221 samta

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Presented by

Samita Thakur, O. P. Pandey, K. Singh

School of Physics & Materials Science

Thapar University, PatialaAt

IV th International Conference on Advances in Energy ResearchIndian Institute of Technology Bombay, Mumbai

Effect of Ca2+ substitution on the structural, thermal and

electrical properties of BiYO3 for SOFC applications

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Why Fuel Cells?

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We use energy every day. Energy is needed to operate machines, to heat and cool our homes and schools, to cook, to provide light and to take people from place to place.

Tuesday, April 11, 2023THAPAR UNIVERSITY, PATIALA 3

Coal

Petroleum

Natural Gas

Nuclear power plants

Conventional Energy sources

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Green House Emission

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Solutions to Energy Problem

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Biomass Energy

Wind Energy

Fuel Cells Hydraulic energy

Solar Energy

Non-conventional energy sources

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Fuel CellsA fuel cell is a device that

converts chemical energy into electrical energy, water, and heat through electrochemical reactions.

The voltage generated by a single cell is typically rather small (< 1 volt), so many cells are connected in series to create a useful voltage.

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Fuel cells operation

Hydrogen Oxygen

Water

2 2 2H H e

Heat

2 21/ 2 2 2 1O H e H O

Membrane(Nafion)Catalyst (Pt)

Anode (-)Catalyst (Pt)Cathode (+)

dc current

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Types of Fuel Cells

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Practical Applications of Fuel Cells


Auxi

liary

pow

er u

nits

(APU

for o

nboa

rd e

lect

ric d

eman

dCo

mbi

ned

heat

and

pow

er

(CHP

) for

smal

l bus

ines

s

Elec

tric

pow

er fo

r ho

useh

old

supp

ly

Secu

re p

ower

for d

ata

cent

re

Heav

y tra

nspo

rtati

on

prop

ellin

g fo

rce

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SOLI

D O

XID

E FU

EL C

ELLS

(SOFC

)

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Solid oxide fuel cells (SOFCs) are attracting attention due

to following reasons:

Higher efficiency

Negligible environmental pollution

No liquid electrolyte

Least material corrosion

Offers good fuel flexibility

Internal reformation of hydrocarbons fuels

Merits of SOFc

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Components of SOFC

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Working Principle of SOFC

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Limitations of SOFC

The high temperature limits applications of SOFC units and they

tend to be rather large

High operating temperature also enhance the degradation rate of materials

AssemblingMaintenance

Design Cost & choice of material

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(1)

Lowering of operating temperature

(2)

Increase the choices for materials selection

(3)

Lower the degradation of materials, cost and increase the durability

Lowering of operating temperature will also increase the resistance of the cell and reduces the overall output. So, there is need to develop new material s .

Remedies for the problems

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Motivation of the present work

The best known solid electrolytes for SOFC are ceramics with fluorite type

structure, materials based on zirconia and ceria. But its conductivity falls down

drastically below 800 °C. The major drawback associated with ceria based

electrolytes is the conversion of Ce4+ to Ce3+ under SOFC anodic conditions

(reducing atmosphere). This results in high electronic conduction and chemical

expansion

One class of materials that exhibits high oxide ion conductivity is based upon the

perovskite structure. Sr2+ doped LaInO3, LaYO3, LaGaO3 have been exploited as

electrolytes for their oxide ion conductivity with conductivity in the range of 10-3

S/cm.

Depending upon the above stated facts we have chosen Bi1-xCaxYO3 (x=0, 0.1) to

study its structural, thermal and electrical properties as electrolyte for SOFC

applications.

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Synthesis of Bi1-xCaxYO3 (x=0, 0.1)

Homogeneous mixture

Calcination at 750 0C

Pelletization and sintering at 800 0C

Characterization

X-ray Diffraction

Dilatometry TGA Scanning electron

microscopy

Ac impedance spectroscopy

Bi2O3 CaO Y2O3

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X-ray Diffraction


0

2000

4000

20 30 40 50 60 70 80

0

2000

4000

(b)

Inte

nsity

(cou

nts/

s)

2 (degree)

(a)

Figure 1: X-ray diffraction pattern of (a) BiYO3 (b) Bi0.9Ca0.1YO3.

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Differential scanning calorimetry/Thermogravimetric analysis


100 200 300 400 500 600 700 800

-0.1

0.0

0.1

0.2

0.3

Temperature (C)

Mic

rovo

lt (e

ndo-

dow

n)

99.2

99.6

100.0

Wei

ght (

%)

(b)

100 200 300 400 500 600 700 800

-0.3

0.0

0.3

0.6

Temperature (C)

Mic

rovo

lt (en

do-d

ow

n)

98.8

99.2

99.6

100.0

Wei

ght (%

)

(a)

Figure 2: DSC/TGA curve of (a) BiYO3 (b) Bi0.9Ca0.1YO3

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Thermal expansion coefficient


100 200 300 400 500 600 700 800

0.000

0.002

0.004

0.006

0.008

Temperature (C)

L/L

0

(a)

-3

0

3

6

9

(

10-6

C-1

)

100 200 300 400 500 600 700 800

0.000

0.002

0.004

0.006

0.008

Temperature (C)

L/L

0

(b)

0

3

6

9

12

(

10-6

C-1)

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Ac impedance spectroscopy


0 4000 8000 12000 16000

0

4000

8000

12000

Z''

( )

Z' ( )

(b) (a)470 C

0.8 1.0 1.2 1.4 1.6 1.8-10

-8

-6

-4

-2

0

2

Ln (T

)

1000/T (K-1)

(a) (b)

Arrhenius curves of (a) BiYO3 (b) Bi1-xCaxYO3.Cole –Cole plot of (a) BiYO3 (b) Bi1-xCaxYO3.

𝟏𝟐

(𝟏−𝒙 ) 𝑩𝒊𝟐𝑶𝟑+𝒙𝑪𝒂𝑶+𝟏𝟐𝒀 𝟐𝑶𝟑→𝑩𝒊𝟏−𝒙

𝟑+¿𝑪𝒂𝒙𝟐+¿𝒀

𝟑 +¿𝑶𝟑−

𝒙𝟐

𝟐− ¿

¿ ¿

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ConclusionS


Rietveld refinement confirms that samples are single phase

and exhibit pm-3m symmetry.

The thermogravimetric analysis shows that samples exhibit

weight loss at high temperatures due to the creation of oxygen

vacancies and bismuth vitalization.

The TEC and conductivity shows two different slopes one

below 550 °C and other above that. This change in slope can

be due to the increase in oxygen vacancy concentration and

hence increase in mobility of defects at high temperatures.

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In today’s world, solving environmental and energy

problems is an investment, not an expense

Thank you

221 samta

Technology

Transcript of 221 samta