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ENI Fuel Cells. Segmented cell testing for cathode parameter investigation. Industrial Energy Systems Laboratory (LENI), Group of Electrochemical Engineering (GGEC), Interdisciplinary Centre of Electron Microscopy (CIME) École Polytechnique Fédérale de Lausanne – EPFL Lausanne - Switzerland. - PowerPoint PPT Presentation
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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 2nd 2010
ENIFuelCells
Industrial Energy Systems Laboratory (LENI), Group of Electrochemical Engineering (GGEC), Interdisciplinary Centre of Electron Microscopy (CIME)
École Polytechnique Fédérale de Lausanne – EPFLLausanne - Switzerland
OUTLINE
Introduction
Experimental
Results
Conclusion
• Validation• Parameter investigation
2/13
INTRODUCTION (1)- motivation -
Objectives: Reduce testing time Increase reproducibility
0.4
0.5
0.6
0.7
0.8
0 250 500 750 1000 1250 1500 1750 2000
Pot
entia
l [V
]
Time [h]
0.6 A/cm2, 850°C, 7%H2O/H2
And more…… for each experiment!!
Button cell testing:
• Low degradation
Long testing time
• Fluctuations
3/13
INTRODUCTION (2)- strategy -
• N-fold decrease of testing time
• Same T, gas concentration, history
4/13
EXPERIMENTAL- the testing station -
5/13
I
I
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
RESULTS (2)validation
7/13
4 IDENTICAL CELLS
700
800
900
1000
1100
0 200 400 600 800
Pote
ntia
l [m
V]
Current [mA/cm2]
AS-A IAS-A IIAS-A IIIAS-A IV
IV-CURVES
• Similar behavior• Small difference in OCV• Polarization lowers the difference
850°C, 97%H2/3% H2O
0
0.1
0.2
0.3
0.4
0 0.2 0.4 0.6 0.8 1 1.2
-Z'' [
Ohm
cm2 ]
Z' [Ohm cm2]
AS-A IAS-A IIAS-A IIIAS-A IV
~3 hzEIS MEASUREMENTS
• High frequency overlapping• Low frequency mismatch
(conversion process)
H2O/H2 distribution850°C, 97%H2/3% H2O
RESULTS (3)current density
8/13
• Polarization-driven activation
• Current-dependent degradation
0.30 A/cm2
0.45 A/cm2
0.60 A/cm2
0.75 A/cm2
0.30 A/cm2
850°C, 97%H2/3%H2O
• Activation at 0.3 A/cm2
• Operation at different I
RESULTS (4)cathode thickness
9/13
850°C, 93%H2/7% H2O, 0.6A/cm2
20µm
15µm10µm
5µm • Different thicknesses
• Operation 0.6 A/cm2
• Difference in Rohm at the beginning
• AS-B I limited by thickness
• Different degradation behavior:
Thickness Degradation5µ 6.0%/1000h
10µ 2.2%/1000h
15µ 1.5%/1000h
20µ 0.9%/1000h
Cr contamination (SEM, WDX)
RESULTS (5)cathode composition
10/13
• LSM/Mn-doped YSZ cathodes
• Same microstructure (except AS-C II)
600
700
800
900
1000
1100
0 0.2 0.4 0.6 0.8 1
Pote
ntia
l [m
V]
Current [A]
AS-C I (0%Mn-YSZ/LSM)AS-C II (2.5%Mn-YSZ/LSM)AS-C III (4.5%Mn-YSZ/LSM)AS-C IV (6.5%Mn-YSZ/LSM)
850°C, 93% H2/7% H2O
EIS analysis with variation of:
Temperature (750°C, 800°C, 850°C)
Current density (OCV, 0.3 A/cm2, 0.6 A/cm2)
Fuel composition (93%H2/7%H2O, 65%H2/7%H2O, 65%H2/5%H2O)
Frequency Process
10 Hz Conversion, anode
30 Hz (750°C)Dissociative adsorption,
cathode70 Hz (800°C)
200 Hz (850°C)
200 HzDiffusion, anode
(not clear, small signal)
700 Hz (750°C)
Charge transfer, anode1000 Hz (800°C)
2000 Hz (850°C)
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 -0.10
-0.05
0.00
0.05
0.10
0.15
0.70 0.80 0.90 1.00 1.10 1.20 1.30
-Z" [
Ohm
cm2 ]
Z' [Ohm cm2]
120h264h336h432h
800°C, 0.2 A/cm2, air both sides
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
CONCLUSIONS12/13
13/13
THANK YOUfor your attention