Battery breakthrough?

http://www.technologyreview.com/Biztech/18086 /
These guys claim to have a new type of ultracapacitor with a power/weight ratio better than lithium-ion batteries.
If true, then once the cost comes down (I assume they'll be expensive at first to serve the price-insensitive niches), these should be a real boon to robotics. More power per weight than batteries, and a LOT faster to charge (and discharge), too.
Best, - Joe
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 26 Jan 2007 11:12:13 -0700, Joe Strout wrote:

batteries and capacitors are two different things, with different purposes. Capacitors are not storage cells in the traditional sense of the term so they cannot replace batteries.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
noone wrote:

From the article:
The company boldly claims that its system, a kind of battery-ultracapacitor hybrid based on barium-titanate powders, will dramatically outperform the best lithium-ion batteries on the market in terms of energy density, price, charge time, and safety. Pound for pound, it will also pack 10 times the punch of lead-acid batteries at half the cost and without the need for toxic materials or chemicals, according to the company.
The claim is that they have a material with a permittivity of "18,500 or more", rather than 20 to 30.
To answer Joe's question, the high voltages they are talking about are not going to be easy to work with. A capacitor with 3,500 volts on it, could be quite dangerous. Lithium-ion batteries (or even NMH batteries) may dominiate the robotics area due to safty concerns.
We'll see how it all pans out.
-Wayne
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

They claim to have addressed this:
Weir says the voltage will be stepped down with a bi-directional converter, and the whole system will be secured in a grounded metal box. It won't have a problem getting an Underwriters Laboratories safety certification, he adds. "If you drive a stake through it, we have ways of fusing this thing where all the energy is sitting there but it won't arc It will be the safest battery the world has ever seen."
(He's using "battery" here in a nontechnical sense, I believe; it's still a capacitor, but targeted at the battery marketspace.)

Agreed.
Best, - Joe
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Joe Strout wrote:

I'm skeptical about this, too. But consider ultracapacitors. Those were once thought impossible. Capacitors big enough to start an auto engine? No way. Yet they exist, and you can buy them now.
http://www.maxwell.com/ultracapacitors/products/index.asp
                John Nagle
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Wayne C. Gramlich" wrote:

Its volts per inch that is important in capacitors, not just volts.
CRTs (and conventional TV sets) have several thousand volts on some caps. Granted, they are small caps, so the energy isn't a major problem. Capacitors used in utility applications typically have up to 20 kV across them. That's quite hazardous. But even here, the energy stored at full charge is much less than what an EV battery would need to store. The major safety problem with high energy storage in capacitors is that the typical failure modes tend to 'run away' so to speak. Once the dielectric punches through, the cap's charge is dissipated at that point. As the discharge progresses, the failed area tends to expand, providing a lower impedance path for the remainder of the charge. The total energy stored might dissipate within a few milliseconds, making a device capable of storing as much energy as a vehicle's battery the equivalent of a small bomb.
--
Paul Hovnanian mailto: snipped-for-privacy@Hovnanian.com
------------------------------------------------------------------
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

These ones could, if they live up to their claims. The main reason you wouldn't use current capacitors to replace batteries is that their specific power (power per unit weight) is far too low. But the specific power of these EEStor units is higher than lithium-ion. They also charge and discharge faster, support an essentially indefinite number of cycles, and contain no toxic chemicals. Why wouldn't you replace batteries with them?
Of course, the claims are so amazing that many people believe the whole thing is a big scam. I guess we'll find out in the next year or two.
Best, - Joe
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.