WP 1: Fuel Cell Development 1 http://www.nonmet.mat.ethz.ch/research/onebat Strictly Confidential NMW Workpackage 1: Fuel Cell Development KTI Review Meeting, December 16, 2005 U. P. Muecke (NMW) and S. Rey-Mermet (EPFL) NTB INTERSTAATLICHE HOCHSCHULE FÜR TECHNIK BUCHS
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WP 1: Fuel Cell Development 1 Strictly Confidential NMW Workpackage 1: Fuel Cell Development KTI Review Meeting,
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water in anode gas PH2 / PH2Oapplying overpotential Up
2.5 5.0 7.5 10.0
-5.0
-2.5
0
2.5
Z' [ohm cm2]
Z''
[ohm
cm
2 ]
A vs. ARA vs. CR
R2 R3
equivalent circuit fitting
diffusion accountsfor changes
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WP 1.2 Anode - Conclusions
• 0.1-1 μm thick crack-free films with >30% porosity
• Conductivity surpasses milestone by factor 5
• Conductivity stable over 1500 hours at 550°C
• Good electrochemical performance in dry and humidified gas
Next:
• Improved low temperature sintering
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WP 1.3 Cathode Microstructure & Conductivity
Porosity > 20 % is achieved by spray pyrolysis.
1 μm1 μm1 μm A
500 nm500 nm500 nm C
Good electrical conductivity.
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WP 1.3 Cathode Phase
Desired perovskite phase is obtained.
La0.6Sr0.4Co0.2Fe0.8O3
ETH
La0.3Sr0.7CoO3
EPFL
2 Theta / deg
J. ten Elshof, J. Boeijsma, Powder Diffr, 1996, 11 (3), 240.G.C. Kostogloudis, C. Ftikos, Solid State Ionics, 1999, 126 (1-2), 143.
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Rp
/ cm
2
WP 1.3 Cathode Performance
J.A. Lane, P.H. Middleton, H. Fox, B.C.H. Steele, J.A. Kilner, In 2nd International Symposium on Ionic and Mixed Conducting Ceramics. 1994J.M. Ralph, A.C. Schoeler, M. Krumpelt, J. Mater. Sci., 2001, 36 (5), 1161.
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WP 1.3 Cathode Conclusions
• Crack-free films with >20% porosity achieved
• Good electrical conductivity
• Excellent electrochemical performance
Next:
• Exploring new materials, e.g. Ba0.5Sr0.5Co0.8Fe0.2O3
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WP 1.4 Microfabrication and Contacting
Pt
foturan glass
foturan irradiated
foturan glass
anodeelectrolyte
cathode
contacted -SOFC
free-standing membrane
etching
25 mm
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WP 1.5 PEN Integration and Testing
Air
FuelE I
MFC4MV4 (NC)V4
FICR401
V5MV5 (NC) MFC5
FIC501
V10
V9
inert gasN2, Ar, ...
MFC1MV1 (NC)V1
FICR101
fuelH2, CxHy, ...
V2MV2 (NC) MFC2
FICR201
V3
MV3 (NC) MFC3
FICR301
oxygenO2
V7
V6
V8
FI901
high precision flow meterfor calibration
off-gas anode
TIR904
TIR905
off-gas cathode
TIR906
spare access
spare access
pressurizedair
spare access
oven
TICR910
cell
TIR902
TIR907
pressureregulator
flashbackarrester
anode
cathode
TIR903
TIR908
TIR909
spare access
flashbackarrester
gas mixing box
spare access
CV2
CV3
CV4
CV5
CV1
pressureregulator
pressureregulator
pressureregulator
V11
bubbler
V12
Test rig with computer controlled gas supply and data acquisition
Fuel
Inert
Oxygen
Gas mixing unit
Water Cell
Exhaust
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WP 1.5 Measured Cell Performance
T ~ 550°C
OCV 170 mV
Power density
~12 mW / cm2
YSZ PLDNi-CGO (SP)
LSCF (SP)
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WP 1.5 Projected Cell Performance
Projected cell performance based on results obtained for single layers
today
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Actual design fabrication
Membrane
2.4
cm
Ni grid
Current collector
Contact cathode
Contact anode
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Electrolyte membrane Ce0.8Gd0.2O2 (CGO)
Dense, polycrystalline film Ionic conductivity as in bulk ceramics Better than project specs
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Stress control of CGO-film
Stress controlled by annealing in oxygen Freestanding membranes can be fabricated (2 mm) Thermal stability with 150 nm: up to 300 °C
100 % Ar, 15 mT, RT
Oxygen uptake
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Nickel Grid for membrane reinforcement and current collection
2. Current collectoranode
4. CGO 9. Ni grid
100 m
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Free standing CGO membranes with nickel grid
No annealing
Annealing for low stress
100 m
50 m
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Summary Achievements
500 nm500 nm500 nm
Anode
Cathode
Membrane
> 100 S / cm Rp < 1 cm2
> 550 S / cm Rp < 1 cm2
> 0.5 S / cm
to 500°C Stable up
12 mW / cm2
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Validation of Milestones and Deliverables• WP 1.1: Electrolyte
Month 3: - dense and crack-free electrolyte with composition CGO 80/20 (NMW, EPFL)
- conductivity @ 500°C-800°C in air characterized; > 0.2 S/m @ 700°C in air (NMW, EPFL)