CN115411274A - A slurry for reducing the defects of fuel cell membrane electrode catalytic layer and its preparation method - Google Patents

Abstract

The invention belongs to the technical field of fuel cells, and in particular relates to a slurry for reducing defects in a catalytic layer of a fuel cell membrane electrode and a preparation method thereof. The slurry includes the following components: catalyst particles 1-40wt.%, inactive materials 0.5-45wt.%, ionomer dispersion 1-30wt.% and solvent 1-95wt.%; the active material is TiC One or more of , TiO ₂ , LiCoO ₂ , CaCO ₃ , P, C, AlN, Te, Si, Ru, Rh. The present invention introduces the inactive material into the slurry of the catalytic layer, and can fill the inactive material into a part of the defects of the catalytic layer when the catalytic layer is formed, avoiding the problem of insufficient volatilization of medium and high boiling point solvents, and residual residues inside the catalytic layer after forming , and effectively reduce the number and size of defects such as bright spots and pinholes in the catalytic layer.

Description

A slurry for reducing the defects of fuel cell membrane electrode catalytic layer and its preparation method

technical field

The invention belongs to the technical field of fuel cells, and in particular relates to a slurry for reducing defects in a catalytic layer of a fuel cell membrane electrode and a preparation method thereof.

Background technique

During the operation of the fuel cell, the efficient transport of hydrogen, air, electrons, protons and water inside plays a decisive role in the power generation performance of the catalytic layer. Generally speaking, the catalytic layer is first dispersed by the slurry mixed with Pt/C catalyst, polymer ionomer, and solvent to form the catalytic layer slurry, and then the catalytic layer slurry is sprayed, scraped or electrospun and dried to prepare electrodes. However, the catalytic layer usually prepared by the above method usually has a series of defects such as bright spots, pinholes, cracks and so on.

From a macro point of view, defects such as cracks and pinholes in the catalytic layer will adversely affect the durability of the proton exchange membrane. The stress at the defect is relatively concentrated, and the mechanical durability of the membrane is poor during operation, and there will be negative and positive electrodes. Risk of gas leakage. In addition, during the operation of the fuel cell, water flooding will occur in the defects of the catalytic layer, which will reduce the gas transmission and reduce the performance of the membrane electrode.

Patent CN110729494A adopts the mixture of one or more of acetic acid, oxalic acid, propionic acid, acrylic acid, butyric acid or isobutyric acid, and chooses a medium boiling point solvent, which can ensure the fluidity of the slurry during the drying process and reduce the It prevents the particle agglomeration of the catalytic layer during the drying process, and reduces defects such as bright spots and cracks in the catalytic layer. However, the boiling points of the solvents in the above methods are all higher than 100° C., and the actual drying process takes a long time, reducing production efficiency. In addition, if the solvent is not volatilized enough, there will be residues inside the catalytic layer, which will affect the performance and durability of the membrane electrode.

Contents of the invention

The present invention aims at the above problems. The present invention provides a slurry for reducing the defects of the fuel cell membrane electrode catalytic layer and a preparation method thereof. Adding inactive materials to the catalytic layer slurry can not only avoid the risk of production efficiency, but also through the filling method Catalyst layer defects are reduced.

In order to achieve the above object, the technical scheme of the present invention is as follows:

One aspect of the present invention provides a slurry for reducing defects in the catalytic layer of a fuel cell membrane electrode, comprising the following components: 1-40wt.% of catalyst particles, 0.5-45wt.% of inactive materials, and 1-30wt.% of ionomer dispersion. % and solvent 1-95wt.%;

The inactive material is one or more of TiC, TiO ₂ , LiCoO ₂ , CaCO ₃ , P, C, AlN, Te, Si, Ru, Rh.

In the above technical solution, further, the catalyst particles are one or more of PtCo/C, PtNi/C, PtFe/C, PtCu/C, PtMo/C, AuPtCo/C, RhPtSn/C, Pt/C kind.

In the above technical solution, further, the ionomer dispersion is a perfluorosulfonic acid resin dispersion. .

In the above technical scheme, further, the solvent is water, methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, ethylene glycol, glycerol one or more.

Another aspect of the present invention provides a method for preparing the slurry for reducing the defects of the fuel cell membrane electrode catalytic layer, comprising the following steps:

(1) Preparation of mixed dispersion liquid of catalyst and inactive material:

Mix catalyst particles with inactive materials and pure water, stir, and disperse evenly to form a mixed dispersion of catalyst and inactive materials;

(2) Preparation of ionomer dispersion:

Mix the ionomer with the solvent for ultrasonic vibration and stirring to obtain the ionomer dispersion;

(3) Catalytic layer slurry preparation:

Stir the ionomer dispersion obtained in step (2) with the mixed dispersion of catalyst and inactive material obtained in step (1), and disperse evenly to obtain a catalytic layer slurry.

Another aspect of the present invention provides a fuel cell membrane electrode CCM, comprising a proton exchange membrane and an anode catalyst layer and a cathode catalyst layer on both sides of the proton exchange membrane, and the anode catalyst layer and/or the cathode catalyst layer are made of the above catalyst layer slurry It is made by spraying or coating on the proton exchange membrane.

The present invention also provides a fuel cell membrane electrode, comprising the above-mentioned CCM, and gas diffusion layers are arranged on both sides of the CCM to obtain a membrane electrode.

The beneficial effects of the present invention are:

The invention introduces the inactive material into the slurry of the catalytic layer, and the inactive material can be filled into a part of the defects of the catalytic layer when the catalytic layer is formed, so as to avoid the problem of insufficient volatilization of medium and high boiling point solvents and residues in the catalytic layer after forming , and effectively reduce the number and size of defects such as bright spots and pinholes in the catalytic layer. In addition, the addition of the inactive material has no effect on the performance of the MEA, and effectively improves the molding quality of the catalytic layer.

Description of drawings

Fig. 1 is the microscopic characterization figure of the catalytic layer prepared by the embodiment of the present invention 1;

Fig. 2 is the microscopic characterization figure of the catalytic layer prepared by comparative example 1 of the present invention;

FIG. 3 is a performance characterization diagram of the MEA prepared in Example 1 and Comparative Example 1 of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the patented embodiments of the present invention clearer, the technical solutions in the patented embodiments of the present invention will be clearly and completely described below in conjunction with the drawings and tables in the embodiments of the present invention. The described embodiments are some, not all, embodiments of the patent of the present invention. Based on the embodiments in the patent of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the patent of the present invention.

Example 1

A slurry for reducing the defects of the fuel cell membrane electrode catalytic layer, comprising the following components: 9wt.% catalyst particles, 0.6wt.% inactive materials, 24wt.% ionomer dispersion, 66.4wt.% solvent; wherein, the catalyst particles are Pt/C particles, the inactive material is C material, the ionomer dispersion is a perfluorosulfonic acid resin dispersion, and the solvent is a mixed solvent of water, ethanol and isopropanol.

The concrete steps of embodiment 1 catalytic layer slurry preparation method are as follows:

(1) Preparation of mixed dispersion of catalyst and inactive material: mix catalyst particles with inactive material and pure water at a speed of 1000 rpm/min, stir for 15 min, and form a mixed dispersion of catalyst and inactive material after dispersing evenly;

(2) Preparation of the ionomer dispersion: mix the ionomer with a solvent for ultrasonic vibration at a speed of 1000 rpm/min, and then stir for 15 minutes to obtain the ionomer dispersion;

(3) Catalyst layer slurry preparation: the polymer ionomer solution in step (2) and the mixed dispersion liquid of the catalyst and inactive material in step (1) were stirred with a stirrer for about 15min, and the rotating speed was 1500rpm/min , and then disperse the mixed slurry by means of ball milling, and finally prepare the catalytic layer slurry.

Comparative example 1

The preparation method of the catalytic layer slurry of Comparative Example 1 is consistent with that of Example 1 except that no inactive materials are added.

The slurries prepared in Example 1 and Comparative Example 1 were molded by spraying or coating, and the defects of the catalytic layer were characterized by an optical microscope, and the imaging range was 13*10mm. The microscopic representations of the catalytic layers prepared in Example 1 and Comparative Example 1 are shown in Figure 1 and Figure 2, respectively. It can be seen from the figure that the number of defects added to the catalytic layer has been greatly reduced, and the number of defects in the field of view of 13mm*10mm has been reduced from 10729 to 1190. In addition, the average radius of bright spots has also decreased from 21.2 μm to 12 μm. It can be seen that adding inactive materials to the catalytic layer slurry can reduce the size and number of molding defects.

Table 1 shows the defect statistics of the slurry prepared in Example 1 and Comparative Example 1.

Table 1

The catalytic layers formed by the slurries of Example 1 and Comparative Example 1 were respectively assembled into film-forming electrodes and tested for electrochemical performance. The results are shown in FIG. 3 . .

The test conditions are as follows: the battery temperature is 80°C; the stoichiometric ratio of hydrogen on the anode side is 2, and the stoichiometric ratio of air on the cathode side is 2; the relative humidity on the cathode side is 0%, and the relative humidity on the anode side is 50%; the hydrogen pressure on the anode side is It is 170kpa, and the air pressure on the cathode side is 150kpa.

It can be seen from Figure 3 that the polarization curves of the catalytic layer with inactive materials and without inactive materials are highly overlapped. Under the condition of 2000mA/cm ² , the voltages of both are 0.65V respectively.

The above embodiments are only preferred embodiments of the present invention, and are not intended to limit the implementation. The protection scope of the present invention should be determined by the scope defined in the claims. On the basis of the above description, other changes or changes in different forms can also be made. Obvious changes or variations derived therefrom are still within the scope of protection of the present invention.

Claims (7)

1. A slurry that reduces the defects of the fuel cell membrane electrode catalytic layer, is characterized in that it comprises the following components: catalyst particles 1-40wt.%, inactive materials 0.5-45wt.%, ionomer dispersion 1-30wt .% and solvent 1-95wt.%; The inactive material is one or more of TiC, TiO ₂ , LiCoO ₂ , CaCO ₃ , P, C, AlN, Te, Si, Ru, Rh. 2. according to claim 1, reduce the slurry of fuel cell membrane electrode catalytic layer defect, it is characterized in that, described catalyst particle is PtCo/C, PtNi/C, PtFe/C, PtCu/C, PtMo/C, AuPtCo One or more of /C, RhPtSn/C, Pt/C. 3. The slurry for reducing defects in the catalytic layer of the fuel cell membrane electrode according to claim 1, wherein the ionomer dispersion is a perfluorosulfonic acid resin dispersion. 4. according to claim 1, reduce the slurry of fuel cell membrane electrode catalytic layer defect, it is characterized in that, described solvent is water, methyl alcohol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec. One or more of butanol, tert-butanol, ethylene glycol, and glycerol. 5. a preparation method for reducing the slurry of the fuel cell membrane electrode catalytic layer defect described in any one of claims 1-4, it is characterized in that, comprising the following steps: (1) Preparation of mixed dispersion liquid of catalyst and inactive material: Mix catalyst particles with inactive materials and pure water, stir, and disperse evenly to form a mixed dispersion of catalyst and inactive materials; (2) Preparation of ionomer dispersion: Mix the ionomer with the solvent for ultrasonic vibration and stirring to obtain the ionomer dispersion; (3) Catalytic layer slurry preparation: Stir the ionomer dispersion obtained in step (2) with the mixed dispersion of catalyst and inactive material obtained in step (1), and disperse evenly to obtain a catalytic layer slurry. 6. A fuel cell membrane electrode CCM is characterized in that it comprises a proton exchange membrane and an anode catalyst layer and a cathode catalyst layer on both sides of the proton exchange membrane, and the anode catalyst layer and/or the cathode catalyst layer are defined by claims 1-4 Any one of the catalytic layer slurry is sprayed or coated on the proton exchange membrane. 7 . A fuel cell membrane electrode, characterized in that it comprises the CCM according to claim 6 , gas diffusion layers are arranged on both sides of the CCM, and the membrane electrode is obtained by sealing with a frame.

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