Supercapacitors: Principles, Characteristics and Applications

# Supercapacitors: Principles, Features and Applications

## Introduction

Supercapacitors, also known as electrochemical capacitors, electric double layer capacitors, farad capacitors, etc., are a new type of energy storage device between traditional capacitors and rechargeable batteries. Since its development in the 7. and 1980 s, supercapacitors have been widely used in many fields due to their unique energy storage mechanism and excellent performance. This article will introduce the principle, characteristics and applications of supercapacitors in detail.

## Principle

The basic principle of supercapacitors is to store energy using an interfacial double layer formed between an electrode and an electrolyte. When the electrode is in contact with the electrolyte, due to the Coulomb force, intermolecular force and interatomic force, a stable and opposite sign double-layer charge will be formed on the solid-liquid interface, that is, the interface double-layer. This electric double layer structure allows the supercapacitor to store a large amount of charge, thereby achieving high energy density of energy storage.

Specifically, a supercapacitor can be viewed as two non-reactive porous electrode plates suspended in an electrolyte. When a voltage is applied to the two electrode plates, the positive plate attracts negative ions in the electrolyte, and the negative plate attracts positive ions, thereby forming an electric double layer capacitor on the surface of the two electrodes. This energy storage process does not involve chemical reactions, so it is reversible, and it is also the basis for supercapacitors to be able to charge and discharge hundreds of thousands of times.

## Features

### High power density

A notable feature of supercapacitors is their high power density, which can reach 10 ² ~ 10 ²W/kg, which is much higher than the power density level of batteries. This makes ultracapacitors perform well in applications that require high current for short periods of time, such as start-stop systems for electric vehicles and regenerative braking energy recovery.

### Long cycle life

Another significant advantage of supercapacitors is their long cycle life. Under the high-speed deep charge-discharge cycle of a few seconds, the supercapacitor can withstand 500000 to 1 million charge-discharge cycles, and the capacity and internal resistance are only reduced by 10% to 20%. This long life makes supercapacitors ideal for applications requiring frequent charging and discharging.

### Wide operating temperature range

The working temperature range of the super capacitor is very wide, and it can work normally in the environment of -40 ℃ ~ 80 ℃. This feature allows supercapacitors to maintain stable performance in extreme environments, far superior to traditional batteries.

### Green environmental protection

Supercapacitors do not use heavy metals and other harmful chemicals in the production and use process, and their own long life, so it is a green power supply. This feature is in line with the current social requirements for sustainable development.

### Maintenance-free

The supercapacitor has high charge and discharge efficiency, has a certain bearing capacity for overcharge and overdischarge, can be stably charged and discharged repeatedly, and does not need maintenance in theory. This feature reduces the cost of use and improves the reliability of the system.

## Application

### Vehicle Industry

Supercapacitors are widely used in the automotive industry. For example, driving recorders often use supercapacitors as a backup power source to ensure that vehicle data can be saved in the event of an accident such as a vehicle collision. In addition, the super capacitor can also be used in vehicle charging, audio, alarm and other equipment to provide stable power support.

### Intelligent instrument

Intelligent water meter, gas meter, electric meter and other instruments in the installation, often the battery and super capacitor in parallel use. Since the switch valve requires a large starting current at the moment of opening, the super capacitor can provide sufficient current power to ensure the safe opening of the valve.