Tracking solid electrolyte interphase dynamics using operando fibre-optic infra-red spectroscopy and multivariate...

Area of Science:

• Materials Science
• Electrochemistry
• Spectroscopy

Background:

• The solid electrolyte interphase (SEI) is critical for battery performance, reliability, and safety.
• Understanding SEI nucleation, growth, and composition is challenging due to its dynamic nature.

Purpose of the Study:

• To develop an advanced method for in-situ analysis of SEI evolution during battery operation.
• To provide molecular-level insights into SEI formation and identify factors influencing its stability.

Main Methods:

• Operando Infra-red Fibre-optic Evanescent Wave Spectroscopy (IR-FEWS) using chalcogenide fibers.
• Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) for spectral data analysis.
• Investigation of SEI formation on different anode materials and electrolytes.

Main Results:

• Established molecular fingerprints for identifying SEI reaction products.
• Observed distinct SEI evolution patterns based on electrolyte and anode material variations.
• Identified intrinsic instability in lithium titanate's SEI, characterized by ongoing carbonate formation.

Conclusions:

• The combined IR-FEWS and MCR-ALS approach offers a powerful tool for understanding SEI dynamics.
• This method bridges the gap between empirical observations and theoretical understanding of SEI formation.
• The findings pave the way for designing more stable and reliable battery systems.