Cathode
Last Updated: 4/30/19 by Neil Spinner
1Cathode
In an electrochemical system,
Electrochemical System
the cathode is the electrode
Electrode
at which reduction
Reduction
is occurring.
The terms cathode and anode
Anode
are most frequently used in two-electrode systems,
Two-Electrode System
such as fuel cells
Fuel Cell
and batteries.
Battery
They are less commonly used in typical three-electrode systems.
Three-Electrode System
In the context of fuel cells and batteries, the cathode is also sometimes called the positive electrode, and may be denoted with a plus sign. In the context of secondary (rechargeable) batteries where both the cathode and anode may alternatively undergo both oxidation
Oxidation
and reduction (depending on whether the battery is being charged or discharged), the cathode is defined as the electrode experiencing reduction during discharge.