Chemists from Rice University have developed a new technology for energy storage, but if you don't look close enough, you might miss it.
It's only one one-hundredth of an inch thick.
The thin film is flexible and contains the best qualities of high-energy batteries, but without the lithium. The research of chemist James Tour and c0-authors Yang Yang, a postdoctoral researcher, and graduate student Gedeng Ruan have appeared in the Journal of the American Chemical Society.
"Compared with a lithium-ion device, the structure is quite simple and safe," Yang said. "It behaves like a battery but the structure is that of a supercapacitor. If we use it as a supercapacitor, we can charge quickly at a high current rate and discharge it in a very short time. But for other applications, we find we can set it up to charge more slowly and to discharge slowly like a battery."
Called an electrochemical capacitor, the film contains nanoporous nickel-fluoride electrodes layered around a solid electrolyte designed to "deliver battery-like supercapacitor performance" for various portable electronics on the market. Though it's tiny, the capacitor could be scaled up for devices either by increasing the size or adding layers, researchers said. They also believe it could be manufactured to be even thinner.
Tour and company set out to find a material with the flexible qualities of graphene, carbon nanotubes and conducting polymers while possessing much higher electrical storage capacity typically found in inorganic metal compounds. While testing, the students found that the square-inch device held 76 percent of its capacity over 10,000 charge-discharge cycles and 1,000 bending cycles.
“This is not easy to do, because materials with such high capacity are usually brittle,” Tour said. “And we’ve had really good, flexible carbon storage systems in the past, but carbon as a material has never hit the theoretical value that can be found in inorganic systems and nickel fluoride in particular.”
The Peter M. and Ruth L. Nicholas Postdoctoral Fellowship of the Smalley Institute for Nanoscale Science and Technology and the Air Force Office of Scientific Research’s Multidisciplinary University Research Initiative supported the chemists' research.
"The numbers are exceedingly high in the power that it can deliver, and it’s a very simple method to make high-powered systems,” Tour said, adding that the technique shows promise for the manufacture of other 3-D nanoporous materials. “We’re already talking with companies interested in commercializing this.”
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