Composite free radical quencher, membrane electrode, preparation method of membrane electrode and fuel cell

Abstract

The invention provides a composite free radical quencher, a membrane electrode, a preparation method of the membrane electrode and a fuel cell, and belongs to the technical field of fuel cells. The composite free radical quencher comprises an active substance and perfluorinated sulfonic acid resin powder coating the active substance, and the active substance is at least one of nano-scale cerium oxide, cerium phosphate, cerium sulfide and cerium fluoride. The composite free radical quencher can realize water retention, wetting and proton conduction increase under low electric density. In addition, the composite free radical quencher can improve the durability of a membrane electrode, so that the design of a proton exchange membrane is simplified.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells, and in particular relates to a composite free radical quencher, a membrane electrode and a preparation method thereof, and a fuel cell. Background Art

[0002] Hydrogen-oxygen fuel cells are power generation devices that convert the chemical energy of hydrogen and oxygen as fuel and oxidant, respectively, into electrical energy. They have high energy conversion efficiency, fast startup, and green products. They are gradually gaining international attention and commercialization, and are used in fuel cell vehicles, heavy trucks, drones, and fixed power stations. Among them, the membrane electrode (CCM) plays a vital role in the cost and performance of proton membrane fuel cells. The membrane electrode is a key component of proton exchange membrane fuel cells. It is a three-in-one structure consisting of an anode catalyst layer, a proton exchange membrane, and a cathode catalyst layer.

[0003] In fuel cell vehicles, heavy trucks and commercial vehicles can be equipped with humidification tanks to ensure the activity of the membrane electrode in medium and high humidification conditions. However, in passenger cars, due to mass and volume limitations, it is necessary to ensure the performance of the membrane electrode at low current density under low or no humidification conditions. In addition, the durability of the membrane electrode assembly (MEA) is one of the key factors for commercialization. Highly durable membrane electrodes can reduce the costs caused by frequent replacement or maintenance, which directly affects the overall performance and reliability of the fuel cell system. The structural layering or gradient design of the cathode anode catalyst layer and the anode catalyst layer of the membrane electrode can optimize the proton conduction, drainage and gas conduction capabilities in the catalyst layer, and can improve the performance and durability of the membrane electrode. Therefore, the development of self-humidification, long-durability, high-performance membrane electrodes is a thorny issue in the fuel cell industry. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the embodiments of the present invention provide a composite free radical quencher, a membrane electrode and a preparation method thereof, and a fuel cell.

[0005] In a first aspect, an embodiment of the present invention provides a composite free radical quencher, comprising an active substance and a perfluorosulfonic acid resin powder coating the active substance, wherein the active substance is at least one of nano-scale cerium oxide, cerium phosphate, cerium sulfide and cerium fluoride.

[0006] The advantages and technical effects brought by the composite free radical quencher of the embodiment of the present invention are:

[0007] (1) The active substances have the function of quenching free radicals, which can reduce the free radicals attacking or corroding the proton exchange membrane and increase the life of the membrane electrode.

[0008] (2) Perfluorosulfonic acid resin is a proton conductor and can conduct protons to the cathode side in a fuel cell.

[0009] (3) The active substance and the perfluorosulfonic acid resin powder are not simply mixed, but the perfluorosulfonic acid resin powder covers the active substance, that is, the active substance is introduced between the chains of the perfluorosulfonic acid resin. Therefore, the active substance is more stable and the two are mixed more evenly.

[0010] (4) Adding a composite free radical quencher to the cathode oxide layer can slow down the loss of water from the membrane electrode, while preventing the generated free radicals from attacking or corroding the proton exchange membrane, thereby increasing the life of the membrane electrode. Adding a composite free radical quencher to the anode oxide layer can improve proton conduction and reduce free radical attack or corrosion, thereby improving the performance and durability of the membrane electrode.

[0011] In some embodiments, based on 100 wt % of the total mass of the composite free radical quencher, the content of the active substance is 5-20 wt %.

[0012] In a second aspect, an embodiment of the present invention provides a method for preparing a composite free radical quencher, comprising the following steps:

[0013] S1. dispersing the active substance in ethanol to form a suspension, and then mixing the suspension with the perfluorosulfonic acid resin powder to obtain a mixture;

[0014] S2. The mixture is placed in a high temperature autoclave, hydrothermally heated at 200-300 ° C for 4-10h, and after the reaction is completed, the mixture is naturally cooled at room temperature to obtain a mixed solution;

[0015] S3. Performing solid-liquid separation on the mixed liquid to obtain a solid substance, then recrystallizing and purifying the solid substance in ethanol, and drying to obtain the composite free radical quencher of the first aspect.

[0016] The advantages and technical effects brought by the preparation method of the composite free radical quencher of the embodiment of the present invention are:

[0017] Step S1 is to mix the active substance and the perfluorosulfonic acid resin powder in two steps so that both can be evenly mixed in ethanol. Step S2 is to hydroheat at 200-300°C for 4-10h. On the one hand, it is to allow ethanol to dissolve the active substance and the perfluorosulfonic acid resin powder. On the other hand, more importantly, the perfluorosulfonic acid resin is a chain polymer that is easy to dissociate and polymerize under high temperature and high pressure. The active substance will be introduced between the chains of the perfluorosulfonic acid resin, making the active substance more stable and the two mixed more evenly.

[0018] In a third aspect, an embodiment of the present invention provides a membrane electrode, comprising an anode catalyst layer, a proton exchange membrane and a cathode catalyst layer, wherein the cathode catalyst layer and / or the anode catalyst layer contains the composite free radical quencher of the first aspect.

[0019] The advantages and technical effects brought by the membrane electrode of the embodiment of the present invention are as follows:

[0020] Adding a composite free radical quencher to the cathode oxide layer can slow down the loss of water from the membrane electrode, while preventing the generated free radicals from attacking or corroding the proton exchange membrane, thereby increasing the life of the membrane electrode. Adding a composite free radical quencher to the anode oxide layer can improve proton conduction and reduce free radical attack or corrosion, thereby improving the performance and durability of the membrane electrode.

[0021] In some embodiments, the loading amount of the composite free radical quencher in the cathode catalyst layer is 6.7-33.3 μg / cm 2 , and / or, the loading amount of the composite free radical quencher in the anode catalyst layer is 1.0-4.7 μg / cm 2 .

[0022] In some embodiments, the cathode catalytic layer includes a first cathode catalytic layer close to the proton exchange membrane and a second cathode catalytic layer away from the proton exchange membrane, the anode catalytic layer includes a first anode catalytic layer close to the proton exchange membrane and a second anode catalytic layer away from the proton exchange membrane, and the cathode first catalytic layer and / or the anode first catalytic layer contain the composite free radical quencher of the first aspect.

[0023] In some embodiments, the IC ratio of the first cathode catalytic layer is higher than the IC ratio of the second cathode catalytic layer, and the EW value of the resin of the first cathode catalytic layer is lower than the EW value of the resin of the second cathode catalytic layer; and / or, the IC ratio of the first anode catalytic layer is higher than the IC ratio of the second anode catalytic layer, and the EW value of the resin of the first anode catalytic layer is lower than the EW value of the resin of the second anode catalytic layer.

[0024] In some embodiments, the anode second catalytic layer contains a platinum-based catalyst and an iridium-based catalyst.

[0025] In a fourth aspect, an embodiment of the present invention provides a method for preparing a membrane electrode, comprising the following steps:

[0026] (1) mixing a platinum-based catalyst, the composite free radical quencher or resin, water and an organic solvent to obtain a cathode catalyst layer slurry, and then coating the cathode catalyst layer slurry on a first transfer substrate to form the cathode catalyst layer, thereby obtaining a first transfer substrate with a cathode catalyst layer;

[0027] (2) mixing a platinum-based catalyst, the composite free radical quencher or resin, water and an organic solvent to obtain an anode catalyst layer slurry, and then coating the anode catalyst layer slurry on a second transfer substrate to form the anode catalyst layer, thereby obtaining a second transfer substrate with an anode catalyst layer;

[0028] (3) The first transfer substrate with the cathode catalyst layer, the second transfer substrate with the anode catalyst layer, and the proton exchange membrane are hot-pressed on a hot press so that the cathode catalyst layer is transferred to one side of the proton exchange membrane and the anode catalyst layer is transferred to the other side of the proton exchange membrane. The first transfer substrate and the second transfer substrate are then removed to obtain the membrane electrode of the third aspect.

[0029] The advantages and technical effects brought by the method for preparing the membrane electrode of the embodiment of the present invention are:

[0030] The preparation method of the membrane electrode of the embodiment of the present invention can obtain a long-lasting proton exchange membrane fuel cell membrane electrode, and the preparation method is suitable for industrial production scale-up.

[0031] In some embodiments, step (1) includes the following steps: mixing a platinum-based catalyst, the composite free radical quencher, water and an organic solvent to obtain a cathode first catalytic layer slurry, mixing a platinum-based catalyst, water, an organic solvent and a resin to obtain a cathode second catalytic layer slurry, and then coating the cathode second catalytic layer slurry on a first transfer substrate to form the cathode second catalytic layer, and then coating the cathode first catalytic layer slurry on the cathode second catalytic layer to form the cathode first catalytic layer, thereby obtaining a first transfer substrate with a cathode catalytic layer;

[0032] And / or, step (2) includes the following steps: mixing a platinum-based catalyst, the composite free radical quencher, water and an organic solvent to obtain an anode first catalytic layer slurry, mixing a platinum-based catalyst, water, an organic solvent and a resin to obtain an anode second catalytic layer slurry, and then coating the anode second catalytic layer slurry on a second transfer substrate to form the anode second catalytic layer, and then coating the anode first catalytic layer slurry on the anode second catalytic layer to form the anode first catalytic layer, thereby obtaining a second transfer substrate with an anode catalytic layer.

[0033] In some embodiments, in step (2), a platinum-based catalyst, an iridium-based catalyst, water, an organic solvent and a resin are mixed to obtain the anode second catalyst layer slurry.

[0034] In a fifth aspect, an embodiment of the present invention provides a fuel cell comprising the membrane electrode according to the third aspect.

[0035] The advantages and technical effects of the fuel cell of the embodiment of the present invention are as follows:

[0036] Due to the use of the membrane electrode of the third aspect, the fuel cell of the embodiment of the present invention has the characteristics of self-humidification, high performance and long durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The performance comparison curves of the membrane electrodes of Example 1 and Examples 1B-1F;

[0038] Figure 2 The performance comparison curve of the membrane electrode of Examples 1-3 and Comparative Example 1;

[0039] Figure 3 This is a cross-sectional line scan of the cathode catalyst layer of Example 1. DETAILED DESCRIPTION

[0040] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0041] The present invention aims to solve the problems of low membrane electrode performance caused by large proton transmission resistance at low electric density, easy flooding at high electric density, and low membrane electrode life caused by variable load start-stop, etc. of automotive proton membrane fuel cells. Water is crucial to the performance of membrane electrodes because it is the key to proton conduction of perfluorosulfonic acid polymer membranes and perfluorosulfonic acid resin binders. When operating at low electric density, the water content is low, and the conductivity of hydrogen protons will be reduced or even fail. Especially in an environment with humidity below 20%, the membrane electrode is prone to water loss, which will significantly affect its performance. When operating at high electric density, the water inside the stack mainly comes from the water generated by the electrochemical reaction on the cathode side. When the speed of water generation exceeds the speed of discharge, flooding may occur. Flooding will cause the gas diffusion layer and the flow channel to be covered with liquid water, thereby hindering the transmission of oxygen to the reaction site, and the mass transfer capacity will deteriorate. In severe cases, it may even cause local swelling of the membrane, causing damage to the membrane, thereby affecting the battery performance and life.

[0042] In a first aspect, an embodiment of the present invention provides a composite free radical quencher, comprising an active substance and a perfluorosulfonic acid resin powder coating the active substance, wherein the active substance is at least one of nano-scale cerium oxide, cerium phosphate, cerium sulfide and cerium fluoride.

[0043] Active substances have the effect of quenching free radicals, which can reduce free radical attacks or corrosion of proton exchange membranes and increase the life of membrane electrodes. Perfluorosulfonic acid resin is a proton conductor, which can conduct protons to the cathode side in fuel cells. In addition, the active substance and perfluorosulfonic acid resin powder are not simply mixed, but the active substance is coated with perfluorosulfonic acid resin powder, that is, the active substance is introduced between the chains of perfluorosulfonic acid resin, so the active substance is more stable and the two are mixed more evenly. Therefore, after adding a composite free radical quencher to the cathode oxide layer, the loss of water from the membrane electrode can be slowed down, and the generated free radicals can be prevented from attacking or corroding the proton exchange membrane, thereby increasing the life of the membrane electrode. After adding a composite free radical quencher to the anode oxide layer, proton conduction can be improved and free radical attacks or corrosion can be reduced, thereby improving the performance and durability of the membrane electrode.

[0044] In some embodiments, the total mass of the composite free radical quencher is 100wt%, and the content of the active substance is 5-20wt%, such as 5wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt%, 20wt%, etc. When the content of the active substance is too low, the free radicals will attack or corrode the proton exchange membrane. When the content of the active substance is too high, the impedance of the battery will increase, resulting in a decrease in membrane electrode performance.

[0045] In a second aspect, an embodiment of the present invention provides a method for preparing a composite free radical quencher, comprising the following steps:

[0046] S1. dispersing the active substance in ethanol to form a suspension, and then mixing the suspension with the perfluorosulfonic acid resin powder to obtain a mixture;

[0047] S2. The mixture is placed in a high temperature autoclave, hydrothermally heated at 200-300 ° C for 4-10h, and after the reaction is completed, the mixture is naturally cooled at room temperature to obtain a mixed solution;

[0048] S3. Performing solid-liquid separation on the mixed liquid to obtain a solid substance, then recrystallizing and purifying the solid substance in ethanol, and drying to obtain the composite free radical quencher of the first aspect.

[0049] Step S1 is divided into two steps to mix the active substance and the perfluorosulfonic acid resin powder, so that both can be uniformly mixed in ethanol. Step S2 is hydrothermal at 200-300 ° C for 4-10 hours. On the one hand, it is to make ethanol dissolve the active substance and the perfluorosulfonic acid resin powder. On the other hand, more importantly, the perfluorosulfonic acid resin is a chain polymer, which is easy to dissociate and polymerize under high temperature and high pressure. The active substance will be introduced between the chains of the perfluorosulfonic acid resin, and the active substance is more stable, and the two are mixed more evenly. It should be understood that no chemical reaction occurs in step S2, and the active substance and the perfluorosulfonic acid resin powder are in a mixed relationship, but it is not a simple mixed relationship similar to stirring, ball milling, etc. Finally, after the treatment of step S3, a composite free radical quencher with higher purity is obtained.

[0050] In a third aspect, an embodiment of the present invention provides a membrane electrode, comprising an anode catalyst layer, a proton exchange membrane and a cathode catalyst layer, wherein the cathode catalyst layer and / or the anode catalyst layer contains the composite free radical quencher of the first aspect.

[0051] Adding a composite free radical quencher to the cathode oxide layer can slow down the loss of water from the membrane electrode, while preventing the generated free radicals from attacking or corroding the proton exchange membrane, thereby increasing the life of the membrane electrode. Adding a composite free radical quencher to the anode oxide layer can improve proton conduction and reduce free radical attack or corrosion, thereby improving the performance and durability of the membrane electrode.

[0052] In some embodiments, the loading amount of the composite free radical quencher in the cathode catalyst layer is 6.7-33.3 μg / cm 2 , and / or, the loading amount of the composite free radical quencher in the anode catalyst layer is 1-4.7 μg / cm 2 . The loading amount of the composite free radical quencher in the cathode catalyst layer and / or the anode catalyst layer is within the above range, which can effectively improve proton conduction and reduce free radical attack or corrosion, thereby improving the performance and durability of the membrane electrode. When the loading amount of the composite free radical quencher in the cathode catalyst layer and / or the anode catalyst layer is too low, the free radicals will attack or corrode the proton exchange membrane. When the content of the composite free radical quencher is too high, it will increase the impedance of the battery, which is not conducive to improving the performance of the membrane electrode.

[0053] In some embodiments, the cathode catalyst layer includes a cathode first catalyst layer close to the proton exchange membrane and a cathode second catalyst layer away from the proton exchange membrane, the anode catalyst layer includes an anode first catalyst layer close to the proton exchange membrane and an anode second catalyst layer away from the proton exchange membrane, and the cathode first catalyst layer and / or the anode first catalyst layer contain the composite free radical quencher of the first aspect. Adding a composite free radical quencher to the cathode first catalyst layer and / or the anode first catalyst layer can prevent the generated free radicals from attacking or corroding the proton exchange membrane, simplifying the design of a durable proton exchange membrane, thereby achieving high-performance output and industrial application of proton exchange membrane fuel cells. Specifically, the membrane electrode described above is a self-humidifying, high-performance and long-durable proton exchange membrane fuel cell membrane electrode structure that can be applied to industrial production and scale-up.

[0054] Under the premise of using the same loading of free radical quencher, compared with adding the composite free radical quencher in the entire cathode / anode catalyst layer, when the composite free radical quencher is introduced into the first cathode / anode catalyst layer, the bulk density of free radicals is higher, and the quencher close to the proton membrane can react with the free radicals faster, which can improve the durability of the membrane electrode.

[0055] In some embodiments, the IC ratio of the first cathode catalytic layer is higher than the IC ratio of the second cathode catalytic layer, and the EW value of the resin of the first cathode catalytic layer is lower than the EW value of the resin of the second cathode catalytic layer; and / or, the IC ratio of the first anode catalytic layer is higher than the IC ratio of the second anode catalytic layer, and the EW value of the resin of the first anode catalytic layer is lower than the EW value of the resin of the second anode catalytic layer. It should be understood that the IC ratio is the ratio between the solid mass of the resin and the mass of the carbon. The EW value is the ion exchange equivalent of the resin, that is, the mass of polymer required to provide 1 mol of exchangeable protons, and the unit is g / mol.

[0056] By constructing a double-layer catalyst layer in the cathode catalyst layer and designing the double-layer catalyst layer as above, it is possible to achieve low electric density water retention and humidification to improve proton conduction, and high electric density water drainage to prevent water flooding of the membrane electrode, thereby improving the performance of the membrane electrode. By constructing a double-layer catalyst layer in the anode catalyst layer and designing the double-layer catalyst layer as above, it is possible to drain the water from the cathode reverse permeation and reduce the corrosion of the bipolar plate.

[0057] In some embodiments, the second catalyst layer of the anode contains a platinum-based catalyst and an iridium-based catalyst. Adding the iridium-based catalyst to the second catalyst layer of the anode can enable iridium to catalyze water decomposition to produce protons faster, increase the membrane electrode's anti-reverse polarity time, reduce performance degradation after reverse polarity, and improve the durability of the membrane electrode when fuel is insufficient.

[0058] In a fourth aspect, an embodiment of the present invention provides a method for preparing a membrane electrode, comprising the following steps:

[0059] (1) mixing a platinum-based catalyst, the composite free radical quencher or resin, water and an organic solvent to obtain a cathode catalyst layer slurry, and then coating the cathode catalyst layer slurry on a first transfer substrate to form the cathode catalyst layer, thereby obtaining a first transfer substrate with a cathode catalyst layer;

[0060] (2) mixing a platinum-based catalyst, the composite free radical quencher or resin, water and an organic solvent to obtain an anode catalyst layer slurry, and then coating the anode catalyst layer slurry on a second transfer substrate to form the anode catalyst layer, thereby obtaining a second transfer substrate with an anode catalyst layer;

[0061] (3) The first transfer substrate with the cathode catalyst layer, the second transfer substrate with the anode catalyst layer, and the proton exchange membrane are hot-pressed on a hot press so that the cathode catalyst layer is transferred to one side of the proton exchange membrane and the anode catalyst layer is transferred to the other side of the proton exchange membrane. The first transfer substrate and the second transfer substrate are then removed to obtain the membrane electrode of the third aspect.

[0062] The preparation method of the membrane electrode of the embodiment of the present invention can obtain a long-lasting proton exchange membrane fuel cell membrane electrode, and the preparation method is suitable for industrial production scale-up.

[0063] In some embodiments, step (1) includes the following steps: mixing a platinum-based catalyst, the composite free radical quencher, water and an organic solvent to obtain a cathode first catalytic layer slurry, mixing a platinum-based catalyst, water, an organic solvent and a resin to obtain a cathode second catalytic layer slurry, and then coating the cathode second catalytic layer slurry on a first transfer substrate to form the cathode second catalytic layer, and then coating the cathode first catalytic layer slurry on the cathode second catalytic layer to form the cathode first catalytic layer, thereby obtaining a first transfer substrate with a cathode catalytic layer;

[0064] And / or, step (2) includes the following steps: mixing a platinum-based catalyst, the composite free radical quencher, water and an organic solvent to obtain an anode first catalytic layer slurry, mixing a platinum-based catalyst, water, an organic solvent and a resin to obtain an anode second catalytic layer slurry, and then coating the anode second catalytic layer slurry on a second transfer substrate to form the anode second catalytic layer, and then coating the anode first catalytic layer slurry on the anode second catalytic layer to form the anode first catalytic layer, thereby obtaining a second transfer substrate with an anode catalytic layer.

[0065] The above-mentioned preparation method can obtain a proton exchange membrane fuel cell membrane electrode with self-humidification, high performance and long durability, and the preparation method is suitable for industrial production scale-up.

[0066] In some embodiments, in step (2), a platinum-based catalyst, an iridium-based catalyst, water, an organic solvent and a resin are mixed to obtain the anode second catalyst layer slurry.

[0067] Typically, the method for preparing the membrane electrode may include the following steps:

[0068] Prepare the cathode second catalyst layer slurry: 1. Weigh 2-3g Pt / C catalyst on an analytical balance, put it into a ball mill, add 3-10g deionized water to fully wet the catalyst, stir evenly and let it stand; 2. Add 20-40g n-propanol in sequence, add 0.45-2g resin (EW value can be 900-1100g / mol) to the slurry, ZrO 2 The particles are 150-250g. After the ball mill is sealed, put them into a ball mill for ball milling at a speed of 450r / min for 8-12h. Finally, stop the machine and take out the ball mill. First, filter out the ball mill beads and then remove bubbles in vacuum. Finally, stir at 300r / min for 20-30min. Use a dropper to take out a small amount of slurry and place it on a clean PTFE film. Place a suitable coating rod on the automatic coating instrument to automatically complete the coating of catalytic layers of different thicknesses. The coated catalytic layer is placed in a vacuum drying oven. After drying at 80℃ for 5-8h in a vacuum atmosphere, take it out and place it in a constant temperature and humidity chamber for use.

[0069] Prepare the first catalytic layer slurry of the cathode: 1. Weigh 2-3g of Pt / C catalyst on an analytical balance, put it into a ball mill, add 3-10g of deionized water to fully wet the catalyst, stir evenly and let it stand; 2. Add 20-40g of n-propanol in sequence, add 0.5-2.5g of composite free radical quencher, ZrO 2 The particles weighing 150-250 g are placed in a ball mill after the ball mill jar is sealed, with a rotation speed of 450 r / min for 8-12 h. Finally, the machine is stopped and the ball mill jar is taken out. The ball mill beads are first filtered out and then vacuum defoamed. Finally, the mixture is stirred at 300 r / min for 20-30 min. A small amount of slurry is taken out with a dropper and placed on the dried second catalytic layer of the cathode. A suitable coating rod is placed on the automatic coating instrument to automatically complete the coating of catalytic layers of different thicknesses, so that the sum of the platinum loading of the two catalytic layers is 0.35-0.4 mg / cm 2 The coated double-layer cathode catalyst layer is placed in a vacuum drying oven, dried at 80°C for 5-8 hours under a vacuum atmosphere, and then taken out and placed in a constant temperature and humidity chamber for use.

[0070] Prepare the second catalyst layer slurry for the anode: 1. Weigh 2-3g Pt / C catalyst and 0.15-0.30g IrO on an analytical balance. 2 1. Add 20-40g n-propanol, 0.65-2.2g resin (EW value can be 900-1100g / mol) to the slurry, ZrO 2 The particles are 150-250g. After the ball mill is sealed, put them into a ball mill for ball milling at a speed of 450r / min for 8-12h. Finally, stop the machine and take out the ball mill. First, filter out the ball mill beads and then remove bubbles in vacuum. Finally, stir at 300r / min for 20-30min. Use a dropper to take out a small amount of slurry and place it on a clean PTFE film. Place a suitable coating rod on the automatic coating instrument to automatically complete the coating of catalytic layers of different thicknesses. The coated catalytic layer is placed in a vacuum drying oven. After drying at 80℃ for 5-8h in a vacuum atmosphere, take it out and place it in a constant temperature and humidity chamber for use.

[0071] Prepare the first catalyst layer slurry of the anode: 1. Weigh 2-3g of Pt / C catalyst on an analytical balance, put it into a ball mill, add 3-10g of deionized water to fully wet the catalyst, stir evenly and let it stand; 2. Add 20-40g of n-propanol in sequence, add 0.7-2.75g of composite free radical quencher, ZrO 2 The particles weighing 150-250 g are placed in a ball mill after the ball mill jar is sealed, with a rotation speed of 450 r / min and a ball milling time of 8-12 h. Finally, the machine is stopped and the ball mill jar is taken out. The ball mill beads are first filtered out and then vacuum defoamed. Finally, the mixture is stirred at 300 r / min for 20-30 min. A small amount of slurry is taken out with a dropper and placed on the dried anode main catalyst layer. A suitable coating rod is placed on the automatic coating instrument to automatically complete the coating of catalyst layers of different thicknesses, so that the sum of the platinum loading of the two anode catalyst layers is 0.05-0.08 mg / cm 2 The coated double-layer anode catalyst layer is placed in a vacuum drying oven, dried at 80°C for 5-8 hours under a vacuum atmosphere, and then taken out and placed in a constant temperature and humidity chamber for use.

[0072] Thermal transfer: Cut the catalyst layer coated on the PTFE film into 5×5 cm 2 , loading of 0.4 / 0.05mg Pt / cm 2 As cathode / anode catalyst layer, the anode and cathode catalyst layer and Gore12 proton membrane are transferred on a hot press at a temperature of 165-185°C and a pressure of 35kgf / cm 2 , the time is 85-170s. After the hot pressing is completed, the PTFE film is quickly torn off to obtain the membrane electrode.

[0073] In a fifth aspect, an embodiment of the present invention provides a fuel cell comprising the membrane electrode according to the third aspect.

[0074] Due to the use of the membrane electrode of the third aspect, the fuel cell of the embodiment of the present invention has the characteristics of self-humidification, high performance and long durability.

[0075] The present invention is described in detail below with reference to the embodiments and the accompanying drawings.

[0076] Example A

[0077] The composite free radical quencher comprises a resin and an active substance, wherein the resin is a perfluorosulfonic acid resin powder, the active substance is a nano-scale cerium oxide, and the active substance in the free radical quencher accounts for 5wt% of the total solid content. The preparation method of the free radical quencher is as follows: 2g of nano-cerium oxide is taken, 200mL of ethanol is added to the active substance, and the active substance is dispersed in the ethanol by an ultrasonic cell crusher to form a suspension. 40g of perfluorosulfonic acid resin powder (EW value is 700g / mol) is added to the suspension, and the dissolution process is carried out in a high-temperature autoclave at a temperature of 220°C, heated and stirred for 6h, and naturally cooled at room temperature after the reaction is completed, and the mixed solution is filtered and separated to obtain the active substance coated with the resin powder, and then recrystallized and purified in ethanol for 3 times, and then stored in an oven at 110°C for standby use.

[0078] Example B

[0079] The composite free radical quencher and its preparation method in this embodiment are the same as those in embodiment A, except that the active substance in the free radical quencher accounts for 10 wt % of the total solid content.

[0080] Example C

[0081] The composite free radical quencher and its preparation method in this embodiment are the same as those in embodiment A, except that the active substance in the free radical quencher accounts for 20 wt % of the total solid content.

[0082] Example D

[0083] The composite free radical quencher and its preparation method of this embodiment are the same as those of embodiment A, except that the active substance is nano-cerium phosphate.

[0084] Example E

[0085] The composite free radical quencher and its preparation method of this embodiment are the same as those of embodiment A, except that the active substance is nano-cerium sulfide.

[0086] Example F

[0087] The composite free radical quencher and its preparation method of this embodiment are the same as those of embodiment A, except that the active substance is nano-cerium fluoride.

[0088] Example 1

[0089] Prepare the cathode second catalyst layer slurry: 1. Weigh 2.5g Pt / C catalyst on an analytical balance, put it into a ball mill, add 7.5g deionized water to fully wet the catalyst, stir evenly and let it stand; 2. Add 30g n-propanol in sequence, add 0.9g perfluorosulfonic acid resin (EW value is 900g / mol) and ZrO 2 250g of particles are put into a ball mill after the ball mill jar is sealed, and the speed is 450r / min. The ball mill time is 12h. Finally, the machine is stopped and the ball mill jar is taken out. The ball mill beads are first filtered out and then vacuum defoamed. Finally, stir at 300r / min for 30min. A small amount of slurry is taken out with a dropper and placed on a clean PTFE film. A suitable coating rod is placed on the automatic coating instrument to automatically complete the coating of catalytic layers of different thicknesses. The coated catalytic layer is placed in a vacuum drying oven, dried at 80℃ for 8h in a vacuum atmosphere, then taken out and placed in a constant temperature and humidity chamber for use.

[0090] Prepare the cathode first catalytic layer slurry: 1. Weigh 2.5 g of Pt / C catalyst on an analytical balance, put it into a ball mill, add 6 g of deionized water to fully wet the catalyst, stir evenly and let it stand; 2. Add 40 g of n-propanol in sequence, add 1.05 g of the composite free radical quencher of Example A, ZrO 2 250g of particles were placed in a ball mill after the ball mill was sealed, with a rotation speed of 450r / min for 12h. The ball mill was finally stopped and the ball mill was taken out. The ball mill beads were first filtered out and then vacuum-defoamed. Finally, the mixture was stirred at 300r / min for 30min. A small amount of slurry was taken out with a dropper and placed on the dried second catalytic layer of the cathode. A suitable coating rod was placed on the automatic coating instrument to automatically complete the coating of catalytic layers of different thicknesses, so that the sum of the platinum loading of the two catalytic layers was 0.4mg / cm 2 The coated double-layer cathode catalyst layer was placed in a vacuum drying oven, dried at 80°C for 8 hours under vacuum atmosphere, and then taken out and placed in a constant temperature and humidity chamber for use. The loading of the composite free radical quencher in the first cathode catalyst layer was 21 μg / cm 2 .

[0091] Prepare the second catalytic layer slurry of the anode: 1. Weigh 2.5g of Pt / C catalyst and 0.25g of IrO on an analytical balance. 2 1. Add 30g of n-propanol, 1.0g of perfluorosulfonic acid resin (EW value is 900g / mol), ZrO 2250g of particles are put into a ball mill after the ball mill jar is sealed, and the speed is 450r / min. The ball mill time is 12h. Finally, the machine is stopped and the ball mill jar is taken out. The ball mill beads are first filtered out and then vacuum defoamed. Finally, stir at 300r / min for 30min. A small amount of slurry is taken out with a dropper and placed on a clean PTFE film. A suitable coating rod is placed on the automatic coating instrument to automatically complete the coating of catalytic layers of different thicknesses. The coated catalytic layer is placed in a vacuum drying oven, dried at 80℃ for 8h in a vacuum atmosphere, then taken out and placed in a constant temperature and humidity chamber for use.

[0092] Prepare the first catalytic layer slurry of the anode: 1. Weigh 2.5 g of Pt / C catalyst on an analytical balance, put it into a ball mill, add 6 g of deionized water to fully wet the catalyst, stir evenly and let it stand; 2. Add 30 g of n-propanol in sequence, add 1.16 g of the composite free radical quencher of Example A, ZrO 2 250g of particles were placed in a ball mill after the ball mill was sealed, with a rotation speed of 450r / min for 12h. The ball mill was finally stopped and the ball mill was taken out. The ball mill beads were first filtered out and then vacuum-defoamed. Finally, the mixture was stirred at 300r / min for 30min. A small amount of slurry was taken out with a dropper and placed on the dried main catalyst layer of the anode. A suitable coating rod was placed on the automatic coating instrument to automatically complete the coating of catalyst layers of different thicknesses, so that the sum of the platinum loading of the two anode catalyst layers was 0.05mg / cm 2 The coated double-layer anode catalyst layer was placed in a vacuum drying oven, dried at 80°C for 8 hours under vacuum atmosphere, and then taken out and placed in a constant temperature and humidity chamber for use. The loading of the composite free radical quencher in the first catalyst layer of the anode was 3 μg / cm 2 .

[0093] Thermal transfer: Cut the catalyst layer coated on the PTFE film into 5×5 cm 2 , loading of 0.4 / 0.05mg Pt / cm 2 As cathode / anode catalyst layers, the anode and cathode catalyst layers and the Gore12 proton membrane were transferred on a hot press at a temperature of 170°C and a pressure of 35 kgf / cm 2 After the hot pressing is completed, the PTFE film is quickly torn off to obtain a membrane electrode. In the membrane electrode, the IC ratio of the first cathode catalyst layer is higher than the IC ratio of the second cathode catalyst layer, and the IC ratio of the first anode catalyst layer is higher than the IC ratio of the second anode catalyst layer.

[0094] Example 1B

[0095] The preparation method of this embodiment is the same as the preparation method of embodiment 1, and the only difference is that the composite free radical quencher of embodiment B is used in this embodiment instead of the composite free radical quencher A of embodiment 1.

[0096] Example 1C

[0097] The preparation method of this embodiment is the same as the preparation method of embodiment 1, and the only difference is that the composite free radical quencher of embodiment C is used in this embodiment instead of the composite free radical quencher A of embodiment 1.

[0098] Example 1D

[0099] The preparation method of this embodiment is the same as the preparation method of embodiment 1, and the only difference is that the composite free radical quencher of embodiment D is used in this embodiment instead of the composite free radical quencher A of embodiment 1.

[0100] Example 1E

[0101] The preparation method of this embodiment is the same as that of embodiment 1, except that the composite free radical quencher of embodiment E is used in this embodiment instead of the composite free radical quencher A of embodiment 1.

[0102] Example 1F

[0103] The preparation method of this embodiment is the same as that of embodiment 1, except that the composite free radical quencher of embodiment F is used in this embodiment instead of the composite free radical quencher A of embodiment 1.

[0104] Example 2

[0105] Prepare the second catalyst layer slurry of the anode: 1. Weigh 2.5g of Pt / C catalyst on an analytical balance and put it into a ball mill, then add 7g of deionized water to fully wet the catalyst, stir evenly and let it stand; 2. Add 30g of n-propanol, 1.0g of perfluorosulfonic acid resin (EW value is 900g / mol), ZrO 2 250g of particles are put into a ball mill after the ball mill jar is sealed, and the speed is 450r / min. The ball mill time is 12h. Finally, the machine is stopped and the ball mill jar is taken out. The ball mill beads are first filtered out and then vacuum defoamed. Finally, stir at 300r / min for 30min. A small amount of slurry is taken out with a dropper and placed on a clean PTFE film. A suitable coating rod is placed on the automatic coating instrument to automatically complete the coating of catalytic layers of different thicknesses. The coated catalytic layer is placed in a vacuum drying oven, dried at 80℃ for 8h in a vacuum atmosphere, then taken out and placed in a constant temperature and humidity chamber for use.

[0106] Prepare the first catalytic layer slurry of the anode: 1. Weigh 2.5g Pt / C catalyst and 0.25g IrO on an analytical balance. 2 1. Add 30 g of n-propanol, 1.16 g of the composite free radical quencher of Example A, ZrO2 250g of particles were placed in a ball mill after the ball mill was sealed, with a rotation speed of 450r / min for 12h. The ball mill was finally stopped and the ball mill was taken out. The ball mill beads were first filtered out and then vacuum-defoamed. Finally, the mixture was stirred at 300r / min for 30min. A small amount of slurry was taken out with a dropper and placed on the dried main catalyst layer of the anode. A suitable coating rod was placed on the automatic coating instrument to automatically complete the coating of catalyst layers of different thicknesses, so that the sum of the platinum loading of the two anode catalyst layers was 0.05mg / cm 2 The coated double-layer anode catalyst layer was placed in a vacuum drying oven, dried at 80°C for 8 hours under a vacuum atmosphere, and then taken out and placed in a constant temperature and humidity chamber for use.

[0107] IrO 2 The base catalyst is added to the first catalytic layer of the anode, and not added to the second catalytic layer of the anode. The preparation process of the cathode catalytic slurry and the preparation process of CCM and MEA are the same as those in Example 1.

[0108] Example 3

[0109] Prepare the cathode second catalyst layer slurry: 1. Weigh 2.5g Pt / C catalyst on an analytical balance, put it into a ball mill, add 7.5g deionized water to fully wet the catalyst, stir evenly and let it stand; 2. Add 30g n-propanol in sequence, add 0.9g perfluorosulfonic acid resin (EW value is 900g / mol) and ZrO 2 250g of particles are put into a ball mill after the ball mill jar is sealed, and the speed is 450r / min. The ball mill time is 12h. Finally, the machine is stopped and the ball mill jar is taken out. The ball mill beads are first filtered out and then vacuum defoamed. Finally, stir at 300r / min for 30min. A small amount of slurry is taken out with a dropper and placed on a clean PTFE film. A suitable coating rod is placed on the automatic coating instrument to automatically complete the coating of catalytic layers of different thicknesses. The coated catalytic layer is placed in a vacuum drying oven, dried at 80℃ for 8h in a vacuum atmosphere, then taken out and placed in a constant temperature and humidity chamber for use.

[0110] Prepare the cathode first catalytic layer slurry: 1. Weigh 2.5 g of Pt / C catalyst on an analytical balance, put it into a ball mill, add 6 g of deionized water to fully wet the catalyst, stir evenly and let it stand; 2. Add 40 g of n-propanol in sequence, add 0.95 g of the composite free radical quencher of Example A, ZrO 2250g of particles were placed in a ball mill after the ball mill was sealed, with a rotation speed of 450r / min for 12h. The ball mill was finally stopped and the ball mill was taken out. The ball mill beads were first filtered out and then vacuum-defoamed. Finally, the mixture was stirred at 300r / min for 30min. A small amount of slurry was taken out with a dropper and placed on the dried second catalytic layer of the cathode. A suitable coating rod was placed on the automatic coating instrument to automatically complete the coating of catalytic layers of different thicknesses, so that the sum of the platinum loading of the two catalytic layers was 0.4mg / cm 2 The coated double-layer cathode catalyst layer was placed in a vacuum drying oven, dried at 80°C for 8 hours under a vacuum atmosphere, and then taken out and placed in a constant temperature and humidity chamber for use.

[0111] Prepare the second catalytic layer slurry of the anode: 1. Weigh 2.5g of Pt / C catalyst and 0.25g of IrO on an analytical balance. 2 1. Add 30g of n-propanol, 5g of perfluorosulfonic acid resin (EW value is 700g / mol), ZrO 2 250g of particles are put into a ball mill after the ball mill jar is sealed, and the speed is 450r / min. The ball mill time is 12h. Finally, the machine is stopped and the ball mill jar is taken out. The ball mill beads are first filtered out and then vacuum defoamed. Finally, stir at 300r / min for 30min. A small amount of slurry is taken out with a dropper and placed on a clean PTFE film. A suitable coating rod is placed on the automatic coating instrument to automatically complete the coating of catalytic layers of different thicknesses. The coated catalytic layer is placed in a vacuum drying oven, dried at 80℃ for 8h in a vacuum atmosphere, then taken out and placed in a constant temperature and humidity chamber for use.

[0112] Prepare the first catalytic layer slurry of the anode: 1. Weigh 2.5 g of Pt / C catalyst on an analytical balance, put it into a ball mill, add 6 g of deionized water to fully wet the catalyst, stir evenly and let it stand; 2. Add 30 g of n-propanol in sequence, add 1.05 g of the composite free radical quencher of Example A, ZrO 2 250g of particles were placed in a ball mill after the ball mill was sealed, with a rotation speed of 450r / min for 12h. The ball mill was finally stopped and the ball mill was taken out. The ball mill beads were first filtered out and then vacuum-defoamed. Finally, the mixture was stirred at 300r / min for 30min. A small amount of slurry was taken out with a dropper and placed on the dried main catalyst layer of the anode. A suitable coating rod was placed on the automatic coating instrument to automatically complete the coating of catalyst layers of different thicknesses, so that the sum of the platinum loading of the two anode catalyst layers was 0.05mg / cm 2 The coated double-layer anode catalyst layer was placed in a vacuum drying oven, dried at 80°C for 8 hours under a vacuum atmosphere, and then taken out and placed in a constant temperature and humidity chamber for use.

[0113] That is, the IC ratio of the first cathode catalyst layer is the same as the resin EW value and the second cathode catalyst layer, the IC ratio of the first anode catalyst layer is the same as the resin EW value and the second anode catalyst layer, and the process for preparing CCM and MEA is the same as Example 1.

[0114] Comparative Example 1

[0115] Single-layer cathode catalyst slurry: 1. Weigh 2.5g Pt / C catalyst on an analytical balance, put it into a ball mill, add 7.5g deionized water to fully wet the catalyst, stir evenly and let it stand; 2. Add 30g n-propanol, 0.9g perfluorosulfonic acid resin (EW value is 900g / mol), ZrO 2 250g of particles were put into a ball mill after the ball mill was sealed, and the speed was 450r / min for 12h. Finally, the ball mill was taken out of the ball mill, the ball beads were filtered out, and then vacuum defoamed, and finally stirred at 300r / min for 30min. A small amount of slurry was taken out with a dropper and placed on a clean PTFE film. A suitable coating rod was placed on the automatic coating instrument, and the platinum loading was automatically completed to 0.4mg / cm 2 The coated catalyst layer is placed in a vacuum drying oven, dried at 80°C for 8 hours under a vacuum atmosphere, and then taken out and placed in a constant temperature and humidity chamber for use.

[0116] Single-layer anode catalyst slurry: 1. Weigh 2.5 g Pt / C catalyst and 0.25 g IrO on an analytical balance. 2 1. Add 30g of n-propanol, 1.0g of perfluorosulfonic acid resin (EW value is 700g / mol), ZrO 2 250g of particles were put into a ball mill after the ball mill was sealed, and the speed was 450r / min for 12h. Finally, the ball mill was taken out of the ball mill, and the ball mill beads were filtered out first, then vacuum defoamed, and finally stirred at 300r / min for 30min. A small amount of slurry was taken out with a dropper and placed on a clean PTFE film. A suitable coating rod was placed on the automatic coating instrument, and the platinum loading was automatically completed to 0.05mg / cm 2 The anode catalyst layer is placed in a vacuum drying oven, dried at 80°C for 8 hours under a vacuum atmosphere, and then taken out and placed in a constant temperature and humidity chamber for use.

[0117] The process for preparing CCM and MEA is the same as that in Example 1.

[0118] Performance Testing:

[0119] (1) Cell polarization performance test: The prepared membrane electrode was directly sandwiched between two gas diffusion layers and tested on a fuel cell test fixture with a serpentine flow field. The cell temperature was 80°C, humidification RH10% / 10%, H 2 The initial flow rates on the side and air side were set to 0.3 / 0.7 NLPM, the excess coefficients were 1.5 / 2.0, and the back pressure was 100 kPa / 100 kPa.

[0120] (2) Square wave endurance test: The cathode and anode areas are both 5×5cm 2 , control the battery temperature to 80℃, H 2 / N 2 Flow rate: 0.2 / 0.1NLPM, back pressure 0 / 0kPa, humidification of cathode and cathode 100% / 100%. Connect the positive electrode of the electrochemical potentiostat to the cathode of the battery, and the negative electrode to the anode of the battery. Set the potential of the potentiostat between 0.6V (3s) and 0.95V (3s) for square wave cycle. The potential switching time is less than 0.5s, and each cycle is 6s. Measure the battery polarization curve and electrochemical active area at the cumulative 0th, 5000th, 10000th, 15000th, 20000th, 25000th, and 30000th cycles, and examine 0.8A / cm 2 The voltage decays.

[0121] (3) Accelerated test of chemical stability of proton membrane: the anode and cathode areas are both 5×5 cm 2 , H 2 / Air flow rate: 0.35 / 0.83LPM, battery temperature: 90℃, cathode and anode humidity 30% / 30%, outlet back pressure: 50 / 50kPa, no need to connect electronic load, keep running in open circuit state, record open circuit voltage (OCV) in OCV test record table every hour, measure hydrogen permeation current density every 100h until OCV decay>20% or hydrogen permeation current density>15mA / cm 2 .

[0122] (4) Membrane electrode performance anti-reverse polarity performance test: the anode and cathode areas are both 5×5cm 2 , the humidification of the cathode and anode is RH100%, the anode gas is nitrogen, the cathode gas is air, the gas flow rate is 1SLPM, the pressure is atmospheric pressure, the battery temperature is 75℃, the battery is connected to a constant current source, the anode is connected to the positive electrode of the constant current source, the cathode is connected to the negative electrode of the constant current source, and the current density is 0.2A / cm 2 , set the battery cut-off voltage to -1.5V. When the battery voltage reaches the cut-off voltage of -1.5V, the current applied by the constant current source is automatically cut off, the reverse polarity stops, and the reverse polarity time is recorded.

[0123] Table 1 Square wave durability after 30k cycles 0.8A / cm 2 Lower voltage loss

[0124]

[0125] Appendix 2 Test of membrane electrode anti-reverse polarity performance

[0126]

[0127] Appendix 3 Membrane electrode 500h chemical stability accelerated durability test

[0128]

[0129] Appendix 4: 1500h Actual Durability of Membrane Electrode

[0130]

[0131] Figure 1 1 is a performance comparison curve of the membrane electrode of Example 1 and Examples 1B-1F. Figure 1 It can be seen that the performance of each membrane electrode is not much different.

[0132] Figure 2 The performance comparison curves of the membrane electrodes of Examples 1-3 and Comparative Example 1 are shown in FIG. 1 . The cathode / anode catalyst layer has a platinum loading of 0.4 / 0.05 mg Pt / cm 2 .from Figure 2 It can be seen that in the electrochemical polarization region (0.8-1.0V), the membrane electrode of Examples 1-3 is superior to the membrane electrode of Comparative Example 1 in terms of battery performance. This is because the addition of a composite free radical quencher in the first catalytic layer of the anode and cathode increases the water retention at low electric density and accelerates proton conduction, so the battery performance at low electric density is higher. In the mass transfer polarization region, the performance of the membrane electrode of Example 1 is 0.65V@1.86A / cm 2 The performance of the membrane electrode of Example 2 is 0.65V@1.85A / cm 2 The performance of the membrane electrode of Example 3 is 0.65V@1.69A / cm 2 The battery performance is better than that of the membrane electrode of comparative example 1 (0.65V@1.52A / cm 2 ), this is because the IC ratio of the first catalytic layer of the anode and cathode in the double-layer membrane electrode is higher than that of the second catalytic layer, and the EW value of the resin in the first catalytic layer is lower than that of the resin in the second catalytic layer, which is more conducive to drainage and gas conduction under high current density.

[0133] As shown in Table 1, the membrane electrodes of Examples 1-3 and Comparative Example 1 were subjected to a square wave durability test for 30k cycles. 2The voltage decay is less than 30mV, which meets the DOE standard. This is because a composite free radical quencher is added to the first catalytic layer of the anode and cathode to reduce the attack of free radicals and improve the durability of the membrane electrode.

[0134] As shown in Table 2, the membrane electrodes of Examples 1-3 and Comparative Example 1 were tested for anti-reverse polarity. The membrane electrode of Example 1 had the longest anti-reverse polarity time, and the voltage decayed (@2A / cm 2 ) ratio is the smallest. According to the anti-reverse polarity results of Examples 1-2 and Comparative Example 1, it can be seen that compared with adding iridium-based catalysts to the first catalytic layer of the anode and adding iridium-based catalysts to the anode monolayer, adding iridium-based catalysts to the second catalytic layer of the anode is more helpful to improve the anti-reverse polarity performance of the membrane electrode.

[0135] As shown in Appendix 3, the membrane electrodes of Example 1 and Comparative Example 1 were subjected to a 500-h chemical stability accelerated durability test. The initial rated performance of the membrane electrodes was similar, but after 500-h chemical stability accelerated durability, the OCV attenuation and hydrogen permeation current of the membrane electrode in Example 1 were significantly lower than those in Comparative Example 1, indicating that the addition of cerium oxide to the first catalytic layer of the anode and cathode can improve the durability of the membrane electrode and simplify the design of the durable proton membrane.

[0136] In addition, a 1000h durability test was conducted on Example 1 and Comparative Example 1. The durability test method refers to the national standard (GB-Z44116-2024 Durability test method for fuel cell engines and key components). As shown in Appendix 4, the performance degradation of the membrane electrode of Example 1 after 1500h durability is significantly less than that of the membrane electrode of Comparative Example 1, which is attributed to the catalytic slurry formula design and the new membrane electrode structure design. In order to prove the structure of the membrane electrode, as shown in Appendix 4, Figure 3 As shown, the cathode in the membrane electrode of Example 1 was characterized by cross-sectional line scanning. The thickness of the cathode catalytic layer is 11-12μm, the thickness of the cathode second catalytic layer is 8-9μm, and the thickness of the cathode first catalytic layer is 3-4μm. From the fluorine content, it can be seen that the fluorine content of the first cathode catalytic layer is significantly higher than that of the second cathode catalytic layer. This is because the resin content of the first cathode catalytic layer is higher than that of the second cathode catalytic layer. This also shows the reliability of the double-layer catalytic layer.

[0137] The embodiments of the present invention can solve the problems of large proton transmission resistance at low electric density of automotive proton membrane fuel cells, low membrane electrode performance caused by flooding at high electric density, and short membrane electrode life caused by variable load start-stop. By comparing the above embodiment 1 with embodiment 2 and embodiment 3, it can be seen that the membrane electrode performance and durability of embodiment 1 are the best.

[0138] Example 1 A double-layer catalyst layer is constructed in the cathode catalyst layer (the cathode first catalyst layer is near the proton membrane side, and the cathode second catalyst layer is near the GDL side), the IC ratio of the cathode first catalyst layer is higher than the IC ratio of the cathode second catalyst layer, and the ion exchange equivalent (EW value) of the resin of the cathode first catalyst layer is lower than the ion exchange equivalent (EW value) of the resin of the cathode second catalyst layer, thereby achieving the effect of low electric density water retention and high electric density water drainage, improving the performance of the membrane electrode, and adding a composite free radical quencher to the cathode first catalyst layer, thereby slowing down the loss of water from the membrane electrode, while preventing the generated free radicals from attacking or corroding the proton exchange membrane, and increasing the life of the membrane electrode. Example 1 A double-layer catalyst layer is constructed in the anode catalyst layer (the anode first catalyst layer is near the proton membrane side, and the anode second catalyst layer is near the GDL side), the IC ratio of the anode second catalyst layer is lower than the IC ratio of the anode first catalyst layer, and the ion exchange equivalent (EW value) of the resin of the anode first catalyst layer is lower than the ion exchange equivalent (EW value) of the resin of the anode second catalyst layer, which can play a role in draining the water from the cathode reverse permeation and slowing down the corrosion caused to the bipolar plate. In addition, a composite free radical quencher is also added to the first catalytic layer of the anode of Example 1 to improve proton conduction and reduce free radical attacks, thereby improving the performance and durability of the membrane electrode. In addition, Example 1 adds an iridium-based catalyst to the second catalytic layer of the anode, so that iridium oxide can catalyze water decomposition to produce protons faster, improve the anti-reverse polarity time, reduce the performance decay after the reverse polarity, and improve the durability of the membrane electrode when the fuel is insufficient. Example 1 adds a composite free radical quencher to the cathode and the first catalytic layer of the anode to prevent the generated free radicals from attacking or corroding the proton exchange membrane, simplifying the design of the durable proton membrane, thereby achieving high-performance output and industrial application of proton membrane fuel cells.

[0139] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0140] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A composite free radical quencher, characterized in that: It comprises an active substance and a perfluorosulfonic acid resin powder coating the active substance, wherein the active substance is at least one of nano-scale cerium oxide, cerium phosphate, cerium sulfide and cerium fluoride; optionally, based on the total mass of the composite free radical quencher being 100wt%, the content of the active substance is 5-20wt%.

2. The method for preparing the composite free radical quencher according to claim 1, characterized in that: The following steps are involved: S1. dispersing the active substance in ethanol to form a suspension, and then mixing the suspension with the perfluorosulfonic acid resin powder to obtain a mixture; S2. The mixture is placed in a high temperature autoclave, hydrothermally heated at 200-300 ° C for 4-10h, and after the reaction is completed, the mixture is naturally cooled at room temperature to obtain a mixed solution; S3. performing solid-liquid separation on the mixed liquid to obtain a solid substance, then recrystallizing and purifying the solid substance in ethanol, and drying to obtain the composite free radical quencher.

3. A membrane electrode, comprising an anode catalyst layer, a proton exchange membrane and a cathode catalyst layer, characterized in that: The cathode catalyst layer and / or the anode catalyst layer contains the composite free radical quencher according to claim 1.

4. The membrane electrode according to claim 3, characterized in that: The loading amount of the composite free radical quencher in the cathode catalyst layer is 6.7-33.3 μg / cm 2 , and / or, the loading amount of the composite free radical quencher in the anode catalyst layer is 1.0-4.7 μg / cm 2 .

5. The membrane electrode according to claim 3, characterized in that: The cathode catalytic layer includes a first cathode catalytic layer close to the proton exchange membrane and a second cathode catalytic layer away from the proton exchange membrane, the anode catalytic layer includes a first anode catalytic layer close to the proton exchange membrane and a second anode catalytic layer away from the proton exchange membrane, and the first cathode catalytic layer and / or the first anode catalytic layer contain the composite free radical quencher according to claim 1.

6. The membrane electrode according to claim 5, characterized in that: The IC ratio of the first cathode catalytic layer is higher than the IC ratio of the second cathode catalytic layer, and the EW value of the resin of the first cathode catalytic layer is lower than the EW value of the resin of the second cathode catalytic layer; and / or, the IC ratio of the first anode catalytic layer is higher than the IC ratio of the second anode catalytic layer, and the EW value of the resin of the first anode catalytic layer is lower than the EW value of the resin of the second anode catalytic layer.

7. The membrane electrode according to claim 5, characterized in that: The second catalytic layer of the anode contains a platinum-based catalyst and an iridium-based catalyst.

8. The method for preparing a membrane electrode according to any one of claims 3 to 7, characterized in that: The following steps are involved: (1) mixing a platinum-based catalyst, the composite free radical quencher or resin, water and an organic solvent to obtain a cathode catalyst layer slurry, and then coating the cathode catalyst layer slurry on a first transfer substrate to form the cathode catalyst layer, thereby obtaining a first transfer substrate with a cathode catalyst layer; (2) mixing a platinum-based catalyst, the composite free radical quencher or resin, water and an organic solvent to obtain an anode catalyst layer slurry, and then coating the anode catalyst layer slurry on a second transfer substrate to form the anode catalyst layer, thereby obtaining a second transfer substrate with an anode catalyst layer; (3) The first transfer substrate with the cathode catalyst layer, the second transfer substrate with the anode catalyst layer, and the proton exchange membrane are hot-pressed on a hot press so that the cathode catalyst layer is transferred to one side of the proton exchange membrane and the anode catalyst layer is transferred to the other side of the proton exchange membrane, and then the first transfer substrate and the second transfer substrate are removed to obtain the membrane electrode.

9. The preparation method according to claim 8, characterized in that: Step (1) The method comprises the following steps: mixing a platinum-based catalyst, the composite free radical quencher, water and an organic solvent to obtain a cathode first catalytic layer slurry; mixing a platinum-based catalyst, water, an organic solvent and a resin to obtain a cathode second catalytic layer slurry; then coating the cathode second catalytic layer slurry on a first transfer substrate to form the cathode second catalytic layer; then coating the cathode first catalytic layer slurry on the cathode second catalytic layer to form the cathode first catalytic layer, and obtaining a first transfer substrate with a cathode catalytic layer; And / or, step (2) comprises the following steps: mixing a platinum-based catalyst, the composite free radical quencher, water and an organic solvent to obtain an anode first catalytic layer slurry, mixing a platinum-based catalyst, water, an organic solvent and a resin to obtain an anode second catalytic layer slurry, and then coating the anode second catalytic layer slurry on a second transfer substrate to form the anode second catalytic layer, and then coating the anode first catalytic layer slurry on the anode second catalytic layer to form the anode first catalytic layer, and obtaining a second transfer substrate with an anode catalytic layer; Optionally, a platinum-based catalyst, an iridium-based catalyst, water, an organic solvent and a resin are mixed to obtain the anode second catalyst layer slurry.

10. A fuel cell, characterized in that: A membrane electrode comprising the membrane electrode as described in any one of claims 4 to 8.

Images