Comprehensive study on dielectric properties and proton conductivity of graphene oxide (GO) embedded PVdF/PVP membrane electrolytes

Abstract

This article investigates how the presence of polyvinylpyrrolidone (PVP) affects the dielectric properties and proton conductivity of phosphoric acid (PA) doped PVdF/PVP-based composite polymer electrolytes supported by graphene oxide (GO). In the study, insights into the structural, morphological, and thermal characteristics of the proposed composite electrolytes are obtained using characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Proton conductivity and dielectric measurements are carried out across a frequency and temperature range (20 Hz-1 MHz, 300–420 K). We conduct in-depth discussions on the dielectric properties, including AC conductivity (σac), dielectric permittivity (ε′), imaginary permittivity (ε″), and loss tangent (tanδ) of the polymer electrolytes. While GO enhances the thermomechanical properties, the highest proton conductivity values are observed for (PVdF70/PVP30)-GO and (PVdF50/PVP50)-GO electrolytes, reaching 4.4 × 10−5 and 6.1 × 10−4 S/cm respectively. The dielectric measurements revealed a significant increase in the dielectric constant (ε′) and dielectric loss (ε″) values for the composite membranes, especially at lower frequencies and higher temperatures. For instance, the (PVdF50/PVP50)-GO composite exhibited ε′ values of 8.8 × 106, 1.99 × 105, and 77.38 at frequencies of 20 Hz, 1 kHz, and 1 MHz, respectively, at 300 K, and 7.38 × 106, 2.76 × 104, and 430.5 at 420 K. The ε″ values at 300 K for the same composite were 16.18 × 106, 7.25 × 105, and 1.09 × 103, respectively, at the same frequencies. (PVdF50-PVP50)-GO exhibits the lowest relaxation time (τ) and the highest proton conductivity at ambient temperature. These findings underscore the intricate interplay between PVP content, dielectric properties, and proton conductivity, providing valuable insights for the advancement of polymer electrolyte materials. This study contributes to our understanding of PA-doped (PVdFx/PVPy)-GO electrolytes, with implications for electronic and energy storage devices.