In modern technology, capacitors, as a fundamental electronic component, play an indispensable role in fields such as power, electronics, and information technology. Among them, double-layer capacitors, as a type of supercapacitor, have attracted widespread attention due to their unique performance and broad application areas.

I. Principle of Double-Layer Capacitors

Double-layer capacitors are based on the interface double-layer theory proposed by German physicist Helmholtz. When a metal electrode is inserted into an electrolyte solution, excess charges of opposite signs will appear on both sides of the electrode surface and the liquid surface, thereby creating a potential difference. If two electrodes are simultaneously inserted into the electrolyte and a voltage lower than the electrolyte solution decomposition voltage is applied between them, positive and negative ions will quickly move to the two poles, forming a dense double layer. This double-layer structure is similar to a parallel plate capacitor, but due to the extremely small distance between the charge layers, it has a larger capacitance than ordinary capacitors.

The charging and discharging process of double-layer capacitors does not involve changes in material, thus they possess characteristics such as short charging time, long service life, good temperature characteristics, energy saving, and environmental friendliness. However, due to the extremely small distance between the double layers, their voltage withstand capability is relatively weak, so they are usually used for energy storage in low-voltage DC or low-frequency applications.

II. Applications of Double-Layer Capacitors

The application fields of double-layer capacitors are very extensive. They can be used as power balance power sources for lifting devices, providing large currents; used as vehicle starting power sources, with higher starting efficiency and reliability than traditional batteries, and can partially or completely replace them; in the military field, they can be used to ensure smooth starting of vehicles in cold conditions or as pulse energy sources for laser weapons. In addition, double-layer capacitors can also be used for energy storage in other electromechanical equipment.

III. Manufacturing Process of Capacitors

The manufacturing process of supercapacitors includes batching, mixing, electrode preparation, cutting, assembly, filling, activation, testing, and packaging, among other steps. Structurally, they are similar to electrolytic capacitors, but the main difference lies in the electrode materials. The electrodes of supercapacitors usually use activated carbon materials because of their large surface area and small electrode spacing, which allows for a large capacitance value. The choice of electrolyte solution is also crucial as it affects the performance and service life of the capacitor.

In summary, double-layer capacitors, with their unique energy storage mechanism and superior performance, have been widely applied in multiple fields. With the continuous development of technology, double-layer capacitors will demonstrate their enormous potential and value in more areas.