Anode catalyst layer combined slurry and preparation method thereof, membrane electrode for water electrolysis and preparation method thereof, and proton exchange membrane electrolytic cell

Abstract

The invention relates to anode catalyst layer combined slurry and a preparation method thereof, a membrane electrode for electrolyzing water and a preparation method and application thereof, and a proton exchange membrane electrolytic bath. The preparation method of the anode catalyst layer of the membrane electrode comprises the following steps: preparing various anode catalyst layer slurry; each slurry is obtained by uniformly mixing an electrolyzed water anode catalyst with Nafion resin, short-chain mono-alcohol, deionized water and acid leaching pore-forming powder; compared with different slurries, the mass parts of other components except the acid leaching pore-forming powder are the same; sequentially coating one surface of a proton membrane with the slurry according to the sequence of the mass parts of the acid leaching pore-forming powder from low to high; the obtained proton membrane is soaked in an acid solution, and after the acid leaching pore-forming powder on the proton membrane fully reacts with acid, deionized water soaking and cleaning are carried out for several times. The method has the advantages that a gradient uniformly-distributed pore structure is constructed, the porosity close to a proton membrane is low, the porosity far away from the proton membrane is high, and the resistance caused by gas diffusion is reduced, so that the PEM electrolyzed water performance is improved.

Description

Technical Field

[0001] The present invention relates to the field of proton exchange membrane water electrolysis, and in particular to an anode catalyst layer composite slurry and a preparation method thereof, a membrane electrode for water electrolysis and a preparation method and application thereof, and a proton exchange membrane electrolyzer. Background Art

[0002] Proton exchange membrane (PEM) water electrolysis hydrogen production technology has become an important research direction in the field of clean energy due to its advantages such as high efficiency, environmental protection, and fast response speed. The membrane electrode assembly (MEA) is the core component of PEM water electrolysis, and the performance of the catalytic layer directly determines the efficiency of water electrolysis. During the water electrolysis reaction, the anode catalyst layer area, under the action of an external power supply, causes water molecules to dissociate at the active sites of the catalytic layer, producing a large amount of oxygen and hydrogen ions, while electrons flow to the external power supply; the cathode catalyst layer area reacts the hydrogen ions transmitted from the heavy anode with the electrons conducted from the external power supply, producing a large amount of hydrogen. Therefore, improving the gas conduction efficiency in the catalytic layer can effectively improve the performance of the membrane electrode.

[0003] In the prior art, methods such as optimizing catalyst distribution and adjusting the content of proton exchange materials are commonly used to improve the performance of the catalytic layer. However, these methods often struggle to balance catalyst utilization and proton transfer efficiency. Furthermore, the high cost and complex removal of pore-forming agents (such as polymer microspheres) used in traditional pore-forming processes limit their application in large-scale production.

[0004] Patent number CN 112259749 A, published on January 22, 2021, titled "An Ultrasonic Spraying Method for Preparing a Porous Catalytic Layer for a Fuel Cell Membrane Electrode." This method utilizes system control to assist in the preparation of a gradient membrane electrode. However, the spraying process requires continuous adjustment of spray parameters, resulting in a complex and lengthy process cycle, and the catalyst layer may exhibit uneven thickness.

[0005] The patent number CN 211637051 U published on October 9, 2020 is "A spraying tool for improving the efficiency of CCM preparation." This invention improves production efficiency by optimizing the structural design. It mainly includes a frame and a spray box mounted on the frame. In addition, the material transfer assembly also integrates a flip-type workpiece clamping mechanism to optimize the CCM (catalytic membrane electrode) preparation process. However, although this design has increased production speed, it still has the technical limitation of insufficient uniformity of spray thickness.

[0006] Therefore, it is necessary to improve and optimize the existing membrane electrode and its preparation method so that it can better meet user needs. Summary of the Invention

[0007] The purpose of the embodiments of the present invention is to address the shortcomings of the existing technical structure and propose an anode catalyst layer combination slurry and preparation method, a membrane electrode for water electrolysis and its preparation method and application, and a proton exchange membrane electrolyzer. It proposes using iron oxide powder, calcium oxide powder, and calcium carbonate powder as pore-forming agents. By adding different proportions of pore-forming agents to the catalyst layer slurry, a gradient and uniformly distributed pore structure is formed in the catalyst layer, thereby significantly improving the efficiency of PEM water electrolysis.

[0008] In order to achieve the above-mentioned object of the invention, the present invention first proposes a method for preparing an anode catalyst layer composite slurry, which is characterized by comprising the following steps:

[0009] A variety of anode catalyst layer slurries are prepared; each slurry is obtained by uniformly mixing an electrolytic water anode catalyst with a Nafion resin, a short-chain monoalcohol, deionized water, and an acid-leached pore-forming powder; compared with different slurries, the mass fractions of the electrolytic water anode catalyst, the Nafion resin, the short-chain monoalcohol, and the deionized water are the same, while the mass fractions of the acid-leached pore-forming powder are different; the acid-leached pore-forming powder includes one or more of iron oxide powder, calcium oxide powder, and calcium carbonate powder, and its particle size is 50-300 nm; the mass ratio of the acid-leached pore-forming powder to the catalyst in the slurry is 0.09-0.3.

[0010] Further preferably, between any two slurries having similar mass fractions of acid-leached pore-forming powder, the mass fraction ratio of the acid-leached pore-forming powder is 1.5-2.

[0011] Further preferably, the number of anode catalyst layer slurries prepared is three, and the mass ratio of the acid-leached pore-forming powders of the three slurries is 1:2:3.

[0012] Further preferably, the solid content of the slurry is 1-30%; the short-chain monoalcohol includes one or more of n-propanol, isopropanol, and ethanol.

[0013] In addition, an embodiment of the present invention further provides an anode catalyst layer composite slurry, which is manufactured by the above-mentioned preparation method.

[0014] In addition, an embodiment of the present invention further provides a method for preparing a membrane electrode for water electrolysis, wherein the anode catalyst layer of the membrane electrode is prepared by the following method:

[0015] The slurry prepared by the above method is sequentially coated on one side of the proton membrane, and the coating order satisfies the following requirements: the mass fraction of the acid-leached pore-forming powder in the slurry close to the proton membrane is the lowest, and increases with the coating order. After each coating of the slurry is dried and solidified, the next coating is carried out; then the obtained proton membrane is immersed in an acidic solution, and after the acid-leached pore-forming powder on it fully reacts with the acid, it is immersed in deionized water for several times for cleaning.

[0016] Further preferably, the method for preparing a membrane electrode for electrolyzing water further comprises the following steps: conducting a conductivity test on the deionized water after soaking and filtration, and completing the soaking and cleaning step after the conductivity reaches below 10 μs / cm.

[0017] Further preferably, the acidic solution is one or more of sulfuric acid solution, acetic acid solution or hydrochloric acid solution, wherein the pH is between 2-4, and the soaking time is 1-5 hours.

[0018] In addition, an embodiment of the present invention further provides a membrane electrode for water electrolysis, wherein the anode catalyst layer of the membrane electrode is manufactured by the above-mentioned preparation method.

[0019] It should be understood that the present invention is intended to improve the microstructure of the anode catalyst layer of a membrane electrode for water electrolysis, and does not involve adjusting the anode catalyst layer's composition. The anode catalyst layer slurry or the anode catalyst layer before acid leaching and cleaning, except for the acid-leached pore-forming powder, contains conventional anode catalyst layer components, and the acid-leached pore-forming powder does not chemically react with these components. After acid leaching and cleaning, the acid-leached pore-forming powder is dissolved and cleaned by acid, forming pores in the catalyst layer. At this point, the material composition of the catalyst layer is the same as that of a conventional catalyst layer.

[0020] Therefore, the components of the anode catalyst layer of the membrane electrode for water electrolysis before and after the application date of the present invention can obtain a gradient microscopic pore structure through the process of the present invention, and the slurry, membrane electrode and proton exchange membrane electrolyzer obtained by the preparation method of the present invention with these proportions, as well as the corresponding preparation methods, all fall within the scope of protection of the present invention.

[0021] In addition, an embodiment of the present invention further provides a proton exchange membrane electrolyzer, comprising the membrane electrode for electrolysis of water produced by the above-mentioned method for producing the membrane electrode for electrolysis of water or the above-mentioned membrane electrode for electrolysis of water.

[0022] In addition, the embodiments of the present invention further provide the use of the membrane electrode for electrolysis of water produced by the above-mentioned membrane electrode for electrolysis of water preparation method or the above-mentioned membrane electrode for electrolysis of water in hydrogen production by electrolysis of water.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects: the present invention proposes to use iron oxide powder, calcium oxide powder, and calcium carbonate powder as acid leaching pore-forming powders, and to add different proportions of acid leaching pore-forming powders into the catalyst layer slurry. By adjusting the mass ratio of acid leaching pore-forming powder / anode catalyst, the porosity close to the proton exchange membrane is low, and the porosity of the catalyst layer away from the proton exchange membrane is high, thereby constructing a gradient and uniformly distributed pore structure to reduce the resistance caused by gas diffusion, thereby effectively improving the PEM electrolysis water performance. Not only that, the cost of the pore-forming agent used in this application is much lower than that of traditional polymer pore-forming agents (such as PTFE / PVDF microspheres). Compared with the CN 112259749 A solution, which requires real-time adjustment of spray parameters, this method is more stable and more controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above features and advantages of the present invention will become more clear and easily understood through the following description of exemplary embodiments thereof in conjunction with the accompanying drawings.

[0025] Figure 1 Schematic diagram of the semi-CCM structure containing an anode in Example 1;

[0026] Figure 2 Schematic diagram of the structure of a semi-CCM containing an anode in Example 2;

[0027] Figure 3 Schematic diagram of the semi-CCM structure containing an anode in Example 3;

[0028] Figure 4 Schematic diagram of the semi-CCM structure containing an anode in Example 4;

[0029] Figure 5 Schematic diagram of the semi-CCM structure containing an anode in Example 4;

[0030] Figure 6 Schematic diagram of the semi-CCM structure containing an anode in Example 4;

[0031] Figure 7 is the membrane electrode performance polarization curve;

[0032] Figure 8 This is a microscope picture of the anode catalyst layer surface;

[0033] Figure 9 This is the SEM image of the anode catalyst layer surface;

[0034] Figure 10 This is the SEM cross-sectional view of the anode catalyst layer. DETAILED DESCRIPTION

[0035] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0036] The terms "front", "back", "left", "right", "inside", and "outside" used in this specification are for the purpose of clarification only and are not intended to limit the scope of the present invention. Any changes or adjustments to their relative relationships, without substantially changing the technical content, should be considered within the scope of the present invention.

[0037] In the following descriptions of the embodiments, unless otherwise specified or limited, the term "connection" and other terms should be understood in a broad sense. For example, "connection" can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a mechanical connection or an indirect connection through an intermediate medium; it can refer to internal communication between two components or an interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0038] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and examples, but the present invention is not limited to the scope of the examples. The process parameters not specified in the examples of this application can be carried out according to conventional methods, and the raw materials used can be obtained through commercial channels.

[0039] Example 1

[0040] An acid leaching multi-gradient pore-forming technology is applied to the preparation of an anode catalyst layer for water electrolysis, characterized in that it comprises the following steps:

[0041] (1) Anode catalyst layer slurry preparation: First, weigh the iridium oxide catalyst, place it in a brown glass bottle, and add deionized water, isopropanol and ionomer in sequence. Among them, the mass ratio of ionomer to catalyst (I / C) is 0.1, the alcohol / water ratio is 2, and the solid content is 1%. Place the mixture in an ultrasonic cleaner and disperse it for 5 minutes. Divide the treated slurry into 3 parts, add acid-leached pore-forming powder and iron oxide with a mass ratio of 0.1, 0.2 and 0.3 of catalyst respectively, use an ultrasonic cell disruptor to treat for 30 minutes, and then transfer to a high-speed shear machine for treatment for 30 minutes; and name them A1 slurry, B1 slurry and C1 slurry in sequence;

[0042] (2) Preparation of anode catalyst layer: An ultrasonic sprayer was used to spray slurries C1 (near the membrane), B1 (middle layer), and A1 (far from the membrane) in sequence. The number of spraying times was 15, the spray flow rate was 2 ml / min, the heating plate temperature was 85 °C, and the nozzle running distance was 6 mm. A proton exchange membrane loaded only with the anode catalyst layer (referred to as semi-CCM in this article) was prepared. The structure of the catalyst layer was A1, B1, and C1, and the catalyst loading was 0.75 mg / cm 2 ,like Figure 1 As shown;

[0043] (3) Preparation of full membrane electrode: Using an ultrasonic sprayer, the HER end catalytic layer is prepared on the semi-CCM with the anode catalyst layer to prepare a complete water electrolysis membrane electrode;

[0044] (4) Acid leaching and pore formation: The prepared MEA is placed in a hydrochloric acid solution and soaked for 3 hours to allow the iron oxide to fully react with the hydrochloric acid and dissolve in the acidic solution to form a gradient structure of the pores in the catalyst layer;

[0045] (5) Cleaning: After acid leaching, the MEA is soaked in deionized water for 3-6 times for cleaning. The conductivity of the water after soaking and filtration is tested and must meet the requirements of less than 10us / cm;

[0046] In Example 1, step 3 is to prepare the HER end catalytic layer on the semi-CCM with the anode catalyst layer to prepare a complete water electrolysis membrane electrode, and then acid leaching and cleaning. However, this order is not the only option for manufacturing proton exchange membranes. The HER end catalytic layer can also be prepared first, or the HER end catalytic layer can be prepared after the cleaning step of the anode catalyst layer is completed.

[0047] Since the HER-side catalytic layer and its preparation are not the innovation of this application, except for Example 1, the following examples omit the preparation process of the HER-side catalytic layer and only describe the preparation method and process differences of the anode catalytic layer.

[0048] Example 2

[0049] An acid leaching multi-gradient pore-forming technology is applied to the preparation of an anode catalyst layer for water electrolysis, characterized in that it comprises the following steps:

[0050] (1) Anode catalyst layer slurry preparation: First, weigh the iridium oxide catalyst and place it in a brown glass bottle. Then, add deionized water, isopropyl alcohol, and ionomer in sequence. Among them, I / C is 0.1, alcohol / water is 2, and solid content is 1%. Place the mixture in an ultrasonic cleaner and disperse it for 5 minutes. Divide the treated slurry into 3 parts, add acid-leached pore-forming powder and calcium carbonate with a mass ratio of 0.1, 0.2, and 0.3 to the catalyst respectively, and treat it in an ultrasonic cell disruptor for 30 minutes. Then, transfer it to a high-speed shearing machine for 30 minutes; and name them A2 slurry, B2 slurry, and C2 slurry in sequence.

[0051] (2) Preparation of anode catalyst layer: An ultrasonic sprayer was used to spray slurries C2, B2, and A2 in sequence. The number of spraying times was 15, the spray flow rate was 2 ml / min, the heating plate temperature was 85 °C, and the nozzle running distance was 6 mm. Semi-CCM (the structure of the catalytic layer was A2, B2, and C2) was prepared, in which the catalyst loading was 0.75 mg / cm 2 ,like Figure 2 As shown;

[0052] (3) Acid leaching and pore formation: The prepared MEA is placed in a hydrochloric acid solution and soaked for 3 hours to allow the calcium carbonate to fully react with the hydrochloric acid and dissolve in the acidic solution to form a gradient structure of the pores in the catalyst layer;

[0053] (4) Cleaning: After acid leaching, the MEA is soaked in deionized water for 3-6 times for cleaning. The conductivity of the water after soaking and filtration is tested and must meet the requirements of less than 10us / cm;

[0054] Example 3

[0055] An acid leaching multi-gradient pore-forming technology is applied to the preparation of an anode catalyst layer for water electrolysis, characterized in that it comprises the following steps:

[0056] (1) Anode catalyst layer slurry preparation: First, weigh the iridium oxide catalyst and place it in a brown glass bottle. Then, add deionized water, isopropyl alcohol, and ionomer in sequence. The I / C ratio is 0.1, the alcohol / water ratio is 2, and the solid content is 8%. Place the mixture in an ultrasonic cleaner and disperse it for 5 minutes. Divide the treated slurry into three parts, add iron oxide with a mass ratio of 0.1, 0.2, and 0.3 of acid-leached pore-forming powder and catalyst, respectively, and treat them in an ultrasonic cell disruptor for 30 minutes. Then, name them A3 slurry, B3 slurry, and C3 slurry in sequence.

[0057] (2) Preparation of anode catalyst layer: Slurries A3, B3 and C3 were sequentially scraped onto a PTFE (Nissin 900UL) transfer membrane using a doctor blade process. The catalyst layer on the PTFE was then transferred onto a proton exchange membrane using a thermal transfer method to prepare a semi-CCM (the structure of the catalyst layer was A3, B3, and C3), with a catalyst loading of 0.75 mg / cm 2 ,like Figure 3 As shown;

[0058] (3) Acid leaching and pore formation: The prepared MEA is placed in a hydrochloric acid solution and soaked for 3 hours to allow the iron oxide to fully react with the hydrochloric acid and dissolve in the acidic solution to form a gradient structure of the pores in the catalyst layer;

[0059] (4) Cleaning: The MEA after acid leaching is soaked in deionized water for 3-6 times for cleaning, and the conductivity of the water after soaking and filtration is tested, which must be below 10us / cm.

[0060] Examples 1-3 are used for comparison, and the expected performance is not as good as the gradient decreasing structure of Examples 4-6.

[0061] Example 4

[0062] An acid leaching multi-gradient pore-forming technology is applied to the preparation of an anode catalyst layer for water electrolysis, characterized in that it comprises the following steps:

[0063] (1) Anode catalyst layer slurry preparation: First, weigh the iridium oxide catalyst and place it in a brown glass bottle. Then, add deionized water, isopropyl alcohol, and ionomer in sequence. The I / C ratio is 0.1, the alcohol / water ratio is 2, and the solid content is 1%. Place the mixture in an ultrasonic cleaner and disperse it for 5 minutes. Divide the treated slurry into three parts, add iron oxide with a mass ratio of 0.1, 0.2, and 0.3 of acid-leached pore-forming powder and catalyst, respectively, and treat them in an ultrasonic cell disruptor for 30 minutes. Then, name them A1 slurry, B1 slurry, and C1 slurry in sequence.

[0064] (2) Preparation of anode catalyst layer: An ultrasonic sprayer was used to spray slurries A1, B1, and C1 in sequence. The number of spraying times was 15, the spray flow rate was 2 ml / min, the heating plate temperature was 85 °C, and the nozzle running distance was 6 mm. Semi-CCM (the structure of the catalytic layer was A1, B1, and C1) was prepared, in which the catalyst loading was 0.75 mg / cm 2 ,like Figure 4 As shown;

[0065] (3) Acid leaching and pore formation: The prepared MEA is placed in a hydrochloric acid solution and soaked for 3 hours to allow the calcium carbonate to fully react with the hydrochloric acid and dissolve in the acidic solution to form a gradient structure of the pores in the catalyst layer;

[0066] (4) Cleaning: The MEA after acid leaching is soaked in deionized water for 3-6 times for cleaning, and the conductivity of the water after soaking and filtration is tested, which must be below 10us / cm.

[0067] Example 5

[0068] An acid leaching multi-gradient pore-forming technology is applied to the preparation of an anode catalyst layer for water electrolysis, characterized in that it comprises the following steps:

[0069] (1) Anode catalyst layer slurry preparation: First, weigh the iridium oxide catalyst and place it in a brown glass bottle. Then, add deionized water, isopropyl alcohol, and ionomer in sequence. The I / C ratio is 0.1, the alcohol / water ratio is 2, and the solid content is 1%. Place the mixture in an ultrasonic cleaner and disperse it for 5 minutes. Divide the treated slurry into three parts, add acid-leached pore-forming powder and calcium carbonate with a mass ratio of 0.1, 0.2, and 0.3 of catalyst respectively, and treat them in an ultrasonic cell disruptor for 30 minutes. Then, name them A2 slurry, B2 slurry, and C2 slurry in sequence.

[0070] (2) Preparation of anode catalyst layer: An ultrasonic sprayer was used to spray slurries A2, B2, and C2 in sequence. The number of spraying times was 15, the spray flow rate was 2 ml / min, the heating plate temperature was 85 °C, and the nozzle running distance was 6 mm. Semi-CCM (the structure of the catalytic layer was C2, B2, and A2) was prepared, in which the catalyst loading was 0.75 mg / cm 2 ,like Figure 5 As shown;

[0071] (3) Acid leaching and pore formation: The prepared MEA is placed in a hydrochloric acid solution and soaked for 3 hours to allow the calcium carbonate to fully react with the hydrochloric acid and dissolve in the acidic solution to form a gradient structure of the pores in the catalyst layer;

[0072] (4) Cleaning: After acid leaching, the MEA is soaked in deionized water for 3-6 times for cleaning. The conductivity of the water after soaking and filtration is tested and must meet the requirements of less than 10us / cm;

[0073] Example 6

[0074] An acid leaching multi-gradient pore-forming technology is applied to the preparation of an anode catalyst layer for water electrolysis, characterized in that it comprises the following steps:

[0075] (1) Anode catalyst layer slurry preparation: First, weigh the iridium oxide catalyst and place it in a brown glass bottle. Then, add deionized water, isopropyl alcohol, and ionomer in sequence. The I / C ratio is 0.1, the alcohol / water ratio is 2, and the solid content is 8%. Place the mixture in an ultrasonic cleaner and disperse it for 5 minutes. Divide the treated slurry into three parts, add iron oxide with a mass ratio of 0.1, 0.2, and 0.3 of acid-leached pore-forming powder and catalyst, respectively, and treat them in an ultrasonic cell disruptor for 30 minutes. Then, name them A3 slurry, B3 slurry, and C3 slurry in sequence.

[0076] (2) Preparation of anode catalyst layer: Slurries C3, B3, and A3 were sequentially scraped onto a PTFE (Nissin 900UL) transfer membrane using a doctor blade process. The catalyst layer on the PTFE was then transferred onto a proton exchange membrane using a thermal transfer method to prepare a semi-CCM (the structure of the catalyst layer was C3, B3, and A3), with a catalyst loading of 0.75 mg / cm 2 ,like Figure 6 As shown;

[0077] (3) Acid leaching and pore formation: The prepared MEA is placed in a hydrochloric acid solution and soaked for 3 hours to allow the calcium carbonate to fully react with the hydrochloric acid and dissolve in the acidic solution to form a gradient structure of the pores in the catalyst layer;

[0078] (4) Cleaning: After acid leaching, the MEA is soaked in deionized water for 3-6 times for cleaning. The conductivity of the water after soaking and filtration is tested and must meet the requirements of less than 10us / cm;

[0079] Comparative Example 1

[0080] An acid leaching multi-gradient pore-forming technology is applied to the preparation of an anode catalyst layer for water electrolysis, characterized in that it comprises the following steps:

[0081] (1) Anode catalyst layer slurry preparation: First, weigh the iridium oxide catalyst and place it in a brown glass bottle. Then, add deionized water, isopropyl alcohol, and ionomer in that order. The I / C ratio is 0.1, the alcohol / water ratio is 2, and the solid content is 1%. Place the mixture in an ultrasonic cleaner and disperse it for 5 minutes. Then, add iron oxide with a mass ratio of 0.2 between the acid-leached pore-forming powder and the catalyst.

[0082] (2) Preparation of anode catalyst layer: The slurry was sprayed using an ultrasonic sprayer with a spray flow rate of 2 ml / min, a heating plate temperature of 85 °C, and a nozzle running distance of 6 mm to prepare a semi-CCM (the structure of the catalyst layer is a single layer), in which the catalyst loading is 0.75 mg / cm 2 ;

[0083] (3) Acid leaching and pore formation: The prepared MEA is placed in a hydrochloric acid solution and soaked for 3 hours to allow the calcium carbonate to fully react with the hydrochloric acid and dissolve in the acidic solution to form a gradient structure of the pores in the catalyst layer;

[0084] (4) Cleaning: After acid leaching, the MEA is soaked in deionized water for 3-6 times for cleaning. The conductivity of the water after soaking and filtration is tested and must meet the requirements of less than 10us / cm;

[0085] Comparative Example 2

[0086] An acid leaching multi-gradient pore-forming technology is applied to the preparation of an anode catalyst layer for water electrolysis, characterized in that it comprises the following steps:

[0087] (1) Anode catalyst layer slurry preparation: First, weigh the iridium oxide catalyst and place it in a brown glass bottle. Then, add deionized water, isopropyl alcohol, and ionomer in that order. The I / C ratio is 0.1, the alcohol / water ratio is 2, and the solid content is 8%. Place the mixture in an ultrasonic cleaner and disperse it for 5 minutes. Then, add iron oxide with a mass ratio of 0.2 between the acid-leached pore-forming powder and the catalyst.

[0088] (2) Preparation of anode catalyst layer: The slurry was scraped onto a PTFE (Nissin 900UL) transfer membrane using a doctor blade process. The catalyst layer on the PTFE was then transferred to a proton exchange membrane using a thermal transfer method to prepare a semi-CCM (the structure of the catalyst layer is a single layer), where the catalyst loading is 0.75 mg / cm 2 ;

[0089] (3) Acid leaching and pore formation: The prepared MEA is placed in a hydrochloric acid solution and soaked for 3 hours to allow the calcium carbonate to fully react with the hydrochloric acid and dissolve in the acidic solution to form a gradient structure of the pores in the catalyst layer;

[0090] (4) Cleaning: After acid leaching, the MEA is soaked in deionized water for 3-6 times for cleaning. The conductivity of the water after soaking and filtration is tested and must meet the requirements of less than 10us / cm;

[0091] Comparative Example 3

[0092] An acid leaching multi-gradient pore-forming technology is applied to the preparation of an anode catalyst layer for water electrolysis, characterized in that it comprises the following steps:

[0093] (1) Anode catalyst slurry preparation: First, weigh the iridium oxide catalyst and place it in a brown glass bottle. Then, add deionized water, isopropyl alcohol, and ionomer in that order. The I / C ratio is 0.1, the alcohol / water ratio is 2, and the solid content is 1%. Place the mixture in an ultrasonic cleaner and disperse it for 5 minutes.

[0094] (2) Preparation of anode catalyst layer: The slurry was sprayed using an ultrasonic sprayer with a spray flow rate of 2 ml / min, a heating plate temperature of 85 °C, and a nozzle running distance of 6 mm to prepare a semi-CCM (the structure of the catalyst layer is a single layer), in which the catalyst loading is 0.75 mg / cm 2 ;

[0095] (3) Acid leaching and pore formation: The prepared MEA was placed in a hydrochloric acid solution and soaked for 3 hours;

[0096] (4) Cleaning: After acid leaching, the MEA is soaked in deionized water for 3-6 times for cleaning. The conductivity of the water after soaking and filtration is tested and must meet the requirements of less than 10us / cm;

[0097] Comparative Example 4

[0098] An acid leaching multi-gradient pore-forming technology is applied to the preparation of an anode catalyst layer for water electrolysis, characterized in that it comprises the following steps:

[0099] (1) Anode catalyst layer slurry preparation: First, weigh the iridium oxide catalyst and place it in a brown glass bottle. Then, add deionized water, isopropyl alcohol, and ionomer in that order. The I / C ratio is 0.1, the alcohol / water ratio is 2, and the solid content is 8%. Place the mixture in an ultrasonic cleaner and disperse it for 5 minutes.

[0100] (2) Preparation of the anode catalyst layer: The slurry is scraped onto a PTFE (Nissin 900UL) transfer base membrane using a doctor blade process. The catalyst layer on the PTFE is then transferred to the proton exchange membrane using a thermal transfer method to prepare a semi-CCM (the catalyst layer structure is a single layer);

[0101] (3) Acid leaching and pore formation: The prepared MEA was placed in a hydrochloric acid solution and soaked for 3 hours;

[0102] (4) Cleaning: After acid leaching, the MEA is soaked in deionized water for 3-6 times for cleaning. The conductivity of the water after soaking and filtration is tested and must meet the requirements of less than 10us / cm;

[0103] In summary, all water electrolysis test conditions are as follows: the electrolytic cell test temperature is 60°C, there is no back pressure, the circulating water flow rate is 10ml / min, the test fixture assembly pressure is 8Nm, and the test area is 5*5; in summary, all water electrolysis material selections are as follows: the anode diffusion layer is titanium adhesive (Heraeus commercial product), the cathode diffusion layer is (Toray 055), the proton exchange membrane is (Chemours N115 membrane), and the cathode catalyst is (JM40).

[0104] Membrane electrode performance Figure 7As shown, under the constant current test condition of 4A / cm2, the corresponding voltages of Examples 1-6 are 2.06, 2.09, 2.07, 2.16, 2.18 and 2.17V, respectively, and the corresponding voltages of Comparative Examples 1-4 are 2.13, 2.11, 2.15 and 2.14V, respectively.

[0105] pass Figure 7 Polarization curve analysis shows that the performance differences between Example 1 and Example 4 at various current densities are due to differences in the pore structure of the catalyst layer. This difference is attributed to differences in gas diffusion resistance between the two. Starting with the proton exchange membrane, the gradual increase in the porosity of the catalyst layer is beneficial for improving the gas transfer efficiency of the membrane electrode.

[0106] The above embodiments describe in detail the inventive intent and implementation methods of the present invention. However, those skilled in the art will appreciate that the above embodiments are only preferred embodiments of the present invention. Due to space limitations, not all implementation methods are listed here. Any implementation that can embody the technical solutions of the claims of the present invention is within the scope of protection of the present invention.

[0107] It should be noted that the above content is a further detailed description of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation methods of the present invention are limited to these. Under the guidance of the above embodiments, those skilled in the art can make various improvements and modifications on the basis of the above embodiments, and these improvements or modifications fall within the scope of protection of the present invention.

Claims

1. A method for preparing an anode catalyst layer composite slurry, characterized in that The steps include: A variety of anode catalyst layer slurries are prepared; each slurry is obtained by uniformly mixing an electrolytic water anode catalyst with a Nafion resin, a short-chain monoalcohol, deionized water, and an acid-leached pore-forming powder; compared with different slurries, the mass fractions of the electrolytic water anode catalyst, the Nafion resin, the short-chain monoalcohol, and the deionized water are the same, while the mass fractions of the acid-leached pore-forming powder are different; the acid-leached pore-forming powder includes one or more of iron oxide powder, calcium oxide powder, and calcium carbonate powder, and its particle size is 50-300 nm; the mass ratio of the acid-leached pore-forming powder to the catalyst in the slurry is 0.09-0.

3.

2. The method for preparing an anode catalyst layer composite slurry according to claim 1, characterized in that: Between any two slurries with similar mass fractions of acid-leached pore-forming powder, the mass fraction ratio of the acid-leached pore-forming powder is 1.5-2.

3. The method for preparing an anode catalyst layer composite slurry according to claim 1, characterized in that: Three anode catalyst layer slurries were prepared, and the mass ratio of the acid-leached pore-forming powders in the three slurries was 1:2:

3.

4. The method for preparing an anode catalyst layer composite slurry according to claim 1, characterized in that: The solid content of the slurry is 1-30%; the short-chain monoalcohol includes one or more of n-propanol, isopropanol and ethanol.

5. An anode catalyst layer composite slurry, characterized by: It is manufactured by the preparation method according to any one of claims 1 to 4.

6. A method for preparing a membrane electrode for water electrolysis, characterized in that The anode catalyst layer of the membrane electrode is prepared by the following method: The slurry prepared according to any one of claims 1 to 4 is sequentially coated on one side of the proton membrane, and the coating order satisfies: the mass fraction of the acid-leached pore-forming powder in the slurry close to the proton membrane is the lowest, and increases with the coating order. After each coating of the slurry is dried and solidified, the next coating is carried out; then, the obtained proton membrane is immersed in an acidic solution, and after the acid-leached pore-forming powder on it fully reacts with the acid, it is immersed in deionized water for several times for cleaning.

7. The method for preparing a membrane electrode for water electrolysis according to claim 6, characterized in that The method further includes the following steps: conducting a conductivity test on the deionized water after immersion, and completing the immersion and cleaning step after the conductivity reaches below 10 us / cm.

8. The method for preparing a membrane electrode for water electrolysis according to claim 7, wherein: The acidic solution is one or more of a sulfuric acid solution, an acetic acid solution or a hydrochloric acid solution, wherein the pH is between 2 and 4, and the soaking time is 1 to 5 hours.

9. A membrane electrode for water electrolysis, characterized in that: The anode catalyst layer of the membrane electrode is manufactured by the preparation method according to claim 7 or 8.

10. A proton exchange membrane electrolyzer, characterized in that: It includes a membrane electrode for electrolysis of water obtained by the preparation method according to claim 7 or 8 or a membrane electrode for electrolysis of water according to claim 9.

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