Researchers at Rice University have developed a lithium-ion battery that can be painted onto virtually any surface. The rechargeable battery, described in the journal Nature: Scientific Reports, consists of spray-painted layers, each representing the components in a traditional battery.

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.  As such, it directly addresses the need for power sources with an improved form factor.

The Rice team spent painstaking hours formulating, mixing, and testing paints for each of the five layers:  the two current collectors, a cathode, an anode, and a polymer separator that goes in the middle.

An airbrush was used to paint these layers onto ceramic bathroom tiles, flexible polymers, glass, stainless steel, and even a beer stein to see how well they would bond with each substrate.

In the first experiment, nine bathroom tile-based batteries were connected in parallel. When fully charged by both a solar panel and house current, the batteries powered a set of light-emitting diodes that spelled out "RICE" for six hours; during the entire time, the batteries provided a steady 2.4 volts.

They were remarkably consistent in their capacities, within plus or minus 10 percent of the target.  There was also only a very small drop in capacity after they were put through 60 charge-discharge cycles.

The Rice researchers have filed for a patent on the technique, which they will continue to refine.