Acyclic and Cyclic Alkyl and Ether‐Functionalised Sulfonium Ionic Liquids Based on the [TFSI]⁻ and [FSI]⁻ Anions as Potential Electrolytes for Electrochemical Applications

Abstract

This work provides a study based on acyclic and cyclic sulfonium ionic liquids (ILs) with alkyl and ether-functionality on the cation paired with the bis{(trifluoromethyl)sulfonyl}imide, [TFSI] À , or the bis(fluorosulfonyl)imide, [FSI] À , as the counter anion. Herein, thermophysical characterisation of nine sulfonium-based ILs concerning the density, viscosity and conductiv-ity and thermal properties including phase transition behaviour and decomposition temperature is reported. The electrochemical stability of the ILs was also measured by cyclic voltammetry at a glassy carbon macro-disk electrode. All of the ILs showed low melting point, low viscosity and good conductivity and could serve as potential electrolytes for energy storage devices.[a] S.

Effect of mixed anions on the transport properties and performance of an ionic liquid-based electrolyte for lithium-ion batteries

“…where I ss is the steady-state current reached after cell polarization, and I 0 is the initial current, which can be determined more accurately by using the cell resistance and Ohm's law. All 1 H, 19 F and 7 Li diffusion experiments were performed at a magnetic field strength of 17.6 T ( 1 H Larmor frequency of 750 MHz) on a Bruker Avance HD wide-bore spectrometer using a double-channel 1 H- 19 F/ 31 P-15 N 3.2 mm Bruker MAS probe inserted in a Micro 2.5 XYZ gradient system with 60 A amplifiers. 7 Li- 19 F Heteronuclear Overhauser Effect SpectroscopY experiments (HOESY) were performed using the same conditions.…”

“…All 1 H, 19 F and 7 Li diffusion experiments were performed at a magnetic field strength of 17.6 T ( 1 H Larmor frequency of 750 MHz) on a Bruker Avance HD wide-bore spectrometer using a double-channel 1 H- 19 F/ 31 P-15 N 3.2 mm Bruker MAS probe inserted in a Micro 2.5 XYZ gradient system with 60 A amplifiers. 7 Li- 19 F Heteronuclear Overhauser Effect SpectroscopY experiments (HOESY) were performed using the same conditions. All experiments were recorded at a regulated temperature using a 1000 L • h −1 flux of dried air with a 173 K dew point using the Bruker BVT unit, and the temperature calibration was obtained with the 1 H NMR spectra of methanol [28].…”

“…Self-diffusion coefficients (D) were obtained for [C 3 C 1 pyr] + , [FSI] − , [TFSI] − and Li + using the 1 H, 19 F and 7 Li spins. The pulsed field gradient-stimulated echo pulse sequence was used with bipolar gradient pulses and a longitudinal eddy-current delay (STE-BP-LED) [29].…”

“…The Overhauser magnetization transfer from 7 Li to 19 F spins was demonstrated using one or two-dimensional HOESY experiments for 7 Li to 19 F and 19 F to 7 Li transfer, respectively, at a magnetic field strength of 17.6 T [31]. The delay for magnetization recovery (1 s) was sufficient to ensure the recovery of 7 Li or 19 F magnetization, the T 1 values of which are approximately 900 ms, 150 ms and 400 ms for 7 Li, [FSI] − and [TFSI] − , respectively. The delay used for magnetization transfer was set to 100 ms.…”

“…Among these ILs, those containing the [FSI] − anion exhibit higher conductivities and better diffusivities than their analogues based on [TFSI] − and have therefore attracted considerable attention [6,7]. Moreover, recent reports highlight the ability of [FSI] − to efficiently passivate anode materials in Li-ion batteries [8][9][10].…”