Accurate Identification of Binder Raw Materials for Li-Ion Battery Electrodes by FTIR

Significance of the Topic

Maintaining stringent quality control of lithium-ion battery (LIB) raw materials is critical to ensure electrode performance, manufacturing consistency, and long-term battery reliability. Binders, though used in small proportions, play a pivotal role in mechanical integrity and electrochemical function of electrodes. A rapid and reliable method to verify binder identity and quality can prevent batch failures and improve production yields.

Objectives and Study Overview

This study demonstrates an efficient workflow to identify and verify common LIB binders—polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE)—using the Agilent Cary 630 FTIR spectrometer and MicroLab software. The approach aims to enable fast material authentication at incoming inspection and to highlight FTIR’s capability in distinguishing binder types and polymer phases.

Methodology

Solid samples of known PVDF and PTFE binders were first characterized to build a custom spectral library. Unknown binder samples from a different supplier were analyzed by placing material directly on the ATR crystal, acquiring spectra over 4000–650 cm⁻¹ with 32 scans and 4 cm⁻¹ resolution. The MicroLab software’s Similarity search algorithm generated a hit quality index (HQI) to automatically match unknown spectra against the library and present color-coded confidence results.

Used Instrumentation

• Agilent Cary 630 FTIR spectrometer with diamond ATR module
• Agilent MicroLab software for spectral acquisition and library search

Main Results and Discussion

All four unknown binder samples were correctly identified: three PVDF grades (HQI: 0.907–0.967) and one PTFE (HQI: 0.983). Variations in HQI among PVDF samples indicated possible differences in polymer grade or formulation. FTIR spectra also revealed α-phase signatures of PVDF through characteristic absorption bands (763, 795, 855, 976, 1149 cm⁻¹), demonstrating the method’s sensitivity to polymorphic phase identification.

Benefits and Practical Applications

• Rapid library creation and onboarding of new binder materials for QC workflows
• User-friendly, picture-driven interface reduces training time and risk of operator error
• Automated, color-coded results facilitate instant decision-making at points of receipt
• Detection of material mislabeling, contamination, or batch variability to prevent production disruptions

Future Trends and Applications

Advances in FTIR instrumentation and data analysis will further streamline on-site QC, including integration with glovebox environments for moisture-sensitive materials. Expanded spectral libraries and enhanced chemometric algorithms may enable simultaneous quantification of binder mixtures and detection of impurities, supporting sustainable binder development and real-time process monitoring.

Conclusion

The Agilent Cary 630 FTIR combined with MicroLab software offers a turnkey solution for fast, reliable identification of LIB binder materials. Its compact design and automated workflow make it ideal for production and quality control environments, improving material traceability and manufacturing consistency.

References

1. Cai X., Lei T., Sun D., Lin L. A Critical Analysis of the α, β and γ Phases in Poly(Vinylidene Fluoride) using FTIR. RSC Advances 2017, 7(25), 15382–15389.