Characterization of Polymer Electrolytes Based on Poly(vinylidene fluoride-co -hexafluoropropylene) and Lithium Triflate

Solid polymer electrolytes composed of poly (vinylidene fluoridecohexafluoro propylene) (PVdFHFP) and various concentrations of lithium trifluoromethanesulfonate (lithium triflate) were prepared by the solution casting technique in order to determine the optimal composition of the lithium salt for maximum ionic conductivity. Structural changes and complex formations of the polymersalt systems were ascertained from xray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy studies. Scanning electron microscope (SEM) investigation results confirm morphological changes upon the addition of the salt to the polymer. Measurements of the temperaturedependent ionic conductivity of the electrolytes were performed in the temperature range 303 � 393 K using a DC conductivity setup. The results reveal that the ionic conductivity of the polymer electrolytes containing various salt concentrations increases with temperature and obeys the Arrhenius rule. Also, it was found that the electrolyte containing 25 wt.% of lithium triflate exhibits the highest room temperature (303 K) ionic conductivity of . The conductivity results are consistent with the structural and morphological properties of the electrolyte samples.