Elektród

An elektród is a conductor through which electric current enters or leaves a non-metallic medium, most often an electrolyte in an electrochemical cell. The electrode serves as the interface where electrons in the external circuit meet chemical species in contact with the medium, enabling redox reactions. At this interface, oxidation or reduction occurs, and the electrode can directly influence reaction rates and selectivity.

Two fundamental roles are the anode, where oxidation occurs, and the cathode, where reduction occurs. In galvanic (spontaneous) cells the anode is usually negative and the cathode positive; in electrolytic cells used for electrolysis the polarities are reversed. The cell’s overall potential depends on the properties of the electrode interfaces and any overpotentials.

Electrodes are made from materials chosen for conductivity, stability, and compatibility with the medium. Inert electrodes such as platinum, carbon, or graphite are used when the electrode must not participate chemically. Active electrodes participate in reactions and may be consumed during operation. Shapes range from rods and plates to porous structures, often with protective coatings.

Common applications include energy storage (batteries and supercapacitors), electroplating and refining, and industrial electrolysis (chlor-alkali processes). Electrodes also feature in sensors, corrosion studies, welding (arc welding electrodes), and various electrochemical analyses.

Related terms include electrode potential and reference electrode, which provide a stable comparison point for measuring electrode behavior.