The effect of poly(ethylene oxide) (PEO)-based surfactant in the gel polymer electrolyte on the cycling efficiency of lithium was investigated by means chronopotentiometry. The gel polymer electrolyte was prepared by thermal curing using bisphenol A ethoxylate diacrylate as a cross-linker. While an improvement in cycling efficiency of lithium was found for the electrolytes containing both of perfluorinated and star-shaped PEO-based surfactants, the better cycling efficiency was observed for the star-shaped surfactants than that for the perfluorinated surfactant. More than 90% of cycling efficiency of lithium was achieved for the polymer electrolyte using star-shaped PEO surfactants. The cycling efficiency of lithium in the gel polymer electrolyte containing star-shaped surfactant increased as increasing of the molecular weight of side chain. By using star-shaped PEO surfactant, the interface resistance was almost constant during the repeated cycles. The star-shaped PEO-based surfactants seem to be very effective to form stable SEI layer. (c) 2005 Elsevier B.V. All rights reserved.