Carbon-based transition metal nanoparticle and single atom synergistic electrocatalyst, preparation method, application and zinc-air battery

Abstract

The application provides a carbon-based transition metal nanoparticle and single-atom synergistic electrocatalyst, a preparation method, application and a zinc-air battery, and belongs to the technical field of electrocatalysis and metal-air batteries. In the application, through the competitive anchoring and limited action of a nitrogen-containing metal chelating agent and a nitrogen-rich precursor on metal atoms in a pyrolysis process, in-situ construction and stable coexistence of transition metal nanoparticles and single atoms are realized in one step, a single-atom-nanoparticle synergistic structure is formed, the single-atom sites dominate the efficient oxygen reduction reaction, and the nanoparticle sites dominate the efficient oxygen evolution reaction. The method has the advantages of simple process, good repeatability, easy scaling from a kilogram to a kilogram, and consistent catalyst structure performance after scaling. The membrane electrode and the zinc-air battery based on the catalyst show excellent bifunctional catalytic activity, high power density and long cycle stability, and provide a complete technical solution from materials to devices for the commercialization of high-performance and low-cost zinc-air batteries.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis and metal-air battery technology, specifically relating to an electrocatalyst synergistic with carbon-based transition metal nanoparticles and single atoms, its preparation method, application, and zinc-air battery. Background Technology

[0002] The rapid development of renewable energy has created an urgent need for efficient and low-cost energy storage and conversion technologies. Zinc-air batteries, with their high theoretical energy density (1086 Wh / kg), good safety, environmental friendliness, and abundant raw materials, are considered highly promising next-generation electrochemical energy storage devices. However, their commercialization is severely hampered by the slow oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics at the air cathode. Currently, expensive noble metal catalysts (such as Pt / C for ORR and RuO2 / IrO2 for OER) are difficult to meet the dual requirements of cost and performance for commercial applications due to their high cost, limited bifunctional activity, and insufficient long-term stability.

[0003] To replace noble metal catalysts, researchers have developed various non-noble metal catalytic systems. Among them, single-atom catalysts (SACs), by maximizing the utilization efficiency of metal atoms, exhibit near-noble metal activity and excellent selectivity in ORR reactions, and have become a current research hotspot. However, single SAC structures generally show poor catalytic performance in OER processes involving multiple proton-electron transfer steps, limiting their application in reversible zinc-air batteries. On the other hand, transition metal nanoparticles (NPs) usually exhibit superior intrinsic OER activity compared to SACs, but their ORR performance is often unsatisfactory, and they are prone to aggregation, leaching, or oxidative deactivation at high potentials.

[0004] Therefore, constructing a composite catalyst containing both single atoms and nanoparticles to achieve efficient bifunctional catalysis through their synergistic effect—that is, single-atom sites dominating the ORR process and nanoparticle sites dominating the OER process—is considered an ideal strategy to address the aforementioned challenges. However, precisely controlling and stably coexisting these two active sites during material preparation remains a significant technical challenge. Existing synthetic methods, such as multi-step pyrolysis based on metal-organic frameworks (MOFs), hydrothermal synthesis combined with annealing, or plasma treatment, generally suffer from complex processes, demanding conditions, and poor reproducibility. More importantly, these methods are mostly limited to gram-scale preparation at the laboratory level, often facing challenges such as uneven mass and heat transfer, uncontrolled distribution of active sites, and inconsistent product structures during scale-up, severely hindering their transformation from laboratory research to industrial applications.

[0005] Furthermore, high-performance catalysts ultimately need to be effectively coupled with electrode fabrication processes and battery structure design to realize their advantages in practical devices. Currently, research on the compatibility between electrode fabrication technologies suitable for large-scale production (such as slurry coating and roll forming) and high-performance catalyst materials is insufficient, and a complete technical solution from material synthesis and electrode fabrication to system integration is lacking.

[0006] Therefore, developing a catalyst preparation method that is simple, easy to scale up, and can accurately construct synergistic active sites of single atoms and nanoparticles, and establishing matching electrode processes and battery technologies, is of great scientific significance and commercial value for promoting the practical application of high-performance, low-cost zinc-air batteries. Summary of the Invention

[0007] This invention is made to solve the above-mentioned problems, and aims to provide an electrocatalyst in which carbon-based transition metal nanoparticles and single atoms work together, its preparation method, its application, and a zinc-air battery.

[0008] This invention provides a method for preparing a carbon-based transition metal nanoparticle-monatomic synergistic electrocatalyst, characterized by the following steps: S10, using an aqueous ethanol solution as a solvent, preparing a mixture of a carbon precursor, a nitrogen-containing metal chelating agent, and a transition metal salt, wherein the volume ratio of ethanol to water in the aqueous ethanol solution is (8~10):1, and the molar ratio of carbon in the carbon precursor, the metal chelating agent, and the transition metal in the transition metal salt is (15~90):(6~27):(3~12); S20, drying the mixture at 60℃~80℃. S30, a solid precursor is obtained by drying; S40, the solid precursor and the nitrogen-rich precursor are mixed and ground at a mass ratio of 1:(4~6) to obtain a mixed precursor; S50, the mixed precursor is pyrolyzed in an inert atmosphere at 700℃~1000℃ for 2h~4h to obtain an electrocatalyst synergistic with carbon-based transition metal nanoparticles and single atoms, wherein the electrocatalyst synergistic with carbon-based transition metal nanoparticles and single atoms includes a nitrogen-doped carbon support and transition metal nanoparticles and transition metal single atoms supported thereon, and the transition metal nanoparticles and transition metal single atoms together constitute the catalytic active center.

[0009] The method for preparing carbon-based transition metal nanoparticles and single-atom synergistic electrocatalysts provided by the present invention may also have the following features: in step S10, the carbon precursor includes acetylene black, the metal chelating agent includes 1,10-phenanthroline monohydrate, and the transition metal salt includes any one or more of cobalt nitrate, iron nitrate, zinc nitrate, copper nitrate, nickel nitrate, and manganese nitrate; in step S30, the nitrogen-rich precursor includes dicyandiamide.

[0010] The method for preparing carbon-based transition metal nanoparticles and single-atom synergistic electrocatalysts provided by the present invention may also have the following feature: in step S10, the molar ratio of carbon in the carbon precursor, metal chelating agent and transition metal in the transition metal salt is (16.6~83.2):(6~27):(3~12).

[0011] The present invention also provides an electrocatalyst in which carbon-based transition metal nanoparticles and single atoms work together, characterized in that it is prepared by any of the aforementioned methods for preparing an electrocatalyst in which carbon-based transition metal nanoparticles and single atoms work together.

[0012] This invention also provides the application of the aforementioned carbon-based transition metal nanoparticles and single-atom synergistic electrocatalysts in electrocatalytic oxygen reduction and oxygen evolution reactions.

[0013] This invention also provides the application of the aforementioned carbon-based transition metal nanoparticles and single-atom synergistic electrocatalyst in the preparation of membrane electrodes, characterized in that the membrane electrode serves as the air cathode of a zinc-air battery. The preparation method of the membrane electrode includes the following steps: T10, dispersing the carbon-based transition metal nanoparticles and single-atom synergistic electrocatalyst with a binder in ethanol to obtain catalyst ink; T20, drying the catalyst ink to a paste state, coating it onto hydrophobic carbon paper as a gas diffusion layer, and drying it to form a catalyst layer; T30, pressing the hydrophobic carbon paper with the catalyst layer onto a nickel foam current collector to obtain the membrane electrode, wherein the loading of the carbon-based transition metal nanoparticles and single-atom synergistic electrocatalyst on the membrane electrode is 25 mg / cm³. 2 ~35mg / cm 2 .

[0014] In the application of the carbon-based transition metal nanoparticles and single-atom synergistic electrocatalyst provided by the present invention in the preparation of membrane electrodes, it may also have the following characteristics: in step T10, the binder is polytetrafluoroethylene, and the mass ratio of carbon-based transition metal nanoparticles and single-atom synergistic electrocatalyst to binder is 95:5~85:15; in step T20, the drying temperature is 70℃~90℃; and in step T30, a rolling process is used for pressing.

[0015] The present invention also provides a zinc-air battery, characterized by comprising: a positive electrode, which is the aforementioned membrane electrode, serving as the air electrode of the zinc-air battery; a negative electrode, made of Zn, disposed opposite to the positive electrode; a separator, made of glass fiber, used to separate the positive electrode and the negative electrode; and an electrolyte, which is a mixed aqueous solution of potassium hydroxide and zinc acetate.

[0016] The present invention also provides a large-scale zinc-air single cell battery, characterized by comprising: a battery casing; a negative electrode sheet made of Zn, disposed in the center inside the battery casing; two positive electrode sheets, which are the aforementioned membrane electrodes, respectively disposed on both sides of the negative electrode sheet, serving as air electrodes of the large-scale zinc-air single cell battery; and an electrolyte, which is a mixed aqueous solution of potassium hydroxide and zinc acetate.

[0017] The present invention also provides a zinc-air battery stack, characterized by being composed of several of the aforementioned large-scale zinc-air single cells connected in series via a positive electrode.

[0018] The present invention has the following beneficial effects:

[0019] (1) This invention utilizes the competitive anchoring and confinement of metal atoms by a nitrogen-containing metal chelating agent and an excess nitrogen source (nitrogen-rich precursor) during pyrolysis to simultaneously achieve the one-step realization of a single metal atom (MN). x The stable construction of the site and the in-situ generation of transition metal nanoparticles form a unique "single atom-nanoparticle" synergistic structure, realizing highly efficient bifunctional catalysis of ORR and OER.

[0020] (2) In this invention, single-atom sites serve as highly efficient ORR active centers, and nanoparticle sites serve as highly efficient OER active centers. The synergistic effect of the two enables the catalyst to exhibit excellent bifunctional oxygen electrocatalytic activity in alkaline media. At the same time, the preparation method used in this invention is simple and reproducible. It can achieve batch preparation of catalysts from gram-scale to kilogram-scale through a simple drying-grinding-pyrolysis process, and the core structure and performance of the catalyst remain consistent after scale-up.

[0021] (3) The supporting membrane electrode preparation process and large-scale battery design provided by the present invention combine high-performance catalysts with feasible device manufacturing technologies, ensuring the performance transfer from materials to devices, and providing a complete technical solution from material synthesis, electrode preparation to system integration for the commercial application of high-performance zinc-air batteries. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the preparation method of the carbon-based transition metal nanoparticles and single-atom synergistic electrocatalyst of Example 1 of the present invention.

[0023] Figure 2 These are TEM and STEM images of Co-NPs / SACs obtained from experimental group 1 of Example 1 of the present invention.

[0024] Figure 3These are the ORR and OER performance curves of Co-NPs / SACs prepared in experimental group 1 and Fe-NPs / SACs prepared in experimental group 2 of Example 1 of the present invention.

[0025] Figure 4 This is the ORR performance curve of Co-NPs / SACs prepared in batches in experimental group 3 of Example 1 of the present invention.

[0026] Figure 5 This is a flowchart illustrating the preparation method of the membrane electrode according to Embodiment 2 of the present invention.

[0027] Figure 6 This is the discharge polarization and power density curve of the zinc-air battery of Embodiment 2 of the present invention.

[0028] Figure 7 The zinc-air battery of Embodiment 2 of the present invention has a performance of 5 mA / cm 2 The constant current charge-discharge cycle curve is shown below.

[0029] Figure 8 These are physical photographs of the large-scale zinc-air single cell and its corresponding zinc-air battery stack according to Embodiment 2 of the present invention.

[0030] Figure 9 This is the discharge polarization and power curve of the large-scale zinc-air single cell of Embodiment 2 of the present invention, and its capacity under constant current discharge of 2.75 A. Detailed Implementation

[0031] To make the technical means, creative features, objectives and effects of the present invention easy to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate the present invention's carbon-based transition metal nanoparticle and single-atom synergistic electrocatalyst, preparation method, application, and zinc-air battery.

[0032] Example 1

[0033] One of the objectives of this embodiment is to provide a method for preparing an electrocatalyst that combines carbon-based transition metal nanoparticles with single atoms.

[0034] Figure 1 This is a flowchart illustrating the preparation method of the carbon-based transition metal nanoparticles and single-atom synergistic electrocatalyst of Example 1 of the present invention.

[0035] like Figure 1 As shown, the preparation method of a carbon-based transition metal nanoparticle-monopolymer electrocatalyst synergistically combined with a single atom according to the present invention includes the following steps:

[0036] S10, prepare the precursor mixture, the specific operation is as follows:

[0037] A carbon precursor, a nitrogen-containing metal chelating agent, and a transition metal salt were added to an aqueous ethanol solution and ultrasonically dispersed to obtain a mixture.

[0038] The specific material selection / parameters are as follows: (1) The carbon precursor is acetylene black. (2) The nitrogen-containing metal chelating agent is 1,10-phenanthroline monohydrate. (3) The transition metal salt includes any one or more of cobalt nitrate, iron nitrate, zinc nitrate, copper nitrate, nickel nitrate, and manganese nitrate. (4) The ethanol aqueous solution is obtained by mixing ethanol and deionized water at a volume ratio of (8~10):1. (5) The molar ratio of carbon in the carbon precursor, metal chelating agent, and transition metal in the transition metal salt is (16.6~83.2):(6~27):(3~12). (6) Ultrasonic dispersion for at least 1 hour.

[0039] S20, Obtaining a solid precursor: The mixture obtained in step S10 is dried at 60℃~80℃ for 10h~15h to obtain a solid precursor.

[0040] S30, Mixing the solid precursor with the nitrogen-rich precursor: The solid precursor obtained in step S30 and the nitrogen-rich precursor are mixed at a mass ratio of 1:(4~6) and mechanically ground for 30 minutes to obtain a mixed precursor. The nitrogen-rich precursor is dicyandiamide.

[0041] S40, one-step pyrolysis to prepare the final catalyst: the mixed precursor obtained in step S30 is pyrolyzed at 700℃~1000℃ for 2h~4h in an inert atmosphere (argon), and then naturally cooled to obtain an electrocatalyst synergistic between carbon-based transition metal nanoparticles and single atoms.

[0042] The second objective of this embodiment is to provide an electrocatalyst synergistic between carbon-based transition metal nanoparticles and single atoms, which is prepared by the aforementioned method. The electrocatalyst synergistic between carbon-based transition metal nanoparticles and single atoms comprises a nitrogen-doped carbon support and transition metal nanoparticles and transition metal single atoms supported thereon, with the transition metal nanoparticles and transition metal single atoms together constituting the catalytic active center.

[0043] In this embodiment, by changing the parameters in the aforementioned preparation method, three experiments were conducted, which were designated as Experiment Group 1, Experiment Group 2, and Experiment Group 3, respectively. Three electrocatalysts synergistically combining carbon-based transition metal nanoparticles and single atoms were prepared. The specific parameters for the three experimental groups are shown in Table 1 below:

[0044] Table 1 (Specific parameters of experimental group 1, experimental group 2 and experimental group 3)

[0045]

[0046] In Table 1 above, the products of experimental groups 1 and 3, “electrocatalysts synergistically composed of carbon-based transition metal nanoparticles and single atoms”, are denoted as Co-NPs / SACs; the product of experimental group 2, “electrocatalysts synergistically composed of carbon-based transition metal nanoparticles and single atoms”, is denoted as Fe-NPs / SACs.

[0047] As shown in Table 1 above, this embodiment achieved the batch preparation of Co-NPs / SACs from the milligram level to the hundred-gram level through experimental groups 1 and 3.

[0048] Figure 2 These are TEM and STEM images of Co-NPs / SACs obtained from experimental group 1 of Example 1 of the present invention.

[0049] like Figure 2 As shown, uniformly distributed nanoparticles (approximately 15 nm) are visible in the TEM image, while bright single-atom bright spots are visible in the STEM image, confirming the successful construction of the Co nanoparticle-single-atom synergistic structure.

[0050] The third objective of this embodiment is to provide the application of the aforementioned carbon-based transition metal nanoparticles and single-atom synergistic electrocatalysts in electrocatalytic oxygen reduction and oxygen evolution reactions.

[0051] Figure 3 These are the ORR and OER performance curves of Co-NPs / SACs prepared in experimental group 1 and Fe-NPs / SACs prepared in experimental group 2 of Example 1 of the present invention.

[0052] like Figure 3 As shown in the figure, this embodiment tested the products of experimental groups 1 and 2, and both Co-NPs / SACs and Fe-NPs / SACs exhibited excellent bifunctional catalytic performance. For ORR, the half-wave potentials reached 0.90 V and 0.91 V (vs. RHE), respectively; for OER, at 10 mA / cm 2 The overpotentials at the current densities are 338 mV and 266 mV, respectively.

[0053] Figure 4 This is the ORR performance curve of Co-NPs / SACs prepared in batches in experimental group 3 of Example 1 of the present invention.

[0054] like Figure 4 As shown in the figure, this embodiment tested the products prepared in batches of experimental group 3. The Co-NPs / SACs, scaled up 2000 times, exhibited excellent oxygen reduction catalytic performance. For ORR, its half-wave potential reached 0.90 V (vs. RHE), indicating that the material can still maintain excellent oxygen reduction reaction performance after scale-up preparation.

[0055] Example 2

[0056] One of the objectives of this embodiment is to provide an application of carbon-based transition metal nanoparticles and single-atom synergistic electrocatalysts in the preparation of membrane electrodes, based on Example 1.

[0057] Figure 5 This is a flowchart illustrating the preparation method of the membrane electrode according to Embodiment 2 of the present invention.

[0058] like Figure 5 As shown, the fabrication method of the membrane electrode in this embodiment includes the following steps:

[0059] T10, Modified Catalyst Ink:

[0060] Take 20 mg of the product of experimental group 1 or experimental group 2 in the examples (carbon-based transition metal nanoparticles and single-atom synergistic electrocatalysts Co-NPs / SACs or Fe-NPs / SACs) and disperse it with 10% by mass of binder (polytetrafluoroethylene) in 10 mL of ethanol and sonicate for 1 h to obtain a uniform catalyst ink.

[0061] T20, obtaining the catalyst layer:

[0062] After drying the catalyst ink at 80℃ to a semi-dry paste state, it is evenly coated onto an area of ​​1 cm². 2 A catalyst layer is formed on hydrophobic carbon paper, which serves as a gas diffusion layer, and then air-dried naturally.

[0063] T30, pressed together to obtain the membrane electrode:

[0064] A membrane electrode is obtained by pressing hydrophobic carbon paper with a catalyst layer onto a nickel foam current collector layer using a rolling process.

[0065] The second objective of this embodiment is to provide a zinc-air battery by using the aforementioned membrane electrode.

[0066] The zinc-air battery in this embodiment includes a positive electrode, a negative electrode, a separator, and an electrolyte.

[0067] The positive electrode is the aforementioned membrane electrode (the electrocatalyst of carbon-based transition metal nanoparticles and single atoms is Co-NPs / SACs from Experimental Group 1), which serves as the air electrode of the zinc-air battery.

[0068] The negative electrode is made of Zn and is positioned opposite the positive electrode.

[0069] The separator is made of glass fiber and is used to separate the positive electrode and the negative electrode.

[0070] The electrolyte is a mixed aqueous solution of potassium hydroxide (6M concentration) and zinc acetate (0.2M concentration).

[0071] Figure 6 This is the discharge polarization and power density curve of the zinc-air battery of Embodiment 2 of the present invention.

[0072] like Figure 6 As shown, the peak power density of the zinc-air battery based on Co-NPs / SACs reaches 304 mW / cm². 2 The peak power density of the zinc-air battery based on Co-NPs / SACs reached 334 mW / cm². 2 .

[0073] Figure 7 The zinc-air battery of Embodiment 2 of the present invention has a performance of 5 mA / cm 2 The constant current charge-discharge cycle curve is shown below.

[0074] like Figure 7 As shown, the zinc-air battery based on Co-NPs / SACs operates at 5 mA / cm². 2 After more than 1800 hours of stable cycling, the charge-discharge voltage gap remained stable, demonstrating excellent cycle stability.

[0075] The third objective of this embodiment is to provide large-scale zinc-air single-cell batteries and their corresponding zinc-air battery stacks.

[0076] The large-scale zinc-air cell in this embodiment includes a cell casing, a negative electrode, a positive electrode, and an electrolyte. The corresponding zinc-air cell stack is composed of several large-scale zinc-air cells connected in series via their respective positive electrodes.

[0077] Specifically in this embodiment:

[0078] The internal dimensions of the battery casing are 28.5 × 20.5 × 3.0 cm. 3 .

[0079] The negative electrode is made of Zn and is located in the center inside the battery casing, with an area of ​​250 cm². 2 The thickness is 2 mm.

[0080] The positive electrode is the aforementioned membrane electrode, numbered two, each with an area of ​​250 cm². 2 These electrodes are positioned on both sides of the negative electrode, serving as air electrodes for large-scale zinc-air single-cell batteries. The Co-NPs / SACs loading on each positive electrode is 31.6 mg / cm³. 2 .

[0081] The electrolyte is a 450 mL aqueous solution of potassium hydroxide (6 M concentration) and zinc acetate (0.2 M concentration), which is kept in a flowing state during battery operation.

[0082] Figure 8 These are physical photographs of the large-scale zinc-air single cell and its corresponding zinc-air battery stack according to Embodiment 2 of the present invention.

[0083] like Figure 8 As shown, the large-scale zinc-air single-cell battery has a compact structural design (total volume of 28.5 × 20.5 × 3.0 cm). 3 This demonstrates good engineering feasibility. The zinc-air battery stack, composed of 10 individual cells connected in series, can achieve a total output voltage of over 12 V, meeting the requirements of practical applications.

[0084] Figure 9 This is the discharge polarization and power curve of the large-scale zinc-air single cell of Embodiment 2 of the present invention, and its capacity under constant current discharge of 2.75 A.

[0085] like Figure 9 As shown, the peak power of the large-scale zinc-air single cell reached 19.18 W, and the discharge capacity of 82.48 Ah was obtained under constant current discharge of 2.75 A, proving that it has the characteristics of high power output and high capacity required for practical applications.

[0086] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an electrocatalyst synergistically composed of carbon-based transition metal nanoparticles and single atoms, characterized in that, Includes the following steps: S10, using an aqueous ethanol solution as a solvent, prepares a mixture of a carbon precursor, a nitrogen-containing metal chelating agent, and a transition metal salt, wherein the volume ratio of ethanol to water in the aqueous ethanol solution is (8~10):1, the molar ratio of carbon in the carbon precursor, the metal chelating agent, and the transition metal in the transition metal salt is (15~90):(6~27):(3~12), the carbon precursor includes acetylene black, and the metal chelating agent includes 1,10-phenanthroline monohydrate; S20, the mixture is dried at 60℃~80℃ to obtain a solid precursor; S30, the solid precursor and the nitrogen-rich precursor are mixed and ground at a mass ratio of 1:(4~6) to obtain a mixed precursor, wherein the nitrogen-rich precursor includes dicyandiamide; S40, the mixed precursor is pyrolyzed in an inert atmosphere at 700℃~1000℃ for 2h~4h to obtain the carbon-based transition metal nanoparticle and single-atom synergistic electrocatalyst. The electrocatalyst, in which carbon-based transition metal nanoparticles and single atoms work together, includes a nitrogen-doped carbon support and transition metal nanoparticles and transition metal single atoms supported thereon, wherein the transition metal nanoparticles and the transition metal single atoms together constitute the catalytic active center.

2. The method for preparing the carbon-based transition metal nanoparticle and single-atom synergistic electrocatalyst according to claim 1, characterized in that: in, In step S10, the transition metal salt includes any one or more of cobalt nitrate, ferric nitrate, zinc nitrate, copper nitrate, nickel nitrate, and manganese nitrate.

3. The method for preparing the carbon-based transition metal nanoparticle-monopolymer synergistic with single-atom electrocatalyst according to claim 1 or 2, characterized in that: in, In step S10, the molar ratio of carbon in the carbon precursor, the metal chelating agent, and the transition metal in the transition metal salt is (16.6~83.2):(6~27):(3~12).

4. An electrocatalyst synergistic between carbon-based transition metal nanoparticles and single atoms, characterized in that, It is prepared by the method for preparing carbon-based transition metal nanoparticles and single-atom synergistic electrocatalysts as described in any one of claims 1 to 3.

5. The application of the carbon-based transition metal nanoparticles and single-atom synergistic electrocatalyst as described in claim 4 in electrocatalytic oxygen reduction reaction and oxygen evolution reaction.

6. The application of the carbon-based transition metal nanoparticles and single-atom synergistic electrocatalyst as described in claim 4 in the preparation of membrane electrodes, characterized in that, The membrane electrode serves as the positive air electrode in a zinc-air battery. The method for preparing the membrane electrode includes the following steps: T10, the carbon-based transition metal nanoparticles, along with a single-atom synergistic electrocatalyst and binder, are dispersed in ethanol to obtain catalyst ink; T20, after the catalyst ink is dried to a paste state, it is coated onto hydrophobic carbon paper as a gas diffusion layer and dried to form a catalyst layer; T30, the hydrophobic carbon paper with the catalyst layer is laminated with a nickel foam current collector to obtain the membrane electrode. The loading of the carbon-based transition metal nanoparticles and the single-atom synergistic electrocatalyst on the membrane electrode is 25 mg / cm³. 2 ~35mg / cm 2 .

7. The application of the carbon-based transition metal nanoparticles and single-atom synergistic electrocatalyst according to claim 6 in the preparation of membrane electrodes, characterized in that: in, In step T10, the binder is polytetrafluoroethylene, and the mass ratio of the carbon-based transition metal nanoparticles and the single-atom synergistic electrocatalyst to the binder is 95:5~85:

15. In step T20, the drying temperature is 70℃~90℃. In step T30, the pressing process is performed using a rolling process.

8. A zinc-air battery, characterized in that, include: The positive electrode is the film electrode as described in claim 6 or 7, serving as the air electrode of the zinc-air battery; The negative electrode, made of Zn, is positioned opposite to the positive electrode. The separator, made of glass fiber, is used to separate the positive electrode and the negative electrode. as well as The electrolyte is a mixed aqueous solution of potassium hydroxide and zinc acetate.

9. A large-scale zinc-air single-cell battery, characterized in that, include: Battery casing; The negative electrode sheet, made of Zn, is located in the center of the inside of the battery casing; The positive electrode, being the film electrode as described in claim 6 or 7, comprises two electrodes, respectively disposed on both sides of the negative electrode, serving as the air electrode of the large-scale zinc-air single-cell battery; and The electrolyte is a mixed aqueous solution of potassium hydroxide and zinc acetate.

10. A zinc-air battery stack, characterized in that, The large-scale zinc-air single cell battery as described in several claims 9 is connected in series through the positive electrode.

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