Hp. Chen et al., The effect of ethylene carbonate and salt concentration on the conductivity of propylene carbonate vertical bar lithium perchlorate electrolytes, J ELCHEM SO, 147(2), 2000, pp. 399-406
Propylene carbonate (PC) is a common organic solvent used in lithium batter
ies due to its high dielectric constant and high chemical stability with li
thium. However, the conductivity of PC-based electrolytes is about two orde
rs of magnitude lower than those of aqueous electrolytes. To increase the c
onductivity of PC-based electrolytes, a co-solvent, ethylene carbonate (EC)
, is added to the electrolyte to form a mixed solvent. In this research, th
e conductivity of electrolytes as a function of lithium perchlorate (LiClO4
) salt concentration and EC/PC molar ratio have been studied. The highest c
onductivity, 1.4 x 10(-2) S cm(-1), occurs when the salt concentration is a
bout 1 mol L-1 and the EC/PC molar ratio is about one. To understand the co
mposition dependence of the conductivity, the interaction between Li+ and E
C 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 LiClO4 concentration and the solvation number of Li+ decr
eases with increasing the LiClO4 concentration at constant EC/PC molar rati
o. (C) 2000 The Electrochemical Society. S0013-4651(99)06-046-2. All rights
reserved.