Cell layer separating device for simultaneously separating cell layers of a cell stack of a fuel cell

Abstract

The invention relates to a cell layer separating device (10; 10'; 10'') for simultaneously separating a plurality of cell layers (12, 14), which are adhered together, of a cell stack (16), in particular of an electrochemical cell, comprising a holding unit (22; 22'; 22'') which has a plurality of separating units (24; 24'; 24'') that are arranged in a mutually spaced manner along an arranging direction (26) and are to be simultaneously inserted between the adhered cell layers (12, 14) to be separated along an intended insertion direction (28) pointing transversely to the arranging direction (26) in order to simultaneously separate the plurality of adhered cell layers (12, 14) of the cell stack (16).

Description

[0001] Description

[0002] title

[0003] Cell layer separation device for the simultaneous separation of cell layers of a cell stack of a fuel cell

[0004] State of the art

[0005] The invention relates to a cell layer separating device and the use of such a cell layer separating device for simultaneously separating a plurality of adhering cell layers of a cell, in particular an electrochemical cell, as well as a method for simultaneously separating a plurality of adhering cell layers of a cell stack, in particular an electrochemical cell.

[0006] When recycling a wide variety of products, such as packaging, electronic waste, etc., the products are typically subjected to "undefined" size reduction, i.e., shredded or ground. The valuable fractions are then separated from the less valuable ones and further processed.

[0007] Fuel cell stacks consist of membrane electrode assemblies (MEAs), which include membranes, gas diffusion layers (GDLs), and sealing frames, as well as bipolar plates (BPPs), which are typically made of sheet steel or milled graphite plates. These two components—MEAs and BPPs—are stacked alternately on top of each other. A typical automotive fuel cell stack with approximately 100 kW output consists of approximately 350 to 450 BPPs and the same number of MEAs. Depending on the product design, the components are increasingly bonded together by the seals or the GDL with increasing mileage.

[0008] The recycling of fuel cell stacks follows the process described in the introduction, which has several disadvantages. First, the MEAs are difficult to separate from the BPPs for recycling or remanufacturing due to increasing adhesion / corrosion. This leads to highly valuable particles or dust containing platinum adhering to the bipolar plate fragments, being sorted out with them and thus irretrievably lost. Remanufacturing, for example, of bipolar plates is generally impossible due to the destructive shredding involved. Furthermore, an undefined disassembly process for recycling carries the risk of significant loss of valuable materials.

[0009] Should rework be necessary in today's stack prototype production (with very low production numbers), a knife or spatula is manually inserted between two cell layers and the adhesive seal is carefully removed. This manual process is very inefficient because, firstly, it only works very locally, as the tool must be carefully guided around the entire stack circumference (roughly 0.75-1 m), and secondly, only one cell layer is removed at a time.

[0010] Disclosure of the invention

[0011] The subject matter of the present invention is a cell layer separating device for simultaneously separating a plurality of adhering cell layers of a cell stack, in particular of an electrochemical cell, with a holding unit having a plurality of separating units arranged at a distance from one another along an arrangement direction for simultaneous insertion between the adhering cell layers to be separated along a designated insertion direction pointing transversely to the arrangement direction in order to simultaneously separate the plurality of adhering cell layers of the cell stack from one another.

[0012] The present invention further relates to the use of a cell layer separating device of the type described above for simultaneously separating a plurality of adhering cell layers of a cell stack, in particular of an electrochemical cell.

[0013] The present invention also relates to a method for simultaneously separating a plurality of adhering cell layers of a cell stack, in particular of an electrochemical cell, comprising the steps of: - providing a cell layer separating device of the type described above; and

[0014] - Simultaneously inserting the plurality of separating units of the cell layer separating device between the adhering cell layers to be separated along the intended insertion direction in order to separate the plurality of adhering cell layers from one another.

[0015] Against this background, the invention proposes a cell layer separation device which enables the simultaneous separation of a plurality of adhering cell layers of a cell stack of an electrochemical cell, such as a fuel cell and / or an electrolyzer, whereby disassembly for recycling or remanufacturing can be carried out much more easily, quickly and thus more efficiently.

[0016] In the context of the present invention, an electrochemical cell includes, in particular, a fuel cell and / or an 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] In the context of the present invention, a cell layer separating device is to be understood as a device which is designed and dimensioned accordingly in order to simultaneously separate a plurality of adhering cell layers of a cell stack of an electrochemical cell, such as a fuel cell and / or an electrolyzer.

[0018] A cell layer of the cell stack can comprise or consist of a membrane electrode assembly (MEA) or a bipolar plate (BPP). Accordingly, the cell stack can comprise, for example, 700 to 1000 cell layers comprising 350 to 500 BPPs and 350 to 500 MEAs.

[0019] Depending on the embodiment, the holding unit can be rod-shaped, plate-shaped, or frame-shaped. A plurality of separation units are arranged on the holding unit, which are distributed at a distance from one another along an arrangement direction. The arrangement direction preferably runs transversely or perpendicularly to the plane of the cell layers to be separated. The number of separation units and / or the distance between the separation units is / are adapted to the cell stack and, if applicable, the respective manufacturing tolerances and geometric component tolerances. The number of separation units can, for example, range from greater than or equal to 5 to less than or equal to 30 separation units. If, for example, the thickness of the BBPs and the distance between the BBPs are quite precise, the number of separation units can be selected in the upper range.The distance between the separation units is preferably in a range of greater than or equal to 0.3 mm to less than or equal to 0.8 mm, more preferably in a range of greater than or equal to 0.4 mm to less than or equal to 0.6 mm.

[0020] The distance between the separation units can be fixed and unchangeable. However, it is advantageous if the distance between the separation units is adjustable. In this case, it is advantageous if, in order to adjust the distance, the separation units are mounted on the holding unit so that they can be moved linearly along the arrangement direction, in particular in a floating or spring-loaded manner, and / or are mounted so that they can rotate about a direction of rotation, in particular transverse to the arrangement direction and the intended insertion direction. This measure allows the cell layer separation device to be adapted to the cell stack in a very simple manner, as well as to adapt manufacturing tolerances and geometric component tolerances. This in turn leads to the number of separation units being maximized, so that more cell layers or ideally all cell layers of the cell stack can be separated in a single work step, i.e.can be separated from each other by inserting the separation units in a single step, which further shortens the disassembly or dismantling time of the cell stack. On the other hand, the separation or disassembly of the cell layers can be carried out very gently and largely damage-free, thus minimizing the loss of valuable elements and increasing the recyclability of the MEAs and BPPs.

[0021] The separation units are designed and dimensioned to be simultaneously inserted between the adhering cell layers to be separated along a designated insertion direction extending transversely to the arrangement direction. The designated insertion direction preferably runs substantially parallel to the plane of the cell layers to be separated. The separation units can be arranged offset from one another along the designated insertion direction; in particular, some of the separation units can be arranged at the front in the designated insertion direction, and the remaining part of the separation units can be arranged offset to the rear. Preferably, all separation units of the cell layer separation device are of the same design.

[0022] The separating units for separating the cell layers are preferably wedge-shaped and / or pointed and tapered in the intended insertion direction. Alternatively or additionally, the separating units for separating the cell layers are preferably designed to be expandable along a spreading direction and, in particular, each have a separating leg that can be expanded along the spreading direction. In other words, each separating unit can have two separating legs, with one separating leg being fixed and the other separating leg being designed to be movable away from it and thus expandable. The spreading direction preferably runs transversely or perpendicularly to the plane of the cell layers to be separated.

[0023] For these embodiments, at least two cell layer separating devices are preferably provided in the provision step, the separating units of which are then simultaneously inserted on different, in particular opposite, sides of the cell stack up to a defined insertion depth. The sides can preferably be the long sides of the cell stack. This measure can further optimize the separation or disassembly of the cell layers.

[0024] Alternatively, it is advantageous if the separation units for separating the cell layers are wire-shaped or fiber-shaped and in particular are designed as wires or threads / cords / yarns arranged parallel to one another along the arrangement direction. In this case, it is particularly advantageous if the holding unit is designed and the separation units are arranged and designed in such a way that the cell layer separation device for separating the cell layers can be guided in the insertion direction from one side of the cell stack to an opposite side of the cell stack. In other words, for example, a large number of parallel-tensioned wires or threads can be arranged as separation units in a frame-shaped holding unit, which, when inserted into the cell stack, are threaded into the spaces between the cell layers to be separated. It is also not detrimental to the function if several of these wires are threaded into one space.

[0025] For these embodiments, a single cell layer separating device is preferably provided in the provision step, the separating units of which are guided through the cell stack from one side of the cell stack to an opposite side of the cell stack in the simultaneous insertion step. The sides can preferably be the long sides of the cell stack. This measure offers the advantage that the separating units are guided transversely through the cell stack once, allowing the cell layers to be separated from one another very effectively, quickly, and gently.

[0026] It is advantageous if a sensor unit is provided which is designed to detect at least one, in particular two or three of the following variables: force along and / or against the intended insertion direction, path along the intended insertion direction, spreading force along and / or against the spreading direction of the spreadable separating units, wire tension of the wire-shaped separating units, fiber tension of the fiber-shaped separating units.

[0027] The counterforce can be measured directly at the separation units themselves and / or the holding unit and / or a drive unit of the separation units. However, the counterforce can also be measured indirectly at the cell stack, whereby, for example, conclusions about the counterforce can be drawn based on a bending, and thus with a known geometry and material of the bent / loaded part. The bending can be measured using compact strain gauges (SGs).

[0028] Drawings

[0029] The invention is explained in more detail below with reference to the accompanying drawings. Figure 1 shows a schematic representation of a cell layer separation device with wedge-shaped separation units;

[0030] Fig. 2 is a schematic representation of a cell layer separating device with spreadable separating legs;

[0031] Fig. 3 is a schematic representation of a cell layer separator with wires;

[0032] Fig. 4 is a schematic plan view of an arrangement of a cell stack with two inserted cell layer separators; and

[0033] Fig. 5 is a flowchart of a method for simultaneous

[0034] Separating a plurality of adhering cell layers of a cell stack of a fuel cell and / or an electrolyzer

[0035] In the following description of advantageous embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and having a similar effect, whereby a repeated description of these elements is omitted.

[0036] Fig. 1 to Fig. 3 show advantageous embodiments of cell layer separating devices, which are provided in their entirety with the reference numeral 10; 10'; 10".

[0037] The cell layer separators 10; 10'; 10" are designed to simultaneously separate a plurality of adhering cell layers 12, 14 of a cell stack 16 of a fuel cell (not shown). Each cell layer 12 to be separated comprises a bipolar plate 12, and each cell layer 14 comprises a membrane electrode assembly 14. The membrane electrode assemblies 14 each comprise gas diffusion layers (GDL) 18 and a sealing frame 20.

[0038] The cell layer separating devices 10; 10'; 10" each have a holding unit 22; 22'; 22". A plurality of separating units 24; 24'; 24" are provided on each holding unit 22; 22'; 22", which are arranged spaced apart from one another along an arrangement direction 26. The arrangement direction 26 runs essentially perpendicular to the plane of the cell layers 12, 14 to be separated. The separating units 24; 24'; 24" are designed and dimensioned to be simultaneously insertable between the adhering cell layers 12, 14 to be separated along a designated insertion direction 28 pointing transversely to the arrangement direction 26. The designated insertion direction 28 runs essentially parallel to the plane of the cell layers 12, 14 to be separated.

[0039] Fig. 1 shows a first embodiment of the cell layer separating device 10, wherein the separating units 24 for separating the cell layers 12, 14 are wedge-shaped and tapered in the intended insertion direction 28.

[0040] Fig. 2 shows a second embodiment of the cell layer separation device 10', wherein the separation units 24' are designed to be spreadable along a spreading direction 30 for separating the cell layers 12, 14. The separation units 24' each have a separating leg 32 that can be spread along the spreading direction 30 and a fixed separating leg 34.

[0041] Fig. 3 shows a third embodiment of the cell layer separation device 10", wherein the separation units 24" for separating the cell layers 12, 14 are designed as wires 24" arranged parallel to one another along the arrangement direction 26. Here, the holding unit 22" is designed and the wires 24" are arranged and designed in such a way that the cell layer separation device 10" for separating the cell layers 12, 14 can be guided in the insertion direction 28 from one side of the cell stack 16 to an opposite side of the cell stack 16.

[0042] Fig. 4 shows a schematic top view of an arrangement of a cell stack 16 with two inserted cell layer separators 10; 10'. The separating units 24; 24' of the cell layer separators 10; 10' were simultaneously inserted on opposite longitudinal sides of the cell stack 16 to a defined insertion depth in order to optimize the separation process.

[0043] Fig. 5 shows a flowchart of a method 100 for simultaneous

[0044] Separating a plurality of adhering cell layers 12, 14 of a cell stack 16, in particular an electrochemical cell. The method 100 comprises a step of providing 102 a cell layer separating device 10; 10'; 10" of the type described above. The method 100 further comprises a step of simultaneously introducing 104 the plurality of separation units 24; 24'; 24" of the cell layer separating device 10; 10'; 10" between the adhering cell layers 12, 14 to be separated along the intended insertion direction 28 in order to separate the plurality of adhering cell layers 12, 14 from one another. If an embodiment includes an "and / or" connection between a first feature and a second feature, this should be read such that the embodiment, according to one embodiment, has both the first feature and the second feature, and according to another embodiment, has either only the first feature or only the second feature.

Claims

Claims 1. Cell layer separating device (10; 10'; 10”) for simultaneously separating a plurality of adhering cell layers (12, 14) of a cell stack (16), in particular an electrochemical cell, with a holding unit (22; 22'; 22”) comprising a plurality of separation units (24; 24'; 24”) spaced apart from one another along an arrangement direction (26) for simultaneous insertion between the adhering cell layers (12, 14) to be separated along a designated insertion direction (28) perpendicular to the arrangement direction (26), in order to simultaneously separate the plurality of adhering cell layers (12, 14) of the cell stack (16) from one another.

2. Cell layer separation device (10; 10'; 10”) according to claim 1 , characterized in that the distance between the separation units (24; 24'; 24”) is in a range of greater than or equal to 0.3 mm to less than or equal to 0.8 mm, in particular in a range of greater than or equal to 0.4 mm to less than or equal to 0.6 mm.

3. Cell layer separation device (10; 10'; 10”) according to claim 1 or 2, characterized in that the distance between the separation units (24; 24”; 24”) is adjustable.

4. Cell layer separation device (10; 10'; 10”) according to claim 3, characterized in that, for adjusting the distance, the separation units (24; 24'; 24”) are linearly movable on the holding unit (22; 22'; 22”) along the arrangement direction (26), in particular floating or spring-loaded mountings; and / or are spring-loaded mountings rotatably about a direction of rotation, in particular transverse to the arrangement direction (26) and the intended insertion direction (28).

5. Cell layer separation device (10; 10') according to one of the preceding claims, characterized in that the separation units (24; 24') for separating the cell layers (12, 14) are wedge-shaped and / or pointed and in The intended insertion direction (28) is tapered. Cell layer separation device (10') according to one of the preceding claims, characterized in that the separation units (24') for separating the cell layers (12, 14) are designed to be spread along a spreading direction (30), and in particular each have a separating leg (32) that can be spread along the spreading direction (30). Cell layer separation device (10”) according to one of claims 1 to 4, characterized in that the separation units (24”) for separating the cell layers (12, 14) are designed to be wire-shaped or fiber-shaped and in particular are designed as wires (24”) or threads arranged parallel to each other along the arrangement direction (26).Cell layer separator (10”) according to claim 7, characterized in that the holding unit (22”) is designed and the separating units (24”) are arranged and designed such that the cell layer separator (10”) can be guided in the insertion direction from one side of the cell stack (16) to an opposite side of the cell stack (16) for separating the cell layers (12, 14). Cell layer separator (10; 10'; 10”) according to any one of the preceding claims, characterized in that the separating units (24; 24'; 24”) are arranged offset from one another along the intended insertion direction (28), in particular a portion of the separating units (24; 24'; 24”) are arranged at the front in the intended insertion direction (28) and the remaining portion of the separating units (24; 24'; 24”) are arranged offset to the rear.Cell layer separation device (10; 10'; 10”) according to one of the preceding claims, characterized in that all separation units (24; 24'; 24”) are identical. Cell layer separation device (10; 10'; 10”) according to one of the preceding claims, characterized by a sensor unit which is configured is to detect at least one, in particular two or three, of the following quantities: force along and / or against the intended insertion direction (28), displacement along the intended insertion direction (28), spreading force along and / or against the spreading direction (30) of the expandable separation units (24'), wire tension of the wire-shaped separation units (24"), fiber tension of the fiber-shaped separation units (24"). Use of a cell layer separation device (10; 10'; 10") according to one of the preceding claims for simultaneously separating a plurality of adhering cell layers (12, 14) of a cell stack (16), in particular an electrochemical cell. Method (100) for simultaneously separating a plurality of adhering cell layers (12, 14) of a cell stack (16), in particular an electrochemical cell, comprising the steps: - Providing (102) a cell layer separation device (10; 10'; 10”) according to any one of claims 1 to 11; and - Simultaneous insertion (104) of the plurality of separation units (24; 24'; 24”) of the cell layer separation device (10; 10'; 10”) between the adhering cell layers (12, 14) to be separated along the intended insertion direction (28) in order to separate the plurality of adhering cell layers (12, 14) from one another. Method (100) according to claim 13, characterized in that - in the provisioning step (102) at least two cell layer separation devices (10) according to one of claims 1 to 6 and 9 to 11 are provided, the separation units (24; 24') of which are inserted simultaneously to a defined insertion depth in the simultaneous insertion step (104) on different, in particular opposite, sides of the cell stack (16); or - in the step of provision (102) a cell layer separation device (10”) according to one of claims 1 to 4 and 7 to 11 is provided, the separation units (24”) of which are guided through the cell stack (16) from one side to an opposite side of the cell stack (16) in the step of simultaneous insertion (104). Use according to claim 12 or method according to claim 13 or 14, characterized in that each cell layer (12, 14) of the plurality of cell layers (12, 14) of the cell stack (16) comprises or consists of a membrane electrode unit (14) or a bipolar plate (12).

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