Characterising lithium-ion electrolytes via operando Raman microspectroscopy.

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Developing advanced lithium-ion and beyond lithium-ion batteries requires a deep understanding of electrolyte behavior.
• Accurate characterization of electrolyte transport and thermodynamic properties is crucial for improving battery performance and safety.

Purpose of the Study:

• To present a comprehensive method for fully characterizing electrolyte systems.
• To quantify key electrolyte properties including diffusion coefficients, transference numbers, and ionic conductivity.
• To correlate bulk electrolyte structure with transport and thermodynamic properties.

Main Methods:

• Operando Raman microspectroscopy to measure electrolyte concentration gradients over time.
• Potentiostatic electrochemical impedance spectroscopy to assess electrochemical properties.
• A combined experimental setup for simultaneous measurement of multiple properties.

Main Results:

• Successfully visualized electrolyte concentration gradients in a model system (LiFSI in G4).
• Quantified Fickian apparent diffusion coefficient, transference number, thermodynamic factor, ionic conductivity, and charge-transfer resistance.
• Demonstrated a method for correlating electrolyte structure with transport phenomena.

Conclusions:

• The presented method enables a complete characterization of electrolyte systems within a single experimental setup.
• This technique is vital for advancing the development of next-generation battery technologies.
• Provides a pathway to link macroscopic electrolyte properties with microscopic structural information.