Catalytic layer for fuel cell and preparation method thereof

Abstract

The present invention discloses a catalytic layer for a fuel cell and a preparation method thereof. The catalytic layer comprises an anode catalyst and a cathode catalyst. The anode catalytic layer comprises: a Pt-C catalyst, a high-dielectric small-molecule alcohol, sulfonated lignin-doped conductive polymer nanoparticles, a hydrophilic adhesive, an ionomer solution, and deionized water; the cathode catalytic layer comprises a catalyst, an ionomer solution, a high-dielectric small-molecule alcohol, polytetrafluoroethylene, and deionized water. The present invention can solve the technical problems of poor water management effect and poor conductivity of the water management materials used in current fuel cell catalytic layers. The preparation method is simple and convenient, greatly reducing the difficulty of preparation and the difficulty of operation for operators.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a catalyst layer for a fuel cell and a preparation method thereof. Background Art

[0002] Fuel cells, as efficient and clean energy conversion devices, have garnered extensive attention and research in recent years. Fuel cells directly generate electricity through a chemical reaction between hydrogen and oxygen, offering advantages such as high energy conversion efficiency and minimal environmental pollution. The catalyst layer is a key component in fuel cells, directly impacting their performance and efficiency. Its primary function is to promote the electrochemical reaction between the fuel and oxidant on the electrode surface, thereby increasing the cell's output power and stability.

[0003] Water management in fuel cells is particularly challenging in low humidity or non-humidified conditions. Significant water loss from the proton exchange membrane during operation can cause deformation of the catalyst layer and compromise proton transfer efficiency. Furthermore, most currently used water management materials have poor electrical conductivity, hindering the establishment of the electron transport network in the catalyst layer and, consequently, affecting battery performance. Summary of the Invention

[0004] In order to overcome the defects of the prior art, the present invention provides a catalytic layer for fuel cells and a preparation method thereof, which can solve the technical problems of poor water management effect of the catalytic layer for fuel cells and poor conductivity of the water management materials used.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a catalyst layer for a fuel cell, comprising an anode catalyst and a cathode catalyst, wherein the anode catalyst layer comprises: a Pt-C catalyst, a high-dielectric small molecule alcohol, sulfonated lignin-doped conductive polymer nanoparticles, a hydrophilic adhesive, an ionomer solution, and deionized water;

[0007] The cathode catalyst layer comprises a catalyst, an ionomer solution, a high-dielectric small-molecule alcohol, polytetrafluoroethylene, and deionized water.

[0008] The main beneficial effects of the present invention are as follows: hydrophilic substances are added to the anode catalyst slurry of the present invention, which can support efficient water management under high current density even under low humidity conditions or non-humidification conditions; conductive polymer nanoparticles doped with sulfonated lignin are added to the anode catalyst, and sulfonated lignin has good hydrophilicity. Due to its highly branched three-dimensional structure, it can form a stable conductive network in combination with nano-conductive particles, thereby improving the overall conductivity of the catalytic layer, forming an effect of one plus one being greater than two; and polytetrafluoroethylene has good hydrophobic properties. When the battery is operated at a high current density, a large amount of water will be generated on the cathode side. PTFE can ensure that this water is quickly discharged to prevent the cathode catalyst layer from being submerged in water, thereby maintaining a good gas transmission channel.

[0009] In one embodiment, the high dielectric small molecule alcohol includes at least one of ethanol, ethylene glycol, n-propanol, and isopropanol.

[0010] The main beneficial effects of the present invention are as follows: high-dielectric small molecule alcohol can not only improve the conductivity of the catalytic layer, thereby improving the electrochemical performance of the battery, but also act as a solvent or dispersant to help the catalyst be evenly dispersed in the slurry, thereby improving the uniformity and stability of the catalytic layer.

[0011] In one embodiment, the ionomer solution includes at least one of a sulfonated polyetheretherketone solution, a sulfonated polystyrene solution, a sulfonated polysulfone solution, a sulfonated polyethylene solution, and a perfluorosulfonic acid resin solution.

[0012] In one embodiment, the hydrophilic binder comprises glycerol and / or PEG.

[0013] Hydrophilic binders not only act as dispersants to help catalyst particles disperse evenly in the slurry, thereby improving the uniformity and stability of the catalytic layer, but also improve the water management performance of the catalytic layer, ensuring the moisture distribution and transmission of the proton exchange membrane under low humidity or non-humidification conditions.

[0014] In one embodiment, in the anode catalyst layer, in the Pt-C catalyst, the Pt loading is 0.03-0.3 mg / cm 2The mass of the active ingredient in the ionomer solution is 20-80% of the mass of the C in the Pt-C catalyst, the mass of the Pt-C catalyst is 15-20% of the mass of the deionized water, the mass ratio of the deionized water to the high-dielectric small molecule alcohol is 1:(1-4), the mass of the sulfonated lignin-doped conductive polymer nanoparticles is 0.5-5% of the mass of the Pt-C catalyst, and the mass of the hydrophilic adhesive is 3-5% of the mass of the deionized water; in the cathode catalyst layer, the catalyst is at least one of a Pt-C catalyst and a Ni-Fe catalyst. The Pt loading in the Pt-C catalyst is 0.3-0.7 mg / cm 2 The mass of the active ingredient in the ionomer solution is 30-80% of the mass of C in the Pt-C catalyst, the mass of the Pt-C catalyst is 15-20% of the mass of the deionized water, the mass ratio of the deionized water to the high dielectric small molecule alcohol is 1:(1-4), and the mass of the polytetrafluoroethylene is 2-5% of the mass of the deionized water.

[0015] By using sulfonated lignin-doped conductive polymer nanoparticles within the above mass range, the hydrophilic effect and conductive effect of the sulfonated lignin-doped conductive polymer nanoparticles in the anode catalyst layer can be effectively improved, and the sulfonated lignin-doped conductive polymer nanoparticles can be more stably present in the anode catalyst. If the mass used is not within this range, the conductive properties and hydrophilic properties of the sulfonated lignin-doped conductive polymer nanoparticles will decrease.

[0016] By using polytetrafluoroethylene in the above-mentioned mass range, the hydrophobic effect and conductive effect of polytetrafluoroethylene in the cathode catalyst layer can be effectively improved, and polytetrafluoroethylene can be more stably present in the cathode catalyst. If the mass used is not within this range, the conductive and hydrophobic properties of polytetrafluoroethylene will decrease.

[0017] In a second aspect, the present invention provides a method for preparing a catalytic layer for a fuel cell, comprising the following steps: preparing an anode catalytic layer: mixing the raw materials contained in the anode catalytic layer, and scraping it on one side of a proton exchange membrane; preparing a cathode catalytic layer: mixing the raw materials contained in the cathode catalytic layer, and scraping it on the other side of the proton exchange membrane, thereby obtaining the catalytic layer for a fuel cell.

[0018] The catalyst layer for fuel cells provided by the present invention is simple and convenient, does not require complex devices and harsh temperature and other preparation conditions, and greatly reduces the difficulty of preparation and the difficulty of operation for operators.

[0019] In one embodiment, the raw materials are mixed by at least one of ultrasonic mixing, high-speed shear mixing, ball milling mixing, and high-pressure homogenization mixing.

[0020] The above-mentioned mixing method can make the structures of the anode catalyst layer and the cathode catalyst layer more stable, and avoid material precipitation.

[0021] In one embodiment, the thickness of the anode catalyst layer and the cathode catalyst layer are both 5-10 μm.

[0022] This thickness range can ensure that the anode catalyst layer and the cathode catalyst layer have good catalytic efficiency while not causing waste of raw materials.

[0023] The beneficial effects of the present invention are:

[0024] This invention achieves efficient water management by adding a hydrophilic conductive polymer (sulfonated lignin-doped conductive polymer nanoparticles) to the anode catalyst slurry and a hydrophobic material (PTFE) to the cathode catalyst slurry. Specifically, the addition of the hydrophilic conductive polymer absorbs and retains moisture, reducing drying of the proton exchange membrane and ensuring sufficient moisture on the anode side. The addition of the hydrophobic PTFE effectively prevents flooding, ensuring rapid drainage of moisture on the cathode side, maintaining a good gas transmission path, and avoiding high stack temperatures and power reduction caused by water blockage.

[0025] Furthermore, by optimizing the catalyst slurry formulation, the present invention enhances the conductivity of the catalytic layer, thereby improving the electrochemical performance of the battery. The hydrophilic conductive polymer and nano-conductive particles form a stable conductive network, enhancing the efficiency of electron and proton transmission. The addition of a high-dielectric low-molecule alcohol reduces particle agglomeration, improves powder distribution uniformity, and promotes proton conduction, increasing the ionic conductivity of the proton exchange membrane, thereby enhancing the overall performance of the battery. By adding a hydrophilic binder (such as glycerol or PEG) to the catalyst slurry, the present invention ensures uniform dispersion of catalyst particles within the slurry, improving the uniformity and stability of the catalytic layer. The hydrophilic binder reduces the interaction between catalyst particles, prevents particle agglomeration, and ensures uniform distribution of the catalyst within the catalytic layer, thereby maintaining the thickness and uniformity of the catalytic layer and improving its performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Graph showing the temperature change over time of the fuel cells prepared in Examples 1 to 3 and Comparative Examples 1 to 2 in the test examples of the present invention;

[0027] Figure 2 Graph showing the power changes over time of the fuel cells prepared in Examples 1-3 and Comparative Examples 1-2 in the test examples of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the accompanying drawings. Example

[0029] This embodiment provides a catalyst layer for a fuel cell and a method for preparing the same:

[0030] The ingredients are as follows:

[0031] Cationic catalyst layer: deionized water 100 g, ethanol 100 g, Pt-C catalyst 15 g (Pt loading is 0.03 mg / cm 2 ), 0.075 g of sulfonated lignin-doped conductive polymer nanoparticles, 2 g of glycerol, and 40 g of sulfonated polyetheretherketone solution (containing 10 wt% of sulfonated polyetheretherketone);

[0032] Cathode catalyst: deionized water 100 g, ethylene glycol 100 g, Pt-C catalyst 15 g (Pt loading is 0.3 mg / cm 2 ), 2 g of polytetrafluoroethylene, and 31.5 g of sulfonated polystyrene solution (containing 10 wt% of sulfonated polystyrene).

[0033] Here are the steps:

[0034] S1. The slurries of the anode catalyst layer and the cathode catalyst layer are mixed separately by ultrasonic mixing (10°C, 40 Hz, 30 min);

[0035] S2. Apply the dispersed anode catalyst slurry to one side of the proton exchange membrane using one of the following methods: wire rod coating, blade coating, or slit coating; prepare a membrane layer with a dry film thickness of 5 μm;

[0036] S3. Apply the dispersed cathode catalyst slurry to the other side of the proton exchange membrane by using one of the following methods: wire rod coating, scraper coating, or slit coating; prepare a membrane layer with a dry film thickness of 5 μm, thereby obtaining the catalyst layer for the fuel cell. Example

[0037] This embodiment provides a catalyst layer for a fuel cell and a method for preparing the same:

[0038] The ingredients are as follows:

[0039] Cationic catalyst layer: deionized water 100 g, ethanol 400 g, Pt-C catalyst 20 g (Pt loading is 0.3 mg / cm 2 ), 1 g of sulfonated lignin-doped conductive polymer nanoparticles, 5 g of PEG, and 56 g of sulfonated polysulfone solution (containing 20 wt% of sulfonated polysulfone);

[0040] Cathode catalyst: deionized water 100 g, ethylene glycol 400 g, Pt-C catalyst 20 g (Pt loading is 0.7 mg / cm2 ), 5 g of polytetrafluoroethylene, and 48 g of sulfonated polyethylene solution (containing 10 wt% of sulfonated polyethylene).

[0041] Here are the steps:

[0042] S1. The slurries of the anode catalyst layer and the cathode catalyst layer are mixed separately by high-speed shear mixing (15000 r / min, 10°C);

[0043] S2. Apply the dispersed anode catalyst slurry to one side of the proton exchange membrane by using one of the following methods: wire rod coating, scraper coating, or slit coating; prepare a membrane layer with a dry film thickness of 10 μm;

[0044] S3. Apply the dispersed cathode catalyst slurry to the other side of the proton exchange membrane by using one of the following methods: wire rod coating, scraper coating, or slit coating; prepare a membrane layer with a dry film thickness of 10 μm, thereby obtaining the catalyst layer for the fuel cell. Example

[0045] This embodiment provides a catalyst layer for a fuel cell and a method for preparing the same:

[0046] The ingredients are as follows:

[0047] Cationic catalyst layer: deionized water 100 g, ethanol 200 g, Pt-C catalyst 18 g (Pt loading is 0.2 mg / cm 2 ), 0.36 g of sulfonated lignin-doped conductive polymer nanoparticles, 4 g of a mixture of PEG and glycerol, and 43.2 g of a mixed solution of sulfonated polysulfone and sulfonated polystyrene (containing 10 wt% of sulfonated polysulfone and 10 wt% of sulfonated polystyrene);

[0048] Cathode catalyst: deionized water 100 g, ethylene glycol 300 g, Pt-C catalyst 16 g (Pt loading is 0.5 mg / cm 2 ), 4 g of polytetrafluoroethylene, and 28 g of a mixed solution of sulfonated polyethylene and sulfonated polyetheretherketone (containing 10 wt% of sulfonated polyethylene and 10 wt% of sulfonated polyetheretherketone).

[0049] Here are the steps:

[0050] S1. The slurries of the anode catalyst layer and the cathode catalyst layer were mixed separately by ball milling (400 r / min, 4 h, forward rotation for 25 min, reverse rotation for 25 min, and rest for 5 min);

[0051] S2. Apply the dispersed anode catalyst slurry to one side of the proton exchange membrane using one of the following methods: wire rod coating, blade coating, or slit coating; prepare a membrane layer with a dry film thickness of 8 μm;

[0052] S3. Apply the dispersed cathode catalyst slurry to the other side of the proton exchange membrane by using one of the following methods: wire rod coating, scraper coating, or slit coating; prepare a membrane layer with a dry film thickness of 8 μm, thereby obtaining the catalyst layer for the fuel cell.

[0053] Comparative Example 1

[0054] The sulfonated lignin-doped conductive polymer nanoparticles were replaced with sulfonated lignin, and the rest were the same as in Example 3.

[0055] Comparative Example 2

[0056] The polytetrafluoroethylene was removed, and the sulfonated lignin-doped conductive polymer nanoparticles were replaced with conductive polymer nanoparticles. The rest was the same as in Example 3.

[0057] Test example

[0058] The catalytic layers of Examples 1-3 and Comparative Examples 1-2 were cut into 5 cm × 5 cm single pieces, sealed by hot melt sealing, and matched with 180 μm diffusion layers to prepare 30 membrane electrode sheets, which were stacked and activated and tested for performance.

[0059] Activation conditions: hydrogen 0.1 MPa, air 0.1 MPa, flow rate of 700 mL / min, 2800 mL / min, 60% humidification, 50°C, 4 A, constant current discharge every 2 A for 30 min, 10 A, constant current discharge every 5 A for 30 min, 19 A, constant current discharge every 2 A for 30 min).

[0060] Constant current discharge conditions: hydrogen at 0.1 MPa, air at 0.1 MPa, flow rates of 700 mL / min and 2800 mL / min, 60% humidification, 50°C, and a constant current of 15 A for 100 h. Stack power and temperature were continuously recorded.

[0061] The results are as follows Figure 1 and Figure 2 As shown, according to Figure 1 and Figure 2 The results show that under the action of the cooling circulation system, the temperature of Examples 1 to 3 is constant at 50-55°C with little fluctuation. The comparative example has large fluctuations, easily generates high temperature, and the corresponding power drops sharply.

[0062] In the description of the present invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "back", "inside", "outside", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention.

[0063] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be employed in conjunction with other described embodiments.

Claims

1. A catalyst layer for a fuel cell, characterized in that: The invention comprises an anode catalyst and a cathode catalyst, wherein the anode catalyst layer comprises: a Pt-C catalyst, a high dielectric small molecule alcohol, a sulfonated lignin-doped conductive polymer nanoparticles, a hydrophilic adhesive, an ionomer solution, and deionized water; The cathode catalyst layer includes a catalyst, an ionomer solution, a high dielectric small molecule alcohol, polytetrafluoroethylene, and deionized water; The catalyst in the cathode catalyst layer is at least one of a Pt-C catalyst and a Ni-Fe catalyst; In the anode catalyst layer, the Pt loading in the Pt-C catalyst is 0.03-0.3 mg / cm 2 The mass of the active ingredient in the ionomer solution is 20-80% of the mass of C in the Pt-C catalyst, the mass of the Pt-C catalyst is 15-20% of the mass of the deionized water, the mass ratio of the deionized water to the high dielectric small molecule alcohol is 1:(1-4), the mass of the sulfonated lignin-doped conductive polymer nanoparticles is 0.5-5% of the mass of the Pt-C catalyst, and the mass of the hydrophilic adhesive is 2-5% of the mass of the deionized water; In the cathode catalyst layer, the Pt loading in the Pt-C catalyst is 0.3-0.7 mg / cm 2 The mass of the active ingredient in the ionomer solution is 30-80% of the mass of C in the Pt-C catalyst, the mass of the Pt-C catalyst is 15-20% of the mass of the deionized water, the mass ratio of the deionized water to the high dielectric small molecule alcohol is 1:(1-4), and the mass of the polytetrafluoroethylene is 2-5% of the mass of the deionized water; The high dielectric small molecule alcohol includes at least one of ethanol, ethylene glycol, n-propanol, and isopropanol; The ionomer solution comprises at least one of a sulfonated polyetheretherketone solution, a sulfonated polystyrene solution, a sulfonated polysulfone solution, a sulfonated polyethylene solution, and a perfluorosulfonic acid resin solution; The hydrophilic binder includes glycerol and / or PEG.

2. The method for preparing a catalyst layer for a fuel cell according to claim 1, wherein: The steps include: Preparation of the anode catalyst layer: mixing the raw materials of the anode catalyst layer and applying the mixture on one side of the proton exchange membrane; Preparation of cathode catalyst layer: After mixing the raw materials contained in the cathode catalyst layer, the raw materials are coated on the other side of the proton exchange membrane by scraping, thereby preparing the catalyst layer for the fuel cell.

3. The method for preparing a catalyst layer for a fuel cell according to claim 2, wherein: The raw materials are mixed by at least one of ultrasonic mixing, high-speed shear mixing, ball milling mixing, and high-pressure homogenization mixing.

4. The method for preparing a catalyst layer for a fuel cell according to claim 2, wherein: The thickness of the anode catalyst layer and the cathode catalyst layer are both 5-10 μm.

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