Supercapacitor Advantages and Disadvantages

This page explores the pros and cons of supercapacitors. It covers the benefits and drawbacks of supercapacitors, also known as ultracapacitors.

What is a Supercapacitor?

Introduction: A supercapacitor is a charge storage device that stores electrical charge through electrochemical and electrostatic processes. Due to the advantages described below, they have the potential to replace or complement traditional batteries and capacitors in a variety of applications. They are used worldwide in various sectors, including automotive, consumer electronics, renewable energy, railways, defense, and power industries.

Supercapacitors are also referred to as ultracapacitors.

Figure 1: Supercapacitor manufactured by Samwha electric.

Supercapacitors are classified into double-layer capacitors, pseudocapacitors, and hybrid capacitors based on their charge storage methods. Double-layer capacitors use electrostatic charge storage, pseudocapacitors use electrochemical charge storage, and hybrid capacitors use both.

Figure 2: Internal construction details of a wound supercapacitor.

Supercapacitors are typically manufactured in cylindrical or rectangular shapes. The layers are stacked in an aluminum can (as shown in Figure 2) or in an adaptable rectangular housing.

Benefits or Advantages of Supercapacitors

Here’s a look at the advantages of using supercapacitors:

• High Energy and Power Density: Supercapacitors offer a higher energy density and power density compared to common capacitors.
• High Capacitance: They offer high capacitance, ranging from 1 mF to over 10,000F.
• Fast Charging: Supercapacitors have the ability to charge very quickly.
• Superior Low-Temperature Performance: They perform well in low-temperature environments (from -40°C to 70°C).
• Long Service Life: Supercapacitors offer a longer service and lifespan (about 10 to 15 years compared to 5-10 years for a Li-ion battery). They have a virtually unlimited cycle life and can be cycled millions of times.
• High Reliability: They provide higher performance reliability.
• Size and Weight Reduction: They can reduce the size and weight of the battery, subsequently lowering costs.
• Eco-Friendly: Supercapacitors meet environmental standards, making them eco-friendly.

Drawbacks or Disadvantages of Supercapacitors

While supercapacitors offer numerous advantages, they also have some drawbacks:

• High Self-Discharge Rate: They have a higher self-discharge rate, which is considerably higher compared to batteries.
• Low Individual Cell Voltages: Individual cells have low voltages, requiring series connections to achieve higher voltages.
• Lower Energy Storage per Unit Weight: The amount of energy stored per unit weight is considerably lower compared to electrochemical batteries. This is about 3 to 5 W.h/Kg for an ultracapacitor compared to 30 to 40 W.h/Kg for a battery.
• Low Energy Density: They offer a lower energy density compared to batteries, about (1/5)th to (1/10)th the energy of a battery.
• Not Suitable for AC Circuits: They cannot be used in AC and higher frequency circuits.