1. Investigation of BSCF Cathode on GDC Electrolyte for Intermediate Temperature SOFCs Vann Brasher Mentors: Dr. Daniel Mumm Anh Duong Sungrok Bang

2. The General Outline The SOFC Synthesis of Samples Testing Conclusion/Future Work

3. The SOFC Electrochemistry ½ O 2 + 2 e -  O 2- O 2- + H 2  H 2 O + 2 e - Conductivity Requirements Electrolyte O - Cathode/Anode e - Solid State Ceramics

4. The SOFC Fuel Cell Problems/Voltage Losses Electrochemical Activation (Overpotential) porosity mixed conductivity Ohmic thin layers/materials Mass Transport gas flow system

5. The SOFC Purely Electronic Conducting Cathode (LSM) Triple Phase Boundary limitations Mixed Conduction (LSF, LSCF) Incompatible with YSZ!

6. Synthesis of Samples GNP

7. Synthesis of Samples B.5 S.5 C x F 1-x O 3-δ X=.2,.5,.75 Pm3m cubic Red=Oxygen Green=A-site Ba, Sr Blue=B-site Co, Fe

8. Synthesis of Samples Screen printing on isostatically pressed GDC BSCF + binder 1cm 2 symmetric (both sides) calcine + fast, cheap + simulates industry - inconsistant (ink, blades)

9. Testing X-Ray Diffraction Identification XRD database published XRD Lattice parameter Bragg’s Law Increase with Co Oxygen vacancy

10. Testing SEM imaging Visual Characterization Porosity Nano-Scale Features Surface Area Uniformity

11. Testing Symmetric Cell Tests Impedance (10mV AC) from 350-550 °C DC voltage + Impedance from 600-750 °C V - iR = η

12. Testing

13. Conclusion Overpotential is a measure of losses due to electrochemical activity at the cathode. BSCF557525 has lower overpotential  better for applications in SOFC cathode. Can be linked to lattice expansion. More oxygen vacancies, larger cations, etc.

14. Future Work Screenprint with consistency and quality Achieve consistent Impedance data More samples, aim for repeatability Compare with other materials Analyze factors related to overpotential (i.e. porosity, surface area) Full Cells?

15. Take it Away! Fuel Cells are efficient & clean Mixed Conductors make good Cathodes Making & Testing Cells takes many steps! Cobalt increases eletrochemical efficiency

16. Acknowledgements National Science Foundation Dr. Mumm & Lab (Anh, Sungrok) Said & UROP