What if your cell phone didn't come with a battery? Imagine, instead, if the material from which your phone was built was a battery.
The promise of strong load-bearing materials that can also work as batteries represents something of a holy grail for engineers. And in a letter published online in Nano Letters last week, a team of researchers from Vanderbilt University describes what it says is a breakthrough in turning that dream into an electrocharged reality.
The researchers etched nanopores into silicon layers, which were infused with a polyethylene oxide-ionic liquid composite and coated with an atomically thin layer of carbon. In doing so, they created small but strong supercapacitor battery systems, which stored electricity in a solid electrolyte, instead of using corrosive chemical liquids found in traditional batteries.
(Photo: Nano Letters)
These supercapacitors could store and release about 98 percent of the energy that was used to charge them, and they held onto their charges even as they were squashed and stretched at pressures up to 44 pounds per square inch. Small pieces of them were even strong enough to hang a laptop from—a big, fat Dell, no less.
Although the supercapacitors resemble small charcoal wafers, they could theoretically be molded into just about any shape, including a cell phone's casing or the chassis of a sedan.
They could also be charged—and evacuated of their charge—in less time than is the case for traditional batteries.
"We've demonstrated, for the first time, the simple proof-of-concept that this can be done," says Cary Pint, an assistant professor in the university's mechanical engineering department and one of the authors of the new paper. "Now we can extend this to all kinds of different materials systems to make practical composites with materials specifically tailored to a host of different types of applications. We see this as being just the tip of a very massive iceberg."
Pint says potential applications for such materials would go well beyond "neat tech gadgets," eventually becoming a "transformational technology" in everything from rocket ships to sedans to home building materials.
"These types of systems could range in size from electric powered aircraft all the way down to little tiny flying robots, where adding an extra on-board battery inhibits the potential capability of the system," Pint says.
And they could help the world shift to the intermittencies of renewable energy power grids, where powerful batteries are needed to help keep the lights on when the sun is down or when the wind is not blowing.
"Using the materials that make up a home as the native platform for energy storage to complement intermittent resources could also open the door to improve the prospects for solar energy on the U.S. grid," Pint says. "I personally believe that these types of multifunctional materials are critical to a sustainable electric grid system that integrates solar energy as a key power source."