Working Paper
Authors
- Jack Fawdon University of Oxford ,
- Gregory Rees University of Oxford ,
- Fabio La Mantia University of Bremen ,
- Mauro Pasta
University of Oxford
Abstract
Ionic liquid electrolytes (ILEs) have become popular in various advanced Li-ion battery chemistries because of their high electrochemical and thermal stability, and low volatility. However, due to their relatively high viscosity and poor Li+ diffusion, it is thought large concentration gradients form, reducing their rate capability. Here, we utilised operando Raman microspectroscopy to visualise ILE concentration gradients for the first time. Specifically, using lithium bis(fluorosulfonyl)imide (LiFSI) in N-propyl- N-methylpyrrolidinium FSI, its "apparent" diffusion coefficient, lithium transference number, thermodynamic factor, ionic conductivity and resistance of charge-transfer against lithium metal, were isolated. Furthermore, the analysis of these concentration gradients led to insights into the bulk structure of ILEs, which we propose is composed of large, ordered aggregates.
Content

Supplementary material

Supporting Information
Supporting Information