Characterization of Lithium-Ion Battery Binders

Significance of the topic

Binders play a vital role in lithium-ion battery electrodes by ensuring mechanical cohesion and contributing to chemical, thermal and electrochemical stability. Accurate characterization of binder materials supports the development of solvent-free, water-based manufacturing processes and optimizes battery performance for energy storage applications.

Study objectives and overview

This study aims to compare three common binder types—sodium carboxymethylcellulose (NaCMC), poly(vinylidene‐fluoride) (PVDF) and styrene–butadiene rubber (SBR)—using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The goal is to assess composition and thermal behaviors that influence electrode processing and stability.

Methodology and used instrumentation

• FTIR analysis with Shimadzu IRSpirit and QATR-S ATR accessory (diamond prism), resolution 4 cm⁻¹, 45 scans.
• Thermogravimetric analysis on Shimadzu DTG-60 under nitrogen (300 mL/min) and air atmospheres from room temperature to 580 °C at 10 °C/min.
• Differential scanning calorimetry on Shimadzu DSC-60 Plus under nitrogen (100 mL/min), ramp cycles between −100 °C and 210 °C at 20 °C/min following ISO 11357-2 and ISO 11357-3 guidelines.

Main results and discussion

• FTIR spectra confirmed characteristic functional groups and highlighted the removal of moisture from SBR by drying, which eliminates overlapping water absorption peaks and enhances polymer fingerprint clarity.
• TGA in both nitrogen and air showed decomposition onset temperatures well above typical electrode drying ranges (20–90 °C). PVDF exhibited the highest thermal stability (≈398 °C in nitrogen, ≈396 °C in air), followed by SBR and NaCMC (≈269 °C). SBR stability decreased more markedly in air.
• Weight loss profiles indicated significant moisture release from NaCMC below 200 °C and multi-stage degradation of PVDF in air, associated with defluorination and carbonaceous residue decomposition.
• DSC measurements revealed moisture evaporation from NaCMC around 115 °C, a glass transition of SBR at 15.7 °C and PVDF melting and crystallization events at 163.9 °C and 121.7 °C, respectively.

Benefits and practical applications

• FTIR enables rapid identification of binder composition and confirmation of moisture content removal, ensuring reproducible electrode formulation.
• TGA provides critical data on thermal stability thresholds, guiding safe processing temperatures and highlighting binder suitability under inert and oxidative conditions.
• DSC characterizes phase transitions that affect mechanical properties and electrode lifespan, informing binder selection for specific temperature regimes.

Future trends and potential applications

• Integration of advanced thermal mapping techniques to assess binder behavior in full cell assemblies.
• Development of novel bio-based and hybrid binders with tailored thermal and mechanical profiles for next-generation batteries.
• Coupling in situ spectroscopic and calorimetric methods to monitor binder degradation during cycling.

Conclusion

Characterization of NaCMC, PVDF and SBR binders by FTIR, TGA and DSC offers comprehensive insight into their composition, thermal stability and phase behavior. These findings support the optimization of water‐based electrode fabrication and the selection of binders for enhanced battery safety and performance.

References

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