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

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 ( LiClO 4 ) salt concentration and EC/PC molar ratio have been studied. The highest conductivity, 1.4 × 10 − 2 S cm − 1 , occurs when the salt concentration is about 1 mol L − 1 and the EC/PC molar ratio is about one. To understand the composition dependence of the conductivity, the interaction between Li + and EC molecule has been studied using Raman spectroscopy. These results showed that the solvation number of Li + increases with increasing the EC/PC molar ratio at constant LiClO 4 concentration and the solvation number of Li + decreases with increasing the LiClO 4 concentration at constant EC/PC molar ratio.