100 fold improvement of LiPO discharge rates

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juk
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100 fold improvement of LiPO discharge rates

Post by juk » Thu, 12 Mar 2009, 22:01

Lithium batteries charge ahead
Researchers demonstrate cells that can power up in seconds.

Geoff Brumfiel


Coated electrodes allow lithium-ion cells to charge up in secondsGetty
Two researchers have developed battery cells that can charge up in less time than it takes to read the first two sentences of this article. The work could eventually produce ultra-fast power packs for everything from laptop computers to electric vehicles.

Byoungwoo Kang and Gerbrand Ceder of the Massachusetts Institute of Technology in Cambridge have found a way to get a common lithium compound to release and take up lithium ions in a matter of seconds. The compound, which is already used in the electrodes of some commercial lithium-ion batteries, might lead to laptop batteries capable of charging themselves in about a minute. The work appears in Nature1 this week.

Lithium-ion batteries are commonplace in everything from mobile phones to hybrid vehicles. "They're essentially devices that move lithium ions between electrodes," says Ceder. The batteries generate an electric current when lithium ions flow out from a storage electrode, float through an electrolyte, and are chemically bound inside the opposing cathode. To recharge the battery, the process is reversed: lithium ions are ripped from the cathode compound and sent back to be trapped in their anode store.

The speed at which a battery can charge is limited by how fast its electrons and ions can move - particularly through its electrodes. Researchers have boosted these rates by building electrodes from nanoparticle clumps, reshaping their surfaces, and using additives such as carbon. But for most lithium-ion batteries, powering up still takes hours: in part because the lithium ions, once generated, move sluggishly from the cathode material to the electrolyte.

Tunnel vision

That seemed to be the case for lithium iron phosphate (LiFePO4), a material that is used in the cathode of a small number of commercial batteries. But when Ceder and Kang did some calculations, they saw that the compound could theoretically do much better. Its crystal structure creates "perfectly sized tunnels for lithium to move through", says Ceder. "We saw that we could reach ridiculously fast charging rates."

So why hadn't anyone seen this speedy charging in practice? Ceder and Kang theorize that the lithium ions were having trouble finding their way to the crystal structure's express tunnels. The authors helped the ions by coating the surface of the cathode with a thin layer of lithium phosphate glass, which is known to be an excellent lithium conductor. Testing their newly-coated cathode, they found that they could charge and discharge it in as little as 9 seconds.

"As far as I know, this is the fastest yet for this material," comments Peter Bruce, a chemist at the University of St Andrews, UK. The researchers do not know exactly how the disordered glass helps lithium ions transfer between the electrolyte and the cathode.

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Other materials, such as nickel oxide, have achieved similarly fast charging rates, says John Owen, a chemist at the University of Southampton, UK. "This is a nice demonstration of the concept in a lithium system," he says. Lithium, though, can store more energy for less weight than nickel compounds, and holds its charge better.

It's particularly important because lithium iron phosphate is already being used commercially, adds Bruce. Speeding lithium ion movement would vastly improve energy recovery in hybrid vehicles, which recharge their batteries when the vehicle brakes — a process that lasts only seconds. It could also eventually lead to fully electric vehicles that could charge reasonably quickly.

Ceder says that he thinks that improvements in modelling will allow researchers to find other candidates for ultra-fast batteries. "My guess is that there are more materials like this out there," he says.

References
Kang, B. & Ceder, G. Nature 458, 190– 193 (2009).

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100 fold improvement of LiPO discharge rates

Post by juk » Thu, 12 Mar 2009, 22:04

Also from the same paper:

A battery research group out of MIT and led by Dr. Gerbrand Ceder just published remarkable research findings in the journal Nature.

The scientists were able to develop a new formulation of lithium iron phosphate that allows for extremely rapid charging, and massive specific power.

In the typical lithium ion cell when a current is applied to charge the cell, lithium ions move away from the cathode compound and are trapped at the anode storage medium. When the battery discharges producing current , those ions travel back to the cathode medium and in so doing produce current flow.

Speed of charging in typical lithium-ion cells is slowed by virtue of the fact that it takes time for the lithium ion to move off the cathode material. Various techniques have been tried to increase that speed including the nanoparticle doping strategy that A123 Systems uses. However recharge times still can take hours, and specific power is limited.

The scientists noted that lithium iron phosphate forms a lattice that creates small tunnels through which the lithium ions flow, but that although the cathode seemed ideal it still took some time for those ions to travel.

The novel solution they devised was to create a lithium phosphate glassy surface to coats these tunnels. This glassy surface acts as a speedway of sorts rapidly transporting the lithium ions on and off the cathode.

The result was startling.

Per the article “extremely high rates can be achieved for the active material: at a 200C rate (corresponding to an 18-s total discharge) more than 100mAh g can still be achieved, and a capacity of 60mAh g is obtained at a 400C rate (9 s to full discharge). Such discharge rates are two orders of magnitude larger than those used in today’s lithium ion batteries.”

The authors note that “Typical power rates for lithium ion battery materials are in the range of 0.5 to 2 kWkg. The specific power we observed for the modified LiFePO4 (170kWkg21 at a 400C rate and 90kWkg at a 200C rate) is two orders of magnitude higher.”

At this point the researchers have only tested the cells to 50 cycles but have noted no degradation.

The authors note that this new ability to charge and discharge lithium-ion batteries within seconds blurs the distinction between batteries and ultracapacitors, and may result in radical lifestyle change in terms of consumer electronic devices and plug-in cars.

Besides being able to charge one’s cellphone in seconds, this will have a major impact on electric cars.

The authors note that if electric grid power was available, an electric car with a 15kWh battery could be charged in 5 minutes. This would require the delivery of 180 kw of energy in that time frame. Further those cars could have extremely powerful acceleration and be useful in other power applications such as towing.

Lead author Ceder said “If manufacturers decide they want to go down this road, they could do this in a few years,” and noted the technology has already been licensed by two companies one of which includes, you guessed it, A123 Systems.

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100 fold improvement of LiPO discharge rates

Post by fuzzy-hair-man » Thu, 12 Mar 2009, 22:26

Wow!!! If that's true and can be as easily applied as the article suggests the high discharge Li Ion battery producers are probably in for a hard time (unless they license the technology) as well as the ultracap producers (as noted in the article) and fuel cell proponents, if your EV pack takes minutes to recharge then there seems little point to Hydrogen fuel cells doesn't there??? the difficulty might be finding some place that can draw that much electricity to push in to your EV battery pack Image

I guess we'll have to wait and see how their cycles beyond 50 go, at 400C and 200C it shouldn't take too long!! Image

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100 fold improvement of LiPO discharge rates

Post by Richo » Fri, 13 Mar 2009, 21:46

juk wrote: The authors note that this new ability to charge and discharge lithium-ion batteries within seconds blurs the distinction between batteries and ultracapacitors, and may result in radical lifestyle change in terms of consumer electronic devices and plug-in cars.
I'll un-blur it:
5,000 cycles for thier battery (being generous) v's 1,000,000 for an ultracapacitor.
juk wrote:
Further those cars could have extremely powerful acceleration and be useful in other power applications such as towing.
Talk about talking it up.
Since when is towing a "power application".
I have seen 3-cyl 1L cars towing.
Admittedly there were nubs for doing it.

They should have said for truck racing or something Image
So the short answer is NO but the long answer is YES.
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100 fold improvement of LiPO discharge rates

Post by woody » Fri, 13 Mar 2009, 22:15

Richo wrote:
Since when is towing a "power application".
Dad's camping trip didn't start promisingly...

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(yes it's my Dad's car + trailer, no he took the Prado instead)
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100 fold improvement of LiPO discharge rates

Post by Richo » Fri, 13 Mar 2009, 22:50

He gets points for trying Image
So the short answer is NO but the long answer is YES.
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100 fold improvement of LiPO discharge rates

Post by zeva » Wed, 18 Mar 2009, 07:56

Richo wrote: I'll un-blur it:
5,000 cycles for thier battery (being generous) v's 1,000,000 for an ultracapacitor.

And to unblur it further, we could consider energy density.. Ultracapacitors: 5-10 wh/kg, lithium batteries: 90-180 wh/kg.

(I'd say ultracaps are unlikely to find a role as a primary energy storage medium in EVs without some truly revolutionary advances in energy density.)
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100 fold improvement of LiPO discharge rates

Post by acmotor » Wed, 18 Mar 2009, 08:20

Yes, but ultra caps have increased energy density 10,000 times in 10 years. (sue me if you don't like the number !!) Probably more than hard disk capacity increases.
Lead acid 0.2 times (no) improvement.
Lithium <1 times hey maybe 10 times (but not in EV versions) but read on..

The PROSPECT for ultracaps is greater than any other technology at present although it is starting from behind the 8 ball.
i.e. an increase of 100 times in ultra cap capacity (and a BIG drop in price) would leave all the chemical batteries for absolute dead.

The increase in capacity will most likely come before the drop in price ? however.... supply and demand. I've said it before, sell your shares in Lithium !

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100 fold improvement of LiPO discharge rates

Post by Gow864 » Wed, 18 Mar 2009, 15:44

If you are not part of the solution, you are part of the problem.

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100 fold improvement of LiPO discharge rates

Post by woody » Wed, 18 Mar 2009, 17:15

Published in nature. Maybe we'll get something to replace our first or second pack of Lithiums.
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100 fold improvement of LiPO discharge rates

Post by Peter C in Canberra » Wed, 18 Mar 2009, 20:53

I'll have to replace my 240V/15Amp circuit with one rated to at least 750 Amps, probably 1kAmp to be safe. I would also have to hope I didn't have more than 2milliohms of internal resistance in the cells or in the various connections, otherwise I would hope the system could dissipate waste heat at over a kilowatt. The article didn't mention more than an electrode in a beaker on a lab bench. There may be a few issues to resolve for scale up and commercialisation.
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100 fold improvement of LiPO discharge rates

Post by Richo » Wed, 18 Mar 2009, 21:23

zeva wrote:I'd say ultracaps are unlikely to find a role as a primary energy storage medium in EVs without some truly revolutionary advances in energy density.


Mmmm I did read somewhere they were trying to grow a forrest of carbon nano-tubes for Ultracaps.
This would probably do it...
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100 fold improvement of LiPO discharge rates

Post by fuzzy-hair-man » Mon, 11 May 2009, 19:49

Quote taken from this thread(same topic) in an effort to get the topic all in the one place again.
coulomb wrote: I believe that this is based on the same Nature article that this thread is:

/forums/forum_posts.asp?TID=1011&PID=10411#10411

The consensus was I think that

1) this isn't all that much of a breakthrough; we already have C12 capable batteries (but maybe can't charge that fast, only discharge)
2) Even at C12, you need massive current (for EV size batteries) to charge in 5 minutes, let alone 18 seconds
3) It's only been demonstrated with tiny batteries so far.
Anyway I was wondering why everyone was so underwhelmed by this 'break through', I get that you'd need a large amount of electricity in the one place to be able to recharge this quickly and I don't have the knowledge to know how large this is likely to be or what impact that sort of demand might have on the grid.

Tiny batteries are a stepping stone and I don't expect I know anything about what it would take to scale it up but the article seemed pretty hopeful of being able to do so pretty quickly, I know they have a self interest but I'd also guess they are best placed to know the difficulties too.

These were 200C and 400C batteries not 12C, according to the article anyway, I figure if they can discharge or charge @ 200C they are likely to be much more robust than the current crop of batteries to fast charge and discharge, that's a significant step in itself isn't it? or am I missing something?

Crystal ball gazing:
Does it mean that your local electricity sub-station becomes your new 'petrol station' or does it mean that infra structure like petrol stations but for EVs will need something to store charge so that they are able to dump it quickly into EVs wanting to fill up quickly? this doesn't mean you can't charge slowly at home. To me this seems a more likely and achievable prospect than battery swapping, and it levels things up compared to fuel cells, you could use these quick charging stations only when you need to get going again quickly and you would expect to pay a premium for the service, paying for however the charging facility manages to store all that energy...

A Hydrogen filling station or electrolysis plant, depending how it was implemented would need some similarly beefy electricity infrastructure but governments and industry still see that as some what achievable.

Anyway I guess what I'm saying is having a battery that can recharge that quickly has removed one of the obstacles to quick recharges and therefore making EVs perform similarly to ICE vehicles in terms of refilling. Refilling recharging while you get a coffee or a snack seems reasonable, EV packs capable of 300 - 400km don't seem that far away and I doubt you'll find many people capable of driving for much over 8 hours in a day, so a 800km trip with a reasonable break (for food and recharge) seems doable to me and would make ICE drivers happy in terms of range for when they have to go that far.

Not having a go at coulomb by the way, I was just rather excited by the prospects I thought this brought and was curious what I was missing?

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100 fold improvement of LiPO discharge rates

Post by woody » Mon, 11 May 2009, 20:12

200C is a <20 second charge, 400C is <10 second charge. It gets pretty academic beyond that I would think :-)

Highest currently available charge rate I have seen is the EVPST-7,8 & 10 Ah cells, 10C (6 minute charge).

All these times I'm quoting are just 60/x for xC charge, charging to full would take longer as the last bit of charging is slower. I think you should be able to half charge in half the time if you are pretty flat already though, e.g. go from 30% to 80% in 3 minutes with a big enough charger. (720 Volts DC 100Amp = 72kW for a 10Ah Industrial AC system).

I think the biggest power point you can normally get in your Australian home is 20A three phase 415VAC which is about 12kW.
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100 fold improvement of LiPO discharge rates

Post by bga » Tue, 12 May 2009, 21:45

Gow864 wrote: and now for something completely different.

University of Miami physicist develops battery using new source of energy

Gow.


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The world population's grown a bit since I last checked! And the pool of winners seems a large for my prize to be very big. Image

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