The engineers managed to create a battery that can stretch in all directions. This was achieved by using graphene electrodes, shaped like a honeycomb. This design has a high capacity and reliable after many sprains. Article published in the journal ACS Nano.
Flexible and stretchable batteries of interest to engineers because they are easy to integrate into clothing or worn on the body to power sensors or electronic clothing. In recent years, bendable batteries, but make them stretch much harder. In existing prototypes, the material of the electrodes are trying to put on the rubber frame, but are either losing voltage and capacity under strain, or have a small energy density.
Sol Ki Kang (Seulki Kang) and his colleagues at Korean Institute of science and technology were able to make reliable and capacious lithium battery, which stretch themselves to the electrodes. They are made of a graphene composite: an anode with lithium titanate and the cathode with lithium iron phosphate. Initially, the mixture of graphene oxide, carbon nanotubes and lithium compounds is mixed in water. Then, the slurry is poured into a silicone mold of about ten centimeters and freeze so that the ice crystals formed a mesh-like structure resembling the honeycomb of bees. Then the ice is evaporated by heating in a furnace to restore the graphene oxide.
The resulting mesh is still impossible to stretch, so as graphene and nanotubes on the contrary solid. Therefore, if you build it compress on the edges to the center, make a gel electrolyte and is enclosed in a rubber frame, which is responsible for shape recovery. Since the electrode is already compressed, under tension, it is only rectified after the frame.