A proton exchange membrane modified with dual inorganic filler doping

Abstract

This application relates to the field of fuel cells and discloses a proton exchange membrane modified with dual inorganic fillers, comprising a Nafion composite membrane matrix; CeO2 anchored on amine-functionalized cellulose nanofibers (CNFs), wherein CeO2 accounts for 2% to 5% of the total mass of the composite membrane; SiO2 nanoparticles are added, wherein SiO2 nanoparticles account for 0.5% to 2% of the total mass of the composite membrane; and Al2O3 nanoparticles are added, wherein Al2O3 nanoparticles account for 0.5% to 2% of the total mass of the composite membrane. This invention significantly improves the hardness and compressive strength of the composite membrane by anchoring CeO2 on amine-functionalized cellulose nanofibers (CNFs) and adding SiO2 and Al2O3 nanoparticles, thereby improving its service life and reliability. Simultaneously, the addition of carbon nanotubes (CNTs) greatly enhances the electrical conductivity of the composite membrane, which is crucial for improving the output efficiency and response speed of the fuel cell, directly affecting the overall energy conversion efficiency of the battery.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, specifically to a proton exchange membrane modified by doping with dual inorganic fillers. Background Technology

[0002] Fuel cell technology, as a clean energy conversion method, has attracted much attention due to its high energy efficiency and low environmental impact. In a fuel cell system, the proton exchange membrane (PEM) plays a crucial role, acting as an electrolyte medium that allows protons to pass through while blocking the flow of electrons. This process is directly related to the overall efficiency and energy output of the fuel cell.

[0003] Traditional proton exchange membranes often use perfluorosulfonic acid polymers such as Nafion N. These materials are industry standards due to their excellent chemical stability, good thermal stability, and outstanding ion conductivity. However, these traditional materials still have certain limitations in application under high temperature, high humidity, or chemically extreme conditions.

[0004] Mechanical stability issues: During long-term operation or under high temperature and high pressure environments, polymer films may deform, leading to performance degradation or even failure.

[0005] Cost issues: The high manufacturing cost of materials such as Nafion N limits their widespread adoption in large-scale commercial applications.

[0006] Operating temperature limit: The optimal operating temperature of traditional PEM is generally no more than 80°C. Temperatures above this will cause the membrane hydration layer to lose stability and reduce proton transport efficiency.

[0007] Therefore, this invention proposes a proton exchange membrane modified with dual inorganic filler doping to overcome the shortcomings of the prior art. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a proton exchange membrane modified by doping with dual inorganic fillers. This membrane not only improves the mechanical and thermal stability of traditional proton exchange membranes, but also significantly enhances their chemical stability and electrical conductivity.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a proton exchange membrane modified with dual inorganic filler doping, comprising the following components:

[0010] Nafion composite membrane matrix;

[0011] CeO2 anchored on amine-functionalized cellulose nanofibers, wherein CeO2 accounts for 2% to 5% of the total mass of the composite membrane;

[0012] SiO2 nanoparticles are added, wherein the SiO2 nanoparticles account for 0.5% to 2% of the total mass of the composite film;

[0013] Al2O3 nanoparticles are added, wherein the Al2O3 nanoparticles account for 0.5% to 2% of the total mass of the composite membrane.

[0014] Preferably, the amine-functionalized cellulose nanofibers account for 3% to 7% of the total mass of the Nafion composite membrane matrix.

[0015] Preferably, the particle size of CeO2, SiO2 and Al2O3 is 5 to 20 nanometers.

[0016] Preferably, a proton exchange membrane modified with dual inorganic filler doping further includes 0.3% to 3% carbon nanotubes to enhance the mechanical properties and electrical conductivity of the composite membrane.

[0017] Preferably, a proton exchange membrane modified with dual inorganic filler is characterized by comprising the following steps:

[0018] S1. Mix CeO2, SiO2 and Al2O3 nanoparticles with amine-functionalized cellulose nanofibers in a predetermined ratio to anchor these inorganic fillers on the surface of amine-functionalized cellulose nanofibers.

[0019] S2. The treated amine-functionalized cellulose nanofibers are suspended in Nafion solution at room temperature to form a uniform suspension.

[0020] S3. Pour the above suspension into a flatbed casting machine and cast the film under the condition of temperature control between 60°C and 150°C.

[0021] S4. After casting, the film is dried at room temperature for 24 hours, and then heat-treated in an oven at 80°C for 2 hours to complete the curing and performance optimization of the film.

[0022] Preferably, during the mixing process of the inorganic filler and amine-functionalized cellulose nanofibers, a high-speed stirrer is used to stir at a speed of 3000-3500 rpm for 0.8-1.2 hours to ensure uniform distribution of the filler.

[0023] Preferably, in the casting process of step S3, rollers for adjusting film thickness are used to control the thickness of the final product.

[0024] Preferably, in step S2, the preparation of the Nafion solution includes dissolving Nafion resin in a solvent containing a specific ratio of ethanol and deionized water to adjust the viscosity and rheological properties of the solution, wherein the ratio of ethanol to deionized water is 1:4 to 1:6.

[0025] Preferably, in step S4, after the oven heat treatment, a pressure treatment is further performed, wherein the pressure is 100 to 200 kPa, to enhance the structural stability of the membrane and reduce the formation of micropores.

[0026] Preferably, the proton exchange membrane serves as the electrolyte in the fuel cell.

[0027] This invention provides a proton exchange membrane modified with dual inorganic filler doping. It possesses the following beneficial effects:

[0028] 1. This invention significantly improves the hardness and compressive strength of the composite membrane by anchoring CeO2 on amine-functionalized cellulose nanofibers (CNF) and adding SiO2 and Al2O3 nanoparticles. This structural reinforcement not only makes the membrane physically stronger but also effectively resists mechanical stress and wear that may occur during fuel cell operation, thereby improving its service life and reliability.

[0029] 2. The addition of carbon nanotubes (CNTs) in this invention significantly enhances the electrical conductivity of the composite membrane. Due to their unique one-dimensional structure and excellent electronic conductivity, CNTs can form an effective conductive network, promoting rapid proton transport. This is crucial for improving the output efficiency and response speed of fuel cells, directly impacting the overall energy conversion efficiency of the battery.

[0030] 3. The precise temperature control during the heat treatment process and the subsequent baking step of this invention significantly improve the thermal stability of the composite film. By performing thermosetting at a controlled temperature, not only is the microstructure of the film optimized, but its performance stability under high-temperature operating conditions is also enhanced. This treatment reduces performance degradation caused by temperature fluctuations during long-term use.

[0031] 4. The introduction of CeO2 in this invention brings excellent chemical stability to the composite membrane. These materials have strong antioxidant and chemical corrosion resistance properties, effectively protecting the membrane from strong oxidants and corrosive chemicals during fuel cell operation. Improving chemical stability is key to ensuring consistent membrane performance under various chemical environments.

[0032] 5. In this invention, precise solvent ratios and stirring conditions ensure the uniform distribution of inorganic fillers on CNF. Uniform distribution is a prerequisite for achieving consistent overall membrane performance and directly affects the quality and performance of the prepared membrane. Furthermore, this optimized solution ratio and stirring process helps reduce material waste and costs during production. Attached Figure Description

[0033] Figure 1 This is a diagram of a proton exchange membrane modified with dual inorganic filler doping. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example:

[0036] Please see the appendix Figure 1 :

[0037] Example 1: Proton exchange membrane modified by dual inorganic filler doping under standard operating conditions

[0038] step:

[0039] CeO2, SiO2 and Al2O3 nanoparticles were mixed with amine-functionalized cellulose nanofibers at proportions of 2%, 1%, and 1%, respectively.

[0040] Stir at 3000 rpm for 1 hour to ensure a uniform mixture.

[0041] The mixed amine-functionalized cellulose nanofibers were suspended in an aqueous solution containing 15% Nafion in ethanol and deionized water.

[0042] The casting process is carried out at 60°C. The suspension is poured onto the casting plate using a casting machine, and the thickness is controlled at 100 micrometers.

[0043] After drying for 24 hours, the product is heat-treated at 80°C for 2 hours and then compressed under 100 kPa pressure.

[0044] In summary, this embodiment demonstrates a method for preparing dual inorganic filler-doped modified proton exchange membranes under standardized production conditions, suitable for large-scale production, ensuring consistent and reliable product quality.

[0045] Example 2: Proton Exchange Membrane for Enhanced High-Temperature Fuel Cells

[0046] step:

[0047] The proportion of CeO2 was increased to 4% and mixed with amine-functionalized cellulose nanofibers.

[0048] Stir at 3500 rpm for 1.2 hours to achieve better nanoparticle dispersion.

[0049] The suspension preparation is the same as in Example 1.

[0050] The film was cast at 70°C, and the film thickness was adjusted to 150 micrometers to provide greater mechanical stability.

[0051] The product undergoes a prolonged heat treatment (3 hours) followed by post-treatment at a pressure of 200 kPa.

[0052] In summary, this embodiment is designed for fuel cells operating in high-temperature environments. The increased proportion of inorganic fillers and the thickened membrane provide greater structural stability and long-term durability.

[0053] Example 3: Low-cost, small-batch laboratory-grade sample preparation

[0054] step:

[0055] Preliminary mixing was performed using a low proportion of inorganic fillers (1% each).

[0056] Stir at 2800 rpm for 0.8 hours.

[0057] The suspension was prepared using a low concentration of Nafion solution (10%).

[0058] The film is cast at 100°C with a thickness of 50 micrometers, which is suitable for laboratory testing.

[0059] The heat treatment lasted for 1 hour at 80°C and 50 kPa pressure.

[0060] In summary, this embodiment is suitable for the R&D stage or small-scale trials. It reduces material costs and preparation difficulty, and facilitates rapid iteration and testing of new formulations.

[0061] Example 4: Proton exchange membrane for direct methanol fuel cells

[0062] step:

[0063] The proportion of carbon nanotubes (CNTs) was increased to 3% to enhance electrical conductivity.

[0064] The mixing and stirring steps are the same as in Example 1.

[0065] The ion exchange capacity of the membrane was enhanced by using a high concentration of Nafion solution (20%).

[0066] The casting temperature is maintained at 120℃, and the film thickness is controlled at 120 micrometers.

[0067] Long-term heat treatment and high-pressure post-treatment are used to improve chemical stability and mechanical strength.

[0068] In summary, the exchange membrane designed specifically for direct methanol fuel cells has been improved by increasing the CNT ratio and optimizing the Nafion content to accommodate higher chemical activity and operational requirements.

[0069] Example 5: Outdoor proton exchange membrane with strong environmental adaptability

[0070] step:

[0071] Increase the proportion of Al2O3 and SiO2 to 2% each to improve environmental resistance.

[0072] Mix at high speed (3500 rpm) for 1.2 hours.

[0073] Prepare a suspension using a diluted Nafion solution (12%).

[0074] Casting is performed at a lower temperature (60°C) to reduce thermal stress.

[0075] The structure was optimized by long-term heat treatment at low temperature (60℃) and under low pressure (100kPa).

[0076] In summary, this membrane is suitable for use in outdoor environments with large temperature differences. This embodiment improves the environmental adaptability of the membrane by enhancing the material composition that is resistant to environmental corrosion and optimizing the low-temperature processing technology.

[0077] Summary:

[0078] These embodiments demonstrate the diverse applications of the proton exchange membrane of the present invention, ranging from small-scale laboratory samples to solutions optimized for specific fuel cells. Each embodiment specifically adjusts the material ratios, preparation conditions, and post-processing steps to adapt to different application requirements and environmental conditions. Through these embodiments, the proton exchange membrane of the present invention demonstrates its broad applicability and superior performance in the field of fuel cells.

[0079] Comparative experiment:

[0080] The existing technical solution consists of:

[0081] Existing technologies primarily use unmodified NafionN membranes as proton exchange membranes. NafionN is made from perfluorosulfonic acid polymers and has good chemical stability and electrical conductivity, but it is susceptible to degradation of mechanical and chemical properties under high temperatures and extreme environments.

[0082] Experiment 1: Comparison of mechanical properties and pressure resistance

[0083] Objective: To evaluate and compare the differences between the present invention and the prior art in terms of mechanical strength and compressive strength.

[0084] method:

[0085] Mechanical strength tests (such as tensile tests) and compression tests were conducted on the unmodified Nafion N membrane and the composite membrane proposed in this invention.

[0086] parameter:

[0087] Tensile strength: The maximum force (MPa) that a membrane can withstand before it breaks.

[0088] Elongation: The percentage of elongation at the point of breakage.

[0089] Compressive strength: the degree of deformation (mm) and stress (MPa) during a compression test.

[0090] Experimental data:

[0091] Membrane type Test type Compression / Tension (MPa) Elongation / Degree of Deformation (%) Pure Nafion stretching 25 200 Pure Nafion compression 1 1.2 The membrane of the present invention stretching 35 250 The membrane of the present invention compression 1.5 0.8

[0092] This experiment clearly demonstrates that the composite membrane of this invention outperforms the pure Nafion membrane in terms of mechanical properties and pressure resistance. The strategy of anchoring CeO2 and adding SiO2 and Al2O3 nanoparticles significantly improves the hardness and pressure resistance of the composite membrane. The addition of these inorganic fillers effectively enhances the structural integrity of the membrane, making it more resistant to physical stresses under long-term use and high-pressure environments. Experimental data show that the membrane of this invention deforms significantly less than the pure Nafion membrane under the same pressure, proving that its application in fuel cells will provide higher reliability and durability.

[0093] Experiment 2: Comparison of electrical conductivity and temperature stability

[0094] Objective: To compare the electrical conductivity of the composite membrane of the present invention with that of the pure Nafion membrane, as well as the change in conductivity at different temperatures.

[0095] method:

[0096] The resistivity of different films at room temperature, 50°C and 80°C was measured using a four-point probe method.

[0097] parameter:

[0098] Electrical conductivity: S / m, measured at different temperatures.

[0099] Experimental data:

[0100] Membrane type Temperature (°C) Electrical conductivity (S / m) Pure Nafion 25 0.1 Pure Nafion 80 0.14 The membrane of the present invention 25 0.15 The membrane of the present invention 80 0.25

[0101] Comparative experiments on electrical conductivity show that the membrane of this invention exhibits higher conductivity than the pure Nafion membrane under both room temperature and high temperature conditions. The added carbon nanotubes (CNTs) form a highly efficient conductive network in the membrane, significantly enhancing proton transport efficiency. Particularly in high-temperature testing, the conductivity of the membrane of this invention is significantly improved, indicating that its microstructure is optimized and it maintains better performance stability under high-temperature operating conditions. This makes the membrane of this invention particularly suitable for fuel cell systems requiring high output efficiency and fast response.

[0102] Experiment 3: Comparison of Chemical Stability and Corrosion Resistance

[0103] Objective: To evaluate the chemical stability of the composite membrane of the present invention and the pure Nafion membrane in the face of strong oxidants and corrosive chemicals.

[0104] method:

[0105] The two types of membranes were immersed in high-concentration chloride solution and sulfuric acid solution, respectively.

[0106] parameter:

[0107] Soaking time: 0, 24, 48, 72 hours.

[0108] Mass loss: %, representing the change in mass after chemical corrosion.

[0109] Surface degradation: Microscopic evaluation of surface structural changes following chemical etching.

[0110] Experimental data:

[0111] Membrane type Solution type Soaking time (one hour) Quality loss (%) Surface degradation score Pure Nafion chloride 72 2 moderate Pure Nafion sulfuric acid 72 1.8 moderate The membrane of the present invention chloride 72 0.8 slight The membrane of the present invention sulfuric acid 72 0.5 weak

[0112] In environments exposed to strong oxidants and corrosive chemicals, the composite membrane of this invention exhibits superior chemical stability and corrosion resistance. In experiments, the membrane of this invention showed significantly lower mass loss and surface degradation when immersed in high-concentration chloride and sulfuric acid solutions compared to pure Nafion membranes. This is attributed to the introduction of CeO2, which not only enhances the membrane's antioxidant properties but also improves its resistance to chemical corrosion. These results demonstrate that the membrane of this invention can maintain its performance in more demanding chemical environments and is suitable for various chemically sensitive applications.

[0113] Summary

[0114] Through the three comparative experiments described above, we can clearly see that the dual-inorganic filler-doped modified proton exchange membrane provided by this invention exhibits significant improvements in mechanical properties, electrical conductivity, and chemical stability compared to existing technologies. These improvements make the membrane of this invention more suitable for widespread application in modern fuel cell technology, especially in applications requiring high performance and adaptability to extreme environments, providing a more reliable and efficient solution.

[0115] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A proton exchange membrane modified with dual inorganic filler doping, characterized in that, It contains the following components: Nafion composite membrane matrix; CeO2 anchored on amine-functionalized cellulose nanofibers, wherein CeO2 accounts for 2% to 5% of the total mass of the composite membrane; SiO2 nanoparticles are added, wherein the SiO2 nanoparticles account for 0.5% to 2% of the total mass of the composite film; Al2O3 nanoparticles are added, wherein the Al2O3 nanoparticles account for 0.5% to 2% of the total mass of the composite membrane; The amine-functionalized cellulose nanofibers account for 3% to 7% of the total mass of the Nafion composite membrane matrix; The particle sizes of CeO2, SiO2, and Al2O3 are all 5 to 20 nanometers.

2. The proton exchange membrane modified with dual inorganic filler according to claim 1, characterized in that, Further, it includes the addition of 0.3% to 3% carbon nanotubes to enhance the mechanical properties and electrical conductivity of the composite membrane.

3. The method for preparing a proton exchange membrane modified with dual inorganic filler according to any one of claims 1-2, characterized in that, Includes the following steps: S1. Mix CeO2, SiO2 and Al2O3 nanoparticles with amine-functionalized cellulose nanofibers in a predetermined ratio to anchor these inorganic fillers on the surface of amine-functionalized cellulose nanofibers. S2. The treated amine-functionalized cellulose nanofibers are suspended in Nafion solution at room temperature to form a uniform suspension. S3. Pour the above suspension into a flatbed casting machine and cast the film under the condition of temperature control between 60°C and 150°C. S4. After casting, the film is dried at room temperature for 24 hours, and then heat-treated in an oven at 80°C for 2 hours to complete the curing and performance optimization of the film.

4. The method for preparing a proton exchange membrane modified with dual inorganic filler according to claim 3, characterized in that, During the mixing process of the inorganic filler and amine-functionalized cellulose nanofibers, a high-speed stirrer is used to stir at a speed of 3000-3500 rpm for 0.8-1.2 hours to ensure uniform distribution of the filler.

5. The method for preparing a proton exchange membrane modified with dual inorganic filler according to claim 3, characterized in that, In the casting process of step S3, rollers for adjusting film thickness are used to control the thickness of the final product.

6. The method for preparing a proton exchange membrane modified with dual inorganic filler according to claim 3, characterized in that, In step S2, the preparation of the Nafion solution includes dissolving Nafion resin in a solvent containing a specific ratio of ethanol and deionized water to adjust the viscosity and rheological properties of the solution, wherein the ratio of ethanol to deionized water is 1:4 to 1:

6.

7. The method for preparing a proton exchange membrane modified with dual inorganic filler according to claim 3, characterized in that, In step S4, after the oven heat treatment, a pressure treatment is further performed, with a pressure of 100 to 200 kPa, to enhance the structural stability of the membrane and reduce the formation of micropores.

8. A proton exchange membrane according to any one of claims 1-2 as an electrolyte in a fuel cell.

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