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Proton Conducting Electrolysers with Tubular Segmented-in-series Cells for Hydrogen Production Marie-Laure Fontaine1, Einar Vøllestad2, Jonathan M. Polfus1, Wen Xing1, ZuoanLi1, Ragnar Strandbakke2, Christelle Denonville1, Truls Norby2, Rune Bredesen1
1 SINTEF Materials and Chemistry, Norway2 University of Oslo, Norway
2
PCE SOE
2H2OΔH
2H2 + O2
Ceramic Electrolysers: utilizing waste heat
Solid Oxide Electrolyzers (SOE)• Well proven technology• Long term stability challenges
• Delamination of O2-electrode• Higher temperature
Proton Ceramic Electrolysers (PCE)• Less mature technology
• Fabrication and processing challenges• Produces dry H2 directly• Potentially intermediate temperatures
• Slow O2-electrode kinetics
Operating Principles of Proton Ceramic Electrolysers (PCEs)
3 Anode CathodeElectrolyte
2H2O
O2
4H+
Ue-
2H2O O2 + 4H+ +4e-
0 e- + h+ h+e- + h+ 0
RionZel,a Zel,c
Re-
4H+ +4e- 2H2
O2-
4
Development of tubular cathode supported
electrolyte cell
Development and optimization of anodes and current collection
Single tube module development and
testing
Multi-tube module testingAim: 1kW demo
H+
H+
H+
O2H2O
e-
e-
BZY
O2e-
O2
H+
H+
H+
H2O
e-
e-
BZY
O2
e-
H+
H+
H+
O2H2O
e-
e-
BZY
O2e-
O2-
Protonic conductor e- Conductor nanoparticlesMixed Oxygen ion-electronic conductor
a b c
Process integration and evaluation
High temperature electrolyser with novel proton ceramic tubular modules (2014-2017)
Scaling up tubular proton ceramic electrolysers
• Why tubular design?• Simpler sealing technology, lower sealing area• Better stress distribution during transient
conditions• Module design enables to close off a tube /
replace it
• Segmented-in-series cells• Retain high voltage
6
Dip-coatingsuspensions
BZCY-NiO paste
Wet milling of precursors
Solid State Reactive Sintering
Extrusion of BZCY-NiO support
Spray- or dip-coating
Scaling up tubular proton ceramic electrolysers
BaZr0.7Ce0.2Y0.1O3-δ (BZCY72)
7
Dense electrolyte @ 1550°C – 24h1610°C – 6h
Scaling up tubular proton ceramic electrolysers
40 μm
8
Development of new steam electrode materials
1.0 1.1 1.2 1.3 1.4 1.5 1.6
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
GBCF / BZCY BSCF / BCY Pr2NiO4 / BCY LSCF / BCY BGCF / BCY BGLC (x=0) / BZCY BCZF
log
((Rp (Ω
cm2 )
1000/T (K-1)
750 700 650 600 550 500 450 400 350T (°C)
Ba1-xGd0.8La0.2+xCo2O6-δ displays best PCE steam electrode performance(symmetrical disk samples)
0.8 1.0 1.2 1.4 1.6 1.8
-2
-1
0
1
2
X = 0.1 X = 0.5 X = 0* X = 0.3
Log(
Rp,
app(Ω
cm2 ))
1000 / T (K-1)
800 600 400
0.01
0.1
1
10
100
Rp,
app(Ω
cm2 )
T (°C)
0.04 Ωcm2
9
Steam electrode processing
1. Cap and seal using glass-ceramic from CoorsTek
2. Deposit Ba0.7Gd0.8La0.5Co2O6-δ as steam electrode by paint brush
3. Firing in dual atmosphere: 1000 °C
2% O2 outside, 5% H2 inside
Ecell = 1.4 V during firing
4. Gold paste applied as currentcollector
10
Electrolysis with BGLC electrode
0
1
2
3
4
5
550°C600°C650°C
700°C
Current (A)
700°C 650°C 600°C 550°C
H2 p
rodu
ctio
n (N
mL
min
-1)
Farada
ic H 2
prod
uctio
n
0.00 0.25 0.50 0.75 1.00
0 50 100 150 200
1.0
1.5
2.0
700°C600°C550°C 650°C
Pot
entia
l (V
)
Current density (mA cm-2)
Anode:
pO2 = 30 mbarpH2 = 0.3 barptot = 3 bar
ptot = 3 bar
pO2 = 80 mbarpH2O = 1.5 bar
Cathode:1.0 1.5 2.0
40
60
80
100 550°C 600°C 650°C 700°C
Fara
daic
effi
cien
cy (%
)
Potential (V)4 5 6 7 8
3
2
1
0
-1
OCV 50 100 300
Z// (Ωcm
2 )
Z/ (Ωcm2)
bends off
Post-characterization: poor electrode adhesion
11
Steam electrode processing
1. BZCY72-Ba0.5Gd0.8La0.7Co2O6-δ
applied as steam electrode Fired in air at 1200°C for 5h
Infiltrated with nanocrystallineBa0.5Gd0.8La0.7Co2O6-δ
Thin Pt layer current collection
2. Capped and sealed at 1000°C Semi-dual atmosphere to keep BGLC
layer intact
3. NiO reduction at 800°C in 10% H2
for 24h Kept in electrolytic bias during
reduction to avoid re-oxidation
12
Electrolysis with BZCY-BGLC composite electrode
0
5
10
15
20
400°C
500°C
600°C
H2 p
rodu
ctio
n (N
mL
min
-1)
Farada
ic H 2
prod
uctio
n
700°C
0 100 200Current Density (mA cm-2)
0 1 2 3
1.0
1.5
2.0
Anode:
pO2 = 30 mbarpH2 = 0.5 barptot = 3 bar
ptot = 3 bar
pO2 = 30 mbar
400°C
500°C600°C
Vol
tage
(V)
Current (A)
700°C
pH2O = 1.5 barCathode:
4 5 6 7 8 9
-2
0
2
4
Zreal (Ωcm2)
400°C
500°C
600°C
-Zim
700°C
0.3 0.4 0.5 0.6 0.7 0.8 0.9Zreal (Ω)
Improved faradaic efficiency primarily due to enhanced electrode kinetics
13
4 5 6 7 8 9-2
0
2
4
Cell 1
Z// (Ωcm
2 )Z/ (Ωcm2)
Cell 2
600C30 mA cm-2
0 50 100 150 200
1.0
1.5
2.0
Cell 1 Cell 2
Vol
tage
(V)
Current density (mA cm-2)
0
20
40
60
80
100
Fara
daic
effi
cien
cy (%
)
Porous support
H2 electrode
H2O+O2 electrodeNovel interconnects
Electrolyte
14
Segment-in-series: print masking
15
Segment-in-series: print masking
Segment-in-series: print masking
16
Temperature:• 1500 °C• 1525 °C• 1530 °C• 1540 °C• 1550 °C• 1600 °C
• Addition of pore formers (A) in the electrode + reduction of temperature
Support
Various thermal profiles
Dwell:• 2h• 5h• 10h
Pore formers and sintering aid
• Addition of sintering aid + pore formers (B) in the support
RT RT
100°C
350°C
xx°C – xxh
1450°C – xxh
1.6°C/min
1.6°C/min
0.5°C/min
0.5°C/min
RT RT
xx°C – 10h
1.6°C/min 1.6°C/min
Electrolyte
Electrode
NiO-BZCY BZCY
NiO-BZCY BZCY
NiO-BZCYSupport Support
Collar for hang-firing
Segment-in-series: print masking
18
30 µm
300 µm
NiO-BZCY72
BZCY72
BZCY72
BZCY72
NiO-BZCY72
BZCY72
30 µm
30 µm
Segment-in-series: print masking
Conclusions
• Tubular PCEs fabricated• BZCY-NiO tubular cathode support• Spray coated BZCY72 electrolyte• BGLC-BZCY72 steam electrode
• Enhanced faradaic efficiencies observed with improved anode performance• Current densities of 220 mA cm-2 at 600°C obtained with > 80% faradaic efficiency• PCEs may suffer from electronic leakage due to p-type conductivity in oxidizing conditions
0 50 100 150 200
1.0
1.5
2.0
Cell 1 Cell 2
Vol
tage
(V)
Current density (mA cm-2)
0
20
40
60
80
100
Fara
daic
effi
cien
cy (%
)
Acknowledgements
The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement n° 621244.
Marie-Laure Fontaine1, Einar Vøllestad2, Jonathan M. Polfus1, Wen Xing1, Zuoan Li1, Ragnar Strandbakke2, Christelle Denonville1, Truls Norby2, Rune Bredesen1
1 SINTEF Materials and Chemistry, Norway2 University of Oslo, Norway
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