HJ-ED-DHJHerald Journal Columns
August 20, 2007, Herald Journal

Nano-engineered ‘paper’ battery created

By MARK OLLIG

Just when you thought we have seen everything – hold onto those laptop computers, folks. Now, they have come out with a battery that is made of paper.

Cellulose, an organic plant compound, makes up most of the paper, cotton, and linen products that we use every day.

Will cellulose become the next generation component for our batteries, too?

A working prototype “paper battery” has been created by the researchers at Rensselaer Polytechnic Institute in New York. This battery is made out of 90 percent cellulose, which is also used in our loose-leaf paper, newsprint, and grocery bags.

This paper battery, however, has a coating of lithium and contains carbon nanotubes.

The photo I saw of this working prototype looks like a thin sheet of black paper that measures roughly an inch square.

What is cool about this piece of paper is that it holds an electrical charge.

The paper battery is actually bendable (which I saw in the photo), and the application uses for a battery like this are endless.

This battery operates using the same electrical principles as any normal battery used today.

In my research, I discovered that the paper battery can be as large as a regular newspaper page, or it can be cut down to the size of a postage stamp.

This new battery can be rolled, twisted, folded, or cut into any number of shapes without damage or loss of efficiency. Paper batteries can also be “stacked” or connected together like a ream of printer paper to increase the total power output.

“It’s essentially a regular piece of paper, but it’s made in a very intelligent way,” said Professor Robert Linhardt, at Rensselaer.

“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.”

The operating temperatures of this battery are extreme – it is rated at -100 degrees below zero to 300 degrees Fahrenheit, so it is very possible this might be the battery NASA would use on future space satellites or to provide power in electronic systems that will be on the next mission to the moon.

Another use of this paper is it can be inserted under the human skin to power medical devices such as pacemakers.

Some printed paper batteries were made without adding any electrolytes. This research demonstrated that the naturally-occurring electrolytes in human sweat, blood, and other fluids inside the human body could be used to provide the “power” from which the battery would draw upon.

Professor Robert Linhardt says he foresees such paper batteries replacing the versions used today – similar to how the transistor replaced vacuum tubes.

“I think, over time, we’ll replace what we’re using as a battery,” Professor Linhardt said.

Lindardt and other researchers have already manufactured a postage-stamp-sized battery that has enough energy to power a small fan.

The paper battery was engineered to also function as a lithium-ion battery that will provide the steady power output comparable to a conventional battery.

This new device can also act as a “supercapacitor.” In this case the supercapacitor is defined as an electrical component that provides a quick burst of energy.

Supercapacitors are also used in automotive applications for hybrid vehicles and as supplementary storage for battery electric vehicles.

Professor Linhardt anticipates 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 other applications.

The invention of the paper battery actually came about by accident. A team of Professor Lindardt’s students was working on fragile paper-like cellulose sheets for medical research and trying to find a way to strengthen them. The team thought of using carbon “nanotubes” as reinforcement, just like using steel rods in concrete.

The nanotubes act as electrodes and allow the storage devices to conduct electricity.

The team realized that the sheet of paper could be used as a battery.

The students used “ionic liquid”, which is basically a liquid salt, as the battery’s electrolyte. This ionic liquid contains no water, which means there’s nothing in the batteries to freeze or evaporate. This lack of water allows the paper energy storage devices to withstand the extreme temperatures I mentioned earlier.

After 18 months, they perfected a working version of this paper battery in their laboratory.

This team of researchers has already filed a patent for its invention.

Korea and Finland are also developing paper battery technology.

More information can be found at the Rensselaer Polytechnic Institute web site located at http://www.rpi.edu/. The link to the paper battery is at http://news.rpi.edu/update.do.