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  • Melting at 1250 C

99 sakshi Presentation Transcript

  • 1. Paper Code: 099 Barium Doped Bismuth Vanadate Structural and Thermal Properties for SOFC Application Sakshi Gupta and K. Singh* School of Physics & Materials Science, Thapar University, Patiala IV th International Conference on Advances in Energy Research Indian Institute of Technology Bombay, Mumbai 1 Copyright 2013-2014 *E-mail: kusingh@thapar.edu
  • 2. Introduction Deficiency of conventional energy sources. Need to develop an energy efficient non conventional eco- friendly source. 2 Copyright 2013-2014 Release of green house gases with combustion of conventional energy sources.
  • 3. Fuel Cell Fuel cell is an electrochemical energy conversion device. It produces electricity from external supplies of fuel (anode side) and oxidant (cathode side). In fuel cell and battery, electrochemical reactions are used to create electric current. which can be replenished, while batteries store electrical energy chemically in a closed system. 3 Copyright 2013-2014 Fuel cells are different from batteries as they consume reactant,
  • 4. Copyright 2013-2014 Types of Fuel Cells 4
  • 5. Alkali Fuel Cell (AFC) Compressed hydrogen and oxygen fuel potassium hydroxide (KOH) electrolyte ~70% efficiency 150˚C - 200˚C operating temp. Requires pure hydrogen fuel and platinum catalyst Liquid filled container → corrosive leaks 5 Copyright 2013-2014 300W to 5kW output
  • 6. Molten Carbonate Fuel Cell (MCFC) Carbonate salt electrolyte 60 – 80% efficiency ~650˚C operating temp. cheap nickel electrode catalyst Corrosive electrolyte 6 Copyright 2013-2014 up to 2 MW constructed, up to 100 MW designs exist
  • 7. Phosphoric Acid Fuel Cell (PAFC) Phosphoric acid electrolyte 37-42% efficiency 150˚C - 200˚C operating temp The electrolyte is very corrosive Platinum catalyst is very expensive 7 Copyright 2013-2014 11 MW units have been tested
  • 8. Polymer electrolyte Membrane (PEM) Thin permeable polymer sheet electrolyte 40 – 50% efficiency 50 – 250 kW Electrolyte will not leak or crack Temperature good for home or vehicle use Platinum catalyst on both sides of membrane 8 Copyright 2013-2014 80˚C operating temperature
  • 9. Solid Oxide Fuel Cell (SOFC) Hard ceramic oxide electrolyte ~80% efficient ~1000˚C operating temperature cells output up to 100 kW High temp allows for power generation using the heat, but limits use SOFC units are very large Solid electrolyte have no leakage problem 9 Copyright 2013-2014 High temp / catalyst can extract the hydrogen from the fuel at the electrode
  • 10. Continued..... Out of the fuel cells discussed above Solid Oxide Fuel Cells (SOFCs) can be considered as a possible solution. SOFCs provide high total efficiency in addition to clean energy production. As well as water energy when hydrogen is used as fuel in SOFCs 10 Copyright 2013-2014 is the only emission along with energy along with
  • 11. The benefits of SOFCs Include: Energy security: reduce oil consumption, cut oil imports, and increase the amount of the country’s available electricity supply. Reliability: achieve operating times in excess of 90% and power available 99.99% of the time. Low operating and maintenance cost: the efficiency of the SOFC system will drastically reduce the energy bill (mass production) and have lower maintenance costs than their alternatives. Choice of fuel: allow fuel selection: hydrogen may be extracted from natural gas, propane, butane, methanol or diesel fuel. 11 Copyright 2013-2014 Constant power production: generate power continuously.
  • 12. Good stability. High conductivity. Chemical compatibility with other components of the cell. Similar thermal expansion coefficient to avoid cracking during the cell operation. Dense electrolyte to prevent gas mixing. Porous anode and cathode to allow gas transport to the reaction sites. High strength and toughness Compatibility at higher temperatures. Low cost. 12 Copyright 2013-2014 desirable characteristics of SOFC components:
  • 13. Characteristics of Solid Electrolyte Availability of large number of free ions Large number of vacancies for hopping Free of porosity Thermal expansion match reducing and oxidizing environments) The ionic conductivity of the electrolyte should be high 13 Copyright 2013-2014 Chemically stable (at high temperatures as well as in
  • 14. METHODOLOGY Bi2O3 + V2O5 + BaO Grinding of required composition in agate mortar pestle Melting at 1250 ͦC Splat quenching of the melted sample XRD Dilatometery 14 SEM Copyright 2013-2014 Characterizations
  • 15. X-RAY DIFFRACTION ANALYSIS (d) Intensity (arb. units) (a) 20 30 40 50 60 70 80 (c) 20 degrees (2) 30 40 50 60 70 80 degrees (2) Reitveld refined XRD patterns of Bi4V2-xBaxO11-δ (a) as quenched x = 0.0, (b) as quenched x = 0.05, (c) sintered x= 0 and (d) sintered x = 0.05. 15 Copyright 2013-2014 Intensity (arb. units) (b)
  • 16. Reitveld refined lattice parameters of Bi4V2-xBaxO11-δ (x = 0.0 and 0.05) As quenched samples Sintered samples Composition b (Å) c (Å) β (degrees) a (Å) b (Å) Bi4V2O11-δ 5.58 15.35 16.59 89.98 5.59 15.33 16.59 89.97 Bi4V1.95Ba0.05O11-δ 5.57 15.39 16.65 90.08 5.59 15.35 16.61 89.95 16 c (Å) β (degrees) Copyright 2013-2014 a (Å)
  • 17. MICROSTRUCTURE ANALYSIS 35 25 20 15 10 5 0.0 0.05 x Grain size range of sintered samples with x = 0.0 and 0.05. 17 Copyright 2013-2014 Range (m) 30
  • 18. SEM Micrographs (b) (a) 10 μm 10 μm (d) 20 μm 20 μm Scanning electron micrographs of Bi4V2-xBaxO11-δ (a) as quenched x = 0.0, (b) as quenched x = 0.05, ( c) sintered x= 0.0 and (d) sintered x = 0.05. 18 Copyright 2013-2014 (c)
  • 19. DILATOMETRIC ANALYSIS -3 7.0x10 (a) -3 -5 1.0x10 (c) -3 6.0x10 -5 1.0x10 6.0x10 -6 -3 5.0x10 8.0x10   -3 -6  5.0x10 8.0x10 -6 6.0x10 -3 -6 2.0x10 -3 2.0x10 0.0 -3 L/Lo 4.0x10 -3 3.0x10 6.0x10 -3 -6 3.0x10 4.0x10 -3 -6 2.0x10 1.0x10 2.0x10 -3 0.0 1.0x10 -6 -2.0x10  (CTE /C ) (CTE / C) -6 L/Lo -6 4.0x10 -3 4.0x10 0.0 -6 -6 0.0 -4.0x10 -2.0x10 -3 -1.0x10 0 100 200 300 400 500 600 700 800 0 100 200 Temperature (C) 6.0x10 -5 400 500 600 700 800 Temperature (C) -3 (b) -3 6.0x10 300 -5 1.0x10 1.0x10 (d) -3 -3 5.0x10  5.0x10 -6 8.0x10 -6  8.0x10   -3 -3 -6 2.0x10 2.0x10 -3 L/Lo -6 4.0x10 -3 3.0x10 -6 4.0x10 -3 2.0x10 -6 2.0x10 -3 0.0 1.0x10 -6 6.0x10 1.0x10 0.0 -6 0.0 -2.0x10 0.0 -6 0 100 200 300 400 500 600 (CTE / C) -3 3.0x10  (CTE /C) L/Lo 4.0x10 -6 6.0x10 700 0 Temperature(C) 100 200 300 400 500 600 700 -2.0x10 800 Temperature (C) Thermal expansion curves Bi4V2-xBaxO11-δ (a) as quenched x = 0.0, (b) as quenched x = 0.05, (c) sintered x= 0.0 and (d) sintered x = 0.05. 19 Copyright 2013-2014 -3 4.0x10
  • 20. Thermal expansion coefficients and different transition temperatures of Bi4V2-xBaxO11-δ (x = 0.0 and 0.05) Composition As quenched samples TEC (10-6 /⁰C) Sintered Remarks samples TEC (10-6 As quenched samples Sintered samples /⁰C) Bi4V2O11-δ 8.83 8.98 α→β and β→γ β→γ transition transitions take place take place at at 405 ⁰C and within 533 ⁰C the range 447-595 ⁰C respectively. Bi4V1.95Ba0.05O11-δ 9.21 8.62 α→β and β→γ transitions take place within the range at 301-398 ⁰C and 414- 509 ⁰C resp. 20 Copyright 2013-2014 α→β and β→γ transitions take place within the range at 330-392 ⁰C and 477- 595 ⁰C resp.
  • 21. Conclusions • All the samples synthesized are found to be single phase. • All the samples are found to be stabilized in α phase with C2/m space group which is confirmed with Reitveld refinement. • The thermal expansion coefficient found to be in the range of the components which are used in SOFC. 21 Copyright 2013-2014 • The grain size of the samples is decreasing with doping.
  • 22. Acknowledgement • I would like thank Department of Science and Technology (DST) for the financial support. • I would like to thank my Supervisor Dr. Kulvir Singh (Professor and Head) School of Physics and Materials Science, Thapar University, Patiala for his Guidance. for providing me an opportunity to present my work here. 22 Copyright 2013-2014 • I would like to thank Dr. P.C. Ghosh (Organizer ICAER 2013)
  • 23. Copyright 2013-2014