Holding device for cell layers of a fuel cell stack and apparatus and method for separating cell layers

Abstract

The invention relates to a holding device (10) for bipolar plates (101) and membrane electrode assemblies of a fuel cell stack (100), comprising two holding elements (12, 14) configured to receive, between the holding elements (12, 14), a bipolar plate (101) or a membrane electrode assembly at an end portion (106) of the bipolar plate (101) or the membrane electrode assembly, wherein one holding element (14) is configured to be at least partly positioned below and the other holding element (12) is configured to be at least partly positioned above the bipolar plate (101) or the membrane electrode assembly.

Description

[0001] R.413780

[0002] - 1 -

[0003] Description

[0004] Holding device for bipolar plates and membrane electrode assemblies of a fuel cell stack, as well as device and method for separating bipolar plates and membrane electrode assemblies.

[0005] Technical field

[0006] The invention relates to a holding device for bipolar plates and membrane electrode assemblies of a fuel cell stack, which enables a particularly reliable separation process for fully automated separation of bipolar plates and membrane electrode assemblies. Furthermore, the invention relates to a device and a method for separating bipolar plates and membrane electrode assemblies of a fuel cell stack, in particular by means of a holding device designed according to the invention.

[0007] State of the art

[0008] In the context of developing alternative drive concepts, for example for commercial vehicles or other vehicles, fuel cell drives are known that utilize fuel cell stacks as energy converters, transforming chemical energy into electrical energy to provide the necessary drive energy. Such fuel cell stacks consist of a multitude of fuel cells arranged one above the other. Each fuel cell typically comprises two bipolar plates and a membrane electrode assembly (MEA) positioned between them. The MEA is mechanically connected to each bipolar plate via a gasket and sealed against the bipolar plate. If parts of the fuel cell stack are damaged or need to be replaced, it is necessary to separate the components of the fuel cell stack.R.413780 is particularly relevant with regard to the raw materials present in the fuel cell stack.

[0009] - 2 -

[0010] Recycling the components is sensible or economically worthwhile if an automated separation process is enabled for the fuel cell stacks, which typically contain up to 400 bipolar plates.

[0011] Separation devices for separating bipolar plates of a fuel cell stack are already known in the art (EP 1 478043 A1, US 2020 / 0373590 A1), which typically have two separating devices or separating blades that are horizontally movable against the bipolar plates from opposite sides of the fuel cell stack. Because the two separating devices are moved against the fuel cell stack from both sides, equal forces are introduced into the gap between the two bipolar plates from opposite sides. This results in an almost symmetrical deformation or symmetrical separation of the upper bipolar plate from the opposite sides.

[0012] Disclosure of the invention

[0013] The holding device according to the invention for cell layers of a cell stack, in particular bipolar plates and membrane electrode units of a cell stack of an electrochemical cell, preferably of a fuel cell stack of a fuel cell with the features of claim 1, has the advantage that, particularly in connection with relatively flexible or deformable membrane electrode units and a two-stage separation process starting from one side of the bipolar plates or the membrane electrode units, it enables defined positioning of an already partially separated bipolar plate or membrane electrode unit and thus avoids unwanted movements of the bipolar plate or the membrane electrode unit, which, for example, lead to an uncontrolled separation process through collision with a lower separation tool or to other damage to the system.

[0014] The cell layers are preferably bipolar plates and / or membrane electrode assemblies. The cell stack is preferably a cell stack or a fuel cell stack. Within the scope of the present invention, an electrochemical cell particularly comprises a fuel cell and / or an R.413780

[0015] - 3 -

[0016] Electrolysis cell and / or a battery cell. It should be noted that the cell stack can also be that of a cooler or heat exchanger without departing from the scope of the present invention.

[0017] The invention is based on the idea of ​​designing and arranging the holding device in such a way that a partially separated bipolar plate or membrane electrode assembly is held at the already separated area by means of the milled recesses or openings provided in the design of the bipolar plate and the membrane electrode assembly, so that the actual separation of the held bipolar plate or the membrane electrode assembly can be carried out along its entire length using a separation tool, without the bipolar plate or the membrane electrode assembly yielding or slipping due to mechanical forces of the separation process, which could potentially negatively affect or prevent the separation process. In this process, a bipolar plate and a membrane electrode assembly are separated alternately from each other.

[0018] In light of the above explanations, a holding device according to the invention for cell layers of a cell stack, in particular bipolar plates and membrane electrode assemblies of a cell stack of an electrochemical cell, preferably of a fuel cell stack of a fuel cell, with the features of claim 1, therefore comprises two holding elements configured to receive a bipolar plate or a membrane electrode assembly at an end section of the bipolar plate or the membrane electrode assembly between the holding elements. Furthermore, one holding element is configured to be positioned at least partially below, and the other holding element at least above, the bipolar plate or the membrane electrode assembly in order to form a receptacle for the end section of the bipolar plate or the membrane electrode assembly.Finally, the retaining device is designed to prevent movement of the bipolar plate or the membrane electrode assembly out of the receptacle between the two retaining elements. R.413780.

[0019] - 4 -

[0020] Advantageous further developments of the holding device according to the invention for bipolar plates and membrane electrode units of a fuel cell stack are listed in the dependent claims.

[0021] A particularly preferred design provides that the two retaining elements are designed to prevent the bipolar plate or the membrane electrode assembly from moving out of the holder. This eliminates the need for additional components, thus simplifying the design.

[0022] In further development of the last proposal, one retaining element has a base section to form an upper stop for the bipolar plate or the membrane electrode unit and at least one leg extending or projecting from the base section towards the other retaining element to prevent the bipolar plate or the membrane electrode unit from moving out of the receptacle.

[0023] In a further preferred development of the last proposal, it is provided that at least one leg of one retaining element, with an end face facing away from the base section, can be lowered to a position below the plane of the other retaining element.

[0024] In order to bring the holding device into operative contact with the bipolar plate or the membrane electrode unit, or to enable the bipolar plate or the membrane electrode unit to be positioned between the two holding elements, it is furthermore preferably provided that at least one of the holding elements is coupled with an adjustment mechanism which is designed to realize a movement of the holding element at least in a direction perpendicular to the plane of the bipolar plate or the membrane electrode unit.

[0025] The single retaining element, which acts as the upper stop, can be manufactured particularly easily and cost-effectively if it is made from a bent sheet metal part. Of course, other solutions are also conceivable, for example, a plastic version (R.413780).

[0026] - 5 -

[0027] Holding device. Furthermore, one of the holding elements is preferably U-shaped to fulfill its function.

[0028] In another, also preferred embodiment, the lower of the two retaining elements serves not only to position the bipolar plate or the membrane electrode assembly together with the other retaining element, but also to form an initial gap between a bipolar plate and a membrane electrode assembly. For this purpose, the retaining element is simultaneously designed as a separating element for locally separating a bipolar plate from a membrane electrode assembly.

[0029] Further developing the previously proposed design, particularly in connection with a blade- or knife-shaped holding and separating element, it is envisaged that the holding element is movable in all three directions of a Cartesian coordinate system. This allows the holding element to be inserted locally at a specific point to create an initial gap—in this case, a notch between a bipolar plate and a membrane electrode assembly—and then moved in a direction perpendicular to the insertion movement within the plane of the bipolar plate or the membrane electrode assembly. This creates the initial gap or separation between the bipolar plate and the membrane electrode assembly across their entire width, but only over a portion of the length of the aforementioned elements.The holding element can then be moved towards the other holding element to widen the initial gap, in particular also to introduce a second separating tool into the then enlarged gap between the bipolar plate and the membrane electrode unit.

[0030] The invention further comprises a device for separating bipolar plates and membrane electrode assemblies of a fuel cell stack, with a holding device preferably designed in the manner described above according to the invention. The device further comprises a separating element, preferably in the form of a strip, which can be positioned below the holding device and projected away from the holding device.

[0031] - 6 -

[0032] The direction for separating the bipolar plates and the membrane electrode units is arranged in a movable manner.

[0033] Finally, the invention also comprises a method for separating bipolar plates and membrane electrode assemblies of a fuel cell stack using a device as described so far, wherein the method comprises at least the following steps: First, an initial gap is formed between a bipolar plate and a membrane electrode assembly on the side facing the holding device. Then, a holding element of the holding device is positioned in the initial gap. Subsequently, the holding element is moved relative to another holding element of the holding device in order to position and, if necessary, fix the bipolar plate or the membrane electrode assembly in the area of ​​a receptacle between the two holding elements.Finally, the separating body is inserted into the initial gap below the holding elements and moved in a direction projecting away from the holding device to preferably completely separate the bipolar plate from the membrane electrode unit arranged below it or the membrane electrode unit from the bipolar plate arranged below it.

[0034] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawing.

[0035] Brief description of the drawing

[0036] Fig. 1 shows a highly simplified representation of a separation device for separating bipolar plates and membrane electrode assemblies of a fuel cell stack in a perspective view and

[0037] Fig. 2 shows a flowchart illustrating a separation process using a bipolar plate as an example. R.413780

[0038] - 7 -

[0039] Embodiments of the invention

[0040] Figure 1 shows a highly simplified representation of a fuel cell stack 100, consisting of a plurality of fuel cells arranged in a straight line. Each fuel cell also comprises, as is known per se, two bipolar plates 101 and a membrane electrode assembly (not shown in Figure 1) arranged between the two bipolar plates 101. The membrane electrode assembly is mechanically connected to the two bipolar plates 101 via sealing elements. To separate the fuel cell components, a bipolar plate 101 and a membrane electrode assembly are alternately separated from each other.

[0041] Furthermore, the bipolar plates 101 have recesses 102; in the illustrated embodiment, three recesses 102 are arranged side by side on each of the two opposite sides of the bipolar plates 101 and the membrane electrode assemblies. The bipolar plate 101 also has a semicircular indentation 104 in the region of a side edge 103 of the bipolar plate 101, in the region of which an enlarged gap 105 is formed between a bipolar plate 101 and a membrane electrode assembly, which is used to separate a bipolar plate 101 from a membrane electrode assembly. The fuel cell stack 100 is, by way of example, arranged on a platform 110 and fixed there.

[0042] A device 1 is provided for detaching or separating the uppermost bipolar plate 101 or the uppermost membrane electrode assembly from the fuel cell stack 100. The device comprises at least a strip-shaped separating element 2 and a holding device 10. The separating element 2 is coupled to a drive mechanism 5, which is configured to move the separating element 2 in the x-direction of a Cartesian coordinate system over the entire length L of the bipolar plate 101 or the membrane electrode assembly.

[0043] Furthermore, the drive mechanism 5 can also be used to adjust the height of the separating body 2 in the positive or negative z-direction. The separating body 2, which is moved parallel to the plane of the lower plane running between the two bipolar plates 101 for the separation process of a bipolar plate 101 or a membrane electrode unit, also has an R.413780

[0044] - 8 -

[0045] The separating body 2 has a width that corresponds at least to the width B of the bipolar plates 101 or the membrane electrode assemblies. Furthermore, the separating body 2 has a separating surface 6 arranged at an oblique angle in order to allow the upper bipolar plate 101 to be separated or peeled off from the membrane electrode assembly arranged below it, or a membrane electrode assembly from a bipolar plate 101 arranged below it, when the separating body 2 is moved in the x-direction.

[0046] The holding device 10 comprises two holding elements 12, 14. The first holding element 12 is designed in particular in the form of a flat blade or similar and serves, in addition to its function of holding a bipolar plate 101 or a membrane electrode assembly, to form a local initial gap between a bipolar plate 101 and a membrane electrode assembly, wherein either the bipolar plate 101 or the membrane electrode assembly forms the upper element of the two components mentioned. For this purpose, the first holding element 12, which simultaneously forms a separating element 16, is movably arranged in the x, y, and z directions by being coupled to a further drive mechanism 18.

[0047] The second retaining element 14 is arranged essentially above the first retaining element 12 and has a U-shaped cross-section with a base section 20 and, for example, two legs 22, 24 projecting perpendicularly from the base section 20 towards the recesses 102. The second retaining element 14 is preferably formed from a sheet metal part by forming and is also coupled to a drive mechanism 26, which is configured to move the second retaining element 12 at least in the z-direction. The movement in the z-direction allows the two legs 22, 24 of the second retaining element 12 to penetrate the recesses 102 of the bipolar plate 101 or the membrane electrode assembly and to be lowered to a position in which the end faces of the legs 22, 24 facing away from the base section 20 are below the level of the first retaining element 12.

[0048] A recess 30 can be formed between the base section 20 of the second retaining element 14 and the first retaining element 12, in which, according to Fig. 1 R.413780

[0049] - 9 -

[0050] The end section 106 of the uppermost bipolar plate 101 or the uppermost membrane electrode assembly, which faces the holding device 10, can be positioned. Furthermore, because the two legs 22, 24 penetrate the recesses 102, movement of the end section 106 in the x-direction is limited. Movement in the positive and negative y-directions is also not possible or is limited.

[0051] The device 1 described so far for separating bipolar plates 101 and membrane electrode assemblies of the fuel cell stack 100 operates according to the flowchart in Fig. 2, using the separation of a bipolar plate 101 as an example, as follows: In a first step 1001, the first retaining element 12 of the holding device 10 is used as a separating element 16. For this purpose, it is positioned in the z-direction between the uppermost bipolar plate 101 and the membrane electrode assembly of the fuel cell stack 100 located below it in the area of ​​the notch 105, such that it can then penetrate between the bipolar plate 101 and the membrane electrode assembly in the x-direction. Subsequently, in a second step 1002, the separating element 16, or the first retaining element 12, is moved in a positive or negative direction.moved in the negative y-direction until the initial gap is formed between the bipolar plate 101 and the membrane electrode unit over the entire width B of the bipolar plate 101 and the membrane electrode unit over part of the length in the x-direction.

[0052] Subsequently, in step 1003, the first retaining element 12 is raised or adjusted in the z-direction such that the separating body 2 can be moved in the x-direction between the bipolar plate 101 and the membrane electrode assembly in step 1004. Either by moving the first retaining element 12 in the z-direction, or by lowering the second retaining element 14 in the opposite z-direction, the end section 106 of the upper bipolar plate 101 is positioned between the two retaining elements 12, 14 in the area of ​​the receptacle 26. A height adjustment mechanically decoupled from the other elements can also be achieved by the platform 110 of the fuel cell stack. In this way, the first retaining element 12 acts as the lower stop element and the second retaining element 14 as the upper stop element for the bipolar plate 101. Subsequently, in step R.413780

[0053] - IQ -

[0054] 1005 a movement of the separating body 2 in the x-direction to completely separate the bipolar plate 101 from the underlying membrane electrode assembly. During the movement of the separating body 2, in conjunction with the bipolar plate 101 exhibiting a certain degree of flexibility, a force in the x-direction is generated on the bipolar plate 101. Since the second retaining element 14, with its two legs 22, 24, penetrates the recesses 102 of the bipolar plate 101, movement of the bipolar plate 101 in the x-direction is prevented, or rather, the second retaining element 14 acts as a stop element in the x-direction for the bipolar plate 101. Furthermore, because the two legs 22, 24 are positioned in a plane below the first retaining element 12, movement of the bipolar plate 101 to a level below the first retaining element 12 is also prevented, since the bipolar plate 101 is always positioned in the receptacle 30 formed between the retaining elements 12, 14.In an analogous manner, a membrane electrode unit is separated from a bipolar plate 101 arranged below it.

[0055] The holding device 10 described so far can be modified or adapted in a variety of ways without deviating from the inventive concept.

[0056] to deviate.

Claims

R.413780 - 11 - Claims 1. Holding device (10) for cell layers (101) of a cell stack (100), in particular bipolar plates (101) and membrane electrode assemblies of a cell stack (100) of an electrochemical cell, preferably of a fuel cell stack (100) of a fuel cell, comprising two holding elements (12, 14) configured to receive one of the cell layers (101), in particular a bipolar plate (101) or a membrane electrode assembly, at an end section (106) of the cell layer (101), in particular the bipolar plate (101) or the membrane electrode assembly, between the holding elements (12, 14), wherein one holding element (14) is configured to be positioned at least partially below, and the other holding element (12) is configured to be positioned at least partially above the cell layer (101), in particular the bipolar plate (101) or the membrane electrode assembly, in order to provide a receptacle (30) for the end section (106) of the cell position (101),in particular the bipolar plate (101) or the membrane electrode unit between the retaining elements (12, 14), and wherein the retaining device (10) is designed to prevent movement of the cell layer (101), in particular the bipolar plate (101) or the membrane electrode unit, out of the receptacle (30).

2. Holding device according to claim 1, characterized by that the two retaining elements (12, 14) are designed to prevent the movement of the cell layer (101), in particular the bipolar plate (101) or the membrane electrode assembly, from the receptacle (30).

3. Holding device according to claim 2, characterized by that one retaining element (14) has a base section (20) to form an upper stop for the cell layer (101), in particular the bipolar plate (101) or the membrane electrode unit, and at least one of the base section (20) extends towards the other retaining element (12). R.413780 - 12 - preferably having vertically extending legs (22, 24) to prevent movement of the cell layer (101), in particular the bipolar plate (101) or the membrane electrode unit from the receptacle (30).

4. Holding device according to claim 3, characterized by that at least one leg (22, 24) with an end section facing away from the base section (20) can be lowered to a position below the plane of the other retaining element (12).

5. Holding device according to one of claims 1 to 4, characterized by that at least one of the retaining elements (12, 14) is coupled to a drive mechanism (18, 26) which is designed to realize a movement of the retaining element (12, 14) at least in a direction perpendicular to the plane of the cell layer (101), in particular the bipolar plate (101) or the membrane electrode unit.

6. Holding device according to one of claims 1 to 5, characterized by that one retaining element (14) is U-shaped and is preferably made from a bent sheet metal part.

7. Holding device according to one of claims 1 to 6, characterized by that the other retaining element (12) is simultaneously designed as a separating element (16) for the local separation of one of the cell layers (101), in particular the bipolar plate (101), from the membrane electrode unit.

8. Holding device according to claim 7, characterized by that the other holding element (12) is designed to be movable in all three directions of a Cartesian coordinate system. R.413780 - 13 - 9. Device (1) for separating cell layers (101) of a cell stack (100), in particular bipolar plates (101) and membrane electrode assemblies of a cell stack (100) of an electrochemical cell, preferably of a fuel cell stack (100) of a fuel cell, comprising a holding device (10) preferably designed according to one of claims 1 to 8, and comprising a preferably strip-like separating element (2) which can be positioned below the holding device (10) and is movably arranged in a direction projecting away from the holding device (10) for separating the cell layer (101), in particular the bipolar plates (101) and the membrane electrode assemblies.

10. Method for separating cell layers (101) of a cell stack (100), in particular bipolar plates (101) and membrane electrode assemblies of a cell stack (100) of an electrochemical cell, preferably of a fuel cell stack (100) of a fuel cell, by means of a device (1) according to claim 9, comprising at least the following steps: - Forming an initial gap between the cell layer (101), in particular a bipolar plate (101) and a membrane electrode unit on the side facing the holding device (10); - Positioning a holding element (12) of the holding device (10) in the initial gap; - Moving the holding element (12) relative to another holding element (14) of the holding device (10) in order to position the cell layers (101), in particular the bipolar plate (101) or the membrane electrode unit in the area of ​​a receptacle (30) between the two holding elements (12, 14) and, if necessary, clamp or fix them; - Inserting the separating body (2) between the cell layers (101), in particular the bipolar plate (101) and the membrane electrode assembly or between the membrane electrode assembly and the bipolar plate (101) below the retaining elements (12, 14) and moving the separating body (2) in a direction projecting away from the retaining device (10) to preferably completely separate the cell layer (101), in particular the bipolar plate (101), from the membrane electrode assembly arranged below it or the membrane electrode assembly from the bipolar plate (101) arranged below it.

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