What comes to mind when you picture a battery? The familiar Duracell Coppertop AA battery? A clunky automotive battery? The small rectangular battery in your cell phone? Researchers at Rice University are reinventing the concept of batteries and battery packaging by creating a lithium-ion battery with spray paint. That’s right, your local neighborhood hoodlum taggers can now be more energy forward than you sitting at home watching Cops.
A team of researchers from Rice University have demonstrated in a paper in Nature Scientific Reports that special “spray paints” can be used sequentially to build up the layers needed to form a lithium-ion battery. A spray-on battery could be used on a variety of materials, both rigid and flexible. They point out that the technology could be coupled to energy conversion devices such as solar cells.
Simply put, a lithium-ion battery is created by tightly layering cathodes and anodes like in the image shown below. The researchers at Rice University replicate this cylindrical design in a customizable form using the spray coatings that they developed. They applied the battery painting process to a variety of materials including stainless steel, glass, ceramic tile, and flexible polymer sheets. An SEM image of a cross section of the battery is shown below. Each of the spray painted batteries performed as a typical battery. They even applied the spray paint to a coffee mug to spell out the name of their Alma mater while also storing energy. They added that more complicated surface geometries could be possible using different spray nozzle designs that are tailored to the different viscous properties of the paints.
The are a few drawbacks to a spray painted lithium-ion battery. For one, the materials are highly toxic, corrosive, and flammable, hence why they are always tightly packaged and hidden away in their conventional form. Secondly, the batteries are highly sensitive to oxygen and moisture. This sensitivity currently restricts their widespread use because they still have to be packaged like their conventional brethren, reducing their novel promise. A spray painted battery is shown below on a glazed ceramic tile alongside its final packaged form. One of the researchers’ next steps is to develop a sealing layer to protect the batteries from these elements. Because who wants to paint their electric vehicle with a new battery but then have the painter tell them that they always have to keep the car cover on.
Typical lithium-ion battery construction.
Conventional and spray painted lithium-ion batteries.
SEM image of spray painted lithium-ion battery cross section.
Glazed ceramic tile with spray painted battery prior to packaging (left) and post-packaging (right)
Energy, Technology, & Policy 
Thanks for your interesting post! This is another reminder that we can really benefit from thinking outside the box in materials innovation. It seems their may be huge potential to combine this technology with solar cells as you mentioned. In fact, Prof. Brian Korgel in the UT Department of Chemical Engineering has been working on ink-based solar cells that could be painted on rooftops or other surfaces [1]. Maybe adding such an ink-based solar cell to the the outer part of an electric vehicle could play a dual-role as a “sealing layer” for the paint-based battery and still harnessing solar energy to power the car.
There would certainly be some risks, as you mentioned, associated with the Li-based batteries; however, this presents a great opportunity to develop “battery components (electrolyte and electrode) that are less sensitive to moisture and oxygen” [2]. Possibly allowing non-specialists, like local body shops, to apply battery coatings. Sounds like a great idea!
[1] Plan to turn rooftops, walls and windows into cheap solar cells
[2] Paintable Battery
References:
1) http://www.gizmag.com/cheaper-solar-cells/12606/
2) http://www.nature.com/srep/2012/120628/srep00481/pdf/srep00481.pdf
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