Device and method for testing surface resistance of composite membrane based on variable-temperature variable-voltage two-electrode method

Abstract

The invention belongs to the technical field of alkaline electrolyzed water, and relates to a device for testing surface resistance of a composite membrane based on a variable-temperature variable-voltage two-electrode method, which comprises a hot press and a testing unit, the test unit comprises a heating and pressurizing upper end plate, a heating and pressurizing lower end plate, a first metal electrode, a second metal electrode, a first metal electrode clamp, a second metal electrode clamp and an insulation sleeve. The invention further relates to a method for testing the surface resistance of the composite membrane based on the variable-temperature variable-voltage two-electrode method. According to the invention, through combination of the test unit and the hot press, the surface resistance value of the composite membrane in a variable-pressure and variable-temperature state can be tested, so that the test result is more reliable, and the test requirement is met. By testing the surface resistance of the composite membrane, the composite membrane is in direct contact with the electrode, alkali liquor resistance does not need to be further eliminated, measurement is more accurate, and the device is convenient to install, easy to operate and high in measurement efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of alkaline water electrolysis, and relates to a testing technology for composite membrane surface resistance, in particular to a device and method for testing composite membrane surface resistance based on a variable temperature and voltage two-electrode method. Background Art

[0002] As a zero-carbon energy carrier, hydrogen has become a core direction of the global energy transition. Currently, alkaline water electrolysis (ALK) and proton exchange membrane electrolysis (PEM) dominate large-scale hydrogen production technologies. Alkaline water electrolysis, with its advantages of low equipment cost, long operating life, and simplified maintenance, has become the most commercialized and mature solution for large-scale application. It is particularly suitable for large-scale hydrogen production scenarios coupled with renewable energy sources such as wind power and photovoltaics.

[0003] The membrane is a key component of the alkaline water electrolysis hydrogen production equipment. It plays the following roles in the water electrolysis process: 1. Separating the cathode and anode to prevent the explosion caused by the mixing of hydrogen and oxygen; 2. Conducting OH - , forming a circuit; 3. Electronic insulation to prevent short circuits. Therefore, membranes used in alkaline water electrolysis should have the following conditions: 1. High electrical conductivity; 2. Excellent gas barrier properties; 3. Good alkaline stability; 4. High mechanical strength; 5. Electronic insulation.

[0004] Sheet resistance is a key parameter of composite membranes. Using composite membranes with lower sheet resistance can reduce energy consumption and, therefore, hydrogen production costs. Therefore, accurately measuring the sheet resistance of composite membranes is essential. Currently, there are two methods for testing the sheet resistance of composite membranes: the four-electrode method and the two-electrode method. However, most of the reported testing techniques can only measure the variation of the sheet resistance of composite membranes with temperature at normal pressure. In actual operating conditions, composite membranes are used under pressure, so testing the sheet resistance of composite membranes under variable temperature and pressure conditions is crucial. Summary of the Invention

[0005] The purpose of the present invention is to provide a device and method for testing the surface resistance of a composite membrane based on a variable temperature and voltage two-electrode method, which has low surface resistance, high electrical conductivity, high gas barrier properties, high mechanical strength, can be prepared on a large scale, and is easy to implement.

[0006] The present invention solves the technical problem by the following technical solutions:

[0007] A device for testing the surface resistance of a composite film based on a variable temperature and variable pressure two-electrode method, comprising a hot press, characterized in that: it also includes a testing unit, the testing unit comprising a heated and pressurized upper end plate, a heated and pressurized lower end plate, a first metal electrode, a second metal electrode, a first metal electrode clamp, a second metal electrode clamp, and an insulating sleeve, the heated and pressurized upper end plate being mounted on the upper mounting plate of the hot press, the second metal electrode being mounted on the lower end surface of the heated and pressurized upper end plate, the second metal electrode being connected to the side of the second metal electrode with the second metal electrode clamp, the second metal electrode comprising an upper connecting portion and a pressure portion protruding downward from the middle portion of the upper connecting portion;

[0008] A heating and pressurizing lower end plate is installed on the lower mounting plate of the hot press, a first metal electrode is installed on the upper end surface of the heating and pressurizing lower end plate, a first metal electrode is connected to one side of the first metal electrode, and a probe connected to the temperature detector is installed on the other side of the first metal electrode. The first metal electrode includes a lower connecting portion and a pressure-bearing portion protruding upward from the middle of the lower connecting portion. An insulating sleeve is sleeved on the outer ring of the pressure-bearing portion, the lower sleeve opening of the insulating sleeve is sleeved on the pressure-bearing portion, the upper end surface of the lower sleeve opening is lower than the upper end surface of the pressure-bearing portion, and the upper sleeve opening of the insulating sleeve is for the pressure-applying portion to expand and contract therein.

[0009] Preferably, the materials of the first metal electrode, the first metal electrode clip, the second metal electrode and the second metal electrode clip include but are not limited to copper, iron, silver and nickel.

[0010] Preferably, the material of the insulating sleeve includes but is not limited to polytetrafluoroethylene, polysulfone, polypropylene, epoxy resin, and acrylic.

[0011] Preferably, the end surface area of ​​the pressure-bearing portion on the first metal electrode is 1-5 cm 2 The end surface area of ​​the pressure portion of the second metal electrode is 10-20cm 2 .

[0012] A method for testing the surface resistance of a composite film based on a variable temperature and voltage two-electrode method, characterized by comprising the following steps:

[0013] Step 1: soak the composite membrane to be tested in alkaline electrolyte for 10 hours to 24 hours in advance;

[0014] Step 2: Start the hot press to preheat the first metal electrode and the second metal electrode. When the temperature detector reaches the set temperature, the formal test phase can begin;

[0015] Step 3: Test the empty cell resistance. Connect the first and second metal electrode clips to the electrochemical workstation (EIS) test device. Apply a sinusoidal AC disturbance signal with an amplitude of 10 mV to the device. Set the frequency sweep range to 1 MHz to 1 Hz. Test the blank cell resistance R0. When R0 < 1 mΩ, the device has good contact and no obvious contact resistance. Turn off the hot press to cool it down.

[0016] Step 4: After the hot press cools down, the soaked composite film is placed on the pressure-bearing portion of the first metal electrode;

[0017] Step 5: Restart the hot press. When the temperature and pressure reach the set values ​​again, connect the first metal electrode clamp and the second metal electrode clamp to the electrochemical workstation test device EIS, apply a sinusoidal AC disturbance signal with an amplitude of 10mV to the device, set the frequency scanning range to 1MHz to 1Hz, test the resistance R, and multiply the test result R by the area of ​​the first metal electrode to obtain the surface resistance of the composite film.

[0018] Preferably, to increase the reliability of the measured sheet resistance of the composite membrane, the electrochemical workstation is used to scan three times and take the average value to obtain the sheet resistance value of one membrane. The sheet resistance of the three membranes is averaged to obtain the final sheet resistance of the composite membrane.

[0019] The advantages and beneficial effects of the present invention are:

[0020] This device, based on the variable temperature and voltage two-electrode method for measuring the sheet resistance of composite membranes, combines a testing unit with a hot press to measure the sheet resistance of composite membranes under variable temperature and voltage conditions, resulting in more reliable test results that meet testing requirements. By using this method to measure the sheet resistance of composite membranes, direct contact between the composite membrane and the electrodes eliminates the need for further alkali solution resistance removal, resulting in more accurate measurements. The device is easy to install, simple to operate, and offers high measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of the testing device of the present invention (the hot press is omitted);

[0022] Figure 2 This is a typical EIS curve diagram of the electrochemical test of the present invention;

[0023] Figure 3 Schematic diagram of the surface resistance test results of the present invention, wherein Figure (a) is the test result of the surface resistance change with pressure of membrane 1 at 80°C and 30wt% KOH; Figure (b) is the test result of the surface resistance change with pressure of membrane 2 at 80°C and 30wt% KOH; Figure (c) is the test result of the surface resistance change with pressure of membrane 3 at 80°C and 30wt% KOH; Figure (d) is the result of the surface resistance change with pressure after taking the average value of membrane 1, membrane 2, and membrane 3.

[0024] Description of Reference Numerals

[0025] 1-heating and pressurizing lower end plate, 2-first metal electrode, 3-first metal electrode clamp, 4-insulating sleeve, 5-second metal electrode clamp, 6-heating and pressurizing upper end plate, 7-second metal electrode, 8-test unit, 9-composite film to be tested, 10-temperature detector. Specific implementation methods

[0026] The present invention will be further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the scope of protection of the present invention cannot be limited thereto.

[0027] like Figure 1 As shown, a device for testing the surface resistance of a composite film based on a variable temperature and variable pressure two-electrode method includes a hot press. The device is innovative in that it also includes a testing unit 8, which includes a heated and pressurized upper end plate 6, a heated and pressurized lower end plate 1, a first metal electrode 2, a second metal electrode 7, a first metal electrode clamp 3, a second metal electrode clamp 5, and an insulating sleeve 4. The heated and pressurized upper end plate is mounted on the upper mounting plate of the hot press, the second metal electrode is mounted on the lower end surface of the heated and pressurized upper end plate, and the second metal electrode clamp is connected to the side of the second metal electrode. The second metal electrode includes an upper connecting portion and a pressure portion protruding downward from the middle of the upper connecting portion.

[0028] A heating and pressurizing lower end plate is installed on the lower mounting plate of the hot press, a first metal electrode is installed on the upper end surface of the heating and pressurizing lower end plate, a first metal electrode is connected to one side of the first metal electrode, and a probe connected to the temperature detector 10 is installed on the other side of the first metal electrode, the first metal electrode includes a lower connecting portion and a pressure-bearing portion protruding upward from the middle of the lower connecting portion, an insulating sleeve is sleeved on the outer ring of the pressure-bearing portion, the lower sleeve opening of the insulating sleeve is sleeved on the pressure-bearing portion, the upper end surface of the lower sleeve opening is lower than the upper end surface of the pressure-bearing portion, and the upper sleeve opening of the insulating sleeve is for the pressure-applying portion to expand and contract therein.

[0029] In this specific embodiment, the first metal electrode, first metal electrode clamp, second metal electrode, and second metal electrode clamp are made of copper. The composite membrane to be tested is made of Zirfon UTP 500, and the insulating sleeve is made of polytetrafluoroethylene. The heating and pressurizing functions of the upper and lower heating and pressurizing end plates are both achieved by a hot press. The pressure applied to the composite membrane is controlled by adjusting the pressure of the hot press, and the temperature of the composite membrane is regulated by heat transfer from the hot press's heating plate.

[0030] A method for testing the surface resistance of a composite film based on a variable temperature and voltage two-electrode method, the innovation of which lies in: comprising the following steps:

[0031] Zirfon UTP 500 was placed in a 30 wt% KOH solution and soaked for 24 h, so that the composite membrane was fully infiltrated by the alkali solution.

[0032] The temperature of the hot press was adjusted to 80°C. When the temperature detector reached 80°C, the first metal electrode clamp and the second metal electrode clamp were connected to the electrochemical workstation test device EIS. A sinusoidal AC disturbance signal with an amplitude of 10mV was applied, and the frequency sweep range was set to 1MHz to 1Hz. The blank resistance R was tested. 0, , R0 < 1mΩ, indicating that the device is well assembled with no significant contact resistance. Turn off the hot press.

[0033] The commercial membrane Zirfon UTP 500, which had been soaked in lye in advance, was cut into three 2×2 cm membranes, named membrane 1, membrane 2, and membrane 3. They were placed above the pressure-bearing part of the first metal electrode. The upper end surface area of ​​the pressure-bearing part of the first metal electrode was 2 cm. 2 The second metal electrode is placed directly above the composite membrane, and the end surface area of ​​the pressure-applying portion of the second metal electrode is 12.56 cm 2 .

[0034] Restart the hot press. When the temperature of the first metal electrode reaches 80°C again and the pressure reaches the specified value, connect the first metal electrode clamp and the second metal electrode clamp to the electrochemical workstation test device EIS. Apply a sinusoidal AC disturbance signal with an amplitude of 10mV to the device, set the frequency scanning range to 1MHz to 1Hz, test the resistance R, and then multiply the test result R by the area of ​​the first metal electrode to obtain the surface resistance of the composite film.

[0035] Use EIS to scan 3 times and take the average value. The typical image of EIS test results is as follows Figure 2 shown.

[0036] Test the surface resistance values ​​of film 2 and film 3, and take the average of the tested values. Figure 3 (d) shown.

[0037] From the test results, it can be seen that the surface resistance of the composite film Zirfon UTP 500 is 0.1-0.16Ωcm at 80℃ and 30wt% KOH. 2 The surface resistance changes little with increasing pressure, so it can be seen that the composite membrane Zirfon UTP500 has excellent compressive resistance and can better adapt to high-pressure hydrogen production conditions.

[0038] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A device for testing the surface resistance of a composite film based on a variable temperature and variable pressure two-electrode method, comprising a hot press, characterized in that: The hot press also includes a test unit, the test unit including a heating and pressurizing upper end plate, a heating and pressurizing lower end plate, a first metal electrode, a second metal electrode, a first metal electrode clamp, a second metal electrode clamp, and an insulating sleeve. The heating and pressurizing upper end plate is mounted on the upper mounting plate of the hot press, the second metal electrode is mounted on the lower end surface of the heating and pressurizing upper end plate, and the second metal electrode clamp is connected to the side of the second metal electrode. The second metal electrode includes an upper connecting portion and a pressure portion protruding downward from the middle portion of the upper connecting portion. A heating and pressurizing lower end plate is installed on the lower mounting plate of the hot press, a first metal electrode is installed on the upper end surface of the heating and pressurizing lower end plate, a first metal electrode is connected to one side of the first metal electrode, and a probe connected to the temperature detector is installed on the other side of the first metal electrode. The first metal electrode includes a lower connecting portion and a pressure-bearing portion protruding upward from the middle of the lower connecting portion. An insulating sleeve is sleeved on the outer ring of the pressure-bearing portion, the lower sleeve opening of the insulating sleeve is sleeved on the pressure-bearing portion, the upper end surface of the lower sleeve opening is lower than the upper end surface of the pressure-bearing portion, and the upper sleeve opening of the insulating sleeve is for the pressure-applying portion to expand and contract therein.

2. The device for testing the surface resistance of a composite film based on a variable temperature and voltage two-electrode method according to claim 1, characterized in that: Materials of the first metal electrode, the first metal electrode clip, the second metal electrode, and the second metal electrode clip include, but are not limited to, copper, iron, silver, and nickel.

3. The device for testing the surface resistance of a composite film based on a variable temperature and voltage two-electrode method according to claim 1, characterized in that: The material of the insulating sleeve includes but is not limited to polytetrafluoroethylene, polysulfone, polypropylene, epoxy resin, and acrylic.

4. The device for testing the surface resistance of a composite film based on a variable temperature and voltage two-electrode method according to claim 1, characterized in that: The end surface area of ​​the pressure-bearing portion on the first metal electrode is 1-5 cm 2 The end surface area of ​​the pressure portion of the second metal electrode is 10-20cm 2 .

5. A method for measuring the surface resistance of a composite film based on a variable temperature and voltage two-electrode method, characterized in that: The method is implemented based on the device for testing the surface resistance of the composite film based on the variable temperature and variable voltage two-electrode method described in any one of claims 1 to 4, and the method comprises the following steps: Step 1: soak the composite membrane to be tested in alkaline electrolyte for 10 hours to 24 hours in advance; Step 2: Start the hot press to preheat the first metal electrode and the second metal electrode. When the temperature detector reaches the set temperature, the formal test phase can begin; Step 3: Test the empty cell resistance. Connect the first and second metal electrode clips to the electrochemical workstation (EIS) test device. Apply a sinusoidal AC disturbance signal with an amplitude of 10 mV to the device. Set the frequency sweep range to 1 MHz to 1 Hz. Test the blank cell resistance R0. When R0 < 1 mΩ, the device has good contact and no obvious contact resistance. Then, turn off the device. Step 4, placing the soaked composite film on the pressure-bearing portion of the first metal electrode; Step 5: Restart the hot press. When the temperature and pressure reach the set values ​​again, connect the first metal electrode clamp and the second metal electrode clamp to the electrochemical workstation test device EIS, apply a sinusoidal AC disturbance signal with an amplitude of 10mV to the device, set the frequency scanning range to 1MHz to 1Hz, test the resistance R, and multiply the test result R by the area of ​​the first metal electrode to obtain the surface resistance of the composite film.

6. The method for measuring the surface resistance of a composite film based on a variable temperature and voltage two-electrode method according to claim 5, characterized in that: To increase the reliability of the measured sheet resistance of the composite membrane, the electrochemical workstation was used to scan three times and take the average value to obtain the sheet resistance value of one membrane. The sheet resistance of the three membranes was averaged to obtain the final sheet resistance of the composite membrane.

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