Material Identification of Lithium‑Ion Battery Separators Using FTIR Spectroscopy

Importance of the Topic

Quality control of lithium-ion battery separators is critical to ensure safe and reliable performance in electric vehicles, portable electronics, and energy storage systems. Separators prevent electrode contact, short-circuits, and thermal runaway while enabling ion transport.

Objectives and Study Overview

This study demonstrates the rapid identification of new and used lithium-ion battery separators using the Agilent Cary 630 FTIR spectrometer with ATR sampling and Agilent MicroLab software.

Methodology and Instrumentation

• Instrumentation Used: Agilent Cary 630 FTIR Spectrometer with single-reflection diamond ATR interface.
• Software: Agilent MicroLab with user-generated polymer spectral library and Similarity search algorithm.
• Operating Parameters: Spectral range 4000–650 cm⁻¹; resolution 4 cm⁻¹; 32 scans per sample; library search method.
• Samples: New multilayer polypropylene separator and used separator recovered from a recycling facility.

Main Results and Discussion

• The new separator was identified as polypropylene with an HQI of 0.9406.
• The used separator was identified as polyethylene with an HQI of 0.9227.
• Color coding in green (HQI > 0.90) provided immediate confidence in identification.
• Overlayed spectra highlighted contaminant regions in the used sample, guiding further analysis.

Benefits and Practical Applications

• Turnkey workflow with picture-driven software reduces training time and user error.
• Compact design allows analysis within controlled environments (e.g., glove boxes).
• Rapid library updates and on‐the‐fly spectrum addition improve matching accuracy.
• Applicable for routine QC and R&D of battery materials and components.

Future Trends and Potential Applications

• Development of expanded spectral libraries for multilayer and additive-enhanced separators.
• Integration of FTIR analysis into in-line QC during separator production and cell assembly.
• Application in recycling workflows for material sorting and verification.
• Extension to emerging battery chemistries, including solid-state electrolytes.

Conclusion

The Agilent Cary 630 FTIR spectrometer with ATR sampling and MicroLab software provides a rapid, reliable, and user-friendly solution for identifying lithium-ion battery separators, supporting both quality control and research applications.

Reference

1. Dutta A. Chapter 4 – Fourier Transform Infrared Spectroscopy. Spectroscopic Methods for Nanomaterials Characterization, Elsevier, 2017.
2. Alwan W.; Babu S.; Zieschang F. Quick and Easy Material Identification of Salts Used in Lithium-Ion Batteries by FTIR, Application Note 5994-6243EN, 2023.
3. Babu S.; Alwan W.; Zieschang F. Quick and Easy Material Identification of Solvents Used in Lithium-Ion Batteries by FTIR, Application Note 5994-6182EN, 2023.
4. Alwan W.; Zieschang F. Advancing Research of Lithium-Ion Batteries Using the Agilent Cary 630 FTIR Spectrometer, White Paper 5994-6144EN, 2023.