Study on electrochemical properties of CMC-PVA doped NH₄Br based solid polymer electrolytes system as application for EDLC

In the present work, solid polymer electrolytes (SPEs) based CMC-PVA blend doped with various contents of NH₄Br were successfully prepared via solution-casting technique. The prepared samples were then characterized with respect to its thermal and conduction properties by using differential scanning calorimetry (DSC) and impedance spectroscopy. The highest dc conductivity at room temperature is observed to be 3.21 × 10⁻⁴ S cm⁻¹ for a sample that consists of 20 wt.% NH₄Br which demonstrated good thermal stability of T_g. The CMC-PVA doped NH₄Br recorded an increment on the ionic conductivity with the increase in temperature, and thus obeys the Arrhenius behavior. The potential window for the highest conducting sample was found to be plateaued at 1.55 V. The performance of the EDLC fabricated with highest ionic conducting CMC-PVA doped NH₄Br was also examined through cyclic voltammetry (CV) and it was shown that the specific capacitance increased as the scan rate reduced. Based on the charge-discharge profile, it is apparent that the proposed system has excellent cyclic retention as it is able to keep the performance of the EDLC at ~88% even after 1000 cycles.