Electrodes are a special class of electrical conductors. Because they are able to contact a non-metallic part of a circuit, and so complete it. They come in various shapes and sizes, where we use them to connect to electrolytes and semiconductors. They can also send electrons in a vacuum, or through the air. The eclectic genius William Whewell born 1794 made up the word ‘electrode’ from the Greek electron (amber), and hodos (a way) So the amber way it is.
Electrodes as Electrical Conductors in Batteries
William Whewell also coined the terms ‘anode’ and ‘cathode’ at the request of Michael Faraday, who discovered magnetism in 1812. Presumably, he wanted to introduce some order.
Who better to turn to than a polymath, philosopher, priest, and historian of science. In this way, electrical conductors from whence electrons leave batteries to power devices became negative anodes. And their companions, where electrons enter, became positive cathodes.
Furthermore, anode and cathode pairs can exchange their roles (and names) when the current flows the other way in secondary batteries.
Current Flows in Primary and Secondary Cells
This role reversal is impossible in the case of non-rechargeable primary batteries. Because they do not have the capacity and it can be dangerous to try.
Secondary rechargeable cells such as our deep cycle, lead-acid batteries do have that capability. Every time we charge them, and start discharging them, they exchange electrochemical personalities.
A bipolar electrode functions as the anode of one, and the cathode of another cell. Multi-layered batteries can be nano-thin and at the cutting edge of battery science and technology.
Other Uses for These Amazing Electrical Conductors
We encounter cathodes and anodes in electric welding. The process may consume them, or they may be recyclable as in gas tungsten arc welding. Electrons enter through the negative cathode, and depart via the positive anode in the case of diodes and electrolytic capacitors. While in medicine they play a vital role as electrical conductors in defibrillators, heart beat recordings, and electrical brain stimulation.
Related
What Are Electrodes & What Do They Do?
How Electrons Travel In and Out of Electrodes
Preview Image: Air Welding
