The present work reports the Raman spectroscopic characterization of solvent-cast and hot-pressed P(EO)(20)LiN(SO2CF2CF3)(2) (LiBETI) polymer electrolytes containing nanosized (7 and 12 nm) SiO2 and micro-sized gamma-LiAlO2. The Raman spectra showed slight changes, including peak shifting and new peaks, in the low frequency region that are likely due to the interaction between the filler and the polymer. However, no significant differences in the BETI- anion modes in filler-free and filler-containing P(EO)(20)LiBETI polymer electrolytes were detected. This indicates that the presence of the nanometric SiO2 ceramic filler in the P(EO)(20)LiBETI polymer electrolyte may have little influence on the ionic interactions. In addition, solvent-cast polymer electrolytes showed only slight changes in very weak vibrational modes. (C) 2004 Elsevier B.V. All rights reserved.