A high-capacity resin-based hard carbon anode material containing phosphorus and nitrogen dual doping and a preparation method thereof

Abstract

The present invention discloses a phosphorus and nitrogen co-doped high-capacity resin-based hard carbon anode material and its preparation method. This material is prepared by reacting the independently innovatively synthesized nitrogen-containing organic compound 3-aminophenoxyphthalonitrile with the phosphorus-containing organic compound 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to obtain a resin-based precursor material with phosphorus and nitrogen co-doping. The precursor material is then subjected to pyrolytic cross-linking and carbonization treatments to obtain the phosphorus and nitrogen co-doped resin-based hard carbon anode material. Through phosphorus and nitrogen co-doping, the present invention effectively improves the specific capacity, cycle stability, and rate performance of the hard carbon material, solving the problem of the limited theoretical capacity of the graphite anode in lithium-ion batteries; the prepared hard carbon anode material has high lithium-ion storage capacity and excellent electrochemical performance, and is particularly suitable for high-performance lithium-ion batteries; the preparation method of this material is simple and feasible, and has good industrialization prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly to a high-capacity resin-based hard carbon anode material containing phosphorus and nitrogen dual doping and a preparation method thereof. Background Art

[0002] Since the 1980s, the research and development of lithium-ion batteries (LIBs) and their key materials have become a hot topic in the field of chemical energy storage. Compared with traditional secondary batteries, LIBs have the advantages of high energy density, long cycle life, light weight, and good safety, so they are widely used in portable electronic devices, electric vehicles, and renewable energy storage systems. Anode materials play an important role in LIBs, and their performance directly affects the capacity, energy density, and safety of the batteries. Currently, graphite is widely used as the anode material for commercial LIBs due to its good stability, but its theoretical specific capacity is only 372 mAh / g, which is difficult to meet the demand for high energy density. Hard carbon, as an amorphous carbon material with high specific capacity and good cycle performance, has gradually become the research focus of the new generation of LIB anode materials.

[0003] Hard carbon is usually composed of a graphite-like microcrystalline structure and open angular microcrystals. This unique structure provides more lithium storage sites and can effectively alleviate the structural damage caused by volume expansion. However, the improvement of hard carbon performance is limited by the preparation method and precursor characteristics. To further optimize the electrochemical performance of hard carbon, researchers have begun to explore enhancing its conductivity and increasing defect sites through heteroatom doping to improve its lithium storage capacity. In particular, the co-doping research of phosphorus and nitrogen has shown significant effects in improving the capacity and cycle life of hard carbon.

[0004] The present invention synthesizes a special resin precursor material containing phosphorus and nitrogen elements and uses pyrolysis to prepare a hard carbon material with phosphorus and nitrogen dual doping to solve the problems of low lithium storage capacity and poor rate performance of existing hard carbon anode materials; and to improve the energy density, rate performance, and cycle life of lithium-ion batteries. Summary of the Invention

[0005] The object of the present invention is to overcome the disadvantages of the prior art, and provide a high-capacity resin-based hard carbon negative electrode material containing phosphorus and nitrogen dual doping and a preparation method thereof. This material reacts the self-innovatively synthesized nitrogen-containing organic compound 3-aminophenoxyphthalonitrile and the phosphorus-containing organic compound 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide DOPO to prepare a resin-based precursor material containing phosphorus and nitrogen dual doping. The precursor material is pyrolyzed, crosslinked and carbonized to obtain a phosphorus and nitrogen dual-doped resin-based hard carbon negative electrode material. Through the phosphorus and nitrogen dual doping, the present invention effectively improves the specific capacity, cycle stability and rate performance of the hard carbon material, and solves the problem of limited theoretical capacity of the graphite negative electrode of lithium-ion batteries; the prepared hard carbon negative electrode material has high lithium-ion storage capacity and excellent electrochemical performance, and is particularly suitable for high-performance lithium-ion batteries; the preparation method of this material is simple and easy to implement, and has good industrialization prospects.

[0006] To achieve the above technical effects, the following technical solutions are adopted:

[0007] A preparation method of a high-capacity resin-based hard carbon negative electrode material containing phosphorus and nitrogen dual doping, comprising:

[0008] Step S1: Weigh the nitrogen-containing organic compound and the phosphorus-containing organic compound according to different doping ratios, mix and react the nitrogen-containing organic compound and the phosphorus-containing organic compound in a solvent, heat up the solution for reaction and then precipitate solids, and obtain a resin-based precursor material containing phosphorus and nitrogen dual doping after washing and drying;

[0009] Step S2: Pyrolyze the precursor material obtained in Step S1 to cause crosslinking reaction of the precursor material, and obtain a crosslinked precursor material;

[0010] Step S3: Place the crosslinked precursor material obtained in Step S2 under an inert gas protection atmosphere, control the heating rate and temperature, and carbonize the crosslinked precursor material to obtain high-capacity resin-based hard carbon materials with different phosphorus and nitrogen doping ratios.

[0011] Step S4: Put the hard carbon material obtained in Step S3 into a ball mill for ball milling, so as to prepare high-capacity resin-based hard carbon negative electrode materials with different phosphorus and nitrogen doping ratios;

[0012] The nitrogen-containing organic compound is 3-aminophenoxyphthalonitrile;

[0013] The phosphorus-containing organic compound is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide DOPO.

[0014] Furthermore, the mass ratio of the nitrogen-containing organic compound to the phosphorus-containing organic compound in Step S1 is 1-2:1-3.

[0015] Further, the solvent in step S1 includes ethanol; the reaction temperature and precipitation temperature in step S1 are 70 - 90°C, and the reaction time is 4 - 6 h.

[0016] Further, the preparation method of the nitrogen-containing organic compound 3-aminophenoxyphthalonitrile in step S1 is as follows:

[0017] Mix 0.1 - 0.3 mol of 4-nitrophthalonitrile, 0.1 - 0.3 mol of 3-aminophenol, and 0.12 - 0.24 mol of anhydrous potassium carbonate in 30 - 60 ml of dimethyl sulfoxide, reflux at 80 - 90°C for 8 - 10 hours under nitrogen protection, pour into distilled water after cooling to precipitate solids, and obtain 3-aminophenoxyphthalonitrile through filtration and purification.

[0018] Further, the specific preparation method of the phosphorus and nitrogen co-doped resin-based precursor material in step S1 is as follows:

[0019] Mix 0.05 - 0.1 mol of 3-aminophenoxyphthalonitrile with 1.5 - 3 g of paraformaldehyde in 100 - 200 ml of ethanol, introduce nitrogen, add 0.05 - 0.15 mol of the phosphorus-containing organic compound 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 5 - 10 ml of formic acid, heat the solution to 70 - 90°C and react for 4 - 6 hours, precipitate yellow solids, and obtain the phosphorus and nitrogen co-doped resin-based precursor material after washing and drying.

[0020] Further, the heating program during the pyrolysis cross-linking process in step S2 is as follows:

[0021] Heat at a heating rate of 5 - 10°C / min to 200 - 300°C, and keep the temperature for 4 - 6 h.

[0022] Further, the inert gas atmosphere in step S3 includes argon; the carbonization treatment container is a tube furnace; the heating program during the carbonization treatment is as follows:

[0023] Heat at a heating rate of 5 - 10°C / min to 500 - 900°C, and keep the temperature for 2 - 4 h.

[0024] Further, the ball milling time in step S4 is 30 - 45 min.

[0025] A phosphorus and nitrogen co-doped high-capacity resin-based hard carbon negative electrode material is prepared by the above preparation method.

[0026] Further, the application of the hard carbon negative electrode material on the graphite negative electrode of a lithium-ion battery.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. The hard carbon negative electrode material of the present invention benefits from heteroatom doping, introducing a nitrogen element component synthesized independently and innovatively in the hard carbon material, thereby providing more reactive sites for the material and enhancing the electronic conductivity. Introducing phosphorus element improves the specific capacity of the material, and the lithium storage capacity of the hard carbon material is significantly improved, thus obtaining a hard carbon negative electrode material with high capacity; achieving a high specific capacity;

[0029] 2. The hard carbon negative electrode material of the present invention has good cycle stability, with strong cycle stability at high rates and is suitable for high-performance batteries;

[0030] 3. The preparation method of the hard carbon negative electrode material of the present invention is simple, using common raw materials, and the preparation process is simple and easy to implement, with the potential for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. The drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0032] Figure 1 It is the X-ray diffraction pattern of the material prepared in Example 1 of the present invention at a carbonization temperature of 600°C;

[0033] Figure 2 It is the cycle performance of the material prepared in Example 1 of the present invention at a carbonization temperature of 600°C;

[0034] Figure 3 It is the rate performance of the material prepared in Example 1 of the present invention at a carbonization temperature of 600°C;

[0035] Figure 4 It is the X-ray diffraction pattern of the material prepared in Example 2 of the present invention at a carbonization temperature of 750°C;

[0036] Figure 5 It is the cycle performance of the material prepared in Example 2 of the present invention at a carbonization temperature of 750°C;

[0037] Figure 6 It is the rate performance of the material prepared in Example 2 of the present invention at a carbonization temperature of 750°C;

[0038] Figure 7 It is the X-ray diffraction pattern of the material prepared in Example 3 of the present invention at a carbonization temperature of 900°C;

[0039] Figure 8 It is the cycle performance of the material prepared in Example 3 of the present invention at a carbonization temperature of 900°C;

[0040] Figure 9 This is the rate performance of the material prepared in Example 3 of the present invention at a carbonization temperature of 900 °C. Detailed implementation mode

[0041] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanations of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0043] It should be noted that the terms used herein are only for describing specific implementation modes and are not intended to limit the exemplary implementation modes according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "include" and / or "comprise" are used in this specification, they indicate the presence of features, steps, operations and / or combinations thereof.

[0044] In the following examples, unless otherwise specified, all reagents and consumables are purchased from conventional reagent manufacturers in the art; unless otherwise specified, the experimental methods and technical means used are conventional methods and means in the art.

[0045] The following describes the high-capacity resin-based hard carbon anode material containing phosphorus and nitrogen dual doping and its performance provided by the present invention in conjunction with embodiments. The protection scope of the present invention is not limited by the following examples.

[0046] Example 1:

[0047] 1. Preparation of nitrogen-containing organic compound 3-aminophenoxyphthalonitrile

[0048] 0.1 mol of 4-nitrophthalonitrile, 0.1 mol of 3-aminophenol and 0.12 mol of anhydrous potassium carbonate were mixed in 30 ml of dimethyl sulfoxide, refluxed at 80 °C for 8 hours under nitrogen protection, cooled and poured into distilled water to precipitate a solid, which was obtained by filtration and purification to obtain 3-aminophenoxyphthalonitrile.

[0049] 2. Preparation of resin-based precursor material containing phosphorus and nitrogen dual doping

[0050] 0.05 mol of 3-aminophenoxyphthalonitrile was mixed with 1.5 g of paraformaldehyde in 100 ml of ethanol. Nitrogen was introduced, and 0.05 mol of a phosphorus-containing organic compound, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), and 5 ml of formic acid were added. The solution was heated to 70 °C and reacted for 4 hours to precipitate a yellow solid. After washing and drying, a phosphorus and nitrogen co-doped resin-based precursor material PNP was obtained.

[0051] 3. Preparation of a high-capacity resin-based hard carbon anode material with phosphorus and nitrogen co-doping

[0052] 5 g of the prepared phosphorus and nitrogen co-doped resin-based precursor material PNP powder was placed in a crucible, and the crucible was placed in a muffle furnace. The temperature was raised to 200 °C at a heating rate of 5 °C / min, and the holding time was 4 h to cause cross-linking of the material. Then the material was transferred to a tubular furnace, and under an argon atmosphere, the temperature was raised to 600 °C at a heating rate of 5 °C / min, and the holding time was 2 h. The carbonized material was taken out, and its mass was about 3.7 g.

[0053] 2 g of the carbonized material was weighed and placed in a stainless steel ball milling jar, and 20 g of stainless steel balls were weighed. Ball milling was carried out for 30 min to obtain a high-capacity resin-based hard carbon anode material powder with phosphorus and nitrogen co-doping. Its XRD is as Figure 1 shown.

[0054] 4. Preparation of a lithium-ion battery

[0055] 70 wt% of the high-capacity resin-based hard carbon anode material powder with phosphorus and nitrogen co-doping, 20 wt% of acetylene black, and 10 wt% of sodium carboxymethyl cellulose (CMC) were stirred for 4 h to obtain a uniform slurry. Subsequently, it was uniformly coated on a copper foil and dried at 60 °C for 8 h. The loading of the electrode active material was 1.0 - 1.5 mg / cm 2 , and the electrode thickness was about 15 μm. The electrolyte used 1.0 M LiPF6 dissolved in ethylene carbonate (EC) and dimethyl carbonate (DMC), and the separator was a Celgard 2400 type microporous polypropylene film. During battery assembly, the negative electrode, positive electrode, and separator were placed in a CR2032 coin cell casing, the electrolyte was injected, and the battery was sealed.

[0056] The performance of the lithium-ion battery was tested. The cycling performance is as Figure 2 shown. It can be seen that for the lithium-ion battery at a current density of 1 A / g, the specific capacity was stable at about 330 mAh / g, and after 1000 cycles, the capacity still had a specific capacity of 230 mAh / g. Its rate performance is as Figure 3 shown. It can be seen that at a current density of 4 A / g, there was still a specific capacity of 170 mAh / g.

[0057] Example 2:

[0058] The main difference between Example 2 and Example 1 is that the carbonization temperature in Example 2 is 750 °C. The XRD of the prepared material is as Figure 4 shown.

[0059] The performance of the lithium-ion battery was tested. The cycling performance is as Figure 5 shown. It can be seen that for the lithium-ion battery at a current density of 1 A / g, the specific capacity is stable at about 400 mAh / g, and after 1000 cycles, the specific capacity is still 340 mAh / g. Its rate performance is as Figure 6 shown. It can be seen that at a current density of 4 A / g, the specific capacity is still 150 mAh / g.

[0060] Example 3:

[0061] The main difference between Example 3 and Example 1 is that the carbonization temperature in Example 3 is 900 °C. The XRD of the prepared material is as Figure 7 shown.

[0062] The performance of the lithium-ion battery was tested. The cycling performance is as Figure 8 shown. It can be seen that for the lithium-ion battery at a current density of 1 A / g, the specific capacity is stable at about 306 mAh / g, and after 1000 cycles, the specific capacity is still 350 mAh / g. Its rate performance is as Figure 9 shown. It can be seen that at a current density of 4 A / g, the specific capacity is still 198 mAh / g.

[0063] Comparative Example 1:

[0064] Based on the preparation process of Example 1, in this comparative example, 3-aminophenoxyphthalonitrile was replaced with 4-aminophenoxyphthalonitrile, and other processes were the same as those in Example 1.

[0065] 1. Preparation of the nitrogen-containing organic compound 4-aminophenoxyphthalonitrile

[0066] 0.1 mol of 4-nitrophthalonitrile, 0.1 mol of 4-aminophenol, and 0.12 mol of anhydrous potassium carbonate were mixed in 30 ml of dimethyl sulfoxide, refluxed at 80 °C for 8 hours under nitrogen protection, and after cooling, poured into distilled water to precipitate a solid, which was obtained as 4-aminophenoxyphthalonitrile through filtration and purification. The subsequent experimental steps were the same as those in Example 1 of the present invention.

[0067] After replacing the nitrogen-containing organic compound, although the reaction process is similar, the ability and effect of reacting with DOPO are different. The battery performance of the finally obtained material is poor, the specific capacity and cycle stability of the material are low. At a current density of 1 A / g, the specific capacity of the material is only 135 mAh / g, and after 1000 cycles, the specific capacity is only 50 mAh / g. It may be that 4-aminophenoxyphthalonitrile cannot react sufficiently with DOPO, resulting in more structural defects in the material, which affects the conductivity and cycle performance of the battery.

[0068] Comparative Example 2:

[0069] Based on the preparation process of Example 1, in this comparative example, the phosphorus-containing organic compound was replaced with 9-amino-10-phosphaphenanthrene, and other processes were the same as those in Example 1.

[0070] 2. Preparation of the resin-based precursor material with phosphorus and nitrogen co-doping

[0071] 0.05 mol of 3-aminophenoxyphthalonitrile and 1.5 g of paraformaldehyde were mixed in 100 ml of ethanol, nitrogen was introduced, 0.05 mol of phosphorus-containing organic compound (9-amino-10-phosphaphenanthrene) and 5 ml of formic acid were added, and the solution was heated to 70 °C and reacted for 4 hours to precipitate a yellow solid. After washing and drying, the resin-based precursor material with phosphorus and nitrogen co-doping was obtained. The subsequent experimental steps were the same as those in Example 1 of this patent.

[0072] Using 9-amino-10-phosphaphenanthrene instead of DOPO, after reacting with 3-aminophenoxyphthalonitrile, the improvement of the battery performance of the finally obtained resin-based precursor material is not obvious. At a current density of 1 A / g, the specific capacity of the material is only 189 mAh / g, and after 1000 cycles, the specific capacity is only 140 mAh / g. Although the phosphorus-containing organic compound participated in the reaction, the doping effect of phosphorus in the material is not ideal, resulting in poor capacitance and cycle stability of the battery.

[0073] Comparative Example 3:

[0074] Based on the preparation process of Example 1, in this comparative example, the cross-linking step was not carried out, and it was directly heated to carbonize, and other processes were the same as those in Example 1.

[0075] The phosphorus and nitrogen co-doped resin-based precursor material is directly heated to 600 °C in a nitrogen atmosphere at a heating rate of 5 °C / min without a cross-linking step, and other experimental steps are the same as those in Example 1 of this patent. For the material directly carbonized by skipping the cross-linking step, although it has been carbonized, due to the lack of structural strengthening during the cross-linking process, the resulting hard carbon structure is loose, leading to a significant decrease in the cycle stability of the battery. At a current density of 1 A / g, although the initial specific capacity of the material reaches 430 mAh / g, after 1000 cycles, the specific capacity is only 124 mAh / g.

[0076] Comparative Example 4:

[0077] Based on the preparation process of Example 1, the cross-linking temperature in this comparative example is increased to 400 °C and the time remains unchanged, and other processes are the same as those in Example 1.

[0078] The phosphorus and nitrogen co-doped resin-based precursor material is cross-linked at a cross-linking temperature of 400 °C and then carbonized, and other experimental steps are the same as those in Example 1 of this patent. Cross-linking at 400 °C can enhance the stability of the material, but too high a cross-linking temperature will cause the structure of the material to be too dense, resulting in a decrease in the capacitance of the battery. At a current density of 1 A / g, the initial specific capacity of the material is only 230 mAh / g, and after 1000 cycles, the specific capacity is only 221 mAh / g.

[0079] Comparative Example 5:

[0080] Based on the preparation process of Example 1, the cross-linking time in this comparative example is increased to 8 hours and the temperature remains unchanged, and other processes are the same as those in Example 1.

[0081] The phosphorus and nitrogen co-doped resin-based precursor material is cross-linked for 8 hours and then carbonized, and other experimental steps are the same as those in Example 1 of this patent. Prolonging the cross-linking time helps to enhance the degree of cross-linking of the material, but too long a cross-linking time may cause the material to be over-cross-linked, with a too rigid structure, reduced porosity, affecting the capacitance and cycle stability of the battery, and showing poor battery performance. At a current density of 1 A / g, the initial specific capacity of the material is only 268 mAh / g, and after 1000 cycles, the specific capacity is only 155 mAh / g.

[0082] Comparative Example 6:

[0083] Based on the preparation process of Example 1, the carbonization heating rate in this comparative example is 50 °C / min and the carbonization temperature is 600 °C, and other processes are the same as those in Example 1.

[0084] The resin-based precursor material doped with both phosphorus and nitrogen is carbonized at a heating rate of 50 °C / min and a carbonization temperature of 600 °C. Other experimental steps are the same as those in Example 1 of this patent. Although increasing the carbonization heating rate may shorten the preparation time, it causes incomplete formation of the material structure during carbonization, resulting in poor capacitance and stability of the battery. This may be because the unstable intermediate phase in the material fails to be fully converted due to the rapid heating. At a current density of 1 A / g, the initial specific capacitance of the material is only 244 mAh / g, and after 1000 cycles, the specific capacitance is only 157 mAh / g.

[0085] Comparative Example 7:

[0086] Based on the preparation process of Example 1, the cross-linking heating rate in this comparative example is 40 °C / min, the cross-linking temperature remains unchanged, and other processes are the same as those in Example 1.

[0087] The resin-based precursor material doped with both phosphorus and nitrogen is cross-linked at a cross-linking heating rate of 40 °C / min, and then carbonized. Other experimental steps are the same as those in Example 1 of this patent. The relatively high heating rate makes the cross-linking process too fast, resulting in an uneven material structure, poor cycle stability of the battery, and low capacitance. This may be because the cross-linking reaction is incomplete, leading to an unstable pore structure of the hard carbon material, thus affecting its battery performance. At a current density of 1 A / g, the initial specific capacitance of the material is only 235 mAh / g, and after 1000 cycles, the specific capacitance is only 171 mAh / g.

[0088] In summary, the present invention discloses a high-capacity resin-based hard carbon negative electrode material doped with both phosphorus and nitrogen and a preparation method thereof. This material is prepared by reacting the nitrogen-containing organic compound 3-aminophenoxyphthalonitrile synthesized through independent innovation and the phosphorus-containing organic compound 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide DOPO to obtain a resin-based precursor material doped with both phosphorus and nitrogen. The precursor material is subjected to pyrolytic cross-linking and carbonization treatments to obtain a phosphorus and nitrogen dual-doped resin-based hard carbon negative electrode material. Through phosphorus and nitrogen dual doping, the present invention effectively improves the specific capacitance, cycle stability, and rate performance of the hard carbon material, and solves the problem of the limited theoretical capacity of the graphite negative electrode of lithium-ion batteries; the prepared hard carbon negative electrode material has high lithium-ion storage capacity and excellent electrochemical performance, and is particularly suitable for high-performance lithium-ion batteries; the preparation method of this material is simple and feasible, and has good industrialization prospects.

[0089] At this point, those skilled in the art recognize that although the embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived from the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and determined to cover all these other variations or modifications.

Claims

1. A preparation method of a high-capacity resin-based hard carbon anode material containing phosphorus and nitrogen dual doping, characterized in that, The preparation method includes the following steps: Step S1: Weigh nitrogen-containing organic compounds and phosphorus-containing organic compounds according to different doping ratios, mix and react the nitrogen-containing organic compounds and the phosphorus-containing organic compounds in a solvent, heat up the solution for reaction, and then precipitate solids. After washing and drying, a resin-based precursor material with phosphorus and nitrogen co-doping is obtained; Step S2: Pyrolyze the precursor material obtained in Step S1 to cause cross-linking reaction of the precursor material, and obtain a cross-linked precursor material; Step S3: Place the cross-linked precursor material obtained in Step S2 under an inert gas protection atmosphere, control the heating rate and temperature, and perform carbonization treatment on the cross-linked precursor material to obtain a high-capacity resin-based hard carbon material with different phosphorus and nitrogen doping ratios; Step S4: Put the hard carbon material obtained in Step S3 into a ball mill for ball milling, so as to prepare a high-capacity resin-based hard carbon negative electrode material with different phosphorus and nitrogen doping ratios; The nitrogen-containing organic compound is 3-aminophenoxyphthalonitrile; The phosphorus-containing organic compound is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide DOPO; The heating program in the pyrolysis cross-linking process in Step S2 is as follows: Heat up at a heating rate of 5-10 °C / min to 200-300 °C, and keep the temperature for 4-6 h; The inert gas atmosphere in Step S3 includes argon; the carbonization treatment container is a tube furnace; the heating program in the carbonization treatment process is as follows: Heat up at a heating rate of 5-10 °C / min to 500-900 °C, and keep the temperature for 2-4 h.

2. The preparation method of a high-capacity resin-based hard carbon anode material containing phosphorus and nitrogen dual doping as described in claim 1, characterized in that, The mass ratio of the nitrogen-containing organic compound to the phosphorus-containing organic compound in Step S1 is 1-2:1-3.

3. The preparation method of a high-capacity resin-based hard carbon anode material containing phosphorus and nitrogen dual doping as described in claim 1, characterized in that, The solvent in Step S1 includes ethanol; the reaction temperature and precipitation temperature in Step S1 are 70-90 °C, and the reaction time is 4-6 h.

4. The preparation method of a high-capacity resin-based hard carbon anode material containing phosphorus and nitrogen dual doping as described in claim 1, characterized in that, The preparation method of the nitrogen-containing organic compound 3-aminophenoxyphthalonitrile in Step S1 is as follows: Mix 0.1-0.3 mol of 4-nitrophthalonitrile, 0.1-0.3 mol of 3-aminophenol and 0.12-0.24 mol of anhydrous potassium carbonate in 30-60 ml of dimethyl sulfoxide, reflux at 80-90 °C for 8-10 hours under nitrogen protection, pour the solution into distilled water after cooling to precipitate solids, and obtain 3-aminophenoxyphthalonitrile through filtration and purification.

5. The preparation method of a high-capacity resin-based hard carbon anode material containing phosphorus and nitrogen dual doping as described in claim 1, characterized in that, The specific preparation method of the resin-based precursor material with phosphorus and nitrogen co-doping in Step S1 is as follows: Mix 0.05-0.1 mol of 3-aminophenoxyphthalonitrile with 1.5-3 g of paraformaldehyde in 100-200 ml of ethanol, introduce nitrogen, add 0.05-0.15 mol of the phosphorus-containing organic compound 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide DOPO and 5-10 ml of formic acid, heat up the solution to 70-90 °C for reaction for 4-6 hours, precipitate yellow precipitate, and obtain the resin-based precursor material with phosphorus and nitrogen co-doping after washing and drying.

6. The preparation method of a high-capacity resin-based hard carbon anode material containing phosphorus and nitrogen dual doping as described in claim 1, wherein, The ball milling time in Step S4 is 30-45 min.

7. A high-capacity resin-based hard carbon anode material containing phosphorus and nitrogen dual doping, characterized in that, The hard carbon negative electrode material is prepared by the preparation method according to any one of claims 1-6.

8. A high-capacity resin-based hard carbon anode material containing phosphorus and nitrogen dual doping as described in claim 7, characterized in that, Application of the hard carbon negative electrode material on the graphite negative electrode of a lithium-ion battery.

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