Fuel cell with metal alloy contacts that form passivating conductive oxide surfaces
View Patent ↗A metal alloy which when oxidized forms a highly conductive surface oxide layer. Alloy compositions such as, but not limited to, Ti—Nb, Ti—Ta, La—Sr—Cr, and La—Sr—Co are known to form oxide passivation layers which are highly conductive. Such alloys are useful in electrical contact apparatus. An electrical contact element formed of the alloy has a contact surface which when oxidized forms a highly conductive surface layer, thus maintaining electrical conductivity and continuity through the element. The oxide layer may be formed in situ after assembly of the electrical contact or may be provided in an oxidative step during manufacture. The electrical contact may be formed entirely of one or more of such alloys; or may be formed of an inexpensive substrate base metal, such as steel, having one or more of the alloys coated thereupon; or may be formed of a mixture of the base metal and the alloy.
1. A fuel cell comprising an electrical contact that includes a metal alloy containing at least two metal elements, wherein said metal alloy is selected from the group consisting of Y—Ba—Cu, La—Sr—Co, La—Sr—Cr, La—Sr—V, La—Ca—Mn, La—Nd—Ni, Ti—Ta, Ti—Nb, Ti—V, Ti—W, Ti—Mo, Ti—Zr—Ta, Ti—Zr—Nb, Cr—Ta, Cr—Nb, Cr—Ti, Cr—Zr, Sr—V, Cu—Ti, Cu—Fe, Cu—Mn, Cu—Al, Cu—Si, Sn—Sb, Ni—Li, and combinations thereof, said metal alloy being capable of forming a surface metal oxide layer that is conductive.
2. The fuel cell in accordance with claim 1 wherein said fuel cell is a proton exchange membrane fuel cell.
3. The fuel cell in accordance with claim 1 wherein said fuel cell is a solid-oxide fuel cell.
4. The fuel cell in accordance with claim 1 wherein said electrical contact is an electrical terminal.
5. The fuel cell in accordance with claim 1 wherein said electrical contact is an interconnect for an electronic system.
6. The fuel cell in accordance with claim 1 wherein said electrical contact is entirely formed of said metal alloy.
7. The fuel cell in accordance with claim 1 wherein said electrical contact comprises:
a) a conductive core portion formed of base metal; and
b) an outer portion formed of said metal alloy.
8. The fuel cell in accordance with claim 1 wherein said surface metal oxide layer exhibits an electrical surface resistance of no more than about 0.0015 Ωcm 2 .
9. The fuel cell in accordance with claim 1 wherein a first metal element is a main metal and an additional metal element is a dopant.
10. The fuel cell in accordance with claim 9 wherein said main metal is titanium and said dopant is selected from the group consisting of niobium and tantalum.
11. The fuel cell in accordance with claim 9 wherein said main metal is copper and said dopant is selected from the group consisting of aluminum, silicon, iron, manganese, vanadium, and titanium.
12. A fuel cell comprising an electrical contact that includes a metal alloy containing at least two metal elements, wherein said metal alloy is selected from the group consisting of Y—Ba—Cu, La—Sr—Co, La—Sr—Cr, La—Sr—V, La—Ca—Mn, La—Sr—Mn, La—Nd—Ni, Ti—Ta, Ti—Nb, Ti—V, Ti—W, Ti—Mo, Ti—Zr—Ta, Ti—Zr—Nb, Cr—Ta, Cr—Nb, Cr—Ti, Cr—Zr, Sr—V, Cu—Ti, Cu—Fe, Cu—Mn, Cu—Al, Cu—Si, Sn—Sb, Sn—In, Ni—Li, and combinations thereof, said metal alloy being capable of forming a surface metal oxide layer that is conductive, wherein a first metal element is a main metal and an additional metal element is a dopant, and wherein said dopant is present in said alloy in a range between about 1 atom percent and about 50 atom percent.
13. The fuel cell in accordance with claim 12 wherein said dopant is present in said alloy between about 1 atom percent and about 5 atom percent.
14. The fuel cell in accordance with claim 13 wherein said dopant is present in said alloy in a range between about 1 atom percent and about 3 atom percent.
15. A fuel cell comprising an electrical contact that includes a metal alloy containing at least two metal elements, wherein said metal alloy is selected from the group consisting of Y—Ba—Cu, La—Sr—Co, La—Sr—Cr, La—Sr—V, La—Ca—Mn, La—Sr—Mn, La—Nd—Ni, Ti—Ta, Ti—Nb, Ti—V, Ti—W, Ti—Mo, Ti—Zr—Ta, Ti—Zr—Nb, Cr—Ta, Cr—Nb, Cr—Ti, Cr—Zr, Sr—V, Cu—Ti, Cu—Fe, Cu—Mn, Cu—Al, Cu—Si, Sn—Sb, Sn—In, Ni—Li, and combinations thereof, said metal alloy being capable of forming a surface metal oxide layer that is conductive, wherein a first metal element is a main metal and an additional metal element is a dopant, and wherein said dopant has an atomic radius that differs from the atomic radius of said main metal atom by less than about twenty percent.
16. A fuel cell comprising an electrical contact that includes a metal alloy containing at least two metal elements, wherein said metal alloy is selected from the group consisting of Y—Ba—Cu, La—Sr—Co, La—Sr—Cr, La—Sr—V, La—Ca—Mn, La—Sr—Mn, La—Nd—Ni, Ti—Ta, Ti—Nb, Ti—V, Ti—W, Ti—Mo, Ti—Zr—Ta, Ti—Zr—Nb, Cr—Ta, Cr—Nb, Cr—Ti, Cr—Zr, Sr—V, Cu—Ti, Cu—Fe, Cu—Mn, Cu—Al, Cu—Si, Sn—Sb, Sn—In, Ni—Li, and combinations thereof, said metal alloy being capable of forming a surface metal oxide layer that is conductive, wherein a first metal element is a main metal and an additional metal element is a dopant, and wherein a cation of said dopant has a radius that differs from the radius of a cation of said main metal by less than about ten percent.
17. The fuel cell in accordance with claim 16 wherein said dopant cation is in a higher valence state than said main metal cation.
18. The fuel cell in accordance with claim 16 wherein said dopant cation is in a lower valence state than said main metal cation.
19. A fuel cell comprising an electrical contact that includes a metal alloy containing at least two metal elements, wherein said metal alloy is selected from the group consisting of Y—Ba—Cu, La—Sr—Co, La—Sr—Cr, La—Sr—V, La—Ca—Mn, La—Sr—Mn, La—Nd—Ni, Ti—Ta, Ti—Nb, Ti—V, Ti—W, Ti—Mo, Ti—Zr—Ta, Ti—Zr—Nb, Cr—Ta, Cr—Nb, Cr—Ti, Cr—Zr, Sr—V, Cu—Ti, Cu—Fe, Cu—Mn, Cu—Al, Cu—Si, Sn—Sb, Sn—In, Ni—Li, and combinations thereof, said metal alloy being capable of forming a surface metal oxide layer that is conductive, wherein a first metal element is a main metal and an additional metal element is a dopant, and wherein said dopant and said main metal are present as an atomic solid solution.
20. A fuel cell comprising an electrical contact that includes a metal alloy containing at least two metal elements, wherein said metal alloy is selected from the group consisting of Y—Ba—Cu, La—Sr—Co, La—Sr—Cr, La—Sr—V, La—Ca—Mn, La—Sr—Mn, La—Nd—Ni, Ti—Ta, Ti—Nb, Ti—V, Ti—W, Ti—Mo, Ti—Zr—Ta, Ti—Zr—Nb, Cr—Ta, Cr—Nb, Cr—Ti, Cr—Zr, Sr—V, Cu—Ti, Cu—Fe, Cu—Mn, Cu—Al, Cu—Si, Sn—Sb, Sn—In, Ni—Li, and combinations thereof, said metal alloy being capable of forming a surface metal oxide layer that is conductive, wherein a first metal element is a main metal and an additional metal element is a dopant, and wherein oxides formed from said main metal and said dopant form a solid solution with one another.
21. A fuel cell comprising an electrical contact that includes a metal alloy containing at least two metal elements, wherein said metal alloy is selected from the group consisting of Y—Ba—Cu, La—Sr—Co, La—Sr—Cr, La—Sr—V, La—Ca—Mn, La—Nd—Ni, Ti—Ta, Ti—Nb, Ti—V, Ti—W, Ti—Mo, Ti—Zr—Ta, Ti—Zr—Nb, Cr—Ta, Cr—Nb, Cr—Ti, Cr—Zr, Sr—V, Cu—Ti, Cu—Fe, Cu—Mn, Cu—Al, Cu—Si, Sn—Sb, Ni—Li, and combinations thereof, said metal alloy being capable of forming a surface metal oxide layer that is conductive, wherein said fuel cell is a solid-oxide fuel cell.