Structural, thermal, and electrochemical studies on PVA-LiTf-TiO2 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 LiCF3SO3) at 60:40 weight ratios with varying weight percentages (wt.%) of titanium (IV) oxide (TiO2) nanofiller were prepared by solution casting technique. The most conductive nanocomposite polymer electrolyte which was added with 10 wt.% of TiO2 nanofiller has an ionic conductivity of (1.08 +/- 0.002) x 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 TiO2. 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.% TiO2 nanofiller is attributed to the interaction between TiO2 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 TiO2 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.

Automated summary

Polymer electrolyte systems composed of poly(vinyl alcohol) (PVA) and lithium trifluoromethanesulfonate (LiTf) with TiO2 nanofiller were prepared by solution casting technique. The addition of TiO2 nanofiller resulted in a more conductive and thermally stable polymer electrolyte. The interaction between TiO2 nanofiller and polymer matrix improved the rigidity of the polymer. An electrical double layer capacitor (EDLC) fabricated using the nanocomposite polymer electrolyte showed good electrochemical stability and specific capacitance.