magine 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.