Aerogel Capacitor Electrode Material Announced
Aerogel Composite, Inc. (ACI) announced today that a carbon aerogel ultracapacitor electrode material with unusually large amount of energy storage for its size is available for sale. Aerogels are solid substances similar to gels but where the internal liquid is replaced with air. Ultracapacitors are of particular interest in automotive applications for hybrid vehicles and as supplemental storage for battery electric vehicles. The following statement from their press release defines the performance of the product:
The extremely high electrochemical surface area of ACI's ENERGel(TM) carbon aerogel enables very high rates of charge and discharge. Capacitance's of more than 104 F/g and energy densities of more than 325 kJ/kg have been demonstrated with carbon aerogels ultracapacitors. Additionally, power densities of up to 20 kW/kg have been achieved. This is orders of magnitude higher than what conventional capacitors offer. ACI believes that its ENERGel(TM) carbon aerogel is a superior option for applications such as specialized electrodes.
Reference: Aerogel Composite announces ENERGel(TM) Ultracapacitor, Greenshift press release, Feb. 21, 2005
Technorati tags: ultracapacitors, energy storage, energy, technology
Since I don't think conveniently in Joules, 325 kJ/kg works out to just about 90 Wh/kg. That's a factor of 15 better than Maxwell's current products. I see that the product announcement is for materials; we'll have to wait for someone to deliver big honkin' capacitors made with it. Still, exciting times...
Posted by: Michael Cain | February 22, 2006 at 12:00 AM
Given the density of aerogels (typically milligrams/cm^3) I wonder how big a volume a kilogram of this material would occupy.
Posted by: Robert McLeod | February 22, 2006 at 11:05 AM
Good catch, Robert.
I noticed too that they don't discuss voltage (and a lot of their numbers are stated in terms of 'up to', such as 'up to' 20 KW/kg, whereas Maxwell has a production device that's 10 KW/kg).
One of the sticking points about carbon supercaps is that while they can hold an astonishing number of farads, the theoretical peak voltage is - I believe - around 3.5V (Maxwell's chemistry achieves 2.7V). You have to stack a lot of these things in series in order to achieve automotive voltages, which kills the capacitance.
So, if the ACI chemistry were, for example, 3.2V, that would be fairly impressive. If on the other hand it were 2.2V, it might be competetive, but not such a breakthrough. Of course, if it is close to the limit, one wonders where we have to go from here. You aren't likely to get much higher energy densities with carbon, I don't think. Are you?
Posted by: Jason | February 22, 2006 at 11:43 PM
Oops. These guys have been shipping carbon aerogel supercaps for a while now. They're pretty small (50F max, it looks like), but they're at 2.5V
http://www.cooperet.com/products/products.cfm?page=supercapacitors
Posted by: Jason | February 22, 2006 at 11:50 PM
At 90 Wh/kg, you could make a powerpack for an electric bicycle which packs 500 Wh (enough for about 30 miles), recharges from a wall outlet in 6 minutes and weighs about 12 pounds. A 2 kWh surge pack for a hybrid car, 50 pounds. Woot!
Posted by: Engineer-Poet | February 23, 2006 at 03:21 PM