A single cell and stack of a fuel cell

Abstract

This invention discloses a single cell and stack of a fuel cell. The single cell of the fuel cell includes a membrane electrode assembly (MEA) and a bipolar plate. The MEA has a reaction zone, and the bipolar plate has a gas flow field zone corresponding to the reaction zone. The MEA has a gas diffusion layer, which includes a base layer near the bipolar plate and a microporous layer disposed on the side of the base layer away from the bipolar plate, so that the reaction gas transported by the gas flow field zone sequentially passes through the base layer and the microporous layer into the MEA. The single cell is provided with a gas barrier portion sealing the edge of the reaction zone. The gas barrier portion is a sealing colloid formed by a fluid adhesive seeping into the pores of the base layer and the microporous layer and solidifying. The single cell and stack of the fuel cell provided by this invention optimize the gas distribution of the fuel cell and solve single-cell performance problems such as low voltage and inconsistency caused by poor gas input.

Description

Technical Field

[0001] This utility model relates to the field of fuel cell technology, and in particular to a single cell and stack of a fuel cell. Background Technology

[0002] A fuel cell is a device that converts chemical energy into electrical energy through a chemical reaction of reactant gases in the membrane electrode assembly (MEA) of a fuel cell stack. During the operation of the fuel cell stack, bipolar plates transfer the reactant gases through flow channels to the gas diffusion layer of the MEA, and then through the gas diffusion layer into the electrode for reaction. The amount of reactant gas entering the electrode directly affects the reaction efficiency of the stack. If the amount of reactant gas entering the electrode is insufficient or uneven, it can lead to problems such as low voltage or poor consistency within a single cell.

[0003] During gas transfer, the movement of gas through the bipolar plates into the gas diffusion layer is varied. Typically, most gas passes through the diffusion layer to reach the electrode, while some diffuses laterally along the diffusion layer, eventually flowing out from its edge and entering the sealed gap between the membrane electrode assembly (MEA) and the bipolar plates. This portion of gas entering the sealed gap forms bypass gas, which does not participate in the reaction and affects the reaction efficiency of the fuel cell unit.

[0004] Therefore, it is necessary to propose a technical solution to overcome the shortcomings of existing technologies. Utility Model Content

[0005] To overcome the shortcomings of the prior art, this invention proposes a single cell and stack for a fuel cell, optimizes the gas distribution of the fuel cell, and solves single-cell performance problems such as low voltage and inconsistency caused by poor gas input.

[0006] This utility model is achieved through the following technical solution: a single cell of a fuel cell, including a membrane electrode assembly (MEA) and a bipolar plate. The MEA has a reaction zone, and the bipolar plate has a gas flow field zone corresponding to the reaction zone. The MEA has a gas diffusion layer, which includes a base layer near the bipolar plate and a microporous layer disposed on the side of the base layer away from the bipolar plate, so that the reaction gas transported by the gas flow field zone passes sequentially through the base layer and the microporous layer into the MEA. The single cell is provided with a gas barrier portion that seals the edge of the reaction zone. The gas barrier portion is a sealing colloid formed by the fluid adhesive seeping into the pores of the base layer and the microporous layer and solidifying.

[0007] As a further improved technical solution, the average pore size of the substrate layer is greater than the average pore size of the microporous layer, and the thickness of the substrate layer is greater than the thickness of the microporous layer.

[0008] As a further improved technical solution, the substrate layer is a carbon paper layer.

[0009] As a further improved technical solution, the sealing colloid is cured from one of epoxy resin, UV-curable adhesive, pressure-sensitive adhesive, and silicone.

[0010] As a further improved technical solution, the width of the sealing colloid is 1.5~4mm.

[0011] As a further improved technical solution, the sealing colloid is configured such that a fluid adhesive carried by a release film is transferred to the substrate layer and the microporous layer and cured.

[0012] As a further improved technical solution, the sealing colloid is formed by hot pressing and curing a fluid adhesive.

[0013] As a further improved technical solution, the sealing colloid is configured to penetrate the substrate layer and the microporous layer in the thickness direction to contact one side of the bipolar plate.

[0014] As a further improved technical solution, the sealing colloid has a pure adhesive portion that protrudes beyond the edges of the substrate layer and the microporous layer.

[0015] This utility model is also achieved through the following technical solution: a fuel cell stack comprising multiple single cells as described above.

[0016] The present invention provides a single cell of a fuel cell, wherein the single cell is provided with a gas barrier portion that seals the edge of the reaction zone. The gas barrier portion is a sealing colloid formed by the infiltration of a fluid adhesive into the pores of the substrate layer and the microporous layer and solidification. This seals the reaction gas transmitted from the bipolar plate within the reaction zone, preventing the reaction gas from escaping from the edge of the gas diffusion layer. This optimizes the gas distribution of the fuel cell and solves performance problems such as low voltage and inconsistency in a single cell of the fuel cell caused by poor gas input. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a common single-cell structure of a fuel cell.

[0018] Figure 2 This is a top-side view of a single cell of the fuel cell of this utility model.

[0019] Figure 3 This is a partial schematic diagram of the single-cell layer structure of the fuel cell of this utility model.

[0020] Reference numerals: 1. Bipolar plate; 11. Gas channel; 2. Gas diffusion layer; 201. Sealing gap; 3. Sealing strip; 4. Gas barrier; 21. Substrate layer; 22. Microporous layer; R. Reaction zone. Detailed Implementation

[0021] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0023] This utility model relates to the field of fuel cell technology, specifically to a single cell of a fuel cell and a stack structure including the single cell. Figure 1 As shown, during fuel cell stack operation, the reactant gas is transferred from the gas channel 11 on the bipolar plate 1 to the membrane electrode assembly (MEA). The reactant gas then passes through the bipolar plate 1 to the gas diffusion layer 2. Typically, most of the gas passes through the gas diffusion layer 2 to reach the exchange membrane of the MEA. Simultaneously, a portion of the gas diffuses laterally along the gas diffusion layer 2, eventually flowing out from the edge of the gas diffusion layer 2 and entering the sealing gap 201 between the MEA and the bipolar plate 1. The sealing gap 201 is formed by a sealing strip 3 sandwiched between the MEA and the bipolar plate 1. The MEA corresponding to the gas channel 11 is the region where the reactant gas reacts, i.e., the reaction zone R. The portion of gas entering the sealing gap 201 between the MEA and the bipolar plate 1 forms bypass gas, does not participate in the reaction, and affects the reaction efficiency of the fuel cell unit.

[0024] This invention provides a single fuel cell and a stack containing the single cell, aiming to prevent reactant gases from escaping from the edge of the gas diffusion layer, optimize gas distribution in the fuel cell, and solve performance problems such as low voltage and inconsistency in the single cell caused by poor gas input. The technical solution of this invention will be described in detail below with reference to the accompanying drawings.

[0025] Please see Figure 2 and Figure 3As shown, a single cell of a fuel cell includes a membrane electrode assembly (MEA) and a bipolar plate 1. The MEA has a reaction zone, and the bipolar plate 1 has a gas flow field zone corresponding to the reaction zone. The MEA also has a gas diffusion layer 2. The gas diffusion layer 2 includes a base layer 21 near the bipolar plate 1 and a microporous layer 22 disposed on the side of the base layer 21 away from the bipolar plate 1, so that the reaction gas transported by the gas flow field zone sequentially passes through the base layer 21 and the microporous layer 22 into the MEA. The single cell is provided with a gas barrier portion 4 sealing the edge of the reaction zone. The gas barrier portion 4 is a sealing colloid formed by a fluid adhesive seeping into the pores of the base layer 21 and the microporous layer 22 and solidifying.

[0026] The fuel cell provided by this utility model has a gas barrier 4 at the edge of the reaction zone R. The gas barrier 4 is a sealing colloid formed by the infiltration and solidification of a fluid adhesive into the pores of the substrate layer 21 and the microporous layer 22. This prevents the reactant gas from escaping from the edge of the gas diffusion layer 2 and isolates the reactant gas transmitted from the bipolar plate 1 within the reaction zone. This optimizes the gas distribution of the fuel cell and solves performance problems such as low single-cell voltage and inconsistency caused by poor gas input.

[0027] like Figure 2 and Figure 3 As shown, the bipolar plate 1 includes several gas channels 11, the area where the gas channels 11 are located is the gas flow field region, and the area of ​​the membrane electrode directly opposite the gas flow field region is the reaction region. In one embodiment, the membrane electrode includes a gas diffusion layer 2, a catalyst layer, and a proton exchange membrane, which are sequentially arranged from the bipolar plate 1. If the bipolar plate 1 delivers anolyte gas, then the gas diffusion layer 2 and the catalyst layer are the anolyte gas diffusion layer and the anolyte catalyst layer; if the bipolar plate delivers catholyte gas, then the gas diffusion layer 2 and the catalyst layer are the catholyte gas diffusion layer and the catholyte catalyst layer. The gas diffusion layer 2 is located between the catalyst layer and the bipolar plate 1, and its function is to uniformly introduce the reaction gas delivered in the gas flow field region into the catalyst layer of the membrane electrode, while ensuring the effective discharge of reaction products.

[0028] Please see Figure 3As shown, the gas diffusion layer 2 adopts a double-layer composite structure, including a base layer 21 near the bipolar plate 1 and a microporous layer 22 disposed on the side of the base layer 21 away from the bipolar plate. The base layer 21, as the main supporting structure, needs to possess sufficient mechanical strength and air permeability. This invention preferably uses a carbon paper layer as the base layer 21. The carbon paper layer is woven from carbon fibers and has an internally interconnected three-dimensional porous structure. In this embodiment, the microporous layer 22 is formed on the surface of the base layer 21 through a coating process, and the average pore size of the base layer 21 is larger than the average pore size of the microporous layer 22. This pore size gradient design allows the reactant gas to maintain a large flow cross-section when passing through the base layer 21, reducing gas transport resistance. Upon entering the microporous layer 22, the refined pores create capillary action, promoting uniform gas distribution within the membrane electrode plane.

[0029] In the thickness direction, the thickness of the substrate layer 21 is greater than the thickness of the microporous layer 22. In some embodiments, the thickness of the substrate layer 21 is set to 150-300 μm, and the thickness of the microporous layer 22 is controlled to be 30-80 μm. This thickness configuration ensures the overall mechanical stability of the gas diffusion layer 2, while also enabling fine control of the gas flow field through the relatively thin microporous layer 22. When the reactive gas delivered by the bipolar plate 1 enters the gas flow field region, the gas sequentially penetrates the substrate layer 21 and the microporous layer 22, and finally reaches the catalyst layer of the membrane electrode to participate in the electrochemical reaction.

[0030] Please continue reading. Figure 2 and Figure 3 As shown, in this embodiment of the invention, a gas barrier 4 is provided at the edge of the reaction zone. This structure allows a fluid adhesive to penetrate into the pores of the substrate layer 21 and the microporous layer 22 and solidify to form a sealing colloid. The fluid adhesive is a fluid or semi-fluid medium with certain flow properties, which can penetrate into the substrate layer 21 and the microporous layer 22 by coating or injection. In this embodiment, a release film is used to transfer the fluid adhesive to the substrate layer 21 and the microporous layer 22. The fluid adhesive carried by the release film is transferred to the edge region of the gas diffusion layer 2, and a hot-pressing process is used to allow the adhesive to penetrate into the pore structure of the substrate layer 21 and the microporous layer 22 under pressure and solidify therein. The solidified sealing colloid forms complete penetration in the thickness direction of the substrate layer 21 and the microporous layer 22, and its edge forms close contact with the surface of the bipolar plate 1, thereby constructing a complete sealing barrier between the membrane electrode and the bipolar plate 1.

[0031] Specifically, firstly, sealing lines are applied to the release film. The position of the sealing lines is set according to the single-pool sealing area. The width of the sealing lines can be changed by applying different amounts of adhesive. Preferably, the width of the formed sealing adhesive is between 1.5 and 4 mm. For example, in this embodiment, the width of the sealing lines is set to 2 mm. Then, UV treatment is performed to adjust the viscosity of the adhesive so that it can better adapt to the pores of the gas diffusion layer 2, facilitating the adhesive to enter and fill the pores of the gas diffusion layer 2. The viscosity of the adhesive should not be too high to avoid it not being able to penetrate the gas diffusion layer 2, and at the same time, the viscosity of the adhesive should not be too low to avoid the adhesive flowing into the reaction zone. The process involves influencing the gas reaction; then, the release film coated with adhesive is bonded to the gas diffusion layer 2 and subjected to hot-press curing. Under pressure, the adhesive on the release film can fully penetrate into the microporous layer 22 and the base layer 21 of the gas diffusion layer 2, and is cured in the gas diffusion layer 2 under the action of temperature; finally, after the adhesive has cured to form a sealing colloid, the release film is peeled off. The release film is specially treated, such as having silicone oil on its surface to make it easy to separate from other substances. By controlling the separation speed and peeling angle when peeling off the release film, the surface of the gas diffusion layer 2 can be protected from damage, and the separation of the sealing colloid and the release film can be achieved.

[0032] The selection of materials for sealing colloids must consider both sealing performance and process adaptability. This invention preferably uses one of epoxy resin, UV-curable adhesive, pressure-sensitive adhesive, or silicone as the adhesive raw material. These materials, after curing, can all form a sealing structure with excellent airtightness and chemical stability. In particular, when using UV-curable adhesives, rapid curing can be achieved through ultraviolet light irradiation, significantly improving production efficiency; while epoxy adhesive systems allow for control of colloid hardness by adjusting the curing agent ratio, adapting to different working conditions.

[0033] In some embodiments, the width of the gas barrier portion 4 is set to 1.5-4 mm. This size range has been verified through flow field simulation and experiments, ensuring effective blocking of laterally diffused gases without excessively reducing the effective area of ​​the reaction zone due to excessive width. It is worth noting that the cured sealant completely penetrates the substrate layer 21 and the microporous layer 22 in the thickness direction, and its lower surface forms direct contact with the sealing surface of the bipolar plate 1. This structural feature effectively blocks the lateral diffusion path of gas from the edge of the gas diffusion layer 2 to the sealing gap between the membrane electrode and the bipolar plate 1. Simultaneously, in some embodiments, the sealant has a pure adhesive portion protruding beyond the edges of the substrate layer 21 and the microporous layer 22. That is, the edge of the sealant extends beyond the edges of the substrate layer 21 and the microporous layer 22 to form a pure adhesive portion. The portion of the sealing colloid that penetrates into the gas diffusion layer 2 is connected to the fiber structure in the gas diffusion layer 2, sealing the pores in the gas diffusion layer 2 and preventing the formation of sealing gaps. At the same time, the fiber structure also helps to retain the colloid and reduce its flow, so as to facilitate the formation of a sealing colloid with the required shape and structure. The sealing colloid also has a pure colloid portion located outside the edge of the gas diffusion layer 2. This pure colloid portion has no fiber structure, resulting in better gas sealing and further enhancing the edge sealing effect.

[0034] This invention also provides a fuel cell stack comprising multiple single cells as described above, i.e., the fuel cell stack of this invention is composed of multiple single cell structures stacked together. During the stack assembly process, the bipolar plates 1 and membrane electrode assemblies of adjacent single cells are arranged alternately, and the gas barrier 4 forms a continuous sealed structure between the layers. This design not only prevents bypass leakage of reactant gases but also avoids the local leakage problem caused by uneven contact pressure in traditional sealing strip structures.

[0035] As can be seen from the above description of the specific embodiments, the technical solution of this utility model, by constructing a sealing structure inside the gas diffusion layer 2, has significant advantages over the prior art: First, the formed sealing colloid is directly molded inside the gas diffusion layer 2, eliminating the need for additional sealing strips and simplifying the fuel cell stack assembly process; second, the three-dimensionally permeable sealing colloid structure can adapt to the microscopic unevenness of the bipolar plate surface, ensuring uniform pressure at all points of the sealing interface; finally, this structure avoids the aging and detachment problem caused by the difference in thermal expansion coefficients of traditional sealing strips, significantly improving the long-term operational reliability of the fuel cell stack. This utility model, through its innovative sealing process for the gas diffusion layer 2, achieves improved single-cell reaction efficiency and enhanced sealing reliability in fuel cells, providing an effective structural solution for the industrial application of fuel cell technology.

[0036] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any partial improvements or equivalent substitutions made based on the technical solution of this utility model shall fall within the scope defined by the claims of this utility model.

[0037] This utility model has been described through several specific embodiments. Those skilled in the art should understand that various modifications and equivalent substitutions can be made to this utility model without departing from its scope. Furthermore, various modifications can be made to this utility model for specific situations or circumstances without departing from its scope. Therefore, this utility model is not limited to the specific embodiments disclosed, but should include all embodiments falling within the scope of the claims of this utility model.

Claims

1. A single cell of a fuel cell, comprising a membrane electrode assembly (MEA) and a bipolar plate, wherein the MEA has a reaction zone and the bipolar plate has a gas flow field zone corresponding to the reaction zone, characterized in that, The membrane electrode has a gas diffusion layer, which includes a base layer near the bipolar plate and a microporous layer disposed on the side of the base layer away from the bipolar plate, so that the reaction gas transported by the gas flow field region passes through the base layer and the microporous layer sequentially into the membrane electrode. The single cell is provided with a gas barrier portion at the edge of the reaction zone, which is a sealing colloid formed by the fluid adhesive seeping into the pores of the base layer and the microporous layer and solidifying.

2. The single cell of a fuel cell as defined in claim 1, characterized by The average pore size of the substrate layer is greater than the average pore size of the microporous layer, and the thickness of the substrate layer is greater than the thickness of the microporous layer.

3. The single cell of a fuel cell as defined in claim 2, characterized by The base layer is a carbon paper layer.

4. The single cell of a fuel cell as defined in claim 1, characterized by The sealant is cured from one of epoxy resin, UV-curable adhesive, pressure-sensitive adhesive, or silicone.

5. The single cell of a fuel cell as defined in claim 1, characterized by The width of the sealant is 1.5~4mm.

6. The single cell of a fuel cell as defined in claim 1, characterized by The sealant is configured such that a fluid adhesive carried by a release film is transferred to the substrate layer and the microporous layer and cured.

7. The single cell of a fuel cell as defined in claim 6, characterized by The sealing colloid is formed by hot pressing and curing a fluid adhesive.

8. The single cell of a fuel cell as defined in claim 1, characterized by The sealing colloid is configured to penetrate the substrate layer and the microporous layer in the thickness direction to contact one side of the bipolar plate.

9. The single cell of a fuel cell as claimed in claim 1, characterized by The sealing colloid has a pure adhesive portion that protrudes beyond the edges of the base layer and the microporous layer.

10. A fuel cell stack, characterized by It includes multiple single pools as described in any one of claims 1 to 9.

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