Polar plate assembly for methanol reforming fuel cell and fuel cell stack

Abstract

The invention relates to the technical field of fuel cells, and discloses a polar plate assembly for a methanol reforming fuel cell and a fuel cell stack, a first flow channel for reformed gas to circulate is formed in an anode plate in the polar plate assembly, and when the reformed gas flows in the first flow channel, the space of the first flow channel is gradually reduced from a first end to a second end, so that the reformed gas flows in the first flow channel; the flow rate of the reformed gas from the first end to the second end is gradually increased, the initial flow rate of the reformed gas at the first end is relatively low, sufficient reaction time can be achieved, the subsequent flow rate is gradually increased, meanwhile, negative pressure can be formed, and then impurities are taken away and flow out; the problem that carbon monoxide and carbon dioxide are attached and accumulated in a flow channel in the prior art can be solved. And the transition part with the smooth curve structure is arranged between the two adjacent step sections, so that the flowing resistance and turbulent flow phenomena of the fluid in the first flow channel can be reduced, and the adhesion and accumulation of carbon monoxide and carbon dioxide in the reformed gas in the flow channel are further avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a polar plate assembly and a fuel cell stack for a methanol reforming fuel cell. Background Art

[0002] The fuel cell stack is the core part of the hydrogen fuel cell power system. It is composed of multiple single cells stacked in series. The bipolar plate is the core structural component of the stack, which plays the role of evenly distributing gas, draining water, conducting heat and electricity. They account for 60% of the weight of the entire fuel cell and about 20% of the cost. Their performance directly affects the output power and service life of the battery. There are flow channels on the bipolar plate, which are channels for providing fuel (hydrogen) and oxidant (oxygen or air). The flow channel guides the flow direction of the reaction gas to ensure that the reaction gas is evenly distributed to all parts of the electrode. The remaining reaction gas and the water produced by the reaction are discharged from the battery through the bipolar plate flow channel.

[0003] With the continuous advancement of energy technology, methanol reforming fuel cell system as an efficient and clean energy conversion device has received widespread attention and application. Methanol reforming fuel cell system produces hydrogen by mixing methanol with water vapor and reforming it, and uses hydrogen to carry out electrochemical reaction in the fuel cell stack to generate electricity and water. One of the core components of the methanol reforming fuel cell system is the bipolar plate and the fuel cell stack it constitutes. However, in practical applications, the reformed gas contains a certain amount of carbon monoxide and carbon dioxide. The reformed gas encounters a large resistance when flowing in the flow channel of the existing bipolar plate. There is a problem that carbon monoxide and carbon dioxide are easy to adhere and accumulate in the flow channel, which leads to uneven distribution of the reaction gas. These problems will seriously affect the performance of the membrane electrode, resulting in reduced efficiency and shortened life of the fuel cell stack.

[0004] SUMMARY OF THE INVENTION

[0005] The technical problem solved by the present invention is: how to avoid the adhesion and accumulation of carbon monoxide and carbon dioxide in the flow channel of the bipolar plate, so as to ensure the performance of the fuel cell stack.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A plate assembly for a methanol reforming fuel cell, comprising:

[0008] An anode plate, wherein a first flow channel is provided on one side of the anode plate, and two ends of the first flow channel are respectively connected to a first inlet and a first outlet, the first flow channel comprises a first end and a second end, the first end is located at an end close to the first inlet, the size of the first end of the first flow channel is larger than the size of the second end, and a direct current slot is provided on the other side of the anode plate;

[0009] A cathode plate, wherein a second flow channel is disposed on one side of the cathode plate away from the anode plate, the second flow channel comprises a plurality of sections disposed at an angle, the two ends of the second flow channel are respectively connected to a second inlet and a second outlet, and a direct current slot is disposed on the other side of the cathode plate;

[0010] The butted anode plate and cathode plate are butted and enclosed by a DC trough to form a DC channel, and two ends of the DC channel are respectively connected to the third inlet and the third outlet.

[0011] In one embodiment of the present invention, the first flow channel includes at least two step sections, there is a height difference between adjacent step sections, and the depths of the multiple step sections gradually decrease from the first end to the second end.

[0012] In one embodiment of the present invention, the height difference between two adjacent step sections may be between 0.1 and 0.5 mm.

[0013] In one solution of the present invention, a transition portion with a smooth curve structure is provided at the step position of two adjacent step sections.

[0014] In one embodiment of the present invention, the radius of curvature of the transition portion is between 1 and 3 mm.

[0015] In one embodiment of the present invention, the width of the first flow channel decreases linearly from the first end to the second end.

[0016] In one embodiment of the present invention, the width of the first flow channel decreases by 1% to 5% from the first end to the second end.

[0017] In one embodiment of the present invention, the width of the direct current groove is between 5 and 10 mm, and the width of the flow channel ridge is between 1 and 2 mm.

[0018] In one solution of the present invention: a flow guide chamber is provided between the anode plate and the cathode plate at the end of the direct current channel, and a plurality of flow guide blocks are fixedly arranged in the flow guide chamber.

[0019] A fuel cell stack comprises at least one set of the above-mentioned polar plate assemblies for a methanol reforming fuel cell.

[0020] According to the present invention, a plate assembly and a fuel cell stack for a methanol reforming fuel cell have at least one of the following technical effects:

[0021] In the present application, a first flow channel for the circulation of reformed gas is provided on the anode plate, and the size of the first end of the first flow channel is larger than the size of the second end, so that when the reformed gas flows in the first flow channel, under the same flow rate, the space of the first flow channel gradually decreases from the first end to the second end, and the flow rate of the reformed gas from the first end to the second end will gradually increase. The initial flow rate of the reformed gas at the first end is relatively low, which can have sufficient reaction time, and the subsequent flow rate gradually increases. At the same time, negative pressure can be formed, and then impurities are taken away and flowed out, which can solve the problem of carbon monoxide and carbon dioxide adhering and accumulating in the flow channel in the prior art. By providing a transition portion with a smooth curve structure between two adjacent step sections, the flow resistance and turbulence of the fluid in the first flow channel can be reduced, thereby further avoiding the adhesion and accumulation of carbon monoxide and carbon dioxide in the reformed gas in the flow channel.

[0022] By bending the second flow channel, the overall flow channel space is increased, the reaction path is extended, the area available for contact between the gas and the catalyst is increased, and the residence time of the gas in the second flow channel is increased, thereby ensuring the reaction effect of the gas and improving the reaction efficiency.

[0023] In the present application, after the anode plate and the cathode plate are butted together, the DC slots are butted together to form a wide-spacing DC channel, and the guide slots are butted together to form a guide chamber. By setting a wide-spacing DC channel, the uniform distribution of the circulating oil in the channel can be ensured, and the impurities produced by the cracking of triethylene glycol circulating oil at high temperature are prevented from adhering to the channel, thereby ensuring the cleanliness of the inside of the bipolar plate. This not only ensures that the thermal conductivity of the system is not affected, but also improves the reliability and stability of the system. The guide chamber and the guide block microstructure arranged therein can improve the flow state of the fluid, ensure the uniform distribution of the circulating oil in the channel, reduce the adhesion of impurities, and ultimately achieve the purpose of improving the reaction efficiency and battery performance.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and easy to understand from the description of the embodiments in conjunction with the following drawings. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. Among them:

[0026] Figure 1 It is a schematic diagram of the overall structure of the electrode plate assembly of the present invention;

[0027] Figure 2 A top view of the anode plate of the present invention;

[0028] Figure 3 A bottom view of the anode plate of the present invention;

[0029] Figure 4 A bottom view of the cathode plate of the present invention;

[0030] Figure 5 is a top view of the cathode plate of the present invention;

[0031] Figure 6 It is a partial enlarged view of the stepped decreasing flow channel of the anode plate of the present invention;

[0032] Figure 7 is a cross-sectional view of a bipolar plate of the present invention;

[0033] Figure 8 For the present invention Figure 7 A partial enlarged view of the part in FIG.

[0034] Fig. 9 This is a comparison chart of the test performance of the bipolar plate of the present invention and the traditional bipolar plate.

[0035] The reference numerals in the figure are: 1. bipolar plate; 2. anode plate; 3. cathode plate; 4. first flow channel; 5. direct current slot; 6. second flow channel; 7. guide block; 8. reforming gas inlet; 9. circulating oil inlet; 10. air inlet; 11. reforming gas outlet; 12. circulating oil outlet; 13. air outlet; 14. guide slot; 15. transition section. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0038] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0039] See also Figure 1-8 , the present application provides a hydrogen fuel cell power system, the core part of which is a fuel cell stack. In the present embodiment, the fuel cell stack is a methanol reforming fuel cell stack, which is composed of a plurality of single cells stacked in series. The fuel cell stack includes a plate assembly (bipolar plate 1), a membrane electrode assembly (MEA), a proton exchange membrane, a catalyst, a gas diffusion layer (GDL), a heat removal plate, a collector, an insulating plate and an end cover plate, etc. When the stack is working, hydrogen and oxygen (or air) are introduced from the inlet respectively, distributed to the bipolar plate 1 of each single cell through the main gas channel of the stack, and evenly distributed to the electrode through the bipolar plate 1. The electrode support contacts the catalyst for electrochemical reaction to convert chemical energy into electrical energy.

[0040] Among them, the plate assembly is used for uniformly distributing gas, draining water, conducting heat and electricity. The plate assembly is provided with a flow channel, which is a channel for providing fuel (hydrogen) and oxidant (oxygen or air). The flow channel guides the flow direction of the reaction gas to ensure that the reaction gas is evenly distributed to all parts of the electrode. The reaction gas remaining after the reaction and the water produced by the reaction are discharged from the battery through the bipolar plate 1 flow channel. In this embodiment, the fuel cell stack includes at least one set of plate assemblies. In practical applications, multiple bipolar plates 1 can be assembled as needed to form a fuel cell stack. During the assembly process, when the plate assembly (hereinafter referred to as bipolar plate 1) is set to multiple groups, the anode plate 2 of each group of bipolar plates 1 is connected to the cathode plate 3 of the adjacent bipolar plate 1 to form an alternating arrangement structure. At the same time, ensure that the interfaces such as the reformed gas inlet 8, the reformed gas outlet 11, the air inlet 10, the air outlet 13, the circulating oil inlet 9 and the circulating oil outlet 12 are correctly docked to realize the input and output of gas and the circulation of liquid.

[0041] See also Figure 1-8In one embodiment of the present invention, the plate assembly for methanol reforming fuel cell includes an anode plate 2 and a cathode plate 3, both of which are made of conductive materials, such as stainless steel or graphite. The plate assembly is provided with a first inlet, a second inlet, a third inlet, a first outlet, a second outlet and a third outlet, and the anode plate 2 and the cathode plate 3 are provided with corresponding notches, and the two are connected to form a bipolar plate 1 to form a corresponding first inlet, a second inlet, a third inlet, a first outlet, a second outlet and a third outlet. Among them, the first inlet and the first outlet are respectively located at the positions where they can be used for the input and output of reformed gas, respectively, as the reformed gas inlet 8 and the reformed gas outlet 11. The first inlet and the first outlet are diagonally distributed on the bipolar plate 1 to increase the flow path of the reformed gas in the bipolar plate 1 and thus ensure the reaction effect. Similarly, the second inlet and the second outlet are diagonally distributed, respectively as the air inlet 10 and the air outlet 13 for the input and output of air (oxygen). The reformed gas inlet 8 and the air inlet 10 can be located at the same end of the bipolar plate 1, or at both ends of the bipolar plate 1, so as to achieve the opposite flow of the two gases and ensure the effect of the bipolar plate 1 as much as possible. The third inlet and the third outlet are respectively arranged at both ends of the bipolar plate 1, as the circulating oil inlet 9 and the circulating oil outlet 12, respectively, for the input and output of the liquid to form a circulating flow of the liquid.

[0042] See also Figure 1-8 In one embodiment of the present invention, a first flow channel 4 is provided on one side of the anode plate 2 for the circulation of the reformed gas, and the first flow channel 4 includes a first end and a second end, wherein the first end is an end close to the reformed gas inlet 8, and the depth and width of the first end of the first flow channel 4 are greater than the depth and width of the second end. The depth and width of the first flow channel 4 may decrease in a stepwise manner or in a linear manner from the first end to the second end.

[0043] See also Figure 1-8 In one embodiment of the present invention, as an example, the first flow channel 4 includes at least two step sections of different heights (depths) to form a step-decreasing flow channel. There is a height difference between adjacent step sections, and the depth of one end close to the reforming gas inlet 8 is greater than the depth of the other end, that is, the depth (height) of multiple step sections decreases in a step-by-step manner from the direction of the reforming gas inlet 8 to the direction of the reforming gas outlet 11. The height difference between two adjacent step sections can be between 0.1 and 0.5 mm. As an example, the height difference between two adjacent stage sections is 0.3 mm. The flow channel width dimension of each step section of the first flow channel 4 decreases in a linear decreasing manner from the first end to the second end, and the width reduction range is between 1% and 5%. As an example, the width reduction range from the first end to the second end is 3%.

[0044] See also Figure 1-8 In one embodiment of the present invention, the depth and width of the first end (input end) of the first flow channel 4 are greater than the depth and width of the second end (output end). When the reformed gas flows in the first flow channel 4, under the same flow rate, the space of the first flow channel 4 gradually decreases from the first end to the second end, and the flow rate of the reformed gas from the first end to the second end will gradually increase. The initial flow rate of the reformed gas at the first end is relatively low, and it can have sufficient reaction time. The subsequent flow rate gradually increases, and at the same time, negative pressure can be formed, thereby taking away impurities and flowing out, which can solve the problem of carbon monoxide and carbon dioxide adhering to and accumulating in the flow channel in the prior art. Further, a transition portion 15 is provided at the step position of two adjacent step sections, and the transition portion 15 is provided in the form of a smooth curve, which can be provided in the form of a fillet, and the curvature radius of the transition portion 15 can be between 1 and 3 mm. As an example, the curvature radius of the transition portion 15 is 2 mm. By providing a transition portion 15 with a smooth curve structure between two adjacent step sections, the flow resistance and turbulence of the fluid in the first flow channel 4 can be reduced, thereby further avoiding the adhesion and accumulation of carbon monoxide and carbon dioxide in the reformed gas in the flow channel.

[0045] See also Figure 1-8 In one embodiment of the present invention, a second flow channel 6 is provided on a side of the cathode plate 3 away from the anode plate 2. The second flow channel 6 is bent, that is, the second flow channel 6 may include multiple sections set at an angle, which may be bent in a Z shape or an S shape, or a corresponding bending layout may be selected as required. By bending the second flow channel 6, the overall flow channel space is increased, the reaction path is extended, the area available for contact between the gas and the catalyst is increased, and the time the gas stays in the second flow channel 6 is increased, thereby ensuring the reaction effect of the gas and improving the reaction efficiency.

[0046] See also Figure 1-8In one embodiment of the present invention, a DC slot 5 connected to the circulating oil inlet 9 and the circulating oil outlet 12 is respectively provided on the mating surfaces of the anode plate 2 and the cathode plate 3. The width of the DC slot 5 can be between 5 and 10 mm, and the width of the flow channel ridge can be between 1 and 2 mm. As an example, the width of the DC slot 5 is 7 mm, and the width of the flow channel ridge is 1.5 mm. A guide slot 14 is respectively provided at both ends of the DC slot 5. The DC slot 5 is connected to the guide slot 14. A plurality of guide blocks 7 are fixedly arranged in the guide slot 14, and the guide blocks 7 can be evenly distributed in the guide slot 14. The guide block 7 is a microstructure with a protrusion. Specifically, the microstructure of the guide block 7 can be a matrix-type protrusion structure with a height of 0.5 to 1.5 mm evenly distributed in the guide slot 14, and the distance between two adjacent protrusions can be 2 to 4 mm. As an example, the microstructure of the guide block 7 is a matrix-type protrusion structure with a height of 1 mm, and the protrusion spacing is 3 mm.

[0047] See also Figure 1-8 In one of the embodiments of the present invention, triethylene glycol circulating oil is easily decomposed at high temperature to produce impurities. These impurities adhere to the inner surface of the bipolar plate 1 and affect the thermal conductivity of the system, thereby causing the battery performance to decline. In the present application, after the anode plate 2 and the cathode plate 3 are docked and matched, the DC slots 5 are docked and enclosed to form a wide-spaced DC channel, and the guide slots 14 are docked and enclosed to form a guide chamber. By setting a wide-spaced DC channel, the uniform distribution of the circulating oil in the flow channel can be ensured, and the impurities produced by the decomposition of triethylene glycol circulating oil at high temperature are prevented from adhering to the flow channel, thereby ensuring the cleanliness inside the bipolar plate 1. This not only ensures that the thermal conductivity of the system is not affected, but also improves the reliability and stability of the system. The flow state of the fluid can be improved by the guide chamber and the microstructure of the guide block 7 arranged therein, ensuring the uniform distribution of the circulating oil in the flow channel, reducing the attachment of impurities, and ultimately achieving the purpose of improving the reaction efficiency and battery performance.

[0048] See also Figure 1-8In one embodiment of the present invention, flow regulating valves are respectively provided at the reformed gas inlet 8, the air inlet 10 and the circulating oil inlet 9 to accurately control the flow of gas and liquid entering the fuel cell stack. This ensures a stable supply of reaction gas and liquid, thereby improving the performance and stability of the fuel cell. At the same time, temperature sensors and pressure sensors are respectively provided at the reformed gas inlet 8, the reformed gas outlet 11, the air inlet 10, the air outlet 13, the circulating oil inlet 9 and the circulating oil outlet 12. These sensors are used to monitor the temperature and pressure of the fuel gas and liquid in real time to ensure that the system is in the best working state. In addition, a gas chromatography mixed gas drying tube is also provided in front of the reformed gas inlet 8. The drying tube is used to dry and purify the reformed gas of the reforming system before entering the fuel cell stack to remove moisture and impurities therein and improve the performance and life of the fuel cell.

[0049] See also Figure 1-8 In one embodiment of the present invention, the temperature sensor and the pressure sensor are electrically connected to the control module respectively, and the control module is used to receive and process the signals sent by these sensors. The control module can automatically adjust the flow control valve according to the received temperature and pressure signals to achieve accurate control of the gas and liquid flow. At the same time, the control module can also monitor and warn the operating status of the system in real time according to the preset threshold value or algorithm. For example, when the temperature or pressure exceeds the preset value, the control module can automatically shut down the system or send an alarm signal to ensure the safe and stable operation of the system.

[0050] Test example: The bipolar plate 1 structure of the present invention is applied to a methanol reforming fuel cell system and a fuel cell stack thereof, and the proton exchange membrane performance of the same membrane electrode in the bipolar plate 1 of the present invention is compared with that of a conventional bipolar plate 1. The flow channel of the bipolar plate 1 of the present invention contains carbon monoxide and carbon dioxide in the reforming gas. The test results are as follows: Fig. 9 As shown, it can be seen from the test results that the performance of the flow channel structure of the bipolar plate 1 of the present invention is far better than that of the traditional flow channel structure.

[0051] Working principle of the present invention:

[0052] In the present application, a first flow channel 4 for the circulation of reformed gas is provided on the anode plate 2, and the size of the first end of the first flow channel 4 is larger than the size of the second end, so that when the reformed gas flows in the first flow channel 4, under the same flow rate, the space of the first flow channel 4 gradually decreases from the first end to the second end, and the flow rate of the reformed gas from the first end to the second end will gradually increase. The initial flow rate of the reformed gas at the first end is relatively low, which can have sufficient reaction time, and the subsequent flow rate gradually increases. At the same time, negative pressure can be formed, and then impurities are taken away and flowed out, which can solve the problem of carbon monoxide and carbon dioxide adhering and accumulating in the flow channel in the prior art. By providing a transition portion 15 with a smooth curve structure between two adjacent step sections, the flow resistance and turbulence of the fluid in the first flow channel 4 can be reduced, thereby further avoiding the adhesion and accumulation of carbon monoxide and carbon dioxide in the reformed gas in the flow channel.

[0053] By bending the second flow channel 6, the overall flow channel space is increased, the reaction path is extended, the area available for contact between the gas and the catalyst is increased, and the residence time of the gas in the second flow channel 6 is increased, thereby ensuring the reaction effect of the gas and improving the reaction efficiency.

[0054] In the present application, after the anode plate 2 and the cathode plate 3 are docked, the DC slots 5 are docked to form a wide-spaced DC channel, and the guide slots 14 are docked to form a guide chamber. By setting a wide-spaced DC channel, the uniform distribution of the circulating oil in the flow channel can be ensured, and impurities produced by the cracking of triethylene glycol circulating oil at high temperature are prevented from adhering to the flow channel, thereby ensuring the cleanliness of the inside of the bipolar plate 1. This not only ensures that the thermal conductivity of the system is not affected, but also improves the reliability and stability of the system. The flow state of the fluid can be improved by the guide chamber and the microstructure of the guide block 7 arranged therein, ensuring the uniform distribution of the circulating oil in the flow channel, reducing the adhesion of impurities, and ultimately achieving the purpose of improving the reaction efficiency and battery performance.

[0055] In summary, the bipolar plate 1 for the methanol reforming fuel cell system and the fuel cell stack provided by the present invention have the advantages of simple structure, superior performance, and easy control. Through the reasonable flow channel design and the setting of the microstructure of the guide block 7, the adverse effects of the reforming gas on the membrane electrode performance are reduced, and the flow efficiency and reaction efficiency of the reaction gas and liquid are improved; at the same time, through the application of the control module, the real-time monitoring and precise control of the system operation status are realized, ensuring the safe and stable operation of the system. Not only the key problems existing in the existing methanol reforming fuel cell system are solved, but also the performance and reliability of the system are significantly improved, the key steps of purifying the methanol reforming gas are omitted, the labor and cost are greatly reduced, and the influence of carbon monoxide and carbon dioxide contained in the reforming gas on the performance of the fuel cell stack is greatly reduced, which provides strong support for the commercial application of the methanol reforming fuel cell system.

[0056] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of application of the present invention should still fall within the scope of the claims of the present invention.

Claims

1. A plate assembly for a methanol reforming fuel cell, characterized in that: include: An anode plate (2), wherein a first flow channel (4) is provided on one side of the anode plate (2), the two ends of the first flow channel (4) are respectively connected to a first inlet and a first outlet, the first flow channel (4) comprises a first end and a second end, the first end is located at an end close to the first inlet, the size of the first end of the first flow channel (4) is larger than the size of the second end, and a direct current slot (5) is provided on the other side of the anode plate (2); A cathode plate (3), wherein a second flow channel (6) is arranged in a bent manner on a side surface of the cathode plate (3) away from the anode plate (2), the second flow channel (6) comprises a plurality of sections arranged at an angle, the two ends of the second flow channel (6) are respectively connected to a second inlet and a second outlet, and a direct current slot (5) is provided on the other side surface of the cathode plate (3); The butted anode plate (2) and cathode plate (3) are butted together via a DC trough (5) to form a DC channel, with both ends of the DC channel being connected to a third inlet and a third outlet, respectively.

2. A plate assembly for a methanol reforming fuel cell according to claim 1, characterized in that: The first flow channel (4) comprises at least two step sections, there is a height difference between adjacent step sections, and the depths of the multiple step sections gradually decrease from the first end to the second end.

3. A plate assembly for a methanol reforming fuel cell according to claim 2, characterized in that: The height difference between two adjacent step sections may be between 0.1 and 0.5 mm.

4. A plate assembly for a methanol reforming fuel cell according to claim 2, characterized in that: A transition portion (15) with a smooth curve structure is arranged at the step position of two adjacent step sections.

5. A plate assembly for a methanol reforming fuel cell according to claim 4, characterized in that: The curvature radius of the transition portion (15) is between 1 and 3 mm.

6. The plate assembly for a methanol reforming fuel cell according to claim 1, characterized in that: The width of the first flow channel (4) decreases linearly from the first end to the second end.

7. A plate assembly for a methanol reforming fuel cell according to claim 6, characterized in that: The width of the first flow channel (4) decreases by 1% to 5% from the first end to the second end.

8. The plate assembly for a methanol reforming fuel cell according to claim 1, characterized in that: The width of the direct current groove (5) is between 5 and 10 millimeters, and the width of the flow channel ridge is between 1 and 2 millimeters.

9. A plate assembly for a methanol reforming fuel cell according to claim 8, characterized in that: A flow guide chamber is provided between the anode plate (2) and the cathode plate (3) at the end of the direct current channel, and a plurality of flow guide blocks (7) are fixedly arranged in the flow guide chamber.

10. A fuel cell stack, characterized in that: It comprises a plate assembly for a methanol reforming fuel cell according to any one of claims 1 to 9.

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