APPLICATIONS OF TECHNOLOGY:
Lithium ion batteries for
- Hybrid electric vehicles
- Portable consumer electronics
- Cordless tools
- Better low temperature performance than ethylene carbonate-containing electrolytes
- Remains liquid through broad temperature range (-48.8 °C to 242 °C)
- Prevents propylene carbonate exfoliation
- Longer rechargeable battery life
Berkeley Lab researchers led by Gao Liu have developed an improved lithium ion battery electrolyte containing a solvent that remains liquid at typical operating temperatures but, unlike similar additives, will not degrade graphite anodes.
Lithium ion batteries in widespread use today rely on graphite anodes and an electrolyte containing ethylene carbonate (EC), which forms a stable solid electrolyte interphase (SEI) on the anode surface during the initial charging process. This SEI permits passage of lithium ions, but insulates against flow of electrons. However, batteries that use EC in their electrolyte require heating and additional solvents to maintain a liquid phase because EC is solid at room temperature.
Propylene carbonate (PC) stays liquid from -48.8 °C to 242 °C and could be an ideal solvent for lithium ion battery electrolytes; however, it causes rapid exfoliation of graphite anodes. The Berkeley Lab team overcame this limitation by adding as co-solvents variants of PC that contain long alkyl chains. When added to PC, these bulky cyclic carbonates such as 1-hexane, 1-octene, and 1-dodecene also create a stable SEI on graphite anode surfaces, yielding cells with high energy storage capacity and high efficiency.
DEVELOPMENT STAGE: Bench scale prototype
STATUS: Issued U. S. Patent #9,692,086, #10581118. Available for licensing or collaborative research.
FOR MORE INFORMATION:
Zhao, H., Park, S-J, Shi, F., Fu, Y., Battaglia, V., Ross, Jr., P.N., Liu, G. “Propylene Carbonate (PC) Based Electrolytes with High Coulombic Efficiency for Lithium Ion Batteries,” Journal of the Electrochemical Society, 161 (1) A194-A200 (2014).
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REFERENCE NUMBER: IB-2974