What is a super capacitor? Analysis of the principle and use of super capacitor

Supercapacitors look like really the same rechargeable batteries. Because supercapacitors can store large amounts of electrical energy for a long time, they behave more like batteries than standard capacitors. In fact, with the development of technology, they will replace rechargeable batteries in a range of products from computers, digital cameras, mobile phones to other handheld devices. What is a super capacitor? Simply put, a super capacitor is a very large polarized electrolytic capacitor. Big here refers to capacity, not physical standards. In fact, for a typical electrolytic capacitor, the larger the capacity and/or voltage, the larger the package. The capacitance of electrolytic capacitors is usually microfarad, ranging from 0.1uf to about 1F, and the nominal voltage value can reach 1kVdc. In general, the higher the rated voltage, the smaller the capacitance, the larger the capacitance, and the larger the package, and the operating voltage may decrease. These rules basically also apply to supercapacitors. The capacity of this supercapacitor exceeds 1F, and the working voltage range is 1.5v to 160V or even higher. As the capacitance and voltage increase, the volume also increases. The early supercapacitors had a capacity of about tens of farads and were large in size, and were mainly used for large power supplies. In consumer electronic products, small supercapacitors with low-voltage operation capabilities are often used as short-term backup power sources. Although supercapacitors and electrolytic capacitors have great similarities, there are also great differences in electrical functions and physical standards. For example, a typical 10uF, 25Vdc rated voltage electrolytic capacitor standard may be slightly smaller than or even equal to 1F to 10F, 2.7Vdc supercapacitor. With the recent technological advancement, when the working voltage of a super capacitor is increased to 25Vdc, the standard is less than doubled. Depending on the application, the voltage change may not be significant. 2. Analysis of super capacitors In principle, we can think of super capacitors as rechargeable batteries. It can store a charge proportional to its capacity and release it when it is about to be discharged. The biggest difference between a supercapacitor and an electrolytic capacitor is its double-layer structure, which can obtain a higher capacity. The structure of a standard capacitor is composed of a dielectric layer sandwiched between two electrodes on a metal plate (Figure 1). Depending on the type of capacitor, the dielectric layer may be aluminum oxide, tantalum tantalum tetraoxide, barium titanium oxide, or polypropylene polyester. Different materials determine different capacity and voltage characteristics (Figure 2). The amount of dielectric and the distance between the plates also affect the capacitance. However, the maximum allowable distance between the plates limits the amount of dielectric. In this single-layer structure, the capacity can usually be increased by adding the number of new dielectrics. There are three methods: adding packaging width and sheet standard, adding packaging length and sheet distance, or a combination of the two methods. All three companies will process larger capacitors, which is a promise that must be made to increase the capacity of capacitors. Double-layer capacitors, as they are known, solve this problem by adding a second dielectric layer in the same package, which can be connected with the central insulator at both ends of the first layer (Figure 3). EDLC also uses non-porous media such as activated carbon, carbon nanotubes, carbon black gel, conductive polymer, which has a higher storage capacity than standard electrolytic materials. The combination of this rating layer and more effective dielectric materials can increase capacitance by nearly four orders of magnitude. However, in supercapacitors as a source of dielectric materials, voltage is the weak link. The dielectric is very thin in the EDLC. As long as the nanometer level, a larger surface area can appear, which in turn constitutes a larger capacity. However, these very thin layers do not have the insulating properties of traditional dielectrics and therefore require lower operating voltages. 3. Using super capacitors Compared with standard capacitors and batteries, EDLC has several advantages that make it an ideal choice. These advantages include: charging and discharging time longer than rechargeable batteries, actual power up to 98%, low internal resistance, large power output, good thermal performance, and a better safety margin than batteries and standard capacitors. Unlike all types of batteries, EDLC has no special production requirements, so it is environmentally friendly throughout its service life. Supercapacitors were once big and bulky, and now there are a series of standard products that are suitable for almost all applications and almost all budgets. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: What factors affect the service life of lithium iron phosphate batteries?