Spray-on battery developed

Traditional lithium-ion batteries power most portable electronics and are compact but limited to rectangular or cylindrical blocks.

Researchers at Rice University in Houston, Texas, have come up with a technique to break down each element of the traditional battery and incorporate it into a liquid that can be spray-painted in layers on virtually any surface.

"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," said Pulickel Ajayan, who leads the team on the project.

The rechargeable battery is made from spray-painted layers, with each representing the components of a traditional battery: two current collectors, a cathode, an anode and a polymer separator in the middle.

The paint layers were airbrushed onto ceramics, glass and stainless steel, and on diverse shapes such as the curved surface of a ceramic mug, to test how well they bond.

One limitation of the technology is in the use of difficult-to-handle liquid electrolytes and the need for a dry and oxygen-free environment when making the new device.

The researchers are looking for components that would allow construction in the open air for a more efficient production process and greater commercial viability.

Neelam Singh, who worked on the project, believes the technology could be integrated with solar cells to give any surface a stand-alone energy capture and storage capability.

The researchers tested the device using nine bathroom tiles coated with the paint and connected to each other. When they were charged, the batteries powered a set of light-emitting diodes for six hours, providing a steady 2.4 volts.

The results of the study were published this week in the journal Nature Scientific Reports.