Di-urea cross-linked poly(oxyethylene)/siloxane ormolytes for lithium batteries

Abstract

Poly(oxyethylene)( POE)/siloxane hybrids (di-ureasils) doped with a wide concentration range of lithium triflate were investigated. The host matrix of these materials (d-U(2000)) is a sol-gel derived siliceous network to which POE chains with about 40 repeat units are bonded through urea linkages. Xerogels with n between 500 and 5 (where n is the molar ration of OCH2CH2 repeat units to lithium íons) were obtained as amorphous monoliths thermally stable up to at least 340ºC. A crystalline POE/LiCF3SO3 complex was detected spectroscopically in samples with compositions of n less than 10. Below 90ºC the ormolyte with n = 20 exhibits the highest ionic conductivity of the series characterized. The redox stability of this material is about 4.1 volts.