A preparation method of a battery catalyst layer based on upright graphene, a battery catalyst layer and applications

Abstract

The present invention belongs to the technical field of battery material preparation, and specifically relates to a preparation method of a battery catalyst layer based on upright graphene, a battery catalyst layer and its application, comprising: immersing carbon paper in a graphene oxide gel solution to obtain a first reactant; sequentially adding a first solution and a second solution to the first reactant to obtain a second reactant; adding a metal salt solution precursor and a reducing agent to the second reactant to obtain a third reactant; heat treating the third reactant under a protective atmosphere to obtain a battery catalyst layer. The present invention provides an efficient transmission channel for substances by constructing a structured graphene network structure, effectively reducing the interface transmission loss within the electrode and between the membrane electrode; at the same time, the catalyst layer has high catalytic activity, conductivity and stability, and the prepared catalyst layer and diffusion layer carbon paper have high bonding strength.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery material preparation, and in particular relates to a preparation method of a battery catalyst layer based on upright graphene, a battery catalyst layer and an application thereof. Background Art

[0002] With the acceleration of industrialization and the growth of global population, the demand for energy has increased dramatically. Although traditional fossil fuels such as coal, oil and natural gas provide a large amount of energy for modern society, they also bring serious environmental problems such as air pollution, water pollution and global warming. Therefore, finding clean, renewable and sustainable energy alternatives has become an important direction of current scientific research.

[0003] Fuel cells are a new type of electrochemical technology that can directly convert the chemical energy of fuel into electrical energy. They have the advantages of high efficiency, environmental protection, and safety, and are considered to be an important development direction in the future energy field. In fuel cells, the oxygen reduction reaction is a key step that affects the performance and efficiency of the battery. In order to increase the rate of the oxygen reduction reaction, researchers often use various precious metal materials, such as gold, palladium, and platinum, as catalysts.

[0004] However, these precious metal catalysts face some challenges in practical applications. First, it is very difficult to construct a three-phase interface (i.e., the transmission interface of ions / electrons / gas), which leads to large losses in transmission impedance and affects the transmission efficiency of substances in the fuel cell membrane electrode. Second, precious metal catalysts are expensive and have limited resources, which restricts their promotion in large-scale practical applications.

[0005] In order to solve these problems, researchers began to explore ways to construct ordered electrodes to reduce material transmission losses and improve the performance of fuel cells. Among them, using highly conductive upright graphene to build a "highway" for electron transmission is a creative attempt. Graphene is a two-dimensional material composed of a single layer of carbon atoms with extremely high conductivity and mechanical strength. By arranging graphene upright, a three-dimensional network structure can be formed, providing a channel for rapid transmission of electrons, thereby solving the problem of disordered material transmission in the three-phase interface. Summary of the invention

[0006] (I) Purpose of the invention

[0007] The purpose of the present invention is to provide a preparation method of a battery catalyst layer based on upright graphene, a battery catalyst layer and an application thereof, which can improve the transmission characteristics, catalytic activity, conductivity and stability of the battery catalyst layer.

[0008] (II) Technical solution

[0009] In order to solve the above problems, the present invention provides a method for preparing a battery catalyst layer based on upright graphene, comprising:

[0010] The carbon paper is immersed in the graphene oxide gel solution to obtain a first reactant;

[0011] Adding a first solution and a second solution to the first reactant in sequence to obtain a second reactant, wherein the first solution comprises water and an organic solvent, and the second solution comprises urea and aqueous ammonia;

[0012] adding a metal salt solution precursor and a reducing agent to the second reactant to obtain a third reactant;

[0013] The third reactant is heat-treated under a protective atmosphere to obtain a battery catalyst layer based on upright graphene.

[0014] In another aspect of the present invention, preferably, the concentration of the graphene oxide gel solution is 1-10 mg / ml; the mass ratio of the first solution, the second solution and graphene oxide is 50-60:1-3:1; the mass ratio of the metal salt solution precursor and the reducing agent to graphene oxide is 1-10:3-10:1.

[0015] In another aspect of the present invention, preferably, the organic solvent comprises methanol and dimethylformamide, and the molar ratio of water:methanol:dimethylformamide is 10-20:2-5:5-10.

[0016] In another aspect of the present invention, preferably, the mass ratio of urea to aqueous ammonia is 1-10:1.

[0017] In another aspect of the present invention, preferably, the first solution and the second solution are sequentially added to the first reactant, the temperature for obtaining the second reactant is 20-200° C., and the reaction time is 1-40 hours.

[0018] In another aspect of the present invention, preferably, the reducing agent includes at least one of NaBH4, hydrazine hydrate, LiBH4, formaldehyde and ethylene glycol; the metal salt solution precursor includes at least one of H2PtCl6·6H2O, a mixture of H2PtCl6·6H2O and PdCl2, a mixture of H2PtCl6·6H2O and Na2PdCl4, a mixture of H2PtCl6·6H2O and K2PdCl6, a mixture of H2PtCl6·6H2O and FeCl3, a mixture of H2PtCl6·6H2O and CoCl2 or a mixture of H2PtCl6·6H2O and CuCl2.

[0019] In another aspect of the present invention, preferably, a metal salt solution precursor and a reducing agent are added to the second reactant to obtain the third reactant in a reaction time of 1-24 hours, a temperature of 20-150° C., and a pH range of 10-12.

[0020] In another aspect of the present invention, preferably, the third reactant is heat treated under a protective atmosphere to obtain a protective atmosphere in the battery catalyst layer of nitrogen or argon, and the heat treatment adopts a high-temperature sintering process, which includes heating the temperature to 200-800°C at a heating rate of 2-5°C / min, and the sintering time is 0.1-12 hours.

[0021] In another aspect of the present invention, preferably, a battery catalyst layer is prepared by the preparation method as described above.

[0022] In another aspect of the present invention, preferably, an application of a catalyst layer prepared by the preparation method as described above is characterized in that: the catalyst layer is used to prepare an anode and / or a cathode of a battery membrane electrode.

[0023] (III) Beneficial effects

[0024] The above technical solution of the present invention has the following beneficial technical effects:

[0025] The present invention combines carbon paper with graphene by immersing carbon paper in graphene oxide gel solution, which not only enhances the conductivity of the electrode, but also provides strong support for the subsequent construction of the catalyst layer. By constructing a structured graphene network structure, an efficient transmission channel is provided for the material, and the interface transmission loss in the electrode and between the membrane electrode is effectively reduced; the first solution and the second solution are sequentially added to the first reactant to obtain the second reactant; the addition of these two solutions adjusts the microenvironment of the catalyst layer, optimizes its pore structure and surface properties, and thus provides favorable conditions for the subsequent deposition of metal ions; the addition of the metal salt solution precursor introduces metal ions with catalytic activity, and the metal ions are reduced to metal particles under the action of the reducing agent and deposited on the graphene surface to form catalytic active sites. The reducing agent simultaneously reduces the graphene oxide, and the high specific surface area and good conductivity of the graphene optimize the uniform dispersion of the metal particles. The third reactant is heat-treated under a protective atmosphere to obtain a battery catalyst layer. Further promote the combination between metal particles and graphene, and improve the stability and durability of the catalyst layer.

[0026] The catalytic layer prepared by the present invention is directly deposited on the carbon paper and can be directly used as the electrode layer, which not only improves the bonding force between the catalytic layer and the diffusion layer carbon paper, but also simplifies the preparation process of the electrode layer. The service life is longer, the comprehensive performance and development prospects are good, and the application and promotion are suitable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is an overall flow chart of an embodiment of the present invention;

[0028] Figure 2 Schematic diagram of upright graphene-supported Pt catalyst;

[0029] Figure 3 This is a catalyst polarization curve diagram of the upright graphene catalyst prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0031] Obviously, the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be noted that the terms “first”, “second” and “third” are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0033] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] Example

[0035] A method for preparing a battery catalyst layer based on upright graphene, Figure 1 FIG. 1 shows an overall flow chart of an embodiment of the present invention, as shown in FIG. Figure 1 As shown, including:

[0036] Immersing carbon paper in a graphene oxide gel solution to obtain a first reactant; carbon paper, i.e., carbon fiber paper, is widely used as a gas diffusion layer in a proton exchange membrane of a fuel cell and is one of the indispensable materials for a hydrogen fuel cell. The main functions of carbon paper are mass transfer, electrical conduction, heat transfer, and support for a catalytic layer, etc.; the specific type of carbon paper is not limited here, nor is the specific content of the graphene oxide gel solution. Optionally, in this embodiment, the concentration of the graphene oxide gel solution is 1-10 mg / ml; this step is to prepare upright graphene, and by constructing a structured graphene network structure, an efficient transmission channel is provided for the material, effectively reducing the interface transmission loss within the electrode and between the membrane electrode;

[0037] The first solution and the second solution are sequentially added to the first reactant to obtain the second reactant; the specific content of the first solution is not limited here, and optionally, in this embodiment, the first solution includes water and an organic solvent; the organic solvent includes methanol and dimethylformamide, and the molar ratio of water: methanol: dimethylformamide is 10-20:2-5:5-10; the specific content of the second solution is not limited here either, and optionally, in this embodiment, the second solution includes urea and ammonia water, and the mass ratio of urea to ammonia water is 2-5:1; the first solution and the second solution are added to adjust the microenvironment of the catalyst layer, optimize its pore structure and surface properties, and thus provide favorable conditions for subsequent metal ion deposition; the addition of water and organic solvents can control the wettability and dispersibility of the catalyst layer, while urea and ammonia water may serve as nitrogen sources to introduce nitrogen doping into the catalyst layer to further improve its catalytic activity;

[0038] The specific environment for obtaining the second reactant by sequentially adding the first solution and the second solution to the first reactant is not limited here. Optionally, in this embodiment, the mass ratio of the first solution, the second solution and the graphene oxide is 50-60:1-3:1; the first solution and the second solution are sequentially added to the first reactant to obtain the second reactant at a temperature of 20-200°C, and the reaction time is 1-40 hours. Further, during the heating reaction, the first solution and the second solution are sequentially added to the first reactant and then sealed in a hydrothermal reactor for reaction;

[0039] A metal salt solution precursor and a reducing agent are added to the second reactant to obtain a third reactant; the specific content of the metal salt solution precursor is not limited here, and the mass ratio of the metal salt solution precursor and the reducing agent to graphene oxide is 1-10:3-10:1; optionally, in this embodiment, the metal salt solution precursor includes H2PtCl6■6H2O, a mixture of H2PtCl6■6H2O and PdCl2, a mixture of H2PtCl6■6H2O and Na2PdCl4, a mixture of H2PtCl6■6H2O and K2PdCl6, a mixture of H2PtCl6■6H2O and FeCl3, a mixture of H2PtCl6■6H2O and CoCl2, or a mixture of H2PtCl6■6H2O and CuCl2 At least one of the reducing agent, the specific content of the reducing agent is not limited here, optionally, the reducing agent includes at least one of NaBH4, hydrazine hydrate, LiBH4, formaldehyde and ethylene glycol; further, in this embodiment, a metal salt solution precursor and a reducing agent are added to the second reactant to obtain a third reactant for a reaction time of 1-24 hours, a temperature of 20-150°C, and a pH range of 10-12; a metal salt solution precursor and a reducing agent are added to the second reactant, so that the metal ions are reduced to metal particles on the surface of graphene to form a third reactant; these metal particles, as catalytic active centers, can effectively promote the redox reaction in the fuel cell; the high specific surface area and good electrical conductivity of graphene ensure the uniform distribution and efficient utilization of the metal particles;

[0040] The third reactant is heat treated under a protective atmosphere to obtain a battery catalyst layer based on upright graphene. Further, in this embodiment, the third reactant is heat treated under a protective atmosphere to obtain a battery catalyst layer based on upright graphene, wherein the protective atmosphere is nitrogen or argon, and the heat treatment adopts a high-temperature sintering process, and the high-temperature sintering process includes heating to 200-800°C at a heating rate of 2-5°C / min, and the sintering time is 0.1-12 hours. Figure 2 A schematic diagram of upright graphene-supported Pt catalyst is shown, Figure 2 As shown, the catalytic layer directly deposited on the carbon paper can be used directly as the electrode layer, which not only improves the bonding strength between the catalytic layer and the diffusion layer carbon paper, but also simplifies the preparation process of the electrode layer; this tightly combined structure helps to reduce the contact resistance and interface resistance, and improve the overall performance of the battery; due to the good compatibility and stability between the catalytic layer and the carbon paper, the service life of the battery is significantly extended; at the same time, the catalytic layer prepared by this method also performs well in conductivity, thermal stability and mechanical strength, and has good comprehensive performance and development prospects.

[0041] A battery catalyst layer is prepared by the preparation method as described above.

[0042] An application of a catalyst layer prepared by the preparation method as described above, wherein the catalyst layer is used to prepare an anode and / or a cathode of a battery membrane electrode.

[0043] Example 1

[0044] Select 1cm 2 The carbon paper is immersed in 100 ml of graphene oxide gel solution, the concentration of the graphene oxide gel solution is 1 mg / ml, and a first reactant is obtained;

[0045] Add 29 ml of water, 6 ml of methanol and 15 ml of dimethylformamide to prepare the first solution;

[0046] A second solution prepared by adding 0.1 g of urea and 0.2 g of ammonia water was added, and the mixture was sealed in a hydrothermal reactor and heated to 20° C. for reaction for 40 hours to obtain a second reactant;

[0047] Add 0.1 g of a mixture of H2PtCl6·6H2O and Na2PdCl4 to the second reactant and adjust the pH value to 10, add 0.3 g of LiBH4 for reduction, and react at 20° C. for 24 hours to achieve deposition of Pd and Pt particles on the upright graphite surface, thereby obtaining a third reactant;

[0048] The third reactant was heat treated under a protective atmosphere, heated to 200°C at a heating rate of 2°C / min under argon protection and sintered for 12 hours to obtain a battery catalyst layer, which was used as an electrode layer after the surface was cleaned with ethanol.

[0049] Example 2

[0050] Select 1cm 2 The carbon paper is immersed in 100 ml of graphene oxide gel solution, the concentration of the graphene oxide gel solution is 5 mg / ml, and a first reactant is obtained;

[0051] Add 20 ml of water, 3 ml of methanol and 5 ml of dimethylformamide to prepare the first solution;

[0052] A second solution prepared by adding 0.5 g of urea and 0.5 g of ammonia water was added, and the mixture was sealed in a hydrothermal reactor and heated to 160° C. for reaction for 8 hours to obtain a second reactant;

[0053] 0.5 g H2PtCl6■6H2O was added to the second reactant and the pH value was adjusted to 11, and NaBH4 was added for reduction, and the reaction was carried out at 60°C for 10 hours to achieve the deposition of Fe particles on the vertical graphite surface, thereby obtaining a third reactant;

[0054] The third reactant was heat treated under a protective atmosphere, heated to 350°C at a heating rate of 5°C / min under nitrogen protection, and sintered for 2 hours to obtain a battery catalyst layer, which was used as an electrode layer after the surface was cleaned with ethanol. Figure 3 The catalyst polarization curve of the upright graphene catalyst prepared in Example 2 of the present invention is shown. The blue curve is the electrode performance curve of this embodiment, and the red curve is the electrode performance curve of Comparative Example 2.

[0055] Example 3

[0056] Select 1cm 2 The carbon paper is immersed in 100 ml of graphene oxide gel solution, the concentration of the graphene oxide gel solution is 10 mg / ml, and a first reactant is obtained;

[0057] Add 40 ml of water, 10 ml of methanol and 10 ml of dimethylformamide to prepare the first solution;

[0058] A second solution prepared by adding 2.7 g of urea and 0.3 g of ammonia water was added, and the mixture was sealed in a hydrothermal reactor and heated to 200° C. for reaction for 1 hour to obtain a second reactant;

[0059] Add 10g of H2PtCl6■6H2O and CuCl2 mixture to the second reactant, adjust the pH value to 11, add 10g of hydrazine hydrate for reduction, react at 150°C for 1 hour, achieve deposition of Pt and Cu particles on the vertical graphite surface, and obtain a third reactant;

[0060] The third reactant was heat treated under a protective atmosphere, heated to 800°C at a heating rate of 5°C / min under argon protection and sintered for 0.1 hour to obtain a battery catalyst layer, which was used as an electrode layer after the surface was cleaned with ethanol.

[0061] The comparison of the electrode performance of Examples 1-3 and Comparative Examples 1-3 is shown in Table 1;

[0062] Table 1 Comparison of electrode performance of Examples 1-3 and Comparative Examples 1-3

[0063]

[0064] In summary, the catalyst layer prepared by the present invention has good transmission characteristics, can effectively reduce the interface transmission loss between the membrane electrode, thereby improving the performance of the membrane electrode, and has high catalytic activity, conductivity and stability.

[0065] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

[0066] The present invention has been described above with reference to the embodiments of the present invention. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents. Without departing from the scope of the present invention, a person skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

[0067] Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.

[0068] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing a battery catalyst layer based on upright graphene, characterized in that: include: The carbon paper is immersed in the graphene oxide gel solution to obtain a first reactant; Adding a first solution and a second solution to the first reactant in sequence to obtain a second reactant, wherein the first solution comprises water and an organic solvent, and the second solution comprises urea and aqueous ammonia; adding a metal salt solution precursor and a reducing agent to the second reactant to obtain a third reactant; Heat treating the third reactant under a protective atmosphere to obtain a battery catalyst layer based on upright graphene; The organic solvent includes methanol and dimethylformamide, and the molar ratio of water:methanol:dimethylformamide is 10-20:2-5:5-10; The mass ratio of the urea to the aqueous ammonia is 1-10:

1.

2. The preparation method according to claim 1, characterized in that: The concentration of the graphene oxide gel solution is 1-10 mg / ml; the mass ratio of the first solution, the second solution and graphene oxide is 50-60:1-3:1; the mass ratio of the metal salt solution precursor and the reducing agent to graphene oxide is 1-10:3-10:

1.

3. The preparation method according to claim 1, characterized in that: The first solution and the second solution are sequentially added to the first reactant, the temperature for obtaining the second reactant is 20-200° C., and the reaction time is 1-40 hours.

4. The preparation method according to claim 1, characterized in that: The reducing agent includes at least one of NaBH4, hydrazine hydrate, LiBH4, formaldehyde and ethylene glycol; the metal salt solution precursor includes at least one of H2PtCl6·6H2O, a mixture of H2PtCl6·6H2O and PdCl2, a mixture of H2PtCl6·6H2O and Na2PdCl4, a mixture of H2PtCl6·6H2O and K2PdCl6, a mixture of H2PtCl6·6H2O and FeCl3, a mixture of H2PtCl6·6H2O and CoCl2, or a mixture of H2PtCl6·6H2O and CuCl2.

5. The preparation method according to claim 1, characterized in that: The metal salt solution precursor and the reducing agent are added to the second reactant to obtain the third reactant. The reaction time is 1-24 hours, the temperature is 20-150° C., and the pH value ranges from 10-12.

6. The preparation method according to claim 1, characterized in that: The third reactant is heat treated under a protective atmosphere to obtain a protective atmosphere of nitrogen or argon in the battery catalyst layer. The heat treatment adopts a high-temperature sintering process, which includes heating the temperature to 200-800°C at a heating rate of 2-5°C / min and a sintering time of 0.1-12 hours.

7. A battery catalyst layer, characterized in that: The battery catalyst layer is prepared using the preparation method described in any one of claims 1-6.

8. An application of a catalyst layer prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The catalytic layer is used to prepare the anode and / or cathode of the battery membrane electrode.

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