Nanocomposite polymer electrolytes based on high-molecular weight poly(oxyethylene) (POE) were prepared from high aspect ratio cellulosic whiskers and lithium trifluoromethyl sulfonyl imide (LiTFSI). Prior to the polymer electrolyte characterization, the polymer/whiskers nanocomposites were characterized using wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Interactions between cellulose and POE were evidenced. The main effect of the filler was a thermal stabilization of the storage modulus for the composites above the melting point of the complexes POE/LiTFSI. The ionic conductivity was quite consistent with the specifications of lithium batteries.