The Effect of Ethylene Carbonate and Salt Concentration on the Conductivity of Propylene Carbonate∣Lithium Perchlorate Electrolytes

Abstract

Propylene carbonate (PC) is a common organic solvent used in lithium batteries due to its high dielectric constant and high chemical stability with lithium. However, the conductivity of PC‐based electrolytes is about two orders of magnitude lower than those of aqueous electrolytes. To increase the conductivity of PC‐based electrolytes, a co‐solvent, ethylene carbonate (EC), is added to the electrolyte to form a mixed solvent. In this research, the conductivity of electrolytes as a function of lithium perchlorate salt concentration and EC/PC molar ratio have been studied. The highest conductivity, , occurs when the salt concentration is about and the EC/PC molar ratio is about one. To understand the composition dependence of the conductivity, the interaction between and EC molecule has been studied using Raman spectroscopy. These results showed that the solvation number of increases with increasing the EC/PC molar ratio at constant concentration and the solvation number of decreases with increasing the concentration at constant EC/PC molar ratio. © 2000 The Electrochemical Society. All rights reserved.