Method for producing a bipolar plate, unipolar plate or separator plate for electrolysers or the like, and a corresponding device
Patent Information
- Application Number
- EP2024715112
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-03-24
- Filing Date
- 2024-03-22
- Publication Date
- 2026-02-11
AI Technical Summary
The existing methods for producing bipolar, unipolar, and separator plates for electrolyzers, which involve roll forming and subsequent cutting, suffer from efficiency losses due to deformation of the channel structure, particularly when cutting small cutouts, leading to impaired flow field performance.
A method that involves a two-stage roll-to-roll or roll-to-sheet process where small cutouts are created before roll forming and larger cutouts are produced after roll forming, with the option to cut the bipolar plate in the same process step, using roll-to-roll, roll-to-sheet, or roll-to-product processes to minimize structural impairment and maintain the integrity of the flow field.
This approach maintains the shape and efficiency of the roll-formed structure, reducing material deformation and enhancing the performance of the bipolar plates by categorizing cutouts based on their cross-sectional area and processing them in separate stages to prevent structural damage during cutting.
Smart Images
Figure EP2024057837_03102024_PF_FP_ABST
Abstract
Description
[0001] Method for producing a bipolar plate, unipolar plate or separator plate for electrolyzers or the like and a corresponding device
[0002] DESCRIPTION
[0003] The invention is based on a method for producing a bipolar plate, a unipolar plate, a separator plate for electrolyzers, or the like according to the preamble of claim 1, as described in DE 10 2010 048 761 A1. A similar method is also described in WO 2018 / 115952 A1.
[0004] To form the surface structure of the bipolar plate, unipolar plate, or separator plate, which also includes the flow field, it is known to process the material web by roll forming. For this purpose, a two-part stamping tool can be used, for example, a pair of rollers constructed according to the male-female principle. In this way, channel structures of the flow field can be formed in the material web. Furthermore, additional structural elements are formed, for example, to provide fluidic connections between the flow field and cutouts in the bipolar plate through which reaction gases and other reactants involved in the fuel cell reaction are to be conducted. Such cutouts include, for example, a fuel inlet, a fuel outlet, an oxidant inlet, an oxidant outlet, a coolant inlet, and a coolant outlet.In the subsequent stack of a large number of bipolar plates, these cutouts form channels for the supply and discharge of the reactants or the coolant.
[0005] The plate cutouts are created, for example, in a processing step following roll forming, namely cutting. Bipolar plates are often not cut using a rotary process. In this case, roll cutting or roll punching of the material web can impair the channel structure and other structuring of the material web formed during the preceding roll forming, thus leading to a loss of efficiency in the fuel cell. This impairment of roll forming is particularly pronounced for small cutouts, i.e., cutouts with a small opening cross-section, or for cutouts whose cross-sectional area is much smaller in one direction than in the direction perpendicular to it.
[0006] It is therefore the object of the invention to further develop the method described above in such a way that the shape-retaining maintenance of the roll forming is possible when using a roll-to-roll method, a roll-to-sheet method and / or a roll-to-product method for producing the cutouts.
[0007] In the sense of the invention, a roll-to-roll process is understood to mean that a material web, in particular a continuously guided one, is fed to at least two successive rolls and / or roll arrangements.
[0008] A roll-to-sheet process is understood in the sense of the invention to mean that a, in particular continuously guided, material web is fed to a roll and / or roll arrangement, and in this roll and / or roll arrangement or downstream of this roll and / or roll arrangement, individual elements are produced from the material web, which are in particular fed to further processing steps for the production of an end product.
[0009] A roll-to-product process is understood in the sense of the invention to mean that a, in particular continuously guided, material web is fed to a roll and / or roll arrangement, and in this roll and / or roll arrangement or downstream of this roll and / or roll arrangement, individual elements are produced from the material web, which represent the end product of the process, in particular without further processing steps.
[0010] This object is achieved by a method having the features of claim 1. A corresponding device is the subject of claim 18. Advantageous embodiments are described in the dependent claims. Finally, claim 2 is directed to an electrolyzer comprising an element produced according to the described method. Specifically, the invention thus provides a method for producing a bipolar plate, a unipolar plate, a separator plate, and / or the like, wherein the method comprises the following steps, which can be carried out in different orders: providing a material web made of metal or graphite, and / or a material web based on a polymer;
[0011] Roll forming of the material web; and
[0012] Cutting the material web, wherein a plurality of cutouts are produced in a region of the material web that is or was formed during the roll forming, or adjacent to this region; wherein furthermore the cutting is carried out in a roll-to-roll, roll-to-sheet or roll-to-product process, preferably in roll punching and / or roll cutting.
[0013] It is proposed that at least one of the cutouts is produced before roll forming and / or that the roll-to-roll, roll-to-sheet and / or roll-to-product process is carried out in two stages, with a first stage in which the at least one cutout is produced before roll forming, and with a second stage in which at least one further cutout is produced after roll forming.
[0014] It is also preferred that the at least one cutout produced before the roll forming is produced with an opening cross-section that is smaller than an opening cross-section of the at least one further cutout produced after the roll forming.
[0015] In the aforementioned embodiment, it is preferred that the opening cross-section of the at least one further cutout produced after the roll forming is at least twice, preferably at least four times and particularly preferably at least eight times larger than the opening cross-section of the at least one cutout produced before the roll forming.
[0016] A method according to the invention can be characterized in that in the second stage, in addition to the at least one further cutout, a bipolar plate formed in the preceding method steps, including a flow field, is cut out of the material web.
[0017] It is proposed that the creation of at least one additional cutout and the cutting of the bipolar plate from the material web take place in the same process step. Alternatively, it is proposed that at least one of the cutouts be created after roll forming.
[0018] It can also be provided that all of the cutouts are produced before roll forming, preferably so that after roll forming the bipolar plate is completely formed in the material web.
[0019] A method according to the invention can provide for categorizing the breakouts to be produced in the roll-to-roll, roll-to-sheet or roll-to-product process based on their respective opening cross-sectional area into one of at least two categories, each of which is assigned an opening cross-sectional area range.
[0020] It is also proposed that the opening cross-sectional area regions are non-overlapping or overlapping, but preferably not congruent and / or none of the regions is a proper subset of at least one other of the regions.
[0021] In the two aforementioned embodiments, it is preferred that the roll-to-roll, roll-to-sheet or roll-to-product process is carried out for at least two of the at least two categories in different roll-to-roll, roll-to-sheet or roll-to-product units between which the material web is transported.
[0022] It is proposed that the production of the cutouts of a first of the categories is carried out in a first roll-to-roll, roll-to-sheet or roll-to-product unit which is arranged upstream of the roll forming in the material web feed direction, wherein the first category is assigned to those of the plurality of cutouts with an opening cross-sectional area which is smaller than the opening cross-sectional areas of all the remaining plurality of cutouts.
[0023] Furthermore, it is preferred that the roll-to-roll, roll-to-sheet, or roll-to-product process for a second of the categories, to which the remaining sections are at least partially assigned, is carried out in a second roll-to-roll, roll-to-sheet, or roll-to-product unit that is located downstream of the first roll-to-roll unit in the material web feed direction. Preferred embodiments of the process can provide for the second roll-to-roll unit to be located upstream or downstream of the roll forming process in the material web feed direction.
[0024] It is also preferred that the production of the cutouts of a first of the categories is carried out in a first roll-to-roll, roll-to-sheet or roll-to-product unit which is arranged downstream of the roll forming in the material web feed direction, wherein in particular those of the plurality of cutouts with an opening cross-sectional area which is smaller than the opening cross-sectional areas of all the remaining plurality of cutouts are assigned to the first category.
[0025] It is proposed that the roll-to-roll, roll-to-sheet or roll-to-product process for a second of the categories, to which the remaining sections are at least partially assigned, is carried out in a second roll-to-roll, roll-to-sheet or roll-to-product unit which is located upstream or downstream of the first roll-to-roll unit in the material web feed direction.
[0026] Finally, it is preferred for the method that the bipolar plate is cut out of the material web, wherein the separation is carried out in a third roll-to-roll unit which is arranged downstream of the roll forming and all other roll-to-roll units in the material web feed direction.
[0027] The invention further provides a device for producing a bipolar plate, a unipolar plate, a separator plate or the like, preferably for carrying out the aforementioned method, wherein the device comprises the following functional units: at least one unwinder for providing a material web made of metal or
[0028] Graphite, or a polymer-based material web; at least one roll-forming unit for roll-forming the material web; and at least one roll-to-roll, roll-to-sheet, or roll-to-product unit for roll-punching or roll-cutting the material web, wherein the roll-to-roll, roll-to-sheet, or roll-to-product unit is configured to produce multiple cutouts in a region of the material web formed during the roll-forming or in a region adjacent to this region. It is also proposed for the device that the at least one roll-to-roll, roll-to-sheet, or roll-to-product unit is arranged upstream of the roll-forming unit in the feed direction of the material web.
[0029] It is also preferred that the at least one roll-to-roll, roll-to-sheet or roll-to-product unit is arranged downstream of the roll forming unit in the feed direction of the material web.
[0030] Finally, the invention provides an electrolyzer comprising at least one bipolar plate, at least one unipolar plate and / or at least one separator plate, wherein the bipolar plate, the unipolar plate and / or the separator plate is produced by a method according to the invention.
[0031] Further details of the invention are explained with reference to the following figures. None of the examples described are intended to limit the invention. The features described with reference to the individual figures can, as long as they do not contradict one another, also be used in any combination to realize an embodiment of the invention that is not explicitly shown in the figures. In particular, features of individual embodiments can also be omitted.
[0032] Rotary cutting tools are commonly used in the packaging industry to cut individual packages from the material web. Cutting occurs at speeds of up to 600 m / min. Until now, bipolar plates have not been cut using rotary cutting.
[0033] For the production of bipolar plates, unipolar plates, or separator plates (metal-, graphite- and / or polymer-based) in the roll-to-roll process, roll-to-sheet process and / or roll-to-product process, it is necessary to cut out cutouts for the liquid transport as well as the entire embossed bipolar or unipolar plate.
[0034] Figure 1 shows an example of a bipolar plate with cutout regions according to the prior art, where the size of the cutout regions varies with the plate design. The cutouts are classified according to their size, in this case into the class of small and the class of medium-sized cutouts. If the plate design is rather simple, it is possible to cut out all the necessary parts in one piece, as shown in Figure 2. However, it has been found that if all cutouts of any size are to be produced in a single step in the roll-to-roll process, cutting small cutouts in an already roll-formed plate can deform the embossed structure.
[0035] Although a roll-to-roll process is described in this example, the invention may alternatively or additionally comprise a roll-to-sheet and / or a roll-to-product process.
[0036] To solve this problem, the embodiment shown in Figure 3 proposes first creating small cutouts in a first roll-to-roll process prior to roll forming, and only then embossing the structure by means of roll forming. In a second roll-to-roll process following roll forming, or a second step of a roll-to-roll process, the medium-sized cutouts can be created and the entire plate cut out in a separate cutting unit. It is also possible for the medium-sized cutouts and the entire plate to be cut out in separate cutting units. Depending on the plate design and roller arrangement, it may also be advantageous for the medium-sized cutouts to be cut out before roll forming, as shown in Figures 4 and 5.
[0037] Figure 6 shows various possible plate orientations on a cutting roller for producing the cutouts in a roll-to-roll process. The upper row shows rectangular plates. In the top left variant, the plates are aligned in the circumferential direction. In the top center variant, the plates are aligned in the axial direction. In the top right variant, the plates are inclined to the axial or circumferential direction. In the bottom center variant, the plates are formed with a parallelogram shape.
[0038] The platens can be aligned on the cutting tool in the axial or circumferential direction. It is also possible to tilt the platen so that there is no long cutting line in the axial direction. This avoids high line loads in the axial direction (as in Figure 6, top center) and can be advantageous for the cutting process. It is also possible to design the platen like a parallelogram (Figure 2, bottom center). The platen can then be arranged as in Figure 6, bottom center (or in a different arrangement) to reduce the line load during the cutting process. The line load is also reduced in the variant shown in the top right of Figure 6. Register control can be helpful in keeping the embossing and cutting of the plates in line in multi-stage processes.
[0039] In the packaging industry, cutting tools often use a punching line to cut the material, as shown in Figure 7. A distinction is made here between cutting against a punching surface (a) and cutting against a punching element (b). In variant (a), the punching line exerts pressure on the material web until the material tears and is pushed aside. In this case, the counterpart is flat. According to (b), it is also possible to use a punching element as the counterpart. The cutting effect is better than variant (a), but the wear on the cutting tool is higher. Both variants (a) and (b) could also be used for cutting metal, but the forces that would have to be applied would be very high.
[0040] More suitable for metal is one of the cutting tools according to variants (c) - (f) shown in Figure 8. The distance between the cutting elements is described by k and ranges between 1 pm and 20 pm. There are four particularly preferred embodiments of cutting edges, which are described with reference to Figures 9 to 12.
[0041] Figure 9 shows an embodiment with rectangular cutting elements (c). Rectangular cutting shapes can be used for cutting sheet metal. The spacing between the cutting elements is defined by k and lies between 1 pm and 20 pm. The rectangular shape is robust against wear but sensitive to tool misalignment.
[0042] Figure 10 shows an embodiment with one rectangular and one angled cutting element (d). Here, one cutting element encloses an angle "alpha" to further improve the cutting of metal. "Alpha" can be between 0° and 45°. However, this arrangement is sensitive to misalignment of the tools. The advantage of this arrangement is that the material web is pushed to the side during cutting, which leads to easier material removal. Figure 11 shows an embodiment with two angled cutting elements (e). In the event of small misalignments, the surfaces of the cutting elements slide over each other so that the cutting edge is not destroyed. Both sides of the material web are pushed away from the cutting position.
[0043] Figure 12 shows an embodiment with two angled cutting elements with an additional bevel (f). This arrangement is similar to embodiment (e), but here one or both cutting elements have an additional inclination. The inclination is described by the angle "beta" and can be between 1° and 90°. The use of this additional inclination leads to better material removal after cutting.
[0044] Figure 13 shows an embodiment with a butterfly cut (g). Here, the two angles "alpha" and "beta" point in the opposite direction compared to embodiments (d) to (f). The range of "alpha" and "beta" is preferably 0° - 45°. This embodiment results in the cleanest cut of the material web, especially if it consists of or contains a metal. However, the removed material is not pushed away. Furthermore, misalignment of the tool can lead to significant damage to the cutting edges.
[0045] After embodiments of the preferred cutting geometries have been described with reference to the preceding figures, preferred cutting line geometries are described with reference to the following figures. Parallel cutting lines can fail if long cuts occur in the axial direction (see Figure 6, top left and top center). Here, the long axial cut leads to a high line load that must be compensated for by the cutting unit. To avoid high line loads, advantageous cutting edge shapes are described with reference to Figure 14. Figure 14 shows a side view of the rolls with various cutting elements; (h): triangular cutting element; (i) oblique cutting element; (j): wave or zigzag cutting element. Here, the cutting elements are shown in a plane perpendicular to that shown in (c) to (g).
[0046] In embodiment (h), a cutting tip is located in the center of the element, from which cutting begins. In embodiment (i), a cutting tip begins on the side of the cutting element. In embodiment (j), the cutting element has several ridges where cutting begins. Both embodiments (h) and (i) require a very high cutting edge to achieve a slope across the entire cutting element. This results in a greater element height. Embodiment (j) uses several ridges to begin the cut and requires a lower cutting element height compared to (h) and (i). On the other hand, embodiment (j) can lead to an unclean cutting result. It is also possible to use embodiments (h) - (j) in combination and / or for both edges of the same cutting element.
[0047] All cutting elements can be integrated directly into the roller material or designed as replaceable segments. The advantage of using replaceable segments is the interchangeability of individual segments / cutting elements in the event of damage and the possibility of readjusting individual elements if cutting performance decreases (e.g., due to wear).
[0048] The features of the invention disclosed in the above description, in the drawings and in the claims may be essential for the realization of the invention both individually and in any combination.
Claims
CLAIMS 1. A method for producing a bipolar plate, a unipolar plate, a separator plate and / or the like, the method comprising the steps which can be carried out in different orders: Providing a material web made of metal or graphite, and / or a material web based on a polymer; Roll forming of the material web; and Cutting the material web, wherein a plurality of cutouts are produced in a region of the material web which is or was formed during the roll forming, or adjacent to this region; characterized in that the cutting is carried out in a roll-to-roll, roll-to-sheet or roll-to-product process, preferably in roll punching and / or roll cutting.
2. The method according to claim 1, wherein at least one of the cutouts is produced before the roll forming and / or wherein the roll-to-roll, roll-to-sheet and / or roll-to-product process is carried out in two stages, with a first stage in which the at least one cutout is produced before the roll forming, and with a second stage in which at least one further one of the cutouts is produced after the roll forming.
3. The method according to claim 2, wherein the at least one cutout produced before the roll forming is produced with an opening cross-section which is smaller than an opening cross-section of the at least one further cutout produced after the roll forming.
4. The method according to claim 3, wherein the opening cross-section of the at least one further cutout produced after the roll forming is at least twice, preferably at least four times and particularly preferably at least eight times larger than the opening cross-section of the at least one cutout produced before the roll forming.
5. Method according to one of claims 2 to 4, wherein in the second stage, in addition to the at least one further cutout, a bipolar plate formed in the preceding method steps, including a flow field, is cut out of the material web.
6. The method according to claim 5, wherein the production of the at least one further cutout and the cutting out of the bipolar plate from the material web take place in the same method step.
7. The method of claim 1, wherein at least one of the cutouts is produced after roll forming.
8. The method according to claim 1, wherein all of the cutouts are produced before roll forming, preferably so that after roll forming the bipolar plate is completely formed in the material web.
9. Method according to one of the preceding claims, wherein the categorisation of the breakouts to be produced in the roll-to-roll, roll-to-sheet or roll-to-product process is carried out on the basis of their respective opening cross-sectional area into one of at least two categories, each of which is assigned an opening cross-sectional area range.
10. The method according to claim 9, wherein the opening cross-sectional area regions are non-overlapping or overlapping, but preferably not congruent and / or none of the regions is a true subset of at least one further one of the regions.
11. A method according to claim 9 or 10, wherein the roll-to-roll, roll-to-sheet or roll-to-product method is carried out for at least two of the at least two categories in different roll-to-roll, roll-to-sheet or roll-to-product units between which the material web is transported.
12. A method according to claim 11, wherein the production of the breakouts of a first of the categories is carried out in a first roll-to-roll, roll-to-sheet or roll-to-product unit which, in the material web feed direction, is roll-formed is located in front of it, wherein the first category is assigned to those of the plurality of cutouts with an opening cross-sectional area that is smaller than the opening cross-sectional areas of all the remaining cutouts.
13. The method according to claim 12, wherein the roll-to-roll, roll-to-sheet or roll-to-product method for a second of the categories to which the remaining sections are at least partially assigned is carried out in a second roll-to-roll, roll-to-sheet or roll-to-product unit which is arranged downstream of the first roll-to-roll unit in the material web feed direction.
14. The method according to claim 13, wherein the second roll-to-roll unit is arranged upstream or downstream of the roll forming in the material web feed direction.
15. The method according to claim 11, wherein the production of the cutouts of a first of the categories is carried out in a first roll-to-roll, roll-to-sheet or roll-to-product unit which is arranged downstream of the roll forming in the material web feed direction, wherein in particular those of the plurality of cutouts with an opening cross-sectional area which is smaller than the opening cross-sectional areas of all the remaining plurality of cutouts are assigned to the first category.
16. The method according to claim 15, wherein the roll-to-roll, roll-to-sheet or roll-to-product method for a second of the categories to which the remaining sections are at least partially assigned is carried out in a second roll-to-roll, roll-to-sheet or roll-to-product unit which is located upstream or downstream of the first roll-to-roll unit in the material web feed direction.
17. Method according to one of the preceding claims, wherein the cutting out of the bipolar plate from the material web comprises the separation being carried out in a third roll-to-roll unit which is arranged downstream of the roll forming and all other roll-to-roll units in the material web feed direction.
18. Device for producing a bipolar plate, a unipolar plate, a separator plate or the like, preferably for carrying out the aforementioned method, wherein the device comprises the following functional units: at least one unwinder for providing a material web made of metal or graphite, or a material web based on a polymer; at least one roll forming unit for roll forming the material web; and at least one roll-to-roll, roll-to-sheet, or roll-to-product unit for roll punching or roll cutting the material web, wherein the roll-to-roll, roll-to-sheet, or roll-to-product unit is configured to produce a plurality of cutouts in a region of the material web formed during the roll forming or in a region arranged adjacent to this region.
19. Device according to claim 18, characterized in that the at least one roll-to-roll, roll-to-sheet or roll-to-product unit is arranged in front of the roll forming unit in the feed direction of the material web.
20. Device according to claim 18, characterized in that the at least one roll-to-roll, roll-to-sheet or roll-to-product unit is arranged downstream of the roll forming unit in the feed direction of the material web.
21. Electrolyzer comprising at least one bipolar plate, at least one unipolar plate and / or at least one separator plate, characterized in that the bipolar plate, the unipolar plate and / or the separator plate is manufactured by a method according to claims 1 to 17.