This work investigates the formation of a passivation layer at the lithium/poly(ethylene oxide)-lithium triflate electrolyte interface using attenuated total reflection FTIR spectroscopy, atomic force microscopy (AFM) and a.c. impedance spectroscopy. Self-assembled molecular layer technology was used to generate interfaces having no passivation layer so that comparisons could be made between passivated and non-passivated surfaces. AFM data show the formation of a passivation layer composed of what appears to be crystallites and ATR-FTIR data indicate the presence of CF, radicals in this passivation layer with possible polymer chain scission. The formation of Li-O-R compounds is also observed, (C) 2000 Elsevier Science B.V. All rights reserved.