IONIC-CONDUCTIVITY OF A POLYMER ELECTROLYTE WITH MODIFIED CARBONATE AS A PLASTICIZER FOR POLY(ETHYLENE OXIDE)

A new type of plasticizer, a modified carbonate (MC3) made by attachin g three ethylene oxide units to the 4-position of ethylene carbonate, has been synthesized. The ionic conductivity of a polymer electrolyte using this type of plasticizer in a poly(ethylene oxide) (PEO)-LiCF3SO 3 complex has been studied. Adding 50% of this plasticizer by weight o f PEO to the PEO-LiCF3SO3 complex, yielded an ionic conductivity of 5 x 10(-5) S/cm at 25-degrees-C, which is two orders of magnitude higher than that found f or a PEO-LiCF3SO3 electrolyte without a plasticizer , and one order of magnitude higher than that found when using propyle ne carbonate (PC) as a plasticizer. The temperature dependence of the conductivity and thermal analysis results indicate that this new plast icizer increases the ionic conductivity throughout the entire complex system, whereas conventional plasticizers, like PC, simply create a hi gh conductivity pathway through the plasticizer itself. The new plasti cizer also enhances the ion pair dissociation which in turn improves t he ionic conductivity