Electrolytic capacitor is a kind of capacitor, the metal foil is the positive electrode (aluminum or tantalum), the oxide film (aluminum oxide or tantalum pentoxide) close to the positive electrode is the dielectric, and the cathode is made of conductive material and electrolyte (the electrolyte can be liquid or tantalum pentoxide). Solid) and other materials together, because the electrolyte is the main part of the cathode, so the electrolytic capacitor is named.