Phosphorus-carbon negative electrode material, in-situ coating preparation method and application thereof

Abstract

The application discloses a phosphorus-carbon negative electrode material and an in-situ coating preparation method and application thereof, and belongs to the technical field of lithium / sodium battery materials. The method comprises the following steps: S1, mixing a porous carbon carrier with red phosphorus, heating to sublimate the red phosphorus, and then cooling to deposit the red phosphorus in the porous carbon carrier to obtain a core material; S2, heating the core material in an oxidizing atmosphere to oxidize the surface red phosphorus of the core material; and S3, dispersing the oxidized core material and conductive carbon in a solvent, and adding an alkali to react to obtain a phosphorus-carbon negative electrode material. The method forms a strong chemical bonding in-situ interface between the coating layer and the core, the interface is stable and does not peel off, the problems of red phosphorus sublimation and structure damage caused by traditional high-temperature carbon coating are avoided, high specific capacity, long cycle life and excellent rate performance can be realized, and a new scheme is provided for obtaining high-energy-density lithium / sodium ion batteries.

Description

Technical Field

[0001] This invention relates to the field of lithium / sodium battery materials technology, specifically to a phosphorus-carbon anode material and its in-situ coating preparation method and application. Background Technology

[0002] The development of electric vehicles, large-scale energy storage, and portable electronic devices has placed higher demands on the energy density, cycle life, and safety of rechargeable batteries. Lithium-ion and sodium-ion batteries, as mainstream energy storage technologies, rely heavily on anode materials for their performance. Traditional graphite anodes have a theoretical specific capacity of only 372 mAh / g, which is insufficient to meet high energy density requirements. Phosphorus, due to its high theoretical specific capacity, suitable potential, and abundant reserves, is considered a promising next-generation anode material. However, phosphorus-based materials experience significant volume expansion (>300%) during charge and discharge, leading to active material pulverization, detachment from the current collector, and damage to the solid electrolyte interface film, resulting in rapid capacity decay. Furthermore, their low electronic and ionic conductivity limits rate performance.

[0003] To address these issues, researchers have attempted to combine phosphorus with porous carbon materials. A vapor-phase deposition method is used to deposit red phosphorus into the pores of porous carbon. The porous carbon framework structure can, to some extent, limit volume expansion and construct a conductive network to improve the material's conductivity. For example, Chinese patent application CN109216682A discloses a phosphorus-based anode material, which uses an evaporation-deposition method to prepare a phosphorus / porous carbon composite material, followed by graphene coating. While this method improves the material's conductivity, the adhesion between the coating layer and the core is primarily physical, resulting in weak interfacial bonding and a tendency for peeling during long-term cycling.

[0004] Furthermore, the high reactivity of deposited nano-red phosphorus makes it prone to spontaneous combustion upon contact with air, significantly increasing the difficulty of storage and transportation. Simultaneously, phosphorus and its lithiation / sodiumation products are soluble in the electrolyte, leading to the loss of active materials and a continuous decline in battery capacity. Coating the phosphorus-carbon material to prevent direct contact with air or electrolyte can alleviate these problems. However, current mainstream carbon coating technologies typically require the construction of a conductive hard carbon layer at high temperatures, while nano-red phosphorus will re-sublimate at high temperatures, damaging the material structure. Moreover, while single-material carbon coating can provide electronic conductivity channels, it offers limited improvement in ion transport, making it difficult to simultaneously optimize both electronic and ionic conductivity. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a phosphorus-carbon anode material, its in-situ coating preparation method and application, so as to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] One aspect of this application discloses a method for in-situ coating preparation of the above-mentioned phosphorus-carbon anode material, which can be referred to... Figure 1 This includes the following steps:

[0008] S1. After mixing the porous carbon support with red phosphorus, place it in a sealed container, heat it to sublimate the red phosphorus, and then cool it to deposit the red phosphorus in the porous carbon support to obtain the core material.

[0009] S2. Heat the core material in an oxidizing atmosphere to oxidize the red phosphorus on the surface of the core material;

[0010] S3. Disperse the oxidized core material and conductive carbon in a solvent, add alkali to react, and dry to obtain an in-situ coated phosphorus-carbon anode material.

[0011] This method generates an active phosphorus oxide intermediate through controlled surface oxidation, which then reacts with an alkali base in situ to form a metal phosphate coating layer. This coating layer forms a strongly chemically bonded in-situ interface with the core, ensuring interface stability and preventing peeling. This avoids the red phosphorus sublimation and structural damage problems associated with traditional high-temperature carbon coating. This in-situ coating method ingeniously introduces both a "rigid" phosphate framework with high ionic conductivity and a "flexible" conductive carbon network that ensures electron conduction, forming a strong chemically bonded interface with the phosphorus-carbon core. This structural design systematically and synergistically solves key problems in phosphorus anode materials, such as severe volume expansion, interface instability, and low intrinsic conductivity, achieving a balance between high specific capacity, long cycle life, and excellent rate performance, thus enabling the development of high-energy-density lithium / sodium-ion batteries.

[0012] Specifically, the in-situ coating method for phosphorus-carbon anode materials provided by this invention, compared with traditional non-in-situ coating techniques, directly "grows" the coating layer on the surface of the phosphorus-carbon material through a chemical reaction, achieving a tight bond between the coating layer and the core at the atomic / molecular scale, resulting in low interfacial impedance and strong adhesion. This in-situ coating method combines "vapor phase deposition for preparing phosphorus-carbon composite materials" with "liquid phase chemical reaction in-situ coating," forming a continuous and controllable process. In principle, this method is applicable to various porous carbon supports and different alkali metal hydroxides, providing a general technical route for developing a series of high-performance phosphorus-based anode materials.

[0013] In some specific embodiments, in step S1, red phosphorus is sublimated by heating and holding at a certain temperature. The heating and holding temperature is 480-700℃, for example, any temperature or a range between any two of 480℃, 500℃, 520℃, 550℃, 580℃, 600℃, 620℃, 650℃, 680℃, and 700℃. The heating rate is preferably 5-10℃ / min, and the holding time can be adjusted as needed, for example, 3-6h.

[0014] Furthermore, in step S1, the cooling and holding temperatures are between 100-260℃, for example, any temperature or a range between any two of 100℃, 120℃, 150℃, 180℃, 200℃, 220℃, and 260℃. The preferred cooling rate is 3-5℃ / min, and the holding time can be adjusted as needed, for example, 6-10 hours.

[0015] It is understandable that appropriate heating and cooling temperatures can ensure complete sublimation and uniform deposition of red phosphorus while avoiding damage to the porous carbon structure. Those skilled in the art can select or optimize these temperatures based on the specific circumstances.

[0016] In some specific embodiments, in step S2, the heating temperature is 100-200℃, for example, any temperature or a range between any two of 100℃, 120℃, 150℃, 160℃, 180℃, and 200℃. By selecting the temperature range, controllable oxidation of the surface red phosphorus can be achieved, generating an appropriate amount of active phosphorus oxide intermediates, providing a chemical anchor for subsequent in-situ reactions, while preventing the oxidation of the red phosphorus inside the core. The specific holding time can be adjusted as needed; by adjusting the oxidation time, the thickness of the coating layer can be controlled, for example, it can be 0.5-2 hours.

[0017] In some specific embodiments, in step S3, the solvent is at least one of deionized water and ethanol; and / or, the alkali is at least one of lithium hydroxide, aluminum hydroxide, zinc hydroxide, and iron hydroxide; and / or, the amount of alkali added is 1-5% of the mass of the phosphorus-carbon anode material, for example, any value or a range between any two values ​​from 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, to 5%. It should be understood that the solvent provides the reaction medium, and the metal phosphate composition can be controlled by adjusting the type and amount of alkali. Appropriate selection and ratio of alkali ensure effective formation of the coating layer while avoiding excessive reaction leading to loss of active material.

[0018] The phosphorus-carbon anode material prepared in this invention includes a core and a coating layer covering the outer surface of the core. The core is composed of a porous carbon support and a phosphorus-active substance deposited in the porous carbon support. The coating layer is formed by metal phosphate and conductive carbon, wherein the metal phosphate is chemically bonded to the core.

[0019] In this application, a coating layer is formed by metal phosphate and conductive carbon, and the metal phosphate is chemically bonded to the core. The metal phosphate provides a high-speed ion transport channel and acts as a physical barrier to suppress volume expansion, while the conductive carbon constructs a continuous electronic conductivity network. The synergistic effect of the two significantly improves the material's first coulombic efficiency, capacity retention and rate performance, while effectively reducing the electrode expansion rate.

[0020] Specifically, the outermost in-situ generated metal phosphate is a ceramic phase material with high mechanical strength and stability. It acts as a robust physical barrier, effectively preventing the electrolyte from directly eroding the internal phosphorus-carbon active material and significantly inhibiting the volume expansion and particle pulverization of red phosphorus during charge and discharge, thus protecting the integrity of the core structure. Furthermore, the metal phosphate itself possesses excellent ion transport capabilities. The outer coating layer not only does not hinder the diffusion of lithium / sodium ions but also provides a high-speed channel for ions to enter and exit the internal phosphorus-active region, contributing to improved rate performance. Simultaneously, the uniformly distributed conductive carbon in the coating layer intertwines with the metal phosphate, forming a continuous electronic conductive network within the coating layer and on the particle surface. This compensates for the poor conductivity of the metal phosphate itself, ensuring efficient electron transport between active material particles and between particles and the current collector. More importantly, a strong chemical bond is formed between the phosphate coating layer and the phosphorus-carbon core in situ, rather than a simple physical adhesion. This tight bond greatly enhances interface stability and prevents the coating layer from peeling off during long-term cycling.

[0021] Furthermore, the robust phosphate shell and the internal porous carbon framework constitute a dual volume expansion buffer system in this invention, which synergistically alleviates cycling stress. Simultaneously, the stable coating layer reduces side reactions between the active material and the electrolyte, maintaining the stability of the solid electrolyte interface film, thus enabling the material to exhibit excellent long-term cycling stability. The composite coating layer also provides optimized ion and electron conduction pathways, reducing the charge transfer impedance of the electrode, allowing the material to maintain high capacity even at high current densities. The phosphate coating layer possesses high thermal and electrochemical stability, suppressing the violent reactions of red phosphorus under abnormal conditions and reducing the risk of thermal runaway. At the same time, it effectively encapsulates red phosphorus, reducing potential dissolution and toxic substance diffusion problems in the electrolyte.

[0022] In this application, porous carbon, porous carbon materials, and porous carbon supports all refer to carbon-based materials with abundant pore structures. In some specific embodiments, the pore size of the porous carbon support is 1-2.5 nm, for example, it can be any value or a range between any two values ​​from 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm, 2.0 nm, 2.1 nm, 2.2 nm, 2.3 nm, 2.4 nm, to 2.5 nm. A suitable pore size range is beneficial for the uniform deposition of red phosphorus and the effective limitation of volume expansion, while maintaining the structural stability of the porous carbon framework. Therefore, those skilled in the art can optimize and select the pore size according to specific product performance and research needs, without particular limitations.

[0023] In some specific embodiments, the phosphorus active material accounts for 30-50% of the mass of the phosphorus-carbon anode material, for example, any percentage or a range between any two of the following: 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, and 50%. A suitable content range can balance the requirements of cycle stability and volume expansion control while ensuring high specific capacity. As a preferred example, the weight percentage of the phosphorus active material is 35%-45%.

[0024] In this application, conductive carbon refers to a carbon-based material with conductive properties. In some specific embodiments, specific examples include, but are not limited to, at least one of carbon nanotubes, conductive carbon black, and graphene. It is understood that different conductive carbon materials can be flexibly selected according to application requirements. For example, carbon nanotubes can provide a three-dimensional conductive network, conductive carbon black can fill voids, and graphene can provide a two-dimensional conductive plane, synergistically improving the electronic conductivity of the coating layer. Those skilled in the art can select appropriate conductive carbon based on specific performance requirements.

[0025] In some specific embodiments, the metal phosphate is selected from at least one of lithium phosphate, aluminum phosphate, zinc phosphate, and iron phosphate. Different metal phosphates correspond to different types of alkalis and can be flexibly selected according to the battery system. Among them, lithium phosphate has the highest ionic conductivity and is the optimal choice for use in lithium-ion batteries.

[0026] Thanks to the excellent performance of the phosphorus-carbon anode material prepared by the method in this application, the anode has high specific capacity, long cycle life and excellent rate performance, making it very suitable for high energy density lithium-ion batteries and sodium-ion batteries.

[0027] The present invention has at least the following beneficial effects:

[0028] The in-situ coating method of this invention generates an active phosphorus oxide intermediate through controlled surface oxidation, which reacts with an alkali in situ to form a metal phosphate coating layer. The coating layer forms a strong chemically bonded in-situ interface with the core, ensuring interface stability and preventing peeling. This avoids the problems of red phosphorus sublimation and structural damage caused by traditional high-temperature carbon coating. This in-situ coating method ingeniously introduces both a "rigid" phosphate framework with high ionic conductivity and a "flexible" conductive carbon network that ensures electron conduction. Through the synergistic effect of the metal phosphate and conductive carbon coating structure, the metal phosphate provides a high-speed ion transport channel and acts as a physical barrier to suppress volume expansion, while the conductive carbon constructs a continuous electron conduction network. This achieves a balance between high specific capacity, long cycle life, and excellent rate performance, making it highly suitable for high-energy-density lithium-ion batteries and sodium-ion batteries. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the preparation process of phosphorus-carbon anode material in a preferred embodiment of the present invention.

[0030] Figure 2 This is a scanning electron microscope image of the phosphorus-carbon anode material prepared in Example 1.

[0031] Figure 3 This is a scanning electron microscope image of the phosphorus-carbon anode material prepared in Comparative Example 2. Detailed Implementation

[0032] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. Furthermore, unless otherwise specified, methods not specifically describing conditions or steps are conventional methods, and the reagents and materials used are commercially available.

[0034] Example 1: In-situ coating of phosphorus-carbon anode material

[0035] The specific preparation method is as follows:

[0036] S1. Take 10g of red phosphorus and 12g of porous carbon material, mix them evenly, and add them into a sealable container. Use a molecular pump to reduce the gas pressure in the container to 50Pa and then seal the container. Use a muffle furnace to heat the container to 550℃ at a heating rate of 5℃ / min and hold it for 6 hours. Then cool it down to 250℃ and hold it for 8 hours at a cooling rate of 5℃ / min. After the container cools down to room temperature, open the container to obtain the core material.

[0037] S2. Take 20g of core material into a quartz boat and oxidize it in an air atmosphere using a tube furnace. The oxidation temperature is 100℃ and the oxidation time is 1h.

[0038] S3. Add 10g of oxidized core material, 1.5g of carbon nanotubes (CNTs) with a mass concentration of 0.4% and 0.01g of conductive carbon black (SP) to 60mL of deionized water, heat in a water bath at 75℃, stir at 300r / min for 20min, then take 15mL of lithium hydroxide solution with a concentration of 0.1mol / L and add it dropwise to the mixed solution. Continue to rotary evaporate the solution. After the water evaporates, transfer it to a vacuum drying oven and dry at 80℃ for 3h to obtain the in-situ coated phosphorus-carbon anode material.

[0039] Example 2: In-situ coating of phosphorus-carbon anode material

[0040] The specific preparation method is as follows:

[0041] S1. Take 10g of red phosphorus and 12g of porous carbon material, mix them evenly, and add them into a sealable container. Use a molecular pump to reduce the gas pressure in the container to 50Pa and then seal the container. Use a muffle furnace to heat the container to 600℃ at a heating rate of 5℃ / min and hold it for 6h. Then cool it down to 200℃ and hold it for 8h at a cooling rate of 5℃ / min. After the container cools down to room temperature, open the container to obtain the core material.

[0042] S2. Take 20g of core material into a quartz boat and oxidize it in an air atmosphere using a tube furnace. The oxidation temperature is 150℃ and the oxidation time is 0.5h.

[0043] S3. Add 10g of oxidized core material and 2.5g of 0.4% carbon nanotubes (CNTs) to 60mL of deionized water, heat in a 70℃ water bath, stir at 300r / min for 20min, then slowly add 0.2g of zinc hydroxide to the mixed solution, continuously rotary evaporate the solution, and after the water evaporates, transfer it to a vacuum drying oven at 80℃ for 3h to obtain the in-situ coated phosphorus-carbon anode material.

[0044] Example 3: In-situ coating of phosphorus-carbon anode material

[0045] The specific preparation method is as follows:

[0046] S1. Take 10g of red phosphorus and 12g of porous carbon material, mix them evenly and add them to a sealable container. Use a molecular pump to reduce the gas pressure in the container to 50Pa and then seal the container. Use a muffle furnace to heat the container to 700℃ at a heating rate of 8℃ / min and hold for 4 hours. Then cool it down to 150℃ and hold for 8 hours at a cooling rate of 5℃ / min. After the container cools down to room temperature, open the container to obtain the core material.

[0047] S2. Take 20g of core material into a quartz boat and oxidize it in an air atmosphere using a tube furnace. The oxidation temperature is 150℃ and the oxidation time is 0.5h.

[0048] S3. Add 10g of the oxidized core material and 0.05g of conductive carbon black (SP) to 60mL of deionized water, heat in a 75℃ water bath, stir at 300r / min for 20min to obtain 0.1g of aluminum hydroxide, slowly add it to the mixed solution, continuously rotary evaporate the solution, and after the water evaporates, transfer it to a vacuum drying oven at 80℃ for 3h to obtain the in-situ coated phosphorus-carbon anode material.

[0049] Example 4: In-situ coating of phosphorus-carbon anode material

[0050] The specific preparation method is as follows:

[0051] S1. Take 10g of red phosphorus and 12g of porous carbon material, mix them evenly and add them to a sealable container. Use a molecular pump to reduce the gas pressure in the container to 50Pa and then seal the container. Use a muffle furnace to heat the container to 650℃ at a heating rate of 5℃ / min and hold it for 4 hours. Then cool it down to 120℃ and hold it for 8 hours at a cooling rate of 5℃ / min. After the container cools down to room temperature, open the container to obtain the core material.

[0052] S2. Take 20g of core material into a quartz boat and oxidize it in an air atmosphere using a tube furnace. The oxidation temperature is 120℃ and the oxidation time is 0.5h.

[0053] S3. Add 10g of oxidized core material, 1.5g of 0.4% carbon nanotubes (CNTs) and 0.02g of graphene (GN) to 60mL of deionized water, heat in a 75℃ water bath, stir at 300r / min for 20min, then slowly add 0.3g of ferric hydroxide to the mixed solution, continuously rotary evaporate the solution, and after the water evaporates, transfer it to a vacuum drying oven at 80℃ for 3h to obtain the in-situ coated phosphorus-carbon anode material.

[0054] Comparative Example 1

[0055] This comparative example presents a phosphorus-carbon anode material, the preparation method of which includes the following steps:

[0056] S1. Take 10g of red phosphorus and 12g of porous carbon material, mix them evenly, and add them into a sealable container. Use a molecular pump to reduce the gas pressure in the container to 50Pa and then seal the container. Use a muffle furnace to heat the container to 550℃ at a heating rate of 5℃ / min and hold it for 6 hours. Then cool it down to 250℃ and hold it for 8 hours at a cooling rate of 5℃ / min. After the container cools down to room temperature, open the container to obtain the core material.

[0057] S2. Take 20g of core material into a quartz boat and oxidize it in an air atmosphere using a tube furnace. The oxidation temperature is 100℃ and the oxidation time is 1h.

[0058] S3. Add 10g of oxidized core material, 1.5g of 0.4% carbon nanotubes (CNTs), and 0.01g of conductive carbon black (SP) to 60mL of deionized water. Heat in a water bath at 75℃ and stir at 300r / min for 20min. Then, continuously rotary evaporate the solution until the water evaporates. Transfer the solution to a vacuum drying oven at 80℃ and dry for 3h to obtain the in-situ coated phosphorus-carbon anode material.

[0059] Comparative Example 2

[0060] This comparative example presents a phosphorus-carbon anode material, the preparation method of which includes the following steps:

[0061] S1. Take 10g of red phosphorus and 12g of porous carbon material, mix them evenly and add them to a sealable container. Use a molecular pump to reduce the gas pressure in the container to 50Pa and then seal the container. Use a muffle furnace to heat the container to 550℃ at a heating rate of 5℃ / min and hold it for 6 hours. Then cool it down to 250℃ and hold it for 8 hours at a cooling rate of 5℃ / min. After the container cools down to room temperature, open the container to obtain the phosphorus-carbon composite material.

[0062] Material characterization and performance testing

[0063] (1) The phosphorus-carbon anode materials prepared in Example 1 and Comparative Example 2 were characterized using a scanning electron microscope, and the results are as follows: Figure 2 and Figure 3 As shown. From Figure 2 , Figure 3 It can be seen that, Figure 2 , Figure 3 The material particles in the sample are relatively uniform in size and evenly dispersed, indicating that the phosphorus-carbon anode material prepared by vapor deposition has good uniformity; compared to Figure 3 , Figure 2 The surface of the particles has a large number of filaments, indicating that a uniform carbon nanotube and lithium phosphate coating layer has been formed.

[0064] (2) The phosphorus-carbon anode materials obtained in Examples 1-4 and Comparative Examples 1-2 were respectively used to prepare lithium batteries:

[0065] The negative electrode material, binder (PAA), and conductive agent (SP) were mixed in a mass ratio of 8:1:1 to obtain a slurry. The slurry was coated on the surface of copper foil and then vacuum dried at 100°C for 12 hours. Finally, a negative electrode sheet with a diameter of 12 mm was obtained using a stamping machine. Lithium metal was used as the counter electrode. Celgard 2400 was used as the separator. 40 μL of 1 mol / L LiPF6 solution (the solvent was a mixture of ethylene carbonate EC and dimethyl carbonate DMC in a volume ratio of 1:1, containing 10% FEC additive) was used as the electrolyte. The 2032 coin cell was assembled in a glove box under a high-purity argon atmosphere.

[0066] The electrochemical performance of each coin cell was tested: under normal temperature conditions, constant current charge and discharge at 0.1C, with the charge and discharge voltage limited to 0.005-1.5V. The results are shown in Table 1 below.

[0067] Table 1 Electrochemical performance

[0068]

[0069] The results in Table 1 show that:

[0070] In Example 1, the phosphorus-carbon anode material achieved a first-pass coulombic efficiency of up to 90.5% due to the cross-linked network coating of lithium phosphate and carbon nanotubes; while in Comparative Example 1, the material did not use lithium hydroxide in-situ reaction, resulting in a first-pass efficiency of only 84.7%.

[0071] Compared to the uncoated phosphorus-carbon anode material of Comparative Example 2, the capacity of the phosphorus-carbon anode material in Example 1 decreased from 1276.3 mAh / g to 1136.4 mAh / g. This was due to the conversion of some of the active material, red phosphorus, into a lithium phosphate coating. However, the capacity retention and initial coulombic efficiency were improved due to the presence of the coating. Furthermore, the initial electrode expansion was reduced in the in-situ coated phosphorus-carbon anode materials, indicating that the lithium phosphate and carbon nanotube coatings also played a role in stabilizing the material structure.

[0072] In summary, this in-situ coated phosphorus-carbon anode material improves its overall electrochemical performance to a certain extent.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for in-situ coating preparation of phosphorus-carbon anode materials, characterized in that, Includes the following steps: S1. After mixing the porous carbon support with red phosphorus, place it in a sealed container, heat it to sublimate the red phosphorus, and then cool it to deposit the red phosphorus in the porous carbon support to obtain the core material. S2. Heat the core material in an oxidizing atmosphere to oxidize the red phosphorus on the surface of the core material; S3. Disperse the oxidized core material and conductive carbon in a solvent, add alkali to react, and dry to obtain an in-situ coated phosphorus-carbon anode material.

2. The method according to claim 1, characterized in that, In step S1, the heating temperature is 480-700℃; and / or, the cooling temperature is 100-260℃.

3. The method according to claim 1, characterized in that, In step S2, the heating temperature is 100-200℃.

4. The method according to claim 1, characterized in that, In step S3, the solvent is at least one of deionized water and ethanol.

5. The method according to claim 1, characterized in that, In step S3, the alkali is at least one of lithium hydroxide, aluminum hydroxide, zinc hydroxide, and iron hydroxide.

6. The method according to claim 1, characterized in that, In step S3, the amount of alkali added is 1-5% of the mass of the phosphorus-carbon anode material.

7. The method according to claim 1, characterized in that, The phosphorus-carbon anode material includes: The core is composed of a porous carbon support and phosphorus-active material deposited within the porous carbon support; And a coating layer covering the outer surface of the core, the coating layer being formed by metal phosphate and conductive carbon, wherein the metal phosphate is chemically bonded to the core.

8. The method according to claim 7, characterized in that, The porous carbon support has a pore size of 1-2.5 nm; And / or, the phosphorus active material accounts for 30-50% of the mass of the phosphorus-carbon anode material.

9. The method according to claim 7, characterized in that, The conductive carbon is selected from at least one of carbon nanotubes, conductive carbon black, and graphene.

10. The method according to claim 7, characterized in that, The metal phosphate is selected from at least one of lithium phosphate, aluminum phosphate, zinc phosphate, and iron phosphate.

Images