The electrode is an essential part of the primary battery. A device that generates a current using a spontaneous redox reaction is called a primary battery, and a primary battery must consist of two basic components: two electrodes and an electrolyte solution. An electrode that gives an electron oxidation reaction, such as a Zn electrode in a Daniel battery (shown in the upper part of the right figure), is called a negative electrode because of its low potential; and a pole that accepts electron reduction, such as The Cu electrode is called a positive electrode because of its high potential. The electrodes can be classified into three types depending on the state of the constituent electrode materials. The first type of electrodes are metal electrodes and gas electrodes, such as zinc electrodes and copper electrodes in Daniel batteries, and standard hydrogen electrodes; the second type of electrodes are metal-metal insoluble salt electrodes and metal-metal insoluble oxide electrodes, such as Ag-AgCl electrode. The third type of electrode is a redox electrode (any electrode is a redox electrode, and the redox electrode here refers to a substance which participates in the electrode reaction in the same solution), such as an electrode composed of Fe3+, Fe2+ solution. Wall Mounted Transom,Upper Overpanel,Corner Overpanel Belyn Hardware Factory , http://www.xy-hardware.com