button battery cr1620.Research on the principles and applications of supercapacitors?

　　With the advancement of science and technology, people now pay more and more attention to ecological environment protection and the application of green energy. As a new type of energy storage component, supercapacitor has attracted widespread attention and attention. Supercapacitor is a new energy storage device developed in the 1970s and 1980s between batteries and traditional capacitors. Its emergence fills the gap between traditional electrostatic capacitors and chemical power sources.

　　1. Principles and classification of supercapacitors

　　Supercapacitor is a physical secondary power source with super power storage capacity and strong pulsating power. Supercapacitors are mainly divided into three categories according to the energy storage mechanism [1]: ① Double electric layer capacitance generated by charge separation at the interface between carbon electrode and electrolyte; ② Using metal oxides as electrodes, oxidation occurs on the electrode surface and bulk phase A Faradaic capacitor that produces reversible chemical adsorption due to a reduction reaction; ③ A capacitor that uses a conductive polymer as an electrode to cause a redox reaction. Electric double layer supercapacitor is a new type of energy storage device that relies on polarized electrolyte to store electrical energy. The structure is shown in Figure 1:

　　Since the charging and discharging of electric double layer capacitors is purely a physical process, it has a high number of cycles and a fast charging process, so it is more suitable for use in electric vehicles. Electric double layer supercapacitors are two inactive porous plates suspended in an electrolyte, with a voltage applied to both plates. The potential applied to the positive plate attracts negative ions in the electrolyte, and the negative plate attracts positive ions, thereby forming an electric double layer capacitor on the surfaces of the two electrodes. The capacitance of a supercapacitor unit is as high as several farads to tens of thousands of farads [2]. Because this structure adopts a special process, its equivalent resistance is very low, the capacitance is large, and the internal resistance is small, making the supercapacitor have a very high The peak current, so the supercapacitor has a very high specific power. Its power density is 50 to 100 times that of the battery, which can reach about 10×103W/kg. This feature makes the supercapacitor very suitable for applications in short-term high-power situations. .

　　2.Characteristics of supercapacitor

　　There are no chemical reactions or mechanical movements such as high-speed rotation during the use of supercapacitors. There is no pollution to the environment and no noise. Its simple structure and small size make it an ideal energy storage device. Supercapacitor products have the following technical characteristics[3]:

　　(1) Charging speed is fast. It only takes 10 seconds to 10 minutes to fill more than 95% of its rated capacity;

　　(2) Long cycle life. Deep charge and discharge cycles can reach 10,000 to 500,000 times. For example, the cycle life of the HCC250F/2.7V supercapacitor produced by Beijing Hezhong Huineng Company and the series of capacitors produced by Beijing Jixing Technology Company are both more than 500,000 times;

　　(3) High energy conversion efficiency. High current energy cycle efficiency >90%;

　　(4) High power density. It can reach 300W/kg-50000W/kg, which is 5 to 10 times that of batteries;

　　(5) The production, use, storage and dismantling of raw materials are pollution-free, making it an ideal green and environmentally friendly power source; it has a high safety factor and is maintenance-free for long-term use;

　　(6) High charge and discharge efficiency. Because the internal resistance is very small, the charge and discharge losses are also very small, and the charge and discharge efficiency is very high, reaching more than 90%.

　　(7)Wide temperature range. Reach -40～+70℃. The reaction rate of supercapacitor electrode materials is not greatly affected by temperature;

　　(8) Convenient detection and control. The remaining power can be calculated directly through the formula E=CV2/2. The stored energy can be determined by simply detecting the terminal voltage. The calculation of the state of charge (SOC) is simple and accurate, so it is easy to manage and control the energy.

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