EIS and FTIR Characterisation of NaI-NaN(CN)<sub>2</sub> Solid Electrolyte Prepared by Mechanical Milling

Abstract

Conductivity of sodium based solid electrolyte xNaI-(100 - x)NaN(CN)2 with various compositions (0 ≤ x ≤ 70) were investigated by Electrochemical impedance spectroscopy (EIS) method in order to determine the conductivity value. Maximum conductivity of 10-4 S cm-1 was obtained for sample with 10 wt.% NaI. The improved conductivity could be due to presence of dicyanamide as an anionic-bridging ligand compound that provided conducting pathway for rapid Na+ ion conduction. The binary sodium solid electrolyte system was prepared by ball milling method with 200 rpm for 2 hours in order to promote ultra-fine size reduction and introducing defects in the crystal structure thus assisting rapid ionic mobility via hopping. Results obtained from Fourier transform infrared spectroscopy (FTIR) characterisation showed some changes in infrared spectrum peak appearance within wavenumber region of 2200 – 2500 cm-1 that had proven some weak intermolecular interaction at the terminal N (nitrile) atoms of the dicyanamide.