Synthesis and characterization of an electrolyte system based on a biodegradable polymer

Abstract

A polymer electrolyte system has been developed using a biodegradable polymer namely poly-ε-caprolactone (PCL) in combination with zinc triflate [Zn(CF3SO3)2] in different weight percentages and characterized during this investigation. Free-standing thin films of varying compositions were prepared by solution casting technique. The successful doping of the polymer has been confirmed by means of Fourier transform infrared spectroscopy (FTIR) by analyzing the carbonyl (C=O) stretching region of the polymer. The maximum ionic conductivity obtained at room temperature (25°C) was found to be 8.8x10–6 S/cm in the case of PCL complexed with 25 wt% Zn(CF3SO3)2 which is five orders of magnitude higher than that of the pure polymer host material. The increase in amorphous phase with an increase in salt concentration of the prepared polymer electrolyte has also been confirmed from the concordant results obtained from X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopic (SEM) analyses. Furthermore, the electrochemical stability window of the prepared polymer electrolyte was found to be 3.7 V. An electrochemical cell has been fabricated based on Zn/MnO2 electrode couple as an application area and its discharge characteristics were evaluated.

Keywords

• Biodegradable polymers
• Conductivity
• Zinc triflate
• Polymer electrolyte