Ion association as a main shortcoming in polymer blend electrolytes based on CS:PS incorporated with various amounts of ammonium tetrafluoroborate

Abstract

This work presents a successfulness of the methodology of solution cast technique for fabrication of polymer blend electrolytes based on chitosan (CS): potato starch (PS) doped with various amounts of ammonium tetrafluoroborate (NH4BF4). In this work we demonstrated that association of ions is the main drawback for the NH4BF4 salt. Low DC conductivity of the films displays the non availability of the present system for applications. To look at the electrical properties, structural, and morphological properties, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), and Field emission scanning electron microscopy (FESEM), respectively were used. From the EIS measurement the highest conductivity of the system was found to be 3.07 × 10−8 S/cm which is too low for device applications including batteries and supercapacitors. The increase of bulk resistance is an indication for the recombination of cation and anion of the salt at high concentration. Sharp peaks were observed in the XRD spectra at high salt concentration. The morphological outcomes display protruded salts with large size at high salt concentration. The large value of dielectric constant at low frequency region is associated to electrode polarization (EP) while their decline with increasing frequency is ascribed to the lag of polarization of ion with respect to the quick orientation of dipole species because of the applied AC field. The M″ peak asymmetry displays the distribution of relaxation time.

Keywords

• Polymer blend electrolytes
• XRD and FESEM
• Ion association
• EIS analysis
• Dielectric constant
• Electric modulus