Researchers from Stanford University have discovered a relatively simple process for quickly producing lightweight, flexible batteries and super-capacitors out of everyday paper. Yi Cui, assistant professor of Materials Science and Engineering, reports his work in a paper titled "Highly Conductive Paper for Energy Storage Devices," published online in the Proceedings of the National Academy of Sciences.

Cui and his team are able to coat a sheet of paper with ink containing carbon nanotubes and silver nanowires to produce a highly conductive storage device. A paper supercapacitor may be especially useful for applications like electric or hybrid cars, which depend on the quick transfer of electricity. The paper supercapacitor's high surface-to-volume ratio gives it an advantage.

"These nanomaterials are special," Cui said. "They're a one-dimensional structure with very small diameters." The small diameter helps the nanomaterial ink stick strongly to the fibrous paper, making the battery and supercapacitor very durable. The paper supercapacitor may last through 40,000 charge-discharge cycles -- at least an order of magnitude more than lithium batteries. The nanomaterials also make ideal conductors because they move electricity along much more efficiently than ordinary conductors, Cui said.

"This technology has potential to be commercialized within a short time," said Peidong Yang, professor of chemistry at the University of California-Berkeley. "I don't think it will be limited to just energy storage devices," he said. "This is potentially a very nice, low-cost, flexible electrode for any electrical device."

Source: http://news.stanford.edu/news/2009/december7/nanotubes-ink-paper-120709....

Abstract: http://www.pnas.org/content/early/2009/12/04/0908858106.abstract