Electrochemical cell

A demonstration electrochemical cell setup resembling the Daniell cell. The two half-cells are linked by a salt bridge carrying ions between them. Electrons flow in the external circuit.

An electrochemical cell is a device that either generates electrical energy from chemical reactions in a so-called galvanic or voltaic cell, or induces chemical reactions (electrolysis) by applying external electrical energy in an electrolytic cell.

Both galvanic and electrolytic cells can be thought of as having two half-cells: consisting of separate oxidation and reduction reactions.

When one or more electrochemical cells are connected in parallel or series they make a battery. A primary battery consists of single-use galvanic cells. Rechargeable batteries are built from secondary cells that use reversible reactions and can operate as galvanic cells (while providing energy) or electrolytic cells (while charging).