FUEL CELL FLOW FIELD PLATE INCLUDING NON-STOICHIOMETRIC METAL OXIDE LAYER
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.
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.