Solvent-cast and hot-pressed P(EO)(20)LiN(SO2CF2CF3)(2) (LiBETI) polymer electrolytes containing ceramic fillers such as 7 nm SiO2 and 2-4 mum gamma-LiAlO2 were prepared. The ionic conductivity and interfacial stability of these poly(ethylene oxide) electrolytes were investigated. The addition of ceramic fillers to solvent-cast and hot-pressed P(EO)(20)LiBETI polymer electrolytes did not result in any substantial improvement of ionic conductivity. However, solvent-cast SiO2-containing P(EO)(20)LiBETI polymer electrolytes showed a much higher interfacial resistance and Li stripping overvoltage than hot-pressed and filler-free solvent-cast electrolytes. (C) 2004 The Electrochemical Society. All rights reserved.