CN117589664A - A proton exchange membrane fuel cell bipolar plate corrosion resistance testing system and method - Google Patents

Abstract

The invention discloses a corrosion resistance testing system and method for a bipolar plate of a proton exchange membrane fuel cell. The system comprises: a heating device; the test tank is provided with a hollow accommodating space for accommodating a test solution and a test sample, a reference electrode, a counter electrode, a temperature sensor and a condensing tube are fixedly penetrated at the top of the test tank, and the other end of the condensing tube is communicated with a gas collecting bottle; the test Chi Cebian opening is respectively connected with the liquid level pipe and the peristaltic pump, the other end of the liquid level pipe is communicated with the gas collecting bottle, and the other end of the peristaltic pump is communicated with the solution tank. The patent develops a testing system suitable for corrosion resistance evaluation of the bipolar plate of the high-temperature fuel cell, and solves the problems of inaccurate application of working potential of an electrochemical testing system at high temperature, easy volatilization of solution, concentration change of system solution, pollution to experimental environment and the like. Thereby realizing stable and long-time bipolar plate performance test at high temperature.

Description

A proton exchange membrane fuel cell bipolar plate corrosion resistance testing system and method

Technical field

The present invention mainly relates to the field of proton exchange membrane fuel cells, and in particular to the corrosion resistance test of bipolar plates. Specifically, a corrosion resistance testing system and method for proton exchange membrane fuel cell bipolar plates suitable for high-temperature environments is proposed.

Background technique

Fuel cell bipolar plates are usually required to have excellent corrosion resistance. However, in the application of high-temperature fuel cells, due to the increase in operating temperature, the internal environmental conditions are more harsh compared to low-temperature fuel cells, which will greatly increase the bipolar plate. Risk of electrochemical corrosion of the board. In order to evaluate the corrosion resistance of a bipolar plate, it is usually necessary to determine its corrosion morphology, corrosion potential, corrosion current and other parameters through an electrochemical three-electrode test system under conditions that simulate its working environment, and to speculate on its applicability. However, for high-temperature fuel cells, since the operating temperature is usually above 100 degrees Celsius, it is easy to cause problems such as inaccurate application of test potential and volatilization of the test solution system. For proton exchange membrane fuel cells, increasing the operating temperature can effectively improve efficiency, but it also brings a great test to the corrosion resistance of the bipolar plates. The bipolar plates need to be tested in the high-temperature proton exchange membrane fuel cell environment. Offline electrochemical corrosion testing. Due to the influence of high temperature, the test system has multiple instabilities, making it difficult to achieve accurate measurements. Therefore, the development of a corrosion resistance test system that can support high temperature ranges is particularly important.

The Chinese patent application with publication number CN113933366A discloses a fuel cell bipolar plate electrochemical testing device that uses a separate electrolytic cell and connects the reference electrode and the working electrode through a salt bridge liquid to achieve temperature control of the reference electrode and the working electrode. Separate control is easy to maintain the required operating temperature, so that the commonly used calomel electrode or Ag|AgCl electrode can be used in corrosion electrochemical tests under medium and high temperature (100-200℃) conditions, and it can ensure its stability for long-term use. performance; a circulating water cooling device is added outside the salt bridge to ensure that the first electrolytic cell is maintained at room temperature. The cooperation of the thermocouple and the constant-temperature electric heating plate ensures that the second electrolytic cell operates at high temperature, improving the stability of the test environment. Although the device proposed in the above patent can solve the problem of bipolar plate testing in high-temperature systems to a certain extent, the patent still has obvious shortcomings:

1. The temperature difference between the solution between the reference electrode and the working electrode will cause a difference in potential between the two electrodes, making the test accuracy uncontrollable.

2. The salt bridge used cannot be used at high temperatures. Usually the built-in sand core of the salt bridge will have an obvious increase in seepage rate when the temperature is greater than 70°C, causing the saturated solution in the salt bridge to contaminate the test system.

3. The patent describes that in order to prevent the solution concentration from changing due to volatilization of the solution at high temperatures, a spherical condenser tube is added. However, the test system is not completely isolated from the external environment. Under conditions of long test time and high test temperature, there will still be problems with chronic volatilization of the solution, especially when the test device has a small volume. Therefore, simply adding a condenser tube is not enough to completely avoid a series of problems caused by solution volatilization.

Contents of the invention

In view of the shortcomings of the existing technology, the present invention provides a corrosion resistance testing system and method for a proton exchange membrane fuel cell bipolar plate. The system of the invention isolates the test system from water vapor in the experimental environment, and is equipped with a condensation device, a liquid level detection device and an automatic replenishing function, thereby avoiding problems such as contamination of the experimental environment and solution loss caused by the volatilization of high-temperature solutions. A reversible hydrogen electrode is used as the reference electrode and is in the same solution system as the working electrode, which avoids problems such as test potential differences caused by factors such as solution temperature differences. This system can meet the long-term performance evaluation of bipolar plates in a simulated high-temperature proton exchange membrane fuel cell environment.

The technical means adopted in the present invention are as follows:

A proton exchange membrane fuel cell bipolar plate corrosion resistance testing system, including:

Heating device to control the temperature of the test cell;

Test pool, the test pool has a hollow accommodation space for holding test solutions and test samples. The top of the test pool is fixed with a reference electrode, a counter electrode, a temperature sensor and a condensation tube. The condensation tube is The other end is connected to the gas collecting bottle;

A sample stage for fixing metal bipolar plate samples is provided at the bottom of the test cell;

The openings on the side of the test pool are respectively connected to the liquid level tube and the peristaltic pump. The other end of the liquid level tube is connected to the gas collecting bottle, and the other end of the peristaltic pump is connected to the solution tank.

Further, the reference electrode is a reversible hydrogen electrode.

Further, the counter electrode is a platinum electrode or a graphite electrode.

Further, the upper part of the liquid level tube is equipped with a liquid level sensor, and the liquid level sensor is used to monitor the liquid level of the solution inside the test pool in real time.

The invention also discloses a method for testing the corrosion resistance of proton exchange membrane fuel cell bipolar plates, which is implemented based on the above system and includes the following steps:

Voltage excitation is used to conduct periodic test cycles at 90-200°C to simulate the long-term service environment of bipolar plates in different working conditions under high-temperature solution conditions;

Conduct corrosion current density tests at standard potentials at fixed intervals to detect changes in bipolar plate performance;

The cut-off test time of the bipolar plate is determined by setting the corrosion current density value and total ion precipitation concentration value at the standard potential at the end of performance.

Further, the voltage excitation includes: applying a voltage form of constant potential, variable load potential or a combination of the two to the bipolar plate sample to simulate idle conditions, variable load conditions or mixed conditions when the fuel cell is running. situation.

Further, the method also includes:

When performing standard potential detection, use a pH tester to detect and record the pH value. At the same time, collect the test solution after each standard potential detection, and detect the concentration of matrix ions precipitated from the bipolar plate.

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

1. The system of the present invention inhibits the rapid evaporation of solutions at high temperatures through water vapor isolation, external cooling, etc., and at the same time, through functions such as real-time detection of solution level and automatic replenishment, it avoids solution loss and concentration caused by the volatilization of test solutions under high temperature systems. Changes and environmental pollution issues. The system control accuracy of the test process is improved and unattended is realized.

2. The present invention uses a reversible hydrogen electrode instead of an electrode filled with a saturated solution such as silver chloride or saturated calomel as the reference electrode, thereby avoiding the pollution and impact of the leakage of the filling solution on the test system. In addition, the reference electrode and the test sample are placed in the same high-temperature solution environment, which avoids potential differences caused by temperature differences or solution concentration differences, and improves the accuracy of test potential control.

3. The system of the present invention can realize bipolar plate performance and long-term durability testing in a proton exchange membrane fuel cell environment simulated at high temperatures (90-200°C). Voltage excitation is used to conduct long-term periodic test cycles to simulate the long-term service environment of bipolar plates in different working conditions under high-temperature solution conditions. Corrosion current density tests at standard potentials are performed at regular intervals to detect changes in performance. By setting the corrosion current density value and the precipitated ion concentration value at the standard potential at the end of performance, the stable corrosion resistance time of the bipolar plate can be determined.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that need to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting any creative effort.

Figure 1 is a schematic structural diagram of a proton exchange membrane fuel cell bipolar plate corrosion resistance testing system of the present invention.

Figure 2 shows the corrosion current measurement results at standard potential every 50 hours in the example.

In the picture: 1. Heating device, 2. Test cell, 3. Reference electrode, 4. Counter electrode, 5. Temperature sensor, 6. Condenser tube, 7. Liquid level tube, 8. Liquid level sensor, 9. Gas collection Bottle, 10. Test sample, 11. Working electrode rod, 12. Peristaltic pump, 13. Solution tank.

Detailed ways

In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only These are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall within the scope of protection of the present invention.

As shown in Figure 1, a testing system for evaluating the corrosion resistance of high-temperature proton exchange membrane fuel cell bipolar plates includes: heating device 1, test cell 2, reference electrode 3, counter electrode 4, temperature sensor 5, Condensation tube 6, liquid level tube 7, liquid level sensor 8, gas collection bottle 9, test sample 10, working electrode rod 11, peristaltic pump 12 and solution tank 13.

Heating device 1 refers to a device that can change and continuously control the temperature of the test system, specifically a circulating water bath, oil bath, heating belt, heating plate, etc. The present invention preferably adopts a heating belt device, which can realize a temperature change range of 30°C to 200°C.

As a preferred embodiment of the present invention, the test tank 2 is made of high-temperature-resistant and corrosion-resistant material, and contains test solutions and test samples inside. The top is equipped with threaded holes and O-rings, which can be used with the pagoda connector to fix the reference electrode 3, counter electrode 4, temperature sensor 5, condenser tube 6 and other devices and achieve water vapor isolation from the external environment. The side opening of the test tank 2 is connected to the liquid level pipe 7 and the peristaltic pump 12. A sample stage is provided at the bottom for fixing the metal bipolar plate sample 10, and is connected to the electrochemical workstation through a working electrode rod 11.

As a preferred embodiment of the present invention, the reference electrode 3 specifically uses a reversible hydrogen electrode, which can avoid solution precipitation and potential drift of other reference electrodes filled with saturated solutions at high temperatures, and avoid contamination of the test system and improper control of the test potential. Precise phenomena occur.

As a preferred embodiment of the present invention, the counter electrode 4 includes stable electrode materials such as platinum electrodes and graphite electrodes that can be used for long-term testing.

As a preferred embodiment of the present invention, the temperature sensor 5 is used to monitor the temperature of the solution in the test pool 2 in real time, and is connected to the heating device 1 and controls the heating power to ensure that the system temperature meets the test requirements and remains constant.

As a preferred embodiment of the present invention, circulating cooling water is introduced into the condensation pipe 6 to condense the test solution evaporated by the high temperature of the system. The condensed solution can flow back into the test pool 2 or flow into the gas collecting bottle through the connecting pipe. 9, the exhaust gas in the gas collecting bottle 9 is led to the outdoors through the exhaust pipeline.

As a preferred embodiment of the present invention, the liquid level pipe 7 is connected to the test tank 2, and the internal solutions are communicated with each other. The upper fixed position is equipped with a liquid level sensor 8, and the top end is connected to the gas collecting bottle 9 through a pipeline. The liquid level sensor 8 is used to monitor the liquid level of the solution inside the test tank 2 in real time, and is connected to the peristaltic pump 12 circuit. The peristaltic pump 12 is connected to the solution tank 13 and is used to slowly transport the backup test solution contained in the solution tank 13, and the flow rate of the solution is controllable. When a long-term high-temperature test is performed, more condensed solution flows into the gas collecting bottle 9, which will reflect an obvious drop in the liquid level on the liquid level tube 7. When the liquid level drops below the liquid level sensor 8, the sensor sends an instruction to the peristaltic pump to slowly replenish the backup test solution in the solution tank into the test pool.

The invention also discloses a method for testing the corrosion resistance of bipolar plates under high-temperature conditions. The above-mentioned high-temperature testing system is used to conduct electrochemical corrosion tests on bipolar plate samples, and voltage excitation is used under high-temperature (90-200°C) conditions. Long-term periodic test cycles can simulate the long-term service environment of bipolar plates in different working conditions under high-temperature solution conditions. Corrosion current density tests at standard potentials are performed at regular intervals to detect changes in performance. By setting the corrosion current density value and the precipitated ion concentration value at the standard potential at the end of performance, the cut-off test time of the bipolar plate can be determined.

As a preferred embodiment of the present invention, voltage excitation refers to applying a voltage form of constant potential, variable load potential or a combination of the two to the bipolar plate sample in the electrochemical testing method to simulate the idling condition of the fuel cell during operation. Variable load conditions or mixed conditions.

As a preferred embodiment of the present invention, in order to determine the changes in the internal solution concentration of the test system during long-term operation, a pH tester is used to detect and record the pH value when performing standard potential detection.

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

This embodiment explains the technical solution of the present invention in detail in combination with a specific system:

A testing system for evaluating the corrosion resistance of metal bipolar plates of high-temperature proton exchange membrane fuel cells, including: heating device 1, test cell 2, reference electrode 3, counter electrode 4, temperature sensor 5, condenser tube 6, liquid Level tube 7, liquid level sensor 8, gas collection bottle 9, test sample 10, working electrode rod 11, peristaltic pump 12 and solution tank 13.

Connect the solution tank, peristaltic pump, and test cell through pipelines; place the metal bipolar plate sample at the bottom of the test cell and fix it so that the working electrode rod is in close contact with the sample.

Insert the reference electrode, counter electrode, and temperature sensor into the test cell through the reserved holes in the top cover of the test cell, and seal and tighten them with O-rings and pagoda joints. The reference electrode and counter electrode used a reversible hydrogen electrode and a platinum electrode respectively.

Wrap and fix the heating device around the periphery of the test cell and connect it to the temperature sensor circuit. The heating device is a silicone heating belt, which can achieve temperature control of 30 to 200°C.

The liquid level tube is connected through a reserved fixed hole in the test pool so that it can communicate with the solution inside the test pool. A liquid level sensor is installed at a certain position on the upper part of the liquid level pipe to monitor liquid level changes inside the liquid level pipe in real time, and the liquid level sensor is connected to the peristaltic pump line. Set the peristaltic pump solution delivery speed to 20mL/min.

The top of the test pool is sealed and connected to the condenser pipe through a pagoda joint. The outlet of the condenser tube and the top of the liquid level tube are connected to the gas collecting bottle through the same pipeline.

Pour an appropriate amount of the test solution into the test pool and solution box respectively. The liquid level in the test pool can be observed from the liquid level tube. Make sure that the solution in the liquid level tube does not cover the liquid level sensor by 1cm, and tighten the test pool. Lid seals. The test solution used was a mixed solution of sulfuric acid and 0.1ppm hydrofluoric acid with pH=3.

Turn on the heating belt and temperature sensor switches to heat the solution, and set the test temperature to 130°C. The reversible hydrogen electrode, platinum electrode, and working electrode are connected to the electrochemical workstation in sequence. A long-term electrochemical corrosion test begins when the solution temperature reaches a preset temperature. When the test time is long, the solution in the test pool is obviously missing, the liquid level in the liquid level tube drops to the bottom of the liquid level sensor, and the peristaltic pump begins to slowly replenish the backup test solution in the solution tank into the test pool.

In order to evaluate the corrosion resistance stability of bipolar plate samples under long-term idling conditions at 130°C, the voltage excitation method used was constant potential polarization, the potential value was set to 0.85V, and the single test duration was 50h. In order to monitor the changes in the corrosion resistance of the bipolar plate samples under this system, a 5-h standard potential polarization test was performed every 50 h. The standard potential used was 1V. The life of the bipolar plate reaches the end when the current density exceeds 1μA/cm2 at the standard potential, or the total precipitation concentration of Fe element reaches 300ppb. In order to determine the internal solution concentration changes and ion precipitation of the test system during long-term operation, a pH tester is used to record the pH value during standard potential detection, and an appropriate amount of solution is collected for elemental composition and concentration detection.

In an acidic solution at 130°C and pH 3, the bipolar plate was tested for a long period using the simulated fuel cell idle potential, and the current density tested at the standard potential every 50 hours was recorded. The results are shown in Figure 2. It can be seen that the current density continues to rise, and the current density value exceeds the preset life end point current at the 100h node, indicating that the stable corrosion resistance time of the bipolar plate sample under the above test conditions is 100h.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention. scope.

Claims (7)

1. A proton exchange membrane fuel cell bipolar plate corrosion resistance testing system, comprising:

a heating device (1) for controlling the temperature of the test cell;

the test tank (2) is provided with a hollow accommodating space for accommodating test solution and test samples, a reference electrode (3), a counter electrode (4), a temperature sensor (5) and a condenser tube (6) are fixedly penetrated at the top of the test tank (2), and the other end of the condenser tube (6) is communicated with a gas collecting bottle (9);

a sample table for fixing the metal bipolar plate sample (10) is arranged at the bottom of the test pool (2);

the test Chi Cebian opening is respectively connected with the liquid level pipe (7) and the peristaltic pump (12), the other end of the liquid level pipe (7) is communicated with the gas collection bottle (9), and the other end of the peristaltic pump (12) is communicated with the solution tank (13).

2. The bipolar plate corrosion resistance testing system for a proton exchange membrane fuel cell according to claim 1, wherein the reference electrode (3) is a reversible hydrogen electrode.

3. A bipolar plate corrosion resistance testing system for a proton exchange membrane fuel cell according to claim 1, wherein said counter electrode (4) is a platinum electrode or a graphite electrode.

4. The corrosion resistance testing system of a bipolar plate of a proton exchange membrane fuel cell according to claim 1, wherein a liquid level sensor (8) is arranged at the upper part of the liquid level pipe (7), and the liquid level sensor (8) is used for monitoring the liquid level of a solution in the testing tank (2) in real time.

5. A method for testing corrosion resistance of a bipolar plate of a proton exchange membrane fuel cell, based on the system implementation of any one of claims 1-5, comprising the steps of:

the periodic test cycle is carried out by using voltage excitation under the condition of 90-200 ℃ so as to simulate the long-time service environment of the bipolar plate under different working conditions under the condition of high-temperature solution;

performing corrosion current density testing under standard potential at fixed intervals to detect bipolar plate performance changes;

and determining the cut-off test time of the bipolar plate by setting the corrosion current density value and the total ion precipitation concentration value under the performance ending standard potential.

6. The method for testing the corrosion resistance of a bipolar plate of a proton exchange membrane fuel cell as recited in claim 5, wherein said voltage excitation comprises: and applying a constant potential, a variable load potential or a voltage form of the constant potential, the variable load potential or the voltage form of the variable load potential and the voltage form of the constant potential, the variable load potential or the voltage form of the variable load potential in combination to simulate the idle speed working condition, the variable load working condition or the mixed working condition of the fuel cell during operation.

7. The method for testing the corrosion resistance of a bipolar plate of a proton exchange membrane fuel cell as recited in claim 5, further comprising:

and when the standard potential detection is carried out, a pH tester is used for carrying out pH value detection and recording, meanwhile, after each standard potential detection is finished, a test solution is collected, and the concentration of matrix ions precipitated by the bipolar plate is detected.