New battery material could lead to rapid recharging of many devices

Mar 11, 2009
A sample of the new battery material that could allow quick charging of portable devices. Photo / Donna Coveney

(PhysOrg.com) -- MIT engineers have created a kind of beltway that allows for the rapid transit of electrical energy through a well-known battery material, an advance that could usher in smaller, lighter batteries — for cell phones and other devices — that could recharge in seconds rather than hours.

The work could also allow for the quick recharging of batteries in , although that particular application would be limited by the amount of power available to a homeowner through the electric grid.

The work, led by Gerbrand Ceder, the Richard P. Simmons Professor of Science and Engineering, is reported in the March 12 issue of Nature. Because the material involved is not new — the researchers have simply changed the way they make it — Ceder believes the work could make it into the marketplace within two to three years.

Scanning electron micrograph of a particle of the new battery material. Dark area indicates the inside of the particle surrounded by a lighter surface layer only five nanometers wide. Image courtesy / Ceder Lab

State-of-the-art have very high energy densities — they are good at storing large amounts of charge. The tradeoff is that they have relatively slow power rates — they are sluggish at gaining and discharging that energy. Consider current batteries for electric cars. "They have a lot of energy, so you can drive at 55 mph for a long time, but the power is low. You can't accelerate quickly," Ceder said.

Why the slow power rates? Traditionally, scientists have thought that the lithium ions responsible, along with electrons, for carrying charge across the battery simply move too slowly through the material.

About five years ago, however, Ceder and colleagues made a surprising discovery. Computer calculations of a well-known , lithium iron phosphate, predicted that the material's lithium ions should actually be moving extremely quickly.

"If transport of the lithium ions was so fast, something else had to be the problem," Ceder said.

Further calculations showed that lithium ions can indeed move very quickly into the material but only through tunnels accessed from the surface. If a at the surface is directly in front of a tunnel entrance, there's no problem: it proceeds efficiently into the tunnel. But if the ion isn't directly in front, it is prevented from reaching the tunnel entrance because it cannot move to access that entrance.

Ceder and Byoungwoo Kang, a graduate student in materials science and engineering, devised a way around the problem by creating a new surface structure that does allow the lithium ions to move quickly around the outside of the material, much like a beltway around a city. When an ion traveling along this beltway reaches a tunnel, it is instantly diverted into it. Kang is a coauthor of the Nature paper.

Using their new processing technique, the two went on to make a small battery that could be fully charged or discharged in 10 to 20 seconds (it takes six minutes to fully charge or discharge a cell made from the unprocessed material).

Ceder notes that further tests showed that unlike other battery materials, the new material does not degrade as much when repeatedly charged and recharged. This could lead to smaller, lighter batteries, because less material is needed for the same result.

"The ability to charge and discharge batteries in a matter of seconds rather than hours may open up new technological applications and induce lifestyle changes," Ceder and Kang conclude in their Nature paper.

Source: Massachusetts Institute of Technology (news : web)

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User comments : 9

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earls
not rated yet Mar 11, 2009
So what is currently blocking the tunnels?

Five years ago?!
MrGrynch
5 / 5 (1) Mar 11, 2009
The surface contour of the material prevents the ions from "finding" a nearby tunnel. The new surface, automatically channels ions toward a tunnel. Seem to me all they did was create a gradation surrounding the tunnels so that the ions can only fall to one side or the other, and not up against a flat surface.
fixer
not rated yet Mar 12, 2009
Anyway, It's a good idea.
It will really punch up electric cars into an affordable bracket, so long as oil companies don't buy them out.
directintel
not rated yet Mar 12, 2009
Does this mean that substantially less energy is required to recharge or that the same amount of energy is required but it's just used much faster?
JohnSawyer
not rated yet Mar 12, 2009
MrGrynch: "All they did"? Trying to live up to your username?

directintel: It probably takes the same amount of energy to charge a battery made from this differently-manufactured material, since the total capacity is not increased, but it charges faster.
david_42
not rated yet Mar 13, 2009
"limited by the amount of power available to a homeowner through the electric grid"

But, with a low enough charge time, it becomes reasonable to establish commercial recharging stations. The next problem becomes dissipating the heat during recharge. A low internal resistance reduces the problem, but likely it will become the limiting factor. Actively-cooled systems, such as the Tesla Roadster's power pack, would be the logical approach.
joefarah
not rated yet Mar 13, 2009
Wait a minute - how is this different from lithium titanate batteries that Altair Nanotechnologies has been developing for years now. It seems to charge and discharge about at the same speed, and they have demonstrated recharging an electric car in 10 minutes. Acceleration is instant, and in fact, these electric cars have set speed/acceleration records. I agree the science is interesting, but not new.

As well, the charging resistance is sufficiently low that overheating is not a problem. On top of that, the batteries have excelled in puncture tests, heat tests and other typical auto tests, without any catching fire, although the comparable lithium ion batteries failed miserably.
Newbeak
not rated yet Mar 15, 2009
If electric vehicles are to become widely used,the ability of utilities to supply the massive current draw must be addressed.This would be especially true if a fast charge battery were to emerge. One solution could be to give charging stations a way of storing power gradually,so that they could supply the huge current draw to feed the fast charge batteries.Perhaps a flywheel power storage system?
zevkirsh
not rated yet Mar 16, 2009
the true dawn of electric powered cars begins when existing gas stations can begin adding electric charging pumps beside the ordinary gasoline pumps and have electric car drivers get their 150 mile range charge as fast as they would to fill up an average gasoline tank. project better place and other dedicated infrastructure visions for electric charging are going down a futile path. the only way for electric to begin succesfully catching up with gas ( it hasnt even begun to catch up) is to piggyback off of existing infrastructure. not to build its own. that is far too expensive, and much much more importantly, requires the average consumer to make a giant leap of effort in changing their fueling habbits.

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