Perhaps someday you'll need to go to the store because you ran out of cathode paint. A team of researchers has just announced a new paint-on battery design. The technique could change the way batteries are produced and eliminate restrictions on the surfaces used for energy storage.

The paint-on battery, like all lithium ion batteries, 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.

Neelam Singh, a member of the team of materials scientists and chemists from Rice University in Houston and Catholic University of Louvain in Belgium and lead author of the paper, says, "It was really exciting to find out. Can we really paint a battery on various surfaces and convert any object into a storage device?"

Singh says her team's work is filling a need in the socially critical field of energy storage for new battery designs. "We find that the focus of research is now shifting towards integration of batteries," she says. That is, people are trying to design batteries that can be built into a variety of different objects. Several teams are working to make thin and flexible batteries as well as batteries that can be incorporated into textiles. Solar energy is one of the applications that researchers are particularly interested in. Solar panels can require large surface areas, and the Rice team's design is an efficient way to collect and store energy in this realm.

To test their design, they applied the battery paints onto ceramic bathroom tiles, glass, a flexible transparency film, stainless steel and the side of a beer stein. In each case, the battery worked. In one experiment, they hooked a solar cell to one of the batteries and powered an LED display.

Singh said the biggest challenge was to make a battery that was both stable and powerful: "It was not very easy to get all the layers on top of each other without interfering with their capacity or compromising the performance of the battery." There were safety concerns as well. Many lithium ion batteries use aluminum as a positive current collector, but aluminum microparticles can be lung irritants, so using them in aerosol paint would be hazardous. Instead, the researchers relied on carbon nanotubes.

Lithium cobalt oxide was used as the cathode, commercially available gel electrolytes as the separator, lithium titanium oxide as the anode, and copper as the negative current collector. The approach is detailed in the June 28 issue of Scientific Reports. (Scientific American is part of Nature Publishing Group.)

Singh thinks that the Rice team's battery is a game-changer because it is energy efficient for its volume and can be applied to objects of many different compositions and shapes.

Vilas Pol, a materials scientist at Argonne National Laboratory who was not affiliated with the study, agrees that the new design is exciting, describing it as "an exceptional and notable concept in the arena of battery design and integration."

But 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.

Singh says the team currently is working 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. Then, she envisions "paintable solar cells on top of paintable solar batteries." Houses could become solar-energy capture-and-storage devices.

7 Comments

1. 1. priddseren 01:46 PM 6/28/12

   Now this is the most promising thing I have seen in terms of energy production and storage if they can pull off the solar paint to put on top of the battery.
   
   As an owner of solar panels, I can say they do the job but only barely so. A paint would have been better simply from the fact I could use the entire roof space and even some east and west facing walls that get at least 4 hours of direct sunlight everyday and would increase the square footage usable but nearly 1000 sq feet. Lets hope these two paints work out.

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2. 2. krohleder 02:21 PM 6/28/12

   Very promising! I still think Donald Sadoway's liquid metal battery solution is the future of energy storage, since he already has working models, and it is so cheap; however the more breakthroughs the better chance we have in solving our energy crisis.

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3. 3. jerryd 02:48 PM 6/28/12

   
   They already make lithium batts this way, just under controlled conditions and not in air.
   
   I want to see them spray lithium in air as would be quite exciting ;^P

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4. 4. singing flea 04:25 PM 6/28/12

   "But 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."
   
   ZZZTTT! Whatever you do, don't scratch the paint.

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5. 5. oldfartfox 09:55 PM 6/28/12

   When I was a kid, we were impressed with a lemon and a couple of strips of copper powering up a flashlight bulb.
   
   I guess the emphasis in my nme should be on the OLD part.
   
   Impressive though, if the bugs can be worked out. (See singing flea.)
   

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6. 6. stijak 12:49 PM 6/30/12

   I really don't see why some people are so impressed. It is not like they can spray on a rock and turn rock into big battery. Only sprayed layers remain battery and volumetric power density remains the same. Price won't be much lower because lithium is still needed and they have to use some special materials so the battery can be sprayed.
   
   Sprayed on solar collector would be the news.

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7. 7. DrRCChhipa 01:23 PM 7/1/12

   Its very useful.

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