Researchers at Stanford University have come up with a way to make ultra lightweight and flexible batteries and supercapacitors out of paper. All they had to do was coat a sheet of paper with special ink made out of carbon nanotubes and silver wires. The result is a highly conductive storage device that can function as a battery or a supercapacitor.
Yi Cui, assistant professor of materials science and engineering at Stanford, previously researched plastic coated with ink containing nanotubes, but found that paper worked better. The ink adheres better to the paper since its absorbed into the pores in the paper, plus you can crumple or fold up the paper and it still works! Cui says that a paper supercapacitor could be especially useful in electric or hybrid cars, since they depend on the quick transfer of electricity, and are much lighter nickel-hydride or lithium-ion batteries. The high surface to volume ratio of the paper supercapacitor gives it an advantage. Other applications of the paper battery would be large scale storage of electricity on the power grid, where it can be used to store excess electricity produced by solar plants and wind farms.
“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.