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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 Smart Materials in Renewable Devices Smart Materials in Renewable Devices
http://pramodkumarsingh.weebly.com
M. Tech III
www.materialsresearchlab.netSHARDA UNIVERSITY
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
M. Tech III
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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
M. Tech III
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Marks Distribution
•Assignment
•Test
•Presentation
•Project/Att.
M. Tech III
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Application: Super Capacitors/DSSC
M. Tech III
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Materials
Introduction
Principle, construction and working of Ultracapacitor
Advantage, disadvantage and application
M. Tech III
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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.
M. Tech III
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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.
M. Tech III
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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.
M. Tech III
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Principle
Energy 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
M. Tech III
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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
+--
M. Tech III
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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
M. Tech III
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------------------------
++++++++
+
+
+
+
+
++
+
Electrolyte
Separator
Electric double layer
▬ +
Diagram shows the formation of double layer
M. Tech III
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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-crystalline
GaAs, InP, CdTe
GaAs/Ge
Conducting polymer - fullerene
Conducting polymer - conducting polymer
Organic 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 Cost
Good RecyclabilityGood Recyclability
Wide VariationWide Variation
High Energy Conversion EfficiencyHigh Energy Conversion Efficiency
(Semiconductor)
Electrolyte
Anode Cat
hod
e( T
CO
Gla
ss)
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 coating
500 0C for 30 min in furnace
Pt layer coating400 0C for 30 min in furnace
Two Scotch tape
Thickness ~ 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 Measurement
mesoporous 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
nsi
ty (
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
COMPLEXATION
Stirred 24 hrs. in a
Beaker at 50 0 C
Clear PEO:KI/I2
solution.
Ionic LiquidThorough
Mixing
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 standing
polymer 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
Heat
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)]
CompositionTm
(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 0.8
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
a
b
d
c
Cu
rren
t d
ensi
ty (
mA
/cm
2 )
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
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