Fuel cell with monolithic flow field-bipolar plate assembly and method for making and cooling a fuel cell stack

Abstract

An electrochemical fuel cell contains first and second monolithic electrically conducting flow field-bipolar plate assemblies arranged essentially parallel to each other such that an inside surface of the first bipolar separator plate is facing an inside surface of the second bipolar separator plate, wherein the bipolar separator plates are electrically and mechanically connected by intervening layers that are directly bonded to each other. The fuel cells can be stacked between endplates and supplied with hydrogen and oxygen to generate electric power. An air cooled condenser for use with a fuel cell stack is composed of a porous foam condensing element and a porous foam cooling element. The condenser can be placed by a fuel cell stack for cooling purposes.

1 - 15 . Cancelled.  
     
     
         16 . An air cooled condenser for use with a fuel cell stack, the condenser comprising a three-dimensionally reticulated porous metal condensing element and a three-dimensionally reticulated porous metal cooling element, wherein the three-dimensionally reticulated porous metal condensing element is disposed between two gas impermeable barriers by continuous metallurgical bonds, and wherein the three dimensionally reticulated porous metal cooling element is disposed between and bonded directly to two other gas impermeable barriers.  
     
     
         17 . A condenser according to  claim 16 , wherein the condensing element comprises copper, nickel, aluminum, titanium, or an aluminum-titanium alloy.  
     
     
         18 . A condenser according to  claim 17 , wherein the condensing element comprises nickel.  
     
     
         19 . A condenser according to  claim 16 , wherein the gas impermeable barriers comprise a metal foil.  
     
     
         20 . A condenser according to  claim 19 , wherein the metal foil is tin, copper nickel, aluminum, gold, or an aluminum-titanium alloy.  
     
     
         21 . A condenser according to  claim 20 , wherein the metal foil is nickel.  
     
     
         22 . A condenser according to  claim 16 , wherein the condensing element is bonded to the gas impermeable barriers by electroplating or sintering.  
     
     
         23 . A condenser according to  claim 18 , wherein the cooling element comprises copper, nickel aluminum titanium, or an aluminum-titanium alloy.  
     
     
         24 . A condenser according to  claim 26 , wherein the cooling element comprises copper.  
     
     
         25 . An evaporatively cooled internally humidified fuel cell stack comprising a plurality of fuel cells and an air cooled condenser in fluid communication with the fuel cells, 
 wherein the condenser comprises a plurality of three dimensionally reticulated porous metal condensing elements and a plurality of three dimensionally reticulated porous metal cooling elements, wherein the three dimensionally reticulated porous metal condensing elements are disposed between and bonded to two gas impermeable barriers by continuous metallurgical bonds, and wherein the three dimensionally reticulated porous metal cooling elements are disposed between and bonded directly to two other gas impermeable barriers.    
     
     
         26 . A method of cooling an electrochemical fuel cell comprising placing the electrochemical fuel cell in fluid communication with an air cooled condenser wherein the air cooled condenser comprises a plurality of three dimensionally reticulated porous metal condensing elements and a plurality of three dimensionally reticulated porous metal cooling elements, wherein the three dimensionally reticulated porous metal condensing elements are disposed between and bonded to two gas impermeable barriers by continuous metallurgical bonds, and wherein the three dimensionally reticulated porous metal cooling elements are disposed between and bonded directly to two other gas impermeable barriers.  
     
     
         27 . A flow field-bipolar plate assembly for an electrochemical cell, comprising a first and second three dimensional reticulated porous metal flow-fields bonded directly to opposite sides of an electrically conducting gas impermeable barrier by continuous metallurgical bonds.  
     
     
         28 . The component of  claim 27 , wherein the porous metal flow-fields are bonded to the conducting gas impermeable barrier by electroplating or sintering.  
     
     
         29 . The component of  claim 27 , wherein the electrically conducting gas impermeable barrier comprises a metal foil.  
     
     
         30 . The component of  claim 29 , wherein the metal foil is tin, copper, nickel, aluminum, titanium, gold, or an aluminum-titanium alloy.  
     
     
         31 . The component of  claim 30 , wherein the metal foil is nickel.  
     
     
         32 . The component of  claim 27 , wherein at least one flow field comprises tin, copper, nickel, aluminum, titanium, gold, or an aluminum-titanium alloy.  
     
     
         33 . The component of  claim 32 , wherein at least one flow fields comprises nickel.  
     
     
         34 . The component of  claim 27 , wherein at least one of the porous metal flow-fields further comprises a protecting layer disposed on at least one surface thereof.  
     
     
         35 . The component of  claim 34 , wherein the protecting layer comprises a metal or a metal oxide.  
     
     
         36 . The component of  claim 35 , wherein the protecting layer comprise tin, copper, nickel, aluminum, titanium, or gold.  
     
     
         37 . The component of  claim 35 , wherein the protecting layer comprises ruthenium oxide, titanium oxide, or tin oxide.  
     
     
         38 . The component of  claim 37 , wherein the protecting layer comprises tin oxide.  
     
     
         39 . The component of  claim 34 , wherein the tin oxide layer is between about 1 and about 5 μm thick.  
     
     
         40 . The component of  claim 39 , wherein the tin oxide layer is between about 1 and about 2 μm thick.  
     
     
         41 . A method of delivering a gas to a fuel cell electrode comprising: 
 delivering the gas to a porous metal flow field-bipolar plate assembly wherein the porous metal flow field-bipolar plate assembly comprises an electrically conducting gas barrier and a three-dimensionally reticulated porous metal flow field bonded one side of the electrically conducting gas barrier by a continuous metallurgical bond;    wherein the gas contacts the three-dimensionally reticulated porous metal flow field and diffuses into contact with an electrode that is in gas communication with the three dimensionally reticulated porous metal flow-field.    
     
     
         42 . The method of  claim 41 , wherein the porous metal flow field is bonded to the conducting gas barrier by electroplating or scintering.