Electric Double-Layer Capacitors (EDLC) is a new energy storage device which mainly depends on double layer and pseudocapacitance charge. Different from traditional chemical power sources, EDLC is a kind of power source between traditional capacitors and batteries, with advantages such as high power density, short charge and discharge time, long cycle life and wide operating temperature range. Therefore, it can be widely used in different application scenarios such as auxiliary peak power, standby power supply, storage of renewable energy and alternative power supply. It has huge application value and market potential in industrial control, electric power, transportation, intelligent instrument, consumer electronics, national defense, communications, new energy vehicles and many other fields.
In the supercapacitor industry chain, the raw materials of production are mainly positive and negative electrodes/electrolyte and diaphragm. The active electrode material of double layer capacitor is mostly activated carbon, and its production process is as follows: batching → slurry mixing → electrode making → slice cutting → assembly → liquid injection → activation → detection → packaging. The whole process has high technical content and high entry threshold.
Currently, activated carbon materials with a specific surface area of more than 3000m2/g have been prepared, but the real utilization rate is only about 30% when used for the electrode of supercapacitor. Therefore, the specific surface area of AC usually used at present is about 1500m2/g, generally not more than 2000m2/g. Their maximum specific capacities could be as high as 280F/ G (stream electrolyte) and 120F/g (non-stream electrolyte).
The conductivity of activated carbon is one of the important factors affecting the charge-discharge performance of supercapacitor. For activated carbon materials, the conductivity decreases with the increase of surface area, on the one hand, the content of activated carbon on the wall of the material micropores decreases with the increase of surface area; On the other hand, the conductivity of activated carbon material is closely related to the contact area between activated carbon particles and the position of activated carbon particles. The electrolyte solution is impregnated in the pores of activated carbon particles and the gap between the particles. Whether fully impregnated between activated carbon and electrolyte will have a great influence on the conductivity of the capacitor. The surface characteristics of the material, especially the pore size and hole depth of the micropores, are important factors to determine the conductivity.
High specific surface area activated carbon is the main cathode material used for supercapacitors at present, but its cost accounts for nearly 40-50% of the total cost of the product. With the rapid growth of super capacitor market, the demand for super activated carbon is increasing at home and abroad.
