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

Flexible organic-inorganic hybrid films, useful as separators in rechargeab le lithium batteries, have been prepared by thermally cross-linking poly(et hylene oxide) (PEO, MW: 600 K) with colloidal silica, The colloidal silica was obtained by the hydrolysis of tetraethyl orthosilicate under the cataly sis of HCF3SO3. The mechanical strength and ionic conductivity of the films an 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 wh en the film composed of 65% PEO and 35%c colloidal silica is immersed in an electrolyte (1EC:1DME + 13 wt.% LiCF3SO3) for 3 min at 45 degrees C, the a mount of the electrolyte intake is eight times the original weight of the f ilm and the ionic conductivity is similar to that of the electrolyte (2 mS/ cm). (C) 1999 Elsevier Science B.V. All rights reserved.