Poly(ε-caprolactone)-based polymer electrolyte for electrical double-layer capacitors

Abstract

The potential of electrical double-layer capacitors (EDLCs) fabricated from symmetry activated carbon electrodes and poly(ε-caprolactone) (PCL)-based polymer electrolytes (PE) have been studied. PEs that consisted of PCL, ammonium thiocyanate, and ethylene carbonate (EC) were prepared by solution casting. In this system, EC was added as a plasticizing solvent to improve the conductivity. The room temperature ionic conductivity of PE increased from 3.94 × 10−7 S cm−1 to 3.8 × 10−5 S cm−1 at 50 wt% EC. In the structural studies carried out by X-ray diffraction, it was found that addition of EC reduces the degree of crystallinity of the entire system. Temperature-dependent conductivity studies showed that Vogel–Tamman–Fulcher model fits very well with regression value close to unity. This observation demonstrates a close coupling between the ionic motion and the polymer segment mobility. The preliminary result of EDLC cell was evaluated by cyclic voltammetry. The single-electrode specific capacitance of EDLC is obtained to be 42.4 F g−1.