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The principle of supercapacitors


Electric double layer capacitor is a new type of capacitor based on the interface double layer theory proposed by physicist Helmholtz. It is well known that excess charges with opposite symbols appear on the surface of metal electrodes inserted into electrolyte solutions and on both sides of the liquid surface, resulting in potential differences between phases. "If two electrodes are inserted into the electrolyte at the same time and a voltage smaller than the decomposition voltage of the electrolyte solution is applied between them, then the positive and negative ions in the electrolyte will rapidly move towards the two electrodes under the action of an electric field, and a compact charge layer, called a double layer, is formed on the surfaces of the two electrodes, respectively. The double layer formed by the double layer is similar to the polarization charge generated by the dielectric in traditional capacitors under the action of an electric field,", This results in a capacitive effect. A compact double layer is similar to a flat plate capacitor. However, due to the fact that the close charge layer spacing is much smaller than the distance between the charge layers of an ordinary capacitor, it has a greater capacity than an ordinary capacitor.

Compared to aluminum electrolytic capacitors, double layer capacitors have a larger internal resistance, so they can be directly charged without load resistance. If overvoltage charging occurs, the double layer capacitors will open without damaging the device. This feature is different from the overvoltage breakdown of aluminum electrolytic capacitors. At the same time, compared to rechargeable batteries, double layer capacitors can perform unlimited current charging, and the charging times can reach more than 10 ^ 6 times. Therefore, double layer capacitors not only have the characteristics of capacitors, but also have the characteristics of batteries. They are a new type of special component between batteries and capacitors

The basic principle is that when the electrode is charged, the surface charge of the electrode in the ideal polarization electrode state will attract foreign ions in the surrounding electrolyte solution, causing these ions to attach to the electrode surface to form a double charge layer, forming a double electric layer capacitance. Due to the very small distance between the two charge layers (typically below 0.5 nm), and the use of a special electrode structure, the electrode surface area increases by ten thousand times, resulting in a large capacitance

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The principle of supercapacitors

Electric double layer capacitor is a new type of capacitor based on the interface double layer theory proposed by physicist Helmholtz. It is well known that excess charges with opposite symbols appear on the surface of metal electrodes inserted into electrolyte solutions and on both sides of the liquid surface, resulting in potential differences between phases.


Test methods for fixed capacitors

1. Detection of small capacitors below 10pF: Because the capacity of fixed capacitors below 10pF is too small, using a multimeter to measure can only qualitatively check whether there is leakage, internal short circuit, or breakdown. When measuring, a multimeter R can be selected × At 10k gear, use two probes to arbitrarily connect the two pins of the capacitor, and the resistance value should be always high. If the measured resistance value (pointer swinging to the right) is zero, it indicates that the capacitor is damaged due to leakage or internal breakdown.


What are the classifications of capacitors?

According to analysis and statistics, capacitors are mainly divided into the following 10 categories: 1. According to structure, they are divided into three categories: fixed capacitors, variable capacitors, and fine tuning capacitors. 2. Classification by dielectric: organic dielectric capacitor, inorganic dielectric capacitor, electrolytic capacitor, electrothermal capacitor, air dielectric capacitor, etc.


Function of capacitor

In a DC circuit, a capacitor is equivalent to an open circuit. A capacitor is a device that can store electric charges and is also one of the commonly used electronic components.