SUPERCAPACITORS

Made By:

Amit Soni

Int. PhD NCU

S0626

Outline

CapacitorBasic design and terminologySupercapacitorHistory of SupercapacitorClassification of SupercapacitorsElectrical Double layer capacitorsPseudocapacitorHybrid CapacitorBasic DesignConstructionWorking Technology usedWhy these substances used ?FeaturesComparisonApplications Advantages & DisadvantagesConclusionReference

Capacitor

1. A capacitor (condenser) is a passive two-terminal electrical component used to store energy in its electric field.

2. When a capacitor is attached across a battery, an electric field develops across the dielectric, causing positive charge +Q to collect on one plate and negative charge −Q to collect on the other plate.

Basic design and terminology in

Capacitors

Capacitance: Capacitance is defined as the ratio of the

electric charge on each conductor to the potential

difference between them. C=dQ/dV (S.I. unit is Faraday)

Energy Storage: 1/2CV2

Supercapacitors

➢Also known as Electrical double layer capacitors or Ultracapacitors

➢In general, a capacitor is a device which is used to store the charge in

an electrical circuit. Basically a capacitor is made up of two conductors

separated by an insulator called dielectric.

➢Supercapacitors are modern electric energy storage devices with very

high capacity and a low internal resistance.

➢Supercapacitors utilise high surface area electrode materials and thin

electrolytic dielectrics to achieve high capacitance.

➢This allows for energy densities greater than those of conventional

capacitors and power densities greater than those of batteries. As a

result, these may become an attractive power solutions for an

increasing number of applications

➢The capacitance range is From 100 Farad to 5000Farad

HISTORY OF SUPERCAPACITORS

● In 1950s General Electric Engineers started experimenting components using porous carbon electrodes for fuel cells and rechargeable batteries.

● In 1957 H. Becker developed a "Low voltage electrolytic capacitor with porous carbon electrodes".

● That capacitor came to known as Supercapacitor as it stored very high amount of energy.

● In 2013 Indian-US girl “Esha Khare”invented a new electrode for supercapacitor

Classification of Supercapacitors

Electrical Double layer Capacitors

• EDL formed with electrode and electrolyte with solvent molecules between as dielectric.

• Store energy by adsorbing electrolyte ions onto the surface of the electrode

• Fast acting. Low energy potential, charge confined to surface

(a) simplified EDL

capacitor [4]

(b)

An example of EDLC

using highly porous

carbon as a

dielectric [6]

ba

Pseudocapacitor•Depend on redox reactions that take place at the electrode

•Electrode materials typically made up of transition metals,

conducting polymers, or compound with O and N functional

groups

•Higher Energy density but lower cycling life

Pseudocapacitor [4]

• A combination of EDLC and

pseudocapacitor. Optimises power

density of EDLC with energy

density of pseudocapacitor

• One common example is the Li ion

capacitor which is a current leader

in the field

• Research has focused on three

different types of hybrid capacitors,

distinguished by their electrode

configuration: composite,

asymmetric, and battery-type

respectively

A hybrid capacitor EDLC comparison [7]

Specific Energy and Power comparison [4]

Hybrid capacitor

●Electrochemical capacitors (supercapacitors) consist of two electrodes separated by an ion permeable membrane (separator), and an electrolyte electrically connecting both electrodes. When the voltage is applied, ions in the electrolyte form electric double layers of opposite polarity to the electrode's polarity.

●For example, positive electrodes will have a layer of negative ions and negative electrodes will have a layer of positive ions.

Basic Design

● Supercapacitors are constructed with two metal foils, each coated with an electrode material such as activated carbon.

● The electrodes are kept apart by an ion-permeable membrane (separator) used as an insulator to protect the electrodes against short circuits.

● The construction is subsequently rolled or folded into a cylindrical or rectangular shape and is packed in an aluminium can.

CONSTRUCTION

4. Aluminium can5.Positive pole6.Separator7.Carbon electrode8. Collector9.Carbon electrode10. Negative pole

1.Positive electrode2. Negative electrode3. Separator

● When a voltage is applied, the ions are

attracted to the electrode with the

opposite charge, where they cling

electrostatically to the pores in the

carbon.

● At the low voltages used in

ultracapacitors, carbon is inert and does

not react chemically with the ions

attached to it. Nor do the ions become

oxidized or reduced, as they do at the

higher voltages used in an electrolytic

cell.

● As the effective area where ions are

stuck is much larger, appreciably high

value of capacitance is obtained.

WORKING OF SUPERCAPACITOR

●Carbon nano tubes, carbon aerogels, Graphene based materials are used for supercapacitors plates or electrodes.

●Sodium perchlorate (NaClO4) or lithium perchlorate (LiClO4) are used as electrolytes.

●Polyacrylonitrile(C3H3N)n is used as a separator(thickness 0.3-0.8 nm).

●Aluminium as a packing component.●Carbon Nanotubes : Depending on their geometry, can be excellent conductors .

Thus they can supply more power than

ultracapacitors outfitted with activated carbon.

Their structure makes them less chemically reactive.

TECHNOLOGY USED

NANOTUBES STRUCTURES

● Electrodes:-1)Carbon nanotubes greatly improve capacitor performance, due to the highly wettable

surface area and high conductivity.

2)Highly porous.

● Electrolytes:-1) Wide working temperature (-900c to 4000c).

2)Non flammable and low toxic.

3)Non-corrosive to electrode & packing components.

● Separator:-

1) Unique tensile strength (103MegaPascals).

2)Electrical conductivity (1.5x104 S/m).

3)Not degraded easily.

why these substances used?

COMPARISON WITH BATTERY &

CONVENTIONAL CAPACITORS

The performance

improvement for an

Supercapacitor is shown

in a graph termed as

“Ragone plot.” This type

of graph presents the

power densities of

various energy storage

devices, measured

along the vertical axis,

versus their energy

densities, measured

along the horizontal

axis. Ultracapacitors

occupy a region

between conventional

capacitors and batteries

. Despite greater

capacitances than

conventional capacitors,

ultracapacitors have yet

to match the energy

densities of mid to high-

end batteries and fuel

cells.

COMPARISON(Contd..)

COMPARISON WITH BATTERIES

⦿Very high rates of charge and discharge.Supercapacitor charges within secondswhereas batteries takes hours.

⦿Little degradation over hundreds of thousands of cycle Batteries degrade withina few thousand charge-discharge cycles. Ultracapacitors can have more than300,000 charging cycles, which is far more than a battery can handle.

⦿Can effectively fulfil the requirement of high current pulses that can kill abattery if used instead Batteries fail where high charging discharging takes placewhereas Supercapacitor fares extremely well.

⦿Ultracapacitors are much more effective at rapid, regenerative energy storagethan batteries.

19

Flat style of super capacitor used for mobile devices.

Typical knob capacitorFor PCB mounting used for memory backup

Radial style of lithium-Ion capacitor for PCB mounting used for industrial applications

20

missiles

• Used in Diesel engine start up in submarines & tanks.

• Used to recover braking energy in HEV & modern trains and deliver the same during accelerating periods.

• Used as backup energy source for GPS guided missiles.

Applications:

⦿In 2001 and 2002, VAG, the public transport operator inNuremberg, Germany tested a bus which used a diesel-electricdrive system with ultracapacitors.

⦿Heavy transportation vehicles - such as trains, metros - placeparticular demands on energy storage devices. Such devicesmust be very robust and reliable, displaying both longoperational lifetimes and low maintenance requirements.

⦿Maxwell Technologies solved these issues with itssupercapacitor HTM125 module for braking energyrecuperation and torque assist systems in trains, metrotransportation vehicles. Ultracapacitors can deliver the peakpower for acceleration and store part of vehicle’s kinetic energyduring deceleration.

APPLICATIONS (Contd..)

APPLICATIONS(Contd..)

⦿China is experimenting with a new form of electric bus that runs

without powerlines using power stored in large onboard

ultracapacitors. A few prototypes were being tested in Shanghai in

early 2005. In 2006, two commercial bus routes began to use

supercapacitor buses.

⦿Esma-cap, Russia, developed two experimental vehicles. Electric bus

with 50 passengers capacity, maximum speed 20 km.h-1.Electric

truck with payload limit 1,000 kg, maximum speed 70 km.h-1. Proton

Power Systems has created the world's first triple hybrid Forklift

Truck, which uses batteries as primary energy storage and

ultracapacitors to supplement this energy storage solution.

⦿Delivering or accepting power during short-duration events is the

supercapacitor’s strongest suit.

ADVANTAGES

●High energy storage.

●Wide working temperature(-400c to 600c).

●Eco-friendly.

●Quick charging time.

●Maximum life cycle.

●High cycle efficiency (95%).

●High specific power up to 17 kW/kg.

●Extremely low internal resistance.

●Safe.

DISADVANTAGES

● Low energy density; usually holds 1/5 – 1/10 of a battery.

●Cannot use the full energy spectrum for some applications.

● The voltage varies with the energy stored.

●Have high self-discharge rate.

●Individual cells have low voltages, and so serial connections are needed to obtain higher voltages.

●Requires expert electronic control.

●Cannot be used in AC and high frequency circuits.

●High cost.

Conclusion

⦿Supercapacitors may be used wherever high power delivery orelectrical energy storage is required. Therefore numerous applicationsare possible.

⦿In particular, ultracapacitors have great potential for applications thatrequire a combination of high power, short charging time, high cyclingstability, and long shelf life.

⦿Thus, ultracapacitors may emerge as the solution for manyapplication-specific power systems.

⦿Despite the advantages of ultracapacitors in these areas, theirproduction and implementation has been limited to date. There are anumber of possible explanations for this lack of market penetration,including high cost, packaging problems, and self-discharge.

⦿WE CAN USE SUPERCAPACITORS AS BATTERIES , NONTOXICAND ECO-FRIENDLY

References:

[1]Marin S. Halper, James C. Ellenbogen, “Supercapacitors: A Brief Overview”, March 2006

[2]http://www.maxwell.com/pdf/uc/app_notes/ultracap_product_guide.pdf : last accessed on 25th October

[3]E.J.Dowgiallo & A.F.Bruke ‘’ Ultracapacitors for electric and hybrid vehicles: A technology update.’’

[4]wikipedia.org[5] Huang, Yi, Jiajie Liang, and Yongsheng Chen. “An Overview of the Applications of Graphene-Based Materials in Supercapacitors

[6] http://www.i2bf.com/companies/16/

[7]M. Jayalakshmi, K. Balasubramanian, “Simple Capacitors to Supercapacitors - An Overview”, Int. J. Electrochem. Sci., 3

[8] www.google.com/images

[9] B.E.Conway, ‘’Electrochemical Supercapacitors’’, chemical industry press.

[10] http://cssf.usc.edu//History/2013/Projects/S0912.pdf

Thank you