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Improved Electrolytes For Electrochemical Capacitors—TOXCO
Inc., 1830 Columbia Avenue,
Folcroft, PA
19032-1905;
610-522-5960
Dr. Novis Smith, Principal Investigator, NOVIS@LITHCHEM.COM
Mr. James J. Gormley, Business Official, JIM2591@LITHCHEM.COM
DOE Grant No. DE-FG02-05ER84261
Amount: $749,721
Currently, the best performing ultra-capacitors, an important technology
for hybrid electric vehicles, utilize a non-aqueous electrolyte based on
acetonitrile, which is highly flammable and considered toxic.
Alternative electrolytes that do not contain acetonitrile are based
primarily on propylene carbonate and have about 35% of the conductivity of those
with acetonitrile, which significantly degrades the performance of the
capacitor. This project will develop
and synthesize a number of new quaternary ammonium tetrafluoroborates and
determine their solubility and maximum conductivity in non-acetonitrile
electrolytes. Phase I successfully
found and developed a group of non-acetonitrile electrolytes with conductivity
as high as 60% of the acetonitrile-containing electrolytes. In
addition, the flash point of these electrolytes was increased from 2oC
to 120oC (increased safety), and the allowable capacitor voltage was
increased from about 2.8 volts to over 4.2 volts (increased performance). The
increased performance and safety were accomplished with relatively non-toxic,
low-cost solvents and newer versions of quaternary ammonium tetrafluoroborate
salts. Phase II will complete the
optimization and final selection of the preferred electrolyte compositions.
Processes for manufacturing and purifying the preferred electrolytes will
be developed on a small pilot scale.
Commercial Applications and other Benefits as
described by the awardee: The
new ultra-capacitor electrolytes should overcome a major safety and hazard
barrier in the wide acceptance of the use of ultra-capacitors in hybrid electric
vehicles (HEV) and electric vehicles (EV). The
replacement of the currently used acetonitrile-based electrolytes with these
essentially non-flammable, non-toxic, higher-voltage electrolytes could
eliminate the safety issues that have been raised for ultra capacitors.
Further, the use of ultra-capacitors with these new safe, high
performance electrolytes should aid the rapid commercialization of HEVs and EVs.