Bipolar plate assembly of fuel cell stack and fuel cell stack

Abstract

The invention discloses a bipolar plate assembly of a fuel cell stack and the fuel cell stack, the bipolar plate assembly of the fuel cell stack comprises at least one conductive structure, the conductive structure comprises two graphite layers and at least one permeation barrier layer, the at least one permeation barrier layer is clamped between the two graphite layers, and the at least one permeation barrier layer is arranged between the two graphite layers; and the permeability of the permeation blocking layer is smaller than that of the graphite layer. According to the bipolar plate assembly of the fuel cell stack, the permeation barrier layer is arranged between the two graphite layers, so that the permeation rate of the conductive structure to the reaction gas is reduced, and the permeation rate of the graphite layers to the reaction gas is reduced without increasing the thickness or density of the graphite layers; according to the bipolar plate assembly, miniaturization and lightweight design of the bipolar plate assembly can be achieved, the thin graphite layer can have good conductivity, and the permeation blocking layer also has certain conductivity, so that the conductivity of the conductive structure is further improved, the gravimetric specific power of a fuel cell stack can be increased, the size of the fuel cell stack can be reduced, and the fuel cell stack is more compact. The manufacturing cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell stacks, and in particular to a bipolar plate assembly of a fuel cell stack and a fuel cell stack. Background Art

[0002] Bipolar plates are important components in proton exchange membrane fuel cell stacks (PEMFC stacks). Bipolar plates can provide reaction gases, but the thickness of the bipolar plates will affect their conductivity and permeability. In particular, the permeability of bipolar plates to hydrogen is inversely proportional to their conductivity. While ensuring their conductivity, higher gas permeability reduces the manufacturing yield of fuel cell stack plates.

[0003] In the related art, in order to reduce the permeability of the reaction gas, one method is to increase the polymer resin component in the bipolar plate, and reduce the gas permeability by filling the pore structure of the bipolar plate with the resin. However, when too much resin is added, the conductivity of the bipolar plate will decrease. Another method is to increase the thickness or density of the graphite layer of the bipolar plate to reduce the gas permeability. However, increasing the thickness or density of the graphite layer will increase the volume of the fuel cell stack and reduce the weight power density of the fuel cell stack, and increase the manufacturing cost. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a bipolar plate assembly for a fuel cell stack, which can make the bipolar plate thinner without reducing the conductivity of the bipolar plate, thereby increasing the weight power density of the fuel cell stack and reducing the manufacturing cost.

[0005] According to an embodiment of the present invention, the bipolar plate assembly of a fuel cell stack includes: at least one conductive structure, the conductive structure includes two graphite layers and at least one permeation barrier layer, the at least one permeation barrier layer is sandwiched between the two graphite layers, and the permeability of the permeation barrier layer is less than the permeability of the graphite layer.

[0006] According to the bipolar plate assembly of the fuel cell stack according to an embodiment of the present invention, a permeation barrier layer is arranged between two graphite layers to reduce the permeability of the conductive structure to the reaction gas. In this way, there is no need to increase the thickness or density of the graphite layer to reduce the permeability of the graphite layer to the reaction gas. The thickness of the graphite layer can be reduced, so that the volume of the conductive structure is smaller and the weight is lower, which is conducive to the miniaturization and lightweight design of the bipolar plate assembly. The thinner graphite layer can have good conductivity. At the same time, the permeation barrier layer also has a certain conductivity to further increase the conductivity of the conductive structure, thereby increasing the weight-to-power ratio of the fuel cell stack, reducing the volume of the fuel cell stack, and reducing manufacturing costs.

[0007] According to the bipolar plate assembly of the fuel cell stack of some embodiments of the present invention, each of the permeation barrier layers of the conductive structure is provided with multiple layers, and the multiple permeation barrier layers are stacked between two graphite layers.

[0008] In the bipolar plate assembly of a fuel cell stack according to some embodiments of the present invention, the material of the permeation barrier layer is a transition metal or an alloy.

[0009] In the bipolar plate assembly of a fuel cell stack according to some embodiments of the present invention, the permeation barrier layer is configured as a metal conductive layer.

[0010] In the bipolar plate assembly of a fuel cell stack according to some embodiments of the present invention, the graphite layer is configured as a flexible graphite layer.

[0011] According to the bipolar plate assembly of the fuel cell stack of some embodiments of the present invention, the outer peripheral edge of the permeation barrier layer coincides with the outer peripheral edge of the graphite layer, and the surface area of ​​the permeation barrier layer is the same as the surface area of ​​the graphite layer.

[0012] According to the bipolar plate assembly of the fuel cell stack of some embodiments of the present invention, the graphite layer has at least one fluid porthole, the outer peripheral edge of the permeation barrier layer coincides with the outer peripheral edge of the graphite layer, and the permeation barrier layer is provided with a fluid opening for avoiding the fluid porthole.

[0013] In the bipolar plate assembly of a fuel cell stack according to some embodiments of the present invention, the area of ​​the fluid port hole is larger than the area of ​​the fluid porthole.

[0014] According to the bipolar plate assembly of the fuel cell stack of some embodiments of the present invention, the distance between the edge of the fluid porthole and the edge of the fluid porthole is A1, and satisfies 0.001mm≤A1≤5mm.

[0015] In the bipolar plate assembly of a fuel cell stack according to some embodiments of the present invention, the permeation barrier layer is located in the middle region of the graphite layer, and the perimeter of the permeation barrier layer is smaller than the perimeter of the graphite layer.

[0016] According to the bipolar plate assembly of the fuel cell stack of some embodiments of the present invention, the distance between the outer peripheral edge of the permeation barrier layer and the outer peripheral edge of the graphite layer is A2, and satisfies 0.001 mm≤A2≤5 mm.

[0017] The present invention also provides a fuel cell stack.

[0018] According to the present invention, the fuel cell stack includes: a membrane electrode and a bipolar plate assembly, wherein the bipolar plate assembly is the bipolar plate assembly of the fuel cell stack described in any one of the above embodiments; wherein, the bipolar plate assembly is provided with two, and the two bipolar plate assemblies are respectively a positive plate assembly and a negative plate assembly, and the positive plate assembly and the negative plate assembly are respectively located on two sides of the membrane electrode that are relatively arranged.

[0019] The advantages of the fuel cell stack and the bipolar plate assembly of the above-mentioned fuel cell stack over the prior art are the same, which will not be repeated here.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0022] Figure 1 A cross section of a fuel cell stack according to some embodiments of the present invention;

[0023] Figure 2 It is an assembly diagram of a permeation barrier layer and a graphite layer of a conductive structure of some embodiments of the present invention;

[0024] Figure 3 A top view of a bipolar plate assembly in which the fluid port area of ​​the permeation barrier layer is larger than the area of ​​the fluid porthole of the graphite layer according to an embodiment of the present invention;

[0025] Figure 4 A top view of another embodiment of a bipolar plate assembly of the present invention in which the outer perimeter of the permeation barrier layer is smaller than the outer perimeter of the graphite layer;

[0026] Figure 5 It is a top view of an embodiment of a bipolar plate assembly of the present invention in which the outer perimeter of the permeation barrier layer is smaller than the outer perimeter of the graphite layer.

[0027] Reference numerals:

[0028] A fuel cell stack 100,

[0029] Bipolar plate assembly 10, positive plate assembly 11, negative plate assembly 12, membrane electrode 13, positive gas diffusion layer 14, positive catalyst layer 15, proton exchange membrane 16, negative catalyst layer 17, negative gas diffusion layer 18, coolant 19,

[0030] Conductive structure 20 , permeation barrier layer 21 , graphite layer 22 , fluid porthole 23 , fluid porthole 24 . DETAILED DESCRIPTION

[0031] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0032] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific processes and examples of materials, but those of ordinary skill in the art can be aware of the applicability of other processes and / or the use of other materials.

[0033] Reference below Figure 1-Figure 5 A bipolar plate assembly 10 of a fuel cell stack according to an embodiment of the present invention is described.

[0034] like Figure 1 As shown, the bipolar plate assembly 10 of the fuel cell stack according to the embodiment of the present invention includes: at least one conductive structure 20 .

[0035] The conductive structure 20 includes two graphite layers 22 and at least one permeation barrier layer 21 . The at least one permeation barrier layer 21 is sandwiched between the two graphite layers 22 , and the permeability of the permeation barrier layer 21 is lower than the permeability of the graphite layer 22 .

[0036] Therefore, there is no need to increase the thickness or density of the graphite layer 22 to reduce the permeability of the graphite layer 22 to the reaction gas. The thickness of the graphite layer 22 can be reduced, so that the volume of the conductive structure 20 is smaller and the weight is lower, which is conducive to the miniaturization and lightweight design of the bipolar plate assembly 10. The thinner graphite layer 22 can have good conductivity. At the same time, the permeation barrier layer 21 also has a certain conductivity to further increase the conductivity of the conductive structure 20, thereby increasing the weight-to-power ratio of the fuel cell stack 100, reducing the volume of the fuel cell stack 100, and reducing manufacturing costs.

[0037] For example Figure 1 As shown, the bipolar plate assembly 10 includes two conductive structures 20 , wherein each conductive structure 20 includes two graphite layers 22 and a permeation barrier layer 21 , and the permeation barrier layer 21 is located between the two graphite layers 22 .

[0038] It should be noted that when the bipolar plate assembly 10 is assembled in the fuel cell stack 100, the graphite layer 22 on the side facing the membrane electrode 13 will come into contact with the reaction gas and cause permeation problems. Therefore, in the present invention, a permeation barrier layer 21 is added between the two graphite layers 22, and the permeability of the permeation barrier layer 21 to the reaction gas is less than the permeability of the graphite layer 22 to the reaction gas. In this way, the permeability of the conductive structure 20 to the reaction gas can be reduced by the permeation barrier layer 21, thereby significantly reducing the permeability of the conductive structure 20 to the reaction gas. At the same time, the graphite layer 22 does not need to reduce its permeability to the reaction gas by increasing its thickness or density, so the graphite layer 22 can be made thinner, so that the graphite layer 22 has good conductivity, and the permeation barrier layer 21 also has conductivity, so that the conductivity of the conductive structure 20 is better.

[0039] Furthermore, in the conductive structure 20 using the permeation barrier layer 21, the graphite layer 22 and the permeation barrier layer 21 are both thinner, so that the weight of the conductive structure 20 is lower. In this way, it is possible to ensure that the conductive structure 20 has better conductivity while being light, thereby increasing the weight-to-power ratio of the fuel cell stack 100, while also reducing the volume of the fuel cell stack 100 and reducing manufacturing costs.

[0040] It should be noted that the conductivity of the conductive structure 20 of the present invention can reach 2*10-6Std cm3 / (seccm2Pa), which can meet the US DOE energy efficiency certification target in 2025.

[0041] Of course, the number of the conductive structures 20 , the number of the graphite layers 22 , and the number of the permeation barrier layers 21 mentioned above are all for illustration and do not represent any limitation thereto.

[0042] Optionally, the permeation barrier layer 21 is bonded to the graphite layer 22 so as to enhance the connection stability between the permeation barrier layer 21 and the graphite layer 22 and reduce the impact on the volume of the conductive structure 20 .

[0043] It should be noted that in order to improve the bonding strength between the permeation barrier layer 21 and the graphite layer 22 and reduce the internal resistivity of the conductive structure 20, the permeation barrier layer 21 can be pretreated to remove grease, dust and debris on the surface of the permeation barrier layer 21. The treatment method can be in various forms, for example, through plasma, strong acid or strong alkali, electrochemistry, reduction heat treatment, etc., to reduce the surface oxide of the permeation barrier layer 21, increase the surface roughness of the permeation barrier layer 21, and merge the surface functional groups of the permeation barrier layer 21, thereby improving the adhesion of the permeation barrier layer 21 to the graphite layer 22.

[0044] The shape of the permeation barrier layer 21 can be flat, corrugated, ribbed, dimple-shaped or other pre-constructed shapes. Such a shape can reduce the creep inside the permeation barrier layer 21 and increase the bending strength of the conductive structure 20. At the same time, the surface of the permeation barrier layer 21 can also be pre-coated with carbon or conductive materials or other composite materials, which can inhibit the oxides or hydrides that are easily generated during use, or prevent atmospheric passivation before bonding with the graphite layer 22. The thickness of the permeation barrier layer 21 can be selected from one micron or several microns to tens of microns. The thickness of the permeation barrier layer 21 depends on the ductility of the metal material, and the permeation barrier layer 21 should be suitable for stamping with the graphite layer 22.

[0045] According to the bipolar plate assembly 10 of the fuel cell stack according to an embodiment of the present invention, a permeation barrier layer 21 is arranged between two graphite layers 22 to reduce the permeability of the conductive structure 20 to the reaction gas. In this way, there is no need to increase the thickness or density of the graphite layer 22 to reduce the permeability of the graphite layer 22 to the reaction gas. The thickness of the graphite layer 22 can be reduced, so that the volume of the conductive structure 20 is smaller and the weight is lower, which is conducive to the miniaturization and lightweight design of the bipolar plate assembly 10. The thinner graphite layer 22 can have good conductivity. At the same time, the permeation barrier layer 21 also has a certain conductivity to further increase the conductivity of the conductive structure 20, thereby increasing the weight-to-power ratio of the fuel cell stack 100, reducing the volume of the fuel cell stack 100, and reducing the manufacturing cost.

[0046] In some embodiments, Figure 1 As shown, the permeation barrier layer 21 of each conductive structure 20 is provided with multiple layers, and the multiple permeation barrier layers 21 are stacked between two graphite layers 22 .

[0047] It can be understood that the multi-layer permeation barrier layer 21 is stacked between two graphite layers 22. After stacking, it can make the permeability of the conductive structure 20 to the reaction gas lower, thereby making the reaction gas leakage of the fuel cell stack 100 less, making the reaction more complete, and improving the conversion rate of chemical energy into electrical energy, and can further enhance the conductivity of the conductive structure 20.

[0048] Furthermore, when the multi-layer permeation barrier layer 21 is stacked, various forms can be adopted, for example, all can be stacked in MD (longitudinal direction), all can be stacked in TD (transverse direction), or they can be stacked alternately in MD (longitudinal direction) and TD (transverse direction), which can make the permeability of the conductive structure 20 to the reaction gas lower.

[0049] In some embodiments, the material of the permeation barrier layer 21 is a transition metal or an alloy.

[0050] It is understandable that the permeation barrier layer 21 is made of transition metal or alloy, which can make the permeation barrier layer 21 have good electrical conductivity.

[0051] For example, the permeation barrier layer 21 can be made of any suitable transition metal, such as Ti (titanium), Ni (nickel), W (tungsten), Nb (niobium), etc. At the same time, suitable non-transition metals can also be used, such as Cu (copper), Al (aluminum), Zn (zinc), etc.

[0052] Alternatively, any suitable alloy may also be used, for example, alloys such as SS316 (stainless steel 316) and SS304 (stainless steel 304) may be used as the permeation barrier layer 21 .

[0053] Furthermore, when multiple permeation barrier layers 21 are provided, they can be made of the same metal material or different metal materials. The specific implementation depends on the tendency of the layer to resist oxidation or hydride formation, or to make the overall mechanical strength higher to support the flow field characteristics of the layer as a sublayer. This can make the conductive structure 20 more widely applicable.

[0054] In some embodiments, the permeation barrier layer 21 is configured as a metallic conductive layer.

[0055] Thus, the permeation barrier layer 21 configured as a metal conductive layer can achieve good conductivity while preventing permeation.

[0056] In some embodiments, the graphite layer 22 is configured as a flexible graphite layer.

[0057] Thus, the graphite layer 22 configured as a flexible graphite layer can be arranged more easily in the fuel cell stack 100 , and the graphite layer 22 can be made more permeable to the reaction gas.

[0058] In one embodiment, if Figure 2 As shown, the outer peripheral edge of the permeation barrier layer 21 coincides with the outer peripheral edge of the graphite layer 22 , and the surface area of ​​the permeation barrier layer 21 is the same as the surface area of ​​the graphite layer 22 .

[0059] It is understandable that the permeation barrier layer 21 completely covers the graphite layer 22, which can prevent gas permeation in the graphite layer 22 to the greatest extent, thereby enabling the fuel cell stack 100 to have the highest weight-to-power ratio and a higher chemical energy conversion rate.

[0060] In the second embodiment, if Figure 3 As shown, the graphite layer 22 has at least one fluid porthole 24 , the outer peripheral edge of the permeation barrier layer 21 coincides with the outer peripheral edge of the graphite layer 22 , and the permeation barrier layer 21 is provided with a fluid opening 23 for avoiding the fluid porthole 24 .

[0061] Specifically, the fluid porthole 24 of the graphite layer 22 is its port, and the permeation barrier layer 21 is provided with a fluid opening 23 that avoids the fluid porthole 24, thereby preventing the permeation barrier layer 21 from directly contacting humid air or the surrounding environment, thereby avoiding corrosion of the permeation barrier layer 21, which can extend the service life of the permeation barrier layer 21, thereby increasing the service life of the fuel cell stack 100.

[0062] In the second embodiment, if Figure 3 As shown, the area of ​​the fluid port hole 23 is larger than the area of ​​the fluid porthole 24.

[0063] It can be understood that the area of ​​the fluid porthole 23 is larger than the area of ​​the fluid porthole 24, which can effectively prevent the permeation barrier layer 21 from directly contacting the air or the surrounding environment, thereby preventing the permeation barrier layer 21 from being corroded. At the same time, the area of ​​the fluid porthole 23 is larger than the area of ​​the fluid porthole 24, which can make it easier for the permeation barrier layer 21 to fit with the graphite layer 22, thereby improving processing efficiency.

[0064] In the second embodiment, if Figure 3 As shown, the distance between the edge of the fluid port hole 23 and the edge of the fluid porthole 24 is A1, and satisfies 0.001 mm≤A1≤5 mm.

[0065] It can be understood that when A1 satisfies the above-mentioned value range, it can effectively control the area of ​​the fluid port 23, so that the area of ​​the fluid port 23 can be larger than the fluid porthole 24 but not too large, so that the permeation barrier layer 21 can cover the remaining part of the graphite layer 22 except the fluid porthole 24, preventing the reaction gas from penetrating, thereby ensuring the chemical energy conversion rate of the fuel cell stack 100.

[0066] For example, A1=0.005 mm, in which case the area of ​​the fluid porthole 23 is slightly larger than the area of ​​the fluid porthole 24, so that the permeation barrier layer 21 will not contact the air at the fluid porthole 24, thereby preventing the permeation barrier layer 21 from being corroded.

[0067] Alternatively, A1=0.2 mm, in which case the permeation barrier layer 21 will also cover the remaining portion of the graphite layer 22 except the fluid porthole 24, thereby ensuring that the permeation barrier layer 21 can play a good anti-permeation role, thereby making the chemical energy conversion rate of the fuel cell stack 100 higher.

[0068] In the third embodiment, if Figure 4 As shown, the permeation barrier layer 21 is located in the middle area of ​​the graphite layer 22 , and the perimeter of the permeation barrier layer 21 is smaller than the perimeter of the graphite layer 22 .

[0069] It can be understood that the circumference of the permeation barrier layer 21 is smaller than the circumference of the graphite layer 22, so that the permeation barrier layer 21 fits into the middle area of ​​the graphite layer 22, so that the permeation barrier layer 21 will not be exposed to the external environment, thereby preventing the permeation barrier layer 21 from being corroded, thereby increasing the service life of the permeation barrier layer 21, and further increasing the service life of the fuel cell stack 100.

[0070] In the third embodiment, if Figure 4 and Figure 5 As shown, the distance between the outer peripheral edge of the permeation barrier layer 21 and the outer peripheral edge of the graphite layer 22 is A2, and satisfies 0.001 mm≤A2≤5 mm.

[0071] It can be understood that when A2 satisfies the above value range, the permeation barrier layer 21 can be within the graphite layer 22 while covering most of the graphite layer 22 , thereby ensuring the anti-permeation effect of the permeation barrier layer 21 .

[0072] For example, A2 may adopt the following values: A2=0.1 mm or A2=3 mm, in which case A2 satisfies the above value range.

[0073] For example, Figure 4 As shown, when A2=0.1 mm, the permeation barrier layer 21 covers the middle area (effective area) of the graphite layer 22, and at the same time, the fluid porthole 23 covers the fluid porthole 24, so as to ensure a higher chemical energy conversion rate when the fuel cell stack 100 is used.

[0074] Or, if Figure 5 As shown, when A2=3 mm, the permeability barrier layer 21 is only in the transition area of ​​the graphite layer 22, and the permeability barrier layer 21 does not cover the fluid porthole 24 of the graphite layer 22, so that the permeability barrier layer 21 will not contact the reaction gas of the fluid porthole 24, which can maximize the service life of the permeability barrier layer 21, thereby increasing the service life of the fuel cell stack 100.

[0075] The present invention also provides a fuel cell stack 100 .

[0076] The fuel cell stack 100 according to the embodiment of the invention is as follows: Figure 1 As shown, it includes: a membrane electrode 13 and a bipolar plate assembly 10, and the bipolar plate assembly 10 is the bipolar plate assembly 10 of the fuel cell stack of any one of the above embodiments.

[0077] There are two bipolar plate assemblies 10 , and the two bipolar plate assemblies 10 are respectively a positive plate assembly 11 and a negative plate assembly 12 . The positive plate assembly 11 and the negative plate assembly 12 are respectively located on two sides of the membrane electrode 13 that are opposite to each other.

[0078] It should be noted that both the positive plate assembly 11 and the negative plate assembly 12 can be constructed of two layers of conductive structures 20, and a cavity is formed between the two layers of conductive structures 20. The cavity is suitable for passing a coolant 19. The coolant 19 is used to exchange heat with the fuel cell stack 100 to reduce the temperature of the fuel cell stack 100.

[0079] The positive plate assembly 11 and the negative plate assembly 12 are respectively arranged on both sides of the membrane electrode 13. Figure 1 As shown, the positive plate assembly 11 is located on the upper side of the membrane electrode 13, and the negative plate assembly 12 is located on the lower side of the membrane electrode 13. Hydrogen is passed through the cavity formed between the positive plate assembly 11 and the membrane electrode 13, and air is passed through the cavity formed by the negative plate assembly 12 and the membrane electrode 13.

[0080] The membrane electrode 13 includes a multi-layer structure, and the multi-layer structure includes: a positive electrode gas diffusion layer 14 , a positive electrode catalyst layer 15 , a proton exchange membrane 16 , a negative electrode catalyst layer 17 and a negative electrode gas diffusion layer 18 .

[0081] According to the fuel cell stack 100 of an embodiment of the present invention, a permeation barrier layer 21 is arranged between two graphite layers 22 to reduce the permeability of the conductive structure 20 to the reaction gas. In this way, there is no need to increase the thickness or density of the graphite layer 22 to reduce the permeability of the graphite layer 22 to the reaction gas. The thickness of the graphite layer 22 can be reduced, so that the volume of the conductive structure 20 is smaller and the weight is lower, which is conducive to the miniaturization and lightweight design of the bipolar plate assembly 10. The thinner graphite layer 22 can have good conductivity. At the same time, the permeation barrier layer 21 also has a certain conductivity to further increase the conductivity of the conductive structure 20, thereby increasing the weight-to-power ratio of the fuel cell stack 100, reducing the volume of the fuel cell stack 100, and reducing the manufacturing cost.

[0082] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0083] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0084] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0085] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0086] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0087] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A bipolar plate assembly (10) for a fuel cell stack, characterized in that: include: At least one conductive structure (20), the conductive structure (20) comprising two graphite layers (22) and at least one permeation barrier layer (21), the at least one permeation barrier layer (21) being sandwiched between the two graphite layers (22), and the permeability of the permeation barrier layer (21) being lower than the permeability of the graphite layer (22).

2. The bipolar plate assembly (10) of a fuel cell stack according to claim 1, characterized in that: The permeation barrier layer (21) of each conductive structure (20) is provided with multiple layers, and the multiple layers of the permeation barrier layer (21) are stacked between two layers of the graphite layer (22).

3. The bipolar plate assembly (10) of a fuel cell stack according to claim 1, characterized in that: The material of the permeation barrier layer (21) is a transition metal or an alloy.

4. The bipolar plate assembly (10) of a fuel cell stack according to claim 1, wherein the permeation barrier layer (21) is configured as a metal conductive layer.

5. The bipolar plate assembly (10) of a fuel cell stack according to claim 1, wherein the graphite layer (22) is configured as a flexible graphite layer.

6. The bipolar plate assembly (10) of a fuel cell stack according to claim 1, characterized in that: The outer peripheral edge of the permeation barrier layer (21) coincides with the outer peripheral edge of the graphite layer (22), and the surface area of ​​the permeation barrier layer (21) is the same as the surface area of ​​the graphite layer (22).

7. The bipolar plate assembly (10) of a fuel cell stack according to claim 1, characterized in that: The graphite layer (22) has at least one fluid porthole (24), the outer peripheral edge of the permeation barrier layer (21) coincides with the outer peripheral edge of the graphite layer (22), and the permeation barrier layer (21) is provided with a fluid opening (23) for avoiding the fluid porthole (24).

8. The bipolar plate assembly (10) of a fuel cell stack according to claim 7, characterized in that: The area of ​​the fluid port hole (23) is larger than the area of ​​the fluid porthole (24).

9. The bipolar plate assembly (10) of a fuel cell stack according to claim 8, characterized in that: The distance between the edge of the fluid port hole (23) and the edge of the fluid porthole (24) is A1, and satisfies 0.001 mm≤A1≤5 mm.

10. The bipolar plate assembly (10) of a fuel cell stack according to claim 1, characterized in that: The permeation barrier layer (21) is located in the middle area of ​​the graphite layer (22), and the perimeter of the permeation barrier layer (21) is smaller than the perimeter of the graphite layer (22).

11. The bipolar plate assembly (10) of a fuel cell stack according to claim 10, characterized in that: The distance between the outer peripheral edge of the permeation barrier layer (21) and the outer peripheral edge of the graphite layer (22) is A2, and satisfies 0.001 mm≤A2≤5 mm.

12. A fuel cell stack (100), characterized in that: include: A membrane electrode (13) and a bipolar plate assembly (10), wherein the bipolar plate assembly (10) is a bipolar plate assembly (10) of a fuel cell stack according to any one of claims 1 to 11; There are two bipolar plate assemblies (10), and the two bipolar plate assemblies (10) are respectively a positive plate assembly (11) and a negative plate assembly (12); the positive plate assembly (11) and the negative plate assembly (12) are respectively located on two sides of the membrane electrode (13) that are arranged opposite to each other.

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