Bipolar Plate and Layer Structure on the Bipolar Plate

Abstract

A bipolar plate, has a base area and raised structures provided thereon. The raised structures each have a first region and a second region. The first region is designed to penetrate into a gas diffusion layer that is to be brought into contact with the bipolar plate and to increase the contact area between the bipolar plate and the gas diffusion layer. The second region is between the base area of the bipolar plate and the first region of the raised structures. The first region and/or the second region is/are of such a form and/or arrangement that the base area of the bipolar plate and the gas diffusion layer are kept apart.

Claims

1. A bipolar plate, comprising: a base area; and raised structures provided on the base area, wherein the raised structures each comprise a first region, which is designed to penetrate into a gas diffusion layer to be brought into contact with the bipolar plate and to increase a contact area between the bipolar plate and the gas diffusion layer, and a second region, which is present between the base area of the bipolar plate and the first region of the raised structures, and the first region and/or the second region are formed and/or arranged to keep the base area of the bipolar plate and the gas diffusion layer at a spacing (X).

2. The bipolar plate according to claim 1, wherein the spacing (X) corresponds substantially to a height of the second region of the raised structures.

3. The bipolar plate according to claim 1, wherein the spacing (X) is 50 to 300 m.

4. The bipolar plate according to claim 1, wherein the spacing (X) is 70 to 150 m.

5. The bipolar plate according to claim 1, wherein: the gas diffusion layer is fibrous or foam-like, a height of the first region of the raised structures is 1-10 times an average fiber diameter of the fibers or an average foam bubble diameter of the foam bubbles in the gas diffusion layer, or a height of the first region of the raised structures is 3 to 100 m.

6. The bipolar plate according to claim 5, wherein the height of the first region is 2-4 times the average fiber diameter or the average foam bubble diameter.

7. The bipolar plate according to claim 5, rein the height of the first region is 5-30 m.

8. The bipolar plate according to claim 1, wherein one or more of: a width of a root (c) of the raised structures which is connected to the base area of the bipolar plate is smaller than twice the overall height of the raised structures, a spacing (f) between raised structures arranged in a row at a respective highest point thereof is greater than twice the overall height of the raised structures, and/or a spacing (e) between raised structures in adjacent rows at the respective highest point thereof satisfies the following relationship in relation to the spacing (f) between raised structures arranged in the row at the respective highest point thereof: e/f>2.

9. The bipolar plate according to claim 1, wherein: the raised structures are formed by applying an intermediate layer to the base area of the bipolar plate, or the raised structures are formed by structurally processing the bipolar plate.

10. The bipolar plate according to claim 9, wherein: the intermediate layer is a foam intermediate layer or an intermediate layer composed of individual structures.

11. The bipolar plate according to claim 9, wherein the structural processing is one or more of: a coating with material, a deposition of material, or a growth of material.

12. The bipolar plate according to claim 9, wherein the intermediate layer is connected to the base area of the bipolar plate by one or more of: adhesive bonding, soldering, brazing, by being pressed on or by being pressed in.

13. The bipolar plate according to claim 1, wherein the bipolar plate is free from embossed formations in an active region to provide flow fields.

14. A layer structure, comprising: a bipolar plate having a base area and raised structures provided on the base area; a gas diffusion layer; wherein the raised structures of the bipolar plate each comprise a first region designed to penetrate into the gas diffusion layer of the layer structure to increase contact area between the bipolar plate and the gas diffusion layer and a second region present between the base are of the bipolar plate and the first region, the first region and/or the second region of the raised structures being formed and/or arranged to maintain a spacing (X) between the base area and the gas diffusion layer.

15. The layer structure according to claim 14, wherein: the gas diffusion layer is fibrous or foam-like, and a depth of penetration of the first region of the raised structures into the gas diffusion layer is 1-10 times an average fiber diameter of fibers or an average foam bubble diameter of foam bubbles in the gas diffusion layer.

16. The layer structure according to claim 15, wherein material of the gas diffusion layer is compacted in a region of contact between the bipolar plate and the gas diffusion layer.

17. The layer structure according to claim 15, wherein the depth of penetration is 2-4 times.

18. The layer structure according to claim 14, wherein: the gas diffusion layer is fibrous or foam-like, and the spacing (X) satisfies the relationship:
X5*d, wherein d is an average fiber diameter of fibers or an average foam bubble diameter of foam bubbles in the gas diffusion layer, and the spacing (X) is 50-300 m.

19. The layer structure according to claim 18, wherein the spacing (X) is 70-100 m.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 shows a schematic illustration of a bipolar plate according to a first advantageous development of the invention.

[0035] FIG. 2 shows a schematic illustration of a bipolar plate according to a second advantageous development of the invention.

[0036] FIG. 3 shows a schematic illustration of a bipolar plate according to a third advantageous development of the invention.

[0037] FIG. 4 shows a schematic illustration of a bipolar plate according to a fourth advantageous development of the invention.

[0038] FIG. 5 shows a schematic illustration of a layer structure according to a first development of the invention.

[0039] FIG. 6 shows a schematic illustration of a layer structure according to a second development of the invention.

[0040] FIG. 7 shows a schematic illustration of a layer structure according to a third development of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0041] The invention will be described in detail on the basis of exemplary embodiments. The figures show only those parts of the bipolar plate according to the invention or of the layer structure which are of interest here; all other elements have been omitted for the sake of clarity. Furthermore, identical reference signs refer to identical components.

[0042] FIG. 1 shows a bipolar plate 10 comprising a base area 1 on which raised structures 2 are arranged or provided. The raised structures 2 each comprise a first region 4. The first region(s) 4 is or are designed to penetrate into a gas diffusion layer (not shown) to he brought into contact with the bipolar plate 10. This increases a contact area between the bipolar plate 10 and the gas diffusion layer. The raised structures 2 furthermore comprise second regions 3, which extend between the base area 1 of the bipolar plate 10 and the first regions 4 of the raised structures 2.

[0043] The arrangement of the first region 4 and of the second region 3, and therefore the arrangement of the raised structures 2 in relation to one another, is configured in such a way that the base area 1 of the bipolar plate 10 and a gas diffusion layer to be brought into contact with the bipolar plate are kept at a spacing. As is shown by way of example in FIG. 1, this is made possible by virtue of the fact that first and second regions of for example, adjacent raised structures 2 intersect. Thus, at least two intersecting structures give rise to a raised structure 2 which above the point of intersection has a first region 4 with a height h1 and below the point of intersection has a second region 3 with a height h2. When the bipolar plate 10 is being brought into contact with a gas diffusion layer, the extent of the intersecting structures prevents the complete penetration of the latter with the raised structures 2. The gas diffusion layer is thereby kept at a spacing which corresponds here, for example, to the height h2 of the second regions.

[0044] The height h2 of the second regions is in this case measured in a direction orthogonal to the base area 1 of the bipolar plate 10 and extends as far as the point of intersection of the raised structures 2. The height h1 of the first regions is determined in the direction of extent from the point of intersection as far as the end of the first region, i.e. the end which is provided to penetrate into a gas diffusion layer. The respective values relating to the heights are average values here.

[0045] It is preferable that a spacing X, and therefore also a height h2 of the second regions 3, is 50 to 300 m and preferably 70 to 150 m.

[0046] The raised structures 2 can be formed, for example, by applying an intermediate layer and, in particular, a foam-like intermediate layer and further in particular an intermediate layer composed of individual structures to the base area 1 of the bipolar plate 10. As an alternative thereto, the raised structures 2 can be formed by structurally processing the bipolar plate 10, in particular by coating with material, the deposition of material and/or the growth of material.

[0047] On account of the formation of the raised structures 2, the bipolar plate 10 provides a large potential contact area. Furthermore, on account of the second regions 3 of the raised structures 2, which are provided not to penetrate into the gas diffusion layer, provision is made of a media flow field in the bipolar plate 10 without the bipolar plate 10 having embossed formations in the active region for this purpose.

[0048] FIG. 2 shows an alternative configuration of a bipolar plate. The bipolar plate 20 again comprises a base area 1 with arrow-shaped raised structures 2 arranged thereon. The first regions 4 designed in arrowhead form facilitate penetration into a gas diffusion layer to be contacted, with the contact area being increased and therefore with the contact resistance being reduced. However, the wide legs of the arrowheads of the first regions 4 prevent penetration into a gas diffusion layer as far as the base area 1 of the bipolar plate 20, i.e. including the second regions 3. The second regions 3 thereby ensure that there is a spacing between the base area 1 of the bipolar plate 20 and a gas diffusion layer to be contacted.

[0049] FIG. 3 shows a further alternative configuration of a bipolar plate. The bipolar plate 30 comprises raised structures 2, which in turn have first regions 4 and second regions 3. Here, the form or the structure of the first regions 4 is designed in elation to the form and structure of the second regions 3 in such a way that penetration of the first regions 4 into a gas diffusion layer to be contacted is possible only up to the point of the raised structures 2 at which the second region 3 is designed in thickened form with respect to the first region 4.

[0050] The material and structure of the second regions 3 do not have to be solid, but instead may be porous or may be provided with passages, such that a flow field with a large media volume can be provided. c denotes a root of the raised regions 2 which is connected to the bipolar plate 30. A width of a root of the raised structures c which is connected to the base area of the bipolar plate 1 is in this case advantageously smaller than twice the overall height of the raised structures 2.

[0051] FIG. 4 shows a bipolar plate 40 having raised structures 2 arranged in two rows R, as have already been explained in FIG. 2. FIG. 4 illustrates the relationship between the raised regions 2. In this case, a spacing f between raised structures arranged in a row R at the respective highest point thereof is greater than twice the overall height h of the raised structures 2, where h=h1+h2. Furthermore, a spacing e between raised structures 2 in adjacent rows at the respective highest point thereof advantageously satisfies the following relationship in relation to a spacing f between raised structures 2 arranged in a row at the respective highest point thereof e/f>2.

[0052] FIG. 5 shows a layer structure 100 according to one development of the invention. The layer structure 100 is formed from a gas diffusion layer 5 and a bipolar plate 20 as shown in FIG. 2. The gas diffusion layer 5 and the bipolar plate 20 have been pressed together to produce the layer structure 100. As a result of this, the first regions 4 of the raised structures 2 penetrate into the surface of the gas diffusion layer 5. On account of the form or the structure of the first regions 4 and of the second regions 3, the second regions 3 have been prevented from sinking into the gas diffusion layer 5. A spacing X is thus formed between the gas diffusion layer 5 and the base area 1 of the bipolar plate 20, said spacing having a height which corresponds to the height of the second regions 3. A media flow field has been formed as a result of this. The layer structure 100 is distinguished by a low contact resistance and good suitability for conveying reaction media.

[0053] The gas diffusion layer is preferably fibrous or foam-like, and the spacing X satisfies the following relationship: X5*d. Here, d is an average fiber diameter of the fibers or an average foam bubble diameter of the foam bubbles in the gas diffusion layer 5.

[0054] Furthermore, the spacing X is preferably 50 to 300 m and preferably 70 to 150 m.

[0055] It is likewise preferable that a height hi of the first regions 4 of the raised structures 2 is 1-10 times, preferably 2-4 times, an average fiber diameter of the fibers or an average foam bubble diameter of the foam bubbles in the gas diffusion layer 5, the height h1 of the first regions 4 of the raised structures 2 being in particular 3 to 100 m, preferably 5 to 30 m.

[0056] FIG. 6 shows a layer structure 200 according to a second development of the invention. The layer structure 200 has been produced by pressing a bipolar plate 50 together with a gas diffusion layer 5. The bipolar plate 50 comprises pyramidal raised structures 2 each having a first region 4 and a second region 3. The first regions 4 of the raised structures 2 have penetrated into the gas diffusion layer 5 by virtue of an appropriate pressure when pressing the layers together. The form, design and arrangement of the raised regions, together with the contact pressure, give the desired spacing X. By limiting the pressure, in this case it is possible to prevent the raised structures 2 from penetrating further into the gas diffusion layer 5. It is therefore the case, as shown here, that second regions 3 of the raised structures 2 are exposed between the base area of the bipolar plate 1 and the first regions 4 of the raised structures 2, i.e. also between the base area of the bipolar plate 1 and the gas diffusion layer 5, this resulting in a spacing X between the base area of the bipolar plate 1 and the gas diffusion layer 5 which is suitable for forming a media flow field.

[0057] FIG. 7 shows a layer structure 300 according to a third development of the invention. The layer structure 300 differs from the layer structure 200 shown in FIG. 6 in terms of the form of the raised structure 2. The specific, M-shaped form offers a certain resistance, which, even when pressing the layer structure 300 together, prevents complete penetration of the raised structure 2 into the gas diffusion layer beyond the apex of the raised structure 2. By selecting the form of the raised region 2 in combination with the pressure when pressing the layer structure 300 together, it is thereby possible to set in a targeted manner a depth of penetration of the first region 4 of the raised structure 2, and therefore a certain spacing X, which corresponds to the height h2 of the second region 3 of the raised structure 2.

[0058] The above description of the present invention serves only for illustrative purposes and not for the purpose of limiting the invention. Various amendments and modifications are possible within the context of the invention without departing from the scope of the invention and the equivalents thereof.

LIST OF REFERENCE SIGNS

[0059] 1 Base area of the bipolar plate [0060] 2 Raised structures [0061] 3 Second regions of the raised structures [0062] 4 First regions of the raised structures [0063] 5 Gas diffusion layer [0064] 10 Bipolar plate [0065] 20 Bipolar plate [0066] 30 Bipolar plate [0067] 40 Bipolar plate [0068] 50 Bipolar plate [0069] 60 Bipolar plate [0070] 100 Layer structure [0071] 200 Layer structure [0072] 300 Layer structure [0073] c Root of a raised structure which is connected to the bipolar plate [0074] e Spacing between raised structures in adjacent rows at the respective highest point thereof [0075] f Spacing between raised structures arranged in a row at the respective highest point thereof [0076] h1 Height of the first regions [0077] h2 Height of the second regions [0078] h Overall height of the raised structures [0079] R Row of raised structures [0080] X Spacing

[0081] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.