CN220086112U - Fuel cell stack - Google Patents

Abstract

The present utility model proposes a fuel cell stack comprising a cell assembly having a pair of end bipolar plates at both ends thereof and provided with a plurality of common channels, stacked together, and a pair of end assemblies located outside the cell assembly, each end assembly comprising a current collecting plate and a separator plate, wherein a pair of separator assemblies are further included, one separator assembly being provided between the end bipolar plates and the end assemblies at each side, the separator assemblies comprising: a base plate made of the same material as the end bipolar plate, the base plate being provided with a plurality of duct openings aligned with the plurality of common ducts, respectively, such that each common duct extends to the separator plate, the end bipolar plate being provided with a rubber seal coating surrounding each common duct, respectively, and pressing against the base plate; and a plurality of rubber seals surrounding each common pipe and sandwiched between the base plate and the partition plate, respectively.

Description

Fuel cell stack

Technical Field

The utility model relates to the technical field of fuel cells, in particular to a fuel cell stack.

Background

A fuel cell stack is a core component of a fuel cell, and generally includes a cell assembly formed by stacking a plurality of cells, a pair of current collecting plates located outside the cell assembly, and a pair of separator plates located outermost, in which a plurality of common pipes for transporting a medium (including fuel, oxidant, coolant, etc.) are formed, and communicate with the outside through one separator plate so as to receive or discharge the medium. In order to prevent leakage of the medium between the end bipolar plates and the separator plates of the cell combination, sealing for the respective common ducts needs to be performed between the end bipolar plates and the separator plates. In the prior art, the sealing is achieved by means of rubber sealing coatings applied to the end bipolar plates, which are clamped between the end bipolar plates and the separator plates. However, this presents the problem that the fuel cell stack is subjected to a large difference between its ambient temperature and its operating temperature, and therefore will experience a large temperature change during start-up, and the bipolar plates and separator plates will exhibit different rates of expansion due to their different materials, which will result in a relative displacement of the bipolar plates and separator plates which will exert a large shear force on the rubber sealing coating and even tear the rubber sealing coating, resulting in seal failure for the individual common channels.

Accordingly, there is a need in the art for a solution that maintains a good seal between the end bipolar plates and separator as temperature changes.

Disclosure of Invention

In order to solve the above-mentioned problems in the prior art, the present utility model proposes a fuel cell stack including a cell assembly having a pair of end bipolar plates at both ends thereof and provided with a plurality of common pipes, stacked together, and a pair of end members located outside the cell assembly, each end member including a collector plate and a separator plate, wherein the fuel cell stack further includes a pair of separator members, one separator member being provided between each side of the end bipolar plates and the end members, the separator members comprising: a base plate made of the same material as the end bipolar plate, the base plate being provided with a plurality of duct openings aligned with the plurality of common ducts, respectively, such that each common duct extends to the separator plate, the end bipolar plate being provided with a rubber seal coating surrounding each common duct, respectively, and pressing against the base plate; and a plurality of rubber seals surrounding each common pipe and sandwiched between the base plate and the partition plate, respectively.

According to an alternative embodiment of the utility model, each isolation assembly further comprises: a first conductive member electrically connecting the substrate with the end bipolar plate; and a second conductive member electrically connecting the substrate and the current collecting plate.

According to an alternative embodiment of the utility model, the first conductive member is constituted by a gas diffusion layer and is sandwiched between the substrate and the end bipolar plate; and/or the second conductive member is composed of a gas diffusion layer and is sandwiched between the substrate and the current collecting plate.

According to an alternative embodiment of the utility model, the first conductive member is located within an area defined by a flow field area of the end bipolar plate; and/or the second conductive member is located within an area defined by the current collecting plate.

According to an alternative embodiment of the utility model, each rubber sealing ring is glued to the base plate along its entire turn.

According to an alternative embodiment of the utility model, each rubber sealing ring is provided with a rubber lug protruding radially therefrom, each rubber lug being glued to the base plate.

According to an alternative embodiment of the utility model, the thickness of the rubber lugs is smaller than the thickness of the rubber sealing ring.

According to an alternative embodiment of the utility model, each spacer assembly further comprises a support plate clamped between the base plate and the spacer plate, the support plate being provided with a first opening for the passage of the plurality of rubber sealing rings and a second opening for the passage of the second conductive element.

According to an alternative embodiment of the utility model, the support plate and the base plate are made of the same material.

According to an alternative embodiment of the utility model, the first opening is radially enlarged with respect to the plurality of rubber sealing rings and the second opening is radially enlarged with respect to the second conductive member.

The utility model may be embodied in the form of illustrative embodiments shown in the drawings. It should be noted, however, that the drawings are merely illustrative and that any variations contemplated under the teachings of the present utility model are considered to be included within the scope of the present utility model.

Drawings

The drawings illustrate exemplary embodiments of the utility model. The drawings should not be construed as necessarily limiting the scope of the utility model, wherein:

fig. 1 is a schematic exploded perspective view of a fuel cell stack according to the present utility model;

FIG. 2 is a schematic cross-sectional view of an isolation assembly of the fuel cell stack shown in FIG. 1; and

fig. 3 is a schematic exploded perspective view of the isolation assembly shown in fig. 2.

Detailed Description

Further features and advantages of the utility model will become apparent from the following description with reference to the attached drawings. Exemplary embodiments of the utility model are illustrated in the accompanying drawings, and the various drawings are not necessarily drawn to scale. This utility model may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided only to illustrate the present utility model and to convey the spirit and substance of the utility model to those skilled in the art.

The present utility model aims to propose an improved fuel cell stack having a novel design capable of maintaining reliable sealing of individual common ducts even though subjected to large temperature variations, so that leakage of medium in the individual common ducts can be effectively prevented. In particular, the fuel cell stack is often subjected to a large difference in ambient temperature from its operating temperature, for example a proton exchange membrane type fuel cell stack having an operating temperature above 80 ℃, and if started in winter at-30 ℃, the fuel cell stack will experience a temperature change from start-up to normal operation of 110 ℃, which temperature change will cause components of different materials to flex to different extents, which in turn will cause the different components to displace relative to each other at the interface between each other. The fuel cell stack according to the present utility model has an innovative sealing assembly for sealing the common duct, which can effectively cope with the above displacement, and can maintain a reliable seal against the common duct even if the temperature is greatly changed.

Alternative but non-limiting embodiments of the fuel cell stack according to the present utility model are described in detail below with reference to the various drawings. While embodiments of the present utility model will be described below with respect to proton exchange membrane type fuel cell stacks, it will be appreciated by those skilled in the art that the particular type of fuel cell is not capable of constituting a limitation on the scope of the present utility model, and that embodiments of the present utility model are equally applicable to other types of fuel cells.

Referring to fig. 1, there is shown a schematic exploded perspective view of a fuel cell stack according to the present utility model. As shown in fig. 1, the fuel cell stack 10 includes a cell assembly 100 formed by stacking a plurality of cells 110, a pair of current collecting plates 200 located on both sides of the cell assembly 100, and a pair of separator plates (may also be referred to as insulating plates) 300 located on the outermost side, wherein the cell assembly 100, the pair of current collecting plates 200, and the pair of separator plates 300 are assembled together in a stacked manner along an assembly direction (may also be referred to as a longitudinal direction) XX'. In addition, the current collecting plate 200 is generally combined with the separator 300, and thus it can also be considered that there are a pair of end assemblies on the outside of the unit cell assembly 100, each end assembly including, for example, the current collecting plate 200 and the separator 300 combined together. Each cell 110 includes a Membrane Electrode Assembly (MEA) and a pair of bipolar plates located on either side of the MEA, wherein each bipolar plate is configured to direct a reactant (e.g., a cathode gas such as compressed air, an anode gas such as hydrogen or other hydrogen-rich gas) from a reactant common conduit into a reactant flow field in contact with the MEA so that the MEA generates electricity using an electrochemical reaction of the reactants, and is also configured to direct a coolant (e.g., an ethylene glycol-type coolant, a propylene glycol-type coolant, etc.) from the coolant common conduit into a coolant flow field isolated from the MEA so that heat generated by the electrochemical reaction is absorbed by the coolant, and in particular, the bipolar plates are also configured to conduct electricity generated by the MEA. After each cell 110 is assembled into a cell stack 100, there will be a pair of end bipolar plates 120 at both ends of the cell stack 100, the pair of end bipolar plates 120 being identical in structure to each bipolar plate located in the middle of the cell stack 100, except where they are located differently. During operation of the fuel cell stack 10, each bipolar plate positioned in the middle of the cell stack 100 may conduct power generated by each membrane electrode assembly to a pair of end bipolar plates 120, then the pair of end bipolar plates 120 may conduct power to a pair of current collecting plates 200, and finally a pair of connection terminals (not shown) electrically connected to the pair of current collecting plates 200 may supply power to the outside of the fuel cell stack 10.

Like the respective intermediate bipolar plates, each end bipolar plate 120 has a centered flow field region 121 and a pair of channel regions 122 on either side of the flow field region 121, wherein a flow field for the flow of a medium (e.g., anode gas, cathode gas, coolant) is provided in the flow field region 121, allowing the medium to flow from one channel region 122 to the other channel region 122 in a direction generally transverse to the assembly direction XX' (i.e., transverse direction), while a plurality of channel ports 123 are provided in each channel region 122 for receiving or delivering the medium from or to a common channel. After stacking the individual bipolar plates, including the middle bipolar plate and the end bipolar plates, the respective channel openings of the individual bipolar plates are aligned with each other, thereby forming a plurality of common channels 130 extending along the assembly direction XX' on either side of the flow field region 121 in the cell stack 100, wherein each common channel 130 is used to direct one medium to flow into or out of the individual bipolar plates. In order to allow a medium to flow into or out of the respective common ducts 130, a plurality of duct ports 311 are provided on an inner surface of the partition plate 300 serving as a port plate (i.e., a partition plate located at a lower side in fig. 1, hereinafter referred to as a port partition plate 310), wherein each duct port 311 is aligned with a corresponding common duct in the cell combination 100 so that the respective common duct can extend to the port partition plate 310. In addition, a plurality of ports 312 extending therethrough are also provided in the port isolation plate 310, wherein each port 312 communicates with a respective conduit port 311 and thus with a respective common conduit, in other words, each port 312 meets with a respective common conduit at the conduit port 311 and communicates with each other. Thus, media may flow into or out of the respective common conduit through each port 312. In general, in order to allow the medium to smoothly reach the end bipolar plate 120 farthest from the port separator 310, a plurality of pipe ports (not shown) are also provided on the inner surface of the separator 300 serving as a closing plate (i.e., the separator located at the upper side in fig. 1, hereinafter referred to as a closing separator 320), wherein each pipe port is aligned with a corresponding common pipe in the cell assembly 100 so that each common pipe can also extend to the closing separator 320. In addition, a plurality of grooves (not shown) recessed therein from the respective pipe openings are also provided in the closing partition plate 320, wherein each groove communicates with the respective common pipe, in other words, each groove meets and communicates with the respective common pipe at the pipe opening, and of course, the grooves do not extend through the closing partition plate 320, which enables the closing partition plate 320 to close the respective common pipe. In this configuration, the upper end bipolar plate 120 is not located at the end of each common duct, which enables the medium to smoothly reach the end bipolar plate 120.

As described above, a plurality of common pipes extending from the closing spacer 320 to the port spacer 310 and communicable with the outside through the ports 312 in the port spacer 310 are formed in the fuel cell stack 10. Thus, the primary challenge in sealing the fuel cell stack 10 is to seal around each common channel between the individual plates stacked together to prevent leakage of the media in each common channel into the common channels or flow fields of other media, wherein the sealing between the individual bipolar plates in the cell stack 100 is accomplished by a rubber seal coating applied over the individual bipolar plates around the individual channel openings that is compressed between adjacent bipolar plates by the assembly force applied along the assembly direction XX', unlike the prior art where the sealing between each end bipolar plate 120 and the corresponding separator plate 300 is accomplished by the separator assembly 400 disposed therebetween. That is, the fuel cell stack 10 further includes a pair of separator assemblies 400 located outboard of the pair of end bipolar plates 120, wherein each separator assembly 400 is sandwiched between a respective end bipolar plate 120 and separator plate 300, as described in detail below.

Referring to fig. 2 and 3, there is shown a schematic cross-sectional view and a schematic exploded perspective view, respectively, of the separator assembly of the fuel cell stack shown in fig. 1. It should be noted that while fig. 2 and 3 illustrate the separator assembly 400 disposed between the end bipolar plate 120 and the port separator plate 310, the description of the separator assembly 400 with reference to fig. 2 and 3 applies equally to the separator assembly 400 disposed between the end bipolar plate 120 and the closure separator plate 320, if not otherwise stated.

As shown in fig. 2 and 3, the separator assembly 400 includes a base plate 410, which base plate 410 is made of the same material as the end bipolar plates 120, and is provided with a plurality of duct openings 411 through which the respective common ducts pass, that is, each duct opening 411 in the base plate 410 cooperates with a corresponding duct opening in each bipolar plate (including the duct opening 123 in the end bipolar plate 120) to form each common duct so that each common duct can extend through the base plate 410 up to the duct opening 311 on the port separator plate 310.

A plurality of generally annular rubber seal coatings 124 are provided on the end bipolar plate 120, each rubber seal coating 124 being sandwiched between the end bipolar plate 120 and the base plate 410 and being arranged around a respective common channel, i.e. each rubber seal coating 124 is applied to the end bipolar plate 120 in a manner surrounding one common channel and being sandwiched between the end bipolar plate 120 and the base plate 410. Thus, these rubber seal coatings 124 provide a seal between the end bipolar plate 120 and the substrate 410 for each common channel to prevent media in each common channel from leaking between the end bipolar plate 120 and the substrate 410.

The isolation assembly 400 further comprises a plurality of generally annular rubber seals 420, the rubber seals 420 being located on the side of the base plate 410 facing the port isolation plate 310 and being configured to be clamped between the base plate 410 and the port isolation plate 310 and being arranged around the respective common duct, i.e. each rubber seal 420 being arranged on the base plate 410 in such a way as to surround one common duct and being clamped between the base plate 410 and the port isolation plate 310. Thus, these rubber seals 420 provide a seal between the base plate 410 and the port isolation plate 310 for each common conduit to prevent media in each common conduit from leaking between the base plate 410 and the port isolation plate 310.

The separator assembly 400 further includes a first conductive member 430 for electrically connecting the substrate 410 with the end bipolar plate 120 and a second conductive member 440 for electrically connecting the substrate 410 with the current collector plate 200, wherein the first conductive member 430 is located on a side of the substrate 410 facing the end bipolar plate 120 and the second conductive member 440 is located on a side of the substrate 410 facing the current collector plate 200 (i.e., facing the port separator plate 310). In this configuration, the end bipolar plate 120 may transmit power to the current collecting plate 200 through the first conductive member 430, the substrate 410, and the second conductive member 440. In particular, the first conductive member 430 may be spaced apart from each of the rubber seal coatings 124 along the lateral direction, for example, the first conductive member 430 may be located within the area defined by the flow field region 121 of the end bipolar plate 120 such that the first conductive member 430 does not extend outside of the flow field region 121 in the lateral direction. In particular, the second conductive member 440 may be spaced apart from the respective rubber seal rings 420 in the lateral direction, for example, the second conductive member 440 may be located within an area defined by the current collecting plate 200 such that the second conductive member 440 does not extend outside the current collecting plate 200 in the lateral direction. In particular, both the first conductive member 430 and the second conductive member 440 may be composed of a gas diffusion layer. Since the gas diffusion layer is a conductive member having elasticity, the first conductive member 430 may be clamped between the substrate 410 and the end bipolar plate 120 so as to reliably electrically connect the two, and the second conductive member 440 may be clamped between the substrate 410 and the current collecting plate 200 so as to reliably electrically connect the two. Of course, the first conductive member 430 and the second conductive member 440 may not be required, but the substrate 410 may be configured to be directly electrically connected to the end bipolar plate 120 and the current collector plate 200, for example, bosses intended to be electrically connected to the end bipolar plate 120 and the current collector plate 200 may be provided at both sides of the substrate 410.

In the above configuration, since the base plate 410 and the end bipolar plate 120 are made of the same material, they have the same thermal expansion coefficient, which makes it possible to prevent relative displacement between the base plate 410 and the end bipolar plate 120 even if a large change in temperature occurs, thereby making it possible to protect each of the rubber seal coatings 124 from damage, and thus enabling each of the rubber seal coatings 124 to reliably maintain the sealing effect for a long period of time. In addition, although the substrate 410 is different from the material of the partition plate 310 and may generate a relative displacement when a large change in temperature occurs, since the thickness of each rubber seal ring 420 is much larger than that of each rubber seal coating 124 (e.g., at least two times, three times, etc. larger), each rubber seal ring 420 is sufficient to withstand such a relative displacement without damage, and thus the sealing effect can also be reliably maintained. Therefore, the above configuration reliably solves the problem of leakage of the fuel cell due to temperature change in the related art, and thus significantly improves the operation performance, safety, and service life of the fuel cell.

According to an alternative embodiment of the present utility model, as shown in fig. 2 and 3, each rubber seal ring 420 may be bonded to the base plate 410 along a complete turn, whereby the respective rubber seal ring 420 may be accurately positioned to ensure a reliable seal is performed for the respective common conduit. In particular, as shown in fig. 3, adjacent rubber seals 420 are connected together, for example, two adjacent rubber seals 420 may be connected together by a rubber bridge 421 located therebetween. In this configuration, a plurality of common pipes located in any one pipe region 122 may be sealed by a plurality of rubber seals 420 connected together, which also helps to accurately locate each rubber seal 420 to ensure that a reliable seal is made for each common pipe. Alternatively, as shown in fig. 3, each rubber packing 420 may be provided with a rubber lug 422 protruding from the outer side wall thereof, the rubber lug 422 having a thickness smaller than that of the rubber packing 420, and may be adhered to the base plate 410. In this case, at the time of assembly, it is only necessary to bond each rubber lug 422 to the base plate 410, and it is not necessary to bond each rubber seal 420 to the base plate 410 along the entire turn as described above, that is, each rubber seal 420 may be fixed to the base plate 410 by the rubber lug 422. With this configuration, since the thickness of the rubber lugs 422 is small, the rubber lugs 422 are not pressed as much as the rubber seal rings 420, which helps to protect the adhesion region between the rubber lugs 422 and the base plate 410 from being pressed, so that it is possible to further ensure accurate positioning of the respective rubber seal rings 420.

According to an alternative embodiment of the present utility model, as shown in fig. 2 and 3, the isolation assembly 400 may further include a support plate 450, which is located at a side of the base plate 410 facing the port isolation plate 310, and is configured to be clamped between the base plate 410 and the port isolation plate 310, and is provided with a plurality of first openings 451 through which the respective rubber seals 420 pass, and a second opening 452 through which the second conductive member 440 passes. Of course, the original thickness of each rubber seal ring 420 is greater than the thickness of the support plate 450 so that each rubber seal ring 42 can be compressed. In this configuration, the support plate 450 may fill the space between the substrate 410 and the port isolation plate 310 not occupied by the respective rubber seal ring 420 and the second conductive member 440, thereby providing support to the substrate 410 to prevent deformation of the substrate 410, and the first opening 451 and the second opening 452 also help to accurately position the rubber seal ring 420 and the second conductive member 440, respectively. In particular, the support plate 450 may be fixed (e.g., by bonding, welding, etc.) to the substrate 410 and may be composed of the same material as the substrate 410, that is, the support plate 450, the substrate 410, and the end bipolar plate 120 are all composed of the same material, whereby no relative displacement occurs between the support plate 450 and the substrate 410 due to temperature changes, which contributes to reliable fixing of the support plate 450. In particular, as shown in fig. 3, adjacent first openings 451 may communicate with each other, that is, each first opening 451 located in any of the pipe regions 122 may communicate with each other to form one overall first opening 451. Alternatively, the respective first openings 451 may also be isolated from each other. In particular, each first opening 451 expands in a lateral direction (i.e., radially expands) with respect to each rubber seal ring 420, and likewise, the second opening 452 expands in a lateral direction (i.e., radially expands) with respect to the second conductive member 440. In this configuration, the first opening 451 may provide space for lateral expansion of the rubber seal ring 420 due to longitudinal compression, which enables the rubber seal ring 420 to be smoothly longitudinally compressed to provide a reliable seal against a common pipe, while the second opening 452 may provide space for lateral expansion of the second conductive member 440 due to longitudinal compression, which enables the second conductive member 440 to be smoothly longitudinally compressed to provide a reliable electrical connection between the base plate 410 and the current collecting plate 200.

Alternative but non-limiting embodiments of a fuel cell stack according to the utility model are described in detail above with the aid of the accompanying drawings. Modifications and additions to the techniques and structures, as well as rearrangements of the features of the embodiments, should be apparent to those of ordinary skill in the art to be encompassed within the scope of the utility model without departing from the spirit and spirit of the disclosure. Accordingly, such modifications and additions as are contemplated under the teachings of the present utility model should be considered as part of the present utility model. The scope of the utility model includes known equivalents and equivalents not yet foreseen at the time of filing date of the present application.

Claims (10)

1. Fuel cell stack comprising a cell stack (100) stacked together and a pair of end assemblies located outside the cell stack (100), the cell stack (100) having a pair of end bipolar plates (120) located at both ends thereof and being provided with a plurality of common channels, each end assembly comprising a current collecting plate (200) and a separator plate (300), characterized by further comprising a pair of separator assemblies (400), one separator assembly (400) being provided between each side of the end bipolar plates (120) and the end assemblies, the separator assemblies (400) comprising:

-a base plate (410) made of the same material as the end bipolar plate (120), the base plate (410) being provided with a plurality of duct openings (411) aligned with the plurality of common ducts respectively, such that each common duct extends to the separator plate (300), the end bipolar plate (120) being provided with a rubber sealing coating (124) surrounding each common duct respectively and pressing against the base plate (410); and

a plurality of rubber seals (420) respectively surrounding each common pipe and clamped between the base plate (410) and the separator plate (300).

2. The fuel cell stack according to claim 1, wherein each isolation assembly (400) further comprises: a first conductive member (430) electrically connecting the substrate (410) with the end bipolar plate (120); and a second conductive member (440) electrically connecting the substrate (410) and the current collecting plate (200).

3. The fuel cell stack according to claim 2, wherein the first conductive member (430) is constituted by a gas diffusion layer and is sandwiched between the substrate (410) and the end bipolar plate (120); and/or the second conductive member (440) is composed of a gas diffusion layer and is sandwiched between the substrate (410) and the current collecting plate (200).

4. A fuel cell stack according to claim 2 or 3, wherein the first electrically conductive member (430) is within an area defined by a flow field area of the end bipolar plate (120); and/or the second conductive member (440) is within an area defined by the current collecting plate (200).

5. A fuel cell stack according to claim 2 or 3, characterized in that each rubber sealing ring (420) is glued to the base plate (410) along its entire turn.

6. A fuel cell stack according to claim 2 or 3, characterized in that each rubber sealing ring (420) is provided with a rubber tab (422) protruding radially therefrom, each rubber tab (422) being bonded to the base plate (410).

7. The fuel cell stack of claim 6, wherein the thickness of the rubber tab (422) is less than the thickness of the rubber seal ring (420).

8. A fuel cell stack according to claim 2 or 3, wherein each separator assembly (400) further comprises a support plate (450) sandwiched between the base plate (410) and the separator plate (300), the support plate (450) being provided with a first opening (451) through which the plurality of rubber sealing rings (420) pass and a second opening (452) through which the second conductive member (440) passes.

9. The fuel cell stack according to claim 8, wherein the support plate (450) and the base plate (410) are made of the same material.

10. The fuel cell stack of claim 8, wherein the first opening (451) is radially enlarged relative to the plurality of rubber seals (420) and the second opening (452) is radially enlarged relative to the second conductive member (440).