Supercapacitors (Ultracapacitors)

Introduction

• Used as additional energy storage devices in electric vehicles.
• Specifically for storing energy from regenerative braking.

Definition

• A supercapacitor is a specially designed capacitor.
• Capable of storing large electrical charges.
• Can be recharged quickly and releases a significant amount of power.

Components of a Supercapacitor

• Current Collectors: Made from aluminum.
• Electrodes: Composed of activated carbon material.
• Separator: Made from Kapton.
• Electrolyte Solution: Typically made from potassium hydroxide or sulfuric acid.

Working Principle

Charging Process

1. Connection: Charger is connected across the electrodes.
2. Current Flow: Current starts to flow inside the supercapacitor.
3. Ion Distribution:
   • Positive and negative ions are present in the electrolyte.
   • Positive electrode attracts negative ions, forming a layer.
   • Negative electrode attracts positive ions, forming another layer.
4. Electrostatic Forces: Attraction between electrodes and electrolyte creates electric double layers.
5. Electrical Double Layer Capacitor (EDLC):
   • Capacitor C1 is formed due to this layer.
   • Another capacitor C2 forms in series with C1.
   • Total capacitance is influenced by the surface area of electrodes and the distance between them.

Discharging Process

1. Load Connection: A load is connected across the electrodes.
2. Charge Loss: Electrodes lose charge.
3. Current Flow: Charge flows through the external circuit, powering the load.
4. Ions Redistribution: Ions redistribute back across the electrolyte as electrodes discharge.

Applications

• Used as an additional power source in regenerative braking systems.
• Ideal for applications requiring high power over short periods, such as quick accelerations.

Conclusion

• Supercapacitors offer fast charging and discharging capabilities, making them valuable in modern energy storage solutions.