Ion dissociation and conduction of Nafion/modified oligo(oxyethylene) composite films

In order to improve the ionic conductivity of solid polymer electrolyte by controlling ion(alkali metal ion)–dipole(ether oxygen) interaction, two kinds of modification were adopted on oligo(oxyethylene) (OOE). One is the capping of terminal hydroxyl groups of OOE with methyl or acetyl groups. The other is the replacement of the center ethylene group of OOE with methylene or propylene group. Ion–dipole interaction was analyzed by measuring the ion dissociation, ion conduction and T_g of Nafion/modified OOE composite films. The modification of the end groups was more effective than that of the center group in increasing ionic conductivity. The methyl group is superior to the acetyl group as the end group of OOE for lithium ion conduction.