Welcome to
Science a GoGo's
Discussion Forums
Please keep your postings on-topic or they will be moved to a galaxy far, far away.
Your use of this forum indicates your agreement to our terms of use.
So that we remain spam-free, please note that all posts by new users are moderated.


The Forums
General Science Talk        Not-Quite-Science        Climate Change Discussion        Physics Forum        Science Fiction

Who's Online Now
0 members (), 181 guests, and 2 robots.
Key: Admin, Global Mod, Mod
Latest Posts
Top Posters(30 Days)
Previous Thread
Next Thread
Print Thread
Joined: Oct 2004
Posts: 1,696
M
Megastar
OP Offline
Megastar
M
Joined: Oct 2004
Posts: 1,696
Scientists at the Massachusetts Institute of Technology think they're on the verge of making traditional batteries obsolete.
The researchers are working on a new device that uses carbon nanotubes to store and release electrical energy in a system that could carry as much power as today's lead or lithium batteries.

But unlike the rechargeable batteries used on today's cellphones and laptop computers, these devices could be recharged hundreds of thousands of times before wearing out.
And instead of taking hours to recharge, they could be powered up in about the same time it takes to fill up a gas tank.

Electronics professor Joel Schindall drives a Toyota hybrid car, which uses an electric battery to reduce gasoline consumption. But Schindall would prefer an all-electric car, and he thinks his team's research could finally make such vehicles practical.

In a basement laboratory at MIT, Schindall and his colleagues are using acetylene gas to deposit carbon nanotubes on pieces of silicon. Schindall says that the technology isn't much different from the kind used to produce microchips, and so mass production shouldn't be too difficult. Still, he said, `It's one thing to postulate it, but that's a long way from being commercially viable and competitive in price." Schindall says he hopes to have a finished example by the fall.

During the 1960s, scientists discovered that they could make more powerful capacitors by coating their electrodes with finely ground charcoal -- a form of carbon. The charcoal crystals greatly increased the surface area of each electrode, allowing it to collect a greater electrical charge.

Since then, scientists have learned how to grow carbon nanotubes -- extremely thin fibers of pure carbon. Schindall and his colleagues realized that millions of tiny nanotubes would do a much better job than ground charcoal in expanding an electrode's surface area. And if the nanotube-coated electrodes were made large enough, you could build a capacitor that could work like a battery with enough power to drive a device for hours.
(from The Boston Globe' June26)

***Thoughts
Ive heard these 'basement' promises before,
Remember Cold Fusion- 'Martin Fleischmann et al'


.

.
"You will never find a real Human being - Even in a mirror." ....Mike Kremer.


.
Joined: Nov 2005
Posts: 330
J
Senior Member
Offline
Senior Member
J
Joined: Nov 2005
Posts: 330
Quote:
Originally posted by Mike Kremer:
***Thoughts
Ive heard these 'basement' promises before,
Remember Cold Fusion- 'Martin Fleischmann et al'
Well let them try! You never know until it works or does not work.

Joined: Oct 2004
Posts: 540
U
Superstar
Offline
Superstar
U
Joined: Oct 2004
Posts: 540
When you short out a battery or it internally fails, reaction rate is limited by chemical kinetics and mass transport. A battery crushed in an accident is a nuisance. When you short out a charged capacitor or it internally fails, it explodes. The energy is already fully loose in there as separated charges.

A common D-cell battery holds 59.4 kiloJoules and masses 134 grams. Go ahead, beat that - and it's real cheap to buy, too. Now tell us how to build a D-cell sized capacitor with the energy content of the same mass of hydrocarbon fuel. 134 gm of kerosene would give 2 megaJoules upon combustion - and it is safe and stable for indefinte storage. Capacitors leak.


Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz3.pdf
Joined: Oct 2004
Posts: 540
U
Superstar
Offline
Superstar
U
Joined: Oct 2004
Posts: 540
One more thing... if your energy storage device stores more energy/volume on paper than the /_\G of formation of the same volume of diamond, you might want to wonder what would hold it together in the real world.


Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz3.pdf
Joined: Nov 2005
Posts: 330
J
Senior Member
Offline
Senior Member
J
Joined: Nov 2005
Posts: 330
Quote:
Originally posted by Uncle Al:
One more thing... if your energy storage device stores more energy/volume on paper than the /_\G of formation of the same volume of diamond, you might want to wonder what would hold it together in the real world.
Great comment!!

Joined: May 2006
Posts: 35
P
Member
Offline
Member
P
Joined: May 2006
Posts: 35
As capacitors have negative and positive charges seperated by a thin layer, you would get a strong compression force across the layer. There would also be fairly large repulsive forces acting along both surfaces of the insulating layer. The lateral repulsive force would be partially countered by the lateral component of attraction from the charges on the opposite side of the layer.

With one or both surfaces covered in carbon nano tubes, there would also be a repulsive force along the surface of the tubes, tending to make them stretch in length and in diameter. However each tube would also be attracted towards the layer by the opposite charges on the other side. The carbon nano-tubes would thicken the layer of charge on either side of the insulating material.

I suspect that voltage at which the insulating layer starts leaking is much lower than the voltage at which it tears apart.

Joined: Mar 2006
Posts: 84
P
Member
Offline
Member
P
Joined: Mar 2006
Posts: 84
Al makes a point that should not be taken lightly.
I can recall a youthful indescretion involving a
home-made capacitor, (aluminum foil and widow glass),
to be pumped via a neon sign transformer, (rectifier bridge
on the primary), to about 5KV.
I don't think it even got near there.
The failure was not diagnosed but was spectacular
to witness.
It made a lasting impression, and there was no-where
near enough energy involved to drive an automobile
any distance.

Joined: Oct 2004
Posts: 1,696
M
Megastar
OP Offline
Megastar
M
Joined: Oct 2004
Posts: 1,696
Quote:
Originally posted by Peter Bmn:
As capacitors have negative and positive charges seperated by a thin layer, you would get a strong compression force across the layer. There would also be fairly large repulsive forces acting along both surfaces of the insulating layer..>.....................................>....
With one or both surfaces covered in carbon nano tubes, there would also be a repulsive force along the surface of the tubes, tending to make them stretch in length and in diameter. However each tube would also be attracted towards the layer by the opposite charges on the other side. The carbon nano-tubes would thicken the layer of charge on either side of the insulating material.
Its extremely unlikely than both surfaces would be covered in a layer/or layers of Carbon nano-tubes, in the conventional accepted way. For the reason that the huge surface area of a C-n-tube would not be utilised.
A better answer would be, that a single C-n-tube was charged up to a single potential both internally and externally. With a second C-n-tube charged with the opposite potential, both tubes ENDS, would be brought close together, but not touching. Exactly as if you were to place your index fingers almost together.
This should give you maximum electron/ion storage, due to the huge surface area involved.

In practice, imagine two household brooms placed with their bristles facing each other. For bristles, read C-n-tubes.
The 'heads of the brooms' would be of metal, in which the nano-tubes were grown/inserted, acting as the terminals.
I envisage that a huge capacity could be achieved in this way, prehaps running into millions of Farads? Only dependant upon Cap: size.

I foresee 3 problems in running a motor for powering a car.
1/ Finding a suitable (organic?) Electrolyte, that the Carbon fibres were immersed in.
2/ Its 'wetability', needed for perfect fibre coverage.
3/ A specially designed motor, in series with a variable resistance (Ohms) so as not to wastefully discharge Capacitor.

Prehaps a better method for 3/ would be to initially separate the two opposing Carbon bristles, within their Electrolyte, when the Capacitor was fully charged. Closing their spacing as dischage occurred? Thus regulating the motor torque without wasteful Ohms.


.

.
"You will never find a real Human being - Even in a mirror." ....Mike Kremer.



Link Copied to Clipboard
Newest Members
debbieevans, bkhj, jackk, Johnmattison, RacerGT
865 Registered Users
Sponsor

Science a GoGo's Home Page | Terms of Use | Privacy Policy | Contact UsokÂþ»­¾W
Features | News | Books | Physics | Space | Climate Change | Health | Technology | Natural World

Copyright © 1998 - 2016 Science a GoGo and its licensors. All rights reserved.

Powered by UBB.threads™ PHP Forum Software 7.7.5