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What is the electrochemical capacitor?

2019-08-15 |

Electrochemical capacitors are also supercapacitors.

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.

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.

Compared with batteries and traditional physical capacitors, the characteristics of supercapacitors are mainly reflected in:

High power density. It can reach 102~104 W/kg, which is much higher than the power density level of the battery.

Long cycle life. After a few seconds of high-speed deep charge and discharge cycles of 500,000 to 1 million cycles, the characteristics of the supercapacitor change little, and the capacity and internal resistance are only reduced by 10% to 20%.