1. Electrochemical capacitors

1.1 Technologies and main families

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...