Approximate models of the logarithmic ionic conductivity versus the composition of polymer electrolytes were obtained in terms of the mixture design method. The ionic conductivity of SPEs was strongly affected by the contents of plasticizers (tetraglyme and tetraglycol). The order of ionic conductivity increased from 10(-9) to 10(-4) S.cm(-1) at 30degreesC upon increasing the weight fraction of plasticizers in the PEO-LiCF3SO3-plasticizer from 0 to 0.6. Increasing the weight fraction of the plasticizer in polymer electrolytes caused the glass transition temperature, the melting point, and the crystallinity of PEO-LiCF3SO3-plasticizer to decrease, whereas the ionic conductivity increased. When stainless steel was used as the working electrode, the anodic current was relatively less for potential below 4.0 V (vs. Li/Li+), and the anodic current increased significantly for potential greater than 5.1 and 5.0 V when the compositions of the PEO-LiCF3SO3-Tetraglyme and PEO-LiCF3SO3-Tetraglycol polymer electrolytes were [0.22, 0.19, 0.59] and [0.20, 0.17, 0.63], respectively.