Characterization of Lithium-Ion Battery Binders

Importance of the Topic

The choice and characterization of binders for lithium-ion battery electrodes directly influence cell performance, safety and environmental impact. Water-based manufacturing routes demand binders with sufficient mechanical and thermal stability to maintain electrode integrity without harmful organic solvents.

Study Objectives and Overview

This study evaluates three common lithium-ion battery binders—sodium carboxymethylcellulose (NaCMC), poly(vinylidene fluoride) (PVDF) and styrene-butadiene rubber (SBR)—using spectroscopic and thermal analysis techniques. The aim is to compare their chemical composition, thermal behavior and suitability for water-based electrode fabrication.

Used Instrumentation

• FTIR spectrometer: Shimadzu IRSpirit with QATR-S single-reflection ATR (diamond prism)
• Thermogravimetric analyzer: Shimadzu DTG-60 (simultaneous DTA-TGA)
• Differential scanning calorimeter: Shimadzu DSC-60 Plus

Methodology

SBR solutions were coated on glass slides and dried overnight at room temperature to remove water before analysis. NaCMC and PVDF were analyzed without pretreatment. FTIR spectra were collected at 4 cm⁻¹ resolution over multiple accumulations. TGA measurements ranged from room temperature to 580 °C at 10 °C/min in nitrogen and air. DSC scans were performed according to ISO 11357-2 and 11357-3 with heating/cooling cycles between −100 °C and 210 °C in nitrogen at 20 °C/min.

Main Results and Discussion

FTIR confirmed characteristic binder functional groups and revealed water-related absorption in untreated SBR, which diminished after drying. TGA indicated decomposition onset temperatures in nitrogen of 269 °C (NaCMC), 399 °C (PVDF) and 313 °C (SBR); in air these were 269 °C, 396 °C and 286 °C, respectively. All binders exceed the typical electrode drying temperature range (20–90 °C), ensuring thermal stability during processing. DSC analysis showed a broad moisture-evaporation peak at 115 °C for NaCMC, glass transitions at −38 °C for PVDF and 15.7 °C for SBR, a PVDF melting endotherm at 163.9 °C and crystallization at 121.7 °C.

Benefits and Practical Applications

• FTIR provides rapid binder identification and detection of residual moisture.
• TGA and DSC assess thermal stability and phase transitions critical for electrode drying and cycling durability.
• Data supports selection of binders compatible with water-based, eco-friendly manufacturing processes.

Future Trends and Opportunities

Developments in bio-derived and high-performance copolymer binders will further enhance sustainability and electrode performance. Integration of in situ thermal analysis and advanced spectroscopy during electrode fabrication can enable real-time quality control. AI-driven data analysis may accelerate binder screening and optimization.

Conclusion

This comparative study demonstrates that NaCMC, PVDF and SBR exhibit suitable chemical and thermal properties for lithium-ion battery electrode manufacturing. PVDF offers the highest decomposition temperature, while NaCMC and SBR are compatible with water-based processes. Combined FTIR, TGA and DSC techniques provide a comprehensive toolkit for binder selection and process optimization.

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