A single polymer electrolyte incorporating tributyl methyl phosphonium iodide for energy storage and conversion applications

A novel polymer electrolyte system based onPoly(vinylidene-co-hexaflouropropylene) (PVdF-HFP), sodium iodide (NaI), and Tributyle Methyl Phosphonium Iodide (TMPI) ionic liquid has been successfully synthesized via the solution casting technique. Electrochemical impedance spectroscopy (EIS) indicated enhanced ion transport conductivity of 9.10 × 10 − 4 S/cm, by doping ionic liquid (TMPI) and showed well correlation with dielectric data. The addition of TMPI improves the flexibility of the polymer matrix and helps in better salt dissociation, which increases ion movement in the electrolyte. It also enhances the amorphous nature of the system, leading to improved performance. The ionic transference number (t ion ) measurements suggested predominantly ionic conduction while potential sweep voltammetry (LSV) established a wide electrochemical stability window of 4.39 V. Structural analysis was done using Fourier transform infrared spectroscopy (FTIR) while Dielectric data obey the same pattern as we observed in conductivity measurement. Morphological insights using polarized optical microscopy (POM) shows reduced crystallinity and enhanced amorphousness which is well assisted quantitatively by our differential scanning calorimetry (DSC) measurement. Highest conducting polymer electrolyte is used for dual energy application, namely electrical double layer supercapacitor (EDLC) and dye sensitized solar cells (DSSC). A flexible EDLC was fabricate, which shows good electrochemical performance, while dye sensitized solar cell (DSSC) shows efficiency of 2.80% at 1 sun condition.