Last Updated: 4/30/19 by Neil Spinner
In an electrochemical system,
the cathode is the electrode
at which reduction
The terms cathode and anode
are most frequently used in two-electrode systems,
such as fuel cells
They are less commonly used in typical three-electrode systems.
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
and reduction (depending on whether the battery is being charged or discharged), the cathode is defined as the electrode experiencing reduction during discharge.