Preparation method and storage of high-batch stability catalyst layer slurry

Abstract

The invention relates to a preparation method and storage of high-batch stability catalyst layer slurry, and belongs to the technical field of catalyst layer slurry. A fuel cell membrane electrode is a core component of a fuel cell stack, and the batch stability of the membrane electrode is a key index of batch production, so that the stability of a catalyst layer slurry system is a key factor for determining the batch stability of the membrane electrode. The catalyst layer slurry which is uniformly dispersed through ultrasonic, ball milling, shearing and the like can be dried into powder to be stored through a spray drying method, the powder is re-dispersed during use, and since no dispersion liquid exists in a storage state, the deterioration of a solvent in the storage process can be greatly improved, and the stability of the catalyst layer is improved. And moreover, low-concentration catalyst layer slurry can be prepared during the first dispersion, so that the dispersion uniformity of the catalyst is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic layer slurry, and relates to a preparation method and storage of catalytic layer slurry with high batch stability. Background Art

[0002] Fuel cells are devices that convert fuel directly into electrical energy through chemical reactions. They are highly efficient, clean, and low-emission, and are widely used in transportation, energy storage, industrial production, and other fields. One of the core components of a fuel cell is the membrane electrode, which has the important function of electrochemically reacting fuel and oxygen. The batch stability of the membrane electrode is a key indicator for mass production, so the stability of the catalyst layer slurry system is a key factor in determining the batch stability of the membrane electrode.

[0003] Traditional fuel cell membrane electrodes are usually composed of carbon supports, catalysts, and ion transport membranes, among which catalysts are the key to electrochemical reactions. However, traditional catalysts have problems such as high cost, poor stability, and low activity, which limit the development and application of fuel cells. In the process of preparing the catalytic layer slurry and storing it, factors such as catalyst agglomeration and the oxidation of the solvent into substances such as aldehyde acids will reduce the consistency of the slurry. Chinese patent application CN202210653700.5 discloses a method for preparing a catalyst slurry. Since there are catalyst particles that are insoluble in the solvent in the slurry system, the system belongs to a thermodynamically unstable suspension, and the slurry is easy to settle. In the large-scale preparation process, the different properties of the upper and lower slurry systems due to sedimentation result in significant batch differences, which reduces the yield rate. Therefore, an advanced preparation method and storage technology are needed to ensure efficient catalytic layer performance and long-term stability. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing and storing a catalyst layer slurry with high batch stability, which has the characteristics of stable performance and high consistency.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a catalyst layer slurry with high batch stability, the preparation method process is as follows:

[0007] S1: dispersing perfluorosulfonic acid resin PFSA and catalyst in a mixed solvent of alcohol and water, wherein the ratio of alcohol to water is 1 to 5:1, and preparing a catalyst slurry with a concentration of 1 to 5%, wherein the IC ratio of the added perfluorosulfonic acid resin to the catalyst is 0.6;

[0008] S2: The mixed solution prepared in S1 was placed in a ball mill for grinding at a speed of 300 r / min for 48 h to obtain a fully dispersed catalyst slurry;

[0009] S3: Dry the mixed solution obtained in S2 using a spray dryer to obtain a powder, using hot nitrogen as the drying gas at a drying temperature of 90° C. Collect the dried powder and store it in a cool and dry place;

[0010] The storage environment requirements are: the storage environment temperature is 25°C, the storage environment humidity is 20-30%, the storage environment is a nitrogen-filled sealed packaging container, and the storage environment is a light-proof environment;

[0011] S4: After storage for a period of time, the catalyst slurry is prepared with a solid content of 5 to 12%, and then put into a ball mill for mixing according to a ratio of deionized water to alcohol compound of 3:2. The ball mill is used for mixing for 2 hours at a speed of 300 r / min to obtain a catalytic layer slurry, which is then prepared into a membrane electrode by ultrasonic spraying to test its performance.

[0012] Furthermore, the catalyst in S1 is one or more of platinum / carbon, platinum black, and platinum alloy catalysts.

[0013] Furthermore, the drying gas flow rate in S3 is 4 to 6 m / s.

[0014] Furthermore, the alcohol compound in S4 is one or more of methanol, ethanol, isopropanol, and n-propanol.

[0015] Furthermore, the catalyst slurry particles obtained by ball milling in S4 have a particle size of micrometer level.

[0016] Furthermore, the parameters of the ultrasonic spraying in S4 are: ultrasonic frequency 30 kHz, spraying distance 10 cm, spraying rate 200 mm / s, and spraying pressure 0.6 MPa.

[0017] Furthermore, the storage duration in S4 is 24 to 744 hours.

[0018] The spray drying method has the following advantages: liquid materials can be converted into powder in a short time, thus improving production efficiency; through spray drying, powders with uniform particle size and uniform particle distribution can be obtained; by adjusting the process parameters, the particle size and shape of the powder can be controlled. This method is simple in process and easy to operate and master.

[0019] In the traditional catalyst slurry process, alcohol is easily oxidized to aldehyde by oxygen in the air, especially under the catalysis of platinum catalysts, the degree of this reaction is greatly increased. However, the presence of aldehydes will deteriorate the catalyst slurry, the prepared catalyst layer is prone to cracking, and the product yield rate is reduced. After the catalyst slurry is prepared into powder, the present invention does not have easily oxidized alcohol, and there is no degradation reaction, which can greatly increase the storage time, improve efficiency and production capacity.

[0020] After being prepared into powder, the resin and catalyst particles are fully dispersed and can quickly reach the expected dispersion state during the redispersion process. Online preparation can be achieved to reduce the slurry standing time and weaken the impact of slurry sedimentation on the membrane electrode product batch.

[0021] Beneficial effects of the present invention:

[0022] The present invention proposes a method for preparing a high-consistency catalyst layer slurry, which can improve the consistency of the catalyst layer slurry in the membrane electrode production process; the present invention uses dry powdered catalyst layer slurry for storage, which can greatly increase the storage time of the catalyst layer slurry; the present invention provides a catalyst slurry that can be prepared and used immediately during the production process to maintain the stability between product batches; the present invention provides a catalyst slurry preparation method with high uniformity, which can increase the life of the membrane electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0024] Figure 1 Performance diagram of the membrane electrode cell prepared in Example 1;

[0025] Figure 2 Performance diagram of the membrane electrode cell prepared in Example 2. DETAILED DESCRIPTION

[0026] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0027] Example 1

[0028] S1: dissolving perfluorosulfonic acid resin PFSA and catalyst in a mixed solvent of ethanol and water, wherein the ratio of alcohol to water is 1:1, and preparing a mixed solution of catalyst and PFSA with a concentration of 1%, wherein the IC ratio is 0.6;

[0029] S2: The mixed solution prepared in S1 is put into a ball mill for grinding at a speed of 300 r / min for 48 h to obtain a fully dissolved and dispersed mixed solution;

[0030] S3: The mixed solution obtained in S2 is dried using a spray dryer to obtain a powder, using hot nitrogen as the drying gas, the drying temperature is 90°C, and the drying gas flow rate is 4 m / s. The dried powder is collected and stored in a cool and dry place;

[0031] The storage environment requirements are: the storage environment temperature is 25°C, the storage environment humidity is 20-30%, the storage environment is a sealed packaging container, the storage environment is a light-proof environment, and the storage environment is a stable and shock-proof environment;

[0032] S4: After storage for 24h, 336h, and 744h, respectively, a catalyst slurry with a solid content of 5% was prepared, and then mixed in a ball mill with a mass ratio of deionized water to ethanol of 3:2. The ball milling time was 2 hours, and the ball mill speed was 300r / min to obtain a catalyst layer slurry. The membrane electrode was prepared by ultrasonic spraying to test the performance. The test results are shown in Figure 1 .

[0033] Example 2

[0034] S1: Dissolve perfluorosulfonic acid resin PFSA and catalyst in a mixed solvent of ethanol and water, with the ratio of ethanol to water being 5:1, and prepare a mixed solution of catalyst and PFSA with a concentration of 5%, wherein the IC ratio is 0.6;

[0035] S2: The mixed solution prepared in S1 is put into a ball mill for grinding at a speed of 300 r / min for 48 h to obtain a fully dissolved and dispersed mixed solution;

[0036] S3: Dry the mixed solution obtained in S2 using a spray dryer to obtain a powder, using hot nitrogen as the drying gas, the drying temperature is 90°C, the drying gas flow rate is 6 m / s, collect the dried powder, and store it in a cool and dry place;

[0037] The storage environment requirements are: the storage environment temperature is 25°C, the storage environment humidity is 20-30%, the storage environment is a sealed packaging container, the storage environment is a light-proof environment, and the storage environment is a stable and shock-proof environment;

[0038] S4: After storage for 24h, 336h, and 744h, respectively, a catalyst slurry with a solid content of 12% was prepared, and then mixed in a ball mill with a mass ratio of deionized water to ethanol of 3:2. The ball milling time was 2 hours, and the ball mill speed was 300r / min to obtain a catalyst layer slurry. The membrane electrode was prepared by ultrasonic spraying to test the performance. The test results are shown in Figure 2 .

[0039] From the test results of Examples 1 and 2, it can be seen that the performance of the membrane electrode cell prepared with the catalyst layer slurry prepared by this method is basically the same after storage for 24h, 336h, and 744h, indicating that the catalyst layer slurry obtained by this preparation method and after storage has stable performance and high consistency.

[0040] When the present invention is used:

[0041] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a catalyst layer slurry with high batch stability, characterized in that: The preparation method process is as follows: S1: dispersing perfluorosulfonic acid resin PFSA and catalyst in a mixed solvent of alcohol and water, wherein the ratio of alcohol to water is 1 to 5:1, and preparing a catalyst slurry with a concentration of 1 to 5%, wherein the IC ratio of the added perfluorosulfonic acid resin to the catalyst is 0.6; S2: The mixed solution prepared in S1 was placed in a ball mill for grinding at a speed of 300 r / min for 48 h to obtain a fully dispersed catalyst slurry; S3: Dry the mixed solution obtained in S2 using a spray dryer to obtain a powder, using hot nitrogen as the drying gas at a drying temperature of 90° C. Collect the dried powder and store it in a cool and dry place; The storage environment requirements are: the storage environment temperature is 25°C, the storage environment humidity is 20-30%, the storage environment is a nitrogen-filled sealed packaging container, and the storage environment is a light-proof environment; S4: After storage for a period of time, the catalyst slurry is prepared with a solid content of 5 to 12%, and then put into a ball mill for mixing according to a ratio of deionized water to alcohol compound of 3:

2. The ball mill is used for mixing for 2 hours at a speed of 300 r / min to obtain a catalytic layer slurry, which is then prepared into a membrane electrode by ultrasonic spraying to test its performance.

2. The method for preparing a catalyst layer slurry with high batch stability according to claim 1, characterized in that: The catalyst in S1 is one or more of platinum / carbon, platinum black, and platinum alloy catalysts.

3. The method for preparing a catalyst layer slurry with high batch stability according to claim 1, characterized in that: The drying gas flow rate in S3 is 4-6 m / s.

4. The method for preparing a catalyst layer slurry with high batch stability according to claim 1, characterized in that: The alcohol compound in S4 is one or more of methanol, ethanol, isopropanol and n-propanol.

5. The method for preparing a catalyst layer slurry with high batch stability according to claim 1, characterized in that: The catalyst slurry powder obtained by ball milling in S4 has a size of micron level.

6. The method for preparing a catalyst layer slurry with high batch stability according to claim 1, characterized in that: The parameters of the ultrasonic spraying in S4 are: ultrasonic frequency 30 kHz, spraying distance 10 cm, spraying rate 200 mm / s, and spraying pressure 0.6 MPa.

7. The method for preparing a catalyst layer slurry with high batch stability according to claim 1, characterized in that: The storage duration in S4 is 24 to 744 hours.

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