CN114725410B - Catalytic layer slurry, preparation method and preparation method of catalytic layer membrane electrode - Google Patents

Catalytic layer slurry, preparation method and preparation method of catalytic layer membrane electrode Download PDF

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Publication number
CN114725410B
CN114725410B CN202210333481.2A CN202210333481A CN114725410B CN 114725410 B CN114725410 B CN 114725410B CN 202210333481 A CN202210333481 A CN 202210333481A CN 114725410 B CN114725410 B CN 114725410B
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catalytic layer
catalyst
layer slurry
dimethylformamide
ultrasonic dispersion
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CN114725410A (en
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唐雪君
李洪涛
高佳武
曹天鹏
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Dongfeng Motor Corp
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Dongfeng Motor Corp
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/86Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90Selection of catalytic material
    • H01M4/92Metals of platinum group
    • H01M4/921Alloys or mixtures with metallic elements
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/86Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88Processes of manufacture
    • H01M4/8825Methods for deposition of the catalytic active composition
    • H01M4/8828Coating with slurry or ink
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/86Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88Processes of manufacture
    • H01M4/8878Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
    • H01M4/8882Heat treatment, e.g. drying, baking
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30Hydrogen technology
    • Y02E60/50Fuel cells

Abstract

The invention particularly relates to a catalytic layer slurry, a preparation method and a preparation method of a catalytic layer membrane electrode, and belongs to the technical field of proton exchange membrane fuel cells. The catalyst layer slurry comprises Pt/C catalyst, deionized water, N dimethylformamide mixture and Nafion solution. The N, N-dimethylformamide with excellent dispersibility on the Pt/C catalyst and high boiling point and low viscosity is added into the raw materials, so that the phenomenon that Pt/C catalyst particles are agglomerated due to the fact that only water remains in the later period of drying is avoided, meanwhile, the N, N-dimethylformamide can be automatically removed in the drying process, the solvent is prevented from covering the surface of an active site of the catalyst, and the reduction of the power generation performance of an electrode is effectively avoided.

Description

Catalytic layer slurry, preparation method and preparation method of catalytic layer membrane electrode
Technical Field
The invention belongs to the technical field of proton exchange membrane fuel cells, and particularly relates to a catalytic layer slurry, a preparation method and a preparation method of a catalytic layer membrane electrode.
Background
Efficient transport of hydrogen, oxygen, electrons, protons and water within a proton exchange membrane fuel cell is of exceptional importance for the power generation performance of the catalytic layer. Transport of such materials is primarily affected by the microstructure of the catalytic layer, such as the pore structure of the diffusion gas, the structure of the electron conducting carbon particles, and proton conducting ion channels in the ionomer. In general, the catalytic layer is prepared by preparing a slurry of Pt/C catalyst, ionomer and solvent, and drying, and the structure of the catalytic layer is formed during the drying of the slurry.
Macroscopically, cracking of the catalytic layer has an adverse effect on the mechanical durability of the fuel cell. During operation, the crack area of the catalytic layer can be flooded, so that the proton membrane is cracked. The rupture of the proton membrane causes gas leakage, and the oxyhydrogen generates chemical reaction to cause the attenuation of the membrane electrode. Therefore, in order to improve the durability of the membrane electrode, it is necessary to avoid the occurrence of cracks during the formation of the catalytic layer.
The type of solvent has an important influence on the crack formation or not of the catalytic layer. For the conventional catalyst slurry which only uses low-boiling-point alcohol/water mixture as a solvent, in the drying process, solvent components can be changed from the alcohol/water mixture with good dispersibility to water with poor dispersibility due to different boiling points, so that Pt/C particles are agglomerated at the later stage of the drying process, and cracks appear around the agglomerates due to stress concentration. By adding a high-boiling point and high-viscosity solvent such as propylene glycol, glycerin, ethylene glycol and the like, the occurrence of this phenomenon can be effectively avoided, and the formation of cracks in the catalytic layer can be suppressed. However, the solvent with high viscosity is difficult to remove and is adsorbed on the surface of the catalyst, so that the electrochemical active area of the electrode is reduced, and the performance of the electrode of the proton exchange membrane fuel cell is not exerted.
Disclosure of Invention
The purpose of the application is to provide a catalyst layer slurry to solve the technical problem that a high-viscosity solvent is easy to adsorb on the surface of a catalyst and difficult to remove in the prior art.
The embodiment of the invention provides a catalytic layer slurry, and the raw materials of the catalytic layer slurry comprise a Pt/C catalyst, deionized water, an N, N dimethylformamide mixture and a Nafion solution.
Optionally, the N, N dimethylformamide mixture comprises N, N dimethylformamide and isopropanol.
Optionally, the mass fraction of the solid matters in the catalyst layer slurry is 1-5%.
Optionally, the ratio of the mass of Nafion to the mass of C in the Pt/C catalyst is (0.4-1.4): 1.
Optionally, the mass ratio of deionized water to the mixture of N, N dimethylformamide is 1: (2.5-6).
The mass ratio of the N, N dimethylformamide to the isopropanol is 1: (3-7).
Optionally, the viscosity of the catalyst layer slurry is 1.65-2.30 mpa.s.
Based on the same inventive concept, the embodiment of the invention also provides a preparation method of any one of the catalytic layer slurries, comprising the following steps:
wetting the Pt/C catalyst by deionized water, and mixing the Pt/C catalyst with an N, N-dimethylformamide mixture and a Nafion solution to obtain a premix;
protecting the premixed solution for a preset time by inert gas to obtain a protection solution;
and under the condition of maintaining the protection of the inert gas, the protection liquid is sheared at high speed and dispersed in an ultrasonic way under the ice bath condition, so that the catalytic layer slurry is obtained.
Optionally, the predetermined time is 30-60min.
Optionally, the temperature of the ice bath is < 5 ℃.
Optionally, the rotating speed of the high-speed shearing is 3000-20000r/min, and the time of the high-speed shearing is 10-60min.
Optionally, the ultrasonic dispersion comprises water bath ultrasonic dispersion and probe ultrasonic dispersion, wherein the power of the ultrasonic dispersion is 300-600W, and the time of the ultrasonic dispersion is 30-90min.
Based on the same inventive concept, the embodiment of the invention also provides a preparation method of the catalytic layer membrane electrode, which comprises the following steps:
obtaining a proton exchange membrane;
fixing the proton exchange membrane on a vacuum heating table;
spraying the catalyst layer slurry on the surface of the proton exchange membrane and drying to obtain the catalyst layer membrane electrode.
Optionally, the thickness of the sprayed catalytic layer slurry is 5-10 μm.
Optionally, the temperature of the vacuum heating table is 80-100 ℃.
One or more technical solutions in the embodiments of the present invention at least have the following technical effects or advantages:
according to the catalyst layer slurry provided by the embodiment of the invention, the N, N-dimethylformamide with excellent dispersibility on the Pt/C catalyst and high boiling point and low viscosity is added into the raw materials, so that the phenomenon that the Pt/C catalyst particles are agglomerated due to the fact that only water remains in the later stage of drying is avoided, meanwhile, the N, N-dimethylformamide can be automatically removed in the drying process, the solvent is prevented from covering the surface of the active site of the catalyst, and the reduction of the power generation performance of the electrode is effectively avoided.
The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present invention more readily apparent.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method provided by an embodiment of the present invention;
FIG. 2 is an infrared spectrum of N, N-dimethylformamide;
FIG. 3 is an infrared spectrum of a catalytic layer of the catalytic layer membrane electrode provided in example 1;
FIG. 4 is an infrared spectrum of propylene glycol;
FIG. 5 is an infrared spectrum of a catalytic layer of the catalytic layer membrane electrode provided in comparative example 1;
FIG. 6 is a polarization curve of the catalytic layer membrane electrode provided in examples 1-5;
fig. 7 is a polarization curve of the catalytic layer membrane electrodes provided in comparative examples 1-9.
Detailed Description
The advantages and various effects of the present invention will be more clearly apparent from the following detailed description and examples. It will be understood by those skilled in the art that these specific embodiments and examples are intended to illustrate the invention, not to limit the invention.
Throughout the specification, unless specifically indicated otherwise, the terms used herein should be understood as meaning as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification will control. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the scope of the present invention. For example, room temperature may refer to a temperature in the range of 10 to 35 ℃.
Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or may be prepared by existing methods.
The technical scheme of the embodiment of the application aims to solve the technical problems, and the overall thought is as follows:
according to an exemplary embodiment of the present invention, there is provided a catalytic layer slurry, raw materials of which include Pt/C catalyst, deionized water, N dimethylformamide mixture, and Nafion solution.
The catalyst layer slurry has excellent dispersibility on the Pt/C catalyst, and the N, N-dimethylformamide with high boiling point and low viscosity is added into the solvent of the raw material, so that the phenomenon that Pt/C catalyst particles are agglomerated due to the fact that only water remains in the later period of drying is avoided, meanwhile, the N, N-dimethylformamide can be automatically removed in the drying process, the solvent is prevented from covering the surface of the active site of the catalyst, and the reduction of the power generation performance of the electrode is effectively avoided.
Specifically, the mechanism by which N, N-dimethylformamide can be automatically removed in the drying process is as follows: the viscosity of the N, N-dimethylformamide is far lower than that of high-viscosity solvents such as propylene glycol, and the N, N-dimethylformamide can quickly migrate from the inside of the catalytic layer to the surface layer and volatilize in the heating and drying process. In the case of high-viscosity solvents such as propylene glycol, the migration rate from the inside of the catalytic layer to the surface layer is slow, so that the volatilization resistance of the internal solvent is increased after the surface layer material is shrunk, and the internal solvent cannot be completely removed.
As an alternative embodiment, the N, N dimethylformamide mixture includes N, N dimethylformamide and isopropanol.
The isopropanol has the following functions: dispersing the catalyst and Nafion solution, and quickly volatilizing during spraying and subsequent drying in the catalyst slurry to form mass transfer channels in the catalytic layer.
As an alternative embodiment, in the catalytic layer slurry:
the mass fraction of the solid matters is 1-5%;
the ratio of the mass of Nafion to the mass of C in the Pt/C catalyst is (0.4-1.4): 1;
the mass ratio of the deionized water to the N, N dimethylformamide mixture is 1: (2.5-6);
the mass ratio of the N, N dimethylformamide to the isopropanol is 1: (3-7).
The reason for controlling the above ratios is that: (1) If the mass fraction of the solid matters is too low, the spraying times are required to be increased to achieve a certain loading, so that the spraying efficiency is low; if the mass fraction of the solid matters is too high, the viscosity of the slurry is too high, which is not beneficial to the spraying effect; in conclusion, the mass fraction of the selected solid matters is 1-5%; (2) Nafion acts to transport protons but causes some resistance to oxygen transport. If the ratio of the mass of Nafion to the mass of C is too low, then adequate proton transfer channels cannot be formed; the ratio of the mass of Nafion to the mass of C is too high, which is easy to cause oxygen transmission blockage; in sum, the ratio of the mass of Nafion to the mass of C is (0.4-1.4): 1; (3) Isopropyl alcohol has a low boiling point and is more volatile than water and N, N dimethylformamide. If the mass ratio of N, N dimethylformamide to isopropanol is too high, the drying speed of the slurry of the catalytic layer is too slow, the spraying efficiency is reduced, and the phenomenon of increasing the swelling degree of the film is easy to occur; the mass ratio of N, N dimethylformamide to isopropanol is too low, so that the phenomenon that only water remains in the later drying stage and Pt/C catalyst particles are agglomerated is easily caused; in summary, the mass ratio of N, N dimethylformamide to isopropanol is selected to be 1: (3-7).
As an alternative embodiment, the viscosity of the catalytic layer slurry is 1.65-2.30 mPa-s.
According to an exemplary embodiment of the present invention, there is provided a method for preparing the above-mentioned catalytic layer slurry, including the steps of:
s1, wetting the Pt/C catalyst by deionized water, and mixing the Pt/C catalyst with an N, N-dimethylformamide mixture and a Nafion solution to obtain a premix.
The reason for wetting the Pt/C catalyst is: the catalyst is prevented from being in direct contact with isopropanol to cause carbon combustion reaction, so that Pt particles are prevented from falling off and agglomerating.
The reason for controlling the mass ratio of deionized water to the N, N dimethylformamide mixture is as follows: the addition of water increases the dielectric constant of the solvent and improves the dispersibility of nafion. If the water content is too low, the nafion is not easy to disperse in the solvent, and a uniform proton transmission network cannot be formed; if the water content is too high, the dispersion effect on the catalyst is poor, the catalyst particles are easy to agglomerate, and a sufficient electrochemical reaction interface cannot be provided. To sum up, the mass ratio of deionized water to the N, N-dimethylformamide mixture is controlled to be 1:
(2.5-6)。
s2, protecting the premixed solution by inert gas for a preset time to obtain a protection solution.
Wherein: the predetermined time is 30-60min.
The reason why the subsequent operation (high-speed shearing and ultrasonic dispersion) can be performed after the inert gas is used for a predetermined time is that: oxygen is prevented from being mixed in a system in the subsequent operation process, so that the Pt catalyzes the isopropanol to react with the oxygen to release heat, and the carbon carrier is combusted, thereby causing the falling off and agglomeration of Pt particles.
And S3, under the condition of maintaining the protection of the inert gas, carrying out high-speed shearing and ultrasonic dispersion on the protection liquid under the ice bath condition to obtain the catalytic layer slurry.
Wherein:
the temperature of the ice bath is less than 5 ℃.
The rotating speed of the high-speed shearing is 3000-20000r/min, and the time of the high-speed shearing is 10-60min.
The ultrasonic dispersion comprises water bath ultrasonic dispersion and probe ultrasonic dispersion, wherein the power of the ultrasonic dispersion is 300-600W, and the time of the ultrasonic dispersion is 30-90min.
The ice bath has the following functions: the high-speed shearing and ultrasonic dispersing processes can generate heat, the ice bath can control the temperature of a reaction system, and the agglomeration of carbon particles at high temperature is avoided, so that the slurry dispersing effect is prevented from being influenced.
The functions of high-speed shearing and ultrasonic dispersion are respectively as follows: the high-speed shearing grinds the slurry of the catalytic layer from the micron level to the submicron level mainly by the principle of collision and shearing; ultrasonic dispersion refines the slurry from submicron level to less than 500nm level mainly through ultrasonic crushing and cavitation, and the particle size distribution of the slurry is more concentrated.
The reason for controlling the above parameter ranges is that: the rotating speed of high-speed shearing is too low or the power of ultrasonic dispersion is too low, so that the slurry dispersion effect is affected; the high-speed shearing rotating speed is too high, or the ultrasonic dispersing power is too high, so that the local temperature of a slurry system is easily caused to be too high; in conclusion, the rotating speed of high-speed shearing is set to be 3000-20000r/min, and the power of ultrasonic dispersion is 300-600W. The high-speed shearing or ultrasonic dispersing time is too short, so that the slurry dispersing effect is affected; the high-speed shearing or ultrasonic dispersing time is too long, so that the slurry dispersing efficiency is reduced; in conclusion, the high-speed shearing time is set to be 10-60min, and the ultrasonic dispersing time is set to be 30-90min.
According to another exemplary embodiment of the present invention, there is provided a method for preparing a catalytic layer membrane electrode, including the steps of:
s4, obtaining the proton exchange membrane.
S5, fixing the proton exchange membrane on a vacuum heating table at the temperature of 80-100 ℃.
And S6, spraying any one of the catalytic layer slurries on the surface of the proton exchange membrane and drying to obtain the catalytic layer membrane electrode.
Wherein: the thickness of the sprayed catalyst layer slurry is 5-10 mu m.
The present application will be described in detail with reference to examples, comparative examples and experimental data.
Example 1
This example provides a catalytic layer slurry whose raw materials included 1g of 50wt.% commercial Pt/C catalyst, 7.04g deionized water, 8.49g n, n dimethylformamide, 42.47g isopropyl alcohol, 6g5wt.% Nafion solution.
The embodiment also provides a preparation method of the catalytic layer slurry, which comprises the following steps:
s1, after 1g of 50wt.% commercial Pt/C catalyst was wetted with 7.04g deionized water, it was mixed with 8.49g N, N dimethylformamide, 42.47g isopropyl alcohol, 6g5wt.% Nafion solution to give a premix.
S2, protecting the premix liquid by nitrogen for 30min to obtain a protection liquid.
And S3, under the condition of maintaining the nitrogen protection, the protective liquid is sheared at high speed and dispersed by ultrasound under the ice bath condition, so as to obtain the catalytic layer slurry.
Wherein:
the temperature of the ice bath is less than 5 ℃;
the rotating speed of high-speed shearing is 10000r/min, and the time of high-speed shearing is 30min;
the ultrasonic dispersion comprises water bath ultrasonic dispersion and probe ultrasonic dispersion, the power of the ultrasonic dispersion is 500W, and the time of the ultrasonic dispersion is 30min.
The embodiment also provides a preparation method of the catalytic layer membrane electrode, which comprises the following steps:
s4, obtaining the commercial proton exchange membrane.
S5, fixing the commercial proton exchange membrane on a vacuum heating table at 100 ℃.
And S6, spraying the catalyst layer slurry on the surface of the proton exchange membrane and drying to obtain the catalyst layer membrane electrode.
Wherein: the thickness of the sprayed catalyst layer slurry was 5.3 μm.
Example 2
This example provides a catalytic layer slurry whose raw materials include 1g of 50wt.% commercial Pt/C catalyst, 3.72g deionized water, 8.49g n, n dimethylformamide, 25.46g isopropyl alcohol, 8g5wt.% Nafion solution.
The embodiment also provides a preparation method of the catalytic layer slurry, which comprises the following steps:
s1, after 1g of 50wt.% commercial Pt/C catalyst was wetted with 3.72g deionized water, it was mixed with 8.49g N, N dimethylformamide, 25.46g isopropyl alcohol, 8g5wt.% Nafion solution to give a premix.
S2, protecting the premix liquid by nitrogen for 40min to obtain a protection liquid.
And S3, under the condition of maintaining the nitrogen protection, the protective liquid is sheared at high speed and dispersed by ultrasound under the ice bath condition, so as to obtain the catalytic layer slurry.
Wherein:
the temperature of the ice bath is less than 5 ℃;
the rotating speed of high-speed shearing is 8000r/min, and the time of high-speed shearing is 20min;
the ultrasonic dispersion comprises water bath ultrasonic dispersion and probe ultrasonic dispersion, the power of the ultrasonic dispersion is 300W, and the time of the ultrasonic dispersion is 90min.
The embodiment also provides a preparation method of the catalytic layer membrane electrode, which comprises the following steps:
s4, obtaining the commercial proton exchange membrane.
S5, fixing the commercial proton exchange membrane on a vacuum heating table at 80 ℃.
And S6, spraying the catalyst layer slurry on the surface of the proton exchange membrane and drying to obtain the catalyst layer membrane electrode.
Wherein: the thickness of the sprayed catalyst layer slurry was 6. Mu.m.
Example 3
This example provides a catalytic layer slurry whose raw materials include 1g of 30wt.% commercial Pt/C catalyst, 6.19g deionized water, 9.08g n, n dimethylformamide, 36.33g isopropyl alcohol, 12.6g5wt.% Nafion solution.
The embodiment also provides a preparation method of the catalytic layer slurry, which comprises the following steps:
s1, after 1g of 30wt.% commercial Pt/C catalyst was wetted with 6.19g deionized water, it was mixed with 9.08g N, N dimethylformamide, 36.33g isopropyl alcohol, 12.6g5wt.% Nafion solution to give a premix.
S2, protecting the premix liquid by nitrogen for 50min to obtain a protection liquid.
And S3, under the condition of maintaining the nitrogen protection, the protective liquid is sheared at high speed and dispersed by ultrasound under the ice bath condition, so as to obtain the catalytic layer slurry.
Wherein:
the temperature of the ice bath is less than 5 ℃;
the rotating speed of high-speed shearing is 15000r/min, and the time of high-speed shearing is 10min;
the ultrasonic dispersion comprises water bath ultrasonic dispersion and probe ultrasonic dispersion, the power of the ultrasonic dispersion is 400W, and the time of the ultrasonic dispersion is 60min.
The embodiment also provides a preparation method of the catalytic layer membrane electrode, which comprises the following steps:
s4, obtaining the commercial proton exchange membrane.
S5, fixing the commercial proton exchange membrane on a vacuum heating table at 90 ℃.
And S6, spraying the catalyst layer slurry on the surface of the proton exchange membrane and drying to obtain the catalyst layer membrane electrode.
Wherein: the thickness of the sprayed catalytic layer slurry was 7.5 μm.
Example 4
This example provides a catalytic layer slurry whose raw materials include 1g of 20wt.% commercial Pt/C catalyst, 10.94g deionized water, 9.38g n, n dimethylformamide, 56.28g isopropyl alcohol, 22.4g5wt.% Nafion solution.
The embodiment also provides a preparation method of the catalytic layer slurry, which comprises the following steps:
s1, after 1g of 30wt.% commercial Pt/C catalyst was wetted with 10.94g deionized water, it was mixed with 9.38g N, N dimethylformamide, 56.28g isopropyl alcohol, 22.4g5wt.% Nafion solution to give a premix.
S2, protecting the premix liquid by nitrogen for 60min to obtain a protection liquid.
And S3, under the condition of maintaining the nitrogen protection, the protective liquid is sheared at high speed and dispersed by ultrasound under the ice bath condition, so as to obtain the catalytic layer slurry.
Wherein:
the temperature of the ice bath is less than 5 ℃;
the rotating speed of high-speed shearing is 3000r/min, and the time of high-speed shearing is 60min;
the ultrasonic dispersion comprises water bath ultrasonic dispersion and probe ultrasonic dispersion, the power of the ultrasonic dispersion is 600W, and the time of the ultrasonic dispersion is 30min.
The embodiment also provides a preparation method of the catalytic layer membrane electrode, which comprises the following steps:
s4, obtaining the commercial proton exchange membrane.
S5, fixing the commercial proton exchange membrane on a vacuum heating table at the temperature of 95 ℃.
And S6, spraying the catalyst layer slurry on the surface of the proton exchange membrane and drying to obtain the catalyst layer membrane electrode.
Wherein: the thickness of the sprayed catalyst layer slurry was 8. Mu.m.
Example 5
This example provides a catalytic layer slurry whose starting materials include 1g of 60wt.% commercial Pt/C catalyst, 3.51g deionized water, 1.54g n, n dimethylformamide, 10.78g isopropyl alcohol, 3.2g5wt.% Nafion solution.
The embodiment also provides a preparation method of the catalytic layer slurry, which comprises the following steps:
s1, after 1g of 30wt.% commercial Pt/C catalyst was wetted with 3.51g deionized water, it was mixed with 1.54g N, N dimethylformamide, 10.78g isopropyl alcohol, 3.2g5wt.% Nafion solution to give a premix.
S2, protecting the premix liquid by nitrogen for 50min to obtain a protection liquid.
And S3, under the condition of maintaining the nitrogen protection, the protective liquid is sheared at high speed and dispersed by ultrasound under the ice bath condition, so as to obtain the catalytic layer slurry.
Wherein:
the temperature of the ice bath is less than 5 ℃;
the rotating speed of high-speed shearing is 20000r/min, and the time of high-speed shearing is 60min;
the ultrasonic dispersion comprises water bath ultrasonic dispersion and probe ultrasonic dispersion, the power of the ultrasonic dispersion is 400W, and the time of the ultrasonic dispersion is 40min.
The embodiment also provides a preparation method of the catalytic layer membrane electrode, which comprises the following steps:
s4, obtaining the commercial proton exchange membrane.
S5, fixing the commercial proton exchange membrane on a vacuum heating table at 85 ℃.
And S6, spraying the catalyst layer slurry on the surface of the proton exchange membrane and drying to obtain the catalyst layer membrane electrode.
Wherein: the thickness of the sprayed catalyst layer slurry was 10. Mu.m.
Comparative example 1
The only difference from example 1 is that: the mixed solution of N, N dimethylformamide and isopropanol is replaced by the mixed solution of propylene glycol and isopropanol, and the addition amount of the propylene glycol is adaptively adjusted according to the prior art.
Comparative example 2
The only difference from example 1 is that: step S2 is canceled.
Comparative example 3
The only difference from example 1 is that: in step S3, the ice bath condition is not used.
Comparative example 4
The only difference from example 1 is that: in the step S3, the rotating speed of high-speed shearing is 30000r/min, and the time of high-speed shearing is 5min.
Comparative example 5
The only difference from example 1 is that: in the step S3, the rotating speed of high-speed shearing is 2500r/min, and the time of high-speed shearing is 70min.
Comparative example 6
The only difference from example 1 is that: in step S3, the power of the ultrasonic dispersion is 200W, and the time of the ultrasonic dispersion is 100min.
Comparative example 7
The only difference from example 1 is that: in step S3, the power of ultrasonic dispersion is 700W, and the time of ultrasonic dispersion is 20min.
Comparative example 8
The only difference from example 1 is that: in step S5, the temperature of the vacuum heating stage was 70 ℃.
Comparative example 9
The only difference from example 1 is that: in step S5, the temperature of the vacuum heating stage was 120 ℃.
Experimental example 1
Drawing an infrared spectrogram (figure 2) of the N, N-dimethylformamide and an infrared spectrogram (figure 3) of a catalytic layer of the catalytic layer membrane electrode provided in the example 1, and verifying the residual condition of the N, N-dimethylformamide in the catalytic layer of the catalytic layer membrane electrode provided in the example 1; the infrared spectrum of propylene glycol (fig. 4) and the infrared spectrum of the catalytic layer membrane electrode provided in comparative example 1 (fig. 5) were plotted to verify the residual condition of propylene glycol in the catalytic layer provided in comparative example 1.
As can be seen from FIGS. 2 and 3, 1659cm in FIG. 2 -1 The peak of (2) is a C-H bending vibration characteristic peak, and comparing fig. 2 and 3, and the infrared spectrograms of the catalytic layer provided in example 1 have no obvious characteristic absorption peak of N, N-dimethylformamide and no absorption peak of other obvious chemical bonds, which indicates that the catalytic layer provided in example 1 has no N, N-dimethylformamide residue, that is, it is verified that the catalytic layer surface provided in example 1 has no obvious adsorption of N, N-dimethylformamide.
In contrast, as can be seen from FIGS. 4 and 5, 3302cm in FIG. 4 -1 The broad peak of (C) is O-H stretching vibration characteristic peak, and can be obtained by comparing FIG. 4 with FIG. 5, and the catalytic layer infrared spectrogram provided in comparative example 1 is 3302cm -1 There was a significantly broad peak present, which is a characteristic absorption peak for propylene glycol, indicating that there was significant residual propylene glycol in the catalytic layer provided in comparative example 1, i.e., it was confirmed that propylene glycol was significantly adsorbed on the surface of the catalytic layer provided in comparative example 1.
In conclusion, the surface of the catalytic layer provided by the embodiment of the application has no obvious adsorption of N, N-dimethylformamide, the exertion of the electrode performance cannot be influenced, and the catalytic layer is obviously superior to the catalytic layer provided by comparative example 1.
Experimental example 2
Polarization curves of the catalytic layer membrane electrodes provided in examples 1-5 and comparative examples 1-9 were tested and plotted, respectively, with specific results shown in FIGS. 6 and 7, and 2000mA/cm was collected by FIGS. 6 and 7, respectively -2 Lower voltage (V) and 2000mA/cm 2 Lower power density (W/cm) 2 ) The power generation performance of each catalytic layer membrane electrode is characterized, and details are shown in table 1.
The test conditions were: the temperature of the battery is 80 ℃, pure hydrogen is used as fuel, pure air is used as oxidant,the back pressure of the anode and the cathode is 250kP abs The anode metering ratio is 1.5, the cathode metering ratio is 4.0, and the cathode and anode humidification is 100%.
TABLE 1 Power Generation Performance of catalytic layer Membrane electrode
2000mA/cm -2 Lower voltage (V) 2000mA/cm 2 Lower power density (W/cm) 2 )
Example 1 0.607 1.214
Example 2 0.605 1.210
Example 3 0.602 1.204
Example 4 0.601 1.202
Example 5 0.599 1.198
Comparative example 1 0.448 0.896
Comparative example 2 0.451 0.902
Comparative example 3 0.458 0.916
Comparative example 4 0.538 1.076
Comparative example 5 0.547 1.090
Comparative example 6 0.473 0.946
Comparative example 7 0.455 0.910
Comparative example 8 0.447 0.896
Comparative example 9 0.526 1.050
As can be seen from FIGS. 6, 7 and Table 1, the catalytic layers provided in examples 1 to 5 of the present inventionThe power generation performance of the membrane electrode is obviously better than that of the catalytic layer membrane electrode of comparative examples 1-9, and specifically: the catalytic layer membrane electrodes provided in examples 1-5 were at 2000mA/cm 2 The voltage and power density are significantly better than those of comparative examples 1-9, with the power density improvement of example 1 over comparative examples 1-9 being 11-35%, with significant advantages.
Finally, it is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (11)

1. The catalytic layer slurry is characterized in that raw materials of the catalytic layer slurry comprise a Pt/C catalyst, deionized water, an N, N dimethylformamide mixture and a Nafion solution, and the mass ratio of the deionized water to the N, N dimethylformamide mixture is 1: (2.5-6), the preparation method of the catalyst layer slurry comprises the following steps:
wetting the Pt/C catalyst by deionized water, and mixing the Pt/C catalyst with an N, N-dimethylformamide mixture and a Nafion solution to obtain a premix;
protecting the premixed solution for a preset time by inert gas to obtain a protection solution;
under the condition of maintaining the inert gas protection, the protection liquid is subjected to high-speed shearing and ultrasonic dispersion under the ice bath condition to obtain the catalytic layer slurry;
the preset time is 30-60min, the temperature of the ice bath is less than 5 ℃, the ultrasonic dispersion comprises water bath ultrasonic dispersion and probe ultrasonic dispersion, the power of the ultrasonic dispersion is 300-600W, and the time of the ultrasonic dispersion is 30-90min.
2. The catalytic layer slurry of claim 1, wherein the N, N dimethylformamide mixture comprises N, N dimethylformamide and isopropanol.
3. The catalytic layer slurry according to claim 2, wherein the mass fraction of solid matter in the catalytic layer slurry is 1-5%.
4. The catalytic layer slurry according to claim 2, wherein the ratio of the mass of Nafion to the mass of C in the Pt/C catalyst is (0.4-1.4): 1.
5. The catalytic layer slurry according to claim 2, wherein the mass ratio of N, N dimethylformamide to isopropanol is 1: (3-7).
6. The catalytic layer slurry of any of claims 1-5, wherein the catalytic layer slurry has a viscosity of 1.65-2.30 mPa-s.
7. A method for preparing the catalytic layer slurry according to any one of claims 1 to 6, comprising the steps of:
wetting the Pt/C catalyst by deionized water, and mixing the Pt/C catalyst with an N, N-dimethylformamide mixture and a Nafion solution to obtain a premix;
protecting the premixed solution for a preset time by inert gas to obtain a protection solution;
and under the condition of maintaining the protection of the inert gas, the protection liquid is sheared at high speed and dispersed in an ultrasonic way under the ice bath condition, so that the catalytic layer slurry is obtained.
8. The method according to claim 7, wherein the high shear rotational speed is
3000-20000r/min, and the high-speed shearing time is 10-60min.
9. The preparation method of the catalytic layer membrane electrode is characterized by comprising the following steps:
obtaining a proton exchange membrane;
fixing the proton exchange membrane on a vacuum heating table;
spraying the catalyst layer slurry according to any one of claims 1-6 on the surface of the proton exchange membrane and drying to obtain the catalyst layer membrane electrode.
10. The method of claim 9, wherein the thickness of the sprayed catalytic layer slurry is 5-10 μm.
11. The method of claim 9, wherein the vacuum heating station is at a temperature of 80-100 ℃.
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