Preparation and characterization of PVA/PAM/NH4SCN polymer film by ultrasound-assisted solution casting method for application in electric double layer capacitor

The structural analysis of PVA/PAM blend polymer electrolytes made in the different ratio of 70: 30, 50: 50 and 30: 70 by ultrasound-assisted solution casting technique shows a good miscibility between the polymers. The different weight percentage of ammonium thiocyanate (NH 4 SCN) salt as an ionic dopant was added to the PVA/PAM (50: 50) blend film and tested for the structural changes, electrical and electrochemical properties. The 50 wt% PVA-50 wt% PAM-20 wt% NH 4 SCN (UN20) blend film prepared in the presence of ultrasound exhibits a high conductivity value of 1.66 × 10 −4 S cm −1 , whereas the above blend membrane prepared in the absence of ultrasound (WN20) exhibits a conductivity value of 3.98 × 10 −5 S cm −1 . The electric double–layer capacitor (EDLC) fabricated using the activated carbon as the electrode and the film UN20 as the polymer electrolyte exhibited a specific capacitance value of 1230 mF g −1 as observed by the cyclic voltammetry studies, whereas the EDLC made with the film WN20 exhibited a poor specific capacitance value of 293 mF g −1 . The charge-discharge studies of the device made using the film UN20 was found to exhibit a first cycle discharge capacitance of 2562 mF g −1 for a current load of 1 mA in the voltage range of 0–1 V. The reasons for the changes in the properties of the films prepared in presence and in absence of the ultrasound and its effect in performance of EDLC were discussed.