Seal assembly, method for producing same, and component of an electrochemical cell

Abstract

The invention relates to a method for producing a seal assembly (1), comprising the following steps: - providing a 3D-printed support structure (2) comprising at least one annular groove (3, 3') having a groove base (4) and bevelled groove edges (5a, 5b); - providing at least one thermoplastic sealing material (6); - heating and liquefying the at least one thermoplastic sealing material (6); - depositing at least one first sealing bead (7a) of the at least one liquefied sealing material (6) onto the groove base (4) of the annular groove (3, 3') by means of at least one first nozzle unit (20), which has a first nozzle opening (20a) with a first diameter (D1) which is smaller than a width (B) of the groove base (4) of the annular groove (3, 3'). The invention also relates to a seal assembly (1), a component (11) and an electrochemical cell (100).

Description

[0001] Sealing arrangement, method for its production and component of an electrochemical cell

[0002] The invention relates to a sealing arrangement for an electrochemical cell, which is produced using a 3D printing process, and to a component of an electrochemical cell with such a sealing arrangement.

[0003] Sealing arrangements for electrochemical cells, such as fuel cells, electrolyzers, or redox flow cells, are well known. Such seals are typically applied around the areas to be sealed on a component, for example, bipolar plates or membrane electrode assemblies. A liquid sealant is typically used, which is then cured.

[0004] DE 10 2019 216 667 A1 describes a method for producing a sealing arrangement for a distribution structure of a fuel cell. A sealing compound is applied to a support structure and cured, with the curing taking place in the absence of oxygen. The sealing compound is applied to the support structure by injection molding, stamping, printing, 3D printing, offset printing, gravure printing, flexographic printing, or screen printing.

[0005] In particular, tool-based technologies for producing such sealing arrangements are expensive due to tool costs and lack geometric flexibility.

[0006] The object of the invention is to provide a cost-effective and rapid method for producing a sealing arrangement. Furthermore, the object of the invention is to provide a sealing arrangement produced according to this method and a component of an electrochemical cell comprising such a sealing arrangement.

[0007] The problem is solved for the method for producing a sealing arrangement, comprising the following steps:

[0008] - Providing a 3D-printed support structure comprising at least one annular groove with a groove base and chamfered groove edges,

[0009] - Providing at least one thermoplastic sealing material,

[0010] - Heating and liquefying the at least one thermoplastic sealing material,

[0011] - depositing at least one first sealing bead made of the at least one liquefied sealing material on the groove base of the annular groove by means of at least one first nozzle unit which has a first nozzle opening with a first diameter D1 which is less than or equal to a width B of the groove base of the annular groove.

[0012] Such a sealing arrangement has the advantage of providing a particularly strong bond between the support structure and the sealing material. Furthermore, the use of 3D printing to manufacture the support structure allows for the simple creation of an annular groove with a suitable cross-section. Applying a sealing bead made of liquefied sealing material is quick and easy, with an automated application process using a robot. Furthermore, sealing beads made of different materials can be used.

[0013] Preferably, a second sealing bead of the at least one liquefied sealing material is deposited on the at least one first sealing bead, in particular in the region of the chamfered groove edges of the annular groove, by means of at least one second nozzle unit which has a second nozzle opening with a second diameter D2 which is smaller than the diameter D1 of the first nozzle opening.

[0014] A first diameter D1 of the first nozzle opening of up to 5 mm, in particular of 2 mm, has proven to be advantageous. A second diameter D2 of the second nozzle opening of up to 1.5 mm, in particular of 0.5 mm, has also proven to be advantageous. The groove base of the annular groove is preferably covered by the at least one first sealing bead. Alternatively, the groove base can also be only partially covered by the at least one first sealing bead. In this case, a plurality of first sealing beads can be placed at a distance from one another and parallel to one another on the groove base. Furthermore, a plurality of first sealing beads can be placed parallel to one another on the groove base, with two adjacent first sealing beads touching one another.

[0015] In particular, but not necessarily, the second sealing beads are arranged in the area of ​​the chamfered groove edges of the annular groove and spaced apart from one another on the at least one first sealing bead. Second sealing beads are those arranged closest to the groove edges on both sides of a first sealing bead.

[0016] In a preferred embodiment, at least one third sealing bead is arranged between the second sealing beads.

[0017] Preferably, further sealing beads are deposited on the second sealing beads and the at least one third sealing bead by means of at least one third nozzle unit having a third nozzle opening with a third diameter that is smaller than the second diameter D2 of the second nozzle opening.

[0018] The at least one first sealing bead, optionally the second sealing bead, the at least one third sealing bead, and the further sealing bead, form(s) at least one seal in the solidified state, which is firmly anchored in the annular groove. The formed seal can be a continuous seal formed from multiple sealing beads or consist of multiple separate sealing beads.

[0019] The at least one first sealing bead, the second sealing bead, the at least one third sealing bead, and the further sealing bead are preferably formed from at least two different sealing materials. Thus, a sealing material can be selected for the groove base that bonds particularly firmly to the support structure and has a stiffer consistency when solidified, while the sealing bead(s) arranged thereon can each be adapted to the sealing material of the sealing bead(s) arranged below with regard to adhesion and the generally required elastic deformation capacity of the seal.

[0020] The object is achieved for the sealing arrangement produced according to the method according to the invention in that it is formed comprising the 3D-printed carrier structure with the at least one annular groove, which has a groove base and chamfered groove edges, and wherein a seal is located in the annular groove, which is provided by the solidified sealing beads.

[0021] The groove base of the annular groove is either flat or has a three-dimensional structure. The roughness of the 3D-printed surface of the support structure can already ensure a strong bond with at least one initial sealing bead if the groove base is flat. If the adhesion of the sealing material in the groove base needs to be further improved, the groove base can have a three-dimensional structure, for example, in the form of grooves, knobs, or hooks.

[0022] The object is achieved for the component of an electrochemical cell in that it is configured to comprise at least one sealing arrangement according to the invention. In particular, the electrochemical cell is a fuel cell, in particular a polymer electrolyte fuel cell, or an electrolyzer for the electrolysis of water, or a redox flow cell. The support structure is preferably provided by a separator plate or a bipolar plate. A support structure made of steel, titanium, or titanium alloys has proven suitable. Other possible support structures can be made of plastic or ceramic. Thermoplastic polyurethane elastomers, such as Elastollan® from BASF, or ChromaFlow 90 from Chromatic 3D Materials Inc., have proven suitable as sealing materials. These can be used in combination with one another.

[0023] The use of at least one component according to the invention in an electrochemical cell, in particular a fuel cell, an electrolyzer for the electrolysis of water, or a redox flow cell, has proven advantageous in terms of manufacturing costs and the achieved gas tightness. However, the use of a sealing arrangement in a battery cell is also possible.

[0024] Figures 1 to 7 illustrate the invention by way of example. They show:

[0025] Figure 1 shows a support structure with two annular grooves in cross-section,

[0026] Figure 2 shows schematically the process sequence for producing a sealing arrangement,

[0027] Figure 3 shows a sealing arrangement with a membrane electrode unit,

[0028] Figure 4 shows a sealing arrangement with two differently constructed

[0029] seals,

[0030] Figure 5 shows another sealing arrangement with two differently constructed seals,

[0031] Figure 6 shows a component comprising a support structure in the form of a bipolar plate, and

[0032] Figure 7 shows a cell stack comprising a plurality of electrochemical cells.

[0033] Figure 1 shows a support structure 2 in section with two annular grooves 3, 3'. The annular groove 3 on the left in the image has a vertical wall area starting from the groove base 4. The groove edges 5a, 5b of the annular groove 3 are chamfered, i.e. starting from the vertical wall area a slope extends to the edge of the annular groove 3. The further annular groove 3' on the right in the image has no vertical wall area starting from the groove base 4. The groove edges 5a, 5b of the further annular groove 3' are chamfered, with the slope directly adjoining the groove base 4. Both groove shapes are preferred with regard to their use in forming the sealing arrangement 1 (cf. Figures 3 to 5). However, other similar groove shapes can also be used, in which, for example, a bulbous wall starts from the groove base 4 and merges into the slope.The formation of the support structure 2 by a 3D printing process allows for a variety of groove shapes, including undercut groove shapes that allow the seal to hook into the annular groove 3, 3'. The groove base 4 has a width B.

[0034] Figure 2 shows a schematic of the process sequence for producing a sealing arrangement 1 (cf. Figures 3 to 5). A support structure 2 is provided using a 3D printing process. Figure 2 shows a section through the support structure 3 with a central opening, around which an annular groove 3 with a groove base 4 and chamfered groove edges 5a, 5b (cf. Figure 1) is formed. The central opening can, for example, be a fluid passage opening 31, 31', cf. Figure 6. In a first step, a thermoplastic sealing material 6 is provided, heated, and liquefied. This is preferably carried out in an extruder. The liquefied sealing material 6 is deposited from the extruder onto the groove base 4 of the annular groove 3 by means of a first nozzle unit 20 in the form of a first sealing bead 7a.The first nozzle unit 20 has a first nozzle opening 20a with a first diameter D1 that is smaller than a width B of the groove base 4 of the annular groove 3 (see Figure 1). Subsequently, a second sealing bead 7b made of the at least one liquefied sealing material 6 is deposited on the first sealing bead 7a in the region of the chamfered groove edges 5a, 5b of the annular groove 3 by means of a second nozzle unit 21. The second nozzle unit 21 has a second nozzle opening 21a with a second diameter D2, wherein the second diameter D2 is smaller than the first diameter D1 of the first nozzle opening 20. After cooling, the first sealing bead 7a and the second sealing beads 7b together form a seal 10 (see Figure 3).

[0035] Figure 3 shows an example of a sealing arrangement 1 in a sectional view or a component 11 with such a sealing arrangement 1, which was formed according to the method shown in Figure 2. The sealing arrangement 1 comprises the support structure 2 and the annular seal 10 in the annular groove 3 in combination with a membrane electrode unit 40, which is pressed against the seal 10 and deforms it, here the areas formed from the second sealing beads 7b. In this case, the elevations of the seal 10 formed from the two second sealing beads 7b, which protrude beyond the groove edges 5a, 5b (compare Figures 1 and 2), are deformed and a seal is achieved between the support structure 2 and the membrane electrode unit 40.

[0036] Figure 4 shows, by way of example, a section view of part of a further sealing arrangement 1 with two differently constructed seals 10, 10'. The seal 10 on the left in the figure is located in an annular groove 3 and is constructed from two first sealing beads 7a in the groove base 4, two second sealing beads 7b in the region of the bevels on the groove edges 5a, 5b (cf. Figure 1), and two third sealing beads 7c, which were laid between the second sealing beads 7b on the first sealing beads 7a. The first sealing beads 7a are made of a different sealing material than the second and third sealing beads 7b, 7c, so that the seal 10 has a stiffer consistency in the region of the first sealing beads 7a than in the regions of the second and third sealing beads 7b, 7c. During the sealing process, the areas of the seal 10 formed by the second and third sealing beads 7b, 7c, which protrude beyond the groove edges 5a, 5b, are deformed in particular (see Figure 1).

[0037] The seal 10' on the right in the image is also located in an annular groove 3 and is constructed from two first sealing beads 7a in the groove base 4, two second sealing beads 7b in the area of ​​the bevels at the groove edges 5a, 5b (see Figure 1), and six third sealing beads 7c, which were laid between the second sealing beads 7b on the first sealing beads 7a. Furthermore, there are further sealing beads 7d, which are laid on the second and third sealing beads 7b, 7c. During the sealing process, the areas of the seal 10 formed by the further sealing beads 7d that protrude beyond the groove edges 5a, 5b (see Figure 1) are deformed.

[0038] Figure 5 shows a further sealing arrangement 1 in a sectional view with two differently constructed seals arranged in annular grooves 3' (see Figure 1). The seal on the left in the image is formed from four first sealing beads 7a, which are placed parallel to each other on the groove base 4 without touching each other. The cooled sealing beads 7a together form a seal and protrude beyond the groove edges 5a, 5b, allowing them to be deformed.

[0039] The seal on the right in the image is formed from eight first sealing beads 7a, which are laid parallel to one another on the groove base 4, with two adjacent first sealing beads 7a touching each other. Second sealing beads 7b are arranged on the touching first sealing beads 7a. Third sealing beads 7c are arranged between them. The cooled first, second, and third sealing beads 7a, 7b, 7c together form a seal, with the second and third sealing beads 7b, 7c protruding beyond the groove edges 5a, 5b, allowing them to be compressed and deformed.

[0040] Figure 6 shows a component 11 comprising a support structure 2 in the form of a bipolar plate 30 in a three-dimensional view. The bipolar plate 30 is composed of two sealing assemblies 1, only one of which, with its metallic support structure 2, is visible in this view. The bipolar plate 30 has fluid passage openings 31, 31', each surrounded by a seal 10 arranged in an annular groove 3 (see Figure 3 in section). Furthermore, the bipolar plate 30 has a flow field 32 in which channel-shaped three-dimensional structures are arranged for conducting the flow of fluids in an electrochemical cell 100 (see Figure 7). At the edge of the bipolar plate 30 there is a further annular groove 3 with a seal 10 intended to seal the circumference of the bipolar plate 30.

[0041] Figure 7 schematically shows a three-dimensional view of a cell stack 110 comprising a plurality of electrochemical cells 100. Each electrochemical cell 100 comprises two bipolar plates 30 or components 11 and a membrane electrode assembly 40 arranged therebetween. By pressing the cell stack 110 together, the seals 10 on the bipolar plates 30 are deformed, creating a seal on both sides with respect to the adjacent membrane electrode assembly 40. Such an electrochemical cell is, in particular, a fuel cell or an electrolyzer for electrolyzing water, or a redox flow cell. However, the use of a sealing arrangement in a battery cell is also possible.

[0042] List of reference symbols

[0043] 1 Sealing arrangement support structure, 3' annular groove groove base a, 5b chamfered groove edge sealing material a first sealing bead

[0044] 7b second sealing bead

[0045] 7c third sealing bead

[0046] 7d additional sealing beads

[0047] 10 Seal

[0048] 11 Component 0 first nozzle unit

[0049] 20a first nozzle opening

[0050] 21 second nozzle unit

[0051] 21a second nozzle opening

[0052] 30 bipolar plate

[0053] 31 , 31 ' Fluid passage opening

[0054] 32 River Field

[0055] 40 Membrane electrode assembly

[0056] 100 electrochemical cells

[0057] 110 cell stacks

[0058] B Width of the groove base

[0059] D1 Diameter of first nozzle opening

[0060] D2 Diameter of second nozzle opening

Claims

Patent claims 1. A method for producing a sealing arrangement (1), comprising the following steps: - Providing a 3D-printed support structure (2) comprising at least one annular groove (3, 3') with a groove base (4) and chamfered groove edges (5a, 5b), - Providing at least one thermoplastic sealing material (6), - heating and liquefying the at least one thermoplastic sealing material (6), - depositing at least one first sealing bead (7a) made of the at least one liquefied sealing material (6) on the groove base (4) of the annular groove (3, 3') by means of at least one first nozzle unit (20) which has a first nozzle opening (20a) with a first diameter (D1) which is less than or equal to a width (B) of the groove base (4) of the annular groove (3, 3').

2. Method according to claim 1, wherein furthermore a deposition of a second sealing bead (7b) made of the at least one liquefied sealing material (6) on the at least one first sealing bead (7a), in particular in the region of the chamfered groove edges (5a, 5b) of the annular groove (3, 3'), by means of at least one second nozzle unit (21).

3. The method according to claim 2, wherein the second nozzle unit (21) has a second nozzle opening (21a) with a second diameter (D2), the second diameter (D2) being smaller than the first diameter (D1) of the first nozzle opening (20).

4. Method according to one of claims 1 to 3, wherein the groove base (4) of the annular groove (3, 3') is covered by the at least one first sealing bead (7a).

5. Method according to one of claims 1 to 4, wherein the second sealing beads (7b) are arranged in the region of the chamfered groove edges (5a, 5b) of the annular groove (3, 3') and spaced apart from one another on the at least one first sealing bead (7a).

6. The method according to claim 5, wherein at least one third sealing bead (7c) is arranged between the second sealing beads (7b).

7. Method according to one of claims 1 to 6, wherein further sealing beads (7d) are deposited on the second sealing beads (7b) and the at least one third sealing bead (7c) by means of at least one third nozzle unit which has a third nozzle opening with a third diameter which is smaller than the diameter (D2) of the second nozzle opening (21a).

8. Method according to one of claims 1 to 7, wherein the at least one first sealing bead (7a), the second sealing beads (7b), the at least one third sealing bead (7c) and the further sealing beads (7d) are formed from at least two different sealing materials (6, 6').

9. Sealing arrangement (1) manufactured according to one of claims 1 to 8, comprising the 3D-printed support structure (2) with the at least one annular groove (3, 3'), which has a groove base (4) and chamfered groove edges (5a, 5b), wherein a seal (10) is located in the annular groove (3, 3'), which is provided by the solidified sealing beads (7a, 7b, 7c, 7d).

10. Sealing arrangement (1) according to claim 9, wherein the groove base (4) of the annular groove (3, 3') is flat or three-dimensionally structured.

11. Component (11) of an electrochemical cell (100), in particular a separator plate or bipolar plate (30), comprising at least one sealing arrangement (1) according to one of claims 9 or 10.

12. Electrochemical cell (100), in particular a fuel cell, an electrolyzer for electrolyzing water, or a redox flow cell, comprising at least one component (11) according to claim 11.

Images