Brown team developing a battery made of plastic

Imagine a flashlight powered by the energy stored within its plastic molding. If that sounds too unbelievable to be true, then you probably haven’t talked to Brown University’s Tayhas Palmore.

The engineering professor and Hyun-Kon Song, a former researcher at Brown who now works at LG Chem in South Korea, have developed a new battery using plastics able to conduct electricity. The findings of a study on the batteries were published in the August issue of the journal Advanced Materials – and Palmore said she has received calls from two firms interested in licensing the technology. She declined to name them.

Basically, the engineers have added so-called “redox-active” compounds to a plastic or polymer called “polypyrrole.” The compounds have a high affinity for electrons; they react to make energy that is transferred through the polymer.

The engineers’ prototype is paper-thin, and about as wide and long as a AA battery.
The highly conductive nature of the polymer, coupled with its dense storage of the redox-active compounds, enables it to deliver greater pulses of power than a standard alkaline battery, Palmore said. The device can also store energy longer than capacitors, which are typically used to deliver such bursts of energy.

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The polymer-based battery “just adds to the repertoire of choices you have” of battery systems, Palmore said. “[Now], there’s more candy in the candy store.”

The professor was reluctant to speculate on potential uses for the new battery, but she did say that NASA and the U.S. military have studied polymers as a means of powering devices used in space or on the battlefield. “They’re always looking to improve power delivery,” she said.

The new battery’s commercial viability has not been determined.

“My expectation is, we would look for someone to collaborate with us and provide funding for further research, and then that company would have the opportunity to license the technology,” said David Kiszkiff, director of commercial development at Brown. The National Science Foundation has provided most of the funding for the initial studies.

Worldwide, the battery market is growing. Global battery sales were $52.6 billion in 2005, up 6.6 percent since 2000, with $12.1 billion of last year’s sales coming from North America, according to a recent report by The Freedonia Group Inc., a market research firm in Cleveland.

Still, there are hurdles that must be cleared by anyone hoping to break into that lucrative market.

U.S. startups aiming to launch a new battery face intense pressure to lower the cost of each unit, because many cheap alternatives are mass-produced in Asia, according to Steven Eaves, vice president of technology for Modular Energy Devices Inc. in Warwick.

For nearly five years, Eaves has been working to develop a battery system that combines multiple lithium-ion batteries into a single pack. His packs use the smaller lithium-ion units found in laptops – which are mass-produced to meet demand for the portable computers – to keep them cheaper than other large lithium-ion units, manufactured in smaller numbers.
Modular was fortunate to gain a corporate partner in Reading, Pa.-based battery maker EnerSys Inc., which bought a majority share of the Warwick startup in February. EnerSys has operations in Asia where it can make the batteries, after trials are completed.

Brown’s Palmore said her technology needs fine tuning before it is ready for commercial sales.

The polymer battery now begins to lose some power after it is recharged about 3,000 times, she said; her goal is to get that number up to 10,000. How long that will take is anyone’s guess.

“That is something that depends on how clever we are,” the professor said.