Overview and Features

Supercapacitors have much higher performance than ordinary capacitors. Features include very large capacitance, low ESR, high cycle life and low charge time.

Although their energy density is inferior to that of batteries, they are suitable for applications that require instantaneous charging/discharging or charging/discharging with large currents, or applications that require durability due to less deterioration in performance.

Now let's talk about supercapacitors.

Classification and characteristics of supercapacitors

Supercapacitors can be broadly classified into three types as shown in Figure 1.

The current mainstream is the supercapacitor, which is called an electric double-layer capacitor (EDLC).

Energy is conserved through charge adsorption/desorption reactions.

Figure 1 Classification of supercapacitors

As shown in Figure 2, supercapacitors have higher power density than batteries and higher energy density than general capacitors.

Batteries can be charged in hours, while supercapacitors can be charged quickly in seconds and have unlimited charge/discharge cycles.

Figure 2: Energy density and power density: Wurth Elektronik HP​

Due to its characteristics, it is used for the following purposes.

・Supplying power when replacing the battery or when the power is turned off

・Data protection of IC memory in case of emergency such as power failure

Extends battery life with power assist during energy fluctuations

main parameters

Basic parameters of EDLC

・Rated voltage: Many products are rated at 2.7V, etc., and applying a voltage exceeding the withstand voltage may cause a failure. Use in series to obtain high voltage.

・Capacitance: There are many products with a few F to several hundred F, and they have a tremendously large capacity compared to general capacitors.

・ ESR: Many products have several m to several tens of mΩ. Compared to ceramic capacitors, they are larger and can carry large currents, so ESR can be a factor in heat generation.
It is necessary to consider heat generation when performing continuous charging and discharging with a large current.

・Energy storage capacity: Can be calculated using the following formula. It is necessary to select a product with the required energy storage capacity depending on the application.

Summary

Supercapacitors have many advantages such as a very large capacitance, rapid charging and discharging, and a long service life.

It plays an intermediate role between a general capacitor and a battery, and plays an important role in performing backup power supply and power assist.

Information on simulation tools

Please click the image above. Link to the simulation tool "RED EXPERT" page.

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