Fluid guide assembly

Abstract

A fluid conducting assembly for a fuel cell comprises a channel structure (720) and a gas diffusion layer (5) disposed on the channel structure (720), the channel structure (720) defining flow field channels (72) extending from a first end of the channel structure (720) to an opposite second end thereof, and porous distributors (73) disposed at both ends of the channel structure (720) extending across the entire width of the channel structure (720).

Description

Technical Field

[0001] The present invention relates to a fluid guiding assembly, and more particularly to guiding gases and liquids in a fuel cell.

Background Art

[0002] Fuel cells are one of the major candidates to replace generators operating on fossil fuels and can be used in several applications, including mobile and stationary applications. One such fuel cell is a proton exchange membrane (PEM) fuel cell operating at 70-80 °C. Each cell in the stack assembly typically comprises an electrolyte, which is usually a thin film, a catalyst layer on the anode side, and a catalyst layer on the cathode side, and this assembly is called a membrane electrode assembly (MEA). A fuel, usually hydrogen, and an oxidant, usually air, pass through the layers, an electrochemical reaction occurs to generate electricity, and water is produced as a by-product. In most cases, there is a gas diffusion layer (GDL) made of porous carbon fiber sandwiched between the MEA and a flow field (FF) plate having specific flow channels for uniformly distributing the gas. The water generated in the catalyst layer passes through the GDL and reaches the gas channels, where it is pushed out of the cell. Phase change as well as water and heat management in fuel cells have been widely studied in the past few years, and several patents have been filed in this regard. However, issues such as simplification, cost reduction, and easy manufacturing remain. The limitations of the current state-of-the-art fuel cell technology can be explained using a simple example. Patent Document 1 relates to the design and production of a fuel cell stack for automotive applications (mainly) based on metal plates. On each cell having a cell pitch of about 1.1 mm, about 300 cm 2The operating area is under consideration. The thickness of each cell is mainly defined by the thickness of the plate. Therefore, it is defined by the constraints of press working technology. In order to provide more competitive products in the market, it is important to improve the "volume output density" of the stack and make it more compact. Since this is impossible with existing press working technology for metal plates and compression / injection molding for graphite plates, other production means should be found. Examples of such flow structures are disclosed in Patent Document 2 and Patent Document 3, for example.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a fluid guiding assembly that enables the production of thinner fuel cells. In addition, these fuel cells should have a simple design and be easy to manufacture.

Means for Solving the Problems

[0005] This problem is solved by a fluid guiding assembly having the features of claim 1. Further embodiments of the fluid guiding assembly, the flow field structure and the fuel cell, as well as the manufacturing method thereof, are defined by the features of the further claims.

[0006] The fluid guiding assembly for a fuel cell according to the present invention comprises a channel structure and a gas diffusion layer disposed on the channel structure. The channel structure defines a flow field channel extending from a first end of the channel structure to a second end on the opposite side. Porous distributors are disposed at both ends of the channel structure extending across the entire width from a first side in the horizontal direction of the channel structure to a second side in the opposite horizontal direction.

[0007] Using such a design, the thickness of the fluid guiding assembly can be reduced, and thus the thickness of the fuel cell using the fluid guiding assembly can be reduced. A thickness reduction of approximately 50% can be achieved, while at the same time the performance of the cell is improved. In addition, the gas diffusion and heat transfer rates of the fluid guiding assembly are significantly improved. Also, the production cost of such an assembly is further reduced, and thus the production cost of the fuel cell using such an assembly is also further reduced.

[0008] In one embodiment, a distributor having a porosity of 10% - 90% is formed as a single component. In a further embodiment, the porosity is 50% - 80%.

[0009] In one embodiment, the porosity varies across the width of the distributor, i.e., when the fluid guiding assembly is introduced into the fuel cell, the porosity in the vicinity of the corresponding manifold is lower than that further away from it. For example, when the manifold is disposed on one side in the horizontal direction, the porosity is lowest there and highest on the opposite side in the horizontal direction. When the manifold is disposed in the center, the porosity is highest on both sides in the horizontal direction and lowest in the center.

[0010] In one embodiment, the length of the distributor is 1% - 10% of the length of the flow field channel, i.e., the length of the channel structure.

[0011] In one embodiment, the length of the distributor is 0.1 mm - 20 mm. In a further embodiment, the length of the distributor is 1 mm - 10 mm.

[0012] In one embodiment, the height of the distributor is equal to the height of the channel structure.

[0013] In one embodiment, the height of the distributor is lower than the height of the channel structure.

[0014] In one embodiment, the height of the distributor is equal to the sum of the height of the diffusion layer and the height of the channel structure.

[0015] In one embodiment, the height of the distributor is higher than the height of the channel structure.

[0016] In one embodiment, the height of the distributor is 50 μm to 400 μm. In a further embodiment, the height of the distributor is 200 μm to 400 μm.

[0017] In one embodiment, the flow channel structure and the distributor are permanently connected to each other.

[0018] In one embodiment, the gas diffusion layer, the flow channel structure, and the distributor are permanently connected to each other. The permanent connection can be achieved by coating, pressing, or hot pressing.

[0019] In one embodiment, the distributor comprises at least one of the group consisting of an open pore foam, a hole pattern, and a slit pattern.

[0020] In one embodiment, the distributor comprises circular holes, elliptical holes, or angled holes.

[0021] In one embodiment, the distributor comprises straight slits, curved slits, or angled slits.

[0022] In one embodiment, the distributor is made of metal, plastic or resin, or a combination thereof.

[0023] In one embodiment, the channel structure comprises straight flow field channels, meandering flow field channels, or flow field channels combined with each other.

[0024] In one embodiment, the channel structure and the distributor are integrally formed as a single component.

[0025] The features of the foregoing embodiments of the fluid guiding assembly can be used in any combination as long as they do not conflict with each other.

[0026] The flow field structure according to the present invention comprises a fluid guiding assembly according to one of the foregoing embodiments and a separator plate having a recess for accommodating the fluid guiding assembly. The flow field structure further comprises a manifold and a distribution channel for supplying gas to the distributor at a first end of the channel structure and collecting gas from the distributor at a second end of the channel structure.

[0027] The fuel cell according to the present invention comprises at least one membrane electrode assembly reinforced by two flow field structures according to the foregoing embodiments.

[0028] In one embodiment, the fuel cell comprises two current collector plates and two backing plates, with one current collector plate disposed adjacent to each flow field structure and one backing plate disposed adjacent to each current collector plate.

[0029] In a further embodiment, the two backing plates are reinforced by clamp elements.

[0030] A method for manufacturing a fluid guiding assembly according to the present invention comprises - providing a channel structure; - providing porous distributors at both ends of the channel structure; - providing a gas diffusion layer on the channel structure. and includes.

[0031] In one embodiment, the method includes permanently connecting the channel structure and the two distributors to each other.

[0032] In one embodiment, this method includes permanently connecting a gas diffusion layer to the channel structure and two distributors simultaneously with, or after, the step of connecting the channel structure and the distributor.

[0033] In one embodiment, the step of permanently connecting includes pressing, or heating and pressing.

[0034] The functions of the foregoing embodiments of the manufacturing method can be used in any combination as long as they do not conflict with each other.

[0035] Embodiments of the present invention will be described in more detail below with reference to the drawings. These are for illustrative purposes only and should not be construed as limiting.

Brief Description of the Drawings

[0036]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 6

Figure 7A

Figure 7B

Figure 7C

Figure 7D

Figure 7E

Figure 7F

Figure 7G

Figure 7H

Mode for Carrying Out the Invention

[0037] Figure 1 shows a top view of a flow field plate according to the prior art. The bipolar plate 7, made of any material such as metal or graphite, comprises several gas / liquid inlet / outlet manifolds 90, 91, 92 arranged at the outer part of the plate. At the center of the cell having a specific flow field (FF) directly below, an activation region A having a catalyst layer is arranged. The flow field ensures a uniform and sufficient gas supply to the activation region A. There is a flow distribution channel (FDC) between the inlet manifold and the outlet manifold to guide the gas to be uniformly distributed to the flow field and the activation region. In a fuel cell, in order to uniformly distribute the gas through the catalyst layer, it is common to have a uniform gas flow field with respect to the activation region, regardless of the bipolar manufacturing method (either composite graphite or metal). In the stack assembly, inlet manifolds and outlet manifolds are connected to all cells for gas supply. After the gas / liquid enters the cell and before reaching the activation region, a uniform distribution inside the cell is required. Usually, this is done by the flow distribution channel 71 arranged between the activation region A and the corresponding inlet manifold 91. In a similar way, there is a special flow pattern between the activation region and the outlet manifold to prevent useless backpressure and flow turbulence on the cell. In order to obtain a uniform gas flow rate distribution, sufficient water management, and supply a sufficient amount of reactants to the catalyst layer, gas flow channels are designed on or in the channel structure. The gas flow channels guide the reactants to flow in a specific direction and assist in removing moisture from the cell. Depending on the material of the plate, various manufacturing methods for the flow channels or patterns are used. For example, when the plate / separator is made of a graphite composite material, injection molding, compression molding or machining is used. When the plate is made of a metal plate, among those used, press working is the most promising and cost-effective technology. For all single bipolar plate assemblies, usually two individual sheet metals are press worked, laser welded, and coated with a protective film (before or after press working). In some cases, laser welding is omitted and conventional sealing is used.One of the major drawbacks of the prior art design is the limitation in the potential for reducing the thickness of a single plate. This can directly affect the size of the assembled stack and thus can directly affect the volumetric output density. On the other hand, the manufacturable channel width and depth are limited by the constraints of sheet metal elongation or machining processes. The gas channels are separated from each other by ribs that contact the gas diffusion layer (GDL). The water generated by the electrochemical reaction passes through the GDL and finally enters the gas channels. One of the main constraints of plates manufactured by graphite or pressing techniques is that the width of the contact ribs (sometimes called "lands") may not be reduced to less than 1 - 2 mm. As a result, the ribs become one of the major sources of water accumulation in the cell, reducing the cell performance and increasing the corrosion rate on the plate. To overcome this problem, a porous medium is used as the gas flow channel. However, such a structure has the constraint that the direction of the gas flow is not controlled, and especially in the situation of dynamic load operation, the cell performance is limited and water accumulation increases in the dead zones (such as at the corners of the cell). As an alternative, when using thin wires in parallel to fabricate the gas channels, several other wires are attached perpendicularly to them to act as the gas diffusion layer (GDL) and form a mesh. In such a design, 50% of the activation area is blocked where the wires contact the activation area. Moreover, assembling and joining such a small number of wires to each other is very cumbersome and time-consuming, even if automated using fixtures. Welding in the case of metal wires or high-temperature fusion in the case of plastic wires is a very difficult task. Quality control of such an assembly is difficult, and there is a high possibility that some of the channels / holes will be blocked, resulting in hot spots on the membrane and damage. Moreover, another gas delivery mechanism is required to convey gas to the activation area and the mesh. When some wires contact each other at the edge of the assembly, the gas flow is blocked and the gas uniformity is impaired. In an alternative embodiment, a mesh fabric is used as the gas diffusion layer. In such a design, there are limitations in the uniform gas distribution within the activation area.Therefore, the diffusion of the gas entering and leaving the cell is also restricted, a large pressure drop is caused by the mesh structure, and moreover, it affects the capillary force. The conventional method of manufacturing the gas diffusion layer (GDL) is a combination of carbon fiber and a pore layer on the side where the GDL is in direct contact with the catalyst layer of the cell assembly. The GDLs of Freudenberg or Toray are some of the state-of-the-art in the market. Usually, the GDL is compressed between the flow channels of the bipolar plate and the membrane electrode assembly (MEA) on the anode side and the cathode side.

[0038] Figure 2 shows a top view of the flow field structure 7 according to the present invention, and Figure 3 shows a partial cross-sectional view of the flow field structure of Figure 2 along the cutting line XX. The structure of the present invention combines several components inside the fuel cell in a more compact and reliable way. The structure of the present invention comprises together a channel structure 720, a gas diffusion layer and a gas distributor 73 that are not comparable to the prior art. The structure of the present invention not only overcomes the unsolved problems regarding the prior art, but also significantly improves the performance of the fuel cell. At the same time, such a design simplifies the cell assembly, thus bringing about compactness and reliability, and also considerably reducing the cost in the production of the fuel cell. In the shown embodiment, in the center of the assembly, i.e., in the activation region A of the fuel cell, a channel structure 720 with flow field channels 72 is arranged. There are two individual distributors 73. Each is fixed to one end of the channel structure 720. The distributor 73 functions as mechanical support during the production process and distributes the gas uniformly before it enters the activation region A. Moreover, there is a thin layer acting as a gas diffusion layer 5 on the channel structure 720. This design has several functionalities and advantages. First, this design is very compact compared to existing concepts and is not so expensive to manufacture. Second, this design functions as a flow rectifier for the activation region A, i.e., it makes the gas flow rate distribution uniform before the gas enters the activation region A. Third, when the channel structure 720 is made of individual parts such as wires, this design functions as mechanical support and applies tension to the wires to hold them in place. Fourth, this design makes the overall cell assembly including the plates smaller and more compact.

[0039] As shown in Figure 3, the distributor 73 has no size and dimension constraints and can vary based on the size of the cell, the separator plate 70 and the activation region A. The length of the distributor 73 is preferably 1 to 30%, more preferably 1 to 10% of the length of the flow field channel 72, but is not limited thereto. For example, if the length of the flow field channel 72 is 100 mm, the preferred length of the distributor can be 1 to 10 mm.

[0040] The thickness of the distributor 73 is preferably close to or slightly greater than one of the thicknesses of the channel structure 720. Since the distributor 73 can act as a mechanical support and holder for the channel structure 720, there may be a need to make it slightly thicker so that the joint with the channel structure 720 can be placed at the top. For example, if the thickness or height of the channel structure 720 is 200 μm, the thickness or height of the distributor can vary between 200 and 400 μm, but is not limited thereto. With such a design, the cell assembly becomes more flexible, especially when the distributor 73 is in direct contact with the catalyst-coated membrane (CCM) or the sub-gasket or any other component of the cell assembly. With such a design, the plate, and thus the outer dimensions of the cell (activation region + sub-gasket around it), become smaller, in principle reducing the stack size and production cost. FIG. 2 shows the layout of a cell having a distributor 73 according to the present invention. Compared with the original plate design shown in FIG. 1, the length of the separator plate 70 is shortened. The main difference between the plate of FIG. 1 and the plate of FIG. 2 is that the activation region A and the gas inlet / outlet manifolds 90, 91, 92 remain the same, but in the concept according to the present invention, the region where the distributor is located may be considerably optimized and shorter. For example, the oxidant enters the cell from the oxidant manifold 91 and is distributed to the distribution channel 71 as shown by the arrow in the figure. Thereafter, the oxidant reaches the distributor 73, where the gas flow is adjusted and homogenized, and then enters the flow field channel 72 and the activation region A. The length of the distribution channel 71 is optimized based on the design and the shape dimensions of the cell. The distribution channel 71 should not be too long to prevent high backpressure from occurring. Similarly, if the distribution channel 71 is too small, like an assembled layer above, such as a catalyst-coated membrane, the sub-gasket may deform and the distribution channel 71 may become clogged. Alternatively, the distributor can extend over the entire length of the distribution channel between the channel structure 720 and the corresponding manifold 91. The design parameters can be adjusted by those skilled in the art.

[0041] Figures 4A to 4B show cross-sectional views of an embodiment of the dispenser 73 according to the present invention. The dispenser 73 can be manufactured from various materials such as metals, aluminum, titanium, plastics, thermoplastics, resins, or porous parts, but is not limited thereto. The structure of the dispenser is adjusted based on the materials used for its production. There are no restrictions on the design and manufacturing method of the dispenser. The dispenser can be manufactured, for example, from porous resin or metal or others. The porosity of the dispenser should be estimated based on the design and size of the cells, preferably 10 to 90%, more preferably 50 to 80%, but is not limited thereto. If the porosity is too high, the mechanical stability decreases, and if the porosity is too low, the pressure drop across the dispenser, and thus across the fuel cell, becomes very large, so these porosities are not recommended. If the dispenser is not manufactured from the porous material itself, other production techniques such as 3D printing or injection / compression molding, lamination, erosion, or other methods can be used. For example, the porosity can be provided by a plurality of pins 730 extending through the dispenser 73, or a plurality of slits 731 extending through the dispenser 73. In the embodiment shown in FIG. 4A, the pins 730 are uniformly distributed across the cross-section of the dispenser 73. In the embodiment shown in FIG. 4B, the meandering slits 731 are uniformly distributed across the width of the cross-section of the separator 73. The dispenser 73 can be used together with a separator plate 70 made of metal, graphite, or other materials. The material of the dispenser 73 and the material of the channel structure 720 do not necessarily have to be the same. For example, by introducing the dispenser according to the present invention into the channel between the channel structure and the corresponding manifold, the flow path of the conventional fuel cell shown in FIG. 1 can be reduced or eliminated.

[0042] Figures 5A to 5B show partial perspective views of embodiments of the flow field channel 72 in each channel structure 720. In the illustrated embodiments, the flow field channel 72 is manufactured by pressing a thin metal sheet. In this case, the channel structure 720 is integrally formed as a single part with the separator plate 70. Accordingly, the distributor 73 is adjacent to the flow channel structure 720 and the separator plate 70, respectively. In a fuel cell, fresh oxidant (mainly air) diffuses through the gas diffusion layer and reaches the catalyst layer. Water generated on the catalyst layer moves toward the channel by capillary force in the gas diffusion layer. Inside the channel, the condensed water and the oxidant are mixed, and the generated water is pushed out of the channel. Many things regarding the behavior of the fresh oxidant, the movement of water, and the mixing phenomenon occurring in the channel are explained by the gas velocity in the channel. The gas flow in a fuel cell is mainly laminar. However, various mixing mechanisms based on the Reynolds number can occur between the gas and the condensed water. For example, the gas / liquid mixing at a Reynolds number of 1000 is different from the mixing at a Reynolds number of less than 500. If the gas flow velocity is high, it helps to push out the condensed water from the flow field channel. However, if the gas flow velocity is high, due to the complex mixing effect, there is also a risk that fresh air will be hindered from reaching the activation region, especially toward the channel outlet side where water accumulates. To address this problem and improve water management in the gas channel, it is important to distinguish between conventional mixing and diffusive mixing. In diffusive mixing, the liquid and the gas remain separated from each other before and throughout the transition region. Diffusive mixing is directly related to the fluid flow, the Reynolds number, and the Prandtl number. Therefore, the dimensions of the flow field channel 72 and the gas diffusion layer 5 should be set such that the phenomena of conventional mixing and diffusive mixing are taken into account. Thus, the ratio of the Reynolds number to the Prandtl number should be, for example, from 0.01 to 1000, more preferably from 0.05 to 500, but is not limited thereto.

[0043] In the embodiment of FIG. 5B, several wires 720 are arranged at the same distance from each other to generate the flow field channel 72. The distance between two adjacent wires is preferably 10 to 1000 μm, more preferably 100 to 300 μm, but not limited thereto. The preferred cross-section of the wire is one of round, square or rectangular, but not limited thereto. In the case of a round wire, the preferred diameter is 10 to 500 μm, preferably 100 to 300 μm. In the case of a square wire, the preferred side length is 10 to 500 μm, preferably 100 to 300 μm, but not limited thereto. Similar structures can be fabricated using other methods such as laser cutting, but not limited thereto. The wire can be made of various materials without limitation as long as the material is conductive. Some examples of materials that can be used include stainless steel, aluminum, titanium, copper, or thermoplastic materials such as PET, PEN, epoxy resin, urethane resin, polyamide resin, acrylic resin, carbon, carbon fiber or others. Regardless of the material used, a corrosion-resistant protective coating may be applied to prevent corrosion. Specific materials that can be used include gold, silver, copper, aluminum, platinum ruthenium, and coatings such as DLC, CVD or PVD can be applied thereto. Moreover, when the wire is made of a non-conductive material such as a thermoplastic material, a conductive coating should be applied to function in the assembly. However, this may have lower conductivity than the wire made of the material. There is no limitation on the material used as the conductive coating. For example, carbon type materials combined with a binder such as PVDF or PTFE or conductive particles such as Au, Ni or palladium can be used, but not limited thereto.

[0044] FIG. 6 shows a cross-sectional view of a membrane electrode assembly reinforced by two flow field structures according to the present invention, which can be used in the fuel cell 1. The membrane electrode assembly includes a membrane 2 reinforced by an anode electrode layer 3 and a cathode electrode layer 4. The first flow field structure 6 and the second flow field structure 7 each include separator plates 60, 70, channel structures 620, 720, distributors 63, 73, and a gas diffusion layer 5 disposed in corresponding recesses in the corresponding flow field structures. The channel structures 620, 720 each include corresponding flow field channels 62, 72. In the illustrated embodiment, the flow field structures 6, 7 each include distribution channels 61, 71 that connect the distributors 63, 73 to corresponding manifolds 91. The gas diffusion layer 5 used in the present invention is thinner than a conventional gas diffusion layer, and a preferred thickness is 10 to 150 μm, more preferably 25 to 65 μm, but is not limited thereto. By introducing a gas diffusion layer between the channel structure 720 and the catalyst layers 3, 4, sufficient space should be obtained for gas and water to pass through without blocking the gas diffusion layer. Moreover, since the contact ribs between the layers are very narrow, water accumulation at the contact points is completely eliminated. The gas diffusion layer 5 used in the present invention serves as mechanical support for the channel structure 720, and the channel structure 720 serves as mechanical support for the gas diffusion layer 5. Since the structure forming the flow field channel 72 is very small and the gas diffusion layer 5 is thin, they support each other. As can be understood, handling and operating layers of 25 to 65 μm and flow channels having a thickness of about 200 μm is very cumbersome. However, the current structure provides a reliable means for achieving this. The gas diffusion layer can be made of any substrate as long as it has a porous structure for the diffusion of oxidant and fuel between the catalyst layers. The gas diffusion layer should also have excellent conductivity characteristics to reduce the resistance between the layers. There are several substrates that can be used as conductive particles. Some of the well-known state-of-the-art materials include carbon, carbon black, carbon powder, carbon particles, or carbon paper / carbon cloth or others. It is also preferred that there is an additional hydrophobic substrate in the mixture. The hydrophobic substrate acts as a binder in the mixture and maintains the structure after curing.Also, the hydrophobic matrix helps to push water towards the gas channels. Some of the state-of-the-art hydrophobic particulate materials that can be used are PVDF, PTFE or others from a similar group. There is no clear limit to the amount of binder in the mixture. However, the recommended mass percentage is preferably 5 - 80%, more preferably 10 - 30%, but not limited thereto. To improve conductivity, it is possible to add an additional substrate to the mixture. Some examples are gold, platinum, ruthenium or others from the same group. As previously stated, since the gas diffusion layer is thin, it is preferably manufactured together with the flow field channels. There are several methods that can be used to manufacture the gas diffusion layer. For example, the gas diffusion layer can be manufactured by touch coating, screen printing, 3D printing or other methods, where the composition and viscosity of the mixture should be adjusted for each mechanism used.

[0045] Figures 7A - 7H show a depiction of the manufacturing process of an embodiment of a fluid guiding assembly according to the present invention. One skilled in the art can understand that this is merely an example and that several other techniques can be proposed. Below, the steps necessary to manufacture a structure comprising a flow field channel in a channel structure, a gas diffusion layer and a distributor that can be directly used inside a cell assembly are described.

[0046] Step 1 - Figure 7A: To form the flow field channels 72 for a fuel cell, several wires are arranged side by side. The structure of the channels is not limited and can be parallel, serpentine, interdigitated, or a combination thereof.

[0047] Step 2 - Figure 7B: Fixtures are made so that the wires are accurately positioned and maintained in place. There are several methods to manufacture the fixtures, such as 3D printing, machining, or others.

[0048] Step 3 - Figure 7C: Once the wire is fixed and maintained under tension, two distributors 73 are placed and fixed at the ends of the wire, i.e., the inlet and outlet of the flow field channel 72.

[0049] Step 4: Depending on the materials used, several methods such as hot pressing can be used to fuse the components together. Thereby, the assembly is pressurized at a fixed temperature for a certain period of time.

[0050] Step 5: After fusing the components together, it is cooled to room temperature, and then the gas diffusion layer 5 is attached. There are several possibilities, for example, using a conventional gas diffusion layer 5, or applying a paste over the flow field channel 72 using screen printing or other techniques.

[0051] Step 6: After attaching the gas diffusion layer 5, the assembly is kept at room temperature, and quality control measures are implemented to confirm the accuracy and homogeneity of the layers and structures.

[0052] Step 7: The assembly is placed in an oven for curing. Depending on the materials used on the channel structure 720 and the gas diffusion layer 5, several options are available. For example, a conventional oven or an infrared oven or a UV dryer can be used. When using a paste as the gas diffusion layer 5, the structure is heated to, for example, about 350 °C to cure the mixture and the binder.

[0053] Step 8: After heating the assembly, it is taken out of the oven and cooled to room temperature.

[0054] This structure is ready for attachment to the cell assembly. The assembly used on the anode side and the assembly used on the cathode side can be similar or different. For example, the cathode-side structure may have larger flow channels to reduce the pressure drop, or may have separate gas diffusion layers for various applications.

[0055] As an example, to fabricate one cell assembly having an activation region of 50×50 mm 2 the following components are selected. For the distributors 63, 73, a resin-type material with a height of 2 mm, a length of 5 mm, a width of 50 mm, and a porosity of about 75% is prepared. For the channel structures 620, 720, carbon fiber wires with a diameter of 0.4 mm and a length of 55 mm are prepared and arranged at the same distance of 0.3 mm from each other. For the gas diffusion layer 5, carbon black powder, PTFE dispersion, and surfactant are mixed together, and the ratio of carbon black and PTFE is maintained at 80-20%. These components are assembled together using fixtures. On the channel structure, a gas diffusion layer paste is applied using a screen printing machine, and the assembly is placed in an oven at 350 °C for 15 minutes. For the second structure for the anode side of the cell, a similar procedure is repeated. As the separator, a flat graphite plate with a thickness of 4 mm compressed is used. In addition, for the assembly, a flat sealant made of EPDM is cut and prepared. The membrane electrode assembly is fabricated as follows. As the electrolyte, a Nafion membrane with a thickness of 0.15 mm is used. A mixture of platinum and carbon black using a Nafion solvent is sprayed on both sides of the membrane, 0.4 mg / cm 2 on the cathode side of the membrane and 0.04 mg / cm 2 on the anode side, respectively. All the layers are assembled in the order of, from bottom, graphite plate, gasket, structure 1, membrane electrode assembly, structure 2, gasket, graphite plate, etc. The assembly was successfully tested at about 75 °C using a stable voltage of 0.6 V and a current density of 1.6 A / cm 2 .

Description of Reference Numerals

[0056] 1 Fuel cell 2 Membrane 3 Anode electrode layer 4 Cathode electrode layer 5 Gas diffusion layer 6 First flow field structure 60 Separator plate 61 Distribution channel 62 Flow field channel 620 Channel structure 63 Distributor 7 Second flow field structure 70 Separator plate 71 Distribution channel 72 Flow field channel 720 Channel structure 73 Distributor 730 Hole 731 Slit 90 Fuel manifold 91 Oxidizer manifold 92 Refrigerant manifold A Activation region

Claims

1. A fluid guiding assembly for a fuel cell, comprising a channel structure (620, 720) and a gas diffusion layer (5) disposed on the channel structure (620, 720), the channel structure (620, 720) defining a flow field channel (62, 72) extending from a first end of the channel structure (620, 720) to a second end opposite the first end of the channel structure (620, 720), and a porous distributor (63, 73) extending across the entire width of both the first end and the second end opposite the first end of the channel structure (620, 720) is disposed at both the first end and the second end opposite the first end of the channel structure (620, 720), characterized in that the height of the distributor (63, 73) is equal to the sum of the height of the gas diffusion layer (5) and the height of the channel structure (620, 720).

2. The fluid guiding assembly according to claim 1, wherein the distributor (63, 73) is formed of a single part and has a porosity of 10% to 90%.

3. The fluid guiding assembly according to claim 1 or 2, wherein the porosity varies across the width of the distributor (63, 73).

4. The fluid guiding assembly according to any one of claims 1 to 3, wherein the length of the distributor (63, 73) is 1% to 10% of the length of the flow field channel (62, 72).

5. The fluid guiding assembly according to claim 4, wherein the length of the distributor (63, 73) is 0.1 mm to 20 mm.

6. The fluid guiding assembly according to any one of claims 1 to 5, wherein the height of the distributor (63, 73) is 50 μm to 400 μm.

7. The fluid guiding assembly according to any one of claims 1 to 6, wherein the flow channel structure (620, 720) and the distributor (63, 73) are permanently connected to each other.

8. The fluid guiding assembly according to any one of claims 1 to 6, wherein the gas diffusion layer (5), the flow channel structure (620, 720), and the distributor (63, 73) are permanently connected to each other.

9. The fluid guiding assembly according to any one of claims 1 to 8, wherein the distributor (63, 73) comprises at least one of a group consisting of an open pore foam, a hole pattern (730), and a slit pattern (731).

10. The fluid guiding assembly according to claim 9, wherein the distributor (63, 73) comprises circular, elliptical, or angled holes (730).

11. The fluid guiding assembly according to claim 9, wherein the distributor (63, 73) comprises linear, curved, or angled slits (731).

12. The fluid guiding assembly according to any one of claims 1 to 11, wherein the distributor (63, 73) is made of metal, plastic, or resin.

13. The fluid guiding assembly according to any one of claims 1 to 12, wherein the channel structure (620, 720) comprises linear, serpentine, or interdigitated flow field channels (62, 72).

14. The fluid guiding assembly according to any one of claims 7 to 13, wherein the channel structure (620, 720) and the distributor are integrally formed as a single part.

15. A flow field structure (6, 7) comprising the fluid guiding assembly according to any one of claims 1 to 14 and a separator plate (60, 70) having a recess for accommodating the fluid guiding assembly. manifolds (90, 91), and a distribution channel (61, 71) for supplying gas to the dispenser (63, 73) at the first end of the channel structure (620, 720) and for collecting gas from the dispenser (63, 73) at the second end of the channel structure (620, 720), and a flow field structure (6, 7) further comprising.

16. A fuel cell (1) comprising at least one membrane electrode assembly (2, 3) reinforced by the first flow field structure (6) and the second flow field structure (7) according to claim 15.

17. A fuel cell (1) comprising a first current collector plate and a second current collector plate and a first backing plate and a second backing plate, wherein the first current collector plate is disposed adjacent to the first flow field structure (6), the second current collector plate is disposed adjacent to the second flow field structure (7), the first backing plate is disposed adjacent to the first current collector plate, and the second backing plate is disposed adjacent to the second current collector plate. The fuel cell (1) according to claim 16.

18. A method for manufacturing a fluid guiding assembly, comprising: providing a channel structure (620, 720), the channel structure (620, 720) defining a flow field channel (62, 72) extending from a first end of the channel structure (620, 720) to a second end on the opposite side of the channel structure (620, 720); disposing porous dispensers (63, 73) extending across the entire width of both the first end and the second end on the opposite side of the channel structure (620, 720) at both the first end and the second end on the opposite side of the channel structure (620, 720); disposing a gas diffusion layer (5) on the channel structure (620, 720) and including A method in which the height of the distributor (63, 73) is equal to the sum of the height of the gas diffusion layer (5) and the height of the channel structure (620, 720).

19. The method according to claim 18, comprising the step of permanently connecting the channel structure (620, 720) and the two distributors (63, 73) to each other.

20. The method according to claim 19, comprising the step of permanently connecting the gas diffusion layer (5) to the channel structure (620, 720) and the two distributors (63, 73) simultaneously with or after the step of connecting the channel structure (620, 720) and the distributor (63, 73).

21. The method according to claim 19 or 20, wherein the step of permanently connecting includes pressing, or heating and pressing.

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