A method for preparing a low-sulfonation-degree sulfonated polyether ether ketone-based composite proton exchange membrane

Abstract

This invention discloses a method for preparing a low-sulfonation degree sulfonated polyether ether ketone-based composite proton exchange membrane. The method utilizes the addition reaction of 1,3-propanesulfonyl lactone with NK-COF-41 to synthesize a sulfonic acid-rich porous organic framework, which is then mixed with SPEEK and prepared via solution casting to obtain a low-sulfonation degree SPEEK / sulfonic acid-rich porous organic framework composite proton exchange membrane. The sulfonic acid-rich porous organic framework obtained by this invention not only has a 468.6 μm... 2 g ‑1 Its high specific surface area and nearly 90% sulfonation degree provide abundant active sites for proton transfer. At the same time, its structure is stable and it hardly swells at 80℃ and 100%RH. The resulting composite proton exchange membrane has the characteristics of high proton conductivity, high ion exchange capacity and low swelling rate.

Description

Technical fields:

[0001] This invention belongs to the field of polymer materials, specifically relating to the field of proton exchange membranes for fuel cells, and is a method for preparing a low-sulfonation degree sulfonated polyether ether ketone-based composite proton exchange membrane. Background technology:

[0002] Hydrogen energy is an ideal clean energy source for the 21st century, characterized by high energy density, zero emissions, and renewability. Compared to other energy sources, it is cleaner and more efficient, and will become a major force in future development. Compared to combustion, fuel cells, with their simple and efficient electrode reaction method, can convert hydrogen and other chemical energy sources into electrical energy without cumbersome conversion processes, exhibiting a high conversion rate and representing an excellent pathway for hydrogen energy utilization. Proton exchange membrane fuel cells (PEMs) offer advantages such as high efficiency, environmental friendliness, and energy saving, showing great potential in fields such as automobiles and drones. Among these, the proton transfer performance of the polymer proton exchange membrane (PEM), a crucial component of PEMs, directly determines the performance of the entire fuel cell stack. Besides requiring high proton conductivity and excellent fuel barrier properties, PEMs must also adapt to the diverse operating environments of PEMs, including maintaining high durability, good tensile strength, dimensional stability, and chemical stability in extreme temperature, humidity, and chemical environments. Furthermore, they must be feasible to process and cost-effective. The commercial application of PEMs places extremely high demands on these performance indicators.

[0003] Sulfonated polyether ether ketone (PEE ketone) is considered a potential proton exchange membrane material by researchers due to its good heat resistance and mechanical properties. Its proton conductivity and proton exchange capacity increase with increasing sulfonation degree, but the swelling rate of PEE ketone increases and its mechanical properties decrease with further increases in sulfonation degree. Patent 202311131599.8 provides a method for preparing a composite proton exchange membrane of PEE ketone and a ketoenamine covalent organic framework material. This patent mixes PEE ketone with a first monomer of a ketoenamine covalent organic framework material, adds a second monomer to obtain a mixture of PEE ketone and the covalent organic framework, and then forms a film to obtain the composite proton exchange membrane. However, the sulfonated PEE ketone used has a high degree of sulfonation, which carries the risk of excessive swelling. Summary of the Invention:

[0004] The purpose of this invention is to address the limitations of the prior art by providing a method for preparing a low-sulfonation degree sulfonated polyether ether ketone-based composite proton exchange membrane. This method utilizes the addition reaction of 1,3-propanesulfonyl lactone with NK-COF-41 to synthesize a sulfonic acid-rich porous organic framework, which is then mixed with SPEEK and prepared via solution casting to obtain a low-sulfonation degree SPEEK / sulfonic acid-rich porous organic framework composite proton exchange membrane. The sulfonic acid-rich porous organic framework obtained by this invention not only has a 468.6 μm... 2 g -1 Its high specific surface area and nearly 90% sulfonation degree provide abundant active sites for proton transfer. At the same time, its structure is stable and it hardly swells at 80℃ and 100% RH. The resulting composite proton exchange membrane has the characteristics of high proton conductivity, high ion exchange capacity and low swelling rate.

[0005] The technical solution of this invention is as follows:

[0006] A method for preparing a low-sulfonation degree sulfonated polyether ether ketone-based composite proton exchange membrane includes the following steps:

[0007] Step 1: Synthesis of sulfonic acid-rich porous organic framework (SNK-41):

[0008] Take two reaction tubes. Add acetonitrile and NK-COF-41 to reaction tube A, and add acetonitrile and 1,3-propanesulfonyl lactone to reaction tube B. Under nitrogen protection, add the solution in tube B dropwise to tube A, and then reflux in a water bath at 60-80℃ for 12-24 hours. Filter the reaction product, wash the filter cake with acetonitrile, and vacuum dry to obtain a red powder solid, which is designated as SNK-41.

[0009] In reaction tube A, 200-300 mg of dried NK-COF-41 was added to every 10 mL of ultra-dry acetonitrile; in reaction tube B, 200-300 mg of 1,3-propanesulfonyl lactone was added to every 10 mL of ultra-dry acetonitrile; the mass ratio of NK-COF-41 to 1,3-propanesulfonyl lactone was 4:5.

[0010] The NK-COF-41 is obtained by ball milling followed by vacuum drying; the ball milling speed is 500-1000 rpm, and the time is 5-18 h; the drying temperature is 40-80℃, and the time is 6-24 h.

[0011] Step 2: The SNK-41 powder obtained in Step 1 is ball-milled and sieved, then added to N,N-dimethylacetamide (DMAc) and ultrasonically dispersed to obtain an SNK-41 dispersion.

[0012] Each 4 mL of DMAc contains 380-480 mg of SNK-41 powder.

[0013] Step 3: Add the SNK-41 dispersion obtained in Step 2 dropwise to the low sulfonation degree SPEEK dispersion and stir to mix at room temperature to obtain a mixed solution;

[0014] The concentration of the SPEEK dispersion was 100-120 mg / mL. -1 The solvent is DMAc; the mass ratio is SNK-41 dispersion: SPEEK dispersion = (0.1-0.4):1;

[0015] Step 4: Coat the mixed solution obtained in Step 3 onto a glass plate, vacuum dry at 40-60℃ for 6-24 hours, then vacuum dry at 70-90℃ for 12-24 hours, and finally anneal in a vacuum drying oven at 110-120℃ for 3-6 hours; after cooling to room temperature, peel the composite membrane off the glass plate with ultrapure water to obtain a sulfonated polyether ether ketone / sulfonic acid-rich porous organic framework composite proton exchange membrane.

[0016] The sulfonation degree of the low-sulfonation SPEEK is 45%-55%.

[0017] The thickness of the sulfonated polyether ether ketone / sulfonic acid-rich porous organic framework composite proton exchange membrane is 16-60 μm.

[0018] The sulfonated polyether ether ketone / sulfonic acid-rich porous organic framework composite proton exchange membrane exhibits a proton conductivity of 0.121 S cm⁻¹ at 80°C and 100% RH. -1 -0.163S cm -1 .

[0019] The essential features of this invention are:

[0020] This invention first selects low-sulfonation polyether ether ketone (SPEEK) as the base membrane for the polymer proton exchange membrane, fully utilizing the advantages of the excellent dimensional stability, oxidative stability, and mechanical properties of the low-sulfonation polyether ether ketone base membrane, while avoiding the problem of excessive swelling of the high-sulfonation polyether ether ketone base membrane at high temperatures. Then, to improve the proton transfer performance of the low-sulfonation SPEEK membrane, a sulfonic acid-rich porous organic framework (SNK-41) is introduced into the base membrane as a filler. Finally, a high-sulfonation polyether ether ketone base membrane with high proton conductivity is obtained, while also avoiding the defect of low proton conductivity of the low-sulfonation polyether ether ketone base membrane.

[0021] The mechanism is as follows: 1,3-propanesulfonyl lactone undergoes ring-opening and addition reaction with the pyridine N atom of NK-COF-41 to synthesize the sulfonic acid-rich porous organic framework SNK-41. SNK-41 has a sulfonation degree as high as 90%, and the abundant sulfonic acid groups provide sufficient sites for proton transfer; at the same time, SNK-41 has a 468.6m... 2 g-1 With its high specific surface area, SNK-41 can form a continuous hydrogen bond network after full hydration, promoting proton transport via the Gaossian mechanism. In addition, SNK-41 has a stable structure and hardly swells at 80°C and 100% RH. When combined with a low-sulfonation SPEEK matrix, it can effectively reduce the swelling rate of the composite proton exchange membrane. Therefore, the SPEEK@SNK-41 composite proton exchange membrane has the characteristics of high proton conductivity, high ion exchange capacity and low swelling rate.

[0022] The beneficial effects of this invention are:

[0023] The low-sulfonation, sulfonic acid-rich SPK@SNK-40% composite proton exchange membrane prepared in this invention exhibits high proton conductivity (0.163 S cm⁻¹ at 80°C and 100% RH). -1 Low surface swelling ratio (11.7% at 80℃ and 100% RH), high ion exchange capacity (2.05 meq g at 80℃ and 100% RH). -1 Compared to SPK45 base membranes without sulfonate-rich groups at the same degree of sulfonation, the proton conductivity was increased by 73%, and the ion exchange capacity was increased by 20%. Compared to SPEEK proton exchange membranes with a high degree of sulfonation (68% in this invention), the surface swelling ratio was reduced from 136.2% to 11.7%. In the 28-day stability test, the proton conductivity of the SPK45 base membrane without sulfonate-rich porous organic framework filler was only 28.1% of the initial value, while the low-sulfonate-rich sulfonate-rich SPK45@SNK-40% still retained 79.9% of the initial proton conductivity, demonstrating stability under the same conditions. 96.8% of 117. Therefore, the low-sulfonation SPEEK sulfonic acid-rich covalent organic framework composite proton exchange membrane prepared in this invention has the characteristics of high ion exchange capacity, high proton conductivity, low surface swelling ratio, and high stability. Attached Figure Description

[0024] Figure 1 The proton conductivity of the SPK45-based composite proton exchange membranes obtained in Examples 1-4 and Comparative Example 1 at different temperatures;

[0025] Figure 2 The stability of proton conductivity of the composite proton exchange membranes obtained in Example 1 and Comparative Examples 1-3. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] The low-sulfonation SPEEK@sulfonic acid-rich porous organic framework composite proton exchange membrane proposed in this invention is prepared using low-sulfonation SPEEK as the substrate and sulfonic acid-rich porous organic framework powder as the filler via solution casting. The preparation process mainly includes: preparation of low-sulfonation SPEEK, preparation of sulfonic acid-rich porous organic framework (SNK-41), and preparation of the SPK@SNK-X composite membrane. The SPEEK substrate is prepared using a post-sulfonation method, and the sulfonic acid-rich porous organic framework SNK-41 is prepared using a one-pot method. The obtained SPEEK and SNK-41 powders are uniformly dispersed in DMAc solvent to obtain SPEEK and SNK-41 solutions, respectively. After blending the two solutions, the sulfonated polyetheretherketone / sulfonic acid-rich porous organic composite proton exchange membrane is prepared using solution casting. This proton exchange membrane exhibits excellent proton conductivity and low swelling ratio. The preparation method of this invention is mild, controlled, simple and efficient. The proton exchange membrane prepared has high proton conductivity and excellent tensile strength, as well as good thermal, chemical and long-term stability, which is conducive to its wide application in hydrogen energy conversion technology.

[0028] The NK-COF-41 described in this invention is a known material with a purity of 98%, and is manufactured by Beijing Huawi Ruike Chemical Co., Ltd.

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are for illustrative purposes only and should not be considered as any limitation on the present invention.

[0030] Example 1

[0031] The steps for preparing the SPK@SNK composite proton exchange membrane are as follows:

[0032] Step 1: Preparation of Low-Sulfonation SPEEK: First, the water content of the polyether ether ketone (PEEK) raw material was removed under vacuum at 60°C. Under ice-water bath conditions, 7g of dried PEEK was added granule by granule to 120mL of 98% concentrated sulfuric acid. The reaction flask was then subjected to a vacuum-nitrogen purging process repeated at least three times using a double-row tube. The flask was sealed with an acid-resistant rubber stopper and stirred magnetically (1000rpm) for 6 hours until dissolved. The temperature was then raised to 60°C for a heating sulfonation reaction for 55 minutes. The reaction product was then slowly poured into a large volume of ice water with mechanical stirring to obtain white filamentous SPEEK. The SPEEK was then washed with a large amount of deionized water until pH=7.0, and dried to obtain yellow SPEEK. Nuclear magnetic resonance (NMR) spectroscopy showed that the sulfonation degree of the obtained SPEEK was 45%, denoted as SPK45.

[0033] The specific reaction formula for this sulfonation reaction is as follows:

[0034]

[0035] Step 2: Preparation of SNK-41, a porous organic framework rich in sulfonic acid: The raw material NK-COF-41 was ball-milled for 12 hours (500-1000 rpm) at room temperature, and then dried in a vacuum oven at 80°C for 24 hours. Under ice-water bath conditions, 10 mL of ultra-dry acetonitrile (purity ≥99.99%, water content ≤0.01%) was added to two 50 mL dry pressure-resistant reaction tubes, A and B respectively. 200 mg of dried NK-COF-41 was added to tube A and sonicated until uniformly dispersed. 250 mg of 1,3-propanesulfonyl lactone was added dropwise to tube B and sonicated until uniformly dispersed. The vacuum-nitrogen purging process was repeated at least three times between reaction tubes A and B using a double-row tube system. Under nitrogen protection, the solution in tube B was slowly added dropwise to the dispersion in tube A, and then the mixture was reacted in an 80°C water bath for 12 hours. The reaction product was filtered and repeatedly washed with acetonitrile to remove unreacted 1,3-propanesulfonyl lactone, and then dried to constant weight in a vacuum oven at 60°C to obtain a red powder solid, namely SNK-41.

[0036]

[0037] Nuclear magnetic resonance (NMR) 1H spectroscopy revealed that SNK-41 had a sulfonation degree of 90%, and its specific surface area was determined to be 468.6 m². 2 g -1

[0038] The obtained sulfonic acid-rich porous organic framework material has the following advantages: (1) The physicochemical stability of the porous organic framework itself enables it to adapt to the working conditions of fuel cells without easily swelling or decomposing; (2) The large number of sulfonic acid groups in the sulfonic acid-rich porous organic framework can act as proton carriers, promoting proton transport; (3) The sulfonic acid-rich porous organic framework has an open-space network structure with a high specific surface area, which can construct a complex microphase structure within the membrane, including the interior of the porous organic framework and the space between the porous organic framework and the proton exchange membrane matrix. In summary, combining the sulfonic acid-rich porous organic framework with low-sulfonation SPEEK can provide abundant sites for proton transport, reconstruct the microphase structure within the membrane, improve the connectivity of the proton transport channels within the membrane, improve proton transfer performance, and effectively reduce the swelling of the proton exchange membrane.

[0039] Step 3: Preparation of SPK@SNK composite proton exchange membrane: The SPEEK and N,N-dimethylacetamide (DMAc) prepared in Step 1 were mixed to a concentration of 120 mg / mL. -1The SNK-41 dispersion was stirred at room temperature until completely dissolved. The SNK-41 powder obtained in step 2 was ball-milled and passed through a 150-mesh sieve. 400 mg of the sieved powder was weighed and dispersed in 4 mL of DMAc, and sonicated for 12 hours to ensure uniform dispersion. The SNK-41 dispersion and SPEEK dispersion were thoroughly mixed at a mass ratio of 0.4:1. The mixture was uniformly dropped onto a 5 cm × 5 cm glass plate using a solution casting method, dried in a vacuum drying oven at 60°C for 12 hours, then dried in a vacuum drying oven at 80°C for 12 hours, and finally annealed in a vacuum drying oven at 120°C for 3 hours. After cooling to room temperature, the composite membrane was peeled off the glass plate with ultrapure water to obtain SPEEK@SNK composite membrane 1 with a thickness of 40 μm, denoted as SPK45@SNK-40%.

[0040] The proton conductivity of composite membrane 1 was tested using an electrochemical workstation. Under conditions of 80℃ and 100% relative humidity, the proton conductivity was 0.163 S cm⁻¹. -1 .

[0041] Example 2

[0042] A low-sulfonation SPEEK@sulfonic acid-rich porous organic framework composite proton exchange membrane was prepared. The preparation process was basically the same as in Example 1, except that in step 3, the mass ratio of SNK-41 dispersion to SPEEK dispersion was changed from 0.4:1 to 0.3:1 to finally obtain SPEEK@SNK composite membrane 2, denoted as SPK45@SNK-30%.

[0043] The proton conductivity of composite membrane 2 was tested using an electrochemical workstation. Under conditions of 80℃ and 100% relative humidity, the proton conductivity was 0.141 S cm⁻¹. -1 .

[0044] Example 3

[0045] A low-sulfonation SPEEK@sulfonic acid-rich porous organic framework composite proton exchange membrane was prepared. The preparation process was basically the same as in Example 1, except that in step 3, the mass ratio of SNK-41 dispersion to SPEEK dispersion was changed from 0.4:1 to 0.2:1 to finally obtain SPEEK@SNK composite membrane 3, denoted as SPK45@SNK-20%.

[0046] The proton conductivity of composite membrane 3 was tested using an electrochemical workstation. Under conditions of 80℃ and 100% relative humidity, the proton conductivity was 0.139 S cm⁻¹. -1 .

[0047] Example 4

[0048] A low-sulfonation SPEEK@sulfonic acid-rich porous organic framework composite proton exchange membrane was prepared. The preparation process was basically the same as in Example 1, except that in step 3, the mass ratio of SNK-41 dispersion to SPEEK dispersion was changed from 0.4:1 to 0.1:1 to finally obtain SPEEK@SNK composite membrane 4, denoted as SPK45@SNK-10%.

[0049] The proton conductivity of composite membrane 4 was tested using an electrochemical workstation. Under conditions of 80℃ and 100% relative humidity, the proton conductivity was 0.121 S cm⁻¹. -1 .

[0050] Comparative Example 1

[0051] The specific steps for preparing a SPEEK proton exchange membrane include:

[0052] Step 1, SPEEK preparation: Same as Step 1 in Example 1.

[0053] Step 2, Preparation of SPEEK proton exchange membrane: The SPEEK obtained in Step 1 and N,N-dimethylacetamide (DMAc) were mixed to prepare a solution with a mass-volume concentration of 120 mg / mL. -1 The dispersion was stirred at room temperature until completely dissolved. The dispersion was then uniformly dropped onto a 5cm × 5cm glass plate using a solution casting method. The plate was dried in a vacuum drying oven at 60℃ for 12 hours, then in a vacuum drying oven at 80℃ for 12 hours, and finally annealed in a vacuum drying oven at 120℃ for 3 hours. After cooling to room temperature, the composite membrane was peeled off the glass plate with ultrapure water to obtain the SPEEK proton exchange membrane, denoted as SPK45.

[0054] The proton conductivity of SPK45 was tested using an electrochemical workstation. Under conditions of 80℃ and 100% relative humidity, the proton conductivity was 0.094 S cm⁻¹. -1 .

[0055] Comparative Example 2

[0056] The specific steps for preparing a high-sulfonation SPEEK proton exchange membrane include:

[0057] Step 1, Preparation of high-sulfonation SPEEK: The sulfonation time in Step 1 of Example 1 was changed from 55 min to 150 min. The degree of sulfonation increased from 45% to 68%.

[0058] Step 2, Preparation of high sulfonation degree SPEEK proton exchange membrane: Same as step 2 in Comparative Example 1, a high sulfonation degree SPEEK proton exchange membrane was obtained, denoted as SPK68.

[0059] The proton conductivity of SPK68 was tested using an electrochemical workstation. Under conditions of 80℃ and 100% relative humidity, the proton conductivity was 0.124 S cm⁻¹. -1 .

[0060] Comparative Example 3

[0061] Nafion @ The 117 proton exchange membrane exhibits a proton conductivity of 0.151 S cm⁻¹ under conditions of 80°C and 100% relative humidity. -1 .

[0062] Table 1 shows the process conditions for preparing the composite membrane and the properties of the resulting composite membrane.

[0063] Table 1. Process conditions for composite membrane preparation and properties of the resulting composite membrane

[0064]

[0065] In Table 1, A represents SNK-41 and B represents SPEEK.

[0066] From Table 1 and Appendix Figure 1 The performance of the composite membranes 1-4 was significantly improved, as shown in the examples and comparative examples. Comparing Example 1 and Comparative Example 1, at 80°C and 100% RH, Example 1 showed a 73% increase in proton conductivity and a 20% increase in ion exchange capacity. Compared to Comparative Example 2, the surface swelling ratio of Example 1 decreased from 136.2% to 11.7%. Therefore, the introduction of SNK-41 significantly increased the content of polar groups (such as sulfonic acid groups) within the membrane, leading to enhanced electrostatic interactions between these groups. This electrostatic interaction facilitates the connection of discrete ion clusters within the membrane, forming long-range ordered proton transport channels. Simultaneously, the attached... Figure 2 The proton conductivity stability test results of the composite proton exchange membranes obtained in Examples 1 and Comparative Examples 1-3 show that composite membrane 1 (corresponding to SPK45@SNK-40%) has stronger stability than the SPK membrane, and is comparable to Nafion. @ The 117 is comparable, which is not only due to the low swelling rate of the low-sulfonation SPEEK matrix, but also to the dimensional and chemical stability of the sulfonic acid-rich SNK-41.

[0067] In summary, this invention prepares a SPK@SNK-X (where X is the mass fraction of SNK-41 in SPEEK) composite proton exchange membrane using low-sulfonation SPEEK as the matrix and sulfonic acid-rich porous organic framework material (SNK-41) as the filler. SNK-41 contains a large number of hydrophilic sulfonic acid groups, which readily form hydrogen bonds with water molecules, enhancing the material's adsorption of water molecules. Furthermore, the doping of high specific surface area SNK-41 provides a richer pore structure within the membrane, altering the microscopic phase separation structure of the polymer. By controlling the doping amount of SNK-41, the ordered arrangement of the hydrophilic structures within the membrane is controlled, thereby achieving regulation of the proton transport channels, reducing the energy barrier during proton transport, and optimizing the proton transport path, thus improving proton conductivity. In addition, the sulfonic acid-rich porous organic framework exhibits low swelling ratio under high humidity, and the composite proton exchange membrane formed with the low-sulfonation SPEEK base membrane possesses characteristics of high proton conductivity, high ion exchange capacity, and low swelling ratio.

[0068] The above descriptions are merely several preferred embodiments of the present invention, but the present invention is not limited to the specific implementation methods described above. The specific implementation methods described above are illustrative and not restrictive. Researchers in the art, under the guidance of the present invention and in accordance with the spirit and principles of the present invention, can make improvements and modifications, all of which fall within the protection scope of the present invention.

[0069] Matters not covered in this invention are common knowledge.

Claims

1. A method for preparing a low-sulfonation degree sulfonated polyether ether ketone-based composite proton exchange membrane, characterized by comprising the following steps: Step 1: synthesis of a sulfonic acid group-rich porous organic framework SNK-41: Take two reaction tubes, add acetonitrile and NK-COF-41 to reaction tube A, and add acetonitrile and 1,3-propane sulfone lactone to reaction tube B; under nitrogen protection, add the solution in tube B to tube A dropwise, then reflux in a 60-80 ℃ water bath for 12-24 h; filter the reaction product, wash the filter cake with acetonitrile, and vacuum dry to obtain a red powder solid, which is recorded as SNK-41; wherein In reaction tube A, add 200-300 mg of dried NK-COF-41 to 10 mL of super-dry acetonitrile; in reaction tube B, add 200-300 mg of 1,3-propane sulfone lactone to 10 mL of super-dry acetonitrile; the mass ratio of NK-COF-41 to 1,3-propane sulfone lactone is 4:5; Step 2: sieve the SNK-41 powder obtained in step 1 after ball milling, add it to N,N-dimethylacetamide (DMAc), and ultrasonically disperse to obtain a SNK-41 dispersion; In which, add 380-480 mg of SNK-41 powder to 4 mL of DMAc; Step 3: add the SNK-41 dispersion obtained in step 2 to a low-sulfonation degree SPEEK dispersion dropwise, and stir and mix at room temperature to obtain a mixed solution; wherein the concentration of the SPEEK dispersion is 100-120 mg / mL -1 and the solvent is DMAc; the mass ratio of SNK-41 dispersion to SPEEK dispersion is (0.1-0.4):

1. Step 4: coat the mixed solution obtained in step 3 on a glass plate, vacuum dry at 40-60 ℃ for 6-24 h, then vacuum dry at 70-90 ℃ for 12-24 h, and finally anneal in a vacuum drying oven at 110-120 ℃ for 3-6 h; after cooling to room temperature, peel the composite membrane from the glass plate with ultrapure water to obtain a sulfonated polyether ether ketone / sulfonic acid group-rich porous organic framework composite proton exchange membrane.

2. The method for preparing a low-sulfonation degree sulfonated polyether ether ketone-based composite proton exchange membrane as described in claim 1, characterized in that, The NK-COF-41 is vacuum dried after ball milling; the ball milling speed is 500-1000 rpm, and the time is 5-18 h; the drying temperature is 40-80 ℃, and the time is 6-24 h.

3. The method for preparing a low-sulfonation degree sulfonated polyether ether ketone-based composite proton exchange membrane as described in claim 1, characterized in that, The sulfonated polyether ether ketone / sulfonic acid group-rich porous organic framework composite proton exchange membrane has a thickness of 16-60 µm.

4. The method for preparing a low-sulfonation degree sulfonated polyether ether ketone-based composite proton exchange membrane as described in claim 1, characterized in that, The sulfonated poly (ether ether ketone) / sulfonic acid group-rich porous organic framework composite proton exchange membrane has a proton conductivity of 0.121 S cm of the composite membrane at 80 DEG C and 100% RH -1 -0.163 S cm -1 .

5. The method for preparing a low-sulfonation degree sulfonated polyether ether ketone-based composite proton exchange membrane as described in claim 1, characterized in that, The low-sulfonation degree SPEEK has a sulfonation degree of 45%-55%.

Images