Catalytic layer for fuel cell and preparation method thereof

Abstract

The invention discloses a catalyst layer for a fuel cell and a preparation method thereof, the catalyst layer comprises an anode catalyst and a cathode catalyst, the anode catalyst layer comprises a Pt-C catalyst, high dielectric micromolecular alcohol, sulfonated lignin doped conductive polymer nanoparticles, a hydrophilic adhesive, an ionomer solution and deionized water; the cathode catalyst layer comprises a catalyst, an ionomer solution, high-dielectric micromolecular alcohol, polytetrafluoroethylene and deionized water; the technical problems that an existing catalyst layer for a fuel cell is poor in water management effect, and an adopted water management material is poor in conductivity can be solved. The preparation method is simple and convenient, and the preparation difficulty and the operation difficulty of operators are greatly reduced.

Description

Technical Field

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

[0002] As an efficient and clean energy conversion device, fuel cells have received extensive attention and research in recent years. Fuel cells directly generate electricity through the chemical reaction of hydrogen and oxygen, and have the advantages of high energy conversion efficiency and low environmental pollution. In fuel cells, the catalyst layer is one of the key components and directly affects the performance and efficiency of the battery. The main function of the catalyst layer is to promote the electrochemical reaction of fuel and oxidant on the electrode surface, thereby improving the output power and stability of the battery.

[0003] Water management in fuel cells is particularly difficult under low humidity or non-humidification conditions. The water loss of the proton exchange membrane during operation will not only cause deformation of the catalyst layer, but also affect the proton transfer efficiency. At the same time, most of the water management materials currently used have poor electrical conductivity, which affects the establishment of the electron transfer network in the catalyst layer, thereby affecting the performance of the battery. Summary of the invention

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

[0005] The object of the present invention is achieved through the following technical solutions: 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; The cathode catalyst layer comprises a catalyst, an ionomer solution, a high dielectric small molecule alcohol, polytetrafluoroethylene and deionized water.

[0006] 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 the sulfonated lignin has good hydrophilicity. Due to its highly branched three-dimensional structure, it can form a stable conductive network with the 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 the water is quickly discharged to avoid the cathode catalyst layer being submerged by water, thereby maintaining a good gas transmission channel.

[0007] In one embodiment, the high dielectric small molecule alcohol includes at least one of ethanol, ethylene glycol, n-propanol, and isopropanol.

[0008] The main beneficial effects of the present invention are as follows: high dielectric small molecule alcohol can not only improve the conductivity of the catalyst layer, thereby improving the electrochemical performance of the battery, but also act as a solvent or dispersant to help the catalyst to be evenly dispersed in the slurry, thereby improving the uniformity and stability of the catalyst layer.

[0009] 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.

[0010] In one embodiment, the hydrophilic binder comprises glycerol and / or PEG.

[0011] The hydrophilic binder can not only act as a dispersant to help the 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 and ensure the moisture distribution and transmission of the proton exchange membrane under low humidity or non-humidification conditions.

[0012] In one embodiment, in the anode catalyst layer, in the Pt-C catalyst, the Pt loading is 0.03-0.3 mg / cm 2, the mass of the effective component 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 sulfonated lignin-doped conductive polymer nanoparticles are 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. In the Pt-C catalyst, the Pt loading is 0.3-0.7 mg / cm 2 The mass of the effective 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.

[0013] By using the sulfonated lignin doped conductive polymer nanoparticles in 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 the range, the conductive performance and hydrophilic performance of the sulfonated lignin doped conductive polymer nanoparticles will decrease. 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.

[0014] 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 them 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 them on the other side of the proton exchange membrane, thereby obtaining the catalytic layer for a fuel cell.

[0015] The catalyst layer for fuel cells provided by the present invention is simple and convenient, does not require complicated devices and harsh preparation conditions such as temperature, and greatly reduces the difficulty of preparation and the difficulty of operation for operators.

[0016] 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.

[0017] 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.

[0018] In one embodiment, the thickness of the anode catalyst layer and the cathode catalyst layer are 5-10 μm respectively.

[0019] 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.

[0020] The beneficial effects of the present invention are: The present 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 can absorb and retain moisture, reduce the drying phenomenon of the proton exchange membrane, and ensure sufficient moisture on the anode side; while the addition of the hydrophobic material PTFE can effectively prevent flooding, ensure that the moisture on the cathode side is quickly discharged, maintain a good gas transmission channel, and avoid high temperature and power reduction of the battery stack caused by water blockage.

[0021] In addition, the present invention improves the conductivity of the catalyst layer by optimizing the formula of the catalyst slurry, thereby improving the electrochemical performance of the battery. The hydrophilic conductive polymer and the nano-conductive particles can form a stable conductive network and improve the transmission efficiency of electrons and protons; the addition of high-dielectric small molecule alcohol can reduce particle agglomeration, improve the uniformity of powder distribution, and promote the conduction of protons, improve the ion conductivity of the proton exchange membrane, thereby improving the overall performance of the battery. By adding a hydrophilic binder (such as glycerol, PEG) to the catalyst slurry, the present invention ensures the uniform dispersion of the catalyst particles in the slurry and improves the uniformity and stability of the catalyst layer. The hydrophilic binder can reduce the interaction force between the catalyst particles, prevent the particles from agglomerating, and ensure the uniform distribution of the catalyst in the catalyst layer, thereby ensuring the thickness and uniformity of the catalyst layer and improving the performance of the catalyst layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The temperature of the fuel cells prepared in Examples 1 to 3 and Comparative Examples 1 to 2 in the test examples of the present invention varies with time; Figure 2 This is a graph showing the power variation 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. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings. Example

[0024] This embodiment provides a catalyst layer for a fuel cell and a method for preparing the same: The ingredients are as follows: 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); 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).

[0025] Here are the steps: 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); S2, applying the dispersed anode catalyst slurry on one side of the proton exchange membrane by wire rod coating, scraper coating, or slit coating; preparing a membrane layer with a dry film thickness of 5 μm; S3. Apply the dispersed cathode catalyst slurry to the other side of the proton exchange membrane by using a wire rod coating, a scraper coating, or a slit coating method; prepare a membrane layer with a dry film thickness of 5 μm, and obtain the catalyst layer for the fuel cell. Example

[0026] This embodiment provides a catalyst layer for a fuel cell and a method for preparing the same: The ingredients are as follows: Cationic catalyst layer: 100 g deionized water, 400 g ethanol, 20 g Pt-C catalyst (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); Cathode catalyst: 100 g deionized water, 400 g ethylene glycol, 20 g Pt-C catalyst (Pt loading is 0.7 mg / cm 2 ), 5 g of polytetrafluoroethylene, and 48 g of sulfonated polyethylene solution (containing 10 wt% of sulfonated polyethylene).

[0027] Here are the steps: S1. The slurries of the anode catalyst layer and the cathode catalyst layer are mixed respectively by high-speed shear mixing (15000 r / min, 10°C); S2, applying the dispersed anode catalyst slurry on one side of the proton exchange membrane by wire rod coating, scraper coating, or slit coating; preparing a membrane layer with a dry film thickness of 10 μm; S3. Apply the dispersed cathode catalyst slurry to the other side of the proton exchange membrane by using a wire rod coating, a scraper coating, or a slit coating method; prepare a membrane layer with a dry film thickness of 10 μm, and obtain the catalyst layer for the fuel cell. Example

[0028] This embodiment provides a catalyst layer for a fuel cell and a method for preparing the same: The ingredients are as follows: 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); 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).

[0029] Here are the steps: S1. The slurries of the anode catalyst layer and the cathode catalyst layer are 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); S2, applying the dispersed anode catalyst slurry on one side of the proton exchange membrane by wire rod coating, scraper coating, or slit coating; preparing a membrane layer with a dry film thickness of 8 μm; S3. Apply the dispersed cathode catalyst slurry to the other side of the proton exchange membrane by wire rod coating, scraper coating, or slit coating; prepare a membrane layer with a dry film thickness of 8 μm, and obtain the catalyst layer for the fuel cell.

[0030] Comparative Example 1 The sulfonated lignin-doped conductive polymer nanoparticles were replaced with sulfonated lignin, and the rest was the same as in Example 3.

[0031] Comparative Example 2 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.

[0032] Test example The catalyst layers of Examples 1-3 and Comparative Examples 1-2 were cut into 5 cm×5 cm single pieces, which were plastic-sealed by hot-melt plastic sealing and matched with a 180 μm diffusion layer to prepare 30 membrane electrodes, which were stacked, activated and tested for performance.

[0033] 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 for 30 min every 2 A, 10 A, constant current discharge for 30 min every 5 A, 19 A, constant current discharge for 30 min every 2 A).

[0034] Constant current discharge conditions: hydrogen 0.1 MPa, air 0.1 MPa, flow rate 700 mL / min, 2800 mL / min, 60% humidification, 50°C, 15 A constant current discharge for 100 h. The stack power and temperature were continuously recorded.

[0035] 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 to 55°C, with less fluctuation. The comparative example has a large fluctuation, is prone to high temperature, and the corresponding power drops sharply.

[0036] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "bottom", "top", "front", "back", "inside", "outside", "left", "right", etc. indicate orientations or positional relationships based on the orientations 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 orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0037] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A catalyst layer for a fuel cell, characterized in that: It includes an anode catalyst and a cathode catalyst, wherein the anode catalyst layer includes: 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 catalyst layer comprises a catalyst, an ionomer solution, a high dielectric small molecule alcohol, polytetrafluoroethylene and deionized water.

2. The fuel cell catalyst layer according to claim 1, characterized in that: The high dielectric small molecule alcohol includes at least one of ethanol, ethylene glycol, n-propanol and isopropanol.

3. The fuel cell catalyst layer according to claim 1, characterized in that: 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.

4. The fuel cell catalyst layer according to claim 1, characterized in that: The hydrophilic binder includes glycerol and / or PEG.

5. The fuel cell catalyst layer according to claim 1, characterized in that: The catalyst in the cathode catalyst layer is at least one of a Pt-C catalyst and a Ni-Fe catalyst.

6. The fuel cell catalyst layer according to claim 5, characterized in that: In the anode catalyst layer, in the Pt-C catalyst, the Pt loading is 0.03-0.3 mg / cm 2 , the mass of the effective component 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, in the Pt-C catalyst, the Pt loading is 0.3-0.7 mg / cm 2 The mass of the effective 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.

7. A method for preparing a catalyst layer for a fuel cell according to any one of claims 1 to 5, characterized in that: The steps include: Preparing an anode catalyst layer: mixing the raw materials contained in the anode catalyst layer, and then coating the mixture on one side of a 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, so as to obtain the catalyst layer for the fuel cell.

8. The method for preparing a catalyst layer for a fuel cell according to claim 6, characterized in that: The raw materials are mixed by at least one of ultrasonic mixing, high-speed shear mixing, ball milling mixing and high-pressure homogenization mixing.

9. The method for preparing a catalyst layer for a fuel cell according to claim 6, characterized in that: The thickness of the anode catalyst layer and the cathode catalyst layer are 5-10 μm respectively.

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