Author: Bohac Adam
Date: September 2007
Researchers at Rensselaer Polytechnic Institute have developed a new energy storage device that is easily mistaken for a black piece of paper. The nanoengineered battery is lightweight, thin as a sheet of paper, extremely durable, and geared toward meeting any design and energy requirements of electronic devices, medical equipment, and transportation vehicles.
Researchers used ionic liquid, a type of liquid salt which contains no water, as the battery's electrolyte source. Since the battery contains nothing that can freeze or evaporate, it is capable of functioning in extreme temperatures. The battery has been tested in temperature ranging from three hundred degrees Fahrenheit to one hundred degrees below zero.
Another interesting feature of the paper battery is its ability to be rolled, twisted, folded, or cut without losing mechanical integrity or efficiency. The paper batteries can also be stacked to boost the total power output.
The paper battery is engineered to function both as a lithium-ion battery and a superconductor which are generally two separate components in electrical systems. The lithium-ion battery provides long, steady power output comparable to a standard battery where as the superconductor offers quick, high energy bursts. "It's essentially a regular piece of paper, but it's made in a very intelligent way," said paper co-author Robert Linhardt, the Ann and John H Broadbent Senior Constellation Professor of Biocatalysts and Metabolic Engineering 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 end result is a device that looks, feel, and weighs that same as paper."
The team printed paper batteries without adding electrolytes and demonstrated that naturally occurring electrolytes in human sweat and blood can be used to activate the device. "It's a way to power a small device such as a pacemaker without introducing any harsh chemicals such as the kind that are typically found in batteries into the body," said senior research specialist Victor Pushparaj. Research associate Shaijumon M Manikoth added, "because of the high paper content and lack of toxic chemicals, it's environmentally safe."
"The materials required to create the paper battery are inexpensive," said research associate Saravanababu Murugesan. "But the team has not yet developed a way to inexpensively mass produce the device. The end goal is to print the paper using a roll-to-roll system similar to how newspapers are printed." The device would enable important new engineering innovations.
The team has already filed a patent protecting the invention and is now working on ways to boost the efficiency as well as investigating different manufacturing techniques. Details of the project can be found in the paper "Flexible Energy Storage Devices Based on Nanocomposite Paper" published August 13 in the Proceedings of the National Academy of Sciences, or Rensselaer Polytechnic Institute's website at www.rpi.edu.
By Adam Bohac
Reviewer by: Brittany Raffa
Published by: Konrad Sawicki