Fractal Systems Polymer Ultracapacitors
POLYMER ULTRACAPACITORS TAKE CHARGE
Battery of the future.
Flexible polymer ultracapacitors will provide higher power and energy
density at less cost than ruthenium-dioxide.
It conducts like copper but can be grown like plastic. It's called
nanoporous ordered conducting polymer, and it can be useful either for
energy storage or as a battery.
With MDA SBIR funding, Fractal Systems, Inc. (Safety Harbor, FL), developed
a unique method for producing and ordering the internal morphology of
conductive polymers as well as the composition of the matter itself. Eager
to use this polymer as an electrode, Fractal is working in partnership with
Evans Capacitor Company to create a prototype ultracapacitor.
It will have an order of magnitude more energy density than conventional
carbon-based capacitors, and perform two to three times better at less cost
than a ruthenium- dioxide capacitor. The relative ease of manufacture of
polymer ultracapacitors spells good news for any industry interested in
electrical power storage and discharge including automotive and consumer
High power density and high energy density are always important requirements
for military systems sensitive to weight limitations. MDA awarded SBIR
contracts to Fractal in 2001 and 2002 to assess the characteristics of, and
develop techniques for growing, the nanoporous conducting polymer for use in
Chemists grow thin films of specialized polymers using electrochemical
synthesis of commercially available monomers and reagents. Fractal chemists
experimented with various configurations of polythiophenes, polyanilines,
polypyrroles, and other copolymers and settled on those with the best
combination of voltage and energy density. They use a proprietary
preparation technique to settle thin coatings throughout a carbon paper to
achieve desired nanoporosity.
There are advantages to using conducting polymers for capacitance and not
all of these are related to price and performance.
First of all, polymers are simple to manufacture and can be produced in
sheets and films. Since a polymer can be coated on a substrate, the mix can be used as an electrode. This is simpler than the process used to make a batch of carbon paste to manufacture one carbon pellet at a time. In theory, a sheet
of polymer/substrate one-foot square could supply 144 one-inch-diameter
Secondly, an inexpensive carbon-based capacitor uses sulfuric acid in its
electrolyte and outgasses carbon monoxide as it breaks down. For some applications that is not a significant problem, but it is an environmental effect that does not scale well. In contrast, a conducting-polymer-based capacitor uses an organic electrolyte such as lithium tetrafluoroborate and can operate in water with no acids involved.
Price and performance ultimately will determine when and where conducting
polymer is used, however. A conducting- polymer-based capacitor has more
than 10 times the energy density and approximately 500 times the power
density of a carbon-based capacitor, but it cannot compete on price alone.
Polymer compares favorably to existing ruthenium-dioxide-based capacitors on
both price and power/energy density.
Since a high power, high energy density capacitor can be used in tandem with
a battery (or in some cases act as a battery), one possible commercial market is the automotive and transportation industry.
Typical applications would include coldstart support, use with regenerative
braking, and preheating catalytic converters. Locomotives and industrial
equipment demanding short bursts of peak electrical load would also benefit.
Almost any equipment needing an uninterruptible power supply would be able to take advantage of powerful capacitors.
At the conclusion of its Phase II SBIR funding in 2004, Fractal Systems and
Evans Capacitor intend to make the polymer ultracapacitor commercially avail
able either by licensing it or by direct manufacture and sales.
The market for ultracapacitors is in its infancy-currently, limited to
weapon fuzing and medical implantable devices-but promises to expand in
direct proportion to the demand for more power, and less waste and weight in
batteries. Interested parties should contact Fractal Systems directly.
Dr. Matt Aldissi
Fractal Systems, Inc.
200 9th Avenue North, Suite 100
Safety Harbor, FL 34695
Tel: (727) 723-3006
Fax: (727) 723-3007
E-mail: fsi@ fractalsystemsinc.com