A dry method electrode pole piece for electrolyzing water and a preparation method and application thereof

Abstract

This invention relates to a dry-process electrode sheet and its preparation method. Without the use of solvents, based on a powder electrode forming method, powdered active materials and powdered binders are mixed and pulverized to prepare a powder mixture with uniform size distribution. Then, the powder binder is fiberized using a twin-screw extruder or open mill to prepare a dry-process electrode sheet film. The target electrode sheet thickness and compaction density are then achieved using a rolling mill. This electrode sheet film can be directly fabricated into a dry-process battery electrode sheet, which can be independently assembled as a catalyst layer in water electrolysis. This invention further includes a dry-process battery electrode sheet combining the electrode sheet film and an electrode substrate, which can be independently assembled as an electrode or membrane electrode in water electrolysis. This invention does not involve solvents, effectively reducing the cost of solvent use and drying processes during preparation.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis technology, and in particular to a dry electrode sheet and its preparation method. Background Technology

[0002] Currently, the electrolysis of water typically employs solvent-based coating or spraying wet electrode manufacturing processes. These processes usually involve uniformly mixing catalysts, conductive agents, and polymers in a solution, then depositing the mixture onto an electrode substrate using coating or spraying methods, and finally forming the electrode through a drying process. This manufacturing method increases solvent costs due to the introduction of solvents, and the additional drying process to remove excess solvent results in high energy consumption and is environmentally unfriendly.

[0003] Dry electrode technology, on the other hand, involves directly mixing catalysts and other substances in powder or nanoparticle form under solvent-free conditions, and then pressing the mixture directly into electrode sheets to form the electrode. This simplifies the process, avoiding cumbersome steps such as solution preparation, coating, and drying, thus significantly improving preparation efficiency. Furthermore, since it does not require large amounts of solvent and energy for solution preparation and drying, dry electrode technology offers lower energy consumption and a smaller environmental impact. Therefore, dry electrode technology is of great significance in the field of water electrolysis.

[0004] Patent CN 109755473 A discloses a dry preparation method for lithium battery electrodes, which limits the raw materials used in the lithium battery electrodes. Patent CN 112420986 B discloses a dry preparation method for positive and negative electrode sheets of lithium batteries, which reduces battery polarization by adding solid electrolyte powder to the positive and negative electrodes. However, the above processes are mainly applied to lithium batteries and do not involve the application of water electrolysis. Summary of the Invention

[0005] This invention relates to a dry electrode sheet for water electrolysis and its preparation method, and the technical solution adopted is as follows:

[0006] A dry electrode sheet for water electrolysis, characterized in that the electrode sheet comprises at least a dry electrode film prepared by rolling a powder mixture, wherein the powder mixture comprises 80wt%-98wt% powder active material and 2wt%-20wt% powder binder, the electrode has a thickness of 20μm-500μm and a compaction density of 30.0mg / cm³. 3 -200.0 mg / cm 3 .

[0007] In one embodiment, the dry electrode membrane for water electrolysis proposed in this invention can be further bonded to one or both sides of the electrode substrate by hot pressing.

[0008] In one embodiment, the present invention provides a method for preparing a dry electrode sheet for water electrolysis, comprising the following steps:

[0009] (1) Mixing: Add the active powder and the powder binder to the mixer to obtain a uniformly mixed powder mixture, which includes 80wt%-98wt% active powder and 2wt%-20wt% powder binder;

[0010] (2) Crushing: The uniformly mixed powder mixture obtained in step (1) is crushed by an air jet mill to obtain a powder mixture with uniform particle size;

[0011] (3) Molding: The powder binder in the uniform particle size powder mixture obtained in step (2) undergoes a fiberization reaction by using a twin-screw extruder or open mill that can continuously provide high shear force. The fiberized powder mixture is then extruded or rolled into a sheet with a continuous thickness of 200μm-1000μm.

[0012] (4) Rolling: The sheet obtained in step (3) is rolled into an electrode film with a diameter of 20μm-500μm; the compaction density is 30.0mg / cm³. 3 -200.0 mg / cm 3 .

[0013] The present invention proposes an embodiment of a method for preparing a dry electrode sheet for water electrolysis, which further includes combining the electrode film produced in step (4) with an electrode substrate through a composite machine to form an electrode film / electrode substrate or an electrode film / electrode substrate / electrode film structure.

[0014] This invention proposes an embodiment of a method for preparing dry electrode sheets for water electrolysis, wherein the powder mixture further comprises 80wt%-98wt% powder active material, preferably 90wt%-98wt% powder active material, and the powder active material includes at least one metal, metal compound or alloy material selected from iron-based, cobalt-based, nickel-based or copper-based metals.

[0015] This invention proposes one embodiment of a method for preparing dry electrode sheets for water electrolysis, wherein the powder mixture further comprises 2wt%-20wt% powder binder, preferably 2wt%-10wt% powder binder, which is a mixture of one or more of polyvinylidene fluoride powder, polytetrafluoroethylene powder, acrylic resin powder, polymethacrylic acid resin powder, and styrene-butadiene rubber powder in any proportion.

[0016] This invention proposes one embodiment of a dry electrode preparation method for water electrolysis, wherein the electrode substrate includes, but is not limited to, nickel felt, stainless steel felt, nickel felt, nickel mesh, titanium mesh, nickel foam, aluminum felt, copper foam, and polymer film.

[0017] This invention proposes one embodiment of a method for preparing dry electrode sheets for water electrolysis, wherein the preparation process controls the temperature below the melting point of the powder binder.

[0018] The electrode film can be directly fabricated into a dry-process battery electrode and independently assembled as a catalyst layer in water electrolysis. This invention further includes a dry-process battery electrode composited with the electrode film and electrode substrate, which is independently assembled as an electrode or membrane electrode in water electrolysis. This invention does not involve solvents, effectively reducing the cost of solvent use and drying processes during preparation.

[0019] Compared with wet electrode processes, the advantages of this invention are that the electrode preparation process of this invention does not require the use of solvents, which reduces raw material costs and drying costs, shortens electrode preparation time, and avoids solvent contamination problems. Attached Figure Description

[0020] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0021] Figure 1 : A schematic diagram illustrating a dry electrode preparation method for use in the field of water electrolysis technology;

[0022] Figure 2 The dry electrode sheet obtained in Example 1 was used in a water electrolysis cell, and the current density curve was obtained at a cell voltage of 2V.

[0023] Figure 3 Current density test curves of electrode films of different thicknesses at a tank voltage of 2V;

[0024] Figure 4 Performance comparison chart of dry electrode and wet electrode under the same test conditions. Detailed Implementation

[0025] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0026] The following embodiments provide a dry electrode sheet for the field of water electrolysis technology and its preparation method, characterized in that the electrode sheet is prepared by laminating an electrode film formed by rolling a powder mixture with an electrode substrate. The process includes the following steps:

[0027] (1) Add active powder material and powder binder to a three-dimensional mixer for mixing so that the various powder mixtures are evenly distributed;

[0028] (2) The uniformly mixed powder mixture obtained in step (1) is pulverized by an air jet mill to obtain a powder mixture with uniform particle size;

[0029] (3) The uniformly sized powder mixture obtained in step (2) is extruded into 500 sheets using a twin-screw extruder;

[0030] (4) Roll the sheet obtained in step (3) into an electrode film;

[0031] (5) Combine the electrode film obtained in step (4) with the electrode substrate to form a two-in-one structure.

[0032] In step (1), the powder mixture further contains 80wt%-98wt% of powder active material, preferably 90wt%-98wt% of powder active material, which includes at least one metal, metal compound or alloy material selected from iron-based, cobalt-based, nickel-based or copper-based metals.

[0033] The powder mixture in step (1) further includes 2wt%-20wt% powder binder, preferably 2wt%-10wt% powder binder, which is a mixture of one or more of polyvinylidene fluoride powder, polytetrafluoroethylene powder, acrylic resin powder, polymethyl methacrylate resin powder, and styrene-butadiene rubber powder in any proportion.

[0034] In step (4), the electrode film thickness is 20μm-500μm, and the compaction density is 30.0mg / cm³. 3 -200.0 mg / cm 3 ;

[0035] In step (5), the electrode substrate includes, but is not limited to, nickel felt, stainless steel felt, nickel felt, nickel mesh, titanium mesh, nickel foam, aluminum felt, copper foam, and polymer film.

[0036] The above preparation process controls the temperature below the melting point of the powder binder in step (1).

[0037] Example 1

[0038] A dry electrode sheet for use in water electrolysis and its preparation method, comprising the following steps:

[0039] (1) Add 97wt% of nano-iron-nickel-cobalt alloy powder (particle size 8-13μm) and 3wt% of polytetrafluoroethylene (PTFE) powder binder (particle size 7-9μm) to a three-dimensional mixer. Set the mixing time to 3 hours, the mixing speed to 400r / min, and the stirring temperature to 30℃ until a uniformly mixed powder mixture is obtained.

[0040] (2) The uniformly mixed powder is pulverized by an air jet mill, using nitrogen as the working gas, with the pressure set at 0.6 MPa and the temperature controlled at 25°C. After pulverization, a uniform powder with a particle size of approximately 2.7–4.2 μm is obtained.

[0041] (3) The pulverized powder mixture was extruded through a twin-screw extruder. The extrusion temperature was set to 80℃ and the extrusion speed was 30mm / s to obtain a sheet with a thickness of 500μm and a fiberization rate of 86%. The screw speed of the extruder was set to 60rpm and the extrusion pressure was maintained at 2MPa to ensure uniform flow of the material throughout the extrusion process. After extrusion, the sheet was cooled to room temperature.

[0042] (4) The extruded sheet is passed through a calender and rolled at 100°C with a rolling pressure of 20 MPa to a thickness of 200 μm. The final compacted density is 180 mg / cm³. 3 The roller speed of the roller press is set to 10 rpm, and the roller gap is precisely controlled to 0.2 mm to ensure uniform compaction and consistent thickness of the sheet. The surface of the sheet after roller pressing must be smooth and free of cracks to obtain the anode electrode film.

[0043] The anode film prepared in this embodiment, together with the anode diffusion layer (nickel felt) and PiperION... TM A40 anion exchange membrane, platinum black carbon paper cathode (platinum black content 2.0 mg / cm³) 2 An electrolytic cell (Fuel cell, 11060028) was assembled using 1M KOH as the electrolyte. Figure 2 It can be seen that in an electrolytic water cell using this dry electrode, the reaction current density reaches as high as 1 Acm under a cell voltage of 2V. -2 It exhibits high activity.

[0044] Example 2

[0045] A dry electrode fabrication method for composite nickel foam substrates with electrode films of different thicknesses:

[0046] (1) 90wt% iron-nickel alloy powder active material (5.6μm-6μm, Shijiaweier) and 10wt% PVDF powder (12-18μm) binder were added to a three-dimensional mixer for mixing. The mixing time was 2 hours, the speed was 1000r / min, and the stirring temperature was 30℃ to obtain a uniform powder mixture.

[0047] (2) The mixed powder was pulverized using an air jet mill. The particle size distribution after pulverization was controlled within 3-8 μm. The pulverization time was 2 hours, resulting in a homogeneous powder mixture. Nitrogen was used as the working gas during the pulverization process to prevent oxidation. The pressure of the pulverizing equipment was set to 0.7 MPa. After pulverization, samples were taken for particle size analysis to ensure that the particle size was controlled within the target range.

[0048] (3) The powder mixture was extruded through a twin-screw extruder to form sheets with thicknesses of 100μm, 200μm, and 300μm, respectively. The extrusion temperature was set at 80℃ and the extrusion speed was 25mm / s. During the extrusion process, the screw speed was controlled at 50rpm and the extrusion pressure was maintained at 2.5MPa. The extruded sheets were cooled by cooling rollers to ensure their dimensional stability.

[0049] (4) Electrode films of different thicknesses were rolled into electrode films with thicknesses of 50μm, 100μm, and 150μm respectively at 100℃ using a calender, with a compaction density of 150mg / cm³. 3 200mg / cm 3 and 250mg / cm 3 During the rolling process, the roller speed is set to 10 rpm and the roller gap is precisely adjusted to 0.05 mm to ensure uniform film thickness and avoid cracks or other defects, thus obtaining the anode electrode film.

[0050] (5) The rolled electrode film is hot-pressed onto the nickel foam substrate. The composite temperature is set to 120°C, the hot-pressing pressure is 3MPa, and the composite time is 15 minutes to form a composite anode structure of electrode film / nickel foam.

[0051] The composite electrode prepared in Example 2 was used as the anode for water electrolysis, with a platinum black carbon cloth electrode (2 mg / cm²). 2 Fuel cell (11060064) was used as the cathode, and the anion exchange membrane was PiperION. TM A40, water electrolysis test was performed in 1M KOH solution. (Example) Figure 3 As shown, under the test conditions of a constant terminal voltage of 2V and an electrode film thickness of 150μm, the reaction current density is 1.02Acm. -2 When the electrode film thickness is 100 μm, the reaction current density is 1.2 A cm⁻¹. -2Compared to an electrode film with a thickness of 150 μm, the current density increased by 17.6%; when the electrode film thickness was 50 μm, the reaction current density was 2 A / cm. -2 Compared to an electrode film with a thickness of 150 μm, the current density is increased by 96.1%.

[0052] Comparative Example 1

[0053] Performance comparison with wet electrodes:

[0054] (1) Iron-nickel alloy powder active material (5.6μm-6μm, SJM Micro) and PVDF powder (12-18μm) binder were dispersed in isopropanol solvent, wherein the mass ratio of iron-nickel alloy powder to PVDF powder was 9:1, and the mass ratio of solid to solvent was set to 1:24. Ultrasonic dispersion was performed for 1 hour using an ultrasonic disperser at a frequency of 40kHz and a temperature controlled at 25℃ to ensure that the powder was uniformly dispersed in the solvent and to obtain a uniform electrode slurry.

[0055] (2) Electrode slurry was uniformly deposited onto the nickel foam substrate using an ultrasonic spraying device. The spraying rate was set to 0.5 mL / min, and the substrate temperature was set to 60 °C. The spraying time was adjusted according to the target thickness until a 150 μm catalyst layer was formed. This catalyst layer combined with the nickel foam substrate to form a composite anode structure.

[0056] (3) The electrode obtained by spraying is placed in a vacuum drying oven and dried at 60°C for 2 hours to ensure that the solvent is completely evaporated, so as to obtain a wet electrode with a catalyst layer thickness of 150μm.

[0057] The prepared wet electrode was used as the anode for water electrolysis, and the platinum black carbon cloth electrode (2 mg / cm³) was used. 2 Fuel cell (11060064) was used as the cathode, and the anion exchange membrane was PiperION. TM A40, water electrolysis test was performed in 1M KOH solution. (Example) Figure 4 As shown, under the test condition of a constant terminal voltage of 2V, the wet electrode exhibits a current of 0.75A cm⁻¹. -2 The reaction current density was [not specified]; while in Example 2, a dry electrode of the same thickness achieved 1.02 A cm⁻¹ under the same test conditions. -2 The reaction current density improves performance by 36%.

[0058] Example 3

[0059] (1) Add 80wt% nickel powder (Beijing Gaoke New Material Technology, 8-12μm) and 20wt% polyvinylidene fluoride (PVDF, 15-30μm) powder binder to a three-dimensional mixer. Mix for 1 hour, at a speed of 200r / min, and at a stirring temperature of 20℃ until a uniform powder mixture is obtained.

[0060] (2) The uniformly mixed powder is pulverized by an air jet mill. The pulverization pressure is set to 0.2 MPa, the particle size after pulverization is 3 μm, and the temperature is controlled at 20℃.

[0061] (3) Extrusion was performed using a twin-screw extruder with a shear rate of 50 rpm and a temperature of 50 °C to obtain a sheet with a thickness of 200 μm.

[0062] (4) The sheet is pressed to a thickness of 20μm and a compaction density of 30mg / cm³ using a roller press at a pressure of 5MPa and a temperature of 60℃. 3 .

[0063] The anode film prepared in this embodiment, together with the anode diffusion layer (stainless steel felt) and PiperION... TM A40 anion exchange membrane, platinum black carbon paper cathode (platinum black content 2.0 mg / cm³) 2 An electrolytic cell (fuel cell, 11060028) was assembled using 1M KOH as the electrolyte. At a cell voltage of 2V, the reaction current density was 0.54 A cm⁻¹. -2 .

[0064] Example 4

[0065] (1) Add 89wt% of nickel-iron alloy powder (10-15μm) and 11wt% of PTFE powder binder (20-25μm) to a three-dimensional mixer. The mixing time is 3 hours, the speed is 500r / min, and the stirring temperature is 50℃ to obtain a uniform powder mixture.

[0066] (2) Use an air jet mill to pulverize the material. Set the pulverizing pressure to 0.5 MPa. The particle size after pulverization is 5 μm. The temperature is controlled at 40℃.

[0067] (3) Processed using a twin-screw extruder with a shear rate of 100 rpm and a temperature of 100 °C, forming a sheet of 500 μm.

[0068] (4) The sheet is pressed to a thickness of 250μm and a compaction density of 115mg / cm³ using a roller press at a pressure of 25MPa and a temperature of 80℃. 3 .

[0069] Electrolysis of water was performed in 1M KOH solution. The resulting electrode and stainless steel felt were combined as the anode, and a Pt / C electrode (20% Pt on Vulcan XC-72R, Pt loading 1 mg cm⁻¹) was used. -2 PiperION as the cathode TM Using an A40 anion exchange membrane as the electrolyte membrane, the current density reaches 0.77 A / cm³ when the electrolyzer temperature is 50℃ and the voltage is set to 2V. 2 .

[0070] Example 5

[0071] (1) Add 98wt% of nickel-cobalt alloy powder (15-18μm) and 2wt% of PVDF powder binder (18-20μm) to a three-dimensional mixer. The mixing time is 5 hours, the speed is 1000r / min, and the stirring temperature is 80℃ to obtain a uniformly mixed powder mixture.

[0072] (2) The particles were pulverized by an air jet mill with a pulverizing pressure of 0.8 MPa, a particle size of 10 μm, and a temperature of 60 °C.

[0073] (3) Use a twin-screw extruder for high shear rate processing, with a shear rate of 200 rpm and a temperature of 150 ℃, to form a sheet of 1000 μm.

[0074] (4) The sheet is pressed to a thickness of 500μm and a compaction density of 200mg / cm³ using a roller press at a pressure of 50MPa and a temperature of 120℃. 3 .

[0075] Electrolysis of water was performed in 1M KOH solution. The resulting electrode and stainless steel felt were combined as the anode, and a Pt / C electrode (20% Pt on Vulcan XC-72R, Pt loading 1 mg cm⁻¹) was used. -2 PiperION as the cathode TM Using an A40 anion exchange membrane as the electrolyte membrane, the current density reaches 1.05 A / cm³ when the electrolyzer temperature is 50℃ and the voltage is set to 2V. 2 .

Claims

1. A dry electrode for electrolysis of water, characterized by: The electrode tab at least includes a dry tab film prepared by roller pressing of a powder mixture, the powder mixture including 80 wt% - 98 wt% of a powder active material and 2 wt% - 20 wt% of a powder binder; the powder active material being nickel nanopowder, nickel-iron nanopowder, or iron-cobalt-nickel alloy nanopowder.

2. The dry method electrode plate for electrolysis of water according to claim 1, characterized in that: The electrode tab film is further compounded on one side or both sides of a tab substrate by hot pressing; the tab substrate being one or more than two of stainless steel felt, nickel felt, nickel mesh, titanium mesh, nickel foam, aluminum felt, copper foam, and polymer film.

3. The dry method electrode plate for electrolysis of water according to claim 1, characterized in that: The electrode tab at least includes a dry tab film prepared by roller pressing of a powder mixture, the powder mixture including 90 wt% - 98 wt% of a powder active material and 2 wt% - 10 wt% of a powder binder.

4. The dry method electrode plate for electrolysis of water according to claim 1, characterized in that: The powder binder is a mixture of one or more of polyvinylidene fluoride powder (PVDF), polytetrafluoroethylene powder (PTFE), acrylic resin powder, polymethylacrylic resin powder, and styrene butadiene rubber powder, mixed in any ratio.

5. The dry electrode pole piece for electrolyzing water according to any one of claims 1-4, characterized by: The thickness of the electrode is 20 μm - 500 μm; the compacted density is 30.0 mg / cm 3 - 200.0 mg / cm 3 .

6. The dry method electrode plate for electrolysis of water according to claim 5, characterized in that: The thickness of the electrode is 20 μm - 150 μm; the compacted density is 50.0 mg / cm 3 - 120.0 mg / cm 3 .

7. A method of producing the dry electrode sheet for electrolysis of water according to any one of claims 1 to 6, characterized by, The method includes the following steps: (1) Mixing: adding a powder active material with a particle size of 2-100 μm and a powder binder with a particle size of 3-15 μm into a three-dimensional mixer, mixing for 1-5 hours at a rotation speed of 200-1000 r / min, and controlling the temperature at 20℃-80℃ to obtain a uniform powder mixture; (2) Pulverization: pulverizing the mixture obtained in the previous step by an air flow pulverizer, controlling the pulverization pressure at 0.2-0.8 MPa and the temperature at 20℃-60℃, and controlling the particle size distribution of the pulverized powder at 3 μm-10 μm; the working gas of the air flow pulverizer should be an inert gas to prevent oxidation of the powder; (3) Forming: high-shear processing of the pulverized powder mixture by a double-screw extruder or an open mill, controlling the shear rate at 50-200 rpm and the temperature at 50℃-150℃ to cause fiberization of the powder binder, with a fiberization rate of more than 80%, and extruding or rolling to obtain a sheet with a thickness of 200 μm-1000 μm; (4) Rolling: the formed sheet is rolled by a rolling machine, the rolling pressure is controlled at 5 MPa - 50 MPa, the temperature is controlled at 60℃ - 120℃, and the final rolling obtains a pole piece film with a thickness of 20 μm - 500 μm, and the compaction density is 30 mg / cm 3 - 200 mg / cm 3 .

8. The preparation method according to claim 7, characterized in that, including compounding the tab film produced in step (4) on one side or both sides of a tab substrate by a hot pressing compound machine, compounding at a temperature of 100℃-180℃, a pressure of 2 MPa-10 MPa, and for a time of 10-60 minutes to form a multi-layer structure of tab film / substrate or tab film / substrate / tab film.

9. Use of the electrode tab of any one of claims 1-8 as an anode in electrolysis of water.

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