1. CH5715 Energy Conversion and Storage http://jtsi.wp.st-andrews.ac.uk/module-ch5715- energy-conversion-and-storage-john-irvine/

2. Impedance Spectroscopy Introduction to EIS and process speciation

4. Questions

5. Solid Oxide Fuel Cells: Cathode Materials and Interfacial Reactions

7. Nature of Three Phase Boundary

14. Investigation of role of microstructure in fuel oxidation performance Patrick Muhl Introduction ACC Anode Electrolyte Cathode CCC airH20H20 N2N2 H2H2

15. Patrick Muhl Approach Why do we care about diffusion/ concentration/ utilization - “losses” at the anode? 1. Even though they are mostly small, they are losses! 2. These losses are suspected to increase when using CH 4 ! 3. Vital in the anode supported FC design!

16. Patrick Muhl Approach RsRs R p1 R p2 R total

17. Patrick Muhl Approach constant (@low FU)

18. t acc >> t anode, t electrolyte Patrick Muhl Introduction fuel H20H20 Total current ≠ 0 H 2 0 (CO, CO 2 ) enriched reaction zone Competition of H 2 “getting in”, versus H 2 0 (CO 2 ) “getting out” Material properties - Thickness (diffusion length) - Porosity - Tortuosity - Density - Grain size Gas properties - Diffusion coefficient - Binary or multiple molecules Operation setup - Mass flows (i.e. m H 2 ) - Temperature - Current density. Problems - Electrochemically active diffusion layer - Gas pathway (measurement setup) - Set of variables (matrix) - Clean correlation of measurements to material properties

23. kHz Charge transfer Hz Diffusion

24. Resume of impedance – process relations CC Electrode O R Electrolyte Mass transport Warburg types

25. Questions