High-temperature proton exchange membrane as well as preparation method and application thereof
By using casting method and ionic liquid modification technology in the proton exchange membrane, the compatibility of inorganic particles and polybenzimidazole is improved, and the problem of degradation in the performance of existing proton exchange membranes in medium and high temperature environments is solved, and a higher acid doping level and conductivity are achieved.
Patent Information
- Application Number
- CN202510140634.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-07
- Publication Date
- 2025-05-09
AI Technical Summary
The existing proton exchange membranes have poor compatibility with inorganic particles in medium and high temperature environments, resulting in a degradation of performance.
A composite film of modified titanium dioxide and polybenzimidazole was prepared by casting method, and inorganic nanoparticles were modified by ionic liquid to form a silicon cross-linking network to improve the compatibility of nanoparticles and polybenzimidazole.
The acid doping level, conductivity and mechanical properties of the proton exchange membrane are improved, and the performance and stability of the fuel cell are enhanced.
Smart Images
Figure CN119965310A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of fuel cells, and in particular to a high-temperature proton exchange membrane and a preparation method and application thereof. Background Art
[0002] Proton exchange membrane fuel cells (PEMFCs) are widely used as clean energy conversion devices, especially in vehicles and stationary and portable power generation systems. They have strong characteristics, such as simple cooling system, easy heat and water management, and no pollution emissions. In high-temperature proton exchange membrane fuel cells, the proton exchange membrane is an important component and plays a key role. It is mainly responsible for the internal proton transmission and fuel isolation, and can also be used as a barrier to separate raw gas and product.
[0003] At present, polybenzimidazole doped with phosphoric acid has satisfactory performance in medium and high temperature environments and is widely used and studied for use in fuel cells. Remarkably, phosphoric acid (PA)-doped polybenzimidazole generally has better performance and stability than other polymer membranes, such as polyimide, polyethersulfone, etc., because PA is used as a proton carrier, so that PA-doped polybenzimidazole can work at high temperatures without dehydration. In order to further improve the performance of PA-doped polybenzimidazole membranes, inorganic particles can be doped, but the compatibility between inorganic particles and organic matrices is poor, which will reduce the performance of proton exchange membranes. Therefore, how to improve the compatibility between inorganic particles and organic matrices is an urgent problem to be solved. Summary of the invention
[0004] The purpose of the present invention is to provide a high-temperature proton exchange membrane and a preparation method and application thereof, so as to solve the above-mentioned problems existing in the existing proton exchange membranes.
[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:
[0006] The present invention provides a method for preparing a high-temperature proton exchange membrane, comprising the following steps:
[0007] 1-methylimidazole and 3-chloropropyltriethoxysilane are mixed and reacted to obtain 1-methyl-3-[(triethoxysilyl)propyl]imidazole chloride;
[0008] Mixing 1-methyl-3-[(triethoxysilyl)propyl]imidazolium chloride with a suspension of titanium dioxide for modification to obtain modified titanium dioxide;
[0009] The modified titanium dioxide, polybenzimidazole powder and solvent are mixed and then cast on a substrate to obtain a high-temperature proton exchange membrane.
[0010] Preferably, in the above-mentioned method for preparing a high-temperature proton exchange membrane, the volume ratio of 1-methylimidazole to 3-chloropropyltriethoxysilane is 1-3:4-6.
[0011] Preferably, in the above-mentioned method for preparing a high-temperature proton exchange membrane, the reaction is carried out under a protective atmosphere; the reaction temperature is 50 to 100° C.; and the reaction time is 10 to 20 hours.
[0012] Preferably, in the above-mentioned method for preparing a high-temperature proton exchange membrane, the mass ratio of titanium dioxide in the suspension of 1-methyl-3-[(triethoxysilyl)propyl]imidazole chloride and titanium dioxide is 1-2:1-2.
[0013] Preferably, in the above-mentioned method for preparing a high-temperature proton exchange membrane, the modification is carried out under a protective atmosphere; the modification temperature is 50 to 100° C.; and the modification time is 10 to 20 hours.
[0014] Preferably, in the above method for preparing a high-temperature proton exchange membrane, the modified titanium dioxide, polybenzimidazole powder and solvent are mixed for 10 to 20 hours.
[0015] Preferably, in the above method for preparing a high-temperature proton exchange membrane, the mass of the modified titanium dioxide is 1 to 20% of the mass of the polybenzimidazole powder.
[0016] Preferably, in the above-mentioned method for preparing a high-temperature proton exchange membrane, the casting further includes soaking in alkaline solution and drying.
[0017] The present invention also provides a high-temperature proton exchange membrane prepared by a method for preparing the high-temperature proton exchange membrane.
[0018] The present invention also provides an application of a high-temperature proton exchange membrane in a fuel cell.
[0019] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:
[0020] (1) The present invention adopts a casting method to prepare a composite membrane of inorganic particles and polybenzimidazole, so that the phosphoric acid transfer channel is increased, and the porous nanoparticles can store phosphoric acid to a greater extent, thereby improving the acid doping level.
[0021] (2) In the present invention, ionic liquid is used to modify inorganic nanoparticles. The ionic liquid combines with the hydroxyl groups on the surface of the nanoparticles to form a silicon cross-linked network, which changes the surface energy of the nanoparticles, so that they can better match the polar and non-polar groups of polybenzimidazole, improve the surface affinity of the nanoparticles and thus reduce the aggregation of the particles, making the nanoparticles well compatible with polybenzimidazole, and can effectively improve the mechanical properties and open circuit voltage of the proton exchange membrane.
[0022] (3) The reaction conditions of the present invention are mild, the operation steps are simple, and it is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art are briefly introduced below.
[0024] Figure 1 are SEM images of the high temperature proton exchange membranes of Examples 1 to 4 and Comparative Example 1; wherein (a) is a surface SEM image of Comparative Example 1, (b) is a surface SEM image of Example 1, (c) is a surface SEM image of Example 2, (d) is a surface SEM image of Example 3, (e) is a surface SEM image of Example 4, (f) is a cross-sectional SEM image of Comparative Example 1, (g) is a cross-sectional SEM image of Example 1, (h) is a cross-sectional SEM image of Example 2, (i) is a cross-sectional SEM image of Example 3, and (j) is a cross-sectional SEM image of Example 4;
[0025] Figure 2 The acid doping level results of the high temperature proton exchange membranes of Examples 1 to 4 and Comparative Example 1;
[0026] Figure 3 The conductivity results of the high temperature proton exchange membranes of Examples 1 to 4 and Comparative Example 1;
[0027] Figure 4 The performance test results of a single fuel cell made from the high temperature proton exchange membranes of Examples 1 to 4 and Comparative Example 1;
[0028] Figure 5 The long-term stability results of a single fuel cell made of the high-temperature proton exchange membrane of Example 3 are shown in FIG. DETAILED DESCRIPTION
[0029] The present invention provides a method for preparing a high-temperature proton exchange membrane, comprising the following steps:
[0030] 1-methylimidazole and 3-chloropropyltriethoxysilane are mixed and reacted to obtain 1-methyl-3-[(triethoxysilyl)propyl]imidazole chloride;
[0031] Mixing 1-methyl-3-[(triethoxysilyl)propyl]imidazolium chloride with a suspension of titanium dioxide for modification to obtain modified titanium dioxide;
[0032] The modified titanium dioxide, polybenzimidazole powder and solvent are mixed and then cast on a substrate to obtain a high-temperature proton exchange membrane.
[0033] In the present invention, the volume ratio of 1-methylimidazole to 3-chloropropyltriethoxysilane is preferably 1-3:4-6, more preferably 1-2:4-5, and more preferably 1:4.
[0034] In the present invention, the reaction is preferably carried out under a protective atmosphere; the reaction temperature is preferably 50-100°C, more preferably 80-100°C, more preferably 100°C; the reaction time is preferably 10-20h, more preferably 15-20h, more preferably 20h.
[0035] In the present invention, the reaction further comprises centrifugation, washing and vacuum drying.
[0036] In the present invention, the washing is preferably performed twice with diethyl ether; the vacuum drying temperature is preferably 50 to 100°C, more preferably 80 to 100°C, and more preferably 100°C; the vacuum drying time is preferably 10 to 20 hours, more preferably 15 to 20 hours, and more preferably 20 hours.
[0037] In the present invention, the mass ratio of titanium dioxide in the suspension of 1-methyl-3-[(triethoxysilyl)propyl]imidazolium chloride and titanium dioxide is preferably 1-2:1-2, more preferably 1:1-2, and more preferably 1:2.
[0038] In the present invention, the titanium dioxide is preferably P25.
[0039] In the present invention, the titanium dioxide suspension is preferably a suspension of titanium dioxide in chloroform; the dosage ratio of the titanium dioxide to chloroform is preferably 1-2 g: 20-100 mL, more preferably 1-2 g: 50 mL, and more preferably 1.5 g: 50 mL.
[0040] In the present invention, the modification is carried out under a protective atmosphere; the modification temperature is preferably 50-100°C, more preferably 80-100°C, more preferably 100°C; the modification time is preferably 10-20h, more preferably 15-20h, more preferably 20h.
[0041] In the present invention, the modified titanium dioxide, polybenzimidazole powder and solvent are mixed for preferably 10 to 20 hours, more preferably 15 to 20 hours, and even more preferably 20 hours.
[0042] In the present invention, the modified titanium dioxide, polybenzimidazole powder and solvent are mixed in a method of: dissolving the polybenzimidazole powder in the solvent, and then adding the modified titanium dioxide.
[0043] In the present invention, the solvent is preferably N,N-dimethylacetamide (DMAC).
[0044] In the present invention, the mass of the modified titanium dioxide is preferably 1 to 20% of the mass of the polybenzimidazole powder, more preferably 5 to 20%, and even more preferably 15%.
[0045] In the present invention, the total mass of the modified titanium dioxide and polybenzimidazole powder and the amount of the solvent are preferably 0.3-1 g:5 mL, more preferably 0.3-0.5 g:5 mL, and more preferably 0.4 g:5 mL.
[0046] In the present invention, the substrate is preferably a glass plate.
[0047] In the present invention, the pouring further includes soaking in alkali solution and drying.
[0048] In the present invention, the alkali solution is preferably a 1.15 mol / L NaOH solution; the soaking time is preferably 10 to 20 hours, more preferably 15 to 20 hours, and more preferably 20 hours.
[0049] In the present invention, the drying temperature is preferably 50-100°C, more preferably 80-100°C, and more preferably 100°C; the drying time is preferably 10-20h, more preferably 15-20h, and more preferably 20h.
[0050] The present invention also provides a high-temperature proton exchange membrane prepared by a method for preparing the high-temperature proton exchange membrane.
[0051] The present invention also provides an application of a high-temperature proton exchange membrane in a fuel cell.
[0052] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0053] Example 1
[0054] This embodiment provides a high-temperature proton exchange membrane, and the preparation method thereof comprises the following steps:
[0055] (1) 5 mL of 1-methylimidazole and 20 mL of 3-chloropropyltriethoxysilane were heated at 100° C. for 20 h under a nitrogen atmosphere to react; the resulting solution was centrifuged, washed twice with ether, and vacuum dried at 100° C. for 20 h to obtain 1-methyl-3-[(triethoxysilyl)propyl]imidazole chloride;
[0056] (2) 1.5 g of 1-methyl-3-[(triethoxysilyl)propyl]imidazole chloride was added to a suspension of 3 g of P25 in 100 mL of chloroform, and the mixture was heated at 100° C. for 20 h under a nitrogen atmosphere to react. The product was centrifuged and washed with chloroform to remove unreacted 1-methyl-3-[(triethoxysilyl)propyl]imidazole chloride to obtain modified P25;
[0057] (3) dissolving polybenzimidazole (PBI) powder in DMAC, and then adding modified P25 so that the total mass ratio of PBI powder and modified P25 to DMAC is 0.4 g:5 mL, and the mass of modified P25 is 5% of the mass of PBI powder. After magnetic stirring at room temperature for 20 hours, a mixed solution is obtained;
[0058] (4) The mixed solution was uniformly poured on a glass plate, then immersed in a 1.15 mol / L NaOH solution for 20 h, and then dried at 100° C. for 20 h to obtain a 5 μm high-temperature proton exchange membrane.
[0059] Example 2
[0060] This embodiment provides a high-temperature proton exchange membrane, which is specifically referred to in Embodiment 1, except that the mass of the modified P25 in step (3) is 10% of the mass of the PBI powder.
[0061] Example 3
[0062] This embodiment provides a high-temperature proton exchange membrane, which is specifically referred to in Embodiment 1, except that the mass of the modified P25 in step (3) is 15% of the mass of the PBI powder.
[0063] Example 4
[0064] This embodiment provides a high-temperature proton exchange membrane, which is specifically referred to in Embodiment 1, except that the mass of the modified P25 in step (3) is 20% of the mass of the PBI powder.
[0065] Comparative Example 1
[0066] This comparative example provides a high-temperature proton exchange membrane, which is specifically referred to in Example 1, except that it does not contain modified P25, that is, steps (1) to (2) are not performed, and modified P25 is not added in step (3).
[0067] The high temperature proton exchange membranes of Examples 1 to 4 and Comparative Example 1 were characterized by SEM. Figure 1 As shown. Figure 1 It can be seen that the surface of the film without nanoparticles is smooth. As the amount of nanoparticles doped increases, particles appear on the surface of the film, and the number increases with the increase of doping amount, but no cracks and perforations are observed, indicating that the nanoparticles and PBI have relatively good compatibility. With the addition of nanoparticles, faults and porosity can be observed in the cross section of the film. This is because the addition of nanoparticles destroys the structure between PBI, causing multi-layer phenomena in the film, which is conducive to the adsorption and storage of PA.
[0068] The high temperature proton exchange membranes of Examples 1 to 4 and Comparative Example 1 were immersed in a phosphoric acid solution at 50 to 100° C. until saturated, and then placed on a glass plate and dried at 50 to 100° C. for 1 to 5 hours, and subsequent acid doping levels, conductivity, single fuel cell performance and long-term stability were tested.
[0069] The preparation method of a single fuel cell is as follows: a high-temperature proton exchange membrane soaked in phosphoric acid is assembled into a high-temperature fuel cell under no back pressure and back humidity conditions, 1 mg cm -2 Pt / C was used as gas diffusion electrode, and the cathode and anode test gas was O 2 and H 2 , O 2 The flow rate is 160mLmin -1 , H 2 The flow rate is 80 mL min -1 , tested at 140℃ without water and back pressure.
[0070] The results of the acid doping levels of the high temperature proton exchange membranes of Examples 1 to 4 and Comparative Example 1 are as follows: Figure 2 As shown. Figure 2 It can be seen that the addition of nanoparticles has an effect on the acid doping level of the composite film, and the acid doping levels of Examples 1 to 4 are significantly greater than that of Comparative Example 1. As the content of nanoparticles increases, the acid doping levels of Examples 1 to 4 also gradually increase, which is because more nanoparticles adsorb PA and have a stronger affinity for PA. However, when the content of nanoparticles exceeds 20wt%, the PA doping level decreases because more nanoparticles form agglomerations, the free volume decreases, and the absorption of PA is inhibited.
[0071] The conductivity results of the high temperature proton exchange membranes of Examples 1 to 4 and Comparative Example 1 are as follows: Figure 3 As shown. Figure 3It can be seen that the proton conductivity of all membranes increases with the increase of temperature. At 140°C, the proton conductivity of Example 3 is the highest among all membranes. The higher proton conductivity is due to the uniform dispersion of nanoparticles, which produces a relatively large specific surface area and a greater degree of adsorption of PA. The proton conductivity of Example 4 decreases because a large number of nanoparticles aggregate, resulting in discontinuous proton hopping paths, which hinders the transport of protons.
[0072] The performance results of the single fuel cell made from the high temperature proton exchange membranes of Examples 1 to 4 and Comparative Example 1 are as follows: Figure 4 As shown. Figure 4 It can be seen that the maximum power density of Example 3 is up to 668mW / cm 2 , the nanoparticles adsorb more free PA in the pores and at the same time establish hydrogen bonds to increase the proton transfer channels.
[0073] The long-term stability results of a single fuel cell made from the high-temperature proton exchange membrane of Example 3 are as follows: Figure 5 As shown. Figure 5 It can be seen that the voltage drop of Example 3 after 110h at 140℃ is only 113μV h -1 , This is due to the leaching of PA, the resistance of the membrane increases, and the voltage decreases slowly.
[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for preparing a high-temperature proton exchange membrane, characterized in that: The following steps are involved: 1-methylimidazole and 3-chloropropyltriethoxysilane are mixed and reacted to obtain 1-methyl-3-[(triethoxysilyl)propyl]imidazole chloride; Mixing 1-methyl-3-[(triethoxysilyl)propyl]imidazolium chloride with a suspension of titanium dioxide for modification to obtain modified titanium dioxide; The modified titanium dioxide, polybenzimidazole powder and solvent are mixed and then cast on a substrate to obtain a high-temperature proton exchange membrane.
2. The method for preparing a high temperature proton exchange membrane according to claim 1, characterized in that: The volume ratio of the 1-methylimidazole to the 3-chloropropyltriethoxysilane is 1-3:4-6.
3. The method for preparing a high temperature proton exchange membrane according to claim 2, characterized in that: The reaction is carried out under a protective atmosphere; the reaction temperature is 50-100° C.; and the reaction time is 10-20 hours.
4. The method for preparing a high temperature proton exchange membrane according to claim 1 or 2, characterized in that: The mass ratio of titanium dioxide in the suspension of 1-methyl-3-[(triethoxysilyl)propyl]imidazole chloride and titanium dioxide is 1-2:1-2.
5. The method for preparing a high temperature proton exchange membrane according to claim 4, characterized in that: The modification is carried out under a protective atmosphere; the modification temperature is 50 to 100° C.; and the modification time is 10 to 20 hours.
6. The method for preparing a high temperature proton exchange membrane according to claim 5, characterized in that: The modified titanium dioxide, polybenzimidazole powder and solvent are mixed for 10 to 20 hours.
7. A method for preparing a high temperature proton exchange membrane according to claim 1, 5 or 6, characterized in that: The mass of the modified titanium dioxide is 1-20% of the mass of the polybenzimidazole powder.
8. The method for preparing a high temperature proton exchange membrane according to claim 7, characterized in that: After the pouring, the process also includes soaking in alkali solution and drying.
9. A high-temperature proton exchange membrane obtained by the method for preparing a high-temperature proton exchange membrane according to any one of claims 1 to 8.
10. Use of a high-temperature proton exchange membrane as claimed in claim 9 in a fuel cell.