Porous diffusion electrode and preparation method thereof
By controlling the wettability difference through composite hydrophobic materials on perforated thin plates, porous diffusion electrodes were prepared, solving the manufacturing difficulties and stability problems in the existing technology, and achieving efficient and stable electrolytic performance and mass production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-11
- Publication Date
- 2026-04-14
AI Technical Summary
Existing porous diffusion electrodes are difficult to fabricate in terms of large active area and mass production, and the thin coating is prone to affecting the stability of electrolysis performance due to catalyst loss.
By composite hydrophobic materials on perforated thin plates, the wettability difference is controlled so that the catalyst slurry only covers the surface of the thin plate. Combined with hot pressing, a porous diffusion electrode is formed, which avoids the waste of precious metals and improves the controllability of catalyst loading.
This technology enables the efficient fabrication of porous diffusion electrodes in large-area, mass production, improving electrolytic performance stability and production efficiency while saving precious metal usage.
Smart Images
Figure CN121852965A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrolytic cells, and more specifically to a porous diffusion electrode and its preparation method. Background Technology
[0002] The PEM electrolyzer is a novel type of electrolyzer that uses a proton exchange membrane as the electrolyte and is tightly assembled with components such as a cathode catalyst layer, an anode catalyst layer, a porous diffusion layer, a flow field plate, and a current collector plate on both sides. Its structure is very similar to that of a fuel cell. The three-phase interface of the catalyst, feedstock, and electrolyte in the catalyst layer is the site of the water electrolysis reaction. The porous diffusion layer simultaneously serves as a membrane electrode support, a material transport mechanism between feedstock and products, and an electronic conduction mechanism during water electrolysis. Existing perforated metal sheets are a very promising form of diffusion layer, which can significantly reduce the thickness of a single cell and the overall volume of the electrolyzer while maintaining high electrolysis performance. However, because the electronic conductivity between the diffusion layer and the catalyst layer of the perforated sheet is much greater than the lateral electronic conduction within the catalyst layer, most of the electrochemical reactions occur at the three-phase interface in the catalyst layer that is in close contact with the diffusion layer, while the reaction in the catalyst layer at the perforation location of the sheet is slow and even difficult to detect. Although the catalyst layer at the perforation site of the thin plate can be omitted, and porous diffusion electrodes (PTEs) can be prepared by directly sputtering or electroplating the catalyst on the perforated thin plate, this method still has two problems: 1. The method of preparing porous diffusion electrode coatings is not easy to apply to large active areas and mass production; 2. The coating of this method is less than 1 μm, especially for the anode, and the stability of electrolysis performance is easily affected by catalyst loss during long-term operation. Summary of the Invention
[0003] Therefore, in order to overcome the shortcomings of the prior art, the present invention provides a porous diffusion electrode and a method for preparing the same.
[0004] To achieve the above objectives, the present invention provides a method for preparing a porous diffusion electrode, comprising: composite a hydrophobic material onto the lower surface of a perforated thin plate to obtain a composite plate, wherein the hydrophobic material fully fills the pores of the perforated thin plate, and the pores on the perforated thin plate are configured according to electrolysis requirements; polishing the composite plate to make the hydrophobic material and the perforated thin plate smooth; coating a catalyst slurry onto the upper surface of the composite plate, wherein the catalyst slurry has a large wettability difference between the surface of the perforated thin plate and the surface of the hydrophobic material, and under surface tension induction, the catalyst slurry gathers on the surface of the perforated thin plate and detaches from the surface of the hydrophobic material to form a differential coating; after the catalyst slurry on the composite plate dries, controlling the temperature to weaken the bonding force between the hydrophobic material on the composite plate and the perforated thin plate, and removing the hydrophobic material from the composite plate; hot-pressing the perforated thin plate coated with the catalyst slurry at a pressure of 1~5MPa and a temperature of 120~160℃ to fully compact the catalyst layer and induce a glass transition, thereby obtaining a porous diffusion electrode.
[0005] In one embodiment, the perforated sheet has holes that are straight holes in a normal direction, the total area of the holes accounts for 30% to 80% of the total area of the perforated sheet, and the thickness of the perforated sheet is 0.2 to 5 mm.
[0006] In one embodiment, the contact angle of the catalyst slurry on the perforated thin plate is not greater than 55°, and the contact angle of the catalyst slurry on the hydrophobic material is not less than 130°.
[0007] In one embodiment, the viscosity of the catalyst slurry is not greater than 30 mPa·s.
[0008] In one embodiment, the catalyst slurry comprises an anodic catalyst or a cathode catalyst, a resin solution, deionized water, and a low-carbon alcohol, wherein the low-carbon alcohol has no more than 5 carbon atoms.
[0009] In one embodiment, the lower alcohol is any one of ethanol, ethylene glycol, and n-propanol.
[0010] In one embodiment, the controlled temperature weakens the bonding force between the hydrophobic material on the composite plate and the perforated thin plate, and removes the hydrophobic material on the composite plate, including: selecting a separation temperature based on the hydrophobic material and the perforated thin plate; placing the composite plate coated with catalyst slurry in the separation temperature, and using air blowing or water flushing to remove the hydrophobic material on the composite plate.
[0011] A porous diffusion electrode, characterized in that the porous diffusion electrode is prepared by the above method.
[0012] Compared with the prior art, the present invention has the following significant advantages: By controlling the difference in wettability of the slurry on the perforated thin plate and the hydrophobic material, the slurry only covers the surface of the perforated thin plate, while exposing the location of the hydrophobic material. This allows for precise control of the slurry's adhesion position, avoiding the application of slurry at the perforation points of the thin plate and saving precious metals. Different types of catalysts can be flexibly matched, and the catalyst loading is controllable. The process steps are simple and quick, which is conducive to improving the efficiency of mass production. Attached Figure Description
[0013] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0014] Figure 1 This is a flowchart illustrating the preparation method of the porous diffusion electrode in an embodiment of the present invention; Figure 2 This is a flowchart illustrating the preparation method of the porous diffusion electrode in an embodiment of the present invention. Detailed Implementation
[0015] The embodiments of this application will now be described in detail with reference to the accompanying drawings.
[0016] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0017] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.
[0018] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0019] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.
[0020] like Figure 1 As shown, this application provides a method for preparing a porous diffusion electrode, which can be used in an electrolytic cell. The method for preparing the porous diffusion electrode includes the following steps: Step 101: A hydrophobic material is laminated onto the lower surface of a perforated thin plate to obtain a composite plate. The hydrophobic material fully fills the holes in the perforated thin plate, and the holes in the perforated thin plate are set according to the electrolysis requirements.
[0021] like Figure 2 As shown, the perforated thin plate 10 is the main material of the porous diffusion layer in the PEM electrolytic cell, requiring extremely high conductivity and corrosion resistance, high bending strength, and hydrophilicity (water contact angle ≤70°). Due to the different anode and cathode environments, the material of the thin plate varies: for the anode, due to its strong anodic acid corrosion environment, the perforated thin plate is typically made of high-purity titanium alloy or platinum group metals; for the cathode, the perforated thin plate can be made of high-purity titanium alloy, platinum group metals, or graphite. The surface of the thin plate can be appropriately sandblasted to enhance its hydrophilicity. The perforated thin plate 10 has holes 11 provided according to the electrolysis requirements.
[0022] The hydrophobic material 20 is a medium-to-low temperature molten or plastic polymer with a dyne value ≤40mN / m, such as EPTFE, paraffin, etc., or a raw material solution or emulsion for preparing such polymers, such as PTFE emulsion. The hydrophobic material can be solid or liquid. When the hydrophobic material is solid, it has protrusions that correspond to the holes in the perforated sheet, and the height of the protrusions is not less than the thickness of the perforated sheet. When the hydrophobic material is liquid, it must solidify before subsequent steps can be performed, at which point the hydrophobic material fully fills the holes in the sheet. To facilitate subsequent removal, a hydrophobic layer can be formed on the surface of the perforated sheet using the hydrophobic material, which fully fills the holes in the perforated sheet.
[0023] When the hydrophobic material is solid, it can be composited with a perforated sheet using certain processes, such as molding. When the hydrophobic material is liquid, it can be applied or impregnated to fill the holes in the perforated sheet, and then cured by applying appropriate temperature and pressure.
[0024] Step 102: Polish the composite board to make the hydrophobic material and perforated thin plate on the surface of the composite board smooth.
[0025] Polishing the composite board smooths both the hydrophobic material and the perforated sheet on its surface. This fully exposes the wettable surface of the perforated sheet while simultaneously polishing the non-wettable surface of the hydrophobic material to a smooth finish, which facilitates slurry slippage and enables selective coating.
[0026] Step 103: The catalyst slurry is coated on the upper surface of the composite plate. There is a large difference in wettability between the surface of the perforated thin plate and the surface of the hydrophobic material. Under the induction of surface tension, the catalyst slurry gathers on the surface of the perforated thin plate and detaches from the surface of the hydrophobic material to form a differential coating.
[0027] like Figure 2 As shown, the catalyst slurry is coated on the upper surface of the composite plate. Due to the large difference in wettability between the catalyst slurry on the surface of the perforated thin plate and the surface of the hydrophobic material, the catalyst slurry gathers on the surface of the perforated thin plate under the induction of surface tension and detaches from the surface of the hydrophobic material to form a differential coating.
[0028] Step 104: After the catalyst slurry on the composite plate dries, control the temperature to weaken the bonding force between the hydrophobic material on the composite plate and the perforated thin plate, and remove the hydrophobic material from the composite plate.
[0029] The catalyst slurry can be fully dried by controlling drying conditions such as temperature and air volume.
[0030] like Figure 2As shown, by applying a specific temperature, combined with methods such as blowing air or rinsing water, the bonding force between the perforated thin plate and the hydrophobic material is weakened, thus removing the hydrophobic material. When the components of the hydrophobic material are volatile, a vacuum drying process can be added to ensure complete removal of the hydrophobic material.
[0031] In one embodiment, controlling the temperature to weaken the bonding force between the hydrophobic material on the composite plate and the perforated thin plate, and removing the hydrophobic material on the composite plate, includes: selecting a separation temperature based on the hydrophobic material and the perforated thin plate; placing the composite plate coated with catalyst slurry in the separation temperature, and using air blowing or water flushing to remove the hydrophobic material from the composite plate.
[0032] Step 105: The perforated thin plate coated with catalyst slurry is hot-pressed at a pressure of 1~5MPa and a temperature of 120~160℃ to fully compact the catalyst layer and induce a glass transition, thereby obtaining a porous diffusion electrode. The thickness of the catalyst layer ranges from 3~20μm.
[0033] The above method controls the difference in wettability of the slurry on the perforated thin plate and the hydrophobic material, so that the slurry only covers the surface of the perforated thin plate, while exposing the location of the hydrophobic material. It precisely controls the adhesion position of the slurry, avoids applying the slurry at the perforation of the thin plate, and saves precious metals. It can flexibly match different types of catalysts, and the catalyst loading is controllable. The process steps are simple and quick, which is conducive to improving the efficiency of mass production.
[0034] In one embodiment, the hole shape of the perforated sheet is a normal straight hole, the total area of the holes accounts for 30-80% of the total area of the perforated sheet, and the thickness of the perforated sheet is 0.2-5mm.
[0035] In one embodiment, the contact angle of the catalyst slurry on the perforated thin plate is not greater than 55°, and the contact angle of the catalyst slurry on the hydrophobic material is not less than 130°.
[0036] In one embodiment, the catalyst slurry viscosity is no greater than 30 mPa·s.
[0037] In one embodiment, the catalyst slurry comprises an anode catalyst or a cathode catalyst, a resin solution, deionized water, and a low-carbon alcohol, wherein the low-carbon alcohol has no more than 5 carbon atoms. The resin solution is a Nafion resin solution. The anode catalyst may be an iridium oxide catalyst; the cathode catalyst may be a platinum-carbon catalyst.
[0038] In one embodiment, the lower alcohol is any one of ethanol, ethylene glycol, and n-propanol.
[0039] Example 1 The perforated sheet is made of titanium, with circular holes, a diameter of 100 micrometers, hexagonal arrangement of holes, a center-to-center distance of 300 micrometers, and a thickness of 500 micrometers.
[0040] The hydrophobic material uses PTFE emulsion as the raw material. The emulsion is applied to a perforated thin plate and then dried by heating. The application is repeated 3 to 5 times to ensure that the dried PTFE fully fills the pores.
[0041] The titanium plate (composite plate) was calcined at 250~300℃ for 1 hour under nitrogen protection. After cooling, the side with less PTFE was fully polished to expose the perforated thin plate. At the same time, the surface of the PTFE material in the holes was polished to a smooth surface to facilitate slurry slippage and selective coating.
[0042] The catalyst layer slurry is prepared by mixing and dispersing iridium oxide catalyst, Nafion resin solution, deionized water, and n-propanol to obtain a slurry with a certain surface tension. The contact angle of the catalyst layer slurry on the perforated thin plate surface is ≤55°, and the contact angle on the template surface is ≥130°.
[0043] The slurry is applied to the surface of a perforated titanium plate that is composited with a hydrophobic material. Driven by surface tension, the slurry wets the metal surface but does not wet the PTFE template surface.
[0044] Apply a certain temperature to dry the slurry. Apply hot air blowing vertically downwards while carefully peeling off the PTFE sintered substrate on the other side to separate the hydrophobic template from the perforated plate.
[0045] A perforated thin plate coated with catalyst is hot-pressed at a pressure of 1~5MPa and a temperature of 120~160℃ to fully compact the catalyst layer and induce a glass transition, thereby obtaining a porous diffusion electrode for use as the anode of an electrolytic cell.
[0046] Example 2 The perforated sheet is a graphite sheet with circular holes, a diameter of 300 micrometers, hexagonal arrangement of holes, a center-to-center distance of 800 micrometers, and a thickness of 600 micrometers.
[0047] The hydrophobic material is made of foamed EPTFE sheet with a thickness of 2mm. After stacking the perforated graphite plate and EPTFE, they are placed under a press and hot-pressed at 3~5MPa and 120~150℃ for 2~10 minutes to bond the two together. The part of the EPTFE that is bonded to the graphite plate becomes thinner under pressure, while the EPTFE corresponding to the holes in the graphite plate maintains its thickness to a certain extent and fills the holes, forming a composite board.
[0048] The composite board was calcined at 250~300℃ for 1 hour under nitrogen protection. After cooling, the side of the composite board with less EPTFE was fully polished to expose the perforated thin plate and polish the surface of the EPTFE material in the holes to make it smooth, so as to facilitate the slippage of the slurry and selective coating.
[0049] The catalyst layer slurry is prepared by mixing and dispersing platinum-carbon catalyst, Nafion resin solution, deionized water, and n-propanol to obtain a slurry with a certain surface tension. The contact angle of the catalyst layer slurry on the perforated thin plate surface is ≤55°, and the contact angle on the template surface is ≥130°.
[0050] The slurry is applied to the surface of a perforated graphite plate with a hydrophobic composite material. Driven by surface tension, the slurry wets the graphite surface but does not wet the EPTFE template surface.
[0051] Apply a certain temperature to dry the slurry. Apply hot air blowing vertically downwards while carefully peeling off the EPTFE sheet to separate the hydrophobic material from the perforated plate.
[0052] A perforated thin plate coated with catalyst is hot-pressed at a pressure of 1~5MPa and a temperature of 120~160℃ to fully compact the catalyst layer and induce a glass transition, thereby obtaining a porous diffusion electrode for use as the cathode of an electrolytic cell.
[0053] Example 3 The perforated sheet is made of titanium, with circular holes of 200 micrometers in diameter, arranged in a hexagonal pattern, with a center-to-center distance of 500 micrometers and a thickness of 500 micrometers.
[0054] The hydrophobic material is paraffin wax. The paraffin wax is crushed and fully covered on the surface and inside the holes of the perforated thin plate and compacted. It is then hot-pressed at 1~3MPa pressure and 70~100℃ for 2~5 minutes to melt the paraffin wax and fully fill the holes of the titanium plate, thus obtaining a perforated titanium plate with hydrophobic material.
[0055] The side to be coated with the catalyst layer is thoroughly polished to fully expose the perforated thin plate. At the same time, the surface of the paraffin in the holes is also polished to a smooth finish to facilitate slurry slippage and selective coating.
[0056] A catalyst layer slurry is prepared by mixing and dispersing iridium oxide catalyst, Nafion resin solution, deionized water, and n-propanol to obtain a slurry with a certain surface tension. The contact angle of the catalyst layer slurry on the perforated thin plate surface is ≤55°, and the contact angle on the template surface is ≥130°.
[0057] The slurry was applied to the surface of a perforated titanium plate with a hydrophobic composite material. Driven by surface tension, the slurry wetted the metal surface but did not wet the paraffin template surface.
[0058] Apply a certain temperature to dry the slurry. Apply longitudinal hot air to blow through the perforated plate, melting the paraffin and blowing it out of the holes, while simultaneously draining and recovering the paraffin from the back side. Residual floating paraffin on the side without the catalyst layer can be physically wiped away.
[0059] The perforated titanium plate is vacuum dried at a temperature of 80~120℃ to ensure that the paraffin wax is fully evaporated and removed.
[0060] A perforated thin plate coated with catalyst is hot-pressed at a pressure of 1~5MPa and a temperature of 120~160℃ to fully compact the catalyst layer and induce a glass transition, thereby obtaining a porous diffusion electrode for use as the anode of an electrolytic cell.
[0061]
[0062] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A method for preparing a porous diffusion electrode, characterized in that, include: A composite plate is obtained by laminating a hydrophobic material onto the lower surface of a perforated thin plate. The hydrophobic material fully fills the holes in the perforated thin plate, and the holes in the perforated thin plate are set according to the electrolysis requirements. The composite plate is polished to make the hydrophobic material on the surface of the composite plate and the perforated thin plate smooth. The catalyst slurry is coated on the upper surface of the composite plate. The catalyst slurry has a large difference in wettability between the surface of the perforated thin plate and the surface of the hydrophobic material. Under the induction of surface tension, the catalyst slurry gathers on the surface of the perforated thin plate and detaches from the surface of the hydrophobic material to form a differential coating. After the catalyst slurry on the composite plate dries, the temperature is controlled to weaken the bonding force between the hydrophobic material on the composite plate and the perforated thin plate, and the hydrophobic material on the composite plate is removed. The perforated thin plate coated with the catalyst slurry is hot-pressed at a pressure of 1~5MPa and a temperature of 120~160℃ to fully compact the catalyst layer and induce a glass transition, thereby obtaining a porous diffusion electrode.
2. The preparation method according to claim 1, characterized in that, The perforated sheet has holes that are straight and aligned in the normal direction. The total area of the holes accounts for 30% to 80% of the total area of the perforated sheet. The thickness of the perforated sheet is 0.2 to 5 mm.
3. The preparation method according to claim 1, characterized in that, The contact angle of the catalyst slurry on the perforated thin plate is not greater than 55°, and the contact angle of the catalyst slurry on the hydrophobic material is not less than 130°.
4. The preparation method according to claim 1, characterized in that, The viscosity of the catalyst slurry is not greater than 30 mPa·s.
5. The preparation method according to claim 1, characterized in that, The catalyst slurry comprises an anode catalyst or a cathode catalyst, a resin solution, deionized water, and a low-carbon alcohol, wherein the low-carbon alcohol contains no more than 5 carbon atoms.
6. The preparation method according to claim 5, characterized in that, The lower alcohol is any one of ethanol, ethylene glycol, and n-propanol.
7. The preparation method according to claim 1, characterized in that, The controlled temperature weakens the bonding force between the hydrophobic material on the composite plate and the perforated thin plate, and removes the hydrophobic material on the composite plate, including: The separation temperature is determined based on the hydrophobic material and the perforated thin plate. The composite plate coated with catalyst slurry is placed in the separation temperature, and the hydrophobic material on the composite plate is removed by blowing air or rinsing water.
8. A porous diffusion electrode, characterized in that, The porous diffusion electrode is prepared by any one of claims 1 to 7.