Catalyst slurry for hydrogen fuel cell, preparation method of catalyst slurry, catalyst layer, membrane electrode and hydrogen fuel cell

Abstract

The invention provides catalyst slurry for a hydrogen fuel cell, a preparation method of the catalyst slurry, a catalyst layer, a membrane electrode and the hydrogen fuel cell, and relates to the technical field of membrane electrodes. The catalyst slurry comprises a solid-phase component and a liquid-phase component, the solid-phase component accounts for 0.5%-3%, the solid-phase component comprises Nafion resin, the liquid-phase component comprises an organic solvent and water, the mass ratio of the Nafion resin to the liquid-phase component is 1: (160-320), and the mass ratio of the organic solvent to the water is (3.65-8.63): 1. The preparation method of the catalyst slurry comprises the following steps: mixing and stirring the components, ultrasonically dispersing, shearing and crushing. The catalyst layer is obtained by spraying catalyst slurry on the cathode and anode sides of the proton exchange membrane. The membrane electrode comprises a proton exchange membrane, a catalyst layer and a diffusion layer. The hydrogen fuel cell comprises a bipolar plate and a membrane electrode. The membrane electrode provided by the invention has high performance, and meanwhile, the loading capacity of noble metal platinum on the membrane electrode can be reduced, so that the cost of the membrane electrode is further controlled.

Description

Technical Field

[0001] The present application relates to the technical field of membrane electrode, and in particular to a catalyst slurry for a hydrogen fuel cell, a preparation method thereof, a catalytic layer, a membrane electrode and a hydrogen fuel cell. Background Art

[0002] As is well known, Proton Exchange Membrane Fuel Cells (PEMFC) is a relatively mature fuel cell at present, with special advantages such as no pollution to the environment, high energy conversion efficiency and power density, low emissions and heat radiation, and low noise pollution. Therefore, the proton exchange membrane fuel cell has a broad market prospect, and its application scope is constantly expanding from small portable electrical devices and small fixed base stations to large pure electric vehicles, aerospace and military fields.

[0003] The Membrane Electrode Assembly (MEA) is the core component of the proton exchange membrane fuel cell, and together with the bipolar plates on both sides, it forms a fuel cell single cell. The membrane electrode provides a microchannel for multiphase mass transfer and an electrochemical reaction site for the PEMFC. The quality of its performance directly determines the quality of the PEMFC performance, which is of great significance for the commercial development of the PEMFC. Usually, in order to improve the performance of the membrane electrode, the amount of noble metal Pt used is relatively high, but this will cause Pt to stack on the surface of the proton exchange membrane, resulting in waste of some catalysts, which is not conducive to reducing the cost of the catalyst. Therefore, in view of the above problems, the platinum loading problem on the membrane electrode needs further improvement and perfection to ensure that while ensuring the high performance of the membrane electrode, the cost can be controlled and the catalyst utilization rate can be improved. Summary of the Invention

[0004] In order to improve the problem of catalyst waste caused by ensuring a high platinum loading for the current membrane electrode to ensure the high performance of the fuel cell, the present application provides a catalyst slurry for a hydrogen fuel cell, a preparation method thereof, a catalytic layer, a membrane electrode and a hydrogen fuel cell, which can improve the performance of the membrane electrode on the basis of reducing the platinum loading on the membrane electrode while ensuring the stability of the catalyst on the membrane electrode without falling off.

[0005] In the first aspect, the present application provides a catalyst slurry for a hydrogen fuel cell membrane electrode, and adopts the following technical solution: A catalyst slurry for a hydrogen fuel cell membrane electrode, comprising: a solid phase component and a liquid phase component, wherein the mass ratio of the solid phase component is 0.5%-3%, the solid phase component includes a catalyst, a carbon support and Nafion resin, the liquid phase component includes an organic solvent and water, the mass ratio of the Nafion resin to the liquid phase component is 1:160-320, and the mass ratio of the organic solvent to the water is 3.65-8.63:1.

[0006] By precisely regulating the proportion of the solid phase component in the catalyst slurry, the present invention can not only ensure sufficient catalyst active sites but also avoid excessive stacking of the catalyst, thereby achieving a balance between high performance and low cost of the hydrogen fuel cell. If the proportion of the solid phase component in the catalyst slurry is too high, it will lead to too high a catalyst loading, which not only increases the cost but also may cause stacking of the catalyst on the proton exchange membrane, affecting the catalytic efficiency. On the contrary, if the proportion of the solid phase component is too low, it is likely to result in a reduction in the active sites of the catalyst, thereby reducing the performance of the PEMFC.

[0007] By adding Nafion resin as a solid phase component to the catalyst slurry, the present invention enables the Nafion resin to play the role of fixing the catalyst and providing a proton transport channel. However, if the amount of Nafion resin used is too large, it may overly wrap the catalyst, resulting in the masking of the active sites of the catalyst, affecting the proton conductivity, and further reducing the performance of the PEMFC. Therefore, by controlling the mass ratio of the Nafion resin to the liquid phase component, the present invention can ensure the stable fixation of the catalyst and avoid negative impacts on the proton conductivity.

[0008] The organic solvent mainly plays the role of regulating the fluidity and dispersibility in the catalyst slurry. However, if the amount of the organic solvent used is too large, it may damage the activity of the platinum catalyst and even cause combustion. On the contrary, if the amount of the organic solvent is too small, it will affect the dispersion effect of the catalyst and reduce the performance of the PEMFC. Therefore, by defining the mass ratio of the organic solvent to the water, the present invention can not only ensure good fluidity and dispersibility of the catalyst slurry but also avoid damage to the activity of the platinum catalyst.

[0009] Optionally, the mass ratio of the catalyst, the carbon support and the Nafion resin is 1:0.03-0.06:0.23-0.28.

[0010] The present invention further optimizes the mass ratio among the catalyst, the carbon support and the Nafion resin to ensure the stability and activity of the catalyst. As the support of the catalyst, the content of the carbon support directly affects the dispersion effect and stability of the catalyst; while the Nafion resin plays the role of fixing the catalyst and providing a proton transport channel. By precisely regulating the ratio of these three components, the activity of the catalyst is higher and the stability is stronger, thereby improving the overall performance of the PEMFC.

[0011] Optionally, the organic solvent includes any one of ethanol and isopropyl alcohol.

[0012] Optionally, the catalyst is a Pt / C catalyst with a platinum content of 50%.

[0013] The present invention selects a Pt / C catalyst with a platinum content of 50%. This catalyst has high catalytic activity and stability, and can achieve high performance at a low loading. At the same time, the cost of this catalyst is relatively low, which is beneficial to reducing the overall cost of PEMFC.

[0014] Optionally, the carbon support is an XC-72 carbon support.

[0015] In a second aspect, the present application provides a method for preparing a catalyst slurry for a hydrogen fuel cell membrane electrode, adopting the following technical solution: A method for preparing a catalyst slurry for a hydrogen fuel cell membrane electrode, comprising the following steps: Step S1: Mix the catalyst, the carbon support and the water, and disperse to obtain a first dispersion solution; Step S2: Mix the Nafion resin with a part of the organic solvent, and disperse to obtain a second dispersion solution; Step S3: Mix the first dispersion solution, the second dispersion solution and the remaining organic solvent, and obtain the catalyst slurry for the hydrogen fuel cell membrane electrode after stirring, ultrasonic dispersion, shearing and pulverization.

[0016] Optionally, the mass ratio of the organic solvent added in Step S2 to the organic solvent used in Step S3 is 2-3:3.

[0017] The method for preparing the catalyst slurry of the present invention is simple and easy to implement, and the prepared catalyst slurry has excellent fluidity and dispersibility, so that the performance and service life of PEMFC are significantly improved. At the same time, due to the precise control of the proportion and steps of each component in the preparation process, the prepared catalyst slurry has high stability and consistency.

[0018] In a third aspect, the present application provides a catalytic layer for a hydrogen fuel cell membrane electrode, adopting the following technical solution: A catalytic layer for a hydrogen fuel cell membrane electrode is obtained by the following method: Adsorb the proton exchange membrane on the heating platform of the spraying device, control the temperature at 70-85 °C, and then spray the catalyst slurry on both the anode and cathode sides of the proton exchange membrane, thereby obtaining a catalytic layer formed on both sides of the proton exchange membrane.

[0019] Optionally, the catalyst loading in the catalytic layer is 0.1-0.7 mg / cm 2 。

[0020] Optionally, the thickness of the proton exchange membrane is 8-18 μm.

[0021] Optionally, the spraying speed of the catalyst slurry is 100-300 mm / s.

[0022] By using the above-precisely regulated catalyst slurry, the present invention can evenly distribute the catalyst with a relatively low loading amount in the catalytic layer, and the catalyst particles do not stack, do not fall off, and are not coated by Nafion resin, showing high reaction activity.

[0023] Fourthly, the present application provides a membrane electrode for a hydrogen fuel cell, adopting the following technical solution: A membrane electrode for a hydrogen fuel cell includes a proton exchange membrane, catalytic layers formed on both sides of the proton exchange membrane, and diffusion layers outside the catalytic layers.

[0024] Optionally, the thickness of the diffusion layer is 215-250 μm.

[0025] By precisely controlling the catalyst loading amount and structure of the catalytic layer and reasonably designing the diffusion layer, the present application can maximize the utilization rate of the catalytic layer, reduce the waste of the catalyst, and the obtained membrane electrode can make full use of the catalytic activity of the catalytic layer, improving the performance and efficiency of the hydrogen fuel cell.

[0026] Fifthly, the present application provides a hydrogen fuel cell, adopting the following technical solution: A hydrogen fuel cell includes a bipolar plate and the above-mentioned membrane electrode.

[0027] The hydrogen fuel cell provided by the present invention can still maintain excellent working performance under a low platinum loading amount.

[0028] In summary, the present application includes at least one of the following beneficial effects: By precisely regulating the proportion of each component in the catalyst slurry, the present invention is beneficial to reducing the platinum loading amount in the membrane electrode, improving the utilization rate of platinum in the catalyst, obtaining a membrane electrode with better performance, and further preparing a hydrogen fuel cell with high performance. Description of the Drawings

[0029] Figure 1 is the voltage-current density curve graph of the single cells prepared in Example 1 and Comparative Examples 1-3 of the present application; Figure 2 is the performance comparison graph of the polarization curve and power density curve of the single cells prepared in Example 1 and Comparative Example 1 of the present application; Figure 3 shows the microscopic schematic diagram of the catalytic layer after testing in Example 1; Figure 4 Shows the microscopic schematic diagram of the catalyst layer after the test of Comparative Example 4. Detailed implementation manners

[0030] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] Example 1 (1) Preparation of catalyst slurry: S1: Add 400 mg of catalyst particles (Pt / C catalyst with 50% Pt mass content), 16 mg of carbon support (XC-72) and 3.9 g of deionized water into a dispersion container, and disperse to obtain Dispersion Solution 1; S2: Add 0.1 g of Nafion resin and 9.3 g of ethanol into another dispersion container, and disperse to obtain Dispersion Solution 2; S3: Finally, mix Dispersion Solution 1, Dispersion Solution 2 and 13.95 g of ethanol, and after stirring, ultrasonic dispersion, shearing and pulverization, a uniform suspension-state slurry is obtained, which is the catalyst slurry. In the catalyst slurry, the solid content is 1.87%.

[0032] (2) Preparation of membrane electrode: S4: Spray the catalyst slurry on both surfaces of the proton exchange membrane to obtain a catalyst layer attached to the surface of the proton exchange membrane. Among them, the loading of platinum on the proton exchange membrane in the catalyst layer is 0.38 mg / cm 2 , and it is distributed on the cathode and anode in a ratio of cathode:anode = 3:1; S5: Thermally press two 250-μm-thick diffusion layers (carbon paper) on both sides of the proton exchange membrane containing the catalyst layer with a binder (pressure-sensitive adhesive) to obtain a membrane electrode.

[0033] (3) Assembly of single cell: Assemble the membrane electrode prepared in (2) into a single cell for testing. The test conditions are: battery temperature 85 °C, cathode and anode humidity 50%, cathode and anode back pressure 150 kPa. The test results are shown in Figure 1 .

[0034] Example 2 (1) Preparation of catalyst slurry: S1: Add 400 mg of catalyst particles (Pt / C catalyst with 50% Pt mass content), 24 mg of carbon support (XC-72) and 3.72 g of deionized water into a dispersion container, and disperse to obtain Dispersion Solution 1; S2: Add 0.112 g of Nafion resin and 12.84 g of ethanol into another dispersion container to obtain dispersion solution two by dispersion. S3: Finally, mix dispersion solution one, dispersion solution two and 19.26 g of ethanol, and obtain a homogeneous slurry in suspension state through stirring, ultrasonic dispersion, shearing and pulverization, which is the catalyst slurry. In the catalyst slurry, the solid content is 1.47%.

[0035] (2) Prepare the membrane electrode: The same as Example 1, the loading of platinum in the catalytic layer on the proton exchange membrane is 0.29 mg / cm 2 .

[0036] (3) Assemble the single cell: The same as Example 1.

[0037] Example 3 (1) Prepare the catalyst slurry: S1: Add 400 mg of catalyst particles (Pt / C catalyst with 50% Pt mass content), 12 mg of carbon carrier (XC-72) and 3.48 g of deionized water into a dispersion container to obtain dispersion solution one by dispersion. S2: Add 0.092 g of Nafion resin and 5.08 g of isopropanol into another dispersion container to obtain dispersion solution two by dispersion. S3: Finally, mix dispersion solution one, dispersion solution two and 7.62 g of isopropanol, and obtain a homogeneous slurry in suspension state through stirring, ultrasonic dispersion, shearing and pulverization, which is catalyst slurry A. In catalyst slurry A, the solid content is 3.00%.

[0038] (2) Prepare the membrane electrode: The same as Example 1, the loading of platinum in the catalytic layer on the proton exchange membrane is 0.63 mg / cm 2 .

[0039] (3) Assemble the single cell: The same as Example 1.

[0040] Comparative Example 1 (1) Prepare the catalyst slurry: S1: Add 400 mg of catalyst particles (Pt / C catalyst with 50% Pt mass content), 16 mg of carbon carrier (XC-72) and 3.1 g of deionized water into a dispersion container to obtain dispersion solution one by dispersion. S2: Add 0.12 g of Nafion resin and 9.48 g of ethanol into another dispersion container to obtain dispersion solution two by dispersion. S3: Finally, mix dispersion solution one, dispersion solution two and 14.22 g of ethanol, and after stirring, ultrasonic dispersion, shearing and pulverization, a uniform slurry in suspension state is obtained, which is catalyst slurry A. In catalyst slurry A, the solid content is 2.92%.

[0041] (2) Prepare the membrane electrode: The same as in Example 1, the loading of platinum in the catalytic layer on the proton exchange membrane is 0.57 mg / cm 2 .

[0042] (3) Assemble the single cell: The same as in Example 1.

[0043] Comparative Example 2 (1) Prepare the catalyst slurry: S1: Add 400 mg of catalyst particles (Pt / C catalyst with 50% Pt mass content), 16 mg of carbon support (XC-72) and 3.4 g of deionized water into a dispersion container, and disperse to obtain dispersion solution one; S2: Add 0.14 g of Nafion resin and 8.98 g of ethanol into another dispersion container, and disperse to obtain dispersion solution two; S3: Finally, mix dispersion solution one, dispersion solution two and 13.48 g of ethanol, and after stirring, ultrasonic dispersion, shearing and pulverization, a uniform slurry in suspension state is obtained, which is catalyst slurry A. In catalyst slurry A, the solid content is 2.10%.

[0044] (2) Prepare the membrane electrode: The same as in Example 1, the loading of platinum in the catalytic layer on the proton exchange membrane is 0.40 mg / cm 2 .

[0045] (3) Assemble the single cell: The same as in Example 1.

[0046] Comparative Example 3 (1) Prepare the catalyst slurry: S1: Add 400 mg of catalyst particles (Pt / C catalyst with 50% Pt mass content), 16 mg of carbon support (XC-72) and 2.7 g of deionized water into a dispersion container, and disperse to obtain dispersion solution one; S2: Add 0.1 g of Nafion resin and 9.78 g of ethanol into another dispersion container, and disperse to obtain dispersion solution two; S3: Finally, mix dispersion solution one, dispersion solution two and 14.67 g of ethanol, and after stirring, ultrasonic dispersion, shearing and pulverization, a uniform slurry in suspension state is obtained, which is catalyst slurry A. In catalyst slurry A, the solid content is 1.87%.

[0047] (2) Preparation of membrane electrode: Same as Example 1, the loading of platinum in the catalytic layer on the proton exchange membrane is 0.38 mg / cm 2 .

[0048] (3) Assembly of single cell: Same as Example 1.

[0049] Comparative Example 4 (1) Preparation of catalyst slurry: S1: Add 400 mg of catalyst particles (Pt / C catalyst with 50% Pt mass content), 16 mg of carbon support (XC-72), and 3.9 g of deionized water into a dispersion container, and disperse to obtain Dispersion Solution 1; S2: Add 0.08 g of Nafion resin and 9.3 g of ethanol into another dispersion container, and disperse to obtain Dispersion Solution 2; S3: Finally, mix Dispersion Solution 1, Dispersion Solution 2, and 13.95 g of ethanol, and after stirring, ultrasonic dispersion, shearing, and pulverization, a uniform suspension-state slurry is obtained, which is Catalyst Slurry A. In Catalyst Slurry A, the solid content is 1.79%.

[0050] (2) Preparation of membrane electrode: Same as Example 1, the loading of platinum in the catalytic layer on the proton exchange membrane is 0.38 mg / cm 2 .

[0051] (3) Assembly of single cell: Same as Example 1.

[0052] It should be noted that in the above Examples and Comparative Examples, when preparing the membrane electrode in step (2), the spraying amounts of the catalyst slurries for the anode and cathode are kept consistent. For the specific component dosages of the catalyst slurries in each Example and Comparative Example, see Table 1.

[0053] Table 1 Component Dosages of Catalyst Slurries in Each Example and Comparative Example Figure 1 is the voltage-current density curve graph of the single cells prepared in Example 1 and Comparative Examples 1-3 of the present application. It can be seen from Figure 1 that as the current density continuously increases, the degree of voltage drop of the single cell prepared in Example 1 is much smaller than that of the single cells prepared in Comparative Examples 1-3. Moreover, when the current density is 2550 A / cm 2 , the voltage of the single cell prepared in Example 1 is 0.64 V, while the voltage of the cell prepared in Comparative Example 3 has dropped to 0.58 V. This shows that the working performance of the single cells prepared in Comparative Examples 1-3 is inferior to that of Example 1.

[0054] Figure 2 It is a performance comparison diagram of the polarization curve and power density curve of the single cells prepared in Example 1 and Comparative Example 1 of this application. As can be seen from Figure 2 it, at a voltage of 0.65V, the current density of the single cell prepared in Example 1 can reach 2.3 A / cm 2 or more, and the power density can reach 1.6 W / cm 2 . However, the working performance of the single cell obtained in Comparative Example 1 is inferior to that of Example 1.

[0055] Figure 3 shows the microscopic schematic diagram of the catalyst layer after testing in Example 1, Figure 4 and Figure 3 shows the microscopic schematic diagram of the catalyst layer after testing in Comparative Example 4. As can be seen from Figure 4 and

[0056] the above are all preferred embodiments of this application. The protection scope of this application is not limited by this. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A catalyst slurry for a hydrogen fuel cell membrane electrode, characterized in that: include: A solid phase component and a liquid phase component, wherein the mass ratio of the solid phase component is 0.5%-3%, the solid phase component includes a catalyst, a carbon carrier and a Nafion resin, the liquid phase component includes an organic solvent and water, the mass ratio of the Nafion resin to the liquid phase component is 1:160-320, and the mass ratio of the organic solvent to the water is 3.65-8.63:

1.

2. The catalyst slurry for hydrogen fuel cell membrane electrode according to claim 1, characterized in that: The mass ratio of the catalyst, the carbon carrier and the Nafion resin is 1:0.03-0.06:0.23-0.

28.

3. The catalyst slurry for hydrogen fuel cell membrane electrode according to claim 1, characterized in that: The organic solvent includes any one of ethanol and isopropanol.

4. The catalyst slurry for hydrogen fuel cell membrane electrode according to claim 1, characterized in that: The catalyst is a Pt / C catalyst with a platinum content of 50%.

5. The method for preparing a catalyst slurry for a hydrogen fuel cell membrane electrode according to any one of claims 1 to 4, characterized in that: The steps include: Step S1: mixing the catalyst, the carbon carrier and the water, and dispersing them to obtain a dispersion solution 1; Step S2: mixing the Nafion resin with a portion of the organic solvent and dispersing to obtain a dispersed solution 2; Step S3: The dispersion solution 1, the dispersion solution 2 and the remaining organic solvent are mixed, and the catalyst slurry for hydrogen fuel cell membrane electrode is obtained after stirring, ultrasonic dispersion, shearing and crushing.

6. The method for preparing a catalyst slurry for a hydrogen fuel cell membrane electrode according to claim 5, characterized in that: The mass ratio of the organic solvent added in step S2 to the organic solvent used in step S3 is 2-3:

3.

7. A catalyst layer for a hydrogen fuel cell membrane electrode, characterized in that: The method is as follows: the proton exchange membrane is adsorbed on a heating platform of a spraying device, the temperature is controlled at 70-85°C, and the catalyst slurry described in any one of claims 1-4 is sprayed on both sides of the anode and cathode of the proton exchange membrane, thereby obtaining a catalytic layer formed on both sides of the proton exchange membrane.

8. The catalyst layer for a hydrogen fuel cell membrane electrode according to claim 7, characterized in that: The catalyst loading in the catalyst layer is 0.1-0.7 mg / cm 2 .

9. A membrane electrode for a hydrogen fuel cell, characterized in that: The invention comprises a proton exchange membrane, a catalyst layer formed on both sides of the proton exchange membrane according to claim 8, and a diffusion layer outside the catalyst layer.

10. A hydrogen fuel cell, characterized in that: It comprises a bipolar plate and the membrane electrode as claimed in claim 9.

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