Nanocomposite polymer gel with dispersed alumina as an efficient electrolyte for application in supercapacitors

A nanocomposite polymer gel electrolyte (NCPGE) has been synthesized from polyvinylidene fluoride co-hexafluoropropylene (PVDF-HFP) as the host polymer, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizers, and tetraethylammonium tetrafluoroborate (TEABF4) as an ionic salt by a solution-casting technique, followed by the addition of Al2O3 nanoparticles. The optimal loading of Al2O3 giving the highest ionic conductivity of 6.0 × 10−3 S cm−1 was found to be 18 wt%. An activation energy of 0.107 eV has been calculated from a temperature-dependent conductivity plot, which shows Arrhenius behavior. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) characterizations have been applied to investigate the morphology and structure. The semi-crystalline and porous nature of the NCPGE has been confirmed by SEM and XRD analyses. The ionic transference number was calculated as 0.98 by the DC polarization technique, confirming the dominant ionic nature of the prepared electrolyte. The electrochemical potential window of the NCPGE of about 3.4 V, as estimated by linear sweep voltammetry, makes it suitable for supercapacitor applications. [Display omitted] •A nanocomposite polymer gel electrolyte (NCPGE) with an optimized composition [1:4 {PVDF-HFP + EC-PC-TEABF4} + Al2O3 (18 wt%)] has been synthesized.•The optimized NCPGE showed a high conductivity of 6.0 × 10−3 S cm−1.•An ionic transference number of 0.98 has been measured for the NCPGE, and its estimated electrochemical potential window is 3.4 V.•Impedance spectroscopy, cyclic voltammetry, and galvanostatic charge–discharge techniques are used for performance evaluation of the NCPGE used in a supercapacitor cell.