Preparation method and application of phosphorus-doped porous carbon

Abstract

This invention belongs to the field of carbon materials and discloses a method for preparing phosphorus-doped porous carbon: Biomass pyrolysis carbon, PCl3, and water are mixed; the mixture is placed in an acid-resistant rotary reactor, an inert gas is introduced, and then a staged heating process is performed. Finally, the temperature is raised to allow the generated chlorides to sublimate and be discharged with the inert gas. The furnace is then cooled to obtain phosphorus-doped high-purity porous carbon. The staged heating process consists of three stages: first, the temperature is raised to 40-80℃ for a first-stage holding; then, the temperature is raised to 180-320℃ for a second-stage holding; and finally, the temperature is raised to 500-600℃ for a third-stage holding. This method for preparing phosphorus-doped high-purity porous carbon utilizes a specific reaction between PCl3 and water to form phosphorous acid and hydrochloric acid. The disproportionation reaction of phosphorous acid itself generates phosphoric acid and phosphine. Finally, the decomposition of phosphine achieves the preparation, phosphorus doping, and purification of porous carbon.

Description

Technical Field

[0001] This invention belongs to the field of carbon materials technology, and particularly relates to a method for preparing phosphorus-doped porous carbon and its application. Background Technology

[0002] Porous carbon materials are carbon materials with high specific surface area and abundant pore structure, possessing excellent electrical conductivity, physical and chemical stability. Their pore sizes can be classified as micropores (<2nm), mesopores (2-50nm), and macropores (>50nm). Due to their high electrical conductivity, good stability, and excellent electrochemical performance, these materials have wide applications in energy storage, catalysis, adsorption, and other fields.

[0003] Lithium-ion batteries, characterized by their high energy density, have attracted widespread attention in an increasingly electrified society. Carbon materials are commonly used as anode materials in lithium-ion batteries. However, the theoretical capacity of commercially available graphite is nearing its theoretical limit, making further performance improvements difficult. Therefore, finding next-generation electrode materials for lithium-ion batteries is crucial.

[0004] Porous carbon is an excellent precursor material for preparing high-performance silicon-carbon anode materials for lithium-ion batteries. Its multidimensional and complex porous structure provides effective diffusion channels and a short lithium-ion diffusion distance; vacancies and heteroatom doping defects can serve as lithium storage sites; and it exhibits low mechanical stress during lithium insertion / extraction, resulting in good cycle stability. Therefore, the preparation process of porous carbon is crucial for the development of silicon-carbon anode materials, making it an excellent precursor material for lithium-ion batteries.

[0005] Patent document CN118515257A discloses a method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon and its application. This invention uses chitosan as a carbon source and trithiocyanate and potassium hypophosphite as dopants to dope the porous carbon with nitrogen, phosphorus, and sulfur, thereby increasing the specific surface area of ​​the porous carbon to 1318 m². 2 / g. However, the porous carbon prepared by this method cannot achieve uniform doping of heteroatoms, and the specific surface area fails to reach 2000m². 2 For samples with a density of 1 g or higher, the storage capacity for lithium ions is relatively low and needs to be further improved.

[0006] A patent document with publication number CN117699752A discloses a method for preparing a nano-red phosphorus-porous carbon composite material. It uses Chlorella as a carbon source, calcium, potassium, and sodium salts as pore-forming agents, and red phosphorus as a dopant. The nano-red phosphorus-porous carbon composite material is prepared by liquid-phase mixing and re-carbonization. This material can achieve an initial discharge specific capacity of 1673 mAh / g in coin cells. However, the material's stability is relatively poor, and the phosphorus element is mainly distributed on the material surface, making it difficult to penetrate into the porous carbon material, thus failing to achieve a significant capacity improvement.

[0007] Patent document CN117877893A discloses a method for preparing nitrogen, phosphorus, and oxygen co-doped porous carbon materials in situ. This invention uses coal and petroleum-based heavy organic matter as the carbon source, phosphothreonine and guanidinium phosphate urea as dopants, and an alkali as a pore-forming agent. The method employs a solution mixing and heating process to prepare the nitrogen, phosphorus, and oxygen co-doped porous carbon materials. However, the porous carbon materials prepared by this invention exhibit relatively low capacity in batteries, and their specific surface area does not reach 2000 m². 2 / g or more.

[0008] Patent document CN114388799A discloses a CoFe2O4 / phosphorus-containing porous carbon lithium-ion battery anode material and its preparation method. This method uses triphosphine and acrylonitrile as raw materials, and prepares phosphorus-containing porous carbon by adding tetrahydrofuran and dimethyl sulfoxide in a reactor, heating at low temperature, and then carbonizing at high temperature. The phosphorus-containing porous carbon material prepared by this invention has a relatively high specific surface area, but its charge specific capacity at a current density of 50 mA / g is only 826.3 mAh / g, which is relatively low in lithium battery systems. This is mainly because the method involves impregnating a small amount of phosphorus onto the surface of the material, without achieving significant phosphorus doping inside.

[0009] Patent document CN117049512A discloses a method for preparing phosphoric acid crosslinked starch porous carbon material. This method uses starch as the raw material and phosphoric acid as the activator, and prepares starch-based porous carbon material by promoting starch crosslinking through hydrothermal treatment at 200℃. The porous carbon prepared by this method has a specific surface area of ​​only 1866 m². 2 The value of / g is relatively low in phosphorus-doped porous carbon systems. This may be because simply using phosphoric acid solution to activate biomass can only induce pores on the surface of the material, and cannot treat the pores inside the material.

[0010] The article "Preparation and Characterization of Bamboo Chip Activated Carbon by Phosphoric Acid Method" by Zhou Jinlong et al. discloses a method for preparing bamboo chip activated carbon using the phosphoric acid method. However, this method involves spraying an aqueous phosphoric acid solution onto the surface of bamboo chips while simultaneously stirring the material to ensure uniform spraying. The bamboo chip-based activated carbon is then prepared using a multi-stage calcination process. However, the specific surface area of ​​the bamboo chip-based porous carbon prepared by this method is only 1651 m². 2 / g is also relatively low in phosphoric acid activated porous carbon systems.

[0011] In summary, the porous carbon currently produced in the industry mainly suffers from problems such as excessively small specific surface area, complex preparation process, and relatively low specific capacity. Furthermore, current porous carbon doping technology can only achieve surface doping and has failed to achieve doping of the internal structure of porous carbon. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a method for preparing phosphorus-doped porous carbon and its application.

[0013] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0014] A method for preparing phosphorus-doped porous carbon includes the following steps:

[0015] (1) Mix biomass pyrolysis carbon, PCl3, and water;

[0016] (2) The mixture after step (1) is placed in an acid-resistant rotary reactor, an inert gas is introduced, and then a segmented heating treatment is performed. Finally, the temperature is raised so that the generated chlorides sublimate and are discharged with the inert gas. The furnace body is cooled to obtain phosphorus-doped high-purity porous carbon. The segmented heating treatment is a three-stage heating treatment: first, the temperature is raised to 40-80℃ for the first stage of heat preservation so that PCl3 reacts fully with water to form phosphorous acid and hydrochloric acid. Then, the temperature is raised to 180-320℃ for the second stage of heat preservation so that phosphorous acid begins to disproportionate to produce PH3, and hydrochloric acid is vaporized to form HCl, which reacts with the impurities in the pyrolytic carbon to form chlorides. Finally, the temperature is raised to 500-600℃ for the third stage of heat preservation so that PH3 decomposes into P and H2. The generated H2 reacts with oxygen atoms in the pyrolytic carbon to form H2O, and the P gas gradually penetrates into the interior of the pyrolytic carbon.

[0017] In the above preparation method, preferably, in step (2), the heat preservation time of the first stage is 0.5-4h.

[0018] In the above preparation method, preferably, in step (2), the second stage heat preservation time is 0.5-3h.

[0019] In the above preparation method, preferably, in step (2), the heat preservation time of the third stage is 0.5-2h.

[0020] In the above preparation method, preferably, in step (1), the mass ratio of the bio-pyrolytic carbon to PCl3 is 6:1-1:2. If the amount of PCl3 is too large, the carbon material will be over-corroded and lithium ion insertion cannot be effectively achieved. If the amount of PCl3 is too small, the etching effect is small and it is difficult to effectively prepare high-capacity phosphorus-doped porous carbon.

[0021] In the above preparation method, preferably, in step (1), the volume ratio of PCl3 to ultrapure water is 1:3. Controlling the ratio of PCl3 to water can promote the full reaction of PCl3 and water to form phosphorous acid and hydrochloric acid, reduce the water content inside the furnace at high temperatures, and thus avoid significant damage to the furnace.

[0022] In the above preparation method, preferably, in step (1), the biomass pyrolysis carbon includes one of coconut shell pyrolysis carbon, bamboo pyrolysis carbon, and walnut shell pyrolysis carbon, with a specific surface area of ​​350-450 m². 2 / g, with an oxygen content of 1.2-1.7%.

[0023] In the above preparation method, preferably, in step (2), the inert gas is one or more of nitrogen, helium, argon, and neon; the inert gas flow rate is 0.1 L / min to 0.5 L / min. The inert gas flow rate needs to be controlled within this range; otherwise, if the flow rate is lower than this, on the one hand, the exhaust process will result in incomplete air discharge, causing the material to come into contact with oxygen during the sintering process and be oxidized; on the other hand, if the gas flow rate is too low, the generated chlorides will not be discharged at the sublimation temperature, thus affecting the purity of the material; if the gas flow rate is higher than this, the P generated during the sintering process will be quickly discharged, making it impossible to achieve efficient doping.

[0024] In the preferred preparation method described above, in step (2), after the segmented heating treatment, the temperature is further increased to allow the generated chloride to sublimate and be discharged with the inert gas. Then the furnace body is cooled. During the cooling process, P changes from a gaseous state to a solid state and is distributed in various parts of the pyrolytic carbon. Finally, phosphorus-doped high-purity porous carbon is taken out through the inclined furnace tube.

[0025] In the above preparation method, preferably, after segmented heating treatment, the temperature is further increased to 700-750℃ and held for 0.5-2 hours.

[0026] In the above preparation method, preferably, the main reaction equations involved in each step are as follows:

[0027] PCl3 + 3H2O = H3PO3 + 3HCl;

[0028] 4H3PO3 = 3H3PO4 + PH3;

[0029] 2HCl + FeO = FeCl2 + H2O;

[0030] 2PH3 = 2P + 3H2;

[0031] H2 + O2 = H2O.

[0032] Based on a general inventive concept, the present invention also provides an application of phosphorus-doped porous carbon prepared by the above-described preparation method in lithium-ion battery anode materials.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) The method for preparing phosphorus-doped high-purity porous carbon of the present invention uses a special reaction of PCl3 with water to form phosphorous acid and hydrochloric acid, utilizes the disproportionation reaction of phosphorous acid to generate phosphoric acid and phosphine, and finally utilizes the decomposition of phosphine to achieve the preparation, phosphorus doping and purification of porous carbon.

[0035] (2) Phosphoric acid, generated by the disproportionation of phosphorous acid, activates pyrolytic carbon at higher temperatures. During the activation stage, phosphoric acid etches the carbon structure, forming more micropores <2nm, thus providing a larger specific surface area and effectively transforming pyrolytic carbon into porous carbon. In different heating stages, various phosphorus-containing substances etched the pyrolytic carbon. Multi-stage etching fully realized the formation of pores, which is more conducive to the preparation of porous carbon with a higher specific surface area. Furthermore, the subsequent purification with HCl and H2 further promoted the formation of pores inside the carbon.

[0036] (3) The generation of PH3 during the preparation process of the present invention provides a good doping source for P doping. PH3 decomposes into P and H2 at 500℃. At this temperature, P exists in the form of gas. Under the promotion of thermal motion, gaseous P atoms will enter the interior of porous carbon. The P atoms that enter the porous carbon layers lose sufficient momentum and their atomic radius is larger than that of carbon. They will move continuously between the carbon layers and cannot escape to the outside of carbon. Finally, as the furnace cools down, gaseous P gradually solidifies into solid P atoms, and finally the uniform doping of P is achieved.

[0037] (4) The HCl generated during the preparation process of the present invention reacts with impurities (mainly ferrous oxide) in the porous carbon at a high temperature to form ferrous chloride. At the subsequent high temperature, the ferrous chloride begins to sublimate and is eventually discharged from the furnace with the introduction of inert gas, thereby achieving the removal of impurities inside the porous carbon. The H2 generated by the decomposition of PH3 reacts with oxygen atoms in the carbon material at high temperature to form H2O. The formed H2O is also discharged from the furnace with the introduction of inert gas, further increasing the fixed carbon content of the porous carbon and achieving secondary purification. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 These are SEM images of the phosphorus-doped porous carbon prepared in Example 1 of this invention;

[0040] Figure 2 This is a TEM image of the phosphorus-doped porous carbon prepared in Example 1 of this invention. Detailed Implementation

[0041] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0042] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0043] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0044] The biomass pyrolysis carbon used in the following examples and comparative examples is coconut shell pyrolysis carbon, with a specific surface area of ​​425.3 m². 2 / g, with an oxygen content of 1.4%.

[0045] Example 1:

[0046] A method for preparing phosphorus-doped porous carbon according to the present invention includes the following steps:

[0047] 600g of biomass pyrolysis carbon, 150mL of PCl3, and 450mL of ultrapure water were mixed thoroughly and placed in an acid-resistant rotary reactor. Argon gas was introduced into the furnace at a rate of 0.3L / min. After 6 hours of gas introduction, the temperature was raised to 60℃ and held for 1 hour. Then, the temperature was raised to 230℃ and held for 2 hours. Next, the temperature was raised to 540℃ and held for 1.5 hours. After completing the three-stage heating process, the furnace temperature was raised to 730℃ and held for 1 hour. The generated chlorides sublimated and were discharged with the inert gas. After the holding period was completed, the furnace was cooled down. After cooling, the phosphorus-doped porous carbon was removed by tilting the furnace.

[0048] SEM images of the doped porous carbon prepared in this embodiment. Figure 1 TEM image is Figure 2 . Figure 1 The presence of obvious pores under SEM indicates that this embodiment successfully prepared a porous carbon material with abundant pores. Figure 2 Under TEM, the material shows uniformly distributed black particles, which are P elements incorporated into the porous carbon, indicating that the P elements are successfully distributed inside the porous carbon.

[0049] The specific surface area of ​​the phosphorus-doped porous carbon prepared in this embodiment was determined to be 2356.52 m² using static volumetric methods. 2 / g, the average pore size of the material is 1.2nm; the P content was tested by spectrophotometer and found to be 5.7%, the oxygen content was tested by oxygen analyzer and found to be 0.2%, and the content of other impurities was 0.06%.

[0050] The phosphorus-doped porous carbon, conductive agent, and PVDF prepared in this embodiment were mixed and homogenized in a ratio of 8:1:1 and coated to form an electrode. The electrode was then assembled into a lithium-ion coin cell using a coin cell assembly method. The performance was tested using a current density of 20 mA / g, and the initial discharge specific capacity was 1786 mAh / g.

[0051] Example 2:

[0052] A method for preparing phosphorus-doped porous carbon according to the present invention includes the following steps:

[0053] 600g of biomass pyrolysis carbon, 100mL of PCl3, and 300mL of ultrapure water were mixed evenly and placed in an acid-resistant rotary reactor. Argon gas was introduced into the furnace at a rate of 0.3L / min for 6 hours. After 6 hours of gas introduction, the temperature was raised to 60℃ and held for 1 hour. After that, the temperature was raised to 230℃ and held for 2 hours. After the second stage of heating, the temperature was raised to 540℃ and held for 1.5 hours. After the third stage of heating, the temperature was raised to 730℃ and held for 1 hour. The generated chloride sublimated and was discharged with the inert gas. After the holding period was completed, the furnace was cooled down. After cooling, the phosphorus-doped high-purity porous carbon was removed by tilting the furnace.

[0054] The specific surface area of ​​the phosphorus-doped porous carbon prepared in this embodiment was determined to be 2031.13 m² using static volumetric methods. 2 / g, the average pore size of the material is 1.6nm, the P content is 3.9% when tested by spectrophotometer, the oxygen content is 0.5% when tested by oxygen analyzer, and the content of other impurities is 0.111%.

[0055] The phosphorus-doped porous carbon of this embodiment was used to make an electrode according to the method of Example 1, and then a lithium-ion coin cell was prepared by coin cell assembly method. The performance was tested with a current density of 20mA / g, and the initial discharge specific capacity was 1618mAh / g.

[0056] Example 3:

[0057] A method for preparing phosphorus-doped porous carbon according to the present invention includes the following steps:

[0058] 600g of biomass pyrolysis carbon, 150ml of PCl3, and 450mL of ultrapure water were mixed evenly and placed in an acid-resistant rotary reactor. Argon gas was introduced into the furnace at a rate of 0.5L / min. After 6 hours of gas introduction, the temperature was raised to 60℃ and held for 1 hour. After that, the temperature was raised to 230℃ and held for 2 hours. After the second stage of heating, the temperature was raised to 540℃ and held for 1.5 hours. Finally, the temperature was raised to 730℃ and held for 1 hour. The generated chlorides sublimated and were discharged with the inert gas. After the holding period was completed, the furnace was cooled down. After cooling, the phosphorus-doped high-purity porous carbon was removed by tilting the furnace.

[0059] The specific surface area of ​​the phosphorus-doped porous carbon prepared in this embodiment was determined to be 2276.96 m² using static volumetric methods. 2 / g, the average pore size of the material is 1.3nm, the P content is 5.2% when tested by spectrophotometer, the oxygen content is 0.3% when tested by oxygen analyzer, and the content of other impurities is 0.09%.

[0060] The phosphorus-doped porous carbon of this embodiment was used to make an electrode according to the method of Example 1, and then a lithium-ion coin cell was prepared by coin cell assembly method. The performance was tested with a current density of 20mA / g, and the initial discharge specific capacity was 1705mAh / g.

[0061] Comparative Example 1:

[0062] The preparation method of phosphorus-doped porous carbon in this comparative example includes the following steps:

[0063] Mix 600g of biomass pyrolysis carbon with 150ml of H3PO4 and place the mixture in an acid-resistant rotary reactor. Introduce argon gas into the furnace at a rate of 0.3L / min for 6 hours. Then, raise the temperature to 60℃ and hold for 1 hour. After that, raise the temperature to 230℃ and hold for 2 hours. After the second stage of heating, raise the temperature to 540℃ and hold for 1.5 hours. After the third stage of heating, raise the furnace temperature to 730℃ and hold for 1 hour. After holding for 1 hour, begin cooling the furnace. After cooling, remove the phosphorus-doped high-purity porous carbon by tilting the furnace.

[0064] The specific surface area of ​​the porous carbon in this comparative example, determined using static volumetric methods, was 1267.52 m². 2 / g, the average pore size of the material is 2.7nm, the P content is 0.8% when tested by spectrophotometer, the oxygen content is 1.3% when tested by oxygen analyzer, and the content of other impurities is 0.27%.

[0065] The phosphorus-doped porous carbon of this comparative example was used to make an electrode according to the method of Example 1, and then a lithium-ion coin cell was prepared by the coin cell assembly method. The performance was tested using a current density of 20 mA / g, and the initial discharge specific capacity was 964 mAh / g.

[0066] Comparative Example 2:

[0067] The preparation method of phosphorus-doped porous carbon in this comparative example includes the following steps:

[0068] 600g of biomass pyrolysis carbon, 150mL of H3PO4, and 450mL of HCl were mixed thoroughly and placed in an acid-resistant rotary reactor. Argon gas was introduced into the furnace at a rate of 0.3L / min. After 6 hours of gas introduction, the temperature was raised to 60℃ and held for 1 hour. After that, the temperature was raised to 230℃ and held for 2 hours. After the second stage of heating, the temperature was raised to 540℃ and held for 1.5 hours. After the third stage of heating, the temperature was raised to 730℃ and held for 1 hour. After the holding period, the furnace was cooled down. After cooling, the phosphorus-doped high-purity porous carbon was removed by tilting the furnace.

[0069] The specific surface area of ​​the porous carbon in this comparative example, determined by static volumetric method, was 1336.52 m². 2 / g, the average pore size of the material is 2.3nm, the P content is 0.9% when tested by spectrophotometer, the oxygen content is 1.2% when tested by oxygen analyzer, and the content of other impurities is 0.21%.

[0070] The phosphorus-doped porous carbon of this comparative example was used to make an electrode according to the method of Example 1, and then a lithium-ion coin cell was prepared by coin cell assembly method. The performance was tested with a current density of 20mA / g, and the initial discharge specific capacity was 1031mAh / g.

[0071] Comparative Example 3:

[0072] This comparative example does not employ a multi-stage heating method to prepare phosphorus-doped porous carbon, but specifically includes the following steps:

[0073] 600g of biomass pyrolysis carbon, 150mL of PCl3, and 450mL of ultrapure water were mixed thoroughly and placed in an acid-resistant rotary reactor. Argon gas was introduced into the furnace at a rate of 0.3L / min. After 6 hours of gas introduction, the temperature was raised to 730℃ and held for 5.5 hours. The generated chlorides sublimated and were discharged with the inert gas. After the holding period was completed, the furnace was cooled down. After cooling, the phosphorus-doped porous carbon was removed by tilting the furnace.

[0074] The specific surface area of ​​the phosphorus-doped porous carbon in this comparative example, determined by static volumetric method, was 1463.52 m². 2 / g, the average pore size of the material is 2.1nμm, the P content is 1.8% when tested by spectrophotometer, the oxygen content is 0.8% when tested by oxygen analyzer, and the content of other impurities is 0.15%.

[0075] The phosphorus-doped porous carbon of this comparative example was used to make an electrode according to the method of Example 1, and then a lithium-ion coin cell was prepared by coin cell assembly method. The performance was tested with a current density of 20mA / g, and the initial discharge specific capacity was 1216mAh / g.

[0076] Table 1. Physicochemical properties of porous carbon prepared in each example and comparative example.

[0077]

[0078] The comparison of the above examples and comparative examples shows that using PCl3 as a pore-forming dopant can effectively increase the number of micropores with a pore size of <2nm, thereby increasing the specific surface area and specific capacity of porous carbon. Compared with the mixture of H3PO3 and HCl, PCl3 has a smaller molecular volume and can more easily enter the internal structure of the material. The H3PO3 and HCl generated by the reaction of PCl3 into the material structure and water can directly act from the inside of the material, achieving better purification effect while creating pores inside the material. In contrast, the mixture of H3PO3 and HCl is relatively difficult to enter the inside of the material and mainly acts on the surface of the material, resulting in poorer effect.

Claims

1. A method for preparing phosphorus-doped porous carbon, characterized in that, Includes the following steps: (1) Mix biomass pyrolysis carbon, PCl3, and water; (2) The mixture after step (1) is placed in an acid-resistant rotary reactor, an inert gas is introduced, and then a segmented heating treatment is performed. Finally, the temperature is raised so that the generated chloride sublimates and is discharged with the inert gas. The furnace body is cooled to obtain phosphorus-doped porous carbon. The segmented heating treatment is a three-stage heating treatment: first, the temperature is raised to 40-80℃ for the first stage of heat preservation, then the temperature is raised to 180-320℃ for the second stage of heat preservation, and finally the temperature is raised to 500-600℃ for the third stage of heat preservation.

2. The preparation method according to claim 1, characterized in that, In step (2), the insulation time of the first segment is 0.5-4h.

3. The preparation method according to claim 1, characterized in that, In step (2), the second heat preservation time is 0.5-3h.

4. The preparation method according to claim 1, characterized in that, In step (2), the insulation time of the third section is 0.5-2h.

5. The preparation method according to any one of claims 1-4, characterized in that, In step (1), the solid-liquid ratio of the bio-pyrolytic carbon to PCl3 is 6:1-1:2, and the ratio unit is g / mL.

6. The preparation method according to any one of claims 1-4, characterized in that, In step (1), the volume ratio of PCl3 to water is 1:

3.

7. The preparation method according to any one of claims 1-4, characterized in that, In step (2), the inert gas is one or more of nitrogen, helium, argon, and neon; the flow rate of the inert gas is 0.1L / min-0.5L / min.

8. The preparation method according to any one of claims 1-4, characterized in that, After segmented heating treatment, the temperature is further increased to 700-750℃ and held for 0.5-2 hours to allow the generated chloride to sublimate and be discharged with inert gas.

9. The application of phosphorus-doped porous carbon prepared by any one of claims 1-8 in lithium-ion battery anode materials.

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