Sealing device and fuel cell stack

Abstract

The invention relates to a sealing device (26) for a fuel cell stack (10) of a fuel cell, comprising a first layer (36), a second layer (38) offset in the vertical direction (12) to the first layer, an adhesive layer (48) arranged between the first and second layers (36, 38) and connecting the first and second layers (36, 38) together and comprising an adhesive material (46), wherein the first and / or second layer (36, 38) can be attached to a membrane electrode assembly (24) and the first layer (36) has a sealing area (52) which can be acted upon by a contact force (50) via at least one bipolar plate (18) for sealing against the at least one bipolar plate (18), wherein a partial volume (62) of the adhesive layer (48) which covers the sealing area (52) at least partially comprises a filling medium (64) that differs from the material properties of the adhesive material (46).Furthermore, the invention relates to a fuel cell stack (10).

Description

[0001] The invention relates to a sealing device according to the preamble of claim 1. Furthermore, the invention relates to a fuel cell stack. State of the art

[0002] In DE 10 2022 213 475 A1 a membrane electrode structure of a fuel cell is described, comprising a membrane coated with electrodes, which is attached to at least one frame film of a frame. Disclosure of the invention

[0003] According to the present invention, a sealing device with the features of claim 1 is proposed. This allows the tightness of the fuel cell stack to be increased. The fuel cell stack can be made more reliable and durable. The sealing device can achieve a more consistent sealing effect.

[0004] The lateral direction, or the reference specified as lateral, refers to a direction perpendicular to the vertical direction. This direction can be a longitudinal or transverse direction. Both the longitudinal and transverse directions are lateral directions. The longitudinal direction is preferably perpendicular to the transverse direction.

[0005] The fuel cell can be arranged in a stationary or mobile device, in particular a vehicle. The vehicle can be an electric vehicle. The fuel cell can provide drive energy for propelling the vehicle.

[0006] The fuel cell can be, for example, a PEM fuel cell (Proton Exchange Membrane Fuel Cell), a PEM electrolyzer (Proton Exchange Membrane Electrolyzer) or a redox flow cell.

[0007] The fuel cell stack can be permeable to a reaction medium. The reaction medium can be gaseous or liquid. The reaction medium can be a fuel, in particular hydrogen. The reaction medium can be an oxidizing agent, in particular oxygen, preferably from air. The fuel cell stack can be permeable to a first reaction medium, in particular the fuel, and a second reaction medium, in particular the oxidizing agent.

[0008] The bipolar plate can have a channel structure through which the reaction medium flows. The bipolar plate can be made of metal, graphite, or a composite material. The bipolar plate can have cooling fluid openings for the passage of cooling fluid. The bipolar plate can have an active field encompassing at least a portion of the channel structure. The active field can be the area of ​​the bipolar plate in which the reaction medium is guided vertically from the channel structure to an electrode of the membrane electrode assembly.

[0009] The fuel cell stack can have a stacked layered structure in the vertical direction. This layered structure can be repeated multiple times, consisting of at least one bipolar plate with a channel structure and another bipolar plate offset vertically from it, also with a channel structure, and at least one membrane electrode assembly between the first and second bipolar plates. The second bipolar plate can exhibit the features previously described for the first bipolar plate, such as the additional channel structure corresponding to the first.

[0010] The membrane electrode assembly (MEA) can comprise at least one anode, in particular with a catalyst layer, at least one cathode, in particular with a catalyst layer, and at least one electrolyte membrane, in particular a proton exchange membrane (PEM), which preferably separates the anode and cathode. The electrolyte membrane can be in direct contact with the anode and / or cathode, in particular with the catalyst layers. The membrane electrode assembly can comprise at least one gas diffusion layer (GDL), in particular on at least one side of the electrolyte membrane. The membrane electrode assembly can also comprise a gas diffusion layer on both sides of the electrolyte membrane.

[0011] The first and / or second layer can be made of the same or different layer materials. The layer material can be a synthetic polymer, preferably PEN (polyethylene naphthalate).

[0012] The first and / or second layer can be attached to the membrane electrode assembly by the adhesive material of the adhesive layer.

[0013] The adhesive layer can be positioned vertically between the first and second layers. The adhesive layer can bond the first and second layers together in a material-bonded manner.

[0014] A sealing element can be positioned between the first layer and the bipolar plate. This sealing element can be located within the sealing area. The contact surface between the sealing element and the first layer can define the sealing area. The bipolar plate can exert the contact force on the sealing area via the sealing element. Another sealing element can be positioned between the second layer and the second bipolar plate. This second sealing element can be located within the second sealing area. The contact surface between this second sealing element and the second layer can define the second sealing area. The second bipolar plate can exert the contact force on the second sealing area via this second sealing element. The contact forces can be generated by clamping the first and second bipolar plates together.

[0015] The partial volume can span the entire sealing area. The partial volume can extend laterally beyond the sealing area.

[0016] The filler medium can be the same as the adhesive material, but may, for example, through material treatment such as temperature application, irradiation (especially by infrared radiation, UV radiation, laser light, or other electromagnetic radiation), exhibit at least one material property different from the adhesive material, such as material structure or creep behavior. The filler medium can be a different material than the adhesive material. The filler medium can consist of the adhesive material and at least one additive material.

[0017] In a preferred embodiment of the invention, it is advantageous if the partial volume is at least partially designed as a free space. The free space can extend over the entire height in the vertical direction between the first and second layers. The free space can be spanned by the first and / or second layer in a cantilevered manner.

[0018] In an advantageous embodiment of the invention, the partial volume is partially filled with the adhesive material and partially with the filling medium. Alternatively, the partial volume can be completely filled with the filling medium.

[0019] In a particular embodiment of the invention, it is advantageous if the partial volume is completely covered with the adhesive material and the filler medium is offset vertically to the adhesive material. This allows for a vertically layered structure within the partial volume. The adhesive material can also be introduced alongside the filler medium in at least one lateral direction.

[0020] In a preferred embodiment of the invention, the filling medium is gaseous. The filling medium can be air.

[0021] In an advantageous embodiment of the invention, the filler medium has a higher modulus of elasticity than the adhesive material. The filler medium can consist of the adhesive material and an additive. During the curing of the filler medium, the additive can impart a material property that differs from that of the adhesive material. The additive can be a hardener component.

[0022] In an advantageous embodiment of the invention, the second layer has a further sealing area, which can be subjected to a contact force via at least one further bipolar plate, for sealing against the at least one further bipolar plate, and the partial volume also covers at least part of the further sealing area. The partial volume can cover the entire further sealing area. The partial volume can extend laterally beyond the further sealing area. The sealing area and the further sealing area can have the same lateral dimensions opposite each other in the vertical direction.

[0023] According to the present invention, a fuel cell stack with the features of claim 8 is further proposed. The sealing device can be arranged vertically between the bipolar plate and the further bipolar plate.

[0024] The sealing device prevents the reaction medium from escaping the active field into the environment. The sealing device protects the membrane electrode assembly from mechanical influences.

[0025] A preferred embodiment of the invention is advantageous in which the sealing device is arranged laterally between, on the one hand, the channel structure and / or further channel structures and, on the other hand, the surroundings of the fuel cell stack. The sealing device can be designed as a subgasket of the membrane electrode assembly. The sealing device can be arranged laterally between the membrane electrode assembly and the surroundings.

[0026] In a preferred embodiment of the invention, it is advantageous if the sealing device is an edge structure that at least partially surrounds the membrane-electrode assembly laterally. The sealing device can completely surround the membrane-electrode assembly at its edge.

[0027] Further advantages and advantageous embodiments of the invention will become apparent from the description of the figures and the illustrations. Character description

[0028] The invention is described in detail below with reference to the illustrations. These show, in detail: Fig. 1: A section of a spatial cross-section of a fuel cell stack with a sealing device, each in a specific embodiment of the invention. Fig. 2 and Fig. 3: A section of a cross-section of a fuel cell stack with a sealing device, each in a further specific embodiment of the invention.

[0029] Fig. Figure 1 shows a section of a spatial cross-section of a fuel cell stack with a sealing device, each in a specific embodiment of the invention. The fuel cell stack 10 of a fuel cell comprises a vertically stacked layer structure 14 with a bipolar plate 18 having a channel structure 16 and a further bipolar plate 22 offset vertically 12 and having a further channel structure 20, and a membrane electrode assembly 24 between the bipolar plate 18 and the further bipolar plate 22. A sealing device 26 is arranged at the edge of the membrane electrode assembly 24, sealing against the bipolar plate 18 and the further bipolar plate 22.

[0030] This multilayered structure, repeating vertically 12 and consisting of a bipolar plate 18, another bipolar plate 22, and a membrane electrode assembly 24 with the sealing device 26, forms the layered structure 14. The bipolar plate 18 comprises an active field 28 formed by the channel structure 16, in which a reaction medium, for example hydrogen, is guided to the membrane electrode assembly 24 for electrochemical reaction. The other bipolar plate 22 also comprises a further active field 30 formed by the further channel structure 20, in which another reaction medium, in particular oxygen, is guided to the membrane electrode assembly 24 from a side opposite the active field 28 in the vertical direction 12 for electrochemical reaction with the reaction medium.

[0031] The sealing device 26 is arranged laterally between, on the one hand, the channel structure 16 and / or the further channel structure 20 and, on the other hand, an environment 32 of the fuel cell stack 10, and seals the active field 28 and the further active field 30 against the environment 32. The sealing device 26 is an edge structure 34 that laterally surrounds the membrane electrode assembly 24. The sealing device 26 comprises a first layer 36 and a second layer 38 offset from it in the vertical direction 12. The first and second layers 36, 38 are attached to the inner edge of the membrane electrode assembly 24.

[0032] The membrane electrode assembly 24 comprises at least one electrolyte membrane 40, in particular a proton exchange membrane, and, in the vertical direction 12, opposite each other with respect to the electrolyte membrane 40, an anode-side gas diffusion layer 42 and a further cathode-side gas diffusion layer 44.

[0033] The fuel cell stack 10 in Fig. 2 comprises the bipolar plate 18 and the further bipolar plate 22 opposite it in the vertical direction 12, and the membrane electrode assembly (not visible here) to which the sealing device 26 is attached as a surrounding edge structure 34. The sealing device 26 is arranged laterally at the edge, in particular completely around the membrane electrode assembly 24.

[0034] The sealing device 26 comprises the first layer 36, the second layer 38 offset in the vertical direction 12 to this layer, and an adhesive layer 48 arranged between the first and second layers 36, 38 and connecting the first and second layers 36, 38 to each other and comprising an adhesive material 46. The sealing device can be firmly connected to the membrane electrode assembly 24 by means of the adhesive material 46.

[0035] The first layer 36 comprises a sealing area 52 which can be subjected to a contact force 50 via the bipolar plate 18 for sealing against the bipolar plate 18. The second layer 38 comprises a further sealing area 56 which can be subjected to a contact force 54 via the further bipolar plate 22 for sealing against the further bipolar plate 22.

[0036] A sealing element 58 is arranged between the first layer 36 and the bipolar plate 18, via which the bipolar plate 18 exerts the contact force 50 on the sealing area 52. Furthermore, another sealing element 60 is arranged between the second layer 38 and the second bipolar plate 22, via which the second bipolar plate 22 exerts the contact force 54 on the second sealing area 56. The contact forces 50 and 54 can be generated by clamping the bipolar plate 18 and the second bipolar plate 22 relative to each other.

[0037] A partial volume 62 of the adhesive layer 48, completely spanning the sealing area 52 and the further sealing area 56, contains at least a portion of a filler medium 64 that differs from the material properties of the adhesive material 46. The partial volume 62 is defined vertically 12 by the distance 66 between the first and second layers 36, 38. In a transverse direction 68, the partial volume 62 extends on both sides beyond the sealing area 52 and the further sealing area 56. The partial volume 62 is, for example, designed as a free area 72, free of the adhesive material 46, and completely comprises the filler medium 64, which can be a gas, particularly air. This prevents undesired creep of the adhesive material 46 of the adhesive layer 48 when contact forces 50, 54 are applied in the sealing area 52 and the further sealing area 56.Consequently, a gradual reduction in tightness in sealing area 52 and the further sealing area 56 can be prevented, and the durability of the fuel cell stack 10 can be increased. The surface pressures in sealing area 52 and the further sealing area 56 between the bipolar plate 18, the further bipolar plate 22, and the sealing device 26 can be reliably maintained to ensure a proper seal.

[0038] Instead of filling the entire partial volume 62 with the filler material, the partial volume 62 can also be partially filled with the adhesive material 46 and partially with the filler medium 64. The partial volume 62 can be completely covered with the adhesive material 46 and completely covered with the filler medium 64, and the adhesive material 46 can be offset in the vertical direction 12 relative to the filler medium 64.

[0039] In Fig. 3 is a fuel cell stack of 10 as in Fig.2. However, the partial volume 62 is completely filled with the filling medium 64. The filling medium 64 has a higher modulus of elasticity than the adhesive material 46. This reduces the flowability and creep of the filling medium 64, thereby maintaining more constant surface pressures in the sealing area 52 and the further sealing area 56.

[0040] The filler medium 64 can be the same as the adhesive material 46, but may exhibit different material properties due to material treatment, such as temperature treatment, irradiation, in particular by infrared radiation, UV radiation, laser light, or other electromagnetic radiation. Alternatively, the filler medium 64 can be a different material than the adhesive material 46. For example, the filler medium 64 can consist of the adhesive material 46 and at least one additive material. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2022 213 475 A1

[0002]

Claims

[1] Sealing device (26) for a fuel cell stack (10) of a fuel cell, comprising a first layer (36), a second layer (38) offset in the vertical direction (12) to this one, an adhesive layer (48) arranged between the first and second layers (36, 38) and connecting the first and second layers (36, 38) and comprising an adhesive material (46), wherein the first and / or second layer (36, 38) can be attached to a membrane electrode assembly (24) and the first layer (36) has a sealing area (52) which can be acted upon by a contact force (50) via at least one bipolar plate (18) for sealing against the at least one bipolar plate (18), characterized by , that a partial volume (62) of the adhesive layer (48) that spans at least partially over the sealing area (52) and has at least partially a filling medium (64) that differs from the material properties of the adhesive material (46). [2] Sealing device (26) according to claim 1, characterized by , that the partial volume (62) is at least partially designed as a free space (72). [3] Sealing device (26) according to claim 1 or 2, characterized by , that the partial volume (62) is partially filled with the adhesive material (46) and partially with the filling medium (64). [4] Sealing device (26) according to claim 3, characterized by , that the partial volume (62) is fully covered with the adhesive material (46) and the filling medium (64) is offset in the vertical direction (12) to the adhesive material (46). [5] Sealing device (26) according to one of the preceding claims, characterized by , that the filling medium (64) is gaseous. [6] Sealing device (26) according to one of claims 1 to 4, characterized by , that the filling medium (64) has a larger modulus of elasticity than the adhesive material (46). [7] Sealing device (26) according to one of the preceding claims, characterized by , that the second layer (38) has a further sealing area (56) which can be acted upon by a contact force (54) via at least one further bipolar plate (22) for sealing against the at least one further bipolar plate (22) and that the partial volume (62) also covers the further sealing area (56) at least partially over a surface. [8] Fuel cell stack (10) comprising a layer structure (14) stacked in the vertical direction (12) consisting of at least one bipolar plate (18) having a channel structure (16) and a further bipolar plate (22) offset thereto in the vertical direction (12) and having a further channel structure (20) and at least one membrane electrode assembly (24) and a sealing device (26) between the bipolar plate (18) and the further bipolar plate (22) according to one of the preceding claims. [9] Fuel cell stack (10) according to claim 8, characterized by , that the sealing device (26) is arranged laterally between on the one hand the channel structure (16) and / or the further channel structure (20) and on the other hand an environment (32) of the fuel cell stack (10). [10] Fuel cell stack (10) according to claim 8 or 9, characterized bythat the sealing device (26) is a marginal structure (34) that at least partially surrounds the membrane electrode assembly (24) laterally.

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