High-stability phosphoric acid doped polymer membrane electrode as well as preparation method and application thereof

Abstract

The invention discloses a high-stability phosphoric acid doped polymer membrane electrode which comprises a gas diffusion layer, an outer catalytic layer and an inner catalytic layer, the gas diffusion layer is used as a bottom layer, and the outer catalytic layer and the inner catalytic layer are sequentially stacked on the gas diffusion layer; the loading capacity of platinum (Pt) in the high-stability phosphoric acid doped polymer membrane electrode is 0.05-2 mg / cm < 2 >. A porous carbon material is used as a phosphoric acid sustained-release material, phosphoric acid is confined in a nano pore channel structure of the porous material phosphoric acid sustained-release agent, saturated vapor pressure of phosphoric acid is reduced by utilizing capillary coagulation of pore channels, and host-guest interaction between the pore channels and phosphoric acid water molecules is regulated and controlled through the confinement effect of the nano pore channels, so that the porous material phosphoric acid sustained-release agent is prepared. The hydrogen bond network connection form of phosphoric acid molecules in a pore channel is changed, so that proton transfer is promoted, and the continuity of a phosphoric acid proton transfer channel is kept for a long time.

Description

Technical Field

[0001] The present invention relates to the field of membrane electrodes for high-temperature proton exchange membrane fuel cells, and particularly to a highly stable phosphoric acid-doped polymer membrane electrode, a preparation method thereof, and an application thereof. Background Art

[0002] High-temperature proton exchange membrane fuel cells (HT-PEMFCs) are a type of polymer electrolyte membrane fuel cells that have developed rapidly in recent years and operate at a working temperature between 100 and 200 °C. They have the advantages of high energy conversion efficiency, high power density, clean and pollution-free, and are considered to be the next-generation promising power sources.

[0003] Currently, commercial high-temperature proton exchange membrane fuel cells use phosphoric acid as the proton conductor of the membrane electrode. Due to its mobile characteristics, phosphoric acid will be lost, making it difficult to maintain the continuity of the phosphoric acid proton transfer channels inside the membrane electrode, thus greatly limiting its stability under dynamic operating conditions (such as variable load, variable temperature, etc.).

[0004] Therefore, the key to improving the durability of HT-PEMFCs under dynamic operating conditions lies in maintaining the continuity of the phosphoric acid proton transfer channels in the membrane electrode. Currently, research on this problem mainly focuses on improving the properties of the polymer membrane, such as increasing the acid absorption capacity of the polymer membrane. However, studies have shown that the acid content distribution of membrane electrodes with different initial phosphoric acid contents tends to be the same after activation. Improving the binding ability of the polymer to phosphoric acid molecules is also one of the main research directions, but the modified polymer is prone to degradation under high-temperature strong acid conditions. Although the above strategies can improve the durability of high-temperature proton exchange membrane fuel cells under dynamic operating conditions to a certain extent, the improvement effect is restricted by multiple factors. In addition, existing strategies mostly focus on improving the electrolyte membrane, and less on regulating the phosphoric acid in the catalyst layer. Compared with the strong acid-base interaction between the alkaline polymer and phosphoric acid molecules, the phosphoric acid in the catalyst layer is only affected by the capillary force of the catalyst layer microstructure and the surface tension of the catalyst, and its binding ability to phosphoric acid is weak. Therefore, under dynamic operating conditions, phosphoric acid is more likely to be lost from the catalyst layer.

[0005] Therefore, the essence of solving the problem of low durability of HT-PEMFCs under dynamic operating conditions lies in achieving the controllable migration of phosphoric acid in the electrolyte membrane and the electrode. Since the behavior of free phosphoric acid in the existing HT-PEMFC membrane electrode is similar to that of the bulk solution, its migration in the membrane electrode is more easily affected by the changes in the water vapor content and water partial pressure generated by dynamic operating conditions. Therefore, there is an urgent need to develop a new type of phosphoric acid carrier with a phosphoric acid confinement function, and by regulating its interaction with phosphoric acid / water, to achieve the stable and controllable migration of phosphoric acid in the membrane electrode, and then construct a high-temperature proton exchange membrane fuel cell with high durability under dynamic operating conditions. Summary of the Invention

[0006] To solve the problem that phosphoric acid is easily lost in the membrane electrode of a high-temperature proton exchange membrane fuel cell, resulting in poor dynamic stability, the present invention provides a highly stable phosphoric acid-doped polymer membrane electrode. By using a porous carbon material as a phosphoric acid slow-release material and constructing a composite catalytic layer, the problem that the continuity of the phosphoric acid proton transfer channel in the membrane electrode of a high-temperature proton exchange membrane fuel cell cannot be maintained for a long time is solved, and the dynamic durability of the fuel cell can be effectively improved.

[0007] To achieve the above object, the technical solution provided by the present invention is as follows:

[0008] A highly stable phosphoric acid-doped polymer membrane electrode, comprising a gas diffusion layer, an outer catalytic layer, and an inner catalytic layer. Taking the gas diffusion layer as the bottom layer, the outer catalytic layer and the inner catalytic layer are sequentially stacked on the gas diffusion layer; wherein, the inner catalytic layer contains a platinum (Pt) catalyst and a binder, and the outer catalytic layer is a porous material phosphoric acid slow-release agent and a binder; the gas diffusion layer includes a support layer and a microporous layer; the platinum (Pt) catalyst is one of Pt / C, PtCo / C, PtFe / C, PtNi / C, PtPb / C, Pt / WO 3 、Pt / MO 3 or Pt / TiO 2 ; the amount of the binder in the inner catalytic layer is 5-60% of the mass of the platinum (Pt) catalyst, and the amount of the binder in the outer catalytic layer is 5-60% of the mass of the porous material phosphoric acid slow-release agent; the loading of the noble metal platinum (Pt) in the highly stable phosphoric acid-doped polymer membrane electrode is 0.05-2 mg / cm 2 .

[0009] Further, the binder of the inner catalytic layer and the binder of the outer catalytic layer are both at least one of PTFE (tetrafluoroethylene), PVDF (polyvinylidene fluoride), PBI (polyphenylene benzimidazole), FEP (tetrafluoroethylene), ETFE (ethylene-tetrafluoroethylene copolymer), PDMS (polydimethylsiloxane), or PVP (polyvinylpyrrolidone).

[0010] Further, the porous material phosphoric acid slow-release agent is at least one of mesoporous carbon, cubic mesoporous carbon, hollow mesoporous carbon, ordered mesoporous carbon, carbon nanotubes, C 60 , MOF or COF; preferably hollow mesoporous carbon.

[0011] Further, the porous material phosphoric acid slow-release agent is hollow mesoporous carbon, and the preparation method is to dissolve 3.46 mL of tetrapropyl orthosilicate (TPOS) in a mixed solution (the mixed solution is obtained by mixing 70 mL of absolute ethanol, 10 mL of deionized water, and 3 mL of ammonia water); then 0.4 g of resorcinol and 0.56 mL of formaldehyde are added in sequence, and SiO is generated by stirring at 35 °C for 24 hours2 @RF spheres, and SiO is separated by suction filtration 2 @RF spheres are separated from the suspension and washed with water and absolute ethanol for SiO 2 @RF spheres, and then dried at room temperature; the obtained SiO after drying 2 @RF spheres are carbonized at 700 °C for 5 hours. The atmosphere during carbonization is nitrogen, and the heating rate is 2 °C / min. Finally, SiO 2 @C nanospheres are obtained; template etching treatment is carried out using a 4M sodium hydroxide solution to remove SiO 2 to obtain hollow mesoporous carbon (XFP-18).

[0012] The preparation method of the highly stable phosphoric acid-doped polymer membrane electrode as described above includes the following operating steps:

[0013] (1) Prepare the inner catalyst layer slurry: Weigh the binder and the platinum (Pt)-containing catalyst of the inner catalyst layer according to the amount of the binder being 5-60% of the mass of the platinum (Pt)-containing catalyst, and mix the platinum (Pt)-containing catalyst and the binder to obtain the inner catalyst layer slurry;

[0014] (2) Prepare the outer catalyst layer slurry: Weigh the binder and the porous material phosphoric acid slow-release agent of the outer catalyst layer according to the amount of the binder being 5-60% of the mass of the porous material phosphoric acid slow-release agent, and mix the porous material phosphoric acid slow-release agent and the binder to obtain the outer catalyst layer slurry;

[0015] (3) Coat the outer catalyst layer slurry obtained in step (2) on one side of the microporous layer of the gas diffusion layer. After the outer catalyst layer slurry dries in 3-5 minutes, continue to coat the inner catalyst layer slurry obtained in step (1), and heat-treat at 50-400 °C under a protective atmosphere to obtain a highly stable phosphoric acid-doped polymer membrane electrode. After the heat treatment, the original outer catalyst slurry layer is the outer catalyst layer, and the inner catalyst slurry layer is the inner catalyst layer, that is, a highly stable phosphoric acid-doped polymer membrane electrode is obtained. The loading of the noble metal platinum (Pt) in the membrane electrode is 0.05-2 mg / cm 2 .

[0016] Furthermore, the coating process in step (3) is one of transfer printing, ultrasonic spraying or blade coating; in step (3), heat treatment is carried out at 350 °C for 2 hours under the protective atmosphere, and the protective atmosphere is nitrogen, or a mixed gas of hydrogen and argon; the hydrogen accounts for 5% of the volume ratio of the mixed gas of hydrogen and argon. The application of using the highly stable phosphoric acid-doped polymer membrane electrode as described above as the cathode in the preparation of the membrane electrode of a high-temperature proton exchange membrane fuel cell.

[0017] A high-temperature proton exchange membrane fuel cell membrane electrode, comprising a cathode, a phosphoric acid-doped proton exchange membrane, and an anode arranged in sequence; the cathode is the above-mentioned high-stability phosphoric acid-doped polymer membrane electrode; the catalytic layer in the cathode and the anode catalytic layer are both in close contact with the phosphoric acid-doped proton exchange membrane; after the cathode, the phosphoric acid-doped proton exchange membrane, and the anode are sequentially laminated, they are prepared by hot pressing using a hot pressing method.

[0018] Further, the anode is an anode membrane electrode obtained by coating a catalytic layer on one side of the microporous layer of the gas diffusion layer; the preparation method of the anode membrane electrode is as follows:

[0019] (1) Preparation of the anode catalytic layer slurry (the following are all mass ratios): According to the mass ratio of 40wt% Pt / C catalyst: 3wt% polytetrafluoroethylene (PTFE) aqueous solution: deionized water: isopropanol = 5: 1: 266: 333, weigh 40wt% Pt / C catalyst, 3wt% PTFE aqueous solution, deionized water and anhydrous isopropanol. After ultrasonic dispersing the 40wt% Pt / C catalyst, deionized water and anhydrous isopropanol for 1 hour, slowly drop the 3wt% PTFE aqueous solution, and after ultrasonic dispersing evenly, obtain the anode catalytic layer slurry; the 3wt% PTFE aqueous solution is prepared by mixing PTFE and deionized water to form a 3wt% PTFE aqueous solution;

[0020] (2) Preparation of the anode membrane electrode: The anode catalytic layer slurry obtained in step (1) is uniformly coated on one side of the anode gas diffusion layer containing the microporous layer by ultrasonic spraying; after spraying, it is calcined in a tubular furnace at 350°C for 2 hours under a nitrogen protection atmosphere, and the pressure of the nitrogen protection atmosphere is 1 atmosphere to obtain the anode membrane electrode; the platinum loading in the anode catalytic layer is 0.5 - 1.0mg / cm 2 .

[0021] Further, the phosphoric acid-doped proton exchange membrane is obtained by soaking the proton exchange membrane in phosphoric acid; the mass concentration of the phosphoric acid is 50% - 85%, the soaking temperature is 25 - 160°C; the soaking time is 2 - 72h; the proton exchange membrane is at least one of a polybenzimidazole proton exchange membrane, a polyvinylimidazole proton exchange membrane, a polyvinylpyrrolidone proton exchange membrane, and a polyarylene piperidine proton exchange membrane; the thickness of the proton exchange membrane is 30 - 200μm, the proton conductivity is 0.01 - 0.50S / cm, and the mechanical tensile strength is 5 - 200Mpa.

[0022] Application of the membrane electrode of the high-temperature proton exchange membrane fuel cell in the preparation of the high-temperature proton exchange membrane fuel cell: Installing the membrane electrode into the mold of the high-temperature proton exchange membrane fuel cell and introducing gas makes it a fuel cell; when the high-temperature proton exchange membrane fuel cell works, hydrogen is introduced into the anode side, and hydrogen oxidation reaction (HOR) occurs at the anode, air or oxygen is introduced into the cathode side, and oxygen reduction reaction (ORR) occurs at the cathode; the working temperature of the high-temperature proton exchange membrane fuel cell is 120 - 240 °C.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The present invention uses a porous carbon material as a phosphoric acid slow-release material, confines phosphoric acid in the nano-pore structure of the porous material phosphoric acid slow-release agent, reduces the saturated vapor pressure of phosphoric acid by the capillary condensation effect of the pores, and at the same time regulates the host-guest interaction between the pores and phosphoric acid water molecules through the confinement effect of the nano-pores to reduce its phosphoric acid loss rate and change the hydrogen bond network connection form of phosphoric acid molecules in the pores, thereby promoting its proton transfer; thus enabling the continuity of the phosphoric acid proton transfer channel to be maintained for a long time.

[0025] (2) The present invention adopts the method of phosphoric acid storage and slow release to make up for the lost phosphoric acid in the electrolyte membrane and the electrode, thereby maintaining the stable continuity of the proton conduction channel in the membrane electrode, breaking through the key technical bottleneck of the membrane electrode design of the existing phosphoric acid-doped high-temperature proton exchange membrane fuel cell, and having good application prospects and practical significance.

[0026] (3) The preparation method of the present invention is simple and is conducive to realizing large-scale production. Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of the highly stable phosphoric acid-doped polymer membrane electrode prepared by the present invention; wherein, 1 - support layer, 2 - microporous layer, 3 - outer catalytic layer, 4 - inner catalytic layer; 1 and 2 are gas diffusion layers.

[0028] Figure 2 SEM diagram of the cathode hierarchical membrane electrode structure of the high-temperature proton exchange membrane fuel cell; wherein, 1 - inner catalytic layer of the highly stable phosphoric acid-doped polymer membrane electrode, 2 - outer catalytic layer of the highly stable phosphoric acid-doped polymer membrane electrode, 3 - gas diffusion layer of the inner catalytic layer of the highly stable phosphoric acid-doped polymer membrane electrode.

[0029] Figure 3 Polarization characteristic curves of the membrane electrodes of the high-temperature proton exchange membrane fuel cell prepared with different porous material phosphoric acid slow-release agents.

[0030] Figure 4 Impedance diagrams of the membrane electrodes of the high-temperature proton exchange membrane fuel cell prepared with different porous material phosphoric acid slow-release agents.

[0031] Figure 5 Discharge stability of membrane electrodes of high-temperature proton exchange membrane fuel cells prepared with different porous material phosphoric acid sustained-release agents. Specific embodiments

[0032] The following describes the specific embodiments in detail with reference to the accompanying drawings. However, it should be understood that the protection scope of the present invention is not limited by the specific embodiments. The raw materials and reagents used in the examples are all commercially available unless otherwise specified. The gas diffusion layer was purchased from Beijing Haidelizi New Technology Co., Ltd. This gas diffusion layer has a support layer and a microporous layer. The support layer is carbon fiber, and the microporous layer is layered graphite. Vulcan XC-72 carbon powder was purchased from Cabot Corporation, USA; platinum (Pt)-containing catalysts 50wt% PtCo / C and 40wt% Pt / C were both purchased from Johnson Matthey Co., Ltd., UK; the high-temperature proton exchange membrane fuel cell mold was purchased from Beijing Haidelizi New Technology Co., Ltd.

[0033] The mesoporous carbon XFP-12, cubic mesoporous carbon CMK-8, and hollow mesoporous carbon XFP-18 used in the examples were prepared by the following methods:

[0034] Mesoporous carbon XFP-12: 1 g of zinc nitrate and 1 g of furan were mixed in 100 mL of deionized water containing 2 g of NaOH, and then subjected to high-temperature carbonization at 700 °C in a nitrogen atmosphere for 5 hours, with a heating rate of 2 °C / min, thereby obtaining mesoporous carbon XFP-12.

[0035] Cubic mesoporous carbon CMK-8: 2 g of SiO 2 particles were placed in a mixed solution of 200 mL of phenolic resin solution (phenol concentration 1M - 3M, 37% aqueous formaldehyde solution) and 50 mL of 1M NaOH solution and stirred for 2 h. Subsequently, high-temperature carbonization treatment was carried out at 700 °C in a nitrogen atmosphere for 5 hours, with a heating rate of 2 °C / min. Finally, the SiO 2 template was removed using 5% - 10% HF solution to obtain cubic mesoporous carbon CMK-8.

[0036] Hollow mesoporous carbon XFP-18: 3.46 mL of tetrapropyl orthosilicate (TPOS) was dissolved in a mixed solution (the mixed solution was obtained by mixing 70 mL of absolute ethanol, 10 mL of deionized water, and 3 mL of ammonia water), and then 0.4 g of resorcinol and 0.56 mL of formaldehyde were added in sequence. Stirring was carried out at 35 °C for 24 hours to generate SiO 2 @RF spheres. The SiO 2 @RF spheres were separated from the suspension by suction filtration, and the SiO 2 @RF spheres were washed with water and absolute ethanol, and then dried at room temperature; the dried SiO 2The @RF spheres were carbonized at 700 °C for 5 hours. The atmosphere during carbonization was nitrogen, and the heating rate was 2 °C / min. Finally, SiO 2 @C nanospheres were obtained. The template was etched using a 4M sodium hydroxide solution to remove SiO 2 and thus hollow mesoporous carbon (XFP-18) was obtained.

[0037] In the following examples, a 3wt% PTFE aqueous solution (prepared by adding deionized water to commercially available PTFE to form a 3wt% PTFE aqueous solution) was used.

[0038] Example 1

[0039] A preparation method of a highly stable phosphoric acid-doped polymer membrane electrode is as follows:

[0040] (1) Preparation of the inner catalytic layer slurry (the following are all mass ratios): According to the mass ratio of 50wt% PtCo / C catalyst: PTFE: deionized water: isopropanol = 5:1:266:333, weigh 50wt% PtCo / C catalyst, deionized water and isopropanol. After ultrasonic dispersion for 1 hour, slowly drop 3wt% PTFE aqueous solution, and after ultrasonic dispersion evenly, the inner catalytic layer slurry is obtained.

[0041] (2) Preparation of the outer catalytic layer slurry (the following are all mass ratios): According to the mass ratio of porous material phosphoric acid slow-release agent: PTFE: deionized water: isopropanol = 5:1:266:333, weigh hollow mesoporous carbon (XFP-18), deionized water and isopropanol. After ultrasonic dispersion for 1 hour, slowly drop 3wt% PTFE aqueous solution, and after ultrasonic dispersion evenly, stir for 0.5 hour, and after ultrasonic dispersion evenly, ball mill for 4 hours to obtain the outer catalytic layer slurry.

[0042] (3) Ultrasonically spray the outer catalytic layer slurry obtained in step (2) on one side of the microporous layer of the gas diffusion layer. After the outer catalytic layer slurry dries in 3 - 5 minutes, ultrasonically spray the inner catalytic layer slurry obtained in step (1) on the dried outer catalytic layer, ensuring that the platinum loading is 0.6 mg / cm 2 When the thickness of the outer catalytic layer reaches about 25 microns and the thickness of the inner catalytic layer reaches about 15 microns. After spraying, use a tube furnace to calcine at 350 °C for 2 h under a nitrogen protection atmosphere, and the pressure of the nitrogen protection atmosphere is 1 atmosphere to obtain a highly stable phosphoric acid-doped polymer membrane electrode. See Figure 1 The highly stable phosphoric acid-doped polymer membrane electrode (cathode) is composed of a gas diffusion layer, an outer catalytic layer and an inner catalytic layer.

[0043] Example 2

[0044] In step (2), replace "hollow mesoporous carbon XFP-18" with "mesoporous carbon XFP-12", and keep the rest of the operations the same as those in step of Example 1 to obtain a highly stable phosphoric acid-doped polymer membrane electrode.

[0045] Example 3

[0046] In step (2), replace "hollow mesoporous carbon XFP-18" with "cubic mesoporous carbon CMK-8", and keep the rest of the operations the same as those in step of Example 1 to obtain a highly stable phosphoric acid-doped polymer membrane electrode.

[0047] Comparative Example 1

[0048] In step (2), replace "hollow mesoporous carbon XFP-18" with "Vulcan XC-72 carbon powder", and keep the rest of the operations the same as those in step of Example 1 to obtain a highly stable phosphoric acid-doped polymer membrane electrode.

[0049] Comparative Example 2

[0050] A preparation method of a phosphoric acid-doped polymer membrane electrode without a phosphoric acid slow-release layer, without the preparation process of the outer catalyst layer in step (2), and keep the rest of the operations the same as those in step of Example 1 to obtain a phosphoric acid-doped polymer membrane electrode without a phosphoric acid slow-release layer. The operation steps are as follows:

[0051] (1) Preparation of the inner catalyst layer slurry (the following are all mass ratios): According to the mass ratio of 50wt% PtCo / C catalyst: PTFE: deionized water: isopropanol = 5:1:266:333, weigh 50wt% PtCo / C catalyst, deionized water and isopropanol, ultrasonically disperse for 1 hour, and then slowly drop 3wt% PTFE aqueous solution. After ultrasonically dispersing evenly, obtain the inner catalyst layer slurry.

[0052] (2) Ultrasonically spray the inner catalyst layer slurry obtained in step (1) on the microporous layer side of the gas diffusion layer, ensuring that the platinum loading is 0.6mg / cm 2 When the inner catalyst layer thickness reaches about 15 microns. After spraying, use a tube furnace to calcine at 350°C for 2h under a nitrogen protection atmosphere, and the pressure of the nitrogen protection atmosphere is 1 atmosphere to obtain a phosphoric acid-doped polymer membrane electrode without a phosphoric acid slow-release layer.

[0053] Example 4

[0054] A preparation method of an anode membrane electrode of a high-temperature proton exchange membrane fuel cell. The operation steps are as follows:

[0055] (1) Preparation of the anode catalytic layer slurry (the following are all mass ratios): According to the mass ratio of 40 wt% Pt / C catalyst: 3 wt% polytetrafluoroethylene (PTFE) aqueous solution: deionized water: isopropanol = 5: 1: 266: 333, weigh 40 wt% Pt / C catalyst, 3 wt% PTFE aqueous solution, deionized water and anhydrous isopropanol. After ultrasonic dispersing the 40 wt% Pt / C catalyst, deionized water and isopropanol for 1 hour, then slowly drop the 3 wt% PTFE aqueous solution, and after ultrasonic dispersing evenly, the anode catalytic layer slurry is obtained;

[0056] (2) Preparation of the anode membrane electrode: The anode catalytic layer slurry obtained in step (1) is uniformly coated on the side of the anode gas diffusion layer containing the microporous layer by ultrasonic spraying. After spraying, it is calcined in a tubular furnace at 350 °C for 2 hours under a nitrogen protection atmosphere, and the pressure of the nitrogen protection atmosphere is 1 atmospheric pressure to obtain the anode membrane electrode of the high-temperature proton exchange membrane fuel cell. The platinum loading in the anode catalytic layer is 0.8 mg / cm 2 , and the thickness of the anode catalytic layer is about 30 microns.

[0057] Example 5

[0058] Preparation of the high-temperature proton exchange membrane PBI / H 3 PO 4 composite membrane (phosphoric acid-doped proton exchange membrane): The polybenzimidazole (PBI) proton exchange membrane uses the PPtec membrane of Beijing Haidelizi New Technology Co., Ltd. The thickness of the proton exchange membrane is 30 - 200 μm, the proton conductivity is 0.01 - 0.50 S / cm, and the mechanical tensile strength is 5 - 200 Mpa. The PBI / H 3 PO 4 composite membrane is prepared by the impregnation method. First, cut the PBI proton exchange membrane into the required size. Secondly, soak the cut membrane in 85 wt% phosphoric acid at 40 °C for 12 hours, dry the excess phosphoric acid on the surface of the PBI membrane with filter paper, and quickly weigh it to obtain a PBI proton exchange membrane with a phosphoric acid doping amount of 330%, and the thickness is 80 microns, which is the high-temperature proton exchange membrane PBI / H 3 PO 4 composite membrane.

[0059] Example 6

[0060] Respectively use the highly stable phosphoric acid-doped polymer membrane electrodes prepared in Example 1, Example 2, Example 3, Comparative Example 1, and Comparative Example 2 as the cathode, the anode membrane electrode of the high-temperature proton exchange membrane fuel cell prepared in Example 4 as the anode, and the high-temperature proton exchange membrane PBI / H 3 PO 4The composite membrane serves as a proton exchange membrane. Stack the cathode, proton exchange membrane, and anode in the high-temperature proton exchange membrane fuel cell test mold in the order of "first place the anode, then the proton exchange membrane, and finally the cathode", and then place it in a hot press. Heat press at 160 °C under a pressure of 900 KG for 10 minutes, and take it out after cooling to room temperature to press into an effective area of 45 cm 2 The membrane electrode is formed and sealed for standby, and 4 different high-temperature proton exchange membrane fuel cell membrane electrodes are obtained respectively.

[0061] Example 7

[0062] Put the 5 different high-temperature proton exchange membrane fuel cell membrane electrodes obtained in Example 6 into the high-temperature proton exchange membrane fuel cell mold respectively, and ventilate to obtain a high-temperature proton exchange membrane fuel cell. When the high-temperature proton exchange membrane fuel cell works, hydrogen is introduced into the anode side, and the HOR reaction occurs at the anode. Air or oxygen is introduced into the cathode side, and the ORR reaction occurs at the cathode. The working temperature is 120 - 240 °C.

[0063] Performance detection

[0064] In the performance detection, the high-temperature proton exchange membrane fuel cell prepared in Example 7 is used for testing:

[0065] Refer to GB / T20042.5 - 2009 to conduct polarization curve tests on the above-obtained high-temperature proton exchange membrane fuel cell membrane electrodes. The specific operating conditions are: the working temperature of the high-temperature proton exchange membrane fuel cell is 160 °C, the anode is fed with pure hydrogen, the cathode is fed with atmospheric air, and the cathode / anode feeds are 1.5 / 3 times the stoichiometric ratio respectively.

[0066] Refer to GB / T20042.5 - 2009 to conduct impedance detection on the above-obtained high-temperature proton exchange membrane fuel cell membrane electrodes. The specific operating conditions are: the working temperature of the high-temperature proton exchange membrane fuel cell is 160 °C, the anode is fed with pure hydrogen, the cathode is fed with atmospheric air, the cathode / anode feeds are 1.5 / 3 times the stoichiometric ratio respectively, and the discharge current density is 0.5 Acm -2 .

[0067] Refer to GB / T20042.5 - 2009 to conduct operating condition stability tests on the above-obtained high-temperature proton exchange membrane fuel cell membrane electrodes. The specific operating conditions are: the working temperature of the high-temperature proton exchange membrane fuel cell is 160 °C, the anode is fed with pure hydrogen, the cathode is fed with atmospheric air, the cathode / anode feeds are 1.5 / 3 times the stoichiometric ratio respectively, and the discharge current density is 0.2 Acm -2 .

[0068] The test results are shown in Figure 3 、 Figure 4 and Figure 5:Comparative Example 1 is a cathode structure with a double catalyst layer composed of Vulcan XC-72 carbon powder (outer cathode catalyst layer) and PtCo / C (inner cathode catalyst layer); Comparative Example 2 is a cathode structure with a single catalyst layer composed of PtCo / C; Example 2 is a cathode structure with a double catalyst layer composed of mesoporous carbon (outer cathode catalyst layer) and PtCo / C (inner cathode catalyst layer), Example 3 is a cathode structure with a double catalyst layer composed of cubic mesoporous carbon (outer cathode catalyst layer) and PtCo / C (inner cathode catalyst layer), and Example 1 is a cathode structure with a double catalyst layer composed of hollow mesoporous carbon (outer cathode catalyst layer) and PtCo / C (inner cathode catalyst layer).

[0069] Under this condition, it can be seen that the performance of the membrane electrode corresponding to the hollow mesoporous carbon as the catalyst layer of the porous material phosphoric acid slow-release agent is relatively high, and the current density corresponding to 0.6V can reach 421.3mAcm -2 , at a current density of 0.5Acm -2 the voltage can reach 580.9mV.

[0070] From Figure 5 the battery discharge stability graph, it can be seen that Example 1 corresponding to the catalyst layer containing the hollow carbon material still maintains a battery performance of more than 0.6V after 1900h of stability test, and from Figure 4 the impedance spectrum graph, it can be seen that the change in the cathode charge transfer resistance is relatively small. This is mainly because the hollow carbon porous material phosphoric acid slow-release agent contained in the outer cathode catalyst layer makes the cathode structure of the membrane electrode more conducive to the uniform distribution of phosphoric acid, and its unique hollow mesoporous structure can store and slow-release phosphoric acid to a great extent during the migration of phosphoric acid, avoiding the reduction of the number of three-phase interfaces caused by the loss of phosphoric acid, thereby reducing the losses of activation polarization and ohmic polarization and improving the battery performance.

[0071] Comparative Example 2 without a phosphoric acid slow-release layer has the worst performance, and the current density corresponding to 0.6V can only reach 150mAcm -2 , at a current density of 0.5Acm -2 the voltage can only reach 421.6mV. Comparative Example 1 with Vulcan XC-72 carbon powder as the phosphoric acid slow-release layer of the outer cathode catalyst layer has relatively poor performance, and the current density corresponding to 0.6V is 358.9mAcm -2 , at a current density of 0.5Acm -2 the voltage is 562.9mV.

[0072] From Figure 5It can be seen from the battery discharge stability diagram that for the membrane electrode corresponding to the catalytic layer using Vulcan XC-72 carbon powder as the outer porous material and phosphoric acid slow-release agent, in Comparative Example 1, the battery potential dropped below 0.6V only after 500h, while in Comparative Example 2, the battery potential dropped below 0.6V only after 400h. This is mainly because the Vulcan XC-72 carbon powder in the cathode outer catalytic layer of Comparative Example 1 does not have a hollow structure, and Comparative Example 2 does not have a phosphoric acid slow-release layer, resulting in an extremely fast loss rate of phosphoric acid. The phosphoric acid in the membrane cannot be evenly distributed, the retention ability of phosphoric acid is poor, it becomes more difficult for gas to contact the electrolyte solvent, and the proton transfer channel is interrupted, thus resulting in relatively large losses of activation polarization and ohmic polarization and poor performance of the membrane electrode assembly.

[0073] The foregoing description of the specific exemplary embodiments of the present invention is for purposes of illustration and exemplification. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many modifications and variations are possible in light of the above teaching. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical applications, so that those skilled in the art can implement and utilize various different exemplary embodiments of the invention, as well as various different selections and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A highly stable phosphoric acid-doped polymer membrane electrode, characterized in that: The invention comprises a gas diffusion layer, an outer catalytic layer and an inner catalytic layer, wherein the gas diffusion layer is used as a bottom layer, and the outer catalytic layer and the inner catalytic layer are sequentially stacked on the gas diffusion layer; wherein the inner catalytic layer is a platinum-containing catalyst and a binder, and the outer catalytic layer is a porous material phosphate slow-release agent and a binder; the gas diffusion layer comprises a support layer and a microporous layer; the platinum-containing catalyst is one of Pt / C, PtCo / C, PtFe / C, PtNi / C, PtPb / C, Pt / WO3, Pt / MO3 or Pt / TiO2; the amount of binder in the inner catalytic layer is 5-60% of the mass of the platinum (Pt) catalyst, and the amount of binder in the outer catalytic layer is 5-60% of the mass of the porous material phosphate slow-release agent; the platinum (Pt) loading in the high-stability phosphoric acid-doped polymer membrane electrode is 0.05-2 mg / cm 2 .

2. The highly stable phosphoric acid-doped polymer membrane electrode according to claim 1, characterized in that: The binder of the inner catalytic layer and the binder of the outer catalytic layer are at least one of PTFE, PVDF, PBI, FEP, ETFE, PDMS or PVP.

3. The highly stable phosphoric acid-doped polymer membrane electrode according to claim 1, characterized in that: The porous material phosphate slow-release agent is mesoporous carbon, cubic structure mesoporous carbon, hollow mesoporous carbon, ordered mesoporous carbon, carbon nanotubes, C 60 , MOF or COF; preferably hollow mesoporous carbon.

4. The highly stable phosphoric acid-doped polymer membrane electrode according to claim 1, characterized in that: The porous material phosphate sustained-release agent is hollow mesoporous carbon, and the preparation method is as follows: 3.46 mL of tetrapropoxysilane is dissolved in a mixed solution (, wherein the mixed solution is obtained by mixing 70 mL of anhydrous ethanol, 10 mL of deionized water, and 3 mL of ammonia water; then 0.4 g of resorcinol and 0.56 mL of formaldehyde are added in sequence, and SiO2@RF spheres are generated by stirring at 35° C. for 24 hours, and the SiO2@RF spheres are filtered, and the SiO2@RF spheres are cleaned, and then dried at room temperature; the SiO2@RF spheres obtained after drying are carbonized at 700° C. for 5 hours, the atmosphere during carbonization is nitrogen, and the heating rate is 2° C. / min, and finally SiO2@C nanospheres are obtained; and a 4M sodium hydroxide solution is used for template corrosion treatment, so as to obtain hollow mesoporous carbon.

5. The method for preparing a highly stable phosphoric acid-doped polymer membrane electrode according to any one of claims 1 to 4, characterized in that: The following steps are included: (1) preparing an inner catalyst layer slurry: weighing the binder of the inner catalyst layer and the platinum (Pt)-containing catalyst according to the amount of the binder being 5-60% of the mass of the platinum (Pt)-containing catalyst, mixing the platinum (Pt)-containing catalyst and the binder to obtain an inner catalyst layer slurry; (2) preparing an outer catalyst layer slurry: according to the amount of the binder being 5-60% of the mass of the porous material phosphate slow-release agent, weighing the binder of the outer catalyst layer and the porous material phosphate slow-release agent, mixing the porous material phosphate slow-release agent and the binder to obtain an outer catalyst layer slurry; (3) coating the outer catalyst layer slurry obtained in step (2) on one side of the microporous layer of the gas diffusion layer, and after the outer catalyst layer slurry is dried, continuing to coat the inner catalyst layer slurry obtained in step (1), and heating at 50-400° C. under a protective atmosphere to obtain a highly stable phosphoric acid-doped polymer membrane electrode, that is, a highly stable phosphoric acid-doped polymer membrane electrode.

6. The method for preparing the highly stable phosphoric acid-doped polymer membrane electrode according to claim 5, characterized in that: The coating process described in step (3) is one of transfer printing, ultrasonic spraying or scraping; the heating treatment at 350°C for 2 hours under the protective atmosphere described in step (3) is nitrogen, or a mixture of hydrogen and argon; the hydrogen accounts for 5% of the volume ratio of the mixture of hydrogen and argon. The application of the highly stable phosphoric acid-doped polymer membrane electrode as described above as a cathode in the preparation of a high-temperature proton exchange membrane fuel cell membrane electrode.

7. A high-temperature proton exchange membrane fuel cell membrane electrode, comprising a cathode, a phosphoric acid-doped proton exchange membrane and an anode arranged in sequence; the cathode is a phosphoric acid-doped polymer membrane electrode with high stability as claimed in any one of claims 1 to 4 and 6, characterized in that: The cathode is closely attached to the phosphoric acid-doped proton exchange membrane; the cathode, the phosphoric acid-doped proton exchange membrane and the anode are attached in sequence and then hot-pressed to obtain the product.

8. The high temperature proton exchange membrane fuel cell membrane electrode according to claim 7, characterized in that: The anode is an anode membrane electrode, which is obtained by coating a catalyst layer on one side of a gas diffusion layer microporous layer; the preparation method of the anode membrane electrode has the following operating steps: (1) Preparation of anode catalyst layer slurry: according to the mass ratio of 40% Pt / C catalyst: 3% PTFE aqueous solution: water: isopropanol = 5:1:266:333, weigh 40% Pt / C catalyst, 3% PTFE aqueous solution, water and isopropanol, ultrasonically disperse the 40% Pt / C catalyst, water and isopropanol for 1 hour, then slowly drop 3% PTFE aqueous solution into it, and ultrasonically disperse it uniformly to obtain the anode catalyst layer slurry; the 3% PTFE aqueous solution is a 3wt% PTFE aqueous solution prepared by adding PTFE and deionized water; (2) Preparation of anode membrane electrode: The anode catalyst layer slurry obtained in step (1) is uniformly coated on the side of the anode gas diffusion layer containing the microporous layer by ultrasonic spraying; after spraying, it is calcined at 350° C. for 2 hours in a nitrogen protective atmosphere with a nitrogen protective atmosphere pressure of 1 atmosphere to obtain an anode membrane electrode; the platinum loading in the anode catalyst layer is 0.5-1.0 mg / cm 2 .

9. The high temperature proton exchange membrane fuel cell membrane electrode according to claim 7, characterized in that: The phosphoric acid-doped proton exchange membrane is obtained by soaking the proton exchange membrane in phosphoric acid; the mass concentration of the phosphoric acid is 50%-85%, the soaking temperature is 25-160°C, and the soaking time is 2-72h; the proton exchange membrane is at least one of a polybenzimidazole proton exchange membrane, a polyvinyl imidazole proton exchange membrane, a polyvinyl pyrrolidone proton exchange membrane, and a polyarylene piperidine proton exchange membrane; the proton exchange membrane has a thickness of 30-200μm, a proton conductivity of 0.01-0.50S / cm, and a mechanical tensile strength of 5-200Mpa.

10. Use of a high-temperature proton exchange membrane fuel cell membrane electrode as claimed in any one of claims 1 to 4 and 6 to 9 in the preparation of a high-temperature proton exchange membrane fuel cell, characterized in that: A fuel cell is obtained by installing a membrane electrode of a high-temperature proton exchange membrane fuel cell into a mold of a high-temperature proton exchange membrane fuel cell and ventilating the mold. When the high-temperature proton exchange membrane fuel cell is working, hydrogen is introduced into the anode, hydrogen oxidation (HOR) occurs at the anode, and air or oxygen is introduced into the cathode, and oxygen reduction (ORR) occurs at the cathode. The operating temperature of the high-temperature proton exchange membrane fuel cell is 120-240°C.

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