Method for conditioning membrane-electrode-units for fuel cells

Abstract

The present invention relates to a method for the conditioning of membrane electrode assemblies for fuel cells in which the output of the membrane electrode assemblies used can be increased and therefore the efficiency of the resulting polymer electrolyte membrane fuel cells can be improved.

1 - 19 . (canceled) 
     
     
         20 . A membrane electrode assembly comprising
 A) at least one polymer electrolyte matrix in the form of a membrane containing at least one oxo acid of phosphorus and/or sulphur and at least one polymer with at least one heteroatom selected from the group of nitrogen, oxygen and/or sulphur; and   B) at least two electrodes;   wherein the water content of the polymer electrolyte matrix is 20% by weight or less.   
     
     
         21 . The membrane electrode assembly of  claim 20 , wherein the polymer electrolyte matrix is an alkaline polymer and in turn contains at least one polymer with at least one heteroatom selected from the group of nitrogen, oxygen and/or sulphur. 
     
     
         22 . The electrode of  claim 21 , wherein the alkaline polymer is a polymer comprising at least one nitrogen atom. 
     
     
         23 . The membrane electrode assembly of  claim 21 , wherein the alkaline polymer is a polyphosphazene, polyimine, polyisocyanide, polyetherimine, polyamide, polyhydrazide, polyurethane, polyimide, polyazole or polyazine, or a mixture thereof. 
     
     
         24 . The membrane electrode assembly of  claim 21 , wherein the alkaline polymer is a polymer based on polyazole, which contains the recurring azole units of the general formula (I) and/or (II) and/or (III) and/or (IV) and/or (V) and/or (VI) and/or (VII) and/or (VIII) and/or (IX) and/or (X) and/or (XI) and/or (XII) and/or (XIII) and/or (XIV) and/or (XV) and/or (XVI) and/or (XVII) and/or (XVIII) and/or (XIX) and/or (XX) and/or (XXI) and/or (XXII) 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
       wherein
 Ar are the same or different and are each a tetravalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 Ar 1  are the same or different and are each a divalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 Ar 2  are the same or different and are each a divalent or trivalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 Ar 3  are the same or different and are each a trivalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 Ar 4  are the same or different and are each a trivalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 Ar 5  are the same or different and are each a tetravalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 Ar 6  are the same or different and are each a divalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 Ar 7  are the same or different and are each a divalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 Ar 8  are the same or different and are each a trivalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 Ar 9  are the same or different and are each a divalent or trivalent or tetravalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 Ar 10  are the same or different and are each a divalent or trivalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 Ar 11  are the same or different and are each a divalent aromatic or heteroaromatic group which may be mononuclear or polynuclear, 
 X are the same or different and are each oxygen, sulphur or an amino group which bears a hydrogen atom, a group having 1-20 carbon atoms, 
 R are identical or different and represent hydrogen, an alkyl group and an aromatic group, with the proviso that R in the formula (XX) is not hydrogen, and 
 n and m are identical or different and are each an integer greater than or equal to 10. 
 
     
     
         25 . The membrane electrode assembly of  claim 24 , wherein X are the same or different and are each oxygen, sulphur or an amino group which bears a hydrogen atom, a group having 1-20 carbon atoms, wherein the group having 1-20 carbon atoms is a branched or unbranched alkyl or alkoxy group, or an aryl group as further radical. 
     
     
         26 . The membrane electrode assembly of  claim 24 , wherein n and m are identical or different and are each an integer or equal to 100 
     
     
         27 . The membrane electrode assembly of  claim 24 , wherein the polymer is a copolymer or a blend which contains at least two units of the formulae (I) to (XXII) which differ from one another. 
     
     
         28 . The membrane electrode assembly of  claim 24 , wherein the polymer is in the form of block copolymers, random copolymers, periodic copolymers and/or alternating polymers. 
     
     
         29 . The membrane electrode assembly of  claim 20 , wherein the polymer electrolyte matrix further comprises a further polymer. 
     
     
         30 . The membrane electrode assembly of  claim 29 , wherein said further polymer is at least one of the following polymers selected from the group consisting of polysulphone, polyethersulphone, polyaryl ketone, polyether ketone, polyether ketone ketone, polyether ether ketone, polyether ether ketone ketone and an aromatic polymer carrying sulphonic acid groups. 
     
     
         31 . A fuel cell system comprising the membrane electrode assembly of  claim 20 . 
     
     
         32 . A fuel cell stack comprising the membrane electrode assembly of  claim 20 . 
     
     
         33 . A fuel cell comprising the membrane electrode assembly of  claim 20 .