A bipolar flow field plate, a fuel cell comprising a bipolar flow field plate, and a method for making bipolar flow field plates

Abstract

A bipolar flow field plate assembly comprising first and second flow field plates, the first flow field plate comprising a seal groove around a perimeter and a depressed seal portion within the seal groove for retaining an adhesive; the second flow field plate comprising a raised portion around a perimeter which protrudes from the second flow field plate, cooperates with the depressed seal portion of the first flow field plate, and contacts at least a portion of the adhesive therein. At least one of the depressed seal portion and the raised portion comprises a depressed spill portion adjacent thereto, the depressed spill portion fluidly connected to the depressed seal portion for receiving excess adhesive. A cross-sectional width and depth of the depressed seal portion is greater than a cross-sectional width and height of the first depressed spill portion so the raised portion and the depressed seal portion are physically separated.

Description

[0001] A BIPOLAR FLOW FIELD PLATE, A FUEL CELL COMPRISING A BIPOLAR FLOW FIELD PLATE, AND A METHOD FOR MAKING BIPOLAR FLOW FIELD PLATES

[0002] BACKGROUND OF THE INVENTION

[0003] Field of the Invention

[0004] The present description relates to bipolar flow field plates for electrochemical fuel cells, an electrochemical fuel cell comprising the bipolar flow field plate, and a method for making the same. More specifically, the present description relates to an adhesively-bonded bipolar flow field plate and a method for making the same.

[0005] Description of the Related Art

[0006] Fuel cell systems are currently being developed for use as power supplies in numerous applications, such as automobiles and stationary power plants. Such systems offer promise of delivering power economically and with environmental and other benefits.

[0007] Fuel cells convert reactants, namely, fuel and oxidant, to generate electric power and reaction products. In operation, the output voltage of an individual fuel cell under load is generally below one volt. Therefore, in order to provide greater output voltage, multiple cells are usually stacked together and are connected in series to create a higher voltage fuel cell stack. (End plate assemblies are placed at each end of the stack to hold the stack together and to compress the stack components together. Compressive force effects sealing and provides adequate electrical contact between various stack components.) Fuel cell stacks can then be further connected in series and / or parallel combinations to form larger arrays for delivering higher voltages and / or currents.

[0008] Polymer electrolyte membrane fuel cells (“PEM fuel cell”) employ a membrane electrode assembly ("MEA"), which comprises a solid polymer electrolyte or ion-exchange membrane disposed between the two electrodes, namely a cathode and an anode. A catalyst typically induces the desired electrochemical reactions at the electrodes. Separator plates, or flow field plates, are disposed on each side of the MEA for directing the reactants across one surface of each electrode substrate.

[0009] Flow field plates need to have mechanical stiffness and strength, as well as be electrically and thermally conductive. Therefore, common materials used to make flow field plates are metal and carbon. Metal plates are typically formed from stainless steel or other low-cost metal that is usually coated with a metallic or polymer coating to improve its anti-corrosive properties and electrical conductivity, and then formed with flow field channels. Carbon plates are usually made from graphite that are embossed, molded or machined with flow field channels.

[0010] Bipolar flow field plates are typically formed by joining an anode plate and a cathode plate together so that coolant channels are formed between the anode plate and the cathode plate. The coolant channels allow the circulation of a coolant fluid to regulate the temperature of the fuel cell during operation. Metal plates may be welded together while carbon plates are typically glued together. For instance, U.S. Patent No. 6,777,127 discloses a method of gluing flow field plates around a perimeter thereof wherein a sealing groove with a complex cross-sectional shape receives and retains a bead of adhesive prior to being assembled. The complex cross-sectional shape has a raised portion sized to receive and retain the bead of adhesive, and at least one depressed portion to receive adhesive displaced from the raised portion during assembly. However, the inventor has discovered that wicking and movement of the adhesive on the raised portion during assembly of the plates led to uneven distribution of the adhesive, for example, some sections of the raised portion in the seal area did not have enough adhesive, leading to internal leaks between coolant, fuel and / or oxidant, as well as external leaks in those low adhesive areas, and other sections of the raised portion in the seal area that had too much adhesive, leading to excess adhesive in the depressed portion and subsequent adhesive leakage into the ports of the flow field plate. Furthermore, the adhesive may inadvertently spill preferentially into one depressed portion rather than the other if the complex cross-sectional shape is not perfectly flat.

[0011] As a result, there still exists a need to improve the design of the adhesive region of bipolar plates.

[0012] BRIEF SUMMARY OF THE INVENTION

[0013] In brief, a bipolar flow field plate assembly comprises a first flow field plate comprising a first planar active surface and an opposing first planar non-active surface, and a second flow field plate comprising a second planar active surface and an opposing second planar non-active surface, wherein the first planar non-active surface of the first flow field plate is in contact with the second planar non-active surface of the second flow field plate; the first planar non-active surface of the first flow field plate comprises a seal groove around a perimeter thereof for retaining an adhesive, wherein the seal groove comprises a depressed seal portion for retaining an adhesive; the second planar non-active surface of the second flow field plate comprises at least one raised portion around a perimeter thereof, wherein the at least one raised portion protrudes from the second planar non-active surface, cooperates with the depressed seal portion of the first flow field plate and contacts at least a portion of the adhesive therein; wherein the depressed seal portion of the first flow field plate comprises at least one first depressed spill portion adjacent thereto, the at least one first depressed spill portion fluidly connected to the depressed seal portion for receiving excess adhesive; and a cross-sectional depth of the depressed seal portion is greater than cross-sectional depth of the at least one first depressed spill portion. In further embodiments, a cross-sectional width and height of the at least one raised portion on the second planar non-active surface of the second flow field plate is less than a respective cross- sectional width and depth of the depressed seal portion on the first planar non-active surface of the first flow field plate so that the at least one raised portion is physically separated from the depressed seal portion.

[0014] In other embodiments, a bipolar flow field plate assembly comprises a first flow field plate comprising a first planar active surface and an opposing first planar non-active surface, and a second flow field plate comprising a second planar active surface and an opposing second planar non-active surface, wherein the first planar non-active surface of the first flow field plate is in contact with the second planar non-active surface of the second flow field plate; the first planar non-active surface of the first flow field plate comprises a seal groove around a perimeter thereof for retaining an adhesive, wherein the seal groove comprises a depressed seal portion for retaining an adhesive; the second planar non-active surface of the second flow field plate comprises at least one raised portion around a perimeter thereof, wherein the at least one raised portion protrudes from the second planar non-active surface, cooperates with the depressed seal portion of the first flow field plate and contacts at least a portion of the adhesive therein; wherein the at least one raised portion of the second flow field plate comprises at least one first depressed spill portion adjacent thereto, the at least one first depressed spill portion fluidly connected to the depressed seal portion for receiving excess adhesive. In further embodiments, a cross-sectional width and height of the at least one raised portion on the second planar non-active surface of the second flow field plate is less than a respective cross-sectional width and depth of the depressed seal portion on the first planar non-active surface of the first flow field plate so that the at least one raised portion is physically separated from the depressed seal portion.

[0015] In another embodiment, a method of making a bipolar flow field plate for an electrochemical fuel cell comprises the steps of: providing a first flow field plate comprising a first planar active surface and an opposing first planar non-active surface, the first planar nonactive surface of the first flow field plate comprising a seal groove around a perimeter thereof, wherein the seal groove comprises a depressed seal portion; providing a second flow field plate comprising a second planar active surface and an opposing second planar non-active surface, the second planar non-active surface of the second flow field plate comprising at least one raised portion around a perimeter thereof, wherein the at least one raised portion protrudes from the second planar non-active surface; wherein the depressed seal portion of the first flow field plate comprises at least one first depressed spill portion adjacent thereto, the at least one first depressed spill portion fluidly connected to the depressed seal portion; and a cross-sectional depth of the depressed seal portion is greater than the cross-sectional depth of the first depressed spill portion; depositing an adhesive in the depressed seal portion of the first flow field plate; and contacting the first planar non-active surface of the first flow field plate with the second planar non-active surface of the second flow field plate such that the at least one raised portion of the second flow field plate contacts the adhesive in the depressed seal portion, wherein excess adhesive displaced by such contact is received in the first depressed spill portion of the first flow field plate.

[0016] In yet another embodiment, a method of making a bipolar flow field plate for an electrochemical fuel cell comprises the steps of providing a first flow field plate comprising a first planar active surface and an opposing first planar non-active surface, the first planar non- active surface of the first flow field plate comprising a seal groove around a perimeter thereof, wherein the seal groove comprises a depressed seal portion; providing a second flow field plate comprising a second planar active surface and an opposing second planar non-active surface, the second planar non-active surface of the second flow field plate comprising at least one raised portion around a perimeter thereof, wherein the at least one raised portion protrudes from the second planar non-active surface; wherein the at least one raised portion of the second flow field plate comprises at least one first depressed spill portion adjacent thereto, the at least one first depressed spill portion fluidly connected to the depressed seal portion for receiving excess adhesive; depositing an adhesive in the depressed seal portion of the first flow field plate; and contacting the first planar non-active surface of the first flow field plate with the second planar non-active surface of the second flow field plate such that the at least one raised portion of the second flow field plate contacts the adhesive in the depressed seal portion, wherein excess adhesive displaced by such contact is received in the first depressed spill portion of the second flow field plate. These and other aspects of the invention are evident upon reference in the attached drawings and following detailed description.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure l is a cross-sectional view of a conventional fuel cell, in accordance with some embodiments.

[0019] Figure 2A is a cross-sectional view of the seal area in the unassembled state and Figure 2B is a cross-sectional view of the seal area in the assembled state, according to some embodiments.

[0020] Figure 3 A is cross-sectional view of the seal area in the unassembled state, and Figure 3B is a cross-sectional view of the seal area in the assembled state, according to further embodiments.

[0021] Figure 4A is a cross-sectional view of the seal area in the unassembled state and Figure 4B is a cross-sectional view of the seal area in the assembled state, according to other embodiments. Figure 4C is an isometric view of the anode flow field plate, according to some embodiments.

[0022] Figure 5A is a cross-sectional view of the seal area in the assembled state, according to specific embodiments. Figure 5B is a cross-sectional view of the seal area in the assembled state, according to other embodiments.

[0023] Figure 6 is a cross-sectional view of the seal area in the assembled state, according to other embodiments.

[0024] Figure 7 is an isometric view of the seal area of the cathode flow field plate, according to some embodiments.

[0025] Figures 8A, 8B and 8C are x-ray images of the seal area of flow field plates that were tested.

[0026] DETAILED DESCRIPTION

[0027] In the following description, certain specific details are set forth in order to provide a thorough understanding of the various embodiments of the invention. However, one skilled in the art will understand that the invention may be practiced without these details. In other instances, well-known structures associated with fuel cells, fuel cell stacks, batteries and fuel cell systems have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments of the invention. Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, that is as “including, but not limited to.”

[0028] With reference to Figure 1, an electrochemical fuel cell unit 1 includes an electrode assembly 2 having an anode electrode 6, a cathode electrode 7, and an electrolyte 5 disposed therebetween. Anode electrode 6 includes an anode gas diffusion layer 8 and an anode catalyst layer 10 while cathode electrode 7 includes a cathode gas diffusion layer 9 and a cathode catalyst layer 11. An anode flow field plate 3 has anode flow field channels 13 on its planar active surface and a planar non-active surface 15 on its opposing side. A cathode flow field plate 4 includes cathode flow field channels 12 on its planar active surface and coolant flow field channels 14 on its planar non-active surface on its opposing side. Repeating units of electrochemical fuel cell 1 are stacked together such that the planar active surface of cathode flow field plate 4 with cathode flow field channels 12 contacts the cathode electrode of the next electrochemical fuel cell (not shown) to form a fuel cell stack.

[0029] To form a bipolar flow field plate assembly, the planar non-active surface of anode flow field plate 3 is positioned to be in contact with the planar non-active surface of cathode flow field plate 4 such that coolant channels 14 are interposed therebetween. This allows the circulation of a coolant between fuel cells regulate the temperature of electrochemical fuel cell 1. Anode flow field plate 3 and cathode flow field plate 4 are typically joined and hermetically sealed to prevent the coolant from leaking out of coolant flow channels 14. For carbon and graphite plates, the plates are usually adhered together via an adhesive.

[0030] Around the perimeter of the planar non-active surfaces of anode flow field plate 3 and cathode flow field plate 4 is a seal area to retain the adhesive (the areas indicated by a dotted box in Figure 1). In one embodiment as shown in the cross-section of the seal area in Figures 2A (unassembled state) and 2B (assembled state), the planar non-active surface of anode flow field plate 3 includes a seal groove 18 having a depressed seal portion 20 for retaining the adhesive and depressed spill portions 22a, 22b adjacent and fluidly connected to depressed seal portion 20 for receiving and retaining excess adhesive that is displaced from depressed seal portion 20 during assembly of the bipolar flow field plate. The cross-sectional depth of depressed seal portion 20 is preferably greater than the cross-sectional depth of depressed spill portions 22a, 22b relative to the non-active surface of anode flow field plate 3. Furthermore, depressed spill portions 22a, 22b are preferably immediately adjacent depressed seal portion 20 to so that excessive adhesive in depressed seal portion 20 can be more easily received in depressed spill portion 22a, 22b during assembly.

[0031] Similarly, as shown in Figure 2B in the bipolar plate’s assembled state, the planar nonactive surface of cathode flow field plate 4 includes a raised portion 24 that protrudes from its planar non-active surface and cooperates with seal groove 18 such that raised portion 24 fits into seal groove 18 but does not physically contact the surface of depressed seal portion 20 and depressed spill portions 22a, 22b so as to form a volume for receiving and retaining the adhesive.

[0032] To assemble the bipolar flow field plate, adhesive is deposited on depressed seal portion 20 and then anode flow field plate 3 and cathode flow field plate 4 are brought together such that raised portion 24 fits into seal groove 18, thus contacting the adhesive in depressed seal portion 20. At the same time, any excess adhesive that is displaced by such contact can be received in depressed spill portions 22a, 22b because depressed spill portions 22a, 22b are fluidly connected to depressed seal portion 20.

[0033] As mentioned in the foregoing, movement of the adhesive during assembly of bipolar flow field plates have led to areas of uneven adhesive distribution and subsequent internal and external leaks, as well as undesirable adhesive leakage into other areas of the flow field plate. However, in the design of the present description, the inventor has discovered that because depressed seal portion 20 is deeper than depressed spill portions 22a, 22b, the adhesive is substantially retained in depressed seal portion 20. This thereby reduces the possibility of the adhesive moving to other parts of the flow field plate during assembly, such as the ports and coolant flow channels, even when the adhesive has a relatively low viscosity (such as between about 35,000 centipoise to 80,000 centipoise at the 60 minute test point and a sample temperature of about 25 degrees Celsius). Furthermore, the inventor has discovered that by having a raised portion on the opposite surface as the seal groove, less glue is required to achieve a hermetic seal than previous designs, such as that shown in U.S. Patent No. 6,777,127, because the combined size / volume of the depressed groove and spill groove areas can be reduced. This reduced size / volume may also improve the power density in the fuel cell stack. In addition, without being bound by theory, one skilled in the art will appreciate that utilizing a raised portion on the cathode flow field plate that fits into a corresponding depressed seal portion on the opposite anode flow field plate (but without direct physical contact) will increase the surface area of contact between the anode flow field plate and the cathode flow field plate via the adhesive that bonds the two flow field plates, thereby improving its adhesive strength. Depressed seal portion 20, depressed spill portions 22a, 22b and raised portion 24 should be sized such that adhesive can be received and retained therein. For example, the cross- sectional height of raised portion 24 on cathode flow field plate 4 should be less than the cross- sectional depth of depressed seal portion 20 on anode flow field plate 3 and the cross-sectional width of raised portion 24 should be less than the cross-sectional width of depressed seal portion 20 so that raised portion 24 is physically separated from depressed seal portion 20. One skilled in the art will be able to determine the cross-sectional dimensions of depressed seal portion 20, depressed spill portions 22a, 22b and raised portion 24 so that a sufficient volume is created between the non-active surfaces of anode flow field plate and cathode flow field plate so that adhesive can be substantially retained in volume when the flow field plates are assembled together to form a bipolar flow field plate. In one example, the depressed seal portion may be about 120 microns to about 200 microns in cross-sectional depth and about 1.8 millimeters to about 2.0 millimeters in cross-sectional width while the depressed spill portions may be about 70 microns to about 100 microns in cross-sectional depth and about 400 microns to about 750 microns in cross-sectional width.

[0034] In some embodiments, cathode flow field plate 4 may additionally, or alternatively, contain depressed spill portions adjacent raised portion 24 that cooperate with depressed seal portion 20 of anode flow field plate 3, and optionally, depressed spill portions 22a, 22b of anode flow field plate 3, to form a volume in which to retain displaced adhesive.

[0035] In one example as shown in Figure 3 A (unassembled state) and 3B (assembled state), two raised portions 24a, 24b are formed on cathode flow field plate 4 instead of one raised portion. This allows an additional depressed spill portion 26 to be formed between raised portions 24a and 24b for retaining displaced adhesive when anode flow field plate 3 and cathode flow field plate 4 are assembled. As in the embodiment before, raised portions 24a and 24b are physically separated from depressed seal portion 20 as well as depressed spill portions 22a, 22b to create a sufficient volume to retain the displaced adhesive when the flow field plates are assembled. Furthermore, by employing additional depressed spill portion 26, the size of the sealing area can be reduced in the planar direction because depressed spill portions 22a, 22b can have a lower cross-sectional width, thereby leading to potentially higher power densities. One skilled in the art will be able to readily determine suitable cross-sectional dimensions for raised portions 24a, 24b and depressed spill portion 26 for retaining the displaced adhesive. In further embodiments, more than one two raised portions and more than one depressed spill portion may be utilized (not shown). In previous examples, depressed spill portions 22a, 22b are formed adjacent the depressed seal portion of the anode flow field plate. However, such depressed spill portions may alternatively, or additionally, be formed on cathode flow field plate 4. In one embodiment as shown on the right side of Figures 4A (unassembled state) and 4B (assembled state), a depressed spill portion 28b is formed on cathode flow field plate 4 rather than anode flow field plate 3. Depressed spill portion 28b cooperates with depressed seal portion 20 to form a volume to retain excess adhesive. Alternatively, as shown on the left side of Figures 4A and 4B, a depressed spill portion 22a and a depressed spill portion 28a may be formed on the anode flow field plate 3 and the cathode flow field plate 4, respectively, to form a volume to retain excess adhesive.

[0036] In previous examples, raised portion 24 has a cross-sectional width that is slightly narrower than the cross-sectional width of depressed seal portion 20. In another embodiment, as shown in Figure 4A (unassembled state) and 4B (assembled state), cathode flow field plate 4 includes raised portion 24 that is much smaller in cross-sectional width than depressed seal portion 20. This forms additional volume in depressed seal portion 20 to receive and retain adhesive. However, if less adhesive is applied, the adhesion between raised portion 24 and depressed seal portion 20 will still be sufficient. During manufacturing, the amount of glue, or glue weight, applied to a plate can vary; changing the width of the raised portion 24 relative to depressed seal portion 20 can accommodate such variability without sacrificing proper adhesion.

[0037] In some embodiments, as shown on the right side of Figure 4B, a gap 30 may be implemented to allow venting of excess adhesive to the outer edge of the flow field plates when anode flow field plate 3 and cathode flow field plate 4 are assembled. To enhance mechanical stiffness in the edge, a plurality of discrete protrusions 32 may used in the peripheral region of the flow field plates, as shown in Figure 4C. While protrusions 32 are shown to be formed on anode flow field plate 3, they may be additionally, or alternatively, formed on cathode flow field plate 4.

[0038] In some embodiments, a multi-step spill portion may be implemented in the depressed seal portion that cooperates with at least one depressed spill portion of the opposite flow field plate to form a volume to retain adhesive. For example, with reference to Figure 5A, depressed spill portion 22a may include a step 34a that is greater in cross-sectional depth than depressed spill portion 22a relative to the non-active surface of anode flow field plate 3 while being physically separated from cathode flow field plate 4. Step 34a cooperates with depressed spill portion 28a of cathode flow field plate 4 to form a volume to retain displaced adhesive. Without being bound by theory, such a multi-step configuration in the depressed spill portion may reduce the amount of adhesive necessary to glue the plates together, as well as help guide excess glue to the volume formed by the depressed spill portions. Figure 5B shows an embodiment where the cross-sectional width of depressed spill portion 22b (right side of Figure 5B) is sized such that depressed seal portion 20 is made smaller and spill portion 22b made bigger than in previous embodiments but does not physically contact cathode plate 4 so that depressed seal portion 20 is fluidly connected to depressed spill portion 28b.

[0039] While Figures 1 to 5 show generally flat depressed and raised portions, one skilled the art will appreciate that depressed seal portion 20, depressed spill portions 22a, 22b and raised portion 24 can be any shape so long as depressed seal portion 20 and depressed spill portions 22a, 22b do not physically contact raised portion 24 and so long as depressed seal portion 20 is deeper than depressed spill portions 22a, 22b. For example, curved depressed portions are also contemplated so long as the depressed seal portion is deeper than the depressed spill portions, as shown in Figure 6. One skilled in the art will also appreciate that the seal area may be generally left-right symmetrical, as in the configuration shown in Figure IB, or may be left-right asymmetrical, as shown particularly in Figures 4B, 5A and 5B, because the shapes, widths and depths of the seal portion, spill portions and raised portion may or may not be the same on the left and right sides of the seal area.

[0040] Raised portion 24 may be utilized in a continuous or discrete manner along the planar non-active surface of cathode flow field plate 4. For example, raised portion 24 may have a variable cross-sectional height along the non-active planar surface of cathode flow field plate 4, such as that shown in Figure 7. One skilled in the art will appreciate that such a configuration further increases the surface area of contact between the cathode flow field plate, the adhesive and the anode flow field plate, thereby improving the adhesion strength between the anode flow field plate and the cathode flow field plate. Furthermore, this configuration may compensate for any glue dispensing variability in the manufacturing process. In some embodiments, the cross- sectional width and depth of the depressed seal grooves may be constant or variable along the non-active planar surface so long as the cross-sectional depth of the depressed seal portion is greater than the cross-sectional depth of the depressed spill portion.

[0041] While Figure 1 shows the coolant channels formed only on the non-active surface of the cathode flow field plate, the coolant channels may be, additionally or alternatively, formed on the non-active surface of the anode flow field plate. EXAMPLES

[0042] Three different seal groove designs were tested with the same amount of glue weight, as shown in Figures 8A (prior art), 8B and 8C. Glue was deposited into the depressed seal portion on the cathode plate and then the anode plate is brought into contact with the cathode plate such that the glue is displaced in the depressed seal portion, and then the glue is cured. The plates were then analyzed via X-ray imaging. With reference to Figure 8A, which is a prior art design of the seal area, 7 out of 7 samples showed glue missing in many areas. With reference to Figure 8B, which is the design of the seal area according to one of the embodiments of the present description, only 2 out of 8 samples had glue missing in some areas. With reference to Figure 8C, which is the design of the seal area according to another embodiment of the present description, only 2 out of 9 samples had glue missing in some areas. It is believed that with optimization of the design features, such as the dimensions, instances of missing glue can be even further reduced or eliminated.

[0043] While the present electrodes have been described for use in PEM fuel cells, it is anticipated that they may be useful in other fuel cells having an operating temperature below about 250 °C. They are particularly suited for acid electrolyte fuel cells, including phosphoric acid, PEM and liquid feed fuel cells. In addition, such catalysts may also be useful for water electrolysis applications.

[0044] All of the above U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and / or listed in the Application Data Sheet, including U.S. Provisional Patent Application No. 63 / 594,350, filed on October 30, 2023, are incorporated herein by reference in their entirety.

[0045] While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is therefore contemplated by the appended claims to cover such modifications that incorporate those features coming within the scope of the invention.

Claims

CLAIMSWhat is claimed is:

1. A bipolar flow field plate assembly comprising a first flow field plate comprising a first planar active surface and an opposing first planar non-active surface, and a second flow field plate comprising a second planar active surface and an opposing second planar non-active surface, wherein the first planar non-active surface of the first flow field plate is in contact with the second planar non-active surface of the second flow field plate; the first planar non-active surface of the first flow field plate comprises a seal groove around a perimeter thereof for receiving an adhesive, wherein the seal groove comprises a depressed seal portion for receiving the adhesive; the second planar non-active surface of the second flow field plate comprises at least one raised portion around a perimeter thereof, wherein the at least one raised portion protrudes from the second planar non-active surface, cooperates with the depressed seal portion of the first flow field plate and contacts at least a portion of the adhesive therein; wherein the depressed seal portion of the first flow field plate comprises at least one first depressed spill portion adjacent thereto, the at least one first depressed spill portion fluidly connected to the depressed seal portion for receiving excess adhesive; and a cross-sectional depth of the depressed seal portion is greater than cross-sectional depth of the at least one first depressed spill portion.

2. The bipolar flow field plate assembly of claim 1, wherein the first flow field plate is an anode flow field plate and the second flow field plate is a cathode flow field plate.

3. The bipolar flow field plate assembly of claim 1, wherein at least one of the first and second planar non-active surfaces comprise coolant flow field channels.

4. The bipolar flow field plate assembly of claim 1, wherein a cross-sectional width and height of the at least one raised portion on the second planar non-active surface of the second flow field plate is less than a respective cross-sectional width and depth of the depressed sealportion on the first planar non-active surface of the first flow field plate so that the at least one raised portion is physically separated from the depressed seal portion, [check]5. The bipolar flow field plate assembly of claim 1, wherein a cross-sectional depth of the depressed seal portion is about 120 microns to about 200 microns and a cross-sectional width of the depressed seal portion is about 1.8 millimeters to about 2.0 millimeters.

6. The bipolar flow field plate assembly of claim 1, wherein a cross-sectional depth of the at least one depressed spill portion is about 70 microns to about 100 microns and a cross- sectional width of the at least one depressed spill portion is about 400 microns to about 750 microns.

7. The bipolar flow field plate assembly of claim 1, wherein the second planar nonactive surface of the second flow field plate further comprises at least one second depressed spill portion adjacent the at least one raised portion and cooperates with the at least one first depressed spill portion to receive excess adhesive.

8. A bipolar flow field plate assembly comprising a first flow field plate comprising a first planar active surface and an opposing first planar non-active surface, and a second flow field plate comprising a second planar active surface and an opposing second planar non-active surface, wherein the first planar non-active surface of the first flow field plate is in contact with the second planar non-active surface of the second flow field plate; the first planar non-active surface of the first flow field plate comprises a seal groove around a perimeter thereof for receiving an adhesive, wherein the seal groove comprises a depressed seal portion for receiving the adhesive; the second planar non-active surface of the second flow field plate comprises at least one raised portion around a perimeter thereof, wherein the at least one raised portion protrudes from the second planar non-active surface, cooperates with the depressed seal portion of the first flow field plate and contacts at least a portion of the adhesive therein; whereinthe at least one raised portion of the second flow field plate comprises at least one first depressed spill portion adjacent thereto, the at least one first depressed spill portion fluidly connected to the depressed seal portion for receiving excess adhesive.

9. The bipolar flow field plate assembly of claim 8, wherein the first flow field plate is an anode flow field plate and the second flow field plate is a cathode flow field plate.

10. The bipolar flow field plate assembly of claim 8, wherein at least one of the first and second planar non-active surfaces comprise coolant flow field channels.

11. The bipolar flow field plate assembly of claim 8, wherein a cross-sectional width and height of the at least one raised portion on the second planar non-active surface of the second flow field plate is less than a respective cross-sectional width and depth of the depressed seal portion on the first planar non-active surface of the first flow field plate so that the at least one raised portion is physically separated from the depressed seal portion.

12. The bipolar flow field plate assembly of claim 8, wherein a cross-sectional depth of the depressed seal portion is about 120 microns to about 200 microns and a cross-sectional width of the depressed seal portion is about 1.8 millimeters to about 2.0 millimeters.

13. The bipolar flow field plate assembly of claim 8, wherein a cross-sectional depth of the at least one depressed spill portion is about 70 microns to about 100 microns and a cross- sectional width of the at least one depressed spill portion is about 400 microns to about 1100 microns.

14. A method of making a bipolar flow field plate for an electrochemical fuel cell, the method comprising the steps of: providing a first flow field plate comprising a first planar active surface and an opposing first planar non-active surface, the first planar non-active surface of the first flow field plate comprising a seal groove around a perimeter thereof, wherein the seal groove comprises a depressed seal portion; providing a second flow field plate comprising a second planar active surface and an opposing second planar non-active surface, the second planar non-active surface of the secondflow field plate comprising at least one raised portion around a perimeter thereof, wherein the at least one raised portion protrudes from the second planar non-active surface; wherein the depressed seal portion of the first flow field plate comprises at least one first depressed spill portion adjacent thereto, the at least one first depressed spill portion fluidly connected to the depressed seal portion; and a cross-sectional depth of the depressed seal portion is greater than the cross-sectional depth of the at least one first depressed spill portion; depositing an adhesive in the depressed seal portion of the first flow field plate; and contacting the first planar non-active surface of the first flow field plate with the second planar non-active surface of the second flow field plate such that the at least one raised portion of the second flow field plate contacts the adhesive in the depressed seal portion, wherein excess adhesive displaced by such contact is received in the at least one first depressed spill portion of the first flow field plate.

15. The method of claim 14, wherein a cross-sectional height of the at least one raised portion on the second planar non-active surface of the second flow field plate is less than the cross-sectional depth of the depressed seal portion on the first planar non-active surface of the first flow field plate so that the at least one raised portion is physically separated from the depressed seal portion.

16. The method of claim 15, wherein the second planar non-active surface of the second flow field plate further comprises at least one second depressed spill portion adjacent the at least one raised portion and cooperates with the at least one first depressed spill portion to receive excess adhesive.

17. A method of making a bipolar flow field plate for an electrochemical fuel cell, the method comprising the steps of: providing a first flow field plate comprising a first planar active surface and an opposing first planar non-active surface, the first planar non-active surface of the first flow field plate comprising a seal groove around a perimeter thereof, wherein the seal groove comprises a depressed seal portion;providing a second flow field plate comprising a second planar active surface and an opposing second planar non-active surface, the second planar non-active surface of the second flow field plate comprising at least one raised portion around a perimeter thereof, wherein the at least one raised portion protrudes from the second planar non-active surface; wherein the at least one raised portion of the second flow field plate comprises at least one first depressed spill portion adjacent thereto, the at least one first depressed spill portion fluidly connected to the depressed seal portion for receiving excess adhesive; depositing an adhesive in the depressed seal portion of the first flow field plate; and contacting the first planar non-active surface of the first flow field plate with the second planar non-active surface of the second flow field plate such that the at least one raised portion of the second flow field plate contacts the adhesive in the depressed seal portion, wherein excess adhesive displaced by such contact is received in the at least one first depressed spill portion of the second flow field plate.

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