Solid polymer electrolytes based on poly(vinyl alcohol) incorporated with sodium salt and ionic liquid for electrical double layer capacitor

Solid polymer electrolyte (SPE) based on poly(vinyl alcohol) (PVA) as a host polymer, sodium trifluoromethanesulfonate (NaTf) salt, and 1-butyl-3-methylimidazolium bromide (BmImBr) ionic liquid is fabricated using solution casting technique. The ionic conductivity, crystallinity, composition and thermal stability were characterized by electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), respectively. The optimum ratio between PVA and NaTf salt to obtain highest ionic conductivity was found to be as 60:40. The inclusion of BmImBr ionic liquid into the optimized PVA-based SPE significantly enhanced the ionic conductivity. XRD pattern indicated the successful dissolution of NaTf salt and complexation of BmImBr ionic liquid in the host polymer which has also been confirmed by FTIR spectra. The thermally stable SPE is suitable for electrical double layer capacitor (EDLC) application. The electrochemical studies of GPE for EDLC showed promising performance producing specific capacitance of 16.32 F g(-1).