An electrochemical cell is the association of two metallic materials with different dissolution potentials, and an aqueous medium.
When the two materials are connected by a conducting link, an electrical current of intensity I flows from the material with the higher potential to the one with the lower potential.
This mechanism occurs in galvanic corrosion. Moreover, it causes considerable damage. Care should therefore be taken when combining two different metals.
An electrochemical cell is illustrated in the diagram below.