A proton exchange membrane fuel cell membrane electrode recovery method, a test method and a fuel cell monomer

Abstract

The embodiment of the present application discloses a proton exchange membrane fuel cell membrane electrode recovery method, a test method and a fuel cell monomer, wherein the proton exchange membrane fuel cell membrane electrode recovery method comprises: subjecting a CCM component to a low-temperature embrittlement treatment at a temperature of ‑196°C for 8‑24 hours; subjecting the CCM component after the low-temperature embrittlement to a crushing treatment so that the catalyst layer and the proton exchange membrane are completely crushed to obtain mixed particles; separating the crushed mixed particles by a blower so that the catalyst layer and the proton exchange membrane in the mixed particles are separated; preparing a catalyst slurry by a mixture of deionized water and isopropanol, spraying the catalyst slurry on both sides of the proton exchange membrane, and then adding a gas diffusion layer into a hot press mold, and hot pressing at a temperature of 140°C and a pressure of 3MPa to obtain a fuel cell membrane electrode. By setting a low-temperature crushing method in combination with an ultrasonic dispersion process, the purity of the recovered catalyst layer can be improved and the production cost can be reduced.

Description

Technical Field

[0001] The invention relates to the field of proton exchange membrane fuel cells, and in particular to a recovery method and a testing method for a membrane electrode of a proton exchange membrane fuel cell and a fuel cell monomer. Background Art

[0002] In the tide of global energy transformation, hydrogen fuel cells, as a representative of clean energy technology, are becoming increasingly important. This conversion device directly converts hydrogen and oxygen into electricity and water through electrochemical reactions. It not only has high energy conversion efficiency, but also has almost zero emissions. Especially in the fields of transportation, backup power supply and distributed power generation, hydrogen fuel cells have great application potential, which indicates a major change in the future energy structure.

[0003] In hydrogen fuel cell systems, membrane electrode assemblies (MEAs) play a core role and directly affect the performance, efficiency and life of the battery. MEAs are composed of key parts such as proton exchange membranes, catalyst layers and diffusion layers. Among them, the proton exchange membrane, as a conductive medium for hydrogen ions, is the core platform for electrochemical reactions, while the catalyst layer is responsible for accelerating the electrochemical reaction of hydrogen and oxygen. Due to the complexity and high technical content of the proton exchange membrane and the catalyst layer, the membrane electrode assembly accounts for a considerable proportion of the total cost of fuel cells, becoming one of the key factors restricting the commercialization of fuel cells.

[0004] CCM (Catalyst Coated Membrane) is a composite of a proton exchange membrane and a catalytic layer. The catalyst is evenly distributed on the proton exchange membrane through precision coating technology, further improving the catalytic efficiency of the electrode and the overall performance of the battery. However, in the production process of CCM, due to process control, material heterogeneity or equipment precision limitations, products with unqualified appearance often appear, such as uneven coating, bubbles, cracks and other defects. These unqualified products are often treated as waste, increasing manufacturing costs and causing waste of precious resources.

[0005] In addition, even in the process of cutting qualified CCM, a certain proportion of scraps will be generated. This part of the material is also rich in expensive catalysts and proton exchange membranes, which are traditionally difficult to recycle efficiently, further exacerbating the cost problem. In view of the rapid development of the hydrogen fuel cell industry and the urgent need to reduce costs, exploring efficient and environmentally friendly CCM recycling methods has become the key to promoting the popularization and sustainable development of fuel cell technology.

[0006] Existing MEA recovery technologies mostly use organic solvents to assist in the separation of the catalyst layer and the proton exchange membrane, which faces two major limitations: First, the solvent can easily partially separate the catalyst from the perfluorosulfonic acid ionomer resin, resulting in a change in the ratio of the perfluorosulfonic acid ionomer resin to the carbon carrier in the catalyst (IC ratio), making it impossible to directly reuse the catalyst. Precious metals can only be recovered by hydrometallurgy and other methods, which increases costs and complexity; second, the solvent has a potential environmental pollution risk, and careless use and treatment may introduce ecological burdens. Therefore, it is urgent to improve the strategy to focus on improving the catalyst separation efficiency and environmental compatibility, and to reuse the catalyst without the need for additional operations. Summary of the invention

[0007] In order to solve the problems existing in the prior art, the present invention provides a proton exchange membrane fuel cell membrane electrode recovery method, a testing method and a fuel cell monomer, which can ensure the recovery efficiency and recovery purity and reduce the overall reuse cost through crushing and separation treatment combined with ultrasonic dispersion technology.

[0008] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0009] The present application provides a method for recovering a proton exchange membrane fuel cell membrane electrode, which is used to obtain a fuel cell membrane electrode. The recovery method comprises:

[0010] Step 1: Ultra-low temperature embrittlement treatment: The CCM component is subjected to ultra-low temperature embrittlement treatment in an ultra-low temperature environment to obtain a CCM component subjected to ultra-low temperature embrittlement treatment, wherein the ultra-low temperature embrittlement time is 8-24 hours;

[0011] Step 2: Crushing: crushing the CCM components after the ultra-low temperature embrittlement treatment to obtain mixed particles;

[0012] Step 3: Separation treatment: using a fan to separate the mixed particles obtained after the crushing treatment, so that the catalyst layer particles contained in the mixed particles are separated from the mixed particles, and the separated catalyst layer particles are collected;

[0013] Step 4: Catalytic layer treatment: adding a mixture of deionized water and isopropanol to the collected catalytic layer particles, and using ultrasound to disperse the catalytic layer particles and the mixture to prepare a catalyst slurry;

[0014] The catalyst slurry is used to spray the two sides of the proton exchange membrane respectively, and after the spraying is completed, the gas diffusion layer is attached to the two sides, which are loaded into the mold of the hot press machine, and hot-pressed at a temperature of 140° C. and a pressure of 3 MPa to obtain a fuel cell membrane electrode;

[0015] Wherein, the CCM component includes multiple catalytic coating membranes.

[0016] Optionally, in some embodiments of the present application, the ultra-low temperature environment is a liquid nitrogen or liquid helium environment; the temperature of the ultra-low temperature environment is -270°C to -190°C.

[0017] Optionally, in some embodiments of the present application, in step 2, the crushing treatment includes processing by an ultrasonic crusher, the crushing temperature is -20°C-0°C, the frequency of the ultrasonic crusher is 30-90kHz, the power is 500-1000W, and the processing time is 30-120min.

[0018] Optionally, in some embodiments of the present application, in step three, the fan is a cyclone separator with a wind speed of 40m / s-80m / s and a wind pressure difference of 1500Pa-5000Pa, so that the proton exchange membrane particles are blown to the collector and the catalyst layer particles remain at the bottom, so as to achieve separation of the proton exchange membrane particles and the catalyst layer particles.

[0019] Optionally, in some embodiments of the present application, in step 4, the volume ratio of the deionized water and isopropyl ketone is 1:2.

[0020] The present application also provides a testing method for testing a fuel cell membrane electrode obtained by the proton exchange membrane fuel cell membrane electrode recovery method as described in any one of the above, and the testing method comprises:

[0021] Step 1: Activate the fuel cell membrane electrode;

[0022] Step 2: Installing the activated fuel cell membrane electrode on the fuel cell;

[0023] Step three: controlling the current value or voltage value of the fuel cell discharge, and outputting corresponding current-voltage relationship data.

[0024] Optionally, in some embodiments of the present application, the test conditions in the test method are that the humidity of hydrogen and oxygen is 50% RH;

[0025] Among them, the hydrogen pressure and oxygen pressure are set to 0.28MPa and 0.30MPa respectively.

[0026] When the fuel cell test temperature is 80° C., the current-voltage relationship data of the fuel cell is output.

[0027] The present application also provides a fuel cell monomer, including a fuel cell membrane electrode obtained by the proton exchange membrane fuel cell membrane electrode recovery method as described in any one of the above, the fuel cell monomer includes a fuel cell membrane electrode, a plate, a sealing gasket and an end plate, the plate includes a graphite plate with a size of 50×50×3mm, the inner side of which is designed as a parallel serpentine three-flow channel, the sealing gasket includes a plastic gasket, the end plate includes a stainless steel plate, and the effective area of ​​the membrane electrode in the fuel cell is 25cm 2 .

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] Environmentally friendly, no harmful chemical solvents are required in the whole process, low-temperature embrittlement and ultrasonic crushing avoid pollutants such as HF that may be produced in traditional methods, reducing environmental impact; high efficiency and low cost, low-temperature freezing and ultrasonic combination process, non-invasive low-temperature embrittlement material, ultrasonic crushing reduces energy consumption, reduces overall cost, simplifies steps, and improves economy; high recovery rate and purity, ultra-low temperature crushing cyclone selection method utilizes density difference, no solvent is required, directly separates catalyst layer particles and proton exchange membrane particles of different densities, maintains the purity of the catalyst layer, and is conducive to direct recovery and reuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A schematic flow chart of a proton exchange membrane fuel cell membrane electrode recovery method provided in an embodiment of the present application;

[0032] Figure 2 A schematic flow chart of a test method for the operation of a fuel cell membrane electrode provided in an embodiment of the present application;

[0033] Figure 3 It is a comparison diagram of polarization curves of the embodiments of the present application and the comparative example. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present application. It is understood that the drawings are only provided for reference and illustration, and are not used to limit the present application. The connection relationship shown in the drawings is only for the convenience of clear description and does not limit the connection method.

[0035] Specifically, Figure 1 As shown, a method for recycling a proton exchange membrane fuel cell membrane electrode is provided in an embodiment of the present application. The recycling method is mainly used to recycle the discarded CCM components to obtain a reusable CCM, and then make a fuel cell membrane electrode (MEA, Membrane Electrode Assembly), wherein the recycling and production process of the fuel cell membrane electrode is:

[0036] Step 1: low temperature embrittlement treatment: performing ultra-low temperature embrittlement treatment on the CCM component in an ultra-low temperature environment to obtain a CCM component after ultra-low temperature embrittlement treatment, wherein the ultra-low temperature embrittlement time is 8-24 hours;

[0037] Step 2: Crushing treatment: crushing the CCM component after the ultra-low temperature embrittlement treatment, so that the catalyst layer and the proton exchange membrane in the CCM component are completely crushed to obtain mixed particles;

[0038] Step 3: separation treatment: using a fan to separate the mixed particles obtained after the crushing treatment, so that the catalyst layer particles and the proton exchange membrane particles in the mixed particles are separated, and the separated catalyst layer particles are collected;

[0039] Step 4: Catalytic layer treatment: adding a mixture of deionized water and isopropanol to the collected catalytic layer particles, and using ultrasonic dispersion to prepare a catalyst slurry;

[0040] The catalyst slurry is used to spray both sides of the proton exchange membrane respectively. After spraying, the gas diffusion layer is attached to both sides and loaded into a mold of a hot press machine. The membrane electrode is hot-pressed at 140°C and 3MPa to obtain a fuel cell membrane electrode.

[0041] Among them, in step 1, the CCM component will be embrittled in a low-temperature environment during the low-temperature catalytic treatment process. The embrittlement process changes the tough state in the CCM component into a brittle state, which facilitates the separation of the catalyst layer and the proton exchange membrane in the CCM component;

[0042] In a low-temperature environment, the embodiment of the present application provides an ultra-low-temperature environment by means of liquid nitrogen, and the environment is set to -196°C. Preferably, the present application can also provide the temperature by means of liquid helium, and the temperature is set to -269°C.

[0043] Among them, in step 2, the crushing treatment is mainly carried out by crushing and separating by an ultrasonic crusher, the ultrasonic frequency of the ultrasonic crusher is controlled to be 30-90kHz, the power is set to 500-1000W, the processing time is 30-120 minutes, and the crushing temperature is -20℃-0℃. Under this environment and conditions, the catalytic layer and the proton exchange membrane in the CCM component can be completely separated, and the separated catalytic layer and the proton exchange membrane are formed into particles and mixed to form mixed particles.

[0044] In step three, the crushed mixed particles are separated by a cyclone separator, in which the wind speed is controlled at 40m / s-80m / s, and the wind pressure difference is 1500Pa-5000Pa. Since the proton exchange membrane is light in weight and the catalyst layer is heavy in weight, the proton exchange membrane particles can be blown into a collector for collection during separation, and the catalyst layer particles remain at the bottom of the cyclone separator to achieve complete separation of the proton exchange membrane particles and the catalyst layer particles.

[0045] In step 4, a mixture of deionized water and isopropyl ketone is added to the collected catalyst layer particles, and ultrasonic dispersion is used for treatment, specifically:

[0046] The volume ratio of deionized water to isopropyl ketone is 1:2. After the deionized water and isopropyl ketone are mixed in proportion, the catalyst layer particles are added for ultrasonic dispersion and stirring to obtain a catalyst slurry, wherein the solid content in the catalyst slurry is controlled to be about 1.5%, that is, the mass of the catalyst layer accounts for 1.5% of the catalyst slurry. After obtaining the catalyst slurry, the slurry is ultrasonically sprayed on the proton exchange membrane. During the spraying process, the nozzle movement speed and the discharge speed are adjusted to control the cathode platinum loading to 0.35 mg / cm 2 , the anode platinum loading is 0.1 mg / cm 2， , control the temperature of the proton exchange membrane carrier to 85℃, after completing the anode and cathode slurry spraying, form the catalyst membrane, and then The gas diffusion layers are attached to both sides of the catalyst membrane, loaded into a mold of a hot press, and hot-pressed for 2 minutes at 140°C and 3MPa pressure to obtain a fuel cell membrane electrode.

[0047] The performance of the fuel cell membrane electrode recovered by the above method needs to be tested by a test method. The test needs to use a control group for control treatment, which can compare the current-voltage relationship of the fuel cell membrane electrode prepared in the embodiment of the present application.

[0048] Among them, in the comparative example of the present application, a conventional fuel cell membrane electrode recycling preparation process under the prior art is selected, which mainly includes the following steps:

[0049] Step 1:

[0050] Solvent immersion treatment: Take 100cm of the same area 2 The CCM components were directly immersed in a pre-prepared mixed solvent (N,N-dimethylformamide or N-methylpyrrolidone, volume ratio 1:1) and soaked for 48 hours at room temperature with ultrasound assistance to promote the dissolution and detachment of the catalyst layer from the proton exchange membrane;

[0051] Step 2:

[0052] Centrifugal washing: The soaked solution is separated by a centrifuge, and the centrifugal speed is set to 8000rpm for 10 minutes. Under the action of centrifugal force, the catalytic layer is deposited at the bottom of the centrifuge tube to form catalytic layer particles, while the dissolved membrane fragments and solvent float up. Subsequently, the catalytic layer particles are centrifuged and washed three times with ethanol to remove residual solvent and impurities. Fresh ethanol is replaced after each centrifugation. The washed catalyst particles are vacuum dried at 60°C for 24 hours to ensure complete removal of moisture, and the treated catalytic layer particles are collected.

[0053] Catalytic layer treatment:

[0054] Adding a mixture of deionized water and isopropanol to the collected catalyst layer particles, and dispersing them by ultrasonic to prepare a catalyst slurry;

[0055] The catalyst slurry is used to spray both sides of the proton exchange membrane respectively. After spraying, the gas diffusion layer is attached to both sides and loaded into a mold of a hot press machine. The membrane electrode is hot-pressed at 140°C and 3MPa to obtain a fuel cell membrane electrode.

[0056] Among them, the process of step three of this comparative example is the same as the processing process and processing parameters of step four in the embodiment of the present application, and will not be elaborated here.

[0057] In the above, the fuel cell membrane electrode is prepared in the embodiment and the comparative example respectively under the above two processes. After the fuel cell membrane electrode is completed, the fuel cell membrane electrode needs to be tested.

[0058] The test is mainly processed by a test method, which includes:

[0059] Step 1: Activate the fuel cell membrane electrode;

[0060] Step 2: Installing the activated fuel cell membrane electrode on the fuel cell;

[0061] Step three: controlling the current value or voltage value of the fuel cell discharge, and outputting corresponding current-voltage relationship data.

[0062] In the above step 1, the fuel cell membrane electrode is activated mainly to make the proton exchange membrane and the Nafion resin (perfluorosulfonic acid resin) contained in the catalyst layer contain sufficient water to ensure sufficient conductivity and to ensure that the performance of the electrode reaches the best state, thereby improving measurement accuracy, extending the service life of the electrode, and stabilizing the electrode performance.

[0063] After the electrode is activated, the fuel cell membrane electrode needs to be installed and tested. The fuel cell membrane electrode is installed on the corresponding two electrodes of the fuel cell. During the installation process, it needs to be installed on the test bench. During the test, the humidity of hydrogen and oxygen in the electrochemical performance test conditions of the membrane electrode is 50%RH. The hydrogen pressure and oxygen pressure are adjusted to 0.28MPa and 0.30MPa respectively. The fuel cell is connected to an external constant current and constant voltage power supply. The temperature of the fuel cell rises to 80℃, and the voltage-current curve of the fuel cell is measured, such as Figure 3 shown.

[0064] Among them, one factor that causes the above voltage-current curve to change is mainly the different proportions of the components in the catalyst, as shown in Table 1 below:

[0065] Table 1:

[0066]

[0067] In the examples of the present application, it can be seen from Table 1 above that C (mass%): 53.71; Pt (mass%): 29.83; F (mass%): 10.61; O (mass%): 5.92 and S (mass%): 0.42.

[0068] In the comparative example: C (mass%): 59.76; Pt (mass%): 32.45; F (mass%): 5.31; O (mass%): 2.46 and S (mass%): 0.02.

[0069] Wherein, mass% in the embodiments of the present application refers to mass percentage.

[0070] In the embodiment of the present application, a fuel cell monomer is also included, which can be used for fuel cell membrane electrode testing, including a fuel cell membrane electrode obtained by a proton exchange membrane fuel cell membrane electrode recovery method, the fuel cell monomer includes a fuel cell membrane electrode, a plate, a sealing gasket and an end plate, the plate includes a graphite plate with a size of 50×50×3mm, the inner side is designed as a parallel serpentine three-flow channel, the sealing gasket includes a plastic gasket, the end plate includes a stainless steel plate, and the effective area of ​​the membrane electrode in the fuel cell is 25cm 2 .

[0071] It can be seen from the catalyst content components and voltage-current curves of the above-mentioned embodiments and comparative examples that the membrane electrode of the embodiments has obvious performance advantages over the comparative examples. This is mainly because the use of a solvent method to strip the catalytic layer in the comparative example of the present application will cause the perfluorosulfonic acid ionomer resin in the catalytic layer to precipitate, resulting in reduced performance. This shows that the method in this embodiment can effectively keep the catalyst components in the waste fuel cell membrane electrode CCM unchanged, while optimizing the recovery steps and reducing the recovery cost.

[0072] The above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A method for recovering a proton exchange membrane fuel cell membrane electrode, used to obtain a fuel cell membrane electrode, It is characterized in that The method for recovering a proton exchange membrane fuel cell membrane electrode comprises: Step 1: Ultra-low temperature embrittlement treatment: The CCM component is subjected to ultra-low temperature embrittlement treatment in an ultra-low temperature environment to obtain a CCM component subjected to ultra-low temperature embrittlement treatment, wherein the ultra-low temperature embrittlement time is 8-24 hours; Step 2: Crushing treatment: The CCM component after the ultra-low temperature embrittlement treatment is treated by an ultrasonic crusher, so that the catalyst layer and the proton exchange membrane in the CCM component are completely separated, and the separated catalyst layer and the proton exchange membrane are mixed to form mixed particles, wherein the crushing temperature is -20°C-0°C, the frequency of the ultrasonic crusher is 30-90kHz, the power is 500-1000W, and the processing time is 30-120min; Step 3: Separation treatment: using a fan to separate the mixed particles obtained after the crushing treatment, so that the catalyst layer particles contained in the mixed particles are separated from the mixed particles, and the separated catalyst layer particles are collected; Step 4: Catalytic layer treatment: adding a mixture of deionized water and isopropanol to the collected catalytic layer particles, and using ultrasound to disperse the catalytic layer particles and the mixture to prepare a catalyst slurry; The catalyst slurry is used to spray the two sides of the proton exchange membrane respectively, and after the spraying is completed, the gas diffusion layer is attached to the two sides, which are loaded into the mold of the hot press machine, and hot-pressed at a temperature of 140° C. and a pressure of 3 MPa to obtain a fuel cell membrane electrode; Wherein, the CCM component includes multiple catalytic coating membranes.

2. The method for recovering a proton exchange membrane fuel cell membrane electrode according to claim 1, It is characterized in that The ultra-low temperature environment is a liquid nitrogen or liquid helium environment.

3. The method for recovering a proton exchange membrane fuel cell membrane electrode according to claim 1, It is characterized in that The temperature range of the ultra-low temperature environment is -270°C to -190°C.

4. The method for recovering a proton exchange membrane fuel cell membrane electrode according to claim 1, It is characterized in that In step three, the fan is a cyclone separator with a wind speed of 40m / s-80m / s and a wind pressure difference of 1500Pa-5000Pa.

5. The method for recovering a proton exchange membrane fuel cell membrane electrode according to claim 1, It is characterized in that In step 4, the volume ratio of the deionized water to isopropyl ketone is 1:

2.

6. A testing method for testing a fuel cell membrane electrode obtained by the method for recovering a proton exchange membrane fuel cell membrane electrode according to any one of claims 1 to 5, It is characterized in that The test method includes: Step 1: Activate the fuel cell membrane electrode; Step 2: Installing the activated fuel cell membrane electrode on the fuel cell; Step three: controlling the current value or voltage value of the fuel cell discharge, and outputting corresponding current-voltage relationship data.

7. The testing method according to claim 6, It is characterized in that The test conditions in the test method are that the humidity of hydrogen and oxygen is 50% RH; Among them, the hydrogen pressure and oxygen pressure were set to 0.28MPa and 0.30MPa respectively; When the fuel cell test temperature is 80° C., the current-voltage relationship data of the fuel cell is output.

8. A fuel cell monomer, comprising a fuel cell membrane electrode obtained by the method for recovering a proton exchange membrane fuel cell membrane electrode according to any one of claims 1 to 5, It is characterized in that The fuel cell monomer comprises a fuel cell membrane electrode, a plate, a sealing gasket and an end plate. The plate comprises a graphite plate with a size of 50×50×3 mm, and the inner side is designed as a parallel serpentine three-flow channel. The sealing gasket comprises a plastic gasket, and the end plate comprises a stainless steel plate. The effective area of ​​the membrane electrode in the fuel cell is 25 cm 2 .

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