Battery breakthrough?

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.

 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

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 Š 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.)


- Joe

     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

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:Paul@Hovnanian.com
------------------------------------------------------------------
David Bradley (IBM programmer who created the Ctrl-Alt-Del reboot
keyboard sequence), "I may have invented it, but Bill made it famous."

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