Preparation method and application of proton exchange membrane electrolyzed water iridium-based catalyst coating slurry
Through ultrasonic dispersion and ball milling treatment, a stable iridium-based catalyst slurry was prepared, which solved the problem of easy precipitation of catalyst particles and poor consistency of the coating layer, and improved the electrochemical performance of the membrane electrode.
Patent Information
- Application Number
- CN202411888835.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-03-04
AI Technical Summary
In the prior art, the stability of the iridium-based catalyst coating slurry is poor, the catalyst particles are prone to settle, and the consistency of the coating catalytic layer is poor, which hinders the development of large-area preparation of membrane electrodes.
A uniform and stable catalyst slurry was prepared by mixing the catalyst particles with water and adding an alcohol solution for ultrasonic dispersion, and then adding a proton exchange membrane solution for ball milling. This method improves the dispersion state of the catalyst and the binding effect with the electrolyte membrane through ultrasonic predispersion and ball milling treatment.
The uniformity and stability of the catalyst slurry are achieved, the precipitation of the catalyst particles is reduced, the consistency of the coated catalytic layer is improved, and the electrochemical performance of the membrane electrode is improved.
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Figure CN119553301A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of electrochemistry, and particularly relates to a preparation method and application of an iridium-based catalyst coating slurry for proton exchange membrane water electrolysis. Background Art
[0002] In recent years, with the rapid increase in the global population and the continuous development of global trade services, the consumption of traditional fossil energy and environmental problems have made the demand for alternative energy increasingly urgent. It has become a global consensus to explore the demand for renewable energy and clean energy to reduce dependence on fossil energy and reduce the adverse effects of pollution emissions on the environment. In this context, hydrogen energy technology has attracted widespread attention due to its advantages such as renewable fuel, high combustion calorific value, and strong sustainability. China is the world's largest hydrogen producer, but overall, gray hydrogen and blue hydrogen produced by direct combustion or reforming of fossil energy account for more than 95%, and green hydrogen produced by renewable energy without carbon emissions accounts for only about 5%. At present, the main technical means for preparing green hydrogen is water electrolysis to produce hydrogen. Among them, the proton exchange membrane electrolyzer technology has a simple process and high energy efficiency. It overcomes many shortcomings of traditional alkaline water electrolysis technology and has gradually become the mainstream in water electrolysis technology.
[0003] In a proton exchange membrane electrolyzer, the membrane electrode is the core site of the water electrolysis reaction. Its catalytic layer needs to have channels for the transport of reactants and products, and also needs to have excellent proton transport and electron conduction capabilities. And because the water electrolysis reaction is a three-phase reaction, there are special requirements for the solid, liquid, and gas transport capabilities of the membrane electrode. Therefore, the quality of the membrane electrode process often determines the conversion efficiency and operating stability of the entire electrolyzer. At present, the CCM method (Catalyst Coating Membrane) is one of the more mature methods for membrane electrode preparation, and the methods for preparing CCM are generally divided into two categories, namely ultrasonic spraying and slit coating. However, the ultrasonic spraying method has poor utilization and spraying efficiency of the slurry, which greatly increases the production cost, and the interface contact effect between the sprayed catalyst layer and the electrolyte membrane is poor, resulting in an increase in the ohmic internal resistance in the CCM, which seriously affects the working performance of the electrolyzer. Therefore, in recent years, more and more research and results on the preparation of CCM by slit coating have been reported. However, due to the easy sedimentation of iridium-based catalysts and the high requirements of slot coating technology for the solid content of the slurry, the current iridium-based slot coating slurry generally has problems such as poor slurry stability, easy sedimentation of catalyst particles, and poor consistency of the coated catalytic layer, which greatly hinders the further development of this technology in the large-area preparation of anode catalyst layers. Summary of the invention
[0004] In view of the defects of the prior art, the technical problem to be solved by the present invention is to provide a preparation method and application of an iridium-based catalyst coating slurry for proton exchange membrane water electrolysis.
[0005] The present invention provides a method for preparing a catalyst slurry, comprising:
[0006] (1) Mix the catalyst and water, then add the alcohol solution and disperse;
[0007] (2) Add proton exchange membrane solution into step (1) and perform ball milling to obtain catalyst slurry.
[0008] The catalyst in step (1) is catalyst particles.
[0009] In the step (1), the catalyst and water are mixed to fully wet the catalyst.
[0010] Preferably, the catalyst in step (1) is an iridium-based catalyst; wherein the mass percentage of iridium in the iridium-based catalyst is 35% to 75%; and the water is ultrapure water;
[0011] Preferably, the alcohol solution in step (1) is one or more of anhydrous ethanol, n-propanol, isopropanol, and ethylene glycol.
[0012] Preferably, in step (1), the mass ratio of the catalyst to water is 1:(0.5-1); the mass ratio of the catalyst to alcohol is (0.2-0.7):1.
[0013] Preferably, the dispersion in step (1) is performed by ultrasonic treatment, the ultrasonic power is 300W to 500W, the ultrasonic time is 10min to 30min, and the ultrasonic treatment is performed under ice bath conditions.
[0014] The ultrasonic treatment is carried out by using an ultrasonic cell disruptor.
[0015] Preferably, the proton exchange membrane solution in step (2) is a Nafion solution with a mass concentration of 5-20%, and the mass ratio of the catalyst to the perfluorosulfonic acid resin in the proton exchange membrane solution is (0.8-2):1.
[0016] Preferably, the ball milling treatment in step (2) is performed for a ball milling time of 60 min to 180 min and a ball mill speed of 400 rpm to 800 rpm;
[0017] The ball milling in step (2) is performed by using a planetary ball mill.
[0018] Preferably, in step (2), the ball milling is followed by stirring for 10-30 minutes.
[0019] The present invention provides a catalyst slurry prepared by the method, wherein the solid content of the catalyst slurry is controlled to be 20% to 25%, and the viscosity of the catalyst slurry is controlled to be 10 to 40 mPa.s.
[0020] The present invention provides a membrane electrode, which comprises the catalyst slurry.
[0021] The present invention provides a method for preparing a membrane electrode, comprising: uniformly covering the catalyst slurry on the surface of a base membrane, drying to obtain a prefabricated catalytic layer, transferring the catalytic layer to a proton exchange membrane to form a catalyst coating membrane (CCM), and then pressing it with a gas diffusion layer to form a membrane electrode; wherein the drying is performed at 50-60°C for 1-3 minutes.
[0022] Furthermore, the catalyst slurry is evenly covered on the surface of the transfer base membrane by a scraping method, and dried to obtain a prefabricated catalytic layer. The catalytic layer is transferred to the proton exchange membrane by transfer to form a CCM, and then pressed together with the gas diffusion layer and titanium felt by hot pressing to form a complete membrane electrode.
[0023] The present invention provides an application of the catalyst slurry or the membrane electrode in the field of proton exchange membrane water electrolysis.
[0024] The present invention adds catalyst particles and a certain proportion of ultrapure water to a container in sequence to initially wet the catalyst, then adds an alcohol solution for ultrasonic dispersion, and finally adds a membrane solution for ball milling. After sufficient ball milling, a uniform and stable catalyst slurry for coating is obtained. After coating and drying, a uniform, stable and crack-free catalyst layer is obtained. The membrane electrode obtained after thermal transfer has shown excellent electrochemical performance after testing.
[0025] Beneficial Effects
[0026] The present invention can make the catalyst more dispersible in the slurry by ultrasonic pre-dispersion of the hydroalcohol solution and the catalyst particles. Then, by adding the Nafion solution and performing ball milling, the bonding effect between the surface of the catalyst iridium oxide and the Nafion can be enhanced, the repellency of each component in the mixed system can be reduced, the dispersion state of the slurry can be significantly improved, the flow of the slurry on the coating substrate (such as a transfer film, etc.) can be made more uniform, and a uniform crack-free catalyst layer can be obtained by coating. The process is quick and simple, the required technical difficulty is small, the slurry can be prepared on a large scale, and it is suitable for batch production. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 This is a digital photo of the prefabricated catalytic layer after the porous iridium oxide catalyst coating slurry for electrolysis of water prepared in Example 1 is scraped on the surface of the transfer base film;
[0028] Figure 2 This is a microscope picture of the prefabricated catalytic layer on the transfer base film of Example 1 after drying;
[0029] Figure 3 This is the IV curve of the single electrolytic cell prepared in Example 1. DETAILED DESCRIPTION
[0030] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.
[0031] The present invention provides a solution: a preparation of an iridium-based catalyst coating slurry for electrolysis of water, wherein catalyst particles and a certain proportion of ultrapure water are sequentially added to a container, after the catalyst is soaked, an alcohol solution is then added for ultrasonic dispersion, and after dispersion, a membrane solution is added for ball milling, and after uniform dispersion, a uniform and stable catalyst slurry for coating is obtained. After coating and drying, a uniform, stable and crack-free catalyst layer is obtained, and the membrane electrode obtained after thermal transfer has shown excellent electrochemical performance after testing. The solid content of the catalyst slurry is controlled to be 20% to 25%, and the viscosity of the catalyst slurry is controlled to be 10mPa.s to 40mPa.s.
[0032] The invention discloses a method for preparing iridium-based catalyst coating slurry for proton exchange membrane water electrolysis, which is applied to membrane electrode manufacturing process. Specifically, the catalyst slurry is evenly covered on the surface of transfer base membrane by scraping, and a prefabricated catalytic layer is obtained after drying at 50°C for 1 minute. The catalytic layer is transferred to the proton exchange membrane by transfer printing to form CCM, and then pressed into a complete membrane electrode by hot pressing with gas diffusion layer and titanium felt.
[0033] Example 1
[0034] Preparation method of coating slurry: first add 2.5g iridium oxide (75wt Ir %) catalyst, then add 1.8g ultrapure water, then add 2.5g isopropanol and 2.5g n-propanol respectively, use 400w ultrasonic dispersion for 30min under ice bath condition, maintain the temperature at 5-20℃, then add 4.6g Nafion D2020 solution, magnetic stirring for 20min, pour the above solution into a ball mill, add 14g 0.1mm zirconium beads, use a planetary ball mill for 180min, the speed is 500rpm. Then pour the slurry into a beaker and magnetically stir for 30min.
[0035] Finally, a uniform and stable porous iridium oxide coating catalyst slurry was prepared according to the method of Example 1. The solid content of the slurry was about 25% and the viscosity was 15 mPa.s.
[0036] The catalyst slurry was evenly coated on the surface of the transfer base film by scraping, and dried at 50°C for 1 min to obtain a prefabricated catalytic layer, in which the iridium loading of the catalytic layer was 0.5 mg. The catalytic layer was transferred to the proton exchange membrane by transfer printing to form a CCM, in which the cathode platinum loading was 0.3 mg and the effective area of the CCM was 25 cm 2 , and pressed together with the anode and cathode gas diffusion layers to form a complete membrane electrode, and then the performance is tested.
[0037] Comparative Example 1
[0038] Preparation method of spray slurry: first add 0.13g catalyst (same as Example 1) into a beaker, add 7g ultrapure water, then add 7g isopropanol, use 400w ultrasonic dispersion for 60min, maintain the temperature at 5-20°C, then add 0.3g Nafion D520 solution, use 500w ultrasonic dispersion for 120min, maintain the temperature at 5-20°C.
[0039] Finally, a uniform and stable porous iridium oxide coating catalyst slurry was prepared according to the method of Comparative Example 1. The solid content of the slurry was about 1% and the viscosity was 3 mPa.s.
[0040] The catalyst slurry is evenly sprayed on the proton exchange membrane by spraying. The anode and cathode loadings and the active area are the same as those in Example 1. The body diffusion layer is pressed into a complete membrane electrode in a fitting manner, and then the performance test is carried out in the same manner as in Example 1.
[0041] like Figure 1 It means that after the slurry is scraped and dried, a prefabricated catalytic layer with a relatively uniform surface can be obtained, such as Figure 2 The prefabricated catalyst layer is coated evenly under a microscope without cracking. By adding Nafion solution and then ball milling, the bonding effect between the surface of the catalyst iridium oxide and Nafion is enhanced, the repellency of each component in the mixed system is reduced, the dispersion state of the slurry is significantly improved, the flow of the slurry on the transfer membrane is more uniform, and a uniform and crack-free catalyst layer is obtained by coating. After transfer, the interface contact between the catalyst layer and the electrolyte membrane is increased. Under the same loading and test conditions, the electrochemical performance is better than that of the spray slurry in Comparative Example 1 (such as Figure 3 shown).
Claims
1. A method for preparing a catalyst slurry, comprising: (1) Mix the catalyst and water, then add the alcohol solution and disperse; (2) Add proton exchange membrane solution and perform ball milling to obtain catalyst slurry.
2. The preparation method according to claim 1, characterized in that: The catalyst in step (1) is an iridium-based catalyst; wherein the mass percentage of iridium in the iridium-based catalyst is 35% to 75%; and the water is ultrapure water; The alcohol solution in step (1) is one or more of anhydrous ethanol, n-propanol, isopropanol, and ethylene glycol.
3. The preparation method according to claim 1, characterized in that: In the step (1), the mass ratio of the catalyst to water is 1:(0.5-1); the mass ratio of the catalyst to alcohol is (0.2-0.7):
1.
4. The preparation method according to claim 1, characterized in that: The dispersion in step (1) is performed by ultrasonic treatment, the ultrasonic power is 300W to 500W, and the ultrasonic time is 10min to 30min.
5. The preparation method according to claim 1, characterized in that: The proton exchange membrane solution in step (2) is a Nafion solution with a mass concentration of 5-20%, and the mass ratio of the catalyst to the perfluorosulfonic acid resin in the proton exchange membrane solution is (0.8-2):
1.
6. The preparation method according to claim 1, characterized in that: The ball milling treatment in step (2) is performed for a ball milling time of 60 min to 180 min and a ball mill speed of 400 rpm to 800 rpm; In the step (2), the mixture is stirred for 10-30 minutes after the ball milling treatment.
7. A catalyst slurry prepared by the method of claim 1, characterized in that: The solid content of the catalyst slurry is controlled to be 20% to 25%, and the viscosity of the catalyst slurry is controlled to be 10 to 40 mPa.s.
8. A membrane electrode, characterized in that: The membrane electrode comprises the catalyst slurry according to claim 7.
9. A method for preparing a membrane electrode, comprising: The catalyst slurry described in claim 7 is evenly coated on the surface of the base membrane, and after drying, a prefabricated catalyst layer is obtained. The catalyst layer is transferred to the proton exchange membrane to form a catalyst coating membrane (CCM), and then pressed with the gas diffusion layer to form a membrane electrode.
10. Use of the catalyst slurry according to claim 7 or the membrane electrode according to claim 8 in the field of proton exchange membrane water electrolysis.