Supercapacitor battery, also called gold capacitor and Faraday capacitor, stores energy by polarizing the electrolyte, which is a kind of double layer capacitor. Since the process of its energy storage does not occur chemically, this energy storage process is reversible, and because of this supercapacitor can be charged and discharged hundreds of thousands of times repeatedly. Supercapacitor generally uses activated carbon electrode material, which has the characteristics of large adsorption area and more electrostatic storage, and is widely used in new energy vehicles.
Supercapacitor battery is also called double-layer capacitor (ElectricalDouble-LayerCapacitor) is a new type of energy storage device, which has the characteristics of short charging time, long service life, good temperature characteristics, energy saving and green environment protection. Supercapacitor is widely used. It can be used as a power balancing power source for lifting devices, which can provide super large current power; as a vehicle starting power source, which has higher starting efficiency and reliability than traditional batteries, and can replace traditional batteries in whole or in part; as a traction energy source for vehicles, which can produce electric cars, replace traditional internal combustion engines, and transform existing trolley buses; in the military, which can ensure smooth starting of combat vehicles such as tanks and armored vehicles ( Especially in the cold winter), and as a pulse energy source for laser weapons. It can also be used as energy storage for other electromechanical devices.
Due to the increasing shortage of petroleum resources and the increasingly serious environmental pollution caused by exhaust emissions from oil-burning internal combustion engines (especially in large and medium-sized cities), people are studying new energy devices to replace internal combustion engines. Research and development of hybrid, fuel cell and chemical battery products and applications have been carried out, and certain results have been achieved. However, there has been no good solution due to their inherent fatal weaknesses such as short service life, poor temperature characteristics, environmental pollution by chemical cells, complex systems, and high cost. Supercapacitors, with their excellent characteristics, can partially or fully replace traditional chemical batteries for vehicle traction power and starting energy, and have a wider range of applications than traditional chemical batteries. Because of this, countries all over the world (especially developed countries in the West) have spared no efforts in research and development of supercapacitors. Among them, countries such as USA, Japan and Russia are not only ahead in R&D and production, but also have established special national management agencies (e.g. USABC in USA, SUN in Japan, REVA in Russia, etc.), formulated national development plans, and actively promoted by the state with huge investment and manpower. As far as the technology level of ultracapacitors is concerned, Russia is ahead of the world at present, and its products have been commercially produced and applied, and have been rated as the most advanced products by the 17th Annual International Electric Vehicle Conference (EVS-17), and countries such as Japan, Germany, France, UK, Australia, etc. are also rushing to catch up, and the fields of promoting and applying ultracapacitors in various countries are quite extensive at present. Promoting the use of supercapacitors in China can reduce oil consumption, reduce the dependence on oil import and contribute to national oil security; effectively solve the problem of urban exhaust pollution and lead-acid battery pollution; and contribute to solving the problem of low-temperature starting of chariots. At present, there are mainly more than 10 domestic enterprises in the research and development of supercapacitors
Supercapacitor is a brand-new capacitor based on the interface double electric layer theory proposed by German physicist Helmholtz. It is well known that the excess charge of opposite sign will appear on both sides of the surface of the metal electrode inserted into the electrolyte solution and the liquid surface, thus creating a potential difference between the phases. Then, if two electrodes are inserted in the electrolyte solution at the same time and a voltage smaller than the decomposition voltage of the electrolyte solution is applied between them, the positive and negative ions in the electrolyte solution will move rapidly to the two poles under the action of electric field and form a close charge layer, i.e., double electric layer, on the surface of the two upper electrodes respectively, and the double electric layer formed by it is similar to the polarized charge produced by the dielectric in the conventional capacitor under the action of electric field. The tight double layer is similar to a flat capacitor, but the distance between the charge layers is much smaller than that of an ordinary capacitor, which results in a larger capacity than that of an ordinary capacitor.
The double layer capacitor has higher internal resistance compared with aluminum electrolytic capacitor, so it can be charged directly without load resistance, and in case of over voltage charging, the double layer capacitor will open circuit without damaging the device, which is different from the over voltage breakdown of aluminum electrolytic capacitor. Meanwhile, compared with rechargeable battery, the double layer capacitor can be charged without current limit and the charging times can be more than 10E6 times, so the double layer capacitor has not only the characteristics of capacitor but also the characteristics of battery, which is a new special component between battery and capacitor.
The capacity of super capacitor is much larger than the usual capacitor. Because of its high capacity and the same external performance as a battery, it is also called "capacitor battery" or "golden battery". Supercapacitor battery is also a double layer capacitor, and it is the largest capacity among the double layer capacitors that have been put into mass production in the world, and its basic principle is the same as that of other types of double layer capacitors, both of which use the double layer structure of activated carbon porous electrode and electrolyte to obtain a large capacity.
The electrical energy stored in a conventional physical capacitor comes from the separation of charges on the two plates, which are separated by a vacuum (relative permittivity of 1) or a layer of dielectric material (relative permittivity of ε), and the capacitance value is: C=ε-A/3.6πd-10-6(μF), where A is the area of the plates and d is the thickness of the dielectric. The stored energy is: E=C(ΔV)2/2, where C is the capacitance value and ΔV is the voltage drop between the plates. It can be seen that if we want to get a larger electric capacity and store more energy, we must increase the area A or reduce the dielectric thickness d, but this expansion space is limited, which leads to its smaller storage capacity and energy storage. Supercapacitor uses activated carbon material to make porous electrodes, while filling electrolyte solution between the opposite carbon porous electrodes, when voltage is applied at both ends, positive and negative electrons will be gathered on the opposite porous electrodes, and positive and negative ions in the electrolyte solution will be gathered on the interface opposite to the positive and negative plates respectively due to the electric field, thus forming two collector layers, which is equivalent to two capacitors in series, because the activated carbon Since the activated carbon material has an ultra-high specific surface area of ≥1200m2/g (i.e., a very large electrode area A is obtained), and the interface distance between the electrolyte and the porous electrode is less than 1nm (i.e., a very small dielectric thickness d is obtained), it can be seen from the previous formula that the capacitance of this double layer capacitor is much larger than the traditional physical capacitance, and the specific capacity can be increased by more than 100 times, so that the unit weight The capacitance per unit weight can reach 100F/g, and the internal resistance of the capacitor can be kept at a very low level, and the carbon material has the advantages of low cost and mature technology. This makes it possible to use capacitors to store large amounts of energy, and in practice, they can be connected in series or parallel to increase the output voltage or current.
(1) Fast charging speed, as long as charging tens of seconds to minutes to reach more than 95% of its rated capacity; while now the largest area of use of lead-acid batteries charging usually takes several hours.
(2) Long cycle life, the number of deep charge/discharge cycles can reach 500,000 times, if the super capacitor is charged and discharged 20 times a day, the continuous use can reach 68 years. If we compare it with lead-acid battery, its service life can reach 68 years, and there is no "memory effect".
(3) High current discharge capability, high energy conversion efficiency, small process loss, high current energy cycle efficiency ≥ 90%.
(4) High power density, up to 300W/kg~5000W/kg, equivalent to dozens of times of ordinary batteries; specific energy is greatly improved, lead-acid batteries can only reach 200W/kg, while the current research and development of super capacitor battery has reached 10KW/kg.
(5) The composition of raw materials, production, use, storage and dismantling process are pollution-free, which is an ideal green power source.
(6) Simple charging and discharging circuit, no need for charging circuit like rechargeable battery, high safety factor, maintenance-free for long-term use.
(7) good ultra-low temperature characteristics, the use of a wide range of ambient temperature of -40 ℃ ~ +70 ℃.
(8) Convenient detection, the remaining power can be read out directly.
(9) Single capacity range is usually 0.1F--3400F.
