Method for manufacturing a sealed fuel cell

Abstract

The invention relates to a method for manufacturing a sealed fuel cell (101) for a fuel cell stack (100), comprising the following steps: 1) providing a cathode side distributor plate (K) and an anode side distributor plate (A); 2) providing a first film web (Bl) for sealing the cathode side distributor plate (K) and a second film web (B2) for sealing the anode side distributor plate (A); 3) punching out a cathode side distributor structure (VK) for the cathode side distributor plate (K) from the first film web (Bl) and an anode side distributor structure (VA) for the anode side distributor plate (A) from the second film web (B2); 4) cutting the first film web (Bl) for manufacturing a first seal (Dl) for the cathode side distributor structure (VK) and cutting the second film web (B2) for manufacturing a second seal (D2) for the anode side distributor structure (VA); 5) placing the first seal (Dl) on the cathode side distributor plate (K) and placing the second seal (D2) on the anode side distributor plate (A); 6) heating the cathode side distributor plate (K) and the anode side distributor plate (A) in order to material lockingly attach, in particular melt, the first seal (Dl) on the cathode side distributor plate (K) and the second seal (D2) on the anode side distributor plate (A).

Description

TECHNICAL FIELD

[0001] The invention relates to a method for manufacturing a sealed fuel cell for a fuel cell stack according to the independent method claim. Furthermore, the invention relates to a corresponding sealed fuel cell according to the independent device claim. BACKGROUND

[0002] Fuel cells are basically known. Fuel cells are usually constructed as a stack of repeating units consisting of a cathode-side distributor plate, an anode-side distributor plate and a membrane electrode unit. The distributor plates together form a bipolar plate. The distributor plates are electrically conductive, but impermeable to gases and ions. The distributor plates distribute the gases over the active faces of the membrane electrode units. The stack consisting of such repeating units are pressed against each other. For a fuel cell stack to function properly, the distributor plates must be sealed against the membrane electrode units. If rubber seals are used for the sealing, these must be mounted on the distributor plates and / or the membrane electrode units or inserted between them. This can be achieved, for example, by injection molding of the seals. However, the seals have tolerances, so that in order to ensure electrical contact in the active faces of the membrane electrode units, the sealing areas must also be pressed together. Here, compromises must be made for sealing and electrical contact. Injection molding of rubber seals can be very laborious and leads to a large amount of waste that cannot be recycled. The seals are usually only injection molded on one of the distributor plates, the other distributor plate is usually only pressed against the sealing face, whereby gases, for example, can slowly move between the distributor plate and the seal. SUMMARY

[0003] According to an aspect, the invention provides a method for manufacturing a sealed fuel cell for a fuel cell stack having the features of the independent method claim. Furthermore, according to a second aspect, the invention provides a corresponding sealed fuel cell having the features of the independent device claim. Further advantages, features and details of the invention result from the dependent claims, the description and the drawings. Here, the described features and details relating to the inventive method of course also apply to the description relating to the inventive fuel cell and vice versa, so that with regard to the beginning and end of the aspects of the invention are mutually quoted or can be mutually quoted.

[0004] The invention provides a method for manufacturing a sealed fuel cell for a fuel cell stack according to the first aspect, comprising the following steps:

[0005] 1) providing a cathode-side distributor plate and an anode-side distributor plate,

[0006] 2) providing a first film web for sealing the cathode-side distributor plate and a second film web for sealing the anode-side distributor plate,

[0007] 3) punching out a cathode-side distributor structure for a cathode-side distributor plate from the first film web and a anode-side distributor structure for an anode-side distributor plate from the second film web,

[0008] 4) cutting the first film web for manufacturing a first seal for the cathode-side distributor structure and cutting the second film web for manufacturing a second seal for the anode-side distributor structure,

[0009] 5) placing the first seal on the cathode-side distributor plate and placing the second seal on the anode-side distributor plate,

[0010] 6) heating the cathode-side distributor plate and the anode-side distributor plate in order to lockingly attach, in particular to melt, the first seal material on the cathode-side distributor plate and to lockingly attach, in particular to melt, the second seal material on the anode-side distributor plate.

[0011] It can be considered within the scope of the present application that the steps of the method according to the present application, in particular steps 4) and 5), are carried out in a pre-defined order or in a modified order or simultaneously.

[0012] In the sense of the present application, the distributor plate can also be referred to as monopolar plate, which abuts against a complementary monopolar plate of a fuel cell on it or against a housing plate when stacking such a sealed fuel cell into a fuel cell stack.

[0013] The fuel cell stack according to the present application can have a plurality of repeating units in the form of a sealed fuel cell according to the present application. The fuel cell stack according to the present application can advantageously be used for mobile applications, for example in motor vehicles, or for stationary applications, for example in power generator devices.

[0014] The fuel cell stack according to the present application is advantageously suitable for fast and cost-effective mass production, in particular for line production.

[0015] Here, the idea of the invention is that active areas and the ports of the corresponding distributor structure are punched out of a preferably thermoplastic film web, such as a polymer film web, such as a PVDF film web, as a strip. The punching waste can advantageously be collected and recycled. Each punched film web is placed on the surface, for example metallic, of the anode-side distributor plate and the cathode-side distributor plate. By applying the corresponding film web and, for example, partially heating the distributor plate, the film web is melted on the distributor plate, at least on the sealing area. The heating of the distributor plate can be achieved, for example, by a heated punch or roller, an infrared emitter and / or an inductive heater and / or even a resistance heater distributor plate. Preferably, a defined heating of the distributor plate can be carried out, so that the film web is only surface-melted when in contact with the corresponding distributor plate and can be pressed against the hot film from behind (cooling side of the film) with, for example, a cooling tool. Within the scope of the invention, each sealing can thus be laminated to the corresponding distributor plate. Within the scope of the invention, the film web can be cut before or after or simultaneously with the placement onto the corresponding distributor plate.

[0016] Subsequently, the distributor plates each with one sealing melt-connected in this way can be stacked with the membrane electrode units, wherein the plates are each placed with the sealing side onto the membrane electrode units. That is, the film side of the distributor plates points towards each other and encloses the membrane electrode units. Possibly, the membrane electrode units can be provided with gas diffusion layers and optionally enclosed or surrounded in so-called gaskets as edge reinforcements. In the region of the membrane electrode units, the stack height can further be adjusted in an advantageous manner. To this end, the sealed fuel cell according to the invention can be briefly reheated in the sealing area, so that the polymer of each sealing can be plasticized. Thus, the fuel cell can be adjusted to the precise spacing dimensions. The softened polymer can thus also enclose the membrane electrode units and / or bond the distributor plates, impregnate the gas diffusion layers on the edge side and / or connect the distributor plates to each other. In this way, the fuel cell can be provided as one individually handleable module unit, which is continuously, completely sealed and free of mechanical stress.

[0017] The connection of such sealed fuel cells into a fuel cell stack can be achieved by the stacking of a plurality of sealed fuel cells according to the invention and the optional appropriate sealing of the distributor plates of the fuel cells on the cooling medium side on top of each other. The sealing there is less critical than in the gas region and creates a lower risk when stacking. Furthermore, it can be considered within the scope of the invention to provide individual support welds on the outer cooling medium side of the distributor plates, which can be used for the positioning and / or material-locked connection of the distributor plates of adjacent fuel cells.

[0018] In other words, the inventive concept is to provide a cost-effective seal as a tape which can also be placed on the edge region in an entire-surface manner if necessary (without port and without active area) and melted there. Tolerance compensation in the stacking direction can advantageously take place by means of the re-melting of the seal. By means of the present invention, a mechanical decoupling between the sealing in the membrane area and the compression of the sealing area can be achieved. By using recyclable thermoplastic polymers, waste can be reduced. As a film web material for cutting out the seal, various polymers, copolymers, multilayer film composites, etc. can be considered. According to a further advantage of the present invention, such a seal in the form of a polymer film can also be installed to uneven substrates in order to seal, for example, inclined surfaces. Thus, the distributor plates can have profiles which engage into one another but are still reliably sealed.

[0019] Furthermore, the present invention can provide in a method for producing a sealed fuel cell that in step 6) the cathode-side distributor plate and the anode-side distributor plate are partially heated, in particular in the area of the first seal and the respective second seal. Thus, the seal material can be attached to the distributor plates lockingly and thus effectively.

[0020] Furthermore, the present invention can provide in a method for producing a sealed fuel cell that in step 6) the cathode-side distributor plate and the anode-side distributor plate are heated by means of, in particular, a heated punch or roller, an infrared emitter and / or an induction heater. In this way, it can be ensured that the seal is effectively and uniformly connected to the distributor plates.

[0021] Furthermore, the present invention can provide in a method for producing a sealed fuel cell that in step 6) the cathode-side distributor plate and the anode-side distributor plate are heated selectively, in particular inductively, without introducing heat into the first seal and respectively into the second seal. In this way, it is possible to melt only the surface layer of the film web which is in contact with the respective distributor plate in order to establish a material-locked connection with the distributor plate and to leave the remaining material of the film web substantially intact in order to provide improved sealing properties.

[0022] Furthermore, the present invention can provide in a method for producing a sealed fuel cell that the method comprises at least one further step of the following steps:

[0023] 7) stacking the cathode-side distributor plate with the attached first seal, the membrane-electrode unit and the anode-side distributor plate with the attached second seal into a sealed fuel cell, wherein the sealing side of the distributor plates is directed in particular towards the membrane-electrode unit,

[0024] 8) heating the cathode-side distributor plate with the attached first sealing and the anode-side distributor plate with the attached second sealing in order to adjust the height of the sealed fuel cell purposefully.

[0025] Thus, the thickness or height of the manufactured sealed fuel cell can be adjusted and / or simply adapted in another step to the desired and / or required thickness or height. By melting the sealing in the stack compound of the membrane electrode unit, the sealing can advantageously surround and reliably seal the membrane electrode unit on the edge side, if necessary with the gas diffusion layers mounted thereon.

[0026] Furthermore, the application can provide in the method for manufacturing a sealed fuel cell that the cathode-side distributor plate and the anode-side distributor plate are provided in step 1) from an electrically and / or thermally conductive material, in particular a metallic material, a carbon material and / or an electrically conductive plastic. In this way, the electron transfer and / or the heat transfer through the distributor plate can be ensured.

[0027] Furthermore, the application can provide in the method for manufacturing a sealed fuel cell that in step 2) the first film web for sealing the cathode-side distributor plate and the second film web for sealing the anode-side distributor plate are provided from a preferably thermoplastic polymer or copolymer, in particular the same in order to simplify the manufacture or different in order to be able to provide separate sealings for the anode side and the cathode side of the fuel cell. Thus, a thermally processable sealing with recyclable waste material can be provided.

[0028] Furthermore, the application can provide in the method for manufacturing a sealed fuel cell that in step 2) the first film web for sealing the cathode-side distributor plate and the second film web for sealing the anode-side distributor plate are provided as extruded films, in particular by screw extrusion, preferably by co-extrusion, for example as a film hose which can be subsequently slit on the edge side or as a film flat web. Thus, a cost-effective and rapid production of the sealing as a strip can be achieved.

[0029] Furthermore, the present application can be provided in terms of a method for manufacturing a sealed fuel cell, wherein in step 2) a first film web for sealing the cathode-side distributor plate and a second film web for sealing the anode-side distributor plate are provided as a multi-layer film, in particular a multi-layer film having a plurality of functional layers, which can for example have different melting temperatures. In this way, the functionality can be expanded within the scope of the film web according to the present application. By means of the different layers of the respective film web, different properties of the seal can advantageously be provided. Thus, an additional layer for melting onto the distributor plate can have a lower melting temperature. A further layer can for example have improved insulating properties, for example for the port region of the distributor layer. A still further layer can for example have improved corrosion resistance, in particular with respect to fuel-containing gases.

[0030] A fuel cell according to the second aspect of the present application is manufactured by means of a method which can be carried out as described above. The same advantages described above in connection with the method according to the present application can be achieved by means of the fuel cell according to the present application. All of these advantages have already been mentioned. The fuel cell according to the present application is sealed stress-free and electrically contacted reliably in an improved manner. BRIEF DESCRIPTION OF DRAWINGS

[0031] The present application and its extensions and advantages are explained in more detail below with reference to the drawings. Herein, the following is schematically shown:

[0032] Figure 1 schematic view of an exemplary fuel cell stack according to the present application,

[0033] Figure 2 schematic flow of a method for attaching a first seal to a cathode-side distributor plate according to the present application,

[0034] Figure 3 schematic flow of a method for attaching a second seal to an anode-side distributor plate according to the present application, and

[0035] Figure 4 schematic flow of a method for stacking fuel cell stacks according to the present application.

[0036] In the different drawings, identical parts of the present application are always provided with identical reference numerals, so that these reference numerals are generally only explained once. DETAILED DESCRIPTION

[0037] Figure 1 A fuel cell stack 100 according to the present application is shown. The fuel cell stack 100 according to the present application can be configured to have a plurality of repeating units stacked in the form of individual fuel cells 101. The fuel cell stack 100 according to the present application can be used for different mobile and stationary applications.

[0038] Figures 2 to 4 For explaining the method according to the invention for manufacturing a sealed fuel cell for a fuel cell stack. The method according to the invention can have the following steps:

[0039] 1) providing a cathode side distributor plate K and an anode side distributor plate A,

[0040] 2) providing (e.g. by extrusion) a first film web Bl for sealing the cathode side distributor plate K and providing (e.g. by extrusion) a second film web B2 for sealing the anode side distributor plate A,

[0041] 3) punching out cathode side distributor structures VK for the cathode side distributor plate K from the first film web Bl and punching out anode side distributor structures VA for the anode side distributor plate A from the second film web B2,

[0042] 4) cutting the first film web Bl for manufacturing first sealings Di for the cathode side distributor structures VK and cutting the second film web B2 for manufacturing second sealings D2 for the anode side distributor structures VK,

[0043] 5) placing the first sealings Di on the cathode side distributor plate K and placing the second sealings D2 on the anode side distributor plate A,

[0044] 6) heating the cathode side distributor plate K and the anode side distributor plate A in order to material lockingly attach, in particular melt, the first sealings Di on the cathode side distributor plate K and the second sealings D2 on the anode side distributor plate A.

[0045] As shown in Figure 2 and Figure 3 , steps 4) and 5) can be carried out in a predefined order or in a modified order or even simultaneously.

[0046] The distributor plates K, A can also be referred to as monopolar plates, which rest with the fuel cells 101 on them or with housing plates GP when stacking such sealed fuel cells 101 into a fuel cell stack 100.

[0047] The manufactured fuel cell stack 100 can have a plurality of repeating units in the form of fuel cells 101 sealed by means of the method according to the invention. The method according to the invention enables a fast and cost-effective mass production, in particular a line production, of fuel cells 101.

[0048] In step 2), for the cathode side (see Figure 2 ) and the anode side (see Figure 3) each one (of the same or separate material), preferably thermoplastic, polymer film web, e.g. in the form of a PVDF film web, is provided as a web Bl, B2 as a tape.

[0049] In step 3), the active areas and ports of each distributor structure VK, VA are punched out of the respective film web Bl, B2. In the context of the present application, the punching waste can be collected and recycled.

[0050] In step 5), each one of the punched-out film webs Bl, B2 is placed on the membrane-side surface of a cathode-side distributor plate K (see Fig. 1) and of an anode-side distributor plate A (see Fig. 2). By applying the film web Bl, B2 in step 5) and, in step 6), preferably partially heating the distributor plates K, A, the respective film web Bl, B2 is melted onto the distributor plate K, A, at least on the sealing area. Figure 2 ) and an anode-side distributor plate A (see Figure 3 ).

[0051] In steps 6) and a further step 8), the heating of the distributor plates K, A can be effected, for example, by not shown heating punches or rollers, infrared emitters and / or inductive heaters and / or even resistive heating of the distributor plates. This is indicated in Figure 2 and 3 and Figure 4 by the symbol Q for heat, T for temperature and I for current.

[0052] Preferably, in the context of the present application, the distributor plates K, A are heated selectively, for example by means of inductive heaters, such that the film web Bl, B2 is only surface-melted when in contact with the respective distributor plate K, A and can be pressed against the hot film surface or layer from behind (the cooled side of the film web Bl, B2) with, for example, a cooling tool. In other words, each seal Dl can be laminated onto the respective distributor plate K, A. The film web Bl, B2 can for this purpose have one or more functional layers which can have different properties in terms of melting temperature, corrosion resistance and / or electrical insulation.

[0053] In step 4), the film web Bl, B2 can be cut before or after or simultaneously with the placement onto the respective distributor plate K, A in step 5.

[0054] As Figure 4Further shown, the sealed distributor plates K, A with one melt- connected sealing D1, D2 each can be stacked with the membrane electrode units MEA in a further possible step 7) to the fuel cell 101, wherein the plates K, A are placed onto the membrane electrode units MEA with the sealing side each. The sealings D1, D2 can frame-like surround the membrane electrode units MEA here. The membrane electrode units MEA can optionally be provided with gas diffusion layers and, if necessary, be enclosed or surrounded in so-called gaskets as edge reinforcements.

[0055] In a further possible step 8), the stack height of the fuel cell 101 can be adjusted and / or adapted in an advantageous manner. To this end, the fuel cells 101 stacked together according to the application can be briefly reheated in the sealing region in step 7) so that the material of the respective sealings D1, D2 can melt. The fuel cells 101 can thus be adjusted to the precise spacing dimensions. The softened material of the sealings D1, D2 can thereby surround the membrane electrode units MEA on the edge side and / or bond with the distributor plates K, A. The optional gas diffusion layers can thus also be impregnated on the edge side. Advantageously, the distributor plates K, A can thus be connected to one another. In this way, the fuel cells 101 can be provided as a completely sealed and mechanically stress-free continuous composite.

[0056] The fuel cell 101 manufactured by means of the method which can be carried out as described above also constitutes an aspect of the present application. A corresponding fuel cell stack 100 with a plurality of such fuel cells 101 can also constitute an aspect of the present application.

[0057] The above description of the figures only describes the application in the context of the embodiments. Of course, the individual features of the embodiments can be freely combined with one another, as far as technically meaningful, without leaving the scope of the application.

Claims

1. A method for manufacturing a sealed fuel cell (101) for a fuel cell stack (100), comprising the following steps: 1) providing a cathode-side distributor plate (K) and an anode-side distributor plate (A), 2) providing a first film web (Bl) for sealing the cathode-side distributor plate (K) and a second film web (B2) for sealing the anode-side distributor plate (A), 3) punching out a cathode-side distributor structure (VK) for the cathode-side distributor plate (K) from the first film web (Bl) and an anode-side distributor structure (VA) for the anode-side distributor plate (A) from the second film web (B2), 4) cutting the first film web (Bl) for manufacturing a first seal (Dl) for the cathode-side distributor structure (VK) and cutting the second film web (B2) for manufacturing a second seal (D2) for the anode-side distributor structure (VA), 5) placing the first seal (Dl) on the cathode-side distributor plate (K) and the second seal (D2) on the anode-side distributor plate (A), 6) heating the cathode-side distributor plate (K) and the anode-side distributor plate (A) in order to material-lockingly attach the first seal (Dl) on the cathode-side distributor plate (K) and the second seal (D2) on the anode-side distributor plate (A).

2. The method according to claim 1, characterized in that in step 6) the cathode-side distributor plate (K) and the anode-side distributor plate (A) are partially heated.

3. The method according to claim 1 or 2, characterized in that in step 6) the cathode-side distributor plate (K) and the anode-side distributor plate (A) are heated by means of a punch or a roller, an infrared emitter and / or an inductive heater.

4. The method according to claim 1 or 2, characterized in that in step 6) the cathode-side distributor plate (K) and the anode-side distributor plate (A) are heated selectively without introducing heat into the first seal (Dl) and, respectively, into the second seal (D2).

5. The method according to claim 1 or 2, characterized in that the method has at least one further step of the following steps: 7) stacking the cathode-side distributor plate (K) with the attached first seal (Dl), a membrane electrode assembly (MEA) and the anode-side distributor plate (A) with the attached second seal (D2) into a sealed fuel cell (101), 8) heating the cathode-side distributor plate (K) with the attached first seal (Dl) and the anode-side distributor plate (A) with the attached second seal (D2) in order to selectively adjust the height of the sealed fuel cell (101).

6. The method according to claim 1 or 2, characterized in that in step 1) the cathode-side distributor plate (K) and the anode-side distributor plate (A) are provided from an electrically and / or thermally conductive material.

7. The method according to claim 1 or 2, characterized in that In step 2) the first film web (B1) for sealing the cathode-side distributor plate (K) and the second film web (B2) for sealing the anode-side distributor plate (A) are provided from a polymer or copolymer.

8. The method according to claim 7, characterized in that In step 2) the first film web (B1) for sealing the cathode-side distributor plate (K) and the second film web (B2) for sealing the anode-side distributor plate (A) are provided as extruded films.

9. The method according to any one of claims 1, 2 and 8, characterized in that In step 2) the first film web (B1) for sealing the cathode-side distributor plate (K) and the second film web (B2) for sealing the anode-side distributor plate (A) are provided as multi-layer films.

10. The method of claim 1, wherein, The cathode-side distributor plate (K) and the anode-side distributor plate (A) are heated in order to melt the first seal (D1) on the cathode-side distributor plate (K) and the second seal (D2) on the anode-side distributor plate (A).

11. The method of claim 2, wherein, The cathode-side distributor plate (K) and the anode-side distributor plate (A) are heated partially in the area of the first seal (D1) and the respective second seal (D2).

12. The method of claim 3, wherein, The cathode-side distributor plate (K) and the anode-side distributor plate (A) are heated by means of heated punches or rollers, infrared emitters and / or inductive heaters.

13. The method of claim 4, wherein, The cathode-side distributor plate (K) and the anode-side distributor plate (A) are inductively heated.

14. The method of claim 6, wherein, The cathode-side distributor plate (K) and the anode-side distributor plate (A) are provided from a metallic material, a carbon material and / or an electrically conductive plastic.

15. The method of claim 7, wherein, The first film web (B1) for sealing the cathode-side distributor plate (K) and the second film web (B2) for sealing the anode-side distributor plate (A) are provided from the same polymer or copolymer.

16. The method of claim 7, wherein, The first film web (B1) for sealing the cathode-side distributor plate (K) and the second film web (B2) for sealing the anode-side distributor plate (A) are provided from a thermoplastic polymer or copolymer.

17. The method of claim 8, wherein, The first film web (B1) for sealing the cathode-side distributor plate (K) and the second film web (B2) for sealing the anode-side distributor plate (A) are provided by screw extrusion as a film hose or film flat web.

18. The method of claim 8, wherein, The first film web (B1) for sealing the cathode-side distributor plate (K) and the second film web (B2) for sealing the anode-side distributor plate (A) are provided by co-extrusion as a film hose or film flat web.

19. The method of claim 9, wherein, The first film web (B1) for sealing the cathode-side distributor plate (K) and the second film web (B2) for sealing the anode-side distributor plate (A) are provided as multi-layer films with a plurality of functional layers.

20. The method of claim 19, wherein, The functional layers have different melting temperatures.

21. A sealed fuel cell (101) for a fuel cell stack (100), produced according to the method according to any one of the preceding claims.

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