Anion exchange membrane electrolyzed water cathode electrode and preparation method thereof

Abstract

The invention provides an anion exchange membrane electrolyzed water cathode electrode and a preparation method thereof. The anion exchange membrane electrolyzed water cathode electrode comprises a carbon fiber substrate and cathode catalyst slurry cured on the surface of the carbon fiber substrate, and the cathode catalyst slurry comprises the following components in parts by mass: 20 parts of an anion ionomer, 10 parts of a catalyst, 5-9 parts of a 5% binder solution and 250-300 parts of a solvent; wherein a binder in the 5% binder solution is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyvinyl alcohol and polyvinylpyrrolidone. The high-molecular binder and the anion ionomer are introduced to form a composite network, the binding force between the catalyst layer and the porous transmission layer is improved, the attenuation rate is low, the stability is high, and the problems of stripping and pulverization of the catalyst layer under the working conditions of strong alkalinity and high gas-liquid flow rate can be effectively solved.

Description

Technical Field

[0001] This invention relates to the field of electrolytic water cathode electrode technology, specifically to an anion exchange membrane electrolytic water cathode electrode and its preparation method. Background Technology

[0002] Hydrogen energy, as an ideal clean energy source, is considered one of the most promising energy sources. Among hydrogen production technologies, anion exchange membrane (AEM) hydrogen production technology can simultaneously combine the high current density of solid electrolyte (PEM) hydrogen production with the low cost of alkaline water electrolysis (ALK) hydrogen production technology. Therefore, anion exchange hydrogen production technology is more suitable for large-scale hydrogen production.

[0003] Patent CN202511357911.4 discloses an anode catalyst layer and its preparation method. This invention significantly improves the mechanical strength and electrochemical performance of the proton exchange membrane water electrolysis electrode by introducing polymeric compounds such as sodium hydroxymethyl cellulose, effectively solving the structural degradation problem of the anode catalyst layer under differential pressure operation. This technology, by forming a reinforcing network between the polymeric compound and the iridium catalyst, not only optimizes the conductivity and durability of the catalyst layer but also provides a new approach for high-performance membrane electrode design. However, while this anode-side innovation improves the stability of the proton exchange membrane system, it does not directly address the unique challenges of the cathode electrode in anion exchange membrane water electrolysis. In anion exchange membrane water electrolysis technology, the cathode catalyst layer often suffers from uneven thickness due to the "coffee ring effect" during preparation, leading to problems such as localized current density concentration, increased interfacial contact resistance, and catalyst layer peeling and pulverization. Especially under strongly alkaline conditions and high gas-liquid flow rates, traditional cathode electrodes using anion ionomers as binders are prone to three-phase interface instability and rapid performance degradation. Meanwhile, patent CN119153717A relates to the optimization of water management in fuel cell catalyst layers, improving conductivity and hydrophilicity through sulfonated lignin-doped conductive polymer nanoparticles. However, its focus is on water management on the anode side of the fuel cell, which differs from the environmental adaptability of anion exchange membrane electrolysis cathodes. Therefore, while existing technologies have made progress in their respective fields, they have failed to effectively solve the problems of uniformity and durability of anion exchange membrane electrolysis cathode electrodes. There is an urgent need to develop a novel cathode electrode structure that uses an innovative binder system to suppress the coffee ring effect, improve the smoothness and bonding force of the catalyst layer, thereby reducing hydrogen production energy consumption and extending service life.

[0004] Currently, anion exchange membrane (AEM) water electrolysis cathodes are mainly prepared using a catalyst-coated substrate spraying process. In this process, because the solvent evaporation rate at the droplet edges is significantly higher than in the center, to compensate for the solvent loss at the edges, the liquid inside the slurry continuously flows towards the edges, carrying catalyst particles that are continuously deposited there, forming a ring-shaped thick deposition zone, known as the "coffee ring effect." This effect leads to severely uneven distribution of the catalyst layer thickness, which in turn causes the following problems:

[0005] 1) In the annular thick region, the transport path of reactants and products is extended and the impedance is increased, while in the central thin region, insufficient catalytic layer coverage easily leads to excessively high local reaction current density. This thickness difference drives the current to preferentially concentrate in the thin or defective regions with lower resistance, resulting in a local actual current density far exceeding the design value. This not only reduces the overall utilization rate of the catalyst but also induces local overheating, accelerates the Ostwald ripening of the catalyst and the corrosion of the support, and thus leads to a decline in electrochemical performance.

[0006] 2) The coffee ring effect causes the surface of the catalyst layer to have obvious undulations, making it difficult to form a uniform and tight interface contact when hot-pressing it with the anion exchange membrane. This leads to a significant increase in the contact resistance between the cathode and the membrane, thereby reducing the overall energy conversion efficiency of the system.

[0007] 3) Under strong alkaline and high gas-liquid impact operating conditions, the internal stress distribution of the catalyst layer with uneven thickness is also unbalanced, making it more prone to local peeling and pulverization, which leads to instability of the three-phase reaction interface, weakening of the bonding force between the catalyst layer and the substrate, and thus reducing the mechanical stability and durability of the battery.

[0008] In existing technologies, those skilled in the art typically use anionic ionomers as binders to construct ion-conducting networks, but their effectiveness in regulating slurry rheology and suppressing the coffee ring effect is limited. Anionic ionomers primarily provide ion-conducting functions, with relatively weak influence on particle migration and solvent evaporation gradients during slurry drying, making it difficult to effectively overcome problems caused by the coffee ring effect.

[0009] Therefore, there is an urgent need for a new electrode slurry that can actively suppress the coffee ring effect during the spraying process, so as to obtain a high-performance AEM cathode catalyst layer with uniform thickness, strong bonding and long-term stable operation. Summary of the Invention

[0010] (a) Technical problems to be solved

[0011] To address the shortcomings of existing technologies, this invention provides an anion exchange membrane electrolysis cathode electrode and its preparation method, thus solving the problems mentioned in the background section.

[0012] (II) Technical Solution

[0013] To achieve the above objectives, the present invention provides the following technical solution:

[0014] According to a first aspect of the present invention, an anion exchange membrane electrolysis cathode electrode is provided, comprising a carbon fiber substrate and a cathode catalyst slurry cured on the surface of the carbon fiber substrate, wherein the cathode catalyst slurry comprises, by mass parts, 20 parts of anion ionomer, 10 parts of catalyst, 5 to 9 parts of 5% binder solution and 250 to 300 parts of solvent.

[0015] The binder in the 5% binder solution is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, and polyvinylpyrrolidone.

[0016] This invention fundamentally suppresses the coffee ring effect by adding a polymeric binder to the cathode catalyst slurry. The binder regulates the slurry's rheological properties and solvent evaporation behavior, increasing cohesion to resist capillary flow and promoting uniform sedimentation of catalyst particles, forming a catalytic layer of uniform thickness. Simultaneously, the binder also possesses surface-active properties, reducing surface tension and weakening particle edge migration by forming a dynamic film at the gas-liquid interface. It also enhances dispersibility by adsorbing and encapsulating particles, and strengthens mechanical strength and binding force through cross-linking treatment. The optimal range for binder addition was determined to achieve a balance between catalytic activity, mass transfer, and durability. Furthermore, a composite system composed of anionic ionomers and polymeric binders was constructed to synergistically achieve efficient ion conduction and mechanical enhancement, forming a structurally stable and performance-optimized catalytic layer.

[0017] Preferably, the mass of the 5% binder solution is 5-50% of the catalyst.

[0018] More preferably, the mass of the 5% binder solution is 10-30% of the catalyst.

[0019] Preferably, the catalyst is selected from at least one of Pt / C, Pt-Ru / C, and Pt-Co / C.

[0020] Preferably, the solvent is selected from at least one of isopropanol, ethylene glycol, ethanol, n-propanol, dimethyl sulfoxide, and water.

[0021] Preferably, the loading of the cathode catalyst slurry is 0.8~1.6 mg / cm³. 2 .

[0022] According to a second aspect of the present invention, a method for preparing an anion exchange membrane electrolysis cathode electrode is provided, comprising the following steps:

[0023] Step 1: Add water to the adhesive to obtain a 5% adhesive solution, denoted as solution A;

[0024] Step 2: Dissolve the catalyst and anionic polymer in a solvent and disperse them to obtain solution B;

[0025] Step 3: Mix and disperse the solution A and solution B to obtain the cathode catalyst slurry;

[0026] Step 4: Coat the cathode catalyst slurry onto the carbon fiber substrate and dry it to obtain the anion exchange membrane electrolysis cathode electrode.

[0027] Preferably, in step 2, the dispersion is performed using ultrasound or ball milling.

[0028] Preferably, in step 3, the dispersion is performed by ball milling or shearing.

[0029] Preferably, in step 4, the drying temperature is 70~90℃.

[0030] (III) Beneficial Effects

[0031] This invention provides an anion exchange membrane electrolysis water cathode electrode and its preparation method. It has the following beneficial effects:

[0032] (1) The anion exchange membrane electrolysis cathode electrode provided in this solution eliminates the coffee ring effect by optimizing the catalyst layer, achieving a uniform distribution of catalyst layer thickness. This avoids current density concentration caused by local thickness differences, preventing local overheating and catalyst degradation. Simultaneously, the smooth catalyst layer surface allows for uniform and tight interfacial contact with the anion exchange membrane after hot pressing, significantly reducing interfacial contact resistance and thus lowering hydrogen production energy consumption. Furthermore, by eliminating stress concentration points caused by uneven thickness, the electrode is less prone to cracking under continuous bubble scouring and thermal cycling, greatly extending its service life.

[0033] (2) The anion exchange membrane electrolysis cathode electrode provided in this solution improves the bonding force between the catalyst layer and the porous transport layer by introducing a polymer binder and anion ionomer to form a composite network. It has a low decay rate and high stability, and can effectively resist the problem of catalyst layer peeling and pulverization under strong alkaline and high gas-liquid flow conditions.

[0034] (3) The anion exchange membrane electrolysis water cathode electrode provided in this scheme is used in anion exchange membrane electrolysis water production hydrogen system at 1.5 A / cm 2 It has a lower operating voltage at lower current densities and an ohmic impedance of only 90 mΩ·cm. 2 It has lower ohmic impedance. Attached Figure Description

[0035] Figure 1 This is a surface morphology diagram of the anion exchange membrane electrolysis cathode electrode prepared in Example 1 of the present invention;

[0036] Figure 2 This is a surface morphology diagram of the anion exchange membrane electrolysis cathode electrode prepared in Comparative Example 1 of the present invention;

[0037] Figure 3 This is a surface morphology diagram of the anion exchange membrane electrolysis cathode electrode prepared in Example 2 of the present invention;

[0038] Figure 4 This is a surface morphology diagram of the anion exchange membrane electrolysis cathode electrode prepared in Example 3 of the present invention;

[0039] Figure 5 This is a surface morphology diagram of the anion exchange membrane electrolysis cathode electrode prepared in Example 4 of the present invention;

[0040] Figure 6 This is a surface morphology diagram of the anion exchange membrane electrolysis cathode electrode prepared in Comparative Example 2 of the present invention;

[0041] Figure 7 This is a surface morphology diagram of the anion exchange membrane electrolysis cathode electrode prepared in Comparative Example 3 of the present invention.

[0042] Figure 8 This is a surface morphology diagram of the anion exchange membrane electrolysis cathode electrode prepared in Comparative Example 4 of the present invention.

[0043] Figure 9 The single-cell polarization curves of the cathode electrodes prepared in Example 1 and Comparative Example 1 of this invention are shown.

[0044] Figure 10 The cathode electrodes prepared for Example 1 and Comparative Example 1 of this invention are subjected to a constant current density of 1.5 A / cm. 2 The following is a durability test chart;

[0045] Figure 11 The image shows the single-cell impedance test results of the cathode electrodes prepared in Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0046] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] In this embodiment, the platinum-carbon catalyst powder was purchased from Tanaka Precious Metals Group, and the platinum content was 50%.

[0048] Isopropanol was purchased from Sinopharm Group;

[0049] The anionic polymer was purchased from Ningbo Zhongke Qingyi Membrane Technology Co., Ltd. and was a quaternized polyarylene ether sulfone solution with a concentration of 5%.

[0050] The adhesive was purchased from Sinopharm Group;

[0051] The spraying equipment is Shanghai Yangmi YMUS-ZM600.

[0052] The following detailed description, with reference to specific embodiments, illustrates an anion exchange membrane electrolysis cathode electrode and its preparation method.

[0053] Example 1

[0054] Preparation of cathode catalyst slurry: by weight, 20 parts of quaternized polyarylene ether sulfone solution, 10 parts of Pt / C catalyst, 5.16 parts of 5% binder solution and 289 parts of isopropanol.

[0055] The specific preparation method is as follows:

[0056] Step 1: Dissolve 0.5g of polyvinyl alcohol in 9.5g of ultrapure water for 1 hour to form a 5% binder solution, thus obtaining solution A;

[0057] Step 2: Wet 0.5g of Pt / C catalyst powder with 6.125g of water, then disperse it in 14.45g of isopropanol and 1.025g of 5% anionic polymer solution under the given conditions in a sonicator for 10 minutes to obtain solution B.

[0058] Step 3: Add 0.258g of solution A to solution B and ultrasonically disperse for 40min under ice bath conditions to obtain cathode catalyst slurry;

[0059] Step 4: The cathode catalyst slurry is coated onto the surface of carbon fiber using ultrasonic spraying. X-ray fluorescence spectroscopy is used to determine the loading of the Pt / C catalyst powder, which is 1.2 mg / cm³. 2 The slurry was dried at 90°C to obtain the cathode electrode AEM-1.

[0060] Example 2

[0061] The preparation method of this embodiment is the same as that of Example 1. The difference is that, in the preparation of the cathode catalyst slurry, by weight, 20 parts of quaternized polyarylene ether sulfone solution, 10 parts of Pt / C catalyst, 5.79 parts of 5% binder solution and 277 parts of isopropanol are used to obtain the cathode electrode, which is denoted as AEM-3.

[0062] Example 3

[0063] The preparation method of this embodiment is the same as that of Example 1. The difference is that, in the preparation of the cathode catalyst slurry, by weight, 20 parts of quaternized polyarylene ether sulfone solution, 10 parts of Pt / C catalyst, 5.9 parts of 5% binder solution and 283.5 parts of isopropanol are used to obtain the cathode electrode, which is denoted as AEM-4.

[0064] Example 4

[0065] The preparation method of this embodiment is the same as that of Example 1. The difference is that, in the preparation of the cathode catalyst slurry, by weight, 20 parts of quaternized polyarylene ether sulfone solution, 10 parts of Pt / C catalyst, 7.9 parts of 5% binder solution and 283 parts of isopropanol are used to obtain the cathode electrode, which is denoted as AEM-5.

[0066] Comparative Example 1

[0067] The preparation method of this embodiment is the same as that of Example 1. The difference is that, in the preparation of the cathode catalyst slurry, by weight, 20 parts of quaternized polyarylene ether sulfone solution, 10 parts of Pt / C catalyst and 283 parts of isopropanol are used to obtain the cathode electrode, which is denoted as AEM-2.

[0068] Comparative Example 2

[0069] The preparation method of this embodiment is the same as that of Example 1. The difference is that, in the preparation of the cathode catalyst slurry, by weight, 20 parts of quaternized polyarylene ether sulfone solution, 10 parts of Pt / C catalyst, 9.5 parts of 5% binder solution and 283 parts of isopropanol are used to obtain the cathode electrode, which is denoted as AEM-6.

[0070] Comparative Example 3

[0071] The preparation method of this embodiment is the same as that of Example 1. The difference is that, in the preparation of the cathode catalyst slurry, by weight, 20 parts of quaternized polyarylene ether sulfone solution, 10 parts of Pt / C catalyst, 5.16 parts of glycerol and 289 parts of isopropanol are used to obtain the cathode electrode, which is denoted as AEM-7.

[0072] Comparative Example 4

[0073] The preparation method of this embodiment is the same as that of Example 1. The difference is that, in the preparation of the cathode catalyst slurry, by weight, 20 parts of quaternized polyarylene ether sulfone solution, 10 parts of Pt / C catalyst, 5.16 parts of PEG and 289 parts of isopropanol are used to obtain the cathode electrode, which is denoted as AEM-8.

[0074] The specific component data of Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1.

[0075] Table 1

[0076]

[0077] according to Figures 1 to 8 As shown, without the addition of a polymer binder, the prepared cathode electrode exhibits a severe "coffee ring effect" on its surface, poor thickness uniformity, and high interfacial contact resistance. In contrast, the cathode electrodes prepared in Examples 1 to 4 have smooth surfaces without coffee rings, high thickness uniformity, and low interfacial contact resistance.

[0078] according to Figure 9 As shown, the electrode obtained in Example 1 operates at an electrical density of 1.5 A / cm. 2 The voltage at which the electrode was applied was 1.79V. The electrode obtained in Comparative Example 1 was subjected to an electrical density of 1.5 A / cm. 2 The voltage was 1.84V, indicating that the electrode prepared in Example 1 has higher electrochemical activity.

[0079] according to Figure 10 As shown, the electrode obtained in Example 1 had a voltage decay rate of 0 μV / h within 200 hours, while the electrode obtained in Comparative Example 1 had a voltage decay rate of 75 μV / h within 200 hours, demonstrating excellent operational stability.

[0080] according to Figure 11 As shown, in Example 1, the ohmic impedance of a single cell is 46 mΩ·cm. 2 Comparative Example 1 has an ohmic impedance of 50 mΩ·cm in a single cell. 2 The lower impedance indicates that the electrode surface has better flatness and better interface contact in this embodiment.

[0081] The performance test results of Examples 2 to 4 and Comparative Examples 2 to 4 are shown in Table 2.

[0082] Table 2

[0083]

[0084] As shown in Table 2, excessive binder content (as in Comparative Example 2) has a comprehensive negative impact on the initial performance, long-term stability, and ohmic impedance of the AEM membrane electrode. Excessive binder, acting as an insulator, coats the conductive catalyst particles and carbon support surface, hindering electron conduction pathways within the catalyst layer. Simultaneously, it may also clog the ion-polymer network, increasing the resistance to hydroxide ion transport.

[0085] It should be noted that polyvinyl alcohol in this application can be replaced with other types, such as polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or polyvinylpyrrolidone, to prepare the corresponding cathode catalyst slurry. The cathode electrode prepared by the alternative scheme can also achieve improved electrochemical performance and durability. The relevant embodiments will not be described in detail in this invention.

[0086] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A cathode electrode for anion exchange membrane electrolysis of water, characterized in that: The cathode catalyst slurry includes a carbon fiber substrate and a cathode catalyst slurry cured on the surface of the carbon fiber substrate. The cathode catalyst slurry, by mass parts, includes 20 parts of anionic ionomer, 10 parts of catalyst, 5 to 9 parts of 5% binder solution and 250 to 300 parts of solvent. The binder in the 5% binder solution is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, and polyvinylpyrrolidone.

2. The anion exchange membrane electrolysis cathode electrode according to claim 1, characterized in that: The mass of the 5% binder solution is 5-50% of the catalyst.

3. The anion exchange membrane electrolysis cathode electrode according to claim 2, characterized in that: The mass of the 5% binder solution is 10-30% of the catalyst.

4. The anion exchange membrane electrolysis cathode electrode according to claim 1, characterized in that: The catalyst is selected from at least one of Pt / C, Pt-Ru / C, and Pt-Co / C.

5. The anion exchange membrane electrolysis cathode electrode according to claim 1, characterized in that: The solvent is selected from at least one of isopropanol, ethylene glycol, ethanol, n-propanol, dimethyl sulfoxide, and water.

6. The anion exchange membrane electrolysis cathode electrode according to claim 1, characterized in that: The loading of the cathode catalyst slurry is 0.8~1.6 mg / cm³. 2 .

7. A method for preparing an anion exchange membrane electrolysis cathode electrode according to any one of claims 1 to 6, characterized in that: Includes the following steps: Step 1: Add water to the adhesive to obtain a 5% adhesive solution, denoted as solvent A; Step 2: Dissolve the catalyst and anionic polymer in a solvent and disperse them to obtain solution B; Step 3: Mix and disperse the solution A and solution B to obtain the cathode catalyst slurry; Step 4: Coat the cathode catalyst slurry onto the carbon fiber substrate and dry it to obtain the anion exchange membrane electrolysis cathode electrode.

8. The method for preparing an anion exchange membrane electrolysis cathode electrode according to claim 7, characterized in that: In step 2, the dispersion is performed using ultrasound or ball milling.

9. The method for preparing an anion exchange membrane electrolysis cathode electrode according to claim 7, characterized in that: In step 3, the dispersion is achieved by ball milling or shearing.

10. The method for preparing an anion exchange membrane electrolysis cathode electrode according to claim 7, characterized in that: In step 4, the drying temperature is 70~90℃.

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