You’ve heard of spray on solar cells, scientists at Rice University have developed paint on batteries:

BBC — The new work, from Rice University in Texas, US, opens up completely new avenues for putting batteries on nearly any surface in a simple and robust way.

Pulickel Ajayan and his colleagues chemically optimised the recipe for each of their five layers, using blends of chemicals common in lithium-ion batteries as well as novel materials including carbon nanotubes – tiny “straws” of carbon with incredible electronic properties.

But for the process to result in a working battery, all five layers must stick together and work in synchrony, and the tricky step was finding a separator material that kept the whole stack in one piece.

When the team hit on using a chemical called poly-methylmethacrylate, they had a structure that would stick even to curved surfaces.