Polymer-based battery

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The creation of a polymer-based battery was announced, on November 14 2006, by Brown University engineers. The new battery uses plastic, not metal, to conduct electric current and the hybrid device marries the power of a capacitor with the storage capacity of a battery.

According to associate professor in Brown’s Division of Engineering, Tayhas Palmore, common traditional batteries have disadvantages such as constant recharging and limited power delivery and high costs. Another option to traditional batteries is capacitors. These components, found in electronic devices, can deliver much higher power output, but they don’t have much storage capacity. Polymer based battery prototypes seem to offer the adavntages of both a capacitor with the positive characteristics of a traditional battery minus the disadvantages of the latter.

Tayhas Palmore, associate professor of engineering at Brown University, and Hyun-Kon Song, a former postdoctoral research associate, figured out how to combine the advantages of batteries and capacitors in a plastic hybrid device.

They began to experiment with a new energy-storage system using a substance called polypyrrole, a chemical compound that carries an electrical current. Discovery and development of polypyrrole and other conductive polymers netted three scientists the 2000 Nobel Prize in Chemistry.

In their experiments, Palmore and Song took a thin strip of gold-coated plastic film and covered the tip with polypyrrole and a substance that alters its conductive properties. The process was repeated, this time using another kind of conduction-altering chemical. The result: Two strips with different polymer tips. The plastic strips were then stuck together, separated by a papery membrane to prevent a short circuit.

The result is a hybrid plastic battery. Like a capacitor, the battery can be rapidly charged then discharged to deliver power. Like a battery, it can store and deliver that charge over long periods of time. During performance testing, the new battery performed like a hybrid, too. It had twice the storage capacity of an electric double-layer capacitor. And it delivered more than 100 times the power of a standard alkaline battery.

In width and height, the prototype is smaller than an iPod Nano. And it’s thinner, about as slim as an overhead transparency.

Performance problems – such as decreased storage capacity after repeated recharging – must be overcome before the device is marketable. NASA and the U.S. Air Force are also exploring polymer-based batteries.