Method for fabrication of electrodes

Abstract

Described herein is a method to fabricate porous thin-film electrodes for fuel cells and fuel cell stacks. Furthermore, the method can be used for all fuel cell electrolyte materials which utilize a continuous electrolyte layer. An electrode layer is deposited on a porous host structure by flowing gas (for example, Argon) from the bottomside of the host structure while simultaneously depositing a conductive material onto the topside of the host structure. By controlling the gas flow rate through the pores, along with the process conditions and deposition rate of the thin-film electrode material, a film of a predetermined thickness can be formed. Once the porous electrode is formed, a continuous electrolyte thin-film is deposited, followed by a second porous electrode to complete the fuel cell structure.

The invention claimed is:  
     
         1 . An electrode comprising a conductive material having a plurality of pores, said electrode having a pore size distribution wherein at least 90% of the total pore volume is in pores of diameter from about 10% below the size of the mode pore diameter to about 10% above the size of the mode pore diameter.  
     
     
         2 . The electrode of claim  10 , wherein said pore sizes are in the range of about 0.1 μm to about 10 μm as measured by scanning electron microscopy  
     
     
         3 . The electrode of claim  10 , wherein said pores are tapered having a first pore opening and a second pore opening, wherein said first pore opening is up to about a factor of 10 smaller in size than said second pore opening, wherein said pore openings are measured by scanning electron microscopy.  
     
     
         4 . A fuel cell comprising at least one electrode comprising a conductive material having a plurality of pores, said electrode having a pore size distribution wherein at least 90% of the total pore volume is in pores of diameter from about 10% below the size of the mode pore diameter to about 10% above the size of the mode pore diameter.  
     
     
         5 . The fuel cell of claim  13 , wherein said pores are tapered having a first pore opening and a second pore opening, wherein said first pore opening is up to about a factor of 10 smaller in size than said second pore opening, wherein said pore openings are measured by scanning electron microscopy.  
     
     
         6 . The fuel cell of claim  13 , wherein the pore sizes are in the range of about 0.1 μm to about 10 μm as measured by scanning electron microscopy  
     
     
         7 . A fuel cell stack comprising at least one fuel cell having at least one electrode comprising a conductive material having a plurality of pores, said electrode having a pore size distribution wherein at least 90% of the total pore volume is in pores of diameter from about 10% below the size of the mode pore diameter to about 10% above the size of the mode pore diameter.  
     
     
         8 . The fuel cell stack of claim  16 , wherein said pores are tapered having a first pore opening and a second pore opening, wherein said first pore opening is up to about a factor of 10 smaller in size than said second pore opening, wherein said pore openings are measured by scanning electron microscopy.  
     
     
         9 . The fuel cell stack of claim  16 , wherein the pore sizes are in the range of about 0.1 μm to about 10 μm as measured by scanning electron microscopy