Ionic conduction and relaxation processes in melt compounded poly(ethylene oxide)-lithium perchlorate trihydrate-montmorillonite nanocomposite electrolyte

摘要

Polymer nanocomposite electrolyte (PNCE) films comprising complexes of poly(ethylene oxide) (PEO) and lithium perchlorate trihydrate (LiClO_43H_2O) filled with nano thickness platelets of montmorillonite (MMT) clay up to 20 wt% concentration of PEO are synthesized by melt compounding hot-pressed technique at 70°C and 105°C. Complex dielectric function, electric modulus, alternating current electrical conductivity and impedance behaviour of these PNCE films have been investigated in the frequency range 20 Hz to 1 MHz at ambient temperature. The direct current ionic conductivity of the PNCE films initially increases up to 2 wt% MMT loading and vary anomalously at higher concentrations. The PNCE films synthesized at 105°C have ionic conductivity nearly one order of magnitude higher than that of synthesized at 70cC. Relaxation times corresponding to electrode polarization and ionic conduction relaxation processes in the PNCE films are determined from the values of peak frequencies of the dielectric loss tangent and electric modulus loss spectra, respectively. Results confirm that the ionic conductivity of the PNCE films are governed by the PEO chain dynamics, electrode polarization and ionic conduction relaxation times, and also the structures of dispersed exfoliated/intercalated MMT nano platelets in PEO matrix and the material melt compounding temperature.