Copper foam battery. Illustration showing the structure of a lithium-ion battery made with a copper foam substrate. Using an electroplating process, the foam is coated with copper antimonide which forms the anode. It is then coated with a solid state electrolyte followed by a layer of lithium cobalt oxide cathode slurry. The three separate layers seep into the three-dimensional architecture of the foam, which has greater surface area to store energy. The 3-D structure also shortens how far electrons must travel, which speeds up charging. For a labelled version of this image see C046/6497.