Surface Analyses of PVDF/NMP/[EMIM][TFSI] Solid Polymer Electrolyte

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Solid polymer electrolytes (SPEs) are crucial for advanced battery technologies.
• Understanding the processing-structure-property relationships of SPEs is vital for performance optimization.
• PVDF/NMP/[EMIM][TFSI] is a promising ionic liquid-based SPE system.

Purpose of the Study:

• To investigate the impact of thermal treatment conditions on SPE properties.
• To correlate processing parameters with surface morphology, phase, and chemical composition.
• To optimize SPEs for enhanced electrochemical applications.

Main Methods:

• Scanning electron microscopy (SEM) for surface morphology.
• Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) for phase and chemical analysis.
• Differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) for thermal and surface composition analysis.

Main Results:

• Electrolyte morphology features spherulites whose size increases with solvent evaporation rate.
• Raman mapping reveals semicrystalline spherulites and amorphous inter-spherulite regions.
• FTIR and Raman indicate dominance of the β-phase, while DSC shows decreased crystallinity with increased evaporation rate.
• XPS and ToF-SIMS confirm surface composition approaches that of the ionic liquid at higher evaporation rates.

Conclusions:

• Thermal treatment and solvent evaporation rate significantly influence SPE structure and surface chemistry.
• Controlled solvent evaporation can enhance ionic liquid concentration at the SPE surface.
• Findings provide insights for tailoring SPEs for improved electrochemical device performance.