Modern high-energy batteries are often characterized by the use of super-thin metal foils. Examples include copper and etched-surface copper foils shown here in the Schlenk Metallfolien GmbH booth. The foils are only about 24 microns thick, and Schlenk had even thinner versions on display. one needs to use materials which are stable at the respective electrochemical potential. Copper foil coated with graphite commonly serves as anode (or negative electrode) material in lithium-ion cells because the working potential for the anode is in the range of 0.5 to 2.5 V. This is below copper’s oxidation voltage (about 2.7 V or higher) which allows the metal to serve as a base for a stable anode.