Anode catalyst layer and method for preparing the same and membrane electrode

Abstract

The application discloses an anode catalyst layer and a preparation method thereof and a membrane electrode, relates to the technical field of proton exchange membrane water electrolysis, and the anode catalyst layer is a single-layer structure and is prepared from an anode catalyst slurry after drying, the anode catalyst slurry comprises the following components in parts by weight: 0.05-10 parts of a polymer compound; 0.5-10 parts of an iridium catalyst; 0.5-12 parts of a perfluorosulfonic acid resin; and 5-120 parts of a solvent; wherein the polymer compound is used to form a reinforcing structure in the anode catalyst layer, the polymer compound comprises at least one of sodium hydroxymethyl cellulose, polyvinylidene fluoride, polyacrylic acid, polyimide or butadiene styrene rubber, and the mass of the polymer compound is 20-100% of the mass of the anode catalyst. By introducing the polymer compound, the mechanical performance and electrochemical performance of the membrane electrode can be improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of proton exchange membrane water electrolysis, and particularly relates to an anode catalyst layer and a preparation method thereof and a membrane electrode. BACKGROUND

[0002] In the technical field of proton exchange membrane water electrolysis (PEMWE), a membrane electrode (MEA) as a core component directly determines the operation efficiency and stability of the whole system. The membrane electrode is usually composed of a proton exchange membrane, catalyst layers on both sides and gas diffusion layers. The anode catalyst layer (ACL) is a core functional layer where an anode oxidation reaction occurs, and the structural stability and catalytic activity of the anode catalyst layer directly determine the overall electrochemical performance of the membrane electrode.

[0003] The current conventional anode catalyst layer lacks an effective structural reinforcement mechanism, and its mechanical strength is insufficient. In the electrode preparation and system operation scenarios, slight collision, extrusion and other external forces can cause deformation and rupture of the anode catalyst layer, and damage to the catalyst layer can directly damage the structural integrity of the membrane electrode, affecting its core functions of electric conduction and mass transfer. Moreover, differential pressure operation is a typical working condition of the PEMWE system, and if the structural strength is insufficient, it will be difficult to withstand the continuous stress generated by the differential pressure, which will gradually aggravate the internal structural damage of the membrane electrode, possibly causing the interface separation of the catalyst layer and the proton exchange membrane, or causing the catalyst layer to have a through crack, and thus aggravating performance degradation and shortening the service life. In addition, the electrochemical performance of the membrane electrode still has a large room for improvement, and these problems jointly restrict the further development and application of the PEMWE technology. SUMMARY

[0004] The application aims to provide an anode catalyst layer, a preparation method thereof and a membrane electrode, so as to improve the mechanical performance and electrochemical performance of the membrane electrode.

[0005] To achieve the above-mentioned purpose, the application provides the following technical solutions.

[0006] In a first aspect, the application provides an anode catalyst layer prepared from an anode catalyst slurry after drying, wherein the anode catalyst slurry comprises the following components in parts by weight: 0.05-10 parts of a high molecular compound; 0.5-10 parts of an iridium catalyst; 0.5-12 parts of a perfluorosulfonic acid resin; and 5-120 parts of a solvent.

[0007] Generally, the anode catalyst slurry mainly consists of an anode catalyst, a perfluorosulfonic acid resin and a solvent. The solvent is used to dissolve the perfluorosulfonic acid resin to provide a good medium for subsequent dispersion of the anode catalyst. The ball milling method is used to uniformly disperse the anode catalyst in the perfluorosulfonic acid resin solution. After drying to remove the solvent, the anode catalyst layer presents a structure in which the anode catalyst is wrapped by the perfluorosulfonic acid resin. However, when this kind of anode catalyst layer is applied to a membrane electrode, there is a problem of insufficient mechanical strength.

[0008] However, by additionally adding a high molecular compound in the anode catalyst slurry, after drying to form an anode catalyst layer, the high molecular compound will form a reinforcing structure outside the perfluorosulfonic acid resin. This reinforcing structure not only can significantly increase the mechanical strength of the membrane electrode, thereby effectively enhancing its pressure resistance performance, but also can improve the structural stability of the catalyst layer, improve the structural degradation during operation, and thereby prolong the service life. This anode catalyst layer with a reinforcing structure can effectively solve the problem of insufficient mechanical strength of the membrane electrode and easy breakage under differential pressure operating conditions. At the same time, the reinforcing structure can also support the skeleton of the anode catalyst layer, promote it to form a more fluffy structure, thereby exposing more catalyst active sites, and thereby improving the catalytic activity and optimizing the electrochemical performance of the membrane electrode.

[0009] Through in-depth research, it is found that when the molecular structure of the high molecular compound contains polar groups or is an elastomer, it is helpful to further improve the mechanical properties and electrochemical properties of the membrane electrode. Preferably, the high molecular compound includes at least one of sodium carboxymethylcellulose (CMC-Na), polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), polyimide (PI) or styrene butadiene rubber (SBR).

[0010] Specifically, when the molecular structure of the high molecular compound contains polar groups (such as -CF2- of PVDF, -OH / -COONa of CMC-Na, and imide ring of PI), inter-chain hydrogen bonds, dipole interactions or rigid skeletons are easily formed, which can construct a dense and tough "three-dimensional support network" in the catalyst layer. This network can effectively disperse external forces (such as coating extrusion, vibration impact), reduce the deformation and rupture of the catalyst layer; at the same time, these polar groups can also form interfacial forces (such as the formation of hydrogen bonds between -OH of CMC-Na and -SO3H of the membrane, and the formation of dipole adsorption between -CF2- of PVDF and the polar surface of the catalyst particles) with the surface of the proton exchange membrane (such as -SO3H of Nafion membrane) and the catalyst layer particles (such as IrO2 catalyst), which can significantly improve the adhesion strength of the catalyst layer to the membrane and the gas diffusion layer, and avoid interface separation under differential pressure conditions.

[0011] These polar groups can form moderate strength interactions with the catalyst particles, which can both immobilize the catalyst particles by adsorption, effectively inhibiting particle agglomeration and ensuring the continuous exposure of the catalytically active sites, and will not cover the active sites due to the over-strong adsorption force, thereby avoiding the inhibition of the catalytic reaction. For example, the -COOH of PAA and the Ir on the surface of IrO2 4+ The weak coordination bond is formed, which can stabilize the catalyst while not hindering the reaction sites.

[0012] In addition, PVDF and PI also have excellent acid resistance and oxidation resistance, which can adapt to the harsh environment of high potential and strong acidity of the PEMWE anode, and the molecular structure is not easy to degrade during long-term use, which can stably maintain the mechanical support effect on the catalyst layer. The elastomer such as SBR can further improve the anti-cracking ability of the catalyst layer by "elastic deformation" to buffer external force impact.

[0013] The addition amount of the polymer compound also affects the mechanical properties and electrochemical properties of the membrane electrode. The increase of the addition amount of the polymer compound has a positive effect on the improvement of the mechanical properties of the membrane electrode; but when the addition amount is too high, a series of adverse effects will be caused, at least in the following aspects: first, excessive polymer compound will cause the particle size of the catalyst slurry to increase significantly, and the catalyst layer formed by subsequent coating is prone to light transmission, which reduces the structural uniformity of the catalyst layer; second, as the addition amount of the polymer compound increases, the slurry coating thickness will also increase, which not only prolongs the drying process time, but also causes the catalyst loading to be difficult to control within a uniform range during the coating process due to the flowability of the slurry itself. The above problems of insufficient structural uniformity and fluctuation of loading will ultimately have a negative impact on the electrochemical properties of the membrane electrode.

[0014] As a preferred solution, the mass of the polymer compound is 5% to 100% of the mass of the iridium catalyst. More preferably, the mass of the polymer compound is 20% to 100% of the mass of the iridium catalyst; more preferably, the mass of the polymer compound is 20% of the mass of the iridium catalyst.

[0015] As a preferred solution, the anode catalyst slurry includes the following components in terms of weight fraction: 0.05 parts to 5 parts of a polymer compound; 0.5 parts to 5 parts of an iridium catalyst; 0.5 parts to 5 parts of a perfluorosulfonic acid resin; and 5 parts to 100 parts of a solvent.

[0016] As a preferred solution, the anode catalyst slurry includes the following components in terms of weight fraction: 0.05 parts to 1 part of a polymer compound; 0.6 parts to 1 part of an iridium catalyst; 0.6 parts to 1.2 parts of a perfluorosulfonic acid resin; and 5 parts to 60 parts of a solvent.

[0017] As a preferred solution, the number average molecular weight of the high molecular compound is 5000 g / mol to 1000000 g / mol.

[0018] As a preferred solution, the iridium catalyst comprises at least one of IrO2, IrRuO x1 , IrO2 / TiO2, IrO2 / NbO x1 , IrO2 / Ta2O5, IrO2 / WO x1 , or IrO2 / Nb2O 5-x2 , wherein x1 is 1 to 2, and x2 is 0 to 3.

[0019] As a preferred solution, the perfluorosulfonic acid resin comprises at least one of Nafion D2020, Nafion NR50, IC100, or Aquivion D79-25B.

[0020] As a preferred solution, the solvent comprises a first solvent for dissolving the high molecular compound and a second solvent for dissolving the perfluorosulfonic acid resin.

[0021] More preferably, the first solvent and the second solvent are the same or different, and comprise at least one of isopropyl alcohol, ethylene glycol, ethanol, n-propanol, and water. As an example, the high molecular compound is a water-soluble polymer, the first solvent comprises water, and the second solvent comprises isopropyl alcohol.

[0022] As a preferred solution, the preparation method of the anode catalyst slurry comprises: uniformly mixing a high molecular compound, an iridium catalyst, a perfluorosulfonic acid resin, and a solvent.

[0023] As a preferred solution, the method of uniformly mixing a high molecular compound, an iridium catalyst, a perfluorosulfonic acid resin, and a solvent comprises the following steps:

[0024] A1: dissolving a high molecular compound in a first solvent to obtain a first solution;

[0025] A2: mixing part of the first solution with an iridium catalyst to perform a first ball-milling wetting to obtain a second solution;

[0026] A3: adding a perfluorosulfonic acid resin to the second solution to perform a second ball-milling mixing to obtain a third solution;

[0027] A4: adding a mixed solution of the remaining first solution and a second solvent to the third solution and uniformly mixing.

[0028] The step A2 is used to preliminarily wet the iridium catalyst. As a preferred solution, in the step A2, the rotation speed during the first ball-milling wetting is 500 rpm-1500 rpm, and the time is 5 minutes-15 minutes. More preferably, the rotation speed is 750 rpm-1200 rpm, and the time is 6 minutes-12 minutes. As an example, the rotation speed is 1000 rpm, and the time is 10 minutes.

[0029] As a preferred solution, in the step A2, 2 mm-5 mm ball-milling beads are used. More preferably, 2 mm ball-milling beads, 3 mm ball-milling beads and 5 mm ball-milling beads with a mass ratio of 1:1:1 are used.

[0030] As a preferred solution, in the step A3, the rotation speed during the second ball-milling mixing is 500 rpm-1000 rpm, and the time is 30 minutes-100 minutes.

[0031] More preferably, in the step A3, during the second ball-milling mixing, first ball-milling is performed at 500 rpm-1000 rpm for 2 minutes-10 minutes, then after stopping rotation for 2 minutes-5 minutes, second ball-milling is performed at 500 rpm-1000 rpm for 2 minutes-10 minutes, and the above process is repeated for multiple times. As an example, first ball-milling is performed at 750 rpm for 5 minutes, then after stopping rotation for 2 minutes, second ball-milling is performed at 750 rpm for 5 minutes, and the above process is repeated for 4 times.

[0032] As a preferred solution, in the step A3, 2 mm-5 mm ball-milling beads are used. More preferably, 2 mm ball-milling beads, 3 mm ball-milling beads and 5 mm ball-milling beads with a mass ratio of 1:1:1 are used.

[0033] As a preferred solution, the method for uniformly mixing the high-molecular compound, the iridium catalyst, the perfluorosulfonic acid resin and the solvent comprises the following steps:

[0034] B1: mixing the high-molecular compound, the iridium catalyst and part of the first solvent by using a first ball-milling process to obtain a first mixed solution;

[0035] B2: mixing the first mixed solution and the perfluorosulfonic acid resin by using a second ball-milling process to obtain a second mixed solution;

[0036] B3: uniformly mixing the second mixed solution, the second solvent and the remaining first solvent by using a third ball-milling process.

[0037] As a preferred solution, in the step B1, the rotation speed of the first ball-milling process is 500 rpm-1000 rpm, and the time is 5 minutes-12 minutes. More preferably, the rotation speed is 650 rpm-750 rpm, and the time is 5 minutes-10 minutes. As an example, the rotation speed is 650 rpm, and the time is 10 minutes.

[0038] As a preferred solution, in step B1, 2mm-5mm ball milling beads are used. More preferably, 2mm ball milling beads, 3mm ball milling beads and 5mm ball milling beads are used in a mass ratio of 2:1:2.

[0039] As a preferred solution, in step B2, the rotation speed of the second ball milling process is 500rpm-1000rpm, and the time is 50min-90min. More preferably, the rotation speed is 650rpm-750rpm, and the time is 50min-60min. As an example, the rotation speed is 650rpm, and the time is 60min.

[0040] As a preferred solution, in step B2, 2mm-5mm ball milling beads are used. More preferably, 2mm ball milling beads, 3mm ball milling beads and 5mm ball milling beads are used in a mass ratio of 2:1:2.

[0041] As a preferred solution, in step B3, the rotation speed of the third ball milling process is 500rpm-1000rpm, and the time is 50min-90min. More preferably, the rotation speed is 650rpm-750rpm, and the time is 50min-60min. As an example, the rotation speed is 650rpm, and the time is 60min.

[0042] As a preferred solution, in step B3, 2mm-5mm ball milling beads are used. More preferably, 2mm ball milling beads, 3mm ball milling beads and 5mm ball milling beads are used in a mass ratio of 2:1:2.

[0043] As a preferred solution, in the anode catalyst layer, the loading amount of the iridium catalyst is 0.9mg / cm 2 ~1.1mg / cm 2 As an example, the iridium catalyst is IrO2.

[0044] In a second aspect, the application provides a preparation method of the above-mentioned anode catalyst layer, which comprises: coating the anode catalyst slurry on the surface of a substrate by spraying or doctor-blade coating, and obtaining the anode catalyst layer after drying. The selection of spraying or doctor-blade coating depends on the viscosity of the anode catalyst slurry, and low-viscosity slurry is suitable for spraying process, and high-viscosity slurry is suitable for doctor-blade coating process.

[0045] As a preferred solution, the drying temperature is 70℃-90℃.

[0046] In a third aspect, the application provides a membrane electrode comprising the above-mentioned anode catalyst layer.

[0047] Compared with the prior art, the technical scheme of the application has the following beneficial effects:

[0048] The application introduces a high molecular compound with a specific structure into the anode catalyst slurry, controls the mass ratio of the high molecular compound and iridium catalyst, and constructs a stable reinforcing structure outside the perfluorosulfonic acid resin after drying, which can improve the mechanical strength of the membrane electrode, effectively enhance the pressure resistance, improve the structural degradation during operation, and also improve the electrochemical performance of the membrane electrode. BRIEF DESCRIPTION OF DRAWINGS

[0049] The following drawings in detail describe the exemplary embodiments disclosed in the application. The same reference signs in the several views of the drawings represent similar structures. Those skilled in the art will understand that these embodiments are non-limiting, exemplary embodiments, and the drawings are only for the purpose of illustration and description, and are not intended to limit the scope of the application, and other embodiments can also achieve the same purpose. It should be understood that the drawings are not drawn to scale. Among them:

[0050] Figure 1 Single cell constant current durability test curve of the membrane electrode prepared for Example 1 and Comparative Example 1 of the application;

[0051] Figure 2 Single cell constant current durability test curve of the membrane electrode prepared for Examples 2-4 and Comparative Example 2 of the application;

[0052] Figure 3 Constant current durability test curve of the membrane electrode prepared for Example 1 and Comparative Example 1 of the application under the operating condition of differential pressure between the anode and the cathode;

[0053] Figure 4 Surface morphology diagram of the membrane electrode prepared for Example 1 of the application after differential pressure test;

[0054] Figure 5 Surface morphology diagram of the membrane electrode prepared for Comparative Example 1 of the application after differential pressure test. DETAILED DESCRIPTION

[0055] The following description provides specific application scenarios and requirements of the application, so that those skilled in the art can manufacture and use the content in the application. Various local modifications of the disclosed embodiments are obvious to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of the application. Therefore, the application is not limited to the embodiments shown.

[0056] The technical solutions of the application will be described in detail below in combination with the embodiments of the application. Unless otherwise specified, the reagents and raw materials used can be purchased through commercial channels. The experimental methods in the following examples are not specified, and are selected according to conventional methods and conditions, or according to the instructions of the goods.

[0057] Sodium carboxymethylcellulose (CMC-Na) was purchased from Sinopharm Chemical Reagent Co., Ltd. with the brand CP 800-1200 (Shanghai Test) and Iridium oxide particles (IrO2) was purchased from Heraeus with the brand H2EL-IrO2; Nafion D2020 was purchased from Chemours; IC100 was purchased from AGC; Isopropyl alcohol was purchased from Sinopharm Chemical Reagent Co., Ltd.; Proton exchange membrane was purchased from Chemours with the brand Nafion NR212; Thin fiber cloth was purchased from Shanghai Suofeng Aerospace Material Technology Co., Ltd. with the specification PC3N; Cathode catalyst layer was 4001 cathode catalyst layer from Shanghai Shengshui New Energy Technology Co., Ltd.; Single cell test PTL was purchased from Beijing Mai'annuise Technology Co., Ltd. with the brand MOTT 0.25mm and single cell test GDL was purchased from Shanghai Hesen Electrical Co., Ltd. with the brand Toray 39BB; Ball milling equipment was Simar TMV-200T or YXQM-200Q planetary ball mill; Spraying equipment was Suzhou Xifeng XF900-5T; Blade coating equipment was MS-ZN320B wire bar coater.

[0058] Example 1

[0059] (1) Preparation of anode catalyst slurry

[0060] The present embodiment provides an anode catalyst slurry, which comprises the following components in terms of weight fraction: 0.12 parts of CMC-Na, 0.6 parts of IrO2, 0.6 parts of Nafion D2020, 15 parts of water and 44.7 parts of isopropyl alcohol; and the preparation method is as follows:

[0061] 1) Dissolve 0.12 g of CMC-Na powder in 15 g of water, and name it as A solution.

[0062] 2) Put 1.2 g of A solution, 0.6 g of IrO2, 9 g of 2 mm ball milling beads, 9 g of 3 mm ball milling beads and 9 g of 5 mm ball milling beads into a ball milling tank (Simar TMV-200T), and ball mill for 10 minutes at 1000 rpm to preliminarily wet the IrO2.

[0063] 3) Add 0.6 g of Nafion D2020 into the ball milling tank, and ball mill for mixing, first ball mill for 5 minutes at 750 rpm, then stop for 2 minutes, and then ball mill for 5 minutes at 750 rpm, for 4 times continuously.

[0064] 4) Add the mixed solution of the remaining A solution and 44.7 g of isopropyl alcohol into the ball milling tank, transfer the catalyst system to a container, and perform cold water ultrasonic treatment on the container for 30 minutes to obtain the anode catalyst slurry.

[0065] (2) Preparation of anode catalyst layer

[0066] The anode catalyst slurry prepared in this example was coated on the surface of the thin fiber cloth by means of fine ultrasonic spraying. The loading of IrO2was 0.9 mg / cm2measured by X-ray fluorescence spectroscopy (XRF). 2 ~1.1mg / cm 2 The slurry was dried at 90°C to prepare an anode catalyst layer.

[0067] (3) Preparation of membrane electrode

[0068] The anode catalyst layer and the cathode catalyst layer were respectively transferred to the two opposite surfaces of the proton exchange membrane by means of hot-press transfer printing to prepare a membrane electrode PEM-1. The hot plate temperature in the process of hot-press transfer printing was 180°C, the pressure was 3 MPa, and the duration was 20 minutes.

[0069] Example 2

[0070] (1) Preparation of anode catalyst slurry

[0071] The anode catalyst slurry provided in this example comprises the following components in terms of weight fraction: 0.2 parts of CMC-Na, 1 part of IrO2, 1.2 parts of IC100, 2 parts of water, and 4.3 parts of isopropanol. The preparation method is as follows:

[0072] 1) 0.2 g of CMC-Na powder, 1 g of IrO2, 10 g of 2 mm ball milling beads, 5 g of 3 mm ball milling beads, 10 g of 5 mm ball milling beads, and 1 g of water were placed in a ball milling jar (YXQM-400 planetary ball mill), and ball milling was performed at 650 rpm for 10 minutes.

[0073] 2) 1.2 g of IC100 was added to the ball milling jar, and ball milling was performed at 650 rpm for 60 minutes.

[0074] 3) 1 g of water and 4.3 g of isopropanol were added to the ball milling jar, and ball milling was continued at 650 rpm for 60 minutes to prepare an anode catalyst slurry.

[0075] (2) Preparation of anode catalyst layer

[0076] The anode catalyst slurry prepared in this example was coated on the surface of the thin fiber cloth by means of flat plate scraping, and the loading of IrO2was 0.9 mg / cm2measured by X-ray fluorescence spectroscopy (XRF). 2 ~1.1mg / cm 2 The slurry was dried at 70°C to prepare an anode catalyst layer.

[0077] (3) Preparation of membrane electrode

[0078] The same hot press transfer printing method as in Example 1 was used to transfer the anode and cathode catalyst layers to the two opposite surfaces of the proton exchange membrane to produce a membrane electrode PEM-2.

[0079] Example 3

[0080] In this example, an anode catalyst slurry was provided, which was different from that of Example 2 only in that the amount of CMC-Na added was 1 part, which was 100% of the weight of IrO2. The specific component ratio is shown in Table 1.

[0081] The anode catalyst slurry, anode catalyst layer and membrane electrode PEM-5 were sequentially prepared according to the method of Reference Example 2.

[0082] Example 4

[0083] In this example, an anode catalyst slurry was provided, which was different from that of Example 2 only in that the amount of CMC-Na added was 0.05 parts, which was 5% of the weight of IrO2. The specific component ratio is shown in Table 1.

[0084] The anode catalyst slurry, anode catalyst layer and membrane electrode PEM-6 were sequentially prepared according to the method of Reference Example 2.

[0085] Comparative Example 1

[0086] In this comparative example, an anode catalyst slurry was provided, which was different from that of Example 1 only in that no CMC-Na was added. The specific component ratio is shown in Table 1.

[0087] The anode catalyst slurry, anode catalyst layer and membrane electrode PEM-3 were sequentially prepared according to the method of Reference Example 1.

[0088] Comparative Example 2

[0089] In this comparative example, an anode catalyst slurry was provided, which was different from that of Example 2 only in that no CMC-Na was added. The specific component ratio is shown in Table 1.

[0090] The anode catalyst slurry, anode catalyst layer and membrane electrode PEM-4 were sequentially prepared according to the method of Reference Example 2.

[0091] Table 1 Component ratio and coating method

[0092]

[0093] Mechanical property test

[0094] The membrane electrode was made into a long strip sample with a length of 10 cm and a width of 1 cm, and a computer servo tension machine (Dongguan Haida Instrument, HD-B609-S) was used to test the elongation at break thereof. For each type of membrane electrode, three sets of tests were performed in parallel, and the average value of the obtained data was calculated, and the test results are shown in Table 2.

[0095] According to the comparison results of Example 1 and Comparative Example 1, it can be seen that the tensile breaking strength of the membrane electrode prepared by adding CMC-Na in the anode catalyst layer is significantly improved; this conclusion can also be verified by the comparison results of Examples 2-4 and Comparative Example 2. Therefore, by introducing CMC-Na with a polar group into the anode catalyst layer, the mechanical strength of the membrane electrode can be effectively improved.

[0096] Further analysis of the comparison results of Examples 2-4 shows that as the gram weight ratio of CMC-Na to catalyst increases from 5% to 100%, the tensile breaking strength of the membrane electrode gradually increases. When the gram weight ratio of CMC-Na to catalyst is 100%, the maximum force reaches 21.104 N, and the tensile strength reaches 40.584 MPa.

[0097] Table 2 Mechanical property test results

[0098]

[0099] Electrochemical performance test

[0100] A gas diffusion layer was assembled on the membrane electrode, and a single cell constant current durability test of the membrane electrode was performed on a Ruifeng battery test system, the test temperature was set to 60℃, and the current density was 3.5A / cm 2 , and the test results are shown in Figures 1 to 3 .

[0101] In combination Figures 1 to 3It can be seen that, compared with the membrane electrode (PEM-3 and PEM-4) prepared without adding CMC-Na, the initial voltage of the membrane electrode (PEM-1, PEM-2, PEM-5 and PEM-6) prepared by adding CMC-Na is significantly reduced, which shows that the electrochemical performance of the membrane electrode can be effectively improved by introducing CMC-Na with a polar group. The reason may be that CMC-Na builds an enhanced structure of the support skeleton in the anode catalyst, promotes the anode catalyst layer to form a more fluffy micro-morphology, thereby exposing more catalyst active sites, and then improving the catalytic reaction activity and optimizing the electrochemical performance of the membrane electrode; at the same time, the interaction strength between the polar group in CMC-Na and IrO2 is moderate, which can not only fix IrO2 particles through adsorption to avoid their agglomeration so that the active sites can be continuously exposed, but also will not cover the active sites due to the too strong adsorption force, thereby avoiding the inhibition effect on the catalytic reaction. Among them, the voltage of PEM-5 is low in the early stage because the catalyst layer is in the activation process, and the voltage rises in the later stage due to the relatively large amount of CMC-Na added, which causes the anode catalyst layer to decay, but still meets the application requirements.

[0102] Figure 3 The constant current durability test results under the anode-cathode differential pressure operating condition (anode pressure 0.3 MPa, cathode pressure 3.3 MPa). Compared with PEM-3 prepared without adding CMC-Na, the voltage of PEM-1 is significantly reduced, which further confirms that under the differential pressure operating condition, CMC-Na can effectively improve the electrochemical performance of the membrane electrode.

[0103] The membrane electrode after differential pressure test was observed by using Guo Yi Quantum SEM2100, and the operation steps are as follows: first, the observed part is cut with a sharp blade and placed on the sample stage matched with SEM (the surface of the sample stage is pre-pasted with conductive tape for fixing the membrane electrode); then the sample stage is placed in the SEM chamber, after the chamber is vacuumized, the height of the sample stage is adjusted, and the electron beam flow is turned on to observe the sample morphology. If the sample morphology is blurred during observation, the focusing parameters and astigmatism correction parameters can be adjusted to improve the imaging effect.

[0104] Figure 4 Figure 6 is a surface morphology diagram of PEM-1 after differential pressure test, Figure 5 Figure 7 is a surface morphology diagram of PEM-3 after differential pressure test. Figure 5 Among them, the anode catalyst layer of PEM-3 has obvious cut marks, and the thinning rate of the cut marks is (48.49 μm-42.17 μm) / 48.49 μm x 100%=13%. And Figure 4 Among them, the anode catalyst layer of PEM-1 has no obvious cut marks. It can be seen that by introducing CMC-Na into the anode catalyst layer, the structural stability of the catalyst layer can be significantly improved, and the structural degradation in the running process can be improved.

[0105] It should be noted that based on the method described in the above embodiments, a similar method as the embodiments can be used to replace the high molecular compound with other types, such as polyvinylidene fluoride, polyacrylic acid, polyimide or butadiene rubber, and then corresponding anode catalyst slurry, anode catalyst layer and membrane electrode are prepared. The membrane electrode prepared by such replacement scheme can also achieve the improvement of mechanical properties and electrochemical properties, and the related embodiments in the present application will not be described one by one.

[0106] The above description of the embodiments is to facilitate the understanding and application of the present application by those of ordinary skill in the art. Those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described herein to other embodiments without having to pay creative labor. Therefore, the present application is not limited to the embodiments herein, and the improvements and modifications made by those skilled in the art based on the disclosure of the present application without departing from the scope and spirit of the present application are within the scope of the present application.

Claims

1. An anode catalyst layer characterized by, The application discloses a single-layer structure for a proton exchange membrane membrane electrode, which is prepared by drying an anode catalyst slurry, and the anode catalyst slurry comprises the following components in parts by weight: a polymer compound 0.05-10 parts; an iridium catalyst 0.5-10 parts; a perfluorosulfonic acid resin 0.5-12 parts; a solvent 5-120 parts. The polymer compound is used to form a reinforcing structure in the anode catalyst layer, and the polymer compound comprises at least one of sodium hydroxymethyl cellulose, polyacrylic acid or polyimide; and the mass of the polymer compound is 20-100% of the mass of the iridium catalyst.

2. The anode catalyst layer according to claim 1, characterized by The anode catalyst slurry comprises the following components in parts by weight: a polymer compound 0.05-1 part; an iridium catalyst 0.6-1 part; a perfluorosulfonic acid resin 0.6-1.2 parts; a solvent 5-60 parts.

3. The anode catalyst layer according to claim 1 or 2, characterized by The number average molecular weight of the polymer compound is 5000-1000000 g / mol; and / or the mass of the polymer compound is 20% of the mass of the iridium catalyst.

4. The anode catalyst layer according to claim 1 or 2, characterized by The iridium catalyst comprises at least one of IrO2, IrRuO x1 , IrO2 / TiO2, IrO2 / NbO x1 , IrO2 / Ta2O5, IrO2 / WO x1 , or IrO2 / Nb2O 5-x2 , wherein x1 is 1-2 and x2 is 0-3. The perfluorosulfonic acid resin comprises at least one of Nafion D2020, Nafion NR50, IC100 or Aquivion D79-25B; The solvent comprises a first solvent for dissolving the polymer compound and a second solvent for dissolving the perfluorosulfonic acid resin; the first and second solvents are the same or different, and comprise at least one of isopropyl alcohol, ethylene glycol, ethanol, n-propanol and water.

5. The anode catalyst layer according to claim 1, characterized by The preparation method of the anode catalyst slurry comprises the following steps: uniformly mixing a polymer compound, an iridium catalyst, a perfluorosulfonic acid resin and a solvent to obtain the anode catalyst slurry.

6. The anode catalyst layer according to claim 5, characterized by The method for uniformly mixing the polymer compound, the iridium catalyst, the perfluorosulfonic acid resin and the solvent comprises the following steps: dissolving the polymer compound in a first solvent to obtain a first solution; mixing part of the first solution with the iridium catalyst to perform first ball-milling wetting to obtain a second solution; adding the perfluorosulfonic acid resin to the second solution to perform second ball-milling mixing to obtain a third solution; adding a mixed solution of the remaining first solution and a second solvent to the third solution and uniformly mixing; or, the method for uniformly mixing the polymer compound, the iridium catalyst, the perfluorosulfonic acid resin and the solvent comprises the following steps: mixing the polymer compound, the iridium catalyst and part of the first solvent by using a first ball-milling process to obtain a first mixed solution; mixing the first mixed solution and the perfluorosulfonic acid resin by using a second ball-milling process to obtain a second mixed solution; uniformly mixing the second mixed solution, the remaining first solvent and a second solvent by using a third ball-milling process.

7. The anode catalyst layer according to claim 6, characterized by The rotating speed during the first ball-milling wetting is 500-1500 rpm, and the time is 5-15 minutes; The rotating speed during the second ball-milling mixing is 500-1000 rpm, and the time is 30-100 minutes; The first ball-milling wetting and the second ball-milling mixing adopt 2-5 mm ball-milling beads.

8. The anode catalyst layer according to claim 6, characterized by The rotation speed of the first ball milling process is 500 rpm-1000 rpm, and the time is 5 minutes-12 minutes; And / or, the rotation speed of the second ball milling process is 500 rpm-1000 rpm, and the time is 50 minutes-90 minutes; And / or, the rotation speed of the third ball milling process is 500 rpm-1000 rpm, and the time is 50 minutes-90 minutes; And / or, the first ball milling process, the second ball milling process and the third ball milling process all use 2 mm-5 mm ball milling beads.

9. A method for producing the anode catalyst layer as claimed in any one of claims 1 to 8, characterized by, The application further discloses an anode catalyst layer prepared by the method. The application further discloses an anode catalyst layer prepared by the method.

10. A membrane electrode characterized by, The application further discloses an anode catalyst layer prepared by the method.

Images