Effect of Prolonged Duration of Gelatinization in Starch and Incorporation with Potassium Iodide on the Enhancement of Ionic Conductivity

Abstract

ABSTRACTThree systems of starch-based crust electrolytes were prepared using various gelatinization times, various weight percentages (wt%) of starch, and various wt% of starch incorporated into potassium iodide. All the samples were subjected to electrochemical impedance spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and transference number measurements. Electrochemical impedance spectroscopy shows that 1.7 wt% of starch has maximized the room temperature conductivity of the electrolyte to 1.4587 × 10−4 S cm−1. The conductivity was enhanced to 4.5278 × 10−4 S cm−1 on the increment of starch’s wt% from 1.7 to 3.2. This conductivity was further enhanced to 3.4609 × 10−3 S cm−1 on the addition of 0.3 wt% of potassium iodide. The conductivity enhancement was found due to the formation of glucosyl carboxonium ions. The effect of longer heating time in gelatinization is attributed to the formation of glucosyl carboxonium ions. X-ray diffraction spectroscopy affirms the reduction in crystallinity of starch. Scanning electron microscopy analysis shows the porous morphology of starch electrolyte, and addition of potassium iodide shows the morphology of bean nuts like particles seated on the pores. Fourier transform infrared confirms the degradation of starch. Transference number measurements of the crust electrolyte shows that ions are the dominant conducting species. All the results are authenticating that the conductivity enhancement in starch-based crust electrolyte is due to starch and the addition of inorganic salts.