A cleaner, faster battery

Jul 09, 2012
The nanocrystal structures used in the batteries. Green arrows represent discharging, while purple represent charging. Current flows in through the iron-carbon nanostructure (left) and out through the nickel-carbon nanotube structure (right).

A team of Stanford and Canadian Light Source researchers have developed an ultrafast rechargeable battery from non-toxic materials.

This new uses nanostructures to update a century-old idea: the nickel-iron bat-tery. Those early batteries, developed by in 1901 to power electric cars, have been out of favour for a while. In addition to taking a long time to recharge, they just weren’t as powerful as other sources.

There are, however, compelling reasons to improve the batteries’ efficiency.

“Nickel-iron batteries are attractive because they are cheap and, relative to other battery materials like lithium, they are not very toxic,” explained Dr. Jigang Zhou, a Canadian Light Source Industry Scientist who worked on the project.

Stanford’s Dr. Hongjie Dai and his research team worked with CLS scientists as well as a researcher in Beijing to develop a much faster nickel-iron battery.

The new battery charges in less than two minutes, thanks to a newly developed carbon nanostructure. To achieve the desired conductivity, the team grew nanocrystals of iron oxide on thin sheets of car-bon, and nickel nanocrystals on carbon nanotubes. Traditional batteries lack this structure, mixing iron and nickel with conductors more or less randomly.

The result was a strong chemical bond between the materials, which the team identified and studied at the Canadian synchrotron. The CLS team also included Staff Scientist Tom Regier and Research Associate Jian Wang, who lent their synchrotron expertise to the Stanford team.

“The title of the paper has the term ‘strongly coupled,’ and this is important. This strongly coupled material is needed to deliver ultrafast [batteries],” Zhou said.

Strong coupling between materials makes it much easier to pass electrons -- the currency of electric flow -- just as it’s faster to give someone money when they’re sitting right next to you, than to have to cross the room to do it. The smaller the gap, or the more strongly coupled the materials are, the faster electrons move.

“You can only check if it is strongly coupled by the technique that we did here. There are other beam-lines that can do, in principle, similar work, but this is one of the best soft X-ray beamlines in the world.”

So as a result of the strong coupling identified and studied at the synchrotron, these batteries are able to charge and discharge ultrafast. However, the batteries have a limited life. They can only be re-charged about 800 times before their usable life is over.

Zhou hopes to study other potential benefits to these strongly coupled materials, and gather more information about their structures and how they change over time. Future work to understand structur-al changes over time will help researchers develop a longer-lasting, and potentially even faster, ver-sion of the .

This work represents a small part of the possible uses of synchrotron science in developing new energy applications and exploring new .

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Bob_Wallace
1 / 5 (1) Jul 09, 2012
800 cycles is not a problem if the cost is truly low. If your EV is designed for a rapid battery swap, changing out battery packs every few years would not be an issue. Better Place swaps out batteries in less than five minutes in their EVs.

What's the weight to capacity number? These things light enough to be used in EVs/PHEVs?

gopher65
not rated yet Jul 09, 2012
Bob_Wallace: Indeed. While I understand completely the issues with current electric cars, when people start bringing up the maintenance issues associated with EVs (like replacing batteries), I look at them like they're crazy. Maintenance costs? Yeah, sure. Those are too high right now. But it's like they expect EVs to be maintenance free.

I mean, have they ever owned a car? Got oil changes done? Had their air filters replaced? Run low on transmission fluid? Geez. Ongoing maintenance is part of owning a car, and the costs really add up.

Once the price of batteries comes down to more reasonable levels, swapping out batteries when they fall to 70% max capacity won't be any more difficult than an oil change or wheel alignment.
mrlewish
1 / 5 (1) Jul 11, 2012
gopher65:
So you think manufactures will make it so simple to swap out batteries? They spend half their time designing EV just to make sure that you can't do that. If it were easy to swap that would quickly make a EV battery aftermarket viable. The manufactures don't like competition. That is why they are in apparent lock step in the introduction of slowly "improving" EVs.

I'm just paranoid.. but am I paranoid enough?
Bob_Wallace
1 / 5 (1) Jul 11, 2012
Paranoid? Speak to your therapist about that.

Simple to swap EV batteries. Right now Renault makes an EV that is being sold in Israel and Denmark for use with Better Place's battery swapping stations. Customer drives in with an almost 'empty' battery, drives out with a fully charged battery in less than five minutes.

You can see how it works here...

http://www.youtub...T5NUHyxs

If someone can come up with a truly cheap "800 cycle" battery one manufacturer will use it because it will give them tremendous market advantage. Other companies will be forced to follow.