03-09-2014, 03:50 PM
SUPERCAPACITOR
[attachment=67593]
What is Capacitor?
A capacitor (originally known as condenser) is
a passive two-terminal electrical component used to
store energy in an electric field.
When there is a potential difference (voltage) across the
conductors, a static electric field develops across the
dielectric, causing positive charge to collect on one plate
and negative charge on the other plate. Energy is stored
in the form of electrostatic field.
What is Supercapacitor
A supercapacitor or ultracapacitor is an
electrochemical capacitor that has an
unusually high energy density when compared
to common capacitors. They are of particular
interest in automotive applications for hybrid
vehicles and as supplementary storage for
battery electric vehicles
History
The first supercapacitor based on a double layer
mechanism was developed in 1957 by General Electric
using a porous carbon electrode [Becker, H.I., “Low
voltage electrolytic capacitor”, U.S. Patent 2800616, 23
July 1957].
It was believed that the energy was stored in the carbon
pores and it exhibited "exceptionally high capacitance",
although the mechanism was unknown at that time. It
was the Standard Oil Company, Cleveland (SOHIO) in
1966 that patented a device that stored energy in the
double layer interface [Rightmire, R.A., “Electrical energy
storage apparatus”, U.S. Patent 3288641, 29 Nov 1966.].
Advantages relative to Batteries:
Very high rates of charge and discharge.
Little degradation over hundreds of
thousands of cycles.
Good reversibility.
Low toxicity of materials used.
High cycle efficiency (95% or more).
Technology
Carbon nanotubes and certain conductive
polymers, or carbon aerogels, are practical for
supercapacitors. Carbon nanotubes have
excellent nanoporosity properties, allowing tiny
spaces for the polymer to sit in the tube and act as
a dielectric. Some polymers (eg. polyacenes)
have a redox (reduction-oxidation) storage
mechanism along with a high surface area. MIT's
Laboratory of Electromagnetic and Electronic
Systems (LEES) is researching using carbon
nanotubes [1]
Disadvantage
The amount of energy stored per unit weight is
considerably lower than that of an electrochemical
battery (3-5 W.h/kg for an ultracapacitor compared to
30-40 W.h/kg for a battery). It is also only about
1/10,000th the volumetric energy density of gasoline.
The voltage varies with the energy stored. To effectively
store and recover energy requires sophisticated
electronic control and switching equipment.
Has the highest dielectric absorption of all types of
capacitors.
[attachment=67593]
What is Capacitor?
A capacitor (originally known as condenser) is
a passive two-terminal electrical component used to
store energy in an electric field.
When there is a potential difference (voltage) across the
conductors, a static electric field develops across the
dielectric, causing positive charge to collect on one plate
and negative charge on the other plate. Energy is stored
in the form of electrostatic field.
What is Supercapacitor
A supercapacitor or ultracapacitor is an
electrochemical capacitor that has an
unusually high energy density when compared
to common capacitors. They are of particular
interest in automotive applications for hybrid
vehicles and as supplementary storage for
battery electric vehicles
History
The first supercapacitor based on a double layer
mechanism was developed in 1957 by General Electric
using a porous carbon electrode [Becker, H.I., “Low
voltage electrolytic capacitor”, U.S. Patent 2800616, 23
July 1957].
It was believed that the energy was stored in the carbon
pores and it exhibited "exceptionally high capacitance",
although the mechanism was unknown at that time. It
was the Standard Oil Company, Cleveland (SOHIO) in
1966 that patented a device that stored energy in the
double layer interface [Rightmire, R.A., “Electrical energy
storage apparatus”, U.S. Patent 3288641, 29 Nov 1966.].
Advantages relative to Batteries:
Very high rates of charge and discharge.
Little degradation over hundreds of
thousands of cycles.
Good reversibility.
Low toxicity of materials used.
High cycle efficiency (95% or more).
Technology
Carbon nanotubes and certain conductive
polymers, or carbon aerogels, are practical for
supercapacitors. Carbon nanotubes have
excellent nanoporosity properties, allowing tiny
spaces for the polymer to sit in the tube and act as
a dielectric. Some polymers (eg. polyacenes)
have a redox (reduction-oxidation) storage
mechanism along with a high surface area. MIT's
Laboratory of Electromagnetic and Electronic
Systems (LEES) is researching using carbon
nanotubes [1]
Disadvantage
The amount of energy stored per unit weight is
considerably lower than that of an electrochemical
battery (3-5 W.h/kg for an ultracapacitor compared to
30-40 W.h/kg for a battery). It is also only about
1/10,000th the volumetric energy density of gasoline.
The voltage varies with the energy stored. To effectively
store and recover energy requires sophisticated
electronic control and switching equipment.
Has the highest dielectric absorption of all types of
capacitors.