Batteries have long been one of the biggest problems for device manufactures. They need a lot of power, lasting power, and this generally meant the battery needed more ingredients to make that happen. This lead to the bigger battery and in turn the device had to be bigger.
Older devices were already clunky like Walkman and the like, but today's electronics are trying to get smaller and smaller with more power.
A team at a research lab called RICE have been working tirelessly to generate a new type of battery that infuses the "layers" of ingredients into several types of paints so it can be spray painted on. It uses some nano tube technologies and the types of paints had to be in specific chemical formulations to work with the various layers/chemicals.
They've finally done it by creating a set of paints that can be spray painted, dried, then the next layer applied until the complete battery is finished.
The beauty of this concept is it can be painted onto anything from glass to wood to paint and more. The power generated has shown to be pretty stable even through several charge/discharges.
Batteries work through a set of reactions that happen naturally with certain types of metals/chemicals that generate and hold power. You can actually make a battery from a grapefruit or any acidic fruit and some Gatorade (but that's another article coming) which is a great way to educate your children about the "power" contained in fruit and electrolytes!
Below is a video from the research group themselves explaining in more detail how their painted on battery works and showing you it working in real time as they lit up the word "RICE" in lights similar to those found in the new LED flashlights. They painted the battery onto bathroom tiles then networked them in serial to up the power rating.
One area they are working on using this is in solar cells, a perfect marriage of technologies that would allow storage of power without taking up space (the power cells/painted battery would be housed behind the device).