Preparation and properties of solid polymer electrolytes based on poly(ethylene glycol) monomethyl ether acrylate with inorganic fillers for supercapacitors

Abstract

This study investigated the effect of different types of ionic liquids on electrolytes and structural capacitors, then investigated the effect of inorganic fillers on electrolytes and structural capacitors by adding inorganic fillers to samples of relatively good performance. In this study, solid polymer electrolytes (SPEs) were composed of poly (ethylene glycol) monomethyl ether acrylate (PEGA) as a structure material and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIm][OTF]), 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl) imide ([EMIm] [TFSI]) as an ionic liquid. Fumed silica was added an inorganic filler. Two types of fumed silica were used. One has unmodified surface, and the other has organically modified surfaces. The modified silica was synthesized under acidic conditions using methacryloxypropyl trimethoxy silane (MAPTMS). The modified silica was prepared with different MAPTMS feeding ratios. The ratio of MAPTMS to silica were 0.5:1, 1:1, and 2:1. The structural capacitors were prepared by a vacuum-bag process using glass-fiber/carbon-fiber prepregs. Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy in the attenuated total- reflectance mode (FTIR-ATR), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and the galvanostatic charge-discharge test were performed to investigate the effect of ionic liquid and inorganic filler on the thermal and electrochemical properties of solid polymer electrolytes. The SPEs were formed by adding PEGA and ionic liquids before thermal curing. The ratios of PEGA and ionic liquids were 9:1, 7:3 and 5:5. The ionic conductivities of SPEs based on PEGA[OTF]_S0 series were 5.7․10-4 and 4.8․10-4 S/cm, respectively and the specific capacitances of SPEs based on PEGA[OTF]_S0 series were 10.0 and 9.5 F/g. The specific capacitance of structural capacitors for ionic liquid with a large ion size was lower than that for ionic liquid with a smaller ion size. The ionic conductivity and specific capacitance of SPEs with inorganic fillers were lower than those of neat SPEs.