Automotive

New tech could allow electric cars' body panels to store energy

QUT sees cars powered by their body panels a reality within five years (Photo: Shutterstock)
QUT sees cars powered by their body panels a reality within five years (Photo: Shutterstock)
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QUT sees cars powered by their body panels a reality within five years (Photo: Shutterstock)
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QUT sees cars powered by their body panels a reality within five years (Photo: Shutterstock)

Imagine opening up an electric car and finding no batteries. An absent-minded factory worker or magic? Perhaps neither. If nanotechnology scientists led by the Queensland University of Technology (QUT) are on the right track, it may one day be a reality as cars are powered not by batteries, but their body panels – inside which are sandwiched a new breed of supercapacitors.

Electric cars have a lot of advantages. They don’t directly use fossil fuels, they have zero emissions, and the high-end ones perform like a supercar, with an acceleration that leaves your back teeth at the starting line. The drawback is that they depend on very heavy batteries. At the low end, there are lead-acid types that weigh a staggering amount, while the high end vehicles use lithium-ion batteries that aren't much lighter. In theory, lightweight supercapacitors should do a better job with their ability to hold much higher charges, but in practice, aren't quite there yet.

It’s a matter of energy density. Lithium-ion batteries have a lot of energy, but are limited in how fast they can discharge it. Supercapacitors can release energy in large bursts, but don’t store as much as a Li-ion battery. The trick is to combine the two in the short term, while figuring out how to store more in the supercapacitor in the long term.

QUT is working on new lightweight supercapacitors, which are a thin, strong, high-energy density film made of two all-carbon electrodes sandwiched around an electrolyte. This film is intended to be set in car body panels, roofs, doors, bonnets and floors. The idea, in the short term, is to combine them with Li-ion batteries, where the supercapacitors can store enough energy to charge the battery in minutes.

"Vehicles need an extra energy spurt for acceleration, and this is where supercapacitors come in," says PhD researcher Marco Notarianni. "They hold a limited amount of charge, but they are able to deliver it very quickly, making them the perfect complement to mass-storage batteries. Supercapacitors offer a high power output in a short time, meaning a faster acceleration rate of the car and a charging time of just a few minutes, compared to several hours for a standard electric car battery."

According to QUT, a supercapacitor-powered car would have other advantages. For example, because supercapacitors use carbon and not rare earths like lithium, they’re much cheaper to produce and less toxic.

Supercapacitors and batteries are already being used in cars, which brings the weight down, but QUT sees a car powered by body panels inside of five years.

"In the future, it is hoped the supercapacitor will be developed to store more energy than a Li-ion battery while retaining the ability to release its energy up to 10 times faster – meaning the car could be entirely powered by the supercapacitors in its body panels, says Postdoctoral Research Fellow Dr Jinzhang Liu. "After one full charge this car should be able to run up to 500 km (310 mi) – similar to a petrol-powered car and more than double the current limit of an electric car."

The technology could also be adapted for smart phones with supercapacitor cases quickly charging the phone battery.

The team’s results were published in the Journal of Power Sources and Nanotechnology.

Source: QUT

17 comments
Freyr Gunnar
> it may one day How long after oil peak, ie. the end of cheap and abundant oil? > Electric cars have a lot of advantages. They don’t directly use fossil fuels Indeed. Indirectly, withouth oil, we can't build cars, electric or otherwise: No oil, no mining industry, no plastic. > they have zero emissions Locally, but certainly not on a national level, since the US, along with China and Germany, use a lot of coal-powered electric plants. Go nuclear. > Lithium-ion batteries have a lot of energy, but are limited in how fast they can discharge it They're also way too expensive. Even if Tesla can come up with a $40,000 EV in the next few years, that's still way too expensive for a lot of people. But still, combining a supercap and li-ion batteries is worth trying.
piperTom
"...and not rare earths like lithium,..." "Rare earth" refers to a specific set of 17 elements. Lithium is not one.
piperTom
It says "...the supercapacitors can store enough energy to charge the battery..." Then what's the point of having the battery?
Robert Wyatt
So what happens when you get in an accident and the electricity is discharged through your body?
EH
One of the main reasons to add supercapacitors is that they can handle hundreds of thousands or millions of charge-discharge cycles, which saves the battery from wearing out in acceleration / regenerative braking cycles. It requires a great deal of supercaps, though. It takes over 0.2kWh to get a 4464lb car (Tesla S, 60kWh battery) to 60mph, and you can't use all the theoretical energy in the capacitors because running at too high a voltage shortens service life and the capacitors can't be drained fully while maintaining power. Putting them in body panels may help with cooling, which is the other thing needed for long capacitor life. (Dark cars parked in the sun may be bad for the capacitors, though.) So if you can use 70% of the stored energy and the capacitor maximum voltage is a typical 2.5V, you need nearly 1/3 of a million farads of capacitor to buffer all that energy. With the most popular manufacturer's "Ultracapacitors", that 0.29kWh total energy is still less than 50 kilos (110lb) and 37 liters of space ( = 1/3 m = 13 inch cube). Even with 4 m^2 (43 sq ft.) of body panel capacitors, they'd still be about 1 cm thick. If they really are structural and not brittle, then these could be very strong and damage-resistant, but if the panels did get damaged, they would undoubtedly be very expensive to replace.
Cyndysub
Finally a good idea instead of all the co2 spewing hot rods. Check out this "New" material that is making the manufacturing of super capacitors much cheaper than using graphene: http://www.gizmag.com/hemp-high-performance-supercapacitor/33435/
Noel K Frothingham
piperTom, read the article again. The super capacitors and the batteries serve two separate purposes based upon their diverse operating characteristics. The article explains this quite clearly.
Zolartan
@Freyr Gunnar Nuclear Going nuclear while having the option of safer, cleaner and cheaper wind and solar power is not really clever. Have you read my reply to your comment here? http://www.gizmag.com/solar-powered-pathway-netherlands/34613/ Price of electric cars Yes the price is still pretty steep. But its already partially compensated by lower operating costs (lower maintenance and fuel costs). There are already electric cars selling for under 30 000 $ (http://en.wikipedia.org/wiki/Renault_Zoe) so no need to wait for a 40 000 $ Tesla. From an engineering standpoint electric cars are simpler compared to ones based on combustion engines. It can be expected that mass production will drive the costs for electric cars much lower in future. This also becomes obvious if you look at the cost development of batteries (main cost factor for electric vehicles) for the last few years and decades: they are falling. (http://cleantechnica.com/2013/07/08/40-drop-in-ev-battery-prices-from-2010-to-2012/) @piperTom Yes that does not really make sense as it is written in the article. EH correctly explained the advantage of having supercapacitors in electric cars. @Noel K Frothingham Well I think EH explained it much more clearly. Charging the capacitors to charge the batteries does not seem to make any sense. Electric cars already accelerate much better and sufficient compared to non-electric ones. Faster charging times only become a benefit if you also can store enough energy in the capacitors to drive without batteries for longer durations. If it is just enough to accelerate the car to 60 mph as EH calculated you will still need to charge the batteries giving you no charging time advantage.
thk
I bet the insurance premium would not come cheap. It takes just one dent.
DonGateley
As this technology develops it certainly has the potential to eventually displace the li-ion and be the only energy storage. What I find cool about it is that it places the battery with something that is external to the car. All over it. If these are thin and can be laminated on top of each other then the total energy capacity can be determined by the thickness of the body panel. There is a whole lot of surface area on a car's skin to be used for this. I absolutely love this brilliant and possibly revolutionary idea.
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