Bipolar plate and preparation process thereof, fuel cell and vehicle

Abstract

The invention discloses a bipolar plate and a preparation process thereof, a fuel cell and a vehicle, and solves the technical problem of deformation of the bipolar plate when a sealing ring is injection-molded on the bipolar plate in the prior art. The runner depth of the anode plate of the bipolar plate is smaller than that of the cathode plate; the depth of the sealing groove of the anode plate is the same as that of the sealing groove of the cathode plate; and sealing rings which are integrally formed in the sealing grooves in an injection molding manner are arranged on the gas field sides of the anode plate and the cathode plate. As the depths of the sealing grooves of the cathode and anode plates are the same and the heights of the sealing rings of the cathode and anode plates are the same, the influence of manufacturing tolerance on anode sealing pressure is directly reduced, and the sealing design is more reliable. And the depths of the sealing grooves of the cathode and anode plates are the same, so that the sealing section areas of the cathode and anode plates are consistent, and the glue injection speeds of the cathode plate gas field side and the anode plate gas field side are consistent, thereby effectively avoiding the problem of deformation of the bipolar plate due to different injection molding pressures on two sides.

Description

Technical Field

[0001] The present application belongs to the technical field of bipolar plates, and in particular, relates to a bipolar plate and a corresponding preparation process, a fuel cell and a vehicle. Background Art

[0002] Bipolar plates are key components of hydrogen fuel cells, playing the role of gas distribution, water and heat management, current collection, and supporting core sealing. The commonly used material for bipolar plates is 316L stainless steel, with a thickness of 0.07 to 0.1 mm. At present, in order to improve the volume power density of fuel cells, monolithic bipolar plates are gradually moving towards thinner substrates and refined flow field designs. Of course, thinner bipolar plates bring challenges to the manufacturing process. The flatness of stamped bipolar plates deteriorates, and the deterioration of the bipolar plate's own rigidity also brings hidden dangers to the injection molding seal of the bipolar plate.

[0003] Usually, the anode and cathode plates are sealed by laser welding to achieve the sealing of the coolant flow field, and a sealing ring is set between the bipolar plate and the adjacent membrane electrode frame to achieve the sealing of the anode and cathode gas field. There are many forms of core sealing at present, including pasting sealing film on the membrane electrode frame or bipolar plate, and injection molding sealing ring on the membrane electrode frame or bipolar plate surface. Compared with pasting seals, injection molding has high manufacturing precision and high production efficiency, and is suitable for mass production. In addition, compared with membrane electrode injection molding sealing, bipolar plate injection molding has a higher yield rate and will not cause the problem of cost increase due to damage to the membrane electrode during the production process.

[0004] However, as the thickness of a single bipolar plate decreases, the problem of bipolar plate deformation may occur when a sealing ring is injection-molded on the bipolar plate. Summary of the invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a bipolar plate and a preparation process thereof, a fuel cell and a vehicle, which effectively avoid the problem of deformation of the ultra-thin plate sealing ring during injection molding.

[0006] In a first aspect of the present application, a bipolar plate is provided, comprising an anode plate and a cathode plate provided with an active area and a plurality of medium ports, wherein the flow channel depth of the anode plate is less than the flow channel depth of the cathode plate; the sealing groove depth of the anode plate is the same as the sealing groove depth of the cathode plate; and the gas field sides of the anode plate and the cathode plate are provided with sealing rings integrally injection-molded in the sealing groove.

[0007] In some embodiments, the sealing groove includes an outer frame sealing groove surrounding the periphery of the medium port, an inner frame sealing groove located between the medium port and the flow channel, and a separation sealing groove located between two adjacent medium ports; the inner frame sealing groove of the anode plate and the corresponding inner frame sealing groove in the cathode plate are staggered.

[0008] In some embodiments, the area on the anode plate corresponding to the position of the inner frame sealing groove of the cathode plate and the area on the cathode plate corresponding to the position of the inner frame sealing groove of the anode plate are both provided with a support portion; the support portion is provided with support ribs distributed at intervals, and the convex surface of the support ribs contacts the bottom of the corresponding inner frame sealing groove; and a guide channel for the flow of fluid medium is formed between adjacent support ribs;

[0009] The anode plate and the cathode plate are provided with through holes in the areas between the inner frame sealing groove and the flow channel and corresponding to the reaction medium port, and the medium port, the guide channel, the through holes and the flow channel are connected in sequence.

[0010] In some embodiments, the top surface of the support portion is flush with the top surface of the flow channel ridge of the flow channel;

[0011] The support portion is provided with a height adjustment area, the height adjustment area is located between the inner frame sealing groove and the flow channel, and the height adjustment area is flush with the groove bottom of the flow channel groove of the flow channel.

[0012] In some embodiments, the flow channel period of the flow guiding channel is 1-2 mm; and the ridge width W_boss of the flow guiding channel is not less than 0.5 mm.

[0013] In some embodiments, the flow channel depth H_ano of the anode plate, the flow channel depth H_cath of the cathode plate, and the depth H of the sealing groove satisfy: H=(H_ano+H_cath) / 2.

[0014] In some embodiments, the difference between the channel depth of the anode plate and the channel depth of the cathode plate is 0.05-0.2 mm.

[0015] In a second aspect of the present application, a preparation process for preparing the bipolar plate of the first aspect is provided, comprising the following steps:

[0016] Plate forming: stamping the substrate to obtain the anode plate and the cathode plate;

[0017] Plate welding: welding the sealing groove corresponding area and the active area of ​​the anode plate and the cathode plate, wherein the welding Z-axis coordinate of the sealing groove corresponding area is different from the welding Z-axis coordinate of the active area;

[0018] Injection-molded sealing rings: Injection-molded sealing rings are respectively formed on the sealing grooves of the anode plate and the cathode plate.

[0019] In some embodiments, the electrode plate welding specifically includes:

[0020] Moving the laser welding head to complete the line welding of the corresponding area of ​​the sealing groove to form a sealing welding line;

[0021] The Z-axis coordinate of the laser welding head is adjusted to complete the spot welding operation of the active area step by step to form a spot welding line.

[0022] In some embodiments, the injection molding sealing ring specifically comprises:

[0023] Coating a primer material on the sealing grooves of the anode plate and the cathode plate respectively, wherein the main component of the primer material is at least one of n-hexane, ethyl silicate, ethyl acetate and n-heptane;

[0024] Glue is injected into the sealing grooves respectively and the sealing grooves are filled with glue, and the sealing ring is formed after the glue is solidified.

[0025] In a third aspect of the present application, a fuel cell is provided, comprising the bipolar plate of the first aspect.

[0026] In a fourth aspect of the present application, a vehicle is provided, comprising the fuel cell according to the third aspect.

[0027] According to the bipolar plate provided by one or more embodiments of the present application, the flow channel depth of the anode plate is less than the flow channel depth of the cathode plate. The smaller anode flow channel depth helps to reduce the spatial distance between hydrogen and the membrane electrode catalyst layer, thereby reducing mass transfer resistance and improving the single cell reaction efficiency. In addition, the air flow rate required for the electrochemical reaction of the fuel cell is much greater than the hydrogen flow rate, so the pressure drop of the cathode flow field is significantly greater than that of the anode. By setting the cathode flow channel depth to be larger, the air flow resistance is reduced to meet the performance indicators of the system air compressor.

[0028] In the bipolar plate of the present application, the depth of the sealing groove of the anode plate is the same as that of the cathode plate, and the gas field sides of the anode plate and the cathode plate are provided with sealing rings integrally injection molded in the sealing groove. In other words, the depth of the sealing groove of the bipolar plate is different from the depth of the flow channel. By setting the sealing groove depth of the anode and cathode plates to be the same, the sealing ring heights of the anode and cathode plates are consistent, which directly reduces the impact of the manufacturing tolerance on the anode sealing pressure and makes the sealing design more reliable. And because the sealing groove depths of the anode and cathode plates are the same, the sealing cross-sectional areas of the anode and cathode plates are consistent, and the injection speeds of the gas field side of the cathode plate and the gas field side of the anode plate are consistent, thereby effectively avoiding the problem of deformation of the bipolar plate due to different injection pressures on both sides. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 A schematic diagram of the assembly structure of the bipolar plate and the membrane electrode in one or more embodiments of the present application is shown.

[0031] Figure 2 A schematic structural diagram of the anode plate side of a bipolar plate in one or more embodiments of the present application is shown.

[0032] Figure 3 A schematic structural diagram of the cathode plate side of a bipolar plate in one or more embodiments of the present application is shown.

[0033] Figure 4 Shows Figure 2 and Figure 3 Schematic diagram of the structure of the sealing ring of the bipolar plate.

[0034] Figure 5 A schematic structural diagram of the cooling liquid medium port of the bipolar plate in one or more embodiments of the present application is shown.

[0035] Figure 6 Shows Figure 5 Top view of the .

[0036] Figure 7 Shows Figure 6 AA section view.

[0037] Figure 8 A schematic diagram of the positions of the height adjustment lines and welding lines of the bipolar plates in one or more embodiments of the present application is shown, in which the red lines represent the sealing rings and sealing grooves, the green lines represent the sealing welding lines, and the blue lines represent the height adjustment lines.

[0038] Fig. 9 A schematic structural diagram of the hydrogen medium port of a bipolar plate in one or more embodiments of the present application is shown. The figure shows the anode plate of the bipolar plate, and the cathode plate is located on the back and is not visible.

[0039] Fig.10 The schematic diagram shows the injection molding principle of the bipolar plate in one or more embodiments of the present application. Figure 1 , the figure shows the cathode plate of the bipolar plate, and the anode plate is located on the back and is not visible.

[0040] Fig.11 The schematic diagram shows the injection molding principle of the bipolar plate in one or more embodiments of the present application. Figure 2 .

[0041] Fig.12 A schematic diagram of the structure of the bipolar plate cooperating with the injection mold during injection molding in one or more embodiments of the present application is shown.

[0042] Explanation of reference numerals: 10-medium port, 11-air medium port, 12-hydrogen medium port, 13-coolant medium port; 20-active area, 21-flow channel; 30-sealing groove, 31-outer frame sealing groove, 32-inner frame sealing groove, 33-separation sealing groove; 40-sealing ring, 41-outer frame sealing ring, 42-inner frame sealing ring, 43-separation sealing ring, 40a-cathode sealing ring, 40b-anode sealing ring; 50-supporting part; 60-supporting rib; 70-flow guide channel, 71-through hole; 80-sealing welding wire, 81-outer frame welding wire, 82-inner frame welding wire; 90-height adjustment area, 91-height adjustment wire. 100-bipolar plate, 101-cathode flow field, 102-anode flow field, 103-coolant flow field, 110-cathode plate; 120-anode plate. 200-membrane electrode. 300-Injection mold. DETAILED DESCRIPTION

[0043] In order to make the technical personnel in the technical field to which the present application belongs to understand the present application more clearly, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0044] In the related technology, the flow channel depth of the bipolar plate is consistent with the sealing groove depth, and the sealing weld line and the weld line in the active area can be continuously welded during laser welding, which has high production efficiency and is suitable for mass production. However, with the development of fuel cells, the power of fuel cells has gradually increased, and the area and number of bipolar plates have increased accordingly, which requires the thickness of the substrate to be thinner. Thinner substrates bring challenges to the manufacturing process, and the deterioration of the rigidity of the bipolar plate itself brings hidden dangers to the injection molding seal of the bipolar plate.

[0045] When the channel depth of the anode plate is less than that of the cathode plate, the channel depth is consistent with the sealing groove depth, which makes the sealing groove depth of the anode plate less than that of the cathode plate. Under the same sealing compression rate design requirements, the anode sealing height is relatively smaller. In this way, considering the manufacturing tolerance of ±0.05mm, the anode sealing pressure decays significantly. The greater the difference in the depth of the anode and cathode channels, the greater the impact, and it may even cause core leakage.

[0046] In addition, since the cross-sectional area of ​​the anode seal is small, the cross-sectional area of ​​the cathode seal is relatively larger. During injection molding, under the same injection pressure, the anode rubber has a greater flow resistance, flows slowly, and takes a long time to fill; the cathode rubber has a relatively smaller flow resistance, flows quickly, and takes a short time to fill. The difference in injection flow rate on both sides directly causes the cathode glue to flow through some locations in advance, while the anode glue has not yet arrived, causing the bipolar plates at these locations to collapse toward the anode, resulting in glue overflow. Please refer to Fig.11 The area indicated by O is one of the deformation areas of the bipolar plate with different depths of the sealing grooves of the cathode and anode plates. The cathode side sealing groove in the area indicated by O corresponds to the anode side sealing groove, but the arrival time of the glue is not equal, resulting in the cathode plate being subjected to greater injection pressure than the anode plate, and the bipolar plate collapses toward the anode in the area indicated by O.

[0047] Therefore, the current bipolar plates all adopt a design in which the channel depth of the anode and cathode plates is the same, and the channel depth is consistent with the sealing groove depth. This design will cause low oxygen concentration and lack of gas at the cathode outlet in high-power or even ultra-high-power fuel cells, requiring the configuration of a higher-performance air compressor, which increases costs. In addition, the mass transfer resistance of the anode is large, which reduces the reaction efficiency of the single cell.

[0048] To this end, the present application provides a bipolar plate and a preparation process thereof, a fuel cell and a vehicle, which can solve the problems existing in the bipolar plates in the related art to a certain extent.

[0049] In a first aspect of the present application, a bipolar plate 100 is provided. Figure 1 , Figure 2 and Figure 3 , shows a schematic diagram of the assembly state of the bipolar plate 100 and the membrane electrode, as well as a schematic diagram of the structure of the cathode side and the anode side of the bipolar plate. The bipolar plate 100 includes an anode plate 120 and a cathode plate 110, and both the anode plate 120 and the cathode plate 110 are provided with an active area 20 and a plurality of medium ports 10. The coolant flow field side of the anode plate 120 and the cathode plate 110 is sealed by welding, so that the coolant entering between the anode plate 120 and the cathode plate 110 from the coolant medium port 13 flows to the active area 20, and does not flow out from the hydrogen medium port 12 and the air medium port 11, forming a "two-plate three-field" structure: cathode flow field 101 (air field), anode flow field 102 (hydrogen field), and coolant flow field 103. A flow channel 21 is provided in the active area 20 of the anode plate 120 and the cathode plate 110, and hydrogen and air flow in the flow channel 21. In some embodiments, the anode plate 120 and the cathode plate 110 are also provided with a distribution area and a confluence area, which are both located between the medium port 10 and the active area 20, and play the role of medium distribution and confluence. Distribution channels can also be set in the distribution area and the confluence area, or the distribution area and the confluence area are in a lattice structure.

[0050] See also Figure 1 and Figure 7 , the depth of the flow channel 21 of the anode plate 120 is less than the depth of the flow channel 21 of the cathode plate 110. Unless otherwise specified, the "flow channel depth" in this application refers to the depth of the flow channel 21 in the active area 20. The smaller depth of the flow channel 21 of the anode plate 120 helps to reduce the spatial distance between the hydrogen and the catalyst layer of the membrane electrode 200, thereby reducing the mass transfer resistance of hydrogen and improving the reaction efficiency of the single cell. In addition, the air flow rate required for the electrochemical reaction of the fuel cell is much larger than the hydrogen flow rate. Therefore, the pressure drop of the cathode flow field 101 is significantly greater than that of the anode flow field 102. By setting the cathode flow channel 21 to have a larger depth dimension, the flow resistance of the air is reduced, and the performance index requirements for the air compressor of the air subsystem can be reduced. In some embodiments, the difference between the depth of the flow channel 21 of the anode plate 120 and the depth of the flow channel 21 of the cathode plate 110 is 0.05-0.2 mm, such as 0.06 mm, 0.075 mm, 0.09 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.175 mm, etc.

[0051] See also Figure 7 , the depth of the sealing groove 30 of the anode plate 120 is the same as the depth of the sealing groove 30 of the cathode plate 110, that is, the depth of the sealing groove 30 of the bipolar plate 100 is different from the depth of the flow channel 21. The gas field side of the anode plate 120 and the cathode plate 110 are provided with a sealing ring 40 integrally injection-molded in the sealing groove 30. The sealing ring 40 of the anode plate 120 and the sealing ring 40 of the cathode plate 110 are integrally injection-molded at the same time, but the sealing ring 40 of the anode plate 120 is not connected to the sealing ring 40 of the cathode plate 110. By setting the sealing groove 30 of the cathode and cathode plates 120 to have the same depth, the sealing rings 40 of the cathode and cathode plates 120 are made to have the same height, which directly reduces the influence of the manufacturing tolerance on the anode sealing pressure and makes the sealing design more reliable. Furthermore, since the sealing grooves 30 of the cathode and anode plates 120 have the same depth, the sealing cross-sectional areas of the cathode and anode plates 120 are consistent, and the injection speeds on the gas field side of the cathode plate 110 and the gas field side of the anode plate 120 are consistent, thereby effectively avoiding the problem of deformation of the bipolar plate 100 due to different injection pressures P on both sides.

[0052] Therefore, the bipolar plate 100 of the present application can reduce the mass transfer resistance of the anode medium (hydrogen) and also reduce the flow resistance of the cathode medium (air) in the cathode flow field 101. In addition, the design of inconsistent depths of the sealing groove 30 and the flow channel 21 makes the sealing cross-sections on both sides consistent, avoiding the problem of injection molding overflow caused by deformation of the bipolar plate 100 due to injection molding flow differences, and also improving the reliability of the fuel cell stack core seal.

[0053] See also Figure 2 , Figure 3 and Figure 4, shows a schematic structural diagram of the sealing ring 40 of the bipolar plate 100 in some embodiments, the sealing ring 40 includes an outer frame sealing ring 41 surrounding the periphery of the medium port 10, an inner frame sealing ring 42 located between the medium port 10 and the flow channel 21, and a separation sealing ring 43 located between two adjacent medium ports 10. The inner frame sealing ring 42 of the anode plate 120 and the corresponding inner frame sealing ring 42 of the cathode plate 110 are staggered, as shown in FIG. Figure 5 and Figure 7 The direction of the sealing ring 40 of the bipolar plate 100 is completely consistent with the direction of the sealing groove 30 on the bipolar plate 100. Correspondingly, the sealing groove 30 includes an outer frame sealing groove 31 surrounding the periphery of the medium port 10, an inner frame sealing groove 32 located between the medium port 10 and the flow channel 21, and a separation sealing groove 33 located between two adjacent medium ports 10; the inner frame sealing groove 32 of the anode plate 120 is staggered with the corresponding inner frame sealing groove 32 in the cathode plate 110.

[0054] In some embodiments, the air intake structure of the bipolar plate 100 adopts a cross-over structure, hydrogen and air enter between the anode plate 120 and the cathode plate 110 from the corresponding medium port 10, hydrogen flows out from the outlet opened on the anode plate 120 and enters the anode flow field 102, and air flows out from the outlet opened on the anode plate 120 and enters the cathode flow field 101. To facilitate the entry of hydrogen, air, and coolant between the anode plate 120 and the cathode plate 110, please refer to Figure 5 , Figure 6 and Figure 7 In some embodiments, the area on the anode plate 120 corresponding to the position of the inner frame sealing groove 32 of the cathode plate 110, and the area on the cathode plate 110 corresponding to the position of the inner frame sealing groove 32 of the anode plate 120 are both provided with a support portion 50. It can be understood that at the location of the inner frame sealing groove 32, the inner frame sealing groove 32 is provided on one monopolar plate of the bipolar plate 100, and the support portion 50 is provided on the other monopolar plate, and the support portion 50 supports the bottom of the inner frame sealing groove 32 and provides a channel for the circulation of hydrogen, air, and coolant. The specific structure of the support portion 50 is not limited in this application.

[0055] See also Figure 5 , Figure 6 and Figure 7In some embodiments, support ribs 60 are arranged at intervals on the support portion 50, and the raised surface of the support rib 60 contacts the bottom of the corresponding inner frame sealing groove 32 (the support rib 60 is raised toward the coolant flow field 103 side, and appears as a groove on the gas field side), thereby improving the support stiffness of the bipolar plate 100 at the sealing groove 30 and avoiding deformation under the injection pressure P. The support ribs 60 are arranged at intervals, and guide channels 70 for the flow of fluid medium are formed between adjacent support ribs 60. The support ribs 60 may be convex ribs extending in the flow direction of the medium, or bosses distributed in a dot matrix. In other embodiments, the support ribs 60 may also be curved or broken line convex ribs. The specific structure of the support ribs 60 is not limited in this application.

[0056] See also Figure 5 and Figure 6 In some embodiments, the support ribs 60 are convex ribs extending along the medium flow direction. Fig.12 In order to reduce the deformation of the bipolar plate 100 during injection molding, it is necessary to reduce the flow channel width W_groove of the guide channel 70 to increase the width dimension W_boss of the ridge of the guide channel 70, thereby improving the support stiffness of the support rib 60 to the sealing groove 30. However, if the flow channel width W_groove decreases too much, it will directly affect the flow cross-sectional area of ​​the medium, thereby increasing the flow resistance of the medium, especially the coolant. Therefore, in the actual design of the bipolar plate 100, the flow channel width W_groove and the ridge width W_boss are reduced at the same time, that is, the flow channel period of the guide channel 70 is reduced to increase the support stiffness of the area. In some embodiments, the flow channel period of the guide channel 70 is 1 to 2 mm. For example, for a bipolar plate 100 with a substrate thickness of 0.075 mm, the flow channel period of the guide channel 70 can be 1.5 to 1.7 mm; for a bipolar plate 100 with a substrate thickness less than 0.075 mm, the flow channel period of the guide channel 70 can be 1 to 1.4 mm; for a bipolar plate 100 with a plate thickness of 1 mm, the flow channel period of the guide channel 70 can be 1.6 to 2 mm.

[0057] The back of the flow guide channel 70 on the gas field side is a flow channel groove for the injection mold 300 to extend into. Generally, the mold support width W is required to be no less than 0.5 mm during injection molding. Fig.12 In some embodiments, in order to ensure that the mold has sufficient support width during injection molding, the width dimension W_boss of the back of the guide channel 70 should not be less than 0.5 mm.

[0058] The gas outlet of the flip-over structure is a through hole 71 that penetrates the corresponding anode plate 120 or cathode plate 110. Fig. 9In some embodiments, the anode plate 120 and the cathode plate 110 are provided with the through hole 71 in the area between the inner frame sealing groove 32 and the flow channel 21 and corresponding to the reaction medium port (including the hydrogen medium port 12 and the air medium port 11). The medium port 10, the guide channel 70, the through hole 71 and the flow channel 21 are connected in sequence, and the hydrogen and air enter the guide channel 70 from the corresponding medium port 10, and flow out from the through hole 71 and enter the flow channel 21. During the flow process, the hydrogen gas goes over the anode plate 120 from the coolant flow field 103 side of the anode plate 120 to enter the gas field side of the anode plate 120, and the air goes over the cathode plate 110 from the coolant flow field 103 side of the cathode plate 110 to enter the gas field side of the cathode plate 110, thereby forming a crossing-over air intake structure. The coolant directly enters between the anode plate 120 and the cathode plate 110, so the through hole 71 is not provided in the area corresponding to the coolant medium port 13. Figure 5 and Figure 6 The area shown corresponds to the coolant medium port 13 and has no through hole.

[0059] In some embodiments, the top surface of the support portion 50 is flush with the top surface of the flow channel ridge of the flow channel 21. Figure 7 As shown by the middle line x. That is to say, the highest points of the gas field side of the anode plate 120 and the cathode plate 110 are located on the same plane, which is convenient for fitting with the membrane electrode 200. Since the depth of the sealing groove 30 of the bipolar plate 100 is different from the depth of the flow channel 21, in order to ensure that the support rib 60 fits with the flow channel 21 on the opposite side plate and can stably support the sealing groove 30 on the opposite side plate, the height of the support rib 60 needs to be adjusted to match the depth of the sealing groove 30.

[0060] See also Figure 5 , Figure 6 and Figure 7 In some embodiments, a height adjustment area 90 is provided on the support portion 50. The height adjustment area 90 is located between the inner frame sealing groove 32 of the plate where the height adjustment area 90 is located and the flow channel 21. The height adjustment area 90 is flush with the groove bottom of the flow channel groove of the flow channel 21. On the coolant flow field 103 side of the bipolar plate 100, the top surface of the support rib 60 located on the side of the height adjustment area 90 close to the inner frame sealing groove 32 of the plate where the height adjustment area 90 is located is consistent with the groove bottom height of the inner frame sealing groove 32. Figure 7 The top surface of the support rib 60 located at the height adjustment area 90 close to the flow channel 21 of the plate where it is located is consistent with the bottom surface of the flow channel groove 21, as shown in the middle line z; Figure 7 Indicated by the middle line y.

[0061] The height adjustment line 91 formed by the height adjustment area 90 may be a straight line, such as Figure 5 , Figure 6 and Figure 8As shown, the straight line passes through at least part of the support rib 60 and is parallel to the side of the bipolar plate 100 or the inner side of the medium port 10; preferably, in some embodiments, the height adjustment line 91 corresponding to the hydrogen medium port 12 and the air medium port 11 is parallel to the inner side of the hydrogen medium port 12 and the air medium port 11, so that the depth of the flow channel located on the side of the height adjustment line 91 close to the active area 20 remains unchanged and the flow resistance is small. In some embodiments, the height adjustment line 91 can also be a curve, for example, the height adjustment line 91 is the same as the edge profile of the support portion 50; preferably, in some embodiments, the height adjustment line 91 formed by the height adjustment area 90 coincides with the end connection line of the flow channel 21 on the opposite side plate.

[0062] See also Figure 8 In some embodiments, the height adjustment line 91 is arranged outside the active area 20 to form a closed structure. The height adjustment line 91 corresponding to the hydrogen medium port 12 and the air medium port 11 can ensure the continuity of the sealing weld line 80 at the corresponding position, thereby ensuring the welding seal of the coolant flow field 103. In some embodiments, the top surface of each support rib 60 corresponding to the coolant medium port 13 can also be arranged to be consistent with the bottom surface height of the flow channel groove of the flow channel 21, and the area corresponding to the coolant medium port 13 does not need to be provided with a height adjustment area.

[0063] Since the bipolar plate 100 adopts a flip-over air intake structure, the raised surface of the support rib 60 contacts the bottom of the corresponding inner frame sealing groove 32. In order to keep the gas field side of the bipolar plate 100 as a highly consistent plane, the sum of the raised height of the support rib 60 and the depth of the inner frame sealing groove 32 should be consistent with the sum of the depth of the flow channel 21 of the anode plate 120 and the depth of the flow channel 21 of the cathode plate 110. Considering that the depth of the sealing groove 30 of the anode plate 120 is the same as the depth of the sealing groove 30 of the cathode plate 110, the depth H_ano of the flow channel 21 of the anode plate 120, the depth H_cath of the flow channel 21 of the cathode plate 110, and the depth H of the sealing groove 30 satisfy the following relationship: H = (H_ano + H_cath) / 2, and H_ano<H<H_cath. In some embodiments, the depth H of the sealing groove 30 is 0.3 mm, the depth H_cath of the flow channel 21 of the cathode plate 110 is 0.35 mm, and the depth H_ano of the flow channel 21 of the anode plate 120 is 0.25 mm.

[0064] In a second aspect of the present application, a preparation process of a bipolar plate 100 is provided, which is used to prepare the bipolar plate 100 of any of the above aspects. The preparation process specifically includes the following steps:

[0065] S1, polar plate forming: stamping the substrate to obtain the anode plate 120 and the cathode plate 110.

[0066] For the bipolar plate 100 with the flip-over air intake structure, the cathode plate 110 and the anode plate 120 are both centrally symmetrical structures, but the structures of the cathode plate 110 and the anode plate 120 are different, so the two substrates need to be respectively stamped by corresponding stamping dies to form the anode plate 120 and the cathode plate 110. For the bipolar plate 100 with the same structure of the anode plate 120 and the cathode plate 110, only one set of stamping dies is needed.

[0067] S2. Plate welding: welding the areas corresponding to the sealing grooves 30 and the active area 20 of the anode plate 120 and the cathode plate 110 , wherein the welding Z-axis coordinates of the areas corresponding to the sealing grooves 30 are different from the welding Z-axis coordinates of the active area 20 .

[0068] The welding of the corresponding areas of the sealing groove 30 of the anode plate 120 and the cathode plate 110 is mainly to form a seal on the side of the coolant flow field 103, see Figure 8 The sealing weld 80 includes an outer frame weld 81 and an inner frame weld 82 surrounding the hydrogen medium port 12 and the air medium port 11, ensuring that the coolant enters between the anode plate 120 and the cathode plate 110 through the coolant medium port 13 and the guide channel 70, and flows out of the bipolar plate 100 from the opposite coolant medium port 13, without entering the hydrogen medium port 12 and the air medium port 11. The outer frame weld 81 is located close to the outer frame sealing groove 31, see Figure 8 In some embodiments, the outer frame welding line 81 overlaps with the outer frame sealing groove 31 , and the inner frame welding line 82 is parallel to the height adjustment line 91 corresponding to the hydrogen medium port 12 and the air medium port 11 .

[0069] The main purpose of welding the active area 20 of the anode plate 120 and the cathode plate 110 is to improve the conductivity of the active area 20 of the anode plate 120 and the cathode plate 110 and reduce the contact resistance of the anode plate 120 and the cathode plate 110 in the active area 20. Since the depth of the sealing groove 30 is different from the depth of the flow channel 21 in the active area 20, the height of the welding head needs to be adjusted accordingly during welding, specifically, the Z-axis coordinate of the welding is adjusted differently.

[0070] In some embodiments, the sealing groove 30 corresponding area adopts continuous welding to form the sealing welding line 80, and the active area 20 adopts spot welding to form the spot welding line. The specific content of the electrode plate welding is: moving the laser welding head to complete the line welding of the corresponding area of ​​the sealing groove 30 to form the sealing welding line 80; adjusting the Z-axis coordinate of the laser welding head to complete the spot welding operation of the active area 20 step by step to form the spot welding line.

[0071] S3 . Injection molding of the sealing ring 40 : Injection molding of the sealing ring 40 on the sealing groove 30 of the anode plate 120 and the cathode plate 110 , respectively.

[0072] See also Fig.10 , Fig.11 and Fig.12When the sealing ring 40 is injection molded, the welded anode plate 120 and cathode plate 110 are placed together in the injection mold 300. The injection mold 300 and the anode plate 120 and the cathode plate 110 form two independent injection molding cavities respectively, so that the anode plate 120 sealing ring 40 and the cathode plate 110 sealing ring 40 can be injection molded respectively to form the anode plate 120 sealing ring 40 and the cathode plate 110 sealing ring 40, so as to achieve the sealing of the gas field side on both sides of the bipolar plate 100. The injection molding material can be liquid silicone rubber, liquid EPDM, polyolefin, etc., which is not limited in this application. The cross-section of the sealing ring 40 can be trapezoidal, semicircular, peak-shaped, etc., which is not limited in this application. The one-piece injection molding sealing process of the bipolar plate 100 has high sealing molding precision and high production efficiency.

[0073] See also Fig.10 , arrow a shows the flow direction of the sealing glue in the outer frame sealing groove 31 of the anode plate 120 and the cathode plate 110. The outer frame sealing groove 31 of the anode plate 120 corresponds to the outer frame sealing groove 31 of the cathode plate 110 in position and has the same depth, so the injection pressure P of the bipolar plate here is equal. Arrow b shows the flow direction of the sealing glue in the inner frame sealing groove 32 of the anode plate 120, and arrow c shows the flow direction of the sealing glue in the inner frame sealing groove 32 of the cathode plate 110.

[0074] See also Fig.11 The inner frame sealing groove 32 of the anode plate 120 is staggered with the corresponding inner frame sealing groove 32 in the cathode plate 110, but since the support portion 50 and the support rib 60 are provided, the bottom of the sealing groove 30 can be stably supported, and since the depth of the sealing groove 30 is the same, the injection flow rate on the positive and negative sides is the same, the cathode glue and the anode glue flow through the same position at the same time, the injection pressure P at each location of the sealing groove 30 of the bipolar plate 100 can be regarded as equal, and the bipolar plate 100 will not be deformed during the injection molding process.

[0075] In some embodiments, in order to enhance the adhesion between the injection-molded rubber and the corresponding electrode plate, in the process of injection-molding the sealing ring 40, a primer material is firstly applied to the sealing grooves 30 of the anode plate 120 and the cathode plate 110, and the main component of the primer material is at least one of n-hexane, ethyl silicate, ethyl acetate, and n-heptane. Then, glue is injected into the sealing grooves 30 until the glue fills the sealing grooves 30, and the sealing ring 40 is formed after the glue is solidified.

[0076] A third embodiment of the present application provides a fuel cell, wherein a core of the fuel cell is formed by stacking the bipolar plate 100 and the membrane electrode 200 of any one of the embodiments of the first aspect.

[0077] The typical structure of a fuel cell stack includes an intake end plate, an intake end insulating plate (which can be integrated on an intake end plate or an intake end current collecting plate), an intake end current collecting plate, a core, a blind end current collecting plate, a blind end insulating plate (which can be integrated on a blind end plate or a blind end current collecting plate), and a blind end plate, which are stacked in sequence. Some fuel cells are also provided with disc springs and disc spring support plates in addition to the blind end plates. One end of the fastener is connected to the intake end plate, and the other end is connected to the blind end plate or the disc spring support plate, providing a fastening force in the stacking direction to the entire stack. In some embodiments, a box packaging structure can be used, and the outer shell of the fuel cell provides a fastening force in the stacking direction for the stack. Other structures of the fuel cell that are not described in detail can refer to the relevant disclosures of the prior art and are not described in detail here.

[0078] The fourth aspect of the present application provides a vehicle, including a fuel cell according to any one of the third aspects. Since the vehicle is equipped with the fuel cell, it at least has all the beneficial effects brought by the technical solution of the fuel cell. Other undetailed structures of the vehicle can refer to the relevant disclosure of the prior art and will not be described here.

[0079] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0080] In the description of the present application, 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" and "counterclockwise" 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 application 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 a limitation on the present application.

[0081] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; 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 this application can be understood according to specific circumstances.

[0082] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0083] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A bipolar plate, comprising an anode plate and a cathode plate having an active area and a plurality of dielectric ports, characterized in that: The flow channel depth of the anode plate is smaller than that of the cathode plate; the sealing groove depth of the anode plate is the same as that of the cathode plate; the gas field sides of the anode plate and the cathode plate are both provided with sealing rings integrally injection-molded in the sealing groove.

2. The bipolar plate according to claim 1, characterized in that: The sealing groove includes an outer frame sealing groove surrounding the medium port, an inner frame sealing groove located between the medium port and the flow channel, and a separation sealing groove located between two adjacent medium ports; the inner frame sealing groove of the anode plate and the corresponding inner frame sealing groove in the cathode plate are staggered.

3. The bipolar plate according to claim 2, characterized in that: The area on the anode plate corresponding to the position of the inner frame sealing groove of the cathode plate and the area on the cathode plate corresponding to the position of the inner frame sealing groove of the anode plate are both provided with a support portion; the support portion is provided with support ribs distributed at intervals, and the convex surface of the support ribs contacts the bottom of the corresponding inner frame sealing groove; and a guide channel for the flow of fluid medium is formed between adjacent support ribs; The anode plate and the cathode plate are provided with through holes in the areas between the inner frame sealing groove and the flow channel and corresponding to the reaction medium port, and the medium port, the guide channel, the through holes and the flow channel are connected in sequence.

4. The bipolar plate according to claim 3, characterized in that: The top surface of the support portion is flush with the top surface of the flow channel ridge of the flow channel; The support portion is provided with a height adjustment area, the height adjustment area is located between the inner frame sealing groove and the flow channel, and the height adjustment area is flush with the groove bottom of the flow channel groove of the flow channel.

5. The bipolar plate according to claim 3, characterized in that: The flow channel period of the flow guide channel is 1-2 mm; the ridge width W_boss of the flow guide channel is not less than 0.5 mm.

6. The bipolar plate according to claim 3, characterized in that: The flow channel depth H_ano of the anode plate, the flow channel depth H_cath of the cathode plate, and the depth H of the sealing groove satisfy: H=(H_ano+H_cath) / 2.

7. The bipolar plate according to any one of claims 1 to 6, characterized in that: The difference between the flow channel depth of the anode plate and the flow channel depth of the cathode plate is 0.05-0.2 mm.

8. A process for preparing the bipolar plate according to any one of claims 1 to 7, characterized in that: The steps include: Plate forming: stamping the substrate to obtain the anode plate and the cathode plate; Plate welding: welding the sealing groove corresponding area and the active area of ​​the anode plate and the cathode plate, wherein the welding Z-axis coordinate of the sealing groove corresponding area is different from the welding Z-axis coordinate of the active area; Injection-molded sealing rings: Injection-molded sealing rings are respectively formed on the sealing grooves of the anode plate and the cathode plate.

9. The preparation process according to claim 8, characterized in that: The electrode plate welding specifically includes: Moving the laser welding head to complete the line welding of the corresponding area of ​​the sealing groove to form a sealing welding line; The Z-axis coordinate of the laser welding head is adjusted to complete the spot welding operation of the active area step by step to form a spot welding line.

10. The preparation process according to claim 8, characterized in that: The injection molding sealing ring specifically comprises: Coating a primer material on the sealing grooves of the anode plate and the cathode plate respectively, wherein the main component of the primer material is at least one of n-hexane, ethyl silicate, ethyl acetate and n-heptane; Glue is injected into the sealing grooves respectively and the sealing grooves are filled with glue, and the sealing ring is formed after the glue is solidified.

11. A fuel cell, characterized in that: The bipolar plate comprises the bipolar plate according to any one of claims 1 to 7.

12. A vehicle, characterized in that: Comprising the fuel cell according to claim 11.

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