Painting on a power source

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Friday, 29 June 2012 11:25

June 29, 2012

Developing more reliable batteries that can efficiently store and release energy has been seen as a critical step toward the adoption of everything from solar power to electric vehicles, not to mention the endless array of consumer electronics.

But one group of researchers at Rice University has approached the problem from a different angle, looking at how they can change the way batteries are designed, constructed and implemented at a more fundamental level.

Materials Science professor Pulickel Ajayan and graduate student Neelam Singh led a team that sought to design a reliable battery that could be simply painted onto a surface, rather than being constructed whole.

To accomplish this, the researchers created a series of different paints comprising all the ordinary components of a battery along with some materials designed to supplement the structural integrity of each layer and the resulting "battery" as a whole.

In all, there were five different layers including a cobalt oxide, carbon and ultrafine graphite (UFG) cathode and a lithium titanium and UFG anode. The bottom layer, the negative charge collector, was simple copper paint, while the positive current collector on the top was formed out of carbon and carbon nanotubes. Holding the whole structure together between the cathode and anode was a seperator composed of silicon dioxide along with a type of resin and what is often known as acrylic glass, PMMA.

"The hardest part was achieving mechanical stability, and the separator played a critical role," Singh said. "We found that the nanotube and the cathode layers were sticking very well, but if the separator was not mechanically stable, they would peel off the substrate. Adding PMMA gave the right adhesion to the separator."

Singh tested the new technology by applying batteries to a wide range of different materials, from bathroom tiles and glass to a Rice beer stein. The batteries created were able to be charged by a simple solar panel drawing from the room's lights, and stored enough power to light up a "RICE" in LED's for six hours at a time.

"This means traditional packaging for batteries has given way to a much more flexible approach that allows all kinds of new design and integration possibilities for storage devices," explained Ajayan. "There has been lot of interest in recent times in creating power sources with an improved form factor, and this is a big step forward in that direction."

Combined with the recent introduction of paintable solar cells, the researchers hope this new technology could help create an incredibly flexible source of power. The wide use of spray-painting could also make it applicable for industrial purposes.

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