Researchers have created five sprayable paints that form a lithium-ion battery when layered together, potentially letting you store energy on walls, tiles or even your favorite mug.

Regular batteries contain a positive and negative electrode, both paired with a metal current collector, and a polymer separator sandwiched in the middle. These five layers are normally manufactured in sheets and rolled up into a cylinder, making it hard to create extremely thin batteries.

Now, Neelam Singh and colleagues at Rice University in Houston have used a combination of existing metallic paints and custom materials to create sprayable versions of each layer, allowing them to make batteries just a fraction of a millimeter thick by airbrushing the layers onto a surface one at a time.

The team applied their batteries to a variety of ordinary building materials and even a ceramic mug to test their potential.

Nine bathroom tile batteries charged by a solar cell were able to power 40 light-emitting diodes arranged to spell out “RICE” for six hours. They don’t yet match regular batteries — a paintable battery would have to be about 1.5 feet square to match a standard mobile phone battery — but that is set to improve. “Their capacity, efficiency and performance could be vastly improved if made on an industrial scale,” explains Singh.

Pairing the batteries with recently developed paintable solar cells might give your walls an electrifying makeover, but Singh says the paints are not quite ready for home use, since they must be applied in a moisture- and oxygen-free environment onto surfaces heated to 248 degrees.

Jacob Aron, New Scientist