Polymeric membranes of poly(ethylene oxide) (PEO) and sodium trifluoroacetate (PEO:CF3COONa) combined with different concentrations of aluminum oxide (Al2O3) particles were analyzed by impedance spectroscopy, differential scanning calorimetry (DSC) and thermogravimetry (TGA). DSC results show changes in the crystalline fraction of PEO when the concentration of Al2O3 is increased. TGA analysis showed thermal stability up to 430 K showing small changes with the addition of alumina particles. The decrease in crystalline fraction for membranes with low Al2O3 concentration is associated with the increase in conductivity of (PEO)10CF3COONa + x wt.% Al2O3 composites.

To increase the ionic conductivity of solid polymer electrolyte, (PEO)10CF3COONa, we formed new composites by adding alumina particles as a filler. We prepared these composites by dissolving them in a liquid solvent, and characterized them through impedance spectroscopy (IS), using a Pt/electrolyte/Pt electrode configuration. The combination of polyethylene oxide (PEO) with sodium trifluoroacetate (CF3COONa) produced a reduction in resistance of up to two orders of magnitude in Nyquist plots, and up to three orders of magnitude when we added Al2O3 particles at room temperature. DC conductivity concentration graphs show an increase in the ionic conductivity with low alumina concentrations. The new synthesized ionic conductor composite presented conductivity values of 2.00x10-5 Scm-1 at room temperature and of 7.70x10-4 Scm-1 at a temperature of 383 K. Two sections of the conductivity diagrams also evidenced a temperature induced Arrhenius behavior, indicating a thermally activated process. Higher concentrations of Al2O3 induced a Vogel-Tamman-Fulcher (VTF) behavior. Conductivity variations produced by Al2O3 concentration are linked to the number of sites involved in ion transport between Al2O3 ionic electrolyte species through Lewis acid-base interactions.

Polyvinylidene fluoride (PVDF) and hypophosphorous acid (H3PO2) are combined to synthesize solid polymer electrolyte membranes using the solution cast method. Electrochemical impedance spectroscopy measurements are used to find the conductivity, and those values are plotted as a function of relative humidity (% RH) to which the membranes are kept. In agreement with the modified Onsager, the results show growth in conductivity as % RH increases, which states that ionic mobility of a polar polymeric phase increases as levels of absorbed water by the polymeric membrane increase. The high values of conductivity observed at high concentrations of H3PO2 (σ = 9.83 × 10−3 S cm−1 for x = 60% wt) are attributed to the increase of charge carriers and the dissociation of ions in an aqueous phase. The synthesized membranes are tested as electrolytes in a fuel cell and the voltage and power density plotted as a function of the current density with maxim values of the power density of 2.88 mW cm−2 for a 30% wt membrane.