Methods for manufacturing a stack, stack and fuel cell system

Abstract

The invention relates to a method for manufacturing a stack (1) comprising a cell stack (3) arranged between two end plates (2) and consisting of a plurality of electrochemical cells (4). According to the invention, a current collector plate (5) is arranged between the cell stack (3) and at least one of the two end plates (2), the current collector plate having a sleeve-shaped contact element (6) on its side facing away from the cell stack (3), which is guided through an opening (7) of the end plate (2) during assembly. The invention further relates to a stack (1) and a fuel cell system with at least one stack (1) according to the invention.

Description

[0001] The invention relates to a method for manufacturing a stack according to the preamble of claim 1. Furthermore, the invention relates to a stack and a fuel cell system with at least one stack according to the invention. State of the art

[0002] A stack comprises a multitude of electrochemical cells in a stacked arrangement, or a cell stack. The cell stack is positioned between two end plates and clamped to them, for example, using metal tension bands. Typically, a current collector plate with a laterally projecting contact tab for connecting a high-voltage terminal assembly is located on each side between the two end plates and the cell stack. This means that the electrical connections for the electrical power are located at the top and bottom of the cell stack. Since the height of the cell stack can vary, this also applies to the distance between the two terminals, or the distance between the positive and negative terminals.

[0003] Due to the laterally protruding contact tabs, contacting is also done from the side. This has the disadvantage that the current-carrying elements, especially the busbars and length compensation elements including the insulators and holders, significantly increase the stack's footprint. This results in an increased installation space requirement for the stack. Furthermore, assembling a high-voltage connection assembly often proves difficult, particularly when threading the contact tabs. After contacting, all mounting openings must also be tightly sealed again, which is time-consuming and costly.

[0004] The present invention is concerned with the objective of making the production of a stack simpler and more cost-effective.

[0005] To solve the problem, the method with the features of claim 1 is proposed. Advantageous embodiments of the invention are described in the dependent claims. Furthermore, a stack and a fuel cell system with at least one stack according to the invention are specified. Disclosure of the invention

[0006] A method for manufacturing a stack comprising a cell stack of a plurality of electrochemical cells arranged between two end plates is proposed. According to the invention, a current collector plate is arranged between the cell stack and at least one of the two end plates, the current collector plate having a sleeve-shaped contact element on its side facing away from the cell stack, which is guided through an opening in the end plate during assembly.

[0007] Since the sleeve-shaped contact element passes through the end plate, the stack is not contacted from the side, but from above or below, depending on whether it is the upper or lower end plate. This assumes that the stacking direction of the cells is vertical, which is usually the case. If the cell stack, including the end plates, is rotated by 90°, i.e., arranged horizontally, then contact is made laterally, via the side of at least one end plate.

[0008] Contacting the cells via at least one side of the end plate offers the advantage of saving installation space, as the sleeve-shaped contact element replaces the otherwise conventional, laterally protruding contact tab. Unlike the laterally protruding contact tab, the sleeve-shaped contact element is positioned within the surface of the current collector plate, so the base area of ​​the stack is not increased by the sleeve-shaped contact element. Furthermore, the sleeve-shaped contact element is oriented such that it extends essentially parallel to the stacking direction of the cell pack.

[0009] The sleeve-shaped contact element also has the advantage that it can be easily contacted by inserting, plugging in, pressing in, or screwing in another contact element. This simplifies the manufacturing of the stack, which also helps to save costs.

[0010] According to a preferred embodiment of the invention, a threaded sleeve is used as a contact element. In this case, contact is established by screwing in a further contact element. A contact established in this way is particularly robust and therefore less prone to defects.

[0011] Preferably, during the assembly of the end plate, the contact element is guided through the opening of the end plate so that it is flush with the surface of the end plate or protrudes beyond it. This ensures that the contact element is accessible so that it can be contacted from the outside.

[0012] Furthermore, preferably, an insulating plate with an opening is placed on the current collector plate before the end plate is mounted, with the contact element being guided through the opening of the insulating plate. The insulating plate serves to electrically insulate the current collector plate. The opening in the insulating plate facilitates the insertion of the sleeve-shaped contact element of the current collector plate.

[0013] In a further development of the invention, it is proposed that the opening of the insulating plate be framed by a collar, which is pulled over the contact element during assembly of the insulating plate. In this way, not only the current collector plate but also the sleeve-shaped contact element can be electrically insulated. Preferably, the collar has a height that is equal to or greater than the thickness of the end plate. This ensures that the sleeve-shaped contact element does not make contact with the end plate. Alternatively or additionally to the collar, an annular sealing element can be arranged between the sleeve-shaped contact element and the end plate.

[0014] Furthermore, it is proposed that after mounting the end plate into the sleeve-shaped contact element, a fastening element, such as a screw, is inserted, plugged in, pressed in, or screwed into the stack to secure an electrical conductor, in particular a busbar. In this way, the stack can not only be contacted but also simultaneously connected to a power supply.

[0015] Furthermore, a stack for a fuel cell system is proposed. The stack comprises a cell stack consisting of a plurality of electrochemical cells arranged between two end plates. According to the invention, a current collector plate is arranged between the cell stack and at least one of the two end plates, the collector plate having a sleeve-shaped contact element on its side facing away from the cell stack, the contact element being guided through an opening in the end plate.

[0016] The proposed stack can be manufactured, in particular, using the previously described method according to the invention, so that the same advantages can be achieved. In particular, the contacting of the stack can be simplified. The stack can therefore be manufactured simply and cost-effectively.

[0017] Furthermore, it is proposed that the contact element be flush with the end plate or protrude beyond it, so that accessibility of the contact element is ensured.

[0018] According to a preferred embodiment of the invention, the contact element is a threaded sleeve. A screw can then be inserted into the threaded sleeve, by means of which another contact element or an electrical conductor can be attached to the stack. Attachment by means of a screw connection is particularly robust and therefore less prone to failure. The threaded sleeve is preferably firmly connected to the current collector plate, for example by brazing or welding. This further increases the robustness of the connection.

[0019] Preferably, an insulating plate is arranged between the current collector plate and the end plate, and this insulating plate has an opening in the area of ​​the contact element. The opening facilitates the mounting of the insulating plate, as the sleeve-shaped contact element can be easily inserted through the opening when the insulating plate is placed onto the current collector plate. The insulating plate serves to electrically insulate the current collector plate.

[0020] Preferably, the opening of the insulating plate is surrounded by a collar that encircles the contact element and separates it from the end plate. The collar electrically insulates the sleeve-shaped contact element, preferably along its entire length. For this purpose, the collar preferably has a height that is at least equal to the thickness of the end plate.

[0021] In a further development of the invention, it is proposed that a fastening element, for example a screw, for attaching an electrical conductor, in particular a busbar, to the stack is inserted, plugged in, pressed in, or screwed into the contact element. An electrical conductor can be attached to the stack in a simple and robust manner via the fastening element, particularly in the form of a screw. Analogous to the position of the sleeve-shaped contact element at the upper and / or lower end of the stack, the current flow can thus also be routed from the side of the stack upwards and / or downwards, thereby reducing the stack's installation space requirement.

[0022] Since the preferred application area of ​​a stack according to the invention is fuel cell systems, a fuel cell system with at least one stack according to the invention is further proposed. The stack contributes to simplifying the system and saving space and costs.

[0023] The invention and its advantages are explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 a schematic section through a stack according to the invention before contacting and Fig. 2 a schematic section through the stack of Fig. 1 after contacting. Detailed description of the drawings

[0024] Fig. Figure 1 shows a section through a stack 1 according to the invention, which comprises a cell stack 3 made up of a plurality of electrochemical cells 4. The cell stack 3 is arranged between two end plates 2. Since in the Fig. Since only a portion of Stack 1 is shown, specifically in the area of ​​its upper end, only the upper end plate 2 is depicted. However, the lower end of Stack 1 can be designed analogously to the upper end, so the following description of the upper end can also apply to the lower end.

[0025] The Fig. Figure 1 shows that a current collector plate 5 and an insulating plate 8 are arranged between the end plate 2 and the cell stack 3. The current collector plate 5 rests on the cell stack 3 and has a sleeve-shaped contact element 6 on its side facing away from the cell stack 3, which in this case is designed as a threaded sleeve. The insulating plate 8 is arranged between the current collector plate 5 and the end plate 2. In the area of ​​the sleeve-shaped contact element 6, the insulating plate 8 has an opening 9 through which the sleeve-shaped contact element 6 is guided. The opening 9 is surrounded by a collar 10 of the insulating plate 8, so that the sleeve-shaped contact element 6 is electrically insulated by the collar 10. The collar 10, including the sleeve-shaped contact element 6, extends through the end plate 2, which has an opening 7 for this purpose. The current collector plate 5 and the sleeve-shaped contact element 6 therefore do not have contact with the end plate 2.

[0026] Fig. 2 shows stack 1 of the Fig. 1 after electrical contact. The contact is made by means of an electrical conductor 12, which is attached to the sleeve-shaped contact element 6 by a screw 11. The electrical conductor 12 is designed as a busbar.

Claims

[1] Method for producing a stack (1) comprising a cell stack (3) arranged between two end plates (2) from a plurality of electrochemical cells (4), characterized by , that a current collector plate (5) is arranged between the cell stack (3) and at least one of the two end plates (2), which has a sleeve-shaped contact element (6) on its side facing away from the cell stack (3), which is guided through an opening (7) of the end plate (2) during the assembly of the end plate (2). [2] Method according to claim 1, characterized by , that a threaded sleeve is used as a contact element (6). [3] Method according to claim 1 or 2, characterized by , that during the assembly of the end plate (2) the contact element (6) is guided through the opening (7) of the end plate (2) so far that it is flush with the end plate (2) or protrudes beyond it. [4] Method according to any one of the preceding claims, characterized by, that before mounting the end plate (2) on the current collector plate (5) an insulating plate (8) with an opening (9) is placed and the contact element (6) is guided through the opening (9). [5] Method according to claim 4, characterized by that the opening (9) of the insulating plate (8) is enclosed by a collar (10) which is pulled over the contact element (6) during the assembly of the insulating plate (8), wherein preferably the collar (10) has a height which is equal to or greater than a thickness of the end plate (2). [6] Method according to any one of the preceding claims, characterized by , that after the end plate (2) is mounted into the sleeve-shaped contact element (6) a fastening element, for example a screw (11), is inserted, plugged in, pressed in or screwed into the stack (1) for fastening an electrical conductor (12), in particular a busbar. [7] Stack (1) for a fuel cell system comprising a cell stack (3) arranged between two end plates (2) from a plurality of electrochemical cells (4), characterized by , that between the cell stack (3) and at least one of the two end plates (2) a current collector plate (5) is arranged, which on its side facing away from the cell stack (3) has a sleeve-shaped contact element (6) guided through an opening (7) of the end plate (2). [8] Stack (1) according to claim 7, characterized by that the contact element (6) is flush with the end plate (2) or extends beyond it. [9] Stack (1) according to claim 7 or 8, characterized by , that the contact element (6) is a threaded sleeve which is preferably firmly connected to the current collector plate (5), for example by brazing or welding. [10] Stack (1) according to any one of claims 7 to 9, characterized by, that an insulating plate (8) is arranged between the current collector plate (5) and the end plate (2), which has an opening (9) in the area of ​​the contact element (6). [11] Stack (1) according to claim 10, characterized by , that the opening (9) is surrounded by a collar (10) which surrounds the contact element (6) and separates it from the end plate (2). [12] Stack (1) according to any one of claims 7 to 11, characterized by , that a fastening element, for example a screw (11), for fastening an electrical conductor (12), in particular a busbar, to the stack (1) is inserted, plugged in, pressed in or screwed into the contact element (6). [13] Fuel cell system comprising at least one stack (1) according to any one of claims 7 to 12.

Images