Bipolar plate for normal-pressure air-cooled fuel cell

Abstract

The invention relates to a bipolar plate for a normal-pressure air-cooled fuel cell, which comprises a hydrogen plate (1) and an air plate (2), the front surface of the air plate (2) is provided with an air diversion trench (21), the front surface of the hydrogen plate (1) is provided with a hydrogen flow channel (11), the back surfaces of the hydrogen plate (1) and the air plate (2) are bonded together and hermetically connected to form the bipolar plate, and the two ends of the bipolar plate are provided with hydrogen inlets and outlets (12); hydrogen tunnel flow guide grooves (14) are formed in the two ends of a middle interlayer of the bipolar plate, air tunnel flow guide grooves (22) are formed in the two sides of the middle interlayer, and the hydrogen tunnel flow guide grooves (14) are communicated with a hydrogen flow channel (11); and the air tunnel diversion trench (22) is communicated with the air diversion trench (21). Compared with the prior art, the invention has the advantages of very good sealing performance between the membrane electrode and the bipolar plate, easiness in batch production and the like.

Description

Technical Field

[0001] The present invention relates to a fuel cell, and more particularly to a bipolar plate for an atmospheric pressure air-cooled fuel cell. Background Art

[0002] An electrochemical fuel cell is a device that can convert hydrogen and an oxidant into electrical energy and reaction products. A traditional fuel cell stack mainly consists of an end plate, an insulating plate, a current collector plate, a bipolar plate, a seal, a membrane electrode assembly, and fastening bolts; the internal core component of this device is the membrane electrode (Membrane Electrode Assembly, abbreviated as MEA), and the membrane electrode (MEA) consists of a proton exchange membrane and two porous conductive materials, such as carbon paper, sandwiched on both sides of the membrane. On both interfaces of the membrane and the carbon paper, there are uniformly and finely dispersed catalysts that initiate electrochemical reactions, such as metal platinum catalysts. Conductive objects can be used on both sides of the membrane electrode to lead out the electrons generated during the electrochemical reaction process through an external circuit to form a current loop.

[0003] At the anodic end of the membrane electrode, the fuel can penetrate through the porous diffusion material (carbon paper) and undergo an electrochemical reaction on the catalyst surface, losing electrons to form positive ions. The positive ions can migrate through the proton exchange membrane to reach the cathodic end, the other end of the membrane electrode. At the cathodic end of the membrane electrode, a gas containing an oxidant (such as oxygen), such as air, penetrates through the porous diffusion material (carbon paper) and undergoes an electrochemical reaction on the catalyst surface to obtain electrons and form negative ions. The anions formed at the cathodic end react with the positive ions migrated from the anodic end to form reaction products.

[0004] In a proton exchange membrane fuel cell using hydrogen as fuel and air containing oxygen as an oxidant (or pure oxygen as an oxidant), the catalytic electrochemical reaction of the fuel hydrogen in the anode region generates hydrogen positive ions (or protons). The proton exchange membrane helps the hydrogen positive ions migrate from the anode region to the cathode region. In addition, the proton exchange membrane separates the gas flow containing hydrogen fuel from the gas flow containing oxygen, preventing them from mixing with each other and causing an explosive reaction.

[0005] In a typical proton exchange membrane fuel cell, the membrane electrode assembly (MEA) is generally placed between two conductive plates. On the surface of each current collector plate in contact with the MEA, at least one flow channel is formed by die-casting, stamping or mechanical milling. These current collector plates can be made of metal or graphite. The fluid channels and flow channels on these current collector plates introduce fuel and oxidant into the anode and cathode regions on both sides of the MEA respectively. In the structure of a single cell of a proton exchange membrane fuel cell, there is only one MEA, and on both sides of the MEA are the current collector plates for anode fuel and cathode oxidant respectively. These current collector plates serve both as current collectors and as mechanical supports on both sides of the MEA. The flow channels on the current collector plates also serve as channels for fuel and oxidant to enter the anode and cathode surfaces, and as channels for removing the water generated during the operation of the fuel cell.

[0006] A typical battery pack usually includes: (1) Inlet and flow channels for fuel and oxidant gases to evenly distribute fuel (such as hydrogen, methanol or hydrogen-rich gas obtained by reforming methanol, natural gas, gasoline) and oxidant (mainly oxygen or air) into the flow channels on each anode and cathode surface; (2) Inlet and outlet of cooling fluid (such as water) and flow channels to evenly distribute the cooling fluid into the cooling channels in each battery pack to absorb and remove the heat generated by the electrochemical exothermic reaction of hydrogen and oxygen in the fuel cell; (3) Outlet of fuel and oxidant gases and corresponding flow channels. When the fuel gas and oxidant gas are discharged, they can carry out the liquid and gaseous water generated in the fuel cell. Usually, all the inlets and outlets of fuel, oxidant and cooling fluid are opened on one end plate or two end plates of the fuel cell stack.

[0007] The bipolar plate is crucial for the performance of the stack. It is necessary to consider not only the mass transfer characteristics and conductivity of the electrochemical reaction, but also its heat transfer efficiency in the cooling system to ensure that the entire stack can operate in the best state. The flow field design of the bipolar plate of the fuel cell stack is the main factor affecting the internal gas transport, water transport and temperature distribution. By optimizing the flow field design, the reactants can be effectively distributed to achieve high gas utilization rate and easy water removal, which is crucial for improving the performance of the fuel cell.

[0008] According to the cooling form of the stack, it can be divided into air-cooled stack and liquid-cooled stack. The air-cooled stack mainly dissipates heat from the stack, especially the bipolar plate, through external air. There are two types of cathodes in the air-cooled stack: closed and open. In the closed cathode stack, the cooling air and the air participating in the reaction are provided separately, each with its own channel, and the design and structure are relatively complex; while in the open cathode stack, the cooling air and the air participating in the reaction are supplied through the same channel, and the air dissipates heat and cools the stack, especially the bipolar plate, during the reaction process.

[0009] In the existing open cathode air-cooled fuel cell stack, the bipolar plate structure generally consists of an anode plate (i.e., hydrogen plate) and a cathode plate (i.e., air plate). The back sides of the hydrogen plate and the air plate are bonded together to form a whole. The front side of the hydrogen plate is provided with hydrogen flow channels, and the front side of the air plate is provided with air flow channels. Or it is a single-piece bipolar plate, with hydrogen flow channels on its front side and air flow channels on its back side. The structure is as shown in Figure 1 shown. The air flow channels generally adopt fully-through DC channels, which are convenient for a large amount of air to pass through quickly, realizing heat dissipation and cooling of the bipolar plate while participating in the reaction. However, the hydrogen side of the bipolar plate of this structure still needs to be sealed. Generally, an injection-molded sealing frame is used for sealing or a hard frame is used for sealing by dispensing glue. However, during the sealing process, due to the fully-through DC channel design on the air side of the flow guide plate, it is impossible to set a sealing groove, and it is impossible to form a completely corresponding and matching balanced pressure with the sealing structure on the hydrogen side, resulting in difficulty in forming an effective seal on the hydrogen side, and thus hydrogen is likely to leak. Summary of the Invention

[0010] The purpose of the present invention is to overcome the above-mentioned defects existing in the prior art and provide a bipolar plate for an atmospheric pressure air-cooled fuel cell with very good sealing performance between the membrane electrode and the bipolar plate and easy for mass production.

[0011] The purpose of the present invention can be achieved by the following technical solutions: A bipolar plate for an atmospheric pressure air-cooled fuel cell includes a hydrogen plate (1) and an air plate (2). The front side of the air plate (2) is provided with air flow channels (21), and the front side of the hydrogen plate (1) is provided with hydrogen flow channels (11). The back sides of the hydrogen plate (1) and the air plate (2) are hermetically connected to form a bipolar plate, and hydrogen inlets and outlets (12) are provided at both ends of the bipolar plate. Hydrogen tunnel flow channels (14) are provided at both ends of the middle sandwich of the bipolar plate, and air tunnel flow channels (22) are provided on both sides. The hydrogen tunnel flow channels (14) communicate with the hydrogen flow channels (11); the air tunnel flow channels (22) communicate with the air flow channels (21).

[0012] Further, the hydrogen tunnel flow channels (14) are arranged on the back side of the hydrogen plate (1), or on the back side of the air plate (2), or multiple hydrogen tunnel flow channels (14) are dispersedly arranged on the back sides of the hydrogen plate (1) and the air plate (2).

[0013] Further, hydrogen drainage holes (13) penetrating through the hydrogen plate (1) are provided at both ends of each hydrogen flow channel (11) on the front side of the hydrogen plate (1). One end of the hydrogen drainage hole (13) communicates with the hydrogen flow channel (11) on the front side, and the other end communicates with the hydrogen tunnel flow channel (14) on the back side.

[0014] Further, the air tunnel flow guiding grooves (22) are arranged on the back surface of the air plate (2), or on the back surface of the hydrogen plate (1), or multiple air tunnel flow guiding grooves (22) are dispersedly arranged on the back surfaces of the hydrogen plate (1) and the air plate (2).

[0015] Further, the air tunnel flow guiding grooves (22) are arranged on the back surface of the air plate (2), and multiple air tunnel flow guiding grooves (22) penetrate through the back surface of the air plate (2) in the length direction and are correspondingly penetrated with the air flow guiding grooves (21) on the front surface of the air plate in the depth direction.

[0016] Further, the air tunnel flow guiding grooves (22) are composed of multiple small flow guiding grooves, and each flow guiding groove corresponds to the air flow guiding groove (21) on the front surface one by one.

[0017] Further, the air tunnel flow guiding grooves (22) are multiple wide flow guiding grooves, and each wide flow guiding groove corresponds to 3 - 4 air flow guiding grooves (21).

[0018] Further, the air tunnel flow guiding grooves (22) are strip-shaped grooves located on the opposite two sides of the back surface of the air plate (2), the strip-shaped grooves correspond to all the air flow guiding grooves (21), and 2 - 5 reinforcing ribs are arranged in the strip-shaped grooves.

[0019] Further, air flow guiding holes (23) penetrating through the air plate (2) are arranged at both ends of each air flow guiding groove (21) on the front surface of the air plate (2). One end of the air flow guiding hole (23) is communicated with the air flow guiding groove (21) on the front surface, and the other end is communicated with the air tunnel flow guiding groove (22) on the back surface.

[0020] Further, sealing grooves b (3) are arranged on the back surfaces of both the hydrogen plate (1) and the air plate (2), and the sealing grooves on the two plates correspond to each other. The sealing frame is arranged in the sealing groove b (3) by dispensing glue, and the back surfaces of the hydrogen plate (1) and the air plate (2) are adhesively bonded or welded together for sealed connection to form a bipolar plate.

[0021] Further, hydrogen is introduced into the hydrogen tunnel flow guiding groove (14) between the bipolar plate interlayers from the hydrogen inlet, then introduced into one end of the hydrogen flow channel (11) on the front surface of the hydrogen plate (1) through the hydrogen flow guiding hole (13), flows along the hydrogen flow channel (11) to the other end of the hydrogen flow guiding hole (13), returns to the hydrogen tunnel flow guiding groove (14) between the bipolar plate interlayers, and then is discharged from the hydrogen outlet;

[0022] Air is introduced from the air tunnel flow guiding grooves (22) on both sides of the bipolar plate interlayer, passes through the air plate (2) body and enters the air flow guiding groove (21) on the front surface to participate in the reaction and cool the bipolar plate.

[0023] The bipolar plate includes a graphite bipolar plate, a soft graphite molded bipolar plate, and a metal plate.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The conventional through-type air flow guiding groove is changed to a closed type, that is, a sealing groove is provided on the periphery of the front surface of the air plate. The air flow guiding groove does not penetrate the entire air plate, but air tunnel drainage holes communicating the front and back surfaces of the air plate are provided at both ends of the air flow guiding groove. Air is introduced from the back surface of the air plate into the bipolar plate, passes through the air plate, is introduced from the air flow guiding groove on the front surface, and then enters and returns to the back surface of the air plate through the air tunnel drainage holes. On the one hand, it does not affect the input of air, and on the other hand, it also protects the membrane electrode and avoids damage to the membrane electrode caused by incomplete corresponding matching of forces.

[0026] Hydrogen is introduced in the same way, from the back surface of the hydrogen plate, flows through the hydrogen flow channels on the front surface, participates in the reaction, and then returns to the back surface of the hydrogen plate and exits from the hydrogen inlets and outlets at both ends.

[0027] Thus, completely corresponding and matching sealing grooves can be provided on the front surfaces of the hydrogen plate and the air plate, and matching sealing frames can be placed. During the pressing process, the sealing frames on both sides of the membrane electrode are subjected to completely corresponding, matching, and equal pressures. On the one hand, the sealing effect is improved, and on the other hand, it also protects the membrane electrode and avoids damage to the membrane electrode caused by incomplete corresponding matching of forces.

[0028] Since the hydrogen plate and the air plate of the present invention make full use of the space on both sides of the plate, and the processing is convenient, the sealing performance is improved, thereby improving the performance of the air-cooled fuel cell, and at the same time, mass production can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of the existing air plate;

[0030] Figure 2 is a schematic front structural diagram of the hydrogen plate 1 in Embodiment 1;

[0031] Figure 3 is a schematic back structural diagram of the hydrogen plate 1 in Embodiment 1;

[0032] Figure 4 is a schematic front structural diagram of the air plate 2 in Embodiment 1;

[0033] Figure 5 is a schematic back structural diagram of the air plate 2 in Embodiment 1;

[0034] Figure 6 is a schematic front structural diagram of the hydrogen plate 1 in Embodiment 2;

[0035] Figure 7 is a schematic back structural diagram of the air plate 2 in Embodiment 2;

[0036] Figure 8Schematic diagram of the front structure of the air plate 2 in Embodiment 2;

[0037] Figure 9 Schematic diagram of the bipolar plate structure of the present invention. Detailed implementation manners

[0038] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0040] Unless otherwise specified, the materials, instruments, and equipment used in the present invention are conventional materials, instruments, and equipment in the art. For example, the material of the bipolar plate can be a graphite bipolar plate or a metal bipolar plate commonly used in the art.

[0041] Embodiment 1

[0042] As Figure 2-4 shown, a bipolar plate for an atmospheric pressure air-cooled fuel cell can be matched with an air-cooled stack of 30 kW to 0.1 kW. The bipolar plate is 5 - 30 cm long and 5 - 10 cm wide; it includes a hydrogen plate 1 and an air plate 2. An air flow guiding groove 21 is provided on the front of the air plate 2, and a hydrogen flow channel 11 is provided on the front of the hydrogen plate 1. The back of the hydrogen plate 1 and the air plate 2 are hermetically connected to form a bipolar plate. Hydrogen inlets and outlets 12 are provided at both ends of the bipolar plate; hydrogen tunnel flow guiding grooves 14 are provided at both ends of the middle interlayer of the bipolar plate, and air tunnel flow guiding grooves 22 are provided on both sides. The hydrogen tunnel flow guiding grooves 14 communicate with the hydrogen flow channel 11; the air tunnel flow guiding grooves 22 communicate with the air flow guiding groove 21.

[0043] Among them, the hydrogen tunnel flow guiding grooves 14 are provided on the back of the hydrogen plate 1, or on the back of the air plate 2, or multiple hydrogen tunnel flow guiding grooves 14 are dispersedly provided on the backs of the hydrogen plate 1 and the air plate 2. The air tunnel flow guiding grooves 22 are provided on the back of the air plate 2, or on the back of the hydrogen plate 1, or multiple air tunnel flow guiding grooves 22 are dispersedly provided on the backs of the hydrogen plate 1 and the air plate 2. In this embodiment, multiple hydrogen tunnel flow guiding grooves 14 are dispersedly provided on the back of the air plate 2, and multiple air tunnel flow guiding grooves 22 are dispersedly provided on the back of the air plate 2.

[0044] Specifically, as Figure 2-3 shown, an air flow guiding groove 21 is provided on the front of the air plate 2, and a sealing groove a4 is provided around the air flow guiding groove 21 (that is, the air flow guiding groove 21 does not penetrate the front of the air plate 2). Multiple parallel air tunnel flow guiding grooves 22 are provided on the back of the air plate 2, and multiple air tunnel flow guiding grooves 22 penetrate the back of the air plate 2 in the length direction (see Figure 3), corresponding to and penetrating through the air guiding grooves 21 on the front surface of the air plate one by one in the depth direction, that is, the air tunnel guiding grooves 22 penetrate through the air plate body at the positions corresponding to the air guiding grooves 21, so that the back air tunnel guiding grooves 22 and the front air guiding grooves 21 are designed to be connected in a one-to-one correspondence, and the widths of the grooves are the same. The air guiding grooves 21 and the air tunnel guiding grooves 22 are connected and completely penetrate the entire air plate 2, making the air resistance in each guiding groove smaller and the weight of the plate lighter. On both sides of the hydrogen plate 1, there are also provided a plurality of air drainage grooves 24 (see Figure 4 ), making the air introduction into the bipolar plate sandwich smoother.

[0045] Air is introduced from the air tunnel guiding grooves 22 on the back surface, passes through the air plate 2 body and enters the air guiding grooves 21 on the front surface to participate in the reaction and cool the bipolar plate.

[0046] As Figure 4-5 shown, on the front surface of the hydrogen plate 1, there are hydrogen flow channels 11, with hydrogen inlets and outlets 12 provided at both ends, and hydrogen drainage holes 13 are provided at both ends of the hydrogen flow channels 11 and penetrate through to the back surface thereof; after the back surfaces of the hydrogen plate 1 and the air plate 2 are hermetically connected, a plurality of hydrogen tunnel guiding grooves 14 provided on the back surface of the air plate 2 are connected to the hydrogen flow channels 11 through the hydrogen drainage holes 13. Hydrogen is introduced from the hydrogen inlets and outlets 12, introduced into the hydrogen drainage holes 13 through the hydrogen tunnel guiding grooves 14, and flows towards the hydrogen flow channels 11.

[0047] As Figure 5 shown, on the back surfaces of both the hydrogen plate 1 and the air plate 2, there are sealing grooves b3, and the sealing grooves b3 on the two plates correspond to each other and are arranged around the hydrogen inlets and outlets 12 and the hydrogen tunnel guiding grooves 14. The sealing frame is arranged in the sealing grooves b3 by dispensing. In this embodiment, the air plate and the hydrogen plate are metal plates and are spot welded together by laser welding technology to form a bipolar plate. Hydrogen enters from the hydrogen inlet at one end of the bipolar plate, is introduced into the hydrogen tunnel guiding grooves 14 in the sandwich where the hydrogen plate 1 and the air plate 2 are attached, passes through the hydrogen plate 1 body through the hydrogen drainage holes 13, enters the introduced hydrogen flow channels 11 on the front surface, flows along the hydrogen flow channels 11 to the hydrogen drainage holes 13 at the other end of the hydrogen plate 1, passes through the hydrogen plate 1 body, and flows out from the hydrogen outlet introduced from the hydrogen tunnel guiding grooves on the back surface of the hydrogen plate 1.

[0048] The blower blows air into the air tunnel guiding grooves 22 on both sides of the bipolar plate sandwich, passes through the air plate 2 body and flows along the air guiding grooves 21 to participate in the reaction while cooling the bipolar plate.

[0049] A membrane electrode is sandwiched between two bipolar plates to form a single cell. One side of the membrane electrode is the air plate 2 in one of the bipolar plates, and the other side is the hydrogen plate 1 in the other bipolar plate. Since the front sides of the hydrogen plate 1 and the air plate 2 are provided with corresponding sealing grooves a4, a matching sealing frame is placed. During the pressing process, the sealing frames on both sides of the membrane electrode are subjected to exactly corresponding, matching, and equal pressures, protecting the membrane electrode and avoiding damage to the membrane electrode caused by incomplete corresponding and matching forces.

[0050] Since air is introduced from the side air tunnel diversion groove 22 of the interlayer between the bipolar plates, passes through the air plate 2, and then flows along the air diversion groove 21 on the front side of the air plate, the air diversion groove 21 does not need to penetrate the entire front side of the air plate in the length direction. Therefore, corresponding sealing grooves a4 can be set around the front side of the air plate 2 opposite to the front side of the hydrogen plate 1. After setting the sealing frame, a good seal can be formed, and there will be no problem that a common air-cooled plate cannot be sealed because a through air diversion groove cannot be provided with a sealing groove.

[0051] Embodiment 2

[0052] See Figure 6-9 , in this embodiment, the air tunnel diversion grooves 22 are located on the opposite sides of the back of the air plate 2. The air tunnel diversion grooves 22 are composed of multiple small diversion grooves, and each diversion groove corresponds to the air diversion groove on the front side one by one. Air is introduced from the air tunnel diversion grooves 22 on the back, passes through the air plate 2 body, and enters the air diversion grooves 21 on the front. Air drainage holes 23 penetrating the air plate 2 are provided at both ends of each air diversion groove 21 on the front side of the air plate 2. One end of the air drainage hole 23 is connected to the air diversion groove 21 on the front, and the other end is connected to the air tunnel diversion groove 22 on the back.

[0053] Hydrogen drainage holes 13 penetrating the hydrogen plate 1 are provided at both ends of each hydrogen flow channel 11 on the front side of the hydrogen plate 1. One end of the hydrogen drainage hole 13 is connected to the hydrogen flow channel 11 on the front, and the other end is connected to the hydrogen tunnel diversion groove 14 on the back.

[0054] Sealing grooves b3 are provided on the backs of both the hydrogen plate 1 and the air plate 2, and the sealing grooves on the two plates correspond to each other. The sealing frame is set in the sealing groove b3 by dispensing glue, and the backs of the hydrogen plate 1 and the air plate 2 are adhesively bonded and sealed together to form a bipolar plate.

[0055] Hydrogen is introduced from the hydrogen inlet into the hydrogen tunnel diversion groove 14 between the bipolar plates, then introduced into one end of the hydrogen flow channel 11 on the front side of the hydrogen plate 1 through the hydrogen drainage hole 13, flows along the hydrogen flow channel 11 to the other end of the hydrogen drainage hole 13, returns to the hydrogen tunnel diversion groove 14 between the bipolar plates, and then is discharged from the hydrogen outlet;

[0056] Air is introduced from the air tunnel diversion grooves 22 on both sides of the bipolar plate sandwich, passes through the air plate 2 body through the air diversion holes 23, enters the front air diversion groove 21, flows along the air diversion groove 21 to the air tunnel diversion groove 22 at the other end, and then is discharged from the other side of the bipolar plate sandwich.

[0057] Embodiment 3

[0058] The air tunnel diversion grooves 22 are located on the opposite sides of the back of the air plate 2. The entire air tunnel diversion groove 22 is a long strip groove, corresponding to all the air diversion grooves, and there are 2 - 5 reinforcing ribs in the long strip groove to prevent insufficient strength during the pressing process of the bipolar plate. The rest is the same as in Embodiment 1.

[0059] Embodiment 4

[0060] The air tunnel diversion grooves 22 are located on the opposite sides of the back of the air plate 2. The air tunnel diversion grooves 22 are multiple wide diversion grooves, and each wide diversion groove corresponds to 3 - 4 air diversion grooves 21.

[0061] The rest is the same as in Embodiment 1.

[0062] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A bipolar plate for an atmospheric pressure air-cooled fuel cell, comprising a hydrogen plate (1) and an air plate (2), wherein the front of the air plate (2) is provided with an air guide groove (21), the front of the hydrogen plate (1) is provided with a hydrogen flow channel (11), the backs of the hydrogen plate (1) and the air plate (2) are sealed and connected to form a bipolar plate, and hydrogen inlet and outlet (12) are provided at both ends of the bipolar plate; characterized in that: The bipolar plate has hydrogen tunnel guide grooves (14) at both ends of the middle interlayer and air tunnel guide grooves (22) at both sides. The hydrogen tunnel guide groove (14) is connected to the hydrogen flow channel (11); and the air tunnel guide groove (22) is connected to the air guide groove (21).

2. A bipolar plate for a normal pressure air-cooled fuel cell according to claim 1, characterized in that: The hydrogen tunnel guide groove (14) is arranged on the back of the hydrogen plate (1), or on the back of the air plate (2), or a plurality of hydrogen tunnel guide grooves (14) are dispersedly arranged on the back of the hydrogen plate (1) and the back of the air plate (2).

3. A bipolar plate for a normal pressure air-cooled fuel cell according to claim 1 or 2, characterized in that: Both ends of each hydrogen flow channel (11) on the front side of the hydrogen plate (1) are provided with a hydrogen drainage hole (13) penetrating the hydrogen plate (1); one end of the hydrogen drainage hole (13) is connected to the hydrogen flow channel (11) on the front side, and the other end is connected to the hydrogen tunnel guide groove (14) on the back side.

4. The bipolar plate for a normal pressure air-cooled fuel cell according to claim 1, characterized in that: The air tunnel guide groove (22) is arranged on the back of the air plate (2), or on the back of the hydrogen plate (1), or a plurality of air tunnel guide grooves (22) are dispersedly arranged on the back of the hydrogen plate (1) and the air plate (2).

5. A bipolar plate for a normal pressure air-cooled fuel cell according to claim 1 or 4, characterized in that: The air tunnel guide grooves (22) are arranged on the back of the air plate (2); a plurality of air tunnel guide grooves (22) penetrate the back of the air plate (2) in the length direction and penetrate the air guide grooves (21) on the front of the air plate in a one-to-one correspondence in the depth direction.

6. A bipolar plate for a normal pressure air-cooled fuel cell according to claim 1 or 4, characterized in that: The air tunnel guide groove (22) is composed of a plurality of small guide grooves, each of which corresponds to the front air guide groove (21) one by one; Alternatively, the air tunnel guide groove (22) is a plurality of wide guide grooves, and each wide guide groove corresponds to 3-4 air guide grooves (21); The air tunnel guide groove (22) is a long groove located on two opposite sides of the back of the air plate (2), the long groove corresponds to all the air guide grooves (21), and 2-5 reinforcing ribs are arranged in the long groove.

7. A bipolar plate for a normal pressure air-cooled fuel cell according to claim 6, characterized in that: Both ends of each air guide groove (21) on the front side of the air plate (2) are provided with air guide holes (23) penetrating the air plate (2); one end of the air guide hole (23) is connected to the air guide groove (21) on the front side, and the other end is connected to the air tunnel guide groove (22) on the back side.

8. The bipolar plate for a normal pressure air-cooled fuel cell according to claim 1, characterized in that: The backs of the hydrogen plate (1) and the air plate (2) are both provided with sealing grooves b (3), and the sealing grooves on the two plates correspond to each other. The sealing frame is arranged in the sealing groove b (3) by dispensing glue, and the backs of the hydrogen plate (1) and the air plate (2) are bonded or welded together to form a bipolar plate.

9. The bipolar plate for a normal pressure air-cooled fuel cell according to claim 1, characterized in that: Hydrogen is introduced from the hydrogen inlet into the hydrogen tunnel guide groove (14) between the bipolar plate interlayers, then introduced into one end of the hydrogen flow channel (11) on the front side of the hydrogen plate (1) through the hydrogen drainage hole (13), flows along the hydrogen flow channel (11) to the hydrogen drainage hole (13) at the other end, returns to the hydrogen tunnel guide groove (14) between the bipolar plate interlayers, and then is discharged from the hydrogen outlet; Air is introduced from the air tunnel guide grooves (22) on both sides of the bipolar plate interlayer, passes through the air plate (2) body and enters the front air guide groove (21), participates in the reaction, and cools the bipolar plate.

10. The bipolar plate for a normal pressure air-cooled fuel cell according to claim 1, characterized in that: The bipolar plate includes a graphite bipolar plate, a soft graphite molded bipolar plate or a metal plate.

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