Nano-sized titanium dioxide-reinforced poly(vinyl alcohol) (PVA) nanocomposite polymer electrolyte (NCPE) as proton conductor in electric double layer capacitor (EDLC)

Abstract A solution-casted poly(vinyl alcohol)/ammonium acetate/titanium dioxide (PVA/CH 3 COONH 4 /TiO 2 ) nanocomposite polymer electrolyte (NCPE) exhibits an enhancement in ionic conductivity from 1.91 × 10 −4 S/cm to 4.60 × 10 −4 S/cm upon doping of 10 wt% of nano-sized TiO 2 and follows a Grotthuss-type proton conduction mechanism. Fourier Transform Infrared (FTIR) study confirms the complexation among PVA, CH 3 COONH 4 and TiO 2 . The NCPE exhibits a wide electrochemical window of 4.66 V and demonstrates thermal stability up to 700 °C, as shown in linear sweep voltammetry (LSV) and thermogravimetric analysis (TGA), respectively. The transference number analysis demonstrates that the proton is the charge carrier in the conduction mechanism, and doping of nano-sized TiO 2 improves the ionic mobility and ionic diffusion coefficient. Differential scanning calorimetry (DSC) results show that the glass transition temperature ( T g ) is only affected by the impregnation of CH 3 COONH 4 , while doping of nano-sized TiO 2 has a negligible effect on T g . Electric double layer capacitors (EDLCs) were fabricated using filler-free SPE and the most conducting NCPE with two identical carbon-based electrodes. Cyclic voltammetry (CV) analysis shows that doping of nano-sized filler improves the specific capacitance ( C sp ) from 1.05 to 11.35 F g −1 . Galvanostatic charge-discharge (GCD) shows good cycling stability up to 500 cycles.