At Stanford, Nanotubes + Ink + Paper = Instant Battery
Stanford University scientists are harnessing nanotechnology to quickly produce ultra-lightweight, bendable batteries and supercapacitors in the form of everyday paper. Simply coating a sheet of paper with ink made of carbon nanotubes and silver nanowires makes a highly conductive storage device, said Yi Cui, assistant professor of materials science and engineering. "Society really needs a low-cost, high-performance energy storage device, such as batteries and simple supercapacitors," he said. Like batteries, capacitors hold an electric charge, but for a shorter period of time. However, capacitors can store and discharge electricity much more rapidly than a battery.
Above: Post doctoral students in the lab of Prof. Yi Cui, Materials Science and Engineering, light up a diode from a battery made from treated paper, similar to what you would find in a copy machine. The paper batteries are treated with a nanotube ink, baked and folded into electrical generating sources like the one wrapped in foil seen here. (Video Credit: Stanford University)
"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. Cui had previously created nanomaterial energy storage devices using plastics. His new research shows that a paper battery is more durable because the ink adheres more strongly to paper (answering the question, "Paper or plastic?").
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