Composite protonic solid electrolytes in the CsHSO 4-SiO 2 system

Abstract

Transport, thermal and structural properties of the composite solid electrolytes (1 − x)CsHSO 4xSiO 2 (where x = 0–0.8) were investigated. The composites were prepared by mechanical mixing of components followed by heating at temperatures near CsHSO 4 melting point (483 K). The dependence of low temperature phase conductivity on x has a maximum with a value 2.5 orders of magnitude higher than that of pure CsHSO 4 and conductivity is governed by protons. Heterogeneous doping is shown to change markedly the thermodynamic parameters of the ionic component. The phase transition temperature CsHSO 4 in the composites decreases from 414 to 350 K with the increase of the content of heterogeneous additive SiO 2 from 0 to 0.7. As x raises CsHSO 4 the amorphization takes place and the relative change of ionic conductivity at phase transition diminishes, the phase transition becomes diffusive and disappears for the 0.2CsHSO 40.8SiO 2 composite.