High Energy Density Ultracapacitors

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OPEN 2009
Boston, Massachusetts
Project Term:
04/01/2010 - 12/31/2013

Technology Description:

FastCAP Systems is improving the performance of an ultracapacitor—a battery-like electronic device that can complement, and possibly even replace, an HEV or EV battery pack. Ultracapacitors have many advantages over conventional batteries, including long lifespans (over 1 million cycles, as compared to 10,000 for conventional batteries) and better durability. Ultracapacitors also charge more quickly than conventional batteries, and they release energy more quickly. However, ultracapacitors have fallen short of batteries in one key metric: energy density—high energy density means more energy storage. FastCAP is redesigning the ultracapacitor's internal structure to increase its energy density. Ultracapacitors traditionally use electrodes made of irregularly shaped, porous carbon. FastCAP's ultracapacitors are made of tiny, aligned carbon nanotubes. The nanotubes provide a regular path for ions moving in and out of the ultracapacitor's electrode, increasing the overall efficiency and energy density of the device.

Potential Impact:

If successful, FastCAP's ultracapacitors would reduce the cost and improve the performance of HEVs and EVs, facilitating their widespread use.


Increased use of HEVs and EVs would decrease U.S. reliance on foreign sources of fossil fuels.


Increased use of HEVs and EVs would decrease harmful greenhouse gas emissions from gasoline-based vehicles.


Making it cheaper and easier to charge HEVs and EVs would save consumers time and money.


ARPA-E Program Director:
Dr. Timothy Heidel
Project Contact:
Dr. Riccardo Signorelli
Press and General Inquiries Email:
Project Contact Email:


Massachusetts Institute of Technology

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