BIPOLAR PLATE WITH IMPROVED METAL BEAD SEAL

Abstract

A bipolar plate includes an anode plate and a cathode plate. The anode plate has an inner surface and an outer surface opposite the inner surface. The cathode plate has an inner surface and an outer surface opposite the inner surface. The inner surface of the cathode plate faces the inner surface of the anode plate. The bipolar plate includes a bead region. A portion of the inner surface of the anode plate in the bead region is spaced from a portion of the inner surface of the cathode plate in the bead region. A reinforcing layer is disposed between the inner surface of the anode plate and the inner surface of the cathode plate in the bead region. The reinforcing layer is configured to resist compressive forces experienced by the outer surface of the anode plate and the outer surface of the cathode plate in the bead region.

Description

INTRODUCTION

[0001] The present invention relates generally to fuel cell systems for vehicles and, more particularly, to a bipolar plate according to the preamble of claim 1 or claim 8, as is essentially known from EP 3 269 000 B1.

[0002] In particular, the present invention provides a bipolar plate for a vehicle fuel cell system comprising an anode plate and a cathode plate, wherein a reinforcing layer or structure is disposed between the anode plate and the cathode plate at least in a bead region of the bipolar plate.

[0003] Fuel cell systems for powering propulsion systems of vehicles, such as passenger cars and commercial vehicles, typically include a fuel cell stack having a plurality of fuel cells connected in series by stacking the fuel cells one on top of the other. Typically, each cell includes a membrane electrode assembly positioned between a pair of bipolar plates. The bipolar plates of adjacent cells engage each other to establish an electrically conductive connection between the cells, provide physical strength to the fuel cell stack, and can seal a flow field extending across the bipolar plate and / or the membrane electrode assembly.Forces to which the bipolar plates are subjected, such as to create the seal between adjacent bipolar plates, or excessive forces experienced in a vehicle collision or due to vibrations or stresses during vehicle operation, can cause excessive compression or deformation of the bipolar plates and lead to loss of electrical connection between the cells and leakage from the flow field.

[0004] Further state of the art can be found in the documents DE 10 2014 104 017 A1, DE 10 2011 009 353 A1 and FR 2 896 623 A1.

[0005] To improve the structural integrity and sealing of the fuel cell stack, a bipolar plate comprising an anode plate and a cathode plate includes a reinforcement layer between the anode plate and the cathode plate at least in a bead region of the bipolar plate. The bead region of the bipolar plate includes a chamber between the respective inner surfaces of the anode plate and the cathode plate, and corresponding seals on the outer surfaces of the anode plate and the cathode plate. When the bipolar plate is disposed within the fuel cell stack of a fuel cell system, the seals engage respective structures of the fuel cell stack. The reinforcement layer is coupled to the inner surfaces of the anode plate and the cathode plate and extends within the chamber to reduce the effect of compressive forces on the structural integrity of the bead region of the bipolar plate. SUMMARY

[0006] According to the invention, a bipolar plate is presented which is characterized by the features of claim 1 or those of claim 8.

[0007] The bipolar plate includes an anode plate and a cathode plate. The anode plate has an inner side and an outer side opposite the inner side. The cathode plate has an inner side and an outer side opposite the inner side. The inner side of the cathode plate faces the inner side of the anode plate. The bipolar plate includes a bead region. A portion of the inner side of the anode plate in the bead region is spaced from a portion of the inner side of the cathode plate in the bead region. The bipolar plate includes a reinforcing layer disposed between the inner side of the anode plate and the inner side of the cathode plate in the bead region. The reinforcing layer is configured to resist compressive forces experienced by the outer side of the anode plate and the outer side of the cathode plate in the bead region.

[0008] Embodiments of the invention may include one or more of the following optional features. In some embodiments, the bipolar plate further comprises a first gasket and a second gasket. The first gasket is disposed on the exterior of the anode plate in the bead region. The second gasket is disposed on the exterior of the cathode plate in the bead region. The first gasket and the second gasket are configured to engage the respective membrane electrode assemblies of a fuel cell stack of a fuel cell system when the bipolar plate is disposed in the fuel cell stack. In further embodiments, the first gasket and the second gasket are configured to seal the respective flow fields extending across the exterior surfaces of the anode plate and the cathode plate when they engage the respective membrane electrode assemblies of the fuel cell stack.

[0009] In further examples, the reinforcement layer comprises an opening that fluidically connects a first portion of the chamber between the inside of the anode plate and the reinforcement layer and a second portion of the chamber between the inside of the cathode plate and the reinforcement layer.

[0010] In some embodiments, the reinforcement layer comprises an intermediate plate disposed between the portion of the inner surface of the anode plate and the portion of the inner surface of the cathode plate in the bead region and between other portions of the inner surface of the anode plate and other portions of the inner surface of the cathode plate remote from the bead region.

[0011] In some examples, one of the anode plate and the cathode plate includes a support portion recessed from the inner side of the respective one of the anode plate and the cathode plate. The reinforcement layer is received within the support portion.

[0012] In some aspects, the reinforcement layer is non-planar. In some embodiments, the reinforcement layer is laser welded to the anode plate and the cathode plate.

[0013] Furthermore, a fuel cell system is described. The fuel cell system comprises a fuel cell stack. The fuel cell stack comprises a plurality of fuel cells. At least one fuel cell of the plurality of fuel cells comprises a membrane electrode assembly arranged between a pair of bipolar plates. Each bipolar plate of the pair of bipolar plates comprises an anode plate and a cathode plate. The anode plate has an inner side and an outer side opposite the inner side. The cathode plate has an inner side and an outer side opposite the inner side. The inner side of the cathode plate faces the inner side of the anode plate. Each bipolar plate comprises a bead region. A portion of the inner side of the anode plate in the bead region is spaced from a portion of the inner side of the cathode plate in the bead region.Each bipolar plate includes a reinforcement layer disposed between the inner surface of the anode plate and the inner surface of the cathode plate in the bead region. The reinforcement layer is configured to resist compressive forces experienced by the outer surface of the anode plate and the outer surface of the cathode plate in the bead region. This aspect may include one or more of the following optional features.

[0014] In some embodiments, the bipolar plate of the pair of bipolar plates further comprises a first gasket and a second gasket. The first gasket is disposed on the outside of the anode plate in the bead region. The second gasket is disposed on the outside of the cathode plate in the bead region. The first gasket and the second gasket engage respective membrane electrode assemblies of the fuel cell stack.

[0015] In some examples, the fuel cell system further includes a chamber defined between the portion of the inner surface of the anode plate in the bead region and the portion of the inner surface of the cathode plate in the bead region. The reinforcement layer extends within the chamber in the bead region.

[0016] In some aspects, the reinforcing layer comprises a rib disposed between the portion of the inner surface of the anode plate and the portion of the inner surface of the cathode plate in the bead region, and not disposed between other portions of the inner surface of the anode plate and other portions of the inner surface of the cathode plate remote from the bead region.

[0017] In some embodiments, the reinforcement layer comprises an intermediate plate disposed between the portion of the inner surface of the anode plate and the portion of the inner surface of the cathode plate in the bead region and between other portions of the inner surface of the anode plate and other portions of the inner surface of the cathode plate remote from the bead region.

[0018] A motor vehicle is also described. The vehicle includes a fuel cell system having a fuel cell stack. The fuel cell stack includes a plurality of fuel cells. At least one fuel cell of the plurality of fuel cells includes a membrane electrode assembly disposed between a pair of bipolar plates. Each bipolar plate of the pair of bipolar plates includes an anode plate and a cathode plate. The anode plate has an inner side and an outer side opposite the inner side. The cathode plate has an inner side and an outer side opposite the inner side. The inner side of the cathode plate faces the inner side of the anode plate. Each bipolar plate includes a bead region. A portion of the inner side of the anode plate in the bead region is spaced from a portion of the inner side of the cathode plate in the bead region.Each bipolar plate includes a reinforcement layer disposed between the inner surface of the anode plate and the inner surface of the cathode plate in the bead region. The reinforcement layer is configured to resist compressive forces experienced by the outer surface of the anode plate and the outer surface of the cathode plate in the bead region. This aspect may include one or more of the following optional features.

[0019] In some embodiments, each bipolar plate of the pair of bipolar plates further includes a first gasket and a second gasket. The first gasket is disposed on the outside of the anode plate in the bead region. The second gasket is disposed on the outside of the cathode plate in the bead region. The first gasket and the second gasket engage respective membrane electrode assemblies of the fuel cell stack.

[0020] In some examples, the vehicle further includes a chamber defined between the portion of the inner surface of the anode plate in the bead region and the portion of the inner surface of the cathode plate in the bead region. The reinforcement layer extends within the chamber in the bead region.

[0021] In some aspects, the reinforcing layer comprises a rib disposed between the portion of the inner surface of the anode plate and the portion of the inner surface of the cathode plate in the bead region, and not disposed between other portions of the inner surface of the anode plate and other portions of the inner surface of the cathode plate remote from the bead region.

[0022] In some embodiments, the reinforcement layer comprises an intermediate plate disposed between the portion of the inner surface of the anode plate and the portion of the inner surface of the cathode plate in the bead region and between other portions of the inner surface of the anode plate and other portions of the inner surface of the cathode plate remote from the bead region.

[0023] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Further aspects, features, and advantages will become apparent from the description and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are for illustrative purposes only, illustrating selected configurations. Fig. 1 is an exploded view of a fuel cell stack of a fuel cell system. Fig. 2 is a top view of a bipolar plate of the fuel cell system. Fig. 3 is a plan view of a reinforcement layer of the bipolar plate. Fig. 4A-4E are cross-sectional views of exemplary configurations of a bead region of the bipolar plate taken along line 4-4 of Fig. 2 have been removed. Fig. Figure 5A is an enlarged view of the bead area of ​​the bipolar plate in area 5A of Fig. 2. Fig. 5B-5D are cross-sectional views of exemplary configurations of bipolar plate bead regions and corresponding pressure gradients along a curved portion of the respective bead region under compression. Fig. Figure 5E is a diagram showing the displacement of the bead areas of Fig. 5B-5D under compression loads.

[0025] Corresponding reference numerals indicate corresponding parts throughout the drawings. DETAILED DESCRIPTION

[0026] Example configurations will now be described in more detail with reference to the accompanying drawings.

[0027] Referring now to the figures and the configurations illustrated therein, a fuel cell system 100 for powering a propulsion system of a vehicle (e.g., a passenger vehicle, a commuter vehicle, a commercial vehicle, and the like) includes a fuel cell stack 102 that includes a plurality of power generation cells or fuel cells 104 ( Fig. 1). Each fuel cell 104 may include a membrane electrode assembly (MEA) 106 or a unitized electrode assembly (UEA) disposed between a pair of bipolar plates (BPPs) 200. For example, the MEA 106 may include a membrane 108 that houses a catalyst 110 (e.g., comprising an anode layer and a cathode layer on opposite sides of the membrane 108). The BPPs 200 provide structural support to the fuel cell stack 102 and electrically connect the fuel cells 104 in series so that electricity generated at the MEAs 106 of the fuel cell stack 102 produces a usable output voltage.

[0028] Each BPP 200 includes an anode plate or panel 202 and a cathode plate or panel 204 ( Fig. 4A-4E). The anode plate 202 and the cathode plate 204 may be formed from a metallic material, carbon, or a composite material. The anode plate 202 and the cathode plate 204 may be formed, for example, from steel, stainless steel (e.g., 304 stainless steel, 316 stainless steel, or ferritic stainless steel), coated steel, aluminum, titanium, or surface-treated metal having a thickness of 85 micrometers or less. The anode plate 202 and the cathode plate 204 are stamped and joined together, such as by welding (e.g., laser welding), brazing, or crimping at the outer peripheries of the plates.When disposed within the fuel cell stack 102, the anode plates 202 and the cathode plates 204 may be arranged in an alternating pattern such that an anode plate 202 engages one side of an MEA 106 and a cathode plate 204 on the opposite side of the MEA 106 to conduct current in a particular direction through the fuel cell stack 102.

[0029] As in Fig. 1 and Fig. 2, corresponding openings and channels 206 are formed through the BPPs 200 and aligned with corresponding openings or channels 112 formed by the MEAs 106 to define passageways along the fuel cell stack 102 that enable fluid communication between the fuel cells 104. For example, the respective passageways extending between the BPPs 200 and the MEAs 106 of the fuel cell stack 102 may carry oxygen-containing gas, hydrogen fuel gas, and coolant to flow between the fuel cells 104 of the fuel cell stack 102. Each BPP 200 defines a flow field 208 across an outer surface of the BPP 200 to facilitate the flow of fluid between the BPP 200 and the MEA 106, where the flow field 208 may include a series of channels or valleys and ledges that direct the flow across the BPP 200 and between two or more openings 206 (i.e.an inlet opening and an outlet opening). The fuel cell system 100 may, for example, include features of the fuel cell systems and fuel cells described in US patents US 10 211 473 B2, US 10 411 272 B2, US 10 522 847 B2 and / or US 10 529 996 B2.

[0030] As described further below, the BPP 200 includes one or more ridges or ridge portions 210, 210a-e that are raised relative to the flow field 208 and that engage corresponding structures within the fuel cell stack 102 to separate a portion of the BPP 200 from the MEA 106, enable fluid communication therebetween, and seal portions of the flow field 208 and restrict fluid flow along desired paths. For example, the ridge 210 may be formed around an outer peripheral portion of the BPP 200 and configured to engage one side of the MEA 106 and / or another BPP 200 to seal the outer peripheral portion of the flow field 208. Further, the bead 210 may be formed at least partially around an opening 206 and configured to engage a side of the MEA 106 to isolate or enable fluid communication between the opening 206 and the flow field 208.That is, the bead 210 may enclose the opening 206 to fluidically isolate the opening 206 and the flow field 208, or the bead 210 may partially enclose the opening 206 to allow fluid flow between the opening 206 and the flow field 208, such that fluid flowing through the opening 206 can be delivered only to specific portions of the fuel cell stack 102. For example, one or more channels or tubes 212 may extend through the bead region 210 between an opening 206 and the flow field 208 to fluidically couple that opening 206 and the flow field 208. Thus, the beads 210 separate the BPP 200 from the MEA 106 to allow oxygen, hydrogen, and / or coolant to flow across the flow field surface 208 of the BPP 200 between the inlet and outlet ports 206.The structural integrity of the beads 210 is critical to prevent leaks and maintain electrical connection across the fuel cells 104.

[0031] As in Fig. 4A-4E, each bead 210 is formed from a protrusion of the anode plate 202 or the cathode plate 204 that engages an adjacent structure (e.g., the MEA 106 or another BPP 200) of the fuel cell stack 102. In the illustrated example, both the anode plate 202 and the cathode plate 204 include corresponding protrusions to provide uniform spacing between the BPPs 200 and the MEAs 106 and more direct paths for compression forces on the fuel cell stack 102. Because the anode plate 202 and the cathode plate 204 are formed from metal plates having a uniform thickness, the respective protrusions are stamped into the plates and result in a chamber or cavity 214 being formed between the anode plate 202 and the cathode plate 204. The chamber 214 can facilitate fluid flow between the opening 206 and the flow field 208.

[0032] Accordingly, the anode plate 202 has an inner side 216 and an outer side 218 opposite the inner side 216, and the cathode plate 204 has an inner side 220 and an outer side 222 opposite the inner side 220. The inner side 216 of the anode plate 202 faces the inner side 220 of the cathode plate 204, with the inner side 216 of the anode plate 202 being spaced from the inner side 220 of the cathode plate 204 in the bead region 210 of the BPP 200 to define the chamber 214 and raise the bead 210 relative to the flow field 208. Portions of the anode plate 202 may be coupled to portions of the cathode plate 204 remote from the bead region 210, such as via laser welds 224, to join the anode plate 202 and the cathode plate 204 and fluidly seal the chamber 214.

[0033] A first seal 226 is disposed on the outer surface 218 of the anode plate 202 within the bead region 210, and a second seal 228 is disposed on the outer surface 222 of the cathode plate 204 within the bead region 210, such that when the BPP 200 is disposed within the fuel cell stack 102, the first seal 226 and the second seal 228 engage respective structures of the fuel cell stack 102 and seal the respective flow fields 208 extending across the outer surface 218 of the anode plate 202 and the outer surface 222 of the cathode plate 204. The seals may, for example, engage one or more of an MEA 106, another BPP 200, an end plate of the fuel cell stack 102, and the like.The first seal 226 and the second seal 228 may be formed from a rubberized polymer or other suitable material configured to be compressed and / or flexed to seal between adjacent surfaces.

[0034] To reduce the compression of the bead region 210 and the lateral movement of the anode plate 202 and the cathode plate 204 relative to each other when a compressive force is experienced at the BPP 200, a reinforcing layer 300 is disposed between the inner surface 216 of the anode plate 202 and the inner surface 220 of the cathode plate 204 at least in the bead region 210. For example, during assembly of the fuel cell stack 102, a compressive force may be applied along the fuel cell stack 102 to maintain electrical connection between the fuel cells 104 and to enable sealing along a sealing path defined by the seals at the bead regions 210. During operation of the vehicle and / or in the event of a vehicle collision, additional forces may act on the bead region 210.Excessive compression or buckling of the bead region 210 can lead to leaks in the flow field 208 and / or electrical disruption between the fuel cells 104. The reinforcement layer 300 strengthens the bead region 210 against buckling loads and provides even pressure distribution across the seal of the bead region 210, thereby reducing or eliminating plate buckling.

[0035] As in Fig. 3, the reinforcement layer 300 may comprise a stamped plate or sheet 302 disposed between the anode plate 202 and the cathode plate 204. The reinforcement layer 300 may be made of the same material as the anode plate 202 and the cathode plate 204, or the reinforcement layer 300 may be formed of a different material, such as a thinner metal (e.g., having a thickness of 75 micrometers or less or 65 micrometers or less) and / or a softer metal (e.g., titanium, aluminum, stainless steel, and the like). In the illustrated example, the reinforcement plate 302 includes corresponding openings 304 configured to align with the openings 112 of the MEAs 106 and the openings 206 of the BPPs 200, and a gap or opening 306 configured to align with the flow field 208.Thus, the reinforcement plate 302 is disposed between the inner surface 216 of the anode plate 202 and the inner surface 220 of the cathode plate 204 in the bead region 210 and in other portions of the BPP 200 remote from the bead region 210.

[0036] With reference to Fig. 4A, a non-inventive example of the bead region 210, 210a includes the reinforcement plate 302 extending transversely and / or within the chamber 214 between the anode plate 202 and the cathode plate 204. Corresponding laser welds 224 may be formed along opposite sides of the chamber 214 to interconnect the anode plate 202, the cathode plate 204, and the reinforcement layer 300. In the illustrated example, the bead region 210a is symmetrical such that the reinforcement plate 302 is substantially planar, and the inner surface 216 of the anode plate 202 and the inner surface 220 of the cathode plate 204 are evenly spaced from the reinforcement layer 300.

[0037] As in Fig. 4B, an example of the present invention includes a reinforcing layer 300 for the bead region 210, 210b provided as a reinforcing rib or insert 308. The rib 308 is disposed between the anode plate 202 and the cathode plate 204 only at or near the bead region 210b, such as to reduce the thickness of the BPP 200 away from the bead region 210. In other words, the rib 308 is disposed between the inner surface 216 of the anode plate 202 and the inner surface 220 of the cathode plate 204 in the bead region 210b, and the rib 308 is not disposed between the inner surface 216 of the anode plate 202 and the inner surface 220 of the cathode plate 204 away from the bead region 210b.The cathode plate 204 includes a recessed portion or support portion 230 recessed from the inner surface 220 of the cathode plate 204 to receive the peripheral edge portions of the rib 308, such that the planar rib 308 may extend substantially parallel to a plane of the cathode plate 204. In some examples, the anode plate 202 may alternatively or additionally include recessed portions for at least partially receiving edge portions of the rib 308. The laser welds 224 may directly connect the anode plate 202 and the cathode plate 204 outside the bead region 210b, while the laser welds 224 couple the anode plate 202, the cathode plate 204, and the rib 308 within the bead region 210b.

[0038] In another example according to the invention of the bead area 210, 210c and as in Fig. 4C, at least a portion of the reinforcement layer 300 is non-planar. In other words, the reinforcement layer 300 may be bent, curved, or prestressed toward the anode plate 202 or the cathode plate 204 to provide an asymmetric bead region 210c. The asymmetric or prestressed reinforcement layer 300 may provide tailored pressure distribution and stiffness across the bead 210c.

[0039] With reference to Fig. 4D, a non-inventive example of the bead region 210, 210d includes one or more perforations or openings 310 formed in the reinforcement layer 300. The perforations 310 relax the stiffness of the bead region 210d and allow fluid communication between the portion of the chamber 214 between the anode plate 202 and the reinforcement layer 300 and the portion of the chamber 214 between the cathode plate 204 and the reinforcement layer 300.

[0040] As in Fig. 4E, a non-inventive example of the bead region 210, 210e illustrates the reinforcement layer 300 coupled at one end to the anode plate 202 and the cathode plate 204 via a laser weld 224, and extending at the other end along a channel 212 of the BPP 200. That is, portions of the reinforcement layer 300 may be spaced from the inner surface 216 of the anode plate 202 and / or the inner surface 220 of the cathode plate 204, for example, along the channels 212, to enable fluid communication from the chamber 214 and between the reinforcement layer 300 and the anode plate 202 and / or the cathode plate 204.

[0041] The bead 210 can be adjusted or tuned (such as by adjusting the geometry and shape of the reinforcement layer 300) to achieve the desired sealing pressure and bead stiffness in different areas of the BPP 200. For example, portions of the bead 210 can be symmetrical (e.g., Fig. 4A) to provide uniform sealing pressure at the first seal 226 and the second seal 228 and to provide high, kink-resistant compression forces at the bead 210. Furthermore, the reinforcement layer 300 may be curved (e.g., Fig. 4C) and / or perforations 310 (e.g. Fig. 4D) to relax the stiffness of the bead, such as in the corner regions of the bead 210. The reinforcing layer 300 may be disposed between the anode plate 202 and the cathode plate 204 across the entire bead sealing path (e.g., a reinforcing plate 302), or the reinforcing layer 300 may be selectively disposed across only a portion of the bead sealing path (e.g., a reinforcing rib 308).

[0042] With reference to Fig. 5A-5E shows a graph 500 illustrating exemplary displacements under compression loading for BPPs having differently configured bead regions. That is, the graph 500 illustrates an exemplary compression of a bead without the reinforcement layer ( Fig. 5B), a one-sided bead when arranged within the fuel cell stack ( Fig. 5C), and the bead region 210 having the reinforcing layer 300 ( Fig. 5D). As illustrated, the bead region 210 including the reinforcement layer 300 provides superior structural integrity for the fuel cell stack, resisting displacement or compression even at higher compression loads.

[0043] Furthermore, the compression diagrams 502, 502b-d of Fig. 5B-5D representative of the compression occurring along the curved portion of the bead in Fig. 5A. As illustrated, the bead region 210 having the reinforcing layer provides a uniform pressure distribution on the first seal 226 and the second seal 228 along the straight and curved portions of the bead seal.

[0044] Thus, the BPP 200 of the fuel cell system 100 includes a reinforcement layer 300 disposed between the anode plate 202 and the cathode plate 204 of the BPP 200 at least in a bead region 210 of the BPP 200. The reinforcement layer 300 provides high resistance to buckling loads on the BPP 200 to reduce compression or buckling of the bead region 210 and provide a more uniform seal between the BPP 200 and adjacent structures within the fuel cell stack 102, such as an adjacent BPP 200 and / or the MEA 106. The reinforcement layer 300 can be adjusted to adjust the stiffness in different portions of the bead region 210 and to enable or prevent fluid communication between different portions of the interior chamber 214 of the bead 210.Furthermore, the reinforcement layer 300 allows the anode plate 202 and the cathode plate 204 to be made of thinner and / or softer metal plates, resulting in a weight reduction of the fuel cell stack 102 without compromising structural integrity.

Claims

[1] Bipolar plate (200), comprising: an anode plate (202) having an inner side (216) and an outer side (218) opposite the inner side (216); a cathode plate (204) having an inner side (220) and an outer side (222) opposite the inner side (220), the inner side (220) of the cathode plate (204) facing the inner side (216) of the anode plate (202); a bead region (210) formed around an outer peripheral region of the bipolar plate (200) or around a reactant opening formed in the bipolar plate (200), wherein a portion of the inner side (216) of the anode plate (202) in the bead region (210) is spaced from a portion of the inner side (220) of the cathode plate (204) in the bead region (210), wherein a chamber (214) is defined between the portion of the inner side (216) of the anode plate (202) in the bead region (210) and the portion of the inner side (220) of the cathode plate (204) in the bead region (210), within which a reinforcement layer (300) extends in the bead region (210); and wherein the reinforcement layer (300) is configured to withstand compressive forces experienced on the outer side (218) of the anode plate (202) and the outer side (222) of the cathode plate (204) in the bead region (210); characterized by , that the bead region (210) is asymmetric in that the reinforcing layer (300) is uneven and the portion of the inner side (216) of the anode plate (202) in the bead region (210) and the portion of the inner side (220) of the cathode plate (204) in the bead region (210) are unevenly spaced from the reinforcing layer (300). [2] The bipolar plate (200) of claim 1, further comprising: a first seal (226) disposed on the outer side (218) of the anode plate (202) in the bead region (210); and a second seal (228) disposed on the outer side (222) of the cathode plate (204) in the bead region (210), wherein the first seal (226) and the second seal (228) are configured to engage corresponding membrane electrode assemblies (106) of a fuel cell stack (102) of a fuel cell system (100) when the bipolar plate (200) is disposed in the fuel cell stack (102). [3] The bipolar plate (200) of claim 2, wherein the first seal (226) and the second seal (228) are configured to seal the respective flow fields extending across the outer surfaces (218, 222) of the anode plate (202) and the cathode plate (204) when engaging the respective membrane electrode assemblies (106) of the fuel cell stack (102). [4] The bipolar plate (200) of claim 3, wherein the reinforcement layer (300) comprises an opening (310) fluidly connecting a first portion of the chamber (214) between the inner surface (216) of the anode plate (202) and the reinforcement layer (300) and a second portion of the chamber (214) between the inner surface (220) of the cathode plate (204) and the reinforcement layer (300). [5] The bipolar plate (200) of claim 1, wherein the reinforcement layer (300) comprises an intermediate plate disposed between the portion of the inner surface (216) of the anode plate (202) and the portion of the inner surface (220) of the cathode plate (204) in the bead region (210) and between other portions of the inner surface (216) of the anode plate (202) and other portions of the inner surface (220) of the cathode plate (204) remote from the bead region (210). [6] The bipolar plate (200) of claim 1, wherein the reinforcement layer (300) is non-planar. [7] The bipolar plate (200) of claim 1, wherein the reinforcement layer (300) is laser welded to the anode plate (202) and the cathode plate (204). [8] Bipolar plate (200), comprising: an anode plate (202) having an inner side (216) and an outer side (218) opposite the inner side (216); a cathode plate (204) having an inner side (220) and an outer side (222) opposite the inner side (220), the inner side (220) of the cathode plate (204) facing the inner side (216) of the anode plate (202); a bead region (210) formed around an outer peripheral region of the bipolar plate (200) or around a reactant opening formed in the bipolar plate (200), wherein a portion of the inner side (216) of the anode plate (202) in the bead region (210) is spaced from a portion of the inner side (220) of the cathode plate (204) in the bead region (210), wherein a chamber (214) is defined between the portion of the inner side (216) of the anode plate (202) in the bead region (210) and the portion of the inner side (220) of the cathode plate (204) in the bead region (210), within which a reinforcement layer (300) extends in the bead region (210); and wherein the reinforcement layer (300) is configured to withstand compression forces experienced on the outer side (218) of the anode plate (202) and the outer side (222) of the cathode plate (204) in the bead region (210); and wherein the reinforcement layer (300) comprises a rib (308) disposed between the portion of the inner side (216) of the anode plate (202) and the portion of the inner side (220) of the cathode plate (204) in the bead region (210), and not disposed between other portions of the inner side (216) of the anode plate (202) and other portions of the inner side (220) of the cathode plate (204) remote from the bead region (210); characterized by , that the cathode plate (204) and / or the anode plate (202) has / has recessed portions (230) that receive edge portions of the rib (308); wherein the rib (308) is flat and extends parallel to a plane of the cathode plate (204); and wherein the anode plate (202) and the cathode plate (204) outside the bead region (210) are directly connected to one another by means of laser welds (224), and wherein the anode plate (202), the cathode plate (204) and the rib (308) are coupled to one another within the bead region (210) by means of additional laser welds (224).

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