Capacitive behavior studies on electrical double layer capacitor using poly (vinyl alcohol)–lithium perchlorate based polymer electrolyte incorporated with TiO2

Abstract

Electric double layer capacitors (EDLCs) based on activated carbon electrodes and poly (vinyl alcohol)–lithium perchlorate (PVA–LiClO4)-nanosized titania (TiO2) doped polymer electrolyte have been fabricated. Incorporation of TiO2 into PVA–LiClO4 system increases the ionic conductivity. The highest ionic conductivity of 1.3 × 10−4 S cm−1 is achieved at ambient temperature upon inclusion of 8 wt.% of TiO2. Differential scanning calorimetry (DSC) analyses reveal that addition of TiO2 into polymer system increases the flexibility of polymer chain and favors the ion migration. Scanning electron microscopy (SEM) analyses display the surface morphology of the nanocomposite polymer electrolytes. The electrochemical stability window of composite polymer electrolyte is in the range of −2.3 V to 2.3 V as shown in cyclic voltammetry (CV) studies. The performance of EDLC is evaluated by electrochemical impedance spectroscopy (EIS), CV and galvanostatic charge–discharge technique. CV test discloses a nearly rectangular shape, which signifies the capacitive behavior of an ELDC. The EDLC containing composite polymer electrolyte gives higher specific capacitance value of 12.5 F g−1 compared to non-composite polymer electrolyte with capacitance value of 3.0 F g−1 in charge–discharge technique. The obtained specific capacitance of EDLC is in good agreement with each method used in this present work. Inclusion of filler into the polymer electrolyte enhances the electrochemical stability of EDLC.