Structural, thermal, and electrochemical studies on PVA-LiTf-TiO 2 nanocomposite polymer electrolyte and the performance on electric double layer capacitor application

Polymer electrolyte systems composed of poly(vinyl alcohol) (PVA) and lithium trifluoromethanesulfonate (LiTf, also known as LiCF 3 SO 3 ) at 60:40 weight ratios with varying weight percentages (wt.%) of titanium (IV) oxide (TiO 2 ) nanofiller were prepared by solution casting technique. The most conductive nanocomposite polymer electrolyte which was added with 10 wt.% of TiO 2 nanofiller has an ionic conductivity of (1.08 ± 0.002) × 10 −4 S cm −1 at room temperature. The ionic transport mechanism in the nanocomposite polymer electrolyte was found to obey Arrhenius relationship which is related to thermally activated principle. Fourier-transform infrared (FTIR) study confirmed complexation between the PVA, LiTf, and TiO 2 . TGA thermogram of the most conductive polymer electrolyte shows good thermal stability which can withstand high temperature. The increase in glass transition temperature ( T g ) of PVA upon addition of 10 wt.% TiO 2 nanofiller is attributed to the interaction between TiO 2 nanofiller and polymer matrix that causes the polymeric backbone to become more rigid. Linear sweep voltammogram of the sample shows a wide potential window of 4.95 V. The ionic transference number was found to be close to unity which suggests that the charge carriers are mostly ionic species. A simple electrical double layer capacitor (EDLC) was fabricated using nanocomposite polymer electrolyte with 10 wt.% of TiO 2 nanofiller and its performance was evaluated. The EDLC was found to have specific capacitance of 444.06 mF g −1 (or 3.87 mF cm −2 ) with good electrochemical stability.