Membrane electrode, method for producing the same, and high-temperature proton exchange membrane fuel cell

Abstract

The application discloses a membrane electrode, a preparation method thereof and a high-temperature proton exchange membrane fuel cell. The membrane electrode comprises a cathode catalytic layer, wherein the cathode catalytic layer comprises a cathode catalyst and hyperbranched sulfonated polyamide molecules, the cathode catalyst is at least one of Pt / C, PtFe / C or PtCo / C; and the mass fraction of the noble metal is 5% to 70%. When the hyperbranched sulfonated polyamide is used as a cathode catalytic layer ionomer, the proton conductivity of the cathode is improved, the interface structure of the catalyst, the ionomer and oxygen or air is optimized, and the full use of Pt active sites is facilitated. In addition, by adjusting the surface group to be -NH2, the acid blockage of the mass transfer channel and the acid flooding caused by the traditional polymer ionomer in the cathode are greatly improved, the effective distribution of phosphoric acid in the cathode catalytic layer is ensured, the three-phase interface in the electrode is greatly increased, and the stable operation state of the battery under high current density is improved.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature proton exchange membrane fuel cells, specifically relating to a membrane electrode, its preparation method, and a high-temperature proton exchange membrane fuel cell. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) possess advantages such as high energy conversion efficiency, high power density, zero pollutant emissions, and low operating noise, and are considered promising candidates for next-generation power sources. Based on operating temperature, PEMFCs are divided into low-temperature PEMFCs (LT-PEMFCs) based on Nafion membranes and high-temperature PEMFCs (HT-PEMFCs) based on phosphoric acid (PA)-doped polybenzimidazole (PBI) membranes. Currently, commercially successful low-temperature PEMFCs suffer from limitations such as high requirements for fuel gas purity and complex hydrothermal management systems, restricting their application scenarios. Therefore, HT-PEMFCs, operating at temperatures above 120°C, have attracted significant attention due to their fast reaction kinetics (high energy efficiency), high tolerance to fuel / air impurities, simple plate design, and improved thermal and water management, making them promising candidates for next-generation PEMFCs specifically designed for hydrogen fuel cell vehicles and combined heat and power (CHP) systems. However, since PA is the main proton transport carrier in HT-PEMFC, PA can cover the active sites of Pt in the catalyst layer, resulting in a significant reduction in catalyst activity. In addition, improperly distributed PA can also block the mass transfer channels of the catalyst layer, making it more difficult for air or oxygen to diffuse, which can cause acid flooding under the high current density operating conditions of the battery.

[0003] The commonly used solution is to introduce a certain amount of hydrophobic polymers such as polytetrafluoroethylene (PTFE) into the catalyst layer. PTFE molecules can not only improve the distribution of PA (polytetrafluoroethylene) but also bind the catalyst particles together, improving battery performance. However, since PTFE molecules are not conductive, they cannot transport electrons. Their construction process at the three-phase interface reduces the reactive sites of the catalyst, which is detrimental to improving battery performance. At the same time, PTFE molecules are very prone to agglomeration in the catalyst slurry, resulting in uneven PTFE distribution at the catalyst layer interface, which affects the performance and lifespan of high-temperature proton exchange membrane fuel cells.

[0004] Therefore, it is necessary to find a new type of polymer ionomer to solve the current problems of PTFE and gradually replace its role in the catalyst layer, so as to further improve the performance of HT-PEMFC. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of PTFE's inability to transfer electrons and its uneven distribution in the catalyst layer of HT-PEMFC. Based on the controllable construction technology of ionomer catalyst layer with nanoscale controllable three-phase interface on the catalyst surface, this invention provides a high-temperature proton exchange membrane fuel cell membrane electrode with hyperbranched sulfonated polyamide (HBM) cathode catalyst layer and its preparation method. Under the premise of more convenient production operation, on the one hand, the lower coverage of HBM on the active sites of the catalyst reduces the diffusion resistance of cathode reactive gas in the catalyst layer. On the other hand, the HBM surface group is controlled to be -NH2 to increase the acid storage capacity of the catalyst layer, thereby regulating the distribution of phosphoric acid in the catalyst layer, avoiding acid flooding of the catalyst layer, and ensuring the movement of protons between sulfonic acid groups under water-deficient conditions. Even under conditions of lack of water and PA, it can play a role in constructing a three-phase interface, improving catalyst utilization and battery performance and lifespan.

[0006] To achieve the above objectives, the present invention provides a membrane electrode comprising: a cathode catalyst layer, wherein the cathode catalyst layer comprises a cathode catalyst and hyperbranched sulfonated polyamide molecules, wherein the cathode catalyst is at least one selected from Pt / C, PtFe / C, or PtCo / C; wherein the mass fraction of the noble metal is 5% to 70%.

[0007] Optionally, in the cathode catalyst layer, the mass ratio of the hyperbranched sulfonated polyamide to the carbon in the cathode catalyst is 0.01-0.25.

[0008] Optionally, the loading of noble metals in the cathode catalyst layer is 0.5-1.0 mg / cm³. 2 .

[0009] Optionally, it further comprises: a cathode diffusion layer, the cathode diffusion layer including a support layer and a microporous layer; the support layer is carbon paper and / or carbon cloth, the microporous layer includes carbon powder and PTFE, and the PTFE content in the microporous layer is 5%-25% by mass.

[0010] Optionally, the carbon powder is at least one of activated carbon, graphitized carbon, carbon nanotubes, carbon nanoribbons, and carbon nanospheres.

[0011] Optionally, it further comprises: an anode catalyst layer, the anode catalyst layer comprising an anode catalyst and an anode hydrophobic binder, the anode catalyst comprising at least one of Pt / C, PtFe / C or PtCo / C, wherein the mass fraction of the noble metal is 5% to 70%.

[0012] Optionally, the loading of noble metals in the anode catalyst layer is 0.3-0.5 mg / cm³. 2 .

[0013] Optionally, the anolyte is at least one of PTFE, PVDF, FEP, ECTE, ETFE, PFA, and PDMS.

[0014] Another object of the present invention is to provide a method for preparing the above-mentioned membrane electrode, the method comprising:

[0015] S1, the anode catalyst, the anode hydrophobic binder and the surfactant are uniformly dispersed in an aqueous alcohol solution to form the anode catalyst slurry;

[0016] S2, the anode catalyst slurry is coated onto the anode diffusion layer to obtain the anode;

[0017] S3, the cathode catalyst and the dissolved hyperbranched sulfonated polyamide molecular solution are uniformly dispersed in an organic solvent to serve as a cathode catalyst slurry;

[0018] S4, the cathode catalyst slurry is coated onto the cathode diffusion layer to obtain the cathode;

[0019] S5, the anode, proton exchange membrane and cathode are sequentially bonded together and composited by hot pressing to obtain membrane electrode.

[0020] Another object of the present invention is to provide a high-temperature proton exchange membrane fuel cell comprising: the membrane electrode described above.

[0021] Compared with the prior art, the technical solution of the present invention has at least the following beneficial technical effects:

[0022] When hyperbranched sulfonated polyamide (HBM) is used as the ionomer of the cathode catalyst layer, it not only improves the proton conductivity of the cathode and increases the utilization rate of the catalyst, but also reduces the diffusion resistance of the cathode reactant gas in the catalyst layer by the lower coverage of the catalyst active sites. This further optimizes the interfacial structure between the catalyst, the ionomer and oxygen or air, which is beneficial to the full utilization of Pt active sites.

[0023] The tunable structure of hyperbranched sulfonated polyamide molecules allows them to play more diverse roles in the cathode catalyst layer. By controlling their surface groups to be -NH2, the acid blockage of mass transfer channels and subsequent acid flooding that occurs with traditional polymer ionomers at the cathode is greatly improved. This ensures the effective distribution of phosphoric acid in the cathode catalyst layer, significantly increases the three-phase interface within the electrode, and improves the stable operation of the battery under high current density conditions. Moreover, it can ensure the movement of protons between sulfonic acid groups under water-deficient conditions. Even in the absence of water and PA, it can still play a role in constructing the three-phase interface, improving catalyst utilization and battery performance and lifespan. Attached Figure Description

[0024] Figure 1This is a schematic diagram of the structure of a high-temperature proton exchange membrane fuel cell.

[0025] Figure 2 The graphs show the membrane electrode polarization characteristics of different cathode catalyst layers in Example 1 and Comparative Example 1.

[0026] Figure 3 The membrane electrode impedance diagrams are for different cathode catalyst layers in Example 1 and Comparative Example 1. 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] like Figure 1 As shown, a high-temperature proton exchange membrane fuel cell includes:

[0029] The membrane electrode includes a cathode 10, a proton exchange membrane 1, and an anode 20. The cathode 10 includes a cathode diffusion layer 12 and a cathode catalyst layer 11 applied to one side of the cathode diffusion layer; the anode 20 includes an anode diffusion layer 22 and an anode catalyst layer 21 applied to one side of the anode diffusion layer.

[0030] The cathode monopole plate 13 and the first end plate 14 are disposed on the cathode 10 side; and

[0031] Anode monopolar plate 23 and second end plate 24 are disposed on the anode 20 side.

[0032] The proton exchange membrane is a polybenzimidazole membrane (PBI), which has been treated with phosphoric acid doping.

[0033] The cathode diffusion layer 12 includes a support layer 121 and a microporous layer 122, with the support layer 121 located on the side of the microporous layer 122 away from the proton exchange membrane 1. The anode diffusion layer 22 includes a support layer 221 and a microporous layer 222, with the support layer 221 located on the side of the microporous layer 222 away from the proton exchange membrane 1.

[0034] This invention is based on the controllable construction technology of ionomer catalyst layers with nanoscale controllable construction of three-phase interfaces on catalyst surfaces. As a proton transport functionalized polymer (hyperbranched sulfonated polyamide molecule, HBM) constructed with nanoscale three-phase interfaces, as shown in Formula I, it is a sulfonated polyamide with a nanoparticle morphology. The IEC (ion exchange capacity) value of HBM can reach 2.6. Its synthesis method involves mixing p-diaminobenzenesulfonic acid (DSA) and trimesic acid (TA) in a certain proportion, then adding a certain amount of pyridine (PY), N-methylpyrrolidone (NMP), triphenyl phosphite (TPP), and anhydrous lithium chloride (LiCl) for polymerization. After the reaction is completed, after washing, filtering, and drying, a brown powder is obtained. This powder is then treated with sodium hydroxide solution and vacuum dried to obtain a brownish-yellow hyperbranched macromolecular polymer (HBM). When the DSA:TA molar ratio is greater than 3:4 and less than 1:1, carboxyl-terminated HBM is generated; when the DSA:TA molar ratio is greater than 2:1 and less than 3:1, amino-terminated HBM is generated. By controlling the reaction conditions for HBM synthesis, it is possible to regulate the surface-capped groups (carboxyl or amino groups) and control the molecular size of HBM.

[0035]

[0036] The hyperbranched sulfonated polyamide molecule can be HBM (compound I), or it can be a polymer with a similar structure to HBM, such as the following compound II:

[0037]

[0038] This invention introduces hyperbranched sulfonated polyamide with a nanoparticle morphology into the cathode-side catalyst layer of a membrane electrode. Due to the presence of surface groups on HBM molecules, they can be precisely anchored to nanoparticles on the surface of supported catalysts (such as PtCo / C) through hydrogen bonding, thus achieving the construction of a nanoscale three-phase interface on the catalyst surface. The introduction of this hyperbranched sulfonated polyamide molecule with good proton conductivity reduces the catalyst layer's dependence on traditional non-conductive polymer ionomers (such as PTFE), and the introduction of sulfonate ions also improves the proton transport efficiency at the three-phase interface. Furthermore, the better oxygen permeability and lower poisoning of catalyst active sites by HBM optimizes multiphase mass transport in the catalyst layer, solving the mass transfer problems existing in traditional catalyst layers and providing a solution for improving the high-current operation of high-temperature proton exchange membrane fuel cells.

[0039] The high-temperature proton exchange membrane fuel cell operates at a temperature of 140℃-220℃, and the proton exchange membrane used is a phosphoric acid-doped PBI membrane. During operation, hydrogen gas is introduced into the anode side, causing the HOR reaction (hydrogenation reaction) to generate H₂. + When air or oxygen is introduced into the cathode side, an ORR (oxygen reduction reaction) occurs at the cathode, producing water.

[0040] The membrane electrode provided by this invention comprises a cathode catalyst layer, wherein the cathode catalyst layer contains a catalyst and hyperbranched sulfonated polyamide molecules. The cathode catalyst layer of this invention does not use traditional ionomers (PTFE), which can further improve the proton conductivity of the catalyst layer, accurately construct a good three-phase interface, improve catalyst utilization, and enable unrestricted proton transport under high current density operating conditions.

[0041] The hyperbranched sulfonated polyamide molecules used in this invention not only have a high IEC (intercalation efficiency), but also a high geometric density of sulfonic acid groups due to their hyperbranched structure. This ensures the movement of protons between sulfonic acid groups under water-deficient conditions, and can function as a three-phase interface even in the absence of water and PA (phosphoric acid). Furthermore, during the preparation of HBM, the surface groups can be controlled to -NH2. Its strong alkalinity allows for effective enrichment of PA even when the PA content in the catalyst layer is insufficient. This greatly ensures the effective distribution of phosphoric acid in the catalyst layer, avoids acid flooding of the cathode catalyst layer, significantly increases the three-phase interface within the electrode, and improves catalyst utilization, battery performance, and lifespan.

[0042] The cathode catalyst is at least one of Pt / C, PtFe / C, or PtCo / C; wherein the mass fraction of the noble metal is 5%–70%. The loading of the noble metal in the cathode catalyst layer is 0.5–1.0 mg / cm³. 2 The "precious metal" mentioned in this article refers to Pt (platinum).

[0043] In the cathode catalyst layer, the mass ratio of the hyperbranched sulfonated polyamide to the carbon in the cathode catalyst is 0.01-0.25.

[0044] The membrane electrode further comprises: a cathode diffusion layer, which includes a support layer and a microporous layer, with the support layer located on the side of the microporous layer away from the proton exchange membrane. The support layer is carbon paper and / or carbon cloth, and the microporous layer comprises carbon powder and PTFE, with the PTFE content in the microporous layer being 5%-25%. The carbon powder is at least one of activated carbon, graphitized carbon, carbon nanotubes, carbon nanoribbons, and carbon nanospheres.

[0045] The membrane electrode further comprises: an anode catalyst layer, the anode catalyst layer comprising an anode catalyst and an anode hydrophobic binder, the anode catalyst comprising at least one of Pt / C, PtFe / C, or PtCo / C, wherein the mass fraction of the noble metal is 5%–70%. The loading of the noble metal in the anode catalyst layer is 0.3–0.5 mg / cm³. 2The anolyte hydrophobic binder is at least one of PTFE, polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-chlorotrifluoroethylene copolymer (ECTFE), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and polydimethylsiloxane (PDMS).

[0046] The membrane electrode further includes an anolyte diffusion layer. The anolyte catalyst layer is coated on the anolyte diffusion layer to form an anode. The anolyte diffusion layer may or may not be made of the same material as the cathode diffusion layer. In this example, the anolyte diffusion layer and the cathode diffusion layer are made of the same material and have the same PTFE content.

[0047] The present invention also provides a method for preparing the above-mentioned membrane electrode, the method comprising:

[0048] S1, the anode catalyst, the anode hydrophobic binder and the surfactant are uniformly dispersed in an aqueous alcohol solution as an anode catalyst slurry; the aqueous alcohol solution can be water and isopropanol.

[0049] S2, the anode catalyst slurry is coated onto the anode diffusion layer to obtain the anode;

[0050] S3, the cathode catalyst and the dissolved hyperbranched sulfonated polyamide molecular solution are uniformly dispersed in an organic solvent as a cathode catalyst slurry; the solvent can be N,N-dimethylacetamide (DMAC) and N-methylpyrrolidone (NMP).

[0051] S4, the cathode catalyst slurry is coated onto the cathode diffusion layer to obtain the cathode;

[0052] S5, the anode, proton exchange membrane and cathode are sequentially bonded together and composited by hot pressing to obtain membrane electrode.

[0053] The solid content of the slurry for the cathode and anode catalyst layers is maintained at 0.2-0.25%.

[0054] The present invention will now be described in detail with reference to the embodiments. Of course, the present invention is not limited to the specific embodiments described below. The raw materials and reagents described in the embodiments and comparative examples are all commercially available.

[0055] Example 1

[0056] The preparation method of the membrane electrode assembly for a high-temperature proton exchange membrane fuel cell with a hyperbranched sulfonated polyamide cathode catalyst layer is as follows:

[0057] Preparation of the gas diffusion layer: First, Vulcan XC-72 toner and PTFE emulsion were mixed, and an appropriate amount of ethanol was added. The mixture was ultrasonically stirred to obtain a slurry, which was then coated onto the surface of commercially available Toray carbon paper. The toner loading and PTFE content were then determined by weighing. Finally, the mixture was placed in a muffle furnace and heat-treated at 340°C for 25 minutes. After cooling to room temperature, the gas diffusion layer was obtained.

[0058] Preparation of the anode GDE (anode catalyst layer + anode diffusion layer): Weigh the required Pt / C catalyst, add a small amount of deionized water and stir to wet it, then add a certain amount of PTFE water-alcohol solution, and after ultrasonic dispersion, obtain the catalyst slurry; use a pneumatic spraying method to uniformly coat the microporous layer surface of the anode diffusion layer.

[0059] Preparation of the cathode GDE (cathode catalyst layer + cathode diffusion layer): A certain amount of hyperbranched sulfonated polyamide molecules (compound I) were weighed and added to a certain amount of DMAC solution. The mixture was then stirred at 80°C for more than 4 hours to ensure complete dissolution, resulting in a hyperbranched sulfonated polyamide solution. The required amount of PtCo / C catalyst was weighed and added to the required amount of DMAC solution. After ultrasonic dispersion, an appropriate amount of the dissolved and dispersed hyperbranched sulfonated polyamide solution was added dropwise. The mixture was then ultrasonically dispersed and stirred again to ensure that the hyperbranched sulfonated polyamide molecules were uniformly dispersed in the catalyst slurry, resulting in a cathode catalyst layer slurry. The slurry was then uniformly coated onto the microporous surface of the cathode diffusion layer using a pneumatic spraying method to obtain a cathode catalyst layer containing hyperbranched sulfonated polyamide molecules.

[0060] PBI / H3PO4 composite membranes were prepared using an impregnation method: S1, the PBI membrane was cut to a specific size as needed; S2, the cut membrane was immersed in 85 wt.% phosphoric acid at 120°C for the appropriate time; S3, excess phosphoric acid on the membrane surface was blotted dry with filter paper, and the membrane was quickly weighed to obtain the phosphoric acid adsorption capacity. The phosphoric acid adsorption capacity m of the membrane was evaluated using the mass ratio of phosphoric acid to resin. PA / m PBI (Mass of adsorbed phosphoric acid / original mass of polybenzimidazole membrane). Repeat cycle S2→S3 until the phosphoric acid adsorption reaches 400 wt.%.

[0061] The prepared electrodes (anode GDE and cathode GDE) and the PBI / H3PO4 composite membrane are stacked in a mold in a specific order. Then, the membrane electrode is hot-pressed and formed in a hot press to obtain the fuel cell membrane electrode, which is then placed in a sealed bag for storage and future use.

[0062] The active area of ​​the membrane electrode is 4 cm². 2The cathode and anolyte gas diffusion layers have the same composition and structure, both consisting of a support layer and a microporous layer. The support layer is mainly Torray carbon paper with a thickness of 140 micrometers. The microporous layer is mainly composed of carbon powder and PTFE; the carbon powder type is Vulcan XC-72; the carbon powder loading in the microporous layer is 4 mg / cm³. 2 The PTFE content is 25%; the microporous layer thickness is 40 micrometers. The anode catalyst layer consists of 50 wt% Pt / C catalyst and PTFE, with a platinum loading of 0.5 mg / cm³. 2 The PTFE content in the anode catalyst layer is 20%. The cathode catalyst layer consists of 46.9 wt% PtCo / C and HBM, with a Pt loading of 1 mg Pt / cm³. 2 The HBM content is HBM / C = 0.03.

[0063] Comparative Example 1

[0064] The difference from Example 1 is that in the membrane electrode assembly of the high-temperature proton exchange membrane fuel cell in Comparative Example 1, the cathode catalyst layer is composed of 46.9 wt% PtCo / C and PTFE, and the Pt loading is 1 mg Pt / cm³. 2 The PTFE content is 20%.

[0065] Performance testing

[0066] According to GB / T 20042.5-2009, the polarization curve of the obtained high-temperature proton exchange membrane fuel cell membrane electrode was tested. The specific operating conditions were: single cell operating temperature of 160℃, anode feed of pure hydrogen, cathode feed of atmospheric pressure air, and cathode / anode feed ratio of 3 / 1.5.

[0067] According to GB / T 20042.5-2009, the membrane electrode impedance of a high-temperature proton exchange membrane fuel cell was tested. The specific operating conditions were: single cell operating temperature 160℃, anode feed pure hydrogen, cathode feed atmospheric pressure air, and a cathode / anode feed ratio of 3 / 1.5 @ 0.5A cm. -2 The discharge current density is 0.5 A cm⁻¹. -2 .

[0068] Test results are attached to the instruction manual. Figure 2-3 Wherein, 20% PTFE means that the mass of PTFE in the solid components of the catalyst layer slurry accounts for 20 wt% of the total mass (excluding the mass of HBM), representing Comparative Example 1; HBM / C = 0.03 means that the mass ratio of hyperbranched sulfonated polyamide (HBM) to carbon in the catalyst layer slurry is 0.03, representing Example 1.

[0069] See Figure 2The polarization characteristic curves of the membrane electrode with the cathode composition of Example 1 and Comparative Example 1 were measured. As can be seen from the figure, at 0.1 A / cm... 2 Under these conditions, the voltages of the membrane electrodes corresponding to the cathode compositions of Example 1 and Comparative Example 1 were measured to be 0.692V and 0.691V, respectively; at 0.5A / cm 2 Under these conditions, the voltages of the membrane electrodes corresponding to the cathode compositions of Example 1 and Comparative Example 1 were measured to be 0.574V and 0.565V, respectively; at 1.0A / cm 2 The measured voltages of the membrane electrodes corresponding to the cathode compositions of Example 1 and Comparative Example 1 were 0.476V and 0.456V, respectively; the measured maximum power densities of the membrane electrodes corresponding to the cathode compositions of Example 1 and Comparative Example 1 were 0.586W / cm², respectively. 2 0.510W / cm 2 Compared to the membrane electrode with the cathode composition of Comparative Example 1, the membrane electrode with the hyperbranched sulfonated polyamide cathode catalyst layer in Example 1 of this invention has a maximum power density that is 76 mW / cm² higher than that of the membrane electrode with the cathode composition of Comparative Example 1. 2 Especially in the high current density region, under the same current density, the battery voltage limit of Embodiment 1 of the present invention is higher than the membrane electrode voltage corresponding to the cathode composition of Comparative Example 1, resulting in higher overall battery performance.

[0070] See Figure 3 Impedance spectra show that, compared to Comparative Example 1, Example 1 exhibits significantly lower impedance in the high, mid, and low frequency regions. Since both examples use the same anode composition, the anode impedance is not significantly different. However, the most significant difference lies in the charge transfer resistance of the cathode, where Example 1 is markedly lower than Comparative Example 1. This is primarily due to the introduction of hyperbranched sulfonated polyamide (HBM) molecules into the cathode of Example 1. Their large IEC (intercalation ionization) greatly enhances the proton conductivity of the cathode catalyst layer, reducing charge transfer resistance at the three-phase interface of the catalyst layer. Simultaneously, their redistribution effect on PA allows for stable operation in the low-frequency mass transfer region, preventing deterioration of the three-phase interface of the cathode catalyst layer in the high current density region, thus significantly reducing mass transfer polarization.

[0071] In summary, this invention utilizes hyperbranched sulfonated polyamide (HBM) as the ionomer for the cathode catalyst layer. Hyperbranched sulfonated polyamide molecules not only have a high IEC (intercalation efficiency), but also, due to their hyperbranched structure, a high geometric density of sulfonic acid groups. This ensures proton movement between sulfonic acid groups even under water-deficient conditions, allowing them to function as a three-phase interface even in the absence of water and PA (phosphoric acid). Furthermore, the surface groups of HBM can be controlled to -NH2, and its strong basicity allows for effective PA enrichment even when PA content in the catalyst layer is insufficient. This greatly ensures the effective distribution of phosphoric acid in the catalyst layer, preventing acid flooding of the cathode catalyst layer, significantly increasing the three-phase interface within the electrode, and improving catalyst utilization, battery performance, and lifespan. Moreover, due to the presence of surface groups on HBM molecules, they can be precisely anchored to nanoparticles on the surface of supported catalysts (such as PtCo / C) through hydrogen bonding, achieving the construction of a nanoscale three-phase interface on the catalyst surface. The introduction of this hyperbranched sulfonated polyamide molecule reduces the dependence of the catalyst layer on traditional polymer ionomers. While improving the proton transport efficiency at the three-phase interface, it can also optimize the multiphase mass transport of the catalyst layer and solve the mass transfer problem existing in traditional catalyst layers.

[0072] 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 membrane electrode, characterized in that, It comprises: a cathode catalyst layer, wherein the cathode catalyst layer comprises a cathode catalyst and hyperbranched sulfonated polyamide molecules, wherein the cathode catalyst is at least one of Pt / C, PtFe / C or PtCo / C; wherein the mass fraction of the noble metal is 5% to 70%; and the surface groups of the hyperbranched sulfonated polyamide molecules include -NH2.

2. The membrane electrode as described in claim 1, characterized in that, In the cathode catalyst layer, the mass ratio of the hyperbranched sulfonated polyamide to the carbon in the cathode catalyst is 0.01-0.

25.

3. The membrane electrode as described in claim 1, characterized in that, The noble metal loading in the cathode catalyst layer is 0.5-1.0 mg / cm³. 2 .

4. The membrane electrode as described in claim 1, characterized in that, It also includes: a cathode diffusion layer, which comprises a support layer and a microporous layer; the support layer is carbon paper and / or carbon cloth, and the microporous layer comprises carbon powder and PTFE, wherein the PTFE content in the microporous layer is 5%-25% by mass.

5. The membrane electrode as described in claim 4, characterized in that, The carbon powder is at least one of activated carbon, graphitized carbon, carbon nanotubes, carbon nanoribbons, and carbon nanospheres.

6. The membrane electrode as described in claim 1, characterized in that, It also includes: an anode catalyst layer, the anode catalyst layer comprising an anode catalyst and an anode hydrophobic binder, the anode catalyst comprising at least one of Pt / C, PtFe / C or PtCo / C, wherein the mass fraction of the noble metal is 5% to 70%.

7. The membrane electrode as described in claim 6, characterized in that, The noble metal loading in the anode catalyst layer is 0.3-0.5 mg / cm³. 2 .

8. The membrane electrode as described in claim 6, characterized in that, The anolyte is a hydrophobic binder selected from at least one of PTFE, PVDF, FEP, ECTE, ETFE, PFA, and PDMS.

9. A method for preparing a membrane electrode according to any one of claims 1-8, characterized in that, The method includes: S1, the anode catalyst, the anode hydrophobic binder and the surfactant are uniformly dispersed in an aqueous alcohol solution to form the anode catalyst slurry; S2, the anode catalyst slurry is coated onto the anode diffusion layer to obtain the anode; S3, the cathode catalyst and the dissolved hyperbranched sulfonated polyamide molecular solution are uniformly dispersed in an organic solvent to serve as a cathode catalyst slurry; S4, the cathode catalyst slurry is coated onto the cathode diffusion layer to obtain the cathode; S5, the anode, proton exchange membrane and cathode are sequentially bonded together and composited by hot pressing to obtain membrane electrode.

10. A high-temperature proton exchange membrane fuel cell, characterized in that, It comprises: a membrane electrode as described in any one of claims 1-8.

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