The word "EDLC" is often used for the types of batteries and power storage devices, but many people may not understand the content.

This time, we will introduce the definition, features, and types of EDLC.

What is EDLC?

EDLC is an abbreviation for Electric Double Layer Capacitor.

Since it is a type of capacitor, it does not use a chemical reaction like a battery to store electricity but uses the adsorption force on the electrode surface. (See "What is a capacitor?")

It is the "Electric Double Layer" that is the origin of the name of this capacitor that brings about this adsorption power.

When a conductor is immersed in an electrolytic solution and electricity is passed between the positive and negative electrodes, negative ions are adsorbed on the surface of the positive electrode and positive ions are adsorbed on the surface of the negative electrode as a layer of one molecule, respectively, and the electrolytic solution on the outside thereof is adsorbed. The phenomenon that the diffusion layer spreads occurs. The layer of these ions formed on the electrode surface is called the electric double layer.

The amount of electricity stored as an electric double layer increases in proportion to the size of the electrode surface. In other words, in order to store more electricity in the same volume of electrodes, it is advantageous to use a material with a large surface area. This is the reason why activated carbon is widely used as an electrode material for EDLC.

Features of EDLC

Compared to multilayer ceramic capacitors and aluminum electrolytic capacitors, EDLC uses the electric double layer capacitance formed on the surface of activated carbon, in addition to the features of capacitors (capacitors) such as rapid charge / discharge properties, long-term reliability, and safety. It can store orders of magnitude more electricity.

Due to its large capacity, we often see literature and treatises that describe EDLCs as "supercapacitors", but this is a trademarked trade name and is not academically correct. If you come across these notations, you should read them as EDLC and understand them.

More than 40 years have passed since this EDLC was commercialized, and compared to hybrid capacitors, which have been actively developed in recent years, they are lagging behind in terms of capacity. However, it is a capacitor that is still widely used globally due to its ease of use, such as being completely discharged and usable.

Types of EDLC

There are several types of EDLC.

Classification by material

First, I will explain the classification according to the materials used.

Electrodes and electrolytes are the most important elements that make up EDLC.

Of these, activated carbon is often used as the electrode material, as mentioned above.

On the other hand, electrolytes can be broadly divided into organic (non-aqueous) and aqueous.

In other words, EDLCs can be classified into organic EDLCs and water-based EDLCs.

Organic EDLCs have the advantage of higher usable voltage than water-based EDLCs.

This is because the organic electrolyte has a wider range of electrochemical decomposition voltage than the water system, and the withstand voltage is about 2.3 to 2.8 V in the organic system compared to about 0.8 V in the water system. increase.

On the other hand, in terms of safety, water-based EDLCs that do not use flammable electrolytes are safer, and the manufacturer side does not have to worry about water contamination, which is a process advantage. It is used properly by taking advantage of each characteristic.

Classification by shape

Another classification of EDLC is by shape.

Typical small EDLCs are coin type and chip type, and most of them are mounted on a board and widely used mainly for memory backup of mobile devices.

Larger types include EDLCs such as cylindrical, square and laminated package types. These are sometimes used as cells alone, but many are modularized and used in a wide range of fields such as backup power supplies for electronic devices and mobiles, and main power supplies.

Summary about EDLC

We wrote about the definition, features, and types of EDLC.

We, Musashi Energy Solutions, hybridize EDLC and lithium-ion batteries and develop and manufacture Hybrid SuperCapacitors that take advantage of both of their features.

If you are interested in or have questions about Hybrid SuperCapacitors, please contact us using the inquiry form.