A bipolar plate for a proton exchange membrane fuel cell

Abstract

The present invention provides a proton exchange membrane fuel cell bipolar plate, which is composed of a cathode plate and an anode plate, characterized in that the cathode plate and the anode plate are formed by stamping a metal sheet, a cathode flow field is stamped out of the outer side of the cathode plate, and an anode flow field is stamped out of the outer side of the anode plate, the cathode plate and the anode plate are bonded together, and formed into a whole by laser welding or bonding, and a closed coolant flow field is formed inside the cathode plate and the anode plate; the area of ​​the cathode, anode and coolant inlet / outlet common channel on the anode plate and the cathode plate is asymmetrically arranged. The bipolar plate and its flow field structure designed by the present invention can effectively improve the uniform distribution of the reaction gas to achieve uniform distribution of the reaction current, and at the same time smoothly discharge the liquid water and tail gas generated by the battery reaction; it can also reduce the weight and thickness of the bipolar plate, and improve the mass power and volume power of the fuel cell.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a bipolar plate for a proton exchange membrane fuel cell. Background Art

[0002] Compared with traditional energy conversion devices, proton exchange membrane fuel cells (PEMFC) have the advantages of high efficiency, energy saving, safety, and environmental protection, and therefore have great application prospects. Bipolar plates are one of the key components of PEMFC, accounting for more than 45% of the cost of the stack and 70%-80% of the weight of the stack. Therefore, it is necessary to develop bipolar plates with high conductivity, high corrosion resistance, high chemical compatibility, suitable mechanical properties, suitable hydrophilicity and hydrophobicity, and easy batch manufacturing to improve the life, reliability and specific power of fuel cells, thereby promoting the commercial development of PEMFC. The structure of the bipolar plate directly affects the electrochemical reaction and hydrothermal management of the fuel cell. The flow field on the bipolar plate provides a channel for the reaction gas and coolant to enter and exit, and at the same time determines the flow mode and distribution of the reaction gas and coolant.

[0003] Chinese patent publication number CN 101572318 B discloses a metal bipolar plate for a proton exchange membrane fuel cell, which alternately arranges the pits on the back of each boss in the cathode plate distribution area and the pits on the back of each boss in the anode plate, and the areas opposite to the pits constitute a continuous coolant distribution area, and then connects the parallel water flow channels on the anode and cathode plates to form a complete coolant flow channel. This design will have the problem of insufficient support area for the MEA by the point-shaped bosses, resulting in the inability to control the reaction gas pressure. At the same time, due to manufacturing errors, the cross-sectional area of ​​the coolant channel will be reduced, the flow resistance will increase, and the performance of the fuel cell will be seriously affected.

[0004] Chinese patent publication number CN 110212213 A discloses a metal bipolar plate for a proton exchange membrane fuel cell, in which an anode flow field is provided outside the anode plate, a cathode flow field is provided outside the cathode plate, and the cavity between the anode plate and the cathode plate constitutes a coolant flow field. The coolant port is arranged on the upper and lower sides of the flow field. The advantage is that the vertical cross flow of the coolant and the reaction gas is realized, but it will increase the area of ​​the bipolar plate, or reduce the active area ratio of the bipolar plate, thereby reducing the volume power ratio of the fuel cell, and will also increase the difficulty of the design of the later manifold.

[0005] Therefore, it is necessary to provide a rationally designed bipolar plate and its flow field to improve the uniform distribution of the reaction gas, so as to achieve uniform distribution of the reaction current, and at the same time smoothly discharge the liquid water and exhaust gas generated by the battery reaction; it can also reduce the weight and thickness of the bipolar plate, and improve the mass power ratio and volume power ratio of the fuel cell. Summary of the invention

[0006] According to the above technical problems of uneven distribution of reaction gas and current caused by defects in the bipolar plate structure design in the prior art, a proton exchange membrane fuel cell bipolar plate is provided. The present invention mainly bonds the cathode plate and the anode plate of the stamped flow field together to form a closed coolant flow field to increase the effective use area of ​​the bipolar plate; at the same time, the common inlet and outlet channel areas of the air cavity and the coolant cavity are arranged in an asymmetric manner to increase the flow rate of the reaction gas and facilitate the discharge of water and tail gas generated by the reaction; and further improve the heat exchange efficiency of the stack by combining different structural forms of the anode and cathode distribution areas.

[0007] The technical means adopted by the present invention are as follows:

[0008] A proton exchange membrane fuel cell bipolar plate, consisting of a cathode plate and an anode plate, characterized in that the cathode plate and the anode plate are formed by stamping metal thin plates, a cathode flow field is stamped out of the outer side of the cathode plate, and an anode flow field is stamped out of the outer side of the anode plate, the cathode plate and the anode plate are bonded together and formed into a whole by laser welding or bonding, and a closed coolant flow field is formed on the inner side of the cathode plate and the anode plate; the area of ​​the common channel of the cathode, anode and coolant inlet / outlet on the anode plate and the cathode plate is asymmetrically arranged.

[0009] Furthermore, the area of ​​the cathode outlet common channel is larger than the area of ​​the cathode inlet common channel; the area of ​​the anode outlet common channel is larger than the area of ​​the anode inlet common channel; and the area of ​​the coolant outlet common channel is larger than the area of ​​the coolant inlet common channel.

[0010] Furthermore, the area of ​​the cathode outlet common channel is larger than the area of ​​the cathode inlet common channel, and the ratio is 1.2-2.2; the area of ​​the anode outlet common channel is larger than the area of ​​the anode inlet common channel, and the ratio is 1.0-1.8; the area of ​​the coolant outlet common channel is larger than the area of ​​the coolant inlet common channel, and the ratio is 1.3-2.0.

[0011] Furthermore, the cathode inlet distribution area and the cathode outlet distribution area on the cathode plate are both parallel flow channels, and the flow channel angles are arranged at 45°-60°.

[0012] Furthermore, the anode inlet distribution area and the anode outlet distribution area on the anode plate are both bifurcated structures, which are one or more combinations of 1-to-2, 1-to-3, and 1-to-4.

[0013] Furthermore, fence-type support structures are provided at the cathode inlet / outlet, the anode inlet / outlet, and the coolant inlet / outlet.

[0014] Furthermore, the cathode reaction zone of the cathode plate and the anode reaction zone of the anode plate are composed of multiple groups of grooves and protrusions, extending in a wave shape, and the flow field periods of the cathode reaction zone and the anode reaction zone are consistent, and the two are staggered.

[0015] Furthermore, a cathode sealing glue line groove is provided at the edge of the cathode plate, and an anode sealing glue line groove is provided at the edge of the anode plate. After the bipolar plates are welded and formed, the glue lines are bonded into the glue line grooves to achieve sealed assembly of the bipolar plates.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The present invention adopts an optimized flow channel design to increase the effective use area of ​​the bipolar plate, and arranges the cathode reaction zone and the anode reaction zone with a combination of grooves and protrusions extending in a wave shape, so that the reaction zone process cycles are consistent, and the two are staggered, which can improve the uniformity of coolant distribution and reduce flow resistance.

[0018] 2. The common inlet and outlet passage areas of the air cavity and the coolant cavity of the present invention are arranged asymmetrically, which can enhance the pressure difference between the inlet and outlet, increase the flow rate of the reaction gas, and facilitate the discharge of the water and tail gas generated by the reaction.

[0019] 3. The anode distribution area and the cathode distribution area of ​​the present invention are combined in different structural forms, which is beneficial to improving the flow channel of the coolant cavity and enhancing the heat exchange efficiency of the fuel cell stack.

[0020] In summary, the bipolar plate and its flow field structure designed by the present invention can effectively improve the uniform distribution of the reaction gas to achieve uniform distribution of the reaction current, while smoothly discharging the liquid water and tail gas generated by the battery reaction; it can also reduce the weight and thickness of the bipolar plate, and improve the mass power ratio and volume power of the fuel cell.

[0021] Based on the above reasons, the present invention can be widely promoted in the field of fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 Schematic diagram of the structure of the bipolar plate of the present invention.

[0024] Figure 2 It is a schematic structural diagram of the cathode plate of the present invention.

[0025] Figure 3 It is a structural schematic diagram of the anode plate of the present invention.

[0026] Figure 4 It is a partial enlarged schematic diagram of the cathode distribution area of ​​the present invention.

[0027] In the figure: 1, cathode plate; 2, anode plate; 3, anode inlet I; 3', anode outlet I; 4, cathode inlet I; 4', cathode outlet I; 5, coolant inlet I; 5', coolant outlet I; 6, cathode inlet distribution area; 6', cathode outlet distribution area; 7, cathode reaction area; 8, cathode sealant line groove; 9, anode inlet II; 9', anode outlet II; 10, cathode inlet II; 10', cathode outlet II; 11, coolant inlet II; 11', coolant outlet II; 12, anode inlet distribution area; 12', anode outlet distribution area; 13, anode reaction area; 14, anode sealant line groove; 15, inspection plug-in slot; 16, QR code identification area. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. 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.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0031] like Figure 1 , which is a schematic structural diagram of a metal bipolar plate of a proton exchange membrane fuel cell provided in an embodiment of the present invention.

[0032] The bipolar plate is composed of a cathode plate 1 and an anode plate 2, and the material can be stainless steel, titanium alloy or other metal alloys. The cathode flow field is punched out of the cathode plate, and the anode flow field is punched out of the anode plate. The positive and negative plates are bonded together and formed into a whole by laser welding or bonding, and a closed coolant flow field is formed inside the positive and negative plates.

[0033] like Figure 2 As shown, the cathode plate is provided with an anode inlet Ⅰ3, an anode outlet Ⅰ3', a cathode inlet Ⅰ4, a cathode outlet Ⅰ4', a coolant inlet Ⅰ5, a coolant outlet Ⅰ5', a cathode inlet distribution area 6, a cathode reaction area 7, a cathode outlet distribution area 6' and a cathode sealing glue line groove 8.

[0034] like Figure 3 As shown, the anode plate is provided with an anode inlet II9, an anode outlet II9', a cathode inlet II10, a cathode outlet II10', a coolant inlet II11, a coolant outlet II11', an anode inlet distribution area 12, an anode reaction area 13, an anode outlet distribution area 12' and an anode sealing glue line groove 14.

[0035] Among them, the area of ​​the anode outlet II9' is larger than the area of ​​the anode outlet II9, and the ratio is 1.0-1.8; the area of ​​the cathode outlet II11' is larger than the area of ​​the cathode inlet II11, and the ratio is 1.2-2.2; the area of ​​the coolant outlet II11' is larger than the area of ​​the coolant inlet II11, and the ratio is 1.3-2.0. The asymmetric setting of the inlet and outlet can increase the pressure difference between the inlet and outlet in the flow channel, increase the flow rate of the reaction gas, and facilitate the discharge of the water and tail gas generated by the reaction.

[0036] The cathode flow field described above is formed outside the cathode plate 1: the cathode gas passes through cathode inlet I4 / cathode inlet II10, cathode inlet distribution area 6, cathode reaction area 7, cathode outlet distribution area 6', cathode outlet I4' / cathode outlet II10' in sequence.

[0037] The anode flow field described above is formed outside the anode plate 2: the anode gas passes through the anode inlet I3 / anode inlet II9, the anode inlet distribution area 12, the anode reaction area 13, the anode outlet distribution area 12', the anode outlet I3' / anode outlet II9' in sequence.

[0038] The coolant flow field formed inside the cathode plate 1 and the anode plate 2 described above: the coolant passes through the coolant inlet Ⅰ5 / coolant inlet Ⅱ11, the coolant reaction zone (inside the cathode reaction zone 7 and the anode reaction zone 13), and the coolant outlet Ⅰ5' / coolant outlet Ⅱ11' in sequence.

[0039] The cathode inlet distribution area 6 and the cathode outlet distribution area 6' are parallel flow channels, with an angle of 45°-60° (such as Figure 4 As shown), the width is 1-2mm, and the length can be adjusted according to the layout position. Such an arrangement makes the incoming cathode gas evenly distributed and reduces the flow resistance; the anode inlet distribution area 12 and the anode outlet distribution area 12' are both forked structures, which can be one or more combinations of 1-2, 1-3, 1-4, so that the anode gas is evenly distributed and the flow resistance is reduced.

[0040] The cathode inlet Ⅰ4 / cathode outlet Ⅰ4' / cathode inlet Ⅱ10 / cathode outlet Ⅱ10', anode inlet Ⅰ3 / anode inlet Ⅱ9 / anode outlet Ⅰ3' / anode outlet Ⅱ9', coolant inlet Ⅰ5 / coolant inlet Ⅱ11 / coolant outlet Ⅰ5' / coolant outlet Ⅱ11' are all provided with a fence-type support structure to ensure the connectivity of the common channel and the distribution area, so that the reaction gas and coolant can pass smoothly.

[0041] The cathode reaction zone 7 is composed of multiple groups of grooves and protrusions, extending in a wave shape. The anode reaction zone 13 is composed of multiple groups of grooves and protrusions, extending in a wave shape. The cathode reaction zone flow field 7 and the anode reaction zone flow field 13 have the same period, and the two are staggered; each period includes a groove and a ridge, forming a continuous and uninterrupted flow channel in the coolant flow field.

[0042] A cathode sealing glue line groove 8 is provided at the edge of the cathode plate 1, and an anode sealing glue line groove 14 is provided at the edge of the anode plate 2. After the bipolar plates are welded and formed, the sealing glue lines are bonded into the glue line grooves to meet the sealing requirements for bipolar plate assembly.

[0043] For easy installation, two positioning holes are provided at the diagonals of the bipolar plates, one is a round hole and the other is an oblong hole. The diagonal distribution can improve the installation accuracy, reduce the misalignment error when the bipolar plates are stacked, and avoid positioning over-constraint.

[0044] The bipolar plate is also provided with an inspection plug-in slot 15, and an inspection harness plug-in is installed later, which has the advantages of convenient installation, convenient maintenance, high reliability, etc.

[0045] The bipolar plate is also provided with a two-dimensional code identification area 16 for identifying information such as production batch number and date, so as to facilitate the tracing of production information later.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A proton exchange membrane fuel cell bipolar plate, consisting of a cathode plate and an anode plate, characterized in that: The cathode plate and the anode plate are formed by stamping a metal sheet, a cathode flow field is stamped out of the outer side of the cathode plate, and an anode flow field is stamped out of the outer side of the anode plate. The cathode plate and the anode plate are bonded together and formed into a whole by laser welding or bonding, and a closed coolant flow field is formed inside the cathode plate and the anode plate; the areas of the common channels of the cathode, anode and coolant inlet / outlet on the anode plate and the cathode plate are asymmetrically arranged; The cathode inlet distribution area and the cathode outlet distribution area on the cathode plate are parallel flow channels, and the flow channel angles are arranged at 45°-60°; The area of ​​the cathode outlet common channel is larger than the area of ​​the cathode inlet common channel; the area of ​​the anode outlet common channel is larger than the area of ​​the anode inlet common channel; the area of ​​the coolant outlet common channel is larger than the area of ​​the coolant inlet common channel; The area of ​​the cathode outlet common channel is larger than the area of ​​the cathode inlet common channel, and the ratio is 1.2-2.2; the area of ​​the anode outlet common channel is larger than the area of ​​the anode inlet common channel, and the ratio is 1.0-1.8; the area of ​​the coolant outlet common channel is larger than the area of ​​the coolant inlet common channel, and the ratio is 1.3-2.0; The anode inlet distribution area and the anode outlet distribution area on the anode plate are both bifurcated structures, which are one or more combinations of 1-to-2, 1-to-3, and 1-to-4; A fence-type support structure is provided at the cathode inlet / outlet, anode inlet / outlet, and coolant inlet / outlet; The cathode reaction area of ​​the cathode plate and the anode reaction area of ​​the anode plate are composed of multiple groups of grooves and protrusions, extending in a wave shape, and the flow field periods of the cathode reaction area and the anode reaction area are consistent, and the two are staggered; A cathode sealing glue line groove is provided at the edge of the cathode plate, and an anode sealing glue line groove is provided at the edge of the anode plate. After the bipolar plates are welded and formed, the glue lines are bonded into the glue line grooves to achieve sealed assembly of the bipolar plates.

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