NEW HIGH- CONDUCTING HYBRID CsH5(PO4)2-BUTVAR COMPOUNDS

Abstract

Hybrid polymer compounds (1–x)CsH5(PO4)2-xButvar (polyvinyl butyral brand Butvar®) (x = 0–0.3, x - weight fraction), synthesized with ethanol and isopropanol as solvents, studied using the electrochemical impedance method, powder X-ray diffraction analysis (XRD hereinafter), differential scanning calorimetry, and electron microscopy. A more optimal synthesis method was determined and the fundamental possibility of creating new highly conductive thin polymer electrolytes based on CsH5(PO4)2 was shown. The crystal structure of the CsH5(PO4)2 (P21/c) salt remains unchanged in the polymer hybrid system, but dispersion and partial amorphization of salt were observed during synthesis. It was found that, to achieve the highest proton conductivity of (1–x)CsH5(PO4)2-xButvar, the most preferable method of synthesis is the precipitation of the salt, from the starting components, in the presence of a solvent common with the polymer. The most optimal is the method of salt precipitation from a polymer solution in ethanol as a common solvent with further tape casting. The thickness of polymer electrolytes is no more than 50–100 μm. Proton conductivity increases by 2 orders of magnitude relative to the initial salt and depends on composition, uniformity of salt distribution in the polymer volume, and the presence of residual humidity during electrolyte synthesis. The highest proton conductivity was 10-2 S/cm at 130 °C at low humidity conditions. Changes in the electrotransport characteristics of the system are caused by dispersion and partial amorphization of the salt, as well as by the presence of insignificant amounts of residual water molecules on the salt surface under the conditions of the synthesis of polymer compositions.