Catalyst slurry and preparation, CCM and preparation and membrane electrode

Abstract

The present invention provides a catalyst slurry and preparation thereof, CCM and preparation thereof and membrane electrode, wherein the catalyst slurry comprises a catalyst, a perfluorosulfonic acid resin dispersion and a solvent; wherein the perfluorosulfonic acid resin dispersion comprises a perfluorosulfonic acid resin and a dispersant, and the perfluorosulfonic acid resin dispersion is heated at a temperature of 25°C and a shear rate of 10s ‑1 The viscosity under the conditions is 500 to 700 cP, the solvent includes water and a first alcohol, the first alcohol is an alcohol having less than 3 carbon atoms, and the weight ratio of water to the first alcohol is (1 to 4):1. The catalyst slurry provided by the present invention can significantly alleviate the occurrence of cracks when preparing CCM, and the membrane electrode prepared therefrom has excellent electrochemical performance.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and in particular to a catalyst slurry and its preparation, a CCM and its preparation, and a membrane electrode. Background Art

[0002] The membrane electrode, as the core component of a fuel cell, is primarily composed of an anode gas diffusion layer, an anode catalyst layer, a proton exchange membrane, a cathode catalyst layer, and a cathode gas diffusion layer. The three-in-one component consisting of the anode catalyst layer, proton exchange membrane, and cathode catalyst layer is called a catalyst-coated membrane for membrane electrode, or CCM (Catalyst Coated Membrane). Currently, most CCMs are manufactured using a hot press transfer method, in which a catalyst slurry is first applied to a transfer base membrane, and then transferred from the transfer base membrane to the proton exchange membrane under certain temperature and pressure conditions.

[0003] In the past two years, some membrane electrode manufacturers (such as Hongji, Qingdong, and Jie Hydrogen Technology) have adopted a single-sided or double-sided direct coating method to prepare CCM. The process is to directly apply the catalyst slurry to the proton exchange membrane, and then prepare the CCM through a heating and drying process. Compared with the preparation method of hot pressing transfer, the preparation method of double-sided direct coating has the characteristics of fewer production steps and high production efficiency. In addition, due to the smaller interface contact resistance between the catalyst layer and the proton exchange membrane, the performance of the produced membrane electrode is higher and the stability of batch production is better. According to statistics, the annual output of membrane electrodes prepared by this method is 10 to 100 times that of the hot pressing transfer method.

[0004] However, as research and development progressed, researchers discovered that the double-sided direct coating method for preparing CCMs placed high demands on the slurry. Directly coating the slurry onto the proton exchange membrane using a conventional hot-press transfer system can easily crack the catalyst layer after drying, which in turn affects the performance of the membrane electrode. Consequently, there is an urgent need to provide a catalyst slurry that can address the existing cracking issues associated with CCM preparation, which can lead to poor membrane electrode battery performance. Summary of the Invention

[0005] The main purpose of the present invention is to provide a catalyst slurry and its preparation, CCM and its preparation and membrane electrode, so as to solve the problem that cracks are easily generated when preparing CCM in the prior art, thereby resulting in poor battery performance of the membrane electrode.

[0006] In order to achieve the above object, according to one aspect of the present invention, a catalyst slurry is provided, which includes a catalyst, a perfluorosulfonic acid resin dispersion and a solvent; wherein the perfluorosulfonic acid resin dispersion includes a perfluorosulfonic acid resin and a dispersant, and the perfluorosulfonic acid resin dispersion is heated at a temperature of 25°C and a shear rate of 10S -1The viscosity under the conditions is 500-700 cP; the solvent includes water and a first alcohol, the first alcohol is an alcohol with a carbon number less than 3, and the weight ratio of water to the first alcohol is (1-4):1.

[0007] Furthermore, the weight content of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 15 to 25 wt %; preferably, the EW of the perfluorosulfonic acid resin is 700 to 900 g / mol; preferably, the dispersant includes water and a second alcohol; preferably, the weight ratio of water to the second alcohol in the dispersant is (1 to 3): (1 to 4); preferably, the second alcohol is selected from one or more of ethanol, n-propanol, isopropanol, n-butanol or tert-butanol; preferably, the second alcohol is ethanol and n-propanol, and further preferably, the weight ratio of ethanol to n-propanol is (3 to 1): (2 to 1).

[0008] Furthermore, in the catalyst slurry, the weight ratio of the catalyst, the perfluorosulfonic acid resin dispersion and the solvent is (1-2): (2-10): (10-25), preferably (1-2): (3-7): (10-15).

[0009] Furthermore, the catalyst is an anode catalyst or a cathode catalyst; preferably, the active component of the anode catalyst is platinum, ruthenium, iridium or an alloy thereof; preferably, the active component of the cathode catalyst is platinum, cobalt, nickel or an alloy thereof.

[0010] Furthermore, the catalyst slurry was heated at a temperature of 25°C and a shear rate of 10s -1 The viscosity under the conditions is 30 to 300 cP, preferably 60 to 160 cP; the D90 particle size of the solid particles in the catalyst slurry is preferably <2 μm, more preferably 0.5 to 1.5 μm.

[0011] To achieve the above object, according to one aspect of the present invention, a method for preparing a catalyst slurry is provided. The method comprises: mixing a catalyst, a solvent and a perfluorosulfonic acid resin dispersion to obtain a catalyst slurry.

[0012] Furthermore, the preparation method includes the following steps: step S1, after the catalyst and water are first mixed, the first alcohol and the perfluorosulfonic acid resin dispersion are sequentially added to the system for a second mixing to obtain slurry A; step S2, slurry A is pre-dispersed, ground, filtered and defoamed in sequence to obtain catalyst slurry.

[0013] Furthermore, the processing temperature of the first mixing is 15-25°C, and the processing time is 0.1-2h; preferably, the processing temperature of the second mixing is 10-25°C, and the processing time is 0.1-2h; preferably, the pre-dispersion is carried out in a homogenizer; preferably, the grinding is carried out in a ball mill; more preferably, the grinding speed is 1500-2500rpm, and the grinding time is 1-3h.

[0014] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a CCM is provided, which includes: a proton exchange membrane having a first surface and a second surface arranged opposite to each other; an anode catalyst coating arranged on the first surface of the proton exchange membrane; and a cathode catalyst coating arranged on the second surface of the proton exchange membrane; the slurry of the anode catalyst coating and / or the cathode catalyst coating is independently selected from the above-mentioned catalyst slurry, or the catalyst slurry obtained by the preparation method of the above-mentioned catalyst slurry.

[0015] Furthermore, the proton exchange membrane is a perfluorosulfonic acid proton exchange membrane; preferably, the thickness of the proton exchange membrane is 8 to 20 μm; preferably, the thickness of the anode catalyst coating is 1 to 5 μm; and preferably, the thickness of the cathode catalyst coating is 5 to 10 μm.

[0016] Furthermore, the preparation method of the CCM includes: providing a proton exchange membrane; the proton exchange membrane has a first surface and a second surface arranged opposite to each other; arranging an anode catalyst coating on the first surface of the proton exchange membrane; arranging a cathode catalyst coating on the second surface of the proton exchange membrane; the slurry of the anode catalyst coating and / or the cathode catalyst coating is independently selected from the above-mentioned catalyst slurry, or the catalyst slurry obtained by the preparation method of the above-mentioned catalyst slurry.

[0017] Furthermore, a slit coater is used to coat the anode catalyst slurry on the first surface of the proton exchange membrane to obtain an anode catalyst coating, and a cathode catalyst slurry is coated on the second surface of the proton exchange membrane to obtain a cathode catalyst coating.

[0018] Furthermore, after coating, the preparation method also includes passing the coated material through a first heating device, a second heating device and a third heating device in sequence at a feed speed of 3 to 10 m / min to perform a first heating treatment, a second heating treatment and a third heating treatment; preferably, the first heating treatment temperature is 20 to 40°C; preferably, the second heating treatment temperature is 60 to 100°C; preferably, the third heating treatment temperature is 30 to 60°C.

[0019] To achieve the above object, according to one aspect of the present invention, a membrane electrode is provided, comprising an anode gas diffusion layer, a CCM and a cathode gas diffusion layer, wherein the CCM is the above CCM or a CCM obtained by the above CCM preparation method.

[0020] The application of the catalyst slurry provided by the present invention in the preparation of CCM can significantly alleviate the occurrence of cracks, and the membrane electrode prepared therefrom has excellent electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 An optical microscope image of the CCM of Example 1 of the present invention is shown (magnification: 200 times);

[0023] Figure 2 An optical microscope image of the CCM of Example 2 of the present invention is shown (magnification: 200 times);

[0024] Figure 3 An optical microscope image of the CCM of Example 3 of the present invention is shown (magnification: 200 times);

[0025] Figure 4 An optical microscope image of the CCM of Example 4 of the present invention is shown (magnification: 200 times);

[0026] Figure 5 An optical microscope image of the CCM of Comparative Example 1 of the present invention is shown (magnification: 200 times);

[0027] Figure 6 An optical microscope image of the CCM of Comparative Example 6 of the present invention is shown (magnification: 200 times);

[0028] Figure 7 An optical microscope image (magnification: 200 times) of the CCM of Comparative Example 7 of the present invention is shown. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] Glossary:

[0031] EW: equivalent weight, the weight of perfluorosulfonic acid resin contained in each mole of perfluorosulfonic acid resin dispersion.

[0032] CCM: The three-in-one component consisting of an anode catalyst layer, a proton exchange membrane, and a cathode catalyst layer is called a catalyst-coated proton membrane for membrane electrode, abbreviated as CCM.

[0033] As described in the background technology section of the present invention, the catalyst slurry in the prior art has the problem of cracking easily during the preparation of CCM, which leads to poor electrochemical performance of the membrane electrode. In order to solve this problem, the present invention provides a catalyst slurry, which includes a catalyst, a perfluorosulfonic acid resin dispersion and a solvent; wherein the perfluorosulfonic acid resin dispersion includes a perfluorosulfonic acid resin and a dispersant, and the perfluorosulfonic acid resin dispersion is heated at a temperature of 25°C and a shear rate of 10s -1 The viscosity under the conditions is 500-700 cP; the solvent includes water and a first alcohol, the first alcohol is an alcohol with a carbon number less than 3, and the weight ratio of water to the first alcohol is (1-4):1.

[0034] The catalyst slurry provided by the present invention includes a catalyst, a perfluorosulfonic acid resin dispersion and a solvent, and the perfluorosulfonic acid resin dispersion is limited to a temperature of 25°C and a shear rate of 10S -1 The viscosity under these conditions is 500-700 cP. Limiting the viscosity of the perfluorosulfonic acid resin dispersion to the above range promotes physical crosslinking of the perfluorosulfonic acid resin in the slurry, increasing the degree of intertwining between the polymer chains of the perfluorosulfonic acid resin, thereby preventing cracking in the catalyst slurry during the subsequent preparation of the CCM, thereby improving the electrochemical performance of the membrane electrode. In particular, the present invention further adjusts the solvent in the catalyst slurry to water and a first alcohol with a carbon number less than 3, and controls the weight ratio of water to the first alcohol to (1-4):1. By adjusting the ratio of water to the first alcohol in the solvent of the catalyst slurry, the initially formed agglomerated particles on the CF main chain of the perfluorosulfonic acid resin can be reagglomerated under the action of the side chain sulfonate groups, water, and hydrogen ions on their surfaces, further forming larger agglomerates. Based on this, cracking due to shrinkage in the catalyst slurry during the subsequent preparation of the CCM can be further avoided, thereby improving the stability of the CCM and maintaining good air permeability after drying, increasing the gas transmission rate, and thus improving the electrochemical performance of the membrane electrode. For example, the viscosity of the perfluorosulfonic acid resin dispersion can be 500 cP, 590 cP, 600 cP, or 700 cP. The weight ratio of water to the first alcohol can be 1:1, 1.5:1, 2.3:1, or 4:1.

[0035] To more smoothly promote the physical crosslinking of the perfluorosulfonic acid resin in the dispersion, thereby stabilizing the polymer chain structure of the perfluorosulfonic acid resin, the perfluorosulfonic acid resin content in the perfluorosulfonic acid resin dispersion is preferably 15-25 wt%. To further stabilize the polymer chain structure of the perfluorosulfonic acid resin, the perfluorosulfonic acid resin equivalent weight (EW) is preferably 700-900 g / mol. To promote more uniform dispersion of the perfluorosulfonic acid resin in the dispersion and improve the stability of the perfluorosulfonic acid resin dispersion, the dispersant preferably includes water and a second alcohol. More preferably, the weight ratio of water to the second alcohol in the dispersant is (1-3):(1-4). To further reduce the swelling rate of the proton exchange membrane in the second alcohol and thus reduce cracking during the preparation of the CCM, the second alcohol is preferably selected from one or more of ethanol, n-propanol, isopropanol, n-butanol, or tert-butanol. More preferably, the second alcohol is ethanol and n-propanol. More preferably, the weight ratio of ethanol to n-propanol is (3-1):(2-1). Based on this, the product manufacturing cost is also lower and the prospects for industrial application are better.

[0036] To further enhance the interaction between perfluorosulfonic acid resin molecular chains and improve the stability of the catalyst slurry, thereby preventing cracking during the preparation of CCM, the weight ratio of catalyst, perfluorosulfonic acid resin dispersion, and solvent is preferably (1-2):(2-10):(10-25); more preferably (1-2):(3-7):(10-15). Furthermore, products prepared based on this controlled ratio exhibit superior performance.

[0037] In some optional embodiments, the catalyst may be an anode catalyst or a cathode catalyst. To further improve the catalytic performance of the catalyst slurry, the active component of the anode catalyst is preferably platinum, iridium, ruthenium, or an alloy thereof; more preferably, the active component of the cathode catalyst is platinum, cobalt, nickel, or an alloy thereof.

[0038] In a preferred embodiment, the catalyst slurry is heated at a temperature of 25°C and a shear rate of 10s -1 The viscosity under the conditions is 30 to 300 cP. For example, the viscosity of the catalyst slurry can be: 45 cP, 98 cP, 106 cP, 122 cP, 140 cP, 156 cP, 198 cP and 237 cP. Based on this, the slurry has better uniformity in the subsequent coating process, and is further preferably 60 to 160 cP. In order to obtain a catalyst coating with excellent performance and stability on the proton exchange membrane layer under a simpler and more convenient coating process. It is further preferred that the D90 particle size of the solid particles in the catalyst slurry is <2 μm. Based on this, the catalyst slurry has better dispersibility, which can further effectively avoid the generation of cracks in the subsequent preparation of CCM, and is further preferably 0.5 to 1.5 μm.

[0039] Another aspect of the present invention further provides a method for preparing a catalyst slurry, which comprises: mixing a catalyst, a solvent and a perfluorosulfonic acid resin dispersion to obtain a catalyst slurry.

[0040] In a preferred embodiment, the present invention adjusts the ratio of water and the first alcohol in the catalyst slurry solvent, so that the agglomerated particles initially formed on the CF main chain in the perfluorosulfonic acid resin can be reagglomerated under the action of the side chain sulfonate groups, water and hydrogen ions on its surface, further forming larger agglomerates. Based on this, it is possible to effectively avoid the catalyst slurry from cracking due to shrinkage during the subsequent preparation of CCM, thereby making the CCM have better stability, so that it still has good air permeability after drying, which can increase the gas transmission rate and thus improve the electrochemical performance of the membrane electrode. Furthermore, the present invention preferably adjusts the viscosity of the perfluorosulfonic acid resin dispersion to the above range, which can promote the physical cross-linking of the perfluorosulfonic acid resin in the slurry and increase the degree of mutual entanglement between the perfluorosulfonic acid resin polymer chains, thereby effectively avoiding the catalyst slurry from cracking during the subsequent preparation of CCM, thereby improving the electrochemical performance of the membrane electrode.

[0041] In a preferred embodiment, the method for preparing the catalyst slurry includes: step S1, after the catalyst and water are first mixed, the first alcohol and the perfluorosulfonic acid resin dispersion are sequentially added to the system for a second mixing to obtain slurry A; step S2, the above-mentioned slurry A is sequentially ground, filtered and defoamed to obtain the above-mentioned catalyst slurry.

[0042] Those skilled in the art can first mix the catalyst and water for a first time, and then sequentially add the first alcohol and the perfluorosulfonic acid resin dispersion to the system for a second mixing to obtain slurry A. Then, the above-mentioned slurry A is sequentially ground, filtered and defoamed to obtain the above-mentioned catalyst slurry. The catalyst slurry prepared by this method has better stability, thereby avoiding shrinkage and cracking during the drying process of coating and preparing CCM. Moreover, based on the above-mentioned catalyst slurry, the dried CCM has better air permeability, which can accelerate the transmission of gas and thus improve the electrochemical performance of the membrane electrode. In addition, the preparation method has the advantages of simple process and easy operation, which can better promote the large-scale production of the catalyst slurry, thereby making its industrial application prospects broader.

[0043] In a preferred embodiment, in the above-mentioned method for preparing the catalyst slurry, the first mixing and the second mixing are carried out by methods including, but not limited to, stirring, ball milling, ultrasound, nanodispersion, shear dispersion, or bead milling. In order to better promote the thorough mixing of the catalyst and water, the first mixing temperature is preferably 15 to 25°C and the processing time is 0.1 to 2 hours; in order to better promote the uniform mixing of the catalyst, water, the first alcohol, and the perfluorosulfonic acid resin dispersion and further improve the stability of the catalyst slurry, the second mixing temperature is preferably 10 to 25°C and the processing time is 0.1 to 2 hours; in order to further improve the uniformity and stability of the catalyst slurry, grinding is preferably carried out in a ball mill; further preferably, the grinding speed is 1500 to 2500 rpm and the grinding time is 1 to 3 hours.

[0044] Another aspect of the present invention provides a CCM comprising: a proton exchange membrane having a first surface and a second surface disposed opposite each other, an anode catalyst coating disposed on the first surface of the proton exchange membrane, and a cathode catalyst coating disposed on the second surface of the proton exchange membrane; wherein the slurry of the anode catalyst coating and / or cathode catalyst coating is independently selected from the above-mentioned catalyst slurry, or a catalyst slurry obtained by the above-mentioned catalyst slurry preparation method. By applying the above-mentioned slurry of the anode catalyst coating and / or cathode catalyst coating to the surface of the proton exchange membrane, the present invention can, to a certain extent, mitigate the formation of cracks in the catalytic layer caused by CCM shrinkage, thereby improving the electrochemical performance and lifespan of the membrane electrode.

[0045] The present invention provides a first surface with an anode catalyst coating and a second surface with a cathode catalyst coating on the proton exchange membrane, so that the proton exchange membrane after the catalyst slurry is applied on the first surface and the second surface further reduces the swelling caused by absorbing alcohol and water in the catalyst slurry, and greatly slows down the generation of cracks in the catalytic layer due to shrinkage of the CCM during the subsequent heating and drying process to remove the solvent, thereby more significantly improving the uniformity and stability of the CCM, and further greatly improving the electrochemical performance and life of the membrane electrode.

[0046] In a preferred embodiment, in order to further enable the CCM to better exert stability and uniformity, thereby effectively avoiding the generation of cracks in the CCM during the drying process, and thus improving the electrochemical performance of the membrane electrode, the proton exchange membrane is preferably a perfluorosulfonic acid proton exchange membrane; further preferably, the thickness of the proton exchange membrane layer is 8 to 20 μm, and the thickness of the proton exchange membrane layer can be 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm; preferably, the thickness of the anode catalyst coating is 1 to 5 μm, and the thickness of the anode catalyst coating can be 1 μm, 2 μm, 3 μm, 4 μm or 5 μm; preferably, the thickness of the cathode catalyst coating is 5 to 10 μm, and the thickness of the cathode catalyst coating can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm.

[0047] Another aspect of the present invention also provides a method for preparing a CCM, which comprises: providing a proton exchange membrane; the proton exchange membrane layer having a first surface and a second surface arranged opposite to each other; arranging an anode catalyst coating on the first surface of the proton exchange membrane; and arranging a cathode catalyst coating on the second surface of the proton exchange membrane; the slurries of the anode catalyst coating and the cathode catalyst coating are each independently selected from the above-mentioned catalyst slurry, or the catalyst slurry obtained by the above-mentioned catalyst slurry preparation method.

[0048] Those skilled in the art can first obtain a proton exchange membrane having a first surface and a second surface disposed opposite each other. An anode catalyst coating is then applied to the first surface of the proton exchange membrane, and a cathode catalyst coating is applied to the second surface of the proton exchange membrane. The slurries for the anode catalyst coating and the cathode catalyst coating are each independently selected from the aforementioned catalyst slurries, or catalyst slurries obtained by the aforementioned catalyst slurry preparation method. This preparation method has the advantages of a simple process and easy operation, thereby further promoting the large-scale production of CCMs and broadening their prospects for industrial application.

[0049] In a preferred implementation method, in the preparation method of the above-mentioned CCM, those skilled in the art can first use a slit coater to coat the anode catalyst slurry on the first surface of the proton exchange membrane, dry it, attach a protective film, and then coat the cathode catalyst slurry on the second surface of the proton exchange membrane. This makes the proton exchange membrane after coating with the catalyst slurry have better stability. Based on the perfluorosulfonic acid resin in the catalyst slurry, it can be better physically cross-linked, further increasing the degree of mutual entanglement between the perfluorosulfonic acid resin polymer chains, thereby effectively avoiding cracks in the preparation process of the CCM, thereby improving the battery performance and service life of the membrane electrode. Preferably, the coating rate of the anode catalyst slurry is 5 to 20 m / min, and the coating rate of the cathode catalyst slurry is 3 to 10 m / min.

[0050] In a preferred embodiment, in the above-mentioned CCM preparation method, after coating the first and second surfaces of the proton exchange membrane, the preparation method further includes: passing the coated material of the present invention through a first heating device, a second heating device, and a third heating device at a feed rate of 3 to 10 m / min (for example, 3 m / min, 4 m / min, 5 m / min, 6 m / min, 7 m / min, 8 m / min, 9 m / min, and 10 m / min) to perform a first heating treatment, a second heating treatment, and a third heating treatment. Specifically, after the above-mentioned coating is completed, the CCM can be continued to be conveyed by a conveyor belt to independently arranged first, second, and third ovens for the first heating, second heating, and third heating, respectively. The first heating treatment temperature is preferably 20 to 40°C. Based on this, the majority of the first alcohol in the coating layer can be better removed, thereby effectively preventing the first alcohol from volatilizing too quickly, destroying the intermolecular interaction force, and causing rapid shrinkage of the CCM and cracking, thereby improving the performance and life of the membrane electrode. The second heat treatment temperature is preferably 60-100°C to better remove water and residual first alcohol from the coating layer. To more completely volatilize the water and first alcohol, thereby mitigating cracking during CCM preparation, the third heat treatment temperature is preferably 30-60°C. More preferably, the first, second, and third ovens are each independently spaced 4-8 meters apart.

[0051] Another aspect of the present invention provides a membrane electrode, comprising an anode gas diffusion layer, a CCM and a cathode gas diffusion layer. The CCM is the above-mentioned CCM, or a CCM obtained by the above-mentioned CCM preparation method, which has better electrochemical performance and longer life.

[0052] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0053] Example 1

[0054] Preparation of perfluorosulfonic acid resin dispersion:

[0055] A perfluorosulfonic acid resin is dispersed in a dispersant consisting of water and a second alcohol. The perfluorosulfonic acid resin has an EW of 790 g / mol, the second alcohol is ethanol and n-propanol, wherein the weight ratio of ethanol to n-propanol is 2:1, the weight ratio of water to the second alcohol is 1:1, and the weight content of the perfluorosulfonic acid resin is 15 wt%.

[0056] The final perfluorosulfonic acid resin dispersion was heated at a temperature of 25°C and a shear rate of 10s -1 The viscosity under the conditions was 590 cP.

[0057] Preparation of catalyst slurry:

[0058] Step S1, the catalyst and water are mixed for the first time, and the first alcohol and the above-mentioned perfluorosulfonic acid resin dispersion are added to the system in sequence for the second mixing to obtain slurry A. Wherein, the catalyst is an anode catalyst or a cathode catalyst, the active component of the anode catalyst is platinum, the active component of the cathode catalyst is a platinum-cobalt alloy, and the catalyst is platinum, platinum-cobalt alloy supported on carbon particles, the weight content of the catalyst is 7wt%, and the weight content of platinum in the catalyst is 50wt%. Wherein, the first alcohol is ethanol, and the weight ratio of water to ethanol is 1.5:1, the weight content of the perfluorosulfonic acid resin dispersion is 23wt%, and the weight ratio of the catalyst, perfluorosulfonic acid resin dispersion and solvent is 7:23:70. The first mixing and second mixing processes are carried out in a homogenizer, wherein the processing temperature of the first mixing is 20°C and the processing time is 0.5h; the processing temperature of the second mixing is 15°C and the processing time is 1h.

[0059] Step S2: grinding, filtering, and defoaming the slurry A in sequence to obtain a catalyst slurry. The catalyst slurry is ground in a ball mill at a grinding speed of 1800 rpm for 1.5 hours, and then filtered and defoamed under vacuum.

[0060] The viscosity of the catalyst slurry finally obtained at a temperature of 25° C. and a shear rate of 140 cP was 140 cP, and the particle size D90 of the catalyst slurry was 0.745 μm.

[0061] Preparation of CCM:

[0062] A slot coater is used to first coat the anode catalyst slurry on the first surface of the proton exchange membrane and dry it. A support membrane is then attached to the dried coating surface. The cathode catalyst slurry is then coated on the second surface of the proton exchange membrane. The membrane is heated, dried, and rolled up at a feed rate of 5 m / min to obtain the CCM. The drying process uses a three-stage oven to perform gradient drying on the CCM. The temperatures of the three-stage ovens are set to 30°C for the first stage, 80°C for the second stage, and 50°C for the third stage. The platinum loading of the cathode catalyst layer is 0.3 mg / cm 2 The platinum loading of the anode catalyst layer is 0.05 mg / cm 2 .

[0063] Preparation of membrane electrode:

[0064] The CCM prepared above was cut into pieces with a size of 5×5 cm. 2 The sample was directly assembled by sandwiching it between two diffusion layers provided by Wuhan University of Technology to obtain a membrane electrode.

[0065] Example 2

[0066] The only difference from Example 1 is that the weight ratio of water to ethanol in the solvent of the catalyst slurry is 1:1.

[0067] Example 3

[0068] The only difference from Example 1 is that the weight ratio of water to ethanol in the solvent of the catalyst slurry is 2.3:1.

[0069] Example 4

[0070] The only difference from Example 1 is that the weight ratio of water to ethanol in the solvent of the catalyst slurry is 4:1.

[0071] Example 5

[0072] The only difference from Example 1 is that the viscosity of the perfluorosulfonic acid resin dispersion is 500 cP at a temperature of 25° C. and a shear rate of .

[0073] Example 6

[0074] The only difference from Example 1 is that the viscosity of the perfluorosulfonic acid resin dispersion is 700 cP at a temperature of 25° C. and a shear rate of .

[0075] Example 7

[0076] The only difference from Example 1 is that during the preparation of CCM, heating, drying and winding are performed at a feed speed of 1 m / min.

[0077] Example 8

[0078] The only difference from Example 1 is that during the preparation of CCM, heating, drying and winding are carried out at a feed speed of 15 m / min.

[0079] Example 9

[0080] The only difference from Example 1 is that in the preparation method of CCM, the coated CCM is heated in a one-stage heating manner at a heating temperature of 70°C.

[0081] Comparative Example 1

[0082] The difference from Example 1 is that the solvent in the perfluorosulfonic acid resin dispersion is water, and the weight content of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 25 wt %.

[0083] Comparative Example 2

[0084] The only difference from Example 1 is that the viscosity of the perfluorosulfonic acid resin dispersion is 800 cP at a temperature of 25° C. and a shear rate of .

[0085] Comparative Example 3

[0086] The only difference from Example 1 is that in the catalyst slurry solvent, the first alcohol is isopropanol, and the weight ratio of water to isopropanol is 0.6:1.

[0087] Comparative Example 4

[0088] The only difference from Example 1 is that the weight ratio of water to ethanol in the catalyst slurry solvent is 6:1.

[0089] Comparative Example 5

[0090] The only difference from Example 1 is that the weight ratio of water to ethanol in the catalyst slurry solvent is 3:7.

[0091] Comparative Example 6

[0092] The difference from Example 1 is that the weight content of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is about 27 wt %, the EW of the perfluorosulfonic acid resin is 800±60, the second alcohol in the dispersant is only ethanol, and the weight ratio of water to ethanol is about 3:2.

[0093] Comparative Example 7

[0094] The difference from Example 1 is that the second alcohol in the perfluorosulfonic acid resin dispersion is only ethanol.

[0095] Performance testing:

[0096] Table 1: Swelling rate test results of proton exchange membrane at different water / n-propanol weight ratios.

[0097] Table 2: Test results of the swelling ratio of proton exchange membrane in thickness direction in different solvents.

[0098] The membrane electrode materials prepared in the above examples and comparative examples were tested on a fuel cell test fixture equipped with a serpentine flow field. The test conditions were: 80°C temperature, 40% activation humidity, initial flow rates of 300 sccm on the hydrogen side and 700 sccm on the air side, excess coefficients of 1.5 / 2.0, and back pressures of 100 / 90 kPa.

[0099] Specifically, the performance test results are shown in Table 3 below:

[0100] Table 1

[0101]

[0102] Table 2

[0103]

[0104] Table 3

[0105]

[0106] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0107] Can find by the data of table 2 proton exchange membrane swelling ratio in different solvents, the swelling ratio of proton exchange membrane in pure water, ethanol and ethylene glycol is less, and the swelling ratio in isopropyl alcohol and n-propyl alcohol is larger.Can find by the data of table 1 proton exchange membrane swelling ratio under different water / n-propyl alcohol weight ratio, along with the mass ratio of alcohol and water increases, the swelling ratio of proton membrane in thickness direction also constantly increases.For considering that proton exchange membrane is coated with catalyst slurry process easily because of swelling and produce the purpose of crackle, therefore in the catalyst slurry system, the content of alcohol can not be too high.Further consider that n-propyl alcohol and isopropyl alcohol solvent cause the swelling ratio of proton exchange membrane larger, so in order to avoid coating to produce crackle in baking process, the solvent in the final preferred catalyst slurry is ethanol and water.

[0108] From the data of Examples 1, 5, 6 and Comparative Example 2 in Table 3, it can be found that when the viscosity of the perfluorosulfonic acid resin dispersion is 500-700 cP at a temperature of 25°C and a shear rate of 500 cP (for example, 590 cP in Example 1, 500 cP in Example 5, and 700 cP in Example 6), the catalyst slurry can significantly alleviate the occurrence of cracks in the process of preparing CCM, and the cathode coating of the resulting membrane electrode has a good appearance and excellent electrochemical performance, such as Figure 1When the viscosity of the perfluorosulfonic acid resin dispersion at a temperature of 25°C and a shear rate of 1000 cP is outside the above range (e.g., 800 cP in Comparative Example 2), the resin viscosity is too high and the chain segments are too entangled, which is not conducive to the coating of the catalyst. As a result, the cathode coating of the resulting membrane electrode has a poor appearance and poor electrochemical performance.

[0109] From the data of Example 1 and Comparative Example 7 in Table 3, it can be found that when the first alcohol in the solvent for preparing the catalyst slurry is ethanol (e.g., Example 1), the cathode coating prepared using this catalyst slurry performs better and has higher electrochemical performance. However, when the first alcohol in the solvent for preparing the catalyst slurry is isopropanol (e.g., Comparative Example 7), the CCM cathode coating prepared using this catalyst slurry performs poorly due to swelling, and the electrochemical performance of the membrane electrode is also poor.

[0110] The data from Examples 1 and 9 in Table 3 show that when the CCM preparation process uses a three-stage heating process (e.g., Example 1), the resulting membrane electrode cathode coating exhibits superior performance and high electrochemical properties. However, when the CCM preparation process uses a one-stage heating process at 70°C (e.g., Example 9), the high temperature in the first stage causes rapid solvent evaporation, resulting in rapid shrinkage of the coating and cracking.

[0111] From the data of Examples 1, 2, 3, 4 and Comparative Examples 4 and 5 in Table 3, it can be found that when the weight ratio of catalyst slurry water to the first alcohol is (1-4):1 (e.g., 1.5:1 in Example 1, 1:1 in Example 2, 2.3:1 in Example 3, and 4:1 in Example 4), the catalyst slurry can significantly alleviate the occurrence of cracks during the preparation of CCM, and the cathode coating of the resulting membrane electrode has a good appearance and excellent electrochemical performance, such as Figure 2 、 Figure 3 、 Figure 4 As shown. When the weight ratio of the catalyst slurry water to the first alcohol is higher than this range (for example, 6:1 in Comparative Example 4), due to the high water content, it is not conducive to the dispersion of the resin and the catalyst, resulting in the presence of some large pinholes in the CCM cathode coating prepared by the catalyst slurry, low catalytic active sites, and poor electrochemical performance of the membrane electrode. When the weight ratio of the catalyst slurry water to the first alcohol is lower than this range (for example, 3:7 in Comparative Example 5), due to the high ethanol content, the proton membrane swells, and the proton membrane shrinks during the drying process, resulting in poor performance of the CCM cathode coating prepared by the catalyst slurry, and poor electrochemical performance of the membrane electrode.

[0112] From the data of Example 1 and Comparative Example 1 in Table 3, it can be found that when the solvent in the perfluorosulfonic acid resin dispersion is water and the second alcohol, the CCM cathode coating is pinhole-free and crack-free, and the electrochemical performance of the membrane electrode is also high. However, when the solvent is only water (such as Comparative Example 1), due to poor resin dispersion, it is not conducive to the cross-linking between catalyst aggregates, resulting in cracks in the CCM cathode coating and reduced electrochemical performance of the membrane electrode, such as Figure 5 shown.

[0113] From the data of Example 1 and Comparative Example 6 in Table 3, it can be found that when the weight content of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 25wt% and the equivalent weight EW of the perfluorosulfonic acid resin is 790, the cathode coating is pinhole-free and crack-free, and the electrochemical performance is also high. However, when the weight content of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is higher, the EW of the perfluorosulfonic acid resin is 800±60, and the second alcohol is only ethanol (such as Comparative Example 6), due to the different structures of the resins, the slurry viscosity is too high, which is not conducive to the volatilization of the solvent, resulting in the CCM cathode coating being prone to cracks, and the membrane electrode electrochemical performance is good, such as Figure 6 shown.

[0114] From the data of Example 1 and Comparative Example 7 in Table 3, it can be found that when the solvent in the perfluorosulfonic acid resin dispersion is ethanol and n-propanol as the second alcohol, the cathode coating is pinhole-free and crack-free, and the electrochemical performance is also high. When n-propanol is not added and the second alcohol is only ethanol (such as Comparative Example 7), the resin dispersion is too poor to be conducive to catalyst coating, resulting in cracks in the CCM cathode coating and reduced electrochemical performance of the membrane electrode, such as Figure 7 shown.

[0115] From the data of Example 1, Example 7 and Example 8 in Table 3, it can be found that when the coated material is fed through the first heating device, the second heating device and the third heating device at a feeding speed of 3 to 10 m / min to perform the first heating treatment, the second heating treatment and the third heating treatment (for example, the 5 m / min feeding speed of Example 1) 2 When the feed rate is 1 m / min, the cathode coating is pinhole-free and crack-free, and the electrochemical performance is also high. When the feed rate is lower than this range (for example, 1 m / min in Example 7), the coating rate is too slow, resulting in a slow solvent evaporation rate, so the CCM cathode coating is prone to cracks, and the electrochemical performance of the membrane electrode is average. When the feed rate is higher than this range (for example, 15 m / min in Example 8), the slurry viscosity is not very high. When the coating rate is too fast, the pressure is released after coating, and the coating liquid will shrink, causing the CCM cathode coating to be prone to cracks, and the electrochemical performance of the membrane electrode is average.

[0116] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A catalyst slurry, characterized in that: The catalyst slurry includes a catalyst, a perfluorosulfonic acid resin dispersion and a solvent; wherein, The perfluorosulfonic acid resin dispersion comprises a perfluorosulfonic acid resin and a dispersant, and the perfluorosulfonic acid resin dispersion is heated at a temperature of 25° C. and a shear rate of 10 s -1 The viscosity under the conditions is 500-700 cP; the weight content of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 15-25 wt%, and the EW value of the perfluorosulfonic acid resin is 700-900 g / mol; the dispersant includes water and a second alcohol, and the weight ratio of water to the second alcohol in the dispersant is (1-3):(1-4); the second alcohol is ethanol and n-propanol, and the weight ratio of ethanol to n-propanol is (3-1):(2-1); The solvent includes water and a first alcohol; the first alcohol is an alcohol having less than 3 carbon atoms, and the weight ratio of water to the first alcohol is (1-4):

1.

2. The catalyst slurry according to claim 1, characterized in that The weight ratio of the catalyst, the perfluorosulfonic acid resin dispersion and the solvent in the catalyst slurry is (1-2): (2-10): (10-25).

3. The catalyst slurry according to claim 1, characterized in that The weight ratio of the catalyst, the perfluorosulfonic acid resin dispersion and the solvent in the catalyst slurry is (1-2): (3-7): (10-15).

4. The catalyst slurry according to claim 1 or 2, characterized in that The catalyst is an anode catalyst or a cathode catalyst.

5. The catalyst slurry according to claim 4, characterized in that The active component of the anode catalyst is platinum, ruthenium, iridium or an alloy thereof.

6. The catalyst slurry according to claim 4, characterized in that The active component of the cathode catalyst is platinum, cobalt, nickel or an alloy thereof.

7. The catalyst slurry according to claim 1 or 2, characterized in that The catalyst slurry was heated at a temperature of 25°C and a shear rate of 10s -1 The viscosity under certain conditions is 30~300cP.

8. The catalyst slurry according to claim 7, characterized in that The catalyst slurry was heated at a temperature of 25°C and a shear rate of 10s -1 The viscosity under certain conditions is 60~160cP.

9. The catalyst slurry according to claim 7, characterized in that The D90 particle size of the solid particles in the catalyst slurry is less than 2 μm.

10. The catalyst slurry according to claim 9, characterized in that The D90 particle size of the solid particles in the catalyst slurry is 0.5-1.5 μm.

11. A method for preparing the catalyst slurry according to any one of claims 1 to 10, characterized in that: The preparation method comprises: mixing a catalyst, a solvent and a perfluorosulfonic acid resin dispersion to obtain a catalyst slurry.

12. The method for preparing the catalyst slurry according to claim 11, wherein: The preparation method comprises the following steps: Step S1, after the catalyst and water are first mixed, the first alcohol and the perfluorosulfonic acid resin dispersion are sequentially added to the system for second mixing to obtain slurry A; Step S2: pre-dispersing, grinding, filtering and defoaming the slurry A in sequence to obtain the catalyst slurry.

13. The method for preparing the catalyst slurry according to claim 12, characterized in that: The treatment temperature of the first mixing is 15-25° C., and the treatment time is 0.1-2 hours.

14. The method for preparing the catalyst slurry according to claim 13, wherein: The treatment temperature of the second mixing is 10-25° C., and the treatment time is 0.1-2 h.

15. The method for preparing the catalyst slurry according to claim 13, wherein: The pre-dispersion is carried out in a homogenizer.

16. The method for preparing the catalyst slurry according to claim 13, wherein: The grinding is carried out in a ball mill.

17. The method for preparing the catalyst slurry according to claim 16, characterized in that: The grinding speed is 1500-2500 rpm, and the grinding time is 1-3 hours.

18. A catalyst-coated proton membrane (CCM) for membrane electrode, characterized in that: The catalyst-coated proton membrane (CCM) for membrane electrode comprises: A proton exchange membrane having a first surface and a second surface disposed opposite to each other; an anode catalyst coating disposed on the first surface of the proton exchange membrane; and a cathode catalyst coating disposed on the second surface of the proton exchange membrane; The slurry of the anode catalyst coating and / or the cathode catalyst coating is each independently selected from the catalyst slurry according to any one of claims 1 to 10, or the catalyst slurry obtained by the preparation method of the catalyst slurry according to any one of claims 11 to 17.

19. The catalyst-coated proton membrane (CCM) for membrane electrode according to claim 18, characterized in that: The proton exchange membrane is a perfluorosulfonic acid proton exchange membrane.

20. The catalyst-coated proton membrane (CCM) for membrane electrode according to claim 19, characterized in that: The thickness of the proton exchange membrane is 8-20 μm.

21. The catalyst-coated proton membrane (CCM) for membrane electrode according to claim 19, characterized in that: The thickness of the anode catalyst coating is 1-5 μm.

22. The catalyst-coated proton membrane (CCM) for membrane electrode according to claim 19, characterized in that: The thickness of the cathode catalyst coating is 5-10 μm.

23. A method for preparing a catalyst-coated proton membrane (CCM) for membrane electrode according to any one of claims 18 to 22, characterized in that: The preparation method comprises: Providing a proton exchange membrane, wherein the proton exchange membrane has a first surface and a second surface disposed opposite to each other; providing an anode catalyst coating on the first surface of the proton exchange membrane; providing a cathode catalyst coating on the second surface of the proton exchange membrane; The slurry of the anode catalyst coating and / or the cathode catalyst coating is each independently selected from the catalyst slurry according to any one of claims 1 to 10, or the catalyst slurry obtained by the preparation method of the catalyst slurry according to any one of claims 11 to 17; Using a slot coater to coat the first surface of the proton exchange membrane with an anode catalyst slurry to obtain the anode catalyst coating, and coating the second surface of the proton exchange membrane with a cathode catalyst slurry to obtain the cathode catalyst coating; After the coating, the preparation method further includes: passing the coated material through a first heating device, a second heating device and a third heating device in sequence at a feeding speed of 3-10 m / min to perform a first heating treatment, a second heating treatment and a third heating treatment.

24. The method for preparing a catalyst-coated proton membrane (CCM) for membrane electrode according to claim 23, characterized in that: The first heating treatment temperature is 20-40°C.

25. The method for preparing a catalyst-coated proton membrane (CCM) for membrane electrode according to claim 23, characterized in that: The second heat treatment temperature is 60-100°C.

26. The method for preparing a catalyst-coated proton membrane (CCM) for membrane electrode according to claim 23, characterized in that: The third heating treatment temperature is 30-60°C.

27. A membrane electrode comprising an anode gas diffusion layer, a CCM and a cathode gas diffusion layer, characterized in that: The CCM is the catalyst-coated proton membrane CCM for membrane electrode according to any one of claims 18 to 22, or the catalyst-coated proton membrane CCM for membrane electrode obtained by the preparation method of the catalyst-coated proton membrane CCM for membrane electrode according to any one of claims 23 to 26.

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