|Prototype polymer battery. Source: John Abromowski/Brown University|
Brown University engineers Hyun-Kon Song and Tayhas Palmore have developed a prototype polymer-based battery that combines the power of a capacitor with the storage capacity of a battery. A paper published in Advanced Materials describes their work.
The hybrid storage device is based on polypyrrole, a conductive polymer. Discovery and development of polypyrrole and other conductive polymers netted Alan MacDiarmid, Hideki Shirakawa and Alan Heeger the 2000 Nobel Prize in Chemistry.
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. They repeated the process, this time using another kind of conduction-altering chemical. The result was thus two strips with different polymer tips. The plastic strips were then stuck together, separated by a papery membrane to prevent a short circuit.
The resulting device can be rapidly charged then discharged to deliver power. During performance testing, the new battery demonstrated twice the storage capacity of an electric double-layer capacitor and delivered more than 100 times the power of a standard alkaline battery.
The prototype battery is small, light and thin. There are some initial problems with performance, such as decreased storage capacity after repeated recharging, but the Brown team expects strong interest in developing the concept further.
“Redox-Active Polypyrrole: Toward Polymer-Based Batteries”; H.-K. Song, G. T. R. Palmore; Advanced Materials Volume 18, Issue 13, Date: July, 2006, Pages: 1764-1768
Conductive Polymers—Information (advanced) on the Nobel Prize 2000, The Royal Swedish Academy of Sciences