Solid Oxide Electrolysis Cells: Long-term Durability

Transcription

1 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

2 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

3 Risø Ni/YSZ based Solid Oxide Cells Support layer: Ni/YSZ Fuel electrode: Ni/YSZ Electrolyte: YSZ Oxygen electrode: LSM

4 Risø Ni/YSZ based Solid Oxide Cells Support layer: Ni/YSZ Steam electrolysis Fuel electrode: Ni/YSZ Electrolyte: YSZ Oxygen electrode: LSM HO 2 H 2 + ½ O2 Carbon dioxide electrolysis CO 2 CO + ½ O2

5 Risø Ni/YSZ based Solid Oxide Cells Support layer: Ni/YSZ Steam electrolysis Fuel electrode: Ni/YSZ Electrolyte: YSZ Oxygen electrode: LSM HO 2 H 2 + ½ O2 Carbon dioxide electrolysis CO 2 CO + ½ O2 Water Gas Shift (WGS) / Reverse Water Gas Shift (RWGS) H2O + CO H 2 + CO2

6 Performance of Risø Ni/YSZ based Solid Oxide Cells

7 Performance of Risø Ni/YSZ based Solid Oxide Cells 850ºC 50% H 2 O % H 2 25% Ar 1.3 Cell voltage / V i / A.cm -2 H 2 O/H 2 : ASR electrolysis = 0.24 Ωcm 2 ASR fuel cell =0.25 Ωcm 2

8 Performance of Risø Ni/YSZ based Solid Oxide Cells 850ºC 50% H 2 O % H 2 25% Ar 25% CO 2 25% H 2 O 25% CO 25% Ar 50% CO % CO 25% Ar Cell voltage / V i / A.cm -2 H 2 O/H 2 : ASR electrolysis = 0.24 Ωcm 2 ASR fuel cell =0.25 Ωcm 2 CO 2 /CO: ASR electrolysis = 0.34 Ωcm 2 ASR fuel cell =0.32 Ωcm 2

9 Performance of Risø Ni/YSZ based Solid Oxide Cells 850ºC 50% H 2 O % H 2 25% Ar 25% CO 2 25% H 2 O 25% CO 25% Ar 50% CO % CO 25% Ar Cell voltage / V i / A.cm H 2 O/H 2 : ASR electrolysis = 0.24 Ωcm 2 ASR fuel cell =0.25 Ωcm 2 CO 2 /CO: ASR electrolysis = 0.34 Ωcm 2 ASR fuel cell =0.32 Ωcm 2 H 2 O/CO 2 /CO: ASR electrolysis = 0.28 Ω cm 2 ASR fuel cell =0.27 Ωcm 2

10 Performance of Risø Ni/YSZ based Solid Oxide Cells 850ºC 50% CO % CO 25% Ar 50% CO 2 25% H 2 25% Ar 1.3 Cell voltage / V i / A.cm CO 2 /H 2 : ASR electrolysis = 0.28 Ωcm 2 ASR fuel cell =0.27 Ωcm 2 CO 2 /CO: ASR electrolysis = 0.34 Ωcm 2 ASR fuel cell =0.32 Ωcm 2

11 Electrolysis in Solid Oxide Cells Steam electrolysis HO 2 H 2 + O2 Carbon dioxide electrolysis CO 2 CO + O2 Co-electrolysis of carbon dioxide and steam CO + H O CO + H + O H O + CO H + CO 2 2 2

12 Setup for testing Solid Oxide Cells at Risø Cell holder, Top piece Pt foil current collector Pt Mesh O 2 /Air flow Cell H 2 O/H 2 CO 2 /CO Flow Ni Mesh Ni foil current collector Cell holder, Bottom piece Voltage probes (In-plane)

13 Setup for testing Solid Oxide Cells In-plane explanation Inplane voltage Cell voltage Inplane voltage Time Corrosponding cell voltage Inlet Outlet

14 Durability of Ni/YSZ supported Solid Oxide Cells Support layer: Ni/YSZ Fuel electrode: Ni/YSZ Electrolyte: YSZ Oxygen electrode: LSM Low current density degradation (~ upto -1 A/cm 2 at 850ºC) High current density degradation (~ above -1 A/cm 2 at 850ºC)

15 850ºC, A/cm 2, 50% H O / 50% H Electrolysis durability at low current density Steam Cell voltage (V) Passivation Activation Long term degradation Support layer: Ni/YSZ Time (h)

16 Electrolysis durability at low current density Steam Cell voltage (V) Passivation Activation Long term degradation Support layer: Ni/YSZ Time (h) 0.75 In-plane voltage (mv) Time (h) 850ºC, A/cm 2, 50% H O / 50% H

17 850ºC, A/cm 2, 50% H O / 50% H Electrolysis durability at low current density Steam Support layer: Ni/YSZ 1.2 khz 0 h 260 h 1315 h Z'' (Ω cm 2 ) khz 120 Hz 12 Hz 1.2 Hz Δt Z'(f) / ln(f) (Ω cm 2 ) Z' (Ω cm 2 ) t = 260 h Time Maximal degradation: 115 mv Frequence (Hz)

18 850ºC, A/cm 2, 50% H O / 50% H Electrolysis durability at low current density Steam Support layer: Ni/YSZ 1.2 khz 0 h 260 h 1315 h Z'' (Ω cm 2 ) khz 120 Hz 12 Hz 1.2 Hz Z' (Ω cm 2 ) Electrolysis: Si(OH) SiO + H O Impurities Impurities (gas) (ads)

19 850ºC, A/cm 2, 70% CO / 30% CO Electrolysis durability at low current density Carbon dioxide Cell voltage (mv) Support layer: Ni/YSZ Electrolysis time (h)

20 850ºC, A/cm 2, 70% CO / 30% CO Electrolysis durability at low current density Carbon dioxide Cell voltage (mv) Support layer: Ni/YSZ Electrolysis time (h) In-Plane voltage (mv) Electrolysis time (h)

21 850ºC, A/cm 2, 70% CO / 30% CO Electrolysis durability at low current density Carbon dioxide Z'' (Ω cm 2 ) Support layer: Ni/YSZ 1.2 khz 1.2 khz 120 Hz 12 Hz 1.2 Hz 0 h 250 h 500 h Z' (Ω cm 2 ) Δt Z'(f) / ln(f) (Ω cm 2 ) t = 500 h Time Degradation: 175 mv Frequence (Hz)

22 850ºC, A/cm 2, 70% CO / 30% CO Electrolysis durability at low current density Carbon dioxide Z'' (Ω cm 2 ) Support layer: Ni/YSZ 1.2 khz 1.2 khz 120 Hz 12 Hz 1.2 Hz 0 h 250 h 500 h Z' (Ω cm 2 ) Electrolysis: S S (g) (ads)

23 850ºC, A/cm 2, 70% CO / 30% CO Electrolysis durability at low current density Carbon dioxide Z'' (Ω cm 2 ) Support layer: Ni/YSZ 1.2 khz 1.2 khz 120 Hz 12 Hz 1.2 Hz 0 h 250 h 500 h Z' (Ω cm 2 ) Electrolysis: S S (g) (ads) Introduction of H : S + H H S (ads) 2 2 (g) 2

24 850ºC, A/cm 2, 45% CO / 45%H O / 10% H Electrolysis durability at low current density Carbon dioxide + steam 1025 Cell voltage (mv) Time (h)

25 850ºC, A/cm 2, 45% CO / 45%H O / 10% H Electrolysis durability at low current density Carbon dioxide + steam 1025 Cell voltage (mv) Time (h) 0.6 In-plane voltage (mv) Time (h)

26 850ºC, A/cm 2, 45% CO / 45%H O / 10% H Electrolysis durability at low current density Carbon dioxide + steam h 200 h 1340 h Z'' (Ω cm 2 ) khz 1.2 khz 120 Hz 12 Hz 1.2 Hz Z' (Ω cm 2 ) Δt Z'(f) / ln(f) (Ω cm 2 ) t = 200 h Time Maximal degradation: 75 mv Frequence (Hz)

27 850ºC, A/cm 2, 45% CO / 45%H O / 10% H Electrolysis durability at low current density Carbon dioxide + steam h 200 h 1340 h Z'' (Ω cm 2 ) khz 1.2 khz 120 Hz 12 Hz 1.2 Hz Z' (Ω cm 2 ) Electrolysis : Impurities Impurities (gas) (ads)

28 Electrolysis durability at high current density

29 850ºC, A/cm 2, 70%CO / 30% CO Electrolysis durability at high current density Steam or Carbon dioxide (Steam + Carbon dioxide) 2000 Cell voltage (mv) CO 2 electrolysis H 2 O electrolysis Electrolysis time (h) 850ºC, A/cm 2, 50%H 2 O / 50% H 2

30 Electrolysis durability at high current density Steam or Carbon dioxide (Steam + Carbon dioxide) 2000 Cell voltage (mv) CO 2 electrolysis H 2 O electrolysis Electrolysis time (h) 0 h 200 h 400 h Z'' (Ω cm 2 ) Z' (Ω cm 2 ) 850ºC, A/cm 2, 50%H 2 O / 50% H 2 850ºC, A/cm 2, 70%CO / 30% CO

31 850ºC, A/cm 2, 70%CO / 30% CO Electrolysis durability at high current density Steam or Carbon dioxide (Steam + Carbon dioxide) 2000 Cell voltage (mv) CO 2 electrolysis H 2 O electrolysis Electrolysis time (h) 850ºC, A/cm 2, 50%H 2 O / 50% H 2

32 850ºC, A/cm 2, 70%CO / 30% CO Electrolysis durability at high current density Steam or Carbon dioxide (Steam + Carbon dioxide) 2000 Cell voltage (mv) CO 2 electrolysis H 2 O electrolysis Electrolysis time (h) 850ºC, A/cm 2, 50%H 2 O / 50% H 2

33 Summary Degradation at low current densities No structural degradation Degradation related to adsorption of impurities from the applied gasses (or in raw materials) Degradation at high current densities Significant structural degradation Related to the overpotential