A foam inhibitor for fuel cell membrane electrode slurry, and a preparation method and application thereof

Abstract

The application discloses a kind of fuel cell membrane electrode slurry foam inhibitor and its preparation method and application.The foam inhibitor includes the following weight parts of components: polyether modified siloxane:35~45 parts;Silicone resin:12~18 parts;Polyether polyol:18~22 parts;Nano silicon dioxide:6~9 parts;Deionized water:16~19 parts.The foam inhibitor of the application can quickly eliminate the foam in slurry, while inhibiting the generation of foam;Will not have negative effect on the electrochemical performance of fuel cell membrane electrode;With good compatibility of slurry system, can keep the foam inhibition effect for a long time;Use environmentally friendly raw materials, environment-friendly, safe to use.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, specifically relating to an antifoaming agent for fuel cell membrane electrode slurry, its preparation method, and its application. Background Technology

[0002] In the fabrication of fuel cell membrane electrode assemblies (MEAs), the uniformity of the catalyst slurry directly affects the MEA's performance. Currently, during slurry preparation, stirring and mixing operations easily generate a large amount of foam, which can lead to: (1) Uneven slurry density affects the microstructure of the catalyst layer; (2) Reduced catalyst utilization rate and increased production costs; (3) It affects the electrochemical performance and service life of the membrane electrode.

[0003] Existing technologies often employ physical defoaming or the addition of traditional defoamers, but physical defoaming is inefficient, and traditional defoamers may affect the electrochemical properties of the slurry.

[0004] For example, the invention application with publication number CN120590921A discloses a low conductivity coolant, its preparation method, a hydrogen fuel cell system, and a new energy vehicle, and specifically discloses that the defoamer is one or more of organosilicon defoamers, polyether defoamers, and polyether-modified organosilicon defoamers.

[0005] For example, the invention application with publication number CN110783578A discloses a method for pre-dispersing fuel cell catalyst slurry, wherein the defoamer used is at least one of polydimethylsiloxane defoamer, polyoxypropylene polyoxyethylene glycerol ether defoamer, polyoxyethylene polyoxypropylene amine ether defoamer, and polyoxypropylene glycerol ether defoamer.

[0006] The defoamers mentioned above are all traditional defoamers, which may affect the electrochemical performance of fuel cell membrane electrode slurries when used in their preparation. Therefore, a highly efficient defoamer specifically designed for fuel cell membrane electrode slurries is needed. Summary of the Invention

[0007] To address the aforementioned shortcomings in the prior art, this invention provides an antifoaming agent for fuel cell membrane electrode slurry, its preparation method, and its application.

[0008] This invention first provides an antifoaming agent for fuel cell membrane electrode slurry, comprising the following components in parts by weight: Polyether-modified siloxane: 35-45 parts; Organosilicon resin: 12-18 parts; Polyether polyol: 18-22 parts; Nano silica: 6-9 parts; Deionized water: 16-19 parts.

[0009] Preferably, the average particle size of the nano-silica is 20~40nm.

[0010] This invention further provides a method for preparing an antifoaming agent for the fuel cell membrane electrode slurry, comprising the following steps: Step 1: Add polyether-modified siloxane, organosilicon resin and polyether polyol, and mix well; Step 2: Add nano-silica and mix thoroughly; Step 3: Add deionized water and mix well to obtain the defoamer.

[0011] Preferably, the mixing temperature in steps 1 and 2 is 65~75℃; in step 3, the mixture is cooled to room temperature before adding deionized water.

[0012] Preferably, in step 1, the mixture is stirred at a speed of 250-350 rpm for 40-50 minutes; in step 2, the mixture is stirred at a speed of 350-450 rpm for 1.2-1.8 hours; and in step 3, the mixture is stirred at a speed of 250-350 rpm for 0.5-1 hour.

[0013] The present invention further provides the application of the defoaming agent for the fuel cell membrane electrode slurry in the preparation of the fuel cell membrane electrode slurry.

[0014] Preferably, the defoaming agent is added at a mass of 0.01% to 0.2% of the fuel cell membrane electrode slurry. More preferably, the defoaming agent is added at a mass of 0.1% of the fuel cell membrane electrode slurry.

[0015] The present invention also provides a method for preparing a fuel cell membrane electrode slurry, wherein an antifoaming agent for the fuel cell membrane electrode slurry is added during the preparation process to eliminate and suppress the generation of bubbles or foam.

[0016] Polyether-modified siloxanes combine the low surface tension of siloxanes with the water solubility / dispersibility of polyethers, enabling them to rapidly penetrate the gas-liquid interface of slurry bubbles, disrupting the stability of the bubble film and achieving rapid defoaming and foam suppression. Organosilicon resins enhance the long-term effectiveness of foam suppression. Polyether polyols complement polyether-modified siloxanes, further reducing the overall surface tension of the slurry and improving foam suppression efficiency. Nano-silica can adsorb onto the surface of slurry particles, regulating the micro-interface.

[0017] Beneficial effects of this invention: (1) Highly efficient foam suppressant: The foam suppressant of the present invention can quickly eliminate bubbles in the slurry and suppress the generation of bubbles.

[0018] (2) It does not affect the electrochemical performance: It will not have a negative impact on the electrochemical performance of the fuel cell membrane electrode.

[0019] (3) Good stability: It has good compatibility with the slurry system and can maintain the antifoaming effect for a long time.

[0020] (4) Environmental protection and safety: It uses environmentally friendly raw materials, is environmentally friendly and safe to use. Attached Figure Description

[0021] Figure 1 The coating effect of slurry without adding defoamer.

[0022] Figure 2 The coating effect of slurry with added defoamer.

[0023] Figure 3 The coating effect is shown after the slurry with added defoamer has been left to stand for 1 hour. Detailed Implementation

[0024] Information on some of the compounds is as follows: Polyether-modified siloxane, containing terminal hydroxyl groups, AC-8333, Guangdong Fangzhou Chemical Industry Co., Ltd.

[0025] Organosilicon resin, SR-2406 (Dow Corning), Dow Chemical.

[0026] Polyether polyols, sebacic acid polycarbonate polyether polyols, Anhui Putan New Material Technology Co., Ltd.

[0027] Example 1 An antifoaming agent for fuel cell membrane electrode slurry comprises the following components in parts by weight: Polyether-modified siloxane: 40 parts; Organosilicon resin: 15 parts; Polyether polyol: 20 parts; Nano-silica (average particle size 30nm): 8 parts; Deionized water: 17 parts.

[0028] Preparation method: (1) Add polyether modified siloxane, organosilicon resin and polyether polyol to the reactor and stir and mix at 300 rpm for 45 minutes at 70°C. (2) Add nano silica and continue stirring at 400 rpm for 1.5 hours; (3) After cooling to room temperature, add deionized water and stir at 300 rpm for 0.5 hours to mix evenly to obtain the defoamer.

[0029] Example 2 An antifoaming agent for fuel cell membrane electrode slurry comprises the following components in parts by weight: Polyether-modified siloxane: 35 parts; Organosilicon resin: 18 parts; Polyether polyol: 22 parts; Nano-silica (average particle size 20nm): 6 parts; Deionized water: 19 parts.

[0030] Preparation method: (1) Add polyether-modified siloxane, organosilicon resin and polyether polyol to the reactor and stir and mix at 250 rpm for 50 minutes at 65°C. (2) Add nano silica and continue stirring at 350 rpm for 1.2 hours; (3) After cooling to room temperature, add deionized water and stir at 250 rpm for 1 hour to mix evenly to obtain the defoamer.

[0031] Example 3 An antifoaming agent for fuel cell membrane electrode slurry comprises the following components in parts by weight: Polyether-modified siloxane: 45 parts; Organosilicon resin: 12 parts; Polyether polyol: 18 parts; Nano-silica (average particle size 40nm): 9 parts; Deionized water: 16 parts.

[0032] Preparation method: (1) Add polyether-modified siloxane, organosilicon resin and polyether polyol to the reactor and stir and mix at 350 rpm for 40 minutes at 75°C. (2) Add nano silica and continue stirring at 450 rpm for 1.8 hours; (3) After cooling to room temperature, add deionized water and stir at 350 rpm for 0.5 hours to mix evenly to obtain the defoamer.

[0033] Example 4 Membrane electrode slurry formulation (by weight): 10% carbon catalyst (50% platinum content); 5% Nafion (stored in solution, the actual amount added is calculated based on the amount of Nafion, the solvent is an alcohol); 0.1% defoamer; 7% deionized water; the balance is isopropanol.

[0034] Slurry preparation method: (1) Pre-dispersion: The catalyst and deionized water are mixed in proportion and mechanically stirred at 200 rad / min for 10 min to obtain an aqueous solution of the catalyst.

[0035] (2) First mixing: Add Nafion solution and continue stirring at 200 rad / min for 30 min to obtain the first mixture.

[0036] (3) Second mixing: Add isopropanol and defoamer, and stir at 200 rad / min for 30 min.

[0037] (4) Ball milling dispersion: ball mill at 300 rad / min for 10 hours, stopping for 3 minutes after every 7 minutes of rotation, alternating between the two.

[0038] (5) Homogenization: Homogenize 10 times at 10000psi pressure to obtain the final slurry.

[0039] Comparative Example 1 The fuel cell membrane electrode slurry without adding defoaming agents is prepared in the same manner as in Example 4.

[0040] Comparative Example 2 The fuel cell membrane electrode slurry was prepared by adding traditional silicone defoamer S-105 (0.1% of the total slurry content). The remaining formulation and preparation steps of the fuel cell membrane electrode slurry were the same as in Example 4.

[0041] Detection Example 1 The defoaming agents and fuel cell membrane electrode slurries prepared in each embodiment and comparative example were tested. The test items are as follows: 1. Apply the prepared slurry to the PTFE film by scraping, observe the slurry coating under a metallographic microscope, and determine the antifoaming effect by observing the quality of the coating.

[0042] The coating effect of slurry without defoamer is as follows Figure 1 As shown; the coating effect of the slurry with the defoamer prepared in Example 1 is as follows. Figure 2 As shown; the coating effect of the slurry containing the defoamer prepared in Example 1 after standing for 1 hour is as follows. Figure 3 As shown. (Through) Figure 1 and Figure 2 The comparative results show that the addition of defoamer can act quickly on the slurry system, avoiding coating defects caused by residual bubbles from the source, which is crucial for improving the consistency of membrane electrodes. Figure 3 The display showed that there were still no spots after 1 hour of storage, proving that the defoamer can maintain its effect in the slurry system for a long time and will not become ineffective over time, which perfectly matches the storage, transportation and coating cycle requirements of slurry in actual production.

[0043] 2. Foam Elimination Rate Test (1) Detection principle: By simulating the stirring and shearing operations during slurry preparation, the amount of foam generated and its elimination were recorded, the foam elimination rate was calculated, and the defoaming performance of the defoaming agent was evaluated.

[0044] (2) Detection steps: Sample preparation: Add the defoaming agent to the fuel cell membrane electrode slurry in a certain proportion and stir evenly.

[0045] Foam generation: A high-speed agitator was used to stir the mixture at a certain speed for a certain period of time to simulate the foam generation during the slurry preparation process.

[0046] Foam recording: Record the foam volume before and after stirring using a graduated cylinder or image analysis equipment.

[0047] Data calculation: Foam elimination rate (%) = (Initial foam volume - Final foam volume) / Initial foam volume × 100%.

[0048] 3. Slurry viscosity change rate detection (1) Instruments and equipment: Rotational viscometer (such as Brookfield DV-S type); Rheometer (such as TA Instruments AR2000 model); Thermostatic water bath.

[0049] (2) Detection principle: The viscosity change of the slurry before and after the addition of the defoamer was measured using a viscometer, the viscosity change rate was calculated, and the effect of the defoamer on the rheological properties of the slurry was evaluated.

[0050] (3) Testing steps: Sample preparation: Experimental slurry with added defoamer and control slurry without added defoamer were prepared separately.

[0051] Viscosity measurement: The viscosity of the slurry is measured using a rotational viscometer or rheometer at a certain temperature and shear rate.

[0052] Data calculation: Viscosity change rate (%) = (Experimental group viscosity - Control group viscosity) / Control group viscosity × 100%.

[0053] 4. Battery power density change rate detection (1) Instruments and equipment: Fuel cell testing systems (such as the Scribner 850e model); Electronic load tester; Gas flow controller.

[0054] (2) Detection principle: The slurry with added defoamer was prepared into a membrane electrode, assembled into a single cell, and subjected to electrochemical testing. The change in power density was measured to evaluate the effect of the defoamer on the battery performance.

[0055] (3) Testing steps: Membrane electrode preparation: The slurry is coated on both sides of the proton exchange membrane by spraying or scraping to prepare the membrane electrode (MEA).

[0056] Single cell assembly: Assemble the membrane electrode with bipolar plates, seals, etc., to form a single cell.

[0057] Electrochemical testing: The polarization curve is tested under certain operating conditions using a fuel cell testing system, and the relationship between current density and voltage is recorded.

[0058] Test conditions: Anode-cathode metering ratio: 1.5 / 1.7; Back pressure: 160 kPa / 150 kPa; Humidity: 50% / 40%; Calculation conditions: Current density 2A / cm² 2 .

[0059] Data calculation: Power density (W / cm) 2 = Current density (A / cm) 2 ) × voltage (V); Power density change rate (%) = (Power density of experimental group - Power density of control group) / Power density of control group × 100%.

[0060] Table 1 The test results are shown in Table 1. Comparative analysis of the test results of the examples and comparative examples: (1) Foam elimination rate: The foam elimination rate of the defoamer of the present invention reaches 97%-99%, which is much higher than that without the addition of defoamer, and also better than traditional silicone defoamers.

[0061] (2) Slurry viscosity change rate: The defoamer of the present invention has little effect on the slurry viscosity, with a change rate of <6%, which is much lower than that without the addition of defoamer and also better than traditional silicone defoamers.

[0062] (3) Battery power density change rate: The defoaming agent of the present invention has a very small impact on battery performance, with a change rate of <2.5%, which is much lower than the case of not adding defoaming agent and adding traditional organosilicon defoaming agent.

[0063] The above examples and comparative examples fully demonstrate the excellent performance of the antifoaming agent of the present invention in the preparation of fuel cell membrane electrode slurry, which can effectively solve the bubble problem and will not have a negative impact on the electrochemical performance of the slurry.

Claims

1. A defoaming agent for fuel cell membrane electrode slurry, characterized in that, The components include the following parts by weight: Polyether-modified siloxane: 35-45 parts; Organosilicon resin: 12-18 parts; Polyether polyol: 18-22 parts; Nano silica: 6-9 parts; Deionized water: 16-19 parts.

2. The defoaming agent for fuel cell membrane electrode slurry according to claim 1, characterized in that, The average particle size of the nano-silica is 20~40nm.

3. A method for preparing the defoaming agent for the fuel cell membrane electrode slurry according to claim 1 or 2, characterized in that, Includes the following steps: Step 1: Add polyether-modified siloxane, organosilicon resin and polyether polyol, and mix well; Step 2: Add nano-silica and mix thoroughly; Step 3: Add deionized water and mix well to obtain the defoamer.

4. The preparation method according to claim 3, characterized in that, The mixing temperature in steps 1 and 2 is 65~75℃; in step 3, the mixture is cooled to room temperature before adding deionized water.

5. The preparation method according to claim 3, characterized in that, In step 1, stir and mix at a speed of 250-350 rpm for 40-50 minutes; in step 2, stir and mix at a speed of 350-450 rpm for 1.2-1.8 hours; in step 3, stir and mix at a speed of 250-350 rpm for 0.5-1 hour.

6. The use of the defoaming agent for the fuel cell membrane electrode slurry according to claim 1 or 2 in the preparation of the fuel cell membrane electrode slurry.

7. The application according to claim 6, characterized in that, The defoaming agent is added at a mass of 0.01% to 0.2% of the fuel cell membrane electrode slurry.

8. The application according to claim 7, characterized in that, The defoaming agent is added at a mass of 0.1% of the fuel cell membrane electrode slurry.

9. A method for preparing a fuel cell membrane electrode slurry, characterized in that, During the preparation of fuel cell membrane electrode slurry, an antifoaming agent for fuel cell membrane electrode slurry as described in claim 1 or 2 is added to eliminate and suppress foam generation.

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