A composite fiber separator for an alkaline electrolyzer and a method of manufacturing the same

Abstract

The application relates to the technical field of hydrogen production by alkaline electrolysis of water, in particular to a composite fiber diaphragm for an alkaline electrolysis tank and a preparation method thereof. The preparation method of the composite fiber diaphragm for the alkaline electrolysis tank comprises the following steps: uniformly mixing a high-molecular polymer, hydrophilic nanoparticles and a solvent to obtain an electrostatic spinning precursor solution; the solvent comprises a first solvent; the first solvent comprises an amide organic solvent or / and a pyrrolidone organic solvent; and the electrostatic spinning precursor solution is deposited on a polymer fabric base through electrostatic spinning treatment to obtain the composite fiber diaphragm for the alkaline electrolysis tank. The hydrophilic nanoparticles are uniformly dispersed on the high-molecular polymer nanowire and attached to the surface of the polymer fabric base by using the electrostatic spinning technology, the composite fiber diaphragm for the alkaline electrolysis tank with good mechanical performance, high hydrophilicity and stable chemical performance is prepared, the energy consumption can be reduced, the diaphragm surface resistance can be reduced and the electrolysis efficiency can be improved when the composite fiber diaphragm is applied to the alkaline electrolysis tank.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of hydrogen production by alkaline electrolysis of water, and in particular to a composite fiber diaphragm for an alkaline electrolysis tank and a preparation method thereof. BACKGROUND

[0002] Hydrogen energy has been recognized as a clean energy carrier with zero emissions and zero pollution due to its high energy density, wide sources, and clean and pollution-free advantages. More and more countries regard the development of hydrogen energy as an important part of energy development. Hydrogen energy can be divided into green hydrogen, gray hydrogen, blue hydrogen, and purple hydrogen according to different production methods. Among them, green hydrogen is produced by using clean electricity generated by renewable energy such as wind or solar power to electrolyze water. Green hydrogen basically does not produce greenhouse gases during production, and is the main trend of current hydrogen energy development.

[0003] According to the working principle, temperature, and electrolysis cell materials used, water electrolysis can be divided into three types: alkaline water electrolysis, proton exchange membrane water electrolysis, and high-temperature solid oxide water electrolysis. Alkaline water electrolysis technology has high maturity and cost advantages, and is the main scheme of existing large-scale green hydrogen engineering projects. The diaphragm is a key material for alkaline electrolysis tanks. The diaphragm separates the electrolysis cell into two chambers, anode and cathode, for reduction and oxidation reactions, respectively, and prevents the mixing of generated H2 and O2. Asbestos diaphragm is the earliest commercial alkaline electrolysis tank diaphragm material, but it is gradually replaced by polymer diaphragm because it is a carcinogen.

[0004] Polymer diaphragms have good electrical conductivity, strong chemical stability, and excellent mechanical properties, and are very promising alkaline water electrolysis diaphragm materials, but they generally have poor hydrophilicity. For example, polyphenylene sulfide (PPS) is a key component of the commercial alkaline electrolysis tank diaphragm Zirfon. Due to the presence of benzene rings and sulfide bonds in its molecular structure, PPS has a certain degree of flexibility, good thermal stability, corrosion resistance, mechanical properties, and chemical stability in high-temperature environments, making it a promising polymer diaphragm material. However, PPS fabric has poor hydrophilicity, resulting in high electrical resistance and low electrolysis efficiency of the electrolysis tank. Therefore, how to improve the hydrophilicity of PPS diaphragm is still a problem to be solved.

[0005] In addition, the current process for preparing diaphragms through phase inversion is complex. In addition to effective materials such as PPS, polysulfone, and inorganic nanoparticles, pore-forming agents also need to be added, and a large amount of water is needed during the phase inversion process, which will generate a large amount of wastewater. Moreover, diaphragms prepared by phase inversion are prone to brittleness and poor flexibility in dry state, and usually need to be kept moist. SUMMARY

[0006] Therefore, the technical problem to be solved by the present application is to overcome the defects of the prior art, such as the complex preparation process of the diaphragm for the alkaline electrolytic cell, the need to add a pore-forming agent and the generation of a large amount of wastewater, and the poor performance of the diaphragm, so as to provide a composite fiber diaphragm for an alkaline electrolytic cell and a preparation method thereof.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions.

[0008] In a first aspect, the present application provides a preparation method of a composite fiber diaphragm for an alkaline electrolytic cell, comprising:

[0009] The high molecular polymer, the hydrophilic nanoparticles and the solvent are uniformly mixed to obtain an electrospinning precursor solution; the solvent comprises a first solvent; the first solvent comprises an amide organic solvent or / and a pyrrolidone organic solvent;

[0010] The electrospinning precursor solution is deposited on a polymer fabric substrate through electrospinning treatment to obtain the composite fiber diaphragm for the alkaline electrolytic cell.

[0011] Preferably, the high molecular polymer comprises at least one of polysulfone (PSF), polybenzimidazole (PBI) and sulfonated polyether ether ketone;

[0012] And / or, the amide organic solvent comprises at least one of N,N dimethylformamide (DMF) and N,N dimethylacetamide (DMAc);

[0013] And / or, the pyrrolidone organic solvent comprises N-methyl pyrrolidone (NMP);

[0014] And / or, the solvent further comprises acetone;

[0015] And / or, the solvent further comprises a cosolvent. This is because the high molecular polymer (especially polybenzimidazole) generally has a highly rigid and stable structure, and the addition of the cosolvent can make it dissolve faster and easier in the solvent.

[0016] Preferably, the mass ratio of the first solvent to acetone in the solvent is 1:(0.05-0.2);

[0017] And / or, the cosolvent comprises lithium chloride;

[0018] And / or, the mass of the cosolvent is 1-5wt% of the mass of the solvent, preferably 3wt%.

[0019] Preferably, the material of the polymer fabric substrate comprises at least one of polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polypropylene (PP), polyimide (PI) and polybenzimidazole (PBI).

[0020] Preferably, the hydrophilic nanoparticles comprise at least one of nano-zirconium dioxide particles, nano-silicon dioxide particles, nano-cerium dioxide particles, nano-titanium dioxide particles, nano-aluminum oxide particles.

[0021] Preferably, the mass ratio of the high molecular polymer, the hydrophilic nanoparticles and the solvent is (1-2):(1-2):(6-14), preferably 1:2:6.

[0022] Preferably, the process for obtaining the electrospinning precursor solution comprises: mixing the high molecular polymer and the solvent to obtain a high molecular polymer dispersion liquid; and mixing the high molecular polymer dispersion liquid and the hydrophilic nanoparticles to obtain the electrospinning precursor solution.

[0023] Preferably, the electrospinning treatment is a double-sided electrospinning treatment.

[0024] Preferably, the parameters of the electrospinning treatment are: the voltage is 10-20kV, the distance between the needle tip and the roller is 15-25cm, and the feeding flow rate of the electrospinning precursor solution is 1-2ml / h.

[0025] Preferably, after the electrospinning treatment, a drying treatment is further performed.

[0026] Preferably, the drying treatment is drying in dry air for 24h to remove residual solvent.

[0027] In a second aspect, the present application further provides a composite fiber diaphragm for an alkaline electrolytic cell, which is prepared by the above-mentioned method for preparing a composite fiber diaphragm for an alkaline electrolytic cell.

[0028] The technical scheme of the present application has the following advantages:

[0029] The application discloses a preparation method of a composite fiber diaphragm for an alkaline electrolytic cell, and belongs to the technical field of composite fiber diaphragms.

[0030] In addition, the fiber diaphragm prepared by electrospinning has better flexibility, is not easy to break or fall off after being bent, and is convenient to store and transport, while the diaphragm prepared by phase inversion is easy to become brittle in a dry state and usually needs to be kept in a wet state. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0032] Figure 1 FIG. 1 is a preparation process schematic diagram of the composite fiber diaphragm for the alkaline electrolytic cell in Embodiment 1 of the application. DETAILED DESCRIPTION

[0033] The following examples are provided to better further understand the application, and do not limit the content and protection scope of the application. Any person who is inspired by the application or combines the application with other prior art features to obtain any product same or similar to the application falls within the protection scope of the application.

[0034] Unless otherwise indicated, the specific experimental procedures or conditions in the examples were carried out according to the conventional experimental procedures described in the literature in the art. The reagents or instruments used were not specified by the manufacturer, and were all conventional reagent products that can be obtained commercially.

[0035] Example 1

[0036] This example provides a preparation method of a composite fiber separator for an alkaline electrolyzer, and a preparation process schematic diagram is shown as follows: Figure 1 The specific steps are as follows:

[0037] 1) Obtain an electrospinning precursor solution: first, mix 1 g of polysulfone (PSF) with 6 g of solvent (a mixed solvent of N,N dimethylformamide and acetone with a mass ratio of 1:0.1), and stir mechanically until completely dissolved to form a transparent solution; then add 2 g of nano zirconium dioxide particles (ZrNP) in 4 times, and continuously stir to prevent nano particle agglomeration, finally form a uniform precursor solution, stand for 12 h to remove bubbles, and prepare an electrospinning precursor solution;

[0038] 2) Put the electrospinning precursor solution prepared in step 1) into an electrospinning injector, and perform double-sided electrospinning with polyphenylene sulfide (PPS) fabric attached to the drum; the electrospinning parameters are: voltage 15 KV, distance from needle tip to drum 15 cm, and feeding speed 1.5 ml / h; after spinning, take down the separator and dry it in dry air for 24 h to remove residual solvent, and obtain a composite fiber separator for an alkaline electrolyzer.

[0039] Example 2

[0040] This example provides a preparation method of a composite fiber separator for an alkaline electrolyzer, and the specific steps are as follows:

[0041] 1) Obtain an electrospinning precursor solution: first, mix 1 g of polybenzimidazole with 6 g of solvent (a solution of N,N dimethylacetamide containing 3 wt% LiCl), and stir mechanically at 120°C until the polymer is completely dissolved, centrifuge the solution to remove insoluble impurities, and take the supernatant; then add 2 g of nano titanium dioxide particles in 3 times, and continuously stir to prevent nano particle agglomeration, finally form a uniform precursor solution, stand for 12 h to remove bubbles, and prepare an electrospinning precursor solution;

[0042] 2) Put the electrospinning precursor solution prepared in step 1) into an electrospinning injector, and perform double-sided electrospinning with polyphenylene sulfide fabric attached to the drum; the electrospinning parameters are: voltage 20 KV, distance from needle tip to drum 25 cm, and feeding speed 2 ml / h; after spinning, take down the separator and dry it in dry air for 24 h to remove residual solvent, and obtain a composite fiber separator for an alkaline electrolyzer.

[0043] Example 3

[0044] The embodiment provides a preparation method of a composite fiber diaphragm for an alkaline electrolytic cell, and the specific steps are as follows:

[0045] 1) Obtain an electrospinning precursor solution: first, sulfonate polyether ether ketone with sulfuric acid to make it soluble; 1g of sulfonated polyether ether ketone is mixed with 6g of N,N-dimethylformamide, and mechanical stirring is performed until the polymer is completely dissolved; then 2g of nano-aluminum oxide particles are added in four times, and continuous stirring is performed to prevent the nano-particles from agglomerating, and finally a uniform precursor solution is formed, and the solution is left standing for 12h to remove bubbles, thereby obtaining the electrospinning precursor solution;

[0046] 2) The electrospinning precursor solution prepared in step 1) is loaded into an electrospinning injector, and a polypropylene fabric is attached to a roller to perform double-sided electrospinning; the electrospinning parameters are as follows: a voltage of 15KV, a distance between a needle tip and the roller of 15cm, and a feeding speed of 1ml / h; after the spinning is completed, the diaphragm is taken down and dried in dry air for 24h to remove residual solvents, thereby obtaining the composite fiber diaphragm for the alkaline electrolytic cell.

[0047] Example 4

[0048] The embodiment provides a preparation method of a composite fiber diaphragm for an alkaline electrolytic cell, and the specific steps are as follows:

[0049] 1) Obtain an electrospinning precursor solution: 1g of polysulfone is mixed with 6g of a solvent (a mixed solvent of N,N-dimethylformamide and acetone with a mass ratio of 1:0.1), and 2g of nano-zirconium dioxide particles are simultaneously mixed, and mechanical stirring is performed for more than 24h until a uniform precursor solution is formed, and the solution is left standing for 12h to remove bubbles, thereby obtaining the electrospinning precursor solution;

[0050] 2) The electrospinning precursor solution prepared in step 1) is loaded into an electrospinning injector, and a polyphenylene sulfide (PPS) fabric is attached to a roller to perform double-sided electrospinning; the electrospinning parameters are as follows: a voltage of 15KV, a distance between a needle tip and the roller of 15cm, and a feeding speed of 1.5ml / h; after the spinning is completed, the diaphragm is taken down and dried in dry air for 24h to remove residual solvents, thereby obtaining the composite fiber diaphragm for the alkaline electrolytic cell.

[0051] Example 5

[0052] The embodiment provides a preparation method of a composite fiber diaphragm for an alkaline electrolytic cell, and the difference from the embodiment 1 is that the solvent is N,N-dimethylformamide, that is, a single solvent is used, and other conditions are the same as those in the embodiment 1.

[0053] Example 6

[0054] The embodiment provides a preparation method of a composite fiber diaphragm for an alkaline electrolyzer, which is different from the embodiment 1 in that N-methyl pyrrolidone is used instead of N,N dimethylformamide, and other conditions are the same as those in the embodiment 1.

[0055] Comparative example 1

[0056] The comparative example provides a preparation method of a composite diaphragm for an alkaline electrolyzer, and the specific steps are as follows:

[0057] 1) Obtain a casting solution: first, mix 3 g of polysulfone (PSF) and 11 g of N-methyl pyrrolidone, and mechanically stir until completely dissolved to form a transparent solution; then add 3 g of polyvinylpyrrolidone pore-forming agent, continue to stir until the solvent is fully dissolved, and then add 3 g of nano zirconium dioxide particles (ZrNP) in three times, mechanically stir for 24 h to form a uniform solution, and stir at low speed or stand still for 12 h to remove air bubbles, to obtain a phase inversion casting solution;

[0058] 2) Pour the above-mentioned casting solution onto a flat glass plate, adjust the thickness with a film scraper, and scrape the film, pre-evaporate in the air for 30 seconds, and then place the glass plate as a whole in deionized water for phase inversion, and after 10 minutes, the casting solution is solidified and falls off from the glass plate to obtain a composite diaphragm.

[0059] 3) Soak the above-mentioned diaphragm in deionized water for 20 minutes to further precipitate the residual solvent. Repeat the soaking for 2-3 times, take out the composite diaphragm, and place it in a clean room for drying for more than 24 h to obtain the comparative example composite diaphragm.

[0060] Comparative example 2

[0061] The comparative example provides a preparation method of a composite fiber diaphragm for an alkaline electrolyzer, which is different from the embodiment 1 in that the solvent is acetone, that is, a single solvent is used, and other conditions are the same as those in the embodiment 1. In the comparative example, because the acetone cannot dissolve the high molecular polymer, the electrospinning precursor solution cannot be obtained, and thus the subsequent operation cannot be performed, and the composite fiber diaphragm for the alkaline electrolyzer cannot be prepared.

[0062] Test example 1

[0063] The test example tests the performance of the composite diaphragm samples for alkaline electrolyzers prepared in the above-mentioned embodiments and comparative examples, and the test results are shown in Table 1.

[0064] The contact angle is tested by using deionized water as a medium. The instrument used is Chengde Dingsheng JY-82C contact angle measuring instrument. The test steps are as follows: at room temperature, the prepared separator is cut into a sample with a length and width of 20 mm x 20 mm, which is placed on the JY-82 contact angle test platform, the sample is kept flat, a water droplet is dropped by using the automatic titration system of the equipment, a test photo is taken, the droplet shape curve in the image is fitted, and the contact angle is calculated.

[0065] The porosity is tested by the n-butanol immersion method. The separator is cut into a sample with a size of 20 mm x 20 mm, which is immersed in n-butanol for 2 h. After being taken out, the liquid on the surface of the separator is wiped dry with test paper, and the mass is weighed to calculate the porosity. Each sample is determined in triplicate, and the average value is taken. The porosity calculation formula is: porosity = (W1-W0) / pV0x100%; wherein W1 and W0 are the masses (mg) of the polymer film before and after immersion in n-butanol, p is the density of n-butanol (mg / cm 3 ), and V0 is the volume of the separator before immersion in n-butanol (cm 3 ).

[0066] The specific surface area is tested by nitrogen isothermal desorption experiment. Specifically, about 50-100 mg of sample is placed in a test bottle for 12 h of degassing pretreatment to remove water and adsorbed gas in the sample, and nitrogen adsorption and desorption test is performed under low-temperature liquid nitrogen. The specific surface area of the separator is calculated by the multi-point Brunauer-Emmett-Teller (BET) method.

[0067] The tensile strength is tested by an electronic universal material testing machine. The separator is cut into a sample with a size of 40 mm x 10 mm for tensile testing at a tensile rate of 10 mm / min and a clamping distance of 20 mm. Each sample is determined in triplicate, and the average value is taken.

[0068] The surface resistance is tested by the following method:

[0069] 1) Five samples of the separator with a size of 2.5 cm x 6 cm are placed in a 30% potassium hydroxide solution for immersion for more than 4 h.

[0070] 2) The alkali solution is injected into the resistance test tank, two test clamps are assembled, and placed in the resistance test tank filled with electrolyte, the electrodes are connected, and the solution resistance without the separator is tested;

[0071] 3) The separator sample is assembled into the test clamp, and the total resistance of the solution and the separator after adding the separator is tested;

[0072] 4) The average value of the surface resistance test results of the five test samples is taken as the measured value of the surface resistance of the separator.

[0073] Table 1

[0074]

[0075]

[0076] Obviously, the above-mentioned embodiments are only examples for clearly illustrating, but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments are not required to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for producing a composite fiber separator for an alkaline electrolyzer, characterized by, The application relates to a preparation method of a composite fiber diaphragm for an alkaline electrolytic cell. The method comprises the following steps: mixing a high-molecular polymer, hydrophilic nanoparticles and a solvent to obtain an electrostatic spinning precursor solution; the solvent comprises a first solvent and acetone; the first solvent comprises an amide organic solvent or / and a pyrrolidone organic solvent; the mass ratio of the first solvent and acetone in the solvent is 1:(0.05-0.2); The electrostatic spinning precursor solution is deposited on a polymer fabric substrate through electrostatic spinning treatment to obtain the composite fiber diaphragm for the alkaline electrolytic cell.

2. The production method according to claim 1, characterized by, The high-molecular polymer comprises at least one of polysulfone, polybenzimidazole and sulfonated polyether ether ketone; And / or, the amide organic solvent comprises at least one of N,N dimethylformamide and N,N dimethylacetamide; And / or, the pyrrolidone organic solvent comprises N-methyl pyrrolidone.

3. The preparation method according to claim 1, characterized in that, The material of the polymer fabric substrate comprises at least one of polyphenylene sulfide, polytetrafluoroethylene, polypropylene, polyimide and polybenzimidazole.

4. The method of claim 1, wherein, The hydrophilic nanoparticles comprise at least one of nano zirconium dioxide particles, nano silicon dioxide particles, nano cerium dioxide particles, nano titanium dioxide particles and nano aluminum oxide particles.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the high-molecular polymer, the hydrophilic nanoparticles and the solvent is (1-2):(1-2):(6-14).

6. The production method according to claim 5, wherein The mass ratio of the high-molecular polymer, the hydrophilic nanoparticles and the solvent is 1:2:

6.

7. The preparation method according to claim 1, characterized in that, The process of obtaining the electrostatic spinning precursor solution comprises the following steps: mixing the high-molecular polymer and the solvent to obtain a high-molecular polymer dispersion liquid; and mixing the high-molecular polymer dispersion liquid and the hydrophilic nanoparticles to obtain the electrostatic spinning precursor solution.

8. The method of claim 1, wherein, The electrostatic spinning treatment is double-sided electrostatic spinning treatment.

9. The method of claim 1, wherein, The parameters of the electrostatic spinning treatment are as follows: the voltage is 10-20 kV, the distance from the needle tip to the roller is 15-25 cm, and the feeding flow rate of the electrostatic spinning precursor solution is 1-2 ml / h; And / or, the electrostatic spinning treatment is followed by drying treatment.

10. A composite fiber separator for an alkaline electrolyzer, characterized by comprising a porous polyolefin microporous membrane and a porous polyolefin microporous membrane having a surface layer of a porous polyolefin microporous membrane. The composite fiber diaphragm for the alkaline electrolytic cell is prepared by the preparation method of the composite fiber diaphragm for the alkaline electrolytic cell.

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