The team spent numerous hours formulating, mixing and testing paints for each of the five layered components - two current collectors, a cathode, an anode and a polymer separator in the middle. The materials were subsequently airbrushed 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. One was topped with a solar cell that converted power from a white laboratory light. When fully charged by both the solar panel and house current, the batteries alone powered a set of light-emitting diodes that spelled out 'RICE' for six hours, while the batteries provided a steady 2.4 volts.

The researchers confirmed the hand-painted batteries were quite consistent in their capacities, within plus or minus 10 percent of the target. They were also put through 60 charge-discharge cycles with only a very small drop in capacity.