Your standard AA battery comes in all shapes and sizes from the nail-sized tabs to the chunky cylinders that powered boom boxes right through the 90s. Of course nowadays you may not seem them as much as you use too; your iPod doesn’t really need them but that doesn’t mean they are obsolete or anything but certainly changing. And how.
Researchers from Rice University in Texas have just invented a one of a kind battery that does not exists as a cylinder or a nail-sized tab but actually is, for want of a better description, a battery sheet that can be spray painted.
As fantastical as it may sound, these new ‘spray-paintable’ batteries, detailed in the journal, Scientific Reports, can be applied to nearly any surface, be it ceramic, steel, glass or cement and once applied only measure at 0.5mm thick.
The ‘spray paint’ batteries themselves consist of 5 separate layers, each having its own chemical makeup. Normal batteries always have positive and negative terminals, that is the anode and the cathode, but unlike the usual form of batteries with anode and cathode on either end, the ‘spray paint’ batteries basically opens up the “Swiss roll” bundle that is inside most batteries, and flattens them out, having layers or sheets of lithium-ion. In addition to these sheets, the researchers also incorporated carbon nanotubes for their electrical properties. Of course the makeup of regular batteries is pretty fixed but the Ruce University researchers wanted to create flexible batteries, the need to add this flexibility was needed and this was done through the use of a chemical called poly-methylmethacrylate which allowed the battery to adhere to even curved surfaces.
The result was the creation of a battery that could be slapped onto any surface, the five layers being the cathode being painted on first, with a polymer separator in the middle followed by an anode layer with two layers of current collectors, much like any standard battery. Lead author of the study, Neelam Singh said, “Spray painting is already an industrial process, so it would be very easy to incorporate this into industry. We really do consider this a paradigm changer.”
Speaking about the battery, Pulickel Ajayan, professor in mechanical engineering, materials science, and chemistry said, “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. There has been a lot of interest in recent times in creating power sources with an improved form factor, and this is a big step forward in that direction."