A statistically designed study of ternary electrolyte polymer material (PEO/LIClO4/ethylene carbonate)

Statistically designed mixture experiments were performed for the ternary e lectrolyte polymer system poly(ethylene oxide) (PEO) - lithium perchlorate - ethylene carbonate (EC). Ionic conductivities and crystalline/glass trans ition temperatures were measured for 15 ternary mixtures of varying ingredi ent proportions. Although conductivity increases with salt concentration, t he plasticizer/polymer ratio is important in determining conductivities at higher salt proportions. A quadratic mixture model provides an accurate des cription of how conductivity at room temperature changes with varying ingre dient proportions. It predicts a maximum conductivity for a 0.50 PEO, 0.21 LiClO4, 0.29 EC (weight fractions) mixture. A special cubic model is found to be most appropriate for representing how the corrected transition temper ature values depend on ingredient proportions. The temperature dependence o f conductivity was measured for some of the mixtures. The same composition exhibited higher conductivities at room temperature and up to 100 degrees C . The VTF parameters for the plasticized systems were compared with those o f non-plasticized ones. (C) 2000 Kluwer Academic Publishers.