3-D battery structure shows new twist in battery design

Oct 09, 2011 by Nancy Owano weblog
Bicontinuous battery electrode. Image: Nature Nanotechnology, doi:10.1038/nnano.2011.38

(PhysOrg.com) -- Battery life and driving range are two sticky phrases in discussions about why EVs have yet to hit mainstream use. Drivers still feel skittish about the idea of setting out on longer trips on batteries lasting too few miles and then losing time seeking a recharge. New developments in battery research may brighten the picture somewhat.

Eyes are trained on researchers at the University of Illinois at Urbana-Champaign, because they are doing research that may influence design.

Paul Braun, a professor of and engineering, working with graduate student Xindi Yu and postdoctoral researcher Huigang Zhang, has come up with a 3-D for battery cathodes. The result is a battery that can charge and discharge rapidly without compromising energy-storage capacity. Carry that into car talk, and it means a kind of battery that can be charged in as little time as it takes to fill up a car at a . As important, the rapid charge and discharge method does nothing to diminish the battery capacity.

Drivers, if empowered with a five-minute charge capability, would think of the task of charging in the same way they would an , said Braun. “You would just pull up to a charging station and fill up.”

The battery looks like a normal battery but the difference is inside. Braun and team wrapped a thin film into a 3-D structure and achieved high active volume and large current. Battery electrodes charged and discharged in a few seconds--ten to 100 times faster than equivalent bulk electrodes, in their demonstrations, but can perform normally in existing devices. Besides use in vehicles, the fast-charge battery design might also be useful in medical devices, lasers and military applications.

University of Illinois describes their process in more detail: They start off by coating a surface with tiny spheres and then pack them tightly into a lattice structure. The space between and around the spheres is filled with metal. Melting the spheres results in a spongelike 3-D scaffolding. The next step is electropolishing, a process that etches away the scaffold's surface, to enlarge the pores and make an open framework. The frame is coated with a thin film of the active material.

“The result is a bicontinuous electrode structure with small interconnects, so the lithium ions can move rapidly; a thin film active material, so the diffusion kinetics are rapid; and a metal framework with good electrical conductivity."

The group demonstrated both NiMH and Li-ion batteries, but any battery material, Braun said, that can be deposited on the metal frame can be used.

As such, Braun’s work is not focused on pushing any specific battery product forward. "This is not linked to one very specific kind of battery, but rather it’s a new paradigm in thinking about a battery in three dimensions for enhancing properties,” he said. The work has been supported by the U.S. Army Research Laboratory and Department of Energy.

Earlier this year, the paper, "Three-dimensional bicontinuous ultrafast-charge and -discharge bulk battery electrodes," authored by Braun, Xindi Yu and Huigang Zhang, was published in Nature Nanotechnology.

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semmsterr
not rated yet Oct 09, 2011
Please hurry and bring it on!!!
Isaacsname
5 / 5 (1) Oct 09, 2011
I must not be following these things closely enough, I thought this type of construction was old hat. So there is a benefit to this over using metalic foams for scaffolding ? And why do they use spheres ? If surface area is the main concern ,why not something that allows closer packing like truncated octahedrons ?
wealthychef
not rated yet Oct 09, 2011
How far from production are we? To most readers, this is the important informatIon: what obstacles are left to bring it to market?
jimbo92107
5 / 5 (2) Oct 09, 2011
So there is a benefit to this over using metalic foams for scaffolding ? And why do they use spheres ? If surface area is the main concern ,why not something that allows closer packing like truncated octahedrons ?


Research! These people are finding out what nature allows, not designing a finished product! They may well get around to octahedrons and other fun shapes, but spheres are easy to make, unlike foams they have a consistent size, and they stack naturally in a geometric lattice.

What I like is they're using well known industrial processes. That means other teams can use this technique to test other materials. Good progress.
pokerdice1
not rated yet Oct 09, 2011
If there was a way to use the sulfur-infused carbon nanotube with this technique this would be really big!

www.physorg.com/n...ery.html

I think the methods for creating the spheres would need to be vastly different. The melting charactaristics of the sulphur-infused nanotubes would be utterly different.

With that in mind, I wonder if the tubes could be immersed in sulphur non-reactive medium(bath) whereby fluid tensions could curl them up into spheres around the sulphur during preproduction. What kind of medium and coditions could we use to get the desired affect? Any ideas?
Jayman
1 / 5 (1) Oct 10, 2011
Can't wait. I'd love to see the look on the faces of the Arabs when we tell them to keep their oil. $1 a barrel may not be a stretch.