nanostructured thin films of la 0.6 sr 0.4 coo 3-δ via spray pyrolysis for micro-sofc application...
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26.03.2012 | Gemeinschaftslabors Nanomaterialien | Cahit Benel
Nanostructured thin films of La0.6Sr 0.4CoO3-δ via
spray pyrolysis for micro-SOFC application
Cahit Benel, Azad J. Darbandi, Horst Hahn
Michel Prestat, René Tölke, Anna Evans
26.03.2012 | Gemeinschaftslabors Nanomaterialien | Cahit Benel 2
Fundamentals of SOFC
Anode: H2 + O2- H2O + 2 e-
Cathode: ½ O2 + 2 e- O2-
Total: H2 + ½ O2 H2O
26.03.2012 | Gemeinschaftslabors Nanomaterialien | Cahit Benel 3
MotivationLosses in SOFC
To reduce the losses:
Making the whole cell as thin as
possible
Optimizing of electrode materials
and their properties
National Energy Technology Laboratory Fuel cell handbook. 7th ed. Morgantown, WV: U.S. Department of Energy; 2004.
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Micro-solid oxide fuel cell - State of artCollaboration with ETH Zurich
Eva
ns, A
. et.
Al.
Jour
nal o
f Pow
er S
ourc
es 1
94 (
2009
) 11
9-12
9
µPEMFC80 °Cpure H2
µDMFC
Li-ion batteries
Ni-MH batteries
µSOFC350-550 °Chydrocarbons
Cathode
Anode
Electrolyte
Si
Goal:Nanoparticulate thin film cathode
with thickness between 200 nm and 500 nm
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Synthesis of LSCSalt-assisted Spray Pyrolysis
La0.6Sr0.4CoO3-δ (LSC)
Furnace
T
Vacuum
pump
O2
MFC
FilterControl
valve
Ultrasonic
nebulizer
p
Carrier Gas Water based precursor
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ResultsSalt-assisted Spray Pyrolysis
As synthesized
No reaction between NaCl and LSC phase
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Removal of Salt
As synthesized After washing
As synthesized nanopowder washed by DI water to remove NaCl.
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XRD
Before washing After washing
Crystallite size ≈ 7 nm
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Electrochemical Characterization
• Symmetrical cells under OCV
•1MHz-0.1Hz
•450-650 °C with 50 °C increments
•PO2=0.01-1 atm
• Yttria stabilized zirconia (YSZ) substrates
• Ce0.8Gd0.2O1.9 (GDC) buffer layer via spin coating (950 °C for 2 h)
• LSC functional layers via spin coating (550 °C for 1 h)
•LSC•LSC-GDC (10-40 wt %) nanocomposite
LSCGDC
YSZ
LSCGDC
26.03.2012 | Gemeinschaftslabors Nanomaterialien | Cahit Benel 10
Electrochemical Characterization
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Electrochemical CharacterizationDependence of ASR on temperture & GDC concentration
* Karageorgakis et. al., Journal of Power Sources 195 (2010) 8152-8161
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Summary
Nanocrystalline single phase LSC via SASP
Nanoparticulate thin films of LSC and LSC-GDC (10-40%) with thicknesses between 200 and 500 nm by single step spin coating
LSC-GDC (30%) nanocomposite films showed the lowest ASR values
0.78 Ω cm2 (250 nm thickness, @ 600 °C)
Next step
To check the performance of the LSC functional thin films on free standing electrolytes
26.03.2012 | Gemeinschaftslabors Nanomaterialien | Cahit Benel 13
Financial support:
Center for Functional Nanostructures (CFN)
Equipment support:
Acknowledgments
Elektrochemie Verbund-Süd
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Thank you for your attention
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26.03.2012 | Gemeinschaftslabors Nanomaterialien | Cahit Benel 16
26.03.2012 | Gemeinschaftslabors Nanomaterialien | Cahit Benel 17
Free standing electrolyte - State of artCollaboration with ETH Zurich
1. Silicon nitrade deposition
2. Photoresist by spin coating
3. Exposure & Development
4. Plasma etching of silicon nitride
5. Deposition of electrolyte (PLD)
6. KOH wet etching of Si
7. Plasma etching of silicon nitride