Ionic conductivity of a novel predominantly lithium-ion-conducting solid polymer electrolyte is studied. The electrolyte comprises molten lithium salt(s)-acetamide-urea mixtures in which a small amount of an poly(ethylene oxide) is dissolved to stabilized it against recrystallization. The electrolyte has exceptionally hight conductivity at temperature of 70℃ or lower

including ambient temperature

for example 10-3S/cm at 70℃ and 10-4S/cm at 25. The electrolyte combines the best features of the other two

superionic glasselectrolyte and salt-in-polymer electrolyte. Its inoic conductivity depends on the low melting-point eutectic as well as the molecular weight and content of poly(ethylene oxide).