Structural, electrical properties and dielectric relaxations in Na⁺-ion-conducting solid polymer electrolyte

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Solid polymer electrolytes are crucial for advanced battery technologies.
• Developing efficient sodium-ion conductors is essential for sustainable energy storage.

Purpose of the Study:

• To investigate the impact of succinonitrile on the properties of PEO8-NaPF6 solid polymer electrolytes.
• To analyze the structural, electrical, dielectric, and ion dynamics of these modified electrolytes.

Main Methods:

• X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) for structural and morphological analysis.
• Fourier transform infrared spectroscopy (FTIR) for complex formation and deconvolution of ion pairs.
• Analysis of complex dielectric permittivity, loss tangent, and complex conductivity across a wide frequency range.
• Application of Universal Power Law and Cole-Cole plots for ion dynamics investigation.

Main Results:

• Succinonitrile addition influences structural and microstructural properties.
• FTIR confirms complex formation and quantifies free anion fractions.
• Dielectric analysis reveals changes in conductivity, relaxation times, and capacitance.
• Complex conductivity follows the Universal Power Law, showing strong dependence on succinonitrile content.
• Cole-Cole plots indicate decreased relaxation times and enhanced ionic conductivity with succinonitrile.

Conclusions:

• Succinonitrile acts as a plasticizer, decreasing relaxation times and enhancing ion transport in PEO8-NaPF6 electrolytes.
• The modified electrolytes exhibit improved ionic conductivity, making them promising for sodium-ion batteries.
• A theoretical framework was proposed to explain the observed experimental phenomena.