Poly(ethylene oxide)-silica hybrid materials for lithium battery application

Abstract

Flexible organic-inorganic hybrid films, useful as separators in rechargeable lithium batteries, have been prepared by thermally cross-linking poly(ethylene oxide) (PEO, MW: 600 K) with colloidal silica. The colloidal silica was obtained by the hydrolysis of tetraethyl orthosilicate under the catalysis of HCF3SO3. The mechanical strength and ionic conductivity of the films are dependent on the composition and the amount of the electrolytes soaked into the films as well as the silica-content. An optimum example is that when the film composed of 65% PEO and 35% colloidal silica is immersed in an electrolyte (1EC:1DME+12 wt.% LiCF3SO3) for 3 min at 45 °C, the amount of the electrolyte intake is eight times the original weight of the film and the ionic conductivity is similar to that of the electrolyte (2 mS/cm).