Method for producing an electrochemical cell and electrochemical cell

Abstract

The invention relates to a method for producing an electrochemical cell (1), in particular a fuel cell or an electrolytic cell, comprising a membrane (2), catalyst layers (3) arranged on both sides of the membrane (2), and a one-piece or multi-piece plastic frame (4) for supporting and / or fixing the membrane (2) in at least one edge region (5). According to the invention, a one-piece or multi-piece metal frame (6) of the same or lower height is arranged around the plastic frame (4). The invention also relates to an electrochemical cell (1), in particular a fuel cell or an electrolytic cell, which can be produced according to the method according to the invention.

Description

Technical Field

[0001] This invention relates to a method for manufacturing an electrochemical cell, and an electrochemical cell, particularly capable of being manufactured according to the proposed method. The electrochemical cell may, in particular, be a fuel cell or an electrolyzer.

[0002] A preferred application area of ​​this invention is fuel cell systems and / or electrolysis systems, wherein the systems include at least one battery stack or group consisting of multiple electrochemical cells. The group may, for example, be a PEM electrolyzer stack or an AEM electrolyzer stack for hydrogen production, or a carbon dioxide electrolyzer. Background Technology

[0003] Electrochemical cells have a multilayer, or multi-site-layer, structure. A core site-layer forms the membrane, followed by catalyst layers on either side of the membrane, constituting the anode and cathode. For this purpose, catalyst material is typically coated on both sides of the membrane. Gas diffusion layers (through which the corresponding reactant gases are transported to the membrane) or porous transport layers (for the input and output of the electrolyte and the output of the corresponding product gases) are arranged on both sides of the catalyst layers. Monopolar or bipolar plates arranged on either side of these layers constitute the final site-layer. The monopolar or bipolar plates are typically imprinted metal plates used to construct dielectric channels, which can extend either parallel or perpendicular to the cell plane. Sealing elements are placed between the various layers to ensure the required dielectric isolation.

[0004] To support the membrane (especially in the surrounding edge regions), a one-piece or two-piece frame can be used as an additional sublayer. This surrounding frame avoids the catalyst layer, which forms the active surface for electrochemical reactions within the battery. If the frame is implemented as a one-piece, it may have surrounding recesses to receive the membrane. If it is a two-piece frame, the membrane is embedded between the two frame sections. The overall height of the frame is typically chosen to allow the monopole or bipole to rest against each other on both sides. The electrical insulation required for the monopole or bipole is achieved by selecting a non-conductive material (especially plastic) for constructing the frame.

[0005] At the latest, when multiple stacked batteries are tightened into a pack, significant pressure is applied to the frame, so a steel frame is typically integrated within the main frame for reinforcement. This integration is usually achieved by injection molding the steel frame with the original frame material (or plastic). However, the different coefficients of thermal expansion of steel and plastic cause localized stresses within the frame during cooling after injection molding. These localized stresses can cause the frame to bend. If this occurs, the dielectric insulation inside the battery is compromised. Furthermore, outward desealing can result. Summary of the Invention

[0006] This invention aims to overcome these drawbacks in manufacturing a stable framework for electrochemical cells. Furthermore, the manufacturing process should be configured as simply and cost-effectively as possible.

[0007] To solve this problem, a method having the features of claim 1 and an electrochemical cell having the features of claim 8 are proposed. Advantageous extensions of the invention are derived from the dependent claims.

[0008] A method is proposed for manufacturing an electrochemical cell (particularly a fuel cell or electrolyzer), the electrochemical cell having a membrane, catalyst layers disposed on both sides of the membrane, and a one-piece or multi-piece plastic frame for supporting and / or securing the membrane in at least one edge region. According to the invention, a one-piece or multi-piece metal frame of the same or lower height is arranged around the plastic frame.

[0009] An external metal frame is used to reinforce the plastic frame. This metal frame replaces the metal core typically integrated within the plastic frame. That is, the frame manufactured according to the method of the invention does not have a metal core, but only an external metal frame surrounding the plastic frame. By eliminating the metal core, problems during injection molding and cooling after injection molding (especially problems related to localized stress patterns) are also eliminated. This reduces the risk of the plastic frame bending and becoming leaky during cooling.

[0010] In the proposed method, the plastic frame and the metal frame are manufactured separately, so that the different coefficients of thermal expansion of plastic and metal will not affect the manufacturing process.

[0011] In an extended embodiment of the invention, a metal frame is proposed to be force-locked and / or form-locked to a plastic frame. Force-locking and / or form-locking optimizes the reinforcing effect of the metal frame because it prevents movement of the plastic frame relative to the metal frame. Force-locking can be achieved, in particular, by clamping the metal frame to the plastic frame. Form-locking can be achieved, for example, by a stepped tenon joint or a keyway joint.

[0012] For force-locking and / or form-locking connections between the metal and plastic frames, it is advantageous to implement the metal frame in multiple parts. Multiple parts can be placed around the plastic frame again and subsequently connected to the plastic frame by clamping or other means. If a form-locking connection is provided between the metal and plastic frames, then the interconnection of the frame parts is sufficient to secure the plastic frame inside the metal frame.

[0013] According to a first preferred embodiment of the invention, the metal frame is made of at least two (preferably at least three) frame portions in the form of individual frames. These frame portions are stacked and connected to each other (preferably by material locking, such as welding). Since the frame portions are each constructed as individual frames, and the individual frames are stacked on top of each other, the metal frame is implemented in multiple layers. In the case of two frame portions, at least one frame portion is provided with a recess into which a plastic frame (preferably a key of the plastic frame) can be placed. A second frame portion is then placed on the first frame portion, securing the plastic frame (preferably a key of the plastic frame) within the recess. In the case of three frame portions, one frame portion can be sized and arranged between two other frame portions such that the centrally located frame portion is recessed relative to the other two and is configured with a groove for receiving the plastic frame (preferably a key of the plastic frame). Although the three-piece embodiment requires the manufacture of one more frame portion, it is simpler to manufacture because no frame portion must have a recess.

[0014] According to a second preferred embodiment of the invention, the metal frame is manufactured from at least two frame portions (preferably two angular frame portions), which are assembled and connected to form a rectangular frame. In this embodiment, when assembling the metal frame, the frame portions are not stacked on top of each other, but rather placed side-by-side; specifically, each of the two angular frame portions wraps around one corner of the plastic frame. The two angular frame portions are then connected (preferably by material locking, such as welding) in the regions of the other two corners of the plastic frame. The two frame portions may each have straight or beveled edges at their two ends, allowing them to be assembled in a flush or beveled manner in the connection area.

[0015] According to a third preferred embodiment of the invention, the metal frame is assembled from a plurality of frame portions in the form of metal strips, which are connected directly or indirectly by at least one flat cover plate (preferably by material locking, such as welding). In this case, at least four frame portions are required for a rectangular frame, and they must be connected to each other. Although the number of frame portions increases, this simplifies the shape and thus simplifies the manufacture of individual frame portions. In principle, only four simple metal strips are sufficient to place and connect them around the plastic frame. Similar to the angular frame portions, the metal strips can be assembled at their ends by flat or bevel joints.

[0016] Advantageously, the metal frame or its frame portions are made by stamping from sheet metal (especially steel or stainless steel). This allows for particularly simple and cost-effective manufacturing of the metal frame or frame portions. To minimize material consumption, multi-piece implementations of the metal frame are preferred. This is because multiple frame portions, whether angular or simply strip-shaped, can be stamped closely side-by-side from sheet metal, thus minimizing waste.

[0017] The plastic frame is preferably manufactured using an injection molding process. This injection molding process is also simple and cost-effective. The plastic frame can be implemented as a one-piece or multi-piece design, wherein the one-piece design offers advantages in terms of battery sealing.

[0018] Furthermore, an electrochemical cell (especially a fuel cell or electrolyzer) is proposed. This cell has a membrane, catalyst layers disposed on both sides of the membrane, and a one-piece or multi-piece plastic frame for supporting and / or fixing the membrane in at least one edge region. According to the invention, a one-piece or multi-piece metal frame having the same or lower height is arranged around the plastic frame.

[0019] The proposed electrochemical cell can be manufactured in particular according to the method described above, thus achieving the same advantages. In particular, the plastic frame can be reinforced by a metal frame without generating undesirable localized stresses in the plastic frame that would lead to bending.

[0020] By using a metal frame with a maximum height equivalent to that of the plastic frame, short circuits between conductive substrates (especially between the two bipolar plates) can be prevented, with the substrates resting against the plastic frame on both sides. Alternatively or supplementarily, at least one sealing element can be arranged between the metal frame and the bipolar plates for electrical insulation.

[0021] Advantageously, the metal frame and the plastic frame are connected by force-locking and / or form-locking, for example, by stepped tenon joints or keyways. For instance, the plastic frame may be constructed with steps, and the metal frame rests at least sectionally on these steps. Alternatively, the plastic frame may be constructed with a key that is received in a recess in the metal frame. The key may have a rectangular, trapezoidal, triangular, or rounded cross-sectional shape. The recess in the metal frame preferably has a corresponding cross-sectional shape.

[0022] Preferably, the metal frame has at least two (preferably at least three) frame portions that are stacked on top of each other and are joined together (preferably by material locking, such as welding). In this embodiment of the metal frame, a groove for receiving the key of the plastic frame can be simply constructed. For example, at least one of the two stacked frame portions (or a single frame) has an aussprung for constructing the groove. The key of the plastic frame can be inserted before the two frame portions are joined. After the two frame portions are joined, the key is secured within the groove.

[0023] According to another preferred embodiment of the invention, the metal frame has at least two frame portions (preferably two angular frame portions) assembled and connected to form a rectangular frame. The two angular frame portions can be manufactured using a stamping process, which is particularly material-saving and thus cost-effective. Furthermore, they are very easily arranged and connected around a plastic frame. In the connection, the frame portions can be clamped to the plastic frame to achieve a force-locked connection between the plastic frame and the metal frame.

[0024] According to another preferred embodiment of the invention, the metal frame is assembled from a plurality of frame portions in the form of metal strips, which are connected directly or indirectly by at least one flat cover plate (preferably by material locking, such as welding). Thus, the rectangular metal frame has at least four metal strips. Each metal strip in this case constitutes one side of the rectangular metal frame. In the connection areas, the metal strips can be assembled by flat joints or bevel joints. Attached Figure Description

[0025] The invention and its advantages will now be described in detail with reference to the accompanying drawings. The drawings show: Figure 1 A schematic cross-section of the first electrochemical cell according to the present invention. Figure 2 A schematic top view of the second electrochemical cell according to the present invention. Figure 3 A schematic cross-section of the third electrochemical cell according to the present invention. Figure 4 A schematic cross-section of a plastic frame with an external metal frame for use in an electrochemical cell according to the present invention. Figure 5 A schematic cross-section of the metal frame used in the electrochemical cell according to the present invention. Figure 6 A schematic cross-section of a multi-piece metal frame used in an electrochemical cell according to the present invention. Figure 7 A schematic cross-section of another multi-piece metal frame for the electrochemical cell according to the invention. Figure 8 A schematic top view of the plastic frame during the assembly of a multi-piece metal frame. Figure 9 A schematic top view of another multi-piece metal frame for the electrochemical cell according to the invention. Detailed Implementation

[0026] Figure 1 The electrochemical cell 1 is visible, comprising a membrane 2 and catalyst layers 3 arranged on both sides of the membrane 2. Currently, the catalyst layers 3 are applied to the membrane 2 and are therefore an integral part of the membrane 2. The membrane 2 is supported on a plastic frame 4 in the edge region 5. The plastic frame is externally encased by a metal frame 6. Bipolar plates 10 are respectively attached to the upper and lower sides of the plastic frame 4. A gas diffusion layer 8 or a porous transport layer 9 (see reference numerals in parentheses) arranged on both sides of the membrane 2 is filled in the intermediate space between the catalyst-coated membrane 2 and the two bipolar plates 10. During operation of the cell 1, the input and output of the medium are achieved through gas channels 11 extending perpendicularly and parallel to the cell plane. For medium isolation within the cell 1, a sealing element 12 is placed between the membrane 2 and the plastic frame 4.

[0027] Figure 2 An exemplary top view of the electrochemical cell 1 is shown, including a plastic frame 4 and a metal frame 6 surrounding the plastic frame 4. A gas channel 11 extending through the plastic frame 4 is also shown.

[0028] exist Figure 1 and Figure 2 In this configuration, the metal frame 6 and the plastic frame 4 are respectively connected to each other by clamping force. Alternatively or supplementarily, the metal frame 6 and the plastic frame 4 may also be connected by a form-locking mechanism. This is illustrated here, for example, with reference to the following figures.

[0029] For example, such as Figure 3 As shown, the plastic frame 4 can construct the steps 13, and the metal frame 6 is placed flat on the steps in sections. Figure 3 In the middle, sealing elements 14 are arranged on both sides of the plastic frame 4. The sealing elements prevent the metal frame 6 from contacting the bipolar plate 10, thereby preventing short circuit.

[0030] Figure 4 Another preferred embodiment for manufacturing the shape-locking between the metal frame 6 and the plastic frame 4 is shown. The metal frame 6 is constructed with a groove 15, in which the key 16 of the plastic frame 4 is received. The groove 15 and the key 16 can be constructed in a circumferential manner to achieve a circumferential shape-locking. Alternatively, the groove 15 or at least the key 16 can be implemented as one or more discontinuous locations, thereby establishing the shape-locking between the metal frame 6 and the plastic frame 4 at at least two locations.

[0031] like Figure 5 As exemplarily shown, in order to construct the groove 15 in the metal frame 6, the metal frame can be implemented as a multi-piece structure. Figure 5 In this design, the metal frame 6 has three frame portions 6.1, 6.2, and 6.3, each forming a single frame. The frame portions 6.1, 6.2, and 6.3 are stacked on top of each other, with the centrally located frame portion 6.2 recessed relative to the other two, thus forming a groove 15. The three frame portions 6.1, 6.2, and 6.3 are connected by welding. Prior to this connection, the key 16 of the plastic frame 4 can be easily inserted.

[0032] Figure 6 Another multi-piece metal frame 6 is visible. This metal frame has only two overlapping frame portions 6.1 and 6.2 for constructing the groove 15. These two overlapping frame portions 6.1 and 6.2 each have a recess, which together form the groove 15. Here, the groove 15 is triangular in cross-section. Other cross-sectional shapes can also be achieved in this way. Alternatively, only one frame portion 6.1 or 6.2 may have a recess for forming the groove 15.

[0033] Figure 7 and Figure 8 As can be seen, the multi-piece metal frame 6 is not stacked on top of each other, but arranged side by side. This embodiment is particularly suitable for constructing a force-locking connection between the metal frame 6 and the plastic frame 4 by clamping. The frame parts can be brought closer to the plastic frame 4 from the side and then clamped to the plastic frame 4 (see...). Figure 7 Arrow F in the image.

[0034] exist Figure 7 In the example, the metal frame 6 has two angular frame portions 6.4 and 6.5, which are positioned around and pressed against the plastic frame 4. All parts are secured to each other by welding the two frame portions 6.4 and 6.5. Due to the angular shape of the frame portions 6.4 and 6.5, the frame portions must be joined at only two locations.

[0035] exist Figure 8 In the example, the metal frame 6 has four frame portions 6.6 in the form of metal strips, similar to the aforementioned angular frame portions 6.4 and 6.5. These four frame portions are placed, clamped, and connected (e.g., welded) around the plastic frame 4. Four welds 17 need to be created here.

[0036] Alternatively, the metal strip, or frame portion 6.6, can be connected via a flat cover plate 7. This embodiment is exemplified in... Figure 9As shown in the diagram. In this case, the cover plate 7 is welded to the metal strip or the frame portion 6.6. Figure 9 As shown in the example, different connection methods can also be combined. For example, a force lock can be established between the metal frame 6 and the plastic frame 4 by clamping (see arrow F). To establish an additional form lock, the plastic frame 4 can be constructed with a step 13, on which the metal frame 6 rests flat.

Claims

1. A method for manufacturing an electrochemical cell (1), particularly a fuel cell or electrolyzer, the electrochemical cell having a membrane (2), a catalyst layer (3) disposed on both sides of the membrane (2), and a one-piece or multi-piece plastic frame (4) for supporting and / or fixing the membrane (2) in at least one edge region (5). Its features are, A one-piece or multi-piece metal frame (6) of the same or lower height is arranged around the plastic frame (4).

2. The method according to claim 1, Its features are, The metal frame (6) is force-locked and / or form-locked to the plastic frame (4), for example by step tenon or keyway connection.

3. The method according to claim 1 or 2, Its features are, The metal frame (6) is made of at least two, preferably at least three frame parts (6.1, 6.2, 6.3) in the form of a single frame, the frame parts being stacked and connected to each other, preferably by material locking, such as welding.

4. The method according to claim 1 or 2, Its features are, The metal frame (6) is made of at least two frame parts (6.4, 6.5), preferably two angular frame parts (6.4, 6.5), which are assembled and connected to form a rectangular frame.

5. The method according to claim 1 or 2, Its features are, The metal frame (6) is assembled from a plurality of frame parts (6.6) in the form of metal strips, which are connected directly or indirectly by at least one flat cover plate (7), preferably by material locking, such as welding.

6. The method according to any one of the preceding claims, Its features are, The metal frame (6) or its frame portions (6.1, 6.2, 6.3, 6.4, 6.5, 6.6) are made of sheet metal, particularly of steel or stainless steel sheet by stamping.

7. The method according to any one of the preceding claims, Its features are, The plastic frame (4) is manufactured by injection molding.

8. An electrochemical cell (1), particularly a fuel cell or electrolyzer, having a membrane (2), a catalyst layer (3) disposed on both sides of the membrane (2), and a one-piece or multi-piece plastic frame (4) for supporting and / or fixing the membrane (2) in at least one edge region (5). Its features are, A one-piece or multi-piece metal frame (6) of the same or lower height is arranged around the plastic frame (4).

9. The electrochemical cell (1) according to claim 8. Its features are, The metal frame (6) is force-locked and / or form-locked to the plastic frame (4), for example by step tenon or keyway connection.

10. The electrochemical cell (1) according to claim 8 or 9. Its features are, The metal frame (6) has at least two, preferably at least three frame portions (6.1, 6.2, 6.3) in the form of individual frames stacked on top of each other, the frame portions being connected, preferably by material locking, such as by welding.

11. The electrochemical cell (1) according to claim 8 or 9. Its features are, The metal frame (6) has at least two frame parts (6.4, 6.5), preferably two angular frame parts (6.4, 6.5), which are assembled and connected to form a rectangular frame.

12. The electrochemical cell (1) according to claim 8 or 9. Its features are, The metal frame (6) is assembled from a plurality of frame parts (6.6) in the form of metal strips, which are connected directly or indirectly by at least one flat cover plate (7), preferably by material locking, such as welding.

Images