WO2018113485A1 - Membrane electrode of high power density proton exchange membrane fuel cell and preparation method therefor - Google Patents

Abstract

A membrane electrode of a high power density proton exchange membrane fuel cell and a preparation method therefor. In the method, the power density of the membrane electrode is greatly increased by reducing the thickness of a solid electrolyte, reducing the thickness of a catalyst layer by using a high catalyst content, and introducing carbon nanotubes or carbon fibers to a cathode catalyst layer (3) and/or a gas diffusion layer to improve the mass transfer between the catalyst layer and the diffusion layer. The preparation method is simple, practical and feasible, and has a low cost; and can be used for reducing the thickness of a membrane electrode while improving the performance of the membrane electrode, facilitating the preparation of high power density fuel cells, galvanic piles and systems.

Description

High power density proton exchange membrane fuel cell membrane electrode and preparation method thereof

Technical field

The present invention relates to the field of proton exchange membrane fuel cells, and in particular to a high power density membrane electrode comprising a hydrophilic carbon nanotube or a carbon nanotube as a cathode catalytic layer or a cathode gas diffusion layer and a preparation method thereof.

Background technique

 Proton exchange membrane fuel cell ( PEMFC It is a new type of green energy technology, which has the advantages of high energy conversion efficiency, fast start-up at low temperature, and no pollution. It has broad application prospects in automotive power and small portable power generation equipment. About PEMFC Research has become a hot topic in the field of green energy, and many developed countries are competing to develop this technology.

 Proton exchange membrane fuel cell membrane electrode mainly consists of anode/cathode catalytic layer, anode/cathode gas diffusion layer and Nafion Proton exchange membrane composition. It is well known that the microstructure of the catalytic layer in the membrane electrode is determined by the slurry coated on the proton exchange membrane, and the composition and degree of dispersion of the slurry have a catalyst utilization rate, a proton migration rate, and a diffusion of reactants and products. Great impact. At present, a common catalytic layer is prepared by mixing a catalyst, a binder and a dispersant into a slurry, and then distributing the slurry on both sides of the proton exchange membrane by a coating, transfer or spray method to form a catalytic layer. . The cathode catalytic layer prepared by the conventional method is disadvantageous to the utilization of the catalyst, the transport of the reactants and the product, thereby degrading the performance of the battery. The diffusion and transport of reactants and products in the gas diffusion layer affects the performance of the battery. The common diffusion layer is prepared by dispersing the carbon powder and the binder in an ethanol solvent, dispersing the slurry into a slurry, and then passing the slurry through the scraping. The coating or spraying method is carried on one side of the carbon paper or carbon cloth to form a diffusion layer. The diffusion layer prepared by the conventional method is disadvantageous to the diffusion of the reactants and products to block the pores, thereby lowering the battery performance. Both the catalytic layer and the gas diffusion layer are in contact with the reactants and products, and their structure and properties have a great influence on the output performance and power density of the battery.

 Chinese patent ZL201410568683.0 discloses 'a method for preparing a hydrogen fuel cell membrane electrode' The patent proposes to add a pore-forming agent (ammonium hydrogencarbonate, ammonium oxalate, sodium chloride, etc.) to a conventional catalytic layer material, and the pore-forming agent forms a certain pore in the process of heating and decomposition, thereby increasing the pore size distribution of the membrane electrode. Reduce gas mass transfer resistance.

 Chinese Patent ZL201310333544.5 discloses 'membrane electrode for fuel cell and its preparation method' This patent application adds a thickener (glycerol, ethylene glycol, butyl acetate, etc.) and additives (ammonium hydrogencarbonate, ammonium acetate, dimethicone, etc.) to the conventional catalyst slurry, wherein the thickener Have a higher Dielectric constant and viscosity, ammonium bicarbonate and ammonium acetate in the additive are pore formers, which can also increase the porosity of the catalytic layer. Improve the transport of reactants and products at the high current density of the cathode catalytic layer. However, the pore former introduced in the method generates a toxic gas during the pyrolysis process, and the pore-forming agent pyrolysis is not completely retained in the catalytic layer, thereby causing an increase in the contact resistance of the catalyst layer and lowering the battery performance.

 Chinese patent ZL200710019376.7 discloses 'Preparation method of fuel cell gas diffusion layer' The patent proposes to put carbon paper or carbon cloth into carbon black powder (acetylene black or activated carbon black), distilled water, PTFE or PVDF emulsion, dispersant (XH-1, AEO-9, FC4430, Dip for 0.5-15 minutes in a slurry consisting of Tween-60 or Triton X-100), remove and dry, repeat the above steps until the desired carbon black and PTFE or PVDF are obtained. Carbon paper or carbon cloth. The gas diffusion layer prepared by the method has stable structure and is suitable for large-scale production of fuel cells. However, in the method, the slurry is easily dispersed on both sides and the inner side of the gas diffusion layer substrate, which is unfavorable for controlling the quality of the product, and the prepared microporous layer is not firmly contacted with the substrate, which may bring about an increase in internal resistance of the battery and a decrease in battery performance. .

 Chinese patent ZL201210197913.8 discloses 'based on 3 Ordered single-electrode and membrane electrode of proton-conductor and preparation method ', this patent proposes an ordered membrane electrode with nanofiber array 3 The proton-conductor is a substrate, and a proton conductor nanofiber array is grown on both sides of the proton exchange membrane, and a catalytic layer of active metal is uniformly plated on the array. The membrane electrode prepared by the method increases the contact area between the membrane and the catalytic layer, is beneficial to the diffusion of reactants and products, and accelerates proton transport. However, the ordered structure of the membrane electrode prepared by the method is destroyed by the action of pressure during assembly and assembly, and the assembled fuel cell loses the ordered structure, which is not conducive to the diffusion of reactants and products, and reduces the catalyst. Utilization efficiency.

 Chinese patent ZL201080019534.9 discloses 'gas diffusion layer for fuel cells' This patent proposes to provide a hydrophilic material (activated carbon, zeolite, silica gel, alumina, etc.) having micropores in the gas diffusion layer by diffusing water retained in the cathode catalytic layer during the reaction to have a water absorbing material. In the gas diffusion layer, the phenomenon of hindering the diffusion of the reactant due to the freezing of the product in the cathode catalytic layer during the low-temperature operation can be prevented, thereby improving the starting ability of the battery in a low temperature environment. However, the addition of the water absorbing material increases the amount of stagnant water in the gas diffusion layer, which also hinders the distribution and diffusion of the reactants in the gas diffusion layer, and the addition of the non-conductive water absorbing material increases the internal resistance of the fuel cell, which is disadvantageous for Improved battery performance.

Chinese Patent ZL201010567204.5 discloses 'cathode diffusion layer for proton exchange membrane fuel cells and its preparation and application', which patent adds 5%-10% oxygen storage material (CeO _{2 ) to} conventional diffusion layer slurry. , ZrO ₂ , TiO ₂ , SnO ₂ , InO ₂ , Sb ₂ O _{5 ,} etc.), the diffusion layer has a strong oxygen transmission capacity, and is used for a cathode gas diffusion layer, and the battery performance is remarkably improved. However, the oxygen storage material in the method has poor conductivity or even no conductivity, and the introduction of an oxygen storage material such as CeO ₂ may bring about an increase in internal resistance.

 Chinese patent ZL201410521061.2 discloses 'a method for preparing an electrode suitable for a fuel cell' The patent proposes to add carbon nanotubes or carbon nanofibers to a conventional microporous layer material, and to form a microporous layer by a wet or dry method, the microporous layer can realize reactants and products in the film. Redistribution in the electrodes. The patent also proposes to add a pore-forming agent, which can adjust the pore size distribution of the microporous layer and improve the mass transfer performance of the microporous layer, thereby effectively improving the output performance of the battery.

Although the methods reported above have different effects in improving the performance of the membrane electrode, the power density of the current fuel cell membrane electrode is still low, and the power density of the membrane electrode is highly compatible with a fuel cell system such as an electric vehicle. There is still a huge gap in demand. Therefore, it is still of great significance to further explore the preparation of membrane electrodes with higher power density and their preparation techniques.

Summary of the invention

In order to solve the defects and deficiencies of the prior art, the present invention provides a high power density proton exchange membrane fuel cell membrane electrode and a preparation method thereof, by adding suitable materials in the catalytic layer and the gas diffusion layer and optimizing the electrode fabrication. The process, the resulting catalytic layer and the gas diffusion layer have a high specific surface area, high catalyst exposure, and a significantly increased diffusion capacity of the reactants and products, resulting in a substantial increase in the power density of the resulting membrane electrode.

 The object of the invention is achieved at least by one of the following technical solutions.

 A method for preparing a high power density proton exchange membrane fuel cell membrane electrode comprises the following steps:

 ( 1 The proton exchange membrane is sequentially oxidized and acidified with hydrogen peroxide and sulfuric acid, and then stored in deionized water for storage. When used, the proton exchange membrane is taken out, the surface moisture is absorbed, and it is fixed in a special tool for coating. An anode and a cathode catalytic layer; the proton exchange membrane is a polymer solid electrolyte having different thicknesses;

 (2) pretreating carbon nanotubes or carbon fibers;

(3) A carbon-supported platinum catalyst or an alloy catalyst of platinum with other metals, a perfluorosulfonic acid polymer, pretreated carbon nanotubes or carbon fibers, and a volatile solvent are 10:2-5:0-5:200 After the mass ratio of -2000 is mixed, the ink-like slurry is prepared by ultrasonic dispersion treatment after 0.5-2 hours, and then the ink-like slurry is coated on one side of the proton exchange membrane by spraying or brushing, Pt loading The amount is controlled between 0.1-1 mg cm ^-2 , and then the proton exchange membrane coated with the catalytic layer is heat-treated at 50-80 ° C for 20-60 minutes to prepare a cathode catalytic layer containing carbon nanotubes;

(4) Mixing the carbon-supported platinum catalyst or platinum with other metal alloy catalysts, perfluorosulfonic acid polymer and volatile solvent in a mass ratio of 10:2-5:200-2000, after 0.5-2 hours of ultrasonication After being oscillated, it is dispersed into an ink-like slurry, and the slurry is sprayed on the other side of the proton exchange membrane after the step (3), and the loading of Pt is controlled to be between 0.05 and 0.4 mg cm ^-2 , and then sprayed. A good proton exchange membrane is baked at 50-80 ° C for 20-60 minutes to prepare an anode catalytic layer of the membrane electrode;

 Completely coating an anode catalytic layer and a cathode catalytic layer on both sides of the proton exchange membrane to obtain a three-in-one membrane electrode;

 (5) subjecting the carbon paper to hydrophobic treatment;

(6) Mixing XC-72 toner, polytetrafluoroethylene emulsion, carbon nanotube or carbon fiber and volatile solvent in a mass ratio of 10:1-4:0-5: 200-2000, ultrasonic dispersion 30-80 Minutes, made into an ink-like slurry, which is applied to one side of the hydrophobized carbon paper by spraying and brushing process. The loading capacity of carbon powder, carbon nanotube or carbon fiber is controlled at 2.4-3.4 mg. Cm ^-2 , baking the sprayed carbon paper at 50-80 ° C for 20-60 minutes, drying and then calcining at 340-430 ° C for 0.5-2 hours to obtain a cathode gas diffusion layer; the polytetrafluoroethylene The mass percentage concentration of the emulsion is 10-25 wt%;

 (7) XC-72 toner, polytetrafluoroethylene emulsion and volatile solvent are 10:1-4: 200-2000 The mass is more than mixed, ultrasonically dispersed for 30-80 minutes to prepare an ink-like slurry, which is applied by spraying or brushing to one side of the hydrophobized carbon paper, and the sprayed carbon paper is 50-80 °C Bake for 20-60 minutes, dry and calcine at 340-430 °C for 0.5-2 hours to prepare an anode gas diffusion layer; the concentration concentration of the polytetrafluoroethylene emulsion is 10-25 wt% ;

 (8) affixing the two gas diffusion layers after the treatments of (6) and (7) respectively to the step (4) The corresponding side of the prepared three-in-one membrane electrode is heated at 110-150 degrees for 3-5 minutes, and then subjected to edge sealing treatment; that is, the cathode catalytic layer or the gas diffusion layer contains five-in-one carbon nanotubes. Membrane electrode (Figure 1 ). In the small area test, the hot pressing and edge sealing steps can also be omitted.

A high power density proton exchange membrane fuel cell membrane electrode prepared by introducing carbon nanotubes or carbon fiber materials into a cathode catalyst slurry or a cathode gas diffusion layer.

Further, the carbon nanotubes and carbon fiber materials include one or more of untreated carbon nanotubes or carbon fibers, acid-treated carbon nanotubes or carbon fibers, carbon nanotubes or carbon fibers.

 Further, the proton exchange membrane is a hydrogen proton exchange membrane having a thickness of 20 to 50 micrometers, respectively, including but not limited to the United States. Nafion212, Nafion211 membranes produced by DuPont.

 Further, a catalyst having a high platinum content is used, and the catalyst is Pt/C having a Pt content of 20% - 60% or PtM/C catalyst, where M is Ru, Pd or Au; including but not limited to catalysts from Johanson Matthey.

 Further, the perfluorosulfonic acid polymer is added in the form of a perfluorosulfonic acid polymer solution having a mass percent concentration of 2-5% Nafion solution.

 Further, the volatile solvent is one or more selected from the group consisting of distilled water, ethanol, and isopropyl alcohol.

 Further, the step (2 In the pretreatment of carbon nanotubes or carbon fibers, including acid treatment or nitridation treatment, acid treatment and nitridation treatment;

 The acid treatment or nitridation treatment steps are as follows:

 Place the carbon nano or carbon fiber tube in a concentrated sulfuric acid / concentrated nitric acid solution at a volume ratio of 2.5-3:1 for 20-30 minutes. The mixture is refluxed at 60-90 ° C for 6-12 hours, filtered and washed with deionized water to neutralize the carbon nanotubes or carbon fibers to obtain acid-treated carbon nanotubes or carbon fibers.

 Put the carbon nanotubes or carbon fiber into the quartz tube furnace, adjust the heating program, and control the flow rate of ammonia to 60-150 ml / min. Baking at 700-900 °C for 0.5-3 hours, then lowering to room temperature, replacing ammonia gas with nitrogen or argon to remove ammonia in the system, and taking out the sample to obtain carbon nanotubes;

 The acid treatment and nitridation treatment steps are as follows:

 Place the carbon nano or carbon fiber tube in a concentrated sulfuric acid / concentrated nitric acid solution at a volume ratio of 2.5-3:1 for 20-30 minutes. The mixture is refluxed at 60-90 ° C for 6-12 hours, filtered and washed with deionized water to neutralize the carbon nanotubes or carbon fibers to obtain acid-treated carbon nanotubes or carbon fibers.

 Put the acid-treated carbon nanotubes or carbon fibers into a quartz tube furnace, adjust the temperature program, and control the flow rate of ammonia to 60-150 ml / In the minute, it is calcined at 700-900 °C for 0.5-3 hours, then lowered to room temperature, and the ammonia gas is replaced with nitrogen or argon to remove ammonia in the system, and the sample is taken out to obtain carbon nanotubes.

 further Adding carbon nanotubes or carbon fibers to the catalyst layer and the gas diffusion layer, the carbon nanotubes or nano carbon fibers being untreated carbon nanotubes or carbon fibers, acid-treated carbon nanotubes or carbon fibers, and nitrided carbon nanotubes or carbon fibers, The amount added is the total mass of the catalytic layer or the gas diffusion layer. 5 - 50%.

Further, the specific process of the step (1) is: placing the proton exchange membrane in hydrogen peroxide at a concentration of 5%-15%, boiling at 60-100 °C for 0.5-2 hours, washing with distilled water, and then Place in a 5-1 mol L ^-1 sulfuric acid solution, cook at 60-100 °C for 0.5-2 hours, then wash with distilled water to complete the pretreatment.

 Further, in the step (5), the specific process is: treating the TGP-H-60 carbon paper in acetone 0.5-2 In order to remove surface organic impurities, dry and soak for 2-15 minutes in a 5%-15% by weight polytetrafluoroethylene emulsion, and dry, PTFE accounts for 10% of the weight of the entire carbon paper - 25% After baking at 300 - 500 °C for 0.5 - 2 hours, the polytetrafluoroethylene is sintered in carbon paper to complete the hydrophobic treatment of the carbon paper.

 Compared with the prior art, the invention has the following advantages:

 1. The carbon nanotubes used in the present invention are directly added to the cathode catalyst slurry or the cathode gas diffusion layer slurry, and the introduction of carbon nanotubes or carbon fibers into the cathode catalytic layer can effectively improve the diffusion of the reactants and the utilization efficiency of the cathode catalyst. The introduction of carbon nanotubes or carbon fibers in the cathode diffusion layer can effectively increase the diffusion of reactants and products, thereby improving the battery performance in a large current density region;

 2. The high power density performance of the membrane electrode prepared by the invention is as follows: in the high current density region, the water generated by the cathode catalytic layer can be rapidly diffused into the gas diffusion layer and discharged, and the reaction gas is accelerated to participate in the reaction in the catalytic layer. Thereby achieving the purpose of improving the output performance of the battery.

 3. The preparation method of the high power density membrane electrode of the invention is simple and easy, does not require special equipment and equipment, has low cost and can be mass-produced;

 4. The single cell assembled by using the membrane electrode of the invention has good performance, and the performance in the low current density region is higher than that of the common battery without carbon nanotube or carbon fiber; in the high current density region, the performance is even superior. No performance in adding carbon nanotubes or carbon fiber batteries.

DRAWINGS

 1 is a schematic view showing the structure of a five-in-one membrane electrode with carbon nanotubes added;

 Figure 2 (a) shows the membrane electrode prepared in Examples 1 to 3 and the blank 212 prepared in Comparative Example 1. The membrane electrode and the blank 211 membrane electrode prepared in Comparative Example 2 had a hydrogen-air battery temperature of 70 degrees, a cathode anode back pressure of 30 psi, and a relative humidity of 100%. Comparison of single cell polarization curves;

 Figure 2 (b) shows the membrane electrode prepared in Examples 1 to 3 and the blank 212 prepared in Comparative Example 1. The membrane electrode and the blank 211 membrane electrode prepared in Comparative Example 2 had a hydrogen-air battery temperature of 70 degrees, a cathode anode back pressure of 30 psi, and a relative humidity of 100%. Comparison of single cell power density;

 Figure 3 (a) shows the membrane electrode prepared in Examples 4 to 6 and the blank 212 prepared in Comparative Example 1. The membrane electrode and the blank 211 membrane electrode prepared in Comparative Example 2 had a hydrogen-air fuel cell temperature of 70 degrees, a cathode anode back pressure of 30 psi, and a relative humidity of 100%. Comparison chart of the single cell polarization curves;

 Figure 3 (b) shows the membrane electrode prepared in Examples 4 to 6 and the blank 212 prepared in Comparative Example 1. The membrane electrode and the blank 211 membrane electrode prepared in Comparative Example 2 had a hydrogen-air fuel cell temperature of 70 degrees, a cathode anode back pressure of 30 psi, and a relative humidity of 100%. Comparison of single cell power density;

 Figure 4 (a) shows the membrane electrode prepared in Examples 2, 5, and 7 and the blank 212 prepared in Comparative Example 1. The membrane electrode and the blank 211 membrane electrode prepared in Comparative Example 2 had a hydrogen-air fuel cell temperature of 70 degrees, an anode-anode back pressure of 30 psi, and a relative humidity of 100%. Comparison chart of the single cell polarization curves;

 Figure 4 (b) shows the membrane electrode prepared in Examples 2, 5, and 7 and the blank 212 prepared in Comparative Example 1. The membrane electrode and the blank 211 membrane electrode prepared in Comparative Example 2 had a hydrogen-air fuel cell temperature of 70 degrees, a cathode anode back pressure of 30 psi, and a relative humidity of 100%. The comparison of the single cell power density.

 The components in Figure 1 are as follows: proton exchange membrane 1, anode catalytic layer 2, cathode catalytic layer 3, microporous layer of anode gas diffusion layer 4.1 Microporous layer of cathode gas diffusion layer 4.2, carbon paper 5; microporous layer 4.1 and carbon paper 5 of anode gas diffusion layer are anode gas diffusion layer, microporous layer of cathode gas diffusion layer 4.2 and carbon paper 5 is a cathode gas diffusion layer.

detailed description

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. The embodiments are not described herein, but the embodiments of the present invention are not limited to the following embodiments. Unless otherwise stated, the materials and processing methods employed in the present invention are conventional materials and processing methods in the art.

 Example 1

The first step is to take a 4cm × 4cm Nafion211 proton exchange membrane, firstly treated at 80 °C in 5% by mass of hydrogen peroxide for 1 hour, washed with distilled water, and treated at 0.5 °L ^-1 in sulfuric acid solution at 80 °C. 1 hour, then rinse with distilled water. The treated Nafion membrane was placed on a fixed frame for preparing the membrane electrode, and the active area was 5 cm ² to prevent the membrane from shrinking and deforming during spraying of the catalyst slurry;

 The second step is to soon the carbon nanotubes in a concentrated sulfuric acid / concentrated nitric acid solution at a volume ratio of 3:1 for 30 minutes at 80 °C. After refluxing for 8 hours, filtering and washing the carbon nanotubes with deionized water to neutrality, that is, obtaining acid-treated carbon nanotubes;

 Step 3 Put the second step of acid-treated carbon nanotubes into a quartz tube furnace, adjust the temperature program, and control the flow rate of ammonia to 120 ml / In a minute, calcination at 900 °C for 2 hours, then lowering to room temperature, replacing ammonia gas with nitrogen or argon to remove ammonia in the system, and taking out the sample to obtain carbon nanotubes;

The fourth step is to weigh 4.2 mg Pt/C catalyst (John Matthey) with Pt content of 60% and 33 mg perfluorosulfonic acid polymer solution (5wt% Nafion, DuPont) according to the mass ratio of 10:2.5:1:500. 0.4 mg of carbon nanotubes and 0.2 g of isopropanol, mixed and ultrasonically dispersed to form a catalyst slurry, sprayed on one side of the proton exchange membrane under infrared light, and then heat treated at 70 ° C for 30 minutes. That is, a cathode catalytic layer was prepared, wherein the loading of Pt was 0.2 mg cm ^-1 ;

In the fifth step, 2.1 mg of Pt/C catalyst (John Matthey) with Pt content of 60%, 17 mg of perfluorosulfonic acid polymer solution (5 wt% Nafion, DuPont) and 0.1 were weighed according to the mass ratio of 10:2.5:500. g Isopropanol, mixed and ultrasonically dispersed into a catalyst slurry, sprayed on the other side of the proton exchange membrane sprayed in the fourth step under infrared light irradiation, and then heat-treated the sprayed proton exchange membrane at 70 °C The anode catalytic layer of the membrane electrode was prepared in 30 minutes, wherein the loading of Pt was 0.1 mg cm ^-1 .

 Step 6 Cut TGP-H-60 carbon paper (Toray) to 2.5 cm × 2.5 cm The small pieces were placed in acetone for 2 hours to remove surface organic impurities. After drying, they were immersed in a 5% by weight polytetrafluoroethylene emulsion for 5 minutes, and dried to make the polytetrafluoroethylene account for the entire carbon. Paper weight 15%, calcined at 500 °C for 1 hour, so that the polytetrafluoroethylene is sintered in carbon paper, that is, the carbon paper is treated with water.

 Step 7 Weigh 30mg XC-72 toner, 132.5 mg by mass ratio of 10:1.7: 500 a polytetrafluoroethylene emulsion (mass fraction of 5%) and 1.6 g of isopropyl alcohol solution, mixed and ultrasonically dispersed to form an ink slurry, which is sprayed onto one side of the hydrophobized carbon paper, Sprayed carbon paper at Baking at 70 ° C for 30 minutes, drying and baking at 350 ° C for 1 hour to obtain a gas diffusion layer;

 Step 8 The two gas diffusion layers sprayed in the seventh step are respectively attached to both sides of the proton exchange membrane sprayed with the anode and cathode catalyst layers in the fifth step, thereby preparing a membrane electrode. (Structure shown in Figure 1)

 The membrane electrode was placed in a single cell, and the activation treatment was carried out under the condition that the battery temperature was 70 ° C and the anode and cathode were completely humidified. Hours, repeated discharge to fully activate, battery performance test conditions are as follows: fuel gas is hydrogen, oxidant is air, battery temperature is 70 °C, anode and cathode back pressure are 30 psi, cathode and anode relative humidity is 100%.

Under the condition of battery temperature of 70 °C and anode-anode relative humidity of 100%, the polarization curve of the battery is shown in Fig. 2a and Fig. 2b. When the voltage is 0.7V and 0.6V, the current density can reach 700mA cm ^-2 respectively.

And 1300 mA cm ^-2 . The maximum power density is 814 mW cm ^-2 .

 Example 2

Except for the carbon-supported platinum catalyst, perfluorosulfonic acid polymer, carbon nitride carbon nanotubes and isopropanol in a mass ratio of 1 0:2.5:2:500, the other steps are the same as in Example 1, the battery activation mode and The test method is exactly the same as in Example 1. The cell polarization curve is shown in Figure 2. At voltages of 0.7V and 0.6V, the current density can reach 700 mA cm ^-2 and 1300 mA cm ^{-2 , respectively} . The maximum power density is 822 mW cm ^-2 .

 Example 3

Except for carbon-supported platinum catalyst, perfluorosulfonic acid polymer, carbon nitride carbon nanotubes and isopropanol in a mass ratio of 10:2.5:3:500, the other steps are the same as in Example 1, battery activation mode and test The method is exactly the same as in Example 1. The cell polarization curve is shown in Figure 2. At voltages of 0.7V and 0.6V, the current density can reach 700 mA cm ^-2 and 1250 mA cm ^{-2 , respectively} . The maximum power density is 780 mW cm ^-2 .

 Comparative Example 1

The first step taken Nafion212 4cm × 4cm proton exchange membrane, is first placed in mass percent concentration of 5% hydrogen peroxide treated 80 ℃ 1 hour, washed with distilled water, under treatment 0.5mol L ^-1 sulfuric acid solution 80 ℃ 1 hour, then rinse with distilled water. The treated Nafion membrane was placed on a fixed frame for preparing the membrane electrode, and the active area was 5 cm ² to prevent the membrane from shrinking and deforming during spraying of the catalyst slurry;

In the second step, 6.4 mg of Pt/C catalyst with a Pt content of 40% (Hispec 4100, Johnson Matthey) and 50 mg of perfluorosulfonic acid polymer solution (5 wt% Nafion, DuPont) were weighed according to the mass ratio of 10:2.5:500. And 0.3g of isopropyl alcohol, mixed and ultrasonically dispersed to form a catalyst slurry, sprayed on one side of the proton exchange membrane under infrared light irradiation, and then heat treated at 70 ° C for 30 minutes to obtain a cathode catalytic layer. The loading of Pt is 0.2mg cm ^-1 ;

The third step is to weigh 3.1 mg Pt/C catalyst (Hispec4100, Johnson Matthey) with a Pt content of 40%, 25 mg perfluorosulfonic acid polymer solution (5wt% Nafion, DuPont) and 10:2.5:500 mass ratio. 0.2g of isopropanol, mixed and ultrasonically dispersed to form a catalyst slurry, sprayed on the other side of the proton exchange membrane sprayed in the second step under infrared light irradiation, and then sprayed the proton exchange membrane at 70 °C The lower end of the heat treatment was carried out for 30 minutes to prepare an anode catalytic layer of the membrane electrode, wherein the loading of Pt was 0.1 mg cm ^-1 .

 Step 4 Cut TGP-H- 60 (Toray) carbon paper to 2.5 cm × 2.5 cm The small pieces were placed in acetone for 2 hours to remove surface organic impurities. After drying, they were immersed in a 5% by weight polytetrafluoroethylene emulsion for 5 minutes, and dried to make the polytetrafluoroethylene account for the entire carbon. Paper weight 15%, calcined at 500 °C for 1 hour, so that the polytetrafluoroethylene is sintered in carbon paper, that is, the water treatment of carbon paper is completed.

 Step 5 Weigh 30mg XC-72 toner, 132.5m g by mass ratio of 10:1.7:500 a polytetrafluoroethylene emulsion (mass fraction of 5%) and 1.6 g of isopropyl alcohol solution, mixed and ultrasonically dispersed to form an ink slurry, which is sprayed onto one side of the hydrophobized carbon paper, Sprayed carbon paper at 70 Baking at °C for 30 minutes, drying and calcining at 350 °C for 1 hour to obtain a gas diffusion layer;

 Step 6 The two gas diffusion layers sprayed in the fifth step were respectively attached to both sides of the proton exchange membrane coated with the anode and cathode catalytic layers in the fifth step, thereby preparing a membrane electrode, which was named as a blank 212 membrane electrode.

The polarization performance was tested under the same test conditions as in Example 1 as shown in Fig. 2a and Fig. 2b. At 70 ° C and 100% relative humidity, the current density was 0.7 V and 0.6 V, respectively. Up to 600 mA cm ^-2 and 1000 mA cm ^-2 . The maximum power density is 691 mW cm ^-2 .

 Comparative Example 2

 Except for the preparation of the cathode electrode layer of the membrane electrode, other preparation, activation and test methods were the same as in Example 1 except that carbon nanotubes were not added. Named blank 211 membrane electrode

The polarization performance was tested under the same test conditions as in Example 1. As shown in Fig. 2, the current density reached 700 mA at voltages of 0.7 V and 0.6 V at 70 ° C and 100% relative humidity, respectively. Cm ^-2 and 1200 mA cm ^-2 . The maximum power density is 781 mW cm ^-2 .

 Example 4

The first step was to take a 4cm×4cm Nafion211 proton exchange membrane, firstly treated in a hydrogen peroxide solution at a concentration of 5% by weight at 80 °C for 1 hour, washed with distilled water, and treated at 0.5 °L in a 0.5 mol L ^-1 sulfuric acid solution. 1 hour, then rinse with distilled water. The treated Nafion membrane was placed on a fixed frame for preparing the membrane electrode, and the active area was 5 cm ² to prevent the membrane from shrinking and deforming during spraying of the catalyst slurry;

 The second step is to soon the carbon nanotubes in a concentrated sulfuric acid / concentrated nitric acid solution at a volume ratio of 3:1 for 30 minutes and reflux at 80 °C. After 8 hours, the carbon nanotubes were filtered and washed with deionized water to neutrality, i.e., acid treated carbon nanotubes were obtained.

 Step 3 Put the second step of acid-treated carbon nanotubes into a quartz tube furnace, adjust the temperature program, and control the flow rate of ammonia to 120 ml / In a minute, calcination at 900 °C for 2 hours, then lowering to room temperature, replacing ammonia gas with nitrogen or argon to remove ammonia in the system, and taking out the sample to obtain carbon nanotubes;

In the fourth step, 4.2 mg of Pt/C catalyst (John Matthey) with Pt content of 60%, 33 mg of perfluorosulfonic acid polymer solution (5 wt% Nafion, DuPont) and 0.2 g were weighed according to the mass ratio of 10:2.5:500. Isopropanol, mixed and ultrasonically dispersed to form a catalyst slurry, sprayed on one side of the proton exchange membrane under infrared light irradiation, and then heat treated at 70 ° C for 30 minutes to prepare a cathode catalytic layer, wherein Pt is loaded. The amount is 0.2mg cm ^-1 ;

In the fifth step, 2.1 mg Pt/C catalyst (John Matthey) with Pt content of 60%, 17 mg perfluorosulfonic acid polymer solution (5 wt% Nafion, DuPont) and 0.1 g were weighed according to the mass ratio of 10:2.5:500. Isopropanol, mixed and ultrasonically dispersed to form a catalyst slurry, sprayed on the other side of the proton exchange membrane sprayed in the fourth step under infrared light irradiation, and then heat-treated the sprayed proton exchange membrane at 70 ° C The anode catalytic layer of the membrane electrode was prepared in 30 minutes, wherein the loading of Pt was 0.1 mg cm ^-1 .

 Step 6 Cut TGP-H-60 (Toray) carbon paper into 2.5 cm × 2.5 cm The small pieces were treated in acetone for 2 hours to remove surface organic impurities, and dried and immersed in a 5%-15% by weight polytetrafluoroethylene emulsion. Minutes, dry, make PTFE account for 15% of the weight of the whole carbon paper, and calcine at 500 °C for 1 hour to sinter the polytetrafluoroethylene in carbon paper, that is, complete the water treatment of carbon paper.

 Step 7 Weigh 30mg XC-72 toner, 132.5 mg by mass ratio of 10:1.7:1:500 PTFE emulsion (5% by mass), 3.8mg carbon nanotubes and 1.6g The isopropyl alcohol solution is mixed and ultrasonically dispersed to form an ink slurry. The slurry is sprayed onto one side of the hydrophobized carbon paper, and the sprayed carbon paper is baked at 70 ° C for 30 minutes, and dried. After 350 °C Blowing for 1 hour to obtain a cathode gas diffusion layer;

 Step 8 Weigh 30mg XC-72 toner and 132.5mg according to the mass ratio of 10:1.7:500. a polytetrafluoroethylene emulsion (mass fraction of 5%) and 1.6 g of isopropyl alcohol solution, mixed and ultrasonically dispersed to form an ink slurry, which is sprayed onto one side of the hydrophobized carbon paper, Sprayed carbon paper at 70 Baking at °C for 30 minutes, drying and calcining at 350 °C for 1 hour to obtain an anode gas diffusion layer;

 Step 9 The gas diffusion layers sprayed by the seventh step and the eighth step are respectively attached to both sides of the proton exchange membrane sprayed with the anode and cathode catalytic layers in the fifth step, thereby preparing a membrane electrode.

The polarization properties were tested under the same test conditions as in Example 1 as shown in Figures 3a and 3b. At voltages of 0.7V and 0.6V, the current densities were 800 mA cm ^-2 and 1300 mA cm ^{-2 , respectively} . The maximum power density is 808 mW cm ^-2 .

 Example 5

Except for XC-72 toner, polytetrafluoroethylene emulsion (mass fraction 5%), carbon nitride carbon nanotubes and isopropyl alcohol in the mass ratio of 10:1.7:2:500, other steps and examples 4 Similarly, the battery activation method and test method are exactly the same as in Example 4. The cell polarization curve is shown in Figure 3. At voltages of 0.7V and 0.6V, the current density can reach 800 mA cm ^-2 and 1300 mA cm ^{-2 , respectively} . The maximum power density is 822 mW cm ^-2 .

 Example 6

Except for XC-72 toner, polytetrafluoroethylene emulsion (mass fraction 5%), carbon nitride carbon nanotubes and isopropanol in the mass ratio of 10:1.7:3:500, other steps and examples 4 Similarly, the battery activation method and test method are exactly the same as in Example 4. The cell polarization curve is shown in Figure 3. At voltages of 0.7V and 0.6V, the current density can reach 800 mA cm ^-2 and 1200 mA cm ^{-2 , respectively} . The maximum power density is 730 mW cm ^-2 .

 Example 7

The first step is to take a 4cm × 4cm Nafion211 proton exchange membrane, firstly treated at 80 °C in 5% by mass of hydrogen peroxide for 1 hour, washed with distilled water, and treated at 0.5 °L ^-1 in sulfuric acid solution at 80 °C. 1 hour, then rinse with distilled water. The treated Nafion membrane was placed on a fixed frame for preparing the membrane electrode, and the active area was 5 cm ² to prevent the membrane from shrinking and deforming during spraying of the catalyst slurry;

 The second step is to soon the carbon nanotubes in a concentrated sulfuric acid / concentrated nitric acid solution at a volume ratio of 3:1 for 30 minutes at 80 °C. After refluxing for 8 hours, the carbon nanotubes were filtered and washed with deionized water to neutrality to obtain acid-treated carbon nanotubes.

 Step 3 Put the second step of acid-treated carbon nanotubes into a quartz tube furnace, adjust the temperature program, and control the flow rate of ammonia to 120 ml / In a minute, calcination at 900 °C for 2 hours, then lowering to room temperature, replacing ammonia gas with nitrogen or argon to remove ammonia in the system, and taking out the sample to obtain carbon nanotubes;

The fourth step is to weigh 4.2 mg Pt/C catalyst (John Matthey) with Pt content of 60%, 33 mg perfluorosulfonic acid polymer solution (5 wt% Nafion, DuPont), according to the mass ratio of 10:2.5:2:500. 0.8 mg of carbon nanotubes and 0.2g of isopropanol, mixed and ultrasonically dispersed to form a catalyst slurry, sprayed on one side of the proton exchange membrane under infrared light, and then heat treated at 70 ° C for 30 minutes, ie A cathode catalytic layer was prepared, wherein the loading of Pt was 0.2 mg cm ^-1 ;

In the fifth step, 2.1 mg Pt/C catalyst (John Matthey) with Pt content of 60%, 17 mg perfluorosulfonic acid polymer solution (5 wt% Nafion, DuPont) and 0.1 g were weighed according to the mass ratio of 10:2.5:500. Isopropanol, mixed and ultrasonically dispersed to form a catalyst slurry, sprayed on the other side of the proton exchange membrane completed in the fourth step under infrared light irradiation, and then heat-treated the sprayed proton exchange membrane at 70 ° C. In minutes, an anode catalytic layer of the membrane electrode was prepared, in which the loading of Pt was 0.1 mg cm ^-1 .

 Step 6 Cut TGP-H-60 (Toray) carbon paper into 2.5 cm × 2.5 cm The small pieces were placed in acetone for 2 hours to remove surface organic impurities, dried and soaked in a 5%-15% by weight polytetrafluoroethylene emulsion for 5 minutes, and dried. Polytetrafluoroethylene accounts for 15% of the weight of the whole carbon paper, and is calcined at 500 °C for 1 hour to sinter the polytetrafluoroethylene in carbon paper to complete the water treatment of the carbon paper.

 Step 7 Weigh 30mg XC-72 toner, 132.5 mg by mass ratio of 10:1.7:2:500 PTFE emulsion (5% by mass), 7.5mg carbon nanotubes and 1.6g The isopropyl alcohol solution is mixed and ultrasonically dispersed to form an ink slurry. The slurry is sprayed onto one side of the hydrophobized carbon paper, and the sprayed carbon paper is baked at 70 ° C for 30 minutes, and dried. After 350 °C Blowing for 1 hour to obtain a cathode gas diffusion layer;

 Step 8 Weigh 30mg XC-72 toner, 132.5 mg by mass ratio of 10:1.7:500 a polytetrafluoroethylene emulsion (mass fraction of 5%) and 1.6 g of isopropyl alcohol solution, mixed and ultrasonically dispersed to form an ink slurry, which is sprayed onto one side of the hydrophobized carbon paper, Sprayed carbon paper at 70 Baking at °C for 30 minutes, drying and calcining at 350 °C for 1 hour to obtain an anode gas diffusion layer;

 Step 9 The gas diffusion layers sprayed by the seventh step and the eighth step are respectively attached to both sides of the proton exchange membrane sprayed with the anode and cathode catalytic layers in the fifth step, thereby preparing a membrane electrode.

The polarization properties were tested under the same test conditions as in Example 1 as shown in Fig. 4a and Fig. 4b. At 70 °C and 100% relative humidity, the current densities were respectively at voltages of 0.7 V and 0.6 V. Up to 1000 mA cm ^-2 and 1600 mA cm ^-2 . The maximum power density is 997 mW cm ^-2 .

 Example 8

 The membrane electrode preparation step and the membrane electrode test step are the same as the embodiment except that the untreated carbon nanotube is used instead of the nitrided carbon nanotube in the embodiment 7. 7 . The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention.

Under the same test conditions as in Example 7, the current densities were 700 mA cm ^-2 and 1300 mA cm ^-2 at voltages of 0.7 V and 0.6 V, respectively. The maximum power density is 872 mW cm ^-2 .

 Example 9

 The membrane electrode preparation step and the membrane electrode test step are the same as the embodiment except that the carbon nanotubes in the embodiment 7 are replaced by the acid-treated carbon nanotubes. 7 . The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention.

Under the same test conditions as in Example 7, the current densities were 800 mA cm ^-2 and 1300 mA cm ^-2 at voltages of 0.7 V and 0.6 V, respectively. The maximum power density is 872 mW cm ^-2 .

 Example 10

 The membrane electrode preparation step and the membrane electrode test procedure are the same as in the embodiment 7 except that the carbon nitride carbon nanotubes in Example 7 are replaced by carbon nitride fibers. . The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention.

Under the same test conditions as in Example 7, the current densities were 900 mA cm ^-2 and 1500 mA cm ^-2 at voltages of 0.7 V and 0.6 V, respectively. The maximum power density is 926 mW cm ^-2 .

The above-described embodiments of the present invention are merely illustrative of the present invention and are not intended to limit the embodiments of the present invention. Other variations or modifications of the various forms may be made by those skilled in the art in light of the above description. There is no need and no way to exhaust all of the implementations. Any modifications, equivalent substitutions and improvements made within the spirit and scope of the invention are intended to be included within the scope of the appended claims.

Claims (10)

1. A method for preparing a high power density proton exchange membrane fuel cell membrane electrode, comprising the steps of:

   ( 1 The proton exchange membrane is sequentially oxidized and acidified with hydrogen peroxide and sulfuric acid, and then stored in deionized water for storage. When used, the proton exchange membrane is taken out, the surface moisture is absorbed, and it is fixed in a special tool for coating. An anode and a cathode catalytic layer; the proton exchange membrane is a polymer solid electrolyte having different thicknesses;

   (2) pretreating carbon nanotubes or carbon fibers;

   (3) A carbon-supported platinum catalyst or an alloy catalyst of platinum with other metals, a perfluorosulfonic acid polymer, pretreated carbon nanotubes or carbon fibers, and a volatile solvent are 10:2-5:0-5:200 After the mass ratio of -2000 is mixed, the ink-like slurry is prepared by ultrasonic dispersion treatment after 0.5-2 hours, and then the ink-like slurry is coated on one side of the proton exchange membrane by spraying or brushing, Pt loading The amount is controlled between 0.1-1 mg cm ^-2 , and then the proton exchange membrane coated with the catalytic layer is heat-treated at 50-80 ° C for 20-60 minutes to prepare a cathode catalytic layer containing carbon nanotubes;

   (4) Mixing the carbon-supported platinum catalyst or platinum with other metal alloy catalysts, perfluorosulfonic acid polymer and volatile solvent in a mass ratio of 10:2-5:200-2000, after 0.5-2 hours of ultrasonication After being oscillated, it is dispersed into an ink-like slurry, and the slurry is sprayed on the other side of the proton exchange membrane after the step (3), and the loading of Pt is controlled to be between 0.05 and 0.4 mg cm ^-2 , and then sprayed. A good proton exchange membrane is baked at 50-80 ° C for 20-60 minutes to prepare an anode catalytic layer of the membrane electrode;

   Completely coating an anode catalytic layer and a cathode catalytic layer on both sides of the proton exchange membrane to obtain a three-in-one membrane electrode;

   (5) subjecting the carbon paper to hydrophobic treatment;

   (6) Mixing XC-72 toner, polytetrafluoroethylene emulsion, carbon nanotube or carbon fiber and volatile solvent in a mass ratio of 10:1-4:0-5: 200-2000, ultrasonic dispersion 30-80 Minutes, made into an ink-like slurry, which is applied to one side of the hydrophobized carbon paper by spraying and brushing process. The loading capacity of carbon powder, carbon nanotube or carbon fiber is controlled at 2.4-3.4 mg. Cm ^-2 , baking the sprayed carbon paper at 50-80 ° C for 20-60 minutes, drying and then calcining at 340-430 ° C for 0.5-2 hours to obtain a cathode gas diffusion layer; the polytetrafluoroethylene The mass percentage concentration of the emulsion is 10-25 wt%;

   (7) Mixing XC-72 toner, polytetrafluoroethylene emulsion and volatile solvent in a mass ratio of 10:1-4: 200-2000, ultrasonic dispersion The ink-like slurry is prepared in 30-80 minutes, and the slurry is applied to one side of the hydrophobized carbon paper by spraying or brushing, and the sprayed carbon paper is baked at 50-80 ° C. 20-60 After drying, it is calcined at 340-430 ° C for 0.5-2 hours to obtain an anode gas diffusion layer; the concentration concentration of the polytetrafluoroethylene emulsion is 10-25 wt%. ;

   (8) affixing the two gas diffusion layers after the treatments of (6) and (7) to the respective sides of the three-in-one membrane electrode obtained by the step (4), 110-150 degrees hot pressing for 3-5 minutes, and then edge-sealing; that is, a cathode-catalyst layer or a gas diffusion layer containing carbon nanotubes of a five-in-one film electrode.
2. The method for preparing a high power density proton exchange membrane fuel cell membrane electrode according to claim 1, wherein said proton exchange membrane has a thickness of 20 to 50, respectively. Micron hydrogen proton exchange membrane.
3. The method for preparing a high power density proton exchange membrane fuel cell membrane electrode according to claim 1, wherein a catalyst having a high platinum content is used, and the catalyst has a Pt content of 20%. - 60% Pt/C or PtM/C catalyst, where M is Ru, Pd or Au.
4. The method for preparing a high power density proton exchange membrane fuel cell membrane electrode according to claim 1, wherein the perfluorosulfonic acid polymer is added in the form of a perfluorosulfonic acid polymer solution, the perfluoro The sulfonic acid polymer solution is a Nafion solution having a 2-5% by mass concentration.
5. The method for producing a high power density proton exchange membrane fuel cell membrane electrode according to claim 1, wherein the volatile solvent is one or more selected from the group consisting of distilled water, ethanol, and isopropyl alcohol.
6. The method for preparing a high power density proton exchange membrane fuel cell membrane electrode according to claim 1, wherein in the step (2), the pretreatment of the carbon nanotube or the carbon fiber comprises an acid treatment or a nitridation treatment, and an acid treatment And nitriding treatment;

   The acid treatment or nitridation treatment steps are as follows:

   The carbon nano or carbon fiber tube is ultrasonically treated in a concentrated sulfuric acid/concentrated nitric acid solution having a volume ratio of 2.5-3:1 for 20-30 minutes, refluxed at 60-90 ° C for 6-12 hours, filtered and washed with deionized water. Or carbon fiber to neutral, that is, to obtain acid treated carbon nanotubes or carbon fibers;

   Put carbon nanotubes or carbon fibers into a quartz tube furnace, adjust the temperature program, and control the flow rate of ammonia to 60-150 ml / In a minute, calcination at 700-900 ° C for 0.5-3 hours, then down to room temperature, ammonia gas is replaced by nitrogen or argon to remove ammonia in the system, and the sample is taken out to obtain carbon nanotubes;

   The acid treatment and nitridation treatment steps are as follows:

   The carbon nano or carbon fiber tube is ultrasonically treated in a concentrated sulfuric acid/concentrated nitric acid solution having a volume ratio of 2.5-3:1 for 20-30 minutes, refluxed at 60-90 ° C for 6-12 hours, filtered and washed with deionized water. Or carbon fiber to neutral, that is, acid treated carbon nanotubes or carbon fibers.

   The acid-treated carbon nanotubes or carbon fibers are placed in a quartz tube furnace, and the temperature program is adjusted to control the flow rate of the ammonia gas to 60-150 ml/ In a minute, it is calcined at 700-900 ° C for 0.5-3 hours, then lowered to room temperature, and the ammonia gas is replaced with nitrogen or argon to remove ammonia gas in the system, and the sample is taken out to obtain carbon nanotubes.
7. The method for preparing a high power density proton exchange membrane fuel cell membrane electrode according to claim 1, wherein carbon nanotubes or carbon fibers are added to the catalyst layer and the gas diffusion layer, and the carbon nanotubes or carbon nanofibers are added. For untreated carbon nanotubes or carbon fibers, acid-treated carbon nanotubes or carbon fibers and nitrided carbon nanotubes or carbon fibers, the amount added is the total mass of the catalytic layer or gas diffusion layer. - 50%.
8. The method for preparing a high power density proton exchange membrane fuel cell membrane electrode according to claim 1, wherein the specific process of the step (1) is: placing the proton exchange membrane at a mass concentration of 5%-15 % of hydrogen peroxide, boiled at 60-100 ° C for 0.5-2 hours, washed with distilled water, and then placed in 0. 5-1mol L ^-1 sulfuric acid solution, boiled at 60-100 ° C for 0.5-2 hours, It is then washed with distilled water to complete the pretreatment.
9. The method for preparing a high power density proton exchange membrane fuel cell membrane electrode according to claim 1, wherein in the step (5), the specific process is: TGP-H-60 Carbon paper is treated in acetone 0.5-2 After hours, to remove surface organic impurities, after drying, soak for 2-15 minutes in a 5%-15% by weight polytetrafluoroethylene emulsion, and dry, PTFE accounts for 10% of the weight of the whole carbon paper - 25% at 300 - The mixture is calcined at 500 ° C for 0.5 - 2 hours to sinter the polytetrafluoroethylene in carbon paper, that is, the hydrophobic treatment of the carbon paper is completed.
10. A high power density proton exchange membrane fuel cell membrane electrode is prepared by the preparation method according to any one of claims 1 to 9.