Structures and fabrication techniques for solid state electrochemical devices
View Patent ↗Porous substrates and associated structures for solid-state electrochemical devices, such as solid-oxide fuel cells (SOFCs), are low-cost, mechanically strong and highly electronically conductive. Some preferred structures have a thin layer of an electrocatalytically active material (e.g., Ni—YSZ) coating a porous high-strength alloy support (e.g., SS- 430 ) to form a porous SOFC fuel electrode. Electrode/electrolyte structures can be formed by co-firing or constrained sintering processes.
1. A solid oxide fuel cell, comprising:
a sintered substrate consisting essentially of a material selected from the group consisting of a porous non-noble transition metal, a porous non-noble transition metal alloy, and a porous cermet incorporating one or more of a non-noble, non-nickel transition metal and a non-noble transition metal alloy;
a first porous electrode material having high electrocatalytic activity on the substrate;
an electrolyte comprising a dense, sintered coating of a ceramic material on the electrode; and
a second porous electrode on the electrolyte.
2. The fuel cell of claim 1 , wherein said substrate material is a porous non-noble transition metal alloy selected from the group consisting of low-chromium ferritic steels and intermediate-chromium ferritic steels.
3. The fuel cell of claim 2 , wherein said substrate material is a low-chromium ferritic steel having has 11-15% Cr.
4. The fuel cell of claim 3 , wherein the low-chromium ferritic is selected from the group consisting of stainless steel types 405, 409 and 410.
5. The fuel cell of claim 2 , wherein said substrate material is an intermediate-chromium ferritic steel having has 16-18% Cr.
6. The fuel cell of claim 5 , wherein the intermediate-chromium ferritic steel is selected from the group consisting of stainless steel types 430 and 434.
7. The fuel cell of claim 1 , wherein said substrate is planar.
8. The fuel cell of claim 1 , wherein said substrate is tubular.
9. The fuel cell of claim 1 , wherein the material having high electrocatalytic activity comprises Ni and an ionic conductor.
10. The fuel cell of claim 9 , wherein the material having high electrocatalytic activity is Ni—YSZ.
11. The fuel cell of claim 1 , wherein said electrolyte coating comprises a material selected from the group consisting of at least one of yttria stabilized zirconia, scandia stabilized zirconia, doped ceria, gadolidia doped ceria, La 0.8 Sr 0.2 Ga 0.85 Mg 0.15 O 2.825 and (Bi 2 O 3 ) 0.75 (Y 2 O 3 ) 0.25 .
12. The fuel cell of claim 11 , wherein said coating comprises at least one YSZ.
13. The fuel cell of claim 12 , wherein said at least one YSZ is selected from the group consisting of (ZrO 2 ) 0.92 (Y 2 O 3 ) 0.08 and (ZrO 2 ) 0.90 (Y 2 O 3 ) 0.10 ).
14. The fuel cell of claim 11 , wherein said coating comprises doped ceria.
15. The fuel cell of claim 14 , wherein said coating is gadolidia doped ceria (CGO).
16. The fuel cell of claim 15 , wherein said gadolidia doped ceria has the formula (CeO 2 ) 0.8 (Gd 2 O 3 ) 0.2 .
17. The fuel cell of claim 1 , wherein the sintered coating is about 1 to 50 microns thick.
18. The fuel cell of claim 1 , wherein the sintered coating about 5 to 20 microns thick.
19. The fuel cell of claim 1 , wherein the dense, sintered coating is no more than 2% porous.
20. The fuel cell of claim 1 , wherein said second electrode comprises a mixed ionic electronic conductor (MIEC).
21. The fuel cell of claim 20 , wherein said MIEC is selected from the group consisting of SrCo 1-x Fe X O 3-δ (0.30≧X≧0.20), La 0.6 Sr 0.4 Co 0.6 Fe 0.4 O 3-δ , La 0.8 Sr 0.2 MnO 3 , La 0.65 Sr 0.30 MnO 3 , La 0.45 Sr 0.55 MnO 3 , Sr 0.7 Ce 0.3 MnO 3-δ , LaNi 0.6 Fe 0.4 O 3 , Sm 0.5 Sr 0.5 CoO 3 and La 1-x Sr x CoO 3-δ .
22. The fuel cell of claim 21 , wherein said MIEC is La 0.6 Sr 0.4 Co 0.6 Fe 0.4 O 3-δ .
23. The fuel cell of claim 1 , further comprising a metallic interconnect bonded to said porous substrate.
24. The fuel cell of claim 1 , wherein the material having high electrocatalytic activity comprises a mixed ionic electronic conductor (MIEC).
25. The fuel cell of claim 24 , wherein said MIEC is selected from the group consisting of SrCo 1-x Fe X O 3-δ (0.30≧X≧0.20), La 0.6 Sr 0.4 Co 0.6 Fe 0.4 O 3-δ , La 0.8 Sr 0 MnO 3 , La 0.65 Sr 0.30 MnO 3 , La 0.45 Sr 0.55 MnO 3 , Sr 0.7 Ce 0.3 MnO 3-δ , LaNi 0.6 Fe 0.4 O 3 , Sm 0.5 Sr 0.5 CoO 3 and La 1-x Sr x CoO 3-δ .
26. The fuel cell of claim 21 , wherein said MIEC is La 0.6 Sr 0.4 Co 0.6 Fe 0.4 O 3-δ .
27. The fuel cell of claim 1 , wherein said second electrode comprises Ni and an ionic conductor.
28. The fuel cell of claim 1 , wherein:
the porous substrate comprises a sintered substrate consisting essentially of an intermediate-chromium ferritic steel;
the first porous electrode material having high electrocatalytic activity on the substrate is a fuel electrode material;
the dense, sintered electrolyte coating is a doped ceria on the fuel electrode; and
the second porous electrode is an air electrode.
29. The fuel cell of claim 28 , wherein the intermediate-chromium ferritic steel is selected from the group consisting of stainless steel types 430 and 434.
30. The fuel cell of claim 29 , wherein the first porous electrode material having high material having high electrocatalytic activity comprises Ni and an ionic conductor.
31. The fuel cell of claim 30 , wherein the porous air electrode comprises a mixed ionic electronic conductor (MIEC).
32. The fuel cell of claim 31 , wherein said MIEC is La 0.6 Sr 0.4 Co 0.6 Fe 0.4 O 3-δ .
33. The fuel cell of claim 32 , further comprising a metallic interconnect bonded to said porous substrate.
34. The fuel cell of claim 1 , wherein:
the porous substrate comprises a sintered substrate consisting essentially of an intermediate-chromium ferritic steel;
the first porous electrode material having high electrocatalytic activity on the substrate is an air electrode material;
the dense, sintered electrolyte coating is a doped ceria on the air electrode; and
the second porous electrode is a fuel electrode.
35. The fuel cell of claim 34 , wherein the intermediate-chromium ferritic steel is selected from the group consisting of stainless steel types 430 and 434.
36. The fuel cell of claim 35 , wherein the material having high electrocatalytic activity comprises a mixed ionic electronic conductor (MIEC).
37. The fuel cell of claim 36 , wherein said MIEC is La 0.6 Sr 0.4 Co 0.6 Fe 0.4 O 3-δ .
38. The fuel cell of claim 37 , wherein the porous fuel electrode comprises Ni and an ionic conductor.
39. The fuel cell of claim 38 , further comprising a metallic interconnect bonded to said porous substrate.