Effect of ammonium thiocyanate (NH4SCN) concentration on the ionic transport in dextran-based polymer electrolyte

Abstract

Solid polymer electrolytes (SPEs) have been recognized as a preferable alternative to liquid electrolytes for energy storage application. However, low conductivity of SPEs has restricted their application. This issue can be overcome by adding controlled amount of dopant salt to the SPEs. In this work, various concentration of ammonium thiocyanate (NH₄SCN) salt was incorporated into dextran using solution cast technique in order to study the effect of NH₄SCN on electrical properties, crystallite size, morphology and ionic conductivity. Results from Fourier-transform infrared (FTIR) analysis confirm the coordination of cation of salt at the OH and C-O-C groups of dextran. Deconvolution of the FTIR band between 2015 and 2090 cm⁻¹ was performed to investigate the ion association and dissociation phenomena. It is confirmed that the ion mobility and diffusion are directly proportional to the ionic conductivity. Based on the electrochemical impedance spectroscopy (EIS) result, an optimum ionic conductivity of (3.18 ± 1.19) × 10⁻⁴ S cm⁻¹ was achieved with the sample containing 40 wt.% salt concentration. The conductivity result can be clarified by the crystallite size obtained from X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FESEM) images.

Keywords:

• Ammonium thiocyanate
• dextran
• ionic transport
• solid polymer electrolyte

Conflict of interest

The authors declared there is no conflict of interest in this work.

Additional information

Funding

The authors would like to thank Universiti Teknologi PETRONAS for the Joint Research Project (015MD0-081). M.F.Z. Kadir wishes to thank the Malaysia Ministry of Higher Education (MOHE) for the Fundamental Research Grant Scheme (FRGS) (FP080-2022).