Résumé
The topical demand in all-solid lithium-ion batteries suitable for portable consumer electronic devices has triggered extensive research on more and more sophisticated polymer electrolyte membranes (PEM).This PhD work deals with the synthesis and the mechanical, thermal and structural characterization of new nanocomposite PEM arising from the sol-gel cross-linking of PEO chains end-capped with alkoxysilane groups. Thus, the polysilsesquioxane nano-domains formed by hydrolysis-condensation reactions form a high density of cross-links and play the role of nanocharges, giving rise to mechanical resistance, which allows incorporating high amounts of plasticizer. Moreover, sol-gel process allows the functionalization of these nanodomains with lithium sulfonate or perfluorosulfonate groups, which supply Li+ charge carriers homogeneously dispersed throughout the membrane. In addition the immobilization of the anions via covalent bonds prevents them from contributing to the overall conductivity, thus ensuring a single-ion conduction, which is a compulsory condition to prevent the further formation of lithium dendrites on charge-discharge cycles. The ionic conductivity study of the membranes, in the dry state or after swelling in propylene carbonate, was done. It led to discuss the dynamics of lithium cation in the nanocomposite membranes and the possible ways to improve their conduction performances.