Deterioration Evaluation of Lithium-Ion Battery Components Using Infrared/Raman Microscope and Airtight Cells

Significance of the Topic

A detailed understanding of lithium-ion battery component degradation under inert conditions is vital for improving battery life and performance in applications ranging from consumer electronics to electric vehicles.

Objectives and Study Overview

This work evaluates the deterioration of key battery elements—LiFePO4 positive electrode, graphite negative electrode, and polypropylene separator—by comparing virgin and 100-cycle samples using combined infrared and Raman spectroscopy in sealed cells.

Methodology and Instrumentation

Samples were prepared in a glovebox and enclosed in airtight cells with CaF2 windows to prevent exposure to moisture and oxygen. The AIRsight infrared/Raman microscope integrated with the IRXross platform enabled sequential measurements at the same point without sample relocation. Measurement parameters included:

• Infrared reflection mode: 4000–880 cm⁻¹, 8 cm⁻¹ resolution, 100 scans for electrodes, 40 scans for separator.
• Raman spectroscopy: 532 nm laser, 4000–150 cm⁻¹ range, 10 s exposure, 10 accumulations, 50× objective, 100 % ND filter.

Main Results and Discussion

• LiFePO4 positive electrode: Kramers–Kronig–transformed IR spectra showed a shift of phosphate stretching bands (1230 cm⁻¹ and 1075 cm⁻¹), consistent with Li deintercalation and FePO4 formation after cycling.
• Graphite negative electrode: Raman spectra revealed an increased D-band/G-band intensity ratio (ID/IG rising from 0.21 to 0.32), indicating enhanced structural disorder and edge defects due to repeated charge/discharge.
• Polypropylene separator: IR spectra before and after cycling were superimposable, demonstrating chemical stability under the applied cycling conditions.

Benefits and Practical Applications

Combining IR and Raman capabilities in a single instrument improves spatial alignment of spectroscopic data and streamlines analysis of diverse organic and inorganic battery materials. Airtight cells enable accurate evaluation of air-sensitive samples, facilitating reliable comparative studies for quality control and research.

Future Trends and Possibilities

Advances may include high-resolution chemical mapping of electrode surfaces, in situ monitoring of electrolyte decomposition, and extension to solid-state battery materials. Coupling spectroscopic data with machine learning could offer predictive insights into battery aging and performance.

Conclusion

The AIRsight infrared/Raman microscope with airtight sample holders provides a versatile platform for characterizing lithium-ion battery component degradation. Combined spectroscopic analysis confirmed structural changes in electrodes after cycling, while the separator remained stable, contributing to strategies for enhancing battery durability.

References

1. Ait Salah A., Jozwiak P., Zaghib K., Garbarczyk J., Gendron F., Mauger A., Julien C. M. FTIR features of lithium-iron phosphates as electrode materials for rechargeable lithium batteries. Spectrochimica Acta Part A, 65, 1007–1013 (2006).
2. Katagiri G. Raman Spectroscopy of Graphite and Carbon Materials and Its Recent Application. TANSO (Journal of The Carbon Society of Japan), 175, 304–313 (1996).