Fuel cell flow field plate including non-stoichiometric metal oxide layer

Abstract

A flow field plate or bipolar plate for a fuel cell that includes a combination of non-stoichiometric and a conductive material that makes the bipolar plate conductive, hydrophilic and stable in the fuel cell environment. The non-stoichiometric and the conductive material can be deposited on the plate as separate layers or can be combined as a single layer. Either the non-stoichiometric layer or the conductive layer can be deposited first. In one embodiment, the conductive material is gold.

What is claimed is: 
     
         1 . A method for making a flow field plate for a fuel cell, said method comprising:
 providing a flow field plate being made of a plate material;   depositing a conductive layer on the flow field plate; and   depositing a non-stoichiometric metal oxide layer on the conductive layer so as to make the plate conductive, hydrophilic and stable in a fuel cell environment.   
     
     
         2 . The method according to  claim 1  wherein the plate material is selected from the group consisting of stainless steel, titanium, aluminum and a polymer-carbon composite based material. 
     
     
         3 . The method according to  claim 1  wherein the conductive layer is a gold layer. 
     
     
         4 . The method according to  claim 1  wherein the non-stoichiometric metal oxide layer provides a contact angle for water accumulating in the flow channels to be below 20°. 
     
     
         5 . The method according to  claim 1  wherein the non-stoichiometric metal oxide layer is resistant to surface contamination. 
     
     
         6 . The method according to  claim 1  wherein the conductive layer has a thickness in the 2-10 nm range. 
     
     
         7 . The method according to  claim 1  wherein the non-stoichiometric metal oxide layer and the conductive layer are deposited on the flow field plate by a process selected from the group consisting of an electron beam evaporation process, magnetron sputtering, a pulse plasma process, plasma enhanced chemical vapor deposition, an atomic layer deposition process, thermal spraying, spin coating, dip coating and a sol-gel process. 
     
     
         8 . The method according to  claim 1  wherein the flow field plate is selected from the group consisting of anode side flow field plates and cathode side flow field plates. 
     
     
         9 . The method according to  claim 1  wherein the fuel cell is part of a fuel cell stack on a vehicle. 
     
     
         10 . The method according to  claim 1  wherein the non-stoichiometric metal oxide layer is TiO x  where x is in the range of 0.1-6. 
     
     
         11 . A method for making a flow field plate for a fuel cell, said method comprising:
 providing a flow field plate being made of a plate material; and   depositing a mixture of a non-stoichiometric metal oxide and a conductive material as a combined layer on the flow field plate to make the plate conductive, hydrophilic and stable in a fuel cell environment.   
     
     
         12 . The method according to  claim 11  wherein the plate material is selected from the group consisting of stainless steel, titanium, aluminum and a polymer-carbon composite based material. 
     
     
         13 . The method according to  claim 11  wherein the conductive material is a gold layer. 
     
     
         14 . The method according to  claim 11  wherein the combined non-stoichiometric metal oxide and the conductive layer are deposited on the flow field plate by a process selected from the group consisting of an electron beam evaporation process, magnetron sputtering, a pulse plasma process, plasma enhanced chemical vapor deposition, an atomic layer deposition process, thermal spraying, spin coating, dip coating and a sol-gel process. 
     
     
         15 . The method according to  claim 11  wherein the flow field plate is selected from the group consisting of anode side flow field plates and cathode side flow field plates. 
     
     
         16 . The method according to  claim 11  wherein the fuel cell is part of a fuel cell stack on a vehicle. 
     
     
         17 . The method according to  claim 11  wherein the non-stoichiometric metal oxide is TiO x  where x is in the range of 0.1-6.