A report presents results of research on carbonate-based electrolytes to improve the low-temperature-performances of lithium-ion rechargeable electrochemical cells. The loss of performance with decreasing temperature is attributable largely to a decrease of ionic conductivity and the increase in viscosity of the electrolyte. What is needed to extend the minimum operating temperature from 20 °C down to –40 °C is a stable electrolyte solution with relatively large low-temperature conductivity, relatively small low-temperature viscosity, a large electric permittivity, adequate coordination behavior, and appropriate ranges of solubilities of liquid and salt constituents.

This work was done by Marshall Smart, Ratnakumar Bugga, Chen-Kuo Huang, and Subbarao Surampudi of Caltech for NASA's Jet Propulsion Laboratory. To obtain a copy of the report, "Rechargeable Lithium-Ion Cells with Improved Low-Temperature Performance with Novel Carbonate-Based Electrolyte," access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Materials category. NPO-20407