A gas diffusion layer carbon paper substrate having a gas flow channel and a method of making the same

Abstract

The application provides a gas diffusion layer carbon paper substrate with a gas flow channel and a preparation method thereof, and comprises the following steps: uniformly mixing and dispersing resin, conductive material and solvent according to a certain proportion to prepare a sizing liquid; coating the prepared sizing liquid on a carbon paper base paper and drying; curing and forming the treated carbon paper base paper by using a specific mold; placing the cured carbon paper base paper in a high-temperature furnace for high-temperature densification treatment; placing the densified carbon paper base paper in a high-temperature furnace for graphitization treatment; and cooling after the graphitization treatment to obtain the gas diffusion layer carbon paper substrate with one side having a gas flow channel. The application constructs the gas diffusion layer carbon paper substrate with a flow channel, integrates a gas and liquid transmission flow channel, simplifies the flow channel etching process on a bipolar plate, reduces the cost, and the porous carbon paper material is arranged at the groove and ridge of the flow channel, and the porous structure enhances the liquid and gas transmission capacity of the flow channel.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, specifically relating to a gas diffusion layer carbon paper substrate with gas flow channels and its preparation method. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) offer advantages such as high energy conversion efficiency, continuous power supply, high stability, and environmental friendliness. They primarily consist of bipolar plates, a gas diffusion layer, a catalyst layer, and a proton exchange membrane. In existing structures, the flow channels are generally integrated onto the bipolar plates. The gas diffusion layer typically comprises a substrate layer and a microporous layer, with the substrate layer usually made of porous carbon materials such as carbon paper or carbon cloth. Under assembly pressure, the bipolar plates and the gas diffusion layer achieve interfacial contact.

[0003] Carbon paper is the main material of the gas diffusion layer in proton exchange membrane fuel cells. It supports the catalyst and provides gas, electron, and drainage channels for electrode reactions, making it one of the key components affecting electrode performance. As a gas diffusion layer material, carbon paper should possess a uniform porous structure, good strength, excellent electrical and thermal conductivity, and good chemical and thermal stability.

[0004] In existing technologies, flow channels are etched onto bipolar plates to facilitate gas-liquid transport. However, this method results in dense structures in the flow channel grooves and ridges of the bipolar plate, limiting the vertical gas-liquid transport capacity. Furthermore, the flow channel etching process increases the manufacturing cost and complexity of the bipolar plate. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a carbon paper substrate with a gas diffusion layer and its preparation method. This invention prepares a carbon paper substrate with a gas diffusion layer, which integrates gas-liquid transport channels, simplifies the etching process of the channels on the bipolar plate, reduces costs, and enhances the liquid-gas transport capacity of the channels through the porous structure of the porous carbon paper material at the grooves and ridges of the channels.

[0006] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is as follows: In a first aspect, embodiments of the present invention provide a method for preparing a carbon paper substrate with a gas diffusion layer having gas flow channels, comprising the following steps: (1) Preparation of adhesive solution: The resin, conductive material and solvent are mixed and dispersed evenly in a certain proportion to prepare an impregnation solution; (2) Coating of carbon paper base paper with adhesive solution: The adhesive solution prepared in step (1) is coated onto the carbon paper base paper and dried; (3) Thermosetting of adhesive paper: The carbon paper base paper obtained in step (2) is cured and shaped using a specific mold. The curing temperature is 140-200℃, the pressure is 0.1-10MPa, and the curing time is 1-20min. (4) Densification: The carbon paper base paper cured in step (3) is placed in a high-temperature furnace for high-temperature densification treatment; (5) Graphitization treatment: The carbon paper base paper after the densification treatment in step (4) is placed in a high-temperature furnace for graphitization treatment; (6) After the graphitization treatment in step (5) is cooled, a carbon paper substrate with a gas diffusion layer having a gas flow channel on one side is obtained.

[0007] Further, the resin mentioned in step (1) includes one or more of phenolic resin, epoxy resin, polyimide resin, and epoxy acrylate resin.

[0008] Furthermore, the conductive material mentioned in step (1) includes one or more of graphite powder, carbon powder, carbon nanotubes, and conductive carbon black.

[0009] Further, the solvent mentioned in step (1) includes one or more of water, alcohols, lipids, ethers, and ketones.

[0010] Further, the mass ratio of resin, solvent and conductive material in the impregnation solution in step (1) is 30-60:20-69:1-20.

[0011] Furthermore, the basis weight of the carbon paper base paper mentioned in step (2) is 10-100 g / m³. 2 The drying temperature is 65-95℃, the drying time is 10-60 minutes, and the amount of resin after drying is 100%-200% of the weight of the original paper.

[0012] Furthermore, in step (3), a high-temperature press is used for curing and molding. The high-temperature press is a press including a flat plate press or a roller press. In the flat plate press, one of the upper and lower plates has a groove structure, and in the roller press, one of the two pairs of rollers has a groove structure.

[0013] Furthermore, the high-temperature densification mentioned in step (4) includes densification in a vapor deposition furnace or secondary densification in a vacuum impregnation furnace; When using a vapor deposition furnace for densification, the furnace temperature is 500~1800℃, the pressure is -0.1MPa-2MPa, the mixed atmosphere is a mixture of carbon-containing gas and inert gas, the volume percentage of carbon-containing gas in the mixed atmosphere is 10%-90%, and the processing time is 0.1-2h. When using a vacuum impregnation oven for secondary sizing, the temperature for secondary sizing in the vacuum impregnation oven is 500-1800℃, the pressure is -0.1MPa-20MPa, and the time is 0.1-2h.

[0014] Further, the graphitization process described in step (5) is as follows: the high-temperature furnace is heated to 2000-2800℃ and held for 0.1-2 hours.

[0015] Secondly, embodiments of the present invention provide a carbon paper substrate with a gas diffusion layer having gas flow channels, prepared by the preparation method described in the first aspect, wherein the basis weight of the carbon paper substrate is 20-200 g / m³. 2 The thickness is 0.1-0.5mm, the channel depth is 0.05-0.4mm, and the channel width is 0.05-0.4mm.

[0016] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: 1. Low cost: In the preparation of the carbon paper substrate with gas diffusion layer with gas flow channels of the present invention, the flow channels are directly formed on the carbon paper after the impregnation solution is coated on the carbon paper base paper and the thermosetting process is carried out. Compared with the existing technology, the flow channels used to transport reaction gases are integrated on the bipolar plate, which reduces the cost.

[0017] 2. Simple process: As a gas diffusion layer, carbon paper integrates gas and liquid transmission channels, which simplifies the process of etching channels on bipolar plates and simplifies the channel forming process in the production of bipolar plates.

[0018] 3. Reduced battery resistance loss: In practical applications, the substrate prepared by this invention reduces the resistance between the bipolar plate and the substrate, and directly integrates the flow field on the carbon paper side, so that the flow field and the substrate are integrated, the contact resistance is reduced and the conductivity is improved. Therefore, during the operation of the fuel cell, the resistance loss is reduced and the performance is effectively improved.

[0019] 4. Facilitates gas-liquid transport within the battery: In existing technologies, the integrated flow channels on the bipolar plates, due to the manufacturing process and bipolar plate materials, cause the bipolar plate material to compact after the flow channel grooves and ridges are compressed, affecting gas and liquid transport. In this invention, the flow channels are pressed out on porous carbon material. After being compressed, the groove and ridge structure is more porous than the groove and ridge structure on the bipolar plates. The porous structure of the carbon paper is more conducive to gas and liquid transport. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the hot roller pressing roller used in the heat curing of adhesive paper in an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of a carbon paper substrate with a flow channel on one side prepared in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] Example 1 A method for preparing a carbon paper substrate with a gas diffusion layer having gas flow channels includes the following steps: (1) Preparation of impregnation solution: 800g of phenolic resin and 200g of graphite powder (conductive carbon material) are poured into 1000g of ethanol (solvent) and dispersed at high speed for 60min. The impregnation solution is then placed in the impregnation tank for later use. (2) Carbon paper base paper coating: The carbon paper base paper is immersed in the resin impregnation tank, and after the liquid is rolled, it is put into the drying oven for drying. The oven temperature is 80℃ and the time is 40min. After the time is up, it is taken out and weighed for the second time to calculate the resin impregnation amount. The target is 150% of the base paper mass.

[0024] (3) Thermosetting of adhesive paper: The above-impregnated and dried carbon paper base paper is placed in a pair of rollers for rolling, as shown in the figure. One of the rollers has a groove structure with a groove depth and a groove width of 0.2 mm. The two rollers are heated to 165°C and the pressure between the two rollers is 0.5 MPa. The rollers are rolled multiple times until the average thickness is 0.3 mm.

[0025] (4) Densification: The cured carbon paper base paper is placed in a vapor deposition furnace. The furnace is at normal pressure and the pressure gauge reads 0 MPa. After the vapor deposition furnace is heated to 1000℃, a mixture of methane and nitrogen gas (methane accounts for 50% of the volume of the mixture) is introduced into the furnace. The furnace is kept at this temperature for 1 hour. The methane gas diffuses in the micropores of the carbon paper base paper and undergoes a series of decomposition reactions, eventually becoming carbon and hydrogen. The carbon produced is directly deposited into the voids of the carbon paper base paper to achieve densification, thereby improving the mechanical properties of the carbon fiber composite material at the flow channel ridge on the surface of the carbon paper base paper.

[0026] (5) Graphitization: After densification treatment, the material is placed in a high-temperature furnace, heated to 2400℃, kept at that temperature for 1 hour, and then cooled naturally.

[0027] (6) After the high-temperature furnace cools to room temperature, remove the material and prepare it with a weight of 100 g / m³. 2 A carbon paper substrate for the gas diffusion layer of a proton exchange membrane fuel cell, with a thickness of 0.3 mm and parallel flow channels on one side (both groove depth and width are 0.2 mm), such as... Figure 2 As shown.

[0028] Example 2 A method for preparing a carbon paper substrate with a gas diffusion layer having gas flow channels includes the following steps: (1) Preparation of impregnation solution: 600g of phenolic resin and 20g of graphite powder (conductive carbon material) are poured into 1380g of ethanol (solvent) and dispersed at high speed for 60min. The impregnation solution is then placed in the impregnation tank for later use.

[0029] (2) Coating of carbon paper base paper with resin: The carbon paper base paper is impregnated in the resin impregnation tank, and after the resin is rolled, it is put into the drying oven for drying. The oven temperature is 65℃ and the time is 60min. After the time is up, it is taken out and weighed a second time to calculate the resin impregnation amount. The target is 100% of the mass of the base paper.

[0030] (3) Thermosetting of the adhesive paper: The above-impregnated and dried carbon paper base paper is placed in a pair of rollers for rolling, such as... Figure 1 As shown, one of the rollers has a grooved structure with a groove depth and width of 0.05 mm. The two rollers are heated to 140°C, and the pressure between the two rollers is 0.1 MPa. The rollers are rolled multiple times until the average thickness is 0.1 mm.

[0031] (4) Densification: The cured carbon paper base paper is placed in a vapor deposition furnace and pressurized. The pressure gauge reads 2 MPa. After the vapor deposition furnace is heated to 500°C, a mixture of methane and nitrogen gas (methane accounts for 90% of the volume of the mixture) is introduced into the furnace. The furnace is kept at this temperature for 2 hours. The methane gas diffuses in the micropores of the carbon paper base paper and undergoes a series of decomposition reactions, eventually becoming carbon and hydrogen. The carbon produced is directly deposited into the voids of the carbon paper base paper to achieve densification, thereby improving the mechanical properties of the carbon fiber composite material at the flow channel ridge on the surface of the carbon paper base paper.

[0032] (5) Graphitization: After densification treatment, the material is placed in a high-temperature furnace, heated to 2000℃, held for 2 hours, and then allowed to cool naturally. After the high-temperature furnace cools to room temperature, the material is removed and produced with a basis weight of 20 g / m³. 2 A carbon paper substrate for the gas diffusion layer of a proton exchange membrane fuel cell, with a thickness of 0.08 mm and parallel flow channels on one side (both groove depth and width are 0.05 mm), such as... Figure 2 As shown.

[0033] Example 3 A method for preparing a carbon paper substrate with a gas diffusion layer having gas flow channels includes the following steps: (1) Preparation of impregnation solution: 1200g of phenolic resin and 400g of graphite powder (conductive carbon material) are poured into 400g of ethanol (solution) and dispersed at high speed for 60min. The impregnation solution is then placed in the impregnation tank for later use.

[0034] (2) Coating of carbon paper base paper with resin: The carbon paper base paper is immersed in the resin impregnation tank, and after the resin is rolled, it is put into the drying oven for drying. The oven temperature is 95℃ and the time is 10min. After the time is up, it is taken out and weighed for the second time to calculate the resin impregnation amount. The target is 190% of the base paper mass.

[0035] (3) Thermosetting of the adhesive paper: The above-impregnated and dried carbon paper base paper is placed in a pair of rollers for rolling, such as... Figure 1 As shown, one of the rollers has a grooved structure with a groove depth and width of 0.4 mm. The two rollers are heated to 180°C, and the pressure between the two rollers is 1 MPa. The rollers are rolled multiple times until the average thickness is 0.5 mm.

[0036] (4) Densification: The cured carbon paper base paper is placed in a vapor deposition furnace. The vacuum pump is started to replace and exhaust all the air. The pressure gauge reading is -0.1MPa. After the vapor deposition furnace is heated to 1500℃, a mixture of methane and nitrogen gas (the volume ratio of methane in the mixture is 10%) is introduced into the furnace. The temperature is maintained for 0.1h. The methane gas diffuses in the micropores of the carbon paper base paper and undergoes a series of decomposition reactions, eventually becoming carbon and hydrogen. The carbon produced is directly deposited into the voids of the carbon paper base paper to achieve the purpose of densification, thereby improving the mechanical properties of the carbon fiber composite material at the flow channel ridge on the surface of the carbon paper base paper.

[0037] (5) Graphitization: After densification treatment, the material is placed in a high-temperature furnace, heated to 2800℃, held for 0.1 h, and then allowed to cool naturally. After the high-temperature furnace cools to room temperature, the material is removed and made into 200 g / m³. 2 A carbon paper substrate for the gas diffusion layer of a proton exchange membrane fuel cell, with a thickness of 0.5 mm and parallel flow channels on one side (both channel depth and width are 0.4 mm), such as... Figure 2 As shown.

[0038] Example 4 A method for preparing a carbon paper substrate with a gas diffusion layer having gas flow channels includes the following steps: (1) Preparation of impregnation solution: 1200g of phenolic resin and 400g of graphite powder (conductive carbon material) are poured into 400g of ethanol (solution) and dispersed at high speed for 60min. The impregnation solution is then placed in the impregnation tank for later use.

[0039] (2) Coating of carbon paper base paper with resin: The carbon paper base paper is immersed in the resin impregnation tank, and after the resin is rolled, it is put into the drying oven for drying. The oven temperature is 95℃ and the time is 10min. After the time is up, it is taken out and weighed for the second time to calculate the resin impregnation amount. The target is 190% of the base paper mass.

[0040] (3) Thermosetting of the adhesive paper: The above-impregnated and dried carbon paper base paper is placed in a pair of rollers for rolling, such as... Figure 1 As shown, one of the rollers has a grooved structure with a groove depth and width of 0.4 mm. The two rollers are heated to 180°C, and the pressure between the two rollers is 1 MPa. The rollers are rolled multiple times until the average thickness is 0.5 mm.

[0041] (4) Densification: The cured carbon paper base paper is placed in a tank containing (1) impregnation liquid. The tank is placed in a vacuum impregnation furnace. The vacuum pump is started to replace and exhaust all the air. The pressure gauge reading is -0.1MPa. After the vacuum impregnation furnace is heated to 1500℃, it is kept at the temperature for 0.1h. The impregnation liquid diffuses in the micropores of the carbon paper base paper and eventually becomes carbon deposited in the gaps of the carbon paper base paper to achieve the purpose of densification, thereby improving the mechanical properties of the carbon fiber composite material at the flow channel ridge on the surface of the carbon paper base paper.

[0042] (5) Graphitization: After densification treatment, the material is placed in a high-temperature furnace, heated to 2800℃, held for 0.1 h, and then allowed to cool naturally. After the high-temperature furnace cools to room temperature, the material is removed and made into 200 g / m³. 2 A carbon paper substrate for the gas diffusion layer of a proton exchange membrane fuel cell, with a thickness of 0.5 mm and parallel flow channels on one side (both channel depth and width are 0.4 mm), such as... Figure 2 As shown.

[0043] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a carbon paper substrate with a gas diffusion layer having gas flow channels, characterized in that, Includes the following steps: (1) Preparation of adhesive solution: The resin, conductive material and solvent are mixed and dispersed evenly in a certain proportion to prepare an impregnation solution; (2) Coating of carbon paper base paper with adhesive solution: The adhesive solution prepared in step (1) is coated onto the carbon paper base paper and dried; (3) Thermosetting of adhesive paper: The carbon paper base paper obtained in step (2) is cured and shaped using a specific mold. The curing temperature is 140-200℃, the pressure is 0.1-10MPa, and the curing time is 1-20min. (4) Densification: The carbon paper base paper cured in step (3) is placed in a high-temperature furnace for high-temperature densification treatment; (5) Graphitization treatment: The carbon paper base paper after the densification treatment in step (4) is placed in a high-temperature furnace for graphitization treatment; (6) After the graphitization treatment in step (5) is cooled, a carbon paper substrate with a gas diffusion layer having a gas flow channel on one side is obtained. In step (3), a high-temperature press is used for curing and molding. The high-temperature press is a press including a flat plate press or a roller press. In the flat plate press, one of the upper and lower plates has a groove structure, and in the roller press, one of the two pairs of rollers has a groove structure. The high-temperature densification mentioned in step (4) includes densification in a vapor deposition furnace or secondary densification in a vacuum impregnation furnace; When using a vapor deposition furnace for densification, the furnace temperature is 500-1800℃, the pressure is -0.1MPa-2MPa, the mixed atmosphere is a mixture of carbon-containing gas and inert gas, the volume percentage of carbon-containing gas in the mixed atmosphere is 10%-90%, and the processing time is 0.1-2h. When using a vacuum impregnation oven for secondary sizing, the secondary sizing temperature is 500-1800℃, the pressure is -0.1MPa-20MPa, and the time is 0.1-2h. The graphitization process described in step (5) is as follows: the high-temperature furnace is heated to 2000-2800℃ and held for 0.1-2 hours.

2. The method for preparing a carbon paper substrate with a gas diffusion layer having gas flow channels according to claim 1, characterized in that, The resin mentioned in step (1) includes one or more of phenolic resin, epoxy resin, polyimide resin, and epoxy acrylate resin.

3. The method for preparing a carbon paper substrate with a gas diffusion layer having gas flow channels according to claim 1, characterized in that, The conductive material mentioned in step (1) includes one or more of graphite powder, carbon powder, carbon nanotubes, and conductive carbon black.

4. The method for preparing a carbon paper substrate with a gas diffusion layer having gas flow channels according to claim 1, characterized in that, The solvent mentioned in step (1) includes one or more of water, alcohols, lipids, ethers, and ketones.

5. The method for preparing a carbon paper substrate with a gas diffusion layer having gas flow channels according to claim 1, characterized in that, In step (1), the mass ratio of resin, solvent, and conductive material in the impregnation solution is 30-60:20-69:1-20.

6. The method for preparing a carbon paper substrate with a gas diffusion layer having gas flow channels according to claim 1, characterized in that, The basis weight of the carbon paper base paper mentioned in step (2) is 10-100 g / m². 2 The drying temperature is 65-95℃, the drying time is 10-60 minutes, and the amount of resin after drying is 100%-200% of the weight of the original paper.

7. A carbon paper substrate with a gas diffusion layer having gas flow channels, characterized in that, The carbon paper substrate is prepared by the preparation method according to any one of claims 1-6, and the basis weight of the carbon paper substrate is 20-200 g / m². 2 The thickness is 0.1-0.5mm, the channel depth is 0.05-0.4mm, and the channel width is 0.05-0.4mm.

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