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