https://doi.org/10.1051/epjconf/202227301001
Li-ion solvation in TFSI and FSI -based ionic liquid electrolytes probed by X-ray photoelectron spectroscopy
Electrochemistry Laboratory, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
* Corresponding author: mario.el-kazzi@psi.ch
Published online: 2 December 2022
For Li-ion batteries, the Li-ion solvation in liquid electrolytes is a crucial parameter affecting directly the electrochemical cycling performance. X-ray photoelectron spectroscopy (XPS) can play an essential role for investigating the cation and anion electronic structure and monitoring the Li-ion solvation into various solvent and salt environments. In this contribution, we demonstrate the capability of conventional laboratory XPS using Al Kα X-ray source to determine the anions solvation shell of Li+ cation within the low vapour pressure and vacuum compatible ionic liquid electrolytes. 1M of LiTFSI and 1M of LiFSI salts dissolved in (EMIM+-FSI-) and (EMIM+-TFSI-) ionic liquids respectively are investigated by acquiring the F1s, N1s, C1s, S2p and Li1s core levels. The binding energy difference between the N1s component originating from the EMIM+ cation and the N1s component originating from TFSI- or FSIanions solvating the Li+ confirms that both TFSI- and FSIcontribute simultaneously to the Li+ solvation. Additionally, the stability of the TFSI and FSI -based ionic liquid electrolytes is carefully discussed for long X-ray exposure times.
© The Authors, published by EDP Sciences, 2022
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
