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The Replacement For the Battery?
jackd writes "Great article in Technology Review, bordering on 'too good to be true,' about a small company in Texas that is developing the replacement for the electrochemical battery. The device is a kind of hybrid battery-ultracapacitor based on barium-titanate powders. Quoting: 'The company boldly claims that its system... will dramatically outperform the best lithium-ion batteries on the market in terms of energy density, price, charge time, and safety... The implications are enormous and, for many, unbelievable. Such a breakthrough has the potential to radically transform a transportation sector already flirting with an electric renaissance.'"
I see the claim about charging in 10 minutes---but I've never seen them claim that will happen at home. It is indeed quite clear, as you've figured out yourself, that a residential hookup just doesn't have the capacity for a fast charge. But frankly, that's not that big of a deal, because in practice it will not be impractical to recharge a car at home over the course of hours.
It's when you're on a long trip and you need to refill and go that you'll be wishing for a filling station with an ultracap-compatible, high-power electrical supply---for which you'd likely be willing to pay a premium kWh rate.
As likely as it was in September: http://hardware.slashdot.org/article.pl?sid=06/09/ 25/1837254
From TFA:
There is no "I disagree" mod for a reason. Flamebait, Troll, and Overrated are not substitutes.
Taken from the Technology Review article:
"We're skeptical, number one, because of leakage," says Miller, explaining that high-voltage ultracaps have a tendency to self-discharge quickly. "Meaning, if you leave it parked overnight it will discharge, and you'll have to charge it back up in the morning."
The Jim Miller quote above confuses me, as Maxwell Technologies advertises a 125V output power module which is spec'd to only lose 70% of its charge after 30 days. So why is he contradicting his own company's products?
For those who are unfamiliar, while ultracaps sound fantastic, they are ultimately bound by the physical laws of capacitors, one law being that their output voltage drops (linearly) as they discharge. Maxwell Technologies knows about this, so they develop ultracapacitor arrays with extremely high internal voltages (4000+ V) and regulate the power output using efficient step-down converters. Battery cells, of course, do this naturally, because the electrochemical reactions generating the current do so at a voltage determined by the electric potential of the galvanic reaction inside the cell.
This is one reason why you don't hear much about using ultracaps in portable electronic equipment. While ultracaps may be relatively compact, they are still bulky, and though they may be able to provide the necessary voltage, you have to factor in doubling or even tripling the required voltage to use efficient step-down converters. The story gets even worse for charging. Let's say you want to charge using 12 volts DC. Do you run through dedicated charging circuitry which takes in "safe" voltage, but can only charge the ultracap at battery-style rates (low current), or do you try and charge the ultracap in its theoretical minimum charge time (high current), which means that the wall-warts you are used to seeing will look more like big, boxy IGBT/Invert-based welders (and you thought your xbox 360 power supply was big...)
In short, while it sounds good in theory, the practical challenges of discharging and charging ultracaps are fairly sizable.
Be careful. Slashdot has been running lots of stories that are "investment opportunities". Read this, the first comment to the story linked from the Slashdot story. I didn't write it, it was written by someone with the nick Emosson, but it sounds correct. (Also, read the other comments showing skepticism of the idea.):
"Unfortunately EEStor never made and will never make the supercapacitor described in the patent because they ignore a well known physical effect, called "dielectric saturation".
"Barium titanate has been used in capacitors for decades, due to its high dielectric constant: (PDF file).
"However, the dielectric constant drops as the electric field strength increases: http://www.nap.edu/books/NI000488/html/49.html
http://prola.aps.org/abstract/PR/v71/i12/p890_1
"At a hypothetical field of 3500 Volts over a thickness of 12.76 micrometers, as proposed in the patent, the dielectric constant of barium titanate would be orders of magnitude lower than the claimed 18500, reducing capacity and energy density by the same factor...
"This has been discussed in more detail by Prof. Anatoly Moskalev on December 24th and 26th, 2006 in
http://www.teslamotors.com/blog1/index.php?p=43
"with an update on January 20th, 2007:
http://www.teslamotors.com/blog1/?p=46."
Also read this comment considerably below:
"Further evidences of EEstor's hype! by Roger Pham 1/22/2007 10:41 PM
"In his patent #7033406, Richard Weir, EEstor CEO, cited data published WAY BACK in 1985 from the Japan's Journal of Applied Physics, as basis for the high dielectric property of Barium Titanate (BaTiO3)powder, when coated with aluminum oxide and calcium magnesium aluminosilicated glass. If BaTiO3 capacitor was so good way back in the 1985, the likes of the GM EV1 would be around evey street corners since 1996, or the Prius would have been a PHEV way back in 1997!
"What held back coated BaTiO3 powder from becoming a SuperCapacitor was the fact that BaTiO3 has dielectric property that varies by nearly ten folds with just typical seasonal swing in ambient temperature, and the fact that its dielectric property drops by as much with high electrical field strength, as Emosson has brought up!"
That's just the thing. These supercapacitors have wild performance swings over standard Earth temperature ranges. And the problem of freezing lead-acid car batteries has already been solved. It's called the Absorbed Glass Mat battery and it has been on the market since at least 1989 (has always been the OEM battery in the Miata, for example).