What is a super capacitor? What's the difference with ordinary capacitors? Supercapacitors, also known as electrochemical capacitors, double layer capacitors, gold capacitors, Farah capacitors, are an electrochemical element for energy storage through polarized electrolytes.

　　It is different from the traditional chemical power supply and is a kind of power supply with special performance between the traditional capacitor and the battery. It mainly depends on the double layer and the redox pseudocapacitance charge to store the electric energy. But there is no chemical reaction in its energy storage process, which is reversible and because the supercapacitor can charge and discharge hundreds of thousands of times over.


　　Specific details on the structure of supercapacitors depend on the application and use of supercapacitors. these materials may vary slightly due to manufacturer or specific application requirements. The commonality of all supercapacitors is that they contain a positive electrode, a negative electrode, and a diaphragm between the two electrodes. The electrolyte fills the pores of the two electrodes and the diaphragm.

　　The structure of supercapacitors is composed of porous electrode materials with high surface area, porous battery diaphragm and electrolyte. The diaphragm shall meet the conditions of having the highest possible ionic conductance and the lowest possible electronic conductance, generally fiber-structured electronic insulating materials, such as polypropylene films. The type of electrolyte is selected according to the properties of electrode materials.

　　According to the different energy storage mechanism, it can be divided into the following two categories:

　　1、Dual layer capacitance: a charge confrontation at the electrode / solution interface caused by the directional arrangement of electrons or ions. For an electrode / solution system, a double layer is formed at the interface between the electron-conducting electrode and the ion-conducting electrolyte solution. when an electric field is applied on both electrodes, the anions and cations in the solution migrate to the positive and negative electrodes, respectively, and form a double layer on the electrode surface. after the electric field is withdrawn, the positive and negative charges on the electrode attract the opposite charge ions in the solution and make the double layer stable, resulting in a relatively stable potential difference between the positive and negative electrodes. For an electrode, an opposite ion charge equal to the charge on the electrode is generated at a certain distance (dispersion layer) to keep it electrically neutral; when the poles are connected to the external circuit, The charge migration on the electrode produces current in the external circuit, and the ion migration in the solution is electrically neutral. This is the charge-discharge principle of double-layer capacitance.


　　Faraday quasi-capacitance: its theoretical model was first proposed by Conway. It is an underpotential deposition of electroactive substances on the electrode surface and two-dimensional or quasi-two-dimensional space in the near surface or body phase. A highly reversible chemical desorption and redox reaction occur to produce capacitors related to electrode charging potential.

　　For Faraday quasi-capacitors, the process of storing charges includes not only storage on double layers, but also redox reaction between electrolyte ions and electrode active substances. When ions in the electrolyte (such as H 、OH-、K or Li) diffuse from the solution to the electrode / solution interface under the action of an external electric field, they enter the bulk phase of the active oxide on the electrode surface through the redox reaction at the interface. Thus, a large amount of charge is stored in the electrode.

　　During discharge, the ions entering the oxide will be returned to the electrolyte through the reverse reaction of the redox reaction above, and the stored charge will be released through the external circuit, which is the charge and discharge mechanism of the Faraday quasi-capacitor.

　　The advantages of super capacitor :1, the capacity to reach Farah level in very small volume ;2, no special charging circuit and control discharge circuit ;3, overcharge and overplay compared with the battery do not have a negative impact on its life ;4, from the point of view of environmental protection, it is a green energy ;5, supercapacitors can be welded, so there are no problems such as battery contact is not firm;


　　The disadvantages of super capacitor :1, if used improperly will cause electrolyte leakage and other phenomena ;2, compared with aluminum electrolytic capacitor, its internal resistance is larger, so it can not be used in AC circuit;?

　　The reason why supercapacitors are called "super ":1, supercapacitors can be regarded as two reactive porous electrode plates suspended in the electrolyte, charged on the electrode plate, the positive plate attracts negative ions in the electrolyte, and the negative plate attracts positive ions. In fact, two capacitive storage layers are formed.

　　The supercapacitor stores energy in the separated charge. the larger the area used to store the charge, the denser the separated charge, the larger its capacitance.

　　The area of the traditional capacitor is the flat area of the conductor. In order to obtain a large capacity, the conductor material is rolled very long, and sometimes the surface area is increased by special structure. Traditional capacitors are two-pole plates separated by insulating materials, usually plastic film, paper, etc. These materials usually require as thin as possible.

　　Area of supercapacitor is based on porous carbon material, the porous structure of the material allows its area to reach 2000 m2/g, and a larger surface area can be achieved by some measures. The distance of charge separation of supercapacitors is determined by the size of electrolyte ions attracted to charged electrodes. The distance (<10 A) and the distance that traditional capacitor film materials can achieve are smaller.


　　The huge surface area and the very small charge separation distance make supercapacitors have amazing electrostatic capacity compared with traditional capacitors, which is also the "super" of supercapacitors.

　　RenhotecIC will let you know more about supercapacitors.