A cross-linked polyvinylpyrrolidone-polyether sulfone high-temperature proton exchange membrane, a preparation method thereof, a membrane electrode and a fuel cell

Abstract

The application discloses a cross-linked polyvinylpyrrolidone-polyether sulfone high-temperature proton exchange film, a preparation method thereof, a film electrode and a fuel cell. The cross-linked polyvinylpyrrolidone-polyether sulfone high-temperature proton exchange film comprises a film main material and a cross-linking agent. The film main material comprises polyvinylpyrrolidone and polyether sulfone. The cross-linking agent is surface brominated tin dioxide. The added mass ratio of the cross-linking agent is 1% to 4% based on the film main material. The prepared cross-linked polyvinylpyrrolidone-polyether sulfone high-temperature proton exchange film has high proton conductivity and high mechanical strength, and also has good oxidation resistance, and has a wide application prospect in high-temperature proton exchange film fuel cells.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, specifically to a cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange membrane, its preparation method, membrane electrode, and fuel cell. Background Technology

[0002] With the widespread use of fossil fuels, global environmental pollution and energy shortages are becoming increasingly serious. Fuel cells, as a highly efficient and clean energy conversion technology, are gradually attracting widespread attention. Among them, proton exchange membrane fuel cells (PEMFCs) have received widespread attention and rapid development due to their advantages such as cleanliness and efficiency, fast start-up and response speed, high power density, low noise, wide fuel adaptability, long lifespan, and high reliability. Based on different operating temperatures, PEMFCs are divided into high-temperature PEMFCs (operating temperature 120℃~200℃) and low-temperature PEMFCs (operating temperature <80℃). Compared with low-temperature PEMFCs, high-temperature PEMFCs (HT-PEMFCs) have advantages such as high cell efficiency, simple hydrothermal management, and strong tolerance to CO catalysts. As the core component of high-temperature PEMFCs, the performance of the high-temperature proton exchange membrane has a significant impact on the efficiency, lifespan, and cost of the fuel cell.

[0003] Polyvinylpyrrolidone (PVP) is a basic polymer containing nitrogen-containing heterocyclic rings. The amide groups in its unit structure enable PVP to be highly soluble in organic solvents. The basic N and O atoms in the PVP unit can serve as adsorption centers for phosphoric acid (PA), anchoring PA within the polymer network structure and facilitating proton conduction. However, PVP has poor mechanical strength and cannot form films alone. Therefore, it needs to be composited with a framework material with good mechanical properties, such as polyethersulfone (PES), to improve the mechanical strength of the film.

[0004] However, achieving a balance between proton conductivity and mechanical strength remains challenging for PA-doped polyvinylpyrrolidone-polyethersulfone (PVP-PES) composite membranes. In recent years, researchers have attempted to improve both proton conductivity and mechanical strength through crosslinking and inorganic doping modifications, such as doping with phosphotungstic acid, carbon dots, and boron nitride. However, common crosslinking agents can lead to overly tight polymer chains in the composite membrane, reducing PA adsorption and hindering proton conduction. Existing inorganic fillers have poor compatibility with polymers, resulting in poor dispersion and easy aggregation in the composite membrane, which can damage its structure and reduce its mechanical strength. These factors limit the performance improvement of modified PVP-PES composite membranes. Summary of the Invention

[0005] The purpose of this invention is to provide a cross-linked polyvinylpyrrolidone-polyethersulfone proton exchange membrane prepared using a surface-brominated tin dioxide cross-linking agent, so as to improve the mechanical strength and proton conductivity of the proton exchange membrane.

[0006] To achieve the above objectives, the present invention provides a cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange membrane, characterized in that it comprises a membrane main material and a cross-linking agent, wherein the membrane main material comprises polyvinylpyrrolidone and polyethersulfone, and the cross-linking agent is surface-brominated tin dioxide, wherein the mass ratio of the cross-linking agent added is 1% to 4% based on the membrane main material.

[0007] Furthermore, the mass ratio of polyvinylpyrrolidone to polyethersulfone is (5-7):(3-5).

[0008] The present invention also provides a method for preparing the above-mentioned cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange membrane, comprising:

[0009] Step S1: Dissolve polyvinylpyrrolidone and polyethersulfone in a first polar aprotic solvent to obtain a homogeneous solution;

[0010] Step S2: Disperse the surface tin dioxide bromide in a second polar aprotic solvent to obtain a crosslinking agent solution;

[0011] Step S3: After the homogeneous solution and the crosslinking agent solution are mixed evenly, a film is formed by casting. The first polar aprotic solvent and the second polar aprotic solvent are removed by heating and evaporation to form a blend film.

[0012] Step S4: Immerse the blended membrane in phosphoric acid to obtain a cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange membrane.

[0013] Furthermore, the first polar aprotic solvent and the second polar aprotic solvent may be the same or different.

[0014] Furthermore, the first polar aprotic solvent and the second polar aprotic solvent are each independently selected from any one or more of N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, or dimethyl sulfoxide.

[0015] Furthermore, in step S3, the homogenized solution and the crosslinking agent solution are mixed uniformly at 60°C to 90°C.

[0016] Furthermore, in step S3, the heating and evaporation temperature is 60℃~80℃, and the temperature is maintained for 5h~15h.

[0017] Furthermore, in step S4, the concentration of phosphoric acid is 70wt% to 98wt%, and the soaking time is 15h to 30h.

[0018] The present invention also provides a membrane electrode comprising the above-described cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange membrane.

[0019] The present invention also provides a fuel cell comprising the above-described membrane electrode assembly.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects:

[0021] This invention introduces surface-bound tin dioxide bromide (Br-SnO2) into a polyvinylpyrrolidone-polyethersulfone (PVP-PES) membrane, enabling the Br-SnO2 crosslinked PVP-PES high-temperature proton exchange membrane to simultaneously achieve high mechanical strength and high proton conductivity. The bromine groups on Br-SnO2 undergo nucleophilic substitution reactions with the amide groups of PVP, forming a crosslinked network and generating quaternary ammonium groups. On one hand, this crosslinked network enhances the mechanical strength of the proton exchange membrane, while precise control of the nucleophilic substitution reaction sites avoids over-crosslinking. On the other hand, the formed quaternary ammonium groups compensate for the reduced PA adsorption caused by Br-SnO2 competing with PA for adsorption sites on the polymer backbone. The quaternary ammonium groups react with dihydrogen phosphate (H2PO4) ions. - The strong adsorption of ions promotes the ionization of PA molecules, releasing more H+. + This improves proton conductivity. Simultaneously, the hydrogen bond network in the strongly interacting quaternary ammonium-dihydrogen phosphate ion pairs constructs a continuous and efficient proton transport channel. + The hydrogen bond network facilitates hopping conduction, promoting the proton transition mechanism and accelerating proton conduction, thereby improving the proton conductivity of the proton exchange membrane without relying on an excessively high proportion of PA adsorption.

[0022] Furthermore, Br-SnO2, as an inorganic metal oxide material, exhibits resistance to hydroxyl radicals (-) through redox cycles. · OH) and peroxide hydroxyl radicals (HOO)· The ability to remove -) also improves the antioxidant stability of the composite membrane. Attached Figure Description

[0023] Figure 1 The graph shows the phosphoric acid absorption and anti-swelling properties of the cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange membranes prepared in Examples 1-4 of the present invention and the polyvinylpyrrolidone-polyethersulfone membranes prepared in the comparative example after being immersed in 85 wt% phosphoric acid at room temperature for 24 hours.

[0024] Figure 2 The graphs show the proton conductivity of the cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange membranes prepared in Examples 1-4 of the present invention and the polyvinylpyrrolidone-polyethersulfone membranes prepared in the comparative examples under non-humidification conditions within the range of 80°C to 180°C.

[0025] Figure 3 The graphs show the fuel cell performance of the cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange membrane materials prepared in Examples 1-4 of the present invention and the polyvinylpyrrolidone-polyethersulfone membrane prepared in the comparative example under hydrogen and oxygen conditions at 160°C without humidification.

[0026] Wherein, PVP / PES represents the comparative example, PP-1%-Br-SnO2 represents Example 1, PP-2%-Br-SnO2 represents Example 2, PP-3%-Br-SnO2 represents Example 3, and PP-4%-Br-SnO2 represents Example 4. Detailed Implementation

[0027] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0028] As described in the background section, existing polyvinylpyrrolidone-polyethersulfone (PVP-PES) composite films struggle to simultaneously achieve high proton conductivity and high mechanical strength, primarily for the following reasons:

[0029] High proton conductivity means that the composite membrane needs to have a high level of phosphate (PA) adsorption capacity to provide sufficient transport channels for protons and ensure the stable conduction of electrochemical reactions. However, while high PA adsorption can improve proton conductivity, excessive PA adsorbs around the polymer backbone, increasing the distance between polymer chains. This reduces the intermolecular forces, leading to polymer backbone plasticization, causing the proton exchange membrane to swell, and ultimately reducing the mechanical strength of the proton exchange membrane.

[0030] Therefore, there is an urgent need to develop a PVP-PES composite membrane that possesses both good proton conductivity and high mechanical strength in order to improve the durability of high-temperature proton exchange membrane fuel cells.

[0031] To address the aforementioned problems, the inventors unexpectedly discovered that introducing a surface-crosslinking agent of tin dioxide bromide (Br-SnO2) into the PVP-PES composite membrane allows Br-SnO2 to crosslink with PVP. This effectively improves the proton conductivity of the composite membrane without relying on an excessively high proportion of PA adsorption, while simultaneously maintaining the mechanical strength of the composite membrane. The specific embodiments of this invention are described in detail below.

[0032] This invention provides a Br-SnO2 crosslinked polyvinylpyrrolidone-polyethersulfone (PVP-PES-Br-SnO2, hereinafter referred to as "PP-Br-SnO2") high-temperature proton exchange membrane, comprising a membrane substrate and a crosslinking agent. The membrane substrate comprises polyvinylpyrrolidone (PVP) and polyethersulfone (PES), and the crosslinking agent is surface-treated tin dioxide bromide (Br-SnO2). The molecular structures of PVP, PES, and Br-SnO2 are shown below:

[0033]

[0034] The mass ratio of PVP to PES is (5-7):(3-5), and the mass ratio of Br-SnO2 added is 1%-4% based on the membrane material. The PVP and PES are commercially available. In this example, the value of n ranges from 500 to 1000, and the value of m ranges from 500 to 1000.

[0035] In this example, the synthesis method of Br-SnO2 is as follows: First, 1.5 g of SnO2 (Shanghai Aladdin Reagent Co., Ltd.) is dispersed in 50 mL of deionized water to obtain a SnO2 dispersion. Then, 0.6734 g of (3-bromopropyl)phosphonic acid (Shanghai Bid Pharmaceutical Technology Co., Ltd.) is dissolved in another 50 mL of deionized water to obtain a (3-bromopropyl)phosphonic acid solution. The (3-bromopropyl)phosphonic acid solution is slowly added dropwise to the SnO2 dispersion over 20-30 minutes to obtain a mixture. The mixture is stirred at room temperature for 32-35 hours, centrifuged, and the product is repeatedly washed with deionized water. After washing, it is dried in an oven at 80°C for 48 hours to obtain Br-SnO2.

[0036] In the PP-Br-SnO2 high-temperature proton exchange membrane of the present invention, the Br-SnO2 undergoes a nucleophilic substitution reaction with PVP to form the following crosslinked structure:

[0037]

[0038] The PP-Br-SnO2 high-temperature proton exchange membrane provided by this invention achieves an optimal balance between the mechanical strength and proton conductivity of the composite membrane. The inventors discovered through research that the reasons are as follows:

[0039] First, Br-SnO2, as an inorganic crosslinking agent, competes with PA for adsorption sites on the polymer backbone. Therefore, the addition of Br-SnO2 reduces the amount of free PA in the polymer chain, preventing excessive PA adsorption in the composite membrane and thus improving its mechanical strength. When PA is doped (adsorbed) into the proton exchange membrane, excessive PA doping leads to an increase in the free volume between polymer chains. This phenomenon increases the inter-chain porosity and reduces the inter-chain bonding force, resulting in volume expansion (plasticization) of the composite membrane. Therefore, adding Br-SnO2 avoids excessively high PA doping levels, thereby reducing the swelling rate of the proton exchange membrane after PA adsorption and preventing a decrease in the mechanical strength of the proton exchange membrane caused by excessive PA doping. Furthermore, since Br-SnO2 has an inorganic rigid structure, it can form an organic-inorganic structure in the composite membrane, further improving its mechanical strength.

[0040] Secondly, after the bromine group on Br-SnO2 undergoes a nucleophilic substitution reaction with the amide group of PVP, a cross-linking network is formed, generating quaternary ammonium groups. On the one hand, the cross-linking network enhances the mechanical strength of the composite membrane, and the nucleophilic substitution reaction at specific sites helps to precisely control the cross-linking points in the composite membrane, avoiding over-cross-linking that may be caused by traditional cross-linking agents. On the other hand, the quaternary ammonium groups can compensate for the decrease in proton conductivity caused by reduced PA adsorption. The quaternary ammonium groups have a positive charge and can attract dihydrogen phosphate (H2PO4) ions from PA molecules. - The negative charge of the ions forms a strong quaternary ammonium-dihydrogen phosphate ion pair, enhancing the retention capacity of adsorbed PA and maintaining the proton conductivity of the composite membrane, thereby improving its durability. Furthermore, this interaction can promote the ionization reaction of PA molecules, releasing more H+. + This improves the proton conductivity of the composite membrane. Simultaneously, during proton conduction, H... + Proton conduction can be accelerated by hopping through the hydrogen bond network between quaternary ammonium-dihydrogen phosphate ion pairs, promoting the proton transition mechanism. Therefore, this invention can improve the proton conductivity of the composite membrane without relying on an excessively high proportion of PA adsorption.

[0041] In addition, Br-SnO2 is an inorganic metal oxide material that exhibits the ability to scavenge hydroxyl radicals (-OH) and peroxidized hydroxyl radicals (HOO-) through redox cycles, thereby improving the antioxidant stability of PP-Br-SnO2 high-temperature proton exchange membranes.

[0042] The preparation method of the PP-Br-SnO2 high-temperature proton exchange membrane of the present invention includes:

[0043] Step S1: Dissolve PVP and PES in a first polar aprotic solvent to obtain a homogeneous solution.

[0044] The first polar aprotic solvent includes, but is not limited to, any one or more of N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, or dimethyl sulfoxide.

[0045] Step S2: Br-SnO2 is dispersed in a second polar aprotic solvent to obtain a crosslinking agent solution.

[0046] The second polar aprotic solvent and the first polar aprotic solvent may be the same or different. The second polar aprotic solvent includes, but is not limited to, any one or more of N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, or dimethyl sulfoxide.

[0047] Step S3: After the homogeneous solution and the crosslinking agent solution are mixed evenly, a film is formed by casting. The first polar aprotic solvent and the second polar aprotic solvent are removed by heating and evaporation to form a blend film.

[0048] The homogeneous solution and the crosslinking agent solution are mixed uniformly at 60℃ to 90℃. At this temperature, Br-SnO2 undergoes a crosslinking reaction with PVP to form a crosslinked structure, and this temperature also facilitates better dispersion of Br-SnO2 in the homogeneous solution, forming a uniform solution.

[0049] The heating and evaporation temperature is 60℃~80℃, and the temperature is maintained for 5h~15h to completely remove the first polar aprotic solvent and the second polar aprotic solvent, which facilitates film formation.

[0050] Step S4: Immerse the blended membrane in phosphoric acid to obtain a cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange membrane.

[0051] The concentration of phosphoric acid is 70wt% to 98wt%, and the soaking time is 15h to 30h, so that the blended membrane can fully adsorb phosphoric acid to form a phosphoric acid-doped cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange membrane.

[0052] Unless otherwise specified, all chemicals used in this invention are conventionally available chemical reagents. These chemicals can be purchased from multiple chemical reagent suppliers and do not require special preparation or synthesis.

[0053] The present invention will be further described in detail below with reference to specific embodiments.

[0054] Example 1

[0055] This embodiment provides a high-temperature proton exchange membrane with surface-brominated tin dioxide crosslinked polyvinylpyrrolidone-polyethersulfone (PP-Br-SnO2).

[0056] The preparation method of the PP-Br-SnO2 high-temperature proton exchange membrane is as follows:

[0057] Step S101: Using polyvinylpyrrolidone (PVP) and polyethersulfone (PES) as raw materials and N-methylpyrrolidone solution as solvent, PVP and PES are added to the N-methylpyrrolidone solution at a mass ratio of 7:3. The mixture is stirred at room temperature for 12 hours to dissolve the PVP and PES solution, thus obtaining a polyvinylpyrrolidone-polyethersulfone (PVP-PES) solution.

[0058] In step S102, Br-SnO2 is added to an N-methylpyrrolidone solution, stirred at room temperature, and ultrasonically dispersed to obtain a uniformly dispersed Br-SnO2 suspension. The mass ratio of Br-SnO2 to the total mass of PVP and PES is controlled at 1:100, i.e., 1 wt% Br-SnO2 is added.

[0059] Step S103: Add the uniformly dispersed Br-SnO2 suspension to the PVP-PES solution, stir at 80°C and ultrasonically disperse to obtain a membrane solution with a total mass fraction of 15 wt% for PVP, PES and Br-SnO2 in the solution.

[0060] Step S104: A film is formed by casting. The film solution from step S103 is cast onto a glass plate and heated at 60°C for 12 hours. After evaporation to remove N-methylpyrrolidone, a Br-SnO2 crosslinked polyvinylpyrrolidone-polyethersulfone (PP-Br-SnO2) blend film is obtained.

[0061] Step S105: The PP-Br-SnO2 blend membrane is soaked in 85wt% PA at room temperature for 24 hours and then taken out to obtain the desired composite high-temperature proton exchange membrane, denoted as PP-1%-Br-SnO2.

[0062] Example 2

[0063] The difference between this embodiment and Embodiment 1 is that, in step S102, the mass ratio of Br-SnO2 added is 2wt%. The resulting composite high-temperature proton exchange membrane is denoted as PP-2%-Br-SnO2.

[0064] Example 3

[0065] The difference between this embodiment and Embodiment 1 is that, in step S102, the mass ratio of Br-SnO2 added is 3wt%. The resulting composite high-temperature proton exchange membrane is denoted as PP-3%-Br-SnO2.

[0066] Example 4

[0067] The difference between this embodiment and Embodiment 1 is that, in step S102, the mass ratio of Br-SnO2 added is 4wt%. The resulting composite high-temperature proton exchange membrane is denoted as PP-4%-Br-SnO2.

[0068] Comparative Example

[0069] This comparative example provides a polyvinylpyrrolidone-polyethersulfone (PVP-PES) high-temperature proton exchange membrane, which differs from Example 1 in that Br-SnO2 is not added. The specific preparation process of the PVP-PES high-temperature proton exchange membrane is as follows:

[0070] PVP and PES were added to an N-methylpyrrolidone solution (mass ratio: PVP:PES = 7:3) and stirred at room temperature for 12 hours to ensure uniform dissolution, resulting in a homogeneous and transparent solution with a total mass fraction of 15 wt% for PVP, PES, and Br-SnO2. A film was formed using a casting method, by casting the homogeneous and transparent solution onto a glass plate and heating at 60°C for 12 hours to evaporate and remove N-methylpyrrolidone, yielding a polyvinylpyrrolidone-polyethersulfone (PVP-PES) blend membrane. The PVP-PES blend membrane was then immersed in 85 wt% phosphoric acid at room temperature for 24 hours to obtain the desired high-temperature proton exchange membrane, denoted as PVP / PES.

[0071] The high-temperature proton exchange membranes with different doping amounts obtained in Examples 1-4 and the comparative examples were subjected to the following offline and online tests.

[0072] Referring to GB / T 20042.3-2022, the swelling rate of the obtained high-temperature proton exchange membrane was tested. The specific operating conditions were as follows: under constant temperature and humidity conditions of 23℃±2℃ and 50%±5%, the initial length L0 and initial width W0 of the sample were measured with calipers, and the thickness d0 of the sample was measured with a thickness gauge. The initial volume V0 = L0 × W0 × d0 was calculated. After soaking the sample at room temperature and a phosphoric acid concentration of 85% for 24 hours, the length L and width W of the sample were measured with calipers, and the thickness d of the sample was measured with a thickness gauge. The volume after soaking was calculated as V = L × W × d. The swelling rate E... v =V0 / V.

[0073] According to GB / T 20042.3-2022, the proton conductivity of the obtained high-temperature proton exchange membrane was tested. The specific operating conditions were: the temperature was 80℃~180℃ and the humidity was 0%, and the conductivity testing device was connected to the electrochemical impedance spectroscopy instrument.

[0074] Referring to GB / T 20042.5-2009, the obtained high-temperature proton exchange membrane was used to make a high-temperature proton exchange membrane fuel cell, and polarization curve tests were performed. The specific operating conditions were: the single cell operating temperature was 160℃, the anode was fed with pure hydrogen, the cathode was fed with atmospheric pressure oxygen, and the ratio of cathode feed to anode feed was 1:1.

[0075] Test results are as follows Figures 1 to 3 As shown.

[0076] See Figure 1 The phosphoric acid adsorption (doping) rate and swelling rate of the proton exchange membranes prepared in Examples 1-4 and the comparative example of the present invention were measured. As can be seen from the figures, after phosphoric acid adsorption, the phosphoric acid adsorption rates of the membranes prepared in Examples 1-4 and the comparative example were 352.78%, 342.16%, 342.16%, 323.86%, and 416.84%, respectively. The corresponding swelling rates were 209.54%, 189.72%, 172.41%, 165.97%, and 231.3%, respectively. Compared with the comparative example, the PP-Br-SnO2 proton exchange membranes prepared in Examples 1-4 of the present invention maintained a higher PA adsorption rate and a lower swelling rate; while the PA adsorption rate of the comparative example was too high, resulting in a higher swelling rate, which is detrimental to the mechanical properties of the proton exchange membrane. The PA adsorption rate in Examples 1-4 was slightly lower than that in the comparative example, which proves that Br-SnO2 competes with PA for adsorption sites on the polymer backbone. Therefore, the addition of Br-SnO2 can effectively avoid the reduction of inter-chain bonding caused by excessive PA doping, thereby reducing the deformation and swelling of the proton exchange membrane. This further proves that the PP-Br-SnO2 high-temperature proton exchange membrane prepared in this invention has good mechanical strength.

[0077] See Figure 2 The proton conductivity of the proton exchange membranes prepared in Examples 1-4 and the comparative example of the present invention was measured. As can be seen from the figure, at 100°C, the proton conductivity of Examples 1-4 and the comparative example were measured to be 0.0729 S·cm, respectively. -1 0.0823 S·cm -1 0.0879 S·cm -1 0.0795S·cm -1 0.0704 S·cm -1 At 160°C, the proton conductivity of Examples 1-4 and the comparative example of the present invention was measured to be 0.1097 S·cm, respectively.-1 0.1237 S·cm -1 0.1296 S·cm -1 0.1179 S·cm -1 0.0981 S·cm -1 Compared with the comparative examples, the PP-Br-SnO2 proton exchange membranes prepared in Examples 1-4 of this invention exhibit higher proton conductivity and better proton conductivity. This demonstrates that the quaternary ammonium groups generated by the cross-linking of Br-SnO2 and PVP in this invention can effectively compensate for the decrease in proton conductivity (proton conductivity) caused by the reduction in PA adsorption. The attraction of the quaternary ammonium groups to negative charges is beneficial for the formation of quaternary ammonium groups and dihydrogen phosphate (H2PO4) groups. - This forms a strong quaternary ammonium-dihydrogen phosphate ion pair, promoting the ionization of PA and forming more H+. + Furthermore, it enhances the retention capacity of adsorbed PA, thereby improving the proton conductivity of the proton exchange membrane. In addition, the strong hydrogen bond network between ion pairs makes H... + Capable of transition conduction, accelerating H + This improves the proton conductivity of the proton exchange membrane.

[0078] See Figure 3 The fuel cell performance of the proton exchange membranes prepared in Examples 1-4 and the comparative example of the present invention was measured. As can be seen from the figures, at 0.1 A / cm... 2 The membrane electrode voltages prepared using the proton exchange membranes obtained in Examples 1-4 and the comparative example of this invention were measured to be 0.748V, 0.769V, 0.754V, 0.757V, and 0.708V, respectively. The power densities of the fuel cells prepared using the proton exchange membranes obtained in Examples 1-4 and the comparative example of this invention were measured to be 74.8 mW·cm⁻¹. -2 76.9 mW·cm -2 75.4 mW·cm -2 75.7mW·cm -2 70.8 mW·cm -2 At 0.5A / cm 2 The membrane electrode voltages of the proton exchange membranes prepared using the methods described in Examples 1-4 and the comparative example of this invention were measured to be 0.560V, 0.613V, 0.618V, 0.576V, and 0.501V, respectively. The power densities of the fuel cells prepared using the proton exchange membranes described in Examples 1-4 and the comparative example of this invention were measured to be 280.0 mW·cm⁻¹. -2 306.5mW·cm -2 309.0 mW·cm -2 288mW·cm -2 250.5mW·cm -2At 1.0 A / cm 2 The membrane electrode voltages prepared using the proton exchange membranes obtained in Examples 1-4 and the comparative example of this invention were measured to be 0.343V, 0.428V, 0.463V, 0.381V, and 0.276V, respectively. The power densities of the fuel cells prepared using the proton exchange membranes obtained in Examples 1-4 and the comparative example of this invention were measured to be 343.0 mW·cm⁻¹. -2 428.0 mW·cm -2 463.0 mW·cm -2 381.0 mW·cm -2 276.0 mW·cm -2 Compared with the comparative examples, the PP-Br-SnO2 proton exchange membranes prepared in Examples 1-4 of this invention have higher membrane electrode voltages, which means lower membrane electrode polarization losses and higher power density of the fuel cells. This proves that the PP-Br-SnO2 high-temperature proton exchange membranes prepared in this invention have high proton conductivity during operation, and the fuel cells prepared using PP-Br-SnO2 high-temperature proton exchange membranes have low polarization losses during operation, which is beneficial to improving the durability of the fuel cells.

[0079] In summary, this invention achieves a balance between high mechanical strength and high proton conductivity in high-temperature proton exchange membranes by introducing surface-bound tin dioxide bromide (Br-SnO2) into polyvinylpyrrolidone-polyethersulfone (PVP-PES) membranes. The bromine groups on Br-SnO2 undergo nucleophilic substitution reactions with the amide groups of PVP, forming a cross-linked network and generating quaternary ammonium groups, which enhance the mechanical strength of the membrane while precisely controlling the cross-linking points to avoid over-cross-linking. The quaternary ammonium groups not only compensate for the reduced PA adsorption caused by competition for adsorption sites between Br-SnO2 and phosphoric acid (PA), but also enhance PA adsorption through interaction with dihydrogen phosphate (H2PO4) groups. - The ions form strongly interacting ion pairs, promoting the ionization of PA molecules and releasing more H+. + This improves proton conductivity. The hydrogen bond network constructed by these ion pairs is H... + It provides a continuous and efficient transport channel, promotes the proton transition mechanism, and accelerates the proton conduction speed, thereby improving the proton conductivity of the proton exchange membrane without relying on a high proportion of PA adsorption.

[0080] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A cross-linked polyvinylpyrrolidone-polyether sulfone high temperature proton exchange membrane, characterized in that, The film main material comprises polyvinylpyrrolidone and polyethersulfone, and the cross-linking agent is surface brominated tin dioxide, and the added mass ratio of the cross-linking agent is 1% to 4% based on the film main material; the mass ratio of the polyvinylpyrrolidone and the polyethersulfone is (5 to 7) to (3 to 5).

2. A method for preparing a cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange membrane as described in claim 1, characterized in that, The film main material comprises polyvinylpyrrolidone and polyethersulfone, and the cross-linking agent is surface brominated tin dioxide, and the added mass ratio of the cross-linking agent is 1% to 4% based on the film main material; the mass ratio of the polyvinylpyrrolidone and the polyethersulfone is (5 to 7) to (3 to 5). The film main material comprises polyvinylpyrrolidone and polyethersulfone, and the cross-linking agent is surface brominated tin dioxide, and the added mass ratio of the cross-linking agent is 1% to 4% based on the film main material; the mass ratio of the polyvinylpyrrolidone and the polyethersulfone is (5 to 7) to (3 to 5). The film main material comprises polyvinylpyrrolidone and polyethersulfone, and the cross-linking agent is surface brominated tin dioxide, and the added mass ratio of the cross-linking agent is 1% to 4% based on the film main material; the mass ratio of the polyvinylpyrrolidone and the polyethersulfone is (5 to 7) to (3 to 5). The first polar aprotic solvent and the second polar aprotic solvent are the same or different. The first polar aprotic solvent and the second polar aprotic solvent are independently selected from any one or more of N, N-dimethylacetamide, N, N-dimethylformamide, N-methylpyrrolidone or dimethyl sulfoxide.

3. The production method according to claim 2, wherein In the step S3, the homogeneous solution and the cross-linking agent solution are uniformly mixed at 60°C to 90°C.

4. The production method according to claim 3, wherein In the step S3, the heating evaporation temperature is 60°C to 80°C, and the holding time is 5h to 15h.

5. The production method according to claim 2, wherein In the step S4, the concentration of the phosphoric acid is 70wt% to 98wt%, and the soaking time is 15h to 30h.

6. The production method according to claim 2, wherein The cross-linked polyvinylpyrrolidone-polyethersulfone high-temperature proton exchange film as claimed in claim 1.

7. The production method according to claim 2, wherein The membrane electrode as claimed in claim 8.

8. A membrane electrode characterized by, ​ 9. A fuel cell characterized by comprising: ​

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