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The working principle of supercapacitors
- Time： 2025/9/28 Source： 福布斯客服微信 177 87599998(果博东方开户 客服 上下分)
- According to the different energy storage mechanisms, the working principle of supercapacitors is different. We will divide electrochemical capacitors into two different categories: double-layer capacitors and Faraday quasi capacitors. So, what are the working principles of double-layer capacitors and Faraday quasi capacitors?
1、 Faraday quasi capacitor
The theoretical model of resistance was first proposed by Conway, which involves the underpotential deposition of electroactive substances on the surface and near surface or bulk phases of an electrode in a two-dimensional or quasi two-dimensional space, resulting in highly reversible chemical adsorption desorption and redox reactions, and the generation of capacitance related to the electrode charging potential.
For Faraday quasi capacitors, the process of storing charge includes not only the storage on the double layer, but also the oxidation-reduction reaction between electrolyte ions and electrode active materials. When ions (such as H+, OH -, K+or Li+) in the electrolyte diffuse from the solution to the electrode/solution interface under the action of an external electric field, they will enter the bulk phase of the active oxide on the electrode surface through redox reactions at the interface, thereby storing a large amount of charge in the electrode.
During discharge, these ions that enter the oxide will return to the electrolyte through the reverse reaction of the oxidation-reduction reaction, and the stored charge will be released through the external circuit. This is the charging and discharging mechanism of Faraday quasi capacitors.
2、 Double-layer capacitor
It is caused by the directional arrangement of electrons or ions at the electrode/solution interface, resulting in the confrontation of charges. For an electrode/solution system, a double layer will form at the interface between the electron conducting electrode and the ion conducting electrolyte solution. When an electric field is applied to two electrodes, the anions and cations in the solution migrate towards the positive and negative electrodes respectively, forming a double layer on the surface of the electrodes; After removing the electric field, the positive and negative charges on the electrode attract the opposite charged ions in the solution, stabilizing the double layer and generating a relatively stable potential difference between the positive and negative electrodes.
At this point, for a certain electrode, an opposite ion charge equal to the charge on the electrode will be generated within a certain distance (dispersion layer), keeping it electrically neutral; When the two poles are connected to the external circuit, the charge on the electrodes migrates and generates current in the external circuit. The ions in the solution migrate to the solution and become electrically neutral, which is the charging and discharging principle of double-layer capacitors.
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