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Alkaline solid electrolyte membranes, based on the poly(vinyl alcohol) (PVAL), lithium hydroxide (LiOH) and water with various salt concentrations have been synthesized. These systems have anhydridous ionic conductivity (σ) as high as 2,9 x 10 -4 Scm -1 at room temperature and show a linear dependence of ln(σ) with 1/T below 80 °C. The thermal analysis indicated three transformations in the blends: at 205, 150 and -125 °C, associated with decompositions, melting point and glass transition of the polymer blends, respectively. The X-ray spectra for the samples at room temperature show a peak at about 2θ = 20° for all salt concentrations and whose intensity depends on the amorphous character of the system. The results are discussed in terms of the high mobility of the Li + ions in the amorphous phase of the complex.

In the present work, the electrical and thermal characterization of polymer electrolytes based on PEO/CF3COONa are reported, which turn out to be good ionic conductors near room temperature (of the order 10—4 Ω—1 cm—1 for high salt concentrations). The variation of conductivity with temperature (plotted as ln σ versus 1/T) and salt concentration suggests a complex formation. This is confirmed by differential scanning calorimetry (DSC), which also indicates that the blends are thermally stable up to approximately 480 K. The high conductivity and the single‐phase behavior of the blends are explained in terms of the plastification effect of the organic salt on the PEO.

Solid polymer electrolytes consisting of poly(ethylene oxide) PEO and lithium trifluroacetate (CF 3 COOLi) with various salt mass fractions were prepared by the solvent casting method using acetonitrile. Temperature and concentration dependent impedance spectroscopy, as well as thermal analysis suggest the existence of a complex in the blends with an EO/Li ratio corresponding roughly to 4:1. The dc conductivity (σ 0 ) of the blends were very sensitive to the temperature (T) and their salt mass fraction (x), showing values in the range of 10-5 to 10-2 (S cm -1 ) at 330 K as the salt concentration was increased. The enhancement of conductivity with increasing temperature (5 orders of magnitude when the temperature changes from 300 to 353 K) was attributed to the high mobility of the Li + ions as a consequence of the chain polymer flexibility and the increase of the free volume for ionic migration.

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