Fuel cell and bipolar plate assembly therefor

Abstract

The application discloses a bipolar plate assembly, which utilizes the alternate arrangement of the diameter expansion section and the diameter reduction section in a single medium channel to make the medium flow rate in the single medium channel change moderately, and in the second direction, the diameter expansion section and the diameter reduction section are also arranged alternately, so that there is a pressure difference between the diameter expansion section and the adjacent diameter reduction section, and the medium flowing to any diameter expansion section diffuses to the diameter reduction section of the adjacent medium channel through the gas diffusion layer of the membrane electrode assembly under the action of the pressure difference, so as to form the mass transfer under the ridge and the turbulence, improve the concentration of the medium reactant at the position under the ridge, optimize the medium flow effect between the medium channels, correspondingly optimize the medium flow effect of the bipolar plate assembly, make the medium distribution more uniform and the medium mixing more sufficient and efficient, and correspondingly improve the overall operation efficiency and working performance of the fuel cell. The application further discloses a fuel cell applying the bipolar plate assembly.

Description

Fuel cells and their bipolar plate assemblies Technical Field

[0001] This invention relates to the field of fuel cell systems and related equipment, and particularly to a bipolar plate assembly. This invention also relates to a fuel cell using this bipolar plate assembly. Background Technology

[0002] A proton exchange membrane fuel cell stack typically consists of bipolar plates and membrane electrode assemblies (MEAs). The primary function of the bipolar plates is to supply reactants and remove products in conjunction with the MEAs. With the development of the fuel cell industry, higher demands are being placed on the output power of fuel cells. Especially when fuel cells operate at high output power, the rapid and uniform arrival of reactants at the electrode surfaces is crucial. Therefore, the mass transfer capability of the bipolar plates is critical to the high-performance output of fuel cells.

[0003] Currently, the flow field structure of fuel cells typically adopts a conventional direct-flow structure. The gas medium in the flow field flows along the existing extension direction of the flow channel, resulting in a single flow direction of the gas medium and a lack of disturbance. This is not conducive to the full mixing of the gas inside the flow channel, which restricts the overall working performance and operating effect of the fuel cell.

[0004] Therefore, optimizing the dielectric flow within bipolar plate assemblies to achieve more thorough and efficient dielectric mixing is a crucial technical problem that needs to be addressed by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a bipolar plate assembly with good internal medium flow and efficient and thorough medium mixing. Another purpose of this invention is to provide a fuel cell using the above-described bipolar plate assembly.

[0006] To solve the above-mentioned technical problems, the present invention provides a bipolar plate assembly, including two reference plates that are aligned and fastened together. A membrane electrode assembly is disposed on the outer main extension surface of the reference plates, and the outer main extension surface of the reference plates is in contact with the gas diffusion layer of the membrane electrode assembly. One end of the reference plates is provided with a medium inlet and the other end is provided with a medium outlet. A plurality of reference partition ridges extending along a first direction are provided on the outer main extension surface of the reference plates. Each reference partition ridge is gap-fitted and arranged in parallel along a second direction. A flow guiding partition ridge extending along the first direction is provided between two adjacent reference partition ridges. The reference partition ridges and the flow guiding partition ridges are arranged alternately along the second direction. Any flow guiding partition ridge is gap-fitted with its adjacent reference partition ridge to form a medium channel connecting the medium inlet and the medium outlet for medium flow.

[0007] The medium channel includes several expanding sections and several contracting sections. The cross-sectional area of ​​the expanding section along the second direction is larger than the cross-sectional area of ​​the contracting section along the second direction. The expanding section and the contracting section are arranged alternately and connected sequentially along the first direction, and along the second direction, the expanding section and the contracting section are arranged alternately.

[0008] The first direction intersects with the second direction.

[0009] Preferably, the first direction is perpendicular to the second direction.

[0010] Preferably, the reference dividing ridge extends in a sinusoidal curve along the first direction.

[0011] Preferably, the flow-guiding dividing ridge extends in a sinusoidal curve along the first direction, and the curve period of the flow-guiding dividing ridge is synchronized with that of the reference dividing ridge, with the same wavelength but different amplitudes.

[0012] Preferably, the peak of the flow-guiding ridge is coaxially aligned with the peak of the reference ridge along the second direction, and the trough of the flow-guiding ridge is coaxially aligned with the trough of the reference ridge along the second direction.

[0013] Preferably, the flow-guiding ridge extends in a continuous, repeating curve along the first direction, and the length of the flow-guiding ridge between any highest point and its two adjacent lowest points along the second direction is not equal.

[0014] Preferably, the highest point of the flow-guiding dividing ridge along the second direction is offset from the peak of the reference dividing ridge along the second direction, and the lowest point of the flow-guiding dividing ridge along the second direction is offset from the trough of the reference dividing ridge along the second direction.

[0015] Preferably, the highest point of the flow-guiding dividing ridge along the second direction is staggered from the peak of the reference dividing ridge along the second direction, and the lowest point of the flow-guiding dividing ridge along the second direction is aligned with the trough of the reference dividing ridge along the second direction.

[0016] Alternatively, the highest point of the flow-guiding dividing ridge along the second direction is aligned with the peak of the reference dividing ridge along the second direction, and the lowest point of the flow-guiding dividing ridge along the second direction is offset from the trough of the reference dividing ridge along the second direction.

[0017] Preferably, one of the reference plates is an anode plate that can be used with the anode medium, and the other reference plate is a cathode plate that can be used with the cathode medium.

[0018] The present invention also provides a fuel cell comprising a plurality of bipolar plate assemblies stacked on top of each other, wherein the bipolar plate assemblies are as described in any of the preceding claims.

[0019] Compared to the aforementioned background technology, the bipolar plate assembly provided by this invention, during its operation, utilizes alternating expansion and contraction sections within a single medium channel to moderately vary the medium flow rate within that channel. Simultaneously, because the expansion and contraction sections are also arranged alternately in the second direction, a pressure difference exists between the expansion section and the adjacent contraction section. This pressure difference causes the medium flowing to any expansion section to diffuse through the gas diffusion layer of the corresponding membrane electrode assembly to the contraction section of the adjacent medium channel, thereby forming under-ridge mass transfer and turbulence. This moderately increases the concentration of reactants at the under-ridge location and significantly optimizes the medium flow and diffusion effects between the medium channels, thus optimizing the medium flow effect of the bipolar plate assembly, resulting in a more uniform medium distribution, more thorough and efficient medium mixing, and optimized medium reaction effects in the fuel cell. Consequently, the overall operating efficiency and performance of the fuel cell are improved.

[0020] In another preferred embodiment of the present invention, the first direction is perpendicular to the second direction. This perpendicularity allows for full utilization of the layout space of the main extension surface of the reference plate by the airflow within each medium channel, and optimizes the connectivity and flow efficiency between each medium channel and the medium inlet and outlet. Under typical operating conditions, the main extension surface of the reference plate is usually rectangular. Accordingly, if the first direction can be the length direction of the reference plate, then the second direction can be the width direction of the reference plate. This fully utilizes the assembly space of the main extension surface of the reference plate and ensures that each medium channel is fully adapted to the shape and structure of the main extension surface of the reference plate. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 is a schematic diagram of the anode plate and cathode plate mating structure of a bipolar plate assembly provided in a specific embodiment of the present invention;

[0023] Figure 2 is a schematic diagram of the main extension surface structure of the reference plate in Figure 1;

[0024] Figure 3 is a schematic diagram of the first type of mating structure between the reference partition ridge and the flow guiding partition ridge in Figure 2;

[0025] Figure 4 is a schematic diagram of the second type of matching structure between the reference partition ridge and the flow guiding partition ridge in Figure 2;

[0026] Figure 5 is a schematic diagram of the third type of matching structure between the reference partition ridge and the flow guiding partition ridge in Figure 2;

[0027] Figure 6 is a schematic diagram of the fourth type of mating structure between the reference partition ridge and the flow guiding partition ridge in Figure 2;

[0028] Figure 7 is a schematic diagram of the fifth type of mating structure between the reference partition ridge and the flow guiding partition ridge in Figure 2;

[0029] Figure 8 is a schematic diagram of the three-dimensional structure of the reference dividing ridge and the flow guiding dividing ridge in Figure 2, and the direction of medium diffusion.

[0030] in:

[0031] 11-Base plate; 111-Medium inlet; 112-Medium outlet; 113-Common inlet channel; 114-Inlet distribution area; 115-Reaction zone; 116-Outlet distribution area; 117-Common outlet channel;

[0032] 12-Reference dividing ridge; 121-Flow guiding dividing ridge;

[0033] 13-Medium passage; 131-Expanding section; 132-Reducing section. Detailed Implementation

[0034] The core of this invention is to provide a bipolar plate assembly with good internal medium flow and efficient and thorough medium mixing; at the same time, it provides a fuel cell using the above-mentioned bipolar plate assembly.

[0035] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] It should be noted in advance that, in this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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 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 according to the specific circumstances.

[0037] Furthermore, in this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Moreover, "above," "over," and "on top" of the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature. The first feature is in...

[0038] The terms "below," "under," and "below" in the second feature include the first feature being directly below or diagonally below the second feature, or simply indicate that the first feature is at a lower horizontal height than the second feature. The terms "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are used only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0039] Please refer to Figures 1 and 2, and also refer to Figures 3 through 8.

[0040] In a specific embodiment, the bipolar plate assembly provided by the present invention includes two reference plates 11 that are aligned and fastened together. A membrane electrode assembly is disposed on the outer main extension surface of the reference plate 11, and the outer main extension surface of the reference plate 11 is in contact with the gas diffusion layer of the membrane electrode assembly. A medium inlet 111 is provided at one end of the reference plate 11, and a medium outlet 112 is provided at the other end. A plurality of reference partition ridges 12 extending along a first direction are provided on the outer main extension surface of the reference plate 11. Each reference partition ridge 12 is gap-fitted and arranged in parallel along a second direction. A flow guiding partition ridge 121 extending along the first direction is provided between two adjacent reference partition ridges 12. The reference partition ridges 12 and the flow guiding partition ridges 121 are arranged alternately along the second direction. Any flow guiding partition ridge 121 is gap-fitted with its adjacent reference partition ridge 12 to form a medium channel 13 that connects the medium inlet 111 and the medium outlet 112 for medium flow.

[0041] The medium channel 13 includes several expanding sections 131 and several narrowing sections 132. The cross-sectional area of ​​the expanding section 131 along the second direction is larger than the cross-sectional area of ​​the narrowing section 132 along the second direction. The expanding section 131 and the narrowing section 132 are arranged alternately and connected in sequence along the first direction. Along the second direction, the expanding section 131 and the narrowing section 132 are arranged alternately.

[0042] The first direction intersects with the second direction.

[0043] During its operation, the alternating expansion sections 131 and contraction sections 132 within a single medium channel 13 allow for moderate variations in the medium flow rate. Simultaneously, the alternating arrangement of expansion sections 131 and contraction sections 132 in the second direction creates a pressure difference between the expansion section 131 and the adjacent contraction section 132. This pressure difference causes the medium flowing to any expansion section 131 to diffuse through the gas diffusion layer of the corresponding membrane electrode assembly to the adjacent contraction section 132, thus forming a ridge-like mass transfer and turbulence. This moderately increases the reactant concentration at the ridge position and significantly optimizes the medium flow between the medium channels 13, thereby optimizing the medium flow of the bipolar plate assembly, resulting in a more uniform medium distribution, more thorough and efficient mixing, and optimized medium reaction in the fuel cell. Ultimately, this improves the overall operating efficiency and performance of the fuel cell.

[0044] It should be understood that the main extension surface of the reference plate 11 refers to the single plane on the outer surface of the reference plate 11 enclosed by the two pairs of opposite sides with the longest length, that is, the plane containing the outer wall enclosed by a pair of opposite sides extending along the length direction of the reference plate 11 and a pair of opposite sides extending along the width direction of the reference plate 11.

[0045] Furthermore, it should be clarified that the gas diffusion layer only serves as a flow space that allows the medium to flow and diffuse between two adjacent medium channels under the action of pressure difference. For normal operating conditions, the gas diffusion layer cannot replace the main flow guiding function of each medium channel for the medium. The main flow space of the medium in the bipolar plate is still provided by each medium channel.

[0046] In practical applications, the reference plate 11 typically features an inlet common channel 113, an inlet distribution area 114, a reaction area 115, an outlet distribution area 116, and an outlet common channel 117 arranged sequentially according to the direction of medium flow. Generally, the medium inlet 111 is located at the inlet common channel 113, while the medium outlet 112 is located at the outlet common channel 117. To achieve a more ideal medium flow and reaction effect, taking the main extension surface of the reference plate 11 as a reference, the medium outlet 112 and the medium inlet 111 are respectively arranged at the two apex corners of the reference plate 11 along a set of diagonals extending from the main extension surface of the reference plate 11. Of course, the above layout and positional relationships of the various areas and structures on the reference plate 11 are only conventional selections for general working conditions and are provided as examples for reference. In specific applications, operators can flexibly adjust and select the specific layout and relative positional relationships of the various areas and structures on the reference plate 11 according to specific working requirements. In principle, any material that can meet the actual application requirements of the bipolar plate assembly is acceptable.

[0047] Furthermore, considering the application requirements of bipolar plate assemblies under normal circumstances, of the two reference plates 11 that are aligned and interlocked, one reference plate 11 is an anode plate that can cooperate with the anode medium, and the other reference plate 11 is a cathode plate that can cooperate with the cathode medium. It should be understood that for a typical membrane electrode assembly, it usually includes an electrode membrane body in the middle and carbon layer structures on the main extension surfaces on both sides of the electrode membrane body. During specific assembly and connection, the part that contacts the reference plate 11 is this carbon layer structure, and the corresponding gas diffusion layer is also part of the carbon layer structure. The technical effect of promoting medium diffusion and crossflow achieved by the structural design of each separating ridge and the medium channel 13 in this solution also relies on this gas diffusion layer as the main channel for medium diffusion.

[0048] Of course, the structure of the above-mentioned membrane electrode assembly is a conventional technology in this field. In this case, it is only necessary to clarify the matching position of its gas diffusion layer, and the rest will not be described in detail.

[0049] Considering the normal flow efficiency and guiding effect of the medium, the junctions of adjacent expanding sections 131 and narrowing sections 132 within the same medium channel 13 are smoothly transitioned to ensure smooth medium flow. Of course, for some special operating conditions, if a stepped surface or other non-smooth transition structure is required at the junction of the expanding section 131 and narrowing section 132, this solution is also applicable, and operators can flexibly select and adjust it according to actual needs. In principle, any solution that meets the actual application requirements of the bipolar plate assembly is acceptable.

[0050] Furthermore, the first direction is perpendicular to the second direction. The perpendicularity of the first direction to the second direction enables the airflow in each medium channel 13 to make full use of the layout space of the main extension surface of the reference plate 11, and optimizes the communication effect and medium guiding efficiency between each medium channel 13 and the medium inlet 111 and the medium outlet 112.

[0051] Under normal working conditions, the main extension surface of the reference plate 11 is usually rectangular. Accordingly, the first direction can be the length direction of the reference plate 11, and the second direction can be the width direction of the reference plate 11. This makes full use of the assembly space of the main extension surface of the reference plate 11 and enables each medium channel 13 to be fully adapted to the shape and structure of the main extension surface of the reference plate 11.

[0052] Furthermore, the reference partition ridge 12 extends in a sinusoidal curve along the first direction. The sinusoidal curve structure means that the projection of the reference partition ridge 12 onto the main extension surface of the reference plate 11 extends continuously in a sinusoidal curve. In this way, the existing structural space of the conventional reference plate 11 can be fully utilized, and the processing technology of the conventional partition ridge structure can be matched. At the same time, the regular and continuous curve structure of the reference partition ridge 12 provides a stable edge structure reference for the medium channel 13, ensuring the basic flow effect of the medium in the medium channel 13.

[0053] Based on this, the flow-guiding ridge 121 extends sinusoidally along the first direction, and the curve period of the flow-guiding ridge 121 is synchronized with that of the reference ridge 12, with the same wavelength but different amplitudes. Thus, the expanding section 131 and the contracting section 132 can be formed on the convex and concave sides of any peak of the flow-guiding ridge 121, respectively. Referring to Figure 3, the expanding section 131 is formed between the convex side of any peak of the flow-guiding ridge 121 and the concave side of the peak of the reference ridge 12, which is adjacent to it along the second direction, and the contracting section 132 is formed between the concave side of any peak of the flow-guiding ridge 121 and the convex side of the peak of the reference ridge 12, which is adjacent to it along the second direction. Similarly, the expansion section 131 is formed between the protruding side of any trough of the flow-guiding partition ridge 121 and the concave side of the trough of the reference partition ridge 12 that is adjacent to it along the second direction, and the contraction section 132 is formed between the concave side of any trough of the flow-guiding partition ridge 121 and the protruding side of the trough of the reference partition ridge 12 that is adjacent to it along the second direction.

[0054] Similar to the aforementioned sinusoidal meandering reference ridge 12, the aforementioned flow guide ridge 121 with a sinusoidal extended regular structure can be further aligned and adapted with the reference ridge 12, thereby further optimizing the utilization of the existing structural space of the conventional reference plate 11 and correspondingly matching the processing technology of the conventional ridge structure. At the same time, by utilizing the periodic synchronized regular continuous curve structure of the flow guide ridge 121 and the reference ridge 12, a stable edge structure reference is provided for the medium channel 13, ensuring the basic flow effect of the medium within the medium channel 13.

[0055] Specifically, the crests of the flow-guiding ridge 121 and the crests of the reference ridge 12 are coaxially aligned along the second direction, and the troughs of the flow-guiding ridge 121 and the troughs of the reference ridge 12 are coaxially aligned along the second direction. This alignment of the crests and troughs of the flow-guiding ridge 121 and the reference ridge 12 further optimizes the flow of media in each medium channel 13, and makes the alternating connection structure of the expanding and contracting sections 131 within the same medium channel 13 more regular, resulting in smoother media flow under pressure differential.

[0056] Please refer to Figures 4 to 6. In specific design applications, based on the aforementioned reference dividing ridge 12 extending sinusoidally along the first direction, the guiding dividing ridge 121 extends in a continuously repeating curved pattern along the first direction, and the length of the guiding dividing ridge 121 between any highest point and its two adjacent lowest points along the second direction is unequal. The highest point mentioned here refers to the uppermost vertex of the guiding dividing ridge 121 in the direction shown in any of Figures 4 to 6; correspondingly, the lowest point mentioned here refers to the lowest point of the guiding dividing ridge 121 in the direction shown in any of Figures 4 to 6. This structure with unequal lengths allows for further adaptive optimization of the specific shape and cross-sectional dimensions of each expansion section 131 and contraction section 132 according to actual working conditions, thereby obtaining a medium guiding and diffusion effect that better meets the actual working conditions.

[0057] It should be noted that the continuous repeating curve mentioned above refers to a curve with a certain extension shape that repeats itself according to a certain period and connects end to end to form a continuous and extended overall curve structure. In fact, the sine curve mentioned above is a repeating curve structure with relatively regular peaks and troughs.

[0058] More specifically, for specific applications in actual working conditions, as shown in Figures 4 and 5, the specific shape and structure arrangement of the medium channel 13 can be achieved by adopting an adaptive structure in which the highest point of the flow guiding ridge 121 along the second direction is staggered with the crest of the reference ridge 12 along the second direction, and the lowest point of the flow guiding ridge 121 along the second direction is staggered with the trough of the reference ridge 12 along the second direction.

[0059] Alternatively, as shown in Figure 6, the specific shape and structure of the medium channel 13 can be achieved by using an adaptive structure in which the highest point of the flow guiding ridge 121 along the second direction is staggered with the peak of the reference ridge 12 along the second direction, and the lowest point of the flow guiding ridge 121 along the second direction is aligned with the trough of the reference ridge 12 along the second direction.

[0060] Alternatively, as shown in Figure 7, the specific shape and structure arrangement of the medium channel 13 can be achieved by using an adaptation structure in which the highest point of the flow guiding ridge 121 along the second direction is aligned with the peak of the reference ridge 12 along the second direction, and the lowest point of the flow guiding ridge 121 along the second direction is staggered with the trough of the reference ridge 12 along the second direction.

[0061] In summary, there is no single choice for the specific extension structure type of the flow-guiding partition ridge 121. Depending on the application requirements of different working conditions and the performance and structural layout parameters of the fuel cell under different conditions, different extension structures of the flow-guiding partition ridge 121 can be used to adapt to the reference partition ridge 12 so that the communication structure of the medium channel 13 meets the corresponding working condition requirements and satisfies the structural layout of the bipolar plate assembly and the overall performance requirements of the fuel cell.

[0062] It should be noted that, in practical applications, the main flow direction of the medium in the medium channel 13 can be referenced to the larger black arrow shown in Figure 8; while the flow and diffusion direction of the medium through the gas diffusion layer at each partition ridge, due to the pressure difference between the expansion section 131 and the contraction section 132, can be referenced to the smaller black / white arrows shown in Figure 8. The three-dimensional layout of the corresponding reference partition ridge 12, flow guiding partition ridge 121, and medium channel 13 can also be understood by referring to Figure 8.

[0063] In a specific embodiment, the fuel cell provided by the present invention includes a plurality of bipolar plate assemblies stacked on top of each other, wherein the bipolar plate assembly is the bipolar plate assembly as described in the above embodiment. The internal medium flow effect of the bipolar plate assembly of the fuel cell is good, and its medium mixing is more thorough and efficient.

[0064] In summary, the bipolar plate assembly provided in this invention, during its operation, utilizes alternating expansion and contraction sections within a single medium channel to moderately vary the medium flow rate within that channel. Simultaneously, because the expansion and contraction sections are also arranged alternately in the second direction, a pressure difference exists between the expansion section and the adjacent contraction section. This pressure difference causes the medium flowing to any expansion section to diffuse through the gas diffusion layer of the corresponding membrane electrode assembly to the contraction section of the adjacent medium channel, thereby forming under-ridge mass transfer and turbulence. This moderately increases the concentration of reactants at the under-ridge location and significantly optimizes the medium flow effect between the medium channels, thus correspondingly optimizing the medium flow effect of the bipolar plate assembly, resulting in a more uniform medium distribution, more thorough and efficient medium mixing, and optimized medium reaction effect in the fuel cell. Consequently, the overall operating efficiency and performance of the fuel cell are improved.

[0065] Furthermore, the fuel cell using the above-mentioned bipolar plate assembly provided by the present invention has a better internal medium flow effect in the bipolar plate assembly, and its medium mixing is more thorough and efficient.

[0066] The bipolar plate assembly and the fuel cell using the bipolar plate assembly provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A bipolar plate assembly, comprising two aligning and interlocking reference plates, wherein a membrane electrode assembly is aligning and encapsulated on the outer main extension surface of the reference plates, and the outer main extension surface of the reference plates is in contact with the gas diffusion layer of the membrane electrode assembly, wherein one end of the reference plates is provided with a medium inlet and the other end is provided with a medium outlet, characterized in that, The outer main extension surface of the reference plate is provided with a plurality of reference partition ridges extending along a first direction. Each reference partition ridge is spaced and arranged in parallel along a second direction. A flow guiding partition ridge extending along the first direction is provided between two adjacent reference partition ridges. The reference partition ridges and the flow guiding partition ridges are arranged alternately along the second direction. Any flow guiding partition ridge is spaced and fitted with its adjacent reference partition ridge to form a medium channel connecting the medium inlet and the medium outlet for medium flow. The medium channel includes a plurality of expanding sections and a plurality of contracting sections. The cross-sectional area of ​​the expanding sections along the second direction is larger than the cross-sectional area of ​​the contracting sections along the second direction. The expanding sections and the contracting sections are arranged alternately along the first direction and connected sequentially. Along the second direction, the expanding sections and the contracting sections are arranged alternately. The first direction and the second direction intersect.

2. The bipolar plate assembly as described in claim 1, characterized in that, The first direction is perpendicular to the second direction.

3. The bipolar plate assembly as described in claim 2, characterized in that, The reference dividing ridge extends in a sinusoidal curve along the first direction.

4. The bipolar plate assembly as described in claim 3, characterized in that, The flow-guiding ridge extends sinusoidally along the first direction, and the flow-guiding ridge and the reference ridge have the same curve period, the same wavelength but different amplitude.

5. The bipolar plate assembly as described in claim 4, characterized in that, The peak of the flow-guiding ridge is coaxially aligned with the peak of the reference ridge along the second direction, and the trough of the flow-guiding ridge is coaxially aligned with the trough of the reference ridge along the second direction.

6. The bipolar plate assembly as described in claim 3, characterized in that, The flow-guiding ridge extends in a continuous, repeating curve along the first direction, and the length of the flow-guiding ridge between any highest point and its two adjacent lowest points along the second direction is not equal.

7. The bipolar plate assembly as claimed in claim 6, characterized in that, The highest point of the flow-guiding dividing ridge along the second direction is offset from the peak of the reference dividing ridge along the second direction, and the lowest point of the flow-guiding dividing ridge along the second direction is offset from the trough of the reference dividing ridge along the second direction.

8. The bipolar plate assembly as claimed in claim 6, characterized in that, The highest point of the flow-guiding ridge along the second direction is offset from the peak of the reference ridge along the second direction, and the lowest point of the flow-guiding ridge along the second direction is aligned with the trough of the reference ridge along the second direction; or, the highest point of the flow-guiding ridge along the second direction is aligned with the peak of the reference ridge along the second direction, and the lowest point of the flow-guiding ridge along the second direction is offset from the trough of the reference ridge along the second direction.

9. The bipolar plate assembly as claimed in claim 1, characterized in that, One of the reference plates is an anode plate that can be used with the anode medium, and the other reference plate is a cathode plate that can be used with the cathode medium.

10. A fuel cell comprising a plurality of bipolar plate assemblies stacked on top of each other, characterized in that, The bipolar plate assembly is the bipolar plate assembly as described in any one of claims 1 to 9.

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