dr. pramod k singh sharda university, g. noida, india e mail: [email protected]

M. Tech III

www.materialsresearchlab.netSHARDA UNIVERSITY

Dr. Pramod K Singh

Sharda University, G. Noida, India

E mail: [email protected]

Smart Materials in Renewable Devices Smart Materials in Renewable Devices

http://pramodkumarsingh.weebly.com

mailto:[email protected]

http://pramodkumarsingh.weebly.com/

M. Tech III


Syllabus7.01 SMDXXX.A Unit A Materials- Basic Concepts

7.02 SMDXXX.A1 Unit A Topic 1 Classification of Materials, Bonding in solids

7.03 SMDXXX.A2 Unit A Topic 2 Crystal structure, Bravais lattice, Miller Indices

7.04 SMDXXX.A3 Unit A Topic 3 Imperfections of crystals

7.05 SMDXXX.B Unit B Dielectrics, Superconductors and Magnetic Materials

7.06 SMDXXX.B1 Unit B Topic 1 Dielectic materials and their properties

7.07 SMDXXX.B2 Unit B Topic 2 Superconductors and their applications

7.08 SMDXXX.B3 Unit B Topic 3 Magnetic materials and their properties

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Syllabus7.09 SMDXXX.C Unit C Composite & Nanocomposite materials

7.10 SMDXXX.C1 Unit C Topic 1 Introduction of composite and Nanocomposite materials

7.11 SMDXXX.C2 Unit C Topic 2 Metal-Ceramic nanocomposite / Nanobiocomposites

7.12 SMDXXX.C3 Unit C Topic 3 Polymer based nanocomposites

7.13 SMDXXX.D Unit D Characterization Techniques

7.14 SMDXXX.D1 Unit D Topic 1 X-ray diffraction

7.15 SMDXXX.D2 Unit D Topic 2 UV-Visible spectroscopy

7.16 SMDXXX.D3 Unit D Topic 3 Infrared spectroscopy

7.17 SMDXXX.E Unit E Devices

7.18 SMDXXX.E1 Unit E Topic 1 Devices for energy conversion

7.19 SMDXXX.E2 Unit E Topic 2 Storage Devices

7.20 NSTXXX.E3 Unit E Topic 3 Sensors and Microelectronic devices

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Marks Distribution

•Assignment

•Test

•Presentation

•Project/Att.

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Application: Super Capacitors/DSSC

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Materials

Introduction

Principle, construction and working of Ultracapacitor

Advantage, disadvantage and application

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Super Capacitor• Capacitor is a device to store the charge in an electric circuit.

•Capacitor is made up of two conductorsseparated 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.

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Ultracapacitor• The electron storing capacity of capacitor is measured in Farads

•1 farad is approximately the charge with 6,280,000,000,000,000,000 electrons.

Definition:Ultracapacitors can be defined as a energy storage device that stores energy electrostatically by polarising an electrolytic solution.

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Super Capacitor/Ultra Capacitor

• 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 degredation.

• Ultracapacitors are also known as Double-layer capacitors/ Supercapacitors.

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

Current Collector

Electrolyte

Separator

+

Principle, construction and working

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Supercapacitor Construction• Ultracapacitor consist of a porous electrode, electrolyte and a current collector (metal plates). • There is a membrane, which separates, positive and negative plated is called separator. • The following diagram shows the ultracapacitor module by arranging the individual cell

C1

C2

C3

C4

C5

Ultracapacitor stack

+ --

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Super Capacitor; Working Principle

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.

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ULTRA CAPACITOR

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• 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

ULTRA CAPACITOR

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• 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.

• The amount of energy stored is very large as compared to a standard capacitor

• because of the enormous surface area created by the (typically) porous carbon electrodes &the small charge separation (10 A0 ) created by dielectric separator

ULTRA CAPACITOR

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------------------------

++++++++

+

+

+

+

+

++

+

Electrolyte

Separator

Electric double layer

▬ +

Diagram shows the formation of double layer

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• 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.

Super Capacitor: Advantage

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• 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.

Super Capacitor: Disadvantage

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• 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.

Super Capacitor: Applications

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Solid State Solar Cell (SSSC)* Different conduction mechanism* Charge separation ☞ to form M-S (Schottky) junctions Advantage High efficiency (~24 %)Disadvantage High cost

• both type of semiconductors are prepared from highly pure semiconductor by a severely controlled doping process

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Classification & Principle

Inorganic Solar Cell

Organic Solar Cell

Dye Sensitized Solar Cell

Si: mono, poly and amorphous-crystallineGaAs, InP, CdTeGaAs/Ge

Conducting polymer - fullereneConducting polymer - conducting polymerOrganic polymer - nanoinorganic materials

☞Basic Principle charge separation at the junction (interface) of two materials of different conduction

mechanism

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Components of DSSC

I-

I3-

External Circuit

-TCO

conducting glass

Crystalline TiO2

Sensitizer dye

Polymer electrolyte

-

1. TiO2 electrode with Dye

2. Electrolyte with redox couple

3. Counter electrode

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TiO2

I-/I3-

(Dye)(Electrolyte)

e-

e-

Promising Candidate for Next Generation Promising Candidate for Next Generation Solar cell !?Solar cell !?

Low CostLow CostGood RecyclabilityGood RecyclabilityWide VariationWide VariationHigh Energy Conversion EfficiencyHigh Energy Conversion Efficiency

(Semiconductor)

Electrolyte

Anode Cat

hode

( TC

O G

lass

）

TC

O G

lass

)

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Role of redox couple in DSSC

* boys as electron

* filled boat as iodide

* empty boat as triiodide

Nam- Gyu Park and K. Kim, Phys. Stat. Sol. (a), 205 (2008) 1895

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DSSC: Electrolyte

Electrolyte in DSSC

re-reduction of the oxidized dye

transferring ion

oxidized by contact with electrode

Liquid Electrolytes Ion Conducting Gels

leakage

evaporation of the solvent

leakage

evaporation of the solvent

volatile liquid encapsulated

in the gel pores

Alternative

Polymer Electrolytes

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Preparation of Polymer Electrolytes with IL

1. Mixed PEO, KI and I2 in acetonitrile to get PEO:KI/I2 polymer electrolyte

2. Added ionic liquid in the polymer electrolyte solution

3. Stirred continuously

4. Cast electrolyte solution in polypropylene dishes

5. Dried these films under vacuum to remove the traces of solvent

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Preparation of DSSC with Polymer Electrolytes/ IL

6. Prepared nanocrystalline TiO2 electrode by chemical sintering method and sensitized (24 hrs.) into Dye solution.

7. Casted polymer/IL solution (~400 μL)on TiO2 surface followed two step cast method.

8. Sandwitched electrolyte solution between TiO2 and counter electrode.

9. Dried the cell under vacuum (~2 days) to remove the traces of solvent.

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Fabrication of DSSC with PE/IL as electrolyte

FTO glass

30x30 cm2

Cut

Wash

2x1.5 cm2 Blocking layer coating500 0C for 30 min in furnace

Pt layer coating400 0C for 30 min in furnace

Two Scotch tapeThickness ~ 50

㎛

TiO2 electrode

CE

TiO2 paste using Doctor blade

Sintering in furnace 500 0C for 30 min

Dye Sensitization

(~ 24 hrs]

PE/IL casting (2 step)

TiO2 electrode with Dye

TiO2 electrode

CE

TiO2 sensitized with dye

PE/IL solid electrolyte

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• SEM (for TiO2 surface and particle size)• TEM• XRD

• Impedance spectroscopy (for σ)

• DSC (for check crystallinity)

• J-V Characteristics (to see solar cell performance)

Characterizations

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SEM Measurementmesoporous TiO2 layer (30 min. sintering at 5000 C)

cross sectional view top view

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Pore

Scrapped TiO2 powder TEM:*TiO2 particle size ~ 25 nm

*Pore diameter ~10-15 nm

*Pore wall mostly crystalline

TEM Measurement

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XRD Measurement

20 30 40 50 60

Inte

nsity

(a.u

.)

2

A (Anatase TiO2)S (Substrate FTO)

SA

S

SA

S

A ASA

S

☞*A (Anatase TiO2 peaks) at 25.30, 38.60, 480, 53.90, 55.10

(101),(112),(200),(105),(211)

[JCPDS# 211272] **Average size(TiO2) ~26 nm

(Scherrer Formula)

☞ S (Substrate FTO peaks) at 26.60, 33.90, 430, 51.70, 54.80

(110),(101),(210),(211),(220)

[JCPDS# 211250]

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Polymer Electrolyte Film: Polymer Electrolyte Film: FabricationFabrication

PEO in Methanol Added KI & I2

COMPLEXATIONStirred 24 hrs. in a

Beaker at 50 0 C

Clear PEO:KI/I2

solution.

Ionic LiquidThoroughMixing

Pour in Petridish

&Solution casting

Dry Polymer Film

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Conductivity Measurement

Impedance Spectroscopy (for σ)

σ = G X L / A

G: conductance of the sample

L: thickness of the sample

A: the area of the sample

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Electrical Conductivity:PEO:KI/I2+EMImSCN

Composition σ (S/cm)

PEO:KI/I2 (EO/K=17) 8.80 x 10-6

PEO:KI/I2 + 20 wt% IL 1.39 x 10-5

PEO:KI/I2 + 40 wt% IL 1.90 x 10-5

PEO:KI/I2 + 60 wt% IL 5.99 x 10-4

*PEO:KI/I2 + 80 wt% IL 7.62 x 10-4

* After that composition film was not stable

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Electrical conductivity

PEO:KI/I2+EMImSCN (IL)

doping of IL increased σ

attained max. σ at 80 wt%IL concentration

After 80 wt% IL concentration,we could not get free standingpolymer electrolyte film

0 20 40 60 80

1.0 x10-5

1.0 x10-4

1.0 x10-3

(S

/cm

)

IL amount (wt%)

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XRD

15 20 25 30 35 40

Inte

nsity

2 theta

PEO/KI/I2/IL80wt% PEO/KI/I2 I2 KI

a

b

c

d

• complete complexation

• reduced in crystallinity

no additional peaks of KI in c

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(PEO crystalline peaks 19o and 23.1o)

The Intensity of PEO crystalline peaks

decreased after adding KI and IL

► Incorporation of IL reduced crystallinity

► no new peaks appeared in (PEO:KI/I2)+80 wt% IL

15 20 25 30 35 40

Inte

nsity

2 theta

a

b

c

XRD: Effect of IL

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DSC : Crystallinity

20 30 40 50 60 70 80 90

c

b

Hea

t Flo

w (W

/g)

Temperature (0C)

a

Crystallinity χ (%) = ∆Hf / ∆Hf0

∆Hf0 of 100 % crystalline PEO film

was assumed 188.1J/g. [Polymer., 37, 5109 (1996)]

Composition Tm (0C)

∆Hf

(J/g) χ (%)

a. PEO:KI/I2 (EO/K = 17) 60.34 86.38 45.94

b. PEO:KI/I2 + 40 wt% IL 51.71 29.06 15.45

c. PEO:KI/I2 + 80 wt% IL 45.00 16.18 8.60

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J-V Characteristics

Jsc(mA/cm2)

Voc (V) FF (%) η (%)

a 0.22 0.74 77.4 0.1

b 0.32 0.67 56.0 0.1

c 0.78 0.65 68.3 0.3

d 1.88 0.63 50.7 0.6

0.0 0.2 0.4 0.6 0.80.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

a

b

d

c

Cur

rent

den

sity

(m

A/c

m2 )

Voltage (V)

(using stable polymer films as electrolytes)

(PEO:KI/I2) + x wt% IL (a) x = 0, (b) x = 20, (c) x = 60, (d) x = 80

M. Tech III


dr. pramod k singh sharda university, g. noida, india e mail: [email protected]

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