Solvent-free polymer electrolytes based on polyacrylonitrile (PAN) including lithium trifluoromethane sulfortate (LiCF3SO3) were prepared. All measurements were performed on samples with various salt contents between 0 and 70 wt.%. Interactions between ion and polymer or interion were are investigated by using Fourier-transform infrared (Fr-IR) spectroscopy. X-ray diffraction measurement was also used for the analysis of aggregation states of polymer matrix and salt complex. By analysis Of v(5)(SO3) mode, it was confirmed that larger ion clusters were formed quickly above salt concentration of 50 wt.% and ionic conductivity increased dramatically in this composition region. (C) 2004 Elsevier Ltd. All rights reserved.