ULTRACAPACITOR

Presented by:

SRIDHAR MOHARANAROLL NO-14MET020

RAVENSHAW UNIVERSITYDEPT. OF ETC

OVERVIEWINTRODUCTIONBASIC DESIGNPRINCIPLEDIFFERENT STYLECONSTRUCTIONWORKINGTAXONOMYBATTERY VS. SUPERCAPACITORADVANTAGESDISADVANTAGES

INTRODUCTION

Ultracapacitors is a modern electric energy storage devices with very high capacity and a low internal resistance.

Differ in constructional features with respect to simple capacitors.Has ability to store tremendous charge.Capacitance ranges up to 5000f!Also called super capacitor or double-layered capacitor.No chemical reaction involved.Much more effective at rapid, regenerative energy storage than

chemical batteries Invented by engineers at standard oil,1966.

BASIC DESIGN OF ULTRACAPACITOR

Typical Parts:

1)Power Source2)Collector3)Polarized Electrode4)Double Layer5)Electrolyte having +ve

& -ve ions6)Separator

Energy is stored in ultracapacitor by polarizing the electrolytic solution. The charges are separated via electrode –electrolyte interface.

Current Collector Electrolyte

Separator

Porous electrode

+ _ One layer forms on the charged electrode, and the other layer is

comprised of ions in the electrolyte. The specific capacitance of such a double-layer given by

C/A =/4

C is capacitance, A is surface area, is the relative dielectric constant of the medium between the two layers (the electrolyte), and is the distance between the two layers (the distance from the electrode surface to the centre of the ion layer).

PRINCIPLE

DIFFERENT STYLES DESIGN ULTRACAPACITORS

Flat style used for mobile components.

Typical button capacitor for PCB mounting for memory backup.

Radial style capacitors for PCB mounting in industrial applications.

CONSTRUCTION

with activated carbon electrode :

with stacked electrodes:

1. Positive electrode,

2. Negative electrode,

3. Separator,

1. Terminals, 2. Safety vent, 3 .Sealing disc, 4. Aluminum can, 5. Positive pole,

6. Separator, 7. Carbon electrode, 8. Collector, 9. Carbon electrode, 10. Negative pole

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.

WORKING

Therefore, there is a formation of a layer of ions on the both side of plate. This is called ‘Double layer’ formation.

For this reason, the ultracapacitor 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

Ultracapacitor stores energy via electrostatic charges on opposite surfaces of the electric double layer.

The purpose of having separator is to prevent the charges moving across the electrodes.

TAXONOMY OF ULTRACAPACITOR

ELECTROCHEMICAL DOUBLE-LAYER CAPACITORS

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

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 as follows:

1. Activated Carbon

2. Carbon fiber cloth

3. Carbon Aerogel

4. Graphite

5. Carbon nanotubes

PSEUDOCAPACITORSPseudocapacitance is archived by faradic electron charge transfer with

redox reactions, intercalation or electrosorption.In edlc electodes is relatively low.Pseudocapacitance electrodes with double layer capacitance do not exist.

HYBRID CAPACITORSSuch as the lithium-ion capacitor, use electrodes with

differing characteristics Exhibiting mostly electrostatic capacitance.

Exhibiting mostly electrochemical capacitance. Activated carbon use as cathode. LIC has a higher output voltage, similar to power densities.

ULTRACAPACITOR Hegher power density. Much faster charge and

discharge rate. Environmentally friendly. Extremly low internal

resistance or esr. High effi=icience (97-

98%). Over a million charge-

discharge cycle.

BATTERIES Have higher energy density. Typically 200-1000 charge-

discharge cycle. Contain highly reactive and

hazardous chemicals. Negative effected by low

tempetue.

RECHARGEABLE BATTERIES VS. ULTRACAPACITORS

Ragone plot

SPECIFIC POWER AGAINST SPECIFIC ENERGY performance improvement for

an ultracapacitor is shown in a graph termed as “Ragone plot.

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.

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. Wide working temperture: Temperature range( from -45 to

55 degree centi.)

ADVANTAGES

They have Low energy density

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

APPLICATIONS FOR SUPERCAPACITORS

• Back up for uninterruptable power supplies (UPS).

• Light weight power supplies for small aircraft.

• Provide short duration power for various vehicle systems such as breaking or steering.

• Used to absorb power during short periods of generation such as regenerative braking.

• Extend range and battery life in hybrid electric vehicles (HEV).

Backup for actuators in wind turbine pitch system.

Street lights containing LED and superchapacitors for storage.

Ultracapacitors can be used to supplement batteries in diesel railroad locomotives.

Buses, racing cars, hybrid electrical vehicles and in aerial lift.

THANK YOU