A composite diaphragm for hydrogen production by electrolyzing water and a preparation method thereof

Abstract

The present invention relates to a composite diaphragm for electrolytic water hydrogen production and a preparation method thereof. The composite diaphragm includes a reticulated woven fabric substrate and a composite film layer attached to the reticulated woven fabric substrate. The composite film layer contains inorganic ceramic fibers and a main film-forming liquid material. Among them, the inorganic ceramic fibers are selected from fibers of one or more oxides of Ti, Zr, Si, and Al. The preparation method includes: (1) mixing a ceramic precursor and an auxiliary agent to obtain a spinning solution, then spinning the spinning solution, and calcining the fibers obtained by spinning to obtain inorganic ceramic fibers; (2) dispersing the inorganic ceramic fibers in the film-forming liquid, and then performing film scraping and drying. In the composite diaphragm for electrolytic water hydrogen production of the present invention, a composite film layer containing inorganic ceramic fibers and a main film-forming liquid material is added on the surface of the reticulated woven fabric substrate. The composite film layer is an inorganic-organic composite layer, which significantly improves the stability and hydrophilicity of the composite diaphragm, and increases the membrane current and reduces the membrane resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of diaphragms, and particularly to a composite diaphragm for hydrogen production by electrolyzing water and a preparation method thereof. Background Art

[0002] Hydrogen energy is an efficient, clean and environmentally friendly energy source and an important support for achieving carbon neutrality. At present, among commercial hydrogen production technologies, the electrolytic water hydrogen production technology is mature and widely used. Alkaline water electrolysis is a key technology for large-scale hydrogen production and one of the most mature hydrogen production technologies. The diaphragm is the core component of alkaline water electrolysis. On the one hand, it blocks the mixing of hydrogen and oxygen to ensure the purity of hydrogen. On the other hand, it allows ions in the solution to pass through, ensures the continuous progress of the electrolysis process, and reduces the diaphragm resistance as much as possible to reduce energy consumption.

[0003] Asbestos was the earliest material used for electrolytic water diaphragms. However, asbestos has swelling properties. The swelling of the diaphragm in alkaline water electrolytes reduces the overall tensile strength of the diaphragm, making the diaphragm vulnerable to the impact of electrolytes and gases and being damaged, so it has gradually been phased out. At present, in the existing technology, mainly modified polyphenylene sulfide diaphragms, etc. are used as diaphragms for hydrogen production by electrolyzing water. However, such diaphragms have large pores and gases are easily penetrated (high air permeability), resulting in a decrease in the purity of the produced hydrogen. Existing electrolytic water hydrogen production diaphragms also have problems such as poor hydrophilicity and high energy consumption. In view of the above problems, there is an urgent need to develop new alkaline electrolytic water hydrogen production diaphragms. Summary of the Invention

[0004] The present invention provides a composite diaphragm for hydrogen production by electrolyzing water and a preparation method thereof to reduce the gas permeability and improve the hydrophilicity of the diaphragm, thereby reducing the membrane resistance, reducing energy consumption, and increasing the membrane current.

[0005] In a first aspect, the present invention relates to a composite diaphragm for hydrogen production by electrolyzing water. The composite diaphragm includes a reticulated woven substrate and a composite film layer attached to the reticulated woven substrate. The composite film layer contains inorganic ceramic fibers and a main film-forming liquid material. Among them, the inorganic ceramic fibers are selected from fibers of one or more oxides of Ti, Zr, Si, and Al.

[0006] Optionally, the reticulated woven substrate is selected from one or more combinations of polyphenylene sulfide woven fabrics, polysulfone woven fabrics, and polyether ether ketone woven fabrics; the mesh size of the reticulated woven substrate is 1-5000 μm, and the thickness is 50-1000 μm; the main film-forming liquid material is selected from one or more combinations of polyphenylene sulfide, polysulfone, and polyether ether ketone.

[0007] Optionally, the thickness of the composite diaphragm is 50-1500 μm, and the diameter of the inorganic ceramic fibers is 5-500 nm and the length is 0.1-1 μm.

[0008] Second aspect, the present invention relates to a method for preparing the composite separator, and the preparation method includes the following steps: (1) mixing a ceramic precursor and an auxiliary agent to obtain a spinning solution, then spinning the spinning solution, and calcining the fibers obtained by spinning to obtain inorganic ceramic fibers; (2) grinding the inorganic ceramic fibers obtained from step (1) and dispersing them in a membrane-forming solution, coating the membrane-forming solution dispersed with inorganic ceramic fibers on the surface of a reticulated woven fabric substrate, and then performing film scraping, air drying and phase inversion to obtain a composite separator.

[0009] Optionally, in step (1), the ceramic precursor is selected from esters, inorganic salts or alcoholates of one or more of Ti, Zr, Si and Al as spinning precursors; the auxiliary agent includes a solvent, a complexing agent, a templating agent and a fiber forming agent; the calcination temperature is 300 to 800 °C and the time is 2 to 10 h.

[0010] Optionally, the ceramic precursor is selected from a combination of one or more of tetraethyl titanate, tetrabutyl titanate, titanium tetrachloride, zirconium oxychloride, zirconium propoxide, aluminum isopropoxide and tetraethyl orthosilicate.

[0011] Optionally, the solvent is selected from a combination of one or more of water, ethanol, propanol, isopropanol, n-butanol and N,N-dimethylformamide; the complexing agent is selected from a combination of one or more of acetylacetone, citric acid, diethanolamine and triethanolamine; the fiber forming agent is selected from a combination of one or more of polyvinylpyrrolidone, polyvinyl alcohol and carboxymethyl cellulose; the templating agent is selected from a combination of one or more of triblock copolymers, sodium dodecylsulfonate and polyethylene glycol; the triblock copolymer is selected from a combination of one or more of F127, P123 and L64.

[0012] Optionally, the molar ratio of the ceramic precursor to the solvent, the complexing agent, the templating agent and the fiber forming agent is 1:(4 to 100):(0.01 to 0.1):(0.01 to 0.5):(0.01 to 0.5).

[0013] Optionally, in step (2), the diameter of the inorganic ceramic fibers after grinding is 5 to 500 nm and the length is 0.1 to 1 μm.

[0014] Optionally, in step (2), the dispersing the inorganic ceramic fibers obtained from step (1) in the membrane-forming solution after grinding includes: dispersing the ground inorganic ceramic fibers into the membrane-forming solution and mixing by ultrasonic.

[0015] Optionally, in step (2): the mesh woven substrate is selected from one or more combinations of polyphenylene sulfide woven fabric, polysulfone woven fabric, and polyether ether ketone woven fabric; the film-forming solution includes a film-forming solution main material and a film-forming solution solvent; the film-forming solution main material is selected from one or more combinations of polyphenylene sulfide, polysulfone, and polyether ether ketone; the film-forming solution solvent is selected from one or more combinations of benzophenone, diphenyl ether, cyclohexyl pyrrolidone, polyvinyl pyrrolidone, N-methyl pyrrolidone, and chloroform; the mass percentage of the film-forming solution solvent in the film-forming solution is 5-50%; the mass percentage of the inorganic ceramic fibers in the film-forming solution dispersed with inorganic ceramic fibers is 1-10%.

[0016] Beneficial effects:

[0017] In the composite diaphragm for electrolytic water hydrogen production of the present invention, a composite film layer containing inorganic ceramic fibers and a film-forming solution main material is added on the surface of the mesh woven substrate. This composite film layer is an inorganic-organic composite layer, which significantly improves the stability and hydrophilicity of the composite diaphragm, and increases the membrane current and reduces the membrane resistance. Description of the drawings

[0018] Figure 1 is the SEM photograph of the inorganic ceramic nanofibers after calcination in Example 1 of the present invention;

[0019] Figure 2 is the hydrophilic contact angle test photograph of the inorganic ceramic nanofiber-organic composite diaphragm prepared in Example 4 of the present invention;

[0020] Figure 3 is the hydrophilic contact angle test photograph of the polysulfone porous membrane prepared in Comparative Example 1. Specific embodiments

[0021] The present application will be further described in detail below with reference to the drawings and examples. Through these descriptions, the features and advantages of the present application will become more clearly defined.

[0022] The special word "exemplary" here means "serving as an example, embodiment, or illustration". Any embodiment described as "exemplary" here does not have to be construed as superior or better than other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings do not have to be drawn to scale unless otherwise specified.

[0023] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0024] In a first aspect, the present invention relates to a composite diaphragm for hydrogen production by electrolyzing water. The composite diaphragm includes a reticular woven fabric substrate and a composite film layer attached to the reticular woven fabric substrate. The composite film layer contains inorganic ceramic fibers and a main film-forming liquid material. Among them, the inorganic ceramic fibers are selected from fibers of one or more oxides of Ti, Zr, Si, and Al.

[0025] It should be noted that the composite diaphragm of the present invention is an inorganic ceramic fiber-organic composite diaphragm. The reticular woven fabric substrate can be a woven fabric with a reticular structure. The composite film layer is an organic-inorganic composite film layer, and the composite film layer is in close contact with and connected to the surface of the reticular woven fabric substrate. The inorganic ceramic fibers are preferably nanofibers of the elemental oxides.

[0026] It should be noted that in the composite diaphragm of the present invention, a composite film layer is attached to the surface of the reticular woven fabric substrate. The material of the composite film layer contains inorganic ceramic fibers and a main film-forming liquid material. First, attaching inorganic ceramic fibers to the surface of the reticular woven fabric substrate can improve the hydrophilicity of the composite diaphragm and thus reduce energy consumption. At the same time, the composite film layer containing inorganic ceramic fibers and the main film-forming liquid material can well prevent gas from passing through, and thus can improve the purity of the produced hydrogen.

[0027] According to an embodiment of the first aspect of the present invention, the reticular woven fabric substrate is selected from one or more combinations of polyphenylene sulfide woven fabric, polysulfone woven fabric, and polyether ether ketone woven fabric. The mesh size of the reticular woven fabric substrate is 1 - 5000 μm, and the thickness is 50 - 1000 μm. The main film-forming liquid material is selected from one or more combinations of polyphenylene sulfide, polysulfone, and polyether ether ketone.

[0028] It should be noted that in the composite diaphragm of the present invention, in the composite film layer, the main film-forming liquid materials such as polyphenylene sulfide, polysulfone, and polyether ether ketone are intertwined with the inorganic ceramic fibers. Thus, the composite film layer can enable ions to pass through well while also reducing the gas passing rate.

[0029] According to an embodiment of the first aspect of the present invention, the thickness of the composite diaphragm is 50 - 1500 μm, and the diameter of the inorganic ceramic fibers is 5 - 500 nm, and the length is 0.1 - 1 μm.

[0030] It should be noted that in the composite diaphragm of the present invention, by comprehensively controlling the thickness of the composite diaphragm, the diameter and length of the inorganic ceramic fibers, the hydrophilicity of the composite diaphragm can be better improved while the air permeability can be better reduced.

[0031] Second aspect, the present invention relates to a method for preparing the composite separator, and the preparation method includes the following steps: (1) Mix a ceramic precursor and an auxiliary agent to obtain a spinning solution, then spin the spinning solution, and calcine the fibers obtained by spinning to obtain inorganic ceramic fibers; (2) Grind the inorganic ceramic fibers obtained from step (1) and disperse them in a membrane-forming solution, coat the membrane-forming solution dispersed with inorganic ceramic fibers on the surface of a reticulated woven substrate, then perform film scraping, drying, and phase inversion to obtain a composite separator.

[0032] It should be noted that in the preparation method of the present invention, in step (1), spinning the spinning solution first obtains fibers, and then the organic matter in the fibers obtained by spinning can be removed by calcination, and then inorganic ceramic fibers in the form of oxides are obtained, that is, through step (1), Ti, Zr, Si, and / or Al contained in the ceramic precursor are converted into oxide fibers. Through step (2), an inorganic ceramic fiber and the main material of the membrane-forming solution form a composite film layer on the surface of the reticulated woven substrate.

[0033] It should be noted that in step (1), the spinning solution can be spun into ceramic nanofibers through an electrospinning device. Solvents are removed by drying or air-drying in step (2) to obtain a composite separator, and the obtained composite separator can be well applied to alkaline electrolytic water hydrogen production.

[0034] It should be noted that the inorganic ceramic fibers obtained from step (1) can be ceramic nanofibers.

[0035] According to an embodiment of the second aspect of the present invention, in step (1), the ceramic precursor is selected from ester-based, inorganic salt-based, or alcoholate-based spinning precursors of one or more of Ti, Zr, Si, and Al; the auxiliary agent includes a solvent, a complexing agent, a templating agent, and a fiber-forming agent; the temperature of the calcination is 300-800 °C, and the time is 2-10 h.

[0036] It should be noted that the calcination described in step (1) can be carried out in a muffle furnace. Through the calcination, the organic matter is removed to obtain oxide fibers, such as titanium dioxide fibers, silicon dioxide fibers, or aluminum oxide fibers, etc. Such inorganic fibers are loaded on the surface of the reticulated woven substrate, which significantly improves the hydrophilic property of the composite separator. Especially in the preparation method of the present invention, inorganic oxide fibers, i.e., inorganic ceramic fibers, are first obtained through spinning and calcination, and then the inorganic ceramic fibers are dispersed in the film-forming solution. The film-forming solution containing the dispersed inorganic ceramic fibers forms a coating on the surface of the reticulated woven substrate by coating, or the reticulated woven substrate is immersed in the film-forming solution containing the dispersed inorganic ceramic fibers to form a coating on the surface of the reticulated woven substrate, and then through scraping, drying (air drying), and phase inversion, a composite film layer is formed on the surface of the reticulated woven substrate by the inorganic ceramic fibers and the main material of the film-forming solution. In this way, the inorganic oxide fibers and the main material of the film-forming solution form a composite film layer on the surface of the reticulated woven substrate, which can greatly improve the hydrophilicity and greatly reduce the air permeability, and significantly improve the comprehensive performance of the separator.

[0037] According to an embodiment of the second aspect of the present invention, the ceramic precursor is selected from one or a combination of more than one of tetraethyl titanate, tetrabutyl titanate, titanium tetrachloride, zirconium oxychloride, zirconium propoxide, aluminum isopropoxide, and tetraethyl orthosilicate.

[0038] It should be noted that in the preparation method of the present invention, the ceramic precursor is not limited to the several substances listed above, and any ceramic precursor that can obtain inorganic oxide fibers through spinning and roasting can be applicable to the present invention.

[0039] According to an embodiment of the second aspect of the present invention, the solvent is selected from one or a combination of more than one of water, ethanol, propanol, isopropanol, n-butanol, and N,N-dimethylformamide; the complexing agent is selected from one or a combination of more than one of acetylacetone, citric acid, diethanolamine, and triethanolamine; the fiber forming agent is selected from one or a combination of more than one of polyvinylpyrrolidone, polyvinyl alcohol, and carboxymethyl cellulose; the template agent is selected from one or a combination of more than one of triblock copolymers, sodium dodecylsulfonate, and polyethylene glycol; the triblock copolymer is selected from one or a combination of more than one of F127, P123, and L64.

[0040] It should be noted that in the preparation method of the present invention, the types of additives contained in the spinning solution and the types of substances contained in each additive are not limited to the above definitions, and any additive that is beneficial to spinning the ceramic precursor into fibers can be added to the spinning solution.

[0041] It should be noted that polyvinylpyrrolidone can be used as a 10-20 wt% polyvinylpyrrolidone solution, and the solution can be an aqueous solution, an alcohol solution, etc.

[0042] According to an embodiment of the second aspect of the present invention, the molar ratio of the ceramic precursor to the solvent, the complexing agent, the templating agent, and the fiber forming agent is 1:(4-100):(0.01-0.1):(0.01-0.5):(0.01-0.5).

[0043] It should be noted that the spinning solution obtained by compounding within the above molar ratio range has good spinning stability, can be well spun to obtain fibers, and oxide fibers are obtained through the calcination.

[0044] According to an embodiment of the second aspect of the present invention, in step (2), the diameter of the inorganic ceramic fiber after grinding is 5-500 nm, and the length is 0.1-1 μm.

[0045] According to an embodiment of the second aspect of the present invention, in step (2), the dispersing the inorganic ceramic fiber obtained from step (1) in the film forming solution after grinding includes: dispersing the ground inorganic ceramic fiber into the film forming solution and mixing ultrasonically.

[0046] It should be noted that through the ultrasonic treatment, the inorganic ceramic fiber and the film forming solution can be well mixed.

[0047] According to an embodiment of the second aspect of the present invention, in step (2): the net-like woven fabric substrate is selected from one or a combination of polyphenylene sulfide woven fabric, polysulfone woven fabric, and polyether ether ketone woven fabric; the film forming solution includes a film forming solution main material and a film forming solution solvent; the film forming solution main material is selected from one or a combination of polyphenylene sulfide, polysulfone, and polyether ether ketone; the film forming solution solvent is selected from one or a combination of benzophenone, diphenyl ether, cyclohexyl pyrrolidone, polyvinyl pyrrolidone, N-methyl pyrrolidone, and chloroform; the mass proportion of the film forming solution solvent in the film forming solution is 5-50%; the mass proportion of the inorganic ceramic fiber in the film forming solution dispersed with the inorganic ceramic fiber is 1-10%.

[0048] It should be noted that in the preparation method of the composite diaphragm for electrolytic water hydrogen production of the present invention, by selecting the above substances as the net-like woven fabric substrate, selecting the above substances as the film forming solution main material, combining the methods of steps (1) and (2), and simultaneously making the mass proportion of the film forming solution solvent in the film forming solution be 5-50% and the mass proportion of the inorganic ceramic fiber in the film forming solution dispersed with the inorganic ceramic fiber be 1-10%, the stability, hydrophilicity, conductivity of the prepared composite diaphragm can be further improved, and the gas permeability can be reduced to prepare hydrogen with higher purity.

[0049] In summary, polyphenylene sulfide fabric, polysulfone fabric, and polyether ether ketone fabric have good high-temperature and strong alkali resistance, but poor hydrophilicity. Ceramic fibers have good hydrophilicity. The composite separator prepared by the present invention has the advantages of good stability and good hydrophilicity; the composite separator of the present invention has a high porosity and high electrical conductivity; it has lower airtightness than diaphragms such as polyphenylene sulfide fabrics, and higher-purity hydrogen can be obtained.

[0050] The present invention will be further described in detail below through examples, but it is not intended to limit the present invention.

[0051] All reagents used in the following examples are commercially available finished reagents. Among them, F127, P123, and L64 were purchased from Sigma Corporation respectively.

[0052] Example 1

[0053] Preparation of nanofibers: Tetraethyl titanate, ethanol solvent, acetylacetone complexing agent, template agent F127, and fiber-forming agent 10 wt% polyvinylpyrrolidone (aqueous solution) were mixed and stirred evenly to prepare a spinning solution. The molar ratio of tetraethyl titanate:ethanol:acetylacetone:F127:polyvinylpyrrolidone was 1:50:0.02:0.03:0.15. The spinning solution was electrospun into ceramic fibers by an electrospinning device, and then placed in a muffle furnace and calcined at 500 °C for 4 h to obtain inorganic ceramic nanofibers. The diameter of the inorganic ceramic nanofibers after grinding was about 200 nm, and the length was 0.5 μm. Then, the inorganic ceramic nanofibers were ultrasonically stirred evenly with the polyphenylene sulfide film-forming solution, and the polyphenylene sulfide film-forming solution mixed evenly with the inorganic ceramic nanofibers was coated on a polyphenylene sulfide mesh fabric (thickness 500 μm) with a 1000 μm mesh and then scraped to form a film. After drying and phase inversion to remove the solvent, an inorganic ceramic nanofiber-organic composite separator with a thickness of about 650 μm was obtained. The polyphenylene sulfide film-forming solution included polyphenylene sulfide and benzophenone solvent, the mass fraction of the solvent was 40 w%, and the mass ratio of the inorganic ceramic nanofibers in the film-forming solution dispersed with the inorganic ceramic nanofibers was 2%.

[0054] Example 2

[0055] Preparation of nanofibers: A spinning solution was prepared by uniformly mixing zirconium oxychloride precursor, n-butanol solvent, triethanolamine complexing agent, template P123, and 15 wt% polyvinylpyrrolidone (aqueous solution) as the fiber former. The molar ratio of zirconium oxychloride: n-butanol: triethanolamine: template P123: polyvinylpyrrolidone was 1:60:0.02:0.05:0.18. The spinning solution was electrospun into ceramic fibers, which were then calcined in a muffle furnace at 550 °C for 4 h to obtain inorganic ceramic nanofibers. After grinding, the diameter of the inorganic ceramic nanofibers was approximately 60 nm and the length was 0.8 μm. The inorganic ceramic nanofibers were ultrasonically stirred evenly with the polyphenylene sulfide film-forming solution, and the polyphenylene sulfide film-forming solution mixed evenly with the inorganic ceramic nanofibers was coated on a polyphenylene sulfide woven fabric with a 2000 μm mesh (thickness 600 μm) and then scraped to form a film. After drying and phase inversion to remove the solvent, an inorganic ceramic nanofiber-organic composite separator with a thickness of approximately 700 μm was obtained. The polyphenylene sulfide film-forming solution included polyphenylene sulfide and diphenyl ether solvent, the mass fraction of the solvent was 45 w%, and the mass ratio of the inorganic ceramic nanofibers in the film-forming solution dispersed with the inorganic ceramic nanofibers was 5%.

[0056] Example 3

[0057] Preparation of nanofibers: A spinning solution was prepared by uniformly mixing tetraethyl orthosilicate precursor, ethanol solvent, triethanolamine complexing agent, template L64, and 15 wt% polyvinylpyrrolidone (aqueous solution) as the fiber former. The molar ratio of tetraethyl orthosilicate: ethanol: triethanolamine: template L64: polyvinylpyrrolidone was 1:100:0.02:0.1:0.2. The spinning solution was electrospun into ceramic fibers, which were then calcined in a muffle furnace at 450 °C for 4 h to obtain inorganic ceramic nanofibers. After grinding, the diameter of the inorganic ceramic nanofibers was approximately 100 nm and the length was 0.8 μm. The inorganic ceramic nanofibers were ultrasonically stirred evenly with the polysulfone film-forming solution, and the polysulfone film-forming solution mixed evenly with the inorganic ceramic nanofibers was coated on a polysulfone woven fabric with a 3000 μm mesh (thickness 700 μm) and then scraped to form a film. After drying and phase inversion to remove the solvent, an inorganic ceramic nanofiber-organic composite separator with a thickness of approximately 820 μm was obtained. The polysulfone film-forming solution included polysulfone and polyvinylpyrrolidone solvent, the mass fraction of polyvinylpyrrolidone was 35 w%, and the mass ratio of the inorganic ceramic nanofibers in the film-forming solution dispersed with the inorganic ceramic nanofibers was 7%.

[0058] Example 4

[0059] Preparation of nanofibers: Zirconium oxychloride, ethanol solvent, acetylacetone complexing agent, template P123, and 15 wt% polyvinylpyrrolidone were mixed and stirred evenly to form a spinning solution. The molar ratio of the precursor zirconium oxychloride:ethanol:acetylacetone complexing agent:template P123:polyvinylpyrrolidone was 1:100:0.02:0.15:0.25. The spinning solution was electrospun into ceramic fibers, which were then placed in a muffle furnace and calcined at 450 °C for 4 h to obtain inorganic ceramic nanofibers. The diameter of the inorganic ceramic nanofibers was approximately 100 nm and the length was 0.8 μm after grinding. The inorganic ceramic nanofibers were ultrasonically stirred evenly with a polysulfone casting solution, and the polysulfone casting solution mixed evenly with the inorganic ceramic nanofibers was coated on a polyphenylene sulfide woven fabric with 3000 μm mesh holes (thickness 600 μm) and then scraped to form a film. After drying and phase inversion to remove the solvent, an inorganic ceramic nanofiber-organic composite separator with a thickness of approximately 730 μm was obtained. The polysulfone casting solution included polysulfone and polyvinylpyrrolidone, and the mass fraction of polyvinylpyrrolidone was 35 w%. The mass ratio of the inorganic ceramic nanofibers in the casting solution dispersed with the inorganic ceramic nanofibers was 5%.

[0060] Comparative Example 1

[0061] Polysulfone was dispersed in polyvinylpyrrolidone with a mass fraction of polyvinylpyrrolidone of 35 w%, and then dried to remove the solvent to obtain a polysulfone porous membrane with a film layer thickness of approximately 720 μm.

[0062] Test Example 1

[0063] The inorganic ceramic nanofiber-organic composite separator group and the polysulfone membrane prepared in the above examples and Comparative Example 1 were respectively installed in an alkaline electrolytic cell for testing. Under constant voltage testing, the current of the polysulfone membrane prepared in Comparative Example 1 was less than that of the composite membranes prepared in Examples 1-4, indicating that the composite membranes prepared in the above examples improved the hydrophilicity of the membrane surface, thereby reducing the membrane surface resistance and increasing the electrolysis current.

[0064] Among them, the results of the diaphragm current detection after the diaphragms prepared in Example 4 and Comparative Example 1 were assembled into an alkaline electrolytic cell are shown in Table 1 below:

[0065] Table 1

[0066]

[0067] Test Example 2

[0068] The hydrophilic contact angles of the diaphragms prepared in the above examples and Comparative Example 1 were respectively tested. The test photos of the hydrophilic contact angle θ measured for the diaphragm in Example 4 are shown in Figure 2 , and the test photos of the hydrophilic contact angles detected for other examples are similar to Figure 2 , while the test photo of the hydrophilic contact angle θ for the diaphragm prepared in Comparative Example 1 is asFigure 3 As shown, it indicates that after introducing inorganic ceramic fibers, the hydrophilicity is significantly improved.

[0069] The membrane surface resistance of the separators prepared in the examples and Comparative Example 1 was measured respectively. The membrane surface resistance of the examples was < 0.5 Ω / cm 2 , and the membrane surface resistance of Comparative Example 1 was 2.2 Ω / cm 2 .

[0070] Test Example 3

[0071] The inorganic ceramic nanofibers obtained by calcination in Example 1 were analyzed by scanning electron microscopy. The obtained SEM photos are shown in Figure 1 .

[0072] It can be seen through Figure 1 that the diameters d of the calcined inorganic ceramic fibers are relatively uniform.

[0073] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc. is the orientation or positional relationship based on the working state of the present application. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0074] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0075] The present application has been described in combination with preferred embodiments above. However, these embodiments are only exemplary and only serve an illustrative role. On this basis, various substitutions and improvements can be made to the present application, and these all fall within the protection scope of the present application.

Claims

1. A composite diaphragm for hydrogen production by electrolyzing water, characterized in that The composite separator includes a reticulated woven substrate and a composite film layer attached to the reticulated woven substrate, and the composite film layer contains inorganic ceramic fibers and a main film-forming liquid material; wherein, the inorganic ceramic fibers are selected from fibers of one or more oxides of Ti, Zr, Si, and Al; The reticulated woven substrate is selected from one or more combinations of polyphenylene sulfide woven fabrics, polysulfone woven fabrics, and polyether ether ketone woven fabrics; the mesh size of the reticulated woven substrate is 1-5000 μm, and the thickness is 50-1000 μm; The main film-forming liquid material is selected from one or more combinations of polyphenylene sulfide, polysulfone, and polyether ether ketone; The thickness of the composite separator is 50-1500 μm, and the diameter of the inorganic ceramic fibers is 5-500 nm and the length is 0.1-1 μm.

2. The preparation method of the composite separator according to claim 1, characterized in that, The preparation method includes the following steps: (1) Mix a ceramic precursor and an auxiliary agent to obtain a spinning solution, then spin the spinning solution, and calcine the fibers obtained by spinning to obtain inorganic ceramic fibers; (2) Grind the inorganic ceramic fibers obtained from step (1), disperse them in a film-forming solution, coat the film-forming solution dispersed with inorganic ceramic fibers on the surface of the reticulated woven substrate, and then perform film scraping, drying, and phase inversion to obtain a composite separator.

3. The preparation method according to claim 2, characterized in that, In step (1), the ceramic precursor is selected from one or more of esters, inorganic salts, or alcoholates of Ti, Zr, Si, and Al as spinning precursors; The auxiliary agent includes a solvent, a complexing agent, a templating agent, and a fiber-forming agent; The temperature of the calcination is 300-800 °C and the time is 2-10 h.

4. The preparation method according to claim 3, characterized in that, The ceramic precursor is selected from one or more combinations of tetraethyl titanate, tetrabutyl titanate, titanium tetrachloride, zirconium oxychloride, zirconium propoxide, aluminum isopropoxide, and tetraethyl orthosilicate.

5. The preparation method according to claim 3, characterized in that, The solvent is selected from one or more combinations of water, ethanol, propanol, isopropanol, n-butanol, and N,N-dimethylformamide; The complexing agent is selected from one or more combinations of acetylacetone, citric acid, diethanolamine, and triethanolamine; The fiber-forming agent is selected from one or more combinations of polyvinylpyrrolidone, polyvinyl alcohol, and carboxymethyl cellulose; The templating agent is selected from one or more combinations of triblock copolymers, sodium dodecylsulfonate, and polyethylene glycol; The triblock copolymer is selected from one or more combinations of F127, P123, and L64.

6. The preparation method according to claim 3, wherein The molar ratio of the ceramic precursor to the solvent, the complexing agent, the templating agent, and the fiber-forming agent is 1:(4-100):(0.01-0.1):(0.01-0.5):(0.01-0.5).

7. The preparation method according to claim 2, characterized in that, In step (2), the diameter of the inorganic ceramic fibers after grinding is 5-500 nm and the length is 0.1-1 μm.

8. The preparation method according to claim 2, wherein, In step (2), the dispersing of the inorganic ceramic fibers obtained from step (1) in the film-forming solution after grinding includes: Disperse the ground inorganic ceramic fibers into the film-forming solution and mix them by ultrasonic treatment.

9. The preparation method according to claim 2, wherein In step (2): The reticulated woven substrate is selected from one or more combinations of polyphenylene sulfide woven fabrics, polysulfone woven fabrics, and polyether ether ketone woven fabrics; The film-forming solution includes a film-forming solution main material and a film-forming solution solvent; The film-forming solution main material is selected from one or a combination of more than one of polyphenylene sulfide, polysulfone, and polyether ether ketone; The film-forming solution solvent is selected from one or a combination of more than one of benzophenone, diphenyl ether, cyclohexyl pyrrolidone, polyvinyl pyrrolidone, N-methyl pyrrolidone, and chloroform; The mass proportion of the film-forming solution solvent in the film-forming solution is 5-50%; the mass proportion of the inorganic ceramic fibers in the film-forming solution in which the inorganic ceramic fibers are dispersed is 1-10%.

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