A fuel cell assembly structure

Abstract

The present application relates to a kind of fuel cell assembly structure of splicing and inserting, the assembly structure includes stack core, end plate (8) and limiting structure, wherein end plate (8) is placed in the upper and lower end of stack core, can be compressed and fixed to stack core, stack core is formed by bipolar plate, membrane electrode and battery pack stacking;Bipolar plate is processed with three types of wing feature on the two sides of bipolar plate under the condition that the reaction area feature remains unchanged.A certain number of bipolar plates with the same wing feature are stacked to form a battery pack, and the three types of battery packs are matched with the limiting structure, and the stacking and inserting are completed through the hole structure and the convex structure formed after cooperation to form the smallest assembly unit of the stack.Compared with the prior art, the present application can improve the assembly accuracy and efficiency of stack core, and can provide additional constraints for the stack to reduce the waist collapse after the stack is assembled.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology and relates to a modular fuel cell assembly structure. Background Technology

[0002] A fuel cell is a device that directly converts the chemical energy stored in fuel into electrical energy, characterized by high efficiency, zero pollution, and high power density. In a hydrogen fuel cell, hydrogen gas is input at the anode, where hydrogen atoms lose electrons and become protons. These protons travel through the proton exchange membrane to the cathode, where they combine with electrons arriving from the external circuit and oxygen at the cathode to form water. A typical fuel cell consists of bipolar plates, membrane electrode assemblies (MEAs), and end plates. To meet the power and voltage requirements of fuel cells, multiple individual cells are typically stacked and clamped together by end plates.

[0003] However, high-power fuel cells consist of hundreds of bipolar plates and membrane electrode assemblies stacked together, making it difficult to guarantee positioning accuracy. This affects the output performance of individual cells and results in poor stack performance consistency. Furthermore, stacking a large number of individual cells leads to poor stack structural rigidity. Under harsh operating conditions such as vibration and shock, the middle of the stack may "collapse," affecting the stack's sealing performance and deteriorating cell consistency, posing a safety hazard.

[0004] A review of existing literature reveals that Chinese patent CN210607482U proposes a unitary fuel cell stack, which reduces vibration of the fuel cell stack and improves the positioning accuracy of bipolar plates during assembly by setting a first end plate, a second end plate, and a third end plate. However, this method has limitations in enhancing the structural rigidity of high-power stacks and improving stack "waist collapse". Chinese patent CN215578637U discloses a fuel cell assembly structure that embeds the membrane electrode assembly (MEA) by setting anode and cathode injection molding seals, improving the assembly accuracy between the bipolar plates and the MEA. However, this method does not improve the assembly accuracy between adjacent single cells and has limited improvement on the structural rigidity of the stack after assembly. Chinese patent CN105655609A discloses an internal positioning structure for fuel cell stack assembly, which improves positioning accuracy by setting a proprietary internal positioning structure in the cell unit. However, this method requires installing a positioning structure within each bipolar plate, reducing the efficiency of stack assembly, and the structure has limited ability to alleviate stack "waist collapse" after assembly. Chinese patent CN114865037A proposes a method for assembling a fuel cell stack core. This method improves assembly accuracy by adjusting the centroid position of each bipolar plate. However, the centroid alignment process is cumbersome, reducing assembly efficiency. Furthermore, assembling solely through centroid alignment offers limited improvement to the stack's impact resistance. Chinese patent CN110098414A proposes a fuel cell stack encapsulation structure. This structure improves assembly accuracy through the indentations on both sides of the bipolar plates, combined with the stack enclosure structure and limiting rods. However, this method requires designing different enclosure structures and limiting rod lengths based on the number of stack cells, further reducing assembly efficiency. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a modular fuel cell assembly structure. This invention improves the assembly accuracy and efficiency of the fuel cell stack core and provides additional constraints for the fuel cell stack, reducing the possibility of waist collapse after the fuel cell stack is assembled.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] This invention provides a modular fuel cell assembly structure, which includes a fuel cell stack core, end plates, and limiting structures. The fuel cell stack core is formed by stacking multiple assembly units and is compressed and fixed by the end plates. Each assembly unit includes, in sequence, a third-feature bipolar plate group, a first-feature lower limiting structure plate, a first-feature bipolar plate group, a first-feature upper limiting structure plate, a second-feature lower limiting structure plate, a second-feature bipolar plate group, and a second-feature upper limiting structure plate. The third-feature bipolar plate group has a third-feature side wing feature, and the first-feature bipolar plate group has a first-feature side wing. The first side wing feature has a fixed annular hole, and the second feature bipolar plate group has the second side wing feature; the fixed annular hole is inserted and matched with the lower plate of the second limiting structure, and the lower plate of the first limiting structure is matched with the third side wing feature. The bipolar plates of the three different side wing features together form the smallest assembly unit of the fuel cell stack core; the third feature bipolar plate group, the first feature bipolar plate group and the second feature bipolar plate group are each composed of a certain number of identical bipolar plates stacked together. Except for the differences in the side wing features, the bipolar plate surface features of the three bipolar plate groups are completely the same.

[0008] Furthermore, the lower plate of the first limiting structure and the side wing feature of the third feature bipolar plate cooperate to form a gap annular hole. The size of the gap annular hole is the same as that of the upper plate of the second limiting structure. The upper plate of the second limiting structure at the top of one assembly unit cooperates with the gap annular hole formed by the side wing feature of the third feature bipolar plate and the lower plate of the first limiting structure at the bottom of another assembly unit to achieve seamless splicing between assembly units. The assembly of the fuel cell stack core is completed by splicing them in sequence.

[0009] Furthermore, the size of the fixed annular hole is the same as that of the lower plate of the second limiting structure.

[0010] Furthermore, blind holes are provided on the lower plate of the first limiting structure and the lower plate of the second limiting structure, and light holes are provided on the upper plate of the first limiting structure and the upper plate of the second limiting structure.

[0011] Furthermore, a positioning hole is formed on the first feature bipolar plate, and the light hole on the upper plate of the first limiting structure and the blind hole on the lower plate of the first limiting structure cooperate with the positioning hole and are connected by a positioning pin to improve the assembly accuracy of the fuel cell stack. The first feature bipolar plate assembly is assembled with the lower plate of the first limiting structure and the upper plate of the first limiting structure as a whole.

[0012] Furthermore, the lower plate and upper plate of the first limiting structure are annular plates with the same geometric contour.

[0013] Furthermore, the second feature bipolar plate has a second positioning hole, and the light hole on the upper plate of the second limiting structure and the blind hole on the lower plate of the second limiting structure cooperate with the second positioning hole and are connected by a positioning pin to improve the assembly accuracy of the fuel cell stack. The second feature bipolar plate assembly is assembled with the lower plate of the second limiting structure and the upper plate of the second limiting structure as a whole.

[0014] Furthermore, the lower plate and upper plate of the second limiting structure are annular plates with the same geometric contour.

[0015] Furthermore, the material of the limiting structure is compressible; the thickness of the upper plate of the first limiting structure is the same as the thickness of the second characteristic bipolar plate group, and the thickness of the lower plate of the first limiting structure is the same as the thickness of the third characteristic bipolar plate group.

[0016] Furthermore, the thickness of the lower plate of the second limiting structure is less than the thickness of the first characteristic bipolar plate group, and the thickness of the upper plate of the second limiting structure is less than the thickness of the third characteristic bipolar plate group, to avoid interference when the two assembly units are interlocked. The length of the positioning pin needs to be calculated to avoid the positioning pin affecting the compression during fuel cell stack assembly.

[0017] As a preferred technical solution, the main body of the three types of bipolar plates can be kept consistent. During the manufacturing process, the same forming mold is used to obtain the monopolar plate, and different edge cutting molds are used to form three side wing features. Alternatively, monopolar plates with different side wings can be directly processed by different molds. If graphite plates are used, bipolar plates with different side wing features can be directly processed.

[0018] As a preferred technical solution, the side wing features of the three types of bipolar plates can be separated from the bipolar plates and connected with the same bipolar plate group by making a proprietary limiting structure to form a battery pack with different side wing features.

[0019] As a preferred technical solution, the side wing feature of the bipolar plate is a rectangular structure, and the shape of the third side wing feature is convex.

[0020] As a preferred technical solution, the side wing features of the bipolar plate are not limited to a rectangular structure, and can be designed as a semi-circular structure or other structures depending on the processing conditions.

[0021] As a preferred technical solution, the side features of the bipolar plate are not limited to the left and right sides, but can be processed on the top and bottom sides of the bipolar plate according to the actual situation.

[0022] As a preferred technical solution, the side wing feature of the bipolar plate is not limited to one on each side; two or more can be processed according to actual needs.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) By designing three bipolar plate side wing features and limiting structures, the present invention can be assembled into three battery packs. The three battery packs cooperate with each other to form the smallest assembly unit of the stack. The assembly units are connected to each other to improve assembly accuracy and efficiency.

[0025] (2) The limiting structure of the present invention can cooperate with the side wing features to apply constraints along the battery plane direction to the stack, alleviate the "waist collapse" phenomenon caused by environmental conditions such as vibration and impact during the use of the stack, and improve the service life of the battery. Attached Figure Description

[0026] Figure 1 This is an exploded structural diagram of the modular fuel cell assembly unit component in Embodiment 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of the third feature bipolar plate of the modular fuel cell assembly structure in Embodiment 1 of the present invention;

[0028] Figure 3 This is a schematic diagram of the first feature bipolar plate of the modular fuel cell assembly structure in Embodiment 1 of the present invention;

[0029] Figure 4 This is a schematic diagram of the second feature bipolar plate of the modular fuel cell assembly structure in Embodiment 1 of the present invention;

[0030] Figure 5 This is a schematic diagram of the limiting structure of the modular fuel cell assembly structure in Embodiment 1 of the present invention;

[0031] Figure 6 This is a schematic diagram of the assembly of the first feature bipolar plate and the limiting structure of the interlocking fuel cell assembly structure in Embodiment 1 of the present invention;

[0032] Figure 7 This is a schematic diagram of the assembly of the second feature bipolar plate and the limiting structure of the interlocking fuel cell assembly structure in Embodiment 1 of the present invention;

[0033] Figure 8 This is a schematic diagram of the assembly of the first and second feature bipolar plate groups in the modular fuel cell assembly structure of Embodiment 1 of the present invention;

[0034] Figure 9 This is a schematic diagram of the assembly unit of the modular fuel cell assembly structure in Embodiment 1 of the present invention;

[0035] Figure 10 This is a schematic diagram of the core assembly of the modular fuel cell assembly structure with side wing support structure in Embodiment 1 of the present invention;

[0036] Figure 11This is a schematic diagram of the third feature bipolar plate in the modular fuel cell assembly structure of Embodiment 2 of the present invention;

[0037] Figure 12 This is a schematic diagram of the first feature bipolar plate of the modular fuel cell assembly structure in Embodiment 2 of the present invention;

[0038] Figure 13 This is a schematic diagram of the second feature bipolar plate in the modular fuel cell assembly structure of Embodiment 2 of the present invention;

[0039] Figure 14 This is a schematic diagram of the limiting structure of the modular fuel cell assembly structure in Embodiment 2 of the present invention;

[0040] Figure 15 This is a schematic diagram of the assembly unit of the modular fuel cell assembly structure in Embodiment 2 of the present invention;

[0041] Figure 16 This is a schematic diagram of the third feature bipolar plate of the modular fuel cell assembly structure in Embodiment 3 of the present invention;

[0042] Figure 17 This is a schematic diagram of the first feature bipolar plate of the modular fuel cell assembly structure in Embodiment 3 of the present invention;

[0043] Figure 18 This is a schematic diagram of the second feature bipolar plate in the modular fuel cell assembly structure of Embodiment 3 of the present invention;

[0044] Figure 19 This is a schematic diagram of the assembly unit of the modular fuel cell assembly structure in Embodiment 3 of the present invention.

[0045] Explanation of markings in the diagram:

[0046] 1—Feature 3 bipolar plate assembly, 11—Feature 3 side wing, 2—Lower plate of limit structure 1, 3—Feature 1 bipolar plate assembly, 31—Feature 1 side wing, 32—Lower positioning hole 1, 33—Fixed annular hole, 4—Upper plate of limit structure 1, 5—Lower plate of limit structure 2, 6—Feature 2 bipolar plate assembly, 61—Feature 2 side wing, 62—Lower positioning hole 2, 7—Upper plate of limit structure 2, 8—End plate. Detailed Implementation

[0047] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0048] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] Example 1:

[0051] A modular fuel cell assembly structure, such as Figures 1 to 4 As shown, the assembly includes a fuel cell stack core, end plates 8, and limiting structures. The fuel cell stack core is formed by stacking multiple assembly units and is compressed and fixed by the end plates 8. Each assembly unit, from bottom to top, consists of a third-feature bipolar plate group 1, a first-feature limiting structure lower plate 2, a first-feature bipolar plate group 3, a first-feature limiting structure upper plate 4, a second-feature limiting structure lower plate 5, a second-feature bipolar plate group 6, and a second-feature limiting structure upper plate 7. The third-feature bipolar plate group 1, the first-feature bipolar plate group 3, and the second-feature bipolar plate group 6 are each composed of a certain number of identical bipolar plates stacked together. Except for differences in the side wing features, the bipolar plate surface features are completely identical among the three bipolar plate groups. The first side wing feature 31 has a fixing annular hole 33, the size of which is the same as that of the second-feature limiting structure lower plate 5. The third side wing feature 11 is convex in shape and can cooperate with the first-feature limiting structure lower plate 2 during assembly to form a gap annular hole. The first characteristic bipolar plate group 3 is assembled with the first limiting structure lower plate 2 and the first limiting structure upper plate 4 as a whole. The second characteristic bipolar plate group 6 is assembled with the second limiting structure lower plate 5 and the second limiting structure upper plate 7 as a whole. The fixing annular hole 33 can be inserted and matched with the assembled second limiting structure lower plate 5. The first limiting structure lower plate 2 and the third characteristic bipolar plate group 1 cooperate with each other to form the smallest assembly unit of the fuel cell stack.

[0052] like Figure 5As shown, the lower plate 2 and upper plate 4 of the first limiting structure are rectangular annular plates with the same geometric contour, and the lower plate 5 and upper plate 7 of the second limiting structure are rectangular annular plates with the same geometric contour. The limiting structure is made of compressible rubber material. The thickness of the upper plate 4 of the first limiting structure is the same as the thickness of the second characteristic bipolar plate group 6, and the thickness of the lower plate 2 of the first limiting structure is the same as the thickness of the third characteristic bipolar plate group 1. The thickness of the lower plate 5 of the second limiting structure is less than the thickness of the first characteristic bipolar plate group 3, and the thickness of the upper plate 7 of the second limiting structure is less than the thickness of the third characteristic bipolar plate group 1. The size of the gap annular hole is the same as that of the upper plate 7 of the second limiting structure, and the size of the fixing annular hole 33 is the same as that of the lower plate 5 of the second limiting structure.

[0053] The first feature bipolar plate 3 has a first positioning hole 32. The light hole of the first limiting structure upper plate 4 and the blind hole of the first limiting structure lower plate 2 cooperate with the first positioning hole 32 and are connected by a positioning pin. The second feature bipolar plate 6 has a second positioning hole 62. The light hole of the second limiting structure upper plate 7 and the blind hole of the second limiting structure lower plate 5 cooperate with the second positioning hole 62 and are connected by a positioning pin.

[0054] In this embodiment, the positioning pins used to position the bipolar plate assembly and the limiting structure can be made of non-conductive epoxy resin material to prevent short circuits and damage to the battery after connection.

[0055] Generally, before assembling the fuel cell stack, the three types of bipolar plates are first classified and assembled separately; then, based on the size of the limiting structure and actual needs, an appropriate number of cells are selected as a group of batteries for assembly.

[0056] like Figure 6 As shown, during assembly, the No. 1 feature battery pack is assembled first. The lower plate 2 of the No. 1 limiting structure with blind holes is placed on the assembly platform, and the positioning pin is inserted. Then, the No. 1 feature bipolar plate group 3 is stacked sequentially to the target number of sections. Finally, the upper plate 4 of the No. 1 limiting structure with light holes is positioned and installed to form the No. 1 feature battery pack.

[0057] like Figure 7 As shown, the second feature bipolar plate group 6 is assembled in exactly the same way. After forming the battery pack, the second feature battery pack is assembled onto the first feature battery pack, as shown. Figure 8 As shown, the lower plate 5 of the second limiting structure and the fixed annular hole 33 form an interlocking fit.

[0058] A certain number of characteristic bipolar plates 1 are stacked to form a characteristic battery pack 3. The assembly of characteristic battery pack 1 and characteristic battery pack 2 is then assembled onto the characteristic battery pack 3. Figure 9As shown, the lower plate 2 of the first limiting structure and the third side wing feature 11 cooperate to form a positioning, completing the matching of the three types of batteries and forming the smallest assembly unit of the large battery stack.

[0059] like Figure 10 As shown, after assembling multiple assembly units, all assembly units are stacked sequentially. The gap annular hole formed by the second limiting structure upper plate 7 protruding on the previous assembly unit and the third feature bipolar plate side wing feature 11 and the first limiting structure lower plate 2 in the next assembly unit is inserted into the space. This process is repeated to achieve a fuel cell stack that matches the target. Side wing support structures that match the side wing features are then assembled on both sides to provide additional structural rigidity to the fuel cell stack core.

[0060] This embodiment redesigns the feature groups and minimum assembly units in the fuel cell stack assembly process. By designing bipolar plates 1 (feature 3), 3 (feature 1), and 6 (feature 2) with different side wing features, along with a limiting structure, different features cooperate to assemble a certain number of battery packs as the minimum assembly unit in the large fuel cell stack assembly. During fuel cell stack assembly, only this assembly unit needs to be stacked to complete the assembly, reducing the complexity and high precision requirements of traditional assembly processes. Furthermore, after the stack core is compressed by the end plates, in addition to the frictional force of the stack itself, the positioning pins in the feature battery packs, the interlocking structures within the same assembly unit, and the interlocking structures between different assembly units all provide additional constraints along the stack plane, improving the stiffness of the stack core structure along the core plane and enhancing the stability of the stack under vibration and shock conditions.

[0061] Example 2:

[0062] A modular fuel cell assembly structure, such as Figures 11 to 14 As shown, the difference from Embodiment 1 is that the side wing features are semi-circular structures, and the limiting structure is changed accordingly.

[0063] like Figure 15As shown, when installing a battery with a semi-circular side wing feature, the first feature battery pack is assembled first. The lower plate 2 of the first limiting structure with blind holes is placed on the assembly platform, and positioning pins are inserted. Then, the first feature bipolar plate group 3 is stacked sequentially to the target number of sections. Next, the matching upper plate 4 of the first limiting structure with light holes is positioned and installed to form the first feature battery pack. The second feature bipolar plate group 6 is assembled in the same manner. After forming the battery pack, the second feature battery pack is assembled entirely on top of the first feature battery pack. The lower plate 5 of the second limiting structure and the horseshoe-shaped fixing annular hole 33 form an interlocking fit. A certain number of third feature bipolar plate groups 1 are stacked to form the third feature battery pack. The assembly of the first and second feature battery packs is assembled entirely on top of the third feature battery pack. The lower plate 2 of the first limiting structure and the third side wing feature 11 cooperate to form a positioning, completing the matching of the three types of batteries and forming the smallest assembly unit of the battery stack with a semi-circular side wing feature.

[0064] Example 3:

[0065] A modular fuel cell assembly structure, such as Figures 16 to 18 As shown, the difference from Embodiment 1 is that the side wing features are two sets of rectangular structures, one set of side wing features is distributed on the left and right sides of the bipolar plate, and the other set is distributed on the upper and lower sides of the bipolar plate.

[0066] like Figure 19 As shown, when installing a battery with two sets of rectangular side wing features, the first feature battery pack is assembled first. The lower plate 2 of the first limiting structure with blind holes is placed on the assembly platform, and positioning pins are inserted. Then, the first feature bipolar plate group 3 is stacked sequentially to the target number of sections. Next, the matching upper plate 4 of the first limiting structure with light holes is positioned and installed to form the first feature battery pack. The second feature bipolar plate group 6 is assembled in the same manner. After forming the battery pack, the second feature battery pack is assembled entirely on top of the first feature battery pack, with the lower plate 5 of the second limiting structure interlocking with the fixing annular hole 33. A certain number of third feature bipolar plate groups 1 are stacked to form the third feature battery pack. The assembly of the first and second feature battery packs is assembled entirely on top of the third feature battery pack, with the lower plate 2 of the first limiting structure engaging with the third side wing feature 11 for positioning. This completes the matching of the three types of batteries, forming the smallest assembly unit of a battery stack with two sets of rectangular side wing features.

[0067] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A modular fuel cell assembly structure, characterized in that, The assembly structure includes a fuel cell stack core, an end plate (8), and a limiting structure. The fuel cell stack core is formed by stacking multiple assembly units and is compressed and fixed by the end plate (8). Each assembly unit includes a third feature bipolar plate group (1), a first limiting structure lower plate (2), a first feature bipolar plate group (3), a first limiting structure upper plate (4), a second limiting structure lower plate (5), a second feature bipolar plate group (6), and a second limiting structure upper plate (7) stacked in sequence. The third feature bipolar plate group (1) is provided with a third side wing feature (11), the first feature bipolar plate group (3) is provided with a first side wing feature (31), the first side wing feature (31) has a fixing annular hole (33), and the second feature bipolar plate group (6) is provided with a second side wing feature (61). The fixing annular hole (33) is inserted into the second limiting structure lower plate (5), and the first limiting structure lower plate (2) is in cooperation with the third side wing feature (11). The lower plate (2) of the first limiting structure and the side wing feature (11) of the third feature bipolar plate cooperate to form a gap annular hole, the size of which is the same as that of the upper plate (7) of the second limiting structure.

2. The assembly structure of the fuel cell according to claim 1, wherein The size of the fixed annular hole (33) is the same as that of the lower plate (5) of the second limiting structure.

3. The assembly structure of claim 1, wherein Blind holes are opened on the lower plate (2) of the first limiting structure and the lower plate (5) of the second limiting structure, and light holes are opened on the upper plate (4) of the first limiting structure and the upper plate (7) of the second limiting structure.

4. The assembly structure of the fuel cell according to claim 3, wherein The first feature bipolar plate (3) has a first positioning hole (32), and the first feature bipolar plate group (3) is assembled with the first limiting structure lower plate (2) and the first limiting structure upper plate (4) as a whole.

5. The assembly structure of the fuel cell according to claim 4, wherein The lower plate (2) and upper plate (4) of the first limiting structure are annular plates with the same geometric contour.

6. The assembly structure of the fuel cell according to claim 3, wherein The second feature bipolar plate (6) has a second positioning hole (62), and the second feature bipolar plate group (6) is assembled with the second limiting structure lower plate (5) and the second limiting structure upper plate (7) as a whole.

7. The assembly structure of a fuel cell according to claim 6, wherein The lower plate (5) and upper plate (7) of the second limiting structure are annular plates with the same geometric contour.

8. The assembly structure of the fuel cell according to claim 1, wherein The thickness of the upper plate (4) of the first limiting structure is the same as the thickness of the second feature bipolar plate group (6), and the thickness of the lower plate (2) of the first limiting structure is the same as the thickness of the third feature bipolar plate group (1).

9. The assembly structure of a fuel cell according to claim 8, wherein The thickness of the lower plate (5) of the second limiting structure is less than the thickness of the first feature bipolar plate group (3), and the thickness of the upper plate (7) of the second limiting structure is less than the thickness of the third feature bipolar plate group (1).

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