Preparation method of modified diaphragm for high-temperature-resistant alkaline electrolyzer

Abstract

The application discloses a preparation method of a high-temperature-resistant alkaline electrolytic cell modified diaphragm, which comprises the following steps: melting polyphenylene sulfide material to prepare fibers, cutting the fibers after surface treatment to obtain short fibers with two lengths, mixing the short fibers with a predetermined ratio, dispersing, beating, defibrating, papermaking and hot pressing to obtain a fiber paper-based diaphragm. A polymer skeleton coating is coated on the surface of the diaphragm. The diaphragm obtained by the application has good thermal stability, chemical stability and mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and engineering technology, specifically relating to a method for preparing a high-temperature resistant alkaline electrolytic cell modified diaphragm. Background Technology

[0002] Alkaline water electrolysis is currently the most mature water electrolysis hydrogen production technology. Its advantages of simple operation and high efficiency have led to its widespread industrial application. During electrolysis, oxygen is produced at the anode and hydrogen is produced at the cathode. A diaphragm prevents the mixing of hydrogen and oxygen. Currently, asbestos cloth is mainly used for the diaphragm. However, the swelling and chemical instability of asbestos diaphragms cause severe swelling defects in pure asbestos diaphragms under specific operating environments, especially under high current loads. This reduces the mechanical strength of the diaphragm and shortens its service life.

[0003] In alkaline water electrolysis hydrogen production equipment, the electrolyzer is the core component. The electrolyzer consists of a unit chamber composed of an electrode frame, electrode plates, cathode, anode, diaphragm, and gasket seals, with several unit chambers connected in series to form a multi-chamber structure. The diaphragm serves two main functions: first, as an insulating layer, it separates the anode and cathode to prevent short circuits; second, it is hydrophilic and gas-repellent, allowing alkaline solution to pass through while simultaneously separating hydrogen and oxygen to prevent cross-contamination. Currently, widely used diaphragms are mainly made of organic fiber fabrics, most of which are insulating materials, ensuring their function as an insulating layer. Therefore, in practical use, the diaphragm's primary function is hydrophilicity and gas repellency. This invention provides a method for preparing a modified diaphragm for a high-temperature alkaline electrolyzer. Summary of the Invention

[0004] In the existing technology, the way to improve the high temperature resistance of the diaphragm is generally to coat the diaphragm surface with a high temperature resistant material, such as a porous PVDF coating. However, after coating, the liquid absorption capacity of the diaphragm will decrease, as well as coating bonding problems and uneven coating distribution problems.

[0005] To address the aforementioned issues, the inventors proposed a method that improves the spinnability of fibers by mixing high-viscosity polyphenylene sulfide with low-viscosity polyphenylene sulfide, while ensuring fiber strength through surface treatment with polar organic vapors.

[0006] By combining polyphenylene sulfide composite fibers of different lengths, it is easy to control the porosity, pore size and thickness of the battery separator. At the same time, the number of polar functional groups on the fiber surface is increased by vacuum ionization treatment, ensuring that the electrolyte absorption rate does not decrease after the PVDF membrane is applied.

[0007] One objective of this invention is to provide a method for preparing a high-temperature alkaline electrolytic cell modified diaphragm, which includes melting polyphenylene sulfide material to prepare fibers, surface treating and then cutting them to obtain two short fibers of different lengths. These fibers are then mixed in a predetermined ratio, dispersed, pulped, slurred, paper-made, and hot-pressed to obtain a fiber-paper-based diaphragm. A polymer backbone coating is then applied to the diaphragm surface. The diaphragm obtained by this invention exhibits good thermal stability, chemical stability, and mechanical properties.

[0008] The specific plan is as follows:

[0009] This invention provides a method for preparing a high-temperature alkaline electrolytic cell modified diaphragm, characterized by comprising:

[0010] 1) The first polyphenylene sulfide and the second polyphenylene sulfide are mixed and melt-spun to obtain fibers; wherein the melt index of the first polyphenylene sulfide is 20-25 g / min and the melt index of the second polyphenylene sulfide is 120-150 g / min.

[0011] 2) Treat the fibers from step 1) in tetrahydrofuran vapor and dry them;

[0012] 3) Cut the fibers to obtain a first fiber with a length of 2-4 mm and a second fiber with a length of 12-15 mm. Then, put the first and second fibers into deionized water to disperse, pulp, decompose, paper, and hot press to obtain the diaphragm.

[0013] 4) The diaphragm from step 3 was subjected to vacuum plasma surface treatment in a mixed atmosphere of oxygen and argon.

[0014] 5) After mixing and dispersing PVDF and NMP, a PVDF solution is obtained; the PVDF solution and polyglycerol are mixed and coated on both sides of the membrane obtained in step 4, and then the membrane is pore-forming, extracted, and dried to obtain the high-temperature alkaline electrolytic cell modified membrane.

[0015] Furthermore, the first polyphenylene sulfide and the second polyphenylene sulfide are mixed at a mass ratio of 100:15-25, and then melt-spun to obtain fibers with a fineness of 2-3 μm.

[0016] Furthermore, in step 2), the steam pressure is 10-20 kPa, the processing time is 20-30 min, the drying temperature is 60-80℃, and the drying time is 12-24 h.

[0017] Furthermore, in step 3), the fibers are cut to obtain a first fiber with a length of 2-4 mm and a second fiber with a length of 12-15 mm. Then, the first fiber and the second fiber are added to deionized water at a mass ratio of 1-3:10 for dispersion, pulping, papermaking, and hot pressing to obtain the diaphragm. The pulping concentration is 3-5 wt%, the papermaking wire density is 0.5-0.8%, the hot pressing pressure is 15-20 MPa, and the hot pressing temperature is 200-250℃.

[0018] Furthermore, in step 4, the oxygen accounts for 10-15% of the mixed gas by volume, the vacuum chamber pressure is 30-60 Pa, and the processing intensity is 100-200 KW·s / m. 2 .

[0019] Further, in step 5, PVDF and NMP are mixed and dispersed to obtain a PVDF solution with a mass fraction of 5-10 wt%; the PVDF solution and polyglycerol are mixed at a mass ratio of 10:2-3, and then coated on both sides of the membrane obtained in step 4. Pores are created using an aqueous solution containing 0.1 wt% polyoxyethylene alkylamine and 5 wt% NMP, followed by extraction and drying to obtain the high-temperature alkaline electrolytic cell modified membrane.

[0020] A high-temperature resistant alkaline electrolytic cell modified diaphragm, wherein the diaphragm is prepared by the preparation method described above.

[0021] Application of a high-temperature resistant alkaline electrolyzer modified diaphragm, the diaphragm being used for electrolyzing alkaline water.

[0022] The present invention has the following beneficial effects:

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1) The mixture of high-viscosity polyphenylene sulfide and low-viscosity polyphenylene sulfide improves the spinnability of the fibers and enhances the bonding force between fibers during hot pressing, thereby improving the mechanical properties of the membrane.

[0025] Meanwhile, the addition of low-viscosity polyphenylene sulfide will reduce the fiber strength after heat aging. In order to ensure the fiber strength, surface treatment with polar organic vapor is used to ensure the high temperature resistance of the membrane.

[0026] 2) By combining polyphenylene sulfide composite fibers of different lengths, it is beneficial to control the porosity, pore size and thickness of the battery separator.

[0027] 3) To ensure that the electrolyte absorption rate does not decrease after the PVDF membrane is applied, the surface of the base membrane is subjected to vacuum ionization treatment. In an oxygen-containing atmosphere, ionization treatment can increase the number of polar functional groups on the fiber surface, thereby improving the hydrophilicity of the membrane and increasing the electrolyte retention rate. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments. However, the scope of protection of the present invention is not limited to the following embodiments. Any non-essential adjustments and modifications made to the present invention based on the above description shall still fall within the scope of protection of the present invention.

[0029] Example 1

[0030] 1) The first polyphenylene sulfide and the second polyphenylene sulfide are mixed at a mass ratio of 100:15 and melt-spun to obtain fibers with a fineness of 2μm; wherein the melt index of the first polyphenylene sulfide is 20g / min and the melt index of the second polyphenylene sulfide is 120g / min.

[0031] 2) Place the fibers from step 1) in tetrahydrofuran vapor; the vapor pressure is 10 kPa, the treatment time is 20 min, and after treatment, dry at 60℃ for 24 h.

[0032] 3) Cut the fibers to obtain a first fiber with a length of 2 mm and a second fiber with a length of 12 mm. Then, add the first fiber and the second fiber into deionized water at a mass ratio of 1:10 to disperse, pulp, decompose, form paper, and hot press to obtain the diaphragm. The pulp concentration is 3 wt%, the paper forming online concentration is 0.5%, the hot pressing pressure is 15 MPa, and the hot pressing temperature is 200℃.

[0033] 4) The diaphragm from step 3 is subjected to vacuum plasma surface treatment in a mixed atmosphere of oxygen and argon, wherein the oxygen accounts for 10% by volume of the mixed gas, the vacuum chamber pressure is 30 Pa, and the treatment intensity is 100 KW·s / m. 2 ;

[0034] 5) After mixing and dispersing PVDF and NMP, a PVDF solution with a mass fraction of 5 wt% is obtained; the PVDF solution and polyglycerol are mixed at a mass ratio of 10:2, and then coated on both sides of the membrane obtained in step 4. Pores are created using an aqueous solution containing 0.1 wt% polyoxyethylene alkylamine and 5 wt% NMP. The pore-forming pool temperature is 50℃ and the pore-forming time is 15s; then it is introduced into an extraction pool at a temperature of 50℃ and pH=8 for 2min; the membrane after pore-forming and extraction is dried to obtain the membrane.

[0035] Example 2

[0036] 1) The first polyphenylene sulfide and the second polyphenylene sulfide are mixed at a mass ratio of 100:25 and melt-spun to obtain fibers with a fineness of 2μm; wherein the melt index of the first polyphenylene sulfide is 25g / min and the melt index of the second polyphenylene sulfide is 150g / min.

[0037] 2) Place the fibers from step 1) in tetrahydrofuran vapor; the vapor pressure is 20 kPa, the treatment time is 30 min, and after treatment, dry at 80℃ for 12-24 h.

[0038] 3) Cut the fibers to obtain a first fiber with a length of 4 mm and a second fiber with a length of 15 mm. Then, add the first fiber and the second fiber into deionized water at a mass ratio of 3:10 to disperse, pulp, decompose, form paper, and hot press to obtain the diaphragm. The pulp concentration is 5 wt%, the paper forming wire density is 0.8%, the hot pressing pressure is 20 MPa, and the hot pressing temperature is 250℃.

[0039] 4) The diaphragm from step 3 is subjected to vacuum plasma surface treatment in a mixed atmosphere of oxygen and argon, wherein the oxygen accounts for 15% by volume of the mixed gas, the vacuum chamber pressure is 60 Pa, and the treatment intensity is 200 KW·s / m. 2 ;

[0040] 5) After mixing and dispersing PVDF and NMP, a PVDF solution with a mass fraction of 10 wt% is obtained; the PVDF solution and polyglycerol are mixed at a mass ratio of 10:3, and then coated on both sides of the membrane obtained in step 4. Pores are created using an aqueous solution containing 0.1 wt% polyoxyethylene alkylamine and 5 wt% NMP. The pore-forming pool temperature is 50℃ and the pore-forming time is 15s. Then, the membrane is introduced into an extraction pool at a temperature of 50℃ and pH=8 for 2min. The membrane after pore-forming and extraction is dried to obtain the membrane.

[0041] Example 3

[0042] 1) The first polyphenylene sulfide and the second polyphenylene sulfide are mixed at a mass ratio of 100:20 and melt-spun to obtain fibers with a fineness of 2μm; wherein the melt index of the first polyphenylene sulfide is 22g / min and the melt index of the second polyphenylene sulfide is 130g / min.

[0043] 2) Place the fibers from step 1) in tetrahydrofuran vapor; the vapor pressure is 15 kPa, the treatment time is 25 min, and after treatment, dry at 70℃ for 18 h.

[0044] 3) Cut the fibers to obtain a first fiber with a length of 3 mm and a second fiber with a length of 12 mm. Then, add the first fiber and the second fiber into deionized water at a mass ratio of 2:10 to disperse, pulp, decompose, form paper, and hot press to obtain the diaphragm. The pulp concentration is 4 wt%, the paper forming online concentration is 0.6%, the hot pressing pressure is 20 MPa, and the hot pressing temperature is 220℃.

[0045] 4) The diaphragm from step 3 was subjected to vacuum plasma surface treatment in a mixed atmosphere of oxygen and argon, wherein oxygen accounted for 12% of the mixed gas volume, the vacuum chamber pressure was 40 Pa, and the treatment intensity was 150 KW·s / m. 2 ;

[0046] 5) After mixing and dispersing PVDF and NMP, a PVDF solution with a mass fraction of 8 wt% is obtained; the PVDF solution and polyglycerol are mixed at a mass ratio of 10:3, and then coated on both sides of the membrane obtained in step 4. Pores are created using an aqueous solution containing 0.1 wt% polyoxyethylene alkylamine and 5 wt% NMP. The pore-forming pool temperature is 50℃ and the pore-forming time is 15s; then it is introduced into an extraction pool at a temperature of 50℃ and pH=8 for 2min; the membrane after pore-forming and extraction is dried to obtain the membrane.

[0047] Example 4

[0048] 1) The first polyphenylene sulfide and the second polyphenylene sulfide are mixed at a mass ratio of 100:25 and melt-spun to obtain fibers with a fineness of 2μm; wherein the melt index of the first polyphenylene sulfide is 20g / min and the melt index of the second polyphenylene sulfide is 150g / min.

[0049] 2) Place the fibers from step 1) in tetrahydrofuran vapor; the vapor pressure is 10 kPa, the treatment time is 30 min, and after treatment, dry at 60-80℃ for 12 h.

[0050] 3) Cut the fibers to obtain a first fiber with a length of 4 mm and a second fiber with a length of 15 mm. Then, add the first fiber and the second fiber into deionized water at a mass ratio of 3:10 to disperse, pulp, decompose, form paper, and hot press to obtain the diaphragm. The pulp concentration is 3 wt%, the paper forming online concentration is 0.8%, the hot pressing pressure is 15 MPa, and the hot pressing temperature is 250℃.

[0051] 4) The diaphragm from step 3 is subjected to vacuum plasma surface treatment in a mixed atmosphere of oxygen and argon, wherein the oxygen accounts for 10% by volume of the mixed gas, the vacuum chamber pressure is 60 Pa, and the treatment intensity is 200 KW·s / m. 2 ;

[0052] 5) After mixing and dispersing PVDF and NMP, a PVDF solution with a mass fraction of 5 wt% is obtained; the PVDF solution and polyglycerol are mixed at a mass ratio of 10:3, and then coated on both sides of the membrane obtained in step 4. Pores are created using an aqueous solution containing 0.1 wt% polyoxyethylene alkylamine and 5 wt% NMP. The pore-forming pool temperature is 50℃ and the pore-forming time is 15s; then it is introduced into an extraction pool at a temperature of 50℃ and pH=8 for 2min; the membrane after pore-forming and extraction is dried to obtain the membrane.

[0053] Comparative Example 1

[0054] 1) The first polyphenylene sulfide and the melt spinning process yield fibers with a fineness of 2 μm; wherein the melt index of the first polyphenylene sulfide is 20 g / min;

[0055] 2) Cut the fibers to obtain a first fiber with a length of 2 mm and a second fiber with a length of 12 mm. Then, add the first fiber and the second fiber into deionized water at a mass ratio of 1:10 to disperse, pulp, decompose, form paper, and hot press to obtain the diaphragm. The pulp concentration is 3 wt%, the paper forming wire density is 0.5%, the hot pressing pressure is 15 MPa, and the hot pressing temperature is 200℃.

[0056] 4) The diaphragm from step 3 is subjected to vacuum plasma surface treatment in a mixed atmosphere of oxygen and argon, wherein the oxygen accounts for 10% by volume of the mixed gas, the vacuum chamber pressure is 30 Pa, and the treatment intensity is 100 KW·s / m. 2 ;

[0057] 5) After mixing and dispersing PVDF and NMP, a PVDF solution with a mass fraction of 5 wt% is obtained; the PVDF solution and polyglycerol are mixed at a mass ratio of 10:2, and then coated on both sides of the membrane obtained in step 4. Pores are created using an aqueous solution containing 0.1 wt% polyoxyethylene alkylamine and 5 wt% NMP. The pore-forming pool temperature is 50℃ and the pore-forming time is 15s; then it is introduced into an extraction pool at a temperature of 50℃ and pH=8 for 2min; the membrane after pore-forming and extraction is dried to obtain the membrane.

[0058] Comparative Example 2

[0059] 1) The first polyphenylene sulfide and the second polyphenylene sulfide are mixed at a mass ratio of 100:15 and melt-spun to obtain fibers with a fineness of 2μm; wherein the melt index of the first polyphenylene sulfide is 20g / min and the melt index of the second polyphenylene sulfide is 120g / min.

[0060] 2) Cut the fibers to obtain a first fiber with a length of 2 mm and a second fiber with a length of 12 mm. Then, add the first fiber and the second fiber into deionized water at a mass ratio of 1:10 to disperse, pulp, decompose, form paper, and hot press to obtain the diaphragm. The pulp concentration is 3 wt%, the paper forming wire density is 0.5%, the hot pressing pressure is 15 MPa, and the hot pressing temperature is 200℃.

[0061] 3) The diaphragm from step 2 was subjected to vacuum plasma surface treatment in a mixed atmosphere of oxygen and argon, wherein the oxygen content in the mixed gas was 10% by volume, the vacuum chamber pressure was 30 Pa, and the treatment intensity was 100 KW·s / m. 2 ;

[0062] 4) After mixing and dispersing PVDF and NMP, a PVDF solution with a mass fraction of 5 wt% is obtained; the PVDF solution and polyglycerol are mixed at a mass ratio of 10:2, and then coated on both sides of the membrane obtained in step 4. Pores are created using an aqueous solution containing 0.1 wt% polyoxyethylene alkylamine and 5 wt% NMP. The pore-forming pool temperature is 50℃ and the pore-forming time is 15s; then it is introduced into an extraction pool at a temperature of 50℃ and pH=8 for 2min; the membrane after pore-forming and extraction is dried to obtain the membrane.

[0063] Comparative Example 3

[0064] 1) The first polyphenylene sulfide and the second polyphenylene sulfide are mixed at a mass ratio of 100:15 and melt-spun to obtain fibers with a fineness of 2μm; wherein the melt index of the first polyphenylene sulfide is 20g / min and the melt index of the second polyphenylene sulfide is 120g / min.

[0065] 2) Place the fibers from step 1) in tetrahydrofuran vapor; the vapor pressure is 10 kPa, the treatment time is 20 min, and after treatment, dry at 60℃ for 24 h.

[0066] 3) Cut the fibers to obtain a first fiber with a length of 2 mm and a second fiber with a length of 12 mm. Then, add the first fiber and the second fiber into deionized water at a mass ratio of 1:10 to disperse, pulp, decompose, form paper, and hot press to obtain the diaphragm. The pulp concentration is 3 wt%, the paper forming online concentration is 0.5%, the hot pressing pressure is 15 MPa, and the hot pressing temperature is 200℃.

[0067] 4) After mixing and dispersing PVDF and NMP, a PVDF solution with a mass fraction of 5 wt% is obtained; the PVDF solution and polyglycerol are mixed at a mass ratio of 10:2, and then coated on both sides of the membrane obtained in step 4. Pores are created using an aqueous solution containing 0.1 wt% polyoxyethylene alkylamine and 5 wt% NMP. The pore-forming pool temperature is 50℃ and the pore-forming time is 15s; then it is introduced into an extraction pool at a temperature of 50℃ and pH=8 for 2min; the membrane after pore-forming and extraction is dried to obtain the membrane.

[0068] Comparative Example 4

[0069] 1) The first polyphenylene sulfide and the second polyphenylene sulfide are mixed at a mass ratio of 100:15 and melt-spun to obtain fibers with a fineness of 2μm; wherein the melt index of the first polyphenylene sulfide is 20g / min and the melt index of the second polyphenylene sulfide is 120g / min.

[0070] 2) Place the fibers from step 1) in tetrahydrofuran vapor; the vapor pressure is 10 kPa, the treatment time is 20 min, and after treatment, dry at 60℃ for 24 h.

[0071] 3) Cut the fibers to obtain a first fiber with a length of 2 mm and a second fiber with a length of 12 mm. Then, add the first fiber and the second fiber into deionized water at a mass ratio of 1:10 to disperse, pulp, decompose, form paper, and hot press to obtain the diaphragm. The pulp concentration is 3 wt%, the paper forming online concentration is 0.5%, the hot pressing pressure is 15 MPa, and the hot pressing temperature is 200℃.

[0072] 4) The diaphragm from step 3 was subjected to vacuum plasma surface treatment in an argon atmosphere. The vacuum chamber pressure was 30 Pa, and the treatment intensity was 100 KW·s / m. 2 ;

[0073] 5) After mixing and dispersing PVDF and NMP, a PVDF solution with a mass fraction of 5 wt% is obtained; the PVDF solution and polyglycerol are mixed at a mass ratio of 10:2, and then coated on both sides of the membrane obtained in step 4. Pores are created using an aqueous solution containing 0.1 wt% polyoxyethylene alkylamine and 5 wt% NMP. The pore-forming pool temperature is 50℃ and the pore-forming time is 15s; then it is introduced into an extraction pool at a temperature of 50℃ and pH=8 for 2min; the membrane after pore-forming and extraction is dried to obtain the membrane.

[0074] Comparative Example 5

[0075] 1) The first polyphenylene sulfide and the second polyphenylene sulfide are mixed at a mass ratio of 100:15 and melt-spun to obtain fibers with a fineness of 2μm; wherein the melt index of the first polyphenylene sulfide is 20g / min and the melt index of the second polyphenylene sulfide is 120g / min.

[0076] 2) Place the fibers from step 1) in tetrahydrofuran vapor; the vapor pressure is 10 kPa, the treatment time is 20 min, and after treatment, dry at 60℃ for 24 h.

[0077] 3) Cut the fibers to obtain fibers with a length of 4mm, then put them into deionized water for dispersion, pulping, descaling, papermaking, and hot pressing to obtain the diaphragm; the pulping concentration is 3wt%, the papermaking on-line concentration is 0.5%, the hot pressing pressure is 15Mpa, and the hot pressing temperature is 200℃.

[0078] 4) The diaphragm from step 3 is subjected to vacuum plasma surface treatment in a mixed atmosphere of oxygen and argon, wherein the oxygen accounts for 10% by volume of the mixed gas, the vacuum chamber pressure is 30 Pa, and the treatment intensity is 100 KW·s / m. 2 ;

[0079] 5) After mixing and dispersing PVDF and NMP, a PVDF solution with a mass fraction of 5 wt% is obtained; the PVDF solution and polyglycerol are mixed at a mass ratio of 10:2, and then coated on both sides of the membrane obtained in step 4. Pores are created using an aqueous solution containing 0.1 wt% polyoxyethylene alkylamine and 5 wt% NMP. The pore-forming pool temperature is 50℃ and the pore-forming time is 15s; then it is introduced into an extraction pool at a temperature of 50℃ and pH=8 for 2min; the membrane after pore-forming and extraction is dried to obtain the membrane.

[0080] Performance tests were conducted on the diaphragms of the examples and comparative examples.

[0081] In this invention, the base film thickness of the embodiments and comparative examples is 200±5μm, the coating thickness on both sides is 100±3μm, and the total thickness is 400±5μm;

[0082] 1. Porosity determination method: The porosity of the diaphragm is measured by the n-butanol immersion method: Diaphragm porosity = mass difference of the diaphragm before and after immersion in n-butanol / (n-butanol density * diaphragm volume).

[0083] 2. Pore size testing method: The pore size of the diaphragm was tested using a Porolux 1000 gas-liquid interface pore size tester from Promet GmbH, Belgium.

[0084] 3. The tensile strength shall conform to GB / T3923.1-2013, and the liquid absorption rate shall conform to the national electronic industry standard SJ-T10171.

[0085] 4. Place these electrolytic membranes in a 30wt% KOH solution and heat to 80℃ for 300h. Calculate the fracture strength loss rate of the membranes after heat aging using the following formula: Strength loss rate = Difference in fracture strength before and after heat treatment / Fracture strength before heat treatment.

[0086] Table 1

[0087]

[0088]

[0089] Tests and Results

[0090] Mixing high-viscosity and low-viscosity polyphenylene sulfide (PPS) improves the tensile strength of the membrane, but increases the strength loss rate. Surface treatment with polar organic vapors ensures the membrane's heat resistance. Vacuum ionization treatment of the base membrane surface in an oxygen-containing atmosphere increases the number of polar functional groups on the fiber surface, thereby improving the membrane's hydrophilicity and electrolyte retention rate. Combining fibers of different lengths in membrane fabrication enhances the membrane's mechanical strength.

[0091] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as a limitation of the present invention.

Claims

1. A method for preparing a high-temperature resistant alkaline electrolytic cell modified diaphragm, characterized in that, include: 1) Mix the first polyphenylene sulfide and the second polyphenylene sulfide, and obtain the fiber by melt spinning; The first polyphenylene sulfide has a melt index of 20-25 g / min, and the second polyphenylene sulfide has a melt index of 120-150 g / min. 2) Treat the fibers from step 1) in tetrahydrofuran vapor and dry them; 3) Cut the fibers to obtain a first fiber with a length of 2-4 mm and a second fiber with a length of 12-15 mm. Then, put the first and second fibers into deionized water to disperse, pulp, decompose, paper, and hot press to obtain the diaphragm. 4) The diaphragm from step 3 was subjected to vacuum plasma surface treatment in a mixed atmosphere of oxygen and argon. 5) After mixing and dispersing PVDF and NMP, a PVDF solution is obtained; the PVDF solution and polyglycerol are mixed and coated on both sides of the membrane obtained in step 4, and then the membrane is pore-forming, extracted, and dried to obtain the high-temperature alkaline electrolytic cell modified membrane.

2. The method for preparing the high-temperature resistant alkaline electrolytic cell modified diaphragm as described in claim 1, characterized in that, The first polyphenylene sulfide and the second polyphenylene sulfide are mixed at a mass ratio of 100:15-25, and then melt-spun to obtain fibers with a fineness of 2-3 μm.

3. A method for preparing a high-temperature resistant alkaline electrolytic cell modified diaphragm as described in claim 1, characterized in that: In step 2), the pressure of tetrahydrofuran vapor is 10-20 kPa, the treatment time is 20-30 min, the drying temperature is 60-80℃, and the drying time is 12-24 h.

4. The method for preparing the high-temperature resistant alkaline electrolytic cell modified diaphragm according to claim 1, characterized in that: In step 3), the fibers are cut to obtain a first fiber with a length of 2-4 mm and a second fiber with a length of 12-15 mm. Then, the first and second fibers are added to deionized water at a mass ratio of 1-3:10 for dispersion, pulping, papermaking, and hot pressing to obtain the diaphragm. The pulping concentration is 3-5 wt%, the papermaking wire density is 0.5-0.8%, the hot pressing pressure is 15-20 MPa, and the hot pressing temperature is 200-250℃.

5. The method for preparing the high-temperature resistant alkaline electrolytic cell modified diaphragm according to claim 1, characterized in that: In step 4), the oxygen accounts for 10-15% of the mixed gas by volume, the vacuum chamber pressure is 30-60 Pa, and the processing intensity is 100-200 kW·s / m³. 2 .

6. The method for preparing the high-temperature resistant alkaline electrolytic cell modified diaphragm according to claim 1, characterized in that: In step 5), PVDF and NMP are mixed and dispersed to obtain a PVDF solution with a mass fraction of 5-10 wt%. The PVDF solution and polyglycerol are mixed at a mass ratio of 10:2-3 and then coated on both sides of the membrane obtained in step 4. Pores are created using an aqueous solution containing 0.1 wt% polyoxyethylene alkylamine and 5 wt% NMP. The mixture is then extracted and dried to obtain the high-temperature alkaline electrolytic cell modified membrane.

7. A high-temperature resistant alkaline electrolytic cell modified diaphragm, characterized in that, The diaphragm is prepared using the preparation method described in any one of claims 1-6.

8. An application of the high-temperature resistant alkaline electrolyzer modified diaphragm according to claim 7, wherein the diaphragm is used for electrolyzing alkaline water.

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