Syntheses of graft copolymers based on PEO and fluorinated functional groups are described. Grafting of fluorinated groups reduces the Tm of PEO and also increases the miscibility of PEO with ionic liquids, so that addition of ionic liquids improves ionic conductivity even at room temperature. The disclosed copolymers containing fluorinated functionality have superior safety and are more flame retardant as compared to traditional electrolytes. Such copolymers can be used as either solid or gel electrolytes in Li batteries.