Proton exchange membrane durability test method

Abstract

The invention provides a proton exchange membrane durability test method, and relates to the technical field of proton exchange membrane fuel cells, and the method comprises the following steps: respectively coating two sides of a proton exchange membrane with coatings, respectively attaching thin film layers to the outer sides of the coatings on the two sides, preparing a single cell, and carrying out durability test on the single cell by using a fuel cell test platform, the coating comprises a substance for accelerating chemical degradation of the proton exchange membrane. Compared with an existing test method for testing the durability of the proton exchange membrane by adopting a membrane electrode, the durability test method for the proton exchange membrane does not comprise attenuation of cathode and anode catalyst layers and attenuation of a gas diffusion layer, the durability rate of the proton exchange membrane can be truly reflected, and the method is simple in operation step, low in cost and high in practicability. The device is convenient, practical, free of hydrogen and low in cost.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane fuel cell (PEMFC) technology, and particularly to a method for testing the durability of proton exchange membranes. Background Technology

[0002] Hydrogen fuel cells are devices that directly convert hydrogen and oxygen into electrical energy through a chemical reaction. Due to their advantages such as being environmentally friendly, having high energy density, low emissions, and fast charging, they are widely used in automobiles, portable devices, stationary power stations, and backup power systems.

[0003] The membrane electrode assembly (MEA) is the core component of a hydrogen fuel cell. It typically consists of the following parts: a proton exchange membrane (PEM), a catalyst layer, and a gas diffusion layer.

[0004] In membrane electrode assemblies (MEAs), the proton exchange membrane plays a crucial role. It not only serves as a proton conduction medium and an electron insulation medium, but also isolates the fuel from the oxidant. Therefore, the durability of the proton exchange membrane is decisive for the durability of fuel cells and is one of the main factors restricting the durability of fuel cells.

[0005] Proton exchange membranes are primarily made of polymer materials, with perfluorosulfonic acid (PFSA) membranes being the most common. Currently, the three main methods for evaluating the durability of proton exchange membranes are as follows:

[0006] Method 1: The mechanical durability of the proton exchange membrane was tested using a wet-dry cycle test, consisting of 20,000 cycles at 4-minute intervals, with a test period of 56 days.

[0007] Method 2: The chemical durability of the proton exchange membrane was tested using open-circuit voltage for 500 hours, with a test cycle of 21 days.

[0008] Method 3: Proton exchange membrane chemical / mechanical durability test, 20,000 cycles, one cycle every 75 seconds, test period is 18 days.

[0009] The drawback of the above testing method is that:

[0010] Methods 1 through 3 all test membrane electrodes, which include not only the degradation of the proton exchange membrane, but also the degradation of the anode and cathode catalyst layers and the gas diffusion layer (carbon paper), and therefore cannot truly reflect the degradation of the proton exchange membrane. Summary of the Invention

[0011] In view of this, the present invention aims to provide a proton exchange membrane durability testing method that can more accurately reflect the durability performance of the proton exchange membrane.

[0012] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0013] A method for testing the durability of a proton exchange membrane includes:

[0014] Coatings are applied to both sides of the proton exchange membrane;

[0015] Thin film layers are attached to the outer sides of the coatings on both sides to prepare a single cell;

[0016] The single cell was subjected to durability testing using a fuel cell testing platform.

[0017] The coating includes substances that accelerate the chemical degradation of the proton exchange membrane.

[0018] Furthermore, the components of the substance contain hydrogen peroxide.

[0019] Furthermore, the substance is prepared by mixing hydrogen peroxide gel and ferrous ammonium sulfate.

[0020] Furthermore, the thin film layer is made of polytetrafluoroethylene.

[0021] Furthermore, the thickness of the thin film layer on one side is 2μm-6μm, the porosity is 20%-50%, and the pore size is 0.05μm-0.5μm;

[0022] The thickness of the thin film layer on the other side is 8μm-15μm, the porosity is 40%-70%, and the pore size is 0.1μm-1μm.

[0023] Furthermore, the durability test of the single cell using the fuel cell testing platform includes:

[0024] The single battery is installed into the fuel cell test platform;

[0025] The single battery is subjected to a cycle test according to a preset number of cycles;

[0026] Each cycle test includes introducing gas into both sides of the single cell according to a preset strategy.

[0027] Furthermore, the gas used is air or nitrogen; and / or,

[0028] The preset number of cycles is 2000-2500.

[0029] Furthermore, the preset strategy includes introducing gas under preset conditions to both sides of the single cell in a series of sequential steps.

[0030] The ventilation time for each step is 25-35 seconds. The preset conditions include the pressure, temperature and humidity of the gas, and at least one of the preset conditions is different between different steps.

[0031] Furthermore, before coating both sides of the proton exchange membrane, the testing method also includes performing a first performance test on the proton exchange membrane.

[0032] After performing durability testing on the single cell using the fuel cell testing platform, the testing method further includes:

[0033] The thin film layer and coating on both sides of the single cell were removed, and the proton exchange membrane was cleaned and dried before a second performance test was performed.

[0034] By comparing the test results of the first performance test and the second performance test, it is determined whether the durability performance of the proton exchange membrane is qualified.

[0035] Furthermore, the testing methods for the first performance test and the second performance test are the same, and both the first performance test and the second performance test include at least one of ion exchange equivalent testing, proton conductivity testing, and gravimetric testing; and / or,

[0036] The cleaning of the proton exchange membrane includes sequential cleaning with deionized water and ultrasonic cleaning, and the drying of the proton exchange membrane includes oven drying.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] The proton exchange membrane durability testing method described in this invention tests the durability of a single cell after proton exchange membrane processing, rather than testing the membrane electrode assembly. Compared to existing methods that use membrane electrodes to test proton exchange membrane durability, this method excludes the decay of the anode and cathode catalyst layers and the gas diffusion layer, thus providing a more accurate reflection of the proton exchange membrane's durability. This method is simple to operate, convenient, practical, requires no hydrogen, and is low-cost. The coating includes substances that accelerate the chemical degradation of the proton exchange membrane, which helps to shorten the testing cycle.

[0039] Furthermore, the material contains hydrogen peroxide, which is more direct than existing methods that generate hydrogen peroxide from the anode and cathode catalytic layers. This method accelerates the chemical degradation of the proton exchange membrane, thus shortening the testing cycle. The material is made of hydrogen peroxide gel and ferrous ammonium sulfate, which not only adheres well to the surface of the proton exchange membrane, but also, because the hydrogen peroxide gel contains hydrogen peroxide (H₂O₂), eliminates the need for a chemical reaction to generate hydrogen peroxide as in membrane electrodes, thereby significantly accelerating the chemical degradation of the proton exchange membrane.

[0040] Specifically, the coated hydrogen peroxide gel can simulate the H2O2 generated by the chemical reaction in the fuel cell, which then decomposes to produce free radicals (HO·). The hydrogen peroxide in the hydrogen peroxide gel can be used directly to generate free radicals (HO·), which can accelerate the chemical degradation of the proton exchange membrane. In other words, it can simulate the attack launched by free radicals on the vulnerable parts of the proton membrane in the membrane electrode.

[0041] The main function of adding ferrous ammonium sulfate is to provide ferrous ions. Under the catalysis of ferrous ions, hydrogen peroxide can promote the generation of hydroxyl radicals (HO·), which is beneficial to simulate the attack of free radicals on vulnerable sites of the proton membrane in the membrane electrode.

[0042] In addition, the thin film layer is made of polytetrafluoroethylene, which can simulate the anode and cathode catalyst layers, providing support for the proton exchange membrane and the coated hydrogen peroxide gel, thus facilitating smooth testing. Air or nitrogen is introduced during the test, which is cost-effective and can better simulate the gas pressure experienced by the proton exchange membrane in the membrane electrode.

[0043] Furthermore, limiting the preset conditions, including gas pressure, temperature, and humidity, can effectively simulate the operating conditions of the proton exchange membrane in the membrane electrode assembly (MEA), thus improving the accuracy of durability testing. Ensuring that at least one preset condition differs between different steps allows for the simulation of varying operating conditions of the proton exchange membrane within the MEA, thereby providing a more realistic representation of most of the MEA's operating conditions. Performance tests on the proton exchange membrane are conducted before and after the durability test. Comparing the results of the two tests determines whether the proton exchange membrane's durability performance is up to standard. Specific data is used to evaluate the proton exchange membrane's durability performance, resulting in reliable and highly accurate evaluation results.

[0044] Both the first and second performance tests must include at least one of the following: ion exchange equivalent test, proton conductivity test, and weight test. The more types of performance tests included, the more reliable and accurate the durability performance assessment of the proton exchange membrane will be. Cleaning the proton exchange membrane, including deionized water cleaning and ultrasonic cleaning, can reduce the influence of the coating on the results of the second performance test. Drying the proton exchange membrane saves testing time and prevents residual moisture from the cleaning process from affecting the results of the second performance test. Attached Figure Description

[0045] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0046] Figure 1 This is a schematic diagram illustrating the changes in operating conditions in the proton exchange membrane durability testing method described in this embodiment of the invention. Detailed Implementation

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0048] The present invention will now be described in detail with reference to embodiments.

[0049] This embodiment relates to a proton exchange membrane durability testing method. Its short testing cycle allows for the evaluation of the durability performance of the proton exchange membrane in a short time. Furthermore, the test process does not involve the attenuation of the anode and cathode catalyst layers and the gas diffusion layer, resulting in high test accuracy.

[0050] Based on the above design concept, an exemplary method for proton exchange membrane durability testing in this embodiment includes:

[0051] S1. Coatings are applied to both sides of the proton exchange membrane.

[0052] S2. Thin film layers are attached to the outer sides of the coatings on both sides to prepare a single cell.

[0053] S3. Durability tests on single cells are conducted using a fuel cell testing platform.

[0054] The coating includes substances that accelerate the chemical degradation of the proton exchange membrane.

[0055] In step S1 above, as a preferred embodiment, the composition of the substance contains hydrogen peroxide. Compared with the existing method of generating hydrogen peroxide from the anode and cathode catalyst layers, this method is more direct and helps to accelerate the chemical degradation rate of the proton exchange membrane, thereby shortening the test cycle.

[0056] In a preferred embodiment, the coating material is made of a mixture of hydrogen peroxide gel and ferrous ammonium sulfate. This not only allows for better coating on the surface of the proton exchange membrane, but also, because the hydrogen peroxide gel contains hydrogen peroxide (H2O2), it eliminates the need for a chemical reaction to generate hydrogen peroxide as is required in membrane electrodes, thus accelerating the chemical degradation rate of the proton exchange membrane.

[0057] Specifically, ferrous ammonium sulfate is preferably used at a concentration of 8ppm-12ppm, such as 8ppm, 10ppm, 12ppm, etc., and preferably 10ppm. It should be noted that the coating component contains hydrogen peroxide because: in a fuel cell, O2 at the cathode or anode reacts via a two-electron pathway to generate hydrogen peroxide (H2O2), and further decomposition of hydrogen peroxide produces free radicals HO·.

[0058] The main reaction process is as follows:

[0059] At the cathode: H2 + O2 → H2O2

[0060] At the anode: H2 + O2 → H2O2

[0061] 2H + +O2+2e - →H2O2

[0062] 1 / 2H2O2→HO·

[0063] The generated free radicals can effectively attack the vulnerable sites of the proton exchange membrane, leading to the chemical degradation of the proton exchange membrane. At the microscopic level, this includes the degradation of the proton exchange membrane main chain, the degradation of the side chains, and the degradation of sulfonate groups.

[0064] Specifically, the coated hydrogen peroxide gel is mainly used to simulate the H2O2 generated by the chemical reaction in fuel cells, which then decomposes to produce free radicals. The hydrogen peroxide in the hydrogen peroxide gel directly generates free radicals (HO·), which can simulate the attack of free radicals on vulnerable parts of the proton exchange membrane in membrane batteries, thereby accelerating the chemical degradation of the proton exchange membrane. This proton exchange membrane durability test method is helpful in distinguishing the quality of the proton exchange membrane durability.

[0065] The main function of adding ferrous ammonium sulfate is to provide ferrous ions. Under the catalysis of ferrous ions, hydrogen peroxide can promote the generation of hydroxyl radicals (HO·), which is beneficial to simulate the attack of free radicals on vulnerable sites of the proton membrane in the membrane electrode.

[0066] In this embodiment, the amounts of hydrogen peroxide gel and ferrous ammonium sulfate are directly proportional. Taking a preferred concentration of 10 ppm ferrous ammonium sulfate as an example, generally 0.02 g to 0.03 g of ferrous ammonium sulfate needs to be mixed for every 1 ml of hydrogen peroxide gel. Specifically, for example, when the amount of hydrogen peroxide gel is 1 ml, the amount of 10 ppm ferrous ammonium sulfate is 0.02 g to 0.03 g, and it can be 0.02 g, 0.025 g, 0.03 g, etc. In the following embodiment, when the amount of hydrogen peroxide gel is 4 ml, the amount of 10 ppm ferrous ammonium sulfate is 0.08 g to 0.12 g. Specifically, the amount of ferrous ammonium sulfate in this case can be 0.08 g, 0.10 g, 0.12 g, etc.

[0067] It should be understood that the coating material is made of hydrogen peroxide gel and ferrous ammonium sulfate because, after being coated on the proton exchange membrane, it can be evenly adhered to both sides of the proton exchange membrane, which is beneficial for better proton exchange membrane durability testing. In addition to hydrogen peroxide gel and ferrous ammonium sulfate, the coating material can also be other components containing hydrogen peroxide. For example, using only hydrogen peroxide gel is also possible.

[0068] It should be noted that, as a preferred embodiment, the surface area of ​​the proton exchange membrane is directly proportional to the amount of coating material used, and generally, the surface area of ​​the proton exchange membrane is [amount missing] per 1 cm [area missing]. 2 The amount of material coated on the surface area can be between 0.072 ml and 0.088 ml. In practical applications, for example, on a proton exchange membrane with a surface area of ​​100 cm²... 2 The amount of coating material used is 7.2 ml to 8.8 ml, such as 7.2 ml, 8 ml, or 8.8 ml. In the examples described below, the surface area of ​​the proton exchange membrane is 25 cm². 2 When applying the coating, the amount of the substance used is 1.8ml-2.2ml, such as 1.8ml, 2ml, or 2.2ml.

[0069] To construct a single-cell structure and thus better simulate the operating conditions of a proton exchange membrane in a fuel cell, a preferred embodiment uses a thin film layer made of polytetrafluoroethylene (PTFE). In this embodiment, the thin film layer can simulate the anode and cathode catalyst layers, providing support for the proton exchange membrane and the coated hydrogen peroxide gel, facilitating successful testing.

[0070] In the durability testing of the proton exchange membrane, in order to more realistically simulate the working conditions of the proton exchange membrane in a fuel cell, as a preferred embodiment, the thickness of the thin film layer on one side is 2μm-6μm, such as 2μm, 3μm, 5μm, 6μm, etc., the porosity is 20%-50%, such as 20%, 30%, 40%, 50%, and the pore size is 0.05μm-0.5μm, such as 0.05μm, 0.15μm, 0.25μm, 0.3μm, 0.4μm, 0.5μm. The thin film layer on this side serves as the thin film layer of the anode and is used to simulate the anode catalyst layer.

[0071] The thickness of the thin film layer on the other side is 8μm-15μm, such as 8μm, 10μm, 12μm, 15μm, etc., with a porosity of 40%-70%, such as 40%, 50%, 60%, 70%, and a pore size of 0.1μm-1μm, such as 0.1μm, 0.33μm, 0.5μm, 0.7μm, 0.8μm, 1μm. This thin film layer on this side serves as the cathode thin film layer, used to simulate the cathode catalyst layer.

[0072] It should be noted that during the operation of a fuel cell system, factors affecting the proton exchange membrane also include: 1. Imbalances in gas flow and pressure can lead to pressure differential changes, especially during startup, shutdown, or load changes. 2. Rapid temperature changes can also cause thermal expansion and contraction of materials. Since the proton exchange membrane and electrode materials have different coefficients of thermal expansion, this can potentially lead to deformation and damage to the proton exchange membrane.

[0073] These factors can subject the proton exchange membrane to tensile, compressive, or shear stresses, which may lead to mechanical damage such as cracks, perforations, or delamination over long periods. However, existing methods one through three do not consider the degradation of the proton exchange membrane caused by changes in pressure differential and temperature. Furthermore, methods two and three mentioned in the background section require the continuous flow of hydrogen and air during the test, resulting in high testing costs. While method one uses air throughout the test, its long testing cycle also leads to high costs.

[0074] In this application, to more realistically simulate the operating conditions of the proton exchange membrane in a fuel cell, as a preferred embodiment, the durability test of a single cell using a fuel cell test platform specifically includes: installing the single cell into the fuel cell test platform and performing a cycle test on the single cell according to a preset number of cycles. Each cycle test includes introducing gas to both sides of the single cell according to a preset strategy.

[0075] It should be noted that during the test, gas is introduced through both sides of the product under test. Air or nitrogen is preferred as the gas. Compared with the existing test method that requires the introduction of hydrogen, the cost of using air or nitrogen is lower, and it can better simulate the actual working conditions of the proton exchange membrane in the membrane electrode.

[0076] In this embodiment, in order to select a proton exchange membrane with better performance according to the proton exchange membrane durability test method, as a preferred implementation method, the preset number of cycles is 2000-2500 times, such as 2000 times, 2100 times, 2250 times, 2400 times, or 2500 times.

[0077] In a preferred embodiment, the aforementioned preset strategy includes introducing gases under preset conditions to both sides of a single cell in multiple sequential steps. To obtain more accurate evaluation results, as a preferred embodiment, the gas introduction time for each step is 25-35 seconds, such as 25 seconds, 30 seconds, or 35 seconds, which facilitates better testing of the proton exchange membrane's durability.

[0078] It should be noted that in a real fuel cell, there will be changes in pressure, temperature, and humidity, and these changes will all affect the durability of the proton exchange membrane. Therefore, as a preferred implementation method, the preset conditions for durability testing include gas pressure, temperature, and humidity, and at least one preset condition must be different between different steps. For details, please refer to the preset conditions in the eight steps below.

[0079] In this embodiment, the preset test conditions include gas pressure, temperature, and humidity, which facilitates a realistic simulation of the proton exchange membrane's operating conditions, thereby improving the accuracy of the proton exchange membrane's durability performance evaluation. However, it should be understood that limiting only one or two of the gas pressure, temperature, and humidity during the proton exchange membrane durability test is also feasible.

[0080] Furthermore, at least one preset condition differs between the different steps, which can better simulate the operating conditions of the proton exchange membrane in the membrane electrode, thus improving the accuracy of durability testing. The preset conditions in the eight steps specified below are quite close to the operating conditions of the proton exchange membrane in the membrane electrode, and can realistically reflect most of the operating conditions of the proton exchange membrane in the membrane electrode. It should be understood that the number of steps is not limited to eight; it can certainly be other numbers, such as three, five, ten, etc.

[0081] It should be noted that performing cycle tests on a single cell according to a preset number of cycles, and ensuring that at least one preset condition is different between different steps, is mainly to provide a more stringent testing environment for the proton exchange membrane. Only by selecting a proton exchange membrane in this way can its durability performance be better.

[0082] It should be understood that, in addition to making multiple steps repeat sequentially, multiple steps can also be performed regularly or irregularly, or the experiment can be conducted sequentially without repeating the steps. This will be explained in detail in the following description.

[0083] As a preferred embodiment, the preset conditions for several steps include:

[0084] The first step involves setting the intake pressure on one side to 160 kPa and the intake pressure on the other side to 150 kPa, with the intake temperature on both sides at 60°C and the humidity on both sides at 0%.

[0085] In the second step, the intake pressure on one side is 160 kPa, the intake pressure on the other side is 110 kPa, the intake temperature on both sides is 60°C, and the intake humidity on both sides is 0%.

[0086] The third step involves setting the intake pressure on one side to 160 kPa and the intake pressure on the other side to 150 kPa, with the intake temperature on both sides at 60°C and the humidity on both sides at 100%.

[0087] The fourth step involves an intake pressure of 160 kPa on one side and 110 kPa on the other side, with both intake temperatures at 60°C and both intake humidity at 100%.

[0088] The fifth step involves setting the intake pressure on one side to 160 kPa and the intake pressure on the other side to 150 kPa, with both intake temperatures at 90°C and both intake humidity levels at 0%.

[0089] The sixth step involves setting the intake pressure on one side to 160 kPa and the intake pressure on the other side to 110 kPa, with both intake temperatures at 90°C and both intake humidity at 0%.

[0090] The seventh step involves an intake pressure of 160 kPa on one side and 150 kPa on the other side, with both intake temperatures at 90°C and both intake humidity at 100%.

[0091] The eighth step involves an intake pressure of 160 kPa on one side and 110 kPa on the other side, with both intake temperatures at 90°C and both intake humidity at 100%.

[0092] In the eight steps above, the intake pressure on one side represents the intake pressure on the anode side, and the intake pressure on the other side represents the intake pressure on the cathode side.

[0093] It should be noted that this embodiment is illustrated using multiple steps, including the eight steps mentioned above. These eight steps are performed sequentially, with each step having a ventilation time of, for example, 30 seconds. The process is then repeated from the beginning, with the number of cycles as described above.

[0094] It should be understood that the eight steps mentioned above in this embodiment are only for the purpose of more realistically simulating the working condition of the proton exchange membrane in the fuel cell. It should also be understood that the parameters of each step above can be adjusted according to actual needs.

[0095] Preferably, the pressure of the gas on one side is 140 kPa-180 kPa, such as 140 kPa, 150 kPa, 160 kPa, 170 kPa, or 180 kPa, and the pressure of the gas on the other side is 100 kPa-160 kPa, such as 100 kPa, 110 kPa, 130 kPa, 150 kPa, or 160 kPa.

[0096] The preferred temperature of the gases on both sides is 50℃-70℃, but it can be 50℃, 60℃, 70℃, etc. It should be understood that the temperatures of the gases on both sides can be the same or different. The preferred humidity of the gases on both sides is 0% or 100%. It should be understood that the humidity of the gases on both sides can be the same or different.

[0097] It should also be noted that the above explanation is based on the example of eight steps being performed in a sequential loop. In addition, the eight steps can also be performed irregularly. For example, four steps can be performed in a loop for 2250 times, and then the other four steps can be performed in a loop for 2250 times. Alternatively, after the first step is performed 2250 times, the other steps can be performed in the same manner.

[0098] It should be understood that the eight steps are carried out in a sequential cycle, which makes the test environment for proton exchange membrane durability testing more stringent and helps to obtain more accurate durability test results for proton exchange membranes.

[0099] In order to accurately determine the durability of the proton exchange membrane, as a preferred embodiment, the method further includes performing a first performance test on the proton exchange membrane before coating both sides of the proton exchange membrane.

[0100] After conducting durability tests on a single cell using a fuel cell testing platform, the method further includes removing the thin film layers and coatings from both sides of the single cell, followed by cleaning and drying to obtain a clean proton exchange membrane, and then performing a second performance test on the proton exchange membrane. The results of the first and second performance tests are then compared to determine whether the proton exchange membrane's durability is up to standard.

[0101] Specifically, the test results of the first and second performance tests are compared, including the calculation of the test result value based on the test results of the first and second performance tests, and the proton exchange membrane is deemed to have passed the durability test when the test result value is less than the set test result value.

[0102] The performance of the proton exchange membrane is tested before and after the durability test. The durability performance of the proton exchange membrane is determined based on the test results. The specific data can be used to evaluate the durability performance of the proton exchange membrane, and the evaluation results are reliable and highly accurate.

[0103] It should be noted that, in the preferred embodiment, the testing methods for the first and second performance tests are the same, and both the first and second performance tests include at least one of ion exchange equivalent testing, proton conductivity testing, and gravimetric testing. It should be understood that regardless of the type of test, the calculation methods are similar; therefore, the following explanation uses the ion exchange equivalent test as an example.

[0104] For example, the first performance test is an ion exchange equivalent test, and the second performance test is also an ion exchange equivalent test. The equivalent difference between the two tests is calculated, and then the equivalent difference is compared with the set equivalent difference. If the calculated equivalent difference is less than the set equivalent difference, the proton exchange membrane is deemed to have passed the durability performance test.

[0105] Alternatively, calculate the equivalent difference between the two tests, divide the equivalent difference by the equivalent value of the first performance test to obtain the equivalent change percentage, compare the equivalent change percentage with the set equivalent change percentage, and determine that the proton exchange membrane durability performance test is qualified when the equivalent change percentage is less than the set equivalent change percentage.

[0106] When both the first and second performance tests are proton conductivity tests or weight tests, the calculation method is the same as that for ion exchange equivalent tests. This embodiment will not be described in detail. It should be understood that the more types of tests there are, the more reliable the final evaluation results will be.

[0107] Furthermore, the proton exchange membrane durability test method in this embodiment uses existing equipment, specifically an existing fuel cell test platform. The test method refers to the existing membrane electrode test method, which will not be described in detail in this embodiment.

[0108] In this embodiment, the treatment of the proton exchange membrane includes cleaning and drying. The cleaning process includes sequential cleaning with deionized water and ultrasonic cleaning. Preferably, the membrane is first cleaned multiple times with deionized water, followed by multiple ultrasonic cleanings. Each ultrasonic cleaning session lasts between 20 and 40 minutes, such as 20, 30, or 40 minutes. The drying process includes oven drying. The drying temperature is between 50°C and 70°C, such as 50°C, 60°C, or 70°C, and the drying time is between 18 and 30 hours, such as 18 hours, 24 hours, or 30 hours.

[0109] The proton exchange membrane durability testing method in this embodiment tests the durability of a single cell after proton exchange membrane treatment, rather than testing the membrane electrode. In other words, the single cell in this embodiment replaces the existing membrane electrode for proton exchange membrane durability testing. Compared to existing testing methods that use membrane electrodes to test proton exchange membrane durability, this method does not include the attenuation of the anode and cathode catalyst layers or the gas diffusion layer, thus providing a more accurate reflection of the proton exchange membrane's durability. This method is simple to operate, convenient, practical, requires no hydrogen, and has lower costs.

[0110] The proton exchange membrane durability testing method of this embodiment takes approximately 150 hours, or about 6.25 days. Compared with the existing testing methods that take 18 to 56 days, the proton exchange membrane durability testing method of this embodiment significantly shortens the time. When conducting durability tests on multiple proton exchange membranes, it is beneficial to quickly evaluate the durability performance of the proton exchange membranes, thereby saving time and labor costs.

[0111] To verify the effectiveness of the proton exchange membrane durability test method in this embodiment, three different batches of proton exchange membrane samples were selected for durability evaluation. Each proton exchange membrane was 5 cm long and 5 cm wide.

[0112] For ease of description of the experimental process, the three proton exchange membrane samples will be referred to as Sample 1, Sample 2, and Sample 3 in the following text.

[0113] Before testing each sample, Ew testing, proton conductivity testing, and proton exchange membrane weight measurement were performed on each sample. It should be noted that Ew... W Tests, proton conductivity tests, and proton membrane weight are characterization methods used to characterize proton membrane degradation.

[0114] E W In the Equivalent Weight (EW) test results, the EW value represents the mass of dry film contained per mole of ionic groups (sulfonate groups -SO3H). Changes in the EW value can be used to characterize the degree of degradation of sulfonate groups during the durability process.

[0115] In the results of proton conductivity testing, proton conductivity is used to characterize the ability to conduct protons. Its value is used to measure the proton conduction capacity of the proton membrane. The change in proton conductivity before and after the test can be understood as the degree of damage to the proton channel.

[0116] The difference in weight of the proton exchange membrane before and after the test can be used to characterize the degree of degradation of the main chain and side chains of the proton exchange membrane.

[0117] After selecting the proton exchange membrane samples to be evaluated, a mixture of hydrogen peroxide gel and ferrous ammonium sulfate was coated on both sides of Sample 1, Sample 2 and Sample 3, respectively, with a coating amount of 2 ml on each side of each sample.

[0118] In this embodiment, when the amount of hydrogen peroxide gel used is 4 ml, the amount of 10 ppm ferrous ammonium sulfate used is 0.1 g. Since three samples need to be coated, the amount of hydrogen peroxide gel used is 12 ml, and the amount of 10 ppm ferrous ammonium sulfate used is 0.3 g.

[0119] Then, PTFE (Polytetrafluoroethylene) thin film layers were attached to the outer side of the coating on both sides of each sample to prepare a single cell.

[0120] One side has a PTFE film thickness of 5 μm, a porosity of approximately 40%, and a pore size of approximately 0.4 μm, simulating the anode catalyst layer. The other side has a PTFE film thickness of 10 μm, a porosity of approximately 60%, and a pore size of approximately 0.5 μm, simulating the cathode catalyst layer. The amount of coating material and the parameters of the PTFE film layers on both sides of each sample are consistent to prevent these parameters from affecting the durability test results.

[0121] Next, using an existing fuel cell testing platform, gas (air or nitrogen can be used; air is used in this embodiment) is introduced into the anode and cathode. The steps are performed according to Table 1 below, or as per the instructions. Figure 1 The volume of air on both the yin and yang poles is 1000 sccm.

[0122] Table 1:

[0123]

[0124]

[0125] After completing the above eight steps in sequence, a performance test is performed. The durability test is completed after 2250 cycles. Then, each sample is processed to obtain a clean proton exchange membrane.

[0126] Specifically, the samples were first rinsed with deionized water three times, and then the surface of the proton exchange membrane was observed to ensure there were no obvious impurities remaining. After confirming that there were no obvious impurities remaining on the surface of the proton exchange membrane, each sample was placed in a beaker containing deionized water and ultrasonically cleaned three times, 30 minutes each time. After cleaning, each sample was dried at 60°C for 24 hours.

[0127] Subsequently, each sample underwent Ew testing, proton conductivity testing, and proton exchange membrane weight measurement to compare parameter changes before and after durability testing.

[0128] The test results for samples one through three above are as follows.

[0129] Table 2: Ew Test Results Before and After Durability Testing

[0130] Durable before Ew After durability Ew Sulfonate change rate Sample 1 1102g / mol 1380g / mol 25.23％ Sample 2 1203g / mol 1467g / mol 21.95％ Sample 3 818g / mol 1105g / mol 35.09％

[0131] Table 3: Proton conductivity of PEM (proton exchange membrane) before and after durability testing (25℃, 50%RH)

[0132]

[0133]

[0134] Table 4: Weight of PEM (Proton Exchange Membrane) before and after durability testing

[0135] Weight before durability Weight after durability weight loss rate Sample 1 36.35mg 33.39mg 8.14％ Sample 2 62.52mg 57.99mg 7.23％ Sample 3 28.94mg 25.36mg 12.36％

[0136] After numerous tests on various proton exchange membranes, the inventors ultimately set the following reference values: Ew test change rate of 25%, proton conductivity change rate of 75%, and weight loss rate of 10%. It should be understood that these reference values ​​can be set according to actual needs and can also be set to other values.

[0137] By comparing the above data with the set reference values, the results show that the durability performance of Sample 2 is better than that of Sample 1 and Sample 3. If only the weight of the proton exchange membrane is tested, both Sample 1 and Sample 2 are qualified. However, when Ew test and proton conductivity test are performed at the same time, Sample 1 is unqualified. The more types of tests, the more reliable the evaluation results.

[0138] The proton exchange membrane durability testing method of this invention can be used to test and evaluate the durability performance of proton exchange membranes. When evaluating the durability performance of different proton exchange membranes, it can distinguish the superiority or inferiority of their durability performance in a relatively short time. This proton exchange membrane durability testing method can significantly shorten the testing time, and the method is simple, efficient, and highly practical.

[0139] The proton exchange membrane (PEM) durability testing method in this embodiment is centered on the PEM. Unlike traditional PEM durability evaluation methods, which involve coating a catalyst layer and using carbon paper, this durability testing method directly uses the PEM to simulate the chemical degradation caused by free radical attack on the PEM and the mechanical damage caused by humidity changes. This avoids the influence of the degradation of the anode and cathode catalyst layers and carbon paper on the test results, resulting in more accurate test results. In addition, the test method in this embodiment introduces pressure difference and temperature changes, which more closely resembles the actual operation of the PEM in a fuel cell.

[0140] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for testing the durability of a proton exchange membrane, characterized in that, The testing method includes: Coatings are applied to both sides of the proton exchange membrane; Thin film layers are attached to the outer sides of the coatings on both sides to prepare a single cell; The single cell was subjected to durability testing using a fuel cell testing platform. The coating includes substances that accelerate the chemical degradation of the proton exchange membrane.

2. The proton exchange membrane durability testing method according to claim 1, characterized in that: The substance contains hydrogen peroxide in its components.

3. The proton exchange membrane durability testing method according to claim 2, characterized in that: The substance is made by mixing hydrogen peroxide gel and ferrous ammonium sulfate.

4. The proton exchange membrane durability testing method according to claim 1, characterized in that: The thin film layer is made of polytetrafluoroethylene.

5. The proton exchange membrane durability testing method according to claim 1, characterized in that: The thickness of the thin film layer on one side is 2μm-6μm, the porosity is 20%-50%, and the pore size is 0.05μm-0.5μm; The thickness of the thin film layer on the other side is 8μm-15μm, the porosity is 40%-70%, and the pore size is 0.1μm-1μm.

6. The proton exchange membrane durability testing method according to claim 1, characterized in that: The durability test of the single cell using a fuel cell testing platform includes: The single battery is installed into the fuel cell test platform; The single battery is subjected to a cycle test according to a preset number of cycles; Each cycle test includes introducing gas into both sides of the single cell according to a preset strategy.

7. The proton exchange membrane durability testing method according to claim 6, characterized in that: The gas is air or nitrogen; and / or, The preset number of cycles is 2000-2500.

8. The proton exchange membrane durability testing method according to claim 6, characterized in that: The preset strategy includes introducing gas under preset conditions to both sides of the single cell in multiple sequential steps. The ventilation time for each step is 25-35 seconds. The preset conditions include the pressure, temperature and humidity of the gas, and at least one of the preset conditions is different between different steps.

9. The proton exchange membrane durability testing method according to any one of claims 1-8, characterized in that: Before coating both sides of the proton exchange membrane, the test method further includes: The proton exchange membrane was subjected to its first performance test; After performing durability testing on the single cell using the fuel cell testing platform, the testing method further includes: The thin film layer and coating on both sides of the single cell were removed, and the proton exchange membrane was cleaned and dried before a second performance test was performed. By comparing the test results of the first performance test and the second performance test, it is determined whether the durability performance of the proton exchange membrane is qualified.

10. The proton exchange membrane durability testing method according to claim 9, characterized in that: The first performance test and the second performance test use the same testing methods, and both the first performance test and the second performance test include at least one of ion exchange equivalent testing, proton conductivity testing, and gravimetric testing; and / or, The cleaning of the proton exchange membrane includes sequential cleaning with deionized water and ultrasonic cleaning, and the drying of the proton exchange membrane includes oven drying.

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