Fuel cell stack equipped with compression means

Abstract

The fuel cell consists of multiple assembled cells equipped with end plates at the top and bottom of the cell, which are compressed using an external fixing kit. The end plates are located at the top or bottom of the assembly to separate the compressive force of the active area from the sealant surrounding the cell. The end plates provide degrees of freedom and flexibility to precisely adjust the compressive force on specific areas of the assembly without interfering with other components or the active area.

Description

Technology Field

[0001] Corresponding application

[0002] This application claims priority to Swiss Patent Application No. CH00146 / 19 filed by EH GROUP Engineering SA on February 7, 2019, the contents of which are incorporated herein by reference in their entirety.

[0003] Technology field

[0004] The present invention relates to a fuel cell module and a method for manufacturing and assembling the same. Background Technology

[0005] Summary of Prior Art and Inventions

[0006] Numerous patent applications have been disclosed introducing structures or methods for compressing multilayer stacks and maintaining loads. For example, U.S. Patent Publication No. 2017025701A1 proposes several metal frames that encapsulate a stack from the side to maintain compression during operation. U.S. Patent Publication No. US2018316039A1 discloses designing a novel compression mechanism in which wires wrap around a stack. Various concepts for the same objective are presented in several different applications, such as U.S. Patent Publication No. US2006093890A1, U.S. Patent Publication No. US2008145713A1, U.S. Patent Publication No. US2008311457A1, U.S. Patent Publication No. US2008305380A1, U.S. Patent Publication No. US2002086199, Japanese Patent Publication No. JP2010198861A, Japanese Patent Publication No. JP2012028194A, British Patent Publication No. GB2509152A, U.S. Patent Publication No. US2006046127A1, and International Patent Publication No. W02017131569A1. All of the aforementioned applications feature two end plates at the top and bottom of the stack, and incorporate multiple compression springs that are compressed using an external compression kit between the end plates and the last stack cell. The force applied to the end plates is distributed to the active areas of the cells and the surrounding manifold to minimize contact resistance between the cells and prevent the assembly from leaking.

[0007] The proposed design includes a set of compression mechanisms applied to the assembled stack and simultaneously distributed to the active region and manifold region. However, the key challenge is to have the capability to apply compression independently to the active region and manifold and to precisely adjust the applied force. Depending on the design and materials used, it may be necessary to apply a different compression force to the seals around the active region than to the cell itself. For example, there are sealing materials prepared by injection molding, screen printing, or dispensing, and the required compression force varies depending on the design. The problem to be solved

[0008] The present invention proposes a new solution that overcomes these problems regardless of the design of the external compression kit. means of solving the problem

[0009] One of the main advantages of the present invention is that it provides a method having complete flexibility in an assembly that allows for precise adjustment of the pressure applied to the seal around the active area or battery before assembly.

[0010] Another advantage is that the load applied to the active area can be adjusted after assembly.

[0011] Another advantage is that it helps optimize the thickness of the sealing material, which can simplify the design of the plate in the assembly.

[0012] Another advantage is that it ensures a uniform pressure distribution in the active area, particularly around the edges of the battery closer to the gas manifold.

[0013] In addition, the proposed solution can be used in all types of low-temperature / high-temperature fuel cells, including SOFCs where the pressure applied to the sealant is important, as well as low-temperature fuel cells such as PEMs.

[0014] In one embodiment, the present invention relates to a fuel cell comprising at least one cell having an active region and a manifold region, preferably several such cells, an upper end plate, a lower end plate, an upper cover, and a compression means, wherein the upper end plate comprises a first upper end plate and a second upper end plate.

[0015] In one embodiment, the first upper end plate and / or the second upper end plate may each include a compression means.

[0016] In one embodiment, the first upper end plate can cover the manifold area of ​​the fuel cell.

[0017] In one embodiment, the second upper end plate can cover the active region of the fuel cell.

[0018] In one embodiment, the compression means may include a spring. Other equivalent means are also possible.

[0019] In one embodiment, the springs of the first and second upper end plates may be the same spring or different springs.

[0020] In one embodiment, the fuel cell may further include compression bolts or other equivalent means.

[0021] In one embodiment, the compressive force around the sealant (manifold area) and the active area can be achieved by a dedicated spring of the first upper end plate.

[0022] In one embodiment, the second upper end plate may be left without compression.

[0023] In one embodiment, the fuel cell may further include an external compression means.

[0024] In one embodiment, the external compression means may include belts or rods or other equivalent means.

[0025] In one embodiment, the present invention relates to a fuel cell stack having a proposed compression system and means as described herein.

[0026] In one embodiment, the present invention relates to a fuel cell stack in which the compression force for the active region and the manifold equipped with a sealant may be different.

[0027] In one embodiment, the present invention relates to a fuel cell stack in which the compressive force applied to the sealant may be independent of the compressive force applied to the active region.

[0028] In one embodiment, the present invention relates to a fuel cell stack in which the compressive force on the active region can be adjusted before or after assembly.

[0029] In one embodiment, the present invention relates to a fuel cell stack in which a compression system can be used to cure various sealing materials before or after stack assembly.

[0030] In one embodiment, the present invention relates to a compression system in which heat or pressure can be concentrated only on the sealant surrounding the battery.

[0031] In one embodiment, the present invention relates to a compression system proposed herein that can be integrated into a stack of a cell forming a fuel cell, said stack being compressed by a belt, a rod, a side panel or other configuration or equivalent means.

[0032] In one embodiment, a fuel cell stack assembly equipped with the proposed compression system further comprises at least one of a gas inlet manifold and an outlet manifold that may be located at the bottom, side, or top of the assembly / fuel cell.

[0033] In one embodiment, the compressive force on the active region can be adjusted before or after the assembly of the fuel cell.

[0034] In one embodiment, the compression system may be used to cure (various) sealing materials before or after stack assembly in, for example, in the manifold area.

[0035] In one embodiment, the present invention relates to a compression system defined in the present application that can be used in different types of fuel cells, such as high-temperature or low-temperature operating fuel cells, such as, for example, PEM: proton exchange membrane fuel cell, SOFC: solid oxide fuel cell, DMFC: direct methanol fuel cell, etc.

[0036] In one embodiment, the present invention relates to a product, device, and system comprising at least one fuel cell as described in the present application. Brief explanation of the drawing

[0037] FIG. 1 illustrates an example of a stack assembly equipped with various compression systems: 1a is compressed by external belts. 1b is compressed with external loads. 1c is compressed into side panels. Figure 2 illustrates an example of the compression concept in a stack assembly. FIG. 3 illustrates a stack assembly according to one embodiment of the present invention. FIG. 4 illustrates an example of separate compression springs for the active area and the sealant / manifold area. Figure 5 illustrates an example of compression of the active area. FIG. 6 illustrates an example of a compression spring on an active area and a compression spring on a manifold / sealant area. FIGS. 7A and 7B illustrate an example of a complete assembly of a fuel cell according to one embodiment of the present invention. FIG. 8 illustrates an example of a compression means for a high-temperature fuel cell. FIGS. 9A and 9B illustrate embodiments of a gas supply unit and a manifold for an assembled fuel cell. Specific details for implementing the invention

[0038] FIG. 1 shows a conventional state-of-the-art stack assembly (1) equipped with a compression means. The assembly forming the fuel cell includes a plurality of cells (2) assembled on each other's upper ends, which are encapsulated by two end plates (3, 4) and a cover (5) at the top (plate 3) and bottom (plate 4).

[0039] As described above, there are several techniques for maintaining the assembly in an uncompressed form, and other methods are illustrated in FIG. 1.

[0040] FIG. 1a shows compression using a belt (6) (e.g., US2006093890A1),

[0041] FIG. 1b shows compression using a load (7) and a spring (e.g., US2002110722A155)

[0042] FIG. 1c shows compression using a side panel (8) (e.g., JP2012181996A).

[0043] FIG. 2 illustrates the stack assembly (1) of FIG. 1 in an uncompressed state and an exploded view. The shape and structure of the integrated compression spring (9) for compression may vary depending on the design and application of the fuel cell; however, the main principle of assembly is the same. There are several compression springs (9) on the rod (7) between the upper end plate (3) and the top cover (5), or at the top or bottom of the stack (Fig. 1b). The number of springs (9) and the force applied by the springs are evaluated based on the pressure required for the cell (2). For example, a pressure between 1 and 2 [MPa] may be applied to the surface of the end plates (3, 4). If necessary, or depending on a different distribution, other springs (9) with different compression forces may be used in the center or on the sides of the assembly. In all cases described above, the pressure applied to the stack is distributed to the active area of ​​the cell (2) and its surroundings where the manifold (11) and sealant (12) are placed. If pressure needs to be increased in the sealant / manifold (11, 12) area for any reason, an external compression kit achieves this goal by tightening the area further or using a thicker sealant to compress it further. Those skilled in the art will understand the benefits of increasing pressure on the active area to reduce resistance; however, there are limitations to the extent to which modifications can be made, as excessive compression of the active area can damage or block the channels. Additionally, during the operation of the cell, the stack often thermally expands more than the expansion of the sealing material; consequently, this reduces the compressive force of the sealant, which can lead to leakage in the long term.

[0044] Accordingly, the object of the present invention is to improve known devices and systems. Another object of the present invention is to propose a simple and efficient solution that enables the appropriate compression of fuel cells, assemblies thereof, and similar products.

[0045] Embodiments of the present invention disclose a new design structure (e.g., see FIG. 3 through 9) that overcomes the aforementioned discussions and problems of known fuel cells. In an embodiment of the present invention, the end plates (3, 4) are configured to have a first individual end plate (20) ("external or first upper end plate"), which essentially, preferably, contacts the manifold region (12) and the sealant, and a second end plate (21) ("inner or second upper end plate"), preferably surrounded by the first end plate (20). The second end plate (21) essentially, preferably only contacts the active region (22) of the cell, and thus the current collector (22). Of course, it is also possible to separate the upper end plates into two or more, for example, three or more plates. For example, the second upper end plate may be formed of two plates that are attached to each other or not attached to each other.

[0046] In one embodiment of the present invention, the fuel cell includes compression springs (23, 24) individually positioned on each end plate (20, 21), and the spring (23) is on the plate (20) and the spring (24) is on the plate (21).

[0047] This configuration allows the total force applied to the manifold (sealant) area (12) and the active area (22) to be adjusted based on the number and type of springs (23, 24) used in an independent manner. For example, the total force for the sealant / manifold area (12) can be adjusted to about 2 [MPa], and the total force for the active area (22) can be adjusted to only about 1 [MPa] without interference between the parts (e.g., sealant area). The springs (23) may all have the same characteristics or different characteristics, and the same principle applies to the springs (24) in the active area. The values ​​shown are also non-limiting examples. Another advantage is that the total weight of the assembly can be significantly reduced by designing the embodiments according to the present invention. For example, the upper cover (5) and the two integrated end plates (20, 21) can be manufactured by injection molding of a reinforced plastic that is rigid enough to overcome deformation. The middle plate (21) can be manufactured from a lighter material because it is already encapsulated within the outer frame (i.e., the plate (20)). Of course, other equivalent and suitable materials are also possible.

[0048] Another advantage of the setting according to the embodiment of the present invention is that it provides the possibility to adjust the pressure applied to the active region (22) even after the final assembly of the fuel cell.

[0049] One embodiment is illustrated in FIGS. 5 and 6: Compressive force around the manifold area / sealant area (12) and the active area (22) is achieved by dedicated springs (26, 27) and the top cover (5), and the intermediate end plate (21) is left without compression means. However, several additional compression bolts (25) are added to the top of the end plate (5) to provide compressive force to the intermediate / end plate (21). The bolts (25) are in direct contact with the end plate (21) in the middle, and by tightening them, the compressive force applied to the active area (22) of the fuel cell can be gradually increased depending on the spring used.

[0050] The total applied force can be easily evaluated by the distance the plate (21) moves downward. There are several other methods for evaluating the applied force; for example, using a sensor or pressure-sensitive films or other equivalent means according to an embodiment of the present invention.

[0051] Another advantage of the embodiment of the present invention is that the sealant (12) around the active area (22) (within the manifold area (12)) may require some special treatment for activation; if the sealant is made of a pressure-sensitive material, sufficient pressure must be provided to activate and achieve the best sealing result. This is possible and simple to achieve by the principles of the present invention.

[0052] An embodiment of the present invention provides an opportunity to achieve this goal without applying any force to the active area (22). After obtaining satisfactory force and results in the sealant / manifold area (12), compression of the intermediate section (21) can be applied similarly to that shown in FIGS. 5 and 6. The spring (27) dedicated to the active area (10) is compressed based on the force applied by the bolt (25) of the top cover (5).

[0053] Another advantage of the embodiments of the present invention is that they can be used with various external compression mechanisms; for example (as shown in FIG. 1), belts or rods or other designs. An example in which a compression belt (6) holds all assemblies together and the end plate (20, 21) configuration proposed in the embodiments described herein is integrated inside the stack is shown in FIG. 7. Adding external bolts (25) to the top of the stack is optional, and a person skilled in the art can determine whether such bolts are used, as they can determine whether such flexibility is required during operation.

[0054] Another advantage of the embodiments of the present invention is that they can also be used in fuel cells (1) that operate at higher temperatures, such as SOFCs (solid oxide fuel cells). For example, in an SOFC stack based on a positive electrode supporting cell assembled with a glass sealant, it provides flexibility and reliability regarding the airtightness of the stack.

[0055] The stack can be assembled with a compression mechanism similar to FIG. 1b equipped with an external spring, and the connection rods can be extended to minimize creep and deformation due to high temperature, and additional compression rods can be added in the middle of the end plates (21, 22) to compress the active area at different pressures—an example is shown in FIG. 8. The external connection rods compress the manifold and sealant of the assembly, and the intermediate (single or multiple) connection rods (28) provide compression to the active area (12).

[0056] Embodiments of the present invention do not introduce additional complexity or limitations to the gas supply and manifold (29). Several embodiments are illustrated in FIG. 9. The gas connector (29) (example) may be located at the bottom of the end plate (4) and may be located on the left or right side of the end plate. It may also be integrated into an upper end plate not illustrated herein (e.g., US2008311457A1).

[0057] This description is not intended or interpreted as representing the entire scope and range of the invention. The invention is described at various levels in the accompanying drawings and the detailed description of the invention, and limitations on the scope of the invention are not intended by including or excluding elements, components, etc. Additional aspects of the invention become more readily apparent from the detailed description, particularly when described together with the drawings.

[0058] In addition, exemplary embodiments have been described to provide an overall understanding of the structure, function, manufacturing, and principles of use of the systems and methods disclosed herein. One or more of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the systems and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the invention is not defined solely by the claims. Features illustrated or described in connection with the exemplary embodiments may be combined with features of other embodiments. Such modifications and variations are intended to be included within the scope of the invention. Many problems associated with conventional methods and systems are described herein, and the methods and systems disclosed herein can solve one or more of these problems.

[0059] Describing these matters is not intended to imply knowledge of the art. Those skilled in the art will understand that while specific methods and systems are described herein in connection with embodiments of the invention, the scope of the invention is not limited thereto. Furthermore, although the invention has been described in connection with numerous embodiments, many alternatives, modifications, and variations are or will be obvious to those skilled in the art. Accordingly, it is intended to include all such alternatives, modifications, equivalents, and variations within the spirit and scope of the invention.

Claims

Claim 1 A fuel cell (1) comprising at least one cell (2) having an active region (22), a peripheral region of the active region (22) and a manifold region (12), an upper end plate (3), a lower end plate (4), an upper cover (5), and a compression means (9), wherein the upper end plate (3) includes a first upper end plate (20) covering the peripheral region of the manifold region (12) and the active region (22) and a second upper end plate (21) covering only the active region (22), wherein an independent compression force is applied to the peripheral region of the manifold region (12) and the active region (22) respectively by dedicated springs (23) on the first upper end plate (20), and a second independent compression force is separately applied to the active region (22) by second dedicated springs (24) on the outer surface of the lower part of the second upper end plate (21). Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 In claim 1, the dedicated springs (23) of the first upper end plate (20) are the same as the second dedicated springs (24) of the second upper end plate (21), or the dedicated springs (23) of the first upper end plate (20) are different from the second dedicated springs (24) of the second upper end plate (21), fuel cell (1). Claim 7 In claim 1 or 6, the fuel cell (1) further comprises a compression bolt (25). Claim 8 delete Claim 9 In claim 1 or 6, the fuel cell (1) further comprises external compression means (6). Claim 10 In paragraph 9, the external compression means (6) comprises belts or rods, fuel cell (1). Claim 11 In claim 1 or 6, the fuel cell (1) further comprises one or more of a gas inlet and outlet manifold located at the bottom, side or top of the assembly. Claim 12 In claim 1 or 6, the second compressive force for the active region (22) can be adjusted before or after assembly, fuel cell (1). Claim 13 A fuel cell (1) according to claim 1 or 6 having a seal in a manifold region (12) around an active region (22), wherein the seal is made of a pressure-sensitive curing sealing material that requires sufficient pressure to activate the curing of the sealing material, and a compression system is used to activate the curing of the sealing material before or after stack assembly. Claim 14 In claim 1 or 6, the fuel cell (1) is configured to operate at a high temperature or a low temperature.

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