By coating a sheet of paper with ink made of carbon nanotubes and silver nanowires, the scientists were able to construct a highly conductive storage device that's both low-cost and high-performance.
(The difference between a battery and a capacitor, you ask? both hold energy to be converted to electricity, but capacitors hold it for a shorter period of time. On the other hand, they can store and discharge energy much more rapidly.)
The batteries are so strong that you can crumple them and the performance does not degrade.Led by assistant professor of materials science and engineering Yi Cui, who previously created nano-size batteries using plastics, the researchers developed a solution that is more durable than conventional batteries.
Since the nanomaterials have very small diameters, the nanomaterial ink sticks strongly to the fibrous paper. That means they're more durable -- to the measure of 40,000 charge-discharge cycles, far more than conventional lithium-ion batteries -- and are more efficient conductors.
The paper batteries are so strong, in fact, that you can crumple or fold them -- or even soak them in acidic or basic solutions -- and the performance does not degrade.
Don't believe it? Here's a look:
That flexibility means the paper batteries can be used in as diverse applications as wallpaper or hybrid electric vehicles, thanks to a paper capacitor's high surface-to-volume ratio.
In fact, Cui said the biggest impact could be in large-scale electricity storage on the distribution grid. Example: excess electricity generated at night could be saved for peak-use periods during the day.
"The most important part of this paper is how a simple thing in daily life – paper – can be used as a substrate to make functional conductive electrodes by a simple process," Yang said in a statement. "It's nanotechnology related to daily life, essentially."
Cui's research team includes postdoctoral scholars Liangbing Hu and JangWook Choi, and graduate student Yuan Yang.
The paper, "Highly Conductive Paper for Energy Storage Devices," is published online this week in the Proceedings of the National Academy of Sciences.