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Directory:MIT Nanotube Super Capacitor
MIT researchers are developing a battery based on capacitors that utilize nanotubes for high surface area, enabling near instantaneous charging and no degradation. Estimating ~5 years to commercialization.
No official company yet. Still in research and development at MIT.
How it Works
Rechargable and disposable batteries use a chemical reaction to produce energy. The problem is that after many charges and discharges the battery loses capacity to the point where the user has to discard it.
However, capacitors contain energy as an electric field of charged particles created by two metal electrodes. Capacitors charge faster and last longer than normal batteries.
The problem is that storage capacity is proportional to the surface area of the battery's electrodes, so even today's most powerful capacitors hold 25 times less energy than similarly sized standard chemical batteries.
MIT researchers have solved this by covering the electrodes with millions of nanotubes, which are essentially tiny filaments. The nanotube filaments increase the surface area of the electrodes and allow the capacitor to store more energy.
The MIT capacitor thus combines the strength of today's batteries with the longevity and speed of capacitors.
This technology has broad practical possibilities, affecting any device that requires a battery.
- Small devices such as hearing aids that could be more quickly recharged where the batteries wouldn't wear out.
- In automobiles you could regeneratively re-use the energy of motion and therefore improve the energy efficiency and fuel economy.
- hybrid cars would be a particularly popular application for these batteries, both for the speed of recharge, capacity for charge, and because current hybrid batteries are expensive to replace.
Capacitors have very long life cycles (though they most certainly do wear out). Potentially, environmental waste from discarded batteries could be greatly reduced, but not eliminated.
Stage of Development
Prototype expected to be finished in the next few months.
Commercialization could be less than five years away.
Inventor: Joel Schindall
- Double Layer Capacitors: Automotive Applications and Modeling - powerpoint presentation
Phone: (617) 253-3934; Fax: (617) 258-6774
E-Mail: joels (at) mit (dot) edu
As you are aware, the capacitor battery technology does not serve as an energy source; it is an energy "recycler," so in some ways it does not directly fit your criteria. I've provided some comments to your criteria below...
As a device, its manufacture is probably "5" (manufacturing process consumes energy), but since it lasts so much longer than a battery (over 600,000 charge-discharge cycles versus 1000 or so for a battery), its lifetime is very long compared to its manufacturing energy-cost and it should probably be at least an "8" or "9" As an energy source, it varies from a "5" (allowing time-averaging of energy from a fossil source) to a "10" (recovering braking energy that would otherwise be wasted).
II. Environmental Impact
Requires fossil fuel to manufacture, but lifetime is very long. At disposal, consists of aluminum, carbon, and an electrolyte hydrocarbon called acetonitrile which has some toxicity, but I don't think it is very great.
III. Cost (cents / kw-h)
Once manufactured, it doesn't "cost" anything to use it. Lifetime should be >10 years. Today's ultracapacitors cost about 10X that of equivalent-sized batteries. The main reason for the difference is that they are manufactured in smaller quantities. At equivalent quantities, they should cost the same or even be cheaper. I would expect the same for the nanotube-enhanced devices, but it's too soon to really tell.
IV. Credibility of Evidence
Encouraging, but we still have a ways to go. We are extrapolating from measured performance of existing ultracapacitors (using activated carbon electrodes). We have electron microscope pictures of the nanotube-enhanced electrode structure and we have used a technique called Rhaman Spectroscopy to establish that the nanotubes have the desired structure, but we estimate another 3-6 months before we can verify that our extrapolation is accurate by measuring the actual electrical performance of a sample device.
V. Stability / Reliability
Existing ultracapacitors are extremely stable and reliable, there is no reason why this device should not be the same.
Prototype quantities are probably a couple of years away, small-scale manufacturing in about 5 years, larger scale manufacturing about 10 years, primarily because initial devices will be lower volume and therefore higher cost. This could be shortened if independent investment $$ were provided.
VII. Safety/Danger to Persons
Aluminum and carbon electrode materials are very safe. Acetonitrile produces cyanide gas if incinerated -- devices would need to be in sealed packages. There is an alternate electrolyte called PC which is harmless but has only about half the energy storage capability per unit volume.
VIII. Politics of science
Hmmm, I think everyone has their own opinions on this. However, it's not terribly threatening to existing players (it could be manufactured by "battery" companies), so hopefully it would not be too contentious.
IX. Open-Source conducive
MIT would want royalties, and other people's patents might be involved in the manufacturing process. MIT takes the position that it wants to make royalties, but its primary goal is to disseminate IP, not to restrict it.
X. Stage of Device Development
We have manufactured samples of the electrode material, but we have not yet demonstrated the operation of a prototype device (3-6 months). We believe that it can be mass produced at competitive prices, but this has not yet been established.
In the News
- Nanotube Superbatteries - Researchers at MIT have made pure, dense, thin films of carbon nanotubes that show promise as electrodes for higher-capacity batteries and supercapacitors. (MIT Technology Review; Jan. 9, 2009)
- Super Battery - Researchers at the Massachusetts Institute of Technology are developing a battery that could charge your cellphone or laptop in a few seconds rather than hours, and also might never need to be replaced. (ScienCentral News; June 8, 2006)
- Capacitors to Replace Batteries? - (Slashdot; June 9, 2006)
- Lowly battery technology due for a recharge (Ars Technica, Mass.; June 9, 2006)
- Super battery developed (The Inquirer; 09 June 2006)
- A Better Energizer - An ultracapacitor is what really keeps going and going ... (Discover; Vol. 27 No. 05 | May 2006)
See Discussion page