Introduction:
Supercapacitors are new components that store energy through a double-layer interface formed between electrodes and electrolytes. When the electrode is in contact with the electrolyte, due to the action of coulomb force, intermolecular force and interatomic force, there is a stable and opposite double-layer charge at the solid-liquid interface, which is called the interface double-layer. The double layer supercapacitor is regarded as two inactive porous plates suspended in the electrolyte, and the voltage is applied to the two plates. The potential applied to the positive plate attracts the negative ions in the electrolyte, and the negative plate attracts the positive ions, thus forming a double-layer capacitor on the surface of the two electrodes. According to the different electrode materials, double-layer electric capacitor can be divided into carbon electrode double-layer supercapacitor, metal oxide electrode supercapacitor and organic polymer electrode supercapacitor.
Compared with batteries and traditional physical capacitors, the characteristics of supercapacitors are mainly reflected in:
(1) High power density. It can reach 102 ~ 104 W/kg, which is much higher than the power density level of the battery.
(2) Long cycle life. After a high-speed deep charge and discharge cycle of 500,000 to 1 million times in a few seconds, the characteristics of the supercapacitor change very little, and the capacity and internal resistance are only reduced by 10% to 20%.
(3) Working temperature limit. Because the adsorption and desorption rate of ions in the supercapacitor does not change much at low temperature, its capacity changes much less than that of the battery. The operating temperature range of commercial supercapacitors can reach -40¡æ ~ +80¡æ.
(4) Maintenance free. Supercapacitors have high charge and discharge efficiency, have a certain ability to withstand overcharge and overdischarge, and can stably charge and discharge repeatedly, which does not require maintenance in theory.
(5) Green environmental protection. Supercapacitors do not use heavy metals and other harmful chemicals in the production process, and have a long life, so they are a new type of green power supply.
