CN110828843A - A fuel cell bipolar plate - Google Patents

Abstract

A fuel cell bipolar plate includes a first plate and a second plate, the first plate and the second plate have the same structure; the two plates both include a gas flow channel, a rib, a first plane, a second plane and a second plane. Three planes; the first plane is the reference plane of the metal plate, the first plane includes the gas transition area and the 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 flows from The entrance of the transition area into the flow channel is stepped; when the two polar plates are buckled, an interlayer is formed between the bottom planes of the two gas channels, and the interlayer provides a flow channel for the cooling liquid; each of the polar plates The gas flow channel also includes cylindrical depressions and hemispherical protrusions, and the centers of the cylindrical depressions and hemispherical protrusions are evenly distributed on the central axis of the gas flow channel.

Description

A fuel cell bipolar plate

technical field

The invention belongs to the field of fuel cells, in particular to the field of a metal bipolar plate structure in a fuel cell stack and a cooling liquid channel in the fuel cell.

Background technique

Since the Industrial Revolution, clean and cheap energy has gradually become the driving force behind the increasingly prosperous world and economic development. Traditional energy sources such as oil, coal and natural gas have an increasingly significant impact on the environment in the process of use, and these energy sources are limited energy sources. Unrestricted use will accelerate the depletion of the earth's energy sources. Faced with these problems, the development of fuel cell technology has made breakthroughs in recent years, and the global use of fuel cells has also entered a new stage. Fuel cells are used for power supply in automotive, aerospace and other fields.

The bipolar plate is one of the core components of the fuel cell, accounting for 80% of the mass of the battery pack and 45% of the cost. The bipolar plate has many important functions such as conducting current, supporting membrane electrodes, uniformly transporting and isolating reactive gases, circulating coolant, and rapidly dissipating heat.

At present, there are many types of flow fields in bipolar plates, including parallel flow channels, interdigitated flow channels, serpentine flow channels, mesh flow fields, and point flow fields. The proper flow channel structure in the bipolar plate is conducive to the discharge of water and improves the flooding situation, so that the concentration distribution of reactants in the entire flow field is uniform, local overheating is avoided, and the performance of the fuel cell is improved.

There are three types of bipolar plate materials widely used in proton exchange membranes: graphite materials, metal materials, and composite materials. Graphite bipolar plates have good electrical conductivity, thermal conductivity, stability and corrosion resistance, but relatively poor mechanical properties, brittleness, high cost due to difficult machining, and heavier weight of graphite bipolar plate stacks. The metal bipolar plate has good conductivity, light weight and low cost, but the complex structure of the metal bipolar plate affects the assembly quality and battery performance, and is limited by the current metal bipolar plate forming process, although the complex structure of the bipolar plate can be solved. Drains water and improves battery efficiency, but it is difficult to process, and higher precision requirements also increase the cost of bipolar plates.

The Chinese invention patent (application number 201910330023.1) discloses a fuel cell electrode plate and a fuel cell. The fuel cell electrode plate includes a plate body, and the first surface of the plate body includes a first strip-shaped protrusion. The first stripe The extending direction of the protruding protrusion and the extending direction of the gas flow channel are arranged to cross, so that the gas flow channel has a concave-convex structure, which enhances the turbulent operation during gas flow, improves the reaction efficiency, and reduces the length of the electrode plate. The premise proposed by the patent to facilitate drainage requires the placement direction of the fuel cell (the flow direction of the reaction gas is vertical, and the flow direction is from top to bottom. Converging at the bottom of the concave-convex runner); the patent requires that the metal plate be processed in two directions, and the punching process at the intersection of the double runners will cause the chamfer radius to be too large, which will affect the runner structure and the overall strength of the fuel cell, thereby affecting battery performance. The flow channel type coolant is affected by the size of the cooling liquid flow channel, the flow rate is required to be small, and the cooling and cooling efficiency is low. If the flow rate is increased, the pressure will increase. Due to the complex internal structure, the strength of the metal plate is higher. , otherwise the metal plate will be deformed and the battery performance will be affected.

To sum up, it is necessary to propose a simple structure that can not only enhance the turbulent operation during gas flow, but also avoid water flooding, without restrictions on the placement of bipolar plates, and provide channels for cooling liquid, which is difficult to process. Small multi-purpose metal double board.

SUMMARY OF THE INVENTION

Based on this, in order to solve the technical problems existing in the background art, the purpose of the present invention is to improve the drainage performance of the flow channel of the cathode plate while taking into account the increase of the power density of the fuel cell, and to provide a cooling liquid interlayer in the metal bipolar plate while simplifying the polar plate. The plate structure and the process difficulty of metal plate processing are reduced, and the strength of the bipolar plate itself is improved, so as to achieve a higher and more stable stack efficiency.

The purpose of the present invention is to design a type of flow channel that can improve the current density and facilitate the discharge of product water in the cathode plate. The flow channel is designed so that the two plates can be combined into a bipolar plate without affecting the current density improvement. At the same time, an interlayer is formed for the cooling liquid to pass through to reduce the temperature of the stack.

A fuel cell bipolar plate, comprising a first electrode plate and a second electrode plate, the first electrode plate and the second electrode plate have the same structure; the two electrode plates include gas flow channels, ribs, a first plane, a second plane and The third plane; the first plane is the reference plane of the metal plate, the first plane includes the gas transition area and the sealing ring plane, the second plane is the bottom plane of the gas flow channel, the second plane is higher than the first plane, the gas The entrance from the transition area into the flow channel is stepped; when the two polar plates are buckled, an interlayer is formed between the bottom planes of the two gas channels, and the interlayer provides a flow channel for the cooling liquid; each of the polar plates A gas flow channel also includes cylindrical depressions and hemispherical protrusions, and the center intervals of the cylindrical depressions and hemispherical protrusions are evenly distributed on the central axis of the gas flow channel; the third plane is the top surface of the flow channel rib, which is also a pole. On the upper end face 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 produced in the cathode flow channel is discharged from both sides of the hemispherical protrusion.

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

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

Preferably, the third plane of the bottom end plane of the cylindrical recess in the gas flow channel is parallel to the first plane at the inlet.

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

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

Preferably, for the first and second pole plates of the same structure, after the first pole plate rotates around the long side, it overlaps with the second pole plate, and the bottoms of the cylindrical recessed structures of the two pole plates are in contact with each other and overlap.

Preferably, two adjacent air inlets are arranged at intervals, and two adjacent air outlets are arranged at intervals.

Preferably, the pole plate is formed by a metal or alloy sheet with a thickness of less than 0.5 mm by a method of press working.

In the fuel cell pole plate provided by the present invention, the height difference between the first plane and the second plane of the pole plate makes the two pole plates synthesize a bipolar plate to form an interlayer in the middle. The concave structure provides structural support for the interlayer and avoids the plate deformation caused by the interlayer space. The hemispherical bulge in the flow channel increases the turbulence effect, which makes the gas react more fully in the flow channel and improves the power density. At the same time, the product water generated on the cathode plate side will flow from the gap on both sides of the hemispherical bulge Walk, which is conducive to the discharge of water, thereby avoiding flooding. The flow direction of the cooling liquid is cross-section, and the flow channel is in 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 is large, the heat taken away is high, and the cooling effect is excellent, and the cylindrical depression makes the cooling liquid in the interlayer The pressure is more uniform, which acts as a fluid disturbance to the coolant in the coolant passage, and the temperature distribution is more uniform.

Description of drawings

1 is a schematic three-dimensional structure diagram of a fuel cell electrode plate of the present invention;

Fig. 2 is a partial enlarged view of part A in Fig. 1 of the fuel cell electrode plate of the present invention;

3 is an exploded view of the structure of the fuel cell bipolar plate of the present invention;

Figure 4 is a perspective cross-sectional view of the fuel cell bipolar plate of the present invention;

Fig. 5 is a partial enlarged view of part B in Fig. 4;

6 is a front view of a fuel cell bipolar plate;

FIG. 7 is a cross-sectional view of the fuel cell bipolar plate C-C in FIG. 6;

Fig. 8 is a partial enlarged view E in Fig. 7;

FIG. 9 is a cross-sectional view of the fuel cell bipolar plate D-D in FIG. 6;

Fig. 10 is a partial enlarged view F in Fig. 9;

Fig. 11 is a partial enlarged view G in Fig. 9;

Fig. 12 is a partial enlarged view H in Fig. 9;

FIG. 13 is a partial enlarged view I in FIG. 6 .

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the related drawings. The preferred embodiments of the invention are shown in the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that a thorough and complete understanding of the present disclosure is provided.

The invention provides a bipolar plate, comprising two unipolar plates, one side of the unipolar plate is a flow field flow channel, the other side of the bipolar plate is synthesized by a stepped structure, and there is an interlayer in the middle, and the cylinder is recessed in the two After the bipolar plate is synthesized by the polar plate, it provides support for the middle area of the polar plate to ensure the strength of the bipolar plate and prevent the deformation of the polar plate; a hemispherical protrusion is arranged in the middle of the flow channel of the polar plate to increase the turbulence of the reaction gas. The reaction efficiency is improved, and the product water formed in the cathode plate can flow away from the two sides of the hemispherical bulge to prevent flooding, and there is no restriction on the placement of the fuel cell stack.

The invention provides a bipolar plate, one side of the monopolar plate is a flow field flow channel, and the other side of the monopolar plate is formed by a stepped structure to form an interlayer in the middle after the bipolar plate is synthesized, and the cylinder is recessed in the two polar plates to synthesize the bipolar plate Afterwards, it provides support for the middle area of the polar plate to ensure the strength of the bipolar plate and prevent the deformation of the polar plate; a hemispherical protrusion is arranged in the middle of the flow channel of the polar plate to increase the turbulent effect of the reaction gas, improve the reaction efficiency, and make the The product water formed in the cathode plate flows away from both sides of the hemispherical bulge to prevent flooding, and there is no restriction on the placement of the fuel cell stack.

As shown in Fig. 1-2, which is an embodiment of the present invention, the present invention provides a fuel cell bipolar plate, including a pole plate 1 and a pole plate 2, and the pole plate 1 and the pole plate 2 have the same structure; two The electrode plates all include gas flow channels 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 electrode plate, and the first surface 11 includes a gas transition area 24 and the sealing ring plane 23, the second plane 12 is the bottom plane of the gas flow channel, the second plane 12 is higher than the first plane 11, and the height difference between the second plane 12 and the first plane 11 is set to 1 of the overall thickness of the electrode plate 1. /10, the entrance of the gas from the transition region 24 into the flow channel is stepped; when the two polar plates are buckled, an interlayer is formed between the bottom planes of the two gas flow channels, and the interlayer 27 provides a flow channel for the cooling liquid; Each gas flow channel 25 of the polar plate also includes a cylindrical depression 15 and a hemispherical protrusion 14, and the center intervals of the cylindrical depression 15 and the hemispherical protrusion 14 are evenly distributed on the central axis of the gas flow channel 25; The three planes 13 are the top surface of the flow channel rib and also the upper end surface of the polar 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 channel 25, so that the The water generated in the cathode flow channel is discharged from both sides of the hemispherical protrusion 14 .

As shown in Figure 3, two identical polar plates 1 and 2, one of which is rotated 180° around the long side of the polar plate, the two polar plates overlap, and the inlets 18 of the two polar plates are staggered from each other, and the inlet of the cathode plate is fed with oxygen , the inlet of the anode plate is fed with hydrogen gas, and the gas outlet 19 is also staggered from each other; at the same time, the structure of the cooling liquid channel between the two polar plates cooperates to form a complete channel.

As shown in FIG. 4 , 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, and the height of the gap is twice the height difference between the second plane 12 and the first plane 11 , and the gap The height can be adjusted by the height of the step, and at the same time, the pressure of the coolant passing through the coolant flow channel can be reduced, and the deformation of the metal plate due to excessive pressure can be avoided.

As shown in Fig. 5, after the two pole plates are combined, the cylindrical recesses 15 overlap and contact each other, which increases the support force between the two pole plates, and also strengthens the overall strength of the fuel cell and even the stack. During the assembly process To prevent the metal bipolar plate from being deformed by extrusion, the force on the proton exchange membrane is uneven, and the increase of the pulling force will cause the proton exchange membrane to be damaged; the cylindrical depression 15 acts on it evenly, protects the proton exchange membrane, and increases fuel. The role of the overall structural strength of the battery.

As shown in FIG. 5 , the cylindrical depressions 15 and the hemispherical protrusions 14 are distributed in a staggered manner, and the staggered distribution can make the gas concentration distribution more uniform, increase the gas flow length, and increase the reaction efficiency.

As shown in FIG. 6 , the air inlet 18 and the air outlet 19 are arranged in a staggered arrangement, which can extend the distance of the gas and increase the reaction efficiency, and the gas direction is vertical (shown on the way). There are no restrictions on the placement of the runner, which can be placed vertically or horizontally.

As shown in FIG. 6 , the cooling liquid inlet 16 and the cooling liquid outlet 17 are located at both ends of the bipolar plate, and are distributed across the gas flow channel, and the gas flow direction and the cooling liquid flow direction are perpendicular to each other.

As shown in Fig. 7 and Fig. 8, the flow direction of the cooling liquid is cross-section 20, and the flow channel is in an area-type flow direction, which is in full contact with the reaction gas flow channels 21 and 22, and the contact area is large, the heat taken away by the large water flow rate is high, and the cooling The effect is excellent, and the cylindrical depression makes the pressure of the cooling liquid in the interlayer more uniform, which acts as a fluid disturbance to the cooling liquid in the cooling liquid channel, and at the same time, the temperature distribution is more uniform.

As shown in Fig. 8, 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 as not to contact the proton exchange membrane and increase the reaction area between the fuel gas and the membrane; the movement direction of the arrow It is the local motion 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 to increase the disturbance of the gas, thereby improving the reaction efficiency. , to enhance battery performance.

As shown in FIG. 8 , the hemispherical protrusions 14 and the cylindrical depressions 15 in the flow channel are in symmetrical positions, and the cylindrical depressions 15 overlap and contact each other.

As shown in Figure 9, the direction of the arrow is the flow direction of the cooling liquid D-D direction, the cooling liquid enters the interlayer of the bipolar plate from the cooling liquid inlet 16, flows in the direction of the arrow in the interlayer of the bipolar plate, and finally is discharged from the outlet 17; In particular, the directions of the cooling liquid entering the inlet and the outlet may be the same direction or different directions.

As shown in FIG. 10 , the direction of the arrow is the flow direction of the cooling liquid in the inlet portion.

As shown in FIG. 11 , the direction of the arrow is the flow direction of the cooling liquid in the bipolar plate interlayer.

As shown in FIG. 12 , the direction of the arrow is the flow direction of the cooling liquid in the outlet portion.

As shown in Figure 13, the water generated in the cathode plate flows and discharges in the direction indicated by the arrow, and the product horizontally passes through the cylindrical depression 15, and then passes through both sides of the hemispherical protrusion 14, which increases the turbulence and is beneficial to the product water. and if water is produced on the surface of the hemispherical protrusion 14, due to the hemispherical arc structure, the water will also slide down from the hemispherical arc surface to the bottom of the flow channel and flow out.

The fuel cell bipolar plate provided by the present invention has been proved by professional simulation software, which is beneficial to the performance improvement of the fuel cell. Compared with the performance of the traditional straight channel, the performance is improved by nearly 10%, and from the distribution of the product water, the overall water concentration The distribution is also lower than that of traditional direct current, and the temperature distribution is more uniform than that of traditional direct current.

The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be regarded as the scope described in this specification.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims (9)

1. A fuel cell bipolar plate, comprising: the structure of the first pole plate and the second pole plate is the same; the two polar plates comprise gas flow channels, ribs, a first plane, a second plane and a third plane; the first plane is a reference surface of the metal polar plate, the first plane comprises a gas transition area and a sealing ring plane, the second plane is a gas runner bottom plane, the second plane is higher than the first plane, and the entrance of gas entering the runner from the transition area is in a step shape; when the two polar plates are buckled, an interlayer is formed between the bottom planes of the two gas flow channels and provides a flow channel for cooling liquid; each gas flow channel of the polar plate also comprises a cylindrical recess and a hemispherical bulge, and the circle centers of the cylindrical recess and the hemispherical bulge are uniformly distributed on the central axis of the gas flow channel at intervals; the third plane is the top surface of the runner rib and is also the upper end surface of the polar plate, the third plane is higher than the upper vertex of the hemispherical bulge, and the spherical radius of the hemispherical bulge is smaller than the width of the gas runner, so that water generated in the cathode runner is discharged from two sides of the hemispherical bulge.

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

3. A fuel cell bipolar plate as in claim 2 wherein the hemispherical protrusions in said gas flow channels are slightly lower in height than the height of said gas flow channel ribs.

4. A fuel cell bipolar plate as in claim 2, wherein a bottom planar third plane of said cylindrical recess in said gas flow channel is parallel to said first plane at said inlet.

5. A fuel cell bipolar plate as in claim 2, wherein said hemispherical protrusions and cylindrical depressions in said gas flow channels are centered on the centerline of the width of the flow channels.

6. A fuel cell bipolar plate as in claim 2 wherein the cylindrical diameter of said cylindrical depressions in said gas flow channels is less than 3/4 and greater than 1/2 of the channel width.

7. The bipolar plate of claim 1, wherein the first and second plates have the same structure, and the first plate rotates around the long side and overlaps with the second plate, and the bottoms of the cylindrical recesses of the two plates contact with each other and overlap with each other.

8. A fuel cell bipolar plate as in claim 1, wherein two adjacent inlet ports are spaced apart and two adjacent outlet ports are spaced apart.

9. A fuel cell bipolar plate as in claim 1, wherein said plate is formed by pressing a metal or alloy sheet having a thickness of less than 0.5 mm.

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