Flow field assembly for fuel cell and fuel cell

Abstract

A flow field assembly for a fuel cell includes a flow field plate and a sealing member. A sealing member is disposed on the first side of the flow field plate and defines at least one bypass channel. The at least one bypass channel is configured to partially divert the reaction fluid from the inlet port of the flow field plate into a selected region of the reaction zone to cause the diverted portion of the reaction fluid to mix with the undiverted portion of the reaction fluid in the selected region such that the diverted portion of the reaction fluid is less than the undiverted portion of the reaction fluid in the selected region than in the absence of the at least one bypass channel. And the distribution uniformity of the reaction fluid on the reaction area is improved. The utility model also provides a fuel cell unit comprising the flow field assembly. According to the flow field assembly provided by the invention, the distribution uniformity of the current density can be improved by improving the distribution uniformity of the reaction fluid on the reaction region, so that reliable and efficient operation of the fuel cell unit is ensured.

Description

Technical Field

[0001] This application relates generally to fuel cell technology, and more particularly to flow field components for fuel cell units and fuel cell units including such flow field components. Background Technology

[0002] Fuel cell systems that generate electricity through the electrochemical reaction of fuel and oxidant are increasingly widely used to provide power. Proton exchange membrane fuel cells (PEMFCs) are a widely used type of fuel cell. PEMFCs use hydrogen as fuel and oxygen as the oxidant. Typically, a membrane electrode assembly (MEA) is positioned between two flow field plates to form a fuel cell unit. The two flow field plates include the anode flow field and cathode flow field, respectively, for supplying the anode reaction fluid (i.e., hydrogen) and the cathode reaction fluid (i.e., oxygen or air) to the MEA, and are therefore referred to as the anode plate and cathode plate, respectively. A number of fuel cell units are stacked and combined along a stacking direction to meet electrical application requirements such as power, voltage, and current, thus forming a fuel cell stack.

[0003] like Figure 1 As shown, a conventional flow field plate 1 typically includes an inlet port 3 for receiving the reaction fluid, an outlet port 5 for discharging the reaction products, and a flow field 7 extending between the inlet port 3 and the outlet port 5. During operation of the fuel cell unit, the reaction fluid flows from the inlet port 3 through the flow field 7 to the outlet port 5, and is consumed by an electrochemical reaction as it flows through the reaction zone 9 of the flow field 7. The concentration of the reaction fluid in the reaction zone 9 gradually decreases along its flow direction (e.g., ...). Figure 1 (As indicated by the hollow arrow in the diagram), this results in uneven distribution of the reaction fluid in reaction zone 9. This leads to uneven current density in the fuel cell unit, thereby reducing the efficiency of the fuel cell unit.

[0004] Furthermore, because the reaction fluid enters the flow field 7 at a relatively high speed from inlet port 3, the portion of the proton exchange membrane of the MEA near inlet port 3 is excessively dried, resulting in a lower water content in this portion and thus reducing its proton conductivity. This leads to an increase in the overall high-frequency impedance (HRF) of the fuel cell unit, thereby reducing the efficiency of the fuel cell unit.

[0005] Therefore, there is an urgent need to improve the traditional flow field plate. Utility Model Content

[0006] The purpose of this application is to provide a flow field assembly for a fuel cell unit to overcome at least one of the defects in the prior art.

[0007] In one aspect, this application proposes a flow field assembly for a fuel cell unit. The flow field assembly includes a flow field plate and a sealing member. The flow field plate includes an inlet port for receiving reaction fluid, an outlet port for discharging reaction products, and a flow field extending on a first side of the flow field plate between the inlet port and the outlet port. The flow field includes an inlet distribution zone, a reaction zone, and an outlet collection zone sequentially arranged along a flow direction from the inlet port to the outlet port. The sealing member is disposed on the first side of the flow field plate and defines at least one bypass channel. The at least one bypass channel is configured to partially divert the reaction fluid from the inlet port to a selected region of the reaction zone so that the diverted portion of the reaction fluid mixes with the undiverted portion of the reaction fluid in the selected region, thereby improving the uniformity of the reaction fluid distribution in the reaction zone compared to the case without the at least one bypass channel.

[0008] In some embodiments, the sealing member is fixedly attached to the first side of the flow field plate.

[0009] In some embodiments, the sealing member is adhered to the first side of the flow field plate.

[0010] In some embodiments, the flow field plate is one of an anode plate and a cathode plate, and the fuel cell unit further includes the other of an anode plate and a cathode plate, as well as a membrane electrode assembly disposed between the anode plate and the cathode plate; a first side of the flow field plate is disposed facing the other of the anode plate and the cathode plate and the membrane electrode assembly; and a sealing member is disposed around the membrane electrode assembly between the anode plate and the cathode plate to provide a seal, and is also used to adhere between the anode plate and the cathode plate to maintain the anode plate and the cathode plate as an integral structure, such that the anode plate and the cathode plate hold the sealing member and the membrane electrode assembly therebetween.

[0011] In some embodiments, the reaction zone includes: a plurality of flow channels, each of the plurality of flow channels extending between the inlet distribution zone and the outlet collection zone; and at least one interconnecting channel located in the selected zone, each of the at least one interconnecting channel extending in a direction intersecting the flow direction to connect at least two of the plurality of flow channels to each other, and to directly connect at least one of the at least one bypass channel to receive the diverted portion.

[0012] In some embodiments, the flow field plate includes ridges defining the plurality of flow channels, adjacent flow channels being separated by ridges, and each of the interconnecting channels is formed by setting a portion of the ridge between adjacent flow channels to be shorter than the other portions of the ridge.

[0013] In some embodiments, the at least one interconnect channel is a plurality of interconnect channels, and the at least one bypass channel is one or two bypass channels, each bypass channel being directly connected to the plurality of interconnect channels, wherein each of the bypass channels includes a plurality of outlets, each of the plurality of outlets being aligned with an inlet of a corresponding one of the plurality of interconnect channels.

[0014] In some embodiments, the reaction zone is divided into an upper half near the inlet distribution zone and a lower half near the outlet collection zone, the selected area being located at or near the intersection of the upper half and the lower half, and the total flow capacity of the at least one bypass channel is configured such that, under the rated operating conditions of the fuel cell unit, the concentration of the reaction fluid in the upper half and the lower half is approximately equal.

[0015] In some embodiments, the inlet distribution area and / or the at least one bypass channel are configured to have adjustable flow capacity, enabling adjustment of the ratio of the diverted portion to the undiverted portion.

[0016] In some embodiments, each of the at least one bypass channel extends along the edge of the flow field plate.

[0017] In some embodiments, the flow field is a straight-channel flow field.

[0018] In some embodiments, the sealing member extends from a first surface to a second surface in the thickness direction, the first surface facing and being placed on the first side of the flow field plate, and each of the at least one bypass channel is recessed from the first surface into the sealing member at a first depth along the thickness direction, the first depth being less than the thickness of the sealing member.

[0019] In some embodiments, each of the at least one bypass channel has a constriction structure, the flow area of ​​which decreases and then increases in the flow direction from the inlet port to the selected region, thereby accelerating the flow of the diverted portion as it flows through the constriction structure.

[0020] In some embodiments, the flow field plate is an anode plate and the reaction fluid is hydrogen; or the flow field plate is a cathode plate and the reaction fluid is oxygen or air.

[0021] On the other hand, this application proposes a fuel cell unit. The fuel cell unit includes an anode plate, a cathode plate, and a membrane electrode assembly disposed between the anode plate and the cathode plate. At least one of the anode plate and the cathode plate is the aforementioned flow field assembly.

[0022] These techniques can be used alone or in any suitable combination. The foregoing summary is provided illustratively and is not intended to be restrictive.

[0023] The flow field assembly according to this application can ensure reliable and efficient operation of fuel cell units by improving the uniformity of the distribution of the reaction fluid in the reaction zone. Attached Figure Description

[0024] The above and other aspects of this application will be more thoroughly understood and appreciated below in conjunction with the accompanying drawings. It should be noted that the drawings are schematic only and not drawn to scale. Identical components are indicated by the same reference numerals in different drawings. Furthermore, for the sake of brevity, not all components or portions of the flow field plate, sealing member, flow field assembly, and fuel cell unit according to this application are shown or labeled in the drawings. It should be understood that the dimensions, scale relationships, and number of components or portions in the drawings are not intended to limit this application. In the drawings:

[0025] Figure 1 This is a schematic front view of a traditional flow field plate, in which the direction of the hollow arrows indicates the flow direction of the reactive fluid, and the size of the hollow arrows schematically indicates the concentration distribution of the reactive fluid in the reaction zone of the flow field plate.

[0026] Figure 2 This is a schematic front view of a flow field assembly including a flow field plate and a sealing member according to some embodiments of this application, wherein the direction of the hollow arrows indicates the flow direction of the reactive fluid, the size of the hollow arrows schematically indicates the concentration distribution of the reactive fluid in the reaction zone of the flow field plate, and the solid arrows schematically indicate the flow of the diverted portion of the reactive fluid.

[0027] Figure 3 Is with Figure 2 Same front view, but with specific annotations Figure 2 The structure of the flow field components;

[0028] Figure 4A yes Figure 2 A schematic front view of the sealing component;

[0029] Figure 4B yes Figure 2 A schematic front view of the flow field plate;

[0030] Figure 5 It includes Figure 2 A schematic cross-section of the fuel cell unit of the flow field component along the direction from the anode inlet port to the anode outlet port;

[0031] Figure 6 yes Figure 3A magnified view of the dashed area in the image;

[0032] Figure 7A It is along Figure 6 A cross-sectional view of line II in the diagram;

[0033] Figure 7B It is along Figure 6 A cross-sectional view of line II-II in the diagram;

[0034] Figure 8A and Figure 8B They are respectively with Figure 7A and Figure 7B A similar cross-sectional view, but showing one alternative type of sealing member;

[0035] Figure 9 schematically depicted Figure 2 The flow capacity relationship between the various channels of the flow field component; and

[0036] Figure 10 It schematically shows that it can be generated by Figure 2 The sealing component provides a bypass channel structure. Detailed Implementation

[0037] Some embodiments of this application are described in detail below with reference to the accompanying drawings. In the following embodiments, for ease of description of the flow field assembly for a fuel cell unit according to this application, a flow field assembly for a PEMFC fuel cell unit is used as an example. It should be understood that this example does not imply any limitation on this application, and the flow field assembly according to this application can also be used in other types of fuel cell systems. Furthermore, features in the various embodiments of this application can be combined with each other unless otherwise specified.

[0038] Figures 2 to 7B A flow field assembly 10 according to some embodiments of this application is schematically illustrated. The flow field assembly 10 is configured for a PEMFC fuel cell unit, for example... Figure 5 The fuel cell unit 20 shown.

[0039] like Figures 2 to 4B As shown, the flow field assembly 10 includes a flow field plate 100 and a sealing member 200 disposed on the flow field plate 100. The flow field plate 100, also referred to as a "partition," is substantially impermeable to the reaction fluid and reaction products. Figure 4B As best shown, the flow field plate 100 may be in a generally rectangular shape and includes an inlet port 103 for receiving the reaction fluid, an outlet port 105 for discharging the reaction products, and a flow field 107 extending between the inlet port 103 and the outlet port 105.

[0040] The specific configuration of the flow field assembly 10 is described below with reference to the example of the flow field plate 100 being used as an anode plate. Accordingly, the inlet port 103 is an anode inlet port for receiving the anode reaction fluid (here, hydrogen), the outlet port 105 is an anode outlet port for discharging the anode reaction products, and the flow field 107 is an anode flow field.

[0041] Figure 5 A schematic cross-section of the fuel cell unit 20, including the flow field assembly 10, taken along the direction from the anode inlet port (i.e., inlet port 103) to the anode outlet port (i.e., outlet port 105) is shown. Figure 5 As shown, the fuel cell unit 20 includes the flow field assembly 10 (wherein the flow field plate 100 serves as the anode plate), the cathode plate 30, and the membrane electrode assembly (MEA) 40. The flow field plate 100, MEA 40, and cathode plate 30 can be stacked sequentially along the stacking direction ZZ to form the fuel cell unit 20. Figures 2 to 4B In the diagram, the stacking direction ZZ is perpendicular to the plane of the paper in the view. MEA40 is disposed between the flow field plate 100 and the cathode plate 30 in the stacking direction ZZ. Although not specifically shown, MEA40 is envisioned to include a proton exchange membrane, a cathode diffusion layer and a cathode catalyst layer structure between the cathode plate 30 and the proton exchange membrane, and an anode diffusion layer and an anode catalyst layer structure between the flow field plate 100 and the proton exchange membrane. The cathode diffusion layer, cathode catalyst layer structure, anode diffusion layer, and anode catalyst layer structure are typically integrally formed with the proton exchange membrane. The cathode diffusion layer and anode diffusion layer respectively support the cathode catalyst layer structure and the anode catalyst layer structure, and transport the reaction fluid and reaction products.

[0042] The flow field plate 100 and the cathode plate 30 include an anode flow field (i.e., flow field 107) and a cathode flow field (not shown) for supplying the anode reaction fluid (here, hydrogen) and cathode reaction fluid (here, oxygen or air) to the MEA 40, respectively. An inlet port 103 extends through the flow field plate 100 along the stacking direction ZZ to receive the anode reaction fluid, and an outlet port 105 extends through the flow field plate 100 along the stacking direction ZZ to discharge the anode reaction fluid. Ports 33 and 35 are also formed on the cathode plate 30 at positions corresponding to the inlet port 103 and outlet port 105 of the flow field plate 100 in the stacking direction ZZ. Ports 33 and 35 are aligned with the inlet port 103 and outlet port 105 in the stacking direction ZZ, respectively, to together form the anode inlet channel and anode outlet channel of the fuel cell unit 20. When multiple fuel cell units 20 are stacked together along the stacking direction ZZ to form a fuel cell stack (not shown), the anode inlet channels of the multiple fuel cell units 20 can be aligned with each other in the stacking direction ZZ to form an anode inlet manifold, and the anode outlet channels of the multiple fuel cell units 20 can be aligned with each other in the stacking direction ZZ to form an anode outlet manifold. The anode inlet manifold can communicate with the anode input port of the fuel cell stack to receive the anode reaction fluid. The anode outlet manifold can communicate with the anode discharge port of the fuel cell stack to discharge the reaction products from the fuel cell stack. It is conceivable that the cathode inlet channel, cathode outlet channel, coolant inlet channel, and coolant outlet channel of the fuel cell unit 20, as well as the cathode inlet manifold, cathode outlet manifold, coolant inlet manifold, and coolant outlet manifold of the fuel cell stack, can be configured in a similar manner. Therefore, these similar contents will not be described in detail here.

[0043] The sealing component 200 can also be referred to as a "sealing frame". For example... Figure 2 , Figure 3 and Figure 5 As shown, the sealing member 200 can be disposed on the first side 100a of the flow field plate 100. For example... Figure 5As best illustrated, in the assembled fuel cell unit 20, a first side 100a of the flow field plate 100 is disposed facing the cathode plate 30 and the MEA 40. A sealing member 200 is disposed around the MEA 40 between the flow field plate 100 (i.e., the anode plate) and the cathode plate 30 to provide a seal. Specifically, the sealing member 200 provides a seal that isolates the internal space of the fuel cell unit 20 for the flow of reaction fluids and reaction products from the outside of the fuel cell unit 20. A portion of the sealing member 200 may be disposed around (e.g., in a direction perpendicular to the stacking direction ZZ) the anode flow field of the flow field plate 100 and the cathode flow field of the cathode plate 30, as well as the MEA 40, to isolate them from the outside of the fuel cell unit 20. Furthermore, another portion of the sealing member 200 may be disposed around (e.g., in a direction perpendicular to the stacking direction ZZ) the anode inlet channel and the anode outlet channel (and cathode inlet channel, cathode outlet channel, coolant inlet channel, and coolant outlet channel, not shown) of the fuel cell unit 20 to isolate them from the outside of the fuel cell unit 20.

[0044] like Figure 2 , Figure 3 and Figure 4B As shown, the flow field 107 can be a straight-channel flow field and is formed on a first side 100a of the flow field plate 100, extending between the inlet port 103 and the outlet port 105. The flow field 107 may include an inlet distribution zone 108, a reaction zone 109, and an outlet collection zone 110 arranged sequentially along the flow direction from the inlet port 103 to the outlet port 105. The reaction zone 109 includes a plurality of flow channels 109a, each of which extends between the inlet distribution zone 108 and the outlet collection zone 110. The inlet distribution zone 108 is located near and communicates with the inlet port 103 for receiving the reaction fluid from the inlet port 103 and for distributing the reaction fluid to the respective flow channels 109a. The outlet collection zone 110 is used to collect reaction products from the respective flow channels 109a and is located near and communicates with the outlet port 105 for discharging the reaction products to the outlet port 105.

[0045] The sealing member 200 defines at least one bypass channel 210 (two bypass channels 210 in the figure) on a first side 100a of the flow field plate 100. This at least one bypass channel 210 is configured to partially divert the reaction fluid from the inlet port 103 into a selected region of the reaction zone 109 so that the diverted portion of the reaction fluid mixes with the undiverted portion in that selected region, thereby improving the uniformity of the reaction fluid distribution in the reaction zone 109 compared to the absence of this at least one bypass channel 210. In other words, the at least one bypass channel 210 is configured to partially divert the reaction fluid from the inlet port 103 and introduce the diverted portion of the reaction fluid into the reaction zone 109 in such a selected region, allowing for improved uniformity of the reaction fluid distribution in the reaction zone 109. The at least one bypass channel 210 extends around a portion of the flow field 107 between the inlet port 103 and the selected area of ​​the reaction zone 109 to connect the inlet port 103 to the selected area. The selected area does not include the intersection of the reaction zone 109 and the inlet distribution zone 108, nor the intersection of the reaction zone 109 and the outlet collection zone 110, because introducing the diverted portion into the reaction zone 109 in these areas would not help improve the uniformity of the distribution of the reactive fluid in the reaction zone 109.

[0046] By partially diverting the reaction fluid from the inlet port 103 to a selected region of the reaction zone 109 through at least one bypass channel 210 defined by the sealing member 200, the uniformity of the reaction fluid distribution in the reaction zone 109 can be improved, thereby improving the uniformity of the current density of the fuel cell unit 20 utilizing the flow field assembly 10 and ensuring reliable and efficient operation of the fuel cell unit 20. Improving the uniformity of the reaction fluid distribution in the reaction zone 109 can mitigate or even prevent inconsistent aging of different parts of the MEA40 components (e.g., the upper half upstream and the lower half downstream of the proton exchange membrane along the flow direction from the inlet port 103 to the outlet port 105), thereby mitigating localized degradation of the MEA40 and reducing stress points, thus improving the durability of the fuel cell unit 20. Furthermore, by utilizing at least one bypass channel 210 defined by the sealing member 200 to partially divert the reaction fluid from the inlet port 103 to a selected region of the reaction zone 109, the velocity of the reaction fluid entering the flow field 7 from the inlet port 3 can be appropriately reduced. This prevents the portion of the proton exchange membrane of the MEA near the inlet port 3 from being excessively dried, thus ensuring that this portion has appropriate proton conductivity. This prevents an increase in the overall HRF of the fuel cell unit 20, thereby ensuring reliable and efficient operation of the fuel cell unit 20.

[0047] Furthermore, compared to forming bypass channels on the flow field plate 100 via stamping, providing bypass channels 210 using the sealing member 200 helps reduce the mold design and stamping labor required when manufacturing the flow field assembly 10, and improves the design and manufacturing flexibility of the flow field assembly 10. This makes the flow field assembly 10 easier to manufacture and reduces its manufacturing cost, thereby facilitating mass production of the flow field assembly 10. For example, the bypass channels 210 can be formed in the sealing member 200 via cutting or molding processes. As will be described in detail below, these processes enable the provision of bypass channels 210 with unique structures in the sealing member 200, thereby improving the performance of the flow field assembly 10, which is difficult or even impossible to form on the flow field plate 100 via stamping. Moreover, compared to forming bypass channels on the flow field plate 100 via stamping, providing bypass channels 210 using the sealing member 200 ensures that the strength of the flow field plate 100 is not affected. For example, as... Figure 2 and Figure 3 As shown, the bypass channel 210 can be arranged near the edge of the flow field plate 100. If the bypass channel is formed near the edge of the flow field plate 100 by a stamping process, it will adversely reduce the strength of the flow field plate 100 at its edge, thus making the flow field plate 100 prone to deformation.

[0048] In some embodiments, such as Figure 2 , Figure 3 , Figure 4B , Figure 6 and Figure 7B As shown, the reaction zone 109 of the flow field plate 100 includes at least one interconnecting channel 113 (four interconnecting channels 113 in the figure) located within the selected region. Each interconnecting channel 113 extends in a direction intersecting the flow direction from the inlet port 103 to the outlet port 105 to communicate with at least two of the plurality of flow channels 109a, and is directly connected to at least one of the at least one bypass channel 210 to receive a diverted portion of the reaction fluid. For example, each interconnecting channel 113 may extend laterally (e.g., perpendicularly or obliquely to) the flow direction. Exemplarily, as... Figure 2 and Figure 3 As shown, with the sealing member 200 providing a bypass channel 210 on each of the opposite sides of the reaction zone 109, each interconnecting channel 113 can extend transversely to the flow direction from one side of the reaction zone 109 to the other side, thereby connecting the plurality of flow channels 109a to each other, and each interconnecting channel 113 can be directly connected to each bypass channel 210 to receive the diverted portion of the reaction fluid. Figure 3 and Figure 6As best shown, each bypass channel 210 may extend along the edge of the flow field plate 100. Each bypass channel 210 may include a plurality of outlets 210b, each of which is aligned with and in direct communication with an inlet 113a of a corresponding one of the four interconnecting channels 113. With this configuration, each bypass channel 210 may introduce a diverted portion of the reactive fluid into each interconnecting channel 113. Furthermore, although not shown, it is contemplated that in some embodiments, each bypass channel 210 may include a plurality of inlets 210a, each of which is in direct communication with an inlet port 103, thereby facilitating the diversion of the reactive fluid from the inlet port 103 into the bypass channel 210.

[0049] like Figure 3 , Figure 6 , Figure 7A and Figure 7B As shown, a plurality of flow channels 109a in the reaction zone 109 of the flow field 107 of the flow field plate 100 are defined by ridges 115 formed on the flow field plate 100, and adjacent flow channels 109a are separated by ridges 115. The ridges 115 can be formed by methods known in the art (e.g., stamping processes). Each interconnecting channel 113 is formed by making a portion of the ridge 115 between adjacent flow channels 109a (in...) Figure 6 and Figure 7B (represented by "115a") is set higher than the other parts of the spine 115 (in Figure 6 , Figure 7A and Figure 7B The ridge 115 (represented by "115b") is formed by a short section 115a. The short section 115a of the ridge 115 forms a channel between multiple flow channels 109a to allow fluid to flow through it (e.g., Figure 7B (As indicated by the dashed arrow in the diagram). In this way, the diverted portion of the reaction fluid introduced into the interconnecting channel 113 by the inlets 113a at both ends of each interconnecting channel 113 via the two bypass channels 210 can flow into the corresponding flow channel 109a, mixing with the undiverted portion in the flow channel 109a, thereby increasing the concentration of the reaction fluid in the flow channel 109a, which was previously reduced due to consumption by the electrochemical reaction compared to when it entered the flow channel 109a from the inlet distribution region 108. Figure 1 Compared to the conventional flow field plate 1 shown, the flow field assembly 10 according to this application can improve the uniformity of the distribution of the reaction fluid in the reaction zone 109 (e.g., Figure 2 (as indicated by the hollow arrow in the diagram). It should be understood that the height of the short portion 115a of the ridge 115 can be zero, that is, there is no protruding ridge in that portion.

[0050] Although the flow field plate 100 is described above as including four interconnecting channels 113 and the sealing member 200 as including two bypass channels 210, it should be understood that the number of interconnecting channels 113 and bypass channels 210 is not limited thereto. For example, the sealing member 200 may include a single bypass channel 210 including a plurality of outlets 210b, each of which is aligned with and directly communicates with an inlet 113a of a corresponding one of the four interconnecting channels 113. That is, the aforementioned at least one interconnecting channel may be a plurality of interconnecting channels, and the aforementioned at least one bypass channel may be a single or two bypass channels. Each bypass channel is directly in communication with the plurality of interconnecting channels, wherein each bypass channel includes a plurality of outlets, each of which is aligned with and directly communicates with an inlet of a corresponding one of the plurality of interconnecting channels. As another example, the flow field plate 100 may include a single interconnecting channel 113, which may, for example, connect the plurality of flow channels 109a to each other at an intermediate position along the length of each of the plurality of flow channels 109a. In this case, the number of bypass channels 210 may, for example, be a single or two. For example, the sealing member 200 may also include more than two bypass channels 210, and the flow field plate 100 may include other numbers (e.g., two, three or more than four) of interconnecting channels 113.

[0051] In some embodiments, the reaction zone 109 of the flow field 107 of the flow field plate 100 may be divided into an upper half (not shown) near the inlet distribution zone 108 and a lower half (not shown) near the outlet collection zone 110. The upper and lower half of the reaction zone 109 may have the same volume. The aforementioned selected area may be located at or near the intersection of the upper and lower half, and the total flow capacity of the at least one bypass channel 210 of the sealing member 200 may be configured such that, under the rated operating conditions of the fuel cell unit 20, the concentration of the reactant fluid in the upper and lower half of the reaction zone 109 is substantially equal. As used herein, “flow capacity” refers to the ability of a channel to allow fluid to pass through it, which is generally characterized by the effective cross-sectional area of ​​the channel for the flow of fluid. Furthermore, as used herein, “substantially equal” means that two values ​​are close, for example, within ±0.5%, within ±1%, within ±2%, within ±3%, or within ±5%. Therefore, configuring the total flow capacity of the at least one bypass channel 210 such that the concentration of the reaction fluid in the upper and lower halves of the reaction zone 109 is approximately equal under the rated operating conditions of the fuel cell unit 20 means that the total effective cross-sectional area of ​​the at least one bypass channel 210 can be set based on the rated consumption of the reaction fluid under the rated operating conditions of the fuel cell unit 20. In other words, the specific structure of the at least one bypass channel 210 can be set based on the rated operating conditions of the fuel cell unit 20 to which the flow field assembly 10 will be used, in order to provide a corresponding total flow capacity.

[0052] The following is combined with Figure 9 An exemplary design method is described, in which the total flow capacity of the at least one bypass channel 210 is configured such that, under rated operating conditions of the fuel cell unit 20, the concentrations of the reaction fluid in the upper and lower halves of the reaction zone 109 are substantially equal. In the case where the flow field plate 100 is an anode plate, the reaction fluid is hydrogen. An ideal scenario is assumed where the hydrogen flow is reduced in volume due to consumption during the electrochemical reaction, and no other gases are generated on the anode side or received from the cathode side that increase the volume of the anode-side reaction fluid (or reaction products). Furthermore, as described above, the upper and lower halves of the reaction zone 109 can have the same volume. Therefore, on the anode side, the amount of hydrogen in the upper and lower halves of the reaction zone 109 can represent the concentration of hydrogen in the upper and lower halves of the reaction zone 109.

[0053] like Figure 9 As schematically shown, during operation of the fuel cell unit 20, excess hydrogen is supplied to the inlet port 103 of the flow field plate 100 to ensure that the fuel cell unit 20 has sufficient hydrogen available. The amount of hydrogen input from the inlet port 103 is Q. In Expressed by formula (1):

[0054] Q In =λ·Q act (1)

[0055] Among them, Q act This is the rated hydrogen consumption of the fuel cell unit 20 under rated operating conditions, expressed in units such as Nl / min; λ is the excess coefficient, with a value greater than 1, for example, it can be 1.3 to 1.5. The desired amount of hydrogen flowing through the upper and lower halves of the reaction zone 109 is Q. Us and Q Ds Q In Half of, that is:

[0056]

[0057] This will ensure that the hydrogen concentration is approximately the same in both the upper and lower halves of the region, i.e., uniformly distributed. In this case, the hydrogen consumption in both the upper and lower halves is half of the rated hydrogen consumption of the fuel cell unit 20 under rated operating conditions. Thus, the amount of hydrogen Q flowing through the lower half of the region... Ds for:

[0058]

[0059] Where Q1 and Q2 are the amounts of hydrogen flowing through the two bypass channels 210, respectively. The sum of Q1 and Q2 represents the total flow capacity of the two bypass channels 210. Substituting formula (2) into formula (3) yields:

[0060]

[0061] Therefore, the total flow capacity of the two bypass channels 210 can be configured to divert a first amount of hydrogen from the inlet port 103 to the lower half of the reaction zone 109 under rated operating conditions of the fuel cell unit 20 using the flow field assembly 10. This first amount is equal to half of the rated hydrogen consumption of the fuel cell unit 20 under rated operating conditions. In this way, the total flow capacity of the at least one bypass channel 210 of the sealing member 200 can be configured such that the concentration of hydrogen in the upper and lower half of the reaction zone 109 is approximately equal under rated operating conditions of the fuel cell unit 20.

[0062] It should be understood that the above design method is not limited to the case of two bypass channels 210, but is also suitable for the case of a single bypass channel or more than two bypass channels, as long as the total flow capacity of these bypass channels is configured to divert a first amount of hydrogen from the inlet port 103 to the lower half of the reaction zone 109 under the rated operating conditions of the fuel cell unit 20 using the flow field component 10, and this first amount is equal to half of the rated hydrogen consumption under the rated operating conditions of the fuel cell unit 20.

[0063] Although the flow field plate 100 is described herein as an anode plate and the reaction fluid as hydrogen, it should be understood that the flow field plate 100 can also be used as a cathode plate, and the reaction fluid accordingly can be air or oxygen. It is conceivable that, in the case of air as the reaction fluid, the overall flow capacity of the bypass channel 210 designed using the above method should take into account the concentration of oxygen in the air and the effects of other non-reactive gases in the air (e.g., nitrogen) on the concentration of oxygen in the upper and lower halves of the reaction zone 109.

[0064] In some embodiments, the inlet distribution zone 108 and / or the at least one bypass channel 210 are configured to have an adjustable flow capacity, enabling adjustment of the ratio of the diverted to the undiverted portion of the reaction fluid. For example, an adjustment mechanism such as a slider or a sliding baffle can be disposed in the inlet distribution zone 108 and / or the at least one bypass channel 210 and can slide therein (manually or automatically) to adjust the flow capacity of the inlet distribution zone 108 and / or the at least one bypass channel 210. This allows adjustment of the ratio of the diverted to the undiverted portion of the reaction fluid. In this way, the distribution of the reaction fluid in the reaction zone 109 can be controlled more precisely. It should be understood that the specific form of the adjustment mechanism is not limited to a slider or a sliding baffle, and other suitable forms are possible. It should also be understood that even if the total flow capacity of the at least one bypass channel has been set under the rated operating conditions of the fuel cell unit 20, the at least one bypass channel can still have an adjustable flow capacity to adapt to various operating condition changes.

[0065] In some embodiments, such as Figure 7A and Figure 7B As shown, the sealing member 200 extends from a first surface 201 to a second surface 202 in the thickness direction (i.e., the stacking direction ZZ). The first surface 201 faces and is placed on the first side 100a of the flow field plate 100. Each of the at least one bypass channel 210 is recessed from the first surface 201 into the sealing member 200 along the thickness direction to a first depth D1. The first depth D1 can be equal to the thickness T1 of the sealing member 200 (i.e., the dimension of the sealing member 200 between the first surface 201 and the second surface 202). That is, the bypass channel 210 extends through the sealing member 200 in the thickness direction. For example, the thickness T1 of the sealing member 200 can be from 0.15 mm to 0.3 mm, and correspondingly, the first depth D1 of the bypass channel 210 can also be from 0.15 mm to 0.3 mm.

[0066] In other embodiments, such as Figure 8A and Figure 8B As shown, the first depth D1 of each of the at least one bypass channel 210 can be less than the thickness T1 of the sealing member 200. That is, the bypass channel 210 does not extend through the sealing member 200 in the thickness direction. In other words, each bypass channel 210 is recessed into the sealing member 200 from the first surface 201 and has a groove with a closed bottom. This configuration helps to improve the sealing performance of the sealing member 200 at the bypass channel 210. For example, the thickness T1 of the sealing member 200 can be from 0.15 mm to 0.3 mm, and the first depth D1 of the bypass channel 210 can be less than the thickness T1 of the sealing member 200.

[0067] In some embodiments, such as Figures 7A to 8B As shown, the width W1 of each of the at least one bypass channel 210 can be from 0.5 mm to 2 mm. As used herein, the width W1 of the bypass channel 210 refers to the dimension of the main body portion of the bypass channel 210 in a direction perpendicular to its direction of extension (i.e., the direction in which the reactive fluid flows).

[0068] In some embodiments, such as Figure 10 As shown, each of at least one bypass channel 210 may have a constriction structure 211. The flow area of ​​the constriction structure 211 decreases and then increases in the flow direction from the inlet port 103 to the selected region, thereby accelerating the flow of the diverted portion of the reactive fluid as it flows through the constriction structure 211. In this document, unless otherwise stated, "flow area" refers to the effective cross-sectional area of ​​a passageway or section used for the flow of fluid. This constriction structure 211 can be positioned at a desired location within the bypass channel 210 to accelerate the flow of the reactive fluid. Using this constriction structure 211, the space occupied by the bypass channel 210 on the flow field plate 100 can be reduced, so that the placement of the bypass channel 210 does not significantly alter or change the shape of the flow field plate 100. Figure 10 The constricted structure 211 shown is difficult to form using conventional processes such as stamping and machining. Instead, by utilizing the sealing member 200, the bypass channel 210 with the constricted structure 211 can be easily and cost-effectively formed. It should be understood that the sealing member 200 also allows for the easy and cost-effective formation of other bypass channel structures or patterns that are difficult to form using conventional processes such as stamping and machining.

[0069] In some embodiments, such as Figure 2 , Figure 3 and Figure 5 As shown, the sealing member 200 can be fixedly attached to the first side 100a of the flow field plate 100. Fixedly attaching the sealing member 200 to the flow field plate 100 enables the flow field assembly 10 to be formed as a single, integral structure. As used herein, an integral structure means that the components are held together so that they can be moved together (e.g., moved to a designated location or position), installed (e.g., installed into the fuel cell unit 20), and removed (e.g., detached from the fuel cell unit 20).

[0070] The integrated flow field assembly 10 is easier to handle during the manufacture of the fuel cell unit 20, thereby improving the manufacturing efficiency of the fuel cell unit 20. Furthermore, the integrated fuel cell unit 20 significantly reduces assembly errors (such as misalignment and deformation) during manufacturing, thus improving the quality of the fuel cell unit 20. When some components of the fuel cell unit 20 are damaged or fail and need replacement, the integrated flow field assembly 10 is easier to disassemble, replace, and reassemble, thereby improving the maintenance efficiency of the fuel cell unit 20 and reducing its maintenance costs. Compared to the components of the fuel cell unit 20 in the prior art, which are held together by pressure, the integrated flow field assembly 10 has higher integration and reliability. Therefore, the flow field assembly 10 according to this application and the fuel cell unit 20 including such a flow field assembly 10 are easy to manufacture, assemble, and maintain, have high reliability and flexibility, and offer significant cost benefits.

[0071] In one of these embodiments, the sealing member 200 may be adhered to a first side 100a of the flow field plate 100 for fixed attachment. For example, the first surface 201 of the sealing member 200 may have an adhesive layer, and the sealing member 200 may be directly adhered to the flow field plate 100 via the adhesive layer. Exemplarily, the material of the main body portion of the sealing member 200 may be PEN (polyethylene naphthalate), PET (polyethylene terephthalate), or PI (polyimide), and the material of the adhesive layer may be acrylic resin, silicone sealant, epoxy resin sealant, or acrylic adhesive. Alternatively, the sealing member 200 may be formed from an adhesive film. That is, the sealing member 200 may first be manufactured as an adhesive film having a certain pattern (i.e., including bypass channels 210). Subsequently, the adhesive film may be arranged on the first side 100a of the flow field plate 100 to form the flow field assembly 10. The adhesive membrane can improve the arrangement efficiency of the sealing component 200, thereby improving the manufacturing efficiency of the flow field assembly 10. For example, the adhesive membrane can be made of epoxy resin sealant or acrylic adhesive. Specifically, the adhesive membrane can be initially supported and held by a release membrane, and can be moved from the release membrane to the flow field plate 100 during the arrangement of the adhesive membrane.

[0072] In one of these embodiments, such as Figure 5As shown, the sealing member 200 can be bonded between the flow field plate 100 (used here as an anode plate) and the cathode plate 30 to maintain the flow field plate 100 and the cathode plate 30 as a single structure, thereby holding the sealing member 200 and the MEA 40 therebetween. For example, the first surface 201 and the second surface 202 of the sealing member 200 can each have an adhesive layer, and the sealing member 200 is directly bonded to the flow field plate 100 and the cathode plate 30 through the adhesive layer. Alternatively, the sealing member 200 can be formed of an adhesive film, which can be bonded between the flow field plate 100 and the cathode plate 30 to maintain the flow field plate 100 and the cathode plate 30 as a single structure.

[0073] In this way, the entire fuel cell unit 20 (i.e., MEA40, flow field plate 100, sealing member 200, and cathode plate 30) can be formed as a single integrated structure, i.e., a monolithic structure. During the manufacture of the fuel cell stack, the fuel cell stack can be formed by first forming each fuel cell unit 20 as a single integrated structure and then stacking the individual fuel cell units 20 together. The integrated fuel cell unit 20 is easier to handle during the manufacture of the fuel cell stack, thereby improving the manufacturing efficiency of the fuel cell stack. Furthermore, the integrated fuel cell unit 20 can significantly reduce assembly errors (such as misalignment, deformation, etc.) during the manufacture of the fuel cell stack, thereby improving the quality of the fuel cell stack. When some components of the fuel cell unit 20 are damaged or fail and need to be replaced, the integrated fuel cell unit 20 is easier to disassemble, replace, and reassemble, thereby improving the maintenance efficiency of the fuel cell stack and reducing its maintenance costs. In addition, the integrated fuel cell unit 20 has higher integration and reliability. Moreover, the integrated fuel cell unit 20 allows for the flexible increase or decrease of the number of fuel cell units 20 in the fuel cell stack as needed, thereby increasing the flexibility of the fuel cell stack. Therefore, the fuel cell unit 20 according to this application and the fuel cell stack including such fuel cell unit 20 are easy to manufacture, assemble and maintain, have high reliability and flexibility, and have significant cost benefits.

[0074] Although the foregoing description describes the sealing member 200 being bonded between the flow field plate 100 and the cathode plate 30 to be fixedly attached to the flow field plate 100 and the cathode plate 30, thereby maintaining the flow field plate 100 and the cathode plate 30 as a single structure, it should be understood that the sealing member 200 can be fixedly attached to the flow field plate 100 and the cathode plate 30 by any other suitable means to maintain the flow field plate 100 and the cathode plate 30 as a single structure. For example, the sealing member 200 can be heat-fused or ultrasonically welded to the flow field plate 100 and the cathode plate 30. Alternatively, the sealing member 200 can be directly snapped onto the flow field plate 100 and the cathode plate 30 to achieve a reliable mechanical attachment and tight seal between the flow field plate 100 and the cathode plate 30. Yet another example is that the sealing member 200 can be fixedly attached to the flow field plate 100 and the cathode plate 30 by heat-fused staples. For example, the flow field plate 100 and the cathode plate 30 may each be perforated ZZ along the stacking direction, and a hot-melt pin may extend through the hole and be hot-melted and fixed in place to securely attach the sealing member 200 to the flow field plate 100 and the cathode plate 30.

[0075] Although the description herein depicts the sealing member 200 being fixedly attached to the flow field plate 100 and the cathode plate 30 to hold the flow field plate 100 and the cathode plate 30 as a single structure, it should be understood that in other embodiments, the components of the fuel cell unit 20, namely the MEA 40, the flow field plate 100, the sealing member 200 and the cathode plate 30, can be held together by pressure (by stack clamps).

[0076] In some embodiments, such as Figure 4A and Figure 4B As shown, the flow channels in the inlet distribution area 108 and the outlet collection area 110 of the flow field plate 100 can be defined by the sealing member 200. It should be understood that this application is not limited thereto, and in other embodiments, the flow channels in the inlet distribution area 108 and the outlet collection area 110 of the flow field plate 100 can be formed by stamping the flow field plate 100.

[0077] Although the structure on the side of the flow field plate 100 opposite to the first side 100a is not shown and specifically described here, it is conceivable that a coolant flow field can be formed on that side (e.g., by the same stamping process that forms the flow field 107).

[0078] Although the configuration of the flow field assembly 10 is described herein as an example of the flow field plate 100 being used as an anode plate, it should be understood that in other embodiments, the flow field plate 100 may also be used as a cathode plate. In this case, the reaction fluid flowing in the flow field assembly 10 is oxygen or air.

[0079] That is, the flow field plate 100 can be one of an anode plate and a cathode plate, and the fuel cell unit 20 also includes the other of an anode plate and a cathode plate, as well as an MEA 40 disposed between the anode plate and the cathode plate. A first side 100a of the flow field plate 100 is disposed facing the other of the anode plate and cathode plate and the MEA 40. A sealing member 200 is used to provide a seal around the MEA 40 between the anode plate and the cathode plate. In some embodiments, the sealing member 200 can be fixedly attached (e.g., bonded) between the anode plate and the cathode plate to maintain the anode plate and the cathode plate as an integral structure, such that the anode plate and the cathode plate hold the sealing member 200 and the MEA 40 therebetween.

[0080] In some embodiments, at least one of the anode plate and cathode plate of the fuel cell unit 20 may be a flow field assembly 10. When both the anode plate and cathode plate of the fuel cell unit 20 are flow field assemblies 10, the sealing members 200 of the two flow field assemblies 10 may abut or be fixed (e.g., bonded) together to provide a seal.

[0081] Furthermore, although the configuration of the flow field plate 100 and the cathode plate 30 has been described herein using a monopolar plate as an example, it should be understood that in other embodiments, the flow field plate 100 and the cathode plate 30 may also be bipolar plates, and the same applies to the fuel cell unit 20 of this application. Therefore, in this application, bipolar plates and monopolar plates can be summarized as flow field plates.

[0082] It should also be understood that although the configuration of the flow field component 10 has been described herein as a straight-channel flow field 107, it should be understood that in other embodiments, the flow field 107 may also present other suitable flow field configurations, such as serpentine flow field configurations, 3D flow field configurations, etc.

[0083] In this application, the terms "first," "second," etc., are used only to distinguish one component, pipeline, or mode from another component, pipeline, or mode, but these components, pipelines, and modes should not be limited by such terms.

[0084] The present application has been described in detail above with reference to specific embodiments. Obviously, the above description and the embodiments shown in the accompanying drawings should be understood as exemplary and not as limiting the present application. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and such modifications or alterations do not depart from the scope of the present application.

Claims

1. A flow field assembly (10) for a fuel cell unit (20), characterized in that, The flow field component includes: A flow field plate (100) includes an inlet port (103) for receiving reaction fluid, an outlet port (105) for discharging reaction products, and a flow field (107) extending on a first side (100a) of the flow field plate between the inlet port and the outlet port, the flow field including an inlet distribution zone (108), a reaction zone (109), and an outlet collection zone (110) sequentially arranged along the flow direction from the inlet port to the outlet port; and A sealing member (200) is disposed on the first side of the flow field plate and defines at least one bypass channel (210), the at least one bypass channel being configured to partially divert the reaction fluid from the inlet port to a selected region of the reaction zone so that the diverted portion of the reaction fluid mixes with the undiverted portion of the reaction fluid in the selected region, thereby improving the uniformity of the distribution of the reaction fluid in the reaction zone compared to the case without the at least one bypass channel.

2. The flow field component according to claim 1, characterized in that, The sealing member is fixedly attached to the first side of the flow field plate.

3. The flow field component according to claim 2, characterized in that, The sealing member is bonded to the first side of the flow field plate.

4. The flow field component according to claim 3, characterized in that: The flow field plate is one of the anode plate and the cathode plate, and the fuel cell unit also includes the other of the anode plate and the cathode plate, as well as a membrane electrode assembly (40) disposed between the anode plate and the cathode plate; The first side of the flow field plate is configured to face the other of the anode plate and the cathode plate, and the membrane electrode assembly; and The sealing member is disposed around the membrane electrode assembly between the anode plate and the cathode plate to provide a seal, and is also used to adhere between the anode plate and the cathode plate to maintain the anode plate and the cathode plate as an integral structure, such that the anode plate and the cathode plate hold the sealing member and the membrane electrode assembly therebetween.

5. The flow field component according to any one of claims 1 to 4, characterized in that, The reaction zone includes: A plurality of flow channels (109a), each of which extends between the inlet distribution area and the outlet collection area; and At least one interconnecting channel (113) located in the selected area, each of the at least one interconnecting channel extending in a direction intersecting the flow direction to connect at least two of the plurality of flow channels to each other, and directly connected to at least one of the at least one bypass channel to receive the diverted portion.

6. The flow field component according to claim 5, characterized in that, The flow field plate includes ridges (115) defining the plurality of flow channels, adjacent flow channels being separated by the ridges, and each of the interconnecting channels being formed by setting a portion (115a) of the ridge between adjacent flow channels to be shorter than the other portions (115b) of the ridge.

7. The flow field component according to claim 5, characterized in that, The at least one interconnect channel is a plurality of interconnect channels, and the at least one bypass channel is one or two bypass channels, each bypass channel being directly connected to the plurality of interconnect channels, wherein each of the bypass channels includes a plurality of outlets (210b), each of the plurality of outlets being aligned with an inlet (113a) of a corresponding one of the plurality of interconnect channels.

8. The flow field assembly according to any one of claims 1 to 4 and 6 to 7, characterized in that, The reaction zone is divided into an upper half near the inlet distribution zone and a lower half near the outlet collection zone. The selected area is located at or near the intersection of the upper half and the lower half. The total flow capacity of the at least one bypass channel is configured such that, under the rated operating conditions of the fuel cell unit, the concentration of the reaction fluid in the upper half and the lower half is approximately equal.

9. The flow field assembly according to any one of claims 1 to 4 and 6 to 7, characterized in that: The inlet distribution area and / or the at least one bypass channel are configured to have adjustable flow capacity, enabling adjustment of the ratio of the diverted portion to the undiverted portion; and / or Each of the at least one bypass channel extends along the edge of the flow field plate; and / or The flow field is a straight-channel flow field; and / or The sealing member extends from a first surface (201) to a second surface (202) in the thickness direction (ZZ), the first surface facing and being mounted on the first side of the flow field plate, each of the at least one bypass channel being recessed from the first surface into the sealing member at a first depth (D1) along the thickness direction, the first depth being less than the thickness (T1) of the sealing member; and / or Each of the at least one bypass channel has a constriction structure (211) whose flow area decreases and then increases in the flow direction from the inlet port to the selected region, thereby accelerating the flow of the diverted portion as it flows through the constriction structure.

10. The flow field assembly according to any one of claims 1 to 4 and 6 to 7, characterized in that: The flow field plate is an anode plate, and the reaction fluid is hydrogen gas; or The flow field plate is a cathode plate, and the reaction fluid is oxygen or air.

11. A fuel cell unit (20), the fuel cell unit comprising an anode plate, a cathode plate, and a membrane electrode assembly (40) disposed between the anode plate and the cathode plate, characterized in that, At least one of the anode plate and the cathode plate is a flow field assembly (10) according to any one of claims 1 to 10.

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