Performance additive for fuel cells

Abstract

A fuel mixture comprising at least one performance additive, wherein the performance additive comprises a cyclic tertiary amine having a molecular weight of at least about 200. Alternately, the performance additive may be present in the electrode composition. The performance additive is capable of improving the electrooxidation reaction rate of the fuel mixture, measured as current density, by at least 2% compared to a fuel mixture not containing the performance additive.

1 . A fuel mixture comprising at least one performance additive, wherein the performance additive comprises a cyclic tertiary amine having a molecular weight of at least 200.  
   
   
       2 . The fuel mixture of  claim 1  wherein the performance additive is capable of improving the electrooxidation reaction rate of the fuel mixture, measured as current density, by at least 2% compared to a fuel mixture not containing the performance additive.  
   
   
       3 . The fuel mixture of  claim 1  wherein the cyclic tertiary amine has a molecular weight of about 200 to about 10,000.  
   
   
       4 . The fuel mixture of  claim 3  wherein the cyclic tertiary amine has a molecular weight of about 400 to about 4,000.  
   
   
       5 . The fuel mixture of  claim 4  wherein the cyclic tertiary amine has a molecular weight of about 400 to about 2000.  
   
   
       6 . The fuel mixture of  claim 1  wherein the cyclic tertiary amine comprises at least one saturated monocyclic, bicyclic or polycyclic ring containing at least one tertiary N atom, and wherein the number of ring atoms ranges from 3 to 18.  
   
   
       7 . The fuel mixture of  claim 6  wherein the cyclic tertiary amine further comprises at least one atom selected from the group of C, N, O and Si.  
   
   
       8 . The fuel mixture of  claim 6  wherein the cyclic tertiary amine comprises at least two saturated cyclic amine rings, and wherein the rings are linked to one another by means of a linking group selected from the group consisting of linear alkylidene, cyclic alkylidene, oxyalkylidene, polyoxyalkylidene, alkoxylated alkylidene and alkylaryl groups having 1 to 100 carbon atoms.  
   
   
       9 . The fuel mixture of  claim 8  wherein the cyclic tertiary amine is selected from the group consisting of:  
     
       
         
         
             
             
         
       
     
   
   
       10 . The fuel mixture of  claim 6  wherein the cyclic tertiary amine comprises at least two saturated cyclic amine rings, and wherein the rings are attached to polymeric cores by means of side chains.  
   
   
       11 . The fuel mixture of  claim 10  wherein the cyclic tertiary amine has the following structure:  
     
       
         
         
             
             
         
       
     
     wherein n=about 1 to about 50,000.  
   
   
       12 . The fuel mixture of  claim 11  wherein n=about 100 to about 50,000.  
   
   
       13 . The fuel mixture of  claim 12  wherein n=about 1000 to about 10,000.  
   
   
       14 . The fuel mixture of  claim 11  wherein n=1 to about 100.  
   
   
       15 . The fuel mixture of  claim 14  wherein n=1 to about 20.  
   
   
       16 . The fuel mixture of  claim 6  wherein the cyclic tertiary amine is an end group of a dendrimer.  
   
   
       17 . The fuel mixture of  claim 16  wherein the dendrimer is a dendrimeric polyether.  
   
   
       18 . The fuel mixture of  claim 16  wherein the dendrimer is based on successive generations of polypropylenimines substituted onto a central diamine.  
   
   
       19 . The fuel mixture of  claim 18  wherein the central diamine is ethylenediamine, in which the terminal amine end groups are part of saturated cyclic rings.  
   
   
       20 . The fuel mixture of  claim 1  wherein the concentration of the performance additive in the methanol fuel is at least about 0.001 M.  
   
   
       21 . The fuel mixture of  claim 20  wherein the concentration of the performance additive in the methanol fuel is at least about 0.05 M.  
   
   
       22 . The fuel mixture of  claim 21  wherein the concentration of the performance additive in the methanol fuel is about 0.1 M to about 2.0 M  
   
   
       23 . A fuel supply for supplying fuel to the anode of a fuel cell, the fuel supply supplying fuel comprising at least one performance additive, wherein the performance additive comprises a cyclic tertiary amine having a molecular weight of at least about 200.  
   
   
       24 . The fuel supply of  claim 23  wherein the performance additive is capable of improving the electrooxidation reaction rate of the fuel mixture, measured as current density, by at least 2% compared to a fuel mixture not containing the performance additive.  
   
   
       25 . The fuel supply of  claim 23  wherein the cyclic tertiary amine has a molecular weight of about 200 to about 10,000.  
   
   
       26 . The fuel supply of  claim 23  wherein the cyclic tertiary amine comprises at least one saturated monocyclic, bicyclic or polycyclic ring containing at least one tertiary N atom, and wherein the number of ring atoms ranges from 3 to 18.  
   
   
       27 . The fuel supply of  claim 26  wherein the cyclic tertiary amine further comprises at least one atom selected from the group of C, N, O and Si.  
   
   
       28 . The fuel supply of  claim 23  wherein the cyclic tertiary amine comprises at least two saturated cyclic amine rings, and wherein the rings are linked to one another by means of a linking group selected from the group consisting of linear alkylidene, cyclic alkylidene, oxyalkylidene, polyoxyalkylidene, alkoxylated alkylidene and alkylaryl groups having 1 to 100 carbon atoms.  
   
   
       29 . The fuel supply of  claim 23  wherein the cyclic tertiary amine comprises at least two saturated cyclic amine rings, and wherein the rings are attached to polymeric cores by means of side chains.  
   
   
       30 . The fuel supply of  claim 23  wherein the cyclic tertiary amine is an end group of a dendrimer.  
   
   
       31 . The fuel supply of  claim 30  wherein the dendrimer is a dendrimeric polyether  
   
   
       32 . The fuel supply of  claim 30  wherein the dendrimer is based on successive generations of polypropylenimines substituted onto a central diamine.  
   
   
       33 . The fuel supply of  claim 23  wherein the concentration of the performance additive in the methanol fuel is at least about 0.001 M.  
   
   
       34 . The fuel supply of  claim 33  wherein the concentration of the performance additive in the methanol fuel is at least about 0.05 M.  
   
   
       35 . The fuel supply of  claim 34  wherein the concentration of the performance additive in the methanol fuel is about 0.1 M to about 2.0 M  
   
   
       36 . An electrode composition comprising an electrocatalyst, a polymer binder and at least one performance additive, wherein the performance additive comprises a cyclic tertiary amine having a molecular weight of at least about 200.  
   
   
       37 . The electrode composition of  claim 36  wherein the performance additive is capable of improving the electrooxidation reaction rate of the electrode composition, measured as current density, by at least 2% compared to an electrode composition not containing the performance additive.  
   
   
       38 . The electrode composition of  claim 36  wherein the cyclic tertiary amine has a molecular weight of about 200 to about 1,000,000.  
   
   
       39 . The electrode composition of  claim 38  wherein the cyclic tertiary amine has a molecular weight of about 2000 to about 500,000.  
   
   
       40 . The electrode composition of  claim 39  wherein the cyclic tertiary amine has a molecular weight of about 4000 to about 100,000.  
   
   
       41 . The electrode composition of  claim 36  wherein the cyclic tertiary amine comprises at least one saturated monocyclic, bicyclic or polycyclic ring containing at least one tertiary N atom, and wherein the number of ring atoms ranges from 3 to 18.  
   
   
       42 . The electrode composition of  claim 41  wherein the cyclic tertiary amine further comprises at least one atom selected from the group of C, N, O and Si.  
   
   
       43 . The electrode composition of  claim 41  wherein the cyclic tertiary amine comprises at least two saturated cyclic amine rings, and wherein the rings are linked to one another by means of a linking group selected from the group consisting of linear alkylidene, cyclic alkylidene, oxyalkylidene, polyoxyalkylidene, alkoxylated alkylidene and alkylaryl groups having 1 to 100 carbon atoms.  
   
   
       44 . The electrode composition of  claim 43  wherein the cyclic tertiary amine is selected from the group consisting of:  
     
       
         
         
             
             
         
       
     
   
   
       45 . The electrode composition of  claim 41  wherein the cyclic tertiary amine comprises at least two saturated cyclic amine rings, and wherein the rings are attached to polymeric cores by means of side chains.  
   
   
       46 . The electrode composition of  claim 45  wherein the cyclic tertiary amine has the following structure:  
     
       
         
         
             
             
         
       
     
     wherein n=about 1 to about 50,000.  
   
   
       47 . The electrode composition of  claim 46  wherein n=about 100 to about 50,000.  
   
   
       48 . The electrode composition of  claim 46  wherein n=about 1000 to about 10000.  
   
   
       49 . The electrode composition of  claim 46  wherein n=about 1 to about 100.  
   
   
       50 . The electrode composition of  claim 46  wherein n=about 1 to about 20.  
   
   
       51 . The electrode composition of  claim 41  wherein the cyclic tertiary amine is an end group of a dendrimer.  
   
   
       52 . The electrode composition of  claim 51  wherein the dendrimer is a dendrimeric polyether.  
   
   
       53 . The electrode composition of  claim 51  wherein the dendrimer is based on successive generations of polypropylenimines substituted onto a central diamine.  
   
   
       54 . The electrode composition of  claim 53  wherein the central diamine is ethylenediamine, in which the terminal amine end groups are part of saturated cyclic rings.  
   
   
       55 . The electrode composition of  claim 36  wherein the polymer binder is a highly fluorinated ion-exchange polymer, optionally containing sulfonate ion exchange groups  
   
   
       56 . The electrode composition of  claim 55  wherein the weight percentage of the polymer binder is at least about 5%.  
   
   
       57 . The electrode composition of  claim 56  wherein the weight percentage of the polymer binder is at least about 10% and less than about 20%.  
   
   
       58 . The electrode composition of  claim 36  wherein the weight percentage of the performance additive is at least about 0.1%.  
   
   
       59 . The electrode composition of  claim 36  wherein the weight percentage of the performance additive is at least about 1% and less than about 5%.  
   
   
       60 . A membrane electrode assembly comprising an electrode composition, wherein the electrode composition comprises an electrocatalyst, a polymer binder and at least one performance additive, wherein the performance additive comprises a cyclic tertiary amine having a molecular weight of at least about 200.  
   
   
       61 . The membrane electrode assembly of  claim 60  further comprising a solid polymer electrolyte membrane.  
   
   
       62 . The membrane electrode assembly of  claim 60  further comprising at least one gas diffusion backing.  
   
   
       63 . The membrane electrode assembly of  claim 60  wherein the performance additive is capable of improving the electrooxidation reaction rate of the electrode composition, measured as current density, by at least 2% compared to an electrode composition not containing the performance additive.  
   
   
       64 . The membrane electrode assembly of  claim 60  wherein the cyclic tertiary amine has a molecular weight of about 200 to about 1,000,000.  
   
   
       65 . The membrane electrode assembly of  claim 64  wherein the cyclic tertiary amine has a molecular weight of about 4000 to about 100,000.  
   
   
       66 . The membrane electrode assembly of  claim 64  wherein the cyclic tertiary amine comprises at least one saturated monocyclic, bicyclic or polycyclic ring containing at least one tertiary N atom, and wherein the number of ring atoms ranges from 3 to 18.  
   
   
       67 . The membrane electrode assembly of  claim 66  wherein the cyclic tertiary amine further comprises at least one atom selected from the group of C, N, O and Si.  
   
   
       68 . The membrane electrode assembly of  claim 66  wherein the cyclic tertiary amine comprises at least two saturated cyclic amine rings, and wherein the rings are linked to one another by means of a linking group selected from the group consisting of linear alkylidene, cyclic alkylidene, oxyalkylidene, polyoxyalkylidene, alkoxylated alkylidene and alkylaryl groups having 1 to 100 carbon atoms.  
   
   
       69 . The membrane electrode assembly of  claim 68  wherein the cyclic tertiary amine is selected from the group consisting of:  
     
       
         
         
             
             
         
       
     
   
   
       70 . The membrane electrode assembly of  claim 66  wherein the cyclic tertiary amine comprises at least two saturated cyclic amine rings, and wherein the rings are attached to polymeric cores by means of side chains.  
   
   
       71 . The membrane electrode assembly of  claim 70  wherein the cyclic tertiary amine has the following structure:  
     
       
         
         
             
             
         
       
     
     wherein n=about 100 to about 50000.  
   
   
       72 . The membrane electrode assembly of  claim 64  wherein the cyclic tertiary amine is an end group of a dendrimer.  
   
   
       73 . An electrochemical cell comprising an anode and a cathode, a membrane comprising ionomer having ion-exchange groups separating the anode and cathode prepared from an electrode composition, and a fuel supply for supplying fuel to the anode, the fuel supply comprises at least one performance additive.  
   
   
       74 . The electrochemical cell of  claim 73  wherein the electrochemical cell is a fuel cell.  
   
   
       75 . The fuel cell of  claim 74  wherein the fuel is methanol.  
   
   
       76 . The electrochemical cell of  claim 74  wherein the performance additive is capable of improving the electrooxidation reaction rate of the electrode composition, measured as current density, by at least 2% compared to an electrode composition not containing the performance additive.  
   
   
       77 . The electrochemical cell of  claim 74  wherein the performance additive is a cyclic tertiary amine, and wherein the cyclic tertiary amine has a molecular weight of about 200 to about 1,000,000.  
   
   
       78 . The fuel cell of  claim 74  wherein the performance additive is a cyclic tertiary amine, and the cyclic tertiary amine comprises at least one saturated monocyclic, bicyclic or polycyclic ring containing at least one tertiary N atom, and wherein the number of ring atoms ranges from 3 to 18.  
   
   
       79 . An electrochemical cell comprising a membrane electrode assembly, wherein the membrane electrode assembly comprises at least one electrode composition, wherein the electrode composition comprises an electrocatalyst, and wherein the electrochemical cell comprises a fuel supply comprising a performance additive.  
   
   
       80 . The electrochemical cell of  claim 79  wherein the electrochemical cell is a fuel cell.  
   
   
       81 . The fuel cell of  claim 80  wherein the membrane electrode assembly further comprises a solid polymer electrolyte membrane wherein the membrane comprises an ionomer having proton conductive ion-exchange groups separating the anode and cathode.  
   
   
       82 . The fuel cell of  claim 80  wherein the membrane electrode assembly further comprises at least one gas diffusion backing.  
   
   
       83 . The fuel cell of  claim 80  wherein the electrode composition comprises a performance additive.  
   
   
       84 . A process for operating a direct methanol fuel cell comprising an anode and a cathode, a membrane comprising ion-exchange groups separating the anode and cathode, and a fuel supply for supplying liquid methanol fuel to the anode, the process comprising contacting one or all of the membrane, anode or fuel with at least one performance additive, wherein the performance additive comprises a cyclic tertiary amine having a molecular weight of at least about 200.