Effects of ultrasonic assisted processing and clay nanofiller on dielectric properties and lithium ion transport mechanism of poly(methyl methacrylate) based plasticized polymer electrolytes

Abstract

Lithium ion conducting solid polymer electrolyte (SPE) films consisted of poly(methyl methacrylate) (PMMA) matrix with lithium perchlorate as a dopant ionic salt, poly(ethylene glycol) as plasticizer and montmorillonite clay as inorganic nanofiller have been prepared by classical solution casting and high intensity ultrasonic assisted solution casting methods. The X-ray diffraction study confirmed the amorphous structure of all these PMMA-based solid electrolytes and the clay nanosheets existed in exfoliated form in their amorphous phase. Dielectric relaxation spectroscopy had been employed for the investigation of complex dielectric function, ac electrical conductivity, electric modulus, and impedance spectra of these electrolytes over the frequency range from 20 Hz to 1 MHz. It was observed that the dielectric properties and ionic conductivity of the electrolytes strongly depended on the sample preparation methods, and also had changes with addition of the clay nanofiller. Temperature-dependent dielectric study of the electrolyte films confirmed that their dc ionic conductivity and conductivity relaxation time values obeyed the Arrhenius behavior. This study also revealed that the lithium ion transportation in the ion-dipolar complexes of these electrolytes occurred through hopping mechanism and it was correlated with the conductivity relaxation time. Preparation of these electrolyte films through ultrasonic assisted solution casting method increased the ionic conductivity by more than one order of magnitude in comparison to that of the classical solution casting method, which revealed that the former was a novel method for the preparation of these SPEs of relatively enhanced ionic conductivity.

Anomalous behavior of the dielectric and electrical properties of polymeric nanodielectric poly(vinyl alcohol)–titanium dioxide films

“…The spectra of M ′ and M ″ for the PVA– x wt % TiO 2 nanocomposites at 30 °C are depicted in Figure . We found that the M ′ values increased nonlinearly with increasing frequency; this suggested that it was the response of a bulk material because the electrode‐polarization‐effect‐dominated material had low‐frequency M ′ values close to zero . The M ″ spectra of the 1 and 3 wt % TiO 2 ‐based PNC films clearly exhibited sharp relaxation peaks in the low‐frequency region; these corresponded to the PVA main‐chain dynamics.…”

“…The M* (ω) spectra, which are the inverse of the dielectric function [ M* (ω) = 1/ɛ * (ω)] of the PNC materials, have been frequently studied to nullify the contribution of the electrode polarization effect in the bulk properties . The spectra of M ′ and M ″ for the PVA– x wt % TiO 2 nanocomposites at 30 °C are depicted in Figure .…”

Dielectric properties of irradiated polymer/multiwalled carbon nanotube and its amino functionalized form

“…Figure (a–c) shows the variation of electric modulus real parts as a function of frequency for the unirradiated and irradiated PVA, (PVA‐CEA)‐MWCNT‐NH 2 , and (PVA‐CEA)‐MWCNT samples. The low values of electric modulus ( M ′) for all samples signifies the electrode polarization . The value of the real part ( ) at lower frequencies is low and it increases and a saturated is obtained when moving to the higher frequencies region.…”

“…The peaks of the electric modulus imaginary part ( M ″) with particular frequency is shown in Figure (a–c) for the unirradiated and irradiated PVA, (PVA‐CEA)‐MWCNT‐NH 2 , and (PVA‐CEA)‐MWCNT films. The effect of MWCNT decreases the relaxation time required for dipole orientation as shown in Figure (d) . Several polymer composite films exhibit a relaxation peak in their M ″ spectra below 1 MHz corresponding to the conductivity relaxation process .…”

“…The electrical modulus corresponds to the relaxation of the electric field in the materials when the electric displacement remains constant. The electric modulus ( M ) is generally represented the reciprocal of complex dielectric modulus where represents real part and represents imaginary part of electric modulus.…”