A modified proton exchange membrane and its preparation method and application
The modified proton exchange membrane, with nano-silica and phosphonic acid groups, addresses the limitations of conventional membranes by enhancing water retention, glass transition temperature, and conductivity, allowing operation up to 120°C.
Patent Information
- Application Number
- CN202411133037.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-19
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2044-08-19
AI Technical Summary
Existing proton exchange membranes face limitations in terms of operating temperature range, which can significantly improve the water retention, glass transition temperature and high-temperature conductivity of the membrane layer, thereby improving the water retention and glass transition temperature and high-temperature conductivity of the membrane layer, thereby improving the water retention and glass transition temperature of the membrane layer, thereby improving the water retention and glass transition temperature of the membrane layer, thereby improving the water retention and glass transition temperature of the membrane layer, and enhancing the high-temperature conductivity of the proton exchange membrane.
A modified proton exchange membrane is developed by incorporating modified nano-silica into the perfluorosulfonic acid resin, where nano-silica is modified with 1,1-diphosphonic acid ethanol to graft phosphonic acid groups and perfluorosulfonic acid resin is modified with 2,3-epoxypropyltrimethylammonium chloride to create quaternary amine groups, forming strong interactions that anchor the nano-silica, enhancing dispersion and reducing phosphoric acid loss.
The modified membrane achieves a maximum operating temperature of 120°C with improved water retention, glass transition temperature, and conductivity up to 0.03S/cm, significantly surpassing conventional membranes.
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Figure CN118712437B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of proton exchange membranes, and in particular relates to a modified proton exchange membrane and a preparation method and application thereof. Background Art
[0002] Fuel cells, especially hydrogen fuel cells, are one of the most promising alternative energy sources. Compared with traditional internal combustion engines, they have higher energy conversion efficiency, higher energy density than ordinary batteries, and the advantage of using clean fuels without producing pollutants. At the same time, fuel cells are very quiet during operation, with almost no noise or very little noise, but their large-scale application still faces the problem of limited operating temperature range. Perfluorosulfonic acid polymer membranes are one of the most well-known polymer ion exchange membranes due to their unique transport properties and stability, and are also the most common type of proton exchange membrane on the market. However, their conventional operating temperature range is only about 80°C, resulting in low efficiency of fuel cell systems. Therefore, widening their operating temperature range has become a research hotspot in the field of fuel cells.
[0003] Phosphoric acid, as a high-temperature proton conductor, can be used in a relatively high temperature range. However, the proton exchange membrane doped with phosphoric acid generally has the problem of excessive phosphoric acid loss rate. Therefore, the development of a high-temperature proton exchange membrane that can meet the requirements of long-term stable operation is of great significance for broadening the operating temperature range of fuel cells. Summary of the invention
[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a modified proton exchange membrane and a preparation method and application thereof, wherein the modified proton exchange membrane can significantly improve the water retention, glass transition temperature and high-temperature conductivity of the membrane layer.
[0005] To solve the above technical problems, the first aspect of the present invention provides a modified proton exchange membrane, comprising modified nano-silica and modified perfluorosulfonic acid resin, wherein the modified nano-silica is uniformly distributed in the modified perfluorosulfonic acid resin; the modification of the modified nano-silica is to graft 1,1-diphosphonic acid ethanol on the surface of the nano-silica, and the modification of the modified perfluorosulfonic acid resin is to graft 2,3-epoxypropyltrimethylammonium chloride on the side chain ends of the perfluorosulfonic acid resin after amination.
[0006] Specifically, the present invention improves the water retention and glass transition temperature of the proton exchange membrane by doping modified nano-silica in the modified perfluorosulfonic acid resin, thereby improving its high-temperature conductivity. On the one hand, the present invention uses 1,1-diphosphonic acid ethanol to modify the nano-silica, and grafts phosphonic acid groups on the surface of the nano-silica to provide more effective transmission sites for the proton conduction of the proton exchange membrane at medium and high temperatures. Compared with traditional amino, sulfonic acid, carboxylic acid or hydroxyl modifications, most of them rely on water for the transmission of protons; while 1,1-diphosphonic acid ethanol hardly relies on water for the transmission of protons at medium and high temperatures, so the grafted phosphonic acid group is more conducive to the use of the proton exchange membrane at medium and high temperatures. On the other hand, the present invention grafts 2,3-epoxypropyltrimethylammonium chloride on the end of the side chain of the perfluorosulfonic acid resin after ammoniation, so that the end of the side chain of the perfluorosulfonic acid resin is connected to a quaternary amine group with a positive charge, thereby generating a strong interaction with the phosphonic acid group with a negative charge on the surface of the modified nano-silica, playing an anchoring role. Under the anchoring effect, the modified nano-silica is evenly dispersed in the proton exchange membrane, which not only significantly reduces the loss rate of the phosphonic acid group, but also helps to improve the water retention and glass transition temperature of the proton exchange membrane, and improve the high-temperature conductivity.
[0007] Preferably, the mass ratio of the modified nano-silica to the modified perfluorosulfonic acid resin is 1:(20-100).
[0008] Preferably, the particle size of the modified nano-silicon dioxide is 60-80 nm. Small-sized and evenly distributed silicon dioxide can provide more active sites for surface modification of nano-silicon dioxide.
[0009] The second aspect of the present invention provides a method for preparing the above-mentioned modified proton exchange membrane, comprising the following steps:
[0010] Preparation of modified nano-silica:
[0011] Under the protection of an inert gas, 4-dimethylaminopyridine is dissolved in a first organic solvent, nano-silicon dioxide is added, the temperature is lowered, and then 1,1-diphosphonic acid ethanol is added and mixed to obtain the modified nano-silicon dioxide;
[0012] Preparation of modified perfluorosulfonic acid resin:
[0013] Liquid ammonia is introduced into a reaction container containing a perfluorosulfonic acid resin, and the mixture is mixed; after the ammonia gas is released, the mixture is calcined to obtain a perfluorosulfonic acid resin with aminated branched ends; the perfluorosulfonic acid resin with aminated branched ends is then dissolved in a second organic solvent, 2,3-epoxypropyltrimethylammonium chloride is added, the mixture is heated, mixed, and centrifuged to obtain the modified perfluorosulfonic acid resin;
[0014] The modified nano-silica and the modified perfluorosulfonic acid resin are mixed in a third organic solvent to obtain a casting solution; the casting solution is then formed into a film, dried, washed, and dried again to obtain the modified proton exchange membrane.
[0015] Specifically, the present invention grafts phosphonic acid groups on the surface of nano-silica under the action of the catalyst 4-dimethylaminopyridine, providing more effective transmission sites for proton conduction of proton exchange membranes at medium and high temperatures. At the same time, the present invention utilizes the presence of quaternary amine groups in 2,3-epoxypropyltrimethylammonium chloride, which carries a positive charge. After the end of the branch chain of the perfluorosulfonic acid resin is aminated, 2,3-epoxypropyltrimethylammonium chloride is grafted to connect the quaternary amine groups to the end of the branch chain, so that the end of the branch chain carries a positive charge, thereby generating a strong interaction with the negatively charged phosphonic acid groups on the surface of the modified nano-silica, playing an anchoring role.
[0016] Preferably, the preparation steps of the nano-silica are: firstly, adding tetraethyl silicate to an aqueous solution of a pH regulator, refluxing in a water bath to obtain a silica seed dispersion; then, adding the silica seed dispersion and tetraethyl silicate to the aqueous solution of the pH regulator, heating, mixing, and freeze-drying to obtain the nano-silica.
[0017] Specifically, the present invention uses silicon dioxide seeds as crystal nuclei and adopts the hydrolysis of tetraethyl silicate to prepare nano silicon dioxide. The nano silicon dioxide prepared by this method has the characteristics of small particle size and uniform distribution, which provides more hydroxyl active sites for subsequent surface modification of nano silicon dioxide.
[0018] Preferably, the pH adjuster is selected from at least one of arginine, ammonia water and potassium carbonate; more preferably, the pH adjuster is arginine, which has better stability.
[0019] Preferably, in the silica seed dispersion, the mass ratio of tetraethyl silicate, pH adjuster and water is (0.2-0.3):(0.1-0.2):100.
[0020] Preferably, the mass ratio of the silica seed dispersion and tetraethyl silicate added to the aqueous solution of the pH adjuster is (11-20):(2-3).
[0021] Preferably, during the preparation of nano-silicon dioxide, the heating temperature is 60-80°C.
[0022] Preferably, the concentration of the solution formed by dissolving 4-dimethylaminopyridine in the first organic solvent is 1-2 g / L, and the mass ratio of 4-dimethylaminopyridine, nano-silica and 1,1-diphosphonoethanol is 1:(0.4-0.6):(40-60).
[0023] Preferably, the first organic solvent comprises dichloromethane.
[0024] Preferably, the temperature is lowered to 0°C.
[0025] Preferably, the mixing is performed at room temperature.
[0026] Preferably, in the preparation process of the modified perfluorosulfonic acid resin, the calcination temperature condition is: calcination at 180-220° C. for 1-3 hours.
[0027] Preferably, in the preparation process of the modified perfluorosulfonic acid resin, the heating temperature is 85-95° C., and the mixing time is 10-14 hours.
[0028] Preferably, the mass ratio of the branched-end aminated perfluorosulfonic acid resin, the second organic solvent and 2,3-epoxypropyltrimethylammonium chloride is 1:(60-100):(0.3-0.4).
[0029] Preferably, the second organic solvent comprises dimethyl sulfoxide.
[0030] Preferably, in the casting solution, the mass ratio of the modified perfluorosulfonic acid resin to the third organic solvent is (1-3):40.
[0031] Preferably, the third organic solvent comprises N, N-dimethylacetamide and / or N, N-dimethylformamide.
[0032] Preferably, the drying temperature is 60-150° C., and the drying time is 20-28 hours.
[0033] Preferably, the washing is performed by soaking and washing with a hydrogen peroxide solution, a sulfuric acid solution and deionized water in sequence for 0.5-1 hour.
[0034] Preferably, the temperature of the secondary drying is 50-70°C.
[0035] The third aspect of the present invention provides the use of the modified proton exchange membrane in a fuel cell or water electrolysis.
[0036] Compared with the prior art, the above technical solution of the present invention has at least the following technical effects or advantages:
[0037] (1) The present invention introduces modified nano-silica into the modified perfluorosulfonic acid resin to increase the glass transition temperature of the proton exchange membrane, thereby increasing the upper limit of the operating temperature of the proton exchange membrane and achieving a maximum operating temperature of 120°C.
[0038] (2) The present invention uses 1,1-diphosphonoethanol to modify nano-silica, and grafts phosphonic acid groups on the surface of nano-silica, which provides more effective transmission sites for proton conduction of proton exchange membranes at medium and high temperatures, and reduces the loss rate of phosphonic acid groups. At the same time, by grafting 2,3-epoxypropyltrimethylammonium chloride on the end of the side chain of the perfluorosulfonic acid resin after amination, the end of the side chain of the perfluorosulfonic acid resin is connected to a quaternary amine group, so that the end of the side chain carries a positive charge, thereby generating a strong interaction with the negatively charged phosphonic acid group on the surface of the modified nano-silica, playing an anchoring role, so that the modified nano-silica can be evenly dispersed in the proton exchange membrane, thereby improving the water retention, glass transition temperature and high-temperature conductivity of the proton exchange membrane, and achieving a conductivity greater than 0.03S / cm when the use temperature is 120°C. BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Figure 1 This is a SEM image of nano-silicon dioxide prepared in Example 1 of the present invention;
[0040] Figure 2 This is the infrared spectrum of the modified nano-silicon dioxide prepared in Example 1 of the present invention;
[0041] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the modified perfluorosulfonic acid resin prepared in Example 1 of the present invention;
[0042] Figure 4 The conductivity diagrams of the modified proton exchange membranes prepared in Examples 1-3 of the present invention and the proton exchange membranes prepared in Comparative Examples 1-3 at different humidity levels;
[0043] Figure 5 The conductivity diagrams of the modified proton exchange membranes prepared in Examples 1-3 of the present invention and the proton exchange membranes prepared in Comparative Examples 2-3 at different temperatures. DETAILED DESCRIPTION
[0044] The present invention is described in detail below in conjunction with the examples, so that the technical personnel of the relevant technical field can understand the present invention. It is necessary to point out here that the examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. The non-essential improvements and adjustments made to the present invention by the skilled person in the relevant field according to the above invention content should still belong to the scope of protection of the present invention. At the same time, the raw materials mentioned below that are not described in detail are all commercially available products; the process steps or preparation methods that are not mentioned in detail are all process steps or preparation methods known to those skilled in the art.
[0045] Example 1
[0046] A method for preparing a modified proton exchange membrane comprises the following steps:
[0047] (1) Preparation of silica seed dispersion
[0048] 174 mg of arginine and 174 g of deionized water were mixed in a conical flask and stirred at room temperature for 10 min to obtain a colorless and transparent solution. 0.348 g of tetraethyl silicate was added to the arginine aqueous solution and refluxed in a water bath with stirring for 24 h to obtain a silica seed dispersion.
[0049] (2) Preparation of Nano-Silica
[0050] 19.14 g of silica seed dispersion was added to a solution containing 174 mg of arginine and 174 g of deionized water and stirred, and then 3.48 g of tetraethyl silicate was added; the mixture was stirred at room temperature for 10 min and continued to be stirred at 70°C for 24 h; a uniformly dispersed nano-silica suspension was obtained, which was freeze-dried to obtain nano-silica particles. The SEM image of the nano-silica particles is shown in FIG. Figure 1 As shown by Figure 1 It can be seen that the particle size of the nano-silicon dioxide particles is 60-80 nm.
[0051] (3) Preparation of modified nano-silica
[0052] Under nitrogen protection, 0.4 g of 4-dimethylaminopyridine was dissolved in 300 mL of dichloromethane (DCM) and 2 g of nano-silica particles were added. The temperature was lowered to 0°C and 20 g of 1,1-diphosphonic acid ethanol was added. The mixture was stirred at room temperature for 24 h to obtain modified nano-silica particles. The infrared spectrum of the modified nano-silica particles is shown in FIG. Figure 2 As shown, from Figure 2 It can be seen that 634cm -1 is the bending vibration of PO-Si bond, 712cm -1 It is the stretching vibration of PO-Si, which proves that the surface modification of nano-silica is successful.
[0053] (4) Preparation of modified perfluorosulfonic acid resin
[0054] 10 g of perfluorosulfonic acid resin was placed in a round-bottom flask, and liquid ammonia was introduced at -50°C and stirred for 12 hours. After the ammonia was completely released, the resin was calcined at 200°C under nitrogen protection to remove crystal water. 5 g of the calcined resin was dissolved in 400 g of dimethyl sulfoxide, and 1.5 g of 2,3-epoxypropyltrimethylammonium chloride was added and stirred at 90°C for 12 hours. After recrystallization, the mixture was centrifuged and washed to obtain a modified perfluorosulfonic acid resin. Figure 3 The obtained modified perfluorosulfonic acid resin 1 H NMR spectrum, Figure 3 The letters ae and h marked on the polymer can find corresponding peaks in the H-NMR spectrum, proving that the modified perfluorosulfonic acid resin was successfully prepared.
[0055] (5) Preparation of modified proton exchange membrane
[0056] 0.01g of modified nano-silica and 1g of modified perfluorosulfonic acid resin are respectively added to 40g of N, N-dimethylformamide and dispersed evenly. The dispersed modified nano-silica suspension is added to the modified perfluorosulfonic acid resin solution, and mixed thoroughly to obtain a casting solution. The casting solution is poured into a plastic mold or a glass plate and dried at 60°C for 24h. The dried proton exchange membrane is sequentially soaked and washed in 3wt% hydrogen peroxide solution, 1mol / L sulfuric acid solution, and deionized water for 0.5-1h, and finally placed in a 60°C forced air drying oven to dry to obtain a modified proton exchange membrane.
[0057] Example 2
[0058] A method for preparing a modified proton exchange membrane comprises the following steps:
[0059] (1) Preparation of silica seed dispersion
[0060] 174 mg of arginine and 174 g of deionized water were mixed in a conical flask and stirred at room temperature for 10 min to obtain a colorless and transparent solution. 0.408 g of tetraethyl silicate was added to the arginine aqueous solution and refluxed in a water bath with stirring for 24 h to obtain a silica seed dispersion.
[0061] (2) Preparation of Nano-Silica
[0062] 21.6 g of silica seed dispersion was added to a solution containing 174 mg of arginine and 174 g of deionized water and stirred, and then 4.08 g of tetraethyl silicate was added; stirring was performed at room temperature for 10 min and continued at 70° C. for 24 h; a uniformly dispersed nano-silica suspension was obtained, which was freeze-dried to obtain nano-silica particles.
[0063] (3) Preparation of modified nano-silica
[0064] Under nitrogen protection, 0.4 g of 4-dimethylaminopyridine was dissolved in 300 mL of dichloromethane (DCM), and 2 g of nano-silica particles were added. The temperature was lowered to 0°C, and 20 g of 1,1-diphosphonic acid ethanol was added. The mixture was stirred at room temperature for 24 h to obtain modified nano-silica particles.
[0065] (4) Preparation of modified perfluorosulfonic acid resin
[0066] 10 g of perfluorosulfonic acid resin was placed in a round-bottom flask, and liquid ammonia was introduced at -50°C and stirred for 12 hours. After the ammonia was completely released, the obtained resin was calcined at 200°C under nitrogen protection to remove crystal water. 5 g of the calcined resin was dissolved in 400 g of dimethyl sulfoxide, and 1.75 g of 2,3-epoxypropyltrimethylammonium chloride was added and stirred at 90°C for 12 hours. After recrystallization, the mixture was centrifuged and washed to obtain a modified perfluorosulfonic acid resin.
[0067] (5) Preparation of modified proton exchange membrane
[0068] 0.06g of modified nano-silica and 2g of modified perfluorosulfonic acid resin are respectively added to 40g of N, N-dimethylformamide and dispersed evenly. The dispersed modified nano-silica suspension is added to the modified perfluorosulfonic acid resin solution, and mixed evenly to obtain a casting liquid. The casting liquid is poured into a plastic mold or a glass plate and dried at 60°C for 24h. The dried proton exchange membrane is sequentially soaked and washed in 3wt% hydrogen peroxide solution, 1mol / L sulfuric acid solution, and deionized water for 0.5-1h, and finally placed in a 60°C forced air drying oven to dry to obtain a modified proton exchange membrane.
[0069] Example 3
[0070] A method for preparing a modified proton exchange membrane comprises the following steps:
[0071] (1) Preparation of silica seed dispersion
[0072] 174 mg of arginine and 174 g of deionized water were mixed in a conical flask and stirred at room temperature for 10 min to obtain a colorless and transparent solution. 0.522 g of tetraethyl silicate was added to the arginine aqueous solution and refluxed in a water bath with stirring for 24 h to obtain a silica seed dispersion.
[0073] (2) Preparation of Nano-Silica
[0074] 34.8 g of silica seed dispersion was added to a solution containing 174 mg of arginine and 174 g of deionized water and stirred, and then 5.22 g of tetraethyl silicate was added; stirring was performed at room temperature for 10 min and continued at 70° C. for 24 h; a uniformly dispersed nano-silica suspension was obtained, which was freeze-dried to obtain nano-silica particles.
[0075] (3) Preparation of modified nano-silica
[0076] Under nitrogen protection, 0.4 g of 4-dimethylaminopyridine was dissolved in 300 mL of dichloromethane (DCM), and 2 g of nano-silica particles were added. The temperature was lowered to 0°C, and 20 g of 1,1-diphosphonic acid ethanol was added. The mixture was stirred at room temperature for 24 h to obtain modified nano-silica particles.
[0077] (4) Preparation of modified perfluorosulfonic acid resin
[0078] 10 g of perfluorosulfonic acid resin was placed in a round-bottom flask, and liquid ammonia was introduced at -50°C and stirred for 12 hours. After the ammonia was completely released, the resin was calcined at 200°C under nitrogen protection to remove crystal water. 5 g of the calcined resin was dissolved in 400 g of dimethyl sulfoxide, and 2 g of 2,3-epoxypropyltrimethylammonium chloride was added and stirred at 90°C for 12 hours. After recrystallization, the mixture was centrifuged and washed to obtain a modified perfluorosulfonic acid resin.
[0079] (5) Preparation of modified proton exchange membrane
[0080] 0.15g of modified nano-silica and 3g of modified perfluorosulfonic acid resin are respectively added to 40g of N, N-dimethylformamide and dispersed evenly. The dispersed modified nano-silica suspension is added to the modified perfluorosulfonic acid resin solution, and mixed evenly to obtain a casting solution. The casting solution is poured into a plastic mold or a glass plate and dried at 60°C for 24h. The dried proton exchange membrane is sequentially soaked and washed in 3wt% hydrogen peroxide solution, 1mol / L sulfuric acid solution, and deionized water for 0.5-1h, and finally placed in a 60°C forced air drying oven to dry to obtain a modified proton exchange membrane.
[0081] Comparative Example 1
[0082] A proton exchange membrane and a preparation method thereof, comprising the following steps:
[0083] Add 2g of perfluorosulfonic acid resin to 40g of dimethyl sulfoxide and disperse evenly to obtain a casting solution. Pour the casting solution into a plastic mold or a glass plate and dry it at 60°C for 24h. The dried proton exchange membrane is sequentially soaked and washed in 3wt% hydrogen peroxide solution, 1mol / L sulfuric acid solution, and deionized water for 0.5-1h, and finally dried in a 60°C forced air drying oven to obtain a proton exchange membrane.
[0084] Comparative Example 2
[0085] A proton exchange membrane and a preparation method thereof, comprising the following steps:
[0086] (1) Preparation of silica seed dispersion
[0087] 174 mg of arginine and 174 g of deionized water were mixed in a conical flask and stirred at room temperature for 10 min to obtain a colorless and transparent solution. 0.408 g of tetraethyl silicate was added to the arginine aqueous solution and refluxed in a water bath with stirring for 24 h to obtain a silica seed dispersion.
[0088] (2) Preparation of Nano-Silica
[0089] 21.6 g of silica seed dispersion was added to a solution containing 174 mg of arginine and 174 g of deionized water and stirred, and then 4.08 g of tetraethyl silicate was added; stirring was performed at room temperature for 10 min and continued at 70° C. for 24 h; a uniformly dispersed nano-silica suspension was obtained, which was freeze-dried to obtain nano-silica particles.
[0090] (3) Preparation of modified perfluorosulfonic acid resin
[0091] 10 g of perfluorosulfonic acid resin was placed in a round-bottom flask, and liquid ammonia was introduced at -50°C and stirred for 12 hours. After the ammonia was completely released, the obtained resin was calcined at 200°C under nitrogen protection to remove crystal water. 5 g of the calcined resin was dissolved in 400 g of dimethyl sulfoxide, and 1.75 g of 2,3-epoxypropyltrimethylammonium chloride was added and stirred at 90°C for 12 hours. After recrystallization, the mixture was centrifuged and washed to obtain a modified perfluorosulfonic acid resin.
[0092] (4) Preparation of modified proton exchange membrane
[0093] 0.06g of nano-silica and 2g of modified perfluorosulfonic acid resin are respectively added to 40g of N, N-dimethylformamide and dispersed evenly, the dispersed modified nano-silica suspension is added to the modified perfluorosulfonic acid resin solution, and the mixture is fully mixed to obtain a casting solution, the casting solution is poured into a plastic mold or a glass plate and dried at 60°C for 24h, the dried proton exchange membrane is sequentially soaked and washed in a 3wt% hydrogen peroxide solution, a 1mol / L sulfuric acid solution, and deionized water for 0.5-1h, and finally dried in a 60°C forced air drying oven to obtain a proton exchange membrane.
[0094] Comparative Example 3
[0095] A method for preparing a proton exchange membrane comprises the following steps:
[0096] (1) Preparation of silica seed dispersion
[0097] 174 mg of arginine and 174 g of deionized water were mixed in a conical flask and stirred at room temperature for 10 min to obtain a colorless and transparent solution. 0.408 g of tetraethyl silicate was added to the arginine aqueous solution and refluxed in a water bath with stirring for 24 h to obtain a silica seed dispersion.
[0098] (2) Preparation of Nano-Silica
[0099] 21.6 g of silica seed dispersion was added to a solution containing 174 mg of arginine and 174 g of deionized water and stirred, and then 4.08 g of tetraethyl silicate was added; stirring was performed at room temperature for 10 min and continued at 70° C. for 24 h; a uniformly dispersed nano-silica suspension was obtained, which was freeze-dried to obtain nano-silica particles.
[0100] (3) Preparation of modified nano-silica
[0101] Under nitrogen protection, 0.4 g of 4-dimethylaminopyridine was dissolved in 300 mL of dichloromethane (DCM), and 2 g of nano-silica particles were added. The temperature was lowered to 0° C., 20 g of 1,1-diphosphonic acid ethanol was added, and the mixture was stirred at room temperature for 24 h to obtain modified nano-silica particles.
[0102] (4) Preparation of modified proton exchange membrane
[0103] 0.06g of modified nano-silica and 2g of perfluorosulfonic acid resin are respectively added to 40g of N, N-dimethylformamide and dispersed evenly, the dispersed modified nano-silica suspension is added to the modified perfluorosulfonic acid resin solution, and the mixture is fully mixed to obtain a casting solution, the casting solution is poured into a plastic mold or a glass plate and dried at 60°C for 24h, the dried proton exchange membrane is sequentially soaked and washed in a 3wt% hydrogen peroxide solution, a 1mol / L sulfuric acid solution, and deionized water for 0.5-1h, and finally dried in a 60°C forced air drying oven to obtain a proton exchange membrane.
[0104] Performance Testing
[0105] According to the standard GB_T 20042.3-2022 proton exchange membrane fuel cell, part 3: proton exchange membrane test method, the conductivity of the proton exchange membrane prepared in Examples 1-3 and Comparative Examples 1-3 was tested at different humidity under 80°C. The results are as follows: Figure 4 And as shown in Table 1.
[0106] Table 1: Conductivity of proton exchange membrane at different humidity
[0107]
[0108] Depend on Figure 4 As shown in Table 1, compared with Example 2, the conductivity of Comparative Examples 1-3 is significantly reduced under various humidity conditions due to the use of unmodified nano-silica and / or unmodified perfluorosulfonic acid resin.
[0109] According to the standard GB_T 20042.3-2022 Proton Exchange Membrane Fuel Cell, Part 3: Proton Exchange Membrane Test Method, the conductivity of the proton exchange membranes prepared in Examples 1-3 and Comparative Examples 1-3 was tested at different temperatures. The results were as follows: Figure 5 And as shown in Table 2.
[0110] Table 2: Conductivity of proton exchange membrane at different temperatures
[0111]
[0112] Depend on Figure 5 As shown in Table 2, the conductivity of Comparative Examples 2-3 is also significantly reduced under various temperature conditions compared to Example 2 due to the use of unmodified nano-silica or unmodified perfluorosulfonic acid resin. Comparative Example 1 uses unmodified nano-silica and unmodified perfluorosulfonic acid resin, which cannot be used at temperatures above 100°C.
[0113] For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, without having to go through creative labor. Therefore, simple improvements made to the present invention by those skilled in the art based on the disclosure of the present invention should be within the protection scope of the present invention. The above embodiments are preferred embodiments of the present invention, and all processes similar to the present invention and equivalent changes made should belong to the protection scope of the present invention.
Claims
1. A modified proton exchange membrane, characterized in that: It comprises modified nano-silicon dioxide and modified perfluorosulfonic acid resin, wherein the modified nano-silicon dioxide is uniformly distributed in the modified perfluorosulfonic acid resin, and the mass ratio of the modified nano-silicon dioxide to the modified perfluorosulfonic acid resin is 1:(20-100); The modification of the modified nano-silica is to graft 1,1-diphosphonic acid ethanol on the surface of the nano-silica, and the mass ratio of the nano-silica to 1,1-diphosphonic acid ethanol is (4-6): (40-60); The modified perfluorosulfonic acid resin is modified by ammoniation of the branched end of the perfluorosulfonic acid resin and then grafting 2,3-epoxypropyltrimethylammonium chloride, and the mass ratio of the aminated perfluorosulfonic acid resin at the branched end to 2,3-epoxypropyltrimethylammonium chloride is 1:(0.3-0.4).
2. The modified proton exchange membrane according to claim 1, characterized in that: The particle size of the nano silicon dioxide is 60-80nm.
3. A method for preparing a modified proton exchange membrane as claimed in claim 1 or 2, characterized in that: The following steps are involved: Preparation of modified nano-silica: Under the protection of an inert gas, 4-dimethylaminopyridine is dissolved in a first organic solvent, nano-silicon dioxide is added, the temperature is lowered, and then 1,1-diphosphonic acid ethanol is added and mixed to obtain the modified nano-silicon dioxide; Preparation of modified perfluorosulfonic acid resin: Liquid ammonia is introduced into a reaction container containing a perfluorosulfonic acid resin, and the mixture is mixed; after the ammonia gas is released, the mixture is calcined to obtain a perfluorosulfonic acid resin with aminated branched ends; the perfluorosulfonic acid resin with aminated branched ends is then dissolved in a second organic solvent, 2,3-epoxypropyltrimethylammonium chloride is added, the mixture is heated, mixed, and centrifuged to obtain the modified perfluorosulfonic acid resin; The modified nano-silica and the modified perfluorosulfonic acid resin are mixed in a third organic solvent to obtain a casting solution; the casting solution is then formed into a film, dried, washed, and dried again to obtain the modified proton exchange membrane.
4. The method for preparing a modified proton exchange membrane according to claim 3, characterized in that: The preparation steps of the nano silicon dioxide are: firstly, tetraethyl silicate is added into the aqueous solution of pH value adjusting agent, and refluxed in water bath to obtain silicon dioxide seed dispersion liquid; then, the silicon dioxide seed dispersion liquid and tetraethyl silicate are added into the aqueous solution of pH value adjusting agent, and the steps are heated, mixed, and freeze-dried to obtain the nano silicon dioxide.
5. The method for preparing a modified proton exchange membrane according to claim 4, characterized in that: The pH regulator is selected from at least one of arginine, ammonia water and potassium carbonate; and / or, in the silica seed dispersion, the mass ratio of tetraethyl silicate, pH adjuster and water is (0.2-0.3):(0.1-0.2):100; And / or, the mass ratio of the silica seed dispersion and tetraethyl silicate added to the aqueous solution of the pH adjuster is (11-20):(2-3).
6. The method for preparing a modified proton exchange membrane according to claim 3, characterized in that: The concentration of the solution formed by dissolving 4-dimethylaminopyridine in the first organic solvent is 1-2 g / L, and the mass ratio of the 4-dimethylaminopyridine, nano-silica and 1,1-diphosphonic acid ethanol is 1: (4-6): (40-60); And / or, the calcination temperature condition is: calcination at 180-220° C. for 1-3 hours.
7. The method for preparing a modified proton exchange membrane according to claim 3, characterized in that: The mass ratio of the branched-end aminated perfluorosulfonic acid resin, the second organic solvent and 2,3-epoxypropyltrimethylammonium chloride is 1:(60-100):(0.3-0.4).
8. The method for preparing a modified proton exchange membrane according to claim 3, characterized in that: In the casting solution, the mass ratio of the modified perfluorosulfonic acid resin to the third organic solvent is (1-3):
40.
9. Use of the modified proton exchange membrane according to claim 1 or 2 in a fuel cell.
10. Use of the modified proton exchange membrane according to claim 1 or 2 in electrolysis of water.