Dispenser arrangement for electrochemical cell, electrolysis device and electricity-to-X device

Abstract

The invention relates to a distributor arrangement (10) for an electrochemical cell (30) for supplying a cell element (1) with a fluid medium (M). The invention relates to a distributor arrangement comprising a fluid inlet (11) branched into N distributor stages, in which a distributor channel (12) is divided in the main flow direction (S) from one stage (K) to the next stage (K + 1) into two channels with smaller cross-section, and in which the distributor channel (12) is divided into two channels with smaller cross-section from one stage (K) to the next stage (K + 1). The distributor channels (12) of the Nth stage of the distributor structure (10) are designed to distribute the fluid medium (M) uniformly over the width of the battery element (1). The invention further relates to an electrolysis device having a distributor structure or to a corresponding component lighting device.

Description

Technical Field

[0001] The invention relates to a distributor structure for an electrochemical cell, in particular an electrolysis device, for supplying a fluid medium to one or more cell components. In addition, a corresponding electrolysis device and a corresponding electro-X device are the subject matter of the invention. Background Art

[0002] The fluid medium can be, in particular, a gas and / or a liquid, in particular an electrolyte, a catalyst, an analyte or an educt for the operation of the relevant electrochemical cell.

[0003] In electrolysis, in particular the electrolysis of water (H2) or CO or CO2, and in fuel cells, the incoming fluid stream must be distributed as evenly as possible over the width of the active cell in order to be able to achieve and maintain the electrochemical reaction, i.e. the introduction of fresh medium and the discharge of used medium, over the entire surface (e.g., on an ion or proton exchange membrane). Only a uniform supply of medium or a uniform introduction and / or discharge of the medium over the entire membrane surface allows a uniform current density to be achieved. While maintaining the maximum permissible current density (which depends on the respective membrane), the overall power of the cell can be maximized without local overloading and the associated premature aging.

[0004] It is particularly advantageous here to increase the flow resistance of the distributor channel as much as possible at least downstream in the vicinity of the active cells in order in particular to prevent or significantly reduce parasitic currents. Summary of the invention

[0005] It is therefore an object of the present invention, in particular, to provide an improved, homogeneous medium distribution for an electrochemical cell which simultaneously allows a design of the component having the cell to be as robust and compact as possible.

[0006] This object is achieved by the subject matter of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.

[0007] One aspect of the invention relates to a distributor structure for an electrochemical cell, in particular a distributor structure for an electrolysis device for supplying a fluid medium to a cell element. The distributor structure comprises a fluid inlet, preferably a main channel for supplying or feeding a medium to the cell, wherein the fluid inlet branches into N, i.e. at least one, preferably a plurality of distributor stages, wherein the distributor channel divides into two or more channels of smaller cross-section from one stage to the next in the main flow direction or along the main flow direction (preferably in the direction of the cell). The distributor channels of the "Nth" stage are designed to distribute or feed the fluid medium uniformly (directly) over the width of the cell element to the electrochemically active part of the cell.

[0008] The advantages of the invention over the prior art are, in particular, that a compact construction can be improved while distributing the fluid substantially uniformly over the width of the cell. This in turn makes it possible to achieve a more robust electrochemical component with a greatly improved power density. Furthermore, the advantages of improved manufacturability result, and a cell stack having a plurality of cell elements can be supported or pressed against one another in a particularly stable mechanical manner.

[0009] In one design, the distributor channels of a stage (in particular of the same stage) preferably have substantially the same channel length along the main flow direction. This design advantageously enables the most uniform possible fluid distribution.

[0010] In a design, the distributor channels of a stage also have substantially equal channel widths and / or channel cross sections. Through this design, in particular, traditional manufacturing can be simplified, in particular by milling or plastic injection molding in plastic sheets.

[0011] In one design, the distributor structure is symmetrically constructed from its second level, in particular completely symmetrical. In this context, the axis of symmetry preferably refers to an axis parallel to the height of the distributor structure or battery element and perpendicular to its width. This design also helps to achieve the purpose of the fluid distribution according to the present invention as evenly as possible.

[0012] In one embodiment, the distributor channels are arranged evenly distributed over the cell width starting from the second stage, preferably also equidistantly. This embodiment can also advantageously achieve a fluid distribution that is as even as possible.

[0013] In one embodiment, the distributor structure is designed such that after a branch or at a transition from one stage to the next, its channel course or flow course is directed back in the main flow direction or is changed accordingly to this direction for guiding the fluid medium.

[0014] The channel course or the flow course therefore at least partially does not correspond completely to the main flow direction, but instead runs partially or locally perpendicularly to the latter direction after the branching.

[0015] In one design, the height of the distributor structure or the extension of the distributor structure in the main flow direction is less than half the width of the battery element. With this design, the distributor structure can be particularly advantageously kept compact and can be designed particularly robustly in conjunction with other features according to the invention.

[0016] In one design, during normal operation of the distributor structure, the relative standard deviation (relStd) or the corresponding coefficient of variance of the fluid velocity distribution relative to the arithmetic mean is less than 0.15. According to this design, the differences in flow velocities (velocity gradients and pressure gradients) can advantageously be kept small. The values ​​relate in particular to positions along the center plane of the channel, i.e. not at its edges (see the special embodiment of the invention described further below with the aid of the drawings).

[0017] In one design, the distributor structure has connecting channels between channel branches at the same level in the higher-level or finer branches, which extend substantially perpendicularly to the main flow direction, in particular transversely to or perpendicularly to this direction, and are designed to make the distribution of the fluid medium between the channel branches more uniform. Through these transverse connecting channels, the pressure difference or velocity distribution difference can be further reduced, so that the medium supply to the battery element can be further effectively made uniform.

[0018] In one design, the distributor structure is designed to guide liquid or aqueous electrolyte as the fluid medium to the cell elements. This design is particularly advantageous and beneficial for electrolyte supply in CO / CO2 electrolysis.

[0019] In an alternative design, the distributor structure is designed for water electrolysis or for supplying water as fluid medium to the cell elements.

[0020] In one design, the distributor structure can be manufactured by or by an additive manufacturing method. The fine branching of the channel and the provision of the channel by means of a plastic material can in particular advantageously be carried out in an additive manner. Additive manufacturing methods (AM: "additive manufacturing"), commonly known as 3D printing, include, for example, selective laser melting (SLM) or "fused deposition modeling" (FDM) as powder bed methods. Additive manufacturing methods have proven to be particularly advantageous for complex or finely designed components, such as labyrinth structures, cooling structures and / or lightweight structures. In particular, additive manufacturing is advantageous due to a particularly short chain of process steps, since the production or manufacturing steps of the component can be carried out primarily on the basis of a corresponding CAD file and the selection of corresponding manufacturing parameters.

[0021] Another aspect of the invention relates to an electrolysis device, which comprises a distributor structure for feeding or supplying a fluid medium to a cell element and a likewise, in particular identically designed, outlet structure for discharging the fluid medium. Thus, with respect to the main flow direction, the outlet structure can preferably be designed or oriented exactly oppositely in order to guide the fluid from the cell element likewise uniformly again into a possibly central separate outlet channel and discharge it.

[0022] Another aspect of the invention relates to a power-to-X device comprising the electrolysis device or the distributor structure. "Power-to-X" refers in particular to one or more technologies for storing or otherwise using excess power generated by an excess supply of renewable energy sources, such as solar, photovoltaic, wind and / or hydropower. In the present case, this excess power is in particular used to operate an electrochemical cell, preferably an electrolysis cell.

[0023] The present designs, features and / or advantages relating to the dispenser structure or the corresponding electrochemical cell may also be directly related to the electrolysis device or the electro-to-X device, and vice versa.

[0024] When the expression “and / or” or “or” used herein, when used with two or more elements, means that each of the elements described may be used alone or any combination of two or more elements described may be used. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further details of the invention will be described below with the aid of the accompanying drawings.

[0026] Figure 1 A schematic side or top view of a conventional distributor structure for an electrochemical cell is shown.

[0027] Figure 2 Shows that with Figure 1 Schematic diagram of a conventional electrochemical cell with a similar distributor structure.

[0028] Figure 3 An alternative design to the conventional distributor structure is shown.

[0029] Figure 4 A schematic diagram of a distributor structure for supplying a fluid medium to an electrochemical cell according to the present invention is shown.

[0030] Figure 5 A schematic diagram of a dispenser structure according to the invention is shown according to an alternative design.

[0031] Figure 6 An advantageously compact design of the dispenser structure according to the invention is shown.

[0032] Figure 7 A further advantageously compact embodiment of the distributor structure according to the invention is shown with transverse connecting channels.

[0033] Figure 8 A further advantageous design of the distributor structure according to the invention is shown.

[0034] Fig. 9A further advantageous design of the distributor structure according to the invention is shown.

[0035] Fig.10 A further advantageous design of the distributor structure according to the invention is shown.

[0036] Fig.11 A further advantageous design of the distributor structure according to the invention is shown.

[0037] Fig.12 The relative standard deviation of the simulated fluid velocity distribution of the distributor structure according to the present invention is shown in a graph. DETAILED DESCRIPTION

[0038] In these embodiments and drawings, identical or identically functioning elements may be marked with the same reference numerals. The illustrated elements and their size relationships to one another are not to be considered dimensionally accurate in principle, but individual elements may be shown thicker or larger in size for better representation and / or better understanding.

[0039] In the following description Figures 1 to 3 The present invention relates to a conventional medium distributor or distributor structure for an electrochemical cell. Figure 1 and Figure 2 In particular, the same design of a conventional medium distributor 10 ′ for an electrochemical cell, such as an electrolytic cell, is shown.

[0040] Figure 1 1 ' shows in particular such a distributor with a fluid inlet 11 '. Starting from the tubular medium inlet, a plurality of smaller channels 12 ' are fanned out to cover the battery width (see Figure 1 and Figure 2 The horizontal extension of the cells in the middle). Obviously, the longer channels have a larger cross section in order to obtain a flow resistance that is approximately equal or consistent with the other shorter channels. In this way, approximately the same volume flow or flow rate can be achieved.

[0041] Figure 2 An electrochemical cell 2' of the type described is schematically shown, comprising a distributor structure 10' for supplying a fluid medium (see reference numeral M below). In particular, a complete cell with fluid inlets and outlets on the anode side and cathode side of the membrane cell is shown. In particular, a distributor of the same kind is designed for the fluid or medium outlet (see reference numeral 3' in the lower part of the figure).

[0042] Currently using Figures 1 to 3 The structure shown can preferably be designed for supplying an electrolysis cell for water electrolysis and thus for supplying and conducting water to a (PEM) membrane.

[0043] Figure 3 An alternative to the conventional distributor design is shown, wherein the distributor can also consist of a section with a large cross section (and low flow resistance), with which the distribution is then carried out in width and in small identical channels (with correspondingly high flow resistance) branching off from it. The homogeneous small channels advantageously supply the individual battery sections in width. The flow resistance of the individual battery sections is here controlled by the small channels and is virtually constant over the entire width.

[0044] Such a distributor structure is suitable in principle for supplying fluids with a combination of low flow resistance and high flow resistance.

[0045] Both of the above-mentioned distributor variants are suitable for uniformly supplying batteries of relatively small widths. However, problems arise if larger battery widths must be supplied without the distributor structure having an excessively large vertical extension.

[0046] exist Figure 1 and Figure 2 In the variant shown, the ratio of the length of the longest supply channel to the shortest supply channel increases with increasing cell width. Since all channels branch from the same inlet, a correspondingly larger channel width ratio (or channel cross-section ratio) is required in order to equalize the flow resistance accordingly. In any case, for manufacturing reasons, the technical limit is reached for the smallest channel width.

[0047] exist Figure 3 In the second variant shown, for larger cell widths, the flow resistance for the portion distributed over the width is disadvantageously no longer negligible, or the difference between the portion close to the inlet and the portion arranged further away from the inlet is so great that a sufficiently uniform medium distribution cannot be achieved.

[0048] Support structure in Figure 3 In the figure, it is indicated by reference numeral 15 and is used to receive a plunger or a mechanical support. When observing the required fluid pressure of several bars, the mechanically stable support of each individual electrolytic cell can be clearly seen.

[0049] Figure 4 A distributor structure according to the invention is now presented which solves the above-mentioned technical problems and in particular enables a compact, robust and supply-efficient construction of an electrochemical cell using the distributor structure according to the subject matter of the invention.

[0050] Therefore, a distributor structure 10 for an electrochemical cell (e.g., an electrolysis device 30) is proposed, which is designed to supply a fluid medium M to a cell element 1 and comprises a fluid inlet 11, which branches into N distributor stages, wherein a distributor channel 12 is divided into two or more channels of smaller cross-section from one stage K to the next stage K+1 in the main flow direction S. In addition, the distributor channels 12 of the Nth stage of the distributor structure 10 are designed to distribute the fluid medium M particularly uniformly over the width B of the cell element 1.

[0051] The two downstream distributor channels of the first stage originate from the channel inlet 11 (see N=1, left side in the diagram). Therefore, in this stage, the distributor design (as shown in the figure) - in the case of supplying fluid to the cell for CO2 / CO electrolysis with liquid electrolyte - is slightly asymmetrical, because a completely symmetrical channel design is not feasible in terms of manufacturing technology. For this reason, the first stage (branch) is designed in this example with channels of different lengths and channel widths in order to obtain equal flow resistance in this section or to compensate for corresponding differences.

[0052] In this operating mode, according to which carbon dioxide is usually formed in the channels and must likewise be discharged via the outlet, production, strictly speaking, requires the conduction of a plurality of media, in particular the conduction of analytes, catalysts and gaseous media. By means of this example, the person skilled in the art also recognizes the practical difficulties, namely the stability over time. In this respect, gas bubbles can disadvantageously close small channels, which in turn can lead to inhomogeneities in the medium supply and the current density of the cell, and to corresponding degradation and premature aging.

[0053] After the first stage, in which the channel cross section is (still) relatively large, Figure 4 , a substantially symmetrical tree-like distributor structure is shown, which—shown as an example—branching into seven (N=7) stages, so that the fluid or medium to be conducted and distributed is then discharged uniformly to the active cell surface 1 .

[0054] The distribution channels 12 of each stage have here essentially the same channel length l (see Figure 5 This also applies in principle to the corresponding channel widths b or corresponding cross-sections in the present embodiment and in the embodiments described below, whereby a substantially equal flow resistance is obtained and a uniform fluid distribution over the cell width is also ensured.

[0055] Furthermore, the distributor channels 12 are distributed substantially uniformly over the battery width B starting approximately from the second level.

[0056] After or at the time of the branch 13 from the K≥2 stage to the K+1 stage, the electrolytic medium to be guided by the distributor structure advantageously does not strictly follow the main flow direction indicated by S. On the contrary, at the transition to the next (K+1) stage, the deflection of the channel 12 or the orientation of the corresponding flow M then again preferably occurs along the main flow direction S or parallel to the main flow direction S.

[0057] In this way, the distributor channel 12 branches from the second to the third level into four channels, from the third to the fourth level into eight channels, from the fourth to the fifth level into 16 channels, from the fifth to the sixth level into 32 channels, from the sixth to the seventh level into 64 channels, so that after the seventh level, there are finally 128 identical distributor channels for supplying the battery elements 1. In other words, the branching or multiplication of the distributor channels is carried out in powers of 2, where the exponent represents the number of levels and the power (for base 2) represents the number of channels of the last level in which the level is effective. Without limiting the generality and without departing from the basic concept of the invention, branching into, for example, three or more channels is also possible.

[0058] The velocity distribution of the fluid medium can be calculated and / or estimated by means of a fluid dynamics simulation (CFD), wherein the fluid dynamics are preferably assumed in the center plane of the channel (see depth in the illustrated plane and the coordinate system at the bottom left). It can be seen that the velocities (and thus the volume flow) in the channels are substantially equal. As a criterion, the relative (relative to the mean) standard deviation of the velocity in the center of the channel can be taken over all 128 channels. For such a structure (see Figure 4 , Figure 5 See also Fig.12 ), the standard deviation is relStd=0.0482.

[0059] and Figure 5 In contrast to the diagram, Figure 6 It is shown that when the above structure is compressed in terms of vertical extension to make the structure more compact, the velocity distribution becomes significantly non-uniform. Figure 6 The height H2 of the distributor structure is shown to be Figure 5 The height H1 of the structure in is correspondingly smaller (see the length of the arrow at the edge of the right figure).

[0060] A more compact technical design is thus achieved together with the speed profile Figure 6 This is also reflected by the significantly (factor 7) higher relative standard deviation of the velocity in the channel center, which is relStd=0.337 (see Fig.12 point "B" in the graph of ).

[0061] One reason for the greater scattering (inhomogeneity) in the fluid dynamics is that the vertical channel section, which is greatly shortened before the next branch, is not sufficient to also absorb the flow momentum in the horizontal direction. Therefore, the branch or channel section located in the flow direction, respectively, receives a larger share of the flow. One remedy is Figure 5 A variant has been shown in , which has an extension of the vertical extension, which however conflicts with the requirement for compact vertical dimensions.

[0062] Figure 6 In particular, a distributor structure 10 of a more complex construction or design is shown, namely a distributor structure in which the height H of the distributor structure is less than half the width of the battery element 1 .

[0063] According to an advantageous design of the distributor structure 10 of the present invention, the relative standard deviation of the fluid velocity distribution during normal operation of the distributor structure 10 is less than 0.34, preferably less than 0.15, and particularly preferably less than 0.1.

[0064] exist Figure 7 According to an exemplary embodiment of the invention, in this design, horizontally extending (transverse) connecting channels are introduced, in particular between the channels of the last and seventh stages, in order to further homogenize the distribution. Figure 7 The relative standard deviation is relStd = 0.137 (see Fig.12 point “C” in the graph).

[0065] The subsequent figures also show the results of further CFD simulations with the fluid paths highlighted in the figures, and the parameters (flow rate and fluid properties) are exactly the same as those in the previous simulations and examples.

[0066] In the following Figures 7 to 10 In the design variant mentioned, in the distribution area of ​​the lower and lower levels, other transverse connecting channels 14 are successively introduced into the branching level. In other words, the fluid connection is designed to rise step by step between adjacent branches of the distributor channel 12 of the same level, which can advantageously compensate for the pressure gradient or flow gradient when supplying the battery element 1.

[0067] Figure 8 The transverse connecting passages 14 in the seventh and sixth stages are shown. Figure 8 The relative standard deviation is relStd=0.10 (see Fig.12 point “D” in the graph of ).

[0068] Fig. 9 The transverse connecting channels 14 in the seventh, sixth and fifth stages are shown. Fig. 9 The relative standard deviation is relStd = 0.0834 (see Fig.12 point “E” in the graph).

[0069] Fig.10 The transverse connecting channels 14 in the seventh, sixth, fifth and fourth stages are shown. Fig.10 The relative standard deviation is relStd = 0.0781 (see Fig.12 point "F" in the graph).

[0070] according to Fig.11 The relative standard deviation of the velocity distribution is relStd = 0.0749 (see Fig.12 The point "G" in the diagram of ( ) is most conducive to achieving the goal of uniform medium distribution according to the present invention. Here, starting from the seventh stage, the connecting channel 14 exists in five immediately adjacent lower stages (towards upstream).

[0071] As a rule of thumb, through the lateral passage in the seventh level (see Fig.10 ) achieves the most significant improvement in uniformity. However, all other additionally provided transverse channels also lead to a further improvement in the uniformity of the velocity distribution and thus to an improvement in the medium supply over the entire cell width.

[0072] However, according to the concept of the invention, the channels 14 extending horizontally or transversely to the main flow S do not necessarily have to be provided in every branch, but this may in principle be necessary for the flow distribution.

[0073] For the cell dimensions described herein, an exemplary cell width is assumed to be approximately 1.40 m x 1.40 m in height (and width) and there are 2 7 = 128 distributor channels 12. This results essentially in a channel cross section of slightly more than 10 mm.

[0074] As described above, the distributor structure 10 can be designed to supply liquid electrolyte as a fluid medium to the battery element 1 (see the above-mentioned Figures 1 to 3 ).

[0075] Alternatively, the distributor structure 10 may be designed to supply water as the fluid medium to the battery element 1 for water electrolysis.

[0076] Another aspect of the invention relates to an electrolysis device 30 comprising a distributor structure 10 for supplying a fluid medium M into the cell element 1 and a likewise designed output structure 20 for discharging the fluid medium M (see Fig.11 ).

[0077] Another aspect of the invention relates to a power-to-X plant 100 comprising an electrolysis device 30. For the conversion of a large part or all of the energy supply system to a maximum proportion of renewable energy in the course of necessary decarbonization measures, a corresponding power-to-X technology is essential, which can in particular compensate for a surplus of partially renewable energy or smooth out fluctuations in such a way that the surplus energy can be used in response to produce green or synthetic fuels. For example, a bundle of approximately 100 (in the plane of the drawing) elements 1 arranged side by side is characteristic of a so-called "stack" of electrolysis cells used in a power-to-X plant.

[0078] Another aspect of the invention relates to the design of a dispenser structure produced by an additive manufacturing method, which can provide an advantageous alternative to conventional production by milling from a plastic sheet or by plastic injection molding, for example.

Claims

1. A distributor structure (10) for an electrochemical cell (30), the distributor structure being used to supply a fluid medium (M) to a cell element (1), the distributor structure comprising a fluid inlet (11) which branches into N distributor stages, wherein: The distributor channel (12) is divided into two channels with smaller cross-sections from one level (K) to the next level (K+1) in the main flow direction (S), and wherein the distributor channel (12) of the Nth level of the distributor structure (10) is designed to evenly distribute the fluid medium (M) over the width (B) of the battery element (1).

2. The distributor structure (10) according to claim 1, wherein: The distributor channels of a stage have substantially the same channel length (l).

3. The distributor structure (10) according to claim 1 or 2, wherein: The distributor channels of a stage have substantially the same channel width (b).

4. The distributor structure (10) according to any one of the preceding claims, wherein: The distributor structure is symmetrical starting from its second stage.

5. The distributor structure (10) according to any one of the preceding claims, wherein: Starting from the second level, the distributor structures are arranged evenly distributed over the cell width (B).

6. A distributor structure (10) according to any one of the preceding claims, wherein: The channel course of the distributor structure (10) is directed again in the direction of the main flow direction (S) after branching off (13) from one stage (K≥2) to the next stage (K+1).

7. A distributor structure (10) according to any one of the preceding claims, wherein: The height (H) of the distributor structure is less than half the width of the battery element (1).

8. The distributor structure (10) according to claim 7, wherein: During normal operation of the distributor structure (10), the relative standard deviation of the fluid velocity distribution is less than 0.

15.

9. A distributor structure (10) according to any one of the preceding claims, which has a connecting channel (14) between channel branches at the same level in a higher level, wherein the connecting channel extends substantially perpendicular to the main flow direction (S), and the connecting channel is designed to uniformly distribute the fluid medium (M) between the channel branches.

10. The distributor structure (10) according to any of the preceding claims, which is designed to supply a liquid electrolyte as fluid medium to the battery element (1).

11. The distributor structure (10) according to any one of claims 1 to 9, which is designed to supply water as a fluid medium to the cell element (1) for water electrolysis.

12. The dispenser structure (10) according to any one of the preceding claims, which is manufactured by an additive manufacturing method.

13. An electrolysis device (30), comprising a distributor structure (10) according to any of the preceding claims and an output structure (20) designed in the same manner, wherein the distributor structure is used to supply a fluid medium (M) into a battery element (1), and the output structure is used to discharge the fluid medium (M).

14. An electro-to-X device (100) comprising the electrolysis device (30) according to claim 13.

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