22 April 2009—The field of printable electronics has taken off in recent years, with researchers touting prototype wearable sensors, smart packaging labels, and even solar cells made with printing technology. However, little advancement has been made in developing printable, flexible energy-storage devices, such as supercapacitorsand batteries.
Now researchers from Stanford University and the University of California, Los Angeles, have built a flexible supercapacitor out of printable carbon nanotubes and polymer gel electrolyte. Their results were detailed this month in Nano Letters .
George Grüner, a physics professor at UCLA who led the research, says that printing supercapacitors could one day be as simple and cheap as making photocopies or printing a newspaper.
The researchers built the supercapacitor by spraying carbon nanotubes onto two thin plastic substrates. In between the two substrates they sandwiched a polymer gel electrolyte, which acts to separate the charges at the interface of the carbon nanotubes and the gel. Carbon nanotubes are ideal for flexible, printable electronics because they are lightweight and can bend and stretch without breaking or compromising their electrical properties.
”Many people have been trying to build a printable supercapacitor,” says Chongwu Zhou, associate professor of electrical engineering at the University of Southern California, speaking about his own research group as well. Zhou recently demonstrated a flexible and transparent supercapacitor, but it was not made using printing technology, which he is working on now.