Composite and method of making and electrolytic cell structure for electrolytic hydrogen production

Abstract

The application relates to the technical field of hydrogen production, and discloses a composite, a preparation method and an electrolysis cell structure for electrolytic hydrogen production. The composite comprises a support framework and a hydrophilic microporous layer attached to the support framework. The preparation method comprises the following steps: heat spraying mixed powder containing a hydrophilic material and a pore-forming agent to the support framework, and impregnating the pore-forming agent. The support framework comprises an electrode catalyst layer or a substrate. The application can solve the problems that the electrolysis cell has a short service life and hydrogen and oxygen are easily intermixed in the alkaline electrolysis water electrolysis cell.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production technology, specifically to a composite and its preparation method, and an electrolytic chamber structure for hydrogen production by electrolysis. Background Technology

[0002] The main body of an alkaline electrolyzer is assembled from components such as end plates, sealing gaskets, electrode plates, electrode plates, and diaphragms. The electrolyzer comprises dozens or even hundreds of electrolytic cells, which are pressed together by screws and end plates to form a cylindrical or square shape. Each electrolytic cell is divided by two adjacent electrode plates and includes positive and negative bipolar plates, an anode electrode, a diaphragm, sealing gaskets, and a cathode electrode. The diaphragm is mainly made of PPS fabric, which has poor gas barrier properties. Currently, the anode and cathode electrodes of the electrolytic cells are attached to the diaphragm surface. During electrolysis, bubbles are generated on the diaphragm surface, and the pressure and concentration differences across the diaphragm easily cause gas cross-contamination. Simultaneously, the PPS diaphragm has poor hydrophilicity; after bubbles are generated on the electrode surface, a bubble shielding effect exists between the electrode and the diaphragm surface, resulting in significant mass transfer resistance. To improve the hydrophilicity and gas barrier properties of the PPS diaphragm, existing technologies employ coating functional coatings onto PPS or other fabric substrates to improve their hydrophilicity, creating a composite diaphragm with a sandwich-like structure.

[0003] Specifically, current composite membrane surface coating slurries contain inorganic oxides such as zirconium dioxide and polymers. Among them, the inorganic oxide nanoparticles such as zirconium dioxide are the main substances that improve its hydrophilicity. In current technical solutions, the coating layer is directly applied to the surface of fabrics such as PPS. For example, CN 117512691 A provides a method for preparing an alkaline water electrolysis composite membrane, in which the porous polyphenylene sulfide fabric and / or inorganic hydrophilic particle modified polyphenylene sulfide porous fabric are dipped into the porous hydrophilic layer slurry, and then phase inversion is carried out in a coagulation bath to obtain an alkaline water electrolysis composite membrane; CN117107297A provides a composite membrane for alkaline water electrolysis to produce hydrogen with enhanced gas barrier properties and a preparation method thereof; CN117802531A provides a composite membrane, its preparation method and an electrolyzer, the composite membrane including a support mesh and a porous coating attached to the surface of the support mesh, the porous coating including inorganic particles, binder, pore-forming agent and adsorption additive.

[0004] However, the electrolysis chamber using the above-mentioned composite diaphragm has a short lifespan. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of short lifespan of electrolysis chambers and easy cross-contamination of hydrogen and oxygen inside alkaline water electrolysis chambers in the existing technology, and to provide a composite, preparation method and electrolysis chamber structure for hydrogen production by electrolysis.

[0006] To achieve the above objectives, the present invention provides a method for preparing a composite having a hydrophilic microporous layer, the composite comprising a support framework and a hydrophilic microporous layer attached to the support framework, the preparation method comprising: thermally spraying a mixed powder containing a hydrophilic material and a pore-forming agent onto the support framework, thereby impregnating and creating pores; wherein the support framework comprises an electrode catalyst layer or a substrate.

[0007] A second aspect of the present invention provides a composite having a hydrophilic microporous layer, the composite being prepared using the preparation method described in the present invention.

[0008] A third aspect of the present invention provides an electrolytic chamber structure for electrolytic hydrogen production, wherein the electrolytic chamber structure adopts the composite with a hydrophilic microporous layer described in the present invention, wherein the hydrophilic microporous layer of the composite is located between the electrode catalyst layer and the membrane.

[0009] Through the above technical solution, the present invention attaches a hydrophilic microporous layer to the electrode catalyst layer or substrate by thermal spraying. Compared with the microporous layer preparation process of composite membranes, it can improve the bonding strength, prevent detachment, and is simple and easy to implement. It can solve the problem of easy cross-contamination of hydrogen and oxygen inside the alkaline water electrolysis chamber.

[0010] Other advantages of the present invention will be described in detail in the specific embodiments. Attached Figure Description

[0011] Figure 1 This is a schematic diagram showing the position of the hydrophilic microporous layer in the electrolytic chamber structure for electrolytic hydrogen production according to one embodiment of the present invention.

[0012] Figure 2 This is a schematic diagram showing the position of the hydrophilic microporous layer in the electrolytic chamber structure for electrolytic hydrogen production, according to another embodiment of the present invention.

[0013] Figure 3 This is a schematic diagram showing the position of the hydrophilic microporous layer in the electrolytic chamber structure for hydrogen production according to another embodiment of the present invention.

[0014] Explanation of reference numerals in the attached figures

[0015] 1. Anode catalyst layer; 2. Anode hydrophilic microporous layer; 3. Separator; 4. Cathode hydrophilic microporous layer; 5. Cathode catalyst layer. Detailed Implementation

[0016] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the invention. Unless otherwise defined, the technical terms used in the following specific embodiments have the same meaning as commonly understood by those skilled in the art to which this invention pertains.

[0017] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0018] Referring to the background art of this invention, in the prior art, to improve the hydrophilicity and gas barrier properties of PPS membranes, a functional coating is applied to a PPS or other fabric substrate to improve its hydrophilicity, forming a composite membrane with a sandwich-like structure. However, electrolytic cells using this type of composite membrane suffer from short lifespan. The inventors have discovered that current composite membrane solutions suffer from poor bonding between different materials, leading to easy coating detachment and membrane failure, thus causing the short lifespan of the electrolytic cells.

[0019] Therefore, this invention discloses a method for preparing a composite with a hydrophilic microporous layer. The composite includes a supporting framework and a hydrophilic microporous layer attached to the supporting framework. The preparation method includes: thermally spraying a mixed powder containing hydrophilic materials and pore-forming agents onto the supporting framework to form a coating; impregnating and creating pores to attach the hydrophilic microporous layer to the supporting framework; wherein, the supporting framework includes an electrode catalyst layer or a substrate. When the supporting framework is an electrode catalyst layer, since the electrode catalyst is part of the electrode as a whole, the hydrophilic microporous layer is equivalent to being attached to the electrode and forming an integral part with the electrode, and the composite is the electrode. When a substrate is selected, the hydrophilic microporous layer is attached to the substrate to form a composite. When forming an electrolysis chamber, the composite is independently located between the electrode and the diaphragm in the prior art. When the electrolysis chamber is pressed together by a screw and an end plate to form a cylindrical or cubic shape, the composite can be fixed by extrusion.

[0020] This invention uses thermal spraying to form a hydrophilic microporous layer on the electrode catalyst layer or substrate. Compared with the composite membrane solution in the prior art, it can improve the bonding strength, is not easy to fall off, and the process is simple and easy to implement, which can solve the problem of short life of electrolysis chamber.

[0021] In some embodiments, the thermal spraying operating conditions include: the carrier gas can be a mixture of argon and hydrogen, the carrier gas velocity is 30-150 L / min, and the particle velocity is 200-600 m / s.

[0022] It is understood that any thermal spraying method that can achieve the aforementioned thermal spraying operation conditions can be used in this invention. The following is an illustrative description, but it does not limit the scope of this invention. In some embodiments, the thermal spraying method can be at least one of the prior art, such as plasma spraying, flame spraying, supersonic flame spraying, or arc spraying.

[0023] In some embodiments, the mixed powder is composed of a hydrophilic material and a pore-forming agent, wherein the hydrophilic material comprises 60% to 90% and the pore-forming agent comprises 10% to 40% by mass percentage. The present invention does not have special requirements for the mixing method of the hydrophilic material and the pore-forming agent, and conventional powder mixing methods can be used, which will not be elaborated further in the present invention.

[0024] In some embodiments, the particle size of the hydrophilic material powder can be 5 to 150 μm.

[0025] In some embodiments, the particle size of the hydrophilic material powder can be 10-80 μm.

[0026] In some embodiments, the particle size of the pore-forming agent is 0.5–100 μm.

[0027] In some embodiments, the particle size of the pore-forming agent is 0.5–10 μm.

[0028] In some embodiments, the hydrophilic material includes at least one of zirconium oxide, yttrium oxide, cerium oxide, magnesium oxide, and titanium oxide.

[0029] In some embodiments, the pore-forming agent comprises an elemental metal, such as aluminum powder and / or zinc powder.

[0030] In some embodiments, the impregnation solution for impregnating the pore-forming process includes an aqueous solution of sodium hydroxide and / or an aqueous solution of potassium hydroxide.

[0031] In some embodiments, the impregnation solution for creating the pores is an aqueous solution of sodium hydroxide.

[0032] In some embodiments, the impregnation solution for impregnating the pores is a 3-30 wt% aqueous solution of sodium hydroxide.

[0033] In some embodiments, the immersion conditions include: immersion time of 10 to 100 minutes, immersion temperature of 50 to 90°C, and complete immersion in the immersion solution.

[0034] In some embodiments, the substrate is a mesh with a thickness of 0.05-0.5 mm and a mesh size of 50-200.

[0035] In this invention, the range of substrates is quite wide. The following is an illustrative description, but it does not limit the scope of the invention. In some embodiments, the substrate is a metal mesh, such as at least one of nickel wire woven mesh, stainless steel woven mesh, nickel stamped mesh, or stainless steel stamped mesh.

[0036] Based on the foregoing disclosure, this invention discloses a composite with a hydrophilic microporous layer, which is prepared using the preparation method of this invention.

[0037] In some embodiments, after impregnation and pore formation, the hydrophilic microporous layer attached to the support skeleton has a pore size range of 10–800 nm, a porosity range of 40%–80%, and a thickness of 0.05–0.5 mm.

[0038] Referring to the background technology, in existing technologies, the anode and cathode electrodes of the electrolysis chamber are attached to the surface of the diaphragm. During electrolysis, bubbles are generated on the diaphragm surface, and the existence of pressure and concentration differences across the diaphragm easily leads to gas cross-contamination. To solve the cross-contamination problem, existing technologies use composite diaphragms to improve hydrophilicity and gas barrier properties. However, the manufacturing process of composite diaphragms is complex, costly, and difficult to control in terms of quality. Furthermore, the coating layer is prone to peeling off, resulting in a short lifespan for the electrolysis chamber.

[0039] Therefore, based on the aforementioned disclosure, this invention discloses an electrolytic chamber structure for hydrogen production by electrolysis. The electrolytic chamber structure adopts the composite with a hydrophilic microporous layer of this invention. When the composite is installed in the electrolytic chamber structure, the hydrophilic microporous layer of the composite is located between the electrode catalyst layer and the membrane 3. The hydrophilic microporous layer has a capillary effect, which can realize liquid storage and avoid the formation of gas cavities.

[0040] This invention can attach a hydrophilic microporous layer to the catalyst layer of an existing electrode by thermal spraying, or install the composite material of the substrate used in this invention between the electrode and the diaphragm in an existing electrolysis chamber structure using a common diaphragm. In this way, it can avoid the direct contact of bubbles generated on the electrode surface with the diaphragm, reduce the risk of gas cross-contamination, improve the airtightness of the chamber during alkaline water electrolysis to produce hydrogen, solve the problem of easy cross-contamination of hydrogen and oxygen inside the electrolysis chamber, and avoid the problem of short life of the electrolysis chamber.

[0041] Specifically, the electrolysis chamber structure for hydrogen production includes an anode with an anode catalyst layer 1, a diaphragm 3, and a cathode with a cathode catalyst layer 5 arranged sequentially. Because a pressure difference and concentration difference are generated across the diaphragm, gas cross-contamination can easily occur. Therefore, a hydrophilic microporous layer of the present invention can be provided on either the anode or cathode side. In some embodiments, such as... Figure 2 As shown, a hydrophilic microporous layer (named anode hydrophilic microporous layer 2) is provided between the diaphragm 3 and the anode catalyst layer 1 of the anode; or as shown... Figure 3 As shown, a hydrophilic microporous layer (named cathode hydrophilic microporous layer 4) is provided between the diaphragm 3 and the cathode catalyst layer 5 of the cathode electrode. Alternatively, the hydrophilic microporous layer of the present invention can be provided on both the anode and cathode sides, specifically, as shown... Figure 1 As shown, an anode hydrophilic microporous layer 2 is provided between the diaphragm and the anode catalyst layer 1 of the anode, and a cathode hydrophilic microporous layer 4 is provided between the diaphragm and the cathode catalyst layer 5 of the cathode.

[0042] In the same electrolysis chamber, the supporting frameworks to which the anode hydrophilic microporous layer 2 and the cathode hydrophilic microporous layer 4 are attached may be the same or different; this invention has no special requirements in this regard. It should be noted that the anode hydrophilic microporous layer 2 and the cathode hydrophilic microporous layer 4 are identical, but are distinguished by their different positions within the electrolysis chamber structure.

[0043] In this invention, regardless of whether the supporting skeleton is made of a substrate or a catalyst layer, there is no need to change the existing connection method. That is, the electrolysis chambers are pressed together by screws and end plates to form a cylindrical or square shape. When the supporting skeleton of the composite is a substrate, the composite is fixed by the extrusion of the electrode and the diaphragm 3. When the supporting skeleton of the composite is a catalyst layer, the hydrophilic microporous layer is integrated with the electrode.

[0044] In this invention, the selection range of the diaphragm 3 is relatively wide. The following is an illustrative description, but it does not limit the scope of the invention. In some embodiments, the diaphragm 3 includes at least one of PPS woven mesh, hydrophilic PTFE mesh, PPS fiber felt and polysulfone woven mesh.

[0045] The advantages of the present invention are illustrated below through examples, but the present invention is not limited thereto. Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art; the experimental materials used are commercially available unless otherwise specified. Unless otherwise specified, the reagent dosages are those used in routine experimental operations; the ultrasonic treatment power in the following examples and comparative examples is 500W.

[0046] Example 1

[0047] 800g of zirconia powder (50µm particle size) and 200g of aluminum powder (1µm particle size) were mixed uniformly by mechanical mixing. Plasma spraying was then used, employing a mixture of argon and hydrogen as the carrier gas at a velocity of 80L / min and a particle velocity of 400m / s. The mixed powder was sprayed onto the substrate surface. The substrate was a 0.2mm thick, 100-mesh nickel wire mesh. After spraying, the composite was completely immersed in a 30wt% potassium hydroxide aqueous solution at 80℃ for 1 hour, followed by cleaning and drying to obtain a composite with a hydrophilic microporous layer. The hydrophilic microporous layer of the obtained composite had a pore size of 100nm, a porosity of 60%, a thickness of 0.21mm, and a bubble point pressure of 1.5bar. After ultrasonic treatment for 30 minutes, the composite exhibited a weight loss of 0.5%. Figure 1 As shown, the aforementioned composite is disposed on both sides of the PPS woven membrane, with the hydrophilic microporous layer facing the surface of the PPS woven membrane, and anode and cathode electrodes and plates disposed on the outer side, forming an electrolysis chamber.

[0048] Example 2

[0049] Unlike Example 1, 650g of titanium dioxide powder (50µm particle size) and 350g of zinc powder (5µm particle size) were used. They were mixed uniformly by mechanical mixing. Plasma spraying was employed, using a mixture of argon and hydrogen as the carrier gas at a velocity of 70L / min and a particle velocity of 350m / s. The mixed powder was sprayed onto the surface of a substrate. The substrate was a 0.15mm thick stainless steel woven mesh with a mesh size of 150 mesh. After spraying, the composite was completely immersed in a 20wt% sodium hydroxide aqueous solution at 80°C for 1 hour, then cleaned and dried to obtain a composite with a hydrophilic microporous layer. The resulting hydrophilic microporous layer had a pore size of 230nm, a porosity of 50%, a thickness of 0.16mm, a bubble point pressure of 1.1 bar, and a weight loss of 0.64% after ultrasonic treatment for 30 minutes. Figure 1 As shown, composites are set on both sides of the hydrophilic PTFE mesh, with the hydrophilic microporous layer facing the surface of the hydrophilic PTFE mesh. Anode and cathode electrodes and plates are set on the outer side to form an electrolysis chamber. The rest is the same as in Example 1.

[0050] Example 3

[0051] Unlike Example 1, as Figure 2 As shown, the substrate is an anode, and the mixed powder is thermally sprayed onto the catalyst layer of the anode. The cathode and the PPS woven membrane do not have a hydrophilic microporous layer. The rest is the same as in Example 1.

[0052] Results: The bubble point pressure of the obtained complex was 1.0 bar. After ultrasonic treatment for 30 min, the weight loss rate of the complex was 0.52%.

[0053] Example 4

[0054] Unlike Example 1, 500g of zirconium oxide powder and 500g of aluminum powder were taken respectively, and the rest were the same as in Example 1.

[0055] Results: The bubble point pressure of the obtained composite was 0.7 bar, and the weight loss rate of the composite was 0.7% after ultrasonic treatment for 30 min.

[0056] Example 5

[0057] Unlike Example 1, the zirconium oxide powder has a particle size of 120 μm, but otherwise it is the same as in Example 1.

[0058] Results: The bubble point pressure of the obtained complex was 0.8 bar, and the weight loss rate of the complex was 0.69% after ultrasonic treatment for 30 min.

[0059] Example 6

[0060] Unlike Example 1, the aluminum powder has a particle size of 20 μm, but otherwise it is the same as Example 1.

[0061] Results: The bubble point pressure of the obtained complex was 0.83 bar, and the weight loss rate of the complex was 0.66% after ultrasonic treatment for 30 min.

[0062] Comparative Example 1

[0063] The electrolysis chamber in this comparative example uses the same anode and cathode electrodes and plates as in Example 1. The difference is that the hydrophilic microporous layer of this invention is not provided; instead, the composite membrane disclosed in CN117802531A is used.

[0064] Results: The bubble point pressure of the obtained complex was 1.5 bar, and the weight loss rate of the complex was 1.1% after ultrasonic treatment for 30 min.

[0065] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a composite with a hydrophilic microporous layer, characterized in that, The composite includes a support framework and a hydrophilic microporous layer attached to the support framework. The preparation method includes: thermally spraying a mixed powder containing hydrophilic material and pore-forming agent onto the support framework and impregnating it to create pores. The supporting framework includes an electrode catalyst layer or a substrate.

2. The preparation method according to claim 1, characterized in that, The thermal spraying method includes at least one of plasma spraying, flame spraying, supersonic flame spraying, or arc spraying.

3. The preparation method according to claim 1, characterized in that, The mixed powder is composed of hydrophilic materials and pore-forming agents.

4. The preparation method according to claim 3, characterized in that, The mixed powder contains, by mass percentage, 60%–90% hydrophilic material and 10%–40% pore-forming agent.

5. The preparation method according to claim 3 or 4, characterized in that, The particle size of the hydrophilic material is 5–150 μm.

6. The preparation method according to claim 5, characterized in that, The particle size of the hydrophilic material is 10–80 μm.

7. The preparation method according to claim 3 or 4, characterized in that, The particle size of the pore-forming agent is 0.5–100 μm.

8. The preparation method according to claim 7, characterized in that, The particle size of the pore-forming agent is 0.5–10 μm.

9. The preparation method according to claim 3 or 4, characterized in that, The hydrophilic material includes at least one of zirconium oxide, yttrium oxide, cerium oxide, magnesium oxide, and titanium oxide.

10. The preparation method according to claim 3 or 4, characterized in that, The pore-forming agent includes an elemental metal.

11. The preparation method according to claim 10, characterized in that, The pore-forming agent includes aluminum powder and / or zinc powder.

12. The preparation method according to claim 1, characterized in that, The impregnation solution for pore formation includes aqueous solutions of sodium hydroxide and / or potassium hydroxide.

13. The preparation method according to claim 12, characterized in that, The impregnation solution used for creating pores includes an aqueous solution of sodium hydroxide.

14. The preparation method according to claim 13, characterized in that, The impregnation solution for creating pores includes a 3-30 wt% aqueous solution of sodium hydroxide.

15. The preparation method according to claim 1, characterized in that, The immersion conditions include: immersion time of 10 to 100 minutes, immersion temperature of 50 to 90°C, and complete immersion in the immersion solution.

16. The preparation method according to claim 1, characterized in that, The substrate is a mesh with a thickness of 0.05-0.5 mm and a mesh size of 50-200.

17. The preparation method according to claim 1 or 16, characterized in that, The substrate is a metal mesh.

18. The preparation method according to claim 1 or 16, characterized in that, The substrate is at least one of nickel wire woven mesh, stainless steel woven mesh, nickel stamped mesh, or stainless steel stamped mesh.

19. A composite having a hydrophilic microporous layer, characterized in that, The composite is prepared using the preparation method described in any one of claims 1-18.

20. The composite according to claim 19, characterized in that, After impregnation and pore creation, the hydrophilic microporous layer attached to the support skeleton has a pore size range of 10-800 nm, a porosity range of 40%-80%, and a thickness of 0.05-0.5 mm.

21. An electrolytic chamber structure for hydrogen production by electrolysis, characterized in that, The electrolysis chamber structure adopts the composite with a hydrophilic microporous layer as described in claim 19 or 20, wherein the hydrophilic microporous layer of the composite is located between the electrode catalyst layer and the membrane (3).

22. The electrolysis chamber structure according to claim 21, characterized in that, The hydrophilic microporous layer is provided between the diaphragm (3) and the anode catalyst layer (1) of the anode.

23. The electrolysis chamber structure according to claim 21 or 22, characterized in that, The hydrophilic microporous layer is provided between the diaphragm (3) and the cathode catalyst layer (5) of the cathode electrode.

24. The electrolysis chamber structure according to claim 21, characterized in that, When the supporting skeleton of the composite is a substrate, the composite is fixed by the extrusion of the electrode and the diaphragm (3).

25. The electrolysis chamber structure according to claim 21, characterized in that, The diaphragm (3) includes at least one of PPS woven mesh, hydrophilic PTEF mesh, PPS fiber felt and polysulfone woven mesh.

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