Fuel cell bipolar plate

Abstract

A hydrogen fuel cell unit made from identical bipolar plates stamped from a single sheet of metal includes, in order: (i) a first bipolar plate having a front side and a back side, the back side being an anode in the unit, (ii) a first membrane electrode assembly, (iii) a second bipolar plate having a front side and a back side, the front side being a cathode in the unit, the back side being an anode in the unit, wherein the first membrane electrode assembly is located between the first and second bipolar plates, a hydrogen gas flow path is provided between the back side of the first bipolar plate and the first membrane electrode assembly, and an oxygen gas flow path is provided between the front side of the second bipolar plate and the first membrane electrode assembly, (iv) a second membrane electrode assembly, (v) a third bipolar plate having a front side and a back side, the front side being a cathode in the unit, wherein the second membrane electrode assembly is located between the second and third bipolar plates, a hydrogen gas flow path is provided between the back side of the second bipolar plate and the second membrane electrode assembly, and an oxygen gas flow path is provided between the front side of the third bipolar plate and the second membrane electrode assembly.

Description

Technical Field

[0001] This invention relates to bipolar plates for hydrogen fuel cells (particularly PEM fuel cells) and methods for their fabrication. Background Technology

[0002] A growing awareness of the impacts of climate change has led to increased research into alternative "fossil-free" energy sources, such as hydrogen. Hydrogen fuel cells have been developed that generate electricity by electrochemically (usually catalytically) oxidizing hydrogen to produce water.

[0003] The most widely used hydrogen fuel cell is the proton exchange membrane (PEM) fuel cell, which includes a semi-permeable membrane that allows protons to pass through while acting as a barrier between electrons and reactants such as hydrogen and oxygen. PEM fuel cells offer many advantages, including high energy conversion efficiency, environmental friendliness, and low operating temperature.

[0004] Because each cell in a PEM fuel cell produces a relatively low voltage, multiple PEM cells can be connected in series to increase the output voltage. Multi-cell assemblies are sometimes referred to as fuel cell stacks. Adjacent PEM cells are connected together, with the cathode of one cell connected to the anode of another, effectively forming bipolar plates that conduct current from one PEM cell to the adjacent PEM cell. Each cathode and anode plate, and thus each half of the bipolar plate, typically also contains channels on its surface along which reactants or coolant can be supplied. As a core component of hydrogen fuel cells, bipolar plates have many important functions, including conducting current, supporting the membrane electrode assembly, uniformly delivering and isolating reactant gases and circulating coolant for rapid cooling.

[0005] When connecting adjacent PEM cells, bipolar plates are formed by two separate plates (anode and cathode) from the adjacent cells. These plates are typically welded together. Several issues arise with this. In particular, oxidation and corrosion at the weld joints can reduce the efficiency of the bipolar plates. However, bipolar plates are standard practice in this field when multiple cells are connected in series.

[0006] US 2020 / 212470 discloses a fuel cell unit formed by a plurality of flow plate assemblies arranged in a stacked configuration, with adjacent flow plate assemblies arranged at an skew angle relative to each other.

[0007] DE 10 2020 207353 discloses a bipolar plate for a fuel cell system, wherein the plates are aligned such that the coolant flows through a first channel structure and a second channel structure are different.

[0008] US 2015 / 325876 discloses a fuel cell having an anode / cathode stack with a first channel structure and a second channel structure, wherein the first channel structure and the second channel structure have a first feed structure and a second feed structure, respectively.

[0009] US 4292 379 discloses a fuel cell system designed to mitigate uneven reaction distribution.

[0010] US 2019 / 169759 discloses a stack of interconnected solid oxide electrochemical gas separator (SOEGS) cells separated by interconnects.

[0011] The object of this invention is to improve upon the problems of known fuel cell stacks, or to provide an alternative to the bipolar plates between known fuel cell stacks and adjacent fuel cells. Specific embodiments aim to provide an improved bipolar plate for a fuel cell stack, a fuel cell stack comprising one or more improved bipolar plates, and methods for manufacturing them. Summary of the Invention

[0012] This invention provides a hydrogen fuel cell unit, which comprises, in sequence: (i) A first bipolar plate having a front side and a back side, wherein the back side is the anode in the cell. (ii) First membrane electrode assembly, (iii) A second bipolar plate having a front side and a back side, wherein the front side is the cathode of the unit and the back side is the anode of the unit. The first membrane electrode assembly is located between the first bipolar plate and the second bipolar plate. A flow path for hydrogen flow is provided between the back side of the first bipolar plate and the first membrane electrode assembly, and a flow path for oxygen flow is provided between the front side of the second bipolar plate and the first membrane electrode assembly. (iv) Second membrane electrode assembly, and (v) A third bipolar plate having a front and a back side, the front side being the cathode in the unit. The second membrane electrode assembly is located between the second bipolar plate and the third bipolar plate. A flow path for hydrogen flow is provided on the back side of the second bipolar plate and between the second membrane electrode assembly, and a flow path for oxygen flow is provided on the front side of the third bipolar plate and between the second membrane electrode assembly.

[0013] Preferably, the bipolar plate includes channels for oxygen flow, wherein oxygen flow channels of adjacent plates repeatedly diverge and converge on the plates, for example in a cross-shaped pattern.

[0014] The present invention also provides a method for preparing a bipolar plate, comprising: (i) Provide metal or alloy sheets; (ii) Stamping the sheet to form a bipolar plate comprising multiple hydrogen channels and multiple oxygen channels, The bipolar plate described therein can be used to manufacture hydrogen fuel cell units according to the present invention.

[0015] Furthermore, the present invention also provides a method for preparing a hydrogen fuel cell, comprising: (i) A first bipolar plate and a second bipolar plate are provided, the first bipolar plate having a front side and a back side, the front side being a cathode, and the second bipolar plate having a front side and a back side, the front side being a cathode and the back side being an anode. (ii) Position the first membrane electrode assembly between the first bipolar plate and the second bipolar plate. When the first membrane electrode assembly is located between the first bipolar plate and the second bipolar plate, a flow path for hydrogen flow is provided between the back side of the first bipolar plate and the first membrane electrode assembly, and a flow path for oxygen flow is provided between the front side of the second bipolar plate and the first membrane electrode assembly. (iv) Provide a third bipolar plate having a front side and a back side, the front side being a cathode, and (v) Position the second membrane electrode assembly between the second bipolar plate and the third bipolar plate. When the second membrane electrode assembly is located between the second bipolar plate and the third bipolar plate, a flow path for hydrogen flow is provided on the back side of the second bipolar plate and between the second membrane electrode assembly, and a flow path for oxygen flow is provided on the front side of the third bipolar plate and between the second membrane electrode assembly.

[0016] All panels can be of the same design, each made of stamped sheet of metal or alloy, with adjacent panels rotated 180 degrees relative to each other.

[0017] Therefore, the hydrogen fuel cell unit of the present invention comprises, in sequence: (i) A first bipolar plate having a front side and a back side, wherein the back side is the anode in the cell. (ii) First membrane electrode assembly, (iii) A second bipolar plate having a front side and a back side, wherein the front side is the cathode of the unit and the back side is the anode of the unit. The first membrane electrode assembly is located between the first bipolar plate and the second bipolar plate (e.g., between the back side of the first bipolar plate and the front side of the second bipolar plate). A flow path for hydrogen flow is provided between the back side of the first bipolar plate and the first membrane electrode assembly, and a flow path for oxygen flow is provided between the front side of the second bipolar plate and the first membrane electrode assembly. (iv) Second membrane electrode assembly, and (v) A third bipolar plate having a front and a back side, the front side being the cathode in the unit. The second membrane electrode assembly is located between the second bipolar plate and the third bipolar plate (e.g., between the back side of the second bipolar plate and the front side of the third bipolar plate). A flow path for hydrogen flow is provided between the back side of the second bipolar plate and the second membrane electrode assembly, and a flow path for oxygen flow is provided between the front side of the third bipolar plate and the second membrane electrode assembly.

[0018] The plates contain channels for hydrogen flow (also called hydrogen flow channels), each channel having an inlet and an outlet. The respective inlets and outlets of the hydrogen flow channels of adjacent plates in the fuel cell unit are properly vertically aligned in the vertical stacking of the plates. In this stacking, this simplifies the design of gaskets between the plates; for example, the same gasket can always be used on the cathode side of each plate (e.g., to seal the hydrogen inlet and outlet on the cathode side of the plate to prevent hydrogen flow on the cathode side).

[0019] Each hydrogen flow channel also includes a conduit located between its inlet and outlet. The conduits or channels of adjacent plates in a fuel cell are preferably not vertically aligned along their entire length. Therefore, adjacent plates do not nest together when secured (e.g., clamped) to a stack that is part of the fuel cell. The abutting portions of adjacent plates secure the membrane electrode assembly between the adjacent plates, thereby assisting in sealing the hydrogen and oxygen channels to isolate these respective channels from each other. The misalignment of the channels along their partial length also means that adjacent plates support each other in the stack and seal the membrane electrode assembly between the bipolar plates.

[0020] As illustrated in the example described in more detail below, the hydrogen flow channels of adjacent plates can have their respective inlets vertically aligned, then the hydrogen flow channels branch and converge on the plates, finally converging at the vertically aligned outlets. The hydrogen flow channels can repeatedly branch and converge on the plates, for example, in a cross-shaped pattern (regardless of whether the inlets and outlets of adjacent plates are vertically aligned). In a preferred embodiment, the hydrogen flow channels of adjacent plates can branch and converge in a regular pattern.

[0021] The plates contain channels for oxygen flow (also called oxygen flow channels), each channel having an inlet and an outlet. The respective inlets and outlets of the oxygen flow channels of adjacent plates in a fuel cell can also be independently aligned, appropriately arranged vertically in the vertical stacking of the plates. Similarly, the gasket design can therefore be simplified, as the same gasket can be used on the anode side of each plate (e.g., to seal the oxygen inlet and outlet on the anode side of the plate to prevent oxygen flow on the anode side).

[0022] Furthermore, each oxygen flow channel includes a conduit located between its inlet and outlet. The conduits of the oxygen flow channels of adjacent plates in the fuel cell are not vertically aligned along their entire length. This also prevents nesting of adjacent plates and helps to secure the membrane electrode assembly tightly between the plates in a hermetically sealed manner. Due to the partial misalignment, adjacent plates can better support each other in a stack; preferably, both the hydrogen flow channel portions and the oxygen flow channel portions are misaligned.

[0023] As illustrated in the examples described in more detail below, the oxygen flow channels of adjacent plates can have their respective inlets vertically aligned, and the oxygen flow channels branch and converge on the plates, finally converging at the vertically aligned outlets. The oxygen flow channels can repeatedly branch and converge on the plates, for example, in a cross-shaped pattern (regardless of whether the inlets and outlets of adjacent plates are vertically aligned). In a preferred embodiment, the oxygen flow channels of adjacent plates can branch and converge in a regular (i.e., repetitive) pattern.

[0024] Referring to the example below, it will be understood that hydrogen and oxygen flow channels can be defined by a combination of a recess in a plate and a membrane electrode assembly held between that plate and an adjacent plate.

[0025] As illustrated in more detail in the following embodiments, the bipolar plate may include hydrogen flow channels and oxygen flow channels that are substantially transverse to each other. For example, the hydrogen flow channels may cross the plate substantially from left to right, while the oxygen flow channels may cross the plate substantially from back to front, or vice versa. Suitablely, most of the hydrogen flow channels and oxygen flow channels are substantially transverse (perpendicular). In a specific embodiment, all hydrogen flow channels are substantially transverse (perpendicular) to all oxygen flow channels.

[0026] One advantage of this invention is that each plate can be stamped from a single sheet without welding or otherwise connecting the respective anode and cathode sides to form a de facto bipolar plate. Instead, each stamped plate of this invention forms a bipolar plate on its own.

[0027] The hydrogen and oxygen flow channels are formed by a plate, preferably a stamped plate, at an interface with a membrane electrode assembly (MEA), which is fixed between two plates. Protrusions on the plates engage with the membrane seal, and recesses on the plates form channels between the recesses and the MEA.

[0028] According to an embodiment of the invention, for lateral flow, the hydrogen and oxygen channels traverse each other. The oxygen flow channel can be suitably formed by a recess in the bipolar plate, and the lateral hydrogen flow channel can simultaneously include a notch in the recess forming the oxygen flow channel. The notch can lower the height of the oxygen channel at that point, forming a hydrogen channel on the other side between the notch and the MEA. Conversely, the opposite is also true. Therefore, the hydrogen flow channel can be formed by a recess in the bipolar plate, while the lateral oxygen flow channel can include a notch in the recess forming the hydrogen flow channel.

[0029] In embodiments of the invention, one effect of the intersection of the hydrogen flow channel and the oxygen flow channel is that, as described above, the bipolar plate can be stamped from a single sheet. As shown in the following embodiment, when the plates are stacked vertically on top of each other, a horizontal cross-section of the plate (i.e., a plane passing through the center of each plate, perpendicular to the vertical direction of the stack) can be taken such that this cross-section passes through both the hydrogen flow channel and the oxygen flow channel. This is not the case for known hydrogen fuel cell stacks.

[0030] In a preferred embodiment of the invention, all plates, such as each of the first, second, and third bipolar plates in a hydrogen fuel cell unit, are of the same design. This means that not only can the plates be manufactured by stamping, but only a single stamping tool is required. Adjacent plates are conveniently arranged in a stack, rotated 180 degrees relative to each other (appropriately around an axis perpendicular to the plate plane). The asymmetric plate design means that the plates can be efficiently stacked together to form hydrogen and oxygen flow channels, without nesting channels in adjacent plates, while maintaining sufficient plate-to-plate contact to hold the MEA between the plates, thereby forming a sealed channel that separates the hydrogen and oxygen sides.

[0031] In such an implementation, the bipolar plates do not possess rotational symmetry in the vertical direction of the stack about a line passing through the center of the plate (i.e., a line perpendicular to the plane of the plate passing through the center of the plate). Therefore, by rotating adjacent bipolar plates 180 degrees relative to each other, the recesses on the plates become misaligned, meaning the plates cannot be nested. In a preferred embodiment, the lack of rotational symmetry is attributed to the shape design of the oxygen flow channels.

[0032] In embodiments where the bipolar plates do not possess overall rotational symmetry, rotational symmetry may still exist between specific features or elements of the plates. For example, the manifold orifices of each plate may have rotational symmetry. Preferably, the manifold orifices on each bipolar plate have second-order rotational symmetry. That is, when any bipolar plate rotates 180 degrees from a first position to a second position about a line passing through the center of the plate in a direction perpendicular to the plate stack, the position of the manifold orifice in the first position maps to the position of the manifold orifice in the second position. This rotational symmetry allows the manifold orifices of adjacent plates to be vertically aligned, forming a manifold.

[0033] Independently, the inlets and outlets of the hydrogen and / or oxygen flow channels on the bipolar plates can have rotational symmetry (e.g., second-order rotational symmetry). Preferably, the inlets and outlets of the hydrogen and / or oxygen flow channels on each bipolar plate have second-order rotational symmetry. That is, when any bipolar plate is rotated 180 degrees from a first position to a second position about a line passing through the center of the plate in the vertical direction of the plate stack, the positions of the inlets and outlets of the hydrogen and / or oxygen flow channels on each bipolar plate in the first position map to the positions of the inlets and outlets in the second position. Such rotational symmetry allows the inlets and outlets of the hydrogen and / or oxygen flow channels to be vertically aligned in the plate stack, where adjacent plates are rotated 180 degrees relative to each other, as described above.

[0034] In alternative embodiments of the invention, different stamping tools are used to form adjacent bipolar plates (e.g., the first and third bipolar plates are stamped using the same stamping tool, while the second bipolar plate is stamped using a different stamping tool). When two (or more) stamping tools are used, adjacent plates do not need to be rotated to prevent channel nesting between adjacent plates. In these embodiments, a two-bipolar-plate design is preferred, wherein the hydrogen flow channels and / or oxygen flow channels of adjacent plates are not aligned along their entire length, thereby preventing nesting between adjacent plates.

[0035] In such an implementation with two bipolar plate designs, it is preferable that certain features or elements remain in the same location in both designs. For example, the manifold orifice, as well as the inlet and outlet of separate hydrogen and / or oxygen flow channels, are preferably located in the same location in both designs.

[0036] This document also provides a bipolar plate for use in the fuel cell unit of the present invention, wherein the bipolar plate does not have rotational symmetry about a line passing through the center of the plate in a direction perpendicular to the plate stack (i.e., a plane perpendicular to the plate). The bipolar plate is suitable to be any one of the first, second, and / or third bipolar plates in the aforementioned hydrogen fuel cell unit.

[0037] In a preferred embodiment, the lack of rotational symmetry is attributed to the shape of the oxygen flow channels. As mentioned above, even in embodiments where the bipolar plate does not have overall rotational symmetry, rotational symmetry can still exist between specific features or elements of the plate. For example, as described above, rotational symmetry can still exist between manifold orifices on the bipolar plate, or between the inlet and outlet of the hydrogen flow channels and / or oxygen flow channels. The rotational symmetry of a particular element can be second-order rotational symmetry, i.e., with each 360-degree rotation, the element will map onto itself twice. In a preferred embodiment, the bipolar plate includes two or more manifold orifices, and the manifold orifices have rotational symmetry. Particularly preferred is that the rotational symmetry of the manifold orifices is second-order rotational symmetry.

[0038] The bipolar plate is preferably stamped from a single sheet of metal or alloy (e.g., steel, titanium, or aluminum, or alloys thereof). It can be coated with, for example, ta-C. Preferably, the bipolar plate has no weld joints, i.e., no welding step is performed during the formation of the bipolar plate.

[0039] This article also provides a method for preparing bipolar plates, including... (i) Provide metal or alloy sheets; (ii) Stamping the sheet to form a bipolar plate containing multiple hydrogen channels and multiple oxygen channels, The bipolar plate described herein can be used to prepare a hydrogen fuel cell unit according to the present invention, including any of its embodiments and preferred embodiments or combinations of features.

[0040] The method preferably does not include a welding step.

[0041] The present invention also provides a method for manufacturing a hydrogen fuel cell, comprising: (i) A first bipolar plate and a second bipolar plate are provided, the first bipolar plate having a front side and a back side, the front side being a cathode, and the second bipolar plate having a front side and a back side, the front side being a cathode and the back side being an anode. (ii) Position the first membrane electrode assembly between the first bipolar plate and the second bipolar plate. When the first membrane electrode assembly is located between the first bipolar plate and the second bipolar plate (e.g., between the back side of the first bipolar plate and the front side of the second bipolar plate), a flow path for hydrogen flow is provided between the back side of the first bipolar plate and the first membrane electrode assembly, and a flow path for oxygen flow is provided between the front side of the second bipolar plate and the first membrane electrode assembly. (iv) Provide a third bipolar plate having a front side and a back side, the front side being a cathode, and (v) Position the second membrane electrode assembly between the second bipolar plate and the third bipolar plate. When the second membrane electrode assembly is located between the second bipolar plate and the third bipolar plate (e.g., between the back side of the second bipolar plate and the front side of the third bipolar plate), a flow path for hydrogen flow is provided between the back side of the second bipolar plate and the second membrane electrode assembly, and a flow path for oxygen flow is provided between the front side of the third bipolar plate and the second membrane electrode assembly.

[0042] Preferred methods for preparing hydrogen fuel cells include one or more or all of the optional or preferred features of the invention described elsewhere herein.

[0043] In the method, the bipolar plates preferably have the same design, with adjacent plates rotated 180 degrees relative to each other.

[0044] A method for preparing a hydrogen fuel cell unit, comprising: (i) Provide sheet metal or alloy; (ii) Stamping the sheet to form a bipolar plate containing multiple hydrogen channels and multiple oxygen channels, (iii) Repeat steps (i) and (ii) at least once to provide multiple similar bipolar plates, and (iv) Arrange multiple similar bipolar plates in a stack, with adjacent plates rotated 180 degrees relative to each other.

[0045] Another method for preparing hydrogen fuel cell units includes: (i) Provide multiple similar bipolar plates, each bipolar plate including multiple hydrogen channels and multiple oxygen channels, and (ii) Arrange the plurality of similar bipolar plates in a stack, with adjacent plates rotated 180 degrees relative to each other.

[0046] The bipolar plates can therefore be used to fabricate hydrogen fuel cell units according to the invention, including combinations of features according to any and preferred embodiments or those described herein. Exemplary stacks include five or more, or particularly ten or more, similar bipolar plates.

[0047] Gaskets are conventional in hydrogen fuel cells and are suitably used in this invention between adjacent plates to prevent leakage between the respective hydrogen and oxygen sides of the fuel cell, to provide seals between the hydrogen flow channel inlets and outlets and between the hydrogen manifold, as is conventionally present in hydrogen fuel cells, and to seal the top and bottom plates of the stack to the current collector. Including an oxygen manifold is optional; if present, gaskets can be used to seal the oxygen flow channel inlets and outlets to the oxygen manifold.

[0048] In a preferred embodiment, a first washer (referred to as a cathode washer) is used on the cathode side of all bipolar plates, and a second washer is used on the anode side of all bipolar plates (referred to as an anode washer). Preferably, all cathode washers are identical (i.e., have the same shape), and all anode washers are identical (i.e., have the same shape). In some embodiments, the anode current collector may require a third washer, and the cathode current collector may require a fourth washer. In other preferred embodiments, the first washer (i.e., the washer used on the cathode side of all plates) is used on the cathode current collector, and the second washer (i.e., the washer used on the anode side of all plates) is used on the anode current collector. Separate washers for the end plates may also be required.

[0049] Therefore, the method appropriately includes adding a hydrogen manifold and a current collector, positioning washers between the respective components, and clamping the plates, washers, and other components together.

[0050] The single-plate bipolar plate of this invention does not require welding between adjacent plates. Therefore, oxidation and corrosion that occur in previously welded plates are avoided.

[0051] Individual bipolar plates can be thinner than those currently available, requiring less material. This can reduce the overall size and / or weight of hydrogen fuel cell stacks to a level comparable to welded stack output.

[0052] Individual bipolar plates can have the same design, differing only in orientation from one layer to the next in the plate stack, reducing the complexity of plate fabrication and stack structure. A single stamping tool can be used to fabricate all the plates in the stack.

[0053] It has been found that the individual plates used in embodiments of the present invention can be easily and reliably sealed to each other by using internal gaskets and MEAs. Attached Figure Description

[0054] The present invention is described with reference to the accompanying drawings, in which: Figure 1 The diagram shows a known bipolar plate in a fuel cell stack; Figure 2 An assembly of a known anode and cathode plate forming a bipolar plate is shown; Figure 3 The top and side views of the bipolar plate of the present invention are shown; Figure 4 A top view of one side of the bipolar plate of the present invention is shown; Figure 5 This is a top view showing the channels of two independent bipolar plates of the present invention, one bipolar plate being directly stacked on the other bipolar plate, the two plates having the same shape and configuration, and one bipolar plate being rotated 180 degrees relative to the other bipolar plate; Figure 6 It shows Figure 4A top view of a bipolar plate, with a proton exchange membrane at the top, the proton exchange membrane sealing the anode side of the bipolar plate; Figure 7 It shows Figure 4 A top view of the bipolar plate, showing the anode gasket on the plate; Figure 8 It shows Figure 4 A top view of the bipolar plate, showing the cathode gasket on the plate; Figure 9 A partial top and side view of the bipolar plate stack of the present invention is shown, revealing a cross-section through the stack and illustrating the airflow channels; Figure 10 It shows the center of the fuel cell stack and Figure 9 A more detailed cross-section in the same direction; Figure 11 It shows the direction perpendicular to Figure 9 and Figure 10 The direction of the hydrogen flow path is shown through the cross-section of the fuel cell stack; Figure 12 A more detailed cross-section is shown at the edge of the fuel cell stack, with the cross-section oriented in the same direction as... Figure 11 same; Figure 13 A top view of another alternative embodiment of the bipolar plate of the present invention is shown; Figure 14 It shows Figure 13 The illustrated embodiment is a top view of the channels of two separate bipolar plates, one plate being directly stacked on the other bipolar plate. The two bipolar plates have the same shape and configuration, with one bipolar plate rotated 180 degrees relative to the other bipolar plate. Figures 15a and 15b show top views of another embodiment of the bipolar plate of the present invention; Figure 16 A top view of another embodiment of the bipolar plate of the present invention is shown, the bipolar plate having a closed cathode for use with an oxygen manifold; Figures 17a and 17b show top views of another embodiment of the bipolar plate of the present invention, the bipolar plate having a closed cathode for use with an oxygen manifold; Figure 18 Top and side views of a fuel cell incorporating the bipolar plate stack of the present invention are shown; Figure 19 It shows Figure 18 An exploded view of a fuel cell stack; Figure 20 It shows crossing Figure 18 and 19 Top and side views of the cross-section at the center of the fuel cell stack, showing the flow channels; Figure 21 It shows the relationship with Figure 20 A more detailed cross-section in the same direction shows the conduit connected to the hydrogen manifold; Figure 22 It shows the relationship with Figure 20 Similar cross-sections in the same direction, but passing through the peripheral gasket; Figure 23 It shows the line and Figure 20-22 More detailed partial cross-sectional views of the gasket passing through the surrounding gasket in the same direction; Figure 24 It shows crossing Figure 18 Top and side views of the cross-section at the center of the fuel cell stack, oriented with... Figure 20-23 Vertical, showing the hydrogen flow channel; Figure 25 It shows the relationship with Figure 24 A more detailed cross-section in a similar orientation, but viewed from the side, shows the hydrogen flow channel and the surrounding gasket; Figure 26 It shows the relationship with Figure 24 Similar cross-sections in the same direction, but passing through an additional portion of the cathode gasket; Figure 27 A more detailed partial cross-section is shown through the cathode gasket attachment, oriented in the same direction as... Figure 26 Similar, but viewed from the side; Figure 28 A top view and a side view of another alternative embodiment of the bipolar plate of the present invention are shown; Figure 29 It shows Figure 28 A top view of the bipolar plate; Figure 30 It shows Figure 28 A top view of the anode side of the bipolar plate, showing the anode gasket; Figure 31 It shows Figure 28 Top view of the bipolar plate cathode side, showing the cathode gasket; Figure 32a , 32b 32c respectively showed Figure 28-31 The diagram shows a top view and a side view of the anode gasket, cathode gasket, and end plate gasket of an embodiment of the present invention. Figure 33 It shows crossing Figure 28 Bipolar anode gasket characteristics (along) Figure 29 The cross-section of line A in the diagram; Figure 34 It shows according to Figure 28 Bipolar plate stack (parallel to) Figure 29 The edge view of line A in the middle; Figure 35It shows crossing Figure 28 Hydrogen inlet channel of bipolar plate (along) Figure 29 The cross-section of line B in the diagram; Figure 36 It shows crossing Figure 28 The center of the bipolar plate (along) Figure 29 The cross section of line C in the diagram; and Figures 37 to 40 yes Figures 33 to 36 The color version is equivalent to the others in all other respects. Detailed Implementation

[0055] refer to Figure 1 and Figure 2 For reference, known bipolar plate assemblies include alternating bipolar plates 1 and membrane electrode assemblies (MEAs) 2, separated by a gas diffusion layer 3. Each known bipolar plate 1 actually includes an anode plate 5 of a first cell, a cathode plate 6 of an adjacent cell, and a weld 7 to form the bipolar plate. The anode plate 5 and the cathode plate 6 are thus welded together to form the bipolar plate, with a gasket 8 on either side of the bipolar plate.

[0056] refer to Figure 3 and Figure 4 The bipolar plate 10 of the present invention is formed as a single stamped steel plate with two sides, located in the middle of a fuel cell stack. One side is formed and serves as the anode side 11, and the other side is formed and serves as the cathode side 12; the plates at the top and bottom of the stack are respectively the anode or cathode. The bipolar plate of the present invention also has a through-hole 14 at each end for sealing hydrogen manifolds (not shown here, but shown in the figures below) connected to the top and bottom of the stack within the plate stack. The hole allows H2 to flow from the inlet manifold (not shown) along and through the anode side of the plates in the stack, via H2 channel 16 to the outlet manifold (not shown). Hydrogen flows longitudinally through the plates, and escape is prevented by gaskets (not shown here, but shown in the figures below) and proton exchange membranes (not shown) held between adjacent plates in the gasket channel 18. Hydrogen escape from the H2 manifold hole 14 on the cathode side of the bipolar plate is prevented only by an additional gasket portion (not shown here, but shown in the figures below) present only on the cathode side of the bipolar plate. Therefore, hydrogen can flow into the channel on the anode side but not into the channel on the cathode side. The bipolar plate of the present invention further has an air channel 17 on the cathode side 12 of the plate, through which air flows laterally across the width 20 of the plate on the cathode side. The air flow (lateral) is substantially perpendicular (transverse) to the hydrogen flow flow (longitudinal). When the bipolar plate is observed alone (i.e., without gaskets or MEA), there is no difference between the anode and cathode sides of the bipolar plate (except for orientation); however... Figure 4 The cathode side 11 is marked as a bipolar plate.

[0057] Figure 5The diagram shows two bipolar plates 10 of the present invention, one on top of the other. The top bipolar plate is partially transparent (for illustrative purposes only) so that the hydrogen channel of the lower plate (not labeled, but referenced) is visible in the figure. Figure 4 And air channels 17a and 17b. The orientation of the plates alternates: adjacent bipolar plates in the fuel cell stack rotate 180 degrees around a line perpendicular to the plate surface at the plate center. The channels are intentionally designed so that the air channels 17 of adjacent bipolar plates are not perfectly aligned, i.e., not aligned along their entire length: in Figure 5 As can be seen, the air channels 17a of the top plate are vertically aligned at their edges (i.e., the inlet and outlet), but then cross in opposite directions, their paths repeatedly branching and then converging, so that they are not completely aligned with the air channels 17b of the lower plate. The plate design intentionally results in the air channels of adjacent plates (i.e., one plate rotates relative to the next) being partially misaligned, so that the channels of adjacent plates do not fit together or "nest," and allows the MEA (not shown) to be clamped between adjacent plates, held at the point where the lower surface of one plate intersects the upper surface of the other, without falling into or being pushed into the air channels 17, as this would reduce airflow and / or damage the seal.

[0058] The curvature of the channels is also important. The air channels are not straight to prevent partial compression / collapse of the fuel cell stack. In the bipolar plates of this invention, the alternating bipolar plates in the fuel cell stack rotate 180°. Therefore, because the air channels on adjacent plates are not parallel, the plates cannot nest with each other. This is important for providing support from one plate to the next and for preventing the air and hydrogen channels from being blocked by the channels on adjacent plates pressing against each other. The partially non-parallel channels between adjacent plates also allow the proton exchange membrane, as well as the anode and cathode gaskets, to be securely clamped between the adjacent plates to prevent H2 leakage from the cell and to prevent H2 and air from mixing within the fuel cell.

[0059] Figure 6 The MEA membrane 20 on the anode side 11 of the bipolar plate of the present invention is shown. The membrane extends across the width of the bipolar plate between gasket channels 18 (where gaskets are present) on both sides, and extends across the length of the bipolar plate between H2 manifold orifices 14 at each end of the bipolar plate. The membrane allows H2 to flow longitudinally through the plate via hydrogen channels (not shown) from the H2 manifold (not shown) and into the H2 manifold orifice at the other end of the bipolar plate without escaping or leaking to the cathode side of the adjacent bipolar plate.

[0060] Figure 7 and Figure 8The gaskets on the anode and cathode sides of the bipolar plate of the present invention are shown respectively. The anode gasket 22 bypasses the outside of the bipolar plate in the gasket channel 18; this prevents H2 leakage and allows H2 to flow through the H2 channel. The cathode gasket 23 includes an additional portion 23a that prevents H2 from flowing out from the H2 manifold channel on the cathode side of the bipolar plate.

[0061] Figure 9 and Figure 10 It shows the way Figure 4 The cross-section of the fuel cell stack is shown by line A. Multiple bipolar plates 10 are visible in the stack, each with a cathode side 12 on its lower side and an anode side 11 on its upper side. A membrane 20 is visible at the top of the stack, connecting to the anode side of each bipolar plate in the fuel cell stack. Anode gaskets 22 prevent air flow on the anode side of each plate, while air channels 17 on the cathode side of each plate are open to allow airflow. Elsewhere, it is noted that the air channels in adjacent bipolar plates of the fuel cell stack are not aligned along their entire length, but the cross-section shown is taken from the position where the channels are aligned to facilitate... Figure 9 View in the middle.

[0062] Figure 11 and Figure 12 A cross-section of the fuel cell stack is shown, which is perpendicular to... Figure 9 The cross section in the middle, along Figure 4 Line B is shown as a cutoff. Multiple bipolar plates 10 can be seen in the stack, each with its lower side being the cathode side 12 and its upper side the anode side 11. An MEA membrane 20 can be seen at the top of the stack, and the membrane 20 is also attached to the anode side of each bipolar plate in the fuel cell stack. An additional portion 23a of the cathode gasket (along its cutoff cross-section) prevents H2 from flowing on the cathode side of each plate, while H2 channels 16 allow hydrogen to flow on the anode side of each bipolar plate 10 in the stack. Figure 12 An anode gasket 22 in gasket channel 18 is also shown to prevent air from flowing along the anode side 11 of the bipolar plate.

[0063] Figure 11 and 12 The H2 channel 16 does not extend through the entire thickness of each bipolar plate 10. This is to prevent the H2 channel 16 from blocking the vertical air channel 17 (as shown in the image). Figure 9 and Figure 10(As shown). Air channels 17 are stamped into the bipolar plates such that each channel has a depth d1, and then a vertical H2 channel is stamped into the bipolar plates with a depth d2. The depth d2 of the H2 channel is less than the depth d1 of the air channel. At the intersection of the air channel and the H2 channel (on opposite sides of the bipolar plates), the air channel has a notch therein and narrows to depths d1-d2. This arrangement allows air and hydrogen to flow simultaneously in a substantially perpendicular direction through their respective channels on opposite sides of each bipolar plate, intersecting each other.

[0064] Figure 13 The bipolar plate shown is another alternative embodiment of the present invention. Similar to the above regarding... Figure 3-8 The bipolar plate, stamped Figure 13 The bipolar plate 30 is then rotated 180 degrees. This rotation prevents the air channels 38 from aligning, thus allowing the cathode and anode gaskets (not shown) and the proton exchange membrane (not shown) to be fixed between adjacent plates. Due to the different shapes of the stamping air channels, Figure 13 bipolar plates and Figure 3-8 The bipolar plates are different. Besides, Figure 13 The characteristics of bipolar plates and Figure 3-8 The bipolar plates are the same or correspond to each other.

[0065] Figure 14 Two bipolar plates 30 of the present invention are shown, one on top of the other. The top bipolar plate is partially transparent (for illustrative purposes only) so that the hydrogen passage of the lower plate (unlabeled, but referenced) is visible in the figure. Figure 13 Marker 36) and air passage 38b. Alternating plate orientation: Adjacent bipolar plates in the fuel cell stack rotate 180 degrees around a line perpendicular to the plate surface at the plate center. The channels are intentionally designed so that the air passages 38 of adjacent bipolar plates are not perfectly aligned: in Figure 14 As can be seen, the air channels 38a of the top plate are vertically aligned at their edges (i.e., the inlet and outlet), but then cross in opposite directions, their paths repeatedly branching and then converging, so that they are not completely aligned with the air channels 38b of the lower plate. The plates are designed such that the air channels of adjacent plates (i.e., one plate rotates relative to the next) are intentionally partially misaligned, so that the channels of adjacent plates do not fit together or "nest," and so that the MEA membrane (not shown) can be held between adjacent plates, held at the point where the lower surface of one plate intersects the upper surface of the other plate, without falling into or being pushed into the air channels 38, as this would reduce airflow and / or damage the seal.

[0066] The bipolar plates shown in Figures 15a and 15b are another alternative embodiment of the present invention. As described above (e.g., regarding...) Figure 5 and Figure 13 (as described), stamping Figure 3-8and Figure 13 The bipolar plates of the type described above are then rotated 180 degrees to prevent air channel alignment. In the embodiments shown in Figures 15a and 15b, the bipolar plates do not need to be rotated when stacking. Bipolar plates 50 (shown in Figure 15a) and 60 (shown in Figure 15b) are formed using different stamping tools. Therefore, when forming a fuel cell stack by alternating bipolar plates 50 and 60, it is not necessary to rotate any of the plates. Except for the pattern of air channels 57, 67, the channels of these bipolar plates follow the same pattern as... Figure 3-8 The same principle applies. The upper surface of each bipolar plate is the anode side 51, 61, while the lower side is the cathode side (not shown). Each bipolar plate 50, 60 has holes 54, 64 on either side, which connect a hydrogen manifold (not shown) to hydrogen flow channels 56, 66 on the anode side of the plate. Furthermore, in each of Figures 15a and 15b, there are gasket channels 58, 68 in which anode gaskets 52, 62 are located. Adjacent plates do not nest with each other, allowing the MEA to be securely held between adjacent plates.

[0067] Figure 16 The bipolar plate in the figure is another alternative embodiment of the present invention. Figure 16 The bipolar plate 80 in the middle has a closed cathode, which means it can be connected to an oxygen manifold. Figure 3-8 Both the bipolar plates of the present invention shown in Figures 1 and 13 have open cathodes, meaning the air passage is not sealed. Figure 16 The diagram illustrates an embodiment with a closed cathode, meaning that air passage 87 is sealed, and air enters the air passage through a hole 94 connected to an air manifold (not shown). The closed cathode arrangement also allows pure oxygen or air with additional oxygen to pass through air passage 87. In addition to the presence of air hole 94, the bipolar plate 80 with the closed cathode arrangement also has gasket channels 88 of different shapes to complement anode gaskets 82 of different shapes, as well as cathode gaskets (not shown) required for the closed cathode arrangement. Both the anode gasket 82 and the cathode gasket have additional portions for sealing the air hole 94.

[0068] Figures 17a and 17b show an alternative arrangement of the bipolar plates of the present invention with enclosed cathodes. Similar to bipolar plates 50 and 60 (shown in Figures 15a and 15b), bipolar plates 100 and 110 (shown in Figures 17a and 17b) do not require rotation during stacking. Instead, two separate molds are used to form the two bipolar plates 100 and 110. These bipolar plates are alternated when forming the fuel cell stack, which prevents the air channels 107, 117 on adjacent plates from aligning. Except for the shape of the air channels 107, 117, the bipolar plates 100 and 110 are... Figure 16 The bipolar plates shown are identical and have the same characteristics.

[0069] refer to Figure 18 and Figure 19 This illustrates a fuel cell stack incorporating the bipolar plates of the present invention. The fuel cell stack is characterized by bipolar plates having open cathodes (e.g.,...). Figure 3-8 (As shown in Figures 13 and 15). The fuel cell stack includes a bipolar plate stack 120, with a current collector plate 123 and an end plate 121 at each end of the bipolar plate stack. The fuel cell stack is also characterized by multiple different gaskets, specifically an anode gasket 128 and a cathode gasket (not shown) in the bipolar plate stack, a current collector gasket 127, and an end plate gasket 129 at each end. Bolts 124 hold the two end plates 121 together, compressing the stack and ensuring a seal between the various gaskets 127, 128, and 129 in the stack and the bipolar plates / end plates, preventing gas leakage between the hydrogen passage and the air passage. A hydrogen inlet 125 is shown through which hydrogen is pumped in a controlled manner into the hydrogen manifold and through orifices (not shown) in each bipolar plate and hydrogen flow passages (not shown). Additionally, an insulating layer 126 exists between the current collector plate and the end plate on each side of the stack.

[0070] Figure 20 and Figure 21 Showing the passage Figure 18 and Figure 19 A cross-section at the center of the fuel cell stack shows the air passage 130. This cross-section also allows visualization of the hydrogen manifold 131 and the holes 132 in the bipolar plates 120 through which hydrogen enters and exits the hydrogen passages on the anode side of the bipolar plates in the fuel cell stack. A cathode gasket 136 is visible to prevent hydrogen leakage from the fuel cell stack, and an additional portion 136a of the cathode gasket is also visible to prevent hydrogen from flowing along the cathode side of the bipolar plates in the stack. An anode gasket 137 additionally surrounds the outside of the hydrogen holes 132 to prevent hydrogen leakage from the fuel cell stack while allowing hydrogen to flow along the anode side of each bipolar plate through the hydrogen passages.

[0071] Figure 22 and Figure 23 It shows the line and Figure 20 and Figure 21 Another cross-section of the fuel cell stack runs in the same direction, but this cross-section passes through the peripheral gasket and is not at the center of the fuel cell stack. Anode gasket 135 prevents air from entering the anode side of the bipolar plate 120. MEA membrane and current collector gaskets 127 and 138 are present between the bipolar plate stack and the current collector plate 123, located on each side of the stack, to prevent hydrogen leakage from the bipolar plate stack. Additionally, there is an endplate gasket 129 between the current collector 123 and the endplate 120 of the fuel cell stack.

[0072] Figure 24 and Figure 25 It shows the direction perpendicular to Figure 20-23The cross-sections are oriented through the center of the same fuel cell stack. A hydrogen passage 140 is shown through which hydrogen travels along the anode side of each bipolar plate in the fuel cell stack. Additionally, an anode gasket 128 is visible, preventing air from entering the anode side 142 of the bipolar plate (upper side in these figures). A cathode gasket 143 is also visible, preventing hydrogen from entering the cathode side of the bipolar plate (lower side in these figures). Furthermore, an MEA membrane is present between each bipolar plate, preventing hydrogen from flowing from the anode side of one bipolar plate to the cathode side of the adjacent bipolar plate.

[0073] Figure 26 and Figure 27 It shows the line and Figure 24 and Figure 25 The same direction passes through another cross-section of the fuel cell stack, but this cross-section passes through an additional portion 136a of the cathode gasket adjacent to the hydrogen port. The additional portion 136a of the cathode gasket prevents hydrogen from entering the cathode side of the bipolar plate. Additionally, an anode gasket 135 can be seen, which prevents air from entering the anode side of the bipolar plate. These gaskets, combined with the proton exchange membrane between each bipolar plate, are crucial for ensuring the separation of air and hydrogen within the fuel cell stack.

[0074] Figure 28-40 An alternative embodiment of the invention is shown. First, refer to… Figure 28 and 29 The bipolar plate 200 is formed as a single stamped plate with two sides, a first side being the anode side 211 and the other side being the cathode side 212, in the same manner as in the embodiment described above. The bipolar plate has a hole 214 at each end to form a hydrogen manifold when multiple plates are hermetically stacked together. Hydrogen can flow from the inlet manifold (not shown) through the hydrogen inlet channel 216, via the main hydrogen channel 216b (e.g., a notch formed in an air channel) and the anode valley 221 (formed due to the air channel on the cathode side of the plate), through the hydrogen outlet channel 216c to the outlet manifold (not shown). In this embodiment, the hydrogen inlet and outlet channels are located on one side of the bipolar plate, and these channels can be uniformly distributed across the width of the hole 214. Because the cathode gasket (not shown here, but illustrated in the figure below) seals the hydrogen manifold to the cathode side of the bipolar plate, hydrogen can only flow on the anode side of the bipolar plate.

[0075] The bipolar plate in this embodiment also has an air passage 217 through which air (and therefore oxygen) flows substantially perpendicular to the hydrogen flow on the cathode side 212 of the plate. Airflow on the anode side of the bipolar plate is prevented by the interaction between the anode gasket feature 220 and the anode gasket (not shown here, but illustrated in the figure below). The anode gasket feature is a stamped portion of the bipolar plate with a raised profile on the anode side. The anode gasket feature is not connected to the anode valley 221. Therefore, when the anode gasket is compressed between the anode gasket feature 220 and the MEA (not shown), the anode side is sealed, and airflow on the anode side of the bipolar plate is prevented.

[0076] When stacked, the alternating boards are rotated 180 degrees to prevent air channels between adjacent boards from stacking, thus allowing the MEA (not shown) to remain between adjacent boards.

[0077] Figure 30 and 31 The anode gasket and cathode gasket, respectively located on the anode side and cathode side of the bipolar plate of the present invention, are shown. These figures should be consistent with... Figure 32a -c should be considered in conjunction with Figure 32a -c sequentially shows the anode gasket, cathode gasket, and end plate gasket. As described above, the anode gasket 230 seals between the anode gasket feature (not shown here, but shown in the above figure) and the MEA (not shown) on the anode side 211 of the plate. The anode gasket is a ring with a continuous thickness.

[0078] A cathode gasket 235 seals between the cathode side 212 of the plate and the MEA (not shown) to prevent hydrogen from leaking out of the hole 214 on the cathode side of the plate. The cathode gasket is shaped to complement the hydrogen inlet / outlet channels 216a, 216c. In a preferred embodiment, as shown here, there is rotational symmetry between the hydrogen inlet channel 216a and the hydrogen outlet channel 216c. Thus, the same cathode gasket 235 can be used for the hole 214 at each end of the plate.

[0079] End plate gaskets 237 may be present at one or both ends of the fuel cell stack (not shown) to seal the hydrogen manifold (not shown). For example, if the hydrogen manifold inlet and outlet are located on the same side of the fuel cell stack, two end plate gaskets 237 will be required between the current collector plate and the end plate on the same side of the fuel cell stack to seal the orifice (not shown). In this embodiment, no end plate gasket is required between the current collector plate and the end plate on the other side of the fuel cell stack. In an alternative embodiment, the hydrogen manifold inlet and outlet may be located on opposite sides of the fuel cell stack, in which case it is conceivable that one end plate gasket would be required between the current collector plate and the end plate on either side of the fuel cell stack to seal the orifice.

[0080] Figure 33 (and corresponding colors) Figure 37The diagram shows a cross-section of the anode gasket features passing through two adjacent bipolar plates 200 (the cross-section is through...). Figure 29 (Line A is cut off in the figure). In this figure, the upper side of each plate is the anode side 211, and the lower side of each plate is the cathode side 212. An air channel 217 can be seen on the cathode side of each bipolar plate, which is defined by the anode side of the bipolar plate and MEA 238. An anode gasket feature 220 is present and forms a seal between the anode side 211 and the anode gasket 230 of each bipolar plate, thereby preventing air from entering the anode side of the bipolar plate.

[0081] Figure 34 (and corresponding colors) Figure 38 ) shows with Figure 33 A view of the fuel cell stack edges in the same cross-sectional direction, but without capturing the anode gasket feature. It can be seen that the anode gasket feature 220 is sealed and not connected to the anode valley 221, allowing the anode gasket feature to contact the anode gasket 230 and seal the anode side 211 (the upper side of each plate in this figure) from air. Air passages 217 are visible on the cathode side 212 (the lower side of each plate in this figure) and allow oxygen-containing air to flow on the cathode side of each plate.

[0082] Figure 35 (and corresponding colors) Figure 39 The diagram shows a cross-section of the hydrogen inlet channel through two adjacent bipolar plates 200 (the cross-section is shown through...). Figure 29 (B-line cutout in the figure). Hydrogen inlet channel 216a is visible on each bipolar plate. The hydrogen inlet channel is formed between the anode side (upper side in the figure) and MEA 238 of each bipolar plate. Hydrogen ingress is prevented from the cathode side (lower side in the figure) of each bipolar plate by a cathode gasket 235, which is shaped to correspond to the hydrogen inlet channel and seals between the cathode side of the plate and MEA 238. Anode gasket feature 220 of each bipolar plate and anode gasket 230 between the two bipolar plates are also visible.

[0083] Figure 36 (and corresponding colors) Figure 40 ) shows along Figure 29 Line C passes through the cross-section at the center of the two bipolar plates 200. Hydrogen channels 216b can be seen on the anode side of each bipolar plate (the upper side in this figure). MEA 238 can be seen located between the two bipolar plates. The cross-section cuts off the edges of the bipolar plates, so the anode gasket feature 220 can be seen on each plate and on the anode gasket 230.

[0084] In operation, hydrogen is pumped into a hydrogen manifold, then passes through a hole on one side of the fuel cell stack. The hydrogen then flows along the anode side of each bipolar plate in the stack via H2 channels. On the other side, there is an outlet manifold through which unused hydrogen can be recirculated. Cathode gaskets prevent hydrogen from entering the channels on the cathode side of each plate. Upon passing through the anode, H2 is converted to hydrogen by a catalyst (part of or contained within the MEA). + Ions (protons). The protons then pass through a proton exchange membrane, where they combine with oxygen and electrons in the presence of a cathode catalyst to form water. This process involves converting hydrogen into H₂. + Electrons generated by ions travel through an external circuit (not shown) to a current collector, where electricity is collected. Current collectors are present at each end of the fuel cell stack.

[0085] Airflow can occur passively. Simultaneously with the controlled hydrogen flow, a fan pumps air through approximately vertical air channels on the cathode side of each bipolar plate. Anode gaskets prevent air from entering the anode side of each plate. The airflow supplies oxygen to the cathode, which is converted to O2 by combining with electrons on the cathode catalyst (not shown). 2- Ions. From O 2- Ions and H + Water formed by ion bonding flows out of the fuel cell as water vapor in the air channel.

[0086] In the fuel cell stack of the present invention, a membrane electrode assembly (MEA) exists between each bipolar plate. MEAs are conventional in the art and typically include, in sequence, a first gas diffusion layer (GDL), an anode catalyst layer, a proton exchange membrane, a cathode catalyst layer, and a second gas diffusion layer (GDL). Each of these layers is conventional in the art. In the fuel cell stack of the present invention, the first GDL (adjacent to the anode catalyst layer in the MEA) will be adjacent to the anode side of the first bipolar plate 10, and the second GDL (adjacent to the cathode catalyst layer of the same MEA) will be adjacent to the cathode side of the second bipolar plate. Other arrangements of the MEA are also known and can be used with the bipolar plates of the present invention; for example, the GDL and catalyst layer can be combined into a single layer.

[0087] In preparing the plates and plate stack, multiple plates can be prepared using a single stamping tool, with each adjacent plate rotated 180° relative to the previous one. The MEA is located between the adjacent plates, and the adjacent plates are sealed to each other with gaskets. Alternatively, two different stamping tools can be used, and the bipolar plates prepared using each stamping tool are then alternately processed in the stack. Using two different stamping tools avoids rotating adjacent plates. Another advantage of using two separate stamping tools is that the cathode flow field can be uniform, eliminating the unused space in the center of the bipolar plates, which is unavoidable when using a single stamping tool. Channels on the plate surfaces form sealed channels for hydrogen and oxygen. The compressed MEA between the gaskets and the plates maintains the separation of the hydrogen and oxygen channels and seals the hydrogen channels, preventing leakage between the respective channels. The plate stack is securely held together by clamps or an external fuel stack body. Current collectors are added to the corresponding anode and cathode ends of the stack. The sealing of the hydrogen channels forms a single hydrogen inlet at one end of the stack and a single outlet at the other end. The hydrogen manifold is connected to and sealed to the inlet and outlet to allow hydrogen to flow through the hydrogen passage in a controlled manner, which is conventional in fuel cells and is not part of this invention.

[0088] In the illustrated embodiment, oxygen (containing air) freely flows into and through an oxygen channel (air channel) on the cathode side of the plate, while hydrogen entering the anode side is controlled by a manifold and gas inlet control system, and the fuel cell operates to generate electricity. As will be understood, reference to a hydrogen channel refers to a channel for the flow of a gas including or composed of hydrogen, and reference to an oxygen flow channel refers to a channel for the flow of a gas including or composed of oxygen (particularly in air).

[0089] In another embodiment, an oxygen manifold (air manifold) is also provided for controlling the input of oxygen (or air) and the output of water. In this alternative embodiment, both the oxygen manifold and the oxygen passage are sealed by a manifold, and the gas flow is controlled by valves at the respective gas inlets and outlets.

[0090] Therefore, the present invention provides a bipolar plate and a hydrogen fuel cell unit including the plate, and a method for preparing the same.

Claims

1. A hydrogen fuel cell unit, comprising, in sequence: (i) A first bipolar plate having a front side and a back side, wherein the back side is the anode in the cell. (ii) First membrane electrode assembly, (iii) A second bipolar plate having a front side and a back side, wherein the front side is the cathode of the unit and the back side is the anode of the unit. in, The first membrane electrode assembly is located between the first bipolar plate and the second bipolar plate. A flow path for hydrogen flow is provided between the back side of the first bipolar plate and the first membrane electrode assembly, and a flow path for oxygen flow is provided between the front side of the second bipolar plate and the first membrane electrode assembly. (iv) Second membrane electrode assembly, and (v) A third bipolar plate having a front and a back side, the front side being the cathode in the unit. The second membrane electrode assembly is located between the second and third bipolar plates. A flow path for hydrogen flow is provided on the back side of the second bipolar plate and between the second membrane electrode assembly, and a flow path for oxygen flow is provided on the front side of the third bipolar plate and between the second membrane electrode assembly. The bipolar plates include channels for oxygen flow, and the oxygen flow channels of adjacent plates repeatedly branch and converge on the adjacent plates. The bipolar plate further includes channels for hydrogen flow, wherein the hydrogen flow channels and oxygen flow channels are substantially transverse to each other, and the bipolar plate is stamped from a single metal or alloy sheet. The oxygen flow channel is formed by a recess in the bipolar plate, and the transverse hydrogen flow channel includes a notch in the recess that forms the oxygen flow channel, or vice versa, that is, the hydrogen flow channel is formed by a recess in the bipolar plate, and the transverse oxygen flow channel includes a notch in the recess that forms the hydrogen flow channel.

2. The hydrogen fuel cell unit according to claim 1, wherein the oxygen flow channels of adjacent plates branch and converge on the plates in a cross-shaped pattern.

3. The hydrogen fuel cell unit according to claim 1 or claim 2, wherein the oxygen flow channels branch and converge in a regular pattern.

4. The hydrogen fuel cell unit according to claim 1 or claim 2, wherein each oxygen flow channel includes an inlet and an outlet and a conduit located between its inlet and its outlet, and wherein the oxygen conduits of adjacent plates in the fuel cell are not vertically aligned along their entire length, such that adjacent plates do not nest together when fixed to a stack as part of the fuel cell unit.

5. The hydrogen fuel cell unit of claim 4, wherein the membrane electrode assembly is sandwiched between the bipolar plates.

6. The hydrogen fuel cell unit according to claim 1 or claim 2, wherein the plate includes channels for hydrogen flow, each channel having an inlet and an outlet, wherein the respective inlets and outlets of the hydrogen flow channels of adjacent plates in the fuel cell are vertically aligned.

7. The hydrogen fuel cell unit according to claim 1 or claim 2, wherein the hydrogen flow channel further includes a conduit located between its inlet and outlet, wherein the conduits of the channels of adjacent plates in the fuel cell are not vertically aligned along their entire length.

8. The hydrogen fuel cell unit according to claim 1 or claim 2, wherein, Each oxygen flow channel has an inlet and an outlet, wherein the inlets and outlets of the oxygen flow channels of adjacent plates in the fuel cell are vertically aligned.

9. The hydrogen fuel cell unit according to claim 1 or claim 2, wherein, When the plates are stacked vertically on top of each other, the horizontal cross-section of any plate passing through the center of the plate passes through both the hydrogen flow channel and the oxygen flow channel.

10. The hydrogen fuel cell unit according to claim 1 or claim 2, wherein the first bipolar plate and / or the second bipolar plate and / or the third bipolar plate do not have rotational symmetry about a line passing through the center of the plate in the vertical direction of the plate stack.

11. The hydrogen fuel cell unit of claim 10, wherein the first bipolar plate and / or the second bipolar plate and / or the third bipolar plate comprises two or more manifolds, and the manifolds on each plate are rotationally symmetric.

12. The hydrogen fuel cell unit according to claim 1 or claim 2, wherein the first bipolar plate, the second bipolar plate, and the third bipolar plate are designed identically.

13. The hydrogen fuel cell unit of claim 12, wherein adjacent bipolar plates are rotated 180 degrees relative to each other.

14. The hydrogen fuel cell unit according to claim 1 or claim 2, wherein the bipolar plate is a steel plate.

15. A method for preparing a hydrogen fuel cell, comprising: (i) A first bipolar plate and a second bipolar plate are provided, the first bipolar plate having a front side and a back side, the front side being a cathode, and the second bipolar plate having a front side and a back side, the front side being a cathode and the back side being an anode. (ii) Position the first membrane electrode assembly between the first bipolar plate and the second bipolar plate. When the first membrane electrode assembly is located between the first bipolar plate and the second bipolar plate, a flow path for hydrogen flow is provided between the back side of the first bipolar plate and the first membrane electrode assembly, and a flow path for oxygen flow is provided between the front side of the second bipolar plate and the first membrane electrode assembly. (iii) A third bipolar plate is provided, the third bipolar plate having a front side and a back side, the front side being the cathode, and (iv) Position the second membrane electrode assembly between the second bipolar plate and the third bipolar plate. Specifically, when the second membrane electrode assembly is located between the second and third bipolar plates, a flow path for hydrogen flow is provided between the back side of the second bipolar plate and the second membrane electrode assembly, and a flow path for oxygen flow is provided between the front side of the third bipolar plate and the second membrane electrode assembly. The bipolar plates include channels for oxygen flow, and the oxygen flow channels of adjacent plates repeatedly branch and converge on the adjacent plates. The bipolar plate further includes channels for hydrogen flow, wherein the hydrogen flow channels and oxygen flow channels are substantially transverse to each other, and the bipolar plate is stamped from a single metal or alloy sheet. The oxygen flow channel is formed by a recess in the bipolar plate, and the transverse hydrogen flow channel includes a notch in the recess that forms the oxygen flow channel, or vice versa, that is, the hydrogen flow channel is formed by a recess in the bipolar plate, and the transverse oxygen flow channel includes a notch in the recess that forms the hydrogen flow channel.

16. The method of claim 15, wherein the bipolar plates all have the same design and adjacent plates are rotated 180 degrees relative to each other.

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