Method for Manufacturing a Separator Plate for a Fuel Cell, Separator Plate and Intermediate Product for a Separator Plate

Abstract

The invention relates to a method for manufacturing a separator plate (12) for a fuel cell, wherein a curable and electrically conductive material (20) is applied to a substrate material (14). A flow field (34) for a reactant which can be supplied to the fuel cell is formed in the material (20). After the flow field (34) is formed, the material (20) is cured. The invention also relates to a separator plate (12) for a fuel cell and an intermediate product for a separator plate (12).

Claims

1-11 (canceled)

12. A method for manufacturing a separator plate for a fuel cell, in which a curable and electrically conductive material is applied onto a carrier material at a first processing station, wherein a flow-field for a reactant suppliable to the fuel cell is formed in the material, and wherein the material is cured following the forming of the flow-field, characterized in that the carrier material, provided with the curable material, passes through a plurality of processing stations, in that the material is, at least in regions, dried and/or gelled and/or precured before the introduction of the flow-field at the respective processing station, and in that the flow-field is subsequently formed in the material by means of an embossing tool and/or through roll-forming.

13. The method according to claim 12, characterized in that the material is, at least in regions, dried, and is subsequently gelled and/or precured before the introduction of the flow-field at the respective processing station.

14. The method according to claim 12, characterized in that the material (20) is curable through application with UV light.

15. The method according to claim 13, characterized in that the material (20) is curable through application with UV light.

16. The method according to claim 12, characterized in that the material is precured through application with UV light.

17. The method according to claim 13, characterized in that the material is precured through application with UV light.

18. The method according to claim 14, characterized in that the material is precured through application with UV light.

19. The method according to claim 15, characterized in that the material is precured through application with UV light.

20. The method according to claim 12, characterized in that to provide the cured material, a mixture, comprising at least one synthetic material provided with an electrically conductive filler, in particular an epoxy resin and/or an acrylate resin, and including a solvent, in particular comprising at least one photo-initiator, is used and/or a film, in particular a preferably biaxially-oriented polyester film, is used.

21. The method according to claim 13, characterized in that to provide the cured material, a mixture, comprising at least one synthetic material provided with an electrically conductive filler, in particular an epoxy resin and/or an acrylate resin, and including a solvent, in particular comprising at least one photo-initiator, is used and/or a film, in particular a preferably biaxially-oriented polyester film, is used.

22. The method according to claim 14, characterized in that to provide the cured material, a mixture, comprising at least one synthetic material provided with an electrically conductive filler, in particular an epoxy resin and/or an acrylate resin, and including a solvent, in particular comprising at least one photo-initiator, is used and/or a film, in particular a preferably biaxially-oriented polyester film, is used.

23. The method according to claim 15, characterized in that to provide the cured material, a mixture, comprising at least one synthetic material provided with an electrically conductive filler, in particular an epoxy resin and/or an acrylate resin, and including a solvent, in particular comprising at least one photo-initiator, is used and/or a film, in particular a preferably biaxially-oriented polyester film, is used.

24. The method according to claim 20, characterized in that the mixture includes the electrically conductive filler, preferably graphene, in a proportion from 3% by weight to 30% by weight, preferably from 3% by weight to 20% by weight, particularly preferably from 3% by weight to 10% by weight.

25. The method according to claim 12, characterized in that the carrier material is provided as a continuous material web, wherein at least one region is separated out of the carrier material provided with the cured material to manufacture the separator plate.

26. The method according to claim 12, characterized in that the cured material is provided in a thickness from around 50 ?m to around 150 ?m on the carrier material.

27. The method according to claim 13, characterized in that the cured material is provided in a thickness from around 50 ?m to around 150 ?m on the carrier material.

28. The method according to claim 12, characterized in that the cured material is detached from the carrier material for providing the separator plate.

29. The method according to claim 13, characterized in that the cured material is detached from the carrier material for providing the separator plate.

30. A separator plate for a fuel cell, wherein the separator plate is obtainable by the method according to claim 12.

31. An intermediate product for a separator plate according to claim 30, wherein the cured material is arranged on the support material.

Description

[0058] The Figures show in:

[0059] FIG. 1 schematically a production plant for manufacturing bipolar plates for fuel cells of a fuel cell stack, and

[0060] FIG. 2 an enlarged plan view of a manufactured bipolar plate.

[0061] A production plant 10, schematically shown in FIG. 1, serves the production of separator plates, wherein a bipolar separator plate, in the form of a bipolar plate 12, is shown in FIG. 2 in a plan view, which plate can be manufactured in the production plant 10. The bipolar plates 12 are provided for fuel cells of a fuel cell stack, as can come into use in a motor vehicle, for example.

[0062] Initially, a carrier material, presently in form of a carrier film 14, is provided in the production of the bipolar plates 12. Here, the carrier film 14 can be present wound up into a roll 16. In particular, a biaxially-stretched or biaxially-oriented polyester film can come into use as carrier film 14.

[0063] The carrier film 14 is unwound from the roll 16, and subsequently supplied to further processing stations of the production plant 10, At a first processing station 18, a mixture 28 is applied onto the carrier film 14, which mixture includes an electrically conductive material 20, wherein the material 20 can be cured. For example, the carrier film 14 can be applied with the mixture 28 via a slot nozzle 22 or the like application device, which mixture includes an epoxy resin and/or acrylic resin, at least one solvent, photo-initiators and electrically conductive fillers, such as carbon black and/or graphite. What is more, the mixture 28 can also comprise further fillers. A venting of the solvent from the mixture 28 occurs at a subsequent processing station 24. The consistency of the of material 20 thereby changes. The venting can, for example, be carried out over around a minute.

[0064] In particularly preferred embodiments, a mixture out of the following components can also be used as a mixture 28, instead of the mixture with the epoxy resin and/or the acrylic resin: [0065] 9.4% by weight of a double-bond containing polyol (solvent-free) with an OH content of 5.7% and a double-bond density of 3.5 mol/kg [0066] 28.2% by weight of a double-bond containing urethane acrylate (solvent-free) with a NCO content of 5.4% and a double-bond density of 1.5 mol/kg [0067] 28.2% of a double-bond containing urethane acrylate (solvent-free) with a glass transition temperature of 2? C. (established by means of differential scanning calorimetry at a heating rate of 10? C/min) and a double-bond density of 4 mol/kg [0068] 1.4% by weight of a commercially-available photo initiator [0069] 0.5% by weight of a commercially-available flow-control agent [0070] 1.0% by weight of a commercially-available defoamer [0071] 25.3% by weight butyl acetate [0072] 6% by weight graphene

[0073] The mixture 28 or material 20 is subsequently pre-dried, for example by means of a heating unit 26, which mixture/material is applied onto the carrier film 14. The application of the mixture 28 with heat at the heating unit 26 leads presently to a gelling or dry-hardening of the mixture 28 or of the material 20. The material 30 can additionally be partially-cured or pre-cured at a subsequent, optional processing station 30. For this purpose, the material 20 can be applied with light, in particular with UV light at the processing station 30.

[0074] Subsequently, structures are formed in the dry-hardened or partially-cured material 20, e.g. in the form of channels 32 (see FIG. 2), which form a flow-field 34 in the completed bipolar plate 12. Through a corresponding setting of the proportion of the solvent and the solids in the mixture 20, it can be achieved that desired surface structures can be formed in the pre-dried or dry-hardened and/or, through UV light at the processing station 30, partially cured material 20.

[0075] To form the surface structures of the bipolar plate 12 including the flow-field 34, an in particular two-piece embossing tool can find use as a tool 36. Additionally or alternatively, this structuring can be undertaken through a tool 36 suited for roll forming or roll-profiling. In particular, the channels 32 or groove structures can, in this way, be formed in the material 20.

[0076] The flow-field 34 (see FIG. 2) formed by means of the corresponding tool 36 enables a (not shown) membrane electrode assembly of the fuel cell to be applied with a reactant, for example with hydrogen as fuel or with oxygen or air as an oxidizing agent. Moreover, structural elements can be provided on surface structures by means of the tool 36, which elements are provided, in the bipolar plate 12, in a respective transition region 40 between the flow-field and corresponding inlets or outlets, for the reactants involved in the fuel cell reaction (see FIG. 2).

[0077] Due to the provisioning of the photo-initiators in the mixture 28, the material 20 can be completely cured in a subsequent processing step. For this purpose, a corresponding light source 38, in particular UV light source, is provided at a further processing station. After the curing of the material 20, e.g. by means of the UV light emitted by the light source 38, the corresponding structures are permanently formed in the material 20.

[0078] In a subsequent processing step, a plurality of though-passages 44 can be formed in the material 20, for example through punching 42 (see FIG. 2). A fuel cell inlet and a fuel cell outlet, an oxidizing agent inlet and an oxidizing agent outlet, as well as a coolant inlet and a coolant outlet are usually provided through such through-passages 44. These through-passages 44 form corresponding channels for supplying and discharging of the reactants or of the coolant, in the fuel cells stacked on top of each other.

[0079] An outer contour 56 of the bipolar plate 12 can be manufactured, as desired, in a subsequent processing step or at a subsequent processing station, by cutting 46. In particular a laser or the like can come into use for the cutting 46. Moreover, regions can be removed from the cured material 20 by means of a laser, in order to form desired structures in the bipolar plate 12.

[0080] The material 20, moreover, is connectable, through a suitable joining method, in particular through adhesion, with a further part formed out of the material 20, as precedingly described. Consequently, a first partial plate of the bipolar plate 12 can be provided through the material 20, which plate can be connected with a second partial plate of the bipolar plate 12 through joining 48. In this way, a flow-field for a coolant can be provided in cavity or intermediate space 50 between two such partial plates (comparison FIG. 2).

[0081] Preferably, a thickness 52 of the cured material 20 (see FIG. 2) is very low. In particular, the thickness 52 is preferably significantly less than a depth 54 of the grooves or channels 52, which are formed, in the region of the flow-field 34, for the reactant or, in the region of the flow-field, for the coolant.

[0082] Moreover, the material 20 is sealed with respect to air or oxygen and with respect to hydrogen. In addition, the material 20 comprises a corresponding mechanical strength and structural integrity for the providing of the bipolar plates 12, which are meant to come into use in the fuel cells of the fuel cell stack. The electrical resistance is set, through suitable fillers, such as the carbon black particles or graphite particles, such that the material 20 comprises a good electrical conductivity. For example, the electrical resistance of the material 20 can lie in the range from 10 mOhm/cm.sup.2 to 30 mOhm/cm.sup.2.

[0083] The carrier film 14 provided with the cured material 20 can also be provided, initially, as intermediate product or semi-finished product before its final form is conferred through corresponding further processing steps, such as the punching 42, the cutting 46 or the joining 48 of the bipolar plates 12. The intermediate product can in particular be wound up into a roll.

[0084] Moreover, it can be provided that regions, such as the through-passages 44, can be separated out of the carrier film 14 provided with the cured material 20, and thus an intermediate product or semi-finished product surrounding the carrier film 14 with the cured material 20 is made available and is wound up, in particular into a roll. The bipolar plate 14 with a desired outer contour 56 can then be formed from such an intermediate product through a cutting 46 and joining 48, after a detaching of the material 20 from the carrier film 14. In particular, the intermediate product can initially be cut and, after the detaching of the material 20 from the carrier plate, the bipolar plate 12 can be formed through joining of the thus-obtained partial plates.