1. Segmented cell testing for cathode parameter investigation P. Tanasini, J. A. Schuler, Z. Wuillemin, M. L. Ben Ameur, C. Comninellis, and J. Van herle European Fuel Cell Forum Lucerne, July 2 nd 2010 ENI Fuel Cells Industrial Energy Systems Laboratory (LENI), Group of Electrochemical Engineering (GGEC), Interdisciplinary Centre of Electron Microscopy (CIME) École Polytechnique Fédérale de Lausanne – EPFL Lausanne - Switzerland

2. OUTLINE  Introduction  Experimental  Results  Conclusion Validation Parameter investigation 2/13

3. INTRODUCTION (1) - motivation - Objectives: Reduce testing time Increase reproducibility 0.6 A/cm 2, 850°C, 7%H 2 O/H 2 And more… … for each experiment!! Button cell testing: Low degradation Long testing time Fluctuations 3/13

4. INTRODUCTION (2) - strategy - N-fold decrease of testing time Same T, gas concentration, history 4/13

5. EXPERIMENTAL - the testing station - 5/13 I I

6. RESULTS (1) 1.Validation 2.Parameter investigation Current density Cathode thickness Cathode composition Cr source Anode-Supported (AS) cells Electrolyte- Supported (ES) cells 6/13

7. RESULTS (2) validation 7/13 4 IDENTICAL CELLS IV-CURVES Similar behavior Small difference in OCV Polarization lowers the difference 850°C, 97%H 2 /3% H 2 O ~3 hz EIS MEASUREMENTS High frequency overlapping Low frequency mismatch (conversion process)  H 2 O/H 2 distribution 850°C, 97%H 2 /3% H 2 O

8. RESULTS (3) current density 8/13 Polarization-driven activation Current-dependent degradation 0.30 A/cm 2 0.45 A/cm 2 0.60 A/cm 2 0.75 A/cm 2 0.30 A/cm 2 850°C, 97%H 2 /3%H 2 O Activation at 0.3 A/cm 2 Operation at different I

9. RESULTS (4) cathode thickness 9/13 850°C, 93%H 2 /7% H 2 O, 0.6A/cm 2 20µm 15µm 10µm 5µm Different thicknesses Operation 0.6 A/cm 2 Difference in R ohm at the beginning AS-B I limited by thickness Different degradation behavior: ThicknessDegradation 5µ6.0%/1000h 10µ2.2%/1000h 15µ1.5%/1000h 20µ0.9%/1000h Cr contamination (SEM, WDX)

10. RESULTS (5) cathode composition 10/13 LSM/Mn-doped YSZ cathodes Same microstructure (except AS-C II) 850°C, 93% H 2 /7% H 2 O EIS analysis with variation of: Temperature (750°C, 800°C, 850°C) Current density (OCV, 0.3 A/cm 2, 0.6 A/cm 2 ) Fuel composition (93%H 2 /7%H 2 O, 65%H 2 /7%H 2 O, 65%H 2 /5%H 2 O) FrequencyProcess 10 HzConversion, anode 30 Hz (750°C) Dissociative adsorption, cathode 70 Hz (800°C) 200 Hz (850°C) 200 Hz Diffusion, anode (not clear, small signal) 700 Hz (750°C) Charge transfer, anode 1000 Hz (800°C) 2000 Hz (850°C)

11. RESULTS (6) Cr source 11/13 WE (cathodes) exposed to Cr source One polarized cell, 3-electrode measurements One cell at OCV, symmetric cell measurements (4-electrode configuration)  Separation of the cathodic contribution in the polarized cell  The non-polarized cell doesn’t show degradation 800°C, 0.2 A/cm 2, air both sides

12. The multicathode strategy permits to decrease n-fold the testing time Same testing environment, history for all the segments Rapid identification of issues by comparison Flexibility comparable to the classic button-cell testing CONCLUSIONS 12/13

13. 13/13 THANK YOU for your attention