The silver-colored panels are ceramic tiles coated with the spray on batteries and then covered by sealant. In a test, the blue solar panel took in light from the laboratory and transferred through the batteries, powering LED lights that spell out RICE for 6 hours. (Photo: Jeff Fitlow/Rice University)

Batteries have traditionally come in rectangular or cylindrical shapes, but that's about to change. Scientists at Rice University have developed a spray-on battery paint that can be affixed to just about any surface.

"We can convert almost any object to a battery," Neelam Singh, a materials scientist at Rice University in Houston, told Innovation News Daily. "You could turn your home into a battery," she said.

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Singh and her team fine-tuned the formula for five layered components that make up the spray on battery. Like conventional lithium ion batteries, the spray paint consists of layers: a positive current collector, a cathode that attracts positively charged ions, an ion-conducting separator, an anode to attract negative ions, and a negative current collector.

They then tested the material on ceramic bathroom tiles, flexible polymers, glass, stainless steel and even a beer stein, and found that the battery conducts electricity even on curved or flexible surfaces. The material the battery was painted onto had no effect on the performance of the device, which suggests this technology could find many household or industrial uses.

"There has been a 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." said Rice materials scientist Pulickel Ajayan. "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."

In one experiment, the team hooked a solar cell to tiles painted with the battery substance and powered an LED display. The airbrushed batteries kept consistent power, and even after 60 charge/discharge cycles, it had only a small drop in capacity.

The researchers call each layer of the battery an "optimized stew." The first, the positive current collector, combines carbon nanotubes with carbon black particles. The cathode contains lithium cobalt oxide, carbon and ultrafine graphite powder. The polymer separator is a mix of commercially available gel electrolytes. The anode is lithium titanium oxide combined with ultrafine graphite powder, and the negative current collector is a commercially available copper paint that conducts electricity.

Though it's an exciting step toward new forms of power sources, for now paint-on batteries are not quite ready to hit the shelves at your local hardware store. For one, the electrolyte separator layer is not yet oxygen stable. It would explode if it came into contact with air, so special conditions are necessary when creating the battery, according to Scientific American.

Singh said she foresees the possibility of integrating paintable batteries with recently reported paintable solar cells to create an energy-harvesting combination that would be hard to beat. As good as the hand-painted batteries are, she said, scaling up with modern methods will improve them by leaps and bounds. "Spray painting is already an industrial process, so it would be very easy to incorporate this into industry," Singh said.

The team also said they envision their batteries as snap-together tiles that can be configured in any number of ways. So, once they can stabilize the separator, you may want to be on the lookout for Lego-style battery tiles at your hardware store.

The scientists have filed for a patent on their findings, which are detailed online in the journal Scientific Reports.