1/38 Synchrotron X-Ray and Pulsed Neutron Imaging of Water Transport Distribution in Fuel Cells 240th ECS Meeting :I01A-11 Gas Diffusion Layer #I01A-1025 Synchrotron X-ray Neutron MPL Pore GDL Water Micrometer Nanometer Millimeter Meter MEGA(material) Cell/Stack Vehicle Quantum beam (X-ray/Neutron) Analysis Catalyst/Membrane Neutron Carbon Ionomer Ice Water Water Topic 1 Topic 2 H 2 H 2 O 2 O 2 H 2 O Yasutaka Nagai (Toyota Central R&D Labs., Inc, Japan) [email protected]
Transcript
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Synchrotron X-Ray and Pulsed Neutron Imaging
of Water Transport Distribution in Fuel Cells
240th ECS Meeting :I01A-11 Gas Diffusion Layer #I01A-1025
Synchrotron X-ray NeutronMPL
Pore
GDL
Water
Micrometer Nanometer Millimeter Meter
MEGA(material) Cell/Stack Vehicle
Quantum beam(X-ray/Neutron)
Analysis
Catalyst/Membrane
Neutron
Carbon
Ionomer
Ice
Water
Water
Topic 1 Topic 2
H2 H2
O2O2
H2O
Yasutaka Nagai (Toyota Central R&D Labs., Inc, Japan)
1. Research Activity on Quantum Beam at Toyota Central R&D Labs.
2. Synchrotron X-ray Imaging
3. Pulsed Neutron Imaging
4. Conclusion
18/38Synchrotron radiation X-ray imaging in FC
Channel
O2H2
H+ H2O
GDL(200 μm)MPL Substrate
200 μm
GDL（Optical microscope）
MPL(SEM)
Carbon
Pore
2 μm
Cell
(sub～)Micron scale pore control
CT : Computed Tomography
Micro-CTNano-CT
Rotation
Sample Cam
era
X-ray
Objective lens
Rotation
Sample
Cam
era
Condenser
X-rayWater
visualization
19/38Water management through MPL modifications
CL
MPL
Substrate
H+
O2
No large pores in/on MPL
nanoscale pores
Oxygen transfer pathways in the MPL region compete with liquid water pathways
CL
Large pores in/on MPL
H+
large pores
Oxygen pathways Liquid water pathways
O2 O2 O2
H2O H2O H2O
Large MPL pores create primary water pathways for effective drainage
Hypothesis 1：Liquid water formed in large pores of MPLHypothesis 2：Large pores in MPL merge liquid water
pathways and decreas liquid water in the substrate
MPL
Substrate
nanoscale pores
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Water vapor
Hypothesis 1：Liquid water formation in large MPL pores
Cooling plate(Peltier device)
Glass capillary MPL carbon
(Vulcal 30 nm)＋PTFE
15 μm
Large pores
Small pores
Condensation by introducing water vapor inside the simulated MPL
MPL carbon particles
Liquid water formation in large pores surrounded by MPL carbon particles
Nano-CTObjective lens
Rotation
Sample
Cam
era
Condenser
X-ray
Small pores
Toyota Beamline
21/38Hypothesis 2：Decrease in liquid water in the GDL
10 mm
O2 inH2 in
O2 outH2 out
Clamp
Operando CT cell
Fast operando tomographicimaging of liquid water
Micro-CT
Rotation
Sample Cam
era
X-ray
CellX-raycamera
X-ray
Rotation stage
CCM
Gasket
GDL
Flow field
An
od
e
Cath
od
e1
0 m
m
Journal of Power Sources 435 (2019) 226809
TOMCAT Beamline
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100 μm 100 μm
In-plane slice images of the MPL region Large pores
Operando CT cell
Fabrication of two types of cells with and without large pores in the MPL on the cathode side
Hypothesis 2：Decrease in liquid water in the GDL
CL
MPL
Substrate
H+
O2
No large pores in/on MPL
nanoscale pores
CL
Large pores in/on MPL
H+
large pores
O2 O2 O2
H2O H2O H2O
MPL
Substrate
nanoscale pores
several microns to several tens of microns
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Rib RibRib Ch. Ch.30x speed
MPL large pores improves drainage by 15%
Top connected
Non connected
Full conected
Bottom connected
Hypothesis 2：Decrease in liquid water in the GDL
No large pores in/on MPL Large pores in/on MPL
CL H+
O2 O2
CL H+
O2 O2
H2O H2O H2O
Rib RibRib Ch. Ch.
Rib
Channel
Different water cluster types
30x speed
Conditions: 1.0 A cm-2, cell temperature 40 oC, dry gas velocities 7.6 m s-1 for air and 5.3 m s-1 for H2, relative humidity 105% for air and 100% for H2, gas pressure 100 kPa.
Current-voltage curves: about 20% improvement
24/38Outline
1. Research Activity on Quantum Beam at Toyota Central R&D Labs.
2. Synchrotron X-ray Imaging
3. Pulsed Neutron Imaging
4. Conclusion
25/38Water in FC：SPring-8/PSI×J-PARC
Gas diffusion layerCatalyst layer Flow channel
Channel
µmnm mm
Selection of ionomerDesign for water-repellent and
Raises the temperature of the stack by generating heat
0℃
20℃
-20℃
Proceedings of the Society of Automotive Engineers of Japan,44(2013)、1021-1026
Several ancillary systems are equipped in commercial FCVs, including a rapid warm-up system, cell monitoring system and various other safety systems.
Ve
hic
le
spe
ed
Ene
rgy
Time
Feedback to cell design, operation mode (fuel efficiency)
Lower cost (elimination of cell monitor, pre-purge system, etc.)
In-situ observation of the behavior of water and ice in cells is important.
Ice Water
27/38Principle of water/ice identification
Approach: Pulsed neutron imaging
Detector
3.5cm
Metal pipe
PulsedNeutron
Y. Higuchi et al., PCCP, 23, (2021), DOI:10.1039/D0CP03887C.
Metal pipe
water
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PulsedNeutron
Principle of water/ice identification
Metal pipe
Water
Approach: Pulsed neutron imaging
Detector
3.5cm
Metal pipe
Neutron energy (meV)
0.1 1 10 100 1000
-ln
(Tra
nsm
itta
nce
)Water（16℃）
Ice(-6℃)
Difference
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PulsedNeutron
Principle of water/ice identification
Approach: Pulsed neutron imaging
Detector
3.5cm
Metal pipe
Neutron energy (meV)
0.1 1 10 100 1000
-ln
(Tra
nsm
itta
nce
)Water（16℃）
Ice(-6℃)
Difference
Molecular mobility
Liquid
Solid
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PulsedNeutron
Principle of water/ice identification
Approach: Pulsed neutron imaging
Detector
3.5cm
Metal pipe
Neutron energy (meV)
0.1 1 10 100 1000
-ln
(Tra
nsm
itta
nce
)Water（16℃）
Ice(-6℃)
Difference
QuantificationIdentification
Blue： Red
-5.5℃ 17℃
Ice Water
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5 mm
-7.0 ˚C 1.2 ˚CMetal tube
720x speedIce
Water/ice identification images throughout the thawing process.
The transition from ice to liquid water could be confirmed by the volume change of water, and the hues in the images changed accordingly from blue to red.
Transmissionimage
Water/Ice identification images
Thawing process
Blue：
Red
Ice
Water
Water
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Detector
300 mm x 300 mm
Large field observation:Pulsed neutron beam with high intensity and large area, and 300 mm x 300 mm CCD camera
Fuel cell
Cooling method:Fluorinert, which is negligible for neutron transmission, flowed as the refrigerant.
PulsedNeutron
Full-size scale imaging
J-PARC, BL22(RADEN)
Thermal insulation chamber
33/38
250 mm
Full-size mock-up sample
Water-filled capillaries
Al foilbag with water
and Ti plate
Full-size scale imaging
＠BL22(RADEN)
Al alloy case
Ti plate with the raised logo of Toyota chuken
Full-size sample was cooled down to -30oC, and carried out liquid water/ice identification by neutron imaging.
Thermal insulation chamber
Detector
PulsedNeutron
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1800x speed
25 cm
0.3 mm/pixel
Full-size scale imaging
Transmission image
Freezing process
Blue：
Red
Ice
Water
35/38Outline
1. Research Activity on Quantum Beam at Toyota Central R&D Labs.
2. Synchrotron X-ray Imaging
3. Pulsed Neutron Imaging
4. Conclusion
36/38Conclusion
Synchrotron X-ray NeutronMPL
Pore
GDL
Water
Micrometer Nanometer Millimeter Meter
MEGA(material) Cell/Stack Vehicle
Quantum beam(X-ray/Neutron)
Analysis
Catalyst/Membrane
Neutron
Carbon
Ionomer
Ice
Water
Water
Topic 1 Topic 2
H2 H2
O2O2
H2O
Toyota Beamline
37/38Acknowledgments
Paul Scherrer Institut, SwitzerlandFelix N. Büchi, Jens Eller, Federica Marone, Hong Xu, Adrian Mularczyk, Thomas Gloor, Marcel Hottiger
J-PARC, JapanTakenao Shinohara, Kazuhisa Isegawa, Yusuke Tsuchikawa, Yoshihiro Matsumoto, Joseph Don Parker, Tetsuya Kai, Hirotoshi Hayashida
Toyota Motor Europe, BelgiumHai P. Nguyen, Keisuke Kishita
Toyota Motor Corp., JapanHirohito Hirata, Hiroaki Takahashi, Atsushi Ida, Tatsuya Kawahara
