Electrical conductivity and dielectric behaviour of PPG4–AgCF3SO3:Al2O3 nanocomposite gel polymer electrolyte system

Abstract

In this report, the synthesis of solvent-free poly(propylene glycol) 4000 (PPG4)–silver triflate (AgCF3SO3):xAl2O3 nanocomposite gel polymer electrolytes containing four different amounts of Al2O3 nanoparticles corresponding to x = 1, 3, 5 and 7 wt.%, respectively, with an ether oxygen-to-metal cation ratio (O–M) of 4:1 together with their vibrational spectroscopic characteristics derived from Fourier transform infrared (FT-IR ) spectroscopic analysis at room temperature (25 °C) is described. Furthermore, a detailed investigation concerning their mechanism of ion transport performed by means of complex impedance analysis in the frequency range 20 Hz to 1 MHz and over the temperature region 25–90 °C and analysed in terms of electrical conductivity spectra, electrical modulus spectra and impedance spectra has indicated that the typical composition PPG4–AgCF3SO3:5 wt.% Al2O3 would exhibit the best room temperature electrical conductivity of 6.2 × 10−4 S cm−1 owing to the mobility of coordinated silver cations through the mechanism of enhanced segmental motion of the PPG4 polymer chains as aided by the various coordinating sites available within the polymer network. It is also demonstrated from the present FT-IR results that significant changes in the intensity, shape and position of the different vibrational bands corresponding to –OH stretching, C–O–C stretching, C–H stretching and C–O–C in C–H stretching modes occur as a result of the incorporation of Al2O3 nanofiller particles into the PPG4–AgCF3SO3 complex. It is evident from the conductivity data that the observed enhancement in electrical conductivity would result from appropriate changes in ionic association occurring in the form of probable ion–ion and ion–polymer interactions involving Al2O3 nanofiller additive in accordance with the Lewis acid–base model of polymer–salt–filler interactions.