Spectroscopic characterization of a gel polymer electrolyte of zinc triflate and polyacrylonitrile

Abstract

Fourier transform Raman spectroscopy has been used to understand the changes in the zinc ion co-ordination in the gel polymer electrolyte comprising polyacrylonitrile (PAN), ethylene carbonate (EC), propylene carbonate (PC) and zinc triflate (ZnTr). The metal ions tend to co-ordinate with the solvents that manifest in the form of a shift in the wavenumbers of the ring-breathing vibrational mode of the EC. Band shape analysis clearly indicates a strong interaction of the metal ion with the plasticizers. Once the plasticizer is removed, an interaction between the metal ions and the polymer matrix is observed that manifests in the splitting and shift of CN stretching band to higher wave numbers. Presence of ion-pairs and aggregates is confirmed by analyzing the triflate-stretching band. Curve fitting analysis clearly separates out different ionic components. A correlation between the ionic conductivity values and their variation with respect to increasing salt concentration has been found and it is in tune with the spectroscopic results.