Integrally formed hydrogen fuel cell bipolar plate and preparation method thereof

Abstract

The present invention relates to an integrally formed hydrogen fuel cell bipolar plate, which includes an integrally formed metal bipolar plate; the front and back surfaces of the bipolar plate form a concave-convex shape that is integral inside and outside, and the concave part forms a gas flow path; a plurality of through cold medium flow paths are formed in the middle of the bipolar plate along the length direction of the bipolar plate; the diffusion area for air intake and the recovery area for air outlet of the gas flow path are arranged at the diagonal; the diffusion area and the recovery area are connected by a reaction area to form a gas flow path. The present invention uses additive manufacturing technology for digital modeling design and integrally forming, reducing the contact resistance caused by traditional stacking processes, reducing the temperature difference between the inlet end and the outlet end, reducing thermal stress, making the fuel cell stack work more stably, safer, and with a longer lifespan. The motion state of the gas is changed into turbulent flow, thereby improving the mass transfer ability of the bipolar plate, which is beneficial to improving the effective output power of the fuel cell.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and more particularly to an integrally formed bipolar plate for a hydrogen fuel cell and a preparation method thereof. Background Art

[0002] The present invention relates to a bipolar plate for a hydrogen fuel cell, and more specifically, to an integrally formed bipolar plate including a composite series forming design of a positive (hydrogen) plate and a negative (oxygen) plate, and integrally series forming while forming a closed cooling flow field, a hydrogen injection port, an oxygen injection port, a water injection port, a hydrogen discharge port, an oxygen discharge port, and a water discharge port.

[0003] A hydrogen fuel cell is a power generation device that converts chemical energy into electrical energy through an electrochemical reaction of hydrogen at the anode and oxygen at the cathode. Hydrogen energy is a clean energy with high energy density and is generally regarded as one of the important future energies for mankind. Hydrogen fuel cells have great development potential in the new energy industry due to their advantages such as noiseless, pollution-free, and high-efficiency power generation processes.

[0004] The core component of a hydrogen fuel cell is a stack. A complete stack includes components such as a membrane electrode assembly (MEA), a bipolar plate (BP), a gas diffusion layer (GDL), an end plate, an insulating plate, and a sealing ring. These components together determine the power generation efficiency and service life of the stack. The bipolar plate is one of the core components of the stack, and its main functions are to transport hydrogen and oxygen through the gas flow fields of the hydrogen plate (positive) and the oxygen plate (negative) and isolate the gases, dissipate heat and conduct electricity, and discharge reaction products (water), etc. Therefore, the bipolar plate is required to have high electrical conductivity, thermal conductivity, good airtightness, machinability, and good corrosion resistance. Currently, graphite is the most widely used bipolar plate material in industrial applications, but bipolar plates processed from graphite have disadvantages such as a large thickness, limited stack assembly size, poor impact resistance, and small volume density and weight density of graphite stack power generation. Therefore, metal materials with better ductility, lighter weight, smaller volume, and more convenient for thin-wall processing have become a research hotspot for bipolar plate forming technology. Metal bipolar plates can be processed to a single plate thickness of less than 0.2 mm, significantly reducing the volume and weight of the stack.

[0005] At the present stage, the main method for processing metal bipolar plates is to separately design and process the hydrogen (positive) plate and the oxygen (negative) plate. Mold stamping is used to form single plates from metal thin plates, and then two single plates and the membrane electrode are encapsulated to form a single cell. Then, the anodes and cathodes of each group of single cells are connected in series through a conductive, heat-conductive, and sealing material to form a stack. When the positive and negative plates are connected in series, an independent cooling flow field medium is required to export the heat of the chemical reaction to ensure that the internal working temperature of the single cell is lower than the set temperature. Based on this stack assembly process, the existing development methods have problems such as high mold opening cost, high R & D and testing costs, complex manufacturing process, passive formation of the cooling flow field by the positive and negative single plates, high difficulty in designing the heat conduction and cooling module, and easy failure at the connection positions. For example Figure 1As shown, in the prior art, the hydrogen plate 101 and the oxygen plate 102 are usually single plates with the same structure. After stamping, flow field channels are formed on both sides. After the two single plates are symmetrically bonded together by welding, a cooling channel 100 is formed in the middle. Correspondingly, the back of the hydrogen plate 101 is a hydrogen gas flow channel 103, and the front of the oxygen plate 102 is an oxygen gas flow channel 104; further, as Figure 2 shown, using this bipolar plate to prepare a fuel cell includes a hydrogen plate 101, a membrane electrode 105, an oxygen plate 102, a hydrogen plate 101, a membrane electrode 105, and an oxygen plate 102 arranged in sequence. Among them, a welding is formed between the oxygen plate 102 and the hydrogen plate 101 in the center to form the above-mentioned cooling channel 100. The fuel cell stack is composed of multiple single plates, membrane electrodes 105, and is arranged at intervals. In order to ensure heat dissipation, during the stacking process, part of the hydrogen gas flow channel 103 and the oxygen gas flow channel 104 need to be sacrificed and welded into the cooling channel 100 and placed in the stack. If sufficient heat dissipation effect is to be ensured, enough cooling channels 100 need to be set, which will lead to the loss of the single plate flow channel, thereby reducing the energy density of the fuel cell stack. If the energy density of the fuel cell is to be increased, it will inevitably lead to poor heat dissipation. At the same time, the bipolar plate formed by welding two single plates has high welding requirements, and the conductivity of the contact surface after welding will be affected, increasing the contact resistance of the single cell in series, thereby affecting the power generation efficiency.

[0006] Another common solution in the prior art is, for example, the patent with the publication number CN217114452U discloses an externally cooled liquid-cooled fuel cell bipolar plate. The bipolar plate is composed of a single plate with a flow field. The single plate includes a reaction area and cooling fins on both sides of the reaction area. A stack including the above non-shared bipolar plate, the stack includes a repeating unit composed of an end plate, an insulating plate, a current collector plate, a plurality of bipolar plates and membrane electrodes stacked alternately, the current collector plate on the other side, the insulating plate, and the end plate; the cooling fins of the bipolar plate partially extend beyond the stack body, and the cooling fins are surrounded to form an external cooling cavity of the stack. The cooling medium flows through the external cooling cavity to take out the heat generated inside the stack, and finally dissipates it to the surrounding environment through the external radiator of the system or uses it as a high-quality heat source. The cooling in this solution is through the outward-extending fins for heat dissipation. Although the flow channels will not be lost for forming the heat dissipation flow channels during the stacking of the single-stage plates, the additional fin structure increases the overall volume of the stack, and the energy density loss of the stack is greater. This solution provides an excellent heat dissipation effect but gives up the control of the volume.

[0007] In the prior art, cooling water exchanges heat with the fuel cell to take away heat, thereby keeping the fuel cell within a reasonable temperature range. The cooling water absorbs heat inside the fuel cell and then the temperature rises, resulting in different amounts of heat taken away at the inlet end and the outlet section of the cooling water, causing a temperature difference at the inlet end and the outlet end of the fuel cell and affecting the performance of the stack.

[0008] The design of the fuel cell bipolar plate and the flow field will directly affect the fluid distribution of the fuel gas and the oxidant in the fuel cell, as well as the water and heat management, thus directly affecting the working efficiency and service life of the fuel cell.

[0009] Compared with the oxidation reaction occurring at the anode with hydrogen, the reaction kinetics at the cathode end is extremely slow. The diffusion coefficient of oxygen is about one order of magnitude lower than that of hydrogen, and the electrochemical reaction product water is mainly discharged from the cathode side. If the flow field (flow channel) structure is not reasonably designed, problems such as reduced gas diffusion, i.e., reduced mass transfer ability of reactants, and difficulty in discharging reaction products, i.e., "flooding", will occur.

[0010] In the prior art, common flow channel designs are mostly in two-dimensional planes, that is, the cross-sectional area of the flow channel does not change along the fluid flow direction, or the hydraulic diameter does not change. In such two-dimensional flow field plates, gas mainly enters the diffusion layer and the electrode surface from the flow channel by diffusion due to concentration differences, and the mass transfer performance is poor. Especially at high current densities, the concentration polarization phenomenon is particularly obvious, and reactants often cannot be transported to the electrochemical reaction surface of the porous electrode in time, resulting in a sharp decline in battery performance; the water droplets discharged into the flow channel in the gas diffusion layer often move in a constant state on the surface of the gas diffusion layer until they are purged out of the flow channel, and there will be stationary droplets in the gas diffusion layer, especially in the area opposite to the ridge, resulting in a reduction in the effective area for the reaction gas to diffuse into the porous electrode, thus further deteriorating the mass transfer performance. Summary of the Invention

[0011] (1) Technical problems to be solved

[0012] To solve the above problems of the prior art, the present invention provides an integrally formed hydrogen fuel cell bipolar plate, which makes it easier to design the cooling flow field through an integrated structure, and can effectively reduce the temperature difference between the inlet end and the outlet end, and make the gas in the gas flow field show turbulent flow, improving the mass transfer ability of the bipolar plate.

[0013] (2) Technical solutions

[0014] To achieve the above object, the main technical solutions adopted by the present invention include:

[0015] An integrally formed hydrogen fuel cell bipolar plate, comprising an integrally formed metal bipolar plate; the front and back surfaces of the bipolar plate form an integral concave-convex shape, and the concave parts form gas flow paths; several through-flow cold medium channels are formed in the middle of the bipolar plate along the length direction of the bipolar plate; a connecting body for disturbing the cold medium to reduce the flow rate of the cold medium is arranged in the cold medium channels; the diffusion area for intake air and the recovery area for exhaust air of the gas flow path are arranged at the diagonal; the diffusion area and the recovery area are connected by a reaction area to form a gas flow path; the cross-sectional area of the concave part of the gas flow path is set to be relatively large for the reaction area compared to the diffusion area and the recovery area in the cross-sectional view at the corresponding position when viewed from the direction perpendicular to the gas flow direction; the gas flow path is configured to make the introduced gas move to form a turbulent flow so as to improve the mass transfer ability of the bipolar plate.

[0016] Further, the diffusion area and the recovery area in the gas flow path have straight flow paths, and the reaction area is a zigzag flow path; the cold medium channels are straight flow paths.

[0017] Further, the reaction area includes a plurality of wave-shaped flow paths arranged in parallel.

[0018] Further, the wave-shaped flow path includes a straight gas-passable path along the gas flow direction.

[0019] Further, sealing grooves are arranged on the circumferential direction of the front and back surfaces of the bipolar plate.

[0020] Further, three openings are respectively arranged at both ends of the bipolar plate, including an oxygen injection port and a hydrogen injection port arranged oppositely, a cold medium injection port and a cold medium discharge port arranged oppositely in the middle, and a hydrogen discharge port and an oxygen discharge port arranged oppositely; the gas flow fields on the front and back surfaces of the bipolar plate are arranged in central symmetry.

[0021] Further, the cross-sectional area of the cold medium channel is set to be relatively large for the middle side of the cold medium compared to the upstream side and the downstream side of the cold medium in the cross-sectional view at the corresponding position when viewed from the direction perpendicular to the cold medium flow direction.

[0022] Further, the connecting body includes a flow path formed by a plurality of first connecting bodies located on the upstream side and the downstream side of the cold medium in the cold medium channel, which are configured to be dot-shaped distributed at the front end and the tail end of the middle part of the hollowed bipolar plate and are integrally connected to the bipolar plate body at both ends to form a mutually connected flow path.

[0023] Further, the connecting body includes a plurality of second connecting bodies located on the middle side of the cold medium in the cold medium channel, which are configured to be arranged in parallel along the cold medium flow direction in the middle section of the hollowed bipolar plate and are integrally connected to the bipolar plate body on both side surfaces perpendicular to the cold medium flow direction to form a straight flow path.

[0024] Further, in the cross-sectional view of the bipolar plate, the cross-sectional width of the cold medium flow path is equivalent to that of the gas flow path.

[0025] A preparation method of an integrally formed hydrogen fuel cell bipolar plate, characterized in that: according to the drawing of the bipolar plate, 3D printing of a metal material is carried out by using the SLM selective laser melting process to obtain the fuel cell bipolar plate described above.

[0026] (III) Beneficial effects

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. For the integrally formed hydrogen fuel cell bipolar plate of the present invention, digital modeling design and integral molding are applied by using additive manufacturing technology, and no mold is required for processing, which can greatly reduce the R & D cycle and R & D cost. After the integral molding, the series-connected forming tissues of the anode and cathode of the integrally formed bipolar plate are uniform and dense, reducing the contact resistance caused by the traditional stacking process. The hydrogen field, oxygen field, and cooling water channels are independently designed without interference, and the sealing effect is excellent. Finally, based on such a bipolar plate processing method, designers are no longer restricted by the stamping processing method and can design and simulate the flow field more freely to obtain a flow field with better power generation efficiency and cooling efficiency, optimizing and simplifying the current stacking process, improving the yield of the stack assembly, and reducing costs and increasing efficiency.

[0029] 2. Through the setting of the first connecting body and the second connecting body, the present invention changes the flow rate of the cold medium in the cold medium flow path. The cold medium is cooling water, increasing the residence time of the cooling water in the cold medium flow channel. Specifically, the first connecting body distributed in a point shape disperses the cooling water on the upstream side (inlet), reducing the flow rate. At the same time, through the special design of the first connecting body, the cooling water can be quickly divided, enabling it to quickly flow into the straight flow path formed by the second connecting body, and finally discharged after being blocked, dispersed, decelerated, and merged by the first connecting body on the downstream side (outlet). Through the flow disturbance effect of the front and rear first connecting bodies, heat transfer is increased, and more heat can be carried away. At the same time, while increasing the heat transfer time, based on the heat conductivity of the integrally formed bipolar plate, the temperature difference between the inlet end and the outlet end can be effectively reduced, reducing the thermal stress, making the stack work more stably, safely, and with a longer lifespan.

[0030] 3. The gas flow channels in the bipolar plate reaction zone of the present invention are arranged in a wavy shape and include a straight gas-passable path along the gas flow direction. The wavy region can cause fluctuations in the flow velocity and pressure of the anode gas in the anode gas flow channel, and then the straight passable path in the flow direction mixes the fluctuating gases, so that the motion state of the anode gas is turbulent; the motion state of the cathode gas is also turbulent in the same way, thereby improving the mass transfer ability of the bipolar plate and being beneficial to improving the effective output power of the fuel cell. At the same time, the turbulent gas has better purging ability and can more comprehensively impact the water droplets in the flow channel during transmission, making them move irregularly and being more easily purged out of the flow channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0032] Figure 1 is the bipolar plate structure of the prior art;

[0033] Figure 2 is the exploded view of the prior art stack structure;

[0034] Figure 3 is the schematic diagram of the bipolar plate structure of the present invention;

[0035] Figure 4 is the schematic cross-sectional view of the bipolar plate of the present invention;

[0036] Figure 5 is the enlarged view of part A of the present invention;

[0037] Figure 6 is the partial enlarged schematic view of the internal cold medium flow channel of the present invention;

[0038] Figure 7 is the enlarged view of the reaction zone of the present invention;

[0039] Figure 8 is the three-dimensional view of the bipolar plate of the present invention;

[0040] Figure 9 is the schematic assembly view of the bipolar plate of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0042] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0043] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" 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 directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] Example 1, please refer to Figure 3-8 as shown:

[0045] An integrally formed hydrogen fuel cell bipolar plate, comprising an integrally formed metal bipolar plate 200; the front and back surfaces of the bipolar plate 200 form an integrally formed concave-convex shape, and the concave portions form gas flow paths 201; a plurality of through cold medium flow paths 202 are formed in the middle of the bipolar plate 200 along the length direction of the bipolar plate; the diffusion region 203 for intake air and the recovery region 205 for exhaust air of the gas flow path 201 are arranged at the diagonal; the diffusion region 203 and the recovery region 205 are connected by a reaction region 204 to form the gas flow path 201; the cross-sectional area of the concave portion of the gas flow path 201 is set to be relatively large for the reaction region 204 in the cross-sectional view of the corresponding position when viewed from the direction perpendicular to the gas flow direction with respect to the diffusion region 203 and the recovery region 205. That is, as Figure 3 shown, the diffusion region 203 and the recovery region 205 are arranged at the diagonal, and a relatively wide reaction region 204 is formed by the gradual extension of the flow channel and the expansion in the width direction; the diffusion region 203 includes an inlet section along the length direction and an extended section where the end of the inlet section turns and extends in the width direction. The reaction region 204 is immediately adjacent to the extended end. Since the extended section expands in the width direction, the flow channel of the inlet section will have a larger flow channel opening after the expansion of the extended end. In order to ensure the uniformity of each flow channel, the reaction region 204 will set a plurality of reaction region flow channels corresponding to the extended section with a larger opening, so as to ensure the uniformity of the flow channel gas. Similarly, the recovery region 205 is symmetrically arranged with the diffusion region 203 about the center.

[0046] The diffusion region 203 and the recovery region 205 in the gas flow path 201 have straight flow paths, specifically referring to the straight flow channels of the inlet section and the extended section, and the reaction region 204 is a zigzag flow path; further, the reaction region 204 includes a plurality of juxtaposed wavy flow paths; the wavy flow path includes a straight gas-passable path along the gas flow direction, such as Figure 7As shown, the distance between the upper and lower wavy shapes should not be too large, otherwise the described straight passable path cannot be formed. When the undulation of the wavy shape is too large, a curved flow path will be formed, causing the gas to move directly along the flow path and making it difficult to form a turbulent flow, which is not conducive to improving the mass transfer ability. The reason is that when there is a straight gas passable path, when the gas flows through the flow channel, analyzing the gas in the straight flow channel, this gas should normally flow at a constant speed. However, in the flow channel of the present invention, arc-shaped accommodating areas 206 arranged at intervals are directly connected to both the upper and lower sides of the straight flow channel. When the gas flows along the inner wall of the arc-shaped accommodating area 206, its speed will change, and this area is connected to the straight path. Therefore, after the speed of the gas flowing through the arc-shaped accommodating area 206 changes, it impacts the gas in the straight path, causing fluctuations in the flow speed and pressure of the gas and forming a turbulent flow, thereby improving the mass transfer ability of the bipolar plate and being beneficial to increasing the effective output power of the fuel cell. At the same time, the turbulent gas has better purging ability and can more comprehensively impact the water droplets in the flow channel during transmission, making them move irregularly and being more easily purged out of the flow channel.

[0047] In one embodiment of the present invention, the cold medium flow path is a straight flow path.

[0048] As Figure 8 As shown, three openings are respectively provided at both ends of the bipolar plate 200, including an oxygen injection port 210 and a hydrogen injection port 211 arranged oppositely, a cold medium injection port 212 and a cold medium discharge port 213 arranged oppositely in the middle, and a hydrogen discharge port 214 and an oxygen discharge port 215 arranged oppositely; the gas flow fields on the front and back surfaces of the bipolar plate are centrosymmetrically arranged. Sealing grooves 207 are provided along the circumferential direction on the front and back surfaces of the bipolar plate.

[0049] As Figure 6As shown, the cross-sectional area of the cold medium flow path is set such that, when viewed from a direction perpendicular to the direction of cold medium flow, the mid-stream side of the cold medium is relatively larger than the upstream side and the downstream side of the cold medium in the corresponding position cross-sectional view. The mid-stream side of the cold medium is the middle part of the cold medium flow direction, the upstream side of the cold medium is at the cold medium injection port 212, and the downstream side of the cold medium is at the cold medium discharge port 213. The upstream side and the downstream side of the cold medium in the cold medium flow path are configured to form a mutually communicating flow path after a number of first connectors 208, which are integrally connected to the bipolar plate body at both ends and are dot-shapedly distributed at the front end and the tail end in the middle of the hollow bipolar plate. The first connector 208 is usually cylindrical, and can also be set as strip-shaped or curved at the corner or where the width direction becomes larger to adapt to the shape change curve. The first connector 208 is a connector provided in the middle of the integrally formed bipolar plate during 3D printing for connecting the two sides for forming the gas flow path. The space between adjacent connectors is hollow for the flow of the cold medium. The function of the first connector 208 is, on the one hand, to disturb the cold medium (cooling water), reduce the water flow velocity, and increase the residence time of the cooling water in the cold medium flow path. Specifically, the dot-shapedly distributed first connectors 208 disperse the cooling water on the upstream side (cold medium injection port 212), reducing the flow velocity. On the other hand, it plays a role in supporting the two side plates. Further, the integrally formed structure eliminates the welding operation of the traditional single bipolar plate. After the integrally formed bipolar plate is completely formed, the anode and cathode are connected in series, and the formed tissue is uniform and dense, reducing the contact resistance caused by the traditional stacking process. The hydrogen field, oxygen field, and cooling water channels are independently designed without interference, and the sealing effect is excellent, so as to obtain a flow field with better power generation efficiency and cooling efficiency.

[0050] The middle part of the cold medium on the upstream side in the cold medium flow path is configured to be provided with a plurality of second connectors 209 that are parallel to each other and perpendicular to the cold medium flow direction along the middle section of the hollow bipolar plate and are integrally connected to the bipolar plate body on both side surfaces, so as to form a straight flow path. The straight flow path formed by the second connectors 209 is communicated with the flow path formed by the first connectors 208. The arrangement of the first connectors 208 and the second connectors 209 causes the flow rate of the cold medium in the cold medium flow path to change. The cold medium is cooling water, which increases the residence time of the cooling water in the cold medium flow channel. Specifically, the first connectors 208 distributed in a dot shape disperse the cooling water on the upstream side (cold medium injection port 212), reducing the flow rate. At the same time, through the special design of the first connectors 208, the cooling water can be quickly split, enabling it to quickly split into the straight flow path formed by the second connectors 209, and finally discharged at the downstream side (cold medium discharge port 213) after being blocked, dispersed, decelerated, and merged by the first connectors 208. Through the flow disturbance effect of the first connectors 208 before and after, heat transfer is increased, and more heat can be carried away. At the same time, while increasing the heat transfer time, based on the heat conductivity of the integrally formed bipolar plate, the temperature difference between the inlet end and the outlet end can be effectively reduced, the thermal stress is reduced, and the stack works more stably, safely, and has a longer service life.

[0051] In the cross-sectional view of the bipolar plate, the cross-sectional width of the cold medium flow path is equivalent to the cross-sectional width of the gas flow path, which can provide a better cooling effect.

[0052] A fuel cell stack includes the integrally formed hydrogen fuel cell bipolar plate, which is arranged in the following Figure 9 way, that is, the bipolar plate 200 and the membrane electrode 105 are arranged at intervals to form a stack. The advantage of this structure is that a complete fuel cell unit can be directly formed on both sides of the bipolar plate 200, and it can be directly stacked with the membrane electrode 105, without the need to sacrifice part of the gas flow channels as in the Figure 2 existing technical solutions in the prior art to construct a cold medium flow channel for heat dissipation. And it has a better heat dissipation effect while ensuring space utilization, and can also effectively increase the energy density of the battery. At the same time, by applying additive manufacturing technology for digital modeling design and integral forming, the bipolar plate can have a thinner thickness, without the need for mold processing, which can greatly reduce the R & D cycle and R & D costs. After the integral forming is completed, the cathode and anode of the integrally formed bipolar plate are connected in series, and the formed structure is uniform and dense, reducing the contact resistance caused by the traditional stacking process. The hydrogen field, oxygen field, and cooling water channels are independently designed without interference, and the sealing effect is excellent. Finally, based on such a bipolar plate processing method, designers are no longer restricted by the stamping processing method, and can design and simulate the flow field more freely to obtain a flow field with better power generation efficiency and cooling efficiency, optimizing and simplifying the current stacking process, improving the yield rate of the stack assembly, reducing costs, and increasing efficiency.

[0053] A preparation method of an integrally formed hydrogen fuel cell bipolar plate, in which a 3D printing metal material is 3D printed by using an SLM selective laser melting process according to the drawing of the bipolar plate to obtain the fuel cell bipolar plate described above.

[0054] The above are only embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. An integrally formed bipolar plate for a hydrogen fuel cell, characterized in that: It includes an integrally formed metal bipolar plate; the front and back surfaces of the bipolar plate form a concave-convex shape that is integral inside and outside, and the concave part forms a gas flow path; several through-flow cold medium channels are formed in the middle of the bipolar plate along the length direction of the bipolar plate; a connecting body for disturbing the cold medium to reduce the flow rate of the cold medium is arranged in the cold medium channel; the diffusion area for intake air and the recovery area for outlet air of the gas flow path are arranged at the diagonal; the diffusion area and the recovery area are connected through a reaction area to form a gas flow path; the gas flow path is configured to make the introduced gas move to form a turbulent flow to improve the mass transfer capacity of the bipolar plate; the reaction area includes several juxtaposed wavy channels; the wavy channel includes a straight gas-passable path along the gas flow direction.

2. The integrated hydrogen fuel cell bipolar plate according to claim 1, wherein: The cross-sectional area of the concave part of the gas flow path is set to be relatively large for the reaction area compared to the diffusion area and the recovery area in the cross-sectional view at the corresponding position when viewed from the direction perpendicular to the gas flow direction; the diffusion area and the recovery area in the gas flow path have straight channels, and the reaction area is a zigzag channel; the cold medium channel is a straight channel.

3. The one-piece formed hydrogen fuel cell bipolar plate according to claim 1, wherein: Sealing grooves are provided on the circumferential direction of the front and back surfaces of the bipolar plate.

4. The integrated one-piece hydrogen fuel cell bipolar plate according to claim 1, characterized in that: Three openings are respectively arranged at both ends of the bipolar plate, including an oxygen injection port and a hydrogen injection port arranged oppositely, a cold medium injection port and a cold medium discharge port arranged oppositely in the middle, and a hydrogen discharge port and an oxygen discharge port arranged oppositely; the gas flow fields on the front and back surfaces of the bipolar plate are symmetrically arranged about the center.

5. The integrated hydrogen fuel cell bipolar plate according to claim 1, wherein: The cross-sectional area of the cold medium channel is set to be relatively large for the middle side of the cold medium compared to the upstream side and the downstream side of the cold medium in the cross-sectional view at the corresponding position when viewed from the direction perpendicular to the cold medium flow direction.

6. The one-piece formed hydrogen fuel cell bipolar plate according to claim 5, wherein: The connecting body includes a flow path that is formed by several first connecting bodies located on the upstream side and the downstream side of the cold medium in the cold medium channel, which are configured to be distributed in a dot-like manner at the front end and the tail end of the middle part of the hollowed bipolar plate and are integrally connected to the bipolar plate body at both ends and are mutually connected.

7. The one-piece formed hydrogen fuel cell bipolar plate according to claim 5, characterized in that: The connecting body includes a second connecting body located on the middle side of the cold medium in the cold medium channel, which is configured to be arranged juxtaposed along the cold medium flow direction in the middle section of the hollowed bipolar plate and is parallel and perpendicular to the cold medium flow direction, and both side surfaces are integrally connected to the bipolar plate body to form a straight channel.

8. A preparation method of an integrally formed bipolar plate for a hydrogen fuel cell, characterized in that: The 3D printing metal material is 3D printed by using the SLM selective laser melting process according to the drawing of the bipolar plate to obtain the fuel cell bipolar plate according to any one of claims 1-7.

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