Thermal and transport properties of the polymer electrolyte based on poly(vinyl alcohol)‐LiOH‐H ₂ O

Abstract

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.

New polymer electrolyte based on PVAL‐LiOH‐Al2O3‐H2O

“…These results agree with the literature reports [3,4,18,19] for the glass transition temperature of PVAL, related to its sensitivity to doping level. The X-ray diffraction spectra shows a peak around 20 °C which can be interpreted by considering the Hodge et al criterion [20], establishing a correlation between the height of this peak and the degree of crystallinity of PVAL, e.g.…”

“…The DSC curves for the samples with different alumina concentrations show three anomalies, the first one as a step around 20 °C associated to the glass transition (T g ), the second one as an endothermic peak around 210 °C associated to the melting point, and the third one as an endothermic peak around 235 °C associated to the decomposition process. We can observe that the transition temperatures of the tree anomalies, due to the alumina content, shift upward to values close to www.pss-c.com those reported for the pure PVAL [4,17]. Also, we observed for the alumina concentrations y = 0.125 and 0.150, that the anomalies are smaller.…”

“…We observed that the temperature of the three anomalies reported for PVAL-LiOH [4] shifts upward to values close to that reported for pure PVAL [4] due to the alumina content. These results agree with the literature reports [3,4,18,19] for the glass transition temperature of PVAL, related to its sensitivity to doping level.…”

“…The T g of pure PVAL is around 80 o C [17]. The plastification effect of water on PVAL is well known [18], but the addition of LiOH/water causes a further drop of T g in PVAL [4]. The melting point of the complex is around 150 o C and the decomposition begins around 195 °C.…”

“…Palacios et al reported previously [3] the dissolution of KOH in poly(vinyl alcohol) and water resulting in proton conductor polymer membranes with the highest room temperature conductivity in the order of 10 -3 Scm -1 . Fernández et al [4] studied by thermal and electrical measurements of solid polymer electrolyte mem-…”