Get a charge out of this: a foldable battery

by Patrick Brethour

Globe and Mail Update
August 14, 2007

VANCOUVER - It looks like a simple sheet of black paper, but it 
could spell a revolution in battery technology - not to mention an end 
to the miserable Canadian ritual of plugging in the car on frigid 
winter nights.

Researchers at the Rensselaer Polytechnic Institute in New York 
have come up with a working prototype of a battery made out of 
cellulose, a coating of lithium and carbon tubes the size of a virus: 
a sheet of black paper that stores an electrical charge.

While it works on the same principle as any battery for sale in a 
corner store, the paper battery from Rensselaer is much different 
than a typical AA. 

For starters, it can be as large as a newspaper page, or cut to the 
size of a postage stamp. It can be inserted under human skin, and 
be powered in part by body fluids.

Most important, the paper battery keeps functioning even at extreme 
temperatures, from -73 degrees to 148 degrees, meaning that it 
could be put to work in outer space. 

Rensselaer professor Robert Linhardt says he foresees such paper 
batteries (which can also double as a car ignition and other kinds 
of supercapacitors) displacing the metal-and-acid versions in 
common use today, much as integrated microprocessor computer 
circuits have taken the place of bulky vacuum tubes.

“I think over time we'll replace what we're using as a battery,” 
he said.

However, for the moment, those ambitions are mostly hope. He and 
his fellow researchers have manufactured a postage-stamp-sized 
battery that can power a small fan or an LED device. 

Dr. Linhardt says the device works, but cost will be the biggest 
barrier - which is why use in the extreme cold of outer space by 
customers with budgets running into the billions is the most 
promising takeoff point for the technology.

“If you need something to work in outer space, money is no object,” 
he said.

The paper battery also holds promise in medicine, where it could be 
implanted under a patient's skin and used to power medical devices 
such as pacemakers. And it can use electrolytes in bodily fluids 
such as sweat or blood to draw power. In a paper published yesterday, 
the Rensselaer team details its efforts, including the use of urine to 
power a test version in the lab.

Dr. Linhardt hopes that technological fine-tuning and the economies 
of mass manufacture can reduce the selling price to the point where 
the paper battery could be used to power hybrid cars and a wide 
range of other applications, 

Other paper batteries are in development, including one in Korea and 
another in Finland. “We're just one player in a competitive field,” 
he said.

Despite its promise, the invention of Rensselaer's paper battery was 
pretty much an accident. 

Some of Dr. Linhardt's students were working on cellulose sheets 
for medical use and were searching for ways to strengthen the 
somewhat fragile sheets. 

They came upon the idea of using carbon nanotubes as reinforcement, 
serving much the same function as steel rods in concrete. 

And then there was a eureka moment, when the team realized that 
the sheet of paper could be used as a battery. 

It took 18 months to get a version working in the lab, but Dr. Linhardt 
said the paper battery has enormous potential, which could 
overshadow other high-profile innovations he has worked on in his 
three-decade career, including anti-clotting drugs. “This is potentially 
bigger.”