A fuel cell bipolar plate

Abstract

A fuel cell bipolar plate includes a first plate and a second plate, and the first plate and the second plate have the same structure; both plates include gas flow channels, ribs, a first plane, a second plane and a third plane; the first plane is the reference plane of the metal plate, and the first plane includes a gas transition region and a sealing ring plane, the second plane is the bottom plane of the gas flow channel, the second plane is higher than the first plane, and the gas is in a stepped shape at the entrance where it enters the flow channel from the transition region; when the two plates are buckled, a sandwich layer is formed between the two bottom planes of the gas flow channels, and the sandwich layer provides a flow channel for the coolant; each gas flow channel of the plate further includes a cylindrical depression and a hemispherical protrusion, and the centers of the cylindrical depression and the hemispherical protrusion are evenly spaced on the central axis of the gas flow channel.

Description

Technical Field

[0001] The present invention belongs to the field of fuel cells, and particularly relates to a metal bipolar plate structure in a fuel cell stack and a coolant channel field in the fuel cell. Background Art

[0002] Since the Industrial Revolution, clean and inexpensive energy has gradually become the driving force for the world's increasing prosperity and economic development. The environmental impact of traditional energy sources such as oil, coal, and natural gas has become increasingly significant during their use, and these energy sources are finite. Unrestricted use will accelerate the depletion of the earth's energy. In the face of these problems, the development of fuel cell technology has made breakthroughs in recent years, and the global use of fuel cells has entered a new stage. Fuel cells are used for power supply in fields such as automobiles and aerospace.

[0003] The bipolar plate is one of the core components of a fuel cell, accounting for 80% of the battery pack's mass and 45% of the cost. The bipolar plate has multiple important functions such as conducting current, supporting the membrane electrode, uniformly delivering and isolating reaction gases, circulating coolant, and dissipating heat quickly.

[0004] Currently, there are also many types of flow field forms for bipolar plates, including parallel flow channels, interdigitated flow channels, serpentine flow channels, mesh flow fields, dot flow fields, etc. A suitable flow channel structure in the bipolar plate is beneficial to the discharge of water to improve the flooding situation, make the concentration distribution of reactants uniform throughout the flow field, avoid local overheating, and improve the performance of the fuel cell.

[0005] The bipolar plate materials widely used in proton exchange membranes are divided into three types: graphite materials, metal materials, and composite materials. Graphite bipolar plates have good electrical conductivity, thermal conductivity, stability, and corrosion resistance, but their mechanical properties are relatively poor, brittle, and difficult to machine, resulting in higher costs. In addition, the weight of the graphite bipolar plate fuel cell stack is relatively heavy. Metal bipolar plates have good electrical conductivity, light weight, and low cost, but the complex structure of metal bipolar plates affects the assembly quality and battery performance. And due to the limitations of the current metal bipolar plate forming process, although bipolar plates with complex structures can solve drainage and improve battery efficiency, they are difficult to process, and at the same time, the high precision requirements will also increase the cost of the bipolar plate.

[0006] A Chinese invention patent (application number 201910330023.1) discloses a fuel cell plate and a fuel cell, wherein the fuel cell plate includes a plate body, wherein the first surface of the plate body includes a first strip-shaped protrusion, wherein the extension direction of the first strip-shaped protrusion is cross-set with the extension direction of the gas flow channel, so that the gas flow channel becomes a concave-convex structure, which enhances the turbulent flow during gas flow, improves the reaction efficiency, and reduces the length of the plate. The premise proposed by the patent for drainage is that the placement direction of the fuel cell is required (the flow direction of the reaction gas is vertical, and the flow direction is from top to bottom. If it is placed horizontally, flooding is likely to occur, and the water generated in the flow channel is likely to gather at the bottom of the concave-convex flow channel); the patent requires the metal plate to be processed in two directions, and the stamping process at the intersection of the double flow channels will result in a larger chamfer radius, which will affect the flow channel structure and the strength of the overall fuel cell, thereby affecting the battery performance. Channel-type coolants are affected by the size of the coolant flow channel, requiring a smaller flow rate and lower cooling efficiency. If the flow rate is increased, the pressure will increase. Due to the complex internal structure, the strength of the metal plate must be higher, otherwise the metal plate will be deformed and affect the battery performance.

[0007] In summary, it is necessary to propose a multifunctional metal dual-machine plate that can enhance the turbulent flow during gas flow, avoid flooding, have no restrictions on the placement of bipolar plates, provide channels for coolant, and has a simple structure and low processing difficulty. Summary of the invention

[0008] Based on this, in order to solve the technical problems existing in the background technology, the purpose of the present invention is to improve the drainage performance of the cathode plate flow channel while taking into account the improvement of the power density of the fuel cell, and to simplify the plate structure and reduce the process difficulty of metal plate processing while providing a coolant interlayer in the metal bipolar plate, thereby improving the strength of the bipolar plate itself, thereby achieving higher and more stable efficiency of the fuel cell stack.

[0009] The purpose of the present invention is to design a flow channel type that can increase the current density and facilitate the discharge of product water at the cathode plate. Without affecting the increase in current density, the flow channel is designed so that two polar plates are combined into a bipolar plate and a sandwich is formed for the coolant to pass through, thereby reducing the temperature of the battery stack.

[0010] A fuel cell bipolar plate includes a first plate and a second plate, and the first plate and the second plate have the same structure. Both plates include gas flow channels, ribs, a first plane, a second plane, and a third plane. The first plane is the reference plane of the metal plate, and the first plane includes a gas transition region and a sealing ring plane. The second plane is the bottom plane of the gas flow channel, and the second plane is higher than the first plane. The gas enters the inlet of the flow channel from the transition region in a stepped manner. When the two plates are buckled, a sandwich is formed between the bottom planes of the two gas flow channels, and the sandwich provides a flow channel for the coolant. Each gas flow channel of the plate further includes a cylindrical depression and a hemispherical protrusion, and the centers of the cylindrical depression and the hemispherical protrusion are evenly distributed on the central axis of the gas flow channel. The third plane is the top surface of the flow channel rib and also the upper end surface of the plate. The third plane is higher than the upper vertex of the hemispherical protrusion, and the spherical radius of the hemispherical protrusion is smaller than the width of the gas flow channel, so that the water generated in the cathode flow channel is discharged from both sides of the hemispherical protrusion.

[0011] Preferably, the height difference between the second plane and the first plane is set to 1 / 10 of the overall thickness of the first plate.

[0012] Preferably, the height of the hemispherical protrusion in the gas flow channel is slightly lower than the height of the gas flow channel rib.

[0013] Preferably, the bottom plane of the cylindrical depression in the gas flow channel and the third plane are parallel to the first plane at the inlet.

[0014] Preferably, the centers of the hemispherical protrusions and the cylindrical depressions in the gas flow channel are located on the center line of the flow channel width.

[0015] Preferably, the cylindrical diameter of the cylindrical depression in the gas flow channel is less than 3 / 4 of the flow channel width and greater than 1 / 2 of the flow channel width.

[0016] Preferably, for the two plates with the same structure, namely the first plate and the second plate, after the first plate is rotated around the long side and overlapped with the second plate, the bottoms of the cylindrical depression structures of the two plates are in contact with each other and overlap.

[0017] Preferably, the two adjacent air inlets are arranged at intervals, and the two adjacent air outlets are arranged at intervals.

[0018] Preferably, the plate is made of a metal or alloy thin plate with a thickness less than 0.5 mm by a pressure processing method.

[0019] The fuel cell plate provided by the present invention has a height difference between the first plane and the second plane of the plate, so that when two plates are combined into a bipolar plate, a middle sandwich layer is formed. The area of the sandwich layer is for the coolant to pass through. The cylindrical concave structure in the flow channel provides structural support for the sandwich layer, avoiding the deformation of the plate caused by the sandwich space. The hemispherical protrusions in the flow channel increase the flow disturbance effect, making the reaction of the gas in the flow channel more sufficient, improving the power density. At the same time, the product water generated on the cathode plate side will flow away from the gaps on both sides of the hemispherical protrusions, which is beneficial to the discharge of water, thus avoiding flooding. The flow cross-section of the coolant, and the flow channel has an area-type flow direction, which is in full contact with the reaction gas flow channel, and the contact area is large, the water flow rate is large, and the heat carried away is high, so the cooling effect is excellent. And the cylindrical concave makes the pressure of the coolant in the sandwich layer more uniform, plays a role in fluid disturbance on the coolant in the coolant channel, and at the same time the temperature distribution is more uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic three-dimensional structure diagram of the fuel cell plate of the present invention;

[0021] Figure 2 is the fuel cell plate of the present invention Figure 1 Partial enlarged view of part A therein;

[0022] Figure 3 is an exploded view of the structure of the fuel cell bipolar plate of the present invention;

[0023] Figure 4 is a three-dimensional sectional view of the fuel cell bipolar plate of the present invention;

[0024] Figure 5 is Figure 4 Partial enlarged view of part B therein;

[0025] Figure 6 is a front view of the fuel cell bipolar plate;

[0026] Figure 7 is Figure 6 Sectional view of the fuel cell bipolar plate in the C-C direction therein;

[0027] Figure 8 is Figure 7 Partial enlarged view E therein;

[0028] Figure 9 is Figure 6 Sectional view of the fuel cell bipolar plate in the D-D direction therein;

[0029] Figure 10 is Figure 9 Partial enlarged view F therein;

[0030] Figure 11 is Figure 9The partial enlarged view G in

[0031] Figure 12 is Figure 9 The partial enlarged view H in

[0032] Figure 13 is Figure 6 The partial enlarged view I in Detailed implementation mode

[0033] For the convenience of understanding the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0034] The present invention provides a bipolar plate, which includes two single plates. One side of the single plate is a flow field channel, and the other side forms a sandwich in the middle after the bipolar plates are combined through a stepped structure. And the cylindrical depression provides a supporting effect for the middle area of the plate after the two plates are combined into a bipolar plate, ensuring the strength of the bipolar plate and preventing the deformation of the plate; a hemispherical protrusion is arranged in the middle of the flow channel of the plate to increase the turbulence effect of the reaction gas, improve the reaction efficiency, and enable the product water formed in the cathode plate to flow away from both sides of the hemispherical protrusion, preventing flooding, and there is no restriction on the placement of the fuel cell stack.

[0035] The present invention provides a bipolar plate, one side of the single plate of which is a flow field channel, and the other side forms a sandwich in the middle after the bipolar plates are combined through a stepped structure. And the cylindrical depression provides a supporting effect for the middle area of the plate after the two plates are combined into a bipolar plate, ensuring the strength of the bipolar plate and preventing the deformation of the plate; a hemispherical protrusion is arranged in the middle of the flow channel of the plate to increase the turbulence effect of the reaction gas, improve the reaction efficiency, and enable the product water formed in the cathode plate to flow away from both sides of the hemispherical protrusion, preventing flooding, and there is no restriction on the placement of the fuel cell stack.

[0036] Such as Figure 1-2As shown, this is an embodiment of the present invention. The present invention provides a fuel cell bipolar plate, which includes plate 1 and plate 2, and the structures of plate 1 and plate 2 are the same; both plates include a gas flow channel 25, ribs 26, a first surface 11, a second surface 12, and a third surface 13; the first surface 11 is the reference surface of the metal plate, and the first plane 11 includes a gas transition region 24 and a sealing ring plane 23. The second plane 12 is the bottom plane of the gas flow channel, and the second plane 12 is higher than the first plane 11. The height difference between the second surface 12 and the first plane 11 is set to 1 / 10 of the overall thickness of plate 1. The gas enters the inlet of the flow channel from the transition region 24 in a stepped manner; when the two plates are buckled, a sandwich layer is formed between the two bottom planes of the gas flow channels, and the sandwich layer 27 provides a flow channel for the coolant; each gas flow channel 25 of the plate also includes a cylindrical depression 15 and a hemispherical protrusion 14. The centers of the cylindrical depression 15 and the hemispherical protrusion 14 are evenly distributed on the central axis of the gas flow channel 25; the third plane 13 is the top surface of the flow channel rib and is also the upper end surface of the plate. The third plane 13 is higher than the upper vertex of the hemispherical protrusion 14, and the spherical radius of the hemispherical protrusion 14 is smaller than the width of the gas flow channel 25, so that the water generated in the cathode flow channel is discharged from both sides of the hemispherical protrusion 14.

[0037] As Figure 3 shown, there are two identical plates 1 and 2. After one of them is rotated 180° around the long side of the plate, the two plates coincide, and the inlets 18 of the two plates are staggered from each other. Oxygen is introduced into the inlet of the cathode plate, and hydrogen is introduced into the inlet of the anode plate, and the gas outlets 19 are also staggered from each other; at the same time, the coolant channel structures between the two plates cooperate to form a complete channel.

[0038] As Figure 4 shown, since the second plane 12 is higher than the first plane 11, when the two plates are combined, there is a gap in the middle. The height of the gap is twice the height difference between the second plane 12 and the first plane 11, and the height of the gap can be adjusted by the step height. At the same time, the pressure of the coolant passing through the coolant flow channel can be reduced, avoiding deformation of the metal plate due to excessive pressure.

[0039] As Figure 5 shown, after the two plates are combined, the cylindrical depressions 15 coincide and contact with each other, increasing the supporting force between the two plates. At the same time, it also strengthens the overall strength of the fuel cell and even the stack, avoiding deformation of the metal bipolar plate due to extrusion during the assembly process, uneven stress on the proton exchange membrane, and increasing the pulling force to cause damage to the proton exchange membrane; the cylindrical depression 15 plays a role in uniform stress, protecting the proton exchange membrane, and increasing the overall structural strength of the fuel cell.

[0040] As Figure 5As shown, the cylindrical depressions 15 and the hemispherical protrusions 14 are staggered in distribution. The staggered distribution can make the gas concentration distribution more uniform, increase the gas flow length, and increase the reaction efficiency.

[0041] like Figure 6 As shown, the air inlet 18 and the air outlet 19 are staggered, which can extend the distance of the gas and increase the reaction efficiency. The gas flows in a vertical direction (as shown in the middle). In real cases, due to the special design of the flow channel, there is no restriction on the placement of the flow channel, and it can be placed vertically or horizontally.

[0042] like Figure 6 As shown, the coolant inlet 16 and the coolant outlet 17 are located at both ends of the bipolar plate, and are cross-distributed with the gas flow channel, and the gas flow direction and the coolant flow direction are perpendicular to each other.

[0043] like Figure 7 and Figure 8 As shown, the coolant has a flow section 20, and the flow channel is an area-type flow direction, which is in full contact with the reaction gas flow channels 21 and 22, and has a large contact area. The water flow is large and the heat taken away is high, so the cooling effect is excellent. The cylindrical depression makes the pressure of the coolant in the interlayer more uniform, which has a fluid disturbance effect on the coolant in the coolant channel, and the temperature distribution is more uniform.

[0044] like Figure 8 As shown, the height of the hemispherical protrusion 14 in the flow channel is slightly lower than the third plane 13 of the top surface of the flow channel rib, so that it does not contact the proton exchange membrane, increasing the reaction area between the fuel gas and the membrane; the direction of movement of the arrow is the local movement trajectory of the gas in the flow channel. When encountering the hemispherical protrusion 14, the gas flow changes, and the gas needs to cross the hemispherical protrusion 14 or flow from both sides, increasing the turbulence of the gas, thereby improving the reaction efficiency and enhancing the battery performance.

[0045] like Figure 8 As shown, the hemispherical protrusion 14 and the cylindrical depression 15 in the flow channel are symmetrically located, the cylindrical depressions 15 overlap and contact each other, and the supporting surface of the middle area of the two plates is the circular bottom surface of the cylindrical depression 15 .

[0046] like Figure 9 As shown, the arrow direction is the flow direction of the coolant DD. The coolant enters the interlayer of the bipolar plate from the coolant inlet 16, flows in the interlayer of the bipolar plate in the direction of the arrow, and is finally discharged from the outlet 17. It is particularly noted that the direction in which the coolant enters the inlet and is discharged from the outlet can be the same direction or opposite directions.

[0047] like Figure 10 As shown, the arrow direction is the flow direction of the coolant in the inlet part.

[0048] like Figure 11As shown, the arrow direction indicates the flow direction of the coolant in the interlayer of the bipolar plate.

[0049] As Figure 12 shown, the arrow direction indicates the flow direction of the coolant in the outlet part.

[0050] As Figure 13 shown, the water generated in the cathode plate flows out in the direction indicated by the arrow. The product water passes horizontally through the cylindrical depression 15, and then passes through both sides of the hemispherical protrusion 14. While increasing the flow disturbance, it is also beneficial to the discharge of the product water. And if water is generated on the surface of the hemispherical protrusion 14, due to the arc-shaped structure of the hemisphere, the water will also slide down from the arc surface of the hemisphere to the bottom of the flow channel and thus flow out.

[0051] A bipolar plate for a fuel cell provided by the present invention has been verified by professional simulation software, which is beneficial to improving the performance of the fuel cell. Compared with the traditional straight channel, the performance is improved by nearly 10%. And from the distribution of the product water on the bipolar plate, the overall distribution of the water concentration is also lower than that of the traditional straight channel, and the temperature distribution is more uniform than that of the traditional straight channel.

[0052] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0053] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A fuel cell bipolar plate, characterized in that, Comprising: A first plate and a second plate, the structures of the first plate and the second plate being the same; both plates include a gas flow channel, ribs, a first plane, a second plane, and a third plane; the first plane is the reference plane of the metal plate, and the first plane includes a gas transition region and a sealing ring plane. The second plane is the bottom plane of the gas flow channel, and the second plane is higher than the first plane. The gas enters the inlet of the flow channel from the transition region in a stepped manner. When the two plates are buckled together, a sandwich layer is formed between the two bottom planes of the gas flow channels, and the sandwich layer provides a flow channel for the coolant. Each gas flow channel of the plate further includes a cylindrical depression and a hemispherical protrusion, and the centers of the cylindrical depression and the hemispherical protrusion are evenly spaced along the central axis of the gas flow channel. The third plane is the top surface of the flow channel rib, and the third plane is the upper end surface of the plate. The third plane is higher than the upper vertex of the hemispherical protrusion, and the spherical radius of the hemispherical protrusion is less than the width of the gas flow channel, so that the water generated in the cathode flow channel is discharged from both sides of the hemispherical protrusion. When the two plates are combined, there is a gap in the middle. The height of the gap is twice the height difference between the second plane and the first plane, and the height of the gap can be adjusted by the step height. The cylindrical depressions coincide with each other and are in contact, increasing the supporting force between the two plates.

2. A fuel cell bipolar plate according to claim 1, wherein The height difference between the second plane and the first plane is set to 1 / 10 of the overall thickness of the first plate.

3. A fuel cell bipolar plate according to claim 2, wherein The cylindrical diameter of the cylindrical depression in the gas flow channel is less than 3 / 4 of the flow channel width and greater than 1 / 2 of the flow channel width.

4. A fuel cell bipolar plate according to claim 1, wherein Two adjacent air inlets are spaced apart, and two adjacent air outlets are spaced apart.

5. A fuel cell bipolar plate according to claim 1, wherein The plate is made by a pressure processing method using a metal thin plate with a thickness less than 0.5 mm.

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