Fuel cell stack and electrochemical reactor

Abstract

The invention relates to a fuel cell stack (10) for an electrochemical reactor (11), having a first membrane electrode assembly (12), a first anode plate (21) having separators (30) between which channels (31) for conducting fuel (32) and coolant (33) are configured, and a second anode plate (22) having separators (30) between which channels (31) for conducting fuel (32) and coolant (33) are configured, wherein the first membrane electrode assembly (12) is arranged between the first anode plate (21) and the second anode plate (22) in a stacking direction (36) of the fuel cell stack (10), wherein the separators (30) each have a separator outer side (35) which is spaced apart from the channels (31), wherein the separator outer sides (35) of the first anode plate (21) and the second anode plate (22) which point towards one another are arranged in pairs stacked along the stacking direction (36), respectively, and the separator outer sides (35) of the first anode plate (21) and the second plate (22) which are directed away from one another are arranged in pairs stacked along the stacking direction (36), respectively. Furthermore, the invention relates to a fuel cell system (11) having at least one fuel cell stack (11) according to the invention.

Description

Technical Field

[0001] This invention relates to a fuel cell stack for an electrochemical reactor, the fuel cell stack having a first membrane electrode assembly, a first anode plate, and a second anode plate. The first anode plate has spacers with channels configured between the spacers for conducting fuel and coolant. The second anode plate has spacers with channels configured between the spacers for conducting fuel and coolant. The first membrane electrode assembly is arranged between the first and second anode plates in the stacking direction of the fuel cell stack, and the spacers each have an outer side spaced apart from the channels. Furthermore, this invention relates to an electrochemical reactor having a fuel cell stack. Background Technology

[0002] In the prior art, electrochemical reactors in the form of fuel cell systems are known. A fuel cell system is an electrochemical transducer in which hydrogen and oxygen are converted into water, electrical energy, and heat. To increase the power of the fuel cell system, repetitive units, particularly in the form of a stacked structure having a membrane electrode assembly (MEA) and bipolar plates, are stacked multiple times within the fuel cell stack of the fuel cell system. The electrochemical reaction takes place within the MEA. The bipolar plates ensure that the three media, namely fuel, air, and coolant, are guided to the MEA in a manner that ensures uniform distribution across the MEA.

[0003] Different construction schemes exist for the stacking structure of fuel cell stacks. The so-called channel / land-strut structure (or Kanal / Steg-Strut) is known first. Figure 5 In the system shown, the bipolar plate consists of two corrugated stamped plates forming three channels or channel types through which three process fluids, namely hydrogen, water, and coolant, are conducted. Two adjacent bipolar plates with membrane electrode assemblies located between them are always arranged such that spacers are positioned adjacent to each other and channels are positioned adjacent to each other or via the membrane electrode assemblies. Additionally, a structural configuration is known that has an open, porous gas distributor on the respective cathode side of the membrane electrode assembly. Figure 6In the structure shown, similarly corrugated stamped plates are used to conduct hydrogen and coolant. However, these plates are not arranged directly against each other, but are separated from each other by a flat separator plate and an open porous gas distributor through which air is passed. That is to say, in this implementation variation, the corrugated cathode plate is replaced by a separator plate and an open porous gas distributor, respectively. A danger exists in this system: when the membrane electrode assembly is laid flat on the open porous structure from below, the spacers of the anode-side plate press against the membrane electrode assembly. If pressure is now vented laterally through the anode-side plate into the porous structure until the next spacer of the cathode-side plate, a danger arises: the thin separator plate arches and thus reduces the cross-section of the coolant channel located below it. This leads to increased pressure loss and therefore a decrease in the coolant volumetric flow rate in the fuel cell stack. In addition, due to pressure, the membrane electrode assembly can bend into the hydrogen channel and narrow the hydrogen channel, which can result in a corresponding reduction in the hydrogen volumetric flow rate during fuel cell system operation. Summary of the Invention

[0004] Within the framework of this invention, a fuel cell stack and an electrochemical reactor are provided, the fuel cell stack and the electrochemical reactor having a stacking structure that improves the stability of the fuel cell stack. In particular, a fuel cell stack and an electrochemical reactor are proposed. Further embodiments of the invention are derived from the specification and accompanying drawings. Here, the features described in the context of a fuel cell stack are of course also applicable in the context of a reactor according to the invention, and vice versa, so that the disclosures of various aspects of the invention are always mutually referenced and / or mutually referential.

[0005] According to a first aspect of the invention, a fuel cell stack for an electrochemical reactor is provided. The fuel cell stack has a first membrane electrode assembly, a first anode plate, and a second anode plate. The first anode plate has spacers with channels configured between the spacers for conducting fuel and coolant. The second anode plate has spacers with channels configured between the spacers for conducting fuel and coolant. Viewed in the stacking direction of the fuel cell stack, the first membrane electrode assembly is disposed between the first anode plate and the second gas anode plate. The spacers each have outer sides spaced apart from the channels. Viewed along the stacking direction, the outer sides of the first and second anode plates facing each other are stacked in pairs, and the outer sides of the first and second anode plates facing away from each other are stacked in pairs along the stacking direction.

[0006] Therefore, compared to known fuel cell stacks with gas diffusion layers and / or corresponding open porous oxygen distributor structures, each second anode plate is arranged in a direction perpendicular to the stacking direction with a staggered half-wavelength configuration, particularly in a wavy configuration. Through this arrangement and configuration of the anode plates according to the invention, the first membrane electrode assembly disposed between the first and second anode plates, and the gas distributor or corresponding open porous oxygen distributor structure also disposed between the first and second anode plates, are pressed together by two stacked spacers or two spacers pointing towards each other, without the membrane electrode assembly and / or gas distributor necessarily exerting forces laterally relative to the stacking direction. The resulting advantageous force flow prevents the separator plate disposed between the second anode plate and the gas distributor from arching into the coolant passage. Furthermore, it prevents the membrane electrode assembly from arching into the fuel passage as described above. Here, the anode plate should not be understood as part of the anode electrode of the membrane electrode assembly, but rather as a fluid conduction plate on the anode side of the corresponding fuel cell, particularly configured as part of a bipolar plate.

[0007] The first and second anode plates are arranged in pairs, stacked along the stacking direction, with their outer septa pointing towards each other. This can be understood as the outer septa of the first anode plate pointing towards the outer septa of the second anode plate and / or aligned with the outer septa of that septa being positioned above or below the outer septa of the second septa, respectively, in the stacking direction. The overlapping positioning of the outer septa should be understood in particular as direct stacking and / or at least partially aligned stacking. Specifically, the corresponding end sections pointing towards and / or away from the outer septa of each other can be aligned along the stacking direction. However, direct stacking here does not mean that the two outer septa are in contact with each other. More precisely, a membrane electrode assembly, a gas distributor, and a separator plate are arranged between the two outer septa. The outer septa should be understood in particular as the side of the corresponding septa that does not point into the associated channel but points away from it. Therefore, the outer septa of the anode plates can be understood as the anode plate contact sides, which are in contact with the separator plate or the anode electrode, respectively. Therefore, each anode plate may have a separator plate separator outer side that contacts the corresponding separator plate and an anode electrode separator outer side that contacts the corresponding anode electrode. The stacking direction can be understood as a direction along the y-axis through the fuel cell stack. Here, the stacking direction and / or the y-axis extends particularly along or parallel to the normal vector of the separator outer side. The same applies in a similar manner to the separator outer sides of the first and second anode plates, which, when viewed along the stacking direction, are arranged in pairs, i.e., particularly directly stacked and / or at least partially aligned.

[0008] The outer surfaces of the spacers preferably have flat or substantially flat surfaces. The spacers having outer surfaces spaced apart from the channels can be understood as follows: the outer surfaces of the spacers are not configured and / or positioned for forming the channel structure and / or channel geometry. The arrangement of the first membrane electrode assembly between the first anode plate and the second anode plate in the stacking direction of the fuel cell stack should not be construed as limiting the arrangement to only the first membrane electrode assembly between the first anode plate and the second anode plate in the stacking direction of the fuel cell stack. More precisely, viewed in the stacking direction of the fuel cell stack, other functional components, such as separator plates and gas distributors according to this category, may be positioned between the first anode plate and the second anode plate, in addition to the membrane electrode assembly.

[0009] In the fuel cell stack according to the invention, at least a portion of the spacers of the first anode plate may be disposed on the first anode electrode, and / or at least a portion of the spacers of the second anode plate may be disposed on the second anode electrode. The anode plate has spacers with channels configured between the spacers for conducting fuel and coolant; more particularly, it should be understood that the anode plate has spacers with channels configured between the spacers for conducting fuel and coolant and channels spaced apart from these channels for conducting coolant.

[0010] Fuel cell stacks are specifically configured for use in fuel cell systems, but can also be used in electrolysis units and / or fuel cell systems capable of reversible operation.

[0011] According to another embodiment of the invention, in a fuel cell stack, the stacking direction corresponds to the y-axis, and the second anode plate is arranged such that it is rotated 180° relative to the first anode plate about the y-axis. Viewed separately from the fuel cell stack, the first and second anode plates can thus have the same configuration. This results in low production costs. Here, one outer channel or edge-side channel of the first anode plate can be configured to conduct coolant, and another outer channel or edge-side channel of the first anode plate can be configured to conduct fuel. Furthermore, one edge-side channel of the second anode plate can be configured to conduct coolant, and another edge-side channel of the second anode plate can be configured to conduct fuel. The outer channel or edge-side channel should be understood in particular as the last and / or outermost channel of the respective anode plate.

[0012] Furthermore, in the fuel cell stack according to the invention, the stacking direction corresponds to the y-axis, and the second anode plate is arranged such that it is rotated 180° relative to the first anode plate about its associated x-axis. The x-axis extends perpendicular to the y-axis or the stacking direction and perpendicular to or parallel to the channel direction or the diaphragm direction. Therefore, viewed separately from the fuel cell stack, the first and second anode plates can also have the same configuration and can be produced cost-effectively accordingly. According to this configuration variation, the outer channel of the first anode plate can be configured to conduct coolant, and the outer channel of the second anode plate can be configured to conduct fuel. To prevent damage to the fuel cell stack and / or a reduction in the power of the fuel cell stack, the outer channel of the anode plate can be configured and / or configured as an empty channel for conducting and / or guiding ambient air, and the anode plate does not guide coolant into the outer channel.

[0013] Furthermore, in the fuel cell stack according to the invention, the first and second anode plates each have a wavy cross-section, and the channels each have a trapezoidal or substantially trapezoidal cross-section. In the present context, a trapezoidal or substantially trapezoidal cross-section should be understood in particular as a trapezoidal cross-section without sharp corners, but with small rounded corners, possibly due to manufacturing processes. This trapezoidal shape allows for a sufficiently large outer septum in the fuel cell stack to provide the desired stability while simultaneously providing the channel structure. The anode plates may have a uniform wavy shape and / or trapezoidal shape with correspondingly unchanged wavy segments and / or trapezoidal segments. However, it may also be advantageous for the anode plates to form uniform channels for conducting fuel and uniform channels for conducting coolant, wherein the channels for conducting fuel have a different cross-section than the channels for conducting coolant. Therefore, according to a configurational variation of the invention, the channels for conducting fuel are arranged along the stacking direction and, when viewed in cross-section of the fuel cell stack, above the channels for conducting coolant.

[0014] In addition, the fuel cell stack according to the present invention may include a second membrane electrode assembly, a first gas distributor, a second gas distributor, a first separator plate, and a second separator plate. The second membrane electrode assembly has a second anode electrode and a second cathode electrode. The first gas distributor is used to conduct air through the fuel cell stack, and the second gas distributor is used to conduct air through the fuel cell stack. The first membrane electrode assembly has a first anode electrode and a first cathode electrode. A first anode plate is disposed between the first separator plate and the first anode electrode, a second anode plate is disposed between the second separator plate and the second anode electrode, and the second gas distributor is disposed between the first cathode electrode and the second separator plate. The separator plate ensures electrical separation in the fuel cell stack and also contributes to the stability of the fuel cell stack. The separator plates may each have a thickness in the range of 75 μm to 100 μm. Furthermore, in such embodiments, it is possible that the outer sides of the spacers on the first anode plate disposed on the first anode electrode and the outer sides of the spacers on the second separator plate of the second anode plate face each other. Alternatively, the outer sides of the spacers on the first separator plate and the outer sides of the spacers on the second anode electrode of the second anode plate face away from each other.

[0015] Furthermore, the fuel cell stack according to the invention may have a third membrane electrode assembly, a third anode plate, a third gas distributor, and a third separator plate. The third membrane electrode assembly has a third anode electrode and a third cathode electrode. The third anode plate has spacers with channels configured between the spacers for conducting fuel and coolant. The third gas distributor is used to conduct air through the fuel cell stack. The third anode plate is arranged between the third separator plate and the third anode electrode, and the third gas distributor is arranged between the second anode electrode and the third separator plate. The outer sides of the spacers on the second anode plate and the outer sides of the spacers on the third anode plate of the third anode plate point towards each other, and / or the outer sides of the spacers on the second separator plate and the outer sides of the spacers on the third anode plate of the third anode plate point away from each other.

[0016] According to another aspect of the invention, an electrochemical reactor having a fuel cell stack as described above is provided. Therefore, the reactor according to the invention provides the same advantages as those described in detail with reference to the fuel cell stack according to the invention. Attached Figure Description

[0017] Further improvements to the invention can be derived from the following description of various embodiments of the invention, which are schematically illustrated in the accompanying drawings. All features and / or advantages derived from the specification or drawings, including structural details and spatial arrangements, may be important to the invention, either individually or in different combinations.

[0018] The attached figures schematically illustrate: Figure 1 A fuel cell stack according to a first embodiment of the present invention is shown. Figure 2 The first anode electrode and the rotated second anode electrode are shown according to a first embodiment variant. Figure 3 The first anode electrode and the rotated second anode electrode are shown according to the second embodiment variant. Figure 4 An electrochemical reactor having a fuel cell system according to the present invention is shown. Figure 5 This illustrates a fuel cell stack known in the prior art. Figure 6 This illustrates another fuel cell stack known in the prior art. Detailed Implementation

[0019] Components with the same function and mode of operation are respectively given the same reference numerals in the accompanying drawings.

[0020] exist Figure 1 The diagram illustrates a preferred embodiment for use in Figure 4 The image shows a segment of a fuel cell stack 10 of an electrochemical reactor 11. The fuel cell stack 10 has a first membrane electrode assembly 12, a second membrane electrode assembly 13, and a third membrane electrode assembly 14. The first membrane electrode assembly has a first anode electrode 15 and a first cathode electrode 18; the second membrane electrode assembly has a second anode electrode 16 and a second cathode electrode 19; and the third membrane electrode assembly has a third anode electrode 17 and a third cathode electrode 20. Furthermore, the fuel cell stack 10 includes a first anode plate 21, a second anode plate 22, and a third anode plate 23. The first anode plate has spacers 30 with channels 31 configured between the spacers for conducting fuel 32 and coolant 33. The second anode plate has spacers 30 with channels 31 configured between the spacers for conducting fuel 32 and coolant 33. The third anode plate has spacers 30 with channels 31 configured between the spacers for conducting fuel 32 and coolant 33. In addition, the fuel cell stack 10 has a first gas distributor 24, a second gas distributor 25, and a third gas distributor 26 for conducting air 34 through the fuel cell stack 10. Gas distributors 24, 25, and 26 are configured as open, porous gas distributor layers. Furthermore, the fuel cell stack has a first separator plate 27, a second separator plate 28, and a third separator plate 29.

[0021] Viewed in the stacking direction 36 of the fuel cell stack 10, the first membrane electrode assembly 12 is disposed between the first anode plate 21 and the second gas distributor 25. The second membrane electrode assembly 13 is disposed between the second anode plate 22 and the third gas distributor 26. The third membrane electrode assembly 14 is disposed between the third anode plate 23 and another gas distributor (not shown). The first anode plate 21 is disposed between the first separator plate 27 and the first anode electrode 15, and the second anode plate 22 is disposed between the second separator plate 28 and the second anode electrode 16. The third anode plate 23 is disposed between the third separator plate 29 and the third anode electrode 17. The first gas distributor 24 is disposed between a cathode electrode (not shown) and the first separator plate 27. The second gas distributor 25 is disposed between the first cathode electrode 18 and the second separator plate 28. The third gas distributor 26 is disposed between the second cathode electrode 19 and the third separator plate 29.

[0022] The spacers 30 are spaced apart from the channel 31 or have outer spacer sides 35 outside the channel 31. According to the illustrated embodiment, the outer spacer sides 35 of the first anode plate 21 and the second anode plate 22, facing each other, are stacked in pairs along the stacking direction 36 or along the normal vector of the outer spacer sides 35. Furthermore, viewed along the stacking direction 36, the outer spacer sides 35 of the first anode plate 21 and the second anode plate 22, facing away from each other, are stacked in pairs. Additionally, the outer spacer sides 35 of the second anode plate 22 arranged on the second anode electrode 16 and the outer spacer sides 35 of the third anode plate 23 arranged on the third separator plate 29 face each other. The outer spacer sides 35 of the second anode plate 22 arranged on the second separator plate 28 and the outer spacer sides 35 of the third anode plate 23 arranged on the third anode electrode 17 face away from each other. The outer sides 35 of the spacers on the first anode plate 21 and the second anode plate 22, which are arranged on the second separator plate 28, point towards each other. The outer sides 35 of the spacers on the first anode plate 21 and the second anode plate 22, which are arranged on the second separator plate 27, point away from each other. The layered structure shown generates a force flow F, which can be efficiently discharged through the anode plates 21, 22, and 23 to prevent warping of the separator plates 27, 28, and 29. Figure 1 As shown, each pair of outer sides 35 of the partitions facing each other has two other pairs of outer sides 35 of the partitions facing away from each other, and vice versa.

[0023] According to the illustrated embodiment, the anode plates 21, 22, and 23 shown each have a wavy cross-section, and the channels 31 each have a trapezoidal cross-section. The channels 31 for conducting fuel 32 are arranged along the stacking direction 36 and above the channels 31 for conducting coolant 33 when viewed in cross-section of the fuel cell stack 10.

[0024] Next, refer to Figure 2 This describes a configuration variation of the anode plate that can be used in a different position within the fuel cell stack 10 than the first anode plate 21, the second anode plate 22, and other anode plates in the additional stacked layers. Figure 2 The anode plate, positioned above, is shown as the first anode plate 21. This same plate can be used as a second anode plate 22 if it is now rotated 180° about the y-axis or about the axis along the stacking direction 36. Figure 2 As shown, the first anode plate 21 is configured to conduct fuel 32 through the left outer channel 31 and coolant 33 through the right outer channel 31. The rotated second anode plate 22 is configured to conduct fuel 32 through the right outer channel 31 and coolant 33 through the left outer channel 31.

[0025] Reference Figure 3 Another configuration variation of the anode plate is described, which can be used in the fuel cell stack 10 in a different position than the first anode plate 21, the second anode plate 22, and other anode plates in the additional stacked layers. Figure 3 The anode plate, shown above, serves as the first anode plate 21. If the same plate is now rotated 180° about an x-axis perpendicular to the y-axis, it can be used as a second anode plate 22. Figure 3 As shown, the first anode plate 21 is configured to conduct fuel 32 through the left outer channel 31 and coolant 33 through the right outer channel 31. The rotatable second anode plate 22 is configured to conduct coolant 33 through both the right outer channel 31 and the left outer channel 31.

[0026] exist Figure 5 and 6 The image shows fuel cell stacks 10a and 10b, which have already been described at the beginning and are known in the prior art. Figure 5 In the illustrated embodiment, air 34 is conducted within the channel structure of the cathode plate 37. Besides the illustrated embodiment, the invention allows for other design principles. That is, the invention should not be considered limited to the embodiments described with reference to the accompanying drawings.

Claims

1. A fuel cell stack (10) for an electrochemical reactor (11), the fuel cell stack having: - First membrane electrode assembly (12). - A first anode plate (21) having septa (30) between which channels (31) are configured for conducting fuel (32) and coolant (33). - A second anode plate (22) having septa (30) between which channels (31) are configured for conducting fuel (32) and coolant (33). - Second membrane electrode assembly (13), the second membrane electrode assembly having a second anode electrode (16) and a second cathode electrode (19). - A first gas distributor (24) for conducting air (34) through the fuel cell stack (10). - A second gas distributor (25) for conducting air (34) through the fuel cell stack (10). - First separator plate (27), and - Second separator plate (28). - in, The first membrane electrode assembly (12) is arranged in the stacking direction (36) of the fuel cell stack (10) between the first anode plate (21) and the second anode plate (22), wherein the spacers (30) have outer sides (35) spaced apart from the channels (31). The first membrane electrode assembly (12) has a first anode electrode (15) and a first cathode electrode (18). The first anode plate (21) is arranged between the first separator plate (27) and the first anode electrode (15). The second anode plate (22) is arranged between the second separator plate (28) and the second anode electrode (16). The second gas distributor (25) is arranged between the first cathode electrode (18) and the second separator plate (28). in, The first anode plate (21) and the second anode plate (22) are arranged in pairs along the stacking direction (36) with their outer sides (35) facing each other. The first anode plate (21) and the second anode plate (22) are arranged in pairs along the stacking direction (36) with their outer sides (35) away from each other.

2. The fuel cell stack (10) according to claim 1. Its features are, The stacking direction (36) corresponds to the y-axis, and the second anode plate (22) is arranged in such a way that it is rotated 180° relative to the first anode plate (21) about the y-axis.

3. The fuel cell stack (10) according to claim 1. Its features are, The stacking direction (36) corresponds to the y-axis, and the second anode plate (22) is arranged in such a way that it is rotated 180° relative to the first anode plate (21) about the associated x-axis.

4. The fuel cell stack (10) according to any one of claims 1 to 3. Its features are, The first anode plate (21) and the second anode plate (22) each have a wavy cross-section, and the channel (31) each has a trapezoidal cross-section.

5. The fuel cell stack (10) according to any one of claims 1 to 3. Its features are, The channels (31) for conducting fuel (32) are arranged along the stacking direction (36) and above the channels (31) for conducting coolant (33) when viewed in cross-section of the fuel cell stack (10).

6. The fuel cell stack (10) according to any one of claims 1 to 3. Its features are, The outer side (35) of the septum of the first anode plate (21) arranged on the first anode electrode (15) and the outer side (35) of the septum of the second anode plate (22) arranged on the second separator plate (28) point toward each other.

7. The fuel cell stack (10) according to any one of claims 1 to 3. Its features are, The outer side (35) of the septum of the first anode plate (21) arranged on the first separator plate (27) and the outer side (35) of the septum of the second anode plate (22) arranged on the second anode electrode (16) point away from each other.

8. The fuel cell stack (10) according to any one of claims 1 to 3. Its features are, - A third membrane electrode assembly (14), which has a third anode electrode (17) and a third cathode electrode (20). - A third anode plate (23) having septa (30) between which channels (31) are configured for conducting fuel (32) and coolant (33). - A third gas distributor (26), which is used to conduct air (34) through the fuel cell stack (10), and - Third separator plate (29), wherein - The third anode plate (23) is arranged between the third separator plate (29) and the third anode electrode (17), and the third gas distributor (26) is arranged between the second cathode electrode (19) and the third separator plate (29), wherein, - The outer side (35) of the septum of the second anode plate (22) arranged on the second anode electrode (16) and the outer side (35) of the septum of the third anode plate (23) arranged on the third separator plate (29) point toward each other, and / or the outer side (35) of the septum of the second anode plate (22) arranged on the second separator plate (28) and the outer side (35) of the septum of the third anode plate (23) arranged on the third anode electrode (17) point away from each other.

9. An electrochemical reactor (11) having a fuel cell stack (10) according to any one of claims 1 to 8.

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