Membrane-electrode unit with sealed frame

Abstract

The present invention relates to a unit comprising a device (1) consisting of two gas diffusion electrodes (2,3) sandwiched between which is a membrane (4), the device (1) being tightly connected by a first seal (5) to a frame (6) surrounding the device (1) on its periphery, the frame (6) having two mutually opposed end faces (7,8), the frame (6) having a tubular aperture (9) extending from its first end face (7) to its second end face (8), the aperture (9) being surrounded by second seals (10.1, 10.2, 10.3, ...) on both sides of the end faces of the frame (6) and sealed to each other during normal use of the unit.

Description

[Technical field]

[0001] The invention relates to a unit comprising a device consisting of two gas diffusion electrodes sandwiched between which a membrane is tightly connected by a first seal to a frame surrounding the device on its periphery, the frame having two mutually facing end faces.

[0002] Prior Art Such a unit is known from DE 10 2013 014 083 A1. The unit in question is a membrane-electrode unit. The device is surrounded on its periphery by a frame at a distance, and a seal is arranged in the gap formed by this distance, which seal tightly connects the device to the frame. The membrane-electrode unit is provided for a fuel cell.

[0003] The frame, like the device, is formed in a sandwich shape having two outer frame portions with an inner frame portion disposed between the two outer frame portions.

[0004] The joining of the device and the frame is carried out by applying a pressing process at high temperature. The sealing material of the seal is placed between the outer frame parts in the pressing direction before the pressing process is carried out, thus defining a gap for the device. During the pressing process, the outer frame parts are continuously moved until they abut against the inner frame parts, respectively. The flowable sealing material is then forced into the gap formed by the above-mentioned gap until the gap is sealed and the sealing material penetrates into the border of the device with which it abuts. The membrane-electrode unit is thus formed as a composite of the device and the frame with the seal.

[0005] The membrane-electrode unit is held within the frame by a seal.

[0006] Disclosure of the Invention The object of the present invention is to improve a unit of the type mentioned at the beginning in such a way that the electrochemical cells, in particular fuel cells, which are operated in conjunction with said unit, have a simpler structure and can be manufactured more simply and at lower cost.

[0007] The above object is achieved according to the invention by the features of claim 1. With regard to advantageous configurations, reference is made to the respective claims which directly or indirectly cite claim 1.

[0008] To achieve the above object, a unit is provided comprising a device consisting of two gas diffusion electrodes, a membrane sandwiched between the two gas diffusion electrodes, the device being tightly coupled by a first seal to a frame surrounding the device at its periphery, the frame having two mutually opposing end faces, the frame having a tubular aperture extending from the first end face to the second end face, the aperture being surrounded by a second seal on either side of the end faces of the frame and sealed to each other during normal use of the unit.

[0009] In this case, it is advantageous for the unit to be multifunctional, providing further functions that allow a low-part-count and low-cost construction of the electrochemical cell, for example a fuel cell.

[0010] The unit is configured as a membrane-electrode unit.

[0011] Usually, the membrane-electrode unit must be sealed in an electrochemical cell, for example in a fuel cell, by an additional and separately formed seal, as mentioned at the beginning as being known from the prior art. The production and installation of the seal makes the production of the cell complicated and expensive. Furthermore, an installation error of the further seal may impair the function of the cell.

[0012] These drawbacks are avoided in the unit according to the invention by providing a frame having a conduit-like aperture extending from a first end face to a second end face of the frame, the aperture being surrounded on either side of the end faces of the frame by a second seal.

[0013] The device and the second seal form a pre-assembled unit.

[0014] The apertures in the frame are formed to congruently overlap openings in the bipolar plates adjacent to them on both sides of the end face when the unit is used in a fuel cell, where the openings in the bipolar plates are formed by the inlet and outlet ports for the coolant and the inlet and outlet ports for the gas.

[0015] The aperture and the secondary seal which seals it form an integral part of the unit, thereby making the electrochemical cell low cost and simple to manufacture and install.

[0016] Alternatively, a unit may be provided comprising a device consisting of two gas diffusion layers sandwiched between which is a catalyst coated membrane, the device being intimately connected by a first seal to a frame surrounding the device at its periphery, the frame having two mutually opposing end faces, the frame having a duct-like aperture extending from its first end face to its second end face, the aperture being surrounded by a second seal on either side of the end faces of the frame and sealed to each other during normal use of the unit.

[0017] According to one advantageous configuration, the second seal can be made of an elastomeric sealing material, which is available in many applications and often at low cost.

[0018] At least two of the second seals, and preferably all of them, can be made of a homogeneous material so as to blend together and become one piece, which is advantageous since at least two of the second seals, and preferably all of them, can be manufactured in a single method step, and the one pieceness avoids transitions between adjacent second seals and the associated risk of no seal between the second seals.

[0019] The second seal is moldable.

[0020] The frame is preferably formed in a sandwich shape and has two outer frame parts between which an inner frame part is arranged, such a frame construction having the advantage, as mentioned at the beginning, that the first seal forms a tight bond between the device of the unit and the frame by compression between the outer frame parts.

[0021] The frame structure may be formed from a thermoplastic film material such as, for example, polyester.

[0022] The inner frame portion protrudes beyond the outer frame portion at a periphery, thereby forming a protrusion in the frame, in which the aperture is located.

[0023] The second seal is intimately bonded to the inner frame portion and intimately surrounds the aperture during normal use of the electrochemical cell in which the unit is used.

[0024] In order to achieve a durable, tight bond between the second seal and the inner frame part, the second seal is preferably connected to the inner frame part by a material connection and / or by a form connection. For this purpose, it can be configured that the second seal is integrally injection molded to the inner frame part, whereby a bond by material connection is created.

[0025] The form-fitting between the second seal and the inner frame can be achieved in that the inner frame part has fastening apertures which are penetrated by the sealing material of the second seal during manufacture, which allows for a simple manufacture of the second seal which is located on both sides of the end face of the inner frame part.

[0026] The concepts described above are of significant applicability to fuel cells as well as to electrolysers or redox flow batteries.

[0027] The fuel cell is fed with hydrogen and oxygen, which produces water and energy.

[0028] In response, the electrolyser is supplied with water and energy, which produces hydrogen and oxygen.

[0029] Redox flow batteries process an electrolyte liquid in a chemical reaction (a redox reaction) that provides usable electrical energy.

[0030] In the following, an embodiment of the unit according to the invention will be explained in more detail with reference to the schematic representations of FIGS. [Brief description of the drawings]

[0031] [Figure 1] FIG. 3 is a schematic cross-sectional view showing the membrane-electrode unit of FIG. 2 taken along line AB. [Diagram 2] FIG. 2 is a plan view showing the unit of FIG. 1.

[0032] EMBODIMENTS OF THE PRESENTINVENTION 1 and 2 show an embodiment of a unit according to the invention.

[0033] FIG. 1 shows a cross-sectional view taken along line AB in FIG.

[0034] The unit comprises a device 1 formed from two gas diffusion electrodes 2, 3 and a membrane 4 sandwiched between the gas diffusion electrodes 2, 3. The device 1 is surrounded on its periphery by a frame 6, in which the device 1 is held hermetically within the frame 6 by a first seal 5.

[0035] The frame 6 is made in parts and has two outer frame parts 11, 12 which form the end faces 7, 8. Between the outer frame parts 11, 12 an inner frame part 13 is sandwiched.

[0036] The inner frame part 13 is provided with duct-like apertures 9, each of which is formed to congruently overlap the inlet and outlet of an electrochemical cell, here a bipolar plate (not shown in FIG. 1) of a fuel cell stack. Second seals 10.1, 10.2, 10.3, ... are arranged around the apertures 9, and are made of a uniform material so as to blend together. The second seals 10.1, 10.2, 10.3, ... are arranged on both sides of the end faces of the frame 6 and seal the apertures 9 from each other during normal use of the unit, i.e. when the unit is assembled.

[0037] The inner frame part 13 is provided with fastening apertures 14 which are pierced by the sealing material of the second seals 10.1, 10.2, 10.3, .... This allows, on the one hand, a simple attachment of the second seals 10.1, 10.2, 10.3, ... to both end faces of the frame 6, and, on the other hand, a durable and tight bond of the second seals 10.1, 10.2, 10.3, ... with the inner frame part 13 over a long period of use.

[0038] In Fig. 2 a plan view of the unit of Fig. 1 is shown. The outer frame parts 11, 12 surround the outer periphery of the device 1, with an inner frame part 13, which is arranged between the outer frame parts 11, 12 in the drawing plane, projecting circumferentially beyond the outer frame parts 11, 12. An aperture 9 is arranged in this projection of the inner frame part 13, which is surrounded on both sides of the end faces of the inner frame parts by second seals 10.1, 10.2, 10.3, ... which are formed integrally with one another, as shown in Fig. 1.

Claims

1. A unit comprising a device (1) consisting of two gas diffusion electrodes (2, 3), A membrane (4) is sandwiched between the two gas diffusion electrodes (2, 3), the device (1) being tightly coupled by a first seal (5) to a frame (6) surrounding the device (1) at its periphery; The frame (6) has two end faces (7, 8) facing each other. In the unit, The frame (6) has a tubular aperture (9) extending from a first end surface (7) to a second end surface (8) thereof; The aperture (9) is surrounded by second seals (10.1, 10.2, 10.3, ...) on either side of the end face of the frame (6) and are sealed to each other during normal use of the unit. A unit characterized by:

2. A unit comprising a device (1) consisting of two gas diffusion layers (2, 3), A catalyst-coated membrane (4) is sandwiched between the two gas diffusion layers (2, 3), the device (1) being tightly coupled by a first seal (5) to a frame (6) surrounding the device (1) at its periphery; The frame (6) has two end faces (7, 8) facing each other, The frame (6) has a tubular aperture (9) extending from a first end surface (7) to a second end surface (8) thereof; the aperture (9) is surrounded by second seals (10.1, 10.2, 10.3, ...) on either side of the end face of the frame (6) and are sealed to each other during normal use of the unit; unit.

3. A unit according to claim 1 or 2, characterized in that the second seals (10.1, 10.2, 10.3, ...) consist of an elastomeric sealing material.

4. 4. A unit according to claim 1, wherein at least two of the second seals (10.1, 10.2) are made of a homogeneous material so as to blend together and become one with each other.

5. 5. A unit according to claim 1, wherein all said second seals (10.1, 10.2, 10.3, ...) are made of a homogeneous material so as to blend together as one unit.

6. 3. A unit according to claim 1 or 2, characterized in that the frame (6) is formed in a sandwich shape.

7. 7. A unit according to claim 6, wherein the frame (6) comprises two outer frame parts (11, 12) between which an inner frame part (13) is arranged.

8. A unit according to any one of the preceding claims, wherein the apertures (9) are arranged only in the inner frame part (13).

9. 9. A unit according to any one of the preceding claims, wherein the second seal (10.1, 10.2, 10.3, ...) is tightly connected to the inner frame part (13) and tightly surrounds the aperture (9).

10. 10. The unit according to claim 9, wherein the second seal (10.1, 10.2, 10.3, . . . ) and the inner frame part (13) are connected by a material connection and / or by a form connection.

11. A unit according to any one of claims 7 to 10, characterized in that the inner frame part (13) has a fixing aperture (14) pierced by the sealing material of the second seal (10.1, 10.2, 10.3, ...).

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