Characterising lithium-ion electrolytes via operando Raman microspectroscopy

Knowledge of electrolyte transport and thermodynamic properties in Li-ion and beyond Li-ion technologies is vital for their continued development and success. Here, we present a method for fully characterising electrolyte systems. By measuring the electrolyte concentration gradient over time via operando Raman microspectroscopy, in tandem with potentiostatic electrochemical impedance spectroscopy, the Fickian apparent diffusion coefficient, transference number, thermodynamic factor, ionic conductivity and resistance of charge-transfer were quantified within a single experimental setup. Using lithium bis(fluorosulfonyl)imide (LiFSI) in tetraglyme (G4) as a model system, our study provides a visualisation of the electrolyte concentration gradient; a method for determining key electrolyte properties, and a necessary technique for correlating bulk intermolecular electrolyte structure with the described transport and thermodynamic properties. The full characterisation of lithium-ion electrolytes is of paramount importance for the continued development and innovation of lithium ion and lithium metal batteries. Here, the authors present a new experimental setup to obtain all key electrolyte parameters using operando Raman microspectroscopy

Automated summary

Understanding electrolyte transport and thermodynamic properties is crucial for the development and success of Li-ion and beyond Li-ion technologies. This study presents a method for fully characterising electrolyte systems, providing key parameters using operando Raman microspectroscopy for visualization and correlation with bulk intermolecular electrolyte structure. The full characterisation of lithium-ion electrolytes is essential for continued advancement and innovation in lithium ion and lithium metal batteries.