An electrode is an electrically conductive part in an electrical or electronic component or device that makes a transition from a conductor-bound current to another medium. For example, in electronic components such as diodes, transistors, luminous, electron and cathode ray tubes and also in the electrochemical conversion in batteries and accumulators. Electrodes are used to generate, control and collect electrons.
- In electrochemical conversion, electrodes are part of the electrochemical cell. They are surrounded by or immersed in the electrolyte. Electrodes are made of electrically conductive material and are used to generate or collect electrons. Electrochemical reduction takes place at the cathode, with electrons flowing from the connected circuit into the cathode. The required charge balance at the cathode is provided by cations coming from the electrolyte. The chemical process at the anode of a battery is oxidation. In this process, the anode releases electrons into the connected circuit. The charge balance at the anode is achieved by the inflow of anions from the electrolyte. In rechargeable batteries, both the negative and the positive electrode can become the anode or the cathode, respectively. This depends on whether the battery is being charged or discharged.
- In electron tubes and cathode ray tubes, there are other electrodes besides the cathode and anode to control the flow of electrons. In these tubes, the cathode generates electrons that flow down the tube to the positive anode. Electrons can be generated by heating the cathode, as well as by photoelectronic conversion.
- In transistors, the electrodes are designated emitter and collector, and the control electrode is the base. In field effect transistors( FET), the corresponding electrodes are called source, drain and gate.