Composite polymer electrolyte based on (PEO)<inf>6</inf>:NaPO<inf>3</inf> dispersed with BaTiO<inf>3</inf>

Background: Polymer electrolytes have attracted considerable attention as regards portable solid-state electrochemical device applications. The present investigation is focused on the characterization of a new Na+ ion conducting polymer electrolyte (PEO)6:NaPO3 dispersed with 3-10 wt% BaTiO3 (0.7 μm) fillers. The composite polymer electrolytes (CPEs) were prepared by a solution-casting method and characterized using various physical measurement techniques. Results: Differential scanning calorimetry results indicate a maximum reduction in the degree of crystallinity of the polymer from 62.6% for uncomplexed poly(ethylene oxide) (PEO) to 27.6% for the CPE with 6 wt% BaTiO3. This substantiates an enhancement in the amorphous phase of the polymer inferred from X-ray diffraction and optical micrographs. The CPE dispersed with 6 wt% BaTiO3 is found to be the best composition exhibiting a maximum ionic conductivity of 1.2 × 10-6 S cm-1 at 345 K with cationic transport number (tNa+) of 0.33. Conclusions: An enhancement in the ionic conductivity of about two orders of magnitude is achieved for the composite electrolytes when compared to filler-free solid polymer electrolyte. Correlation of the temperature-dependent conductivity, activation energy for ion migration and transport number enables an understanding of the role played by the fillers in conduction characteristics of the CPEs. © 2007 Society of Chemical Industry.