Electrically conductive fluid distribution plate for fuel cells
In at least one embodiment, the present invention provides an electrically conductive fluid distribution plate and a method of making, and system for using, the electrically conductive fluid distribution plate. The plate comprises a plate body having a surface defining a set of fluid flow channels configured to distribute flow of a fluid across at least one side of the plate, at least a portion of the surface having a roughness average of 0.5 to 5 μm and a contact resistance of less than 40 mohm cm 2 when sandwiched between carbon papers at 200 psi.
1 . An electrically conductive fluid distribution plate comprising:
a plate body having a surface defining a set of fluid flow channels configured to distribute flow of a fluid across at least one side of the plate, at least a portion of the surface having a roughness average of greater than 0.5 μm, and a contact resistance of less than 40 mohm cm 2 when sandwiched between carbon papers at 200 psi.
2 . The plate of claim 1 wherein the roughness average of the surface portion is 0.5 to 50 μm.
3 . The plate of claim 2 wherein the contact resistance is 5 to 40 mohm cm 2 when sandwiched between carbon paper at 200 psi.
4 . The plate of claim 1 wherein the plate body comprises a metallic surface.
5 . The plate of claim 4 wherein the plate body comprises a high quality stainless steel having a combined content of molybdenum, chromium, and nickel greater than 40% by weight of the total weight of the stainless steel.
6 . The plate of claim 5 wherein the contact resistance is 5 to 30 mohm cm 2 when sandwiched between carbon papers at 200 psi.
7 . The plate of claim 1 wherein the plate body comprises a composite polymeric surface.
8 . The plate of claim 1 wherein the plate comprises a bipolar plate comprising opposed sheets having a contact resistance across the sheets of the bipolar plate of 0.1 to 4 mohm cm 2 at 200 psi.
9 . The plate of claim 1 wherein the plate comprises a unipolar plate.
10 . The plate of claim 1 wherein the surface was roughened by a solid media under conditions to obtain the roughness average of greater than 0.5 μm.
11 . The plate of claim 2 wherein the surface portion has a peak density of at least 8 peaks/mm along the X direction, an average maximum profile height of at least 7 μm, and a contact resistance of less than 30 mohm cm 2 when sandwiched between carbon papers at 200 psi; and
the plate body comprising high quality stainless steel having a combined content of molybdenum, chromium, and nickel of greater than 40% by weight of the total weight of the stainless steel.
12 . A method of manufacturing a fluid distribution plate comprising:
providing a plate body having a surface defining a set of fluid flow channels configured to distribute flow of a fluid across at least one side of the plate, the surface having a first roughness average of less than 0.2 μm; and
exposing the surface to a solid media under conditions to provide at least a portion of the surface with a second roughness average of greater than 0.5 μm, and a contact resistance of less than 40 mohm cm 2 when sandwiched between carbon papers at 200 psi.
13 . The method of claim 12 wherein solid media is exposed to the surface at an average pressure of 5-75 psi and for a period of 0.15 to 5 minutes.
14 . The method of claim 13 wherein the solid media has an average diameter of 0.5-25 μm.
15 . The method of claim 14 wherein the solid media comprises sand.
16 . The method of claim 12 wherein the contact resistance is 5 to 40 mohm cm 2 when sandwiched between carbon paper at 200 psi.
17 . The method of claim 12 wherein the plate body comprises a high quality stainless steel having a combined content of molybdenum, chromium, and nickel greater than 40% by weight of the total weight of the stainless steel.
18 . The method of claim 17 wherein the contact resistance is 5 to 30 mohm cm 2 when sandwiched between carbon papers at 200 psi.
19 . The method of claim 12 wherein the plate body comprises a composite polymeric surface and a bipolar plate comprising opposed sheets, the resistance across the sheets of the bipolar plate being 0.1 to 4 mohm cm 2 at 200 psi.
20 . A fuel cell comprising:
a first electrically conductive fluid distribution plate comprising a plate body having a surface defining a set of fluid flow channels configured to distribute flow of a fluid across at least one side of the plate, at least a portion of the surface having a roughness average of greater than 0.5 μm and a contact resistance of less than 40 mohm cm 2 when sandwiched between carbon papers at 200 psi;
a second electrically conductive fluid distributing plate; and
a membrane electrode assembly separating the first electrically conductive fluid distribution plate and the second electrically conductive fluid distribution plate, the membrane electrode assembly comprising:
an electrolyte membrane, having a first side and a second side, an anode adjacent to the first side of the electrolyte membrane; and
a cathode adjacent to the second side of the electrolyte membrane.