Catalyst ink

Abstract

A catalyst ink is provided, comprising: 25-95% by weight water; 1-50% by weight of at least one solid catalyst, typically a highly dispersed platinum catalyst; 1-50% by weight of at least one polymer electrolyte in acid (H + ) form; and 1-50% by weight of at least one polar aprotic organic solvent. The catalyst ink typically has a viscosity at 1 sec −1 of 10 Pa·sec or less. The catalyst ink typically does not ignite spontaneously when dried to completion in air at a temperature of 80° C. or greater. The catalyst ink may be used in the fabrication of membrane electrode assemblies for use in fuel cells.

We claim:  
     
         1 . A catalyst ink comprising: 
 a) 25-95% by weight water;    b) 1-50% by weight of at least one solid catalyst;    c) 1-50% by weight of at least one polymer electrolyte in acid (H + ) form; and    d) 1-50% by weight of at least one polar aprotic organic solvent.    
     
     
         2 . The catalyst ink according to  claim 1  wherein said solid catalyst is a highly dispersed platinum catalyst.  
     
     
         3 . The catalyst ink according to  claim 2  wherein said polar aprotic organic solvent has a standard boiling point of at least 80° C.  
     
     
         4 . The catalyst ink according to  claim 2  wherein said polar aprotic organic solvent is selected from the group consisting of: dimethylsulfoxide (DMSO), N,N-dimethyacetamide (DMA), ethylene carbonate, propylene carbonate, dimethylcarbonate, diethylcarbonate, N,N-dimethylformamide (DMF), N-methylpyrrolidinone (NMP), dimethylimidazolidinone, acetonitrile, butyrolactone, hexamethylphosphoric triamide, isobutyl methyl ketone, and sulfolane.  
     
     
         5 . The catalyst ink according to  claim 2  wherein said polar aprotic organic solvent is selected from the group consisting of: N-methyl pyrrolidinone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsufoxide (DMSO) and acetonitrile.  
     
     
         6 . The catalyst ink according to  claim 2  wherein said polar aprotic organic solvent is N-methyl pyrrolidinone (NMP).  
     
     
         7 . The catalyst ink according to  claim 2  wherein said polymer electrolyte is highly fluorinated.  
     
     
         8 . The catalyst ink according to  claim 7  wherein said polymer electrolyte contains no arylene units in the polymer backbone.  
     
     
         9 . The catalyst ink according to  claim 2  comprising 50-80% water.  
     
     
         10 . The catalyst ink according to  claim 2  comprising 10-20% of said solid catalyst.  
     
     
         11 . The catalyst ink according to  claim 2  comprising 1-10% of said polymer electrolyte in acid (H + ) form.  
     
     
         12 . The catalyst ink according to  claim 2  comprising 5-15% of said polar aprotic organic solvent.  
     
     
         13 . The catalyst ink according to  claim 2  having a viscosity at 1 sec −1  of 10 Pa·sec or less.  
     
     
         14 . The catalyst ink according to  claim 2  having a viscosity at 1 sec −1  of 1.0 Pa·sec or less.  
     
     
         15 . The catalyst ink according to  claim 2  wherein said catalyst ink does not ignite spontaneously when dried to completion in air at a temperature of 80° C. or greater.  
     
     
         16 . The catalyst ink according to  claim 2  wherein said catalyst ink does not ignite spontaneously when dried to completion in air at a temperature of 110° C. or greater.  
     
     
         17 . The catalyst ink according to  claim 2  wherein said catalyst ink does not ignite spontaneously when dried to completion in air at a temperature of 140° C. or greater.  
     
     
         18 . A catalyst ink comprising: 
 a) 25-95% by weight water;    b) 1-50% by weight of at least one highly dispersed platinum catalyst;    c) 1-50% by weight of at least one polymer electrolyte in acid (H + ) form; and    d) 1-50% by weight of at least one second solvent which is not water;    wherein said catalyst ink has a viscosity at 1 sec −1  of 10 Pa·sec or less, and    wherein said catalyst ink does not ignite spontaneously when dried to completion in air at a temperature of 80° C. or greater.    
     
     
         19 . The catalyst ink according to  claim 18  wherein said second solvent has a standard boiling point of at least 80° C.  
     
     
         20 . The catalyst ink according to  claim 18  wherein said second solvent is selected from the group consisting of: dimethylsulfoxide (DMSO), N,N-dimethyacetamide (DMA), ethylene carbonate, propylene carbonate, dimethylcarbonate, diethylcarbonate, N,N-dimethylformamide (DMF), N-methylpyrrolidinone (NMP), dimethylimidazolidinone, acetonitrile, butyrolactone, hexamethylphosphoric triamide, isobutyl methyl ketone, and sulfolane.  
     
     
         21 . The catalyst ink according to  claim 18  wherein said second solvent is selected from the group consisting of: N-methyl pyrrolidinone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsufoxide (DMSO) and acetonitrile.  
     
     
         22 . The catalyst ink according to  claim 18  wherein said second solvent is N-methyl pyrrolidinone (NMP).  
     
     
         23 . The catalyst ink according to  claim 18  wherein said polymer electrolyte is highly fluorinated.  
     
     
         24 . The catalyst ink according to  claim 23  wherein said polymer electrolyte contains no arylene units in the polymer backbone.  
     
     
         25 . The catalyst ink according to  claim 18  comprising 50-80% water.  
     
     
         26 . The catalyst ink according to  claim 18  comprising 10-20% of said solid catalyst.  
     
     
         27 . The catalyst ink according to  claim 18  comprising 1-10% of said polymer electrolyte in acid (H + ) form.  
     
     
         28 . The catalyst ink according to  claim 18  comprising 5-15% of said second solvent.  
     
     
         29 . The catalyst ink according to  claim 18  having a viscosity at 1 sec −1  of 1.0 Pa·sec or less.  
     
     
         30 . The catalyst ink according to  claim 18  wherein said catalyst ink does not ignite spontaneously when dried to completion in air at a temperature of 110° C. or greater.  
     
     
         31 . The catalyst ink according to  claim 18  wherein said catalyst ink does not ignite spontaneously when dried to completion in air at a temperature of 140° C. or greater.