The Replacement For the Battery? 318
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.'"
About fast charging... (Score:5, Informative)
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.
Dupe (Score:5, Informative)
The article is confusing (Score:3, Informative)
Hate to break it to you: (Score:5, Informative)
From TFA:
Redox flow batteries (Score:4, Informative)
Re:Better hybrids (Score:3, Informative)
Um, you mean like the recently announced Chevy Volt (made by GM, the "company that killed the electric car"), which has a 40 km capacity on battery, and a small electric engine that kicks in as a generator when the battery runs out? They expect to be producing it in two or three years.
I can't really understand Jim Miller's criticism (Score:4, Informative)
"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.
Re:Charged in 10 minutes (Score:3, Informative)
For example, your television steps your house current up to a couple thousand volts. At, say, 120kv, your house circuit need only handle 20A (ie: 120kv by 0.02A is 20A at 120v. Given the specs of 280Wh/kg and 100lb [45.5kg] for a vehicle power system, that means we have 12kWh to fill. That means 5 hours for a complete fill-up, or just leaving your car plugged in overnight.)
Another Slashdot "Investment Opportunity"? (Score:5, Informative)
"Unfortunately EEStor never made and will never make the supercapacitor described in the patent [google.com] 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) [avxcorp.com].
"However, the dielectric constant drops as the electric field strength increases: http://www.nap.edu/books/NI000488/html/49.html [nap.edu]
http://prola.aps.org/abstract/PR/v71/i12/p890_1 [aps.org]
"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 [teslamotors.com]
"with an update on January 20th, 2007:
http://www.teslamotors.com/blog1/?p=46 [teslamotors.com]."
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!"
Is this more wishful hype than physics? (Score:3, Informative)
This is hundres of times more than polystyrene, but the challeng is still formidable:
A cap with 320Wh/kg or 1GJ/m^3 or 1kJ/cm^3 at 3kV would require:
C/cm^3=0.7Farad
Since C=k*e0*A/d, e0=8.8E-12, k=5000
we get C(BaTiO3)/cm^3=4.4E-8*A/d
and with A*d=1cm^3 (not all of the cap can be dielectric so this is a ceiling)we get:
A=4m^2 and d=250nm
So with d=250nm, and U=3kV, the voltage across the dielectric is 12GV/m. Breakdown voltage for most ceramics are less than 300MV/m.
This would imply less than 1% the capacity claimed. Still an incredible feat, but the car would only go a few km.
Re:About fast charging... (Score:4, Informative)
Re:I can't really understand Jim Miller's criticis (Score:3, Informative)
> Maxwell Technologies advertises a 125V output power module which is spec'd to only lose 70% of its charge after 30 days.
and
> they are ultimately bound by the physical laws of capacitors, one law being that their output voltage drops (linearly) as they discharge.
Now do the math. Or you could if enough numbers were available, so lets do it back of the envelope style. It's all about the discharge CURVE. Remember caps won't self discharge like a battery. That voltage is going to be slip sliding away from the small unavoidable losses and the that first 10% of the voltage drop will be seeping out what percentage of the watt-hours? 19% Ouch!
It will be like a car with a leak in the gas tank, the question is will be be a slow leak that can be ignored in most cases or will it feel like losing gallons per day. They are promising a car with a 500 mile range. Get the losses down where those Maxwell caps are and you lose 15 miles per day to losses. If the losses creep up to 5% terminal voltage per day to losses and recharge nightly and that will be paying for a 50 mile drive whether it sits in the driveway or runs all day. Large losses mean splitting it into banks and only charging what you plan on needing plus a reserve. Big lot of bother. Lets hope for low losses, but at the extreme voltages they are talking about I doubt it.
Brown U has similiar, polymer tech (Score:3, Informative)
http://www.brown.edu/Administration/News_Bureau/2
It's a battery-capacitor hybrid that has interesting properties. It's not at the same production level, but doesn't provide quite the same strong claims as the EESTOR system. Any opinions on the Brown effort?
Josh
Re:Why are they even trying to do cars? (Score:5, Informative)
Googol = 10^100 (Score:4, Informative)
Re:Charged in 10 minutes (Score:3, Informative)
Re:Charged in 10 minutes (Score:1, Informative)
You'd want high voltage to the house, not a high voltage transformer in the house anyway.
Regardless, transformers for high voltages aren't particularly expensive, you've probably been around more high voltage equipment then you realise:
- CRT flyback transformers can be had for tens of dollars, they typically do around 30kV
- Microwave ovens typically power the magnetron with 2kV
"Just because you increase the voltage to offset the current flow, it will not negate the fact that you are sending 12KW through, you need big wires for that."
True, but not for the reason I suspect you think this. The wires do not need to be very thick as the current will be small, however the insulation will have to be quite thick because of the high voltage. Primarily you look at the current for conductor thickness, and
Re:Miracles Required? (Score:3, Informative)
Re:Charged in 10 minutes (Score:3, Informative)