Characterising Lithium-Ion Electrolytes Via Operando Raman Microspectroscopy

Abstract

The successful innovation of high-energy Li-ion battery alternatives requires a comprehensive understanding of their respective electrolyte.1 Full characterisation of liquid electrolytes conventionally requires multiple experimental setups, which can be both time and resource intensive.2,3 Here, we present a unified method for characterising Li-ion liquid electrolytes using operando Raman microspectroscopy in tandem with potentiostatic electrochemical impedance spectroscopy (PEIS). Performing a time-series of 1D Raman line scans to measure electrolyte concentration gradients, and being in tandem with PEIS, allowed for the quantification of the Fickian “apparent” diffusion coefficient, transference number, thermodynamic factor, ionic conductivity and resistance of charge transfer of the electrolyte lithium bis(fluorosulfonyl)imide (LiFSI) in tetraglyme (G4).4 We believe this facile and powerful new experiment is implementable in both academia and industry to understand how novel electrolyte’s properties are influencing the concentration gradient and non-uniform Li+ deposition (dendrite growth). References Cheng, X. B., Zhang, R., Zhao, C. Z. & Zhang, Q. Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review. Chemical Reviews 117, 10403–10473 (2017).Valoen, L. O. & Reimers, J. N. Transport Properties of LiPF6-Based Li-Ion Battery Electrolytes. Journal of The Electrochemical Society 152, A882 (2005).Hou, T. & Monroe, C. W. Composition-dependent thermodynamic and mass-transport characterization of lithium hexafluorophosphate in propylene carbonate. Electrochimica Acta 332, 135085 (2020).Fawdon, J., Ihli, J., La Mantia, F., Pasta, M. Characterising Lithium-Ion Electrolytes via Operando Raman Microspectroscopy, (2020). ChemRxiv. Preprint. https://doi.org/10.26434/chemrxiv.13359344.v1