Electrochemical cell

An electrochemical cell converts chemical energy into electrical energy or uses electrical energy to drive chemical reactions. It couples electron transfer through an external circuit with ion movement through an electrolyte.

Anode: The electrode where oxidation occurs in an electrochemical cell. Oxidation at the anode releases electrons into the external circuit.
Oxidation–reduction reaction: A chemical reaction in which electrons are transferred between species, changing their oxidation states. Every electrochemical cell couples oxidation to reduction at separate or shared electrodes.
Galvanic cell: An electrochemical cell that produces electrical energy from a spontaneous chemical reaction. It is the power-producing mode of electrochemical cells.
Concentration cell: A galvanic cell whose voltage arises from a difference in concentration between corresponding chemical species. It generates voltage from concentration imbalance rather than different electrode materials.
Cathode: The electrode where reduction occurs in an electrochemical cell. Reduction at the cathode consumes electrons arriving through the external circuit.
Chemical potential: The change in a system's Gibbs energy when an infinitesimal amount of a substance is added. Chemical potential differences help determine which cell reactions can proceed spontaneously.
Electrolytic cell: An electrochemical cell that uses electrical energy to drive a nonspontaneous chemical reaction. It is the externally powered mode, used in processes such as electrolysis.
Primary cell: An electrochemical cell designed for one-time use because its reaction is not practically reversible. It contrasts with rechargeable cells whose reactions can be reversed by applied current.
Electrolyte: A medium containing mobile ions that conduct electricity through ionic motion. Its ions carry charge inside the cell and maintain electroneutrality.
Gibbs free energy: A thermodynamic potential that predicts the maximum non-expansion work available at constant temperature and pressure. Its change sets the maximum electrical work obtainable from a reversible cell.

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