Ionic conductivity of polymer-ceramic composites

The paper analyzes ionic conductivity data in the PEO:LiBF4-MgO and PEO:LiBF4-BaTiO3 composite electrolyte systems. The polymer and ceramic phases in the systems interact to provide a stable, amorphous phase. The ceramic phase is believed to impart a dual effect. It suppresses crystallization of and interacts with the polymer phase. The nature of the interaction is believed to be dipole-dipole and driven by a dielectric constant gradient. The nanosize ceramic powder provides higher conductivity values because of an enhanced interaction. At low temperatures (similar or equal to 20 degreesC) the dipole-dipole interaction is favored, whereas at high temperatures (similar or equal to 100 degreesC) a reverse trend is observed. A very high dielectric constant material such as BaTiO3 provides little additional benefit. (C) 2001 The Electrochemical Society.