Fuel cell bipolar plate sealing structure and sealing method

Abstract

The present invention relates to a fuel cell bipolar plate sealing structure used to seal between the anode plate, membrane electrode, and cathode plate. The sealing structure comprises an insulating varnish layer, an adhesive, and a sealing member. Both the insulating varnish layer and the adhesive are sprayed onto the anode or cathode plate. The insulating varnish layer is sprayed onto the plate edge area, and the adhesive is applied to the plate reaction area. The membrane electrode is secured to the plate via the adhesive, and the sealing member is located within the plate sealing groove. Compared with existing technologies, this invention offers advantages such as higher stack volumetric power density, simpler assembly, and reduced leakage risk.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell sealing, and in particular to a fuel cell bipolar plate sealing structure and a sealing method. Background Art

[0002] Fuel cells are a type of new energy battery with advantages such as low operating temperature, high specific power, and rapid startup. They have become a hot topic of research in the new energy field. The key components of fuel cells are the membrane electrode assembly (MEA) and bipolar plates. The bipolar plates consist of a cathode plate and an anode plate with a flow field. The MEA comprises a reaction zone and a supporting frame, placed between the anode and cathode plates. The reaction zone provides a platinum catalyst to support the electrochemical reaction, while the frame supports the reaction zone and isolates the anode and cathode plates to prevent short circuits.

[0003] Since the fuel cell contains both hydrogen and air as gas media and ethylene glycol as cooling media when it is working, in order to prevent leakage of the media and leakage between each other, it is necessary to seal between the MEA and the cathode and anode plates. The usual sealing method is to place an elastomeric seal on each side of the membrane electrode MEA, and then apply a certain pressure to compress and seal. Chinese patent publication number CN110571452A discloses a sealing gasket for fuel cells. The sealing method adopted is to place a seal on each side of the MEA and then compress it. This sealing form usually requires two seals for sealing, which is thick, resulting in a high height of the stack, affecting the power density, and inconvenient assembly. One side of the seal must be fixed with glue, otherwise it cannot be stacked and installed, and cannot be mass-produced. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a fuel cell stack sealing structure and sealing method with high stack volume power density, simpler assembly and low leakage risk.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A fuel cell bipolar plate sealing structure is used for sealing between an anode plate, a membrane electrode and a cathode plate. The sealing structure includes an insulating varnish layer, an adhesive and a sealing member. The insulating varnish layer and the adhesive are both sprayed on the anode plate or the cathode plate. The insulating varnish layer is sprayed on the edge area of ​​the plate. The adhesive is applied to the reaction area of ​​the plate. The membrane electrode is fixed to the plate by the adhesive. The sealing member is located in the sealing groove of the plate.

[0007] Preferably, the insulating paint layer is acrylic conformal paint.

[0008] Preferably, the adhesive is epoxy resin glue.

[0009] More preferably, the adhesive is applied on the anode plate by dispensing or screen printing.

[0010] Preferably, the sealing member is a silicone sealing ring.

[0011] More preferably, the number of the sealing member is one.

[0012] More preferably, the sealing member is sealed by compression sealing.

[0013] Preferably, the membrane electrode is a frameless membrane electrode or a narrow-frame membrane electrode; the frame length of the narrow-frame membrane electrode is 3 to 5 mm.

[0014] A sealing method for the fuel cell bipolar plate sealing structure includes the following steps:

[0015] Step 1: Select the plate that needs to be sprayed with insulating paint and adhesive;

[0016] Step 2: Spray an insulating paint layer on the edge of the plate;

[0017] Step 3: Apply adhesive to the reaction area of ​​the plate by dispensing or screen printing, and then bond the membrane electrode to the plate with the adhesive;

[0018] Step 4: Install the seal in the plate sealing groove and perform compression sealing.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. High volume power density of the battery stack: The bipolar plate sealing structure in the present invention uses only one seal for sealing, and the distance between the anode and cathode plates is significantly reduced; at the same time, the membrane electrode adopts a frameless or narrow frame design, which further reduces the weight of the battery stack and increases the volume power density of the battery stack.

[0021] 2. Easier assembly: The bipolar plate sealing structure of the present invention uses a sealing member for sealing, and the membrane electrode is directly bonded to the plate, which reduces the number of parts required for assembly and simplifies assembly.

[0022] 3. Low leakage risk: The membrane electrode in the bipolar plate sealing structure of the present invention adopts a frameless or narrow frame design, and the sealing surfaces that need to be sealed are reduced from four surfaces to two surfaces, which reduces the leakage risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of the anode plate in an embodiment of the present invention;

[0024] Figure 2 Schematic diagram of the structure of the cathode plate in an embodiment of the present invention;

[0025] Figure 3 2 is a cross-sectional view of the bipolar plate sealing structure in an embodiment of the present invention.

[0026] The numbers in the figure show:

[0027] 1. Anode plate, 2. Membrane electrode, 3. Cathode plate, 4. Insulating paint layer, 5. Adhesive, 6. Seal. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0029] The present invention relates to a fuel cell bipolar plate sealing structure and a sealing method for the sealing structure, and a specific embodiment is provided below.

[0030] A fuel cell bipolar plate sealing structure is used to seal between an anode plate 1, a membrane electrode 2, and a cathode plate 3. The sealing structure includes an insulating varnish layer 4, an adhesive 5, and a sealant 6. Both the insulating varnish layer 4 and the adhesive 5 are sprayed onto the anode plate 1 or the cathode plate 3. In this embodiment, the insulating varnish layer 4 and the adhesive 5 are sprayed onto the anode plate 1. The insulating varnish layer 4 is sprayed onto the edge area of ​​the anode plate, and the adhesive 5 is applied to the reaction area of ​​the anode plate. The membrane electrode 2 is fixed to the anode plate 1 by the adhesive 5. The sealant 6 is located in the sealing groove of the anode plate 1.

[0031] The insulating varnish layer 4 in this embodiment is used to prevent short circuits between the cathode and anode plates. It requires good adhesion to the anode plate 1, resistance to temperatures between -40°C and 90°C, resistance to ethylene glycol, and water, and excellent insulation. Therefore, the insulating varnish layer 4 selected in this embodiment is an acrylic conformal coating, specifically Dow Corning SE9176.

[0032] The adhesive 5 in this embodiment is required to cure at room temperature. Precipitates from the adhesive must not adversely affect the catalyst. It must also maintain good adhesion to the membrane electrode 2 frame and plates, withstand temperatures ranging from -40°C to 90°C, and be resistant to ethylene glycol and water. Therefore, the adhesive 5 selected for this embodiment is an epoxy resin adhesive, specifically 3M DP420. The adhesive 5 is applied to the anode plate 1 by dispensing or screen printing.

[0033] The sealing member 6 in this embodiment is a silicone sealing ring, one of which is used for compression sealing. The silicone sealing ring can be a Dow Corning RBB series or a Wacker RTV series sealing ring.

[0034] The membrane electrode 2 in this embodiment adopts a frameless or narrow-frame design. The frame length of the narrow-frame membrane electrode ranges from 3 to 5 mm. Both the frameless membrane electrode and the narrow-frame membrane electrode can be directly bonded to the anode plate 1 through the adhesive 5.

[0035] This embodiment also relates to a sealing method for the sealing structure, which specifically includes the following steps:

[0036] Step 1: Select the plate that needs to be sprayed with insulating paint and adhesive;

[0037] Step 2: Spray an insulating paint layer on the edge of the plate;

[0038] Step 3: Apply adhesive to the reaction area of ​​the plate by dispensing or screen printing, and then bond the membrane electrode to the plate with the adhesive;

[0039] Step 4: Install the seal in the plate sealing groove and perform compression sealing.

[0040] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A fuel cell bipolar plate sealing structure, used for sealing between an anode plate (1), a membrane electrode (2) and a cathode plate (3), characterized in that: The sealing structure comprises an insulating varnish layer (4), an adhesive (5) and a sealing member (6); the insulating varnish layer (4) and the adhesive (5) are both sprayed on the anode plate (1) or the cathode plate (3); the insulating varnish layer (4) is sprayed on the edge area of ​​the plate; the adhesive (5) is applied to the reaction area of ​​the plate; the membrane electrode (2) is fixed to the plate by the adhesive (5); and the sealing member (6) is located in the sealing groove of the plate; The membrane electrode (2) is a frameless membrane electrode or a narrow-frame membrane electrode; the frame length of the narrow-frame membrane electrode is 3 to 5 mm; The insulating paint layer (4) is acrylic triple-proof paint; The adhesive (5) is epoxy resin glue; The adhesive (5) is applied to the anode plate (1) by dispensing or silk-screening.

2. A fuel cell bipolar plate sealing structure according to claim 1, characterized in that: The sealing member (6) is a silicone sealing ring.

3. A fuel cell bipolar plate sealing structure according to claim 2, characterized in that: The number of the sealing member (6) is one.

4. A fuel cell bipolar plate sealing structure according to claim 2, characterized in that: The sealing member (6) is sealed by compression sealing.

5. A sealing method for the fuel cell bipolar plate sealing structure according to claim 1, characterized in that: The following steps are involved: Step 1: Select the plate to be sprayed with the insulating paint layer (4) and adhesive (5); Step 2: spraying an insulating paint layer (4) on the edge area of ​​the plate; Step 3: Apply adhesive (5) to the reaction area of ​​the plate by dispensing or screen printing, and then bond the membrane electrode (2) to the plate by the adhesive (5); Step 4: Install the seal (6) in the plate sealing groove and perform compression sealing.

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