In principle, there are two kinds of electrical energy storage mechanisms for electrochemical capacitors. One is to store the charge in the electric double layer at the interface of the electrode/electrolyte solution. The typical high specific surface area carbon is the electrode material; the other is the utilization The two-dimensional or quasi-two-dimensional Faraday reaction on the surface of the electrode stores charge, typically with some transition metal oxide as the electrode material, typically represented by cerium oxide.
The unit of the electrochemical capacitor consists of a pair of electrodes, a separator and an electrolyte. The electrodes are electrically blocked by ions, and the separator and the electrode are both impregnated with an electrolyte. The materials used for electrochemical capacitor electrode materials are mainly carbon materials, metal oxides, conductive polymers and the like. Carbon-based materials are currently the most successful supercapacitor electrode materials in industrialization. Recent research has focused on increasing the specific surface area of materials and controlling the pore size and pore size distribution of materials.
The current carbon-based materials mainly include: activated carbon powder, activated carbon fiber, carbon aerogel, carbon nanotubes, nano carbon fiber, and the like. Carbon-based materials have stable performance and are inexpensive, but the internal resistance of the electrodes is large and it is not suitable for working at high currents. Metal oxides are mainly concentrated in the study of ruthenium dioxide (RuO2). Its conductivity is two orders of magnitude larger than that of carbon-based materials, and it is stable in sulfuric acid solution. Its specific capacitance is as high as 768 F/g, which is the ideal metal oxidation. The electrode material, but its expensive price limits its wide application. Therefore, finding a stable and inexpensive electrode material has become a hot spot in electrochemical capacitor research.
It is a new type of energy storage device between a capacitor and a battery. Electrochemical capacitors have a higher specific capacity than conventional capacitors. Compared with the battery, it has higher specific power, can release large current instantaneously, has short charging time, high charging efficiency, long cycle life, no memory effect and basically maintenance-free. Therefore, it has great potential application value in the fields of mobile communication, consumer electronics, electric vehicles, and aerospace.