Introduction about Super-capacitor and Significance of Hybrid supercapacitor

1. Hybrid nanocomposite electrode for
supercapacitor application

2. CONTENT
 Introduction to capacitors
 Why supercapacitor?
 Principle and working of supercapacitor
 Classification of supercapacitor
 Why they can store more energy
 Hybrid supercapacitor

3. Introduction to capacitors
THE CAPACITOR
 Energy stored in an electric field between two conduction plates
 Charges and discharges quickly
 Long life, very low cycling losses
Figure 1. A capacitor Figure 2. A common capacitor design

4. Why supercapacitor?
The two primary attributes of a capacitor are its energy
density and power density.
Conventional capacitors have relatively high power
densities, but relatively low energy densities when
compared to electrochemical batteries and to fuel cells.
That is, a battery can store more total energy than a
capacitor, but it cannot deliver it very quickly, which means
its power density is low.
 To overcome this disadvantage, Supercapacitors are
introduced.

5. Principle and working of supercapacitor
Principle
Energy is stored in supercapacitor by polarizing the
electrolytic solution. The charges are separated via electrode -
electrolyte interface
Working
• There are two electrodes separated by separator.
• 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.
• The ions are then stored near the surface of electrode.

6. • The distance between the plates is in the
order of angstroms.
• Supercapacitor stores energy via
electrostatic charges on opposite surfaces
of the electric double layer.
• They utilize the high surface area of
electrode 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 a standard capacitor because
of the enormous surface area created by the
electrodes and the small charge separation
(10 angstroms) created by the dielectric
separator
Diagram shows the
formation of double
layer

7. Classification of Supercapacitor

8. Why they can store more energy
 Store energy by adsorbing electrolyte ions onto the
surface of the electrode (EDLC)
 Rely on redox reactions that take place at the
electrode (Pseduocapacitor)
 A combination of EDLC and Pseudocapacitors
implies optimizes power density of EDLC with energy
density of Pseudocapacitor (hybrid capacitor)
Based on this, designing of hybrid capacitor is more
valuable for storage.

9. Electrode material selection for hybrid supercapacitor
As shown in classification, hybrid capacitor may be symmetric or
asymmetric composite for supercapacitor.
Symmetric supercapacitor contains same material from the group
of EDLC (e.g: Carbon tubes/graphite) or from the group of
Pseduocapacitance (e.g.: Metal oxide/Conducting polymer)
 Asymmetric composite supercapacitor will be prepared by
combination of anyone of the material from EDLC and another one
from Pseudocapacitor material.
Hybrid supercapacitor
Electric Double-Layer Capacitors + Pseudocapacitors = Hybrid capacitor