Proton exchange membrane fuel cell slurry and preparation method thereof

Abstract

The invention relates to the technical field of fuel cells, in particular to proton exchange membrane fuel cell slurry and a preparation method thereof. The preparation method comprises the following steps: (1) adding a perfluorosulfonic acid resin solution into alcohol, dispersing, and heating to obtain a gelatinized ionomer solution; (2) adding water or alcohol into a catalyst, and dispersing to obtain a catalyst solution; and (3) mixing the gelatinized ionomer solution and the catalyst solution, and uniformly dispersing to obtain the proton exchange membrane fuel cell slurry. The catalyst has the advantages of excellent power generation performance and uniform coating on the surface of the catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of fuel cells, and in particular to a proton exchange membrane fuel cell slurry and a preparation method thereof. Background Art

[0002] Proton exchange membrane fuel cells (PEMFC) have attracted widespread attention due to their high energy conversion efficiency and zero pollution emissions. The membrane electrode (CCM) is the core component of PEMFC, which consists of the cathode catalyst layer, the anode catalyst layer, and the proton exchange membrane, and affects the performance, life, and cost of PEMFC.

[0003] In CCM, the catalyst layer (CL) is the main place where the reaction occurs, converting chemical energy into electrical energy, so the conduction of reactant gases, water, protons and electrons must be met. In fuel cells, the oxygen transfer impedance in the cathode catalyst layer is mainly caused by the dense ionomer coated on the catalyst surface. Improving the distribution of ionomers in the catalyst layer by optimizing the cathode catalyst slurry is an effective means to improve the performance of proton exchange membrane fuel cells.

[0004] Generally speaking, the traditional fuel cell catalyst slurry is to mix the catalyst with the solvent and the ionomer solution, and obtain a uniformly dispersed catalyst slurry by ultrasonic or high-speed dispersion. However, in the fuel cell slurry, the ionomer is usually adsorbed on the catalyst surface by the hydrophobic properties of the ionomer main chain and the carbon carrier and the hydrophilic properties of the side chain and Pt. Due to the easy aggregation of the ionomer itself, it is difficult to achieve uniform coating of the ionomer on the catalyst surface, resulting in a reduction in the three-phase reaction interface, thereby causing a decrease in the performance of the membrane electrode. Therefore, by improving the dispersion state of the ionomer and increasing the contact area between the ionomer and the catalyst surface, it can be more evenly adsorbed on the catalyst to form a good three-phase interface, which can improve the performance of the fuel cell.

[0005] Chinese patent application CN202310769996.1 combines three methods, namely, sulfur doping modification of carbon carrier to improve the hydrophilicity of the carrier, stage-by-stage control of the solvent ratio in the slurry, and temperature control process, to directionally control the adsorption state of the ionomer. However, this method has a complicated process flow and is not conducive to mass production.

[0006] Chinese patent application CN202410328962.3 adds a dispersant with steric hindrance during the preparation of the catalyst slurry to avoid the entanglement of the perfluorosulfonic acid resin, so that the perfluorosulfonic acid resin can evenly wrap the catalyst. However, additives with steric hindrance usually have the characteristics of high boiling point and low volatility, and are very likely to remain in the catalyst layer, causing defects such as cracks in the catalyst layer.

[0007] Therefore, it is very necessary to develop a proton exchange membrane fuel cell slurry and a preparation method thereof, and a battery containing the slurry that can solve the above technical problems. Summary of the invention

[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a proton exchange membrane fuel cell slurry with excellent power generation performance and uniform coating on the catalyst surface, a preparation method thereof, and a battery containing the slurry.

[0009] The present invention is achieved through the following technical solutions:

[0010] A method for preparing a proton exchange membrane fuel cell slurry comprises the following steps:

[0011] (1) adding a perfluorosulfonic acid resin solution into alcohol for dispersion and heating to obtain a gelled ionomer solution;

[0012] (2) dispersing the catalyst in water or alcohol to obtain a catalyst solution;

[0013] (3) The gelled ionomer solution and the catalyst solution are mixed and dispersed evenly to obtain a proton exchange membrane fuel cell slurry.

[0014] In some embodiments of the present invention, step (3) comprises:

[0015] 3i) diluting the gelled ionomer solution with water or alcohol to obtain an ionomer dilution solution, wherein the purpose of the dilution is to facilitate industrial production;

[0016] 3ii) The ionomer dilution solution is mixed with the catalyst solution and dispersed evenly to obtain a proton exchange membrane fuel cell slurry.

[0017] In some embodiments of the present invention, in step 3i), the solid content of the ionomer dilution solution is 5-18%.

[0018] In some embodiments of the present invention, in step 3i), the dispersion is performed using a high-speed shear disperser.

[0019] In some preferred embodiments of the present invention, in step 3i), the dispersion process parameters are as follows: rotation speed is 5m / s-15m / s, time is 5min-15min, and shear temperature is 10-20°C.

[0020] In some embodiments of the present invention, in step 3ii), the dispersion process parameters are as follows: rotation speed is 10000-18000 rpm, time is 30 min-240 min, and temperature is 15-25°C.

[0021] In some embodiments of the present invention, the dispersing equipment used in step 3ii) is a high-speed disperser.

[0022] In some embodiments of the present invention, the alcohol is at least one of n-propanol and isopropanol.

[0023] In some embodiments of the present invention, in step (1), the perfluorosulfonic acid resin solution is at least one of commercial Nafion, Aquivion, Flemion and Aciplex. Perfluorosulfonic acid resin solutions of different brands can be used in the present invention with similar effects and are not particularly limited.

[0024] In some embodiments of the present invention, in step (1), the mass ratio of the alcohol to the perfluorosulfonic acid resin solution is 0.3-4:1.

[0025] In some embodiments of the present invention, in step (1), the dispersion process parameters are: rotation speed of 10000-18000 rpm, time of 10 min-30 min, and temperature of 10-25°C.

[0026] In some embodiments of the present invention, the dispersing equipment used in step (1) is a high-speed disperser.

[0027] In some embodiments of the present invention, in step (1), the heating temperature is 60-80° C. and the heating time is 2-4 h.

[0028] In some embodiments of the present invention, the heating method used in step (1) is water bath heating.

[0029] In some embodiments of the present invention, the catalyst in step (2) includes at least one of Pt / C, PtFe / C and Pt3Co / C.

[0030] In some preferred embodiments of the present invention, in step (2), the mass fraction of Pt in the catalyst is 20-60%.

[0031] In some embodiments of the present invention, in step (2), the alcohol is one of isopropanol and n-propanol, and the mass ratio of the catalyst to water or alcohol is 1:2-7.

[0032] The alcohol may be a mixed solution of an alcohol solvent and water, or may be an alcohol solvent without water.

[0033] In some embodiments of the present invention, in step (2), the dispersion is performed using a cutting-edge ultrasonic dispersion device.

[0034] In some preferred embodiments of the present invention, in step (2), the dispersion process parameters are as follows: ultrasonic power is 200-800 W, ultrasonic time is 6-15 min, and ultrasonic temperature is 0-10°C.

[0035] In some preferred embodiments of the present invention, the mass ratio of the perfluorosulfonic acid resin solution to the catalyst is 2:1.

[0036] The present invention also relates to a proton exchange membrane fuel cell slurry prepared by the above-mentioned preparation method.

[0037] The present invention also relates to a battery, comprising the above-mentioned proton exchange membrane fuel cell slurry.

[0038] The beneficial effects of the present invention are:

[0039] The present invention achieves full opening of agglomerated chain segments of the ionomer in a solvent through heat treatment of the ionomer, increases the interaction between the ionomer and the catalyst during slurry dispersion, achieves uniform coating of the ionomer on the catalyst surface, increases the three-phase reaction interface of the catalyst layer, reduces the oxygen transmission resistance of the catalyst layer, improves membrane electrode performance, and simultaneously improves the durability of the membrane electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is the SEM image of the cathode electrode prepared in Example 1.

[0041] Figure 2 This is the SEM image of the cathode electrode prepared in Comparative Example 3.

[0042] Figure 3 This is the SEM image of the cathode electrode prepared in Comparative Example 5.

[0043] Figure 4 It is a schematic diagram of the dispersed state of the ionomer of the present invention.

[0044] Figure 5 This is a comparison chart of the membrane electrode polarization curves prepared in Examples 1 to 3 and Comparative Example 1. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solution of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the scope of protection of the present invention.

[0046] Example 1

[0047] 1) 6.4 g of perfluorosulfonic acid resin solution (Aquivion D72-25BS 25% wt) and 25.6 g of n-propanol were mixed and dispersed at 10° C. using a high-speed disperser at a speed of 10,000 rpm for 30 min. The dispersion was then heated in a water bath at 70° C. for 2 h to obtain a gelled ionomer solution.

[0048] 2) adding 11.2 g of n-propanol solution to the gelled ionomer solution prepared in step 1), and mixing using a high-speed disperser at a speed of 5 m / s, a time of 5 min, and a temperature of 10° C. to obtain an ionomer dilution solution;

[0049] 3) 3.2 g of Pt / C catalyst (Pt content 60%) and 13.6 g of deionized water were mixed, and dispersed by tip ultrasound at 5° C., with an ultrasound power of 800 W and an ultrasound time of 6 min to obtain a catalyst solution;

[0050] 4) The ionomer dilution obtained in step 2) and the catalyst obtained in step 3) are mixed and dispersed using a high-speed disperser at a speed of 15,000 rpm, a time of 120 min, and a temperature of 25° C. to obtain a proton exchange membrane fuel cell catalyst slurry.

[0051] Example 2

[0052] 1) 8 g of perfluorosulfonic acid resin solution (Aquivion D72-25BS 25% wt) and 2.42 g of n-propanol were mixed and dispersed at 25° C. using a high-speed disperser at a speed of 18,000 rpm for 20 min. The dispersion was then heated in a water bath at 80° C. for 2 h to obtain a gelled ionomer solution.

[0053] 2) adding 24.58 g of n-propanol solution and 6 g of deionized water to the gelled ionomer solution prepared in step 1), and mixing using a high-speed disperser at a speed of 10 m / s, a time of 15 min, and a temperature of 20° C. to obtain an ionomer dilution solution;

[0054] 3) 4 g of PtFe / C catalyst (Pt content 50%) and 15 g of deionized water were mixed, and the mixture was dispersed by tip ultrasound at 0° C., with an ultrasound power of 500 W and an ultrasound time of 12 min to obtain a catalyst solution;

[0055] 4) The ionomer dilution obtained in step 2) and the catalyst obtained in step 3) are mixed and dispersed using a high-speed disperser at a speed of 10,000 rpm, a time of 240 min, and a temperature of 15° C. to obtain a proton exchange membrane fuel cell catalyst slurry.

[0056] Example 3

[0057] 1) 6.4 g of perfluorosulfonic acid resin solution (Aquivion D72-25BS 25% wt) and 9.6 g of isopropanol were mixed and dispersed at 25° C. with a high-speed disperser at a speed of 10,000 rpm for 10 min. The dispersion was then heated in a water bath at 60° C. for 4 h to obtain a gelled ionomer solution.

[0058] 2) adding 15 g of isopropanol solution to the gelled ionomer solution prepared in step 1), and mixing using a high-speed disperser at a speed of 15 m / s, a time of 15 min, and a temperature of 20° C. to obtain an ionomer dilution solution;

[0059] 3) 3.2 g of Pt3Co / C catalyst (Pt content 20%), 13.6 g of deionized water and 12.2 g of isopropanol were mixed, and dispersed by tip ultrasound at 10° C., with an ultrasound power of 200 W and an ultrasound time of 15 min to obtain a catalyst solution;

[0060] 4) The ionomer dilution obtained in step 2) and the catalyst obtained in step 3) are mixed and dispersed using a high-speed disperser at a speed of 18,000 rpm, a time of 30 minutes, and a temperature of 25° C. to obtain a proton exchange membrane fuel cell catalyst slurry.

[0061] Comparative Example 1

[0062] A method for preparing a conventional proton exchange membrane fuel cell catalyst slurry comprises the following steps:

[0063] 1) 3.2 g of Pt / C catalyst (Pt content 60%) was completely wetted with 22.8 g of deionized water, and then 27.6 g of n-propanol was added, and finally 6.4 g of Aquivion D79-25BS (mass fraction 25%) perfluorosulfonic acid resin solution was added to obtain a catalyst slurry; wherein the components and proportions of the catalyst slurry were the same as those in Example 1;

[0064] 2) The catalyst slurry was first dispersed in a water bath at 5°C with an ultrasonic power of 500 W and an ultrasonic time of 20 min, and then dispersed in a high-speed disperser at 15°C with a shear speed of 13,000 rpm for 120 min to obtain a proton exchange membrane fuel cell catalyst slurry.

[0065] Comparative Example 2

[0066] The only difference from Example 1 is that the perfluorosulfonic acid resin dispersion is not heated, and the other conditions are the same, as follows:

[0067] 1) 6.4 g of perfluorosulfonic acid resin solution (Aquivion D72-25BS 25% wt) and 25.6 g of n-propanol were mixed and dispersed in a high-speed disperser at 10° C. with a rotation speed of 10,000 rpm for 30 min to obtain an ionomer solution.

[0068] 2) adding 11.2 g of n-propanol solution to the ionomer solution prepared in step 1), and mixing using a high-speed disperser at a speed of 5 m / s, a time of 5 min, and a temperature of 10° C. to obtain an ionomer dilution solution;

[0069] 3) 3.2 g of Pt / C catalyst (Pt content 60%) and 13.6 g of deionized water were mixed, and dispersed by tip ultrasound at 5° C., with an ultrasound power of 800 W and an ultrasound time of 6 min to obtain a catalyst solution;

[0070] 4) The ionomer dilution obtained in step 2) and the catalyst obtained in step 3) are mixed and dispersed using a high-speed disperser at a speed of 15,000 rpm, a time of 120 min, and a temperature of 25° C. to obtain a proton exchange membrane fuel cell catalyst slurry.

[0071] Comparative Example 3

[0072] The only difference from Example 1 is that the heating parameters in the preparation process of the gelled ionomer solution are different, specifically: the heating temperature is 50° C. and the heating time is 2 h, and the other conditions are the same.

[0073] Comparative Example 4

[0074] The only difference from Example 1 is that the heating parameters in the preparation process of the gelled ionomer solution are different, specifically: the heating temperature is 50° C. and the heating time is 6 h, and the other conditions are the same.

[0075] Comparative Example 5

[0076] The only difference from Example 1 is that the heating parameters in the preparation process of the gelled ionomer solution are different, specifically: the heating temperature is 90° C. and the heating time is 2 h, and the other conditions are the same.

[0077] Comparative Example 6

[0078] The only difference from Example 1 is that the heating parameters in the preparation process of the gelled ionomer solution are different, specifically: the heating temperature is 90° C. and the heating time is 6 h, and the other conditions are the same.

[0079] Test Example 1

[0080] The proton exchange membrane fuel cell catalyst slurry in Example 1, Comparative Example 3, and Comparative Example 5 was coated on the PET coating substrate using a wire rod coater, the wire rod type was 110 μm, and the coating speed was 60 m / min, and then dried in an oven at 45° C. to obtain the cathode electrode sheet. The scanning electron microscope (SEM) images of the cathode electrode sheets prepared in Example 1, Comparative Example 3, and Comparative Example 5 are shown respectively. Figure 1-Figure 3 As shown, from Figure 1 It can be seen that the surface structure of the electrode is relatively flat, without large agglomerates and particles.

[0081] Test Example 2

[0082] The schematic diagram of the dispersion state of the ionomer dilution prepared in each embodiment of the present invention is as follows: Figure 4 Before heating, the ionomer chain segments are in a curled state, and the chain segments gradually open during the heating process. After the heating is completed, a gelled ionomer is obtained, and the chain segments are completely opened. Water or alcohol is added to dilute it to obtain an ionomer dilution liquid.

[0083] Test Example 3

[0084] Take the proton exchange membrane fuel cell catalyst slurry prepared in Example 1 to Example 3 and Comparative Example 1 to Comparative Example 6, and use a wire rod coater to scrape it on the PET coated substrate. The wire rod type is 110 μm and the coating speed is 60 m / min. Then dry it in an oven at 45°C to obtain a cathode electrode.

[0085] Take 2.44g of Pt / C catalyst with a Pt loading of 47%, moisten it with 7.703g of deionized water, add 7.162g of Nafion D2020 ionomer dispersion, add 24g of n-propanol (nPA), use tip ultrasonic dispersion, the ultrasonic power is 800W, the ultrasonic time is 30min, and the anode catalyst solution is obtained; then use a wire rod coater to coat it on the PET coated substrate, the wire rod type is 30μm, the coating speed is 60m / min, and then dry it in an oven at 45°C to obtain the anode electrode sheet.

[0086] Then, the cathode electrode pieces prepared in Examples 1 to 3 and Comparative Examples 1 to 6, the anode electrode pieces and the perfluorosulfonic acid proton exchange membrane were respectively taken and hot-pressed and transferred at 150° C. to obtain membrane electrodes.

[0087] The power generation performance of the membrane electrode was investigated by polarization curves. The electrochemical test conditions were: stack temperature 65°C, air-to-hydrogen ratio 2.5:3.5, and humidification temperature 60°C. The results are shown in Table 1 and Figure 5 As shown in Table 1, it can be seen that the performance of the membrane electrode prepared by the proton exchange membrane fuel cell catalyst slurry of Example 1-Example 3 is better than that of Comparative Example 1-Comparative Example 6.

[0088] Table 1

[0089]

[0090] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A method for preparing a proton exchange membrane fuel cell slurry, characterized in that: The steps include: (1) adding a perfluorosulfonic acid resin solution into alcohol for dispersion and heating to obtain a gelled ionomer solution; (2) dispersing the catalyst in water or alcohol to obtain a catalyst solution; (3) The gelled ionomer solution and the catalyst solution are mixed and dispersed evenly to obtain a proton exchange membrane fuel cell slurry.

2. The preparation method according to claim 1, characterized in that: Step (3) includes: 3i) diluting the gelled ionomer solution with water or alcohol and dispersing the solution to obtain an ionomer dilution solution; 3ii) The ionomer dilution solution is mixed with the catalyst solution and dispersed evenly to obtain a proton exchange membrane fuel cell slurry.

3. The preparation method according to claim 1 or 2, characterized in that: The alcohol is at least one of n-propanol and isopropanol; in step (1), the mass ratio of the alcohol to the perfluorosulfonic acid resin solution is 0.3-4:

1.

4. The preparation method according to claim 1 or 2, characterized in that: In step (1), the dispersion process parameters are: rotation speed of 10000-18000 rpm, time of 10 min-30 min, and temperature of 10-25°C.

5. The preparation method according to claim 1 or 2, characterized in that: In step (1), the heating temperature is 60-80° C. and the heating time is 2-4 hours.

6. The preparation method according to claim 2, characterized in that: In step 3i), the dispersion is carried out by a high-speed shearing disperser, and the process parameters are as follows: rotation speed is 5m / s-15m / s, time is 5min-15min, and shear temperature is 10-20°C.

7. The preparation method according to claim 1 or 2, characterized in that: In step (2), the mass ratio of the catalyst to water or alcohol is 1:2-7.

8. The preparation method according to claim 1 or 2, characterized in that: In step (2), the dispersion is carried out using a cutting-edge ultrasonic dispersion device, and the process parameters are as follows: ultrasonic power is 200-800W, ultrasonic time is 6-15min, and ultrasonic temperature is 0-10°C.

9. The preparation method according to claim 2, characterized in that: In step 3ii), the dispersion process parameters are as follows: rotation speed is 10000-18000 rpm, time is 30 min-240 min, and temperature is 15-25°C.

10. A proton exchange membrane fuel cell slurry prepared according to the preparation method according to any one of claims 1 to 9.

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