This is interesting: in the future, the batteries for our tablets, cellphones, netbooks, and cameras (assuming we’ll still have them in those forms) will be built directly into the casing of the devices themselves.
Lithium-ion batteries are made by tightly rolling up the various battery components in layers before encasing them in rectangular or cylindrical packaging. The engineers, from Rice University in Texas, devised their own unique version of a multilayer battery by painting these individual battery components (two current collectors, a cathode, an anode and a polymer separator) on to select surfaces in layers. These layers included paints made from lithium cobalt oxide (a positive electrode), lithium titanium oxide (a negative electrode) and conductive single-walled nanotubes (a current collector). The special polymer paint blend helped achieve superior conductivity by forming the micro-porous layer required in a lithium battery.
via Spray-on Rechargeable Batteries Could Store Energy Anywhere | Wired Science | Wired.com.