Electrically Powered Ultralight Aircraft

On Fri, 17 Aug 2007 11:28:06 -0700, Phil wrote
in .com:

It might be possible to get enough capacity
there for a practical general aviation electric plane.

It might indeed. But I'd have to know more about the paper battery
specifications before I could render any sort of judgment. I guess
we'll have to wait until more information is disclosed. Let's see
.....



http://www.eetimes.com/news/semi/rss...etimes_semiRSS

Paper battery is rechargeable

R. Colin Johnson
EE Times
(08/14/2007 9:42 AM EDT)

PORTLAND, Ore. — Rensselaer Polytechnic Institute researchers
said they have developed a paper-thin battery by immersing a
carpet of vertical nanotubes in an ionic liquid electrolyte. The
result is a cellulose paper that stores electrical energy.

The RPI team produced a supercapacitor by placing a second
nanotube electrode on the other side of the paper. They then added
a lithium electrode atop the paper, creating what they claim is a
paper-thin rechargeable battery.

"The carbon nanotubes are embedded in the paper, and the
electrolyte is soaked into the paper, so it really looks, feels
and weighs about the same as paper," said RPI professor Robert
Linhardt.

The supercapcitor and rechargeable battery are the result of a
year and half of collaborative research among three RPI labs. One
lab was making carbon nanotube-based structures, which were
adapted to serve as a battery electrode. By growing the nanotubes
vertically on a sheet, liquid cellulose was poured between the
"forest of nanotubes" to form the battery. Another lab added a
lithium-based top electrode to create either a rechargeable
battery
or a supercapacitor by adding a second nanotube electrode.

Ionic liquids first dissolved the cellulose, turning it into a
gel.
The fluids also serve as the battery electrolyte, carrying ions
from one side of the paper battery to the other.

Each sheet of battery-paper generated about 2.4 volts with a power
density of about 0.6 milliamps/cm2. For higher voltages, paper can
be stacked. For more current, the sheets can be expanded to larger
areas. The battery-paper operates from minus 100 degrees up to 300
degrees Fahrenheit, and can deliver quick surges of current, the
RPI researchers claim. It can also be rolled twisted or cut into
many shapes.

So far, the RPI researchers have only cycled their paper batteries
through 100 rechargings. But they claim no deterioration in
performance has been detected after recharging. Next, they plan
long-term testing of the batteries to determine the maximum number
of rechargings, and to optimize the design for higher power
densities. ...



http://www.uberreview.com/2007/08/fl...-institute.htm
It does not function better than existing batteries on the market
and at present it is extremely expensive to produce.


http://news.rpi.edu/update.do?artcenterkey=2280
Contact: Michael Mullaney
Phone: (518) 276-6161
E-mail:

“We’re not putting pieces together – it’s a single, integrated
device,” he said. “The components are molecularly attached to each
other: the carbon nanotube print is embedded in the paper, and the
electrolyte is soaked into the paper. The end result is a device
that looks, feels, and weighs the same as paper.”




Can someone make the necessary conversions to compare the power
density of about 0.6 milliamps/cm2 for the paper battery to secondary
lithium-ion Polymer batteries at 130 - 1200 Wh/kg*?



* http://xtronics.com/reference/energy_density.htm

The original paper battery article is available on-line:

http://www.pnas.org/cgi/content/abst...urcetype=HWCIT
Proceedings of the National Academy of Sciences of the United States
of America

Published online before print August 15, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0706508104


This Article

Full Text (PDF)
Articles by Pushparaj, V. L.
Articles by Ajayan, P. M.


Engineering
Flexible energy storage devices based on nanocomposite paper

To whom correspondence should be addressed.

Pulickel M. Ajayan, E-mail: