By Allan Robinson | Updated March 24, 2022
An electrode is a conductor that establishes electrical contact with the nonmetallic components of a circuit—such as electrolytes, semiconductors, or a vacuum. Depending on the intended application, electrodes are often named after their specific role, for example anode, cathode, or reference electrode.
Begin with a simple electrochemical cell: connect a wire to each terminal of a battery, and immerse the free ends in an electrolytic solution. The segments of wire that enter the solution serve as the electrodes.
In an electrolytic cell, the electrode attached to the battery’s negative terminal is the anode, while the one connected to the positive terminal is the cathode.
To increase surface area without enlarging the electrode’s length, wrap the conductive wire around a small cylinder—such as the barrel of a pen. A larger surface area improves charge transfer and overall efficiency.
Prepare the cathode by grinding a blend of manganese dioxide, potassium hydroxide, and graphite into a fine powder, then pressing it into tablets. These tablets form the cathode of an alkaline battery. For the anode, use a gel largely composed of zinc powder. Separate the two electrodes with a paper layer, place them in a metal container, and seal it to create a functional primary cell.
The electrode fabrication process mirrors that of primary cells, but the electrochemical reactions are reversible. In a nickel‑cadmium battery, for example, the cathode contains cadmium and the anode contains nickel. During discharge, cadmium ions migrate to the anode while nickel ions move to the cathode, generating current. When an external current is applied, the ions return to their original electrodes, recharging the cell.
