Industry News
MIT nanotube-based ultracapitors may be demonstrated in a few months' time
16th April 2007
Work at MIT's Laboratory for Electromagnetic and Electronic Systems (LEES) on increasing the storage capacity of ultracapacitors may be demonstrated in the next few months, Prof. Joel E. Schindall told Le Figaro newspaper on 13 April.
Capacitors store energy as an electrical field, making them more efficient than standard batteries, which get their energy from chemical reactions. Ultracapacitors are capacitor-based storage cells that provide quick, massive bursts of instant energy. They are sometimes used in fuel-cell vehicles to provide an extra burst for accelerating into traffic and climbing hills, but need to be much larger than batteries to hold the same charge.
The LEES invention would increase the storage capacity of existing commercial ultracapacitors by storing electrical fields at the atomic level. Although ultracapacitors have been around since the 1960s, they are relatively expensive and only recently began being manufactured in sufficient quantities to become cost-competitive.
To date, despite their inherent advantages -- a 10-year-plus lifetime, indifference to temperature change, high immunity to shock and vibration and high charging and discharging efficiency -- physical constraints on electrode surface area and spacing have limited ultracapacitors to an energy storage capacity around 25 times less than a similarly sized lithium-ion battery.
The LEES ultracapacitor has the capacity to overcome this energy limitation by using vertically aligned, single-wall carbon nanotubes -- one thirty-thousandth the diameter of a human hair and 100,000 times as long as they are wide. It would reportedly permit ultracapacitors to give a car a 160 km range on electric power, and reduce energy storage units by two thirds in weight and 75% in size by comparison with existing nickel-metal hydride units as used by Toyota’s Prius.
MIT’s work on this project, first announced in late 2005, has been funded in part by the MIT/Industry Consortium on Advanced Automottive Electrical/Electronic Components and Systems and in part by a grant from the Ford-MIT Alliance.
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