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Solid Oxide Electrolysis Cells: Long-term Durability Steam electrolysis Carbon dioxide electrolysis Co-electrolysis of steam and carbon dioxide
Sune D Ebbesen,
Christopher Graves, Anne Hauch, Søren H Jensen, Ruth Knibbe, and Mogens Mogensen
Fuel Cells and Solid State Chemistry Division, Risø National Laboratory for Sustainable Energy,
The Technical University of Denmark
Outline
•Risø Ni/YSZ based Solid Oxide Cells
•Performance of Risø Ni/YSZ based Solid Oxide Cells
•Setup for testing Solid Oxide Cells at Risø
• Influence if impurities
•Electrolysis durability at low current density — Steam — Carbon dioxide — Carbon dioxide + steam
•Electrolysis durability at high current density — Steam, Carbon dioxide or Carbon dioxide + steam
•Summary
Risø Ni/YSZ based Solid Oxide Cells
Support layer: Ni/YSZ
Fuel electrode: Ni/YSZElectrolyte: YSZOxygen electrode: LSM
• Steam electrolysis
• Carbon dioxide electrolysis
→2 2CO CO + ½ O
→2 2 2H O H + ½ O
Risø Ni/YSZ based Solid Oxide Cells
Support layer: Ni/YSZ
Fuel electrode: Ni/YSZElectrolyte: YSZOxygen electrode: LSM
• Steam electrolysis
• Carbon dioxide electrolysis
• Water Gas Shift (WGS) / Reverse Water Gas Shift (RWGS)
2 2 2H O + CO H + CO
→2 2CO CO + ½ O
→2 2 2H O H + ½ O
Risø Ni/YSZ based Solid Oxide Cells
Support layer: Ni/YSZ
Fuel electrode: Ni/YSZElectrolyte: YSZOxygen electrode: LSM
0.5
0.7
0.9
1.1
1.3
1.5
-1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6
i / A.cm-2
Cel
l vol
tage
/ V
50% H2O – 25% H2 – 25% Ar
H2 O/H2 : ASRelectrolysis = 0.24 Ωcm2 ASRfuel cell = 0.25 Ωcm2
— 850ºC Performance of Risø Ni/YSZ based Solid Oxide Cells
0.5
0.7
0.9
1.1
1.3
1.5
-1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6
i / A.cm-2
Cel
l vol
tage
/ V
50% H2O – 25% H2 – 25% Ar25% CO2 – 25% H2O – 25% CO – 25% Ar50% CO2 – 25% CO – 25% Ar
H2 O/H2 : ASRelectrolysis = 0.24 Ωcm2 ASRfuel cell = 0.25 Ωcm2
CO2 /CO: ASRelectrolysis = 0.34 Ωcm2 ASRfuel cell = 0.32 Ωcm2
— 850ºC Performance of Risø Ni/YSZ based Solid Oxide Cells
H2 O/H2 : ASRelectrolysis = 0.24 Ωcm2 ASRfuel cell = 0.25 Ωcm2
CO2 /CO: ASRelectrolysis = 0.34 Ωcm2 ASRfuel cell = 0.32 Ωcm2
H2 O/CO2 /CO: ASRelectrolysis = 0.28 Ω
cm2 ASRfuel cell = 0.27 Ωcm2
0.5
0.7
0.9
1.1
1.3
1.5
-1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6
i / A.cm-2
Cel
l vol
tage
/ V
50% H2O – 25% H2 – 25% Ar25% CO2 – 25% H2O – 25% CO – 25% Ar50% CO2 – 25% CO – 25% Ar
— 850ºC Performance of Risø Ni/YSZ based Solid Oxide Cells
0.5
0.7
0.9
1.1
1.3
1.5
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6
i / A.cm-2
Cel
l vol
tage
/ V
50% CO2 – 25% CO – 25% Ar50% CO2 – 25% H2 – 25% Ar
CO2 /H2 : ASRelectrolysis = 0.28 Ωcm2 ASRfuel cell = 0.27 Ωcm2
CO2 /CO: ASRelectrolysis = 0.34 Ωcm2 ASRfuel cell = 0.32 Ωcm2
— 850ºC Performance of Risø Ni/YSZ based Solid Oxide Cells
Electrolysis in Solid Oxide Cells
• Steam electrolysis
• Carbon dioxide electrolysis
• Co-electrolysis of carbon dioxide and steam
2 2CO CO + O→
2 2 2H O H + O→
→2 2 2 2
2 2 2
CO + H O CO + H + O
H O + CO H + CO
Setup for testing Solid Oxide Cells at Risø
Cell holder,Bottom piece
O2/Air flow
Ni foilcurrent collector
Ni Mesh
Cell holder,Top piece
Pt foilcurrent collector
Cell
H2O/H2CO2/CO
Flow
Pt Mesh
Voltage probes(In-plane)
0.00.20.40.60.81.01.21.41.6
0 5 10 15 20 25 30 3500.20.40.60.811.21.41.61.8
Inpl
ane
volta
ge
Cor
rosp
ondi
ng c
ell v
olta
ge
Time
Inplane voltage
Cell voltage
Setup for testing Solid Oxide Cells In-plane explanation
Inlet Outlet
Durability of Ni/YSZ supported Solid Oxide Cells
Support layer: Ni/YSZ
Fuel electrode: Ni/YSZElectrolyte: YSZOxygen electrode: LSM
• Low current density degradation (~ upto -1 A/cm2 at 850ºC)
• High current density degradation (~ above -1 A/cm2 at 850ºC)
Electrolysis durability at low current density — Steam
Support layer: Ni/YSZ
1.10
1.15
1.20
1.25
1.30
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400Time (h)
Cell
volta
ge (V
) Passivation Activation Long term degradation
850ºC, -0.50 A/cm2, 50% H2 O / 50% H2
Electrolysis durability at low current density — Steam
Support layer: Ni/YSZ
1.10
1.15
1.20
1.25
1.30
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400Time (h)
Cell
volta
ge (V
) Passivation Activation Long term degradation
-0.25
0.00
0.25
0.50
0.75
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400
Time (h)
In-p
lane
vol
tage
(mV
)
850ºC, -0.50 A/cm2, 50% H2 O / 50% H2
Electrolysis durability at low current density — Steam
Support layer: Ni/YSZ
850ºC, -0.50 A/cm2, 50% H2 O / 50% H2
-0.20
-0.15
-0.10
-0.05
0.00
0.050 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Z' (Ω ·cm2)
Z'' (Ω
·cm
2 )
12 Hz1.2 Hz
120 Hz
1.2 kHz
1.2 kHz
0 h260 h1315 h
0
10
2030
40
50
6070
80
90
1 10 100 1000 10000 100000Frequence (Hz)
Δt ∂
Z'(f)
/ ∂l
n(f)
( Ω·c
m2 )
t = 260 h
TimeMaximal degradation: 115 mV
-0.20
-0.15
-0.10
-0.05
0.00
0.050 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Z' (Ω ·cm2)
Z'' (Ω
·cm
2 )
12 Hz1.2 Hz
120 Hz
1.2 kHz
1.2 kHz
0 h260 h1315 h
Electrolysis durability at low current density — Steam
Support layer: Ni/YSZ
850ºC, -0.50 A/cm2, 50% H2 O / 50% H2
→
4 2 2
(gas) (ads)
Electrolysis:Si(OH) SiO + H O
Impurities Impurities
Electrolysis durability at low current density — Carbon dioxide
Support layer: Ni/YSZ
850ºC, -0.25 A/cm2, 70% CO2 / 30% CO
1000
1050
1100
1150
1200
1250
0 100 200 300 400 500 600 700 800
Electrolysis time (h)
Cell
volta
ge (m
V)
Support layer: Ni/YSZ
0.00
0.15
0.30
0.45
0.60
0.75
0.90
0 100 200 300 400 500 600 700 800
Electrolysis time (h)
In-P
lane
vol
tage
(mV)
1000
1050
1100
1150
1200
1250
0 100 200 300 400 500 600 700 800
Electrolysis time (h)
Cell
volta
ge (m
V)
850ºC, -0.25 A/cm2, 70% CO2 / 30% CO
Electrolysis durability at low current density — Carbon dioxide
Support layer: Ni/YSZ
850ºC, -0.25 A/cm2, 70% CO2 / 30% CO
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
0.05
0.100 0.2 0.4 0.6 0.8 1
Z' (Ω ·cm2)
Z'' (Ω
·cm
2 )
12 Hz1.2 Hz
120 Hz1.2 kHz
1.2 kHz
0 h250 h500 h
020406080
100120140160180200
1 10 100 1000 10000 100000Frequence (Hz)
Δt ∂
Z'(f)
/ ∂l
n(f)
( Ω·c
m2 )
Timet = 500 h
Electrolysis durability at low current density — Carbon dioxide
Degradation: 175 mV
Support layer: Ni/YSZ
→(g) (ads)
Electrolysis:S S
850ºC, -0.25 A/cm2, 70% CO2 / 30% CO
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
0.05
0.100 0.2 0.4 0.6 0.8 1
Z' (Ω ·cm2)
Z'' (Ω
·cm
2 )
12 Hz1.2 Hz
120 Hz1.2 kHz
1.2 kHz
0 h250 h500 h
Electrolysis durability at low current density — Carbon dioxide
Support layer: Ni/YSZ
→
→
(g) (ads)
2
(ads) 2 2 (g)
Electrolysis:S S
Introduction of H :S + H H S
850ºC, -0.25 A/cm2, 70% CO2 / 30% CO
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
0.05
0.100 0.2 0.4 0.6 0.8 1
Z' (Ω ·cm2)
Z'' (Ω
·cm
2 )
12 Hz1.2 Hz
120 Hz1.2 kHz
1.2 kHz
0 h250 h500 h
Electrolysis durability at low current density — Carbon dioxide
875
900
925
950
975
1000
1025
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400Time (h)
Cell
volta
ge (m
V)
850ºC, -0.25 A/cm2, 45% CO2 / 45%H2 O / 10% H2
Electrolysis durability at low current density — Carbon dioxide + steam
875
900
925
950
975
1000
1025
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400Time (h)
Cell
volta
ge (m
V)
-0.2
0.0
0.2
0.4
0.6
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400
Time (h)
In-p
lane
vol
tage
(mV
)
850ºC, -0.25 A/cm2, 45% CO2 / 45%H2 O / 10% H2
Electrolysis durability at low current density — Carbon dioxide + steam
850ºC, -0.25 A/cm2, 45% CO2 / 45%H2 O / 10% H2
-0.20
-0.15
-0.10
-0.05
0.00
0.050 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Z' (Ω ·cm2)
Z'' (Ω
·cm
2 )0 h200 h1340 h
12 Hz1.2 Hz
120 Hz1.2 kHz
1.2 kHz
0
20
40
60
80
100
120
140
1 10 100 1000 10000 100000Frequence (Hz)
Δt ∂
Z'(f)
/ ∂l
n(f)
( Ω·c
m2 )
Time
t = 200 h
Electrolysis durability at low current density — Carbon dioxide + steam
Maximal degradation: 75 mV
(gas) (ads)
Electrolysis :Impurities Impurities →
850ºC, -0.25 A/cm2, 45% CO2 / 45%H2 O / 10% H2
-0.20
-0.15
-0.10
-0.05
0.00
0.050 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Z' (Ω ·cm2)
Z'' (Ω
·cm
2 )0 h200 h1340 h
12 Hz1.2 Hz
120 Hz1.2 kHz
1.2 kHz
Electrolysis durability at low current density — Carbon dioxide + steam
Electrolysis durability at high current density — Steam or Carbon dioxide (Steam + Carbon dioxide)
1400
1500
1600
1700
1800
1900
2000
0 50 100 150 200 250 300 350 400 450
Electrolysis time (h)
Cel
l vol
tage
(mV)
CO2 electrolysis
H2O electrolysis
850ºC, -1. 50 A/cm2, 50%H2 O / 50% H2
850ºC, -1. 50 A/cm2, 70%CO2 / 30% CO
Electrolysis durability at high current density — Steam or Carbon dioxide (Steam + Carbon dioxide)
1400
1500
1600
1700
1800
1900
2000
0 50 100 150 200 250 300 350 400 450
Electrolysis time (h)
Cel
l vol
tage
(mV)
CO2 electrolysis
H2O electrolysis
850ºC, -1. 50 A/cm2, 50%H2 O / 50% H2
850ºC, -1. 50 A/cm2, 70%CO2 / 30% CO
-0.15
-0.10
-0.05
0.00
0.050 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
Z' (Ω ·cm2)
Z'' (Ω
·cm
2 )
0 h200 h400 h
1400
1500
1600
1700
1800
1900
2000
0 50 100 150 200 250 300 350 400 450
Electrolysis time (h)
Cel
l vol
tage
(mV)
CO2 electrolysis
H2O electrolysis
850ºC, -1. 50 A/cm2, 50%H2 O / 50% H2
850ºC, -1. 50 A/cm2, 70%CO2 / 30% CO
Electrolysis durability at high current density — Steam or Carbon dioxide (Steam + Carbon dioxide)
1400
1500
1600
1700
1800
1900
2000
0 50 100 150 200 250 300 350 400 450
Electrolysis time (h)
Cel
l vol
tage
(mV)
CO2 electrolysis
H2O electrolysis
850ºC, -1.50 A/cm2, 50%H2 O / 50% H2
850ºC, -1.50 A/cm2, 70%CO2 / 30% CO
Electrolysis durability at high current density — Steam or Carbon dioxide (Steam + Carbon dioxide)