Fully Charged In 30 Seconds? Super Capacitor Technology Explained

- Jun 06, 2020-

Basic structure of super capacitor

Supercapacitors are also called electric double layer capacitors. From a structural point of view, they are very similar to electrolytic capacitors. Simply put, if two electrodes are inserted into the electrolyte and a voltage is applied, then the positive and negative ions in the electrolyte will quickly move to the two poles under the application of the electric field, and eventually form a compact on the surface of the two electrodes. The electric charge layer, namely the electric double layer.


Super capacitor working diagram

The size of the capacitor depends on the size of the electrode surface area and the distance between the two electrodes. The surface area of the electrode of a traditional capacitor is the flat area of the conductor. In order to obtain a larger capacity, the conductor material is usually rolled very long, and sometimes a special organizational structure is used to increase its surface area. At the same time, traditional capacitors use insulating materials to separate its two electrodes, generally plastic film, paper, etc. These materials also require as thin as possible.


The electrode surface area of the supercapacitor is based on a porous carbon material. The porous structure of the material makes its surface area very large, and the distance between the electrodes of the supercapacitor is determined by the size of the electrolyte ions attracted to the charged electrode. The distance achievable by thin film materials is smaller. This huge surface area, coupled with a very small electrode spacing, makes supercapacitors have an amazing electrostatic storage capacity compared to traditional capacitors, which is also an important reason for being called "super".


The basic uses of capacitors are charging and discharging, but the many circuit phenomena extended by the basic charging and discharging uses make the capacitors more colorful. In general electronic circuits, capacitors are commonly used to achieve bypass, coupling, filtering, oscillation, phase shift, and waveform transformation. These uses are the evolution of charging and discharging functions. According to various characteristics of supercapacitors, they are more used in the energy field and are usually used as batteries.


Advantages and disadvantages of supercapacitors

Compared with lead-acid batteries, nickel-cadmium batteries, and lithium-ion batteries, supercapacitors have the advantages of energy saving, long service life, safety, environmental protection, wide temperature range, and no need for manual maintenance. Since the super capacitor uses a physical method to store energy, one of its most important features is its high power density. We can understand it as rapid charging and discharging and can instantly absorb or release extremely high energy. This is also any current The battery can't do it.


Perhaps everything has imperfections, and supercapacitors are no exception. One of its relatively fatal weaknesses is its low energy density. The so-called energy density refers to the amount of energy stored in a certain space or mass substance. For example, the number 5 rechargeable battery that we often use, if its milliampere hour is greater, it means that its energy density is higher. It can be said that super capacitors have lower energy density than lithium-ion batteries, which limits their application in many fields.


After understanding some overviews of supercapacitors, let's take a look at the fields where it is currently applied. First of all, the emergence and development of any new technology is often the first to be applied in the military field. Whether the original intention of super capacitor research and development is the same, we do not know very well, but in a complex battlefield environment, super capacitors do have special advantages. The wide temperature range (usually between -40℃-65℃) and high power density mentioned above can ensure the smooth start-up of high-power military vehicles such as tanks and armored vehicles, especially in the cold winter. Its high power density can also be used as a pulse energy source for laser weapons.


In the civil field, super capacitors also play a huge role. For example, it can be used for the power supply of the camera flash, which can make the flash achieve continuous performance, thereby improving the camera's ability to continue shooting, and the super capacitor can also be used to control the camera shutter. In addition, with the development of the electronics and energy industries, supercapacitors have irreplaceable uses in maintenance-free systems such as short-term UpS systems and solar power systems.


Because the super capacitor can charge and discharge at high power, according to this feature, the super capacitor can be applied to some vehicles to store the braking energy of trains or large passenger cars and supply peak power output during acceleration. Due to the fast charge and discharge speed, the super capacitor can be fully charged in a short time when the vehicle enters and exits the station, and it is enough to run to the next station. In this way, the vehicle does not need to carry a pantograph, and no longer needs to erect high-voltage lines along the way, which undoubtedly reduces construction costs.