Deposition of Ceramic Composites for Solid
Oxide Fuel Cell Applications using
Aerosol Jet Printing
Mary Sukeshini Ayyadurai
University of Dayton Research Institute,
Dayton, OH
The Air Force Research Laboratory,
Wright-Patterson Air Force Base, OH
Optomec Inc., St. Paul, MN
May 15, 2012
1
Outline
 Fuel Cell – How it works and why we need
 Solid Oxide Fuel Cells (SOFCs)




Material properties
Multi-layer configuration, electrochemistry
Conventional fabrication methods
Single cell fabrication and performance
 Aerosol Jet Printing and Processing of SOFCs
 Electrochemical performance of cells & microstructure
• Single component- Electrolyte, YSZ
• Composite Cathode layers- LSM and YSZ
• Scanning Electron Microscopy(SEM)
 Anode Interlayer/Functional Gradation
 Summary, Challenges and Future Work
2
Anode
cathode
Hydrogen Fuel Cell
H2 + ½ O2 = H2O
ΔGo = -nFEo
Eo= 1.23 V
Cartoon scheme –Schatz Energy Research Center website
Diverse Energy Sources/Fuels and Applications
Stationary
Conventional
Fuels
Biomass
Natural Gas
Propane
Diesel
Other
hydrocarbons
Methane
Methanol
Renewable
sources (wind,
solar, biomass)
Nuclear
Hydrogen
Natural Gas
Clean and efficient
Energy conversion
Fuel Cells
 Alkaline
 Direct methanol
 Molten carbonate
 Polymer electrolyte
membrane
 Phosphoric acid
 Solid Oxide
•Primary Power and CHP
(residential, commercial and
industrial)
• Backup power
Transportation
Auxiliary
Power
Motive
power
•Trucks
•Trains
•Aircraft
•Ships
•Specialty
vehicles
(e.g.- fork lift)
•Buses
•Automobiles
Coal (with carbon
sequestration)
Portable Power
•Consumer Electronics
• Battery chargers
• Soldier power
Source: US DOE 2010
The Promise of Renewable Hydrogen from Wind and Solar Energy
-Hydrogen from renewable carbon free sources
-Needs advanced photoelectrolysis and photobiological technologies
PV Panels
Electrolyzer
Fuel Cell
Compressor/
gas flow control
To grid
Inverter
Controller
Underground
tank
Artist’s rendition of a futuristic home – source: Interface, vol. 13 (4), 2004
5
SOFC: Material Properties
Electrical
properties
Materials
Nickel-cermet
(Ni-Yttria stabilized zirconia)
•el. Conductivity
(el + ion)
•Catalytic activity
Thermomechanical
properties
•Porosity
•Thermal expansion
coefficient
•Adhesion
•Gas-tightness
Yttria doped
Zirconia (YSZ)
•ionic conductivity
(ionic >> el)
Strontium doped
lanthanum-manganate
(La,Sr)MnO3 (LSM)
•el. Conductivity
(el + ion)
•Catalytic activity
•Mechanical stability
•Adhesion
•Thermal expansion
coefficient
•Porosity
Color scheme in center : Courtesy -Robert Kee, Colorado School of Mines
6
Microstructure - “Triple Phase Boundary”
Ni-YSZ Anode
•
Microstructure
- particle size, Ni content, Ni dispersion
in the cermet
- preheating and heating temperatures
- sintering temperature
reaction at
gas/electrode/electrolyte
interface, a three phase boundary
(TPB)
Adsorption, surface reaction and charge
transfer
-dissociative adsorption of H2 (on Ni?)
-surface diffusion of H or (H+)
-ionization of surface H to Ni
-charge transfer reactions of H+ and O2and OH- around the TPB
-desorption of H2O
7
Multi-layered SOFC Configuration
Cathode
Cathode Interlayer
LSM
LSM/YSZ
YSZ
Electrolyte
Anode Interlayer
50Ni/50YSZ
Anode support-Ni/YSZ
Electrode functional layers, electrolytes and barrier layers
 Extension of “Triple phase boundary” into bulk of the electrode
 Barrier layers to avoid deleterious reactions between components
 Match the thermal co-efficient of expansion between components
 Thinner electrolytes to compensate for ohmic loss at intermediate temperature
operation
8
Fabrication Methods for SOFC Components
• Chemical methods
- Chemical vapor deposition(1-10 µm/h)
- Electrochemical vapor deposition(3-50
µm/h)
- Sol-Gel (0.5 µm-1 µm for each coating)
- Spray pyrolysis (5 -60µm /h)
• Ceramic Powder/Wet
• Physical Methods
- Physical vapor
-pulse laser (PLD)
-sputtering (0.25-2.5 µm/h)
- Laser Ablation
- Molecular beam epitaxy
- Atmospheric and vapor
plasma spraying (100-500 µm/h)
- Screen printing (10-100 µm)
- Tape casting (25-200 µm)
- Slip casting
- Filter pressing
- Slurry, spray, dip coating
- Tape calendering
- Transfer printing
- Electrophoretic deposition
9
Characteristics of Different Methods
• Chemical methods
dense films
high reaction temperatures
limited range of compositions
• Physical Methods
reproducible, patterning with litho graphy/
masks,
too expensive for scale-up
• Ceramic Powder/Wet
inexpensive,scale-up possible, prone to crack
formation, inhomogenous thickness
10
Cell Fabrication: Electrolyte and Cathode Layers on Anode
Support
Anode support Ni- YSZ
Paste or print LSM
Sinter- 1200 ˚C
Paste or print LSM/YSZ
Paste or print electrolyte, YSZ
Sinter- 1400 ˚C
Anode interlayer
50/50 wt% NiO/YSZ
Anode substrate- Ni -YSZ
Bisque- 950 ˚C
11
Comparison of Cell with Ink-jet Printed and Pasted Cathode
-Z"( cm2)
3
SEI - cell with
printed cathode
2
SEI - cell with
1
pasted cathode
0
LSM
(a)
650 oC
700 oC
750 oC
800 oC
850 oC
1
0
0
1
2
3
4
5
3
Cell impedance
3
650 oC
700 oC
750 oC
800 oC
850 oC
)
6
(a)
0
1
2
4
5
6
650 oC
700 oC
750 oC
800 oC
850 oC
2
3
4
(b)
Cell impedance
1
0
1
2
3
4
5
Z'( cm )
2
Z'( cm )
3
650 oC
700 oC
5
Z'( cm )
2
3
6
Ni/YSZ support
3
-Z"( cm2)
-Z"( cm2)
(a)
2
5
1
0
1
4
Z'( cm )
1
0
3
2
3
0
2
2
2
0
6
Ni/YSZ support
2
1
YSZ
Z'( cm2)
650 oC
700 oC
750 oC
800 oC
850 oC
LSM
LSM/YSZ
YSZ
-Z"( cm2)
-Z"( cm2)
3
0
(b)
LSM/YSZ
2
650 oC
700 oC
750 oC
800 oC
850 oC
•Sukeshini, A.M., Cummins, R., Reitz, T.L., and Miller, R.M., “Ink-Jet Printing of Anode Supported SOFC: Comparison of Slurry 650 oC
(b)
Pasted Cathode and Printed Cathode,” Electrochem. and Solid-State Lett., 12(12), pp. B176-179 (2009).
700 oC
12
6
Comparison of Performance of Cells with Ink-jet
Printed and Pasted Cathode (Fuel-H2; Oxidant- Air)
0.3
0.6
0.2
0.4
700 ˚C
0.2
650 ˚C
0.1
750 ˚C
800 ˚C
0.5
1
1.5
0.2
0.4
650 ˚C
0.4
1
0.8
printed
0.3
0.6
0.2
0.4
700 ˚C
650 ˚C
0.2
0.1
750 ˚C 800 ˚C
850 ˚C
0
0
0
0.5
1
Current Density (A/cm2)
1.5
2
Voltage (V)
1.2
Power Density (W/cm2)
Voltage (V)
0.5
(b)
800 ˚C 850 ˚C
750 ˚C
0
0
0.5
Current Density (A/cm2)
1
0.1
700 ˚C
0
2
1.2
0.3
0.6
0.2
0
0.4
printed
0.8
850 ˚C
0
0
(c)
1
Power Density (W/cm2)
printed
0.8
0.5
1
1.5
Current Density (A/cm2)
2
0.5
(d)
Power Density (W/cm2)
0.4
Voltage (V)
(a)
1
Voltage (V)
1.2
0.5
Power Density (W/cm2)
1.2
0.4
0.8
pasted
0.3
0.6
0.2
0.4
700 ˚C
0.2
650 ˚C
750 ˚C 800 ˚C
0.1
850 ˚C
0
0
0
0.5
1
1.5
2
Current Density (A/cm2)
• comparable performance for both types
• reproducible performance
•Sukeshini, A.M., Cummins, R., Reitz, T.L., and Miller, R.M., “Ink-Jet Printing of Anode Supported SOFC: Comparison of Slurry
Pasted Cathode and Printed Cathode,” Electrochem. and Solid-State Lett., 12(12), pp. B176-179 (2009).
13
Aerosol Jet Printing: Electrolyte, YSZ
Pattern filling –
(spiral fill)
Printed YSZ
Smooth corners/
adjust line width
NiO/YSZ substrate
Pattern filling –
(raster fill)
VM ToolsTM Software
 patterns for material deposition designed using AutoCAD®.
 drawing files are converted into tool paths using VMTools™ (VMT)
 files generated by VMT integrate stage motion with deposition
Optimizing Nozzle-Substrate Distance
Optical Images of printed electrolyte surface
d= 9 mm
d= 10 mm
d= 11 mm
d= 12 mm
d= 5 mm
d= 6 mm
d= 7 mm
d= 8 mm
A gap of up to 8mm between the nozzle and substrate gave
homogenous deposits with no particulates
 longer transit distances lead to coalescence of smaller droplets
•Sukeshini, A.M., Gardner, P., Jenkins, T., Reitz, T.L., and Miller, R.M., “Investigation of Aerosol Jet Deposition Parameters for printing SOFC layers,” Proceedings of the ASME
8th International Conference on Fuel Cell Science, Engineering and Technology, vol. 1, pp 325-332 (2010).
SEM: Surface of Printed Electrolytes
 printed (and sintered) electrolytes were dense
 grain size- 2- 5 µm
•Sukeshini, A.M., Gardner, P., Jenkins, T., Reitz, T.L., and Miller, R.M., “Investigation of Aerosol Jet Deposition Parameters for printing SOFC layers,” Proceedings of the ASME
8th International Conference on Fuel Cell Science, Engineering and Technology, vol. 1, pp 325-332 (2010).
SEM: Cross-sectional View of Electrolytes
20 µm
YSZ
electrolytes with different
thicknesses printed by altering
20 µm
YSZ
•deposition time
•speed
•line spacing
20 µm
YSZ
17
Composite Electrode Layer: Cathode LSM/YSZ
 Mass calibration curves to determine the required gas
flow conditions to establish desired compositions
- use single atomizer and determine individual
deposition rates for a range of gas flow conditions
- plot calibration curves for the two individual
materials
- select gas flow conditions corresponding to
desired compositions
- use dual atomizers simultaneously to print the
composites
18
Material Mixing: Composite Cathode
Vacuum
pump
 individual components directly
mixed on the fly offers potential
for functional gradation
•Sukeshini, A.M., Gardner, P., Jenkins, T., Reitz, T.L., and Miller, R.M., “Investigation of
Aerosol Jet Deposition Parameters for printing SOFC layers,” Proceedings of the ASME
8th International Conference on Fuel Cell Science, Engineering and Technology, vol. 1,
pp 325-332 (2010).
Virtual
Impactor
(LSM)
sheath gas
LSM
Deposition
head
sheath gas
Virtual
Impactor
(YSZ)
Aerosol jet
YSZ
exhaust gas
PCM
substrate
platen
19
Calibration of Deposition Rate for Selection of
Composition
16
YSZ
Deposition rate (mg/min)
14
YSZ
Atomizer1500 sccm
Atomizer2000 sccm
sheath gas- 3000
sccm
12
Atomizer1500 sccm
10
LSM
8
LSM
Atomizer2000 sccm
6
4
600
1100
1600
Exhaust Flow (sccm)
 deposition rate of YSZ > LSM
 deposition rate likely depends on initial particle size
distribution and aerosolized droplet distribution
20
SEM (Back scattered): Microstructure of Composite
LSM/YSZ and LSM Layers
LSM
Cathode layers of different samples
LSM/YSZ
YSZ
 cathode interlayer, LSM/YSZ about 12 µm thick and porous
 LSM layer about 3 µm thick and more dense than desired
 highly reproducible
21
VI Curves for Button Cells (Fuel-H2;
Oxidant- Air)
0.3
(a)
1
0.2
0.6
0.4
0.1
850 ⁰C
0.2
700 ⁰C
650 ⁰C
0
0
0.2
750 ⁰C
800 ⁰C
0
0.4
0.6
0.8
1.2
(b)
(b)
0.8
0.2
0.6
0.4
0.2
700 ⁰C
650 ⁰C
0
0
0.2
750 ⁰C
800 ⁰C
0.1
850 ⁰C
0
0.4
0.6
0.8
Current Density (A/cm2)
LSM
LSM/YSZ
(a)
YSZ
The cells have open circuit voltages
(OCV) ranging from 1.16-1.20V,
depending on the temperature.
0.3
1
Voltage (V)
(a)
1
Power Density (W/cm2)
Voltage (V)
0.8
Power Density (W/cm2)
1.2
LSM
The maximum power density at 850(b)
LSM/YSZ2.
˚C for both cells is 250 mW/cm
YSZ
1
22
Cathode Optimization
Identically printed and processed YSZ, LSM/YSZ
but different LSM printing/processing
LSM
LSM/YSZ
YSZ
(a)
(b)
(c)
(d)
Identical for
all four cells
Ni/YSZ
Ink composition
Thickness
Sintering
Temperature
(a) LSM Ink- 34 wt %, 40 passes, - 1200 ⁰C
(b) LSM Ink- 34 wt %, 60 passes, - 1200 ⁰C
(c) LSM Ink- 17 wt %, 40 passes,
- 1200 ⁰C
(d) LSM Ink- 34 wt %, 40 passes,
- 1150 ⁰C
Aerosol Jet Printing and Microstructure of SOFC Electrolyte and Cathode Layers", ECS Transactions, Vol. 35(1), "Solid Oxide Fuel Cells 12 (SOFC-XII)", pp 2151-2160, (2011).
23
0.6
0.6
0.4
0.4
0.4
0.4
0.2
0.2
0.2
0.2 700 ⁰C
700 ⁰C
00
00
00
11
0.1
0.1
800
800
800⁰C⁰C
800⁰C
⁰C
700
⁰C
700
750
⁰C⁰C⁰C 750
⁰C
750
750 ⁰C
650
⁰C
650 ⁰C
650
650⁰C⁰C
00
11
0.3
40
40
0.3
40passes
passes
40 passes
passes
850
⁰C
sintering
temp.1200
temp.850sintering
⁰C
sintering
temp.-1200
1200⁰C
⁰C
sintering
temp.1200 ⁰C
⁰C
solids
wt
%34
solids
%34
solidswt
wt
%34
solids wt %- 34
0.2
0.2
850
850⁰C⁰C
0.6
0.6
0.4
0.4
0.5
0.5
11
0.5
0.5
1.5
1.5
1.5
1.5
22
0.8
0.8
0.6
0.6
0.6
0.6
0.2
0.2
0.4
0.4
0.4
0.4
00
0.5
0.5
11
0.8
0.8
0.8
0.8
0.6
0.6
850
850⁰C⁰C
800
800⁰C⁰C
0.4
0.4
850
850⁰C
⁰C
0.3
0.3
800
800⁰C
⁰C
0.6
0.6
750
750⁰C⁰C
0.4
0.4
0.4
0.4
0.2
0.2
0.2
0.2
750
750⁰C
⁰C
0.2
0.2
650
700⁰C⁰C
650⁰C
⁰C700
0.5
0.5
0.5
0.5
11
0.8
0.8
0.3
0.3
0.6
0.6
0.2
0.2
0.4
0.4
11
dd
1.5
1.5
22
2
Current
(A/cm
) ) (A/cm
Current
Density
CurrentDensity
Density
(A/cm
Current
Density
(A/cm2))
1.5
1.5
1.5
1.5
22
00
22
1.5
1.5
22
00
22
40
40
40passes
passes
40 passes
passes
sintering
temp.1150
sintering
temp.sintering
temp.1150⁰C
⁰C
sintering1150
temp.1150 ⁰C
⁰C
solids
wt
solids
solidswt
wt%%-34
34
solids
wt %%- 34
34
0.5
0.5
0.5
0.5
0.4
0.4
0.4
0.4
dd
0.8
0.8
0.3
0.3
0.6
0.6
0.2
0.2
0.4
0.4
0.2
0.2
650
650⁰C⁰C
11
11
850
850⁰C⁰C
0.1
0.1
0.2
0.2
00
00
11
700
700⁰C
⁰C
00
00
1.2
1.2
0.4
0.4
0.1
0.1
650
650⁰C⁰C
00
cc
cc
1.2
0.5
1.2
0.5
(V)
Voltage(V)
Voltage
11
40
40
40passes
passes
40 passes
passes
sintering
temp.1200
sintering
temp.sintering
temp.1200⁰C
⁰C
sintering1200
temp.1200 ⁰C
⁰C
solids
wt
solids
solidswt
wt%%-17
17
solids
wt %%- 17
17
0.5
0.5
(W/cm2)2)
Density(W/cm
PowerDensity
Power
1.2
1.2
11
0.2
0.2
22
2
Current
(A/cm
) ) (A/cm
Current
Density
CurrentDensity
Density
(A/cm
Current
Density
(A/cm2))
(W/cm22))
Density (W/cm
Power Density
Power
(V)
Voltage (V)
Voltage
1.2
1.2
(V)
Voltage(V)
Voltage
(V)
Voltage (V)
Voltage
22
2
Current
(A/cm
) ) (A/cm
Current
Density
CurrentDensity
Density
(A/cm
Current
Density
(A/cm2))
0.5
0.5
0.3
0.3
0.1
0.1
00
00
00
0.4
0.4
0.1
0.1
0.2
0.2
00 00
22
0.4
0.4
0.3
60
60
0.3
60passes
passes
60 passes
passes
sintering
temp.1200
sintering
temp.sintering
temp.-1200
1200⁰C
⁰C
sintering
temp.1200 ⁰C
⁰C
solids
wt
%34
solids
%34
solidswt
wt
%34
solids wt %- 34
0.2
0.2
850
850
850⁰C⁰C
850⁰C
⁰C
800
800
800⁰C⁰C
800⁰C
⁰C
750
750
750⁰C⁰C
750⁰C
⁰C
650
650
⁰C
650⁰C⁰C 700
650
⁰C⁰C⁰C 700
700
700⁰C
⁰C
0.1
0.1
0.2
0.2
00
11
0.8
0.8
0.3
0.3
bb
bb
0.5
0.5
(W/cm2)2)
Density(W/cm
PowerDensity
Power
0.8
0.8
0.4
0.4
0.5
0.5
00
650
700
650⁰C
⁰C
700⁰C⁰C
750
⁰C
700
⁰C
700750
⁰C ⁰C
750
800
⁰C
800⁰C
⁰C
750
⁰C
850
850⁰C
⁰C
0.1
0.1
0.1
0.1
00
00
0.5
0.5
0.5
0.5
11
11
0.2
0.2
800
800⁰C
⁰C
00
00
0.3
0.3
(W/cm2)2)
Density(W/cm
PowerDensity
Power
0.8
0.8
aa
aa
1.2
1.2
(W/cm22))
Density (W/cm
Power Density
Power
11
1.2
0.5
1.2
0.5
(W/cm22))
Density (W/cm
Power Density
Power
11
0.5
0.5
(W/cm2)2)
Density(W/cm
PowerDensity
Power
(V)
Voltage(V)
Voltage
1.2
1.2
(W/cm22))
Density (W/cm
Power Density
Power
(V)
Voltage (V)
Voltage
1.2
1.2
(V)
Voltage(V)
Voltage
(V)
Voltage (V)
Voltage
VI Curves of Different Printed Cells
1.5
1.5
22
2
Current
(A/cm
) ) (A/cm
Current
Density
CurrentDensity
Density
(A/cm
Current
Density
(A/cm2))
1.5
1.5
22
00
22
24
Anode Interlayer : Functional Gradation Scheme
Electrolyte, YSZ
50/50
Anode support
non graded
Ni/ YSZ
Electrolyte, YSZ
17/83
33/67
50/50
Anode support
compositionally graded interlayer
with NiO/YSZ.
25
VI Curves for Cells with Graded and Non-graded anode
Functional Layer
Two identical sets
Voltage (V)
0.8
0.2
0.6
non-graded anode
interlayer
0.4
0.1
0.3
1
graded anode interlayer
Voltage (V)
graded anode interlayer
Power Density (W/cm2)
0.3
1
0.8
0.2
0.6
non-graded anode
interlayer
0.4
0.1
0.2
0.2
0
0
0
0.2
0.4
0.6
0.8
1
Current Density (A/cm2)
0
0
0
0.2
0.4
0.6
Current Density (A/cm2)
0.8
1
• reproducible performance
• graded cells show better performance
compared to non-graded cells
26
material submitted for publication
Power Density (W/cm2)
1.2
1.2
Summary, Challenges and Conclusion
 SOFC anode , cathode, and electrolyte components were deposited using
aerosol jet printing
 Layer thickness and microstructure and hence electrochemical
performance of cells incorporating printed components was reproducible
Functionally graded composite anode and composite cathode layers
were printed and incorporated in button cells
Cells with functionally graded anode interlayers performed better
than cells with non-graded anode interlayer
Low voltage scanning electron microscopy was used as a diagnostic
tool for evaluating material mixing and elucidation of phases
Material mixing on anode side requires further optimizationmodify inks, improve processing? Current overall cell performance is
not satisfactory- requires further printing/processing optimization
Additive deposition manufacturing methods enable printing of
dense and porous SOFC Layers. The potential for electrode
patterning, reproducibility of microstructures, and ease of mass
manufacture make these deposition methods very advantageous
compared to traditional methods of screen printing and spraying.
27
Acknowledgments
 Thomas Jenkins (UES Corp.)
Paul Gardner (AFRL)
Frederick Meisenkothen (UES Corp.)
 Optomec Inc., for a grant through a AFRL contract #FA8650-09-C2016
 Dr. Thomas Reitz, Dr. Ryan Miller, AFRL for facilities and funding
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