Basics of Capacitor and Detailed theory of ultracapacitors

1. Presented By:-
Mr. Manish Dhiman

2. Content
 What is Capacitor?
 What are Ultracapacitors?
 Construction and working
 Formation of double layer
 Types of Ultracapacitors
- Double-layer Capacitors
- Pseudocapacitors
- Hybrid Capacitors
 Comparison with Battery and Conventional Capacitor
 Advantages
 Disadvantages
 Applications
 Conclusion

3. What is Capacitor?
• A capacitor (originally known as condenser) is
a passive two-terminal electrical component used to
store energy in an electric field.
• Basically, a capacitor is made up of two conductors
separated by an insulator called dielectric.
• The dielectric can be made of paper, plastic, mica,
ceramic, glass, a vacuum or nearly any other
nonconductive material.
• Some capacitors are called Electrolytic in which the
dielectric is aluminium foil conductor coated with oxide
layer.

4. What are Ultracapacitors?
• Ultracapacitors can be defined as a energy storage
device that stores energy electro statically by polarizing
an electrolytic solution.
• Unlike batteries no chemical reaction takes place when
energy is being stored or discharged and so
ultracapacitors can go through hundreds of thousands of
charging cycles with no degradation.
• Ultracapacitors are also known as double-layer
capacitors or supercapacitors.

5. Construction
Current Collector
Electrolyte
Separator
Porous electrode
+ _
Ultracapacitors consist of a porous electrode, electrolyte,
and a current collector (metal plates).

6. Continue…..
• There is a membrane, which separates, positive and
negative plates is called separator.
• The following diagram shows the ultracapacitors module
by arranging the individual cell.
C
1
C
2
C
3
C
4
C
5
Ultracapacitor stack
+
--

7. Working
• There are two carbon sheet separated by separator.
• The geometrical size of carbon sheet is taken in such a
way that they have a very high surface area.
• The highly porous carbon can store more energy than
any other electrolytic capacitor.
• When the voltage is applied to positive plate, it attracts
negative ions from electrolyte.
• When the voltage is applied to negative plate, it attracts
positive ions from electrolyte.
• Therefore, there is a formation of a layer of ions on the
both side of plate. This is called ‘Double layer’
formation.

8. Continue…
• For this reason, the ultracapacitors can also be called
Double layer capacitor.
• The ions are then stored near the surface of carbon.
• The distance between the plates is in the order of
angstroms.
• According to the formula for the capacitance,
Dielectric constant of medium X area of the plate
Capacitance = -------------------------------------------------------------------
Distance between the plates

9. Continue….
• Ultracapacitors stores energy via electrostatic charges
on opposite surfaces of the electric double layer.
• They utilize the high surface area of carbon as the
energy storage medium, resulting in an energy density
much higher than conventional capacitors.
• The purpose of having separator is to prevent the
charges moving across the electrodes.
• The amount of energy stored is very large as compared
to standard capacitor because of the enormous surface
area created by the (typically) porous carbon electrodes
and the small charge separation (10 angstroms) created
by the dielectric separator.

10. Diagram shows the formation of double layer
----
----
----
----
----
----
++
++
++
++
+
+








+
+
+
+
+
+
Electrolyte
Separator
Electric double layer
▬ +

11. Types of Ultracapacitors

12. Double-layer capacitors
• Electrochemical double-layer capacitors (EDLCs) are
constructed from two carbon-based electrodes, an
electrolyte, and a separator.

13. Continue….
• EDLCs store charge electrostatically and there is no transfer of
charge between electrode and electrolyte.
• EDLCs utilize an electrochemical double-layer of charge to store
energy. As voltage is applied, charge accumulates on the electrode
surfaces.
• These achieve very high cycling stabilities.
• The subclasses of EDLCs are distinguished primarily by the form of
carbon they use as an electrode material.
• Different forms of carbon materials that can be used to store charge
in EDLC electrodes are activated carbons, carbon aerogels, and
carbon nanotubes.

14. Pseudocapacitors
• In contrast to EDLCs, which store charge electrostatically,
pseudocapacitors store charge Faradically through the transfer of
charge between electrode and electrolyte. This is accomplished
through reduction-oxidation reactions.
• Faradic processes may allow pseudocapacitors to achieve greater
capacitances and energy densities than EDLCs. There are two
electrode materials that are used to store charge in
pseudocapacitors, conducting polymers and metal oxides.

15. Hybrid capacitors
• Hybrid capacitors attempt to exploit the relative advantages and
mitigate the relative disadvantages of EDLCs and pseudocapacitors
to realize better performance characteristics.
• Utilizing both Faradic and non-Faradic processes to store charge,
hybrid capacitors have achieved energy and power densities greater
than EDLCs without the sacrifices in cycling stability and affordability
that have limited the success of pseudocapacitors.
• Research has focused on three different types of hybrid capacitors,
distinguished by their electrode configuration: composite,
asymmetric, and battery-type respectively.

16. Comparison with Battery and
Conventional Capacitor

17. • Long life: It works for large number of cycle without wear
and aging.
• Rapid charging: it takes a second to charge completely.
• Low cost: it is less expensive as compared to
electrochemical battery.
• High power storage: It stores huge amount of energy in a
small volume.
• Faster release: Release the energy much faster than
battery.
Advantages

18. •They have Low Specific Energy.
• Individual cell shows low voltage.
• Not all the energy can be utilized during discharge.
• They have high self-discharge as compared to battery.
• Voltage balancing is required when more than three
capacitors are connected in series.
Disadvantages

19. • They are used in electronic applications such as cellular
electronics, power conditioning, uninterruptible power
supplies (UPS).
• They used in industrial lasers, medical equipment.
• They are used in electric vehicle and for load leveling to
extend the life of batteries.
• They are used in wireless communication system for
uninterrupted service.
• There are used in VCRs, CD players, electronic toys,
security systems, computers, scanners, smoke detectors,
microwaves and coffee makers.
Applications

20. Conclusion
• Ultracapacitors may be used wherever high power delivery or
electrical energy storage is required. Therefore numerous
applications are possible.
• In particular, ultracapacitors have great potential for applications
that require a combination of high power, short charging time, high
cycling stability, and long shelf life.
• Thus, ultracapacitors may emerge as the solution for many
application-specific power systems.
• Despite the advantages of ultracapacitors in these areas, their
production and implementation has been limited to date. There are
a number of possible explanations for this lack of market
penetration, including high cost, packaging problems, and self-
discharge.