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Capacitors to Replace Batteries?
An anonymous reader writes "MIT's Joel Schindall plans to use old technology in a new way with nanotubes.
'We made the connection that perhaps we could take an old product, a capacitor, and use a new technology, nanotechnology, to make that old product in a new way.'
Capacitors contain energy as an electric field of charged particles created by two metal electrodes, and capacitors charge faster and last longer than normal batteries, but the problem is that storage capacity is proportional to the surface area of the battery's electrodes.
MIT researchers solved this by covering the electrodes with millions of nanotubes.
'It's better for the environment, because it allows the user to not worry about replacing his battery,' he says. 'It can be discharged and charged hundreds of thousands of times, essentially lasting longer than the life of the equipment with which it is associated.'"
I'm sick of that bloody rabbit. Now it's going to last forever. Perfect.
Meta will eat itself
Good point. Maybe the nanotubes actually mesh between each other - kind of like the teeth in gears. Can't see it being easy to manufacture, but that would definitely provide a massive increase in closest-point surface area.
Meta will eat itself
Philip Jose Farmer predicted "batacitors" in his novels decades ago. Chalk annother one up for life imitating science fiction.
:-)
Well - its a bit of a no-brainer to any EE kind of guy. No wasteful energy conversion process, etc etc.
Everyone's been waiting for the materials technology to catch up to the rather obvious idea that's all
There are shills on slashdot. Apparently, I'm one of them.
With its longer life and faster recharge time. I wonder if this could lead to an electric car that is good for the masses where they can cross country and take only 5 to 10 minutes to recharge. That is the primary reason why the Electric Car never made popularity it is because it is not convenient enough for normal people.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
From the looks of the detail sparce article I just made before I headed off to work (at a company that works with Nanotubes ironically enough), this actually looks pretty easy. The image of nanotubes that they show are almost certainly nanotubes made by chemical vapor deposition (CVD). CVD is cheap, scalable, fairly easy, and found in every semiconductor fab you have ever gone to. Now, I am not saying that there might be some real engineering challenges, but if alls they have to do is grow a mess of nanotubes ontop of a substrate as shown in the picture of the article, this is going to very easy and hit the market in the very near future.
That said, I would not hold my breath waiting for this product to come out. The making of the nanotubes in the way that they have is not hard, but I would be suprised to learn that there is not some other performance or quality issue that needs to be struggled with.
In electrolytic capacitors, one electrode is formed by a conducting liquid, and an oxide layer on the metallic conductor acts as the insulator. The nanotube version may use something like this.
On another note, every time someone proposes to replace batteries with capacitors, I wonder how they make up for the huge variation of voltage that a capacitor delivers. Basically, the voltage of a capacitor is proportional to the amount of charge stored, whereas a battery provides more or less constant voltage. The capacitor-battery would require a circuit (something like a switching power supply) to be able to provide constant voltage. That, in turn, would take up space and waste some energy.
Escher was the first MC and Giger invented the HR department.
If they have batteries, a short circuit will cause the battery to get warm for a while, or it will release some slightly caustic goo and you have to wash your hands.
:-/
Sorry, that's incorrect.
Try shorting a car battery with a screwdriver and tell me there isn't a violent electrical arc. Also, NiCads (and I believe NiMH) have very low internal resistance - if shorted, they can literally explode as they overheat dramatically. You're confusing this with non-rechargeable batteries, which behave as you describe.
Also, capacitors deliver charge at a rate dependent on the impedance of the load they're driving. It would be very straightforward to put a small resistor in the package containing the capacitor, so that the current out of it is limited.
Regarding the short-circuiting, capacitors require overlapping surfaces that are electrically insulated from each other. That means if you're using nanotubes, you'll want both sides covered in nanotube "fuzz" and the two sides then pushed together so that the two intertwine. This means that one (or preferably both) sides need their nanotubes coated with some kind of insulating material for it to work, otherwise the nanotubes will simply short out, and then you won't have a capacitor any more. And that means you won't get short circuits from random broken nanotubes in the structure.
Fragility I don't know about, but since carbon nanotubes are the strongest substance currently known, I suspect it's not going to be a huge problem. Also consider that the whole thing could easily be encapsulated in some solid insulating block so that it's a single physical chunk (remember that carbon isn't a metal so there are no significant expansion/contraction issues with heat). Batteries are only as solid as they are because they've got a solid metal case encapsulating well-packed electrodes and electrolyte - try dropping a plastic-case car battery from a height and tell us how solid it is.
Given how desperate battery manufacturers are for any kind of edge, I imagine this will be rushed to market as fast as physically possible!
Grab.
The real information can be found in http://lees.mit.edu/lees/posters/RU13_signorelli.p df It lists project goals as 300,000 cycles and 60 Wh/kg (Which if I used the units program correctly is 0.216 MJ ar almost as much as a NiMH battery.)