The electrode with a negative potential is called a sacrificial anode, because with the continuous flow of current, the anode material is continuously consumed. As a sacrificial anode material, the metal or alloy must meet the following conditions: (1) The potential is negative enough to supply sufficient electrons to enable cathodic polarization of the protected metal device.

Cathodic protection of zinc anodes is to protect steel equipment by connecting a metal or alloy that is more likely to lose electrons. For example: steel gate protection, some use this method. It is a more active metal, such as zinc, connected to the steel gate. In this way, when electrochemical corrosion occurs, it is the kind of metal that is more reactive than iron, and the iron is protected. Usually in the stern of the ship and in the hull below the waterline part, a certain amount of zinc block is installed to prevent corrosion of the hull, etc., is the application of this method. At present, in addition to the protection of steel equipment in seawater or river channels, electrochemical protection is also used to prevent corrosion of cables, oil pipelines, underground equipment and chemical equipment.