Keywords: Polymer electrolyte; polymer blend; ionic liquid; salt

Abstract

Chitosan/methylcellulose/1-butyl-3 methyl imidazolium bis (trifluoromethylsulfonyl) imide (BMIMTFSI) biopolymer electrolyte has been prepared via solution casting technique by doping with different weight percentages of ammonium triflate (NH₄CF₃SO₃) salt. The films were characterized by impedance spectroscopy to measure the ionic conductivity. Samples with 25 wt.% of NH₄CF₃SO₃ exhibited the highest conductivity of 7.64 × 10^-4 S cm^-1 at ambient. Dielectric data showed that the increase in conductivity could be due to the increase in the number of charge carriers, while modulus study confirmed the non-Debye behaviour. Temperature dependence study showed that the polymer electrolyte system obeyed the Arrhenius rule. Conduction mechanism analysis showed that this system matched the Quantum Mechanical Tunnelling (QMT) behaviour. X-ray Diffraction (XRD) spectra, which had been deconvoluted using Origin 8 software disclosed that samples with the lowest degree of crystallinity (X_c %) obtained the highest ionic conductivity. On the other hand, Fourier Transform Infrared (FTIR) spectra, which were also deconvoluted using the same software showed that samples with the highest ionic conductivity had the highest number of mobile ions in this system.