Fuel cell membrane electrode, preparation method and application

Abstract

The invention belongs to the technical field of fuel cell materials, and particularly relates to a fuel cell membrane electrode, a preparation method and application. The fuel cell membrane electrode comprises a gas diffusion electrode and a self-supporting active component attached to the surface of the electrode, the gas diffusion electrode is foamed nickel, and the self-supporting active component is NiFeZnCoPt high-entropy metal alloy; and the atom ratio of a single metal element in the high-entropy metal alloy is 5-30%. The preparation method comprises the following steps that S1, foamed nickel is put into a hydrochloric acid solution to be soaked, deionized water and ethyl alcohol are sequentially used for ultrasonic cleaning, and the cleaned foamed nickel is put into a drying oven to be dried for use; s2, NiCl2. 6H2O, FeCl3. 6H2O, ZnCl2, CoCl2. 6H2O and PtCl2 are dissolved in deionized water, ammonium fluoride and urea are sequentially added, and a mixed solution is obtained after magnetic stirring is conducted; and S3, putting the cleaned foamed nickel into the mixed solution, putting the mixed solution into a high-pressure reaction kettle for reaction, cooling to room temperature after the reaction is finished, and centrifuging, cleaning and drying to obtain the fuel cell membrane electrode.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cell materials, and in particular relates to a fuel cell membrane electrode, a preparation method and an application thereof. Background Art

[0002] Reducing dependence on fossil fuels and reducing greenhouse gas emissions are indispensable measures to address climate change and environmental issues. Ammonia, as a high-energy-density carbon-free hydrogen storage medium, has the advantages of high energy density, easy liquefaction storage and transportation, high safety and no carbon emissions. Direct ammonia fuel cells can directly use ammonia to generate electricity at the anode, and ammonia is directly electrochemically oxidized into nitrogen and water, while releasing electricity. This is a potential power generation technology.

[0003] However, in practical applications, the poor interface between the catalyst layer and the gas diffusion layer will lead to hysteresis in the diffusion kinetics of reactants / products; at the same time, the physical bonding between the two interfaces will increase the interface contact resistance, which is not conducive to electron transport. Therefore, the contact ohmic loss at the catalyst layer / gas diffusion layer interface has become one of the main intrinsic reasons for the poor performance of direct ammonia fuel cells. Compared with conventional supported catalysts, the use of nickel foam as the gas diffusion electrode and the preparation of the high entropy metal alloy catalyst layer by in-situ polymerization growth can reduce the interface impedance and greatly improve the performance of direct ammonia fuel cells. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention can be achieved through the following technical solutions:

[0005] A fuel cell membrane electrode, comprising: a gas diffusion electrode and a self-supporting active component attached to the surface of the electrode, the gas diffusion electrode is nickel foam, and the self-supporting active component is a NiFeZnCoPt high-entropy metal alloy; the atomic proportion of a single metal element in the high-entropy metal alloy is 5-30%.

[0006] A method for preparing a fuel cell membrane electrode, the method comprising the following steps:

[0007] S1, soaking the nickel foam in a hydrochloric acid solution, then ultrasonically cleaning with deionized water and ethanol in sequence, and then drying the cleaned nickel foam in an oven for later use;

[0008] S2, NiCl 2 6H 2 O, FeCl 3 6H 2 O、ZnCl 2 、CoCl 2 6H 2 O、PtCl 2Dissolve in deionized water, then add ammonium fluoride and urea in sequence, and obtain a mixed solution after magnetic stirring;

[0009] S3, putting the cleaned nickel foam in step S1 into the mixed solution, and then placing it in a high-pressure reactor for reaction. After the reaction is completed, it is cooled to room temperature, and then centrifuged, washed, and dried to obtain a fuel cell membrane electrode.

[0010] Furthermore, the concentration of the hydrochloric acid solution is 1 mol / L.

[0011] Furthermore, in step S1, the ultrasonic cleaning time of the deionized water and ethanol solution is 10-60 minutes; during drying, the temperature in the oven is 50-70° C., and the drying time is 1-2 hours.

[0012] Further, in step S2, NiCl 2 6H 2 O, FeCl 3 6H 2 O、ZnCl 2 、CoCl 2 6H 2 O and PtCl 2 The molar ratio of substances is (0.1-2):(0.1-2):(0.1-2):(0.1-2):(0.1-2).

[0013] Furthermore, the amount of ammonium fluoride added is (0.5-1.5) g, and the amount of urea added is (0.5-1.5) g.

[0014] Furthermore, the reaction conditions in the high-pressure reactor in step S3 are: reaction temperature is 110-140° C., and reaction time is 6-18 hours.

[0015] Furthermore, in step S3, the rotation speed during centrifugation is 6000-10000 rpm, and the centrifugation time is 1-2 h.

[0016] Furthermore, in step S3, the washing is performed with deionized water for 3 to 5 times, and the drying conditions are: the temperature is 60 to 80° C., and the drying time is 6 to 12 hours.

[0017] The fuel cell membrane electrode described above is used as electrolysis in an electrolytic cell for ammonia oxidation power generation.

[0018] Beneficial effects of the present invention: The raw materials required for the membrane electrode preparation method provided in the present application are all bulk commercial products and the cost is relatively low.

[0019] The preparation method for a direct ammonia fuel cell membrane electrode provided in the present application has the advantages of simple and safe preparation process, and is easy to achieve large-scale preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a scanning electron microscope image of Example 1.

[0022] Figure 2 These are the performance test results of the membrane electrode in Example 1 and Comparative Examples 1-2 used in direct ammonia fuel cells. DETAILED DESCRIPTION

[0023] 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 creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] Put nickel foam into 1 mol L -1 The nickel foam was placed in a 60°C oven and dried for 1 hour. 4 mmol NiCl 2 6H 2 O, 4mmol FeCl 3 6H 2 O, 4mmol ZnCl 2 、4mmol CoCl 2 6H 2 O, 4mmol PtCl 2 Dissolve in 80mL deionized water. Then add 0.463g ammonium fluoride and 0.75g urea to the above solution, stir magnetically for 30min, transfer the obtained solution to a 100ml autoclave, and immerse a piece of the above washed nickel foam into the solution. After sealing, react at 130°C for 8 hours. After cooling to room temperature, collect by centrifugation at 800rpm, wash 3 times with deionized water, and then dry at 60°C for 8h to obtain a fuel cell membrane electrode.

[0026] Comparative Example 1

[0027] Put nickel foam into 1 mol L -1 The nickel foam was placed in a 60°C oven and dried for 1 hour. 4 mmol NiCl 2 6H 2 O, 3mmol FeCl 3 6H 2 O, 1mmol ZnCl 2 、2mmol CoCl 2 6H 2 O, 4mmol PtCl 2 Dissolve in 80mL deionized water. Then add 0.463g ammonium fluoride and 0.75g urea to the above solution, stir magnetically for 30min, transfer the obtained solution to a 100ml autoclave, and immerse a piece of the above washed nickel foam into the solution. After sealing, react at 130°C for 8 hours. After cooling to room temperature, collect by centrifugation at 800rpm, wash 3 times with deionized water, and then dry at 60°C for 8h to obtain a fuel cell membrane electrode.

[0028] Comparative Example 2

[0029] Put nickel foam into 1 mol L -1 The nickel foam was placed in a 60°C oven and dried for 1 hour. 1 mmol NiCl 2 6H 2 O, 4mmol FeCl 3 6H 2 O, 3mmol ZnCl 2 、4mmol CoCl 2 6H 2 O, 2mmol PtCl 2 Dissolve in 80mL deionized water. Then add 0.463g ammonium fluoride and 0.75g urea to the above solution, stir magnetically for 30min, transfer the obtained solution to a 100ml autoclave, and immerse a piece of the above washed nickel foam into the solution. After sealing, react at 130°C for 8 hours. After cooling to room temperature, collect by centrifugation at 800rpm, wash 3 times with deionized water, and then dry at 60°C for 8h to obtain a fuel cell membrane electrode.

[0030] Performance testing:

[0031] The materials prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were assembled into fuel cells and the air tightness was checked:

[0032] Place the single cell in the temperature control measurement subsystem, and wire for voltage measurement, current extraction, temperature measurement, mechanical load, etc., and pipe for gas input and exhaust, and connect the lines to the corresponding subsystems.

[0033] Measure the resistance between the cathode and anode current collector current lead-out points to determine whether there is a short circuit; measure the resistance between the battery voltage measurement points to determine whether there is electrical insulation;

[0034] Check and ensure electrical insulation between the thermocouple and the single cell, and between the mechanical load-applying device and the single cell; check the air tightness of the gas pipelines in the single cell and the test system, using the pressure holding method or the nitrogen leak detection method;

[0035] Battery temperature reduction and activation

[0036] According to the temperature raising program, the temperature is raised from room temperature to the reduction temperature, and nitrogen is introduced during the temperature raising process;

[0037] During the insulation process, gas is introduced into the anode and cathode for purging. Nitrogen is introduced into the anode and air is introduced into the cathode. The pressure maintenance method is used to detect whether there is gas leakage.

[0038] Reduction: gradually switch the anode gas composition to hydrogen, keep the cathode gas composition to air, and record the open circuit voltage, total resistance, thermocouple reading, time and other data every 30 seconds;

[0039] Observe the change of open circuit voltage over time during the reduction process to determine whether to conduct subsequent tests:

[0040] If the reduction requirement is met (the difference between the open circuit voltage and the thermodynamic equilibrium voltage is no more than 50 mV and is maintained in a stable state for more than 2 hours), the battery performance test is performed; if the above requirements are not met, the test is stopped;

[0041] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0042] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A fuel cell membrane electrode, characterized in that: The fuel cell membrane electrode comprises: a gas diffusion electrode and a self-supporting active component attached to the surface of the electrode, the gas diffusion electrode is nickel foam, and the self-supporting active component is a NiFeZnCoPt high entropy metal alloy; the atomic proportion of a single metal element in the high entropy metal alloy is 5-30%.

2. A method for preparing a fuel cell membrane electrode, characterized in that: The preparation method comprises the following steps: S1, soaking the nickel foam in a hydrochloric acid solution, then ultrasonically cleaning with deionized water and ethanol in sequence, and then drying the cleaned nickel foam in an oven for later use; S2, dissolving NiCl2·6H2O, FeCl3·6H2O, ZnCl2, CoCl2·6H2O, and PtCl2 in deionized water, then sequentially adding ammonium fluoride and urea, and obtaining a mixed solution after magnetic stirring; S3, putting the cleaned nickel foam in step S1 into the mixed solution, and then placing it in a high-pressure reactor for reaction. After the reaction is completed, it is cooled to room temperature, and then centrifuged, washed, and dried to obtain a fuel cell membrane electrode.

3. The method for preparing a fuel cell membrane electrode according to claim 2, characterized in that: The concentration of the hydrochloric acid solution is 1 mol / L.

4. The method for preparing a fuel cell membrane electrode according to claim 2, characterized in that: In step S1, the ultrasonic cleaning time of deionized water and ethanol solution is 10-60 minutes; during drying, the temperature in the oven is 50-70° C. and the drying time is 1-2 hours.

5. The method for preparing a fuel cell membrane electrode according to claim 2, characterized in that: In step S2, the molar ratios of NiCl2·6H2O, FeCl3·6H2O, ZnCl2, CoCl2·6H2O and PtCl2 are (0.1-2): (0.1-2): (0.1-2): (0.1-2).

6. The method for preparing a fuel cell membrane electrode according to claim 2, characterized in that: The amount of ammonium fluoride added is (0.5-1.5) g, and the amount of urea added is (0.5-1.5) g.

7. The method for preparing a fuel cell membrane electrode according to claim 2, characterized in that: The reaction conditions in the high-pressure reactor in step S3 are: reaction temperature is 110-140° C., and reaction time is 6-18 hours.

8. The method for preparing a fuel cell membrane electrode according to claim 2, characterized in that: The rotation speed during centrifugation in step S3 is 6000-10000 rpm, and the centrifugation time is 1-2 hours.

9. The method for preparing a fuel cell membrane electrode according to claim 2, characterized in that: In step S3, the washing is performed with deionized water for 3 to 5 times, and the drying conditions are: the temperature is 60 to 80° C. and the drying time is 6 to 12 hours.

10. A fuel cell membrane electrode as claimed in claim 1 is used for electrolysis in an electrolytic cell for ammonia oxidation power generation.

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