Effect of heat in chitosan dissolution and addition of KI on the enhancement of ionic conductivity

Abstract

This work focuses on the effect of chitosan-based carbohydrate polymer electrolytes (CHPE) that were prepared by the application of heat in chitosan dissolution. Furthermore, various wt% of potassium iodide (KI) that was incorporated into this heat-applied chitosan (KI-HAC) were investigated. Electrochemical impedance spectroscopy (EIS) shows that the pure HAC has the room temperature ionic conductivity of 5.57 × 10−4 S/cm. The conductivity enhanced from 5.57 × 10−4 S/cm to 6.39 × 10−4 S/cm on the addition of 0.3 wt% of KI and further enhanced to 2.07 × 10−2 S/cm on the increment of KI from 0.3 to 1.8 wt%. The conductivity enhancement in chitosan was found due to the formation of amino glucosyl carboxonium ions (AGCI) and is due to the effect of heat in chitosan dissolution. XRD affirms the reduction in crystallinity. SEM analysis shows the spherical morphology for pure chitosan, porous morphology for HAC, and KI-HAC. FTIR confirms the degradation of chitosan and the formation of AGCI. Dielectric study, dielectric tan loss study, and dielectric modulus study confirm the results obtained by EIS. The results are authenticating that the conductivity enhancement in CHPE is not only due the addition of inorganic salt but also due to the chitosan which plays the role in conductivity enhancement. Dye-sensitized solar cell using HAC and KI-HAC shows efficiency of 1.25 and 1.62% at 1 sun condition.