Electrolytes and Additives for Lithium Ion Batteries

The current state-of-the-art lithium ion battery consists of electrolytes, separators and electrodes. This talk focuses on the development of safe and efficient electrolytes for high-capacity/high-temperature/high-voltage lithium ion batteries. In order to develop electrolytes with a large electrochemical window (the gap between HOMO and LUMO), high lithium-ion conductivity with s > 10^-4 S/cm, and a high lithium transference number (t_Li close to 1), functional groups such as ether, alkyl as well as cyano groups were incorporated into the cations of ionic liquids. Physicochemical properties such as viscosity, thermalstability, ionic conductivity, solubility, as well as the interfacial stability between the electrolyte and the anode/cathode were studied.

There is also an ongoing effort to develop: 1) novel polymer gel electrolytes for highly efficient LiFePO₄ batteries with capacity reaching 120 mAhg^-1 at 50 ^oC; and 2) novel lithium salts with improved anodic stability (oxidation) which is important for high voltage electrolytes.