Cathode plate assembly, single cell assembly, and fuel cell stack

Abstract

The present invention discloses a cathode plate assembly, which relates to a 3D flow field structure for fuel cells. When gas flows in a 3D stretched mesh, the irregular shape of the flow channel causes the flow to be in an ups and downs turbulent state, generating a velocity component perpendicular to the gas diffusion layer, which increases the mass transfer efficiency by one order of magnitude; secondly, the airflow in this turbulent state is also more likely to carry away the liquid water produced by the electrochemical reaction, which not only weakens the mass transfer polarization but also reduces the volume fraction of liquid water in the membrane electrode, reducing the possibility of flooding. At the same time, the process of stretching the mesh is relatively mature, with low requirements for the tonnage of the equipment, and can be produced continuously, reducing production costs and improving production efficiency. The present invention also discloses a single cell assembly using the above-mentioned cathode plate assembly. The present invention also discloses a fuel cell stack using the above-mentioned single cell assembly.

Description

Technical Field

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

[0002] At present, most metal bipolar plates are made by stamping thin metal plates to form adjacent protrusions and depressions, which serve as fine flow channels to complete the gas supply to the membrane electrode in the fuel cell stack.

[0003] The above-mentioned structure obtained by stamping has no ups and downs along the flow channel, basically flows in the form of laminar flow, and the flow direction is parallel to the diffusion direction, so the mass transfer efficiency is low; secondly, liquid water will be generated during the operation of the fuel cell stack, and it is difficult to carry away the liquid water in the membrane electrode catalyst layer and the gas diffusion layer by relying solely on the diffused gas, and the concentration polarization during high-density operation will be further increased.

[0004] Furthermore, sheet metal stamping involves micro-forming, requiring high pressure and precision. To maintain precision, ordinary small presses can only punch one single plate at a time, resulting in low efficiency. Large presses can perform continuous stamping, but this is costly and requires high precision. In particular, to ensure high-quality forming of fine flow channels, a single plate may require two or even multiple stamping steps, resulting in high tooling and time costs. Summary of the Invention

[0005] In view of this, the present invention provides a cathode plate assembly to improve mass transfer efficiency and reduce costs.

[0006] The present invention also provides a single cell assembly using the cathode plate assembly.

[0007] The present invention also provides a fuel cell stack using the above-mentioned single cell assembly.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A cathode plate assembly, used for being arranged on the cathode of a single cell assembly, comprising: a 3D stretched mesh and a separator;

[0010] The 3D stretching mesh is formed by stretching and is divided into multiple sub-stretching parts, including at least: a first stretching part and a second stretching part; a grid is formed between the first stretching part and the second stretching part;

[0011] The first sides of the first stretching portion and the second stretching portion are both connected to the isolation plate; the first side of the joint of the second stretching portion is connected to the second side of the joint of the first stretching portion, and the second side is the other side opposite to the first side;

[0012] There is a gap between the first side of the second stretching portion and the isolation plate, forming a first flow channel along a first direction, and the first direction is parallel to the isolation plate; the grid constitutes a second flow channel along a second direction, and the second direction is perpendicular to the first direction; there is a gap between the second side of the second stretching portion and the isolation plate, which can form a third flow channel along the first direction.

[0013] Preferably, the first stretching portion is parallel to the second stretching portion.

[0014] Preferably, the 3D stretch mesh further comprises: a third stretching portion;

[0015] The first side of each of the sub-stretching portions is connected to the isolation plate;

[0016] The relationship between each pair of adjacent sub-stretching portions is: the first side of one sub-stretching portion is connected to the second side of the joint of the other sub-stretching portion.

[0017] Preferably, a plurality of diamond-shaped meshes are formed between the first stretching portion and the second stretching portion.

[0018] Preferably, the long pitch of the diamond mesh is 0.3-0.4 mm, the short pitch is 0.1-0.2 mm, and the stem width is 0.2-0.3 mm.

[0019] Preferably, the 3D stretch mesh is made of stainless steel or titanium, and has a thickness of 0.09 mm to 0.1 mm.

[0020] Preferably, the 3D stretched mesh is fixedly connected to the isolation plate by laser welding.

[0021] Preferably, the 3D stretched mesh is coated by magnetron sputtering, and the contact resistance is ≤5mΩ·cm 2 , corrosion current ≤ 0.6μA / cm 2 .

[0022] A single cell assembly comprises an anode plate, a membrane electrode and a cathode plate, wherein the cathode plate is the cathode plate assembly as described above.

[0023] A fuel cell stack includes a plurality of single cell assemblies as described above.

[0024] As can be seen from the above technical solution, the cathode plate assembly provided by the present invention exhibits a turbulent, fluctuating flow due to the irregular shape of the flow channels within the 3D stretched mesh. This generates a velocity component perpendicular to the gas diffusion layer, increasing mass transfer efficiency by an order of magnitude. Furthermore, this turbulent flow also more easily removes liquid water produced by the electrochemical reaction, weakening mass transfer polarization while also reducing the volume fraction of liquid water within the membrane electrode, thereby minimizing the possibility of flooding. Furthermore, the stretched mesh manufacturing process is relatively mature, requiring less equipment tonnage, and allows for continuous production, reducing production costs and improving efficiency.

[0025] The present invention also provides a single cell assembly and a fuel cell stack, which have corresponding beneficial effects due to the adoption of the above-mentioned cathode plate assembly. For details, please refer to the above description and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 A schematic structural diagram of a single battery assembly provided in an embodiment of the present invention;

[0028] Figure 2 A schematic structural diagram of a 3D stretch mesh provided by an embodiment of the present invention;

[0029] Figure 3 for Figure 2 A partial enlarged view of .

[0030] Among them, 1 is the anode plate; 2 is the membrane electrode;

[0031] 31 is a 3D stretching mesh, 311 is a first stretching portion, 312 is a second stretching portion, 313 is a third stretching portion, and 314 is a fourth stretching portion;

[0032] 32 is a separation plate. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] The embodiment of the present invention discloses a cathode plate assembly for being arranged at the cathode of a single cell assembly, comprising: a 3D stretched mesh 31 and a separator 32, the structure of which can be referred to Figure 1 As shown;

[0035] The 3D stretching mesh 31 is formed by stretching and is divided into multiple sub-stretching parts, including at least: a first stretching part 311 and a second stretching part 312; a grid is formed between the first stretching part 311 and the second stretching part 312, and the joints of the two parts are also connected; the 3D stretching mesh 31 can be continuously produced by the manufacturing process of the traditional stretching mesh and then uniformly cut; its structure can refer to Figure 2 For ease of description, understanding and Figure 1 Unified, this article is based on Figure 2 The isolation plate 32 is considered to be arranged under the 3D stretch mesh 31 for explanation when viewing the scene;

[0036] The first side of the first stretching portion 311 and the first side of the second stretching portion 312 are both connected to the isolation plate 32; it can be understood that the 3D stretching mesh 31 of this solution is arranged between the isolation plate 32 and the membrane electrode 2, and the first side mentioned is the side of each sub-stretching portion close to the isolation plate 32. Figure 1 and Figure 3 Specifically, the lower side; correspondingly, the second side is the side of each sub-stretching portion away from the isolation plate 32 and close to the membrane electrode 2. Figure 1 and Figure 3 The middle part is the upper part, the same below;

[0037] The first side of the joint of the second stretching part 312 is connected to the second side of the joint of the first stretching part 311, and the second side is the other side opposite to the first side; its structure can refer to Figure 3 As shown, the second stretching portion 312 and the first stretching portion 311 in this embodiment are not located in the same plane, thus forming a three-dimensional structure, so as to form a flow channel with different heights between the separator 32 and the membrane electrode 2, i.e., a 3D flow field.

[0038] Furthermore, there is a gap between the first side of the second stretching portion 312 and the isolation plate 32, forming a first flow channel along a first direction, which is parallel to the isolation plate 32; Figure 3 The short arrow in the middle is the first flow channel. The fluid in the cathode plate flows under the second stretching portion 312. For ease of explanation, it is described as a horizontal flow. The third flow channel also flows horizontally, and the second flow channel flows vertically. The separator 32 is a flat plate structure.

[0039] The grid forms a second flow channel along the second direction, which is perpendicular to the first direction; there is a gap between the second side of the second stretching portion 312 and the isolation plate 32, which can form a third flow channel along the first direction; Figure 3 As shown by the long arrow in the figure (the matching structure of the fourth stretching portion 314 and the third stretching portion 313 is the same as the matching structure of the second stretching portion 312 and the first stretching portion 311), section A starting from the lower left is the first flow channel mentioned above, and then section B corresponds to the second flow channel, which is the longitudinal flow through the grid, and section C corresponds to the third flow channel, flowing over the second stretching portion 312. Sections E, F and G are similar repetitions, which are the first flow channel, the second flow channel and the third flow channel respectively.

[0040] During operation, air flows in the 3D stretched mesh 31. Due to the above-mentioned structure of the mesh, a series of staggered flow channels are formed with the adjacent membrane electrode 2 and isolation plate 32. These channels will cause the fluid to form small vortices locally. On the one hand, the convection mass transfer of the air is enhanced. On the other hand, the water generated by the electrochemical reaction will also be sucked out by the vortex and gradually carried out of the battery stack along the flow direction.

[0041] As can be seen from the above technical solution, in the cathode plate assembly provided by the embodiments of the present invention, the irregular shape of the flow channels creates a turbulent, undulating flow pattern within the 3D stretched mesh 31. This generates a velocity component perpendicular to the gas diffusion layer, increasing mass transfer efficiency by an order of magnitude. Furthermore, this turbulent flow also more easily removes liquid water produced by the electrochemical reaction, weakening mass transfer polarization while also reducing the volume fraction of liquid water within the membrane electrode, minimizing the possibility of flooding. Furthermore, the stretched mesh manufacturing process is relatively mature, requiring relatively low equipment tonnage. Continuous production is also possible, reducing production costs and improving efficiency.

[0042] As an example, the first stretching portion 311 is parallel to the second stretching portion 312. This configuration helps to form a more uniform flow channel, the structure of which can be referred to Figure 1 、 Figure 2 and Figure 3 As shown, each sub-stretching portion of the 3D stretching net 31 is tilted and arranged between the membrane electrode 2 and the separator 32; the flow channel direction of this solution ( Figure 3 (from the lower left to the upper right direction) perpendicular to the length extension direction of each fold line-shaped sub-stretching portion ( Figure 3 A plurality of grids are formed between the first stretching portion 311 and the second stretching portion 312 along the longitudinal extension direction.

[0043] Specifically, the 3D stretching mesh 31 further includes: a third stretching portion 313;

[0044] A first side of each sub-stretching portion is connected to the isolation plate 32;

[0045] The relationship between each pair of adjacent sub-stretching parts is: the first side of one sub-stretching part is connected to the second side of the joint of the other sub-stretching part. Figure 1-Figure 3 As shown, the sub-stretching parts of the 3D stretching net 31 are stacked in an inclined manner, forming a series of staggered flow channels with the adjacent membrane electrode 2 and the separator 32. Figure 3 As shown, the first side of the third stretching portion 313 is connected to the isolation plate 32, and the first side of the joint of the third stretching portion 313 is connected to the second side of the joint of the second stretching portion 312; a first flow channel is formed below the third stretching portion 313, as shown in FIG. Figure 3 In the E section, the second flow channel of the mesh between the third stretching portion 313 and the second stretching portion 312 is as shown in FIG. Figure 3 In the F section, a third flow channel is formed above the third stretching portion 313, such as Figure 3 Of course, the number of sub-stretching parts of the 3D stretching mesh 31 is not limited to this, and it can also include more than the fourth stretching part 314 to form the C, D and E segments of the flow channel, which will not be repeated here.

[0046] In this embodiment, a plurality of diamond-shaped meshes are formed between the first stretching portion 311 and the second stretching portion 312. Figure 1-Figure 3 It should be noted that this solution can also adopt stretching nets with grid structures of other shapes, which will not be described in detail here.

[0047] Furthermore, the long pitch of the diamond mesh is 0.3-0.4mm, the short pitch is 0.1-0.2mm, and the stem width is 0.2-0.3mm, meeting current fuel cell performance requirements. Of course, the shape of the 3D stretched mesh 31 can also be controlled by controlling parameters such as the long pitch, short pitch, and stem width to adapt to different gas volume and pressure drop requirements.

[0048] Preferably, the 3D stretched mesh 31 is made of stainless steel or titanium, with a thickness of 0.09 mm to 0.1 mm, which can well meet the current fuel cell performance requirements.

[0049] Specifically, the 3D stretch mesh 31 is fixedly connected to the isolation plate 32 by laser welding. That is, the first side of each stretching portion is fixedly connected to the isolation plate 32 by laser welding.

[0050] Furthermore, the 3D stretching mesh 31 is coated by magnetron sputtering, and the contact resistance is ≤5mΩ·cm 2 , corrosion current ≤ 0.6μA / cm 2 , ensuring high corrosion resistance and high conductivity.

[0051] The embodiment of the present invention also discloses a single cell assembly, comprising: an anode plate 1, a membrane electrode 2 and a cathode plate, wherein the cathode plate is the cathode plate assembly as described above. Figure 1 As shown, the anode plate 1 and cathode plate membrane are respectively located on both sides of the membrane electrode 2. The single cell assembly provided by this solution has corresponding beneficial effects due to the use of the above cathode plate assembly. For details, please refer to the previous description and will not be repeated here.

[0052] The present invention also discloses a fuel cell stack comprising a plurality of the above-mentioned single cell assemblies. The fuel cell stack provided by this solution, due to the use of the above-mentioned single cell assemblies, has corresponding beneficial effects. For details, please refer to the above description and will not be repeated here.

[0053] The present invention will be further described below with reference to specific embodiments:

[0054] The present invention discloses a plate structure for improving the cathode flow field of a fuel cell, such as Figure 1 The figure shows a single cell assembly, which consists of an anode plate 1, a membrane electrode 2, a 3D stretched mesh 31, and a separator 32, wherein the 3D stretched mesh 31 and the separator 32 constitute the cathode plate assembly. Air flows in the 3D stretched mesh 31. Due to the structure of the mesh, it forms a series of staggered circulation channels with the adjacent membrane electrode 2 and separator 32. These channels cause the fluid to form small vortices locally. On the one hand, this enhances the convection mass transfer of the air. On the other hand, the water generated by the electrochemical reaction will also be sucked out by the vortex and gradually carried out of the stack along the flow direction. The existence of the separator 32 is to isolate the air side from the cooling side. The separator 32 cooperates with the anode plate 1 of the next single cell to form a cooling water chamber.

[0055] In specific implementation, the shape of the 3D stretched mesh 31 can be controlled by controlling parameters such as the long pitch, short pitch, and stem width of the mesh to adapt to different gas volume and pressure drop requirements. Combined with the current fuel cell performance requirements, the long pitch is about 0.3-0.4 mm, the short pitch is 0.1-0.2 mm, and the stem width is 0.2-0.3 mm.

[0056] In specific implementation, the 3D stretching mesh 31 can use stainless steel or titanium as raw material, and the base material thickness is 0.09mm to 0.1mm;

[0057] In a specific implementation, the 3D stretch mesh 31 and the isolation plate 32 can be fixed by laser welding;

[0058] In specific implementation, the 3D stretched mesh 31 can be welded to the isolation plate 32 and then subjected to a coating treatment by magnetron sputtering, with a contact resistance of ≤5mΩ·cm. 2 , corrosion current ≤ 0.6μA / cm2 , ensuring high corrosion resistance and high conductivity.

[0059] In summary, an embodiment of the present invention discloses a cathode plate assembly, which relates to a 3D flow field structure for a fuel cell. When the gas flows in the 3D stretched mesh, due to the irregular shape of the flow channel, the flow is in an ups and downs turbulent state, which produces a velocity component perpendicular to the gas diffusion layer, and increases the mass transfer efficiency by one order of magnitude; secondly, the airflow in this turbulent state is also more likely to carry away the liquid water produced by the electrochemical reaction, while weakening the mass transfer polarization, it also reduces the volume fraction of liquid water in the membrane electrode, reducing the possibility of flooding. At the same time, the process of stretching the mesh is relatively mature, with low requirements for the tonnage of the equipment, and can be produced continuously, reducing production costs and improving production efficiency. The embodiment of the present invention also discloses a single cell assembly using the above-mentioned cathode plate assembly. The embodiment of the present invention also discloses a fuel cell stack using the above-mentioned single cell assembly.

[0060] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0061] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A cathode plate assembly, used to be arranged on the cathode of a single cell assembly, characterized in that: include: 3D stretch mesh (31) and isolation board (32); The 3D stretching net (31) is stretch-formed and is divided into a plurality of sub-stretching parts, including at least: a first stretching part (311), a second stretching part (312) and a third stretching part (313); A grid is formed between each pair of adjacent sub-stretching parts, and the joints between the two parts remain connected; The first side of each sub-stretching portion is connected to the isolation plate (32); the relationship between each pair of adjacent sub-stretching portions is: the first side of the joint of one sub-stretching portion is connected to the second side of the joint of the other sub-stretching portion, the second side being the other side opposite to the first side, and the sub-stretching portions are stacked in an inclined manner in sequence; There is a gap between the first side of the second stretching portion (312) and the isolation plate (32), forming a first flow channel along a first direction, and the first direction is parallel to the isolation plate (32); the grid constitutes a second flow channel along a second direction, and the second direction is perpendicular to the first direction; there is a gap between the second side of the second stretching portion (312) and the isolation plate (32), which can form a third flow channel along the first direction.

2. The cathode plate assembly according to claim 1, wherein: The first stretching portion (311) is parallel to the second stretching portion (312).

3. The cathode plate assembly according to claim 1, wherein: A plurality of diamond-shaped meshes are formed between the first stretching portion (311) and the second stretching portion (312).

4. The cathode plate assembly according to claim 3, wherein: The long pitch of the diamond mesh is 0.3-0.4 mm, the short pitch is 0.1-0.2 mm, and the stem width is 0.2-0.3 mm.

5. The cathode plate assembly according to claim 1, wherein: The 3D stretching mesh (31) is made of stainless steel or titanium and has a thickness of 0.09 mm to 0.1 mm.

6. The cathode plate assembly according to claim 1, wherein: The 3D stretched net (31) is fixedly connected to the isolation plate (32) by laser welding.

7. The cathode plate assembly according to claim 1, wherein: The 3D stretched mesh (31) is coated by magnetron sputtering, and the contact resistance is ≤5mΩ•cm 2 , corrosion current ≤ 0.6μA / cm 2 .

8. A single battery assembly comprising: An anode plate (1), a membrane electrode (2) and a cathode plate, characterized in that the cathode plate is a cathode plate assembly according to any one of claims 1 to 7.

9. A fuel cell stack, characterized in that: The device comprises a plurality of single cell assemblies as claimed in claim 8.

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