Supercapacitors

Question 1

What are capacitors?

Answer 1

• An alternative for energy storage, with the electric potential energy stored related to the voltage and charge on the capacitor.
• Energy is stored in electric field instead of chemical reaction.

Question 2

What is the equation of a capacitor and the energy stored?

Answer 2

Equation for capacitor:
q = CV
q: charge, C: capacitance, V: voltage

Equation for energy stored:
U = 1/2 CV^2 (J)

Question 3

What are the 3 things capacitors consist of?

Answer 3

1. Conductive parallel plates.
2. Insulating dielectric layer.
3. Voltage from a power source.

Question 4

What are Supercapacitors (SC)?

Answer 4

They are energy storage devices that bridge the gap between baterries and conventional capacitors.

Question 5

What are the properties of supercapacitors?

Answer 5

• store more energy
• supply energy at higher power outputs
• high cyclability
• long-term stability

Question 6

What is used in the electrodes of commercial supercapacitors and why?

Answer 6

• porous carbons
  Because of:
  1. high surface area
  2. Good conductivity

Question 7

How does a supercapacitor operate?

Answer 7

• Consists of two parallel electrodes separated by a non-conductive material impregnated with an electrolyte.
• Applying potential between electrodes, ions in electrolyte are attracted to electrode of opposite charge.
• Electrostatic double-layer (EDL) created on each electrode.
• Therefor3e, two contributions to capacitance of device.

Question 8

Give another name for supercapacitors.

Answer 8

Electrostatic double-layer capacitors (ELDCs).

Question 9

How could an increase in energy storage of SC be achieved?

Answer 9

1. Using high voltages upon charging.
2. Increasing their capacitance.
   U = 1/2 CV^2

Question 10

What does the energy storage determine of SCs?

Answer 10

The number of charges it can hold.

Question 11

What problem can be faced if the potential of the electrolyte used in SC goes beyond the limit of its stability?

Answer 11

If the increase in potential passes the limit of stability there are two consequences:
1. Decomposition of electrolyte
2. Unwanted reactions degradind the material in the SC

Question 12

What are the applications of SCs?

Answer 12

1. Defibrillators
2. Big buses
3. Fast-charging transport vehicles (e.g. electric shuttle)