Capacitors use static electricity rather than chemical reactions to store energy. A Capacitor consists of two conducting metal plates with an insulating material called a dielectric in between them. Basically, positive and negative charges build up on the plates and the dielectric (separates two plates) prevents them coming into contact, is what stores the energy. The dielectric of a capacitor allows a capacitor of a certain size to store more charge at the same voltage.
Super Capacitor or Ultra Capacitor
A Super Capacitor differs from a normal capacitor. Its plates have a much bigger area and the distance between them is smaller. The plates are separated by a separator of very small thickness.
The Super Capacitor plates are metal coated with a porous substance such as powdery, activated charcoal. Actually, there is no dielectric as such in a supercapacitor. Both plates are soaked in an electrolyte and separated by a very thin insulator such as plastic, carbon, paper, etc.
When Super Capacitor’s plates are charged up, an opposite charge forms on the different side of the separator, creating an electric double layer having very small thickness i.e. one molecule thick. The separator stops the electrodes from touching and short-circuiting.
Super Capacitors are also called by other names such as Ultra Capacitors or Double-layer Capacitors or Electric double layer Capacitors or EDLCs.
Super Capacitor or double layer capacitor store energy much in the same way as a conventional capacitor, hence the amount of stored energy can be described by
Note: Batteries have higher energy density whereas Super Capacitors have higher power density.
Advantages
- Comparatively quick response time.
- It can store and release energy almost instantly.
- Typical power ratings are 1kW-250kW and efficiencies in the range of 85-98 %.
Disadvantages
- High Self-discharge
- High Cost
- Low energy density
Applications
- Supercapacitors are suitable for high power applications and offer very quick response times and high efficiency.
- Store power in a hybrid bus.
- Used in Wind turbines, where supercapacitors help to smooth out the intermittent power supplied by the wind.
- It is also used in storing energy due to regenerative breaking in Electric Vehicles, and Hybrid Vehicles.
