High-performance alkaline water electrolysis composite diaphragm, preparation method and application thereof

Abstract

The application relates to the technical field of hydrogen production by alkaline water electrolysis, in particular to a high-performance alkaline water electrolysis composite diaphragm and a preparation method and application thereof. The preparation method comprises the following steps: S1, soaking an organic polymer matrix in a swelling solvent to obtain a swollen organic polymer matrix; S2, mixing a swelling solvent and a precursor aqueous solution to obtain a functional inorganic mother liquor; S3, adding the swollen organic polymer matrix in step S1 into the functional inorganic mother liquor in step S2, standing, in-situ growth reaction, washing and drying to obtain an organic-inorganic composite diaphragm, namely a high-performance alkaline water electrolysis composite diaphragm. Compared with the prior art, the application can effectively enhance the firmness of the composite diaphragm, improve the hydrophilicity of the composite diaphragm, reduce the surface resistance of the composite diaphragm, and enhance the electrolysis performance and electrolysis stability of the composite diaphragm.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of alkaline water electrolysis hydrogen production, in particular to a high-performance alkaline water electrolysis composite diaphragm and a preparation method and application thereof. BACKGROUND

[0002] Hydrogen energy is considered as the "ultimate energy" in the 21st century due to its high calorific value, diverse sources, abundant reserves and characteristics suitable for large-capacity and long-time storage, and has become an important part of the future national energy system and an important carrier for realizing green and low-carbon transformation of energy terminal. Hydrogen energy, as a "zero-carbon emission" renewable energy, can realize efficient conversion between hydrogen energy and electric energy through water electrolysis technology, and can overcome the discontinuity and instability of wind and solar power generation, and realize large-scale conversion and storage of energy. Therefore, carrying out research on renewable energy water electrolysis hydrogen production technology meets the major strategic needs of the country and is of great significance for the sustainable development of human society.

[0003] Compared with proton exchange membrane electrolysis hydrogen production technology and other technologies, alkaline water electrolysis hydrogen production technology has the advantages of mature technology and low cost, and has realized commercialization, and is the mainstream technology of current electrolysis hydrogen production industrialization. Diaphragm material is the core component and key material of water electrolysis hydrogen production device, and directly affects the energy consumption, gas purity, electrolysis stability and safety of water electrolysis. Polymer diaphragm is widely used in alkaline electrolysis hydrogen production diaphragm due to its high chemical stability and mechanical strength. However, this kind of membrane cannot be uniformly infiltrated into the membrane hole by water solution electrolyte due to its low surface energy, and the transfer of hydroxyl ions is blocked, which increases the internal resistance of the electrolysis system and increases the electrolysis energy consumption. Therefore, the polymer needs to be hydrophilic modified to enhance the hydrophilicity and reduce the surface resistance.

[0004] The common hydrophilic modification is divided into two categories. One is to graft hydrophilic functional groups on the surface of the polymer, such as sulfonation treatment (Chinese patents CN119082984A, CN118292259A, etc.), but the hydrophilic functional groups are easy to lose stability and fall off in the high-temperature and strong-alkali water electrolysis hydrogen production environment, and the hydrophilicity of the modified polymer is difficult to maintain, so that the surface resistance of the diaphragm increases again after a period of operation, which finally affects the electrolysis efficiency. The other is to mix inorganic substances into the polymer casting solution to prepare a composite diaphragm by blending the polymer and the inorganic powder. Hydrophilic inorganic substances can effectively reduce the membrane resistance and thus reduce the electrolysis energy consumption. Typical examples are Composite diaphragm, similar method also has Chinese patent CN114207189A, CN115029732A, CN115677269A and so on. The common problem of this kind of composite diaphragm is that the surface of the diaphragm is easy to crack, and the inorganic matter is easy to fall off. The essential reason is that the inorganic matter and the organic polymer matrix are poor in compatibility, which leads to that the organic-inorganic combination is not firm, and the inorganic matter occurs self-agglomeration. In addition, in order to make the composite diaphragm obtain good hydrophilicity and mechanical strength, the particle size of the inorganic matter must reach micron or even nanometer level, and the smaller the particle, the more serious the agglomeration phenomenon, which puts higher requirements on the dispersion process of the material, and is not conducive to the large-scale production of the composite diaphragm. SUMMARY

[0005] The purpose of the present application is to overcome the defects of poor compatibility of organic and inorganic materials in the organic-inorganic composite membrane, easy agglomeration and falling off of inorganic materials in the polymer matrix in the prior art, and to provide a high-performance alkaline water electrolysis composite diaphragm, a preparation method and application thereof, which can effectively enhance the firmness of the composite diaphragm, improve the hydrophilicity of the composite diaphragm, reduce the surface resistance of the composite diaphragm, and enhance the electrolysis performance and electrolysis stability of the composite diaphragm.

[0006] The purpose of the present application can be realized by the following technical solutions:

[0007] One of the technical solutions of the present application is to provide a preparation method of a high-performance alkaline water electrolysis composite diaphragm, comprising the following steps:

[0008] S1, soaking the organic polymer matrix in a swelling solvent to obtain a swollen organic polymer matrix;

[0009] S2, mixing the swelling solvent with a precursor aqueous solution to obtain a functional inorganic material mother liquor;

[0010] S3, adding the swollen organic polymer matrix in step S1 into the functional inorganic material mother liquor in step S2, standing, in-situ growth reaction, washing and drying to obtain an organic-inorganic composite diaphragm, i.e. a high-performance alkaline water electrolysis composite diaphragm, and the process is completed.

[0011] Further, in step S1, the organic polymer matrix includes but is not limited to polyphenylene sulfide (PPS), polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), polyimide (PI), and its existing forms include porous membrane, fiber membrane, non-woven fabric, woven fabric, composite fabric;

[0012] In steps S1 and S2, the swelling solvent includes but is not limited to N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, toluene;

[0013] The volume ratio of the organic polymer matrix and the swelling solvent is 1:20-200.

[0014] Further, in step S1, because the different organic polymer matrixes have different swelling difficulty, in order to make the organic polymer matrix reach a certain degree of swelling without dissolving, the soaking time is generally 1-10 days.

[0015] Further, in step S1, in order to accelerate the penetration process, the organic polymer matrix is subjected to heat treatment at 25-100°C.

[0016] Further, in step S2, the precursor aqueous solution is a mixed solution containing divalent metal cations, trivalent metal cations and basic substances.

[0017] Further, the divalent metal cations include but are not limited to one or more of Mg 2+ , Zn 2+ , Co 2+ , Ni 2+ , Fe 2+ , etc.; the trivalent metal cations include but are not limited to one or more of Al 3+ , Fe 3+ ; and the basic substances include but are not limited to sodium hydroxide, potassium hydroxide, urea, ammonia, and hexamethylenetetramine.

[0018] The concentration of the divalent metal cations is 0.02-1 mol / L, the concentration of the trivalent metal cations is 0.02-1 mol / L, and the concentration of the basic substances is 0.1-5 mol / L.

[0019] Further, in step S2, the volume ratio of the swelling solvent and the precursor aqueous solution is 1:0.3-3.

[0020] Further, in step S2, the functional inorganic material mother liquor has hydrophilicity.

[0021] Further, in step S3, the volume ratio of the swollen organic polymer matrix and the functional inorganic material mother liquor is 1:1-50.

[0022] The in-situ growth reaction includes but is not limited to co-precipitation and hot solvent method, and the free volume or surface micropore in the organic polymer matrix is used as a nucleation site, and a suitable reaction environment is provided to make the functional inorganic material grow from the inside to the outside of the organic polymer matrix.

[0023] Further, in step S3, the swollen organic polymer matrix is added to the functional inorganic material mother liquor and is allowed to stand for 0.5-5 h, so that the precursor solution is fully introduced into the organic polymer matrix.

[0024] Further, in step S3, the washing uses deionized water and ethanol alternately, the drying temperature is 50-80 DEG C, and the drying time is 6-24h.

[0025] Further, when the swelling solvent is immiscible with the precursor aqueous solution, the preparation method comprises the following steps:

[0026] S1, soaking the organic polymer matrix in a swelling solvent to obtain a swollen organic polymer matrix, and replacing the swelling solvent with a medium solvent by placing the swollen organic polymer matrix in the medium solvent to obtain a replaced organic polymer matrix;

[0027] S2, mixing another medium solvent and a precursor aqueous solution to obtain a functional inorganic material mother liquor;

[0028] S3, adding the replaced organic polymer matrix in step S1 into the functional inorganic material mother liquor in step S2, standing, in-situ growth reaction, washing and drying to obtain an organic-inorganic composite diaphragm, i.e., a high-performance alkaline water electrolysis composite diaphragm, and the process is completed.

[0029] Further, the medium solvent is a solvent that is miscible with both the precursor aqueous solution and the swelling solvent, including but not limited to ethanol, acetone, tetrahydrofuran;

[0030] In step S1, the volume ratio of the swollen organic polymer matrix to the medium solvent is 1:50-200;

[0031] In step S2, the volume ratio of the precursor aqueous solution to the medium solvent is 1:0.3-3;

[0032] In step S3, the volume ratio of the replaced organic polymer matrix to the functional inorganic material mother liquor is 1:1-50.

[0033] Further, after the swollen organic polymer matrix is placed in the medium solvent, it is ultrasonically treated for 0.5-2h, and then new medium solvent is replaced again, and the ultrasonic treatment is repeated for 3-5 times to fully fill the medium solvent into the organic polymer matrix.

[0034] The second technical solution of the present application provides a high-performance alkaline water electrolysis composite diaphragm, which is prepared by the above preparation method.

[0035] Further, the composite diaphragm comprises an organic polymer matrix and functional inorganic materials that are in-situ grown on the surface and inside of the organic polymer matrix, the functional inorganic materials completely cover the surface of the organic polymer matrix, and the functional inorganic materials present a two-dimensional sheet / multi-porous structure and are inserted into the inside of the organic polymer matrix.

[0036] Further, unlike the common organic-inorganic composite separator structure, the grown functional inorganic matter can completely cover the surface of the organic polymer matrix, and thus can be completely infiltrated by water, thereby exhibiting superhydrophilicity. The functional inorganic matter exhibits an ordered and two-dimensional sheet / porous structure, and is inserted into the interior of the organic polymer matrix, which is conducive to absorbing alkaline electrolyte, promoting both the hydrogen and hydroxyl ion conduction and the firmness of the organic-inorganic combination. Moreover, the grown functional inorganic matter has intrinsic hydrogen and hydroxyl ion conduction capability, which can further reduce the surface resistance of the separator, thereby reducing the electrolysis energy consumption.

[0037] Further, the functional inorganic matter includes, but is not limited to, covalent organic frameworks, perovskite oxides, and layered hydroxides with hydrogen and hydroxyl ion transport capability.

[0038] Further, the functional inorganic matter includes, but is not limited to, modified covalent organic frameworks, modified perovskite oxides, and layered hydroxides.

[0039] Further, the modified covalent organic framework includes a modified covalent organic framework doped with zirconate;

[0040] The modified perovskite oxide includes a modified perovskite oxide doped with cationic imidazole groups, quaternary ammonium groups, polybenzimidazolium, or viologen;

[0041] The layered hydroxide includes, but is not limited to, Mg(OH)2, Co(OH)2, MgAl LDH, ZnAl LDH, CoAl LDH, NiFe LDH, ZnMgAl LTTH, and FeCuNi LTTH.

[0042] The third aspect of the technical solution of the present application provides an application of a high-performance alkaline water electrolysis composite separator in the field of alkaline water electrolysis hydrogen production.

[0043] Compared with the prior art, the present application has the following advantages:

[0044] (1) The composite separator prepared by the present application has small surface resistance and good stability. The functional inorganic matter not only has good hydrophilicity, but also has intrinsic hydrogen and hydroxyl ion conduction. After the introduction of the functional inorganic matter, the surface resistance of the composite separator is significantly reduced, and excellent electrolysis performance is exhibited. In particular, the present application induces the in-situ growth of functional inorganic matter from the interior of the separator through the swelling regulation of the organic polymer matrix, and the functional inorganic matter is pinned in the interior of the composite separator, which enhances the firmness of the combination of the functional inorganic matter and the organic polymer matrix, effectively prevents the shedding of the functional inorganic matter, and improves the structural and performance stability of the composite separator.

[0045] (2) The functional inorganic particles in the application are fine and uniformly dispersed, the composite diaphragm has good hydrophilic stability and enhanced air tightness. The application creates dense nucleation sites for the functional inorganic particles by regulating the swelling of the organic polymer matrix, and in the limited growth environment of the organic polymer matrix, the generated functional inorganic particles are fine and dispersed, effectively preventing the agglomeration of the functional inorganic particles, and enhancing the hydrophilic and hydrophilic stability of the composite diaphragm. In addition, the fine and dense functional inorganic particles can fill the pores of the organic polymer matrix of the composite diaphragm, enhancing the air tightness of the composite diaphragm.

[0046] (3) The application realizes non-destructive regulation of the organic polymer matrix of the composite diaphragm, and the regulation process is mild and effective, prolonging the service life of the composite diaphragm. Compared with existing chemical modification (such as sulfonation treatment), the application utilizes the swelling characteristics of the organic polymer matrix for reversible regulation, does not use strong corrosive solvents, does not damage the organic polymer matrix of the composite diaphragm, ensures the mechanical strength of the composite diaphragm, and the close combination of the organic polymer matrix and the functional inorganic particles further enhances the toughness of the composite diaphragm.

[0047] (4) The preparation method of the application is simple, safe and easy to operate, and is easy to industrialize. The composite diaphragm prepared by the application has excellent electrolysis performance and stability in alkaline water electrolysis hydrogen production. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 The process flow chart of the preparation method of the high-performance alkaline water electrolysis composite diaphragm of the application is shown in the figure.

[0049] Figure 2 The characterization figure of the composite diaphragm shown in Example 1 is shown in the figure: (a) surface morphology-1mm; (b) surface morphology-200nm; (c) cross-sectional morphology-10μm; (d-g) cross-sectional energy spectrum: (d) cross-sectional morphology, (e) Ni element distribution in the corresponding area, (f) Fe element distribution in the corresponding area, (g) O element distribution in the corresponding area.

[0050] Figure 3 The firmness test figure of the composite diaphragm prepared by Examples 1-5 and Comparative Examples 1-4 is shown in the figure: (a) swelling rate of the diaphragm of each preparation process; (b) mass loss rate of the diaphragm in high-frequency oscillation; (c-f) morphology of the composite diaphragm before and after firmness test: (c) Comparative Example 2-before test, (d) Example 1-before test, (e) Comparative Example 2-after test, (f) Example 1-after test.

[0051] Figure 4 The surface resistance test result figure of the diaphragm prepared by Examples 1-4 and Comparative Examples 1-3 is shown in the figure.

[0052] Figure 5Linear voltammograms of the separators prepared for Examples 1-4, Comparative Examples 1-3;

[0053] Figure 6 Electrolytic stability results of the composite separator prepared for Example 1, Comparative Example 2: (a-b) morphology after immersion: (a) Example 1, (b) Comparative Example 2; (c) electrolytic performance of Example 1, Comparative Example 2 before and after immersion; (d) constant current chronovoltage curve of Example 1 under working conditions. DETAILED DESCRIPTION

[0054] The application will be described in greater detail with reference to the accompanying drawings and specific embodiments. The embodiments are implemented on the premise of the technical solutions of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following embodiments. All other embodiments obtained by those of ordinary skill in the art on the premise that no creative labor is done based on the given embodiments belong to the scope of protection of the application.

[0055] Unless otherwise specified, the reagents, methods, instruments and equipment used in the application are conventional reagents, methods, instruments and equipment in the art.

[0056] In the following examples and comparative examples, the PPS woven cloth is TORCON TM The PPS woven cloth is purchased from Toray Industries, Inc. The filter membrane is Merck Millipore's The filter membrane is FHUP04700.

[0057] Example 1

[0058] A preparation method of a high-performance alkaline water electrolysis composite separator, as shown in Figure 1 includes the following steps:

[0059] S1, place a circular PPS woven cloth with a diameter of 3 cm in 60 mL of N-methyl pyrrolidone, heat at 80°C for 180 h to obtain a swollen PPS woven cloth;

[0060] S2, prepare a precursor aqueous solution with a solute of 0.6 mol / L nickel nitrate, 0.2 mol / L ferrous chloride and 2 mol / L urea, mix it with the same volume of N-methyl pyrrolidone to form a uniform functional inorganic mother liquor (functional inorganic material-NiFe LDH);

[0061] S3, place the swollen PPS woven cloth of step S1 into 20 mL of the functional inorganic mother liquor prepared in step S2 and stand for 2 h, then hydrothermally treat at 90°C for 8 h. Take out the PPS woven cloth after hydrothermal growth, wash with deionized water and ethanol respectively, and dry at 60°C for 8 h, to finally obtain an organic-inorganic composite separator.

[0062] Example 2

[0063] A method for preparing a high-performance alkaline water electrolysis composite diaphragm, compared with Example 1, uses other swelling solvents (toluene) for swelling, as shown in Figure 1 , comprising the following steps:

[0064] S1, place a circular PPS woven cloth with a diameter of 3 cm in 60 mL of toluene, heat to 100°C under condensation reflux, and keep for 100 h to obtain a swollen PPS woven cloth. Place the swollen PPS woven cloth in 60 mL of ethanol, ultrasonic treatment for 1 h, then place the PPS woven cloth in 60 mL of fresh ethanol and continue ultrasonic treatment. Repeat the ultrasonic treatment for 3 times, then the deionized water and the liquid after ultrasonic treatment are completely mixed, that is, the toluene in the PPS is completely replaced by ethanol.

[0065] S2, prepare a precursor aqueous solution with a solute of 0.6 mol / L nickel nitrate, 0.2 mol / L ferrous chloride, and 2 mol / L urea, mix it with the same volume of ethanol to form a uniform functional inorganic material mother liquor (functional inorganic material—NiFe LDH);

[0066] S3, place the PPS woven cloth after step S1 swelling with sufficient ethanol into 20 mL of the functional inorganic material mother liquor prepared in step S2 and stand for 2 h, then hydrothermal treatment at 90°C for 8 h. Take out the PPS woven cloth after hydrothermal growth, wash with deionized water and ethanol respectively, and dry at 60°C for 8 h to finally obtain an organic-inorganic composite diaphragm.

[0067] Example 3

[0068] A method for preparing a high-performance alkaline water electrolysis composite diaphragm, compared with Example 1, uses other functional inorganic material mother liquor, as shown in Figure 1 , comprising the following steps:

[0069] S1, place a circular PPS woven cloth with a diameter of 3 cm in 60 mL of N-methyl pyrrolidone, heat at 80°C for 180 h to obtain a swollen PPS woven cloth;

[0070] S2, prepare a precursor aqueous solution with a solute of 0.4 mol / L aluminum nitrate, 0.2 mol / L magnesium chloride, and 3 mol / L urea, mix it with the same volume of N-methyl pyrrolidone to form a uniform functional inorganic material mother liquor (functional inorganic material—MgAl LDH);

[0071] S3, put the PPS fabric pre-wetted in step S1 into 20 mL of the functional inorganic material mother liquor prepared in step S2 and stand for 2 h, and then hydrothermally treat at 140°C for 12 h. Take out the PPS fabric with completed hydrothermal growth, clean with deionized water and ethanol respectively, and dry at 60°C for 8 h to finally obtain the organic-inorganic composite separator.

[0072] Example 4

[0073] A preparation method of a high-performance alkaline water electrolysis composite separator, compared with example 1, uses other in-situ growth methods (co-precipitation synthesis method), such as Figure 1 as shown, comprising the following steps:

[0074] S1, place a circular PPS fabric with a diameter of 3 cm in 60 mL of N-methyl pyrrolidone and heat at 80°C for 180 h to obtain the swollen PPS fabric;

[0075] S2, prepare the following solutions respectively: 1) a precursor aqueous solution with a solute of 0.06 mol / L nickel nitrate and 0.03 mol / L iron nitrate, mix the same volume of N-methyl pyrrolidone (NMP) to form a uniform precursor NMP aqueous solution (solution ①); 2) an aqueous solution with a solute of 0.5 mol / L sodium hydroxide, mix the same volume of NMP to form a uniform NMP aqueous solution (solution ②).

[0076] S3, put the swollen PPS fabric in step S1 into 60 mL of solution ① prepared in step S2 and stand for 1 h, take out the PPS fabric and put it into 60 mL of solution ② prepared in step S2 and stand for 1 h, repeat the above steps for 3 times. Take out the PPS fabric with completed co-precipitation growth, clean with deionized water and ethanol respectively, and dry at 60°C for 8 h to finally obtain the organic-inorganic composite separator.

[0077] Example 5

[0078] A preparation method of a high-performance alkaline water electrolysis composite separator, compared with example 1, uses other organic polymer matrix (PTFE porous membrane), such as Figure 1 as shown, comprising the following steps:

[0079] S1, place a circular PTFE porous membrane with a diameter of 3 cm in 60 mL of n-hexane and heat at 60°C for 7 days to obtain the swollen PTFE porous membrane. Place the swollen PTFE porous membrane in 60 mL of ethanol and ultrasonic treat for 1 h, replace the fresh ethanol 60 mL, and repeat the ultrasonic treatment for 3 times to obtain the swollen PTFE porous membrane fully filled with ethanol;

[0080] S2, a precursor aqueous solution with a formulation of 0.6 mol / L nickel nitrate, 0.2 mol / L ferrous chloride, and 2 mol / L urea was prepared, and the aqueous solution was mixed with an equal volume of ethanol to form a uniform functional inorganic material mother liquor (functional inorganic material-NiFe LDH);

[0081] S3, the PTFE porous membrane filled with ethanol after swelling in step S1 was placed in 20 mL of the functional inorganic material mother liquor prepared in step S2 and was allowed to stand for 2 h, and then was subjected to hydrothermal treatment at 90°C for 8 h. The PTFE porous membrane with completed hydrothermal growth was removed, and was washed with deionized water and ethanol, respectively, and was dried at 60°C for 8 h, to finally obtain an organic-inorganic composite separator.

[0082] Comparative Example 1

[0083] A circular PPS woven fabric with a diameter of 3 cm was taken without any process treatment, and was used as a raw membrane control.

[0084] Comparative Example 2

[0085] Compared with Example 1, most of the steps were the same, except that step S1 was omitted, and the PPS woven fabric was not subjected to swelling.

[0086] Comparative Example 3

[0087] A method for preparing a water electrolysis composite separator, compared with Example 1, a non-functional inorganic material mother liquor was used, including the following steps:

[0088] S1, a circular PPS woven fabric with a diameter of 3 cm was placed in 60 mL of N-methyl pyrrolidone, and was heated at 80°C for 180 h to obtain a swollen PPS woven fabric;

[0089] S2, 6.25 mmol of ZrOCl2·8H2O was dissolved in 10 mL of deionized water and 9 mL of ethanol, and was placed on a constant-temperature magnetic stirrer at 85°C, and was stirred uniformly, and 1 mL of ammonia water was added, and was mixed to form a uniform non-functional inorganic material mother liquor (non-functional inorganic material ZrO2);

[0090] S3, the swollen PPS woven fabric in step S1 was placed in 60 mL of ethanol, and was ultrasonically treated for 1 h, and then fresh ethanol 60 mL was replaced, and ultrasonic treatment was repeated for 3 times, and the PPS woven fabric after ultrasonic treatment was placed in 20 mL of the non-functional inorganic material mother liquor prepared in step S2 and was allowed to stand for 5 h, and then was subjected to hydrothermal treatment at 150°C for 24 h. The PPS woven fabric with completed hydrothermal growth was removed, and was washed with deionized water and ethanol, respectively, and was dried at 60°C for 8 h, to finally obtain an organic-inorganic composite separator.

[0091] Comparative Example 4

[0092] A preparation method of a water electrolysis composite diaphragm, compared with example 1, adopts a non-in-situ growth mode (dip coating), comprising the following steps:

[0093] S1, place a circular PPS woven fabric with a diameter of 3 cm in 60 mL of N-methyl pyrrolidone and heat at 80°C for 180 h to obtain a swollen PPS woven fabric;

[0094] S2, prepare an aqueous solution with a solute of 0.06 mol / L nickel nitrate, 0.03 mol / L iron nitrate, 0.2 mol / L formamide, and 0.5 mol / L sodium hydroxide, stir, centrifugal filter, and ball mill to obtain NiFe LDH with a particle size of 200 nm. Take 6 g of NiFe LDH and add it to a solution composed of 30 mL of ethanol and 30 mL of water, and mix and stir uniformly.

[0095] S3, immerse the swollen PPS woven fabric of step S1 in 60 mL of the solution prepared in step S2, stand for 5 min, pull out, immerse again, stand, pull out, then take out the immersed PPS woven fabric, and dry at 80°C for 8 h to finally obtain an organic-inorganic composite diaphragm.

[0096] The composite diaphragm prepared in example 1 is characterized, Figure 2 The characterization diagram of the composite diaphragm shown in example 1 is (a) surface morphology-1 mm (microscope shooting, representing macroscopic morphology), (b) surface morphology-200 nm (SEM shooting, representing microscopic morphology), (c) cross-sectional morphology-10 μm, (d-g) cross-sectional morphology and corresponding Ni, Fe, O element distribution diagram. From Figure 2 It can be seen from the above that the grown hydrophilic inorganic matter can completely cover the surface of the organic polymer matrix (2a), and uniformly wrap the fiber filaments of the matrix (2c), the inorganic matter is in a two-dimensional sheet shape (2b), and is inserted into the polymer matrix (2d-g), which reflects the orderliness and firmness of the growth of the inorganic matter in the organic polymer matrix.

[0097] The firmness of the diaphragms prepared in examples 1-5 and comparative examples 1-4 is tested, the diaphragm is subjected to 40KHz high frequency oscillation treatment for 60 min, the mass of the diaphragm during this period is weighed, and the powder loss (inorganic matter falling off) is reflected by the mass loss rate of the diaphragm. Figure 3 (a) lists the swelling rates of each diaphragm in the preparation process, Figure 3(b) the mass loss rate of the corresponding membrane when subjected to high frequency oscillation. As can be seen from the figure, the composite membranes prepared by using Examples 1-5 and Comparative Example 3 have a mass loss rate of less than 10% when subjected to high frequency ultrasonic oscillation, and the mass loss mainly occurs in the first 20 minutes of ultrasonic oscillation, and then gradually stabilizes. However, the composite membranes prepared by using Comparative Examples 2 (non-swelling) and 4 (non-in-situ grown inorganic matter) have a mass loss rate of more than 50% when subjected to high frequency ultrasonic oscillation. Further observation of the morphology change of the composite membrane before and after the firmness test, Figure 3 (c) Comparative Example 2 - before testing, (d) Example 1 - before testing, (e) Comparative Example 2 - after testing, (f) Example 1 - after testing, as can be seen from the figure, the composite membrane prepared by using Example 1 has no obvious change in surface after being subjected to high frequency ultrasonic oscillation, while the composite membrane prepared by using Comparative Example 2 only has a small amount of inorganic matter remaining after being subjected to high frequency ultrasonic oscillation. This shows that the swelling treatment of the matrix and the in-situ growth of the inorganic matter significantly improve the firmness of the composite membrane.

[0098] The surface resistance of the membranes prepared by using Examples 1-4 and Comparative Examples 1-3 was tested. Referring to the standard SJ / T10171.5-91, the electrochemical impedance spectroscopy test method (frequency 0.1 Hz-1 M Hz) was used to test the impedance of the membranes in 30wt% KOH aqueous solution at 80°C, and the surface resistance of the membranes was calculated Figure 4 The surface resistance of the composite membranes prepared by using Examples 1-4 and Comparative Examples 2-3 was 0.1, 0.15, 0.12, 0.18, 0.24, 0.3 Ω·cm 2 , respectively. 2 The surface resistance of the composite membranes prepared by using Examples 1-4 and Comparative Examples 2-3 was lower than that of the commercially available membrane, and the surface resistance of the composite membranes prepared by using Examples 1-4 was lower than that of the composite membranes prepared by using Comparative Examples 2-3, among which the composite membrane prepared by using Example 1 had the lowest surface resistance. This shows that the swelling of the matrix and the addition of functional inorganic matter can significantly reduce the surface resistance of the membrane.

[0099] The linear voltammetry test was used to test the electrolysis performance of the membranes prepared by using Examples 1-4 and Comparative Examples 1-3. The test conditions were as follows: nickel mesh as the working electrode, 30wt% KOH aqueous solution as the electrolyte solution, and the electrolyte temperature was 80°C. The test results are shown in Figure 5The electrolysis performance of each composite separator and the original separator is ranked from high to low as follows: Example 1 > Example 2 > Example 4 > Example 3 > Comparative Example 2 > Comparative Example 3 > the original separator. The electrolysis performance of the composite separator prepared by using Example 1 is outstanding after slotting, with a voltage of only 1.65 V at a low current density of 500 mA / cm2, and a maximum current density of 2000 mA / cm2 at a voltage of no more than 2 V, which is significantly better than the original separator and the composite separator which is not subjected to swelling treatment and is directly compounded. It is shown that the swelling treatment and in-situ compounding of the functional inorganic matter greatly enhances the electrolysis performance of the separator.

[0100] The electrolysis stability of the composite separators prepared by using Example 1 and Comparative Example 2 is tested. The test conditions are as follows: a nickel mesh is used as the working electrode, a 30wt% KOH aqueous solution is used as the electrolyte solution, the electrolyte temperature is 80°C, the current density is 500 mA / cm2, and the test is divided into two steps. 1) Off-slot test: the composite separators prepared by using Example 1 and Comparative Example 2 are soaked in a 30wt% KOH aqueous solution, the solution temperature is 80°C, and the soaking time is more than 1500 hours. The electrolysis performance of the separators before and after soaking is tested, and the morphology of the separators after soaking is characterized, and the test results are shown in Figs. (a-c). Figure 6 2) On-slot test: the composite separator prepared by using Example 1 is used to electrolyze water, a constant current of 500 mA / cm2 is applied, and the electrolysis time is more than 600 hours. The voltage change of the electrolysis tank is monitored and recorded, and the test results are shown in Fig. (d). Figure 6 It can be seen from the figures that the composite separator prepared by using Example 1 has no obvious change on the surface (a) and only slight decay in electrolysis performance (c) after being subjected to long-term hot alkali erosion, while the composite separator prepared by using Comparative Example 2 only has a small amount of inorganic matter remaining (b) and a significant decrease in electrolysis performance (c) after being subjected to long-term hot alkali erosion. Further, the composite separator prepared by using Example 1 works for 600 h at a current density of 500 mA / cm2, and the electrolysis performance does not decay (d), which exhibits excellent electrolysis stability. 2 The electrolysis performance of each composite separator and the original separator is ranked from high to low as follows: Example 1 > Example 2 > Example 4 > Example 3 > Comparative Example 2 > Comparative Example 3 > the original separator. The electrolysis performance of the composite separator prepared by using Example 1 is outstanding after slotting, with a voltage of only 1.65 V at a low current density of 500 mA / cm2, and a maximum current density of 2000 mA / cm2 at a voltage of no more than 2 V, which is significantly better than the original separator and the composite separator which is not subjected to swelling treatment and is directly compounded. It is shown that the swelling treatment and in-situ compounding of the functional inorganic matter greatly enhances the electrolysis performance of the separator.

[0101] Although the present application has been described in detail by the general description, the specific embodiments and the experiments above, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, are within the scope of the present application.

Claims

1. A method for preparing a high performance alkaline water electrolysis composite separator, characterized by, The method comprises the following steps: S1, soaking the organic polymer matrix in a swelling solvent to obtain a swollen organic polymer matrix; S2, mixing the swelling solvent and a precursor aqueous solution to obtain a functional inorganic material mother liquor, wherein the swelling solvent and the precursor aqueous solution are mutually soluble; S3, adding the swollen organic polymer matrix in step S1 into the functional inorganic material mother liquor in step S2 and standing, in-situ growth reaction, washing and drying to obtain an organic-inorganic composite diaphragm, i.e. a high-performance alkaline water electrolysis composite diaphragm, and the process is completed. In step S2, the precursor aqueous solution is a mixed solution containing divalent metal cations, trivalent metal cations, and a basic substance, wherein the divalent metal cations are selected from Mg 2+ , Zn 2+ , Co 2+ , Ni 2+ , Fe 2+ ; the trivalent metal cations are selected from Al 3+ , Fe 3+ ; and the basic substance is selected from sodium hydroxide, potassium hydroxide, urea, ammonia, and hexamethylenetetramine.

2. The method for preparing a high-performance alkaline water electrolysis composite membrane according to claim 1, characterized in that, In step S1, the organic polymer matrix is selected from polyphenylene sulfide, polyethylene, polypropylene, polytetrafluoroethylene, polyether ether ketone, and polyimide, and the organic polymer matrix is in the form of a porous membrane, a non-woven fabric, a woven fabric, or a composite fabric. The swelling solvent is selected from N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and acetonitrile. The volume ratio of the organic polymer matrix to the swelling solvent is 1:20-200.

3. The method for preparing a high-performance alkaline water electrolysis composite membrane according to claim 1, characterized in that, In step S1, the organic polymer matrix is swelled at 25-100℃.

4. The method of claim 1, wherein the high performance alkaline water electrolysis composite separator is prepared by the steps of: The concentration of the divalent metal cation is 0.02-1 mol / L, the concentration of the trivalent metal cation is 0.02-1 mol / L, and the concentration of the alkaline substance is 0.1-5 mol / L.

5. The method for preparing a high-performance alkaline water electrolysis composite membrane according to claim 1, characterized in that, In step S2, the volume ratio of the swelling solvent to the precursor aqueous solution is 1:0.3-3. In step S3, the volume ratio of the swollen organic polymer matrix to the functional inorganic material mother liquor is 1:1-50. The in-situ growth reaction comprises a co-precipitation method and a hot solvent method.

6. A method for preparing a high performance alkaline water electrolysis composite separator, characterized by, The preparation method comprises the following steps: S1, soaking the organic polymer matrix in a swelling solvent to obtain a swollen organic polymer matrix, and replacing the swelling solvent with a medium solvent to obtain a replaced organic polymer matrix; S2, mixing the medium solvent and a precursor aqueous solution to obtain a functional inorganic material mother liquor, wherein the swelling solvent and the precursor aqueous solution are not mutually soluble, and the medium solvent is a solvent that is miscible with both the precursor aqueous solution and the swelling solvent; S3, adding the replaced organic polymer matrix in step S1 into the functional inorganic material mother liquor in step S2 and standing, in-situ growth reaction, washing and drying to obtain an organic-inorganic composite diaphragm, i.e. a high-performance alkaline water electrolysis composite diaphragm, and the process is completed.

7. The method of claim 6, wherein the high performance alkaline water electrolysis composite separator is prepared by the steps of: In step S1, the medium solvent is selected from ethanol, acetone, and tetrahydrofuran. In step S1, the swelling solvent is selected from toluene or n-hexane. In step S1, the volume ratio of the swollen organic polymer matrix to the medium solvent is 1:50-200. In step S2, the volume ratio of the precursor aqueous solution to the medium solvent is 1:0.3-3. In step S3, the volume ratio of the replaced organic polymer matrix to the functional inorganic material mother liquor is 1:1-50.

8. A high performance alkaline water electrolysis composite separator, characterized in that, The high-performance alkaline water electrolysis composite diaphragm is prepared by using the preparation method in any one of claims 1-7.

9. Application of the high-performance alkaline water electrolysis composite diaphragm in claim 8 in the field of alkaline water electrolysis hydrogen production.

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