The national campaign to fill the roads of America with plug-in and hybrid cars is taking some strange twists and turns. Future generations of car batteries might be made of paper – or they might be created by a virus, as demonstrated in leading-edge battery research and development.
Even with the new directions in research and development, the battery’s underlying concept remains largely the same as when it was invented in 1800. The Italian scientist Alessandro Volta stacked layers of silver and zinc plates separated by pieces of a paper ink blotter soaked in a brine mixture of salt and water. The zinc and copper plates were the electrodes, and the solution on the blotters was the electrolyte.
However high-tech the design, everything about a battery begins and ends with the idea of opposite charges – positive and negative. Electrons move from the negative terminal, through a solid or liquid material called the electrolyte, to the positive terminal. The properties of the electrolyte control how quickly electrons are produced and how quickly they move from the negative to positive terminals.
Paper and Carbon Nanotubes
Researchers at Rensselaer Polytechnic Institute in Troy, New York are back to using paper with a high-tech twist. Carbon nanotubes are infused into a material that is 90 percent cellulose, virtually identical to ordinary paper. The nanotubes, which color the paper black, act as electrodes and allow the storage devices to conduct electricity. The results originally appeared online in RPI News on August 13, 2007.
The device functions as both a lithium-ion battery and a supercapacitor, which stores charge like a battery but has no electrolyte. The paper battery can provide the long, steady power output comparable to a conventional battery, as well as a supercapacitor’s quick burst of high energy. The ionic liquid electrolyte soaked into the paper is a liquid salt and contains no water, so it won’t freeze or boil. The paper battery also uses no toxic chemicals. Not only could it power electronic devices, but in larger configurations the paper battery could be molded into shapes like the door of a car.
The paper battery resulted from an accidental collaboration of three laboratories at Rensselaer, melding the contributions of students in the fields of chemistry and chemical engineering; materials science; and electrical engineering. Dr. Robert Linhardt’s group was making thin cellulose membranes to aid in kidney research. A student in another lab suggested carbon nanotubes to make the membranes stronger, and a student in the third lab saw the potential for use as a battery and supercapacitor.
“These students, from three different labs, through their creative energy and diverse talents drove this project to successful completion,” says Dr. Linhardt. “The biggest stumbling block in the initial discovery was getting our students from different disciplines speaking the same language and convincing their professors of the importance of their discovery.”
The researchers have formed a company called the Paper Battery Company. Now their goal is to take the process they began in the lab and adapt it to large-scale fabrication that would lend itself to commercial applications. They need to boost the battery’s energy capacity, and they need to lower the cost of making the batteries on a large scale. In addition to transportation, they hope to adapt their design for use with windmills and with photovoltaic cells, which produce electricity from sunlight. The batteries would be used to store energy for use when the sun is not shining or when the wind is not blowing.
Virus Battery Catching On
Researchers at Massachusetts Institute of Technology in Cambridge, Mass., have built a battery using a common type of virus that is not harmful to humans. The virus, called a bacteriophage, will infect bacteria but not humans. The development was reported in MIT News on April 9, 2009.
The MIT team believes the virus battery eventually could be used not only to power computers and other electronics, but also to power hybrid or electric cars. The battery is rechargeable, and the researchers believe it will last longer than conventional lithium-ion batteries. All the materials used in producing the virus battery are non-toxic. The virus is genetically engineered, and “self-assembles” both anode and cathode material, adhering to carbon nanotubes. The battery is then printed on flexible film.
"Viruses offer a new way of wiring batteries," said team leader and materials scientist Angela Belcher. "Now we have the anode material, the cathode material and the micro-contact printing method."
For practical applications, Belcher said the next steps are to "stamp out whole batteries, optimize their performance and scale up the technique for commercialization." In the long term, when the batteries are used up, they would not create any toxic chemical waste. “This is definitely a very clean approach,” Belcher said.
In 2009, the Obama Administration’s economic stimulus package included $2 billion to help develop battery technology for electric cars. As always, money should put plenty of charge into new research.
Sources
RPI News. Aug 13, 2007. "Beyond Batteries: Storing Power in a Sheet of Paper." News.rpi.edu. Accessed April 2010.
MIT News. April 2, 2009. "New Virus-Built Batteries Could Power Cars, Electronic Devices." MIT.edu. Accessed April 2010.
Mike Perricone - For nearly a decade, I served as Senior Editor and science writer in the Office of Public Affairs at Fermi National Accelerator Laboratory ...
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