A fuel cell gas diffusion layer and a method for manufacturing the same

Abstract

The application discloses a fuel cell gas diffusion layer, which is suitable for a fuel cell and comprises a porous carbon fiber substrate layer and a microporous layer in abutment; the porous carbon fiber substrate layer is arranged close to a polar plate of the fuel cell, and the microporous layer is arranged close to a catalytic layer of the fuel cell; a flow channel is arranged on one side of the porous carbon fiber substrate layer close to the polar plate; the thickness of the porous carbon fiber substrate layer is 100-400 microns, and the depth of the flow channel is 20-100 microns; and the thickness of the microporous layer is 20-120 microns. The application further provides a preparation method of the fuel cell gas diffusion layer. The preparation method is simple, low in production cost, high in production efficiency and capable of realizing continuous production. The fuel cell gas diffusion layer prepared by the method is applied to the fuel cell, and the polar plate can be thinned greatly, so that the power density of the fuel cell stack and the cell performance can be greatly improved.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a fuel cell gas diffusion layer and its preparation method. Background Technology

[0002] Fuel cells are the ideal power generation device for utilizing hydrogen energy. A fuel cell is a power generation device that directly converts the chemical energy in fuel into electrical energy through an electrochemical reaction. Compared to traditional energy sources, fuel cells are a highly efficient and clean electrochemical power generation device, and have received widespread attention both domestically and internationally in recent years.

[0003] Currently, commercial fuel cells mainly use perfluorosulfonic acid (PFSA) proton exchange membranes, with operating temperatures generally not exceeding 80°C. These systems suffer from drawbacks such as poor catalyst tolerance to CO, the need for PEM humidification to maintain proton conductivity, complex cathode water management, and the requirement to fabricate complex flow channels on the electrode plates for water-gas transport. High-temperature proton exchange membrane fuel cells (HTFE) operate at temperatures above 100°C (typically in the 100°C–200°C range), offering advantages such as high catalytic activity, CO tolerance, and simple hydrothermal management. They can utilize hydrogen sources such as methanol reformate, and water is essentially gaseous at high temperatures, thus reducing the requirements for electrode plate flow channel design and gas diffusion layer drainage. Therefore, high-temperature fuel cells are gradually becoming a research hotspot. However, the current research challenges lie in addressing the challenges of high-temperature fuel cell reactant gas transport (such as the concentration difference between gas inlet and outlet) and the difficulty of electrode plate flow channel fabrication while simultaneously reducing the stack weight and increasing its volumetric and mass power densities. Summary of the Invention

[0004] Based on this, the present invention provides a fuel cell gas diffusion layer and its preparation method, aiming to solve the problems of existing high-temperature fuel cell reactant gas transport (such as the problem of gas inlet and outlet concentration differences), high difficulty in electrode channel processing, heavy stack weight, and low volumetric power density and mass power density. This application optimizes the structure of the fuel cell gas diffusion layer by setting microchannels on a carbon fiber substrate to achieve gas transport and distribution. This avoids the difficulty in electrode channel processing and solves the reactant gas transport problem, achieving superior fuel cell performance.

[0005] To achieve the above objectives, in one aspect, embodiments of the present invention provide a fuel cell gas diffusion layer, applicable to fuel cells, comprising an abutting porous carbon fiber substrate layer and a microporous layer; the porous carbon fiber substrate layer is disposed near the electrode plate of the fuel cell, and the microporous layer is disposed near the catalyst layer of the fuel cell; a flow channel is provided on the side of the porous carbon fiber substrate layer near the electrode plate; the thickness of the porous carbon fiber substrate layer is 100μm to 400μm, the depth of the flow channel is 20μm to 100μm, and the thickness of the microporous layer is 20μm to 120μm.

[0006] By setting flow channels on a porous carbon fiber substrate, the gas transmission function that the original electrode plate needed to have is transferred to the gas diffusion layer, which simplifies the processing of the electrode plate and enables the electrode plate to be "extremely thin". This can significantly reduce the mass and volume of the fuel cell and increase the power density of the fuel cell.

[0007] In a preferred embodiment, the flow channel is a serpentine flow channel, a parallel flow channel, a spiral flow channel, or a grid flow channel.

[0008] On the other hand, embodiments of this application also provide a method for preparing the fuel cell gas diffusion layer, including the following steps:

[0009] S01. Place the carbon fiber substrate slurry in a 3D printer for 3D printing to obtain a carbon paper substrate with a flow channel on one side.

[0010] S02. The carbon paper substrate from step S01 is immersed in the impregnation solution for 1 to 12 hours, and then dried to obtain carbon paper.

[0011] S03. The carbon paper from step S02 is hot-pressed at 120℃~200℃ and 3MPa~8MPa for 30s~240s and then carbonized and graphitized to obtain the finished carbon paper.

[0012] S04. The finished carbon paper from step S03 is subjected to hydrophobic treatment, then vacuum dried and cured to obtain a porous carbon fiber substrate layer.

[0013] S05. A microporous layer is formed on the side of the porous carbon fiber substrate layer away from the flow channel in step S04 to obtain the fuel cell gas diffusion layer.

[0014] In a preferred embodiment, in step S01,

[0015] Based on the weight of the carbon fiber substrate slurry as 100%, the carbon fiber substrate slurry contains 1.0% to 10.0% polyacrylonitrile-based carbon fiber, 0.2% to 2.5% organic dispersant and 1.0% to 3.0% adhesive, with the balance being water.

[0016] The polyacrylonitrile-based carbon fiber has a diameter of 5μm to 20μm, a length of 2μm to 10mm, and an aspect ratio of 200 to 600.

[0017] The organic dispersant is one or a mixture of at least two of polyacrylamide, polyethyleneimine, anionic starch, or cationic starch. The organic dispersant can effectively alter the rheological properties of the slurry, restrict the degrees of freedom of carbon fiber movement, and alleviate the sedimentation and agglomeration of polyacrylonitrile-based carbon fibers.

[0018] The adhesive is one or a mixture of at least two of the following: polyvinyl alcohol (PVA), polyethylene oxide, epoxy resin, or phenolic resin.

[0019] The flow channels can be configured according to the MEA size and related requirements.

[0020] In a preferred embodiment, in step S02,

[0021] The impregnation solution is prepared from water, ethanol and resin; the mass ratio of water to ethanol is 1:1 to 1:3; and the impregnation solution contains 10% to 40% of the resin, based on 100% by weight.

[0022] The resin is preferably a phenolic resin, a phenolic resin, or a furan resin.

[0023] The drying process involves drying at 50℃ to 90℃ for 30 to 120 minutes.

[0024] In a preferred embodiment, in step S03...

[0025] The carbonization is carried out at 800℃~1000℃ for 15min~60min; the graphitization is carried out at 1500℃~2500℃ for 15min~60min.

[0026] In a preferred embodiment, in step S04,

[0027] The hydrophobic treatment involves treating with a hydrophobic agent for 5 to 30 hours; the concentration of the hydrophobic agent is 10% to 50%.

[0028] The hydrophobic agent is one or a mixture of at least two of polytetrafluoroethylene, polyvinylidene fluoride, or fluorinated ethylene propylene.

[0029] The vacuum drying is performed at 60℃~100℃ for 2 to 10 hours. The curing is performed at 300℃~400℃ for 30 minutes to 5 hours.

[0030] In a preferred embodiment, in step S05...

[0031] The setting is achieved by spraying, scraping, or screen printing.

[0032] The thickness of the microporous layer is 20 μm to 120 μm.

[0033] This application avoids the difficulty of fabricating flow channels on the electrode plates by setting flow channels on the porous carbon fiber substrate of the fuel cell gas diffusion layer, and also effectively solves the problems of fuel cell reactant gas transport and uniform distribution. Simultaneously, it enables extremely thin electrode plates, significantly improving the power density (including volumetric power density and mass power density) and battery performance of the fuel cell stack. Furthermore, the porous carbon fiber substrate prepared by 3D printing effectively avoids the problem of low forming precision in conventional wet papermaking, allowing for precise, complex, and three-dimensional flow channel structure designs according to actual needs. The preparation method of this application is simple, has low production cost, high production efficiency, and can achieve continuous production. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the gas diffusion layer of the fuel cell in Embodiment 1 of the present invention;

[0036] Figure 2 This is a schematic diagram of the structure of a fuel cell unit according to Embodiment 1 of the present invention;

[0037] Figure 3 This is a schematic diagram of the structure of the fuel cell unit in Comparative Example 1 of the present invention.

[0038] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, top, bottom, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0041] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0042] It should be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0043] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0044] Currently, the main research challenges in fuel cell manufacturing are how to reduce stack weight and increase volumetric and mass power densities while addressing the difficulties in high-temperature reactant gas transport (such as the concentration difference between gas inlet and outlet) and the fabrication of electrode channels. Therefore, it is necessary to provide a fuel cell gas diffusion layer and its preparation method to solve these technical problems.

[0045] To achieve the above objectives, on the one hand, such as Figure 1 As shown, this embodiment of the invention provides a gas diffusion layer for a fuel cell, suitable for a fuel cell 100, comprising a porous carbon fiber substrate 10 and a microporous layer 20 abutting each other; the porous carbon fiber substrate 10 is disposed near the electrode plate 101 of the fuel cell 100, and the microporous layer 20 is disposed near the catalyst layer 102 of the fuel cell 100; a flow channel 11 is provided on the side of the porous carbon fiber substrate 10 near the electrode plate 101; the thickness of the porous carbon fiber substrate 10 is 100μm to 400μm, the depth of the flow channel 11 is 20μm to 100μm, and the thickness of the microporous layer 20 is 20μm to 120μm.

[0046] By setting flow channels on a porous carbon fiber substrate, the gas transmission function that the original electrode plate needed to have is transferred to the gas diffusion layer, which simplifies the processing of the electrode plate and enables the electrode plate to be "extremely thin". This can significantly reduce the mass and volume of the fuel cell and increase the power density of the fuel cell.

[0047] If the thickness of the porous carbon fiber substrate layer exceeds 400 μm, it will increase the internal resistance of the battery; if the thickness is less than 100 μm, the supporting strength of the substrate layer will be insufficient. The depth of the flow channel needs to be less than the thickness of the porous carbon fiber substrate layer. If the flow channel is too deep, the porous carbon fiber substrate layer is prone to breakage; if the flow channel is too shallow, it cannot perform its "flow channel" function and is prone to disappearing during assembly under pressure. The thickness of the microporous layer needs to be controlled between 20 μm and 120 μm. If it is too thin, the redistribution of gas and water cannot be achieved, and the catalyst is prone to leakage into the porous carbon fiber substrate layer; if it is too thick, it will result in high drainage resistance and the battery interior will be prone to flooding.

[0048] In a preferred embodiment, the flow channel is a serpentine flow channel, a parallel flow channel, a spiral flow channel, or a grid flow channel.

[0049] On the other hand, embodiments of this application also provide a method for preparing the fuel cell gas diffusion layer, including the following steps:

[0050] S01. Place the carbon fiber substrate slurry in a 3D printer for 3D printing to obtain a carbon paper substrate with a flow channel on one side.

[0051] S02. The carbon paper substrate from step S01 is immersed in the impregnation solution for 1 hour to 12 hours, and then dried to obtain carbon paper.

[0052] S03. The carbon paper from step S02 is hot-pressed at 120℃~200℃ and 3MPa~8MPa for 30s~240s and then carbonized and graphitized to obtain the finished carbon paper.

[0053] S04. The finished carbon paper from step S03 is subjected to hydrophobic treatment, then vacuum dried and cured to obtain a porous carbon fiber substrate layer.

[0054] S05. A microporous layer is formed on the side of the porous carbon fiber substrate layer away from the flow channel in step S04 to obtain the fuel cell gas diffusion layer.

[0055] In a preferred embodiment, in step S01,

[0056] Based on 100% by weight, the carbon fiber substrate slurry contains 1.0%–10.0% polyacrylonitrile-based carbon fiber, 0.2%–2.5% organic dispersant, and 1.0%–3.0% adhesive, with the balance being water. This allows for the uniform dispersion of the polyacrylonitrile-based carbon fiber. If the dispersion system is too thin, effective dispersion of the polyacrylonitrile-based carbon fiber is difficult, and the carbon fiber is hard to break up and prone to agglomeration. If the dispersion system is too thick, especially with excessive adhesive, the polyacrylonitrile-based carbon fiber is prone to caking, resulting in a substrate layer with poor air permeability.

[0057] The polyacrylonitrile-based carbon fiber has a diameter of 5μm to 20μm, a length of 2μm to 10mm, and an aspect ratio of 200 to 600.

[0058] The organic dispersant is one or a mixture of at least two of polyacrylamide, polyethyleneimine, anionic starch, or cationic starch. The organic dispersant can effectively alter the rheological properties of the slurry, restrict the degrees of freedom of carbon fiber movement, and alleviate the sedimentation and agglomeration of polyacrylonitrile-based carbon fibers.

[0059] The adhesive is one or a mixture of at least two of the following: polyvinyl alcohol (PVA), polyethylene oxide, epoxy resin, or phenolic resin.

[0060] The flow channels can be configured according to the MEA size and related requirements.

[0061] In a preferred embodiment, in step S02,

[0062] The impregnation solution is prepared from water, ethanol and resin; the mass ratio of water to ethanol is 1:1 to 1:3; and the impregnation solution contains 10% to 40% of the resin, based on 100% by weight.

[0063] The carbon paper formed by the adhesive and carbon fiber initial molding will leave a large number of voids. By adding resin impregnation, the air permeability of the base layer can be well controlled. The impregnation solution is mainly used to regulate the air permeability of the porous carbon fiber base layer. If the impregnation solution is too thin, it cannot fill the large voids left by the initial molding, resulting in excessive air permeability of the porous carbon fiber base layer; if the impregnation solution is too thick, it is easy to cover or block the porous carbon fiber base layer, resulting in poor air permeability of the porous carbon fiber base layer.

[0064] The resin is preferably a phenolic resin, a phenolic resin, or a furan resin.

[0065] The drying process involves drying at 50℃ to 90℃ for 30 to 120 minutes.

[0066] In a preferred embodiment, in step S03...

[0067] The carbonization is carried out at 800℃~1000℃ for 15min~60min; the graphitization is carried out at 1500℃~2500℃ for 15min~60min. In this way, through carbonization and graphitization modification, the prepared porous carbon fiber substrate can have good electrical conductivity, thermal conductivity and thermal stability.

[0068] In a preferred embodiment, in step S04,

[0069] The hydrophobic treatment involves treating the gas diffusion layer with a hydrophobic agent for 5 to 30 hours; the concentration of the hydrophobic agent is 10% to 50%. This allows the prepared gas diffusion layer to be easily drained, effectively preventing water flooding.

[0070] The hydrophobic agent is one or a mixture of at least two of polytetrafluoroethylene, polyvinylidene fluoride, or fluorinated ethylene propylene.

[0071] The vacuum drying is performed at 60℃ to 100℃ for 2 to 10 hours.

[0072] The curing process involves curing at 300℃~400℃ for 30 minutes to 5 hours.

[0073] In a preferred embodiment, in step S05...

[0074] The setting is achieved by spraying, scraping, or screen printing.

[0075] The thickness of the microporous layer is 20 μm to 120 μm.

[0076] This application avoids the difficulty of fabricating flow channels on the electrode plates by setting flow channels on the porous carbon fiber substrate of the fuel cell gas diffusion layer, and also effectively solves the problems of fuel cell reactant gas transport and uniform distribution. Simultaneously, it enables extremely thin electrode plates, significantly improving the power density (including volumetric power density and mass power density) and battery performance of the fuel cell stack. Furthermore, the porous carbon fiber substrate prepared by 3D printing effectively avoids the problem of low forming precision in conventional wet papermaking, allowing for precise, complex, and three-dimensional flow channel structure designs according to actual needs. The preparation method of this application is simple, has low production cost, high production efficiency, and can achieve continuous production.

[0077] Example 1

[0078] A method for preparing a gas diffusion layer for a fuel cell includes the following steps:

[0079] S01. Place the carbon fiber substrate slurry in a 3D printer for 3D printing to obtain a carbon paper substrate with a flow channel on one side.

[0080] S02. The carbon paper substrate from step S01 is immersed in the impregnation solution for 6 hours and then dried to obtain carbon paper.

[0081] S03. The carbon paper from step S02 is hot-pressed at 145℃ and 5MPa for 120s and then carbonized and graphitized to obtain the finished carbon paper.

[0082] S04. The finished carbon paper from step S03 is subjected to hydrophobic treatment, then vacuum dried and cured to obtain a porous carbon fiber substrate layer.

[0083] S05. A microporous layer is formed on the side of the porous carbon fiber substrate layer away from the flow channel in step S04 to obtain the fuel cell gas diffusion layer (structure as shown). Figure 1 (As shown).

[0084] In step S01,

[0085] Based on the weight of the carbon fiber substrate slurry as 100%, the carbon fiber substrate slurry contains 2.0% polyacrylonitrile-based carbon fiber, 2.5% organic dispersant and 1.0% adhesive, with the balance being water.

[0086] The polyacrylonitrile-based carbon fiber has a diameter of 10 μm, a length of 5 mm, and an aspect ratio of 500.

[0087] The organic dispersant is a mixture of polyacrylamide (1.0%) and polyethyleneimine (1.5%).

[0088] The adhesive is polyvinyl alcohol.

[0089] The depth of the flow channel is 80 μm.

[0090] In step S02,

[0091] The impregnation solution is prepared from water, ethanol and resin; the mass ratio of water to ethanol is 1:1; and the impregnation solution contains 25% of the resin, based on 100% by weight.

[0092] The resin is a phenolic resin.

[0093] The drying process involves drying at 60°C for 60 minutes.

[0094] In step S03,

[0095] The carbonization is carried out at 800℃ for 30 minutes; the graphitization is carried out at 2000℃ for 45 minutes.

[0096] In step S04,

[0097] The hydrophobic treatment involves treating with a hydrophobic agent for 10 hours; the concentration of the hydrophobic agent is 10%.

[0098] The hydrophobic agent is polytetrafluoroethylene.

[0099] The vacuum drying process involves drying at 80°C for 3 hours.

[0100] The curing process involves curing at 350°C for 2 hours. The thickness of the porous carbon fiber substrate layer is 300 μm.

[0101] In step S05,

[0102] The configuration is achieved through a spraying process. The thickness of the microporous layer is 50 μm.

[0103] The gas diffusion layer prepared above is positioned with the flow channel designed side near the electrode side, and the microporous layer is positioned near the catalyst layer. These components are then assembled into a single cell (structure as shown in the image). Figure 2 (As shown). Testing revealed that the prepared fuel cell exhibited uniform gas transport and distribution, achieving extremely thin electrode plates and demonstrating good power density (including volumetric power density and mass power density) and battery performance. In this application, the gas inlet and outlet do not require significant alteration; they are simply moved from the electrode plates to the gas diffusion layer to adapt to the flow channels. Therefore, the porous carbon fiber substrate layer has gas inlet and outlet ports adapted to the flow channels at both ends.

[0104] Example 2

[0105] A method for preparing a gas diffusion layer for a fuel cell includes the following steps:

[0106] S01. Place the carbon fiber substrate slurry in a 3D printer for 3D printing to obtain a carbon paper substrate with a flow channel on one side.

[0107] S02. The carbon paper substrate from step S01 is immersed in the impregnation solution for 10 hours and then dried to obtain carbon paper.

[0108] S03. The carbon paper from step S02 is hot-pressed at 180℃ and 3MPa for 200s and then carbonized and graphitized to obtain the finished carbon paper.

[0109] S04. The finished carbon paper from step S03 is subjected to hydrophobic treatment, then vacuum dried and cured to obtain a porous carbon fiber substrate layer.

[0110] S05. A microporous layer is formed on the side of the porous carbon fiber substrate layer away from the flow channel in step S04 to obtain the fuel cell gas diffusion layer.

[0111] In step S01,

[0112] Based on the weight of the carbon fiber substrate slurry as 100%, the carbon fiber substrate slurry contains 4.0% polyacrylonitrile-based carbon fiber, 1.5% organic dispersant and 3.0% adhesive, with the balance being water.

[0113] The polyacrylonitrile-based carbon fiber has a diameter of 20 μm, a length of 6 mm, and an aspect ratio of 300.

[0114] The organic dispersant is polyacrylamide. The adhesive is polyvinyl alcohol. The depth of the flow channel is 100 μm.

[0115] In step S02,

[0116] The impregnation solution is prepared from water, ethanol and resin; the mass ratio of water to ethanol is 1:3; and the impregnation solution contains 18% of the resin, based on 100% by weight.

[0117] The resin is a furan resin. The drying process involves drying at 85°C for 100 minutes.

[0118] In step S03,

[0119] The carbonization is carried out at 1000℃ for 45 minutes; the graphitization is carried out at 2500℃ for 30 minutes.

[0120] In step S04,

[0121] The hydrophobic treatment involves treating with a hydrophobic agent for 15 hours; the concentration of the hydrophobic agent is 30%.

[0122] The hydrophobic agent is polyvinylidene fluoride.

[0123] The vacuum drying process involves drying at 65°C for 8 hours.

[0124] The curing process involves curing at 400°C for 5 hours. The thickness of the porous carbon fiber substrate layer is 400 μm.

[0125] In step S05,

[0126] The microporous layer is applied by a scraping method. The thickness of the microporous layer is 100 μm.

[0127] The gas diffusion layer with the flow channel design prepared above is placed near the electrode side, and the microporous layer is placed near the catalyst layer. These components are then assembled into a single cell. Testing showed that the prepared fuel cell exhibited uniform gas transport and distribution, achieved extremely thin electrodes, and demonstrated good power density (including volumetric power density and mass power density) and battery performance.

[0128] Example 3

[0129] A method for preparing a gas diffusion layer for a fuel cell includes the following steps:

[0130] S01. Place the carbon fiber substrate slurry in a 3D printer for 3D printing to obtain a carbon paper substrate with a flow channel on one side.

[0131] S02. The carbon paper substrate from step S01 is immersed in the impregnation solution for 1 hour, and then dried to obtain carbon paper.

[0132] S03. The carbon paper from step S02 is hot-pressed at 120℃ and 5MPa for 30s and then carbonized and graphitized to obtain the finished carbon paper.

[0133] S04. The finished carbon paper from step S03 is subjected to hydrophobic treatment, then vacuum dried and cured to obtain a porous carbon fiber substrate layer.

[0134] S05. A microporous layer is formed on the side of the porous carbon fiber substrate layer away from the flow channel in step S04 to obtain the fuel cell gas diffusion layer.

[0135] In a preferred embodiment, in step S01,

[0136] Based on the weight of the carbon fiber substrate slurry as 100%, the carbon fiber substrate slurry contains 1.0% polyacrylonitrile-based carbon fiber, 0.2% organic dispersant and 1.0% adhesive, with the balance being water.

[0137] The polyacrylonitrile-based carbon fiber has a diameter of 5 μm, a length of 1 mm, and an aspect ratio of 200.

[0138] The organic dispersant is anionic starch. The adhesive is epoxy resin.

[0139] In step S02,

[0140] The impregnation solution is prepared from water, ethanol and resin; the mass ratio of water to ethanol is 1:2; and the impregnation solution contains 10% of the resin, based on 100% by weight.

[0141] The resin is a phenolic resin.

[0142] The drying process involves drying at 50°C for 30 minutes.

[0143] In step S03,

[0144] The carbonization is carried out at 800℃ for 15 minutes; the graphitization is carried out at 1500℃ for 15 minutes.

[0145] In step S04,

[0146] The hydrophobic treatment involves treating with a hydrophobic agent for 5 hours; the concentration of the hydrophobic agent is 10%.

[0147] The hydrophobic agent is fluorinated ethylene propylene.

[0148] The vacuum drying is performed at 60°C for 2 hours. The curing is performed at 300°C for 30 minutes.

[0149] In step S05,

[0150] The configuration is achieved through screen printing. The thickness of the microporous layer is 20 μm.

[0151] The gas diffusion layer with the flow channel design prepared above is placed near the electrode side, and the microporous layer is placed near the catalyst layer. These components are then assembled into a single cell. Testing showed that the prepared fuel cell exhibited uniform gas transport and distribution, achieved extremely thin electrodes, and demonstrated good power density (including volumetric power density and mass power density) and battery performance.

[0152] Example 4

[0153] A method for preparing a gas diffusion layer for a fuel cell includes the following steps:

[0154] S01. Place the carbon fiber substrate slurry in a 3D printer for 3D printing to obtain a carbon paper substrate with a flow channel on one side.

[0155] S02. The carbon paper substrate from step S01 is immersed in the impregnation solution for 12 hours and then dried to obtain carbon paper.

[0156] S03. The carbon paper from step S02 is hot-pressed at 200℃ and 8MPa for 240s and then carbonized and graphitized to obtain the finished carbon paper.

[0157] S04. The finished carbon paper from step S03 is subjected to hydrophobic treatment, then vacuum dried and cured to obtain a porous carbon fiber substrate layer.

[0158] S05. A microporous layer is formed on the side of the porous carbon fiber substrate layer away from the flow channel in step S04 to obtain the fuel cell gas diffusion layer.

[0159] In step S01,

[0160] Based on the weight of the carbon fiber substrate slurry as 100%, the carbon fiber substrate slurry contains 10.0% polyacrylonitrile-based carbon fiber, 2.5% organic dispersant and 2.0% adhesive, with the balance being water.

[0161] The polyacrylonitrile-based carbon fiber has a diameter of 20 μm, a length of 10 mm, and an aspect ratio of 500.

[0162] The organic dispersant is polyacrylamide.

[0163] The adhesive is polyethylene oxide.

[0164] In step S02,

[0165] The impregnation solution is prepared from water, ethanol and resin; the mass ratio of water to ethanol is 1:3; and the impregnation solution contains 40% of the resin, based on 100% by weight.

[0166] The resin is a phenolic resin.

[0167] The drying process involves drying at 90°C for 120 minutes.

[0168] In step S03,

[0169] The carbonization is carried out at 1000℃ for 60 minutes; the graphitization is carried out at 2500℃ for 60 minutes.

[0170] In step S04,

[0171] The hydrophobic treatment involves treating with a hydrophobic agent for 30 hours; the concentration of the hydrophobic agent is 50%.

[0172] The hydrophobic agent is polytetrafluoroethylene.

[0173] The vacuum drying is performed at 100°C for 10 hours. The curing is performed at 400°C for 5 hours.

[0174] In step S05,

[0175] The configuration is achieved through a spraying process. The thickness of the microporous layer is 120 μm.

[0176] The gas diffusion layer with the flow channel design prepared above is placed near the electrode side, and the microporous layer is placed near the catalyst layer. These components are then assembled into a single cell. Testing showed that the prepared fuel cell exhibited uniform gas transport and distribution, achieved extremely thin electrodes, and demonstrated good power density (including volumetric power density and mass power density) and battery performance.

[0177] Comparative Example 1

[0178] A method for preparing a gas diffusion layer for a fuel cell includes the following steps:

[0179] S01. Place the carbon fiber substrate slurry in a 3D printer for 3D printing to obtain a carbon paper substrate.

[0180] S02. The carbon paper substrate from step S01 is immersed in the impregnation solution for 6 hours and then dried to obtain carbon paper.

[0181] S03. The carbon paper from step S02 is hot-pressed at 145℃ and 5MPa for 120s and then carbonized and graphitized to obtain the finished carbon paper.

[0182] S04. The finished carbon paper from step S03 is subjected to hydrophobic treatment, then vacuum dried and cured to obtain a porous carbon fiber substrate layer.

[0183] S05. A microporous layer is formed on one side of the porous carbon fiber substrate layer in step S04 to obtain the fuel cell gas diffusion layer.

[0184] In step S01,

[0185] Based on the weight of the carbon fiber substrate slurry as 100%, the carbon fiber substrate slurry contains 2.0% polyacrylonitrile-based carbon fiber, 2.5% organic dispersant and 1.0% adhesive, with the balance being water.

[0186] The polyacrylonitrile-based carbon fiber has a diameter of 10 μm, a length of 5 mm, and an aspect ratio of 500.

[0187] The organic dispersant is a mixture of polyacrylamide (1.0%) and polyethyleneimine (1.5%).

[0188] The adhesive is polyvinyl alcohol.

[0189] In step S02,

[0190] The impregnation solution is prepared from water, ethanol and resin; the mass ratio of water to ethanol is 1:1; and the impregnation solution contains 25% of the resin, based on 100% by weight.

[0191] The resin is a phenolic resin.

[0192] The drying process involves drying at 60°C for 60 minutes.

[0193] In step S03,

[0194] The carbonization is carried out at 800℃ for 30 minutes; the graphitization is carried out at 2000℃ for 45 minutes.

[0195] In step S04,

[0196] The hydrophobic treatment involves treating with a hydrophobic agent for 10 hours; the concentration of the hydrophobic agent is 10%.

[0197] The hydrophobic agent is polytetrafluoroethylene.

[0198] The vacuum drying process involves drying at 80°C for 3 hours.

[0199] The curing process involves curing at 350°C for 2 hours. The thickness of the porous carbon fiber substrate layer is 300 μm.

[0200] In step S05,

[0201] The configuration is achieved through a spraying process. The thickness of the microporous layer is 50 μm.

[0202] The porous carbon fiber substrate of the gas diffusion layer prepared above is placed on one side of the electrode plate with a flow channel 1011 (the depth of the flow channel 1011 is 80 μm), and the microporous layer is placed near the catalyst layer. These components are then assembled into a single cell (structure as shown). Figure 3 (As shown). Tests revealed that the fabrication process of the fuel cell was quite difficult, the plates were thicker, and both its volumetric power density and mass power density were lower, resulting in performance inferior to the fuel cell prepared in Example 1.

[0203] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A gas diffusion layer for a fuel cell, characterized in that, Suitable for fuel cells, comprising an abutting porous carbon fiber substrate layer and a microporous layer; the porous carbon fiber substrate layer is disposed near the electrode plate of the fuel cell, and the microporous layer is disposed near the catalyst layer of the fuel cell; a flow channel is provided on the side of the porous carbon fiber substrate layer near the electrode plate; the thickness of the porous carbon fiber substrate layer is 100µm to 400µm, the depth of the flow channel is 20µm to 100µm, and the thickness of the microporous layer is 20µm to 120µm; The method for preparing the fuel cell gas diffusion layer includes the following steps: S01. Place the carbon fiber substrate slurry in a 3D printer for 3D printing to obtain a carbon paper substrate with a flow channel on one side. S02. The carbon paper substrate from step S01 is immersed in the impregnation solution for 1 to 12 hours, and then dried to obtain carbon paper. S03. The carbon paper from step S02 is hot-pressed at 120℃~200℃ and 3MPa~8MPa for 30s~240s and then carbonized and graphitized to obtain the finished carbon paper. S04. The finished carbon paper from step S03 is subjected to hydrophobic treatment, then vacuum dried and cured to obtain a porous carbon fiber substrate layer. S05. A microporous layer is provided on the side of the porous carbon fiber substrate layer away from the flow channel in step S04 to obtain the fuel cell gas diffusion layer; In step S01, based on the weight of the carbon fiber substrate slurry as 100%, the carbon fiber substrate slurry contains 1.0% to 10.0% polyacrylonitrile-based carbon fiber, 0.2% to 2.5% organic dispersant, and 1.0% to 3.0% adhesive, with the balance being water; The polyacrylonitrile-based carbon fiber has a diameter of 5µm to 20µm, a length of 2µm to 10mm, and an aspect ratio of 200 to 600. The organic dispersant is one or a mixture of at least two of polyacrylamide, polyethyleneimine, anionic starch, or cationic starch; The adhesive is one or a mixture of at least two of the following: polyvinyl alcohol, polyethylene oxide, epoxy resin, or phenolic resin. In step S02, the impregnation solution is prepared from water, ethanol and resin; the mass ratio of water to ethanol is 1:1 to 1:3; and the impregnation solution contains 10% to 40% of the resin, based on 100% by weight. The resin is a phenolic resin or a furan resin; In step S03, the carbonization is carried out at 800℃~1000℃ for 15min~60min; the graphitization is carried out at 1500℃~2500℃ for 15min~60min.

2. The fuel cell gas diffusion layer according to claim 1, characterized in that, The flow channel can be a serpentine flow channel, a parallel flow channel, a spiral flow channel, or a grid flow channel.

3. The fuel cell gas diffusion layer according to claim 1, characterized in that, In step S02, the drying process involves drying at 50℃ to 90℃ for 30 min to 120 min.

4. The fuel cell gas diffusion layer according to claim 1, characterized in that, In step S04, the hydrophobic treatment involves treating with a hydrophobic agent for 5 to 30 hours; the concentration of the hydrophobic agent is 10% to 50%. The hydrophobic agent is one or a mixture of at least two of polytetrafluoroethylene, polyvinylidene fluoride, or fluorinated ethylene propylene.

5. The fuel cell gas diffusion layer according to claim 1, characterized in that, In step S04, the vacuum drying is performed at 60℃~100℃ for 2 to 10 hours; the curing is performed at 300℃~400℃ for 30 minutes to 5 hours.

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