Phosphorus-doped porous carbon / silicon composite negative electrode material and preparation method thereof

Abstract

The application provides a phosphorus-doped porous carbon / silicon composite negative electrode material and a preparation method thereof, and belongs to the technical field of new energy battery electrode materials. The preparation method comprises the following steps: preparing a homogeneous solution by using dextrin; adding a phytic acid solution to construct a hydrogen bond cross-linking network; introducing a melamine solution; adding sodium chloride for dispersion to obtain a mixed solution; transferring the mixed solution into a reaction kettle to form microsphere initial embryos through heat-driven self-assembly; filtering and washing to obtain a hydrothermal product; carbonizing the hydrothermal product under a nitrogen atmosphere, washing and removing the sodium chloride template after cooling, and vacuum drying to obtain nitrogen and phosphorus co-doped porous carbon microspheres; adding the nitrogen and phosphorus co-doped porous carbon microspheres and red phosphorus into a quartz tube, vacuumizing and sealing, and obtaining red phosphorus-loaded carbon microspheres through stage-by-stage gas phase loading; mixing the red phosphorus-loaded carbon microspheres, silicon nanoparticles and dextrin in an ethanol medium, ball-milling, performing gas phase carbon coating after spray drying, and obtaining the phosphorus-doped porous carbon / silicon composite negative electrode material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy battery electrode materials, in particular to a phosphorus-doped porous carbon / silicon composite negative electrode material and a preparation method thereof. BACKGROUND

[0002] Lithium ion batteries are widely used in various electronic devices due to their high energy density, high working voltage, and long cycle stability. Among various negative electrode materials, phosphorus-based negative electrode materials have become an important research direction for achieving high energy density and high rate performance in the future due to their high theoretical specific capacity, excellent rate performance, and relatively low cost.

[0003] Elemental phosphorus mainly has three allotropes: white phosphorus, black phosphorus, and red phosphorus. Black phosphorus is difficult to prepare and expensive, white phosphorus is extremely unstable in air and difficult to handle, while red phosphorus is not only low in price, excellent in lithium storage performance, and relatively stable. However, as an insulator of electrons and ions, it cannot be directly used as an electrode active material. Therefore, how to overcome the insulating property of red phosphorus, fully utilize its low cost and high lithium storage capacity, and develop a lithium ion battery negative electrode material based on red phosphorus is of great significance for the research and development of lithium ion batteries. SUMMARY

[0004] To solve the problems mentioned in the background, the present application provides a preparation method of a phosphorus-doped porous carbon / silicon composite negative electrode material, which produces a deep synergistic effect in microstructure, conductive network, and interface chemistry of silicon, phosphorus, and carbon. Finally, a battery negative electrode material with high specific capacity, excellent rate performance, and ultra-long cycle life is successfully prepared.

[0005] Specifically,

[0006] A preparation method of a phosphorus-doped porous carbon / silicon composite negative electrode material, the steps of which include:

[0007] Step 1: 100-120 parts by mass of dextrin is added to 300-400 parts of deionized water to prepare a homogeneous solution; 60-65 parts of phytic acid solution is added to build a hydrogen bond crosslinking network under controlled conditions; 40-45 parts of melamine is introduced to control the dissolution under controlled conditions; 150-170 parts of sodium chloride is added to control the dispersion under controlled conditions, and a mixed solution is obtained;

[0008] Step 2: The mixed solution obtained in step 1 is transferred to a reaction kettle, and a microsphere embryo is formed by heat-driven self-assembly under controlled conditions. After filtration and washing, a hydrothermal product is obtained;

[0009] Step 3: The hydrothermal product is carbonized under nitrogen atmosphere, and after cooling, the sodium chloride template is removed by washing, and vacuum drying is performed to obtain nitrogen and phosphorus co-doped porous carbon microspheres;

[0010] Step 4, take 100-120 parts of the nitrogen and phosphorus co-doped porous carbon microspheres obtained in step 3 and 80-85 parts of red phosphorus, add them to a quartz tube, vacuum seal, and control the conditions to obtain red phosphorus loaded carbon microspheres by stage-by-stage gas phase loading;

[0011] Step 5, take 100-120 parts of the red phosphorus loaded carbon microspheres obtained in step 4, mix them with 15-16 parts of silicon nanoparticles and 5-5.5 parts of dextrin in 200-250 parts of an ethanol medium, ball mill, spray dry, and then heat solidify the dextrin to form microspheres, and then perform gas phase carbon coating on the composite particles to obtain a phosphorus doped porous carbon / silicon composite negative electrode material.

[0012] Further, the phytic acid solution in step 1 is a 50%-55% mass fraction aqueous phytic acid solution.

[0013] Further, after adding the phytic acid solution in step 1, heat to 55-65°C, and react for 30-40 min to construct a hydrogen bond crosslinking network; after adding the melamine, heat to 80-85°C and stir for 1-1.5 h until completely dissolved; after adding the sodium chloride, control the stirring rate at 5000-6000 rpm, and stir for 10-15 min until completely dispersed.

[0014] Further, in step 2, control the filling degree to be ≤70% when transferring the mixed solution to the reaction kettle; heat to 220-230°C at a rate of 5°C, and keep the temperature for 12-14 h, and then cool to 80°C to discharge, vacuum filter, and wash with 80°C deionized water for 3-5 times.

[0015] Further, in step 3, the temperature increasing and carbonizing process is a gradient temperature increasing process, first heat to 300°C at a rate of 5°C, keep the temperature for 1 h, then heat to 750°C at a rate of 3°C, keep the temperature for 2 h; after cooling to room temperature, wash with deionized water to remove the sodium chloride template; the temperature of the vacuum drying process is controlled at 80°C, and the drying time is 12 h.

[0016] Further, in step 4, the stage-by-stage gas phase loading process includes: stage 1, heat to 416°C at a rate of 10°C / min, keep the temperature for 4 h; stage 2, cool to 260°C at a rate of 5°C / min, keep the temperature for 8 h; stage 3, cool to <60°C in the furnace, and then break the vacuum.

[0017] Further, in step 4, when vacuum sealing, the tube length of the quartz tube is left with an expansion space of 30%-33%.

[0018] Further, in step 5, the spray drying control conditions are an inlet temperature of 180-190°C, an outlet temperature of 70-80°C, and a powder particle size of 8-15 μm.

[0019] Further, in step 5, the gas phase carbon coating control conditions are that the carbon source is selected from acetylene, the temperature is 650-660°C, and the treatment time is 1-1.2 h.

[0020] The application further provides a phosphorus-doped porous carbon / silicon composite negative electrode material prepared by the preparation method.

[0021] Compared with the prior art, the application has the beneficial features that:

[0022] 1. The application constructs a "core-shell-bridge" three-level composite structure, three-dimensional porous nitrogen and phosphorus co-doped carbon microspheres as the core framework, the internal through porous structure provides sufficient space for the loading of red phosphorus, and the red phosphorus is firmly anchored through the strong P-C covalent bond, effectively buffering the volume expansion of red phosphorus in the cycle and preventing the active material from pulverizing and falling off. At the same time, the carbon framework also serves as a dispersion matrix, uniformly restricting the silicon nanoparticles on its surface and in its pores, greatly relieving the volume effect of the silicon material. The physical confinement effect of the carbon framework and the chemical bonding effect of the P-C bond cooperate to ensure the integrity of the electrode structure in long-term cycling, thereby achieving high specific capacity while ensuring cycle stability.

[0023] Synergistic mechanism: first, the three-dimensional porous carbon microspheres constructed by the sodium chloride template method have internal nanoscale pores that are interconnected, providing a predetermined space for the storage of red phosphorus. When red phosphorus is filled into these pores by the gas deposition method, the volume expansion during the charging and discharging process will be limited and constrained by the hard carbon wall, thereby converting the macroscopic volume change into local stress within the microcavity, avoiding the pulverizing destruction of the entire electrode. Secondly, pure physical contact will fail due to stress fatigue in long-term cycling, and in the gas loading stage of the application, the annealing process promotes the chemical reaction between the gaseous molecules and the defect carbon atoms (introduced by nitrogen doping or mechanical ball milling) at the edges of the carbon framework, forming a strong P-C covalent bond. At the same time, the introduction of nitrogen atoms can promote the adsorption of phosphorus atoms by the carbon matrix. This upgrades the red phosphorus and the carbon framework from "physical adsorption" to "chemical anchoring", greatly enhancing the bonding energy of the interface and effectively preventing the shedding and loss of the active material in the cycle. Finally, in the silicon-carbon composite stage, the hydroxyl groups (-OH) on the surface of the dextrin as a biological binder undergo a dehydration condensation reaction with the hydroxyl groups in the oxide layer (SiO2) on the surface of the silicon nanoparticles, forming a Si-O-C covalent bond bridge. This makes the silicon particles and carbon microspheres no longer simply mechanically contact, but are firmly chemically connected, ensuring efficient transmission of electrons and ions between the interfaces and inhibiting the agglomeration of silicon particles.

[0024] 2、The present application constructs a high-efficiency three-dimensional network for the rapid transmission of electrons and ions through the multi-level structure of the material. The nitrogen and phosphorus co-doped carbon skeleton significantly improves the intrinsic electronic conductivity. The nitrogen doping provides abundant free electrons, and the phosphorus doping expands the carbon layer spacing, promoting the embedding and extraction of lithium ions. Subsequently, the thin layer of amorphous carbon coated by chemical vapor deposition further forms a continuous and strong conductive network outside the composite particles, greatly reducing the interface impedance and polarization of the electrode. The internal doping modification and external uniform coating work together to ensure that electrons and ions can quickly reach every active site under high-rate charging and discharging conditions, thereby giving the material excellent rate performance.

[0025] Synergistic mechanism: First, the doping behavior of nitrogen and phosphorus atoms in the carbon lattice has a synergistic effect. Nitrogen atoms have a stronger attraction to electrons than carbon atoms, and doping will make the adjacent carbon atoms carry partial positive charges, which is more conducive to adsorbing lithium ions and reducing the migration energy barrier. At the same time, the incorporation of phosphorus atoms will expand the carbon layer spacing, providing a more spacious "channel" for the embedding and extraction of lithium ions, and improving the ionic conductivity. Together, they optimize the charge transport capability of the carbon skeleton itself. Second, the thin layer of amorphous carbon deposited by vapor deposition is like a conductive outer layer wrapped around each composite particle, and all the particles are "welded" into a continuous conductive whole. This greatly reduces the contact resistance between particles, ensuring that electrons can quickly transport to every active particle, especially at high-rate discharge, where this effect is crucial.

[0026] 3、The present application optimizes the interface between the electrode material and the electrolyte. The carbon coating layer deposited by vapor deposition greatly reduces the specific surface area of the composite material, reducing the contact surface with the electrolyte and effectively inhibiting the excessive growth of the solid-state electrolyte interface film (SEI), significantly improving the first coulombic efficiency. Second, the strong P-C and Si-O-C bonds prevent red phosphorus and silicon from falling off the carbon base during the cycling process, preventing the continuous exposure of fresh interfaces and the repeated rupture and reconstruction of the SEI film, ensuring the stability of the interface film. The synergistic effect of the two ensures the stability of the interface state during long-term cycling of the battery, which is the key to long life. In addition, nitrogen doping changes the electron cloud distribution of the surrounding carbon atoms, making them exhibit electron deficiency (positive charge). The gas-phase molecules will undergo bond polarization during heating, exhibiting a certain negative charge. According to the Lewis acid-base theory, there is a strong adsorption between the electron-deficient carbon sites (Lewis Acid) and the electron-rich phosphorus species (Lewis Base). This force makes molecules more inclined to accumulate near the defect sites of the carbon skeleton, creating a favorable local high-concentration environment and driving force for the subsequent chemical reaction to form P-C bonds. DETAILED DESCRIPTION

[0027] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0028] In order to facilitate those skilled in the art to implement the present application, some reagents used in the examples and comparative examples will be described:

[0029] Dextrin: Zhengzhou Yinhe Dextrin Co., Ltd.;

[0030] Phytic acid: Nanjing Songguan Biological Technology Co., Ltd.;

[0031] Melamine: Shandong Han Yue Chemical Co., Ltd.;

[0032] Sodium chloride: Taizhou Bai Chuan Chemical Co., Ltd.;

[0033] Silicon nanoparticles: 40-60 nm, Zhongnuo New Material (Beijing) Technology Co., Ltd.;

[0034] Acetylene: Qingdao Fuda Gas Co., Ltd.

[0035] Example 1

[0036] A phosphorus-doped porous carbon / silicon composite negative electrode material, the preparation steps of which comprise:

[0037] Step 1, 100 parts of dextrin are added to 300 parts of deionized water to stir at a speed of 300 rpm until transparent, to configure a homogeneous solution; 60 parts of a 50% mass fraction phytic acid solution are added, heated to 55°C, and reacted for 30 min to build a hydrogen bond crosslinking network; 40 parts of melamine are introduced, heated to 80°C, and stirred for 1 h until completely dissolved; 150 parts of sodium chloride are added, stirred at 5000 rpm for 15 min, and dispersed by high-speed shearing to obtain a mixed solution;

[0038] Step 2, the mixed solution obtained in step 1 is transferred to a reaction kettle, the filling degree is 70%, the temperature is raised to 220°C at a rate of 5°C, and the temperature is kept for 12 h, then cooled to 80°C to discharge, and the microsphere initial embryo is formed by heat-driven self-assembly; vacuum suction filtration is performed, and the hydrothermal product is obtained by washing with 80°C deionized water for 3 times;

[0039] Step 3, the hydrothermal product is first heated to 300℃ at a temperature rising rate of 5℃ under a nitrogen atmosphere (200mL / min) and kept for 1h to remove the combined water; then heated to 750℃ at a temperature rising rate of 3℃ and kept for 2h to carbonize / activate; after cooling to room temperature, the product is washed with deionized water to remove sodium chloride template until the conductivity of the filtrate is <10μS / cm; vacuum dried at 80℃ for 12h to obtain nitrogen and phosphorus co-doped porous carbon microspheres;

[0040] Step 4, 100 parts of the nitrogen and phosphorus co-doped porous carbon microspheres obtained in step 3 and 80 parts of red phosphorus are added to a quartz tube (diameter 50mm), vacuumed to 10 -3 Pa, sealed, leaving 30% expansion space; loaded in stages, stage 1, heated to 416℃ at a temperature rising rate of 10℃ / min and kept for 4h; stage 2, cooled to 260℃ at a temperature rising rate of 5℃ / min and kept for 8h; stage 3, after cooling to 59℃ in the furnace, the vacuum is broken to obtain red phosphorus loaded carbon microspheres;

[0041] Step 5, 100 parts of the red phosphorus loaded carbon microspheres obtained in step 4, 15 parts of silicon nanoparticles and 5 parts of dextrin are mixed in 200 parts of ethanol medium and ball milled at a speed of 350 rpm for 3h; then the dextrin is heat cured to form microspheres after spray drying, the spray drying control conditions are inlet temperature 180℃, outlet 70℃, and the powder particle size is 8-15μm; the composite particles are placed in a CVD furnace, acetylene (20mL / min) and nitrogen (200mL / min) are introduced, and treated at 650℃ for 1h to deposit a carbon layer with a thickness of about 5nm to obtain a phosphorus doped porous carbon / silicon composite anode material.

[0042] Example 2

[0043] A phosphorus doped porous carbon / silicon composite anode material, the preparation steps of which comprise:

[0044] Step 1, 120 parts of dextrin are added to 400 parts of deionized water to form a homogeneous solution by stirring at a speed of 300rpm until transparent; 65 parts of a 55% phytic acid solution are added, heated to 65℃ and reacted for 40min to construct a hydrogen bond crosslinking network; 45 parts of melamine are introduced, heated to 85℃ and stirred for 1.5h until completely dissolved; 170 parts of sodium chloride are added and stirred at a speed of 6000rpm for 15min to obtain a mixed solution by high-speed shearing dispersion;

[0045] Step 2, the mixed solution obtained in step 1 is transferred to a reaction kettle, the filling degree is 65%, heated to 230℃ at a temperature rising rate of 5℃ and kept for 14h, then cooled to 80℃ to discharge, and the microsphere embryo is formed by heat-driven self-assembly; vacuum filtration is performed and the product is washed with 80℃ deionized water for 5 times to obtain a hydrothermal product;

[0046] Step 3, the hydrothermal product was first heated to 300℃ at a heating rate of 5℃ under nitrogen atmosphere (200mL / min) for 1h to remove the combined water; then heated to 750℃ at a heating rate of 3℃ for 2h to carbonize / activate; after cooling to room temperature, the product was washed with deionized water to remove sodium chloride template until the conductivity of the filtrate was <10μS / cm; vacuum dried at 80℃ for 12h to obtain nitrogen and phosphorus co-doped porous carbon microspheres;

[0047] Step 4, 120 parts of the nitrogen and phosphorus co-doped porous carbon microspheres obtained in step 3 were added to a quartz tube (diameter 50mm) together with 85 parts of red phosphorus, vacuumed to 10 -3 Pa, leaving 33% expansion space; loaded with gas in stages, stage 1, heated to 416℃ at a rate of 10℃ / min, and kept for 4h; stage 2, cooled to 260℃ at a rate of 5℃ / min, and kept for 8h; stage 3, cooled to 55℃ in the furnace and then broken vacuum to obtain red phosphorus loaded carbon microspheres;

[0048] Step 5, 120 parts of the red phosphorus loaded carbon microspheres obtained in step 4 were mixed with 16 parts of silicon nanoparticles and 5.5 parts of dextrin in 250 parts of ethanol medium for ball milling at a speed of 350 rpm for 3h; then the dextrin was heat cured to form microspheres after spray drying, and the control conditions for spray drying were inlet temperature 190℃, outlet 80℃, and powder particle size 8-15μm; the composite particles were placed in a CVD furnace, and acetylene (20mL / min) and nitrogen (200mL / min) were introduced, and treated at 660℃ for 1.2h to deposit a carbon layer with a thickness of about 5nm to obtain a phosphorus doped porous carbon / silicon composite anode material.

[0049] Example 3

[0050] A phosphorus doped porous carbon / silicon composite anode material, the preparation steps of which comprise:

[0051] Step 1, 110 parts of dextrin were added to 350 parts of deionized water to form a homogeneous solution by stirring at a speed of 300rpm until transparent; 65 parts of a 55% phytic acid solution were added, heated to 60℃, and reacted for 35min to construct a hydrogen bond crosslinking network; 45 parts of melamine were introduced, heated to 85℃, and stirred for 1.5h until completely dissolved; 160 parts of sodium chloride were added, stirred at a speed of 5500rpm for 10min, and high-speed shearing dispersion was performed to obtain a mixed solution;

[0052] Step 2, the mixed solution obtained in step 1 was transferred to a reaction kettle, the filling degree was 68%, and the temperature was raised to 225℃ at a heating rate of 5℃ for 12h; then the temperature was cooled to 80℃ to discharge the material, and a microsphere embryo was formed by heat-driven self-assembly; vacuum filtration was performed, and the hydrothermal product was washed with 80℃ deionized water for 4 times to obtain the product;

[0053] Step 3, the hydrothermal product was first heated to 300℃ at a heating rate of 5℃ under nitrogen atmosphere (200mL / min) for 1h to remove the combined water; then heated to 750℃ at a heating rate of 3℃ for 2h to carbonize / activate; after cooling to room temperature, the sodium chloride template was removed by washing with deionized water until the conductivity of the filtrate was <10μS / cm; vacuum dried at 80℃ for 12h to obtain nitrogen and phosphorus co-doped porous carbon microspheres;

[0054] Step 4, 110 parts of the nitrogen and phosphorus co-doped porous carbon microspheres obtained in step 3 were added to a quartz tube (diameter 50mm) together with 85 parts of red phosphorus, vacuumed to 10 -3 Pa, leaving 30% expansion space; loaded with gas in stages, stage 1, heated to 416℃ at a rate of 10℃ / min and kept for 4h; stage 2, cooled to 260℃ at a rate of 5℃ / min and kept for 8h; stage 3, cooled to 55℃ in the furnace and then broken vacuum to obtain red phosphorus-loaded carbon microspheres;

[0055] Step 5, 110 parts of the red phosphorus-loaded carbon microspheres obtained in step 4 were mixed with 15 parts of silicon nanoparticles and 5 parts of dextrin in 230 parts of an ethanol medium and ball-milled at a speed of 350 rpm for 3h; then spray-dried to form microspheres of composite particles after thermal curing of the dextrin, with the spray-drying control conditions being an inlet temperature of 185℃, an outlet temperature of 75℃, and a powder particle size of 8-15μm; the composite particles were placed in a CVD furnace and passed through acetylene (20mL / min) and nitrogen (200mL / min) at 650℃ for 1h to deposit a carbon layer with a thickness of about 5nm to obtain a phosphorus-doped porous carbon / silicon composite anode material.

[0056] Comparative Example 1

[0057] An anode material, the preparation steps of which include: mixing 85 parts of red phosphorus with 15 parts of silicon nanoparticles and 5 parts of dextrin in 230 parts of an ethanol medium and ball-milling at a speed of 350 rpm for 3h; then spray-drying to form microspheres of composite particles after thermal curing of the dextrin, with the spray-drying control conditions being an inlet temperature of 185℃, an outlet temperature of 75℃, and a powder particle size of 8-15μm; placing the composite particles in a CVD furnace and passing through acetylene (20mL / min) and nitrogen (200mL / min) at 650℃ for 1h to deposit a carbon layer with a thickness of about 5nm to obtain a phosphorus-doped porous carbon / silicon composite anode material.

[0058] The anode materials obtained in Examples 1-3 and Comparative Example 1 were applied to batteries for performance testing.

[0059] Battery assembly: the negative electrode material, conductive agent (SP), CMC and SBR are mixed in a mass ratio of 95:1.5:1.5:2, coated on a copper foil to obtain a negative electrode sheet. The positive electrode active material lithium cobaltate, conductive agent (SP) and PVDF are mixed in a mass ratio of 96.5:2:1.5, coated on an aluminum foil to obtain a positive electrode sheet. The electrolyte is 1 mol / L LiPF6+EC+EMC, and the separator is a polyethylene / propylene composite microporous membrane. They are assembled into batteries, and the electrochemical performance test of each group of batteries is carried out on a Wuhan Lan electric CT2001A battery tester.

[0060] The electrochemical performance test results are shown in the following Table 1:

[0061] Table 1

[0062] Performance sample Initial discharge specific capacity, mAh / g Initial coulombic efficiency Capacity retention after 1 C cycling for 1000 cycles 5C rate capacity (vs. 0.1 C) Example 1 1508 83% 80% 75% Example 2 1479 82% 80% 77% Example 3 1493 83% 81% 75% Comparative Example 1 1332 74% 6% 11%

[0063] According to the test results in the above table, although the first discharge specific capacity of Examples 1-3 is lower than that of Comparative Example 1, it is found that the stability and life of the batteries of Examples 1-3 are longer in the subsequent tests.

[0064] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a phosphorus-doped porous carbon / silicon composite negative electrode material, characterized in that, The steps include: Step 1, 100-120 parts by mass of dextrin is added to 300-400 parts of deionized water to configure a homogeneous solution; 60-65 parts of phytic acid solution is added, and the temperature is raised to 55-65 DEG C, and reacted for 30-40 min to build a hydrogen bond crosslinking network; 40-45 parts of melamine is introduced to control the conditional dissolution; 150-170 parts of sodium chloride is added to control the conditional dispersion, and a mixed solution is obtained; Step 2, the mixed solution obtained in step 1 is transferred to a reaction kettle, and the microsphere embryo is formed by heat-driven self-assembly under the control condition, and the hydrothermal product is obtained after filtration and washing; Step 3, the hydrothermal product is carbonized under nitrogen atmosphere, and after cooling, the sodium chloride template is removed by washing, and vacuum drying is performed to obtain nitrogen and phosphorus co-doped porous carbon microspheres; Step 4, 100-120 parts of the nitrogen and phosphorus co-doped porous carbon microspheres obtained in step 3 are added to a quartz tube together with 80-85 parts of red phosphorus, and the quartz tube is vacuum sealed, and the red phosphorus loaded carbon microspheres are obtained by controlling the conditions to load the red phosphorus in the carbon microspheres in stages in the gas phase; Step 5, 100-120 parts of the red phosphorus loaded carbon microspheres obtained in step 4 are mixed with 15-16 parts of silicon nanoparticles and 5-5.5 parts of dextrin in 200-250 parts of ethanol medium, and ball milling is performed, and after spray drying, the dextrin is heat cured to form microsphere level composite particles, and the composite particles are subjected to gas phase carbon coating to obtain a phosphorus doped porous carbon / silicon composite negative electrode material.

2. The production method according to claim 1, characterized by, The phytic acid solution in step 1 is a 50%-55% by mass phytic acid aqueous solution.

3. The preparation method according to claim 1, characterized in that, After adding melamine in step 1, the temperature is raised to 80-85 DEG C and stirred for 1-1.5 h until completely dissolved; after adding sodium chloride, the stirring rate is controlled at 5000-6000 rpm, and stirring is performed for 10-15 min until completely dispersed.

4. The method of claim 1, wherein, In step 2, when the mixed solution is transferred to the reaction kettle, the filling degree is controlled to be ≤70%; the temperature is raised to 220-230 DEG C at a rate of 5 DEG C, and the temperature is maintained for 12-14 h, and then cooled to 80 DEG C to discharge, vacuum filtration, and washing with 80 DEG C deionized water for 3-5 times.

5. The preparation method according to claim 1, characterized in that, In step 3, the temperature rising carbonization process is gradient temperature rising, first raised to 300 DEG C at a rate of 5 DEG C, and maintained for 1 h, then raised to 750 DEG C at a rate of 3 DEG C, and maintained for 2 h; after cooling to room temperature, the sodium chloride template is removed by washing with deionized water; the temperature of the vacuum drying process is controlled at 80 DEG C, and the drying is performed for 12 h.

6. The method of claim 1, wherein, The process of loading in stages in the gas phase in step 4 includes: stage 1, raised to 416 DEG C at a rate of 10 DEG C / min, and maintained for 4 h; stage 2, reduced to 260 DEG C at a rate of 5 DEG C / min, and maintained for 8 h; stage 3, the furnace is cooled to <60 DEG C, and then the vacuum is broken.

7. The preparation method according to claim 1, characterized in that, In step 4, when the quartz tube is sealed, 30%-33% of the expansion space of the tube length is reserved.

8. The method of claim 1, wherein, In step 5, the spray drying control conditions are: the inlet temperature is 180-190 DEG C, the outlet is 70-80 DEG C, and the powder particle size is 8-15 μm.

9. The method of claim 1, wherein, In step 5, the gas phase carbon coating control conditions are: the carbon source is selected from acetylene, the temperature is 650-660 DEG C, and the treatment is performed for 1-1.2 h.

10. A phosphorous doped porous carbon / silicon composite negative electrode material, characterized in that, The preparation method is prepared by using any one of claims 1-9.