Sealing assembly for a fuel cell stack and method for manufacturing a fuel cell stack

Abstract

In order to provide a sealing assembly for a fuel cell stack comprising a plurality of fuel cell units, which are arranged consecutively in a stacking direction, wherein each of the fuel cell units comprises a housing with at least one housing part made of a metallic material, which also has an adequate electrical insulation effect and an adequate mechanical strength at a high operating temperature of the fuel cell stack, it is proposed that the sealing assembly comprises at least one intermediate element made of a metallic material, wherein the intermediate element is soldered to a housing part of a first fuel cell unit at at least one location by means of a metal solder and is secured to a housing part of a second fuel cell unit at at least another location, wherein the intermediate element and/or the housing part of the first fuel cell unit is provided with a coating made of a ceramic material.

1 . Sealing assembly for a fuel cell stack comprising a plurality of fuel cell units, which are arranged consecutively in a stacking direction, wherein each of the fuel cell units comprises a housing with at least one housing part made of a metallic material, wherein the sealing assembly comprises at least one intermediate element made of a metallic material, wherein the intermediate element is soldered to a housing part of a first fuel cell unit by means of a metal solder at at least one location and is secured to a housing part of a second fuel cell unit at at least another location; wherein 
 the intermediate element is provided with a coating made of a ceramic material and is soldered to the housing part of the first fuel cell unit at at least one location provided with the ceramic coating, and/or    the housing part of the first fuel cell unit is provided with a coating made of a ceramic material.    
     
     
         2 . Sealing assembly according to  claim 1 , wherein the intermediate element is welded and/or soldered to the housing part of the second fuel cell unit.  
     
     
         3 . Sealing assembly according to  claim 1 , wherein the intermediate element comprises a frame part, which extends in a ring shape around fluid ducts passing through the fuel cell stack in the stacking direction.  
     
     
         4 . Sealing assembly according to  claim 3 , wherein the intermediate element comprises at least one duct boundary part, which is connected to the frame part and either alone or together with the frame part encloses one of the fluid ducts passing through the fuel cell stack.  
     
     
         5 . Sealing assembly according to  claim 4 , wherein the intermediate element respectively has a duct boundary part associated with the respective duct for each fuel gas feed duct and each fuel gas discharge duct.  
     
     
         6 . Sealing assembly according to  claim 4 , wherein the intermediate element respectively comprises a duct boundary part for each oxidising agent feed duct and each oxidising agent discharge duct.  
     
     
         7 . Sealing assembly according to  claim 1 , wherein the intermediate element is formed from a metal sheet.  
     
     
         8 . Sealing assembly according to  claim 1 , wherein the intermediate element is formed from a highly corrosion-resistant steel.  
     
     
         9 . Sealing assembly according to  claim 1 , wherein the ceramic coating is composed of aluminium oxide and/or titanium dioxide and/or zirconium dioxide and/or magnesium oxide.  
     
     
         10 . Sealing assembly according to  claim 1 , wherein the ceramic coating is produced by thermal spraying, in particular by atmospheric plasma spraying, by vacuum plasma spraying or by flame spraying.  
     
     
         11 . Sealing assembly according to  claim 1 , wherein the intermediate element and/or the housing part of the first fuel cell unit is formed from a metal alloy, which contains an oxidisable component.  
     
     
         12 . Sealing assembly according to  claim 11 , wherein the metal alloy contains aluminium and/or zirconium as oxidisable component.  
     
     
         13 . Sealing assembly according to  claim 11 , wherein the ceramic coating is produced by oxidation of an oxidisable component of the metal alloy.  
     
     
         14 . Sealing assembly according to  claim 1 , wherein the ceramic coating has a thickness of approximately 20 μm to approximately 1000 μm.  
     
     
         15 . Sealing assembly according to  claim 1 , wherein the intermediate element is soldered to the housing part of the first fuel cell unit by means of a silver-based solder with added copper.  
     
     
         16 . Sealing assembly according to  claim 1 , wherein the intermediate element is soldered to the housing part of the first fuel cell unit by means of a silver-based solder without added copper.  
     
     
         17 . Sealing assembly according to  claim 16 , wherein the silver-based solder contains an addition of copper oxide.  
     
     
         18 . Sealing assembly according to  claim 1 , wherein the intermediate element is soldered to the housing part of the first fuel cell unit by means of a silver-based solder with added titanium.  
     
     
         19 . Sealing assembly according to  claim 1 , wherein the intermediate element is provided with a ceramic coating both on a side facing the housing part of the first fuel cell unit and on a side facing the housing part of the second fuel cell unit.  
     
     
         20 . Sealing assembly according to  claim 1 , wherein the intermediate element is soldered to the housing part of the second fuel cell unit by means of a metal solder at at least one location provided with a ceramic coating.  
     
     
         21 . Sealing assembly according to  claim 1 , wherein the intermediate element comprises at least two separate intermediate element parts, which are connected to one another.  
     
     
         22 . Sealing assembly according to  claim 21 , wherein at least two separate intermediate element parts are welded and/or soldered to one another.  
     
     
         23 . Sealing assembly according to  claim 21 , wherein at least two separate intermediate element parts are stacked one on top of the other in the stacking direction of the fuel cell stack.  
     
     
         24 . Sealing assembly according to  claim 21 , wherein at least one intermediate element part projects over an adjacent intermediate element part on an inside edge and/or on an outside edge.  
     
     
         25 . Sealing assembly according to  claim 21 , wherein at least two intermediate element parts are connected to one another so that at least one region of one intermediate element part can move relative to a region of the other intermediate element part.  
     
     
         26 . Method for manufacturing a fuel cell stack comprising a plurality of fuel cell units, which are arranged consecutively in a stacking direction, wherein each of the fuel cell units comprises a housing with at least one housing part made of a metallic material, comprising the following process steps: 
 provision of an intermediate element made of a metallic material;    soldering the intermediate element to a housing part of a first fuel cell unit by means of a metal solder at at least one location;    securing the intermediate element to a housing part of a second fuel cell unit at at least another location;    wherein    the intermediate element is provided with a coating made of a ceramic material and is soldered to the housing part of the first fuel cell unit at at least one location provided with the ceramic coating,    and/or    the housing part of the first fuel cell unit is provided with a coating made of a ceramic material.    
     
     
         27 . Method according to one of claims  26 , wherein the intermediate element is welded and/or soldered to the housing part of the second fuel cell unit.  
     
     
         28 . Method according to  claim 26 , wherein the ceramic coating is produced by thermal spraying, in particular by atmospheric plasma spraying, by vacuum plasma spraying or by flame spraying.  
     
     
         29 . Method according to  claim 26 , wherein an intermediate element is used, which is formed from a metal alloy containing an oxidisable component, and the ceramic coating on the intermediate element is produced by oxidation of the oxidisable component of the metal alloy.  
     
     
         30 . Method according to  claim 26 , wherein a housing part is used, which is formed from a metal alloy containing an oxidisable component, and the ceramic coating on the housing part is generated by oxidation of the oxidisable component of the metal alloy.  
     
     
         31 . Method according to  claim 26 , wherein an intermediate element is used, which is provided with a ceramic coating both on a side facing the housing part of the first fuel cell unit and on a side facing the housing part of the second fuel cell unit.  
     
     
         32 . Method according to  claim 26 , wherein the intermediate element is soldered to the housing part of the second fuel cell unit by means of a metal solder at at least one location provided with a ceramic coating.