Fuel cell stack and fuel cell system

Abstract

The utility model relates to the technical field of fuel cells, and discloses a fuel cell stack and a fuel cell system.The fuel cell stack comprises a stack stacking structure and two end plates which are oppositely arranged, and the stack stacking structure comprises a bipolar plate and a membrane electrode assembly which are sequentially stacked; in the stacking direction, the bipolar plate has a first preset plastic deformation quantity, and the membrane electrode assembly has a second preset plastic deformation quantity; the stack stacking structure is arranged between the two end plates, and the two end plates are fixedly connected through a fastening structure; in the stacking direction, the yield stress of the bipolar plate and the yield stress of the membrane electrode assembly are both larger than the pressure stress applied by the two end plates to the bipolar plate and the membrane electrode assembly. The fuel cell stack is simple in overall structure, and the attenuation amplitude of the assembly force of the stack after operation is greatly reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of fuel cells, and in particular to a fuel cell stack and a fuel cell system. Background Art

[0002] A fuel cell is a power generation device that converts the chemical energy in fuel and oxidant directly into electrical energy. A fuel cell stack is composed of a membrane electrode assembly and a plate. In order to ensure the conduction of electrons generated between the membrane electrode assembly and the plate during the electrochemical reaction, and at the same time, to ensure the sealing performance of the fuel cell stack, a certain assembly pressure needs to be applied to the stack. The components of the stack are always under tightening pressure. During the operation of the stack, changes in temperature, humidity, and pressure load will cause the initial assembly force of the stack to be significantly attenuated, and the contact state between the components inside the stack will be significantly changed, resulting in increased contact resistance, decreased performance, and a sharp increase in the risk of airtightness failure. The current solution for the initial assembly force attenuation of the stack is to set springs and floating short plates at the end plates of the stack to maintain pressure on the components and compensate for the assembly force, but this will increase the complexity of the stack structure, increase the volume and mass of the stack, and increase the cost of the stack.

[0003] Therefore, there is an urgent need for a simple and effective solution to the attenuation of the initial assembly force of the fuel cell stack. Utility Model Content

[0004] The purpose of the utility model is to provide a fuel cell stack and a fuel cell system, in which, before assembly, the membrane electrode assembly and the bipolar plate of the fuel cell stack have a certain preset compression amount, so that after the stack is assembled, the deformation amount after operation is greatly reduced, and the attenuation amplitude of the assembly force of the stack can be greatly reduced, thereby fundamentally solving the problems caused by the permanent deformation of the components in the stack, so as to achieve the effect of enhancing the contact state between the components, reducing the electrode resistance, and improving the performance and reliability of the fuel cell, and greatly simplifying the stack structure, making the stack structure simple, reducing the overall weight of the stack, simplifying the assembly process, and reducing costs.

[0005] In order to achieve the above object, the utility model provides the following technical solutions:

[0006] A fuel cell stack, comprising:

[0007] A stack structure, the stack structure comprising bipolar plates and membrane electrode assemblies stacked in sequence; wherein, along the stacking direction, the bipolar plates have a first preset plastic deformation amount, and the membrane electrode assembly has a second preset plastic deformation amount;

[0008] Two end plates are arranged opposite to each other, and the stack structure is arranged between the two end plates. The two end plates are arranged along the stacking direction, and the two end plates are fixedly connected by a fastening structure; wherein, along the stacking direction, the yield stress of the bipolar plate is greater than the compressive stress applied by the two end plates to the bipolar plate, and the yield stress of the membrane electrode assembly is greater than the compressive stress applied by the two end plates to the membrane electrode assembly.

[0009] Compared with the prior art, after the stack components are assembled, they are always under tightening pressure. During the operation of the stack, changes in temperature, humidity, and pressure loads cause certain permanent deformation of the stack components and their sealing rubber lines, and the initial assembly force of the stack is significantly attenuated, causing the contact state between the stack components inside the stack to change significantly, thereby increasing the contact resistance, reducing the performance, and sharply increasing the risk of airtight failure. The fuel cell stack of this embodiment first pre-presses the stack components that need to be assembled between the end plates in advance, so that the stack components are compressed to a certain extent compared to their original thickness, and have a certain amount of compression, so that the stack components are permanently deformed in the stacking direction in advance. It should be noted that the original thickness of the stack components refers to the thickness when the stack components are processed from raw materials to form stack components with certain functions, and the stack components themselves have not been subjected to pressure deformation in the stacking direction. Among them, the bipolar plate and the membrane electrode assembly are the stack components in the fuel cell, so that the bipolar plate has a first preset compression amount, which produces a certain plastic deformation, and the membrane electrode assembly has a second preset compression amount, which produces a certain plastic deformation. It should be noted that the permanent deformation is a permanent deformation without destroying the structural performance of the stack components themselves. In this embodiment, by pre-uniformly pressurizing the stack components, the stack components themselves have a certain plastic deformation in advance, and then the stack is assembled to form a fuel cell stack, reducing the dimensional change in the stack stacking direction, so that its size has reached the level after permanent deformation before the stack is assembled, and the contact state of each stack component in the stack tends to be stable. After the fuel cell stack is assembled, even if there is a long-term assembly force pressure, the components in the stack will not undergo a large permanent deformation, or even will not deform, thereby greatly reducing the attenuation amplitude of the assembly force of the stack, fundamentally solving the problem caused by the permanent deformation of the components in the stack, so as to achieve the effect of enhancing the contact state between the components, reducing the electrode resistance, and improving the performance and reliability of the fuel cell. Furthermore, the fuel cell stack in this embodiment can effectively alleviate the problem of serious attenuation of the stack assembly force, eliminating the need to provide an elastic structure at the end plate to compensate for the attenuation of the assembly force, greatly simplifying the stack structure, making the stack structure simple, reducing the overall weight of the stack, simplifying the assembly process, and reducing costs.

[0010] Optionally, the first preset plastic deformation is 2% to 40% of the original thickness of the first bipolar plate; the second preset plastic deformation is 2% to 40% of the original thickness of the membrane electrode assembly; and the third preset plastic deformation is 2% to 40% of the original thickness of the second bipolar plate.

[0011] Optionally, the two end plates are provided with opposite connection holes, and the fastening structure includes a connection shaft located on the peripheral side of the battery stack structure and passing through the connection holes of the two end plates, and connecting parts are respectively provided at both ends of the connection shaft.

[0012] Optionally, a cap body is fixed to one end of the connecting shaft, and a nut threadedly connected thereto is provided at the other end of the connecting shaft;

[0013] Preferably, the connection axes located on two opposite sides of the battery stack structure are symmetrically arranged.

[0014] Optionally, the fuel cell stack further comprises a shell, the shell comprising a side wall located between the two end plates and surrounding the stack stack structure; a sealing strip is provided between the shell and the end plates.

[0015] Optionally, a bipolar plate is provided on both sides of the membrane electrode assembly, which is divided into a first bipolar plate and a second bipolar plate, the first bipolar plate includes a first anode plate and a first cathode plate which are stacked, the first cathode plate is located on a side of the first anode plate away from the membrane electrode assembly, a hydrogen flow channel is provided on a side of the first anode plate facing the membrane electrode assembly, and a hydrogen inlet and a hydrogen outlet of the hydrogen flow channel are respectively located at opposite ends of the first bipolar plate;

[0016] The second bipolar plate includes a second anode plate and a second cathode plate which are stacked, the second anode plate being located on a side of the second cathode plate away from the membrane electrode assembly, an air flow channel being provided on a side of the second cathode plate facing the membrane electrode assembly, and an air inlet and an air outlet of the air flow channel being respectively located at opposite ends of the second bipolar plate.

[0017] Optionally, a first cooling channel is provided between the first anode plate and the first cathode plate, and a coolant inlet and a coolant outlet of the first cooling channel are respectively located at two opposite ends of the first bipolar plate;

[0018] A second cooling channel is provided between the second anode plate and the second cathode plate, and a coolant inlet and a coolant outlet of the second cooling channel are respectively located at two opposite ends of the second bipolar plate.

[0019] Optionally, the first anode plate is provided with a first anode cooling groove, and the first cathode plate is provided with a first cathode cooling groove corresponding to the first anode cooling groove one by one, and the first anode cooling groove and the first cathode cooling groove corresponding to each other relatively constitute the first cooling channel;

[0020] The second anode plate is provided with a second anode cooling groove, and the second cathode plate is provided with a second cathode cooling groove corresponding to the second anode cooling groove one by one. The second anode cooling groove and the second cathode cooling groove corresponding to each other relatively constitute the second cooling channel.

[0021] Optionally, the membrane electrode assembly comprises an anode diffusion layer, an anode catalyst layer, a proton exchange layer, a cathode catalyst layer and a cathode diffusion layer stacked in sequence, and the anode diffusion layer is located on a side of the anode catalyst layer facing the first anode plate.

[0022] The utility model also provides a fuel cell system, comprising a plurality of fuel cell stacks of any one type provided by the above technical solution, wherein the plurality of fuel cell stacks are interconnected. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. Among them:

[0024] Figure 1 A schematic diagram of the structure of a fuel cell stack provided by an embodiment of the present invention;

[0025] Figure 2 A partial cross-sectional schematic diagram of a fuel cell stack provided by an embodiment of the present invention;

[0026] Figure 3 A schematic structural diagram of a membrane electrode assembly provided by an embodiment of the present invention;

[0027] Figure 4 A schematic structural diagram of a first anode plate of a first bipolar plate provided in an embodiment of the present invention;

[0028] Figure 5 A schematic structural diagram of a first cathode plate of a first bipolar plate provided in an embodiment of the present invention.

[0029] Icons: 1-stack structure; 2-end plate; 3-shell; 4-connecting shaft; 5-nut; 11-first bipolar plate; 12-membrane electrode assembly; 13-second bipolar plate; 111-first anode plate; 112-first cathode plate; 113-hydrogen inlet; 114-hydrogen outlet; 115-first cooling channel; 116-coolant inlet; 117-coolant outlet; 118-air inlet; 119-air outlet; 121-anode diffusion layer; 122-anode catalyst layer; 123-proton exchange layer; 124-cathode catalyst layer; 125-cathode diffusion layer; 131-second anode plate; 132-second cathode plate; 134-second cooling channel; 1111-hydrogen flow channel; 1121, 1321-air flow channel. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present invention and does not limit the present invention. In fact, it will be clear to those skilled in the art that modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature shown or described as a part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desired that the present invention includes such modifications and variations within the scope of the appended claims and their equivalents.

[0031] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention. The terms "connected", "connected" and "set" used in the present invention should be understood in a broad sense. For example, they can be fixedly connected or detachably connected; they can be directly connected or indirectly connected through an intermediate component. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0032] refer to Figure 1 and Figure 2As shown, the utility model provides a fuel cell stack, comprising: a stack structure 1 and two end plates 2, the stack structure 1 comprising a bipolar plate and a membrane electrode assembly 12 stacked in sequence; wherein, along the stacking direction, the bipolar plate has a first preset plastic deformation, and the membrane electrode assembly 12 has a second preset plastic deformation; the two end plates 2 are arranged oppositely, the stack structure 1 is arranged between the two end plates 2, the two end plates 2 are arranged along the stacking direction, and the two end plates 2 are fixedly connected by a fastening structure; wherein, along the stacking direction, the yield stress of the bipolar plate is greater than the two The compressive stress applied by the end plate 2 to the bipolar plate, the yield stress of the membrane electrode assembly 12 is greater than the compressive stress applied by the two end plates 2 on the membrane electrode assembly 12, and the yield stress of the second bipolar plate 13 is greater than the compressive stress applied by the two end plates 2 on the second bipolar plate 13. Even if the assembly pressure between the two end plates 2 of the stack exists for a long time, the bipolar plates and the membrane electrode assembly 12 themselves have a little permanent deformation. During operation, the thickness of the bipolar plates and the membrane electrode assembly 12 will not change significantly, and the assembly pressure between the two end plates 2 will not decay much, or even not decay at all.

[0033] Compared with the prior art, after the stack components are assembled, they are always under tightening pressure. During the operation of the stack, changes in temperature, humidity, and pressure loads cause certain permanent deformation of the stack components and their sealing rubber lines, and the initial assembly force of the stack is significantly attenuated, causing the contact state between the stack components inside the stack to change significantly, thereby increasing the contact resistance, reducing the performance, and sharply increasing the risk of airtight failure. The fuel cell stack of this embodiment first pre-presses the stack components that need to be assembled between the end plates in advance, so that the stack components are compressed to a certain extent compared to their original thickness, and have a certain amount of compression, so that the stack components are permanently deformed in the stacking direction in advance. It should be noted that the original thickness of the stack components refers to the thickness when the stack components are processed from raw materials to form stack components with certain functions, and the stack components themselves have not been subjected to pressure deformation in the stacking direction. Among them, the bipolar plate and the membrane electrode assembly are the stack components in the fuel cell, so that the bipolar plate has a first preset compression amount, which produces a certain plastic deformation, and the membrane electrode assembly has a second preset compression amount, which produces a certain plastic deformation. It should be noted that the permanent deformation is a permanent deformation without destroying the structural performance of the stack components themselves. In this embodiment, by pre-uniformly pressurizing the stack components, the stack components themselves have a certain plastic deformation in advance, and then the stack is assembled to form a fuel cell stack, reducing the dimensional change in the stack stacking direction, so that its size has reached the level after permanent deformation before the stack is assembled, and the contact state of each stack component in the stack tends to be stable. After the fuel cell stack is assembled, even if there is a long-term assembly force pressure, the components in the stack will not undergo a large permanent deformation, or even will not deform, thereby greatly reducing the attenuation amplitude of the assembly force of the stack, fundamentally solving the problem caused by the permanent deformation of the components in the stack, so as to achieve the effect of enhancing the contact state between the components, reducing the electrode resistance, and improving the performance and reliability of the fuel cell. Furthermore, the fuel cell stack in the present embodiment can effectively alleviate the problem of serious attenuation of the stack assembly force, eliminating the need to provide an elastic structure at the end plate to compensate for the attenuation of the assembly force, greatly simplifying the stack structure, making the stack structure simple, reducing the overall weight of the stack, simplifying the assembly process, reducing the difficulty of stack manufacturing, and reducing costs.

[0034] In addition, the membrane electrode assembly and the two bipolar plates can be pre-pressed before assembly, so that the membrane electrode assembly and the two bipolar plates have a preset compression amount, the membrane electrode assembly is compressed and a certain permanent deformation occurs, the thickness becomes thinner, and the depth of embedding in the flow field becomes smaller, which will not affect the fluid pressure drop and flow distribution of the flow field. At the same time, the thinned membrane electrode assembly makes the stack assembly pressure more evenly distributed to the sealant line, ensuring reliable stack airtightness; after the bipolar plate is pre-pressurized, the bipolar plate has a preset compression amount, the bipolar plate is flatter, and the contact state of the stack is more uniform, thereby ensuring the consistency of the stack voltage. In addition, after the membrane electrode assembly is compressed, the structure is uniform, the porosity of the diffusion layer is reduced, and its resistivity is reduced, so that the ohmic impedance of the stack is reduced and the output voltage is increased; pre-compression can make the membrane electrode assembly and the bipolar plate more closely contact, making the performance more uniform. In addition, pre-compression can make the thickness of the membrane electrode assembly more uniform and enable it to meet more precise thickness requirements during the preparation process. The membrane electrode assembly that has undergone pre-compression has higher mechanical strength and can provide better durability and stability, thereby increasing the life of the fuel cell.

[0035] In a possible implementation, the first preset plastic deformation is 2% to 40% of the original thickness of the bipolar plate; the second preset plastic deformation is 2% to 40% of the original thickness of the membrane electrode assembly. This allows the stack components to be deformed by 2% to 40%, ensuring that the performance of the stack components themselves will not be damaged. The stack components can also have a certain degree of compression deformation to form a suitable permanent deformation. Under the pressure of the stack assembly pressure, no obvious deformation will occur, or even no deformation will occur, solving the problem of serious attenuation of the stack assembly force.

[0036] For the setting of the fastening structure, specifically, Figure 1 As shown, opposite connecting holes are respectively provided on the two end plates 2, and the fastening structure includes a connecting shaft 4 which is located on the peripheral side of the battery stack structure 1 and passes through the connecting holes of the two end plates 2. Connecting pieces are respectively provided at both ends of the connecting shaft 4. The same connecting shaft 4 passes through two opposite connecting holes on the two end plates 2. A connecting piece is respectively provided at both ends of the connecting shaft 4, and the connecting piece is arranged on the outer side of the end plate 2. The connecting piece can be adjusted along the axial direction of the connecting shaft 4 and can be fixedly connected to the connecting shaft 4. The two connecting pieces can clamp the two end plates 2 so that the two end plates 2 are fixed, and the assembly is simple and the connection is firm.

[0037] For example, Figure 1As shown, a cap body is fixed to one end of the connecting shaft 4, and a nut 5 threadedly connected thereto is arranged at the other end of the connecting shaft 4. The cap body can be used as a connecting piece at one end of the connecting shaft 4, and the nut 5 can be used as a connecting piece at the other end of the connecting shaft 4. The nut 5 is threadedly connected to the connecting shaft 4, which is convenient for disassembly and reliable in connection. Preferably, in order to make the assembly force in the stacking direction more uniform, the connecting shafts 4 on opposite sides of the stacking structure 1 can be symmetrically arranged, so that the connection position between each connecting shaft 4 and the connecting piece can be adjusted, and the pressure at each location of the two end plates 2 can be adjusted to be as uniform as possible, thereby improving the uniformity of the assembly force.

[0038] Specifically, Figure 1 As shown, the fuel cell stack further includes a shell 3, which includes a side wall located between the two end plates 2 and surrounding the stack stack structure 1; a sealing strip is provided between the shell 3 and the end plate 2. The shell 3 surrounds the outer peripheral side of the stack stack structure 1 to prevent dust and protect it. Sealing strips are provided at the connection between the two ends of the shell 3 and the end plate 2 to play a sealing role, so that the shell 3 and the end plate 2 are sealed.

[0039] Among them, Figure 2 As shown, the fuel cell stack is formed by stacking a plurality of membrane electrode assemblies 12 and bipolar plates in sequence. In the stacked structure, a bipolar plate is arranged on both sides of the membrane electrode assembly 12, one side of which is a first bipolar plate 11 and the other side is a second bipolar plate 13. The first bipolar plate 11 and the second bipolar plate 13 have the same structure, but their positions relative to the membrane electrode assembly 12 are different.

[0040] In one possible implementation, reference Figure 2 and Figure 4 , Figure 5As shown, the first bipolar plate 11 includes a first anode plate 111 and a first cathode plate 112 which are stacked, the first cathode plate 112 being located on a side of the first anode plate 111 away from the membrane electrode assembly 12, a hydrogen flow channel 1111 being provided on a side of the first anode plate 111 facing the membrane electrode assembly 12, and a hydrogen inlet 113 and a hydrogen outlet 114 of the hydrogen flow channel 1111 being respectively located at opposite ends of the first bipolar plate 11, wherein an air flow channel 1121 is also provided on a side of the first cathode plate 112 away from the first anode plate 111, and the air flow channel 1121 is provided on the side of the first cathode plate 112 facing away from the first anode plate 111. The air inlet 118 and the air outlet 119 of the air flow channel 1121 are respectively located at the two ends of the first bipolar plate 11, and are in contact with another membrane electrode assembly 12; the second bipolar plate 13 includes a second anode plate 131 and a second cathode plate 132 which are stacked, the second anode plate 131 is located on the side of the second cathode plate 132 away from the membrane electrode assembly 12, the second cathode plate 132 is provided with an air flow channel 1321 on the side facing the membrane electrode assembly 12, and the air inlet and the air outlet of the air flow channel 1321 are respectively located at the opposite ends of the second bipolar plate 13. The membrane electrode assembly 12 includes an anode diffusion layer 121, an anode catalyst layer 122, a proton exchange layer 123, a cathode catalyst layer 124 and a cathode diffusion layer 125 which are stacked in sequence, the anode diffusion layer 121 is located on the side of the anode catalyst layer 122 facing the first anode plate 111, and the second anode plate 131 is also provided with a hydrogen flow channel on the side away from the second cathode plate 132, for contacting with another membrane electrode assembly 12.

[0041] Specifically, Figure 2 As shown, a first cooling channel 115 is provided between the first anode plate 111 and the first cathode plate 112, and a coolant inlet 116 and a coolant outlet 117 of the first cooling channel 115 are respectively located at opposite ends of the first bipolar plate 11; a second cooling channel 134 is provided between the second anode plate 131 and the second cathode plate 132, and a coolant inlet and a coolant outlet of the second cooling channel 134 are respectively located at opposite ends of the second bipolar plate 13.

[0042] Further, refer to Figure 2As shown, for the structural arrangement of the first cooling channel 115 and the second cooling channel 134, a first anode cooling groove can be provided on the first anode plate 111, and a first cathode cooling groove corresponding to the first anode cooling groove can be provided on the first cathode plate 112, and the first anode cooling groove and the first cathode cooling groove corresponding to each other can form a first cooling channel; a second anode cooling groove can be provided on the second anode plate 131, and a second cathode cooling groove corresponding to the second anode cooling groove can be provided on the second cathode plate 132, and the second anode cooling groove and the second cathode cooling groove corresponding to each other can form a second cooling channel. The cooling grooves are provided on both the anode plate and the cathode plate, and the coolant can contact both the anode plate and the cathode plate when flowing through, so that the anode plate and the cathode plate can be well cooled, and the cooling effect can be improved.

[0043] The cathode plate and the anode plate are made by stamping stainless steel or titanium alloy metal sheets, or are made of conductive materials.

[0044] This embodiment also provides a fuel cell system, characterized in that it includes a plurality of fuel cell stacks of any one of the above embodiments, and the plurality of fuel cell stacks are interconnected.

[0045] In addition, refer to Figure 1 and Figure 2 As shown, this embodiment also provides a method for assembling a fuel cell stack, wherein the stack components include the membrane electrode assembly 12, the first bipolar plate 11 and the second bipolar plate 13, and the assembling method specifically includes:

[0046] Step S1, measuring initial thickness data: measuring the initial thickness t0 of the battery stack component and recording the numerical data of the initial thickness t0; the initial thickness t0 refers to the thickness of the battery stack component in its natural state after preparation and before being deformed by other pressures.

[0047] Step S2, pre-pressing: applying pressure to the battery stack component along the thickness direction of the battery stack component, and applying pressure evenly to the entire layer of the battery stack component, so that the battery stack component undergoes plastic deformation until a preset compression amount is reached in the thickness direction, and when the preset compression amount is reached, maintaining the first preset time with the current pressure. Exemplarily, the first preset time may be greater than or equal to 15 minutes and less than or equal to 25 minutes. Specifically, the first preset time may be 18 minutes, 20 minutes or 22 minutes. The pressure maintenance time can be selected according to the needs during pre-pressing, and this embodiment is not limited thereto; wherein the preset compression amount is 2% to 40% of the initial thickness t0, so that the battery stack component undergoes a certain permanent deformation in the thickness direction, the thickness becomes thinner, the mechanical strength is improved to a certain extent, and the durability and stability are improved.

[0048] Step S3, after the pre-pressure reaches a first preset time, releasing the pre-pressure pressure.

[0049] Step S4, measuring the data after pre-pressing: measuring the thickness t' of the battery stack component after pre-pressing, and recording the numerical data of the thickness t'.

[0050] Step S5, compare the data before and after pre-pressing, obtain the pre-pressing result according to the initial thickness t0 and the thickness t', if the pre-pressing result meets the preset requirements, enter step S6 and enter the subsequent steps; if the pre-pressing result does not meet the preset requirements, return to step S2.

[0051] Step S6, assembling, stacking the battery stack components, aligning the battery stack components, and placing them between the two end plates 2 for assembly and installation.

[0052] Step S7, pressurizing and tightening, applying assembly pressure to the end plates 2 until the preset assembly thickness of the stack is reached, and then installing the fastening structure of the stack so that the two end plates 2 are relatively fixed, completing the assembly of the stack.

[0053] Specifically, during pre-pressing, there are multiple options for pre-pressing the battery stack components, such as:

[0054] Method 1:

[0055] In step S2, pressure is applied to the battery stack components along the thickness direction of the battery stack components. Multiple battery stack components may be stacked together for compression. Exemplarily, multiple battery stack components may be stacked and aligned, and then pressure is applied to the multiple battery stack components so that the multiple battery stack components are compressed together, which saves pre-compression workload and helps improve work efficiency.

[0056] Method 2:

[0057] In step S2, pressure is applied to the battery stack components along the thickness direction of the battery stack components, and each battery stack component that needs to be pre-pressed may be compressed individually. Exemplarily, pressure may be applied to each battery stack component individually so that the battery stack components are compressed, and the compression effect is better.

[0058] In the above-mentioned fuel cell stack assembly method, for step S5, the method of comparing the data before and after pre-pressing specifically includes:

[0059] Get the ratio: t' / t0, if t' / t0∈(60%, 98%), go to step S6; if Then enter step S2. After the thickness ratio t' / t0 of each battery stack component before and after pre-pressing meets the requirement of t' / t0∈(60%, 98%), enter the subsequent steps for assembly to ensure that each battery stack component is pre-pressed properly, which is conducive to ensuring that the attenuation of the battery stack assembly force is reduced after assembly.

[0060] In order to maintain the stability of the pre-stressed battery stack components, after step S3 and before step S4, the battery stack components after the pre-stressing pressure is released can also be left to stand for a second preset time. The compressed battery stack components are left to stand for a period of time to maintain the structural stability after deformation. Exemplarily, the second preset time can be greater than or equal to 1 minute and less than or equal to 10 minutes. Specifically, the second preset time can be 2 minutes, 3 minutes or 5 minutes, which can be selected according to actual needs, and this embodiment is not limited thereto.

[0061] In a possible implementation manner, the pre-pressing pressure in the above step S2 is greater than the assembly pressure of the press-fastening in step S7.

[0062] The above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. For those skilled in the art, the utility model may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A fuel cell stack, characterized in that: include: A stack structure, the stack structure comprising bipolar plates and membrane electrode assemblies stacked in sequence; wherein, along the stacking direction, the bipolar plates have a first preset plastic deformation amount, and the membrane electrode assembly has a second preset plastic deformation amount; Two end plates are arranged opposite to each other, and the stack structure is arranged between the two end plates. The two end plates are arranged along the stacking direction, and the two end plates are fixedly connected by a fastening structure; wherein, along the stacking direction, the yield stress of the bipolar plate is greater than the compressive stress applied by the two end plates to the bipolar plate, and the yield stress of the membrane electrode assembly is greater than the compressive stress applied by the two end plates to the membrane electrode assembly.

2. The fuel cell stack according to claim 1, characterized in that: The first preset plastic deformation amount is 2% to 40% of the original thickness of the bipolar plate; the second preset plastic deformation amount is 2% to 40% of the original thickness of the membrane electrode assembly.

3. The fuel cell stack according to claim 1, characterized in that: The two end plates are provided with opposite connection holes, and the fastening structure comprises a connection shaft located at the peripheral side of the battery stack structure and penetrating the connection holes of the two end plates, and connecting pieces are respectively provided at both ends of the connection shaft.

4. The fuel cell stack according to claim 3, characterized in that: A cap body is fixed to one end of the connecting shaft, and a nut threadedly connected to the cap body is arranged at the other end of the connecting shaft.

5. The fuel cell stack according to claim 1, characterized in that: It also includes a shell, which includes a side wall located between the two end plates and surrounding the battery stack structure; a sealing strip is provided between the shell and the end plates.

6. The fuel cell stack according to claim 1, characterized in that: A bipolar plate is disposed on both sides of the membrane electrode assembly, which is divided into a first bipolar plate and a second bipolar plate, wherein the first bipolar plate comprises a first anode plate and a first cathode plate which are stacked, wherein the first cathode plate is located on a side of the first anode plate away from the membrane electrode assembly, and a hydrogen flow channel is disposed on a side of the first anode plate facing the membrane electrode assembly, and a hydrogen inlet and a hydrogen outlet of the hydrogen flow channel are respectively located at opposite ends of the first bipolar plate; The second bipolar plate includes a second anode plate and a second cathode plate which are stacked, the second anode plate being located on a side of the second cathode plate away from the membrane electrode assembly, an air flow channel being provided on a side of the second cathode plate facing the membrane electrode assembly, and an air inlet and an air outlet of the air flow channel being respectively located at opposite ends of the second bipolar plate.

7. The fuel cell stack according to claim 6, characterized in that: A first cooling channel is provided between the first anode plate and the first cathode plate, and a coolant inlet and a coolant outlet of the first cooling channel are respectively located at two opposite ends of the first bipolar plate; A second cooling channel is provided between the second anode plate and the second cathode plate, and a coolant inlet and a coolant outlet of the second cooling channel are respectively located at two opposite ends of the second bipolar plate.

8. The fuel cell stack according to claim 7, characterized in that: The first anode plate is provided with a first anode cooling groove, and the first cathode plate is provided with a first cathode cooling groove corresponding to the first anode cooling groove one by one, and the first anode cooling groove and the first cathode cooling groove corresponding to each other relatively form the first cooling channel; The second anode plate is provided with a second anode cooling groove, and the second cathode plate is provided with a second cathode cooling groove corresponding to the second anode cooling groove one by one. The second anode cooling groove and the second cathode cooling groove corresponding to each other relatively constitute the second cooling channel.

9. The fuel cell stack according to claim 6, characterized in that: The membrane electrode assembly comprises an anode diffusion layer, an anode catalyst layer, a proton exchange layer, a cathode catalyst layer and a cathode diffusion layer which are stacked in sequence. The anode diffusion layer is located on a side of the anode catalyst layer facing the first anode plate.

10. A fuel cell system, characterized in that: It comprises a plurality of fuel cell stacks as described in any one of claims 1 to 9, wherein the plurality of fuel cell stacks are interconnected.

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