MOBILITY AND IONIC ASSOCIATION OF LITHIUM-SALTS IN A PROPYLENE CARBONATE-ETHYL METHYL CARBONATE MIXED-SOLVENT

Electrolytic conductivities of lithium salts have been measured in equimolar mixtures of propylene carbonate and either ethyl methyl carbonate or 1,2-dimethoxyethane at 25 degrees C over a salt concentration range of 10(-2) to 10(-3) mol dm(-3). The limiting molar conductivities and association constants were calculated from the expanded Fuoss-Hsia equation. The Walden product of lithium ion was not enhanced by the addition of ethyl methyl carbonate as observed in the case of 1,2-dimethoxyethane, due to the lack of specific solvation. LiPF6 and Li(CF3SO2)(2)N in the propylene carbonate-ethyl methyl carbonate mixed solvent formed solvent-separated ion pairs, which resulted in decreased ion association.