Solid oxide fuel cells with cathode functional layers
In various embodiments, a solid oxide fuel cell features a functional layer for reducing interfacial resistance between the cathode and the solid electrolyte.
1. A solid oxide fuel cell comprising:
a cathode;
a solid electrolyte for conducting oxygen ions from the cathode to an anode;
an anode for reacting oxygen ions from the solid electrolyte with a hydrogen-containing fuel; and
disposed between the cathode and the solid electrolyte, a functional layer for improving conduction within the solid oxide fuel cell,
wherein (i) the functional layer contains cobalt, (ii) the solid electrolyte comprises a first layer and a second layer disposed on the first layer, (iii) the first layer of the solid electrolyte contains cobalt, and (iv) the second layer of the solid electrolyte is free of cobalt.
2. The solid oxide fuel cell of claim 1 , wherein the functional layer comprises at least one of cobalt-doped gadolinium-doped ceria or cobalt-doped samarium-doped ceria.
3. The solid oxide fuel cell of claim 1 , wherein the cathode comprises at least one of lanthanum strontium cobalt ferrite, lanthanum strontium manganite, lanthanum strontium cobaltite, barium strontium cobalt ferrite, samarium strontium cobaltite, samarium-doped ceria, or gadolinium-doped ceria.
4. The solid oxide fuel cell of claim 1 , wherein the solid electrolyte comprises at least one of yttria-stabilized zirconia, scandia-stabilized zirconia, lanthanum strontium magnesium gallate, samarium-doped ceria, or gadolinium-doped ceria.
5. The solid oxide fuel cell of claim 1 , wherein the anode comprises a composite comprising nickel and yttria-stabilized zirconia.
6. The solid oxide fuel cell of claim 1 , wherein a thickness of the functional layer ranges from approximately 1 μm to approximately 10 μm.
7. The solid oxide fuel cell of claim 1 , wherein the functional layer contains cobalt at a composition ranging from approximately 0.5 mol % to 5 mol %.
8. The solid oxide fuel cell of claim 1 , wherein a concentration of cobalt in the first layer of the solid electrolyte is less than a concentration of cobalt in the functional layer.
9. The solid oxide fuel cell of claim 1 , wherein the hydrogen-containing fuel comprises at least one of hydrogen or a hydrocarbon.
10. A method of electrochemically converting a hydrogen-containing fuel to electricity, at an operating temperature, using a solid oxide fuel cell comprising (i) a cathode, (ii) an anode, (iii) a solid electrolyte disposed between the anode and the cathode, and (iv) a functional layer disposed between the cathode and the solid electrolyte, wherein a thickness of the functional layer is selected from the range of 0.1 μm to 20 μ.m, the method comprising:
selecting as the operating temperature a temperature less than 550° C. and greater than 400° C. when the thickness of the functional layer is less than 5 μm;
selecting as the operating temperature a temperature greater than 550° C. when the thickness of the functional layer is greater than 5 μm;
ionizing oxygen at the cathode, thereby producing oxygen ions;
conducting the oxygen ions from the cathode to the anode; and
reacting the oxygen ions with the fuel at the anode at the operating temperature, thereby generating electricity,
wherein (i) the functional layer contains cobalt, (ii) the solid electrolyte comprises a first layer and a second layer disposed on the first layer, (iii) the first layer of the solid electrolyte contains cobalt, and (iv) the second layer of the solid electrolyte is free of cobalt.
11. The method of claim 10 , wherein (i) the thickness of the functional layer is greater than 5 μm, and (ii) the operating temperature is less than 750° C.
12. The method of claim 10 , wherein the functional layer comprises at least one of cobalt-doped gadolinium-doped ceria or cobalt-doped samarium-doped ceria.
13. The method of claim 10 , wherein the functional layer contains cobalt at a composition ranging from approximately 0.5 mol % to 5 mol %.
14. The method of claim 10 , wherein a concentration of cobalt in the first layer of the solid electrolyte is less than a concentration of cobalt in the functional layer.
15. The method of claim 10 , wherein the hydrogen-containing fuel comprises at least one of hydrogen or a hydrocarbon.
16. The method of claim 10 , wherein the solid electrolyte comprises at least one of samarium-doped ceria, gadolinium-doped ceria, yttria-doped ceria, neodymium-doped ceria, praseodymium-doped ceria, or lanthanum-doped ceria.
17. The method of claim 10 , wherein a concentration of cobalt in the first layer of the solid electrolyte is graded.
18. The solid oxide fuel cell of claim 1 , wherein a concentration of cobalt in the first layer of the solid electrolyte is graded.
19. The solid oxide fuel cell of claim 1 , wherein the first layer of the solid electrolyte is disposed between the functional layer and the second layer of the solid electrolyte.
20. The method of claim 10 , wherein the first layer of the solid electrolyte is disposed between the functional layer and the second layer of the solid electrolyte.
21. A method of electrochemically converting a hydrogen-containing fuel to electricity, at an operating temperature, using a solid oxide fuel cell comprising (i) a cathode, (ii) an anode, (iii) a solid electrolyte disposed between the anode and the cathode, and (iv) a functional layer disposed between the cathode and the solid electrolyte, the method comprising:
ionizing oxygen at the cathode, thereby producing oxygen ions;
conducting the oxygen ions from the cathode to the anode; and
reacting the oxygen ions with the fuel at the anode at the operating temperature, thereby generating electricity,
wherein (i) the functional layer contains cobalt, (ii) the solid electrolyte comprises a first layer and a second layer disposed on the first layer, (iii) the first layer of the solid electrolyte contains cobalt, and (iv) the second layer of the solid electrolyte is free of cobalt.
22. The method of claim 21 , wherein the functional layer comprises at least one of cobalt-doped gadolinium-doped ceria or cobalt-doped samarium-doped ceria.
23. The method of claim 21 , wherein the functional layer contains cobalt at a composition ranging from approximately 0.5 mol % to 5 mol %.
24. The method of claim 21 , wherein a concentration of cobalt in the first layer of the solid electrolyte is less than a concentration of cobalt in the functional layer.
25. The method of claim 21 , wherein a concentration of cobalt in the first layer of the solid electrolyte is graded.
26. The method of claim 21 , wherein the first layer of the solid electrolyte is disposed between the functional layer and the second layer of the solid electrolyte.