WO2024146733A2

WO2024146733A2 - Bipolar plate for an electrolyzer

Info

Publication number: WO2024146733A2
Application number: PCT/EP2023/084444
Authority: WO
Inventors: Matthias Brunner
Original assignee: Robert Bosch Gmbh
Priority date: 2023-01-05
Filing date: 2023-12-06
Publication date: 2024-07-11
Also published as: DE102023200079A1; WO2024146733A3

Abstract

The invention relates to a bipolar plate (34) for an electrolyzer (44). The bipolar plate (34) comprises multiple media channels (36), i.e. at least one H2O inlet port (38), an H2O-/O2 outlet port (40), and an H2 outlet port (42). Bipolar plates (34), in the form of repeating components (48), are arranged in the electrolysis cell stack (46) of the electrolyzer (44) one over the other, each of which is arranged so as to seal a port (38, 40, 42), such that an insert seal (56) is fixed on an X/Y plane (86) between two respective bipolar plates (34) lying one over the other by means of the bipolar plates. The invention additionally relates to the use of the bipolar plate (34) in an electrolysis cell stack (46) of an electrolyzer (44).

Description

Bipolar plate for an electrolyzer

Technical area

The invention relates to a bipolar plate for an electrolyzer, wherein the bipolar plate comprises a plurality of media channels, at least one FhO inlet port, one FhO'/Ch outlet port and one Fh outlet port. Furthermore, the invention relates to the use of the bipolar plate in a fuel cell stack of an electrolyzer.

State of the art

DE 2020 215 012 A1 relates to a bipolar plate for an electrochemical cell, comprising at least one port, an active surface and a sealing element with exactly one opening for the passage of at least one medium. The sealing element surrounds the at least one port. In addition, an electrochemical cell and a method for operating an electrochemical cell are disclosed.

DE 101 58 772 C1 and DE 102 48 531 B4 relate to fuel cell stacks with a layering of several fuel cells, whereby media are supplied or removed through bipolar plates and bead arrangements are provided for sealing.

In contrast to bipolar plates used in fuel cells, bipolar plates for electrolyzers can also have only a single sheet if only two media, namely an anode medium and a cathode medium, have to be separated from each other. In electrolyzers, this is usually not necessary. the cooling medium. The cooling function in electrolyzers is taken over by water, ie the anode medium which is created during water electrolysis.

Description of the invention

A bipolar plate for an electrolyzer is proposed, wherein the bipolar plate comprises several media channels, at least one FhO inlet port, one FhO'/Ch outlet port and one Fh outlet port. Within the cell stack of the electrolyzer, the bipolar plates are arranged one on top of the other as repeating components, sealingly accommodate a port and an insert seal between two bipolar plates lying one on top of the other is fixed by these within an X/Y plane.

The solution proposed according to the invention makes it possible to provide a bipolar plate which can be used multiple times as a repeat component within a cell stack and which, due to its shape, simultaneously produces the contour of the bipolar plate on the anode side as well as the corresponding contour on the cathode side of the bipolar plate.

In an advantageous development of the bipolar plate proposed according to the invention, a membrane or a subgasket is fixed in the Z direction between the insert seal and the bipolar plate in such a way that openings of the insert seal are open in the region of the ports.

In the bipolar plate proposed according to the invention, the membrane is positioned essentially in a central arrangement within a distribution area of the bipolar plate within the cell stack. This advantageously makes it possible to create cathode and anode spaces of approximately equal size.

In an advantageous development of the bipolar plate proposed according to the invention, gas or fluid diffusion layers can be arranged in an anode chamber and/or in a cathode chamber between electrolysis cells formed from superimposed bipolar plates. In the bipolar plate proposed according to the invention, it is manufactured as a repeat component, in particular as an embossed or stamped metallic component, in particular as a sheet metal component. This enables large-scale production, in particular if the bipolar plate can be manufactured as an embossed sheet metal component with a small thickness.

In an advantageous development of the bipolar plate proposed according to the invention, it has at least one first X/Y support elevation and at least one Z support elevation on its upper side. Furthermore, the bipolar plate comprises at least one second X/Y support elevation and at least one second Z support elevation on its lower side.

If a component is arranged multiple times within a fuel cell stack of an electrolyzer through such a design of the bipolar plate, stacking aids can be provided so that the cell stack can be constructed more easily and more precisely, even in an automated manner. After inserting the insert seal and arranging the membrane or subgasket, the anode and cathode spaces are defined via the first and second X/Y support elevations and the first and second Z support elevations, without any additional alignment or joining elements being required when constructing the cell stack.

In an advantageous embodiment of the bipolar plate proposed according to the invention, the at least one X/Y support elevation, the at least one first Z support elevation, the at least one second X/Y support elevation and the at least one second Z support elevation are designed as sheet metal beads in the material of the bipolar plate.

In one embodiment of the bipolar plate, the at least one first X/Y support elevation, the at least one first Z support elevation on the top side and the at least one second X/Y support elevation and the at least one second Z support elevation on the bottom side of the bipolar plate can be designed to run continuously in the circumferential direction in the region of the ports, or in a further embodiment, the support elevations mentioned can also be designed to be interrupted in segments in the circumferential direction. In the bipolar plate proposed according to the invention, the openings in the material of the insert seal are oriented essentially in a horizontal direction and can be designed either as bores or as transverse slots.

In the bipolar plate proposed according to the invention, the membrane or the subgasket surrounding the membrane is clamped between the insert seal on the one hand and an upper side of the bipolar plate on the other. Therefore, no separate joining elements are required to fix the membrane or the subgasket surrounding the membrane.

In the bipolar plate proposed according to the invention, the membrane or the subgasket enclosing the membrane is arranged in a central arrangement between two bipolar plates lying one above the other by means of the at least one X/Y support elevation. This arrangement achieves essentially identical geometries in the anode and cathode compartments of the fuel cell within a single fuel cell within the electrolyzer.

In the bipolar plate proposed according to the invention, the at least one second X/Y support elevation is arranged offset from the first X/Y support elevation, wherein the first X/Y support elevation extends in the opposite Z direction.

In the bipolar plate proposed according to the invention, the at least one X/Y support elevation establishes a defined cathode-side distance of the membrane or the subgasket from the bipolar plate, while the at least one second X/Y support elevation establishes a defined anode-side distance of the membrane or the subgasket from the bipolar plate.

Furthermore, the invention relates to the use of the bipolar plate in a cell stack, in particular an electrolyzer. Advantages of the invention

The solution proposed according to the invention in the form of the bipolar plate provides a single repeating unit, so that only one type of bipolar plate is required as the only repeating component for a fuel cell stack, in particular an electrolyzer. The bipolar plate proposed according to the invention, designed as a repeating unit, creates both the contour of the bipolar plate on the anode side and the associated negative contour of the bipolar plate on the cathode side using one component. In the bipolar plate proposed according to the invention, for example, an FhO inlet is sealed by the insert seal. This also serves here to transmit the force of the bipolar plates forming the cell stack by means of a clamping device. The insert seal is supported here by means of a first X/Y support elevation, for example designed as a sheet metal bead. The first X/Y support elevation does not necessarily have to be formed over the entire circumference of the H2O inlet port to be sealed, but can also be made, for example, from individual segments with interruptions between them. The first X/Y support elevation, for example designed as a sheet metal bead, also serves to align the bipolar plate when pre-stacking the individual bipolar plates, which ultimately form the fuel cell stack.

In addition, the bipolar plate can have a second support elevation that is formed in the opposite Z direction in relation to the first X/Y support elevation of the bipolar plate. The insert seal can be clamped by the first and second X/Y support elevations mentioned. If the bipolar plate proposed according to the invention is provided with the second X/Y support elevation, designed as a sheet metal bead, the fuel cell stack is preferably constructed using the first X/Y support elevation and the second X/Y support elevation as alignment features during pre-stacking.

Depending on which of the ports of the bipolar plate is to be sealed, the insert seal is provided with openings that run horizontally to the anode or cathode of the fuel cell to be supplied. These openings can be designed as holes or as transverse slots, for example. Furthermore, the bipolar plate proposed according to the invention, designed as a repeating component, is advantageously provided with at least one first Z-support elevation and at least one second Z-support elevation. The support elevations mentioned, which extend in the Z direction and in the Z direction opposite to this, allow a central arrangement of the bipolar plate. In this case, the resulting anode and cathode spaces are advantageously of the same shape. The first Z-support elevation can be used to create a defined cathode-side distance between the membrane or the subgasket surrounding the membrane and the bipolar plate, while the second Z-support elevation in the form of a support bead can be used to create a defined anode-side distance between the membrane or the subgasket surrounding the membrane and the bipolar plate.

The bipolar plate proposed according to the invention represents a component which is installed in a fuel cell stack with provision of the membrane or the subgasket that accommodates the membrane and the insert seal. The bipolar plates are arranged in a repeatable manner, taking into account the positive or negative geometries on the anode or cathode side, respectively, with a substantially constant sheet thickness. In particular, the bipolar plate proposed according to the invention is made of metallic material and preferably comprises a thin-walled sheet. Since the media channels can be made from this material as punched-outs with a square or circular cross-section, the said support elevations can be formed as beads, in particular as sheet metal beads, in the material of the bipolar plate.

Short description of the drawings

Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

Show it:

Figure 1 shows a known insert seal as used for a cell stack in electrolysis cells, Figure 2 a bipolar plate in plan view with three ports, an H2O inlet port, an FhO outlet port and an Fh outlet port,

Figure 3 shows a section of an electrolysis cell stack of an electrolyzer with repeat components and a bipolar plate designed as repeat components and

Figure 4 shows a variant of the bipolar plate with a circumferential perimeter bead.

Figure 1 shows the schematic representation of a port 12 which is surrounded by a sealing element 10. An insert part 16 with a support structure 18 is arranged in an opening 14, wherein the support structure 18 is designed, for example, as a corrugated sheet 20 and supports a web 22 of the sealing element 10. Reference numeral 24 designates a medium which passes through the port 12 shown in perspective in Figure 1.

Embodiments of the invention

In the following description of the embodiments of the invention, identical or similar elements are designated by identical reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only represent the subject matter of the invention schematically.

Figure 2 shows a schematic top view of an embodiment of the bipolar plate 34 according to the invention intended for an electrolyzer, with a FhO inlet port 38, a FhO/Ch outlet port 40 and a Fh outlet port 42. From the top view according to Figure 2 it can be seen that a bipolar plate 34 proposed according to the invention has a number of media channels 36. The media channels 36 are designed, for example, as a H2O inlet port 38, a FhO/Ch outlet port 40 and a Fh outlet port 42. Although in the illustration according to Figure 2 all media channels 36 have a substantially rectangular or square cross-section, the cross-sections of the media channels 36 can deviate from the Representation according to Figure 2 can also be manufactured in a circular geometry, for example. The bipolar plate 34 shown in the plan view according to Figure 2 is a thin-walled sheet metal component which can be easily formed by embossing and punching processes and which, according to the invention, serves as a repeat component 48 for stacking on top of one another and for building an electrolysis cell stack 46 for an electrolyzer 44.

Figure 3 shows a section of an electrolysis cell stack 46 of an electrolyzer 44 with bipolar plates 34 made of metallic material, which are designed as repeating components 48 and have a membrane electrode unit in the form of a membrane 70 surrounded by a subgasket.

According to the illustration in Figure 3, a FhO inlet port 38 is shown in section. A number of bipolar plates 34 according to the invention, designed as repeating components 48, are arranged around this port within the electrolysis cell stack 46, one above the other. Insert seals 56 are located between the individual bipolar plates 34 of the electrolysis cell stack 46 as shown in Figure 3. The insert seals 56 are provided on their side facing a distribution area 62 with an opening 60 oriented essentially in a horizontal direction. The opening 60 can be designed either as a bore or as a transverse slot or the like.

From the illustration according to Figure 3 it is also clear that the FhO inlet port 38 shown here in section is designed symmetrically with respect to an axis of symmetry 50. A flow direction of H2O through the FhO inlet port 38 is identified in Figure 3 by reference numeral 52. The electrolysis cell stack 46, only a part of which is shown in the illustration according to Figure 3, is compressed by the application of a clamping force 54. The clamping force 54 is partially transmitted by the insert seals 56. The insert seal 56 is essentially designed in the form of a ring 58 in the illustration according to Figure 3 and serves as the transmission point of the clamping force 54 with which the bipolar plates 34 forming the electrolysis cell stack 46 are clamped against one another.

The openings 60 formed in the wall of the insert seal 56, preferably in ring shape 58, open into a distribution area 62, to which a Active region 64 of the bipolar plates 34, which may be enclosed by a subgasket not shown in detail here.

The individual bipolar plates 34, designed as repeating components 48, are arranged essentially one above the other in the electrolysis cell stack 46. The upper sides 80 and lower sides 82 of the bipolar plates 34 form anode chambers 66 and cathode chambers 68, respectively. These, in turn, are separated from one another by the membrane 70 of the membrane-electrode unit, which is enclosed by a subgasket.

The bipolar plates 34 are preferably stamped or embossed as sheet metal components and are designed as repeating components 48. From the illustration according to Figure 3 it can be seen that at least one first X/Y support elevation 72 and at least one first Z support elevation 76 are formed on the upper side 80 of the bipolar plates 34. The support elevations 72, 76 can be embossed or punched into the material of the bipolar plates 34, for example, as sheet metal beads. On the underside 82 of the bipolar plates 34 as shown in Figure 3 there is at least one second X/Y support elevation 74 and at least one second Z support elevation 78. The membrane 70 of the membrane electrode unit including subgasket is fixed between the insert seal 56 and the bipolar plate 34 in the Z direction 84 as shown in Figure 3 in such a way that it exposes the openings 60 in the insert seal 56 in the area of the H2O inlet port 38 shown here and runs within the distribution area 62 in a central arrangement 90 between two bipolar plates 34 lying one above the other. In the case of the bipolar plates 34, as shown in Figure 3, the insert seal 56 is arranged between two bipolar plates 34 stacked on top of one another within the electrolysis cell stack 46 in such a way that they surround the FhO inlet port 38 and the insert seal 56 is fixed by one or both bipolar plates 34 within an X/Y plane 86. No further joining or holding elements are required to fix the insert seal 56. The joining of the insert seal 56 between the two bipolar plates 34 takes place with the aid of the clamping force 54 acting on the bipolar plates 34 within the electrolysis cell stack 46.

The insert seal 56 between two superimposed bipolar plates 34 also serves to transmit force, in particular to transmit the clamping force 54 for clamping the electrolysis cell stack 46. The insert seal 56 is mounted in the X/Y plane 86 by means of the at least one first X/Y support elevation 72. The at least one first X/Y support elevation 72 does not necessarily have to extend around the entire circumference of the FhO inlet port 38 shown here as an example, but can also be constructed in segments and have interruptions, for example. The at least one first X/Y support elevation 72 is preferably used to align the bipolar plate 34 when stacking the individual components of the electrolysis cell stack 46.

The bipolar plate 34 proposed according to the invention further comprises a second X/Y support elevation 74. The two support elevations 72, 74 mentioned clamp the insert seal 56 between the two bipolar plates 34 without the need for fastening elements. The at least one second X/Y support elevation 74, which extends in the opposite Z direction 92, does not have to run over the entire circumference of the H2O inlet port 38 shown here as an example, but can be designed in segments, i.e. with interruptions in the circumferential direction. If the bipolar plate 34 proposed according to the invention comprises said at least one second X/Y support elevation 74, the electrolysis cell stack 46 is pre-stacked and fully stacked using the at least one first X/Y support elevation 72 and the at least one second X/Y support elevation 74 as an alignment orientation.

As can also be seen from the illustration in Figure 3, a membrane 70 or a membrane electrode unit (or within the distribution area 62, its subgasket) is arranged between the individual bipolar plates 34 stacked on top of one another. The subgasket enclosing the membrane 70 is preferably clamped between the insert seal 56 and the bipolar plates 34. In this case, the bipolar plate 34 proposed according to the invention has at least one first Z-support elevation 76 which extends in the Z direction 84. The membrane 70 is aligned on this in a central arrangement 90 between two bipolar plates 34 lying one above the other. In a particularly preferred embodiment, the bipolar plate 34 proposed according to the invention is provided with at least one further second Z-support elevation 78 which is offset in the X/Y direction 86 to the first. This at least one second Z-support elevation 78 has opposite Z- Direction 92 with respect to the first mentioned, at least a first Z-support elevation 76.

In the sectional view according to Figure 3, which shows a section of the electrolysis cell stack 46 of the electrolyzer 44, the at least one first Z-support elevation 76 establishes a defined cathode-side distance of the membrane 70 from the bipolar plate 34, while the second, extending in the opposite Z-direction 92, at least one second Z-support elevation 78 establishes a defined anode-side distance of the membrane 70 or of its subgaskets from the bipolar plate 34.

In order to ensure a media supply to the active region 64 of the individual electrolysis cells 30 within the electrolysis cell stack 46 of the electrolyzer 44, the at least one first Z-support elevation 76 can be designed to run all the way around the FhO inlet port 38 shown here, whereas the at least one second Z-support elevation 78 does not have to run all the way around in order to ensure said media supply.

The bipolar plates 34 shown stacked on top of one another in Figure 3 are all arranged in a repeatable manner, with appropriate consideration of the positive and negative geometries on the anode and cathode sides, respectively, with a constant predetermined sheet thickness of the bipolar plates 34. The designs described above are therefore particularly advantageous for bipolar plates 34 made of metallic material, which are made from only one sheet. Said media channels 36 and the mentioned support elevations 72, 74, 76, 78 can be produced on the top and bottom 80, 82 of the bipolar plates 34 in a preferred embodiment by means of an embossing or punching process as part of sheet metal processing on a large scale.

The bipolar plate 34 described above is used as a repeating component 48 within an electrolyzer 44 and forms a contour on the anode side and on the opposite side the corresponding negative contour on the cathode side. The membranes 70 arranged in the electrolysis cell stack 46 as part of a membrane electrode unit form the respective anode chambers 66 and the Cathode compartments 68 of the individual electrolysis cells 30 are separated from one another in the stack arrangement.

The illustration in Figure 4 shows a schematic representation of a bipolar plate 34 which has three media channels 36, namely the H2O inlet port 38, the FhO/Ch outlet port 40 and the Fh outlet port 42. Furthermore, the bipolar plate 34 according to the illustration in Figure 4 has a perimeter bead 94 which extends around the active area 64 and seals it. The perimeter bead 94 can also take over part of the sealing of the respective media channels 36 or the H2O inlet port 38, the FhO/Ch outlet port 40 and the Fh outlet port 42. The insert seal 56 according to the illustration in Figure 3 can therefore also be used as a perimeter bead 94. Furthermore, the bipolar plate 34 shown in the illustration according to Figure 4 can, analogously to the illustration according to Figure 3, be supported within the X/Y plane 86 by means of the at least one first X/Y support elevation 72 and the at least one second X/Y support elevation 74. To support the membrane 70 or the membrane electrode unit, the at least one first Z support elevation 76 and the at least one second Z support elevation 78 already described in connection with Figure 3 can also be formed on the top or bottom side 80, 82 of the bipolar plate 34.

The bipolar plate 34 proposed according to the invention can advantageously be used in the electrolysis cell stack 46 for an electrolyzer 44. Advantageously, only bipolar plates 34 and membranes 70 or membrane electrode units, optionally surrounded by subgaskets, as well as insert seals 56 or optionally perimeter beads 94, are used as components. The resulting electrolysis cell stack 46 is compressed by the clamping force 54, so that the bipolar plates 34 are each sealed against one another in a media-tight manner by means of the insert seal 56 or the perimeter bead 94.

The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, a large number of modifications are possible within the scope specified by the claims, which are within the scope of expert action.

Claims

Expectations

1. Bipolar plate (34) for an electrolyzer (44), the bipolar plate (34) comprising a plurality of media channels (36), at least one FhO inlet port (38), one FhO'/Ch outlet port (40) and one Fh outlet port (42), characterized in that in the electrolysis cell stack (46) of the electrolyzer (44), bipolar plates (34) designed as repeating parts (48) are sealingly received on top of ports (38, 40, 42) and an insert seal (56) between each two superimposed bipolar plates (34) is fixed by these in an X/Y plane (86).

2. Bipolar plate (34) according to claim 1, characterized in that a membrane (70) is fixed in the Z direction (84) between the insert seal (56) and the bipolar plate (34) in such a way that openings (60) of the insert seal (56) are open in the region of the ports (38, 40, 42).

3. Bipolar plate (34) according to claim 2, characterized in that the membrane (70) is positioned in a central arrangement (90) within a distribution region (62) of the bipolar plate (34) in the electrolysis cell stack (46).

4. Bipolar plate (34) according to claims 1 to 3, characterized in that fluid diffusion layers are arranged in an anode chamber (66) and/or a cathode chamber (68) in the electrolysis cell (30) formed by two superimposed bipolar plates (34), in particular a PEM or AEM electrolysis cell.

5. Bipolar plate (34) according to claims 1 to 4, characterized in that the bipolar plates (34) are manufactured as repeating components (48) and as embossed or stamped metallic components, in particular sheet metal components.

6. Bipolar plate (34) according to claims 1 to 5, characterized in that the bipolar plate (34) has on its upper side (80) at least one first X/Y support elevation (72) and at least one first Z support elevation (76).

7. Bipolar plate (34) according to claims 1 to 6, characterized in that the bipolar plate (34) has at least one second X/Y support elevation (74) and at least one second Z support elevation (78) on its underside (82).

8. Bipolar plate (34) according to claims 6 and 7, characterized in that the at least one first X/Y support elevation (72), the at least one first Z support elevation (76), the at least one second X/Y support elevation (74) and the at least one second Z support elevation (78) are designed as sheet metal beads in the material of the bipolar plate (34).

9. Bipolar plate (34) according to claims 6 to 8, characterized in that the first X/Y support elevation (72), the at least one first Z support elevation (76), the at least one second X/Y support elevation (74) and the at least one second Z support elevation (78) in the region of the ports (38, 40, 42) are designed to run continuously in the circumferential direction without interruption or to be interrupted in segments in the circumferential direction.

10. Bipolar plate (34) according to claims 2 to 9, characterized in that the openings (60) in the material of the insert seal (56) run horizontally and are designed as bores or transverse slots.

11. Bipolar plate (34) according to claims 2 to 10, characterized in that the membrane (70) is clamped between the insert seal (56) and an upper side (80) of the bipolar plate (34).

12. Bipolar plate (34) according to claims 2 to 11, characterized in that the membrane (70) is arranged by the at least one first X/Y support elevation (72) in a central arrangement (90) between two superimposed bipolar plates (34).

13. Bipolar plate (34) according to claims 6 to 12, characterized in that the bipolar plate (34) has at least one second X-/Y support elevation (74) which is arranged offset from the first X-/Y support elevation (72) and points in the Z direction (92) opposite to the first X-/Y support elevation (72)

14. Bipolar plate (34) according to claims 6 to 13, characterized in that the first X/Y support elevation (72) produces a defined bottom-side distance of the membrane (70) from the bipolar plate (34) and the second X/Y support elevation (74) produces a defined bottom-side distance of the membrane (70) from the bipolar plate (34).

15. Use of the bipolar plate (34) according to one of claims 1 to 14 in an electrolysis cell stack (46) of an electrolyzer (44).