Fuel cell and use of iron-based alloys for the construction...

Details Fuel cell and use of iron-based alloys for the construction... Fuel cell and use of iron-based alloys for the construction...

1999-07-20

2001-10-09

Brouillette, Gabrielle (Department: 1745)

Chemistry: electrical current producing apparatus, product, and

Having earth feature

C429S006000, C429S047000

Reexamination Certificate

active

06300001

ABSTRACT:

The invention relates to a fuel cell that comprises a membrane electrode unit, two current collectors and/or a cell frame or a bipolar plate, whereby at least one solid constructive part is characterized by low weight and high corrosion resistance of the material used.
BACKGROUND OF THE INVENTION
Up to now, cell frames, bipolar plates, collector plates, and/or other solid constructive parts of fuel cells, in particular of low-temperature fuel cells such as the PEM fuel cell, have been known that are manufactured from graphite or other carbonaceous materials. The thickness of the plates ranges from at least 2 to 2.5 mm, due to the gas and liquid distribution structure, and, despite the low density of the plate material the plate cause the cells to have a comparatively high weight and large volume.
In EP 0 629 015 Al, the following alloys or metals are disclosed as materials for bipolar or collector plates: aluminum, titanium or alloys thereof, zirconium, niobium, tantalum, or alloys of these five elements. In addition, it is there disclosed that these elements can be passivated by protective electrically insulating oxides, and that, alternatively to the above-named metals, the plates can also be made of more corrosion-resistant materials such as graphite, high-alloy stainless steel, or nickel-chromium alloys. However, more precise statements concerning the composition of well-suited alloys of these metals have not been known up to now.
For mass production, the carbonaceous materials are too heavy and too expensive in the manufacture of cell frames, current collectors and/or bipolar plates, etc. In turn, the metals have an excessively high susceptibility to corrosion, and, due to their passivation by oxide layer formation, have excessively high losses during current transport inside the fuel cell.
Therefore there is a need for a fuel cell suitable for mass production, in which the collector plates and/or cell frames and/or other constructive parts of the fuel cell are made of a material that
is economical and corrosion-resistant (even in direct contact with the acid membrane electrolytes), and
is easily transformable (good deep-drawing quality), and
has a low contact resistance, and finally
has a low thickness and, above all, a low weight in the processing into plates, despite the gas and liquid distribution structure.
The subject matter of the invention is a fuel cell that comprises a membrane electrode unit, two current collectors and,or a cell frame and/or a bipolar plate, whereby the material of at least one of the solid constructive parts is made of an Fe-based material selected from the alloys with the following compositions:
C content:
0-0.06
weight %
Si content:
0-2
weight %
Cr content:
8.25-46.5
weight %
Mo content:
1.25-14.0
weight %
Ni content:
2.25-40.5
weight %
Cu content:
0-4.0
weight %
Mn content:
0-13
weight %
N content:
0.02-1
weight %
Nb content:
0-0.5
weight %
P content:
0-0.09
weight %
S content:
0-0.06
weight %
Fe content:
remainder to 100
weight %
As an iron-based material, Fe is in principle the main component of the inventively used alloy, whereby the designation main component cannot be defined by percent indications, but rather is regarded relative to the other components.
Moreover, the subject matter of the present invention is the use of an iron-based alloy with one of the above-named compositions in the construction of a fuel cell.


REFERENCES:
patent: 4448856 (1984-05-01), Zukerbrod
patent: 5399438 (1995-03-01), Tateishi
patent: 5565167 (1996-10-01), Fujimoto et al.
patent: 5624769 (1997-04-01), Li
patent: 6114058 (2000-09-01), Jodkins
patent: 0 629 015 A1 (1994-04-01), None
patent: 05339679A (1993-12-01), None
patent: 05079060 (1993-12-01), None
patent: 06010099A (1994-01-01), None
patent: 2000239806A (2000-09-01), None
patent: WO9925890A1 (1998-11-01), None
Patent Abstracts of Japan Application No. 05079060 dated Mar. 12, 1993.

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