Claims
- 1. Fuel cell assembly with fuel cells (12), which are arranged in the form of a fuel cell stack (10) and which each comprise an anode (1), a cathode (2), and an electrolyte matrix (3), arranged between said anode and cathode, and which are separated from one another by bipolar plates (4) and are electrically contacted, and which exhibit current collectors (4a) on the anodes (1) for electrically contacting the same and for guiding combustion gas to the same; and current collectors (4b) on the cathodes (2) for electrically contacting the same and for guiding cathode gas to the same; and with means for supplying and carrying away combustion gas and cathode gas to and from the fuel cells (12), as well as means that generate a prestressing force and by means of which the fuel cells (12) inside the fuel cell stack (10) are subjected to a mutual prestressing in the longitudinal direction of the fuel cell stack (10), characterized in that the current collectors (4a, 4b) are formed by means of a porous sintered nickel structure with a solid content ranging from 4% to approximately 75%, preferably 4% to 35%; that the fuel cell stack (10) is arranged horizontally at low prestressing force when in operation; and that the prestressing force of the fuel cells (12) can be variably adapted to the operating state of the fuel cell assembly.
- 2. Fuel cell assembly, as claimed in claim 1, characterized in that the means generating the prestressing force generate a high prestressing force at the startup of the fuel cell assembly and subsequently reduce the prestressing force.
- 3. Fuel cell assembly, as claimed in claim 1 or 2, characterized in that, following startup, the prestressing force is varied in such a manner that the pressure forces in the stack are held essentially equal.
- 4. Fuel cell assembly, as claimed in claim 1, 2, or 3, characterized in that the means generating the prestressing force are formed by means of a device (5, 6, 7, 18) that subjects the fuel cell stack (10) to prestress in its longitudinal direction from the outside.
- 5. Fuel cell assembly, as claimed in claim 1, 2, 3, or 4, characterized in that materials producing an increase in volume are provided in the interior of the fuel cell stack (10).
- 6. Fuel cell assembly, as claimed in claim 5, characterized in that the materials producing an increase in volume are provided in the fuel cells (12).
- 7. Fuel cell assembly, as claimed in claim 6, characterized in that the materials producing an increase in volume suffer an increase in volume at the startup of the fuel cell assembly.
- 8. Fuel cell assembly, as claimed in claim 7, characterized in that the increase in volume is induced by a chemical change in the materials producing an increase in volume.
- 9. Fuel cell assembly, as claimed in claim 8, characterized in that the materials producing an increase in volume are contained in the electrodes (1, 2) of the fuel cells (12).
- 10. Fuel cell assembly, as claimed in claim 9, characterized in that the materials producing an increase in volume are contained in the cathodes (2) of the fuel cells (12).
- 11. Fuel cell assembly, as claimed in claim 10, characterized in that the materials producing an increase in volume are made by means of a porous sintered nickel structure, which is provided on the cathodes (2) and which is oxidized with a simultaneous increase in volume, when the fuel cell assembly is started.
- 12. Fuel cell assembly, as claimed in claim 11, characterized in that the porous sintered nickel structure is in the form of a nickel foam material with a solid content ranging from 4% to approximately 75%, preferably 4% to 35%.
- 13. Fuel cell assembly, as claimed in any one of the claims 1 to 12, characterized in that the electrodes (1, 2) are provided in the form of a layer on the porous structure forming the current collectors (4a, 4b).
- 14. Fuel cell assembly, as claimed in any one of the claims 1 to 13, characterized in that the flow paths are provided in the form of channels (17) for guiding the combustion gas and/or the cathode gas in the porous structure forming the current collectors (4a, 4b).
- 15. Fuel cell assembly, as claimed in any one of the claims 8 to 14, characterized in that the materials producing an increase in volume are contained in the matrices (3) of the fuel cells (12).
- 16. Fuel cell assembly, as claimed in claim 15, characterized in that the matrices (3) of the fuel cells (12) are made of the base materials, which form an aluminate, in particular lithium aluminate; an oxide, in particular zirconium dioxide; and/or a zirconate, in particular lithium zirconate, when the fuel cell assembly is started.
- 17. Fuel cell assembly, as claimed in any one of the claims 7 to 16, characterized in that the prestress generated at the fuel cell stack (10) can be reduced, after the fuel cell assembly is started.
- 18. Fuel cell assembly, as claimed in claim 17, characterized in that the prestress is reduced by balancing the tolerances and setting the components, contained in the fuel cell stack (10), in particular in the fuel cells (12).
- 19. Fuel cell assembly, as claimed in any one of the claims 4 to 18, characterized in that the prestress is reduced by reducing the prestress applied to the fuel cell stack (10) from the outside.
Priority Claims (1)
Number |
Date |
Country |
Kind |
100 56 534.4 |
Nov 2000 |
DE |
|
Parent Case Info
[0001] This application claims the priority of International Application No. PCT/EP01/13091, filed Nov. 13, 2001, and German Patent Document No. 100 56 534.4, filed Nov. 15, 2000, the disclosures of which are both incorporated by reference herein.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/EP01/13091 |
11/13/2001 |
WO |
|