Enhanced ionic conductivity of electrospun nanocomposite (PVDF-HFP + TiO2 nanofibers fillers) polymer fibrous membrane electrolyte for DSSC application

Electrospun pure polymer poly(vinylidene difluoride-co-hexafluoropropylene) [P(VDF-HFP)] fibrous membrane (esPFM) and electrospun nanocomposite polymer [P(VDF-HFP) + TiO2 nanofibers fillers (2, 4, 6, and 8 wt%)] fibrous membranes (esNCPFMs) were prepared using electrospinning technique. All the prepared fibrous membranes were soaked in an optimized electrolytes [0.1M of each LiI/NaI/KI/TBAI + 0.6M BMII + 0.05M I-2 + 0.5M of tert-butyl pyridine + (acetonitrile: (EC: PC) (1:1v/v)) (60:40)] solutions to obtain esPFM and esNCPFMs electrolytes and were characterized using differential scanning calorimetric (DSC), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscope (SEM) techniques. Also, an electrolyte uptake behavior and ionic conductivity of all the prepared esPFM and esNCPFMs electrolytes samples were studied, respectively, using the calculated electrolyte uptake data and the resistance evaluated from the analysis of measured impedance data of each sample. The electrospun nanocomposite polymer (PVDF-HFP + 6 wt% TiO2 nanofibers fillers) fibrous membrane electrolyte with LiI showed highest conductivity of 1.87 x 10(-2) S/cm at room temperature, which was very good, compared to the liquid electrolyte systems. Transference number studies showed that the charge transport in the highest conducting 6 wt% of TiO2 nanofibers fillers of the esNCPFM sample with LiI is predominantly due to ions and has negligible electronic contribution. Hence, the newly developed high ionic conducting electrospun nanocomposite polymer (PVDF-HFP + 6 wt% TiO2 nanofibers fillers) fibrous membrane with LiI can be a better electrolyte for developing high-efficiency dye-sensitized solar cells (DSSCs) application. POLYM. COMPOS., 40:1585-1594, 2019. (c) 2018 Society of Plastics Engineers