Ion conduction in chitosan-starch blend based polymer electrolyte with ammonium thiocyanate as charge provider

Abstract

The global issue of environmental pollution has become the motivation for researchers to develop natural based products. Researchers start to substitute synthetic polymers with natural polymers as host and ammonium salts instead of lithium salts for electrolyte application due to biodegradable, safer to handle and low in cost. In this work, a green polymer electrolyte system is prepared by blending 80 wt.% starch and 20 wt.% chitosan with ammonium thiocyanate (NH4SCN) as dopant salt. The highest room temperature conductivity of (1.30 ± 0.34) × 10−4 S cm−1 is obtained when the starch–chitosan blend is doped with 30 wt.% NH4SCN electrolyte which is found to obey Arrhenius rule. The deconvolution of Fourier transform infrared (FTIR) analysis has proved the molecular interaction between starch, chitosan and NH4SCN. The number density (n), mobility (μ) and diffusion coefficient (D) of ions are found to be affected by NH4SCN concentration. This result is further supported by the XRD sample with 30 wt.% NH4SCN which exhibited the most amorphous structure with the lowest degree of crystallinity. Conduction mechanism for the highest conducting electrolyte follows correlated barrier hopping (CBH) model.