Progress Report on Sequential-Fab Plasma-Sprayed SOFC Components
description
Transcript of Progress Report on Sequential-Fab Plasma-Sprayed SOFC Components
74 Batterson Park Road, Farmington, CT 06032 1-888-NANO-888 Fax: (860) 678-7569
Progress Report on Sequential-Fab Plasma-Sprayed
SOFC Components
Rob S. Hui, H. Zhang, X. Ma, J. Roth, J. Broadhead, D. Xiao, and D. Reisner
US Nanocorp, Inc.
Fuel cells 2003 The Third Annual BCC Conference
Stamford, CT
74 Batterson Park Road, Farmington, CT 06032 1-888-NANO-888 Fax: (860) 678-7569
Outline
• Motivation
• Brief Review of Previous Work
• Progress Report
• Summary
2/23
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• Thermal Sprayed Electrodes / Electrolytes for Batteries and Fuel Cells
• Fuzzy Logic Modeling Methods to Manage Batteries and Fuel Cells
2002 D&T Connecticut Technology Fast 50 Award
3/23
2002 Deloitte & Touche Technology Fast 500 Award
US Nanocorp
74 Batterson Park Road, Farmington, CT 06032 1-888-NANO-888 Fax: (860) 678-7569
Solid Oxide Fuel Cells (SOFCs)
Features:
4/23
• Higher efficiency• More flexible fuels• All solid components
Applications:
Power plant Residential Transportation Military
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YSZ
Ni-YSZ
LSM
Air
Fuel
Loa
d
Low temperature SOFCs (< 850oC)
Alternative materials Appropriate cell design Manufacturing routes
High temperature SOFCs (~ 1000oC)
Materials constraints High stress of differential thermal expansion Long term stability poor Precludes nanomaterials High cost of operation
Research Motivation
5/23
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USN’s Enabling SOFC Technology
Nanostructured electrode materials Enable low Temperature Operation High activity (high interfacial surface area) Expect Improved cell performance
Plasma Spray Integrated fabrication of membrane-type SOFC
New materials with high performance Sr1-1.5xYxTiO3 (“SYT”) replaces Ni/YSZ MIEC has more reaction sites than Ni-cermet LSGM has four-time higher ionic conductivity than YSZ
6/23
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USN’s SOFC Strategy Reduce cell operating temperature
Thin film LSGM electrolyte (high conductivity)
Nanostructured electrodes (many grain boundaries -> large interface)
SYT anode material is a MIEC working at 600 – 800 oC
Increase fuel cell operating efficiency SYT could directly catalyze hydrocarbon fuel SYT has more reaction sites than Ni-cermet
Drive down fuel cell manufacturing cost using APS Inexpensive, Universal (Metco 9MB) Sequential fabrication of cell components Possibility of elimination of reforming unit
7/23
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Plasma Processing
• Brief (on the order of 1 ms) particle residence time
• Rapid heating
• Steep gradients in HVOF and plasma flow fields
8/23
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Thermal Spray GunNanocoated Component
Nanomaterial Feedstock Substrate
Advantages of Plasma Spray
Rapid and sequential fabrication Nanostructured materials Accurately controlled Thickness Potential low cost (automation) Robotic continuous operation
Graded porosity & composition Excellent interfacial contact Large area and free geometry Unlimited substrates (@RT) No high temperature sintering
9/23
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20m
5 - 20 nmparticles
reconstituted sprayable form
5 - 20 nmparticles
non-agglomerated
5 - 20 nm particles
loosely agglomerated
hollow shell agglomerates
30 mm
Feedstock Reconstitution
10/23
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Microstructure of Feedstock
0
2
4
6
8
10
12
14
9 12 18 27 36 40 45 49 53 58 62 78
Feedstock size (um)
Fe
ed
sto
ck
nu
mb
er
100m
10 m
11/23
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Free standing plasma sprayed SOFC single cells
Anode electrode
Cathode electrode
Electrolyte
USN’s Planar SOFC Systems
12/23
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LDC40 + Ni
SWPC tube
LSGM
LDC40
Anode: Nano LDC40 + Ni Interlayer: LDC40 Electrolyte: La0.8Sr0.2Ga0.8Mg0.2O3
Cathode: SWPC proprietary tube
USN’s Tubular SOFC Systems
13/23
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50 m LSM
SYT
LSGM
Requirements for Sprayed Components
14/23
Porous electrodes
Dense electrolyte
Right chemical phase and composition
Compatible electrochemical properties
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SEM Images of LSGM
LSGM feedstock
100m(b) 100m(b)LSGM 30 m
LSGM
LSM
As-sprayed LSGM on LSM 15/23
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Open-Circuit Voltage
0
0.2
0.4
0.6
0.8
1
1.2
0 10 20 30 40 50 60
Time hourV
olta
ge V
700oC
0
0.2
0.4
0.6
0.8
1
1.2
250 350 450 550 650 750
Temperature /oC
Vol
tage
/V
3oC/min
16/23
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As-sprayed LSGM
20 30 40 50 60 70 80
LSGM as sprayed
Inte
nsity
(arb
. unit
)
2
LSGM feedstock
0 500 1000 1500 2000 2500 3000 3500 40000
500
1000
1500
2000
2500
3000
3500
4000
4500
650oC
700oC
750oC
800oC
-ZI
ZR
0.0 0.5 1.0 1.5 2.0 2.50.0
0.5
1.0
1.5
2.0
2.5
-ZI
ZR
Ac Impedance measurementX-ray diffraction spectra17/23
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Heat-treatment of Sprayed LSGM
30 40 50 60 70 80
900oC
800oC
700oC
Inten
sity (
arb.
unit)
2
500oC
0 2 4 6 8 10 120
2
4
6
8
10
12
650oC
700oC
750oC
800oC
-ZI
ZR
Change of ac Impedance spectra Chang of XRD pattern
18/23
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0.0 0.5 1.0 1.50.0
0.5
1.0
1.5
pressed sprayed
-ZI
ZR
Sintered & Sprayed LSGM
0 1 2 3 40
1
2
3
4 650oC
700oC
750oC
800oC
-ZI
ZR
Pressed / Sintered LSGM Sintered vs Sprayed LSGM
19/23
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Pump
Tungsten Anode
Tungsten Cathode
Atomizing Nozzle
Work pieceYSZ Liquid Feed Stock
+
+-
Gas
Gas
Plasma
Solution Feedstock Plasma Spray
20/23
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Advantages of SPS Electrode
Forms 3-D porous structure, leading to high fuel gas permeability for anode
Forms nanostructured anode, increases surface area of fuel – solid interaction
Enables thin layer coating formation
Higher thermal shock resistance21/23
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Nanostructured SOFC was proposed based on the materials selection and fabrication technique
Planar SOFCs have been successful fabricated by plasma spray technique with dense electrolyte and porous electrodes
Thick film LSGM has been sprayed and characterized. Sprayed layer has same electrochemical properties with sintered one
Improvement of electrode structure and characterization of fuel cell performance are needed in the future
22/23
Summary
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Acknowledgement
This work was supported by the Department of Energy:
(1)with Dr. Keqin Huang at Siemens Westinghouse Power Corp. under DOE Prime Contract No. DE-FC26-99FT40709
(2)under a DOE SBIR Grant No. DE-FG 02-01ER83340.
23/23