Effect of Salt Concentration on Dielectric Properties of Li-Ion Conducting Blend Polymer Electrolytes

TL;DR

This study investigates how varying salt concentrations in blend polymer electrolytes affect their dielectric and transport properties, revealing insights into ion dynamics and mechanisms relevant for lithium-ion battery applications.

Contribution

It provides a detailed analysis of the impact of salt concentration on dielectric behavior and ion transport in PEO-PAN electrolytes using FTIR and dielectric spectroscopy.

Findings

Salt increases dielectric constant and shifts relaxation peaks.

Ion interactions influence ionic conductivity at different salt levels.

Proposed ion transport mechanism enhances understanding of ion migration.

Abstract

In the present article, we have studied the effect of the salt concentration (LiPF6) on transport properties and ion dynamics of blend solid polymer electrolyte (PEO PAN) prepared by solution cast technique. Fourier transform infrared (FTIR) spectroscopy confirms the presence of microscopic interactions such as polymer ion and ion ion interaction evidenced by a change in peak area of anion stretching mode. The fraction of free anions and ion pairs obtained from the analysis of FTIR implies that both influence the ionic conductivity with different salt concentration. The complex dielectric permittivity, dielectric loss, complex conductivity have been analyzed and fitted in the entire frequency range (1 Hz to 1 MHz) at room temperature. The addition of salt augments the dielectric constant and shift of relaxation peak in loss tangent plot toward high frequency indicates a decrease of relaxation time. We have implemented the Sigma representation sigma double prime vs sigma prime for solid lithium ion conducting films which provide better insight toward understating of the dispersion region in Cole Cole plot epsilon double prime vs epsilon prime in lower frequency window. The dielectric strength, relaxation time and hopping frequency are in correlation with the conductivity which reveals the authenticity of results. Finally, the ion transport mechanism was proposed for getting the better understanding of the ion migration in the polymer matrix.