cathode
n. countablen. the part of a battery or electrical device where electricity leaves. It is the negative side in a battery that is providing power.
n. the electrode through which conventional current leaves a polarized electrical device. In a discharging battery, it acts as the positive terminal, whereas in an electrolytic cell, it is the negative terminal.
The battery has both an anode and a cathode.
In a standard lithium-ion battery, lithium ions move from the anode to the cathode during discharge to power the device.
The efficiency of the electrochemical reaction depends heavily on the surface area and material composition of the cathode, which facilitates the reduction process within the cell.
From Ancient Greek κατα- (kata-, “down”) and ὁδός (hodós, “journey, way”), equivalent to Ancient Greek κάθοδος (káthodos, “way down, descent”). Coined by English polymath William Whewell in 1834 for Michael Faraday, who introduced it later that year. By surface analysis, cath- (alternative form of cata-) + -ode.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Frequently paired with 'anode' as its functional opposite.
Last updated May 11, 2026