Preparation method of microporous layer slurry, gas diffusion layer and membrane electrode assembly

Abstract

The invention belongs to the technical field of proton exchange membrane fuel cells, and particularly relates to a preparation method of microporous layer slurry, a gas diffusion layer and a membrane electrode assembly. The invention discloses a microporous layer slurry preparation method, which comprises: (1) carrying out dispersion treatment on carbon black, a solvent and a surfactant, adding a PTFE emulsion, stirring, carrying out low temperature drying, and carrying out high temperature heat treatment to obtain a PTFE and carbon black mixed powder material; the mixed powder is subjected to sanding treatment, and hydrophobic carbon black is obtained; (2) mixing hydrophobic carbon black, a solvent and a surfactant, and stirring to obtain microporous layer slurry; the microporous layer slurry prepared by the method is not easy to demulsify and good in rheological property, a microporous layer prepared by adopting the microporous layer slurry is uniform and flat, and the durability of a further obtained gas diffusion layer is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of proton exchange membrane fuel cells, and in particular relates to a method for preparing microporous layer slurry, a gas diffusion layer and a membrane electrode assembly. Background Art

[0002] Proton exchange membrane fuel cells (PEMFC) have the advantages of low operating temperature, high energy conversion efficiency, low noise and no pollution, and are favored by many experts and scholars. The membrane electrode assembly (MEA) is usually composed of a proton exchange membrane, a catalyst layer and a gas diffusion layer (GDL), and is a key core component of PEMFC. Among them, the GDL mainly plays the role of supporting the catalyst layer, draining water and transferring gas, conducting electricity and heat, etc., affecting the battery performance of the fuel cell at high current density, determining the upper limit of the fuel cell performance, and playing a vital role.

[0003] GDL includes a microporous layer and a substrate layer, wherein the microporous layer is crucial to the water and gas management of the fuel cell, especially plays a decisive role in the battery performance at high current density. Therefore, the structural design and morphology of the microporous layer determine the overall performance of the GDL. In the related art, the preparation method of the microporous layer is generally to obtain a microporous layer slurry by mixing PTFE emulsion, conductive carbon material and solvent, and then prepare the GDL through a coating process. This method has the following problems: ① PTFE emulsion is easy to demulsify, resulting in poor uniformity and stability of the microporous layer slurry; ② The uniformity of the conductive carbon material and the hydrophobic resin coating of the prepared microporous layer slurry is poor, resulting in poor uniformity of hydrophilicity and hydrophobicity of GDL in the fuel cell, resulting in unstable performance; ③ The PTFE inside the prepared microporous layer is easy to lose, resulting in the gradual deterioration of the hydrophobicity of GDL and poor durability.

[0004] Therefore, how to prepare GDL with good comprehensive performance has received more and more attention. Summary of the invention

[0005] The present invention is based on the inventor's discovery and understanding of the following facts and problems:

[0006] CN 114335570 A grafts a hydrophobic agent onto a hydrophilic conductive carbon surface by chemical grafting to prepare super-hydrophobic conductive carbon, and then sprays the hydrophobic conductive carbon onto a carbon paper substrate to form a microporous layer in a gas diffusion layer. The chemical grafting method of this method has poor controllability, and the grafted silane-modified carbon powder has poor conductivity. In addition, the carbon paper substrate of the gas diffusion layer prepared in this patent has not been subjected to hydrophobic treatment, and the hydrophobicity of the carbon paper substrate is poor, resulting in poor water and gas management of the entire GDL.

[0007] CN 114335569 AHydrophilically modified conductive resin powder, hydrophilically modified conductive medium powder and hydrophobic agent powder are uniformly mixed to obtain a composite microporous layer dry powder; the composite microporous layer dry powder is uniformly coated on the surface of a porous support layer close to a catalytic layer, and a microporous layer is obtained after heat treatment. The conductive carbon powder and the hydrophobic agent material in the microporous layer prepared by the method have poor mixing uniformity, and during the actual operation of the fuel cell, poor hydrophilic and hydrophobic uniformity and poor water vapor management capability occur.

[0008] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the embodiment of the present invention provides a method for preparing a microporous layer slurry, wherein the microporous layer slurry prepared by the method is not easy to demulsify and has good rheological properties, and the microporous layer prepared by the microporous layer slurry is uniform and flat, and the durability of the obtained gas diffusion layer is further enhanced, which solves the shortcomings of the related art in that the PTFE emulsion is easy to demulsify during the preparation of the microporous layer slurry, the microporous layer slurry has poor rheological properties and stability, the PTFE and conductive carbon material have poor coating, and the PTFE in the microporous layer slurry is easy to lose.

[0009] The method for preparing the microporous layer slurry according to the embodiment of the present invention comprises the following steps:

[0010] (1) dispersing carbon black, solvent and surfactant, adding PTFE emulsion, stirring, drying at low temperature and then performing high temperature heat treatment to obtain a mixed powder material of PTFE and carbon black; sand grinding the mixed powder material to obtain hydrophobic carbon black;

[0011] (2) The hydrophobic carbon black, solvent and surfactant obtained in step (1) are mixed and stirred to obtain a microporous layer slurry.

[0012] The advantages and technical effects brought by the preparation method of the microporous layer slurry of the embodiment of the present invention are as follows: 1. The method of the embodiment of the present invention adopts a wet mixing method and adds a surfactant thereto, which has a better mixing effect, and the obtained microporous layer slurry has better uniformity and stability; 2. The method of the embodiment of the present invention adds PTFE emulsion to the system and then adopts a process of low-temperature drying first and then high-temperature drying, which can strictly control the drying temperature so that the obtained carbon black has good hydrophobic properties.

[0013] In some embodiments, in step (1) and / or step (2), the solvent comprises at least one of water, isopropanol, n-propanol, ethanol or n-butanol;

[0014] And / or, the carbon black includes at least one of XC-72R, BP2000, acetylene black, Ketjen black, graphite powder or expanded graphite.

[0015] In some embodiments, in step (1) and / or step (2), the surfactant includes at least one of Triton X-100, Tween 60, polyethylene glycol isooctylphenyl ether or fatty alcohol polyoxyethylene ether.

[0016] In some embodiments, in step (1), the temperature of the low-temperature drying is 60 to 80° C., and the time of the low-temperature drying is 5 to 30 minutes;

[0017] And / or, the temperature of the high temperature heat treatment is 300-450° C., and the time of the high temperature heat treatment is 0.5-2 h;

[0018] And / or, the sand milling treatment time is 20 to 50 minutes, and the ball milling treatment speed is 800 to 1200 r / min.

[0019] In some embodiments, in step (1), the mass ratio of carbon black, solvent and surfactant is 0.1-1:1-10:0.01-1;

[0020] And / or, the mass ratio of the PTFE to the carbon black is 1-4:2-8.

[0021] In some embodiments, in step (2), the mass ratio of the hydrophobic carbon black, the solvent and the surfactant is 0.1-1:1-10:0.01-0.5;

[0022] And / or, in the step (2), the stirring treatment includes grinding in a nano-grinder, and the grinding time is 20 to 40 minutes.

[0023] The embodiment of the present invention also provides a method for preparing a gas diffusion layer, comprising the following steps: coating the microporous layer slurry prepared by the above preparation method on a hydrophobic treated carbon paper substrate, first performing a drying treatment, and then performing a high temperature treatment.

[0024] The advantages and technical effects brought by the preparation method of the gas diffusion layer of the embodiment of the present invention are as follows: 1. The method of the embodiment of the present invention can produce a gas diffusion layer with better conductivity and durability, superior uniformity and strong water vapor management capabilities; 2. The method of the embodiment of the present invention can be a roll-to-roll automated process with high production efficiency, which is conducive to mass production.

[0025] In some embodiments, the coating method includes slot extrusion coating;

[0026] And / or, the temperature of the drying treatment is 60-120° C., and the dry thickness after the drying treatment is 20-30 μm;

[0027] And / or, the temperature of the high temperature treatment is 350-400° C., and the time of the high temperature treatment is 10-30 minutes.

[0028] The embodiment of the present invention further provides a gas diffusion layer, which is manufactured by the above method.

[0029] An embodiment of the present invention further provides a membrane electrode assembly, comprising a gas diffusion layer prepared by the above preparation method or the above gas diffusion layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic diagram of the process of preparing a gas diffusion layer in Example 1;

[0031] Figure 2 is a polarization curve diagram of a single cell composed of membrane electrodes prepared in Example 1 and Comparative Example 1;

[0032] Figure 3 is a rheological curve diagram of the microporous layer slurry prepared in Example 1 and Comparative Example 1;

[0033] Figure 4 It is a comparison diagram of the contact angles of the gas diffusion layers prepared in Example 1 and Comparative Example 1 before and after acid boiling durability. DETAILED DESCRIPTION

[0034] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0035] The method for preparing the microporous layer slurry according to the embodiment of the present invention comprises the following steps:

[0036] (1) dispersing carbon black, solvent and surfactant, adding PTFE emulsion, stirring, drying at low temperature and then heat treating to obtain a mixed powder of PTFE and carbon black; sand grinding the mixed powder to obtain hydrophobic carbon black;

[0037] (2) The hydrophobic carbon black, solvent and surfactant obtained in step (1) are mixed and stirred to obtain a microporous layer slurry.

[0038] The preparation method of the microporous layer slurry in the embodiment of the present invention adopts a wet mixing method and adds a surfactant thereto, which has a better mixing effect, and the obtained microporous layer slurry has better uniformity and stability; the method of the embodiment of the present invention adds the PTFE emulsion to the system, and then adopts a process of low-temperature drying and then high-temperature drying, which can strictly control the drying temperature so that the obtained carbon black has good hydrophobic properties.

[0039] In some embodiments, preferably, in step (1) and / or step (2), the solvent comprises at least one of water, isopropanol, n-propanol, ethanol or n-butanol. Further preferably, the solvent is water.

[0040] In some embodiments, preferably, in step (1) and / or step (2), the carbon black comprises at least one of XC-72R, BP2000, acetylene black, Ketjen black, graphite powder or expanded graphite. Further preferably, the carbon black comprises at least one of XC-72R, BP2000 or acetylene black.

[0041] In some embodiments, preferably, in step (1) and / or step (2), the surfactant comprises at least one of Triton X-100, Tween 60, polyethylene glycol isooctylphenyl ether or fatty alcohol polyoxyethylene ether. Further preferably, the surfactant is Triton X-100.

[0042] In some embodiments, preferably, in the step (1), the dispersion treatment comprises ball milling, the ball milling time is 20 to 50 minutes, and the ball milling speed is 300 to 500 r / min.

[0043] In some embodiments, preferably, in the step (1), the stirring treatment comprises ball milling, the ball milling time is 20 to 50 minutes, and the ball milling speed is 200 to 300 r / min.

[0044] In some embodiments, preferably, in step (1), the temperature of the low-temperature drying is 60 to 80° C., and the time of the low-temperature drying is 5 to 30 minutes;

[0045] And / or, the temperature of the high temperature heat treatment is 300-450° C., and the time of the high temperature heat treatment is 0.5-2 h;

[0046] And / or, the sand milling treatment time is 20 to 50 minutes, and the ball milling treatment speed is 800 to 1200 r / min.

[0047] In some embodiments, preferably, in the step (1), the mass ratio of the carbon black, the solvent and the surfactant is 0.1-1:1-10:0.01-1;

[0048] And / or, the mass ratio of the PTFE to the carbon black is 1-4:2-8.

[0049] In the embodiments of the present invention, the mass ratio of PTFE and carbon black is optimized, and the prepared hydrophobic carbon black has excellent hydrophobicity and conductivity; if the amount of PTFE is too low, the prepared carbon black has poor hydrophobicity; if the amount of PTFE is too high, the prepared carbon black coverage is too high and the carbon black has poor conductivity.

[0050] In some embodiments, preferably, in the step (2), the mass ratio of the hydrophobic carbon black, the solvent and the surfactant is 0.1-1:1-10:0.01-0.5.

[0051] In some embodiments, preferably, in the step (2), the stirring treatment comprises grinding in a nano-grinder, and the grinding time is 20 to 40 minutes.

[0052] In the embodiment of the present invention, the hydrophobic carbon black can be dispersed more fully by grinding, thereby further ensuring the performance of the gas diffusion layer prepared subsequently.

[0053] The embodiment of the present invention also provides a method for preparing a gas diffusion layer, comprising the following steps: coating the microporous layer slurry prepared by the above preparation method on a hydrophobic treated carbon paper substrate, first performing a drying treatment, and then performing a high temperature treatment.

[0054] The method for preparing a gas diffusion layer in an embodiment of the present invention has better conductivity and durability, and has excellent uniformity and strong water vapor management capabilities; the method in an embodiment of the present invention has a roll-to-roll automated process, high production efficiency, and is conducive to mass production.

[0055] In some embodiments, preferably, the coating method includes slot extrusion coating;

[0056] And / or, the temperature of the drying treatment is 60-120° C., and the dry thickness after the drying treatment is 20-30 μm;

[0057] And / or, the temperature of the high temperature treatment is 350-400° C., and the time of the high temperature treatment is 10-30 minutes.

[0058] The embodiment of the present invention further provides a gas diffusion layer, which is manufactured by the above method.

[0059] An embodiment of the present invention further provides a membrane electrode assembly, comprising a gas diffusion layer prepared by the above preparation method or the above gas diffusion layer.

[0060] The technical solution of the present invention is described in detail below in conjunction with specific embodiments and drawings.

[0061] Example 1

[0062] The process of preparing GDL in this embodiment is as follows Figure 1 As shown:

[0063] (1) Preparation of microporous layer slurry: 1 g of surfactant Triton X-100, 100 g of carbon black XC-72R and 1000 g of water were ball-milled in a ball mill for 30 min at a speed of 450 r / min, and then 50 g of PFFE emulsion (60% wt) was added to the above mixture and ball-milled for 30 min at a speed of 250 r / min to form a mixture, which was then dried at 80°C for 10 min and finally dried at 400°C for 1 h, and then sand-milled in a sand mill for 30 min at a speed of 1000 r / min to prepare hydrophobic carbon black XC-72R; 130 g of carbon black XC-72R with uniform hydrophobicity, 1300 g of water and 1.3 g of surfactant Triton X-100 were ground in a nano-grinder for 30 min to form a uniform and stable bright black ink-like microporous layer slurry;

[0064] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the roll-to-roll carbon paper substrate after hydrophobic treatment by slot extrusion coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high-temperature treated at 390°C for 25 min;

[0065] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0066] Example 2

[0067] (1) Preparation of microporous layer slurry: 1 g of surfactant Triton X-100, 100 g of carbon black BP2000 and 1000 g of water were ball-milled in a ball mill for 30 min at a speed of 450 r / min, and then 50 g of PFFE emulsion (60% wt) was added to the above mixture and ball-milled for 30 min at a speed of 250 r / min to form a mixture, which was then dried at 80°C for 10 min and finally dried at 400°C for 1 h, and then sand-milled in a sand mill for 30 min at a speed of 1000 r / min to prepare hydrophobic carbon black BP2000; 130 g of carbon black BP2000 with uniform hydrophobicity, 1300 g of water and 1.3 g of surfactant Triton X-100 were ground in a nano-grinder for 30 min to form a uniform and stable bright black ink-like microporous layer slurry;

[0068] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry was applied onto the hydrophobic treated roll-to-roll carbon paper substrate by slot extrusion coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high temperature treatment was performed at 390°C for 250 min;

[0069] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0070] Example 3

[0071] (1) Preparation of microporous layer slurry: 1 g of surfactant Triton X-100, 100 g of acetylene black and 1000 g of water were ball milled in a ball mill for 30 min at a speed of 450 r / min, and then 50 g of PFFE emulsion (60% wt) was added to the above mixture and ball milled for 30 min at a speed of 250 r / min to form a mixture, which was then dried at 80° C. for 10 min and finally dried at 400° C. for 1 h, and then sand milled in a sand mill for 30 min at a speed of 1000 r / min to prepare hydrophobic carbon black; 130 g of acetylene black carbon black with uniform hydrophobicity, 1300 g of water and 1.3 g of surfactant Triton X-100 were ground in a nano grinder for 30 min to form a uniform and stable bright black ink-like microporous layer slurry;

[0072] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the roll-to-roll carbon paper substrate after hydrophobic treatment by slot extrusion coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high-temperature treated at 390°C for 25 min;

[0073] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0074] Example 4

[0075] (1) Preparation of microporous layer slurry: 1 g of surfactant Triton X-100, 100 g of carbon black XC-72R and 1000 g of water were ball-milled in a ball mill for 30 min at a speed of 450 r / min, and then 30 g of PFFE emulsion (60% wt) was added to the above mixture and ball-milled for 30 min at a speed of 250 r / min to form a mixture, which was then dried at 80°C for 10 min and finally dried at 400°C for 1 h, and then sand-milled in a sand mill for 30 min at a speed of 1000 r / min to prepare hydrophobic carbon black XC-72R; 130 g of carbon black XC-72R with uniform hydrophobicity, 1300 g of water and 1.3 g of surfactant Triton X-100 were ground in a nano-grinder for 30 min to form a uniform and stable bright black ink-like microporous layer slurry;

[0076] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry was applied onto the hydrophobic treated roll-to-roll carbon paper substrate by slot extrusion coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high temperature treatment was performed at 390°C for 25 min;

[0077] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0078] Example 5

[0079] (1) Preparation of microporous layer slurry: 1 g of surfactant Triton X-100, 100 g of carbon black XC-72R and 1000 g of water were ball-milled in a ball mill for 30 min at a speed of 450 r / min, and then 100 g of PFFE emulsion (60% wt) was added to the above mixture and ball-milled for 30 min at a speed of 250 r / min to form a mixture, which was then dried at 80° C. for 10 min and finally dried at 400° C. for 1 h, and then sand-milled in a sand mill for 30 min at a speed of 1000 r / min to prepare hydrophobic carbon black XC-72R; 130 g of carbon black XC-72R with uniform hydrophobicity, 1300 g of water and 1.3 g of surfactant Triton X-100 were ground in a nano-grinder for 30 min to form a uniform and stable bright black ink-like microporous layer slurry;

[0080] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the roll-to-roll carbon paper substrate after hydrophobic treatment by slot extrusion coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high-temperature treated at 390°C for 25 min;

[0081] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0082] Example 6

[0083] (1) Preparation of microporous layer slurry: 1 g of surfactant Triton X-100, 100 g of carbon black BP2000 and 1000 g of water were ball-milled in a ball mill for 30 min at a speed of 450 r / min, and then 30 g of PFFE emulsion (60% wt) was added to the above mixture and ball-milled for 30 min at a speed of 250 r / min to form a mixture, which was then dried at 80°C for 10 min and finally dried at 400°C for 1 h, and then sand-milled in a sand mill for 30 min at a speed of 1000 r / min to prepare hydrophobic carbon black BP2000; 130 g of carbon black BP2000 with uniform hydrophobicity, 1300 g of water and 1.3 g of surfactant Triton X-100 were ground in a nano-grinder for 30 min to form a uniform and stable bright black ink-like microporous layer slurry;

[0084] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the roll-to-roll carbon paper substrate after hydrophobic treatment by slot extrusion coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high-temperature treated at 390°C for 25 min;

[0085] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0086] Example 7

[0087] (1) preparing a microporous layer slurry, 1g of surfactant Triton X-100, 100g of carbon black BP2000 and 1000g of water, ball milled in a ball mill for 30min at a speed of 450r / min, then adding 100g of PFFE emulsion (60%wt) to the above mixture, ball milled for 30min at a speed of 250r / min to form a mixture, then dried at 80°C for 10min, and finally dried at 400°C for 1h, and then sand milled in a sand mill for 30min at a speed of 1000r / min to prepare hydrophobic carbon black BP2000; 130g of carbon black BP2000 with uniform hydrophobicity, 1300g of water and 1.3g of surfactant Triton X-100, ground in a nano grinder for 30min to form a uniform and stable bright black ink-like microporous layer slurry;

[0088] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the roll-to-roll carbon paper substrate after hydrophobic treatment by slot extrusion coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high-temperature treated at 390°C for 25 min;

[0089] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0090] Example 8

[0091] (1) Preparation of microporous layer slurry: 1 g of surfactant Triton X-100, 100 g of acetylene black and 1000 g of water were ball-milled in a ball mill for 30 min at a speed of 450 r / min, and then 30 g of PFFE emulsion (60% wt) was added to the above mixture and ball-milled for 30 min at a speed of 250 r / min to form a mixture, which was then dried at 80° C. for 10 min and finally dried at 400° C. for 1 h, and then sand-milled in a sand mill for 30 min at a speed of 1000 r / min to prepare hydrophobic acetylene black; 130 g of acetylene black with uniform hydrophobicity, 1300 g of water and 1.3 g of surfactant Triton X-100 were ground in a nano-grinder for 30 min to form a uniform and stable bright black ink-like microporous layer slurry;

[0092] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the roll-to-roll carbon paper substrate after hydrophobic treatment by slot extrusion coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high-temperature treated at 390°C for 25 min;

[0093] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0094] Example 9

[0095] (1) Preparation of microporous layer slurry: 1 g of surfactant Triton X-100, 100 g of acetylene black and 1000 g of water were ball-milled in a ball mill for 30 min at a speed of 450 r / min, and then 100 g of PFFE emulsion (60% wt) was added to the above mixture and ball-milled for 30 min at a speed of 250 r / min to form a mixture, which was then dried at 80° C. for 10 min and finally dried at 400° C. for 1 h, and then sand-milled in a sand mill for 30 min at a speed of 1000 r / min to prepare hydrophobic acetylene black; 130 g of acetylene black with uniform hydrophobicity, 1300 g of water and 1.3 g of surfactant Triton X-100 were ground in a nano-grinder for 30 min to form a uniform and stable bright black ink-like microporous layer slurry;

[0096] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the roll-to-roll carbon paper substrate after hydrophobic treatment by slot extrusion coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high-temperature treated at 390°C for 25 min;

[0097] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0098] Comparative Example 1

[0099] (1) Preparation of microporous layer slurry: 2.3 g of surfactant X-100, 100 g of carbon black XC-72R and 2300 g of water were ball milled in a ball mill for 30 min at a speed of 450 r / min, and then 50 g of PFFE emulsion (60% wt) was added to the above mixture and ball milled for 30 min at a speed of 250 r / min to form a bright black ink-like microporous layer slurry;

[0100] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the hydrophobic treated sheet carbon paper substrate by doctor blade coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high temperature treatment was performed at 390°C for 25 min;

[0101] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0102] Comparative Example 2

[0103] (1) Preparation of microporous layer slurry: 2.3 g of surfactant Triton X-100, 100 g of carbon black BP2000 and 2300 g of water were ball milled in a ball mill for 30 min at a speed of 450 r / min, and then 50 g of PFFE emulsion (60% wt) was added to the above mixture and ball milled for 30 min at a speed of 250 r / min to form a bright black ink-like microporous layer slurry;

[0104] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the hydrophobic treated sheet carbon paper substrate by doctor blade coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high temperature treatment was performed at 390°C for 25 min;

[0105] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0106] Comparative Example 3

[0107] (1) Preparation of microporous layer slurry: 2.3 g of surfactant Triton X-100, 100 g of acetylene black and 2300 g of water were ball milled in a ball mill for 30 min at a speed of 450 r / min, and then 50 g of PFFE emulsion (60% wt) was added to the above mixture and ball milled for 30 min at a speed of 250 r / min to form a bright black ink-like microporous layer slurry;

[0108] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the hydrophobic treated sheet carbon paper substrate by doctor blade coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high temperature treatment was performed at 390°C for 25 min;

[0109] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0110] Comparative Example 4

[0111] (1) Preparation of microporous layer slurry: 1 g of surfactant Triton X-100, 100 g of carbon black XC-72R and 1000 g of water were ball-milled in a ball mill for 30 min at a speed of 450 r / min, and then 50 g of PFFE emulsion (60% wt) was added to the above mixture and ball-milled for 30 min at a speed of 250 r / min to form a mixture, which was then dried at 400° C. for 70 min and then sand-milled in a sand mill for 30 min at a speed of 1000 r / min to prepare hydrophobic carbon black XC-72R; 130 g of carbon black XC-72R with uniform hydrophobicity, 1300 g of water and 1.3 g of surfactant Triton X-100 were ground in a nano-grinder for 30 min to form a uniform and stable bright black ink-like microporous layer slurry;

[0112] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the roll-to-roll carbon paper substrate after hydrophobic treatment by slot extrusion coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high-temperature treated at 390°C for 25 min;

[0113] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0114] Comparative Example 5

[0115] (1) Preparation of microporous layer slurry: 1 g of surfactant Triton X-100, 100 g of carbon black XC-72R and 1000 g of water were ball-milled in a ball mill for 30 min at a speed of 450 r / min, and then 50 g of PFFE emulsion (60% wt) was added to the above mixture and ball-milled for 30 min at a speed of 250 r / min to form a mixture, which was then dried at 80° C. for 70 min and then sand-milled in a sand mill for 30 min at a speed of 1000 r / min to prepare hydrophobic carbon black XC-72R; 130 g of carbon black XC-72R with uniform hydrophobicity, 1300 g of water and 1.3 g of surfactant Triton X-100 were ground in a nano-grinder for 30 min to form a uniform and stable bright black ink-like microporous layer slurry;

[0116] (2) Preparation of gas diffusion layer (GDL): The microporous layer slurry prepared above was applied to the roll-to-roll carbon paper substrate after hydrophobic treatment by slot extrusion coating, and then dried at 80°C; the thickness after drying was 30 μm, and then high-temperature treated at 390°C for 25 min;

[0117] (3) Preparation of membrane electrode assembly (MEA): The prepared GDL-matched catalyst coated membrane (CCM, manufactured by GuoHydrogen Technology) is made into a membrane electrode.

[0118] Single cell assembly and testing: The membrane electrodes prepared in Examples 1 to 9 and Comparative Examples 1 to 5 were assembled into a single cell, and the cell performance was tested using a fuel cell testing system. The test conditions were: cell temperature: T = 80°C, humidity: RH = 40% / 40%, back pressure: BP = 100 kpa / 100 kpa, excess coefficient: STO = 1.5 / 2.0. The test results are shown in Table 1.

[0119] Table 1 GDL resistance comparison table

[0120] Sample name <![CDATA[Vertical resistance @ 1 MPa (mΩ.cm 2 )]]> Example 1 7 Example 2 8 Example 3 8.6 Example 4 6.5 Example 5 7.4 Example 6 7.7 Example 7 8.8 Example 8 8 Example 9 9.2 Comparative Example 1 12.2 Comparative Example 2 13.1 Comparative Example 3 13.8 Comparative Example 4 9.5 Comparative Example 5 10.2

[0121] A fuel cell test bench was used, and the operating conditions were set as follows: battery temperature: 80°C, excess coefficient: anode: cathode = 1.5 / 2.0, humidity: anode: cathode = 40% / 40%, back pressure: anode: cathode = 100 kPa / 100 kPa, and the battery performance of the single cell composed of the membrane electrode prepared in Example 1, Comparative Example 1, Comparative Example 4 and Comparative Example 5 was tested. The results are shown in Table 2, where the polarization curves of Example 1 and Comparative Example 1 are shown in Table 2. Figure 2 As shown in Table 2 and Figure 2 It can be seen that the battery performance of Example 1 is significantly better than that of Comparative Examples 1, 4 and 5, especially at high current density (≥2500mA / cm 2, mass transfer polarization zone), the battery performance advantage of Example 1 is more obvious. After analysis, since the microporous layer slurry of the embodiment adopts hydrophobic conductive carbon black, the uniformity of the conductive carbon material and the PTFE hydrophobic material coating in the slurry is better, which is beneficial to improving the water and gas management ability of the battery, especially under high current density, when the battery produces more water, its advantage is more obvious.

[0122] Table 2 Comparison of battery performance under GDL typical electric density

[0123] Sample name <![CDATA[Battery performance @ 1.0 A / cm 2 > <![CDATA[Battery performance @ 2.5 A / cm 2 > <![CDATA[Battery performance @ 3.0 A / cm 2 > Example 1 0.757V 0.664V 0.634V Comparative Example 1 0.756V 0.625V 0.591V Comparative Example 4 0.741V 0.611V 0.572V Comparative Example 5 0.748V 0.6V 0.553V

[0124] The rheological curves of the microporous layer slurry obtained in Example 1 and Comparative Example 1 were tested by a rheometer. The results are as follows: Figure 3 As shown, from Figure 3 It can be seen from the figure that the slurry prepared in Comparative Example 1 has a shear rate of >10s -1 When the rheological curve is fluctuating, the slurry begins to be unstable, while the rheological curve of the microporous layer slurry prepared in Example 1 is always smooth. This shows that compared with Comparative Example 1, the microporous layer slurry prepared in the manner of Example 1 has better rheological properties and better stability, which is conducive to roll-to-roll slit coating and mass production.

[0125] The gas diffusion layers prepared in Example 1 and Comparative Example 1 were immersed in a 1 mol / L sulfuric acid solution and tested continuously for 500 h in a water bath at 80°C. The contact angles of the gas diffusion layers before and after acid boiling were monitored simultaneously. Figure 4 As shown, from Figure 4 It can be seen that after 500 hours of sulfuric acid boiling, the contact angle of the gas diffusion layer prepared in Example 1 decreased from the original 153° to 148°, with a decay rate of 3.26%; while the contact angle of the gas diffusion layer prepared in Comparative Example 1 decreased from the original 151° to 133°, with a decay rate of 11.92%, indicating that the anti-loss property of PTFE in Example 1 is significantly enhanced, thereby greatly improving the durability of GDL.

[0126] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0127] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A method for preparing a microporous layer slurry, characterized in that: The following steps are involved: (1) dispersing carbon black, solvent and surfactant, adding PTFE emulsion, stirring, drying at low temperature and then performing high temperature heat treatment to obtain a mixed powder material of PTFE and carbon black; sand grinding the mixed powder material to obtain hydrophobic carbon black; (2) The hydrophobic carbon black, solvent and surfactant obtained in step (1) are mixed and stirred to obtain a microporous layer slurry.

2. The method for preparing the microporous layer slurry according to claim 1, characterized in that: In step (1) and / or step (2), the solvent comprises at least one of water, isopropanol, n-propanol, ethanol or n-butanol; And / or, the carbon black includes at least one of XC-72R, BP2000, acetylene black, Ketjen black, graphite powder or expanded graphite.

3. The method for preparing the microporous layer slurry according to claim 1, characterized in that: In the step (1) and / or the step (2), the surfactant includes at least one of Triton X-100, Tween 60, polyethylene glycol isooctylphenyl ether or fatty alcohol polyoxyethylene ether.

4. The method for preparing the microporous layer slurry according to claim 1, characterized in that: In the step (1), the temperature of the low-temperature drying is 60 to 80° C., and the time of the low-temperature drying is 5 to 30 minutes; And / or, the temperature of the high temperature heat treatment is 300-450° C., and the time of the high temperature heat treatment is 0.5-2 h; And / or, the sand milling treatment time is 20 to 50 minutes, and the ball milling treatment speed is 800 to 1200 r / min.

5. The method for preparing the microporous layer slurry according to claim 1, characterized in that: In the step (1), the mass ratio of the carbon black, the solvent and the surfactant is 0.1-1:1-10:0.01-1; And / or, the mass ratio of the PTFE to the carbon black is 1-4:2-8.

6. The method for preparing the microporous layer slurry according to claim 1, characterized in that: In the step (2), the mass ratio of the hydrophobic carbon black, the solvent and the surfactant is 0.1-1:1-10:0.01-0.5; And / or, in the step (2), the stirring treatment includes grinding in a nano-grinder, and the grinding time is 20 to 40 minutes.

7. A method for preparing a gas diffusion layer, characterized in that: The following steps are involved: The microporous layer slurry prepared by the preparation method according to any one of claims 1 to 6 is coated on the hydrophobic treated carbon paper substrate, firstly subjected to drying treatment, and then subjected to high temperature treatment.

8. The method for preparing a gas diffusion layer according to claim 7, characterized in that: The coating method includes slot extrusion coating; And / or, the temperature of the drying treatment is 60-120° C., and the dry thickness after the drying treatment is 20-30 μm; And / or, the temperature of the high temperature treatment is 350-400° C., and the time of the high temperature treatment is 10-30 minutes.

9. A gas diffusion layer, characterized in that: The preparation is obtained by the preparation method described in claim 7 or 8.

10. A membrane electrode assembly, characterized in that: It comprises a gas diffusion layer prepared by the preparation method according to claim 7 or 8 or a gas diffusion layer according to claim 9.

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