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.
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.”
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