What is the manufacturing process of Super capacitors?

Super capacitor refers to a new type of energy storage device between a conventional capacitor and a rechargeable battery. It has both the characteristics of rapid charging and discharging of capacitors and the energy storage characteristics of batteries.

Super capacitors are new types of components that store energy through the interface layer formed between electrodes and electrolytes. When the electrode is in contact with the electrolyte, due to the Coulomb force, inter molecular force, and inter atomic force, the solid and liquid interface has a stable double charge with opposite symbols, which is called the interface double layer. Consider the double layer super capacitor as two inactive porous plates suspended in the electrolyte, and the voltage is loaded onto two plates. The potential added to the positive plate attracts negative ions in the electrolyte, and the negative plate attracts positive ions, thus forming a double layer capacitor on the surface of the two electrodes. According to the different electrode materials, double layer capacitors can be divided into carbon electrode double layer super capacitors, metal oxide electrode super capacitors and organic polymer electrode super capacitors. [ 1]

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

(1) High power density. Up to 102 to 104W/kg, much higher than the battery's power density level.

(2) Long cycle life. After a few seconds of high speed depth charging and discharging cycles of 500,000 to 1 million times, the characteristics of super capacitors change very little, and the capacity and internal resistance are only reduced by 10 % to 20 %.

(3) Wide working temperature limit. Because the adsorption and desorption speed of ions in super capacitors at low temperature does not change much, their capacity changes much less than that of batteries. The operating temperature of commercial super capacitors can reach -40 °C ~ +80 °C.

(4) Exemption from maintenance. Super capacitors have high charging and discharging efficiency, have a certain ability to overcharge and over discharge, and can be steadily recharged and discharged. In theory, there is no need for maintenance.

(5) Green. Super capacitors do not use heavy metals and other harmful chemicals in the production process, and they have a long life, so they are a new type of green environmental protection power source. [ 1]

For super capacitors, different classification methods can be used depending on the content.

First, according to different energy storage mechanisms, super capacitors can be divided into two categories: double layer capacitors and Faraday quasi-capacitors. Among them, the double layer capacitor mainly generates storage energy by adsorption of pure electrostatic charge on the surface of the electrode. Faraday quasi-capacitors mainly produce Faraday quasi-capacitors through reversible Redox reactions on and near the surface of Faraday quasi-capacitive active electrode materials(such as transition metal oxides and polymer polymers) to achieve energy storage and conversion.

Secondly, according to the types of electrolytes, they can be divided into two categories: water Super capacitors and organic Super capacitors.

In addition, symmetric super capacitors and asymmetric super capacitors can be divided into the same type of active material.

Finally, according to the state of the electrolyte, super capacitors can be divided into two categories: solid electrolyte super capacitors and liquid electrolyte super capacitors. [ 2]

1) Life: If the internal resistance of the super-capacitor increases, the capacity is reduced J within the specified parameters, and its effective use time can be extended, generally related to its characteristics as stipulated in Article 4. What affects life span is the drying up of activity and the increase of internal resistance. The reduction of storage power capacity to 63.2 % is called the end of life.

2) Voltage: Super capacitors have a recommended voltage and an optimal operating voltage. If the voltage is higher than the recommended voltage, the service life of the capacitor will be shortened. However, the capacitor can work under over pressure for a long period of time. The activated carbon inside the capacitor will decompose into gas. It is advantageous to store electrical energy, but it can not exceed 1.3 times the recommended voltage, otherwise it will damage the Super capacitor due to the high voltage.

3) Temperature: The normal operating temperature of the super capacitor is -40 ~ 70 °C. Temperature and voltage are important factors that affect the life of super capacitors. For each temperature increase of 5 °C, the lifetime of the capacitor will decrease by 10 %. At low temperature, the operating voltage of the capacitor is increased, and the internal resistance of the capacitor does not rise, which can improve the efficiency of the capacitor.

4) Discharge: In pulse charging technology, capacitance resistance is an important factor; In small current discharge, capacity is also an important factor.

5) Charging: There are many ways to charge capacitance, such as constant current charging, constant pressure charging, Pulse charging, etc.. During the charging process, connecting a resistor to a capacitor loop will reduce the charging current and increase the service life of the battery.

The precautions for the use of Super capacitors include:

1) Super capacitors have a fixed polarity. Before use, the polarity should be confirmed.

2) Super capacitors shall be used at nominal voltage. When the voltage of the capacitor exceeds the nominal voltage, it will cause the electrolyte to decompose. At the same time, the capacitor will heat up, the capacity will drop, and the internal resistance will increase and the life span will be shortened.

3) Super capacitors can not be used in high-frequency charging and discharging circuits. High frequency rapid charging and discharging will lead to internal heating of the container, attenuation of capacity, and increase of internal resistance.

4) External ambient temperature has an important influence on the life of super capacitors. Therefore, Super capacitors should be kept as far away from heat sources as possible.

5) When the super capacitor is used as a backup power supply, there is a voltage drop at the moment of discharge due to the fact that the super capacitor has a large internal resistance.

6) Super capacitors shall not be in an environment with relative humidity greater than 85 % or containing toxic gases, which may cause lead wire and capacitor housing corrosion and cause circuit breakage.

7) Super capacitors can not be placed in high-temperature and high-humidity environments. They should be stored at temperatures of -30 to 50 °C and relative humidity is less than 60 %, and should avoid sudden and sudden changes in temperature, because this will lead to product damage.

8) When the super capacitor is used on a double-sided circuit board, it is necessary to pay attention to the place where the connection can not be reached by the capacitor. Due to the installation of the super capacitor, short-circuit phenomenon will result.

9) When the capacitor is welded to the circuit board, the capacitor shell must not be touched to the circuit board. Otherwise, the welding material will infiltrate into the wire hole of the capacitor, which will affect the performance of the capacitor.

10) After installing the Super capacitor, do not force tilt or twist the capacitor, which will lead to loosening of the lead wire of the capacitor and lead to poor performance.

11) Super heat the capacitor should be avoided during welding. If the capacitor is overheated during welding, the service life of the capacitor will be reduced.

12) After the capacitor is welded, it is necessary to clean the circuit board and capacitor because certain impurities may cause the capacitor to short circuit.

13) When Super capacitors are used in series, there is a voltage equilibrium problem between monomers. Simple series can cause one or more monomer capacitors to over pressure, thus damaging these capacitors and affecting their overall performance. Therefore, when capacitors are used in series, Technical support from manufacturers is required.

14) Other application problems in the use of super capacitors should be consulted with the manufacturer or refer to the relevant technical information in the instructions for the use of super capacitors.

The page contains the contents of the machine translation.