Preparation method of fuel cell mixed catalyst slurry and mixed catalyst slurry

Abstract

The present invention relates to the field of fuel cells and provides a method for preparing a mixed catalyst slurry for a fuel cell: S1. A highly active catalyst A and a highly stable catalyst B are respectively prepared into corresponding catalyst slurries A and B, and catalyst slurries A and B are dispersed using corresponding dispersion intensities and dispersion times according to the properties of catalyst slurries A and B; S2. The dispersed catalyst slurry A is placed in a container, stirred, and the dispersed catalyst slurry B is slowly added while stirring, and stirring is continued for 3 to 5 minutes to obtain a mixed catalyst slurry; or the dispersed catalyst slurry B is placed in a container, stirred, and the dispersed catalyst slurry A is slowly added while stirring, and stirring is continued for 3 to 5 minutes to obtain a mixed catalyst slurry. The advantages of the present invention are that the prepared mixed catalyst slurry has both high activity and high stability.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and more particularly to a method for preparing a fuel cell mixed catalyst slurry and the mixed catalyst slurry. Background Art

[0002] The membrane electrode is the core component of the fuel cell. The performance and durability of the membrane electrode largely depend on the structure of the catalyst layer in the membrane electrode, and further on the catalyst used. In the working principle of the fuel cell, the anode is the place where the hydrogen oxidation reaction (HOR) is completed, and the cathode is the place where the oxygen reduction reaction (ORR) is completed; the electrons generated by the anode flow to the cathode after performing work in the external circuit, and the H generated at the same time + The ORR crosses the electrolyte membrane to reach the cathode. Kinetically, the energy barrier that ORR needs to cross is much higher than that of HOR; therefore, in fuel cells, the cathode catalyst needs to have higher catalytic activity to ensure the performance of the membrane electrode.

[0003] However, achieving both high catalyst activity and stability is difficult. Currently, commonly used fuel cell cathode catalysts are carbon-supported platinum or carbon-supported platinum alloy catalysts. Highly active catalysts require higher mass activity (MA) and electrochemical specific surface area (ECSA). Therefore, the active components of the catalyst must be fully dispersed and maintained at a small particle size, or the active components must be alloyed to achieve high activity. However, highly active catalysts often have stability issues: First, catalysts with small Pt particle sizes can cause Pt instability during fuel cell operation, especially during voltage changes, causing Pt particles to dissolve, migrate, and agglomerate, resulting in reduced catalyst activity; second, fully dispersing Pt or PtM on a carbon carrier usually requires the carbon carrier to have a high specific surface area and some chemical groups that can bind to Pt. Therefore, the degree of graphitization of the carbon carrier is often low, and it is easily corroded under high potentials. During the start-up and shutdown of the fuel cell, the high cathode potential (up to 1.0-1.5V) can easily cause the carbon carrier to oxidize, and even oxidize to CO2 and discharge, thereby causing the Pt particles to fall off, the catalytic layer structure to collapse, and the fuel cell performance to decline significantly. Conversely, highly stable catalysts sacrifice high activity. Such catalysts can usually be used for anodes, but cannot meet performance requirements when used for cathodes.

[0004] Patent CN114342126A discloses a mixed catalyst for fuel cells and its preparation method, which uses a resonant acoustic mixer to mix two different S BETThe invention proposes a catalyst with a large pore volume and a large pore volume to improve target physical properties, and then disperse it in a dispersion medium when forming an electrode, thereby achieving the goal of improving membrane electrode performance and durability. However, the various physical properties of the mixed catalyst described in this patent are generally only between those of the two mixed catalysts, and cannot bring out the advantages of a single catalyst. Summary of the Invention

[0005] The present invention aims to overcome at least one defect of the above-mentioned prior art and provide a method for preparing a fuel cell mixed catalyst slurry and a mixed catalyst slurry to solve the problem that the mixed catalyst slurry cannot achieve both high activity and high durability.

[0006] According to one aspect of the present invention, a method for preparing a mixed catalyst slurry for a fuel cell is provided, comprising the following steps: S1, preparing a highly active catalyst A and a highly stable catalyst B into corresponding catalyst slurries A and B, respectively, and dispersing the catalyst slurries A and B using corresponding dispersion intensities and dispersion times according to the properties of the catalyst slurries A and B;

[0007] S2. Place the dispersed catalyst slurry A in a container, stir, and slowly add the dispersed catalyst slurry B while stirring, and continue stirring for 3 to 5 minutes to obtain a mixed catalyst slurry; or place the dispersed catalyst slurry B in a container, stir, and slowly add the dispersed catalyst slurry A while stirring, and continue stirring for 3 to 5 minutes to obtain a mixed catalyst slurry.

[0008] The performance of a catalyst in a membrane electrode depends not only on its own physical properties, but also on the chemical environment in which the catalyst is located, such as the interface between the catalyst and the ionomer, the amount of ionomer, the morphology of the ionomer, and the pore state of the catalytic layer. To maximize the advantages of a catalyst, it is necessary to design the chemical environment in which the catalyst is located. In this technical solution, a method is adopted in which a single catalyst is first prepared into a slurry and dispersed, and then mixed, so as to design a slurry preparation chemical environment that matches it for the single catalyst, thereby maximizing the high activity of catalyst A and the high durability of catalyst B.

[0009] In addition, since high-durability and high-activity catalysts typically have significant differences in physical properties, high-durability catalysts are often more difficult to disperse than high-activity catalysts. In this technical solution, catalyst slurries A and B are first dispersed separately before mixing, which helps provide optimal dispersion conditions for each, thereby protecting the structures of catalysts A and B from damage and helping to preserve and maximize their respective excellent performance.

[0010] Furthermore, the dispersion time and / or dispersion intensity of the catalyst B is greater than that of the catalyst A.

[0011] In this technical solution, the dispersion time or intensity of catalyst slurry A and catalyst slurry B is significantly different.

[0012] Furthermore, the MA of the catalyst A is greater than that of the catalyst B, and the MA of the catalyst A is greater than 0.15A / mg. Pt ;ECSA>40m 2 / g; the membrane electrode performance of the catalyst A is higher than that of the catalyst B.

[0013] The membrane electrode performance of catalyst A is 15mV@1.0A / cm higher than that of catalyst B. 2 As shown above, when the Pt loading and other components of the membrane electrode are the same, the electrode performance of catalyst A is better than that of catalyst B.

[0014] Furthermore, the stability of the catalyst B is better than that of the catalyst A.

[0015] Under the same membrane electrode, cathode Pt loading and other components, the membrane electrode performance, MA and ECSA degradation of catalyst B after testing according to the DOE2016 catalyst stability test standard (0.6-0.95V, 80℃, 30,000 cycles) are all lower than those of the corresponding membrane electrode of catalyst A, and the membrane electrode performance degradation of catalyst B is ≤30mV@0.8A / cm 2 , MA and ECSA attenuation are both <40%.

[0016] Furthermore, in step S2, the catalyst A accounts for 20% to 80% of the total dry weight of catalysts A and B in the mixed catalyst slurry.

[0017] Furthermore, in step S2, surfactant a is added to the dispersed catalyst slurry A, and the mass of the surfactant a is 5% to 200% of the dry weight of the catalyst A; and / or, surfactant b is added to the dispersed catalyst slurry B, and the mass of the surfactant b is 5% to 200% of the dry weight of the catalyst B.

[0018] Furthermore, the hydrophilicity of the surfactant a is lower than that of the surfactant b, or the content of the surfactant a is lower than that of the surfactant b.

[0019] Furthermore, after dispersion, the average particle size of the catalyst slurry A is 0.2 to 3 μm, and the average particle size of the catalyst slurry B is 1 to 5 μm.

[0020] In another aspect of the present invention, a mixed catalyst slurry is provided, which is prepared by the above-mentioned method for preparing the mixed catalyst slurry for fuel cells.

[0021] Preferably, catalyst A and catalyst B in the mixed catalyst slurry are respectively one of Pt / C catalyst, PtM / C catalyst and ternary catalyst PtMN / C, wherein M in PtM / C catalyst is one or more of Co, Ni, Mn, Pd, Sn, Au, Ag, Ir, Ru, Cu, and Fe, and M or N in PtMN / C is one or more of Co, Ni, Mn, Pd, Sn, Au, Ag, Ir, Ru, Cu, and Fe, and M and N are different.

[0022] In another aspect of the present invention, a CCM structure is provided, wherein the cathode catalyst layer slurry is the above-mentioned mixed catalyst slurry.

[0023] In another aspect of the present invention, a membrane electrode structure is provided, comprising the above-mentioned CCM structure.

[0024] In another aspect of the present invention, a fuel cell stack is provided, comprising the above-mentioned membrane electrode structure.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention prepares slurries of catalyst A and catalyst B separately, disperses them in corresponding appropriate ways, and then mixes the two slurries. The resulting mixed catalyst slurry can give full play to the advantages of each single catalyst and has high activity and high stability.

[0027] (2) The present invention adds respective suitable surfactants to the dispersed catalyst A slurry and catalyst B slurry respectively to improve their dispersion effect, thereby achieving differentiation of the chemical environment of different catalysts in the mixed slurry and promoting the performance of catalyst A and catalyst B.

[0028] (3) The present invention can adjust the properties of catalyst A and catalyst B in the mixed catalyst slurry to design a specific catalytic layer structure to meet the needs in different situations.

[0029] (4) Compared with the membrane electrode coated with catalyst A alone on the cathode side, the membrane electrode coated with the mixed catalyst slurry of the present invention can show better performance.

[0030] (5) The mixed catalyst slurry prepared by the present invention can improve the temperature sensitivity of the membrane electrode, so that the membrane electrode can be applied to a wider temperature range, especially more suitable for low temperature conditions, with enhanced environmental adaptability and reduced cost of replacing components.

[0031] (6) The catalytic layer coated by the mixed catalyst slurry of the present invention is uniform and smooth, which is beneficial to improving the performance of the membrane electrode and extending the life of the membrane electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an SEM image of the cathode catalyst layer in the membrane electrode structure of Example 1.

[0033] Figure 2 This is the SEM image of the cathode catalyst layer in the membrane electrode structure of comparative example 3.

[0034] Figure 3 Polarization curves of membrane electrodes of Examples 1-4 and Comparative Examples 1-3.

[0035] Figure 4 These are polarization curves of Example 1, Comparative Example 1, and Comparative Example 2 before and after the membrane electrode stability test.

[0036] Figure 5 The performance decay diagrams of Example 1, Comparative Example 1 and Comparative Example 2 before and after the membrane electrode stability test are shown.

[0037] Figure 6 The polarization curves of the membrane electrodes of Example 1, Comparative Example 1 and Comparative Example 2 at low temperature are shown.

[0038] Figure 7 The graphs are of the change of membrane electrode performance with temperature for Example 1, Comparative Example 1 and Comparative Example 2.

[0039] Figure 8 The membrane electrode polarization curves of Example 1, Comparative Example 4 and Comparative Example 5 are shown in FIG. DETAILED DESCRIPTION

[0040] The accompanying drawings are for illustrative purposes only and are not to be construed as limiting the present invention. To better illustrate the following embodiments, some components in the accompanying drawings may be omitted, enlarged, or reduced in size, and do not represent actual product dimensions. Those skilled in the art will appreciate that some well-known structures and their descriptions may be omitted from the accompanying drawings.

[0041] Example 1

[0042] This embodiment provides a method for preparing a fuel cell mixed catalyst slurry, and the specific steps are as follows:

[0043] S1, catalyst A is Pt / C catalyst (B505 type from Jiping New Energy Company), with a mass activity of 0.26 A / mg Pt Catalyst B is a Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Precious Metals Co., Ltd.), with a mass activity of 0.12 A / mg Pt .

[0044] Preparation of catalyst slurry A: Weigh 3.7 g of 50 wt% Pt / C catalyst (B505 type from Jiping New Energy Company) and 43.5 g of ultrapure water, slowly add the Pt / C catalyst (B505 type from Jiping New Energy Company) to the ultrapure water in a stirring state, stir for 5 minutes, weigh 6.5 g of 20 wt% perfluorosulfonic acid resin dispersion (Chemours D2020), stir for 2 minutes, add 46.5 g of ethanol, and continue stirring for 2 minutes to complete the pre-dispersion of the slurry; disperse the slurry through a Beads mill disperser, the speed of the disperser is 1000 rpm, the dispersion time is 10 minutes, and then collect the dispersed catalyst slurry for degassing to obtain catalyst slurry A.

[0045] Preparation of catalyst slurry B: Weigh 6.9 g of 50 wt% Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Precious Metals) and 33.7 g of ultrapure water, slowly add the Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Precious Metals) to the ultrapure water in a stirring state, stir for 5 minutes, add 17.2 g of 20 wt% perfluorosulfonic acid resin dispersion (Chemours D2020), stir for 2 minutes, add 0.01 g of PVP, stir for 2 minutes, then add 42.2 g of ethanol, and continue stirring for 2 minutes to complete the pre-dispersion of the slurry; disperse the slurry through a Beads mill disperser, the speed of the disperser is 3000 rpm, the dispersion time is 60 minutes, and then collect the dispersed catalyst slurry for degassing to obtain catalyst slurry B.

[0046] S2. Place the dispersed catalyst slurry A in a container and perform conventional mechanical stirring. Slowly add catalyst slurry B while stirring. Continue stirring for 3 to 5 minutes to obtain a mixed catalyst slurry. In this mixed slurry, catalyst A and catalyst B each account for 50 wt% (dry weight).

[0047] Example 2

[0048] The method and steps of this embodiment are similar to those of embodiment 1, except that: in the mixed catalyst slurry, catalyst A accounts for 70 wt% (dry weight) and catalyst B accounts for 30 wt% (dry weight).

[0049] Example 3

[0050] The method and steps of this embodiment are similar to those of embodiment 1, except that in the mixed catalyst slurry, catalyst A accounts for 20 wt% (dry weight) and catalyst B accounts for 80 wt% (dry weight).

[0051] Example 4

[0052] The method and steps of this embodiment are similar to those of embodiment 1, except that: in the mixed catalyst slurry, catalyst A accounts for 80 wt% (dry weight) and catalyst B accounts for 20 wt% (dry weight).

[0053] Comparative Example 1

[0054] This comparative example provides a method for preparing a fuel cell catalyst slurry, and the specific steps are as follows:

[0055] Preparation of catalyst slurry A: Weigh 3.7 g of 50 wt% Pt / C catalyst (B505 type from Jiping New Energy Company), whose mass activity is 0.26 A / mg Pt , weigh 43.5 g of ultrapure water, slowly add the Pt / C catalyst (B505 type of Jiping New Energy Company) to the ultrapure water in a stirring state, stir for 5 minutes, weigh 6.5 g of 20 wt% perfluorosulfonic acid resin dispersion (Chemours D2020), stir for 2 minutes, add 46.5 g of ethanol, and continue stirring for 2 minutes to complete the pre-dispersion of the slurry; disperse the slurry through a Beads mill disperser, the speed of the disperser is 1000 rpm, the dispersion time is 10 minutes, and then collect the dispersed catalyst slurry for degassing to obtain catalyst slurry A.

[0056] Comparative Example 2

[0057] This comparative example provides a method for preparing a fuel cell catalyst slurry, and the specific steps are as follows:

[0058] Preparation of catalyst slurry B: Weigh 6.9 g of a 50 wt% Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Kikinzoku Co., Ltd.) with a mass activity of 0.12 A / mg Pt. Weigh 33.7 g of ultrapure water and slowly add the Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Kikinzoku Co., Ltd.) to the stirred ultrapure water. Stir for 5 minutes. Then add 17.2 g of a 20 wt% perfluorosulfonic acid resin dispersion (Chemours D2020) and stir for 2 minutes. Then add 0.01 g of PVP and stir for 2 minutes. Then, add 42.2 g of ethanol and continue stirring for 2 minutes to complete the pre-dispersion of the slurry. The slurry is dispersed in a Beads mill at 3000 rpm for 60 minutes. The dispersed catalyst slurry is then collected and deaerated to obtain catalyst slurry B.

[0059] Comparative Example 3

[0060] This comparative example provides a method for preparing a fuel cell mixed catalyst slurry, and the specific steps are as follows:

[0061] S1, catalyst A is Pt / C catalyst (B505 type from Jiping New Energy Company), with a mass activity of 0.26 A / mg Pt Catalyst B is a Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Precious Metals Co., Ltd.), with a mass activity of 0.12 A / mg Pt .

[0062] Mix catalyst A and catalyst B: Weigh 3.7 g of Pt / C catalyst (B505 from Jiping New Energy Company) and 3.7 g of Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Precious Metals) and shake well in a plastic bottle to obtain mixed catalyst C. Weigh 16.4 g of perfluorosulfonic acid resin dispersion (Chemours D2020), 69.1 g of ethanol, and 61.6 g of ultrapure water for later use.

[0063] S2. Slowly add the mixed catalyst C to the ultrapure water in a stirring state, stir for 5 minutes, add the perfluorosulfonic acid resin dispersion and stir for 2 minutes, add ethanol and continue stirring for 2 minutes to complete the pre-dispersion of the slurry; disperse the slurry by a Beadsmill disperser at a speed of 1000 rpm for 30 minutes, and then collect the dispersed catalyst slurry for degassing to obtain a mixed catalyst slurry.

[0064] Comparative Example 4

[0065] This comparative example provides a method for preparing a fuel cell mixed catalyst slurry, and the specific steps are as follows:

[0066] S1, catalyst A is Pt / C catalyst (B505 type from Jiping New Energy Company), with a mass activity of 0.26 A / mg Pt Catalyst B is a Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Precious Metals Co., Ltd.), with a mass activity of 0.12 A / mg Pt .

[0067] Preparation of catalyst slurry A: Weigh 3.7 g of 50 wt% Pt / C catalyst (B505 type from Jiping New Energy Company) and 43.5 g of ultrapure water, slowly add the Pt / C catalyst (B505 type from Jiping New Energy Company) to the ultrapure water in a stirring state, stir for 5 minutes, weigh 6.5 g of 20 wt% perfluorosulfonic acid resin dispersion (Chemours D2020), stir for 2 minutes, add 46.5 g of ethanol, and continue stirring for 2 minutes to complete the pre-dispersion of the slurry; disperse the slurry through a Beads mill disperser, the speed of the disperser is 3000 rpm, the dispersion time is 60 minutes, and then collect the dispersed catalyst slurry for degassing to obtain catalyst slurry A.

[0068] Preparation of catalyst slurry B: Weigh 6.9 g of 50 wt% Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Precious Metals) and 33.7 g of ultrapure water, slowly add the Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Precious Metals) to the ultrapure water in a stirring state, stir for 5 minutes, add 17.2 g of 20 wt% perfluorosulfonic acid resin dispersion (Chemours D2020), stir for 2 minutes, add 0.01 g of PVP, stir for 2 minutes, then add 42.2 g of ethanol, and continue stirring for 2 minutes to complete the pre-dispersion of the slurry; disperse the slurry through a Beads mill disperser, the speed of the disperser is 3000 rpm, the dispersion time is 60 minutes, and then collect the dispersed catalyst slurry for degassing to obtain catalyst slurry B.

[0069] S2. Place the dispersed catalyst slurry A in a container and perform conventional mechanical stirring. Slowly add catalyst slurry B while stirring. Continue stirring for 3 to 5 minutes to obtain a mixed catalyst slurry. In this mixed slurry, catalyst A and catalyst B each account for 50 wt% (dry weight).

[0070] Comparative Example 5

[0071] This embodiment provides a method for preparing a fuel cell mixed catalyst slurry, and the specific steps are as follows:

[0072] S1, catalyst A is Pt / C catalyst (B505 type from Jiping New Energy Company), with a mass activity of 0.26 A / mg Pt Catalyst B is a Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Precious Metals Co., Ltd.), with a mass activity of 0.12 A / mg Pt .

[0073] Preparation of catalyst slurry A: Weigh 3.7 g of 50 wt% Pt / C catalyst (B505 type from Jiping New Energy Company) and 43.5 g of ultrapure water, slowly add the Pt / C catalyst (B505 type from Jiping New Energy Company) to the ultrapure water in a stirring state, stir for 5 minutes, weigh 6.5 g of 20 wt% perfluorosulfonic acid resin dispersion (Chemours D2020), stir for 2 minutes, add 46.5 g of ethanol, and continue stirring for 2 minutes to complete the pre-dispersion of the slurry; disperse the slurry through a Beads mill disperser, the speed of the disperser is 1000 rpm, the dispersion time is 10 minutes, and then collect the dispersed catalyst slurry for degassing to obtain catalyst slurry A.

[0074] Preparation of catalyst slurry B: Weigh 6.9 g of 50 wt% Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Precious Metals) and 33.7 g of ultrapure water, slowly add the Pt / C catalyst (TEC10E50E-HT catalyst from Tanaka Precious Metals) to the ultrapure water in a stirring state, stir for 5 minutes, add 17.2 g of 20 wt% perfluorosulfonic acid resin dispersion (Chemours D2020), stir for 2 minutes, add 0.01 g of PVP, stir for 2 minutes, then add 42.2 g of ethanol, and continue stirring for 2 minutes to complete the pre-dispersion of the slurry; disperse the slurry through a Beads mill disperser, the speed of the disperser is 1000 rpm, the dispersion time is 10 minutes, and then collect the dispersed catalyst slurry for degassing to obtain catalyst slurry B.

[0075] S2. Place the dispersed catalyst slurry A in a container and perform conventional mechanical stirring. Slowly add catalyst slurry B while stirring. Continue stirring for 3 to 5 minutes to obtain a mixed catalyst slurry. In this mixed slurry, catalyst A and catalyst B each account for 50 wt% (dry weight).

[0076] The catalyst slurries prepared in Examples 1-4 and Comparative Examples 1-5 were respectively coated on one side of the proton exchange membrane by slit coating. The anode catalyst was prepared according to the following formula: 6.9 g 50 wt% Pt / C catalyst (Elyst Pt500380), 17.24 g 18 wt% perfluorosulfonic acid resin dispersion (Chemours D2020), 42.2 g ethanol, 33.7 g ultrapure water. The prepared Pt / C anode catalyst was coated on the other side of the proton exchange membrane to prepare a CCM. The platinum loading of the CCM cathode was 0.35 mg / cm 2 , the platinum loading of the anode is 0.1 mg / cm 2 The CCM, frame and gas diffusion layer are further combined to form a membrane electrode, and polarization curve test and stability test are carried out on each membrane electrode.

[0077] Figure 1 is the scanning electron microscope image of Example 1, Figure 2 This is a scanning electron microscope image of Comparative Example 3. As shown, the membrane electrode catalyst layer coated with the mixed catalyst slurry of Example 1 is uniform and smooth, with few large particles on the surface; while the membrane electrode catalyst layer coated with the mixed catalyst slurry of Comparative Example 3 contains a large number of catalyst agglomerates. This shows that in the system using a well-dispersed catalyst slurry for mixing, both catalysts are well dispersed and the coating is highly uniform; in the system where the catalysts are mixed before preparing the slurry, the uniformity of the two catalysts is poor, that is, at least one of the catalysts is not well dispersed.

[0078] Figure 3 The polarization curves of the membrane electrodes of Examples 1-4 and Comparative Examples 1-3 are shown in the figure. As shown in the figure, the comparison of the polarization curves shows that the membrane electrode performance is significantly improved when the slurry of the higher-performance catalyst A is mixed with the slurry of the more durable catalyst B, compared with the use of catalyst B alone, and is slightly higher than the membrane electrode performance of the high-performance catalyst A alone at high current density. Comparison of the polarization curves of Example 1 and Comparative Example 3 shows that the membrane electrode performance in Example 1 is better than that in Comparative Example 3. It can be seen that the performance of the membrane electrode using the same ratio of catalyst A and catalyst B, first mixing the catalysts and then preparing the slurry is between the membrane electrode using the two catalysts alone, and the performance of the membrane electrode using the two catalysts first and then mixing the catalyst slurries is significantly higher than the performance of the membrane electrode using the two catalysts directly after mixing and then dispersing.

[0079] Figure 4 The polarization curves of Example 1, Comparative Example 1 and Comparative Example 2 before and after the membrane electrode stability test are shown in FIG. Figure 5 The performance decay diagrams of Example 1, Comparative Example 1 and Comparative Example 2 before and after the membrane electrode stability test are shown. Figure 4 and Figure 5 It can be seen that the performance attenuation of Comparative Example 1 before and after the test is greater than that of Comparative Example 2, and the performance attenuation of Example 1 is close to that of Comparative Example 2, indicating that the mixed catalyst slurry of the present invention can maintain the initial performance to the greatest extent, that is, taking into account both high activity and high durability.

[0080] Figure 6 The polarization curves of the membrane electrodes of Example 1, Comparative Example 1 and Comparative Example 2 at low temperature are shown in FIG. Figure 7 The following is a graph showing the change of membrane electrode performance with temperature for Example 1, Comparative Example 1 and Comparative Example 2. Figure 6 and Figure 7 As can be seen, the membrane electrode of Example 1 exhibits higher performance than that of the membrane electrode of Comparative Example 1, indicating that the performance of the mixed catalyst slurry of the present invention is superior to that of the high-performance single catalyst. Furthermore, the performance of the membrane electrode of Example 1 is less affected by temperature, while the performance of the membrane electrode of Comparative Example 1 is most affected by temperature, followed by Comparative Example 2. This demonstrates that the mixed catalyst slurry prepared by the method of the present invention can improve the temperature sensitivity of the membrane electrode, making it suitable for use in a wider temperature range, especially under low-temperature conditions.

[0081] Figure 8The following are membrane electrode polarization curves for Example 1, Comparative Example 4, and Comparative Example 5. In Comparative Example 4, Catalyst Slurry A uses the same slurry dispersion conditions as Catalyst Slurry B, but with a longer dispersion time and greater strength. In Comparative Example 5, Catalyst Slurry B uses the same dispersion conditions as Catalyst Slurry A, but with a shorter dispersion time and weaker dispersion ability. Comparative performance shows that, despite the same ratio and catalyst loading in the three samples, the performance of Comparative Examples 4 and 5 is significantly inferior to that of Example 1. This demonstrates that the two catalysts require matching their respective slurry dispersion conditions to achieve the desired high performance after mixing the catalyst slurries.

[0082] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the technical solutions of the present invention, and are not intended to limit the specific implementation methods of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a fuel cell mixed catalyst slurry, characterized in that: The following steps are involved: S1. The highly active catalyst A and the highly stable catalyst B are respectively prepared into corresponding catalyst slurries A and catalyst slurry B. According to the properties of the catalyst slurry A and the catalyst slurry B, the catalyst slurry A and the catalyst slurry B are dispersed using corresponding dispersion strengths and dispersion times; the MA of the catalyst A is greater than that of the catalyst B; and the stability of the catalyst B is better than that of the catalyst A; S2, the dispersed catalyst slurry A is placed in a container, stirred, and the dispersed catalyst slurry B is slowly added under stirring, and stirring is continued for 3 to 5 minutes to obtain a mixed catalyst slurry; or the dispersed catalyst slurry B is placed in a container, stirred, and the dispersed catalyst slurry A is slowly added under stirring, and stirring is continued for 3 to 5 minutes to obtain a mixed catalyst slurry; The dispersion time and dispersion intensity of the catalyst B are greater than those of the catalyst A.

2. The method for preparing a fuel cell mixed catalyst slurry according to claim 1, wherein: The MA of the catalyst A is greater than 0.15 A / mg Pt ;ECSA>40m 2 / g.

3. The method for preparing a fuel cell mixed catalyst slurry according to claim 1, wherein: The membrane electrode performance of the catalyst A is higher than that of the catalyst B.

4. The method for preparing a fuel cell mixed catalyst slurry according to any one of claims 1 to 3, characterized in that: In the mixed catalyst slurry, catalyst A accounts for 20% to 80% of the total dry weight of catalyst A and catalyst B.

5. The method for preparing a fuel cell mixed catalyst slurry according to any one of claims 1 to 3, characterized in that: In step S2, surfactant a is added to the dispersed catalyst slurry A, and the mass of the surfactant a is 5% to 200% of the dry weight of the catalyst A; and / or surfactant b is added to the dispersed catalyst slurry B, and the mass of the surfactant b is 5% to 200% of the dry weight of the catalyst B.

6. The method for preparing a fuel cell mixed catalyst slurry according to claim 5, characterized in that: The hydrophilicity of the surfactant a is lower than that of the surfactant b, or the content of the surfactant a is lower than that of the surfactant b.

7. The method for preparing a fuel cell mixed catalyst slurry according to any one of claims 1 to 3, characterized in that: In step S2, after dispersion, the average particle size of the catalyst slurry A is 0.2-3 μm, and the average particle size of the catalyst slurry B is 1-5 μm.

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