Electrochemical capacitors
Electrolytic capacitors and film capacitors Technologies and evolution

An electrolytic capacitor (or electrochemical capacitor, or both) is made up of the following three elements:

• a metal anode (positive armature) made of aluminum, tantalum or niobium, although the latter technology is rarely used;

• a dielectric layer resulting from oxidation of the anode metal: aluminum oxide, tantalum oxide or niobium oxide;

• the cathode, made up of the conductive electrolyte itself and the metal cathode (negative armature), which merely acts as a link between the electrolyte and the external circuit.

The capacitor thus formed is polarized: the potential of the anode must always be positive in relation to that of the cathode. The dielectric is produced in situ by anodic...