Perhaps someday you'll need to go to the store because you ran out of cathode paint. In June a team of researchers at Rice University and the Catholic University of Louvain in Belgium announced a new paint-on battery design. The advance, described in the online journal Scientific Reports, could change the way batteries are produced and eliminate restrictions on the surfaces used for energy storage.
The paint-on battery consists of five 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. For each layer, the challenge was to find a way to mix the electrically conductive material with various polymers to create a paint that could be sprayed onto surfaces one coat at a time.
To test their design, the researchers applied the battery paints on ceramic bathroom tiles, glass, a flexible transparency film, stainless steel and the side of a beer stein. They attached small circuits to the batteries to harness the electricity. In one experiment, they hooked a solar cell to one of the batteries and used solar power to light an LED display.
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Paint-on batteries are not quite ready to hit the shelves at the 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.
Neelam Singh, a member of the team at Rice, says the researchers are currently trying to make all the materials less reactive to air and moisture and more environmentally friendly. She adds that other groups are working on developing paint-on solar cells. These, Singh envisions, will be followed by “paintable solar cells on top of paintable solar batteries.” Houses could become capture-and-storage devices for solar energy.