which may break down at lower V g magnitudes than the cations (EMI + ). 81,82 This would result in a shift of the charge neutral point to lower (i.e., negative) V g ; further study is needed to deconvolute these effects.…”

Dynamic Performance of Hybrid Infrared Modulator Based on Single‐Walled Carbon Nanotubes and Ionic Liquid Enabling Fast Response

“…The EMIM-TFSI had a wide electrochemical window (from þ2.6 to À2.1 V) and low electrode-electrolyte interfacial impedance, facilitating efficient Faradaic and non-Faradaic charge transfer processes at interfaces. [47] Moreover, we extend our investigations by subjecting the ionic liquid (IL; i.e., EMIM-TSFI) to the influence of a direct current (DC) voltage characterized by a constant polarity. This deliberate application of electrical potential facilitates the displacement of positive and negative ions within the ionic liquid, provoking a controlled charge and discharge process.…”

“…The EMIM‐TFSI had a wide electrochemical window (from +2.6 to −2.1 V) and low electrode–electrolyte interfacial impedance, facilitating efficient Faradaic and non‐Faradaic charge transfer processes at interfaces. [ 47 ]…”

Alkali and alkaline earth metals in liquid salts for supercapatteries

“…As pure liquid salts at room temperature, they are highly ionized, negligibly volatile, nonexplosive and non-ammable, and offer great safety. Further, their ESWs can usually reach beyond 5.0 V. 26 For example, 1butyl-1-methylpyrrolidinium bis(triuoromethanesulfonyl) imide (Pyr 14 TFSI) can remain stable up to 5.9 V as quoted by Susantyoko et al 27 Such wide ESWs are perhaps the most important reason for using ILs in supercapacitors against eqn (4). However, unlike electrolytes with water and organic solvents of small molecules, ILs are mostly prepared from organic synthesis and present wide spectra of structures, compositions and properties.…”