DISTRIBUTOR STRUCTURE FOR A FUEL CELL OR ELECTROLYSER

Abstract

The invention relates to a distributor structure (12, 20), particularly a bipolar plate for a stack structure (10) of a fuel cell or of an electrolyser. The distributor structure (12, 20) comprises a channel structure (48) that interacts with at least one polymer membrane (16). The distributor structure (12, 20) is designed as a plastic part (40) that has electrically conductive properties.

Claims

1. A distributor structure (12, 20), having a channel structure (48) that interacts with at least one polymer membrane (16), characterized in that the distributor structure (12, 20) is embodied as a plastic part (40) that has electrically conductive properties.

2. The distributor structure (12, 20) as claimed in claim 1, characterized in that the distributor structure is an insert in a carrier of trough-shaped design.

3. The distributor structure (12, 20) as claimed in claim 1, characterized in that the plastic part (40) is injection-molded from a graphite-plastic material mixture.

4. The distributor structure (12, 20) as claimed in claim 1, characterized in that the plastic part (40) has a channel structure (48) on its a side (54) facing the polymer membrane (16).

5. The distributor structure (12, 20) as claimed in claim 4, characterized in that the channel structure (48) has a number of small contact points (60) that contact an underside (50) of a polymer membrane (16) or an upper side (52) of a polymer membrane (16).

6. The distributor structure (12, 20) as claimed in claim 1, characterized in that the plastic part (40) has a bearing surface (44), by means of which the plastic part is received on a base (46) of the carrier.

7. The distributor structure (12, 20) as claimed in claim 4, characterized in that the contact points (60) of a contact surface (32) are between 0.1 mm.sup.2 and 1 mm.sup.2.

8. The distributor structure (12, 20) as claimed in claim 1, characterized in that a plastic part (40) has at least one circumferential seal (64) which seals the plastic part with respect to the polymer membrane (16).

9. The distributor structure (12, 20) as claimed in claim 4, characterized in that the contact points (60) are embodied in droplet form (58) or in conical form.

10. (canceled)

11. (canceled)

12. A stack structure (10) of a fuel cell having a polymer membrane (16) which is conductive for protons or hydroxide, the stack structure comprising the distributor structure (12, 20) as claimed in claim 1.

13. A stack structure (10) of an electrolyser having a polymer membrane (16) which is conductive for protons or hydroxide, the stack structure comprising the distributor structure (12, 20) as claimed in claim 1.

14. The distributor structure (12, 20) as claimed in claim 1, characterized in that the distributor structure is an insert in a partition plate (42).

15. The distributor structure (12, 20) as claimed in claim 1, characterized in that the plastic part (40) is injection-molded from plastic material which is provided with an electrically conductive coating (38).

16. The distributor structure (12, 20) as claimed in claim 1, characterized in that the plastic part (40) has a bearing surface (44), by means of which the plastic part is received on a partition plate (42).

17. The distributor structure (12, 20) as claimed in claim 1, wherein the distributor structure is a bipolar plate for a stack structure (10) of a fuel cell or of an electrolyser.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The invention is described in greater detail below with reference to the drawings.

[0027] In the drawings:

[0028] FIG. 1 shows a schematic diagram of a stack structure for a fuel cell or an electrolyser,

[0029] FIG. 2 shows a distributor structure, for example a bipolar plate, manufactured as an injection-molding insert,

[0030] FIG. 3 shows a distributor structure, in particular a bipolar plate as an injection-molded component with an integrally molded seal,

[0031] FIG. 4 shows an enlarged illustration of the plastic part,

[0032] FIGS. 5 and 6 show details of the distributor structure.

DETAILED DESCRIPTION

[0033] The illustration according to FIG. 1 is a schematic diagram of a stack structure 10 for use within a fuel cell or an electrolyser.

[0034] A stack structure 10 according to the illustration in FIG. 1 comprises a first distributor structure 12, in particular a bipolar plate, and a first gas diffusion layer 14. A polymer membrane 16 is situated below the first gas diffusion layer 14, within the stack structure 10. In addition, the stack structure 10 comprises a second gas diffusion layer 18 and a second distributor structure 20, in particular a second bipolar plate. These 5 layers essentially make up the stack structure 10, which can be used both in the context of a fuel cell and in the context of an electrolyser. While in fuel cells hydrogen H2 and oxygen O2 are converted into water H2O, electrical energy and heat for energy production, within an electrolyser water is decomposed into H2 and O2 by means of electric current.

[0035] FIG. 1 shows the stack structure 10, which can be extended to form a stack if the stack structure 10 is repeated.

[0036] The illustration according to FIG. 1 furthermore shows an imaginary dividing line 36 above which the stack structure 10 consisting of the five components mentioned above is situated.

[0037] As FIG. 1 furthermore shows, flow channels 26 for O2 are formed within the first distributor structure 12, as well as cooling channels for a cooling medium, e.g. H2O. Similarly, at the lower end of the stack structure 10 above the imaginary stack boundary 36, there are flow channels 28 for gaseous H2 and flow channels 30 for receiving cooling medium, for example H2O, in a second distributor structure 20, in particular a second bipolar plate. For the sake of completeness, it may be mentioned that the stack structure 10 is mounted along contact surfaces 32 on a further distributor structure 22 of a further stack structure, not shown completely here, having a further gas diffusion system 23 and a further polymer membrane 24. The flow channels 26, 28, 30 for the various media are delimited by wall surfaces 34.

[0038] The illustration according to FIG. 2 shows an embodiment variant of a distributor structure 20 manufactured as a plastic part.

[0039] As FIG. 2 shows, in this embodiment variant, the first distributor structure 12 or the second distributor structure 20 is manufactured as a plastic part 40. The plastic part 40 may be one which is injection-molded from a graphite-plastic-material-compound mixture and already has electrically conductive properties as a result of the plastic component composition. On the other hand, there is also the possibility of producing the plastic part 40 from a plastic material and then coating the latter with an electrically conductive coating 38, for example a metallic coating.

[0040] The plastic part 40 shown in FIG. 2 is mounted on a carrier, for example a partition plate 42, which essentially has a trough shape. By means of a bearing surface 44 of the plastic part 40, the latter is mounted on a base 46 of the carrier, in particular of the partition plate 42, or is simply inserted into the latter.

[0041] The plastic part 40 has a channel structure 48, or a flow field, which replaces the channels of the channel structure 48. The channel structure 48, which is formed on a side 54 of the plastic part 40 which faces the polymer membrane 16, has a number of conical tips 56, at the ends of which there are small contact points 60. The small contact points 60 of the channel structure 48 have a contact surface 30 which can be from 0.1 mm.sup.2 to 1 mm.sup.2, enabling surface contact to be established with the underside 50 of the polymer membrane 16. The individual tips 56 of the channel structure 48 on the plastic part 40, which are, for example, of conical design, can be coated with an electrically conductive coating 38, as indicated in a greatly enlarged representation in FIG. 4.

[0042] The channel structure 48 of the plastic part 40 is in contact with an underside 50 of the polymer membrane 16 on its side 54 facing the polymer membrane 16. An upper side of the polymer membrane 16 is identified by reference sign 52. The tips 56 of the channel structure 48 terminate in the small contact points 60, the number of which is minimized. The small contact points 60 preferably have a contact surface which is in the order of between 0.1 mm.sup.2 and 1 mm.sup.2. The number and size of the small contact points 60 reduce the area under which process water could accumulate during operation of the stack structure 10, which reduces the active area of the polymer membrane 16 and thus reduces the overall efficiency of the stack structure 10, whether it is used in a fuel cell or in an electrolyser. The reduction is mainly due to the reduction of the active area.

[0043] The number of small contact points 60 can be reduced to an extent such that the polymer membrane 16 has sufficient points of support and the electrical resistance does not become excessive. The small contact points 60 of the tips 56 of the channel structure 48 can be formed, for example, in the cathode path in a flow-optimal structure, for example in droplet form 58. As a result, the pressure loss in the stack structure 10 can be reduced and hence the overall efficiency of the stack structure 10, whether in a fuel cell or in an electrolyser, can be considerably improved.

[0044] The illustration according to FIG. 2 furthermore shows that there are flow channels 30 for product water under the base 46 of the carrier, which is, in particular, designed as a partition plate 42. FIG. 2 furthermore shows that the carrier, designed, in particular, as a partition plate 42, rests on contact surfaces 32 of the second distributor structure 20 illustrated in FIG. 2, in particular a bipolar plate.

[0045] The illustration according to FIG. 3 is a further possible embodiment of the plastic part 40 serving as a distributor structure 12, 20, in particular as a bipolar plate.

[0046] In the possible embodiment of the plastic part 40 shown in FIG. 3, the latter is provided with a seal 64 which is, for example, of circumferential design and which, during the production of the plastic part 40, can be molded onto the latter, for example.

[0047] The channel structure 48 comprises individual, for example conical tips 56, at the ends of which small contact points 60 are formed. The number of small contact points 60 is selected so that, on the one hand, a minimum of the small contact points 60 is present and, on the other hand, the polymer membrane 16 still has sufficient points of support to make contact with the plastic part 40.

[0048] The illustration according to FIG. 3 furthermore shows a seal 66. By means of the seal 66, which is situated at the sides of the base 46 of the carrier, designed, in particular, as a partition plate 42, the carrier is sealed off from the distributor structure 12, 20 situated underneath, in particular a bipolar plate. The carrier designed, in particular, as a partition plate 42 rests on individual contact surfaces 32 of the second distributor structure 20, in particular a bipolar plate, arranged beneath the carrier designed as a partition plate 42. The flow channels 30 for product water that is formed run in said distributor structure.

[0049] The circumferential seal 64 shown in the illustration according to FIG. 3 or the seal 66 for the first or second distributor structure 12, 20, in particular bipolar plate, can be produced directly during the production of the plastic part 40 by the 2-component injection molding process, and therefore additional operations for the production of the circumferential seal 64 or of the seal 66 for the first or second distributor structure 12, 20, in particular bipolar plate, are unnecessary.

[0050] With respect to the plastic part 40, its electrical conductivity is produced by the selected material mix of graphite and plastic, and in this case the electrical conductivity is achieved by adding graphite. In the event that the electrical resistance is too high, the plastic material could additionally or exclusively be coated with a metallic material, depending on the electrical resistance requirements.

[0051] The greatly enlarged illustration according to FIG. 4 shows that the plastic part 40 has the channel structure 48, which is essentially provided by an arbitrary sequence of tips 56, e.g. conical tips. The side 54 of the plastic part 40 which faces the polymer membrane 16, in particular the tips 56 of the channel structure 48, can be provided with an electrically conductive coating 38, in particular a metallic coating, for influencing the electrical resistance, as shown in the greatly enlarged illustration according to FIG. 4. The polymer membrane 16 has the underside 50 and the upper side 52, wherein the underside 50 of the polymer membrane 16 faces the side 54 of the plastic part 40 which faces the polymer membrane.

[0052] FIGS. 5 and 6 show details of distributor structures 12, 20, 22, in particular of bipolar plates. As can be seen, for example, from FIG. 5, the channel structure 48 can be formed from a number of channels extending substantially parallel to one another. Furthermore, the channel structure 48 can comprise knob-shaped elevations 62, likewise schematically indicated in FIG. 5. It is apparent from the sectional illustration according to FIG. 6 that the small contact points 60 (shown here in a greatly enlarged illustration) have a droplet shape 58, which is particularly favorable in terms of flow. In comparison with the surfaces of the distributor structures 12, 20, 22 shown in FIGS. 5 and 6, both the channel structure 48, the knobs 62 and the contact points 60 in droplet form 58 are shown in greatly enlarged representation.

[0053] The invention is not restricted to the illustrative embodiments described here or to the aspects emphasized herein. On the contrary, a large number of modifications that lie within the scope of action of a person skilled in the art is possible within the range indicated by the claims.