Limit current testing method

Abstract

The invention discloses a limiting current testing method. The method comprises the following steps: firstly, providing an activation environment; in the activation environment, the membrane electrode of the fuel cell is activated based on the activation voltage variable load process, and the activated membrane electrode of the fuel cell is obtained; then a test environment is provided, in the test environment, current density test is carried out on the activated membrane electrode of the fuel cell, a current density test result is obtained, and the current density test result comprises limiting current density; according to the method, the membrane electrode of the fuel cell is activated before testing, so that the real performance of the membrane electrode is excited, the accuracy of a current density testing result is improved, and meanwhile, the membrane electrode is also protected.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a limiting current testing method. Background Art

[0002] As a new type of fuel cell, proton exchange membrane fuel cell has the advantages of high energy conversion efficiency, completely green and pollution-free, fast response speed, low temperature safety, etc. It is the key direction of the development of the next generation of new energy vehicles. The membrane electrode is the core power generation component in the fuel cell, and its performance is judged by comparing the voltage at a specific electric density point through polarization curve testing. In the current membrane electrode testing, membrane electrodes with a specific active area can usually only be tested in a test bench within a suitable range. Its structural design will greatly affect the performance of the membrane electrode, and the results are also affected by factors such as fixture assembly, flow channel, carbon paper, etc., resulting in the inability to obtain accurate membrane electrode performance test results. Summary of the invention

[0003] In view of the above problems, the object of the present invention is to provide a limiting current test method with high accuracy, which is applied to the membrane electrode of a fuel cell. The method comprises:

[0004] Providing an activation environment; the activation environment represents the environmental conditions for activating the membrane electrode of the fuel cell;

[0005] In the activation environment, the membrane electrode of the fuel cell is activated based on an activation voltage variation process to obtain an activated membrane electrode of the fuel cell; the activation voltage variation process varies the activation voltage of the fuel cell based on preset activation voltage variation information and takes the open circuit voltage of the fuel cell as a starting point; the preset activation voltage variation information represents the relationship between activation voltage and time;

[0006] Providing a test environment; the test environment represents the environmental conditions for testing the activated membrane electrode of the fuel cell;

[0007] In the test environment, a current density test is performed on the activated membrane electrode of the fuel cell to obtain a current density test result; the current density test result includes a limiting current density.

[0008] In an exemplary embodiment, the activation environment includes an activated anode gas fuel and an activated cathode gas fuel;

[0009] The activated anode fuel gas is hydrogen;

[0010] The activated cathode fuel gas is air.

[0011] In an exemplary embodiment, in the test environment, the current density test is performed on the activated membrane electrode of the fuel cell, and the current density test result is obtained including:

[0012] In the test environment, the activated membrane electrode of the fuel cell is tested based on a test voltage variation process to obtain the current density test result; the test voltage variation process varies the test voltage of the fuel cell according to preset test voltage variation information, taking the open circuit voltage of the fuel cell as the starting point; the preset test voltage variation information represents the relationship between the test voltage and time.

[0013] In an exemplary embodiment, after the current density test is performed on the activated membrane electrode of the fuel cell, the method further comprises:

[0014] providing a purge environment, wherein the purge environment represents an environmental condition for purging the activated membrane electrode of the fuel cell;

[0015] In the purge environment, the activated membrane electrode of the fuel cell is purged.

[0016] In an exemplary embodiment, the test environment includes a test anode gas fuel and a test cathode gas fuel;

[0017] The test anode gas fuel is hydrogen;

[0018] The test cathode gas fuel is a mixed gas of air and nitrogen, and the oxygen mole fraction of the test cathode gas fuel is 0.5-15%.

[0019] In an exemplary embodiment, the test environment includes testing anode intake temperature and testing cathode intake temperature;

[0020] The test anode inlet temperature is 40-90°C;

[0021] The test cathode air inlet temperature is 40-90°C.

[0022] In an exemplary embodiment, the test environment includes testing anode gas flow and testing cathode gas flow;

[0023] The test anode gas flow rate is 1-4 NLPM;

[0024] The test cathode gas flow rate is 2-5 NLPM.

[0025] In an exemplary embodiment, the test environment includes testing anode intake pressure and testing cathode intake pressure;

[0026] The test anode inlet pressure is 0-200 kPa;

[0027] The test cathode air inlet pressure is 0-200 kPa.

[0028] In an exemplary embodiment, the test environment includes: testing anode relative humidity and testing cathode relative humidity;

[0029] The relative humidity of the test anode is 70-100%;

[0030] The relative humidity of the test cathode is 70-100%.

[0031] In an exemplary embodiment, the test environment includes a test fuel cell temperature, and the test fuel cell temperature is 40-90°C.

[0032] An embodiment of the present application discloses a limiting current test method, which includes: first providing an activation environment; in the activation environment, activating the membrane electrode of the fuel cell based on an activation voltage variable load process to obtain the activated membrane electrode of the fuel cell; then providing a test environment, in the test environment, performing a current density test on the activated membrane electrode of the fuel cell to obtain a current density test result, wherein the current density test result includes a limiting current density; the embodiment of the present application activates the membrane electrode of the fuel cell before the test, thereby stimulating the true performance of the membrane electrode, improving the accuracy of the current density test result, and protecting the membrane electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments or prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 is a flow chart of a limiting current testing method provided by an embodiment of the present invention;

[0035] Figure 2 is a graph showing the relationship between activation voltage and time provided by an embodiment of the present invention;

[0036] Figure 3 is a test voltage and time relationship diagram provided by an embodiment of the present invention;

[0037] Figure 4 It is a curve diagram of the relationship between the test voltage and the current density provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0039] As a new type of fuel cell, proton exchange membrane fuel cell has the advantages of high energy conversion efficiency, complete greenness and pollution-free, fast response speed, low temperature safety, etc. It is the key direction of the development of the next generation of new energy vehicles.

[0040] As the core power generation component in fuel cells, the performance of membrane electrodes is evaluated by comparing the voltage at specific electric density points through polarization curve testing. During the testing process, this method is also affected by overpotentials such as ohm, activation, and mass transfer, and may also cause problems such as flooding and insufficient internal gas supply, resulting in the membrane electrode being unable to fully exert its ultimate performance.

[0041] At present, membrane electrode testing is mainly carried out in fuel cell testing equipment and standard fixtures. Membrane electrodes with a specific active area can usually only be tested in a test bench within a suitable range, which limits the comparative exploration of the performance upper limit of the membrane electrode and makes it impossible to compare the performance upper limits of different membrane electrodes. In some standard fixtures, the flow channel is usually also specified, and its structural design will greatly affect the performance of the membrane electrode, and the results are also affected by factors such as fixture assembly, flow channel, carbon paper, etc.

[0042] Therefore, in addition to polarization testing, some testing methods are also needed to eliminate the impact of fixtures and flow channels on the actual performance of membrane electrodes, in order to reflect the impact of different slurries and processes on their performance during the development of membrane electrodes. At the same time, a testing method is also needed to support in-depth exploration of membrane electrode performance.

[0043] The present application provides a limiting current test method, which is applied to the membrane electrode of a fuel cell. Figure 1 , Figure 1 The present invention is a flow chart of a limiting current testing method, the method comprising the following steps:

[0044] Step S1: providing an activation environment; the activation environment represents the environmental conditions for activating the membrane electrode of the fuel cell.

[0045] Specifically, in the activation environment, the activated anode air intake temperature, the activated cathode air intake temperature and the activated fuel cell temperature are all in the range of 75 to 90°C, wherein the activated anode air intake temperature, the activated cathode air intake temperature and the activated fuel cell temperature can be set to the same or different values ​​during the same activation; the activated cathode relative humidity and the activated anode relative humidity can be set to 70 to 100%, wherein the activated cathode relative humidity and the activated anode relative humidity can be set to the same or different values ​​during the same activation. Specifically, since there is a relationship between the fuel cell temperature, the dew point temperature and the relative humidity, it should be noted that the fuel cell temperature includes the activated fuel cell temperature and the test fuel cell temperature, the dew point temperature includes the activation dew point temperature and the test dew point temperature, and the relative humidity includes the activated cathode relative humidity, the activated anode relative humidity, the test cathode relative humidity and the test anode relative humidity. When the set values ​​of the activated fuel cell temperature and the activated relative humidity are fixed, wherein the activated relative humidity includes the activated cathode relative humidity and the activated anode relative humidity, the activated dew point temperature can be directly determined by calculating the correlation formula; the activated anode inlet pressure and the activated cathode inlet pressure are both 150-200 kPa (gauge pressure), wherein the activated anode inlet pressure and the activated cathode inlet pressure can be the same or different when set at the same activation; regarding the activation gas flow setting, the activation gas flow refers to the gas flow of the activated gas fuel, and the activated anode stoichiometric ratio is 2-4, and the activated cathode stoichiometric ratio is 3-5. By setting the activation relative humidity between 70% and 100%, it can be ensured that the membrane electrode of the fuel cell is fully moistened, and sufficient water flow is used to form a good mass transfer network; by selecting a suitable activation cell temperature and activation inlet temperature, it can be ensured that the catalyst activity can be well released, wherein the activation inlet temperature includes the activated anode inlet temperature and the activated cathode inlet temperature. In addition, it should be noted that in order to ensure the activation effect, the value of the activation fuel cell temperature setting is required to be greater than or equal to the value of the test fuel cell temperature setting. In the embodiment of the present application, the activation environment parameters other than the activation fuel cell temperature can be set within their respective activation ranges without any other requirements.

[0046] Step S2: In an activation environment, the membrane electrode of the fuel cell is activated based on an activation voltage variation process to obtain an activated membrane electrode of the fuel cell; the activation voltage variation process varies the activation voltage of the fuel cell based on preset activation voltage variation information and takes the open circuit voltage of the fuel cell as a starting point; the preset activation voltage variation information represents the relationship between the activation voltage and time.

[0047] Specifically, the activation voltage can be changed by using multiple rounds of voltage change. For example, see Figure 2 , Figure 2is a graph showing the relationship between activation voltage and time. Specifically, in a multi-round variable load mode for activation voltage, with the open circuit voltage (OCV) of the fuel cell as the starting point, the first round of activation voltage reduction slope is 0.2V / min, and stays at 0.8V, 0.7V, and 0.6V for 30s each, reaching activation voltage V1, that is, staying at 0.5V for 3min, the activation voltage increase slope is 0.2V / min, and stays at 0.6V, 0.7V, 0.8V, and OCV for 30s each; the second round of activation voltage reduction slope is 0.2V / min, and stays at 0.8V, 0.7V, 0.6V, and 0.5V for 30s each, reaching activation voltage V2 , that is, stay at 0.4V for 3min, the activation voltage increase slope is 0.2V / min, and stay at 0.5V, 0.6V, 0.7V, 0.8V, and OCV for 30s; the third round of activation voltage reduction slope is 0.2V / min, and stay at 0.8V, 0.7V, 0.6V, 0.5V, 0.4V for 30s, reaching the activation voltage V3, that is, stay at 0.3V for 3min, the activation voltage increase slope is 0.2V / min, and stay at 0.4V, 0.5V, 0.6V, 0.7V, 0.8V, OCV for 30s; the fourth round of load change is the same as the third round, and the load change steps are carried out for a total of four rounds. The first three rounds increase the load change intensity in turn to avoid the high load operation of the membrane electrode of the fuel cell before it is fully activated, causing the catalyst layer to agglomerate. By using a gradient variable load method similar to the variable load test voltage to change the activation voltage, the membrane electrode of the fuel cell is protected while quickly stimulating the true performance of the membrane electrode of the fuel cell, removing impurities on the surface of the membrane electrode of the fuel cell, activating the catalyst activity in the membrane electrode of the fuel cell, and forming proton and gas transmission channels. The activation voltage variable load process adopts a multi-round progressive method to gradually increase the variable load intensity, fully activate the membrane electrode of the fuel cell, build a suitable mass transfer channel inside, and build a working environment for subsequent limiting current testing. In specific implementation, a gradient variable load voltage method similar to that during the test can be selected as needed to change the activation voltage, protect the membrane electrode of the fuel cell while quickly stimulating the true performance of the membrane electrode of the fuel cell.

[0048] Step S3: providing a test environment; the test environment represents the environmental conditions for testing the activated membrane electrode of the fuel cell.

[0049] Step S4: In a test environment, a current density test is performed on the activated membrane electrode of the fuel cell to obtain a current density test result; the current density test result includes a limiting current density.

[0050] In the embodiment of the present application, the activation environment includes activated anode gas fuel and activated cathode gas fuel;

[0051] The activated anode fuel gas is hydrogen;

[0052] The activated cathode fuel gas is air.

[0053] Specifically, hydrogen and air are used as activation gas fuels, and the activation gas fuels include activated anode fuel gas and activated cathode fuel gas. A relatively high gas stoichiometric ratio is used to provide sufficient hydrogen and air supply for the membrane electrode of the activated fuel cell, and a large flow rate is used to remove moisture to avoid flooding that affects the performance release of the catalyst. At the same time, it is also necessary to avoid excessive flow that causes the membrane electrode of the fuel cell to become too dry and increase the ohmic overpotential.

[0054] In the embodiment of the present application, in the test environment, the current density test is performed on the activated membrane electrode of the fuel cell, and the current density test results obtained include:

[0055] In the test environment, the activated membrane electrode of the fuel cell is tested based on the test voltage variation process to obtain the current density test result; the test voltage variation process is carried out according to the preset test voltage variation information, and the test voltage of the fuel cell is varied starting from the open circuit voltage of the fuel cell; the preset test voltage variation information represents the relationship between the test voltage and time.

[0056] Specifically, the test voltage load variation process is carried out according to the preset test voltage load variation information, starting from the open circuit voltage of the fuel cell to perform the test voltage load variation on the fuel cell. Exemplarily, the test voltage can be regularly reduced from the open circuit voltage to 0.1V, and each test voltage point needs to stay for a certain time. Exemplarily, the present application provides a relationship between the test voltage and time, please refer to 3, Figure 3 It is a graph of the relationship between test voltage and time. The test voltage drops from OCV to V a During the test voltage reduction process, the slope of the test voltage is 0.2V / min, and it stays at 0.8V, 0.7V, 0.6V, and 0.5V for 2 minutes each. a Drop to V b During the test voltage reduction process (0.1V), the test voltage decreases at a slope of 0.2V / min, and stays at 0.4V, 0.35V, 0.3V, 0.25V, 0.2V, 0.15V, and 0.1V for at least 5 minutes. Each test voltage point fluctuates ≤5mV before switching to the next point. The test voltage is V b In the process of rising to OCV, the test voltage rises at a slope of 0.2V / min, and stays at 0.2V, 0.3V, 0.4V, 0.5V, 0.6V, 0.7V, 0.8V, and 0.9V for 0.5min each, and then returns to OCV. The test voltage is changed by changing the load voltage first fast and then slow, ensuring the efficiency of the test and the accuracy of the test results.

[0057] In the embodiment of the present application, after the current density test is performed on the activated membrane electrode of the fuel cell, the following is further included:

[0058] Providing a purge environment, wherein the purge environment represents an environmental condition for purging the activated membrane electrode of the fuel cell;

[0059] In the purge environment, the activated membrane electrode of the fuel cell is purged.

[0060] Specifically, after the test voltage variation process is completed, that is, after the test is completed, the activated membrane electrode of the fuel cell can be purged by using nitrogen as a purge gas to blow away the liquid water inside the activated membrane electrode of the fuel cell and restore the electrochemical balance inside the activated membrane electrode of the fuel cell.

[0061] In the embodiment of the present application, the test environment includes testing anode gas fuel and testing cathode gas fuel;

[0062] The anode gas fuel for the test was hydrogen;

[0063] The cathode gas fuel for the test is a mixed gas of air and nitrogen, and the oxygen mole fraction of the cathode gas fuel for the test is 0.5-15%.

[0064] Specifically, the test gas fuel includes a test anode gas fuel and a test cathode gas fuel. The purpose of using the mixed gas of air and nitrogen is to reduce the proportion of oxygen in the cathode so that the activated membrane electrode of the fuel cell completely consumes the oxygen in the gas, fully stimulates the active sites during the power generation process, and exhibits the ultimate performance of the activated membrane electrode of the fuel cell under this condition. Moreover, the mixed gas can significantly reduce the current density produced by the activated membrane electrode of the fuel cell. When pulled to a lower test potential, the activated membrane electrode of the fuel cell can be protected, and the load will not exceed the range of the test bench, which is suitable for the current mainstream membrane electrode sample test bench model. At the same time, a mixed gas of air and nitrogen is used as the test cathode gas fuel, and a low test voltage is pulled to obtain the limiting current when the activated membrane electrode of the fuel cell completely consumes oxygen. Exemplarily, in Example 1, different oxygen molar volume fractions of 10%, 5%, 3%, and 1% are selected, according to the above Figure 3 The relationship between the test voltage and time is shown in the figure. The test voltage is varied to obtain the current density values ​​corresponding to the voltage points of 0.4V, 0.35V, 0.3V, 0.25V, 0.2V, 0.15V and 0.1V. Please refer to Table 1 for the test data. Table 1 shows the current density (unit A / cm2) under different oxygen concentrations and different test voltages. 2), when the test voltage drops from 0.4V to 0.2V, the current density gradually increases and reaches the highest value at 0.2V. When the test voltage of the mixed gas with a partial oxygen mole fraction drops to 0.1V, the current density still increases. However, at this test potential, the electrochemical reaction inside the membrane electrode of the fuel cell after activation is partially converted into hydrogen adsorption energy for hydrogen evolution reaction. Therefore, 0.2V is selected as the limiting current value point, thereby obtaining the limiting current I lim . Draw a curve graph of the relationship between test voltage and current density, such as Figure 4 As shown in Figure 2, by changing the oxygen mole fraction, the limiting current variation law is obtained.

[0065] In the embodiment of the present application, the test environment includes testing the anode air intake temperature and testing the cathode air intake temperature;

[0066] The anode inlet temperature was tested to be 40-90°C;

[0067] The cathode inlet temperature was tested to be 40-90°C.

[0068] Specifically, the embodiments of the present application take into account that a suitable test intake temperature is beneficial to maintaining the test relative humidity, wherein the test intake temperature refers to the intake temperature of the test gas fuel, the test intake temperature includes the test anode intake temperature and the test cathode intake temperature, and the test relative humidity includes the test cathode relative humidity and the test anode relative humidity. By changing the test intake temperature within the range of 40 to 90°C for the test anode intake temperature and 40 to 90°C for the test cathode intake temperature, the effect of the test intake temperature on the membrane electrode performance of the fuel cell after activation is explored.

[0069] In the embodiment of the present application, the test environment includes testing the anode gas flow rate and testing the cathode gas flow rate;

[0070] The test anode gas flow rate is 1~4NLPM;

[0071] The cathode gas flow rate was tested to be 2-5 NLPM.

[0072] Specifically, in the embodiment of the present application, the test gas flow refers to the gas flow of the test gas fuel, and the test gas flow includes the test anode gas flow and the test cathode gas flow. The test gas flow uses a fixed flow mode, and the test gas flow is set to 3A / cm 2 This is the flow rate corresponding to the anode-cathode stoichiometric ratio of 2 / 3. Considering that too high test gas flow rate will take away too much moisture, the membrane electrode will be too dry and the resistance will increase, while low test gas flow rate will easily cause water blockage and fail to maintain the load voltage, the test gas flow rate is changed within the range of 1-4NLPM for the test anode gas flow rate and 2-5NLPM for the test cathode gas flow rate to explore the effect of the test gas flow rate on the performance of the membrane electrode after activation of the fuel cell.

[0073] In the embodiment of the present application, the test environment includes testing the anode intake pressure and testing the cathode intake pressure;

[0074] The test anode inlet pressure is 0~200kPa;

[0075] The cathode inlet pressure is tested to be 0~200kPa.

[0076] Specifically, the test intake pressure refers to the intake pressure of the test gas fuel, and the test intake pressure includes the test anode intake pressure and the test cathode intake pressure. It should be noted that the test intake pressure is a gauge pressure. The embodiment of the present application takes into account that a suitable test intake pressure can ensure a suitable concentration range of the test gas fuel inside the membrane electrode after activation of the fuel cell. By changing the intake pressure within the range of 0 to 200 kPa for the test anode intake pressure and 0 to 200 kPa for the test cathode intake pressure, the influence of the test intake pressure on the performance of the membrane electrode after activation of the fuel cell is explored.

[0077] In the embodiment of the present application, the test environment includes: testing anode relative humidity and testing cathode relative humidity;

[0078] The relative humidity of the test anode is 70-100%;

[0079] The relative humidity of the cathode was tested to be 70-100%.

[0080] Specifically, the test relative humidity refers to the test relative humidity of the fuel cell, which includes the test anode relative humidity and the test cathode relative humidity. The application embodiment takes into account that a suitable test relative humidity can ensure that the membrane electrode of the fuel cell is fully moistened after activation, and utilizes sufficient water flow to form a good mass transfer network. By changing the test relative humidity within the range of 70-100% for the test anode relative humidity and 70-100% for the test cathode relative humidity, the effect of the test relative humidity on the performance of the membrane electrode of the fuel cell after activation is explored.

[0081] In the embodiment of the present application, the test environment includes testing the fuel cell temperature, and the test fuel cell temperature is 40-90°C.

[0082] Specifically, the embodiments of the present application take into account that when the temperature of the test fuel cell is too low, the catalyst activity cannot be activated, and when the temperature of the test fuel cell is too high, the proton membrane glass transition temperature will be reached, damaging the activated membrane electrode of the fuel cell, and a suitable test fuel cell temperature is conducive to maintaining the test relative humidity. By changing the test fuel cell temperature within the range of 40 to 90°C, the effect of the test fuel cell temperature on the performance of the activated membrane electrode of the fuel cell is explored.

[0083] The limiting current test method disclosed in the above-mentioned embodiment of the present application, under specific conditions, causes all active sites of the membrane electrode to be activated and generates limiting current, which can be used to compare the performance of membrane electrodes made of different slurries or processes under the limiting state, and can be used as a basic test for in-depth exploration of membrane electrode performance. On the basis of limiting current, experiments are designed to deeply analyze membrane electrode performance. It can also be used as a basic method for in-depth analysis of membrane electrodes such as membrane electrode flow channel gas transmission resistance, carbon paper gas transmission capacity, and catalyst layer performance. Appropriate condition range limitation helps targeted experimental design based on this method, and more in-depth research on membrane electrode performance can be expanded while ensuring water balance inside the membrane electrode; through a slow loading slope, the cathode fuel with a reduced oxygen mole fraction and the high relative humidity of the gas fuel are avoided to avoid agglomeration and reverse polarity of the membrane electrode in the limiting current low potential test, thereby ensuring the safety of the membrane electrode, and it is not a destructive test; low-potential loading in an environment where the cathode lacks fuel forces all active sites of the membrane electrode to be activated, generating limiting current, which is used to compare the performance of membrane electrodes made of different slurries or processes under the limiting state, and can be used as a basic test for in-depth exploration of membrane electrode performance. Experiments are designed on the basis of limiting current to deeply analyze membrane electrode performance.

[0084] The technical solution of the present application is described below in conjunction with specific embodiments.

[0085] First, after completing the assembly, airtightness test and connection of the fuel cell test bench, prepare the conditions required for the test. In addition to conventional pure hydrogen and air, the gas fuel supply also needs to prepare a mixture of air and nitrogen; the bench not only has the ability to provide the specified intake temperature, dew point temperature, intake pressure, battery temperature and gas flow, but also needs to have a variable load mode that controls the voltage to obtain the corresponding current. Optionally, the purity of hydrogen is 99.999%, and the air is supplied by compressed ambient air from an air compressor, with an oxygen molar fraction of about 21%. The mixture of air and nitrogen needs to meet the requirements for setting the oxygen molar fraction in the mixture in the following embodiments.

[0086] Example 1

[0087] This embodiment is used to illustrate a limiting current testing method of the present invention.

[0088] Provide an activation environment: wherein the activation environment battery temperature is 75°C, the stoichiometric ratio of the activated anode gas flow is 4, the stoichiometric ratio of the activated cathode gas flow is 5, the activated anode inlet temperature is 90°C, the activated cathode inlet temperature is 90°C, the activated anode relative humidity is 80%, the activated cathode relative humidity is 80%, the activated anode inlet pressure is 150kPa, the activated cathode inlet pressure is 150kPa, according to the above Figure 2The activation voltage is subjected to multiple rounds of load variation to activate the membrane electrode of the fuel cell; a test environment is provided, wherein the test battery temperature is 70°C, the test anode gas flow rate is 3NLPM, the test cathode gas flow rate is 4NLPM, the test anode inlet temperature is 70°C, the test cathode inlet temperature is 70°C, the test anode relative humidity is 80%, the test cathode relative humidity is 80%, the test anode inlet pressure is 150kPa, the test cathode inlet pressure is 150kPa, and the above-mentioned conditions are adopted in the order of 10%, 5%, 3%, and 1%. Figure 3 The relationship between a test voltage and time is shown in Table 1. The test voltage is varied under different oxygen molar volume fractions. After the test, the activated membrane electrode of the fuel cell is purged with nitrogen. The current density values ​​corresponding to the voltage points of 0.4V, 0.35V, 0.3V, 0.25V, 0.2V, 0.15V, and 0.1V are obtained, and the test data are shown in Table 1. Table 1 shows the current density (unit A / cm2) under different oxygen concentrations and different test voltages. 2 ) and draw the test voltage-current density relationship curve, such as Figure 4 As shown, the current density corresponding to the test voltage of 0.2V is taken as the limiting current I lim .

[0089] Example 2

[0090] This embodiment is used to illustrate a limiting current testing method of the present invention.

[0091] First, an activation environment is provided: wherein the activation environment battery temperature is 90°C, the stoichiometric ratio of the activated anode gas flow is 2, the stoichiometric ratio of the activated cathode gas flow is 3, the activated anode inlet temperature is 75°C, the activated cathode inlet temperature is 75°C, the activated anode relative humidity is 100%, the activated cathode relative humidity is 100%, the activated anode inlet pressure is 200kPa, and the activated cathode inlet pressure is 200kPa. Figure 2 The activation voltage is subjected to multiple rounds of load changes to activate the membrane electrode of the fuel cell; a test environment is provided, wherein the test battery temperature is 70°C, the test anode gas flow rate is 3NLPM, the test cathode gas flow rate is 4NLPM, the test anode inlet temperature is 70°C, the test cathode inlet temperature is 70°C, the test anode relative humidity is 80%, the test cathode relative humidity is 80%, wherein the test anode inlet pressure and the test cathode inlet pressure are set the same, and are changed in sequence of 50, 100, 150, and 200 kPa, and each set of test inlet pressure values ​​are in the order of 10%, 5%, 3%, and 1%, using the above Figure 3The relationship between a test voltage and time is shown in FIG. 1. The test voltage is varied under different oxygen molar volume fractions. After the test, nitrogen is used to purge the activated membrane electrode of the fuel cell. The current density corresponding to the test voltage of 0.2 V is obtained as the limiting current I lim The test data are shown in Table 2. Table 2 shows the limiting current density (unit: A / cm 2 ).

[0092] Example 3

[0093] This embodiment is used to illustrate a limiting current testing method of the present invention.

[0094] First, an activation environment is provided: wherein the activation environment battery temperature is 90°C, the stoichiometric ratio of the activated anode gas flow is 4, the stoichiometric ratio of the activated cathode gas flow is 5, the activated anode inlet temperature is 80°C, the activated cathode inlet temperature is 80°C, the activated anode relative humidity is 80%, the activated cathode relative humidity is 80%, the activated anode inlet pressure is 150kPa, the activated cathode inlet pressure is 150kPa, according to the above Figure 2 The activation voltage is subjected to multiple rounds of load changes to activate the membrane electrode of the fuel cell; a test environment is provided, wherein the test battery temperature is 70°C, the test anode gas flow rate is 3NLPM, the test cathode gas flow rate is 4NLPM, the test anode inlet temperature is 70°C, the test cathode inlet temperature is 70°C, the test anode inlet pressure is 150kPa, and the test cathode inlet pressure is 150kPa, wherein the test anode relative humidity and the test cathode relative humidity are set the same, and are changed in sequence of 70, 80, 90, and 100%, and each set of test relative humidity values ​​are in the order of 10%, 5%, 3%, and 1%, using the above Figure 3 The relationship between a test voltage and time is shown in FIG. 1. The test voltage is varied under different oxygen molar volume fractions. After the test, nitrogen is used to purge the activated membrane electrode of the fuel cell. The current density corresponding to the test voltage of 0.2 V is obtained as the limiting current I lim The test data are shown in Table 3, which shows the limiting current density (unit: A / cm 2 ).

[0095] Example 4

[0096] This embodiment is used to illustrate a limiting current testing method of the present invention.

[0097] First, an activation environment is provided: wherein the activation environment battery temperature is 90°C, the stoichiometric ratio of the activated anode gas flow is 4, the stoichiometric ratio of the activated cathode gas flow is 5, the activated anode inlet temperature is 75°C, the activated cathode inlet temperature is 75°C, the activated anode relative humidity is 70%, the activated cathode relative humidity is 70%, the activated anode inlet pressure is 150kPa, the activated cathode inlet pressure is 150kPa, according to the above Figure 2 The activation voltage is subjected to multiple rounds of load changes to achieve activation of the membrane electrode of the fuel cell; a test environment is provided, the test anode gas flow rate is 3NLPM, the test cathode gas flow rate is 4NLPM, the test anode intake pressure is 150kPa, the test cathode intake pressure is 150kPa, the test anode relative humidity is 80%, and the test cathode relative humidity is 80%, wherein each group of test anode intake temperature, test cathode intake temperature and test fuel cell temperature are set the same, and change in sequence according to 40, 50, 60, 70, 80, 90°C, and each group of test temperature values ​​are set in the order of 10%, 5%, 3%, and 1%, using the above Figure 3 The relationship between a test voltage and time is shown in FIG. 1. The test voltage is varied under different oxygen molar volume fractions. After the test, nitrogen is used to purge the activated membrane electrode of the fuel cell. The current density corresponding to each test voltage of 0.2 V is obtained as the limiting current I lim The test data are shown in Table 4, which shows the limiting current density (unit A / cm 2 ).

[0098] Example 5

[0099] This embodiment is used to illustrate a limiting current testing method of the present invention.

[0100] First, an activation environment is provided: wherein the activation environment battery temperature is 90°C, the stoichiometric ratio of the activated anode gas flow is 4, the stoichiometric ratio of the activated cathode gas flow is 5, the activated anode inlet temperature is 70°C, the activated cathode inlet temperature is 70°C, the activated anode relative humidity is 80%, the activated cathode relative humidity is 80%, the activated anode inlet pressure is 150kPa, the activated cathode inlet pressure is 150kPa, according to the above Figure 2The activation voltage is subjected to multiple rounds of load changes according to the relationship between activation voltage and time shown in the figure, so as to activate the membrane electrode of the fuel cell; a test environment is provided, the test battery temperature is 70°C, the test cathode gas flow is 4NLPM, the test anode intake temperature is 70°C, the test cathode intake temperature is 70°C, the test anode intake pressure is 150kPa, the test cathode intake pressure is 150kPa, the test anode relative humidity is 80%, and the test cathode relative humidity is 80%, wherein the test anode gas flow is changed in sequence of 1, 2, 3, and 4NLPM, and each test anode gas flow value is set in the order of 10%, 5%, 3%, and 1%, using the above Figure 3 The relationship between a test voltage and time is shown in FIG. 1. The test voltage is varied and tested at different oxygen molar volume fractions. After the test, nitrogen is used to purge the activated membrane electrode of the fuel cell. The current density corresponding to each test voltage of 0.2 V is obtained as the limiting current I lim The test data are shown in Table 5, which shows the limiting current density (unit: A / cm 2 ).

[0101] Example 6

[0102] This embodiment is used to illustrate a limiting current testing method of the present invention.

[0103] First, an activation environment is provided: wherein the activation environment battery temperature is 80°C, the stoichiometric ratio of the activated anode gas flow is 4, the stoichiometric ratio of the activated cathode gas flow is 5, the activated anode inlet temperature is 75°C, the activated cathode inlet temperature is 75°C, the activated anode relative humidity is 80%, the activated cathode relative humidity is 80%, the activated anode inlet pressure is 180kPa, the activated cathode inlet pressure is 180kPa, according to the above Figure 2 The activation voltage is varied by a multi-round variable load mode of the activation voltage shown in the figure to achieve activation of the membrane electrode of the fuel cell; a test environment is provided, the test battery temperature is 70°C, the test anode gas flow rate is 3NLPM, the test anode intake temperature is 70°C, the test cathode intake temperature is 70°C, the test anode intake pressure is 150kPa, the test cathode intake pressure is 150kPa, the test anode relative humidity is 80%, and the test cathode relative humidity is 80%, wherein the test cathode gas flow rate is changed in sequence of 2, 3, 4, and 5NLPM, and each test cathode gas flow rate value is set in the order of 10%, 5%, 3%, and 1%, using the above Figure 3 The relationship between a test voltage and time is shown in FIG. 1. The test voltage is varied under different oxygen molar volume fractions. After the test, nitrogen is used to purge the activated membrane electrode of the fuel cell. The current density corresponding to each test voltage of 0.2 V is obtained as the limiting current Ilim The test data are shown in Table 6, which shows the limiting current density (unit: A / cm 2 ).

[0104] Table 1. Current density (unit A / cm2) at different oxygen concentrations and test voltages 2 )

[0105]

[0106]

[0107] Table 2. Limiting current density (in A / cm2) at different oxygen concentrations and different test inlet pressures 2 )

[0108]

[0109] Table 3. Limiting current density (in A / cm2) at different oxygen concentrations and relative humidity 2 )

[0110] Test relative humidity% 1％ 3％ 5％ 10％ 80 0.279 0.492 0.965 1.373 70 0.263 0.471 0.932 1.354 90 0.276 0.490 0.957 1.367 100 0.266 0.485 0.944 1.361

[0111] Table 4. Limiting current density (in A / cm2) at different oxygen concentrations and test temperatures 2 )

[0112] Test temperature ℃ 1％ 3％ 5％ 10％ 70 0.279 0.492 0.965 1.373 40 0.251 0.462 0.944 1.352 50 0.263 0.477 0.951 1.364 60 0.271 0.482 0.957 1.370 80 0.280 0.495 0.967 1.375 90 0.278 0.493 0.962 1.374

[0113] Table 5. Limiting current density (unit: A / cm2) at different oxygen concentrations and different test anode gas flow rates 2 )

[0114]

[0115] Table 6. Limiting current density (unit: A / cm2) at different oxygen concentrations and different cathode gas flow rates 2 )

[0116]

[0117]

[0118] It can be seen from the above technical scheme of the embodiment of the present invention that the present invention discloses a limiting current testing method, which includes: providing an activation environment; in the activation environment, activating the membrane electrode of the fuel cell based on the activation voltage load variation process to obtain the activated membrane electrode of the fuel cell; then providing a test environment, in the test environment, performing a current density test on the activated membrane electrode of the fuel cell to obtain a current density test result, wherein the current density test result includes a limiting current density; the embodiment of the present application activates the membrane electrode of the fuel cell before the test, thereby stimulating the true performance of the membrane electrode, improving the accuracy of the current density test result, and protecting the membrane electrode.

[0119] The above description has fully disclosed the specific embodiments of the present invention. It should be pointed out that any changes made by those skilled in the art to the specific embodiments of the present invention do not deviate from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not limited to the above specific embodiments.

Claims

1. A limiting current test method, applied to a membrane electrode of a fuel cell, characterized in that: The method comprises: Providing an activation environment; the activation environment represents the environmental conditions for activating the membrane electrode of the fuel cell; In the activation environment, the membrane electrode of the fuel cell is activated based on an activation voltage variation process to obtain an activated membrane electrode of the fuel cell; the activation voltage variation process varies the activation voltage of the fuel cell based on preset activation voltage variation information and takes the open circuit voltage of the fuel cell as a starting point; the preset activation voltage variation information represents the relationship between activation voltage and time; Providing a test environment; the test environment represents the environmental conditions for testing the activated membrane electrode of the fuel cell; In the test environment, a current density test is performed on the activated membrane electrode of the fuel cell to obtain a current density test result; the current density test result includes a limiting current density.

2. A limiting current testing method according to claim 1, characterized in that: The activation environment includes activated anode gas fuel and activated cathode gas fuel; The activated anode fuel gas is hydrogen; The activated cathode fuel gas is air.

3. A limiting current testing method according to claim 1, characterized in that: In the test environment, the activated membrane electrode of the fuel cell is subjected to a current density test, and the current density test result obtained includes: In the test environment, the activated membrane electrode of the fuel cell is tested based on a test voltage variation process to obtain the current density test result; the test voltage variation process varies the test voltage of the fuel cell according to preset test voltage variation information, taking the open circuit voltage of the fuel cell as the starting point; the preset test voltage variation information represents the relationship between the test voltage and time.

4. A limiting current testing method according to claim 1, characterized in that: After the current density test is performed on the activated membrane electrode of the fuel cell, the method further comprises: providing a purge environment, wherein the purge environment represents an environmental condition for purging the activated membrane electrode of the fuel cell; In the purge environment, the activated membrane electrode of the fuel cell is purged.

5. A limiting current testing method according to claim 1, characterized in that: The test environment includes testing anode gas fuel and testing cathode gas fuel; The test anode gas fuel is hydrogen; The test cathode gas fuel is a mixed gas of air and nitrogen, and the oxygen mole fraction of the test cathode gas fuel is 0.5-15%.

6. A limiting current testing method according to claim 1, characterized in that: The test environment includes testing anode air intake temperature and testing cathode air intake temperature; The test anode air intake temperature is 40-90°C; The test cathode air inlet temperature is 40-90°C.

7. A limiting current testing method according to claim 1, characterized in that: The test environment includes testing anode gas flow and testing cathode gas flow; The test anode gas flow rate is 1-4 NLPM; The test cathode gas flow rate is 2-5 NLPM.

8. A limiting current testing method according to claim 1, characterized in that: The test environment includes testing the anode intake pressure and testing the cathode intake pressure; The test anode inlet pressure is 0-200 kPa; The test cathode air inlet pressure is 0-200 kPa.

9. A limiting current testing method according to claim 1, characterized in that: The test environment includes: testing anode relative humidity and testing cathode relative humidity; The relative humidity of the test anode is 70-100%; The relative humidity of the test cathode is 70-100%.

10. A limiting current testing method according to claim 1, characterized in that: The test environment includes a test fuel cell temperature, and the test fuel cell temperature is 40-90°C.

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