A silicon-carbon anode material based on spherical phenolic resin and its preparation method

Abstract

This invention belongs to the field of battery technology, and particularly relates to a silicon-carbon anode material based on spherical phenolic resin and its preparation method. The steps include: mixing phenolic monomers, aldehyde monomers, an alkaline catalyst, and a pore-forming agent in deionized water to form an aqueous phase; adding an oil phase containing oil monomers and an emulsifier to the aqueous phase to perform a reverse emulsion polycondensation reaction; and curing to obtain spherical phenolic resin. The spherical phenolic resin is then pre-oxidized by heating, followed by carbonization in an inert atmosphere. After cooling, it is impregnated with an activator for gradient activation to obtain spherical porous carbon. The spherical porous carbon is degassed under vacuum and placed in a chemical vapor deposition reaction chamber. After heating, a silicon source gas is introduced to perform a deposition reaction, obtaining a deposition precursor. A carbon source and a nitrogen source are coated onto the surface of the deposition precursor, and after a high-temperature reaction, a silicon-carbon anode material based on spherical phenolic resin is obtained. This effectively solves the problems of cycle degradation and rate performance decline.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, and particularly relates to a silicon-carbon anode material based on spherical phenolic resin and its preparation method. Background Technology

[0002] With the rise of the Internet of Things, smart homes and smart devices require long battery life and large storage capacity, while mobile phones, smart wearables and other devices need to be thin and light, and also require lithium-ion batteries with high compaction and low expansion performance. Therefore, the performance requirements for lithium-ion battery-related materials are becoming increasingly stringent. In order to meet the demand for high capacity, given that the specific capacity of the positive and negative electrodes cannot be increased, cell manufacturers can only increase the lamination thickness by reducing the thickness of the relevant roll materials, thereby increasing the specific capacity per unit weight. The roll materials include current collectors (copper foil, aluminum foil) and separators. However, the thinner the thickness of both, the weaker the resistance to the risk of sharp punctures of the relevant materials. Therefore, for the negative electrode, especially the porous silicon carbon, the specific morphology requirements are: no sharp corners, smooth, and arc-shaped morphology. Similar materials in the industry are graphite anode materials. Because they are relatively soft and solid, they can be shaped by crushing and rounding to reduce sharp angles. Porous silicon carbon, on the other hand, is a hard and brittle material that is difficult to round. Even porous carbon materials are hard, light and brittle, so it is difficult to obtain spherical porous carbon through post-processing. Spherical or near-spherical porous carbon needs to be obtained from pre-processing.

[0003] Porous silicon-carbon anode materials utilize porous carbon as a carrier, depositing a silicon source into the pores of the porous carbon under specific temperature and pressure conditions. Porous carbon primarily consists of micropores and mesopores. The deposited silicon is separated by these pores, resulting in the absence of large silicon particles and low expansion stress. Furthermore, the porous structure of the carbon provides space for silicon expansion. Therefore, porous silicon-carbon anode materials exhibit excellent anti-expansion properties and long cycle performance, making them widely considered one of the most promising battery anode materials for the future. Porous carbon is the core material of porous silicon-carbon anode materials; its morphology, composition, and pore structure significantly influence the performance of these products.

[0004] Currently, most porous carbon is irregularly shaped or spherical, which presents three problems:

[0005] (1) Blocky porous carbon has sharp corners, which will be crushed or punctured during the compaction process, resulting in internal micro short circuits and affecting the voltage and capacity of the cell; (2) Perfect spherical porous carbon has point-to-point lithium ion conduction, poor rate performance, and the arc surface will cause the glue to detach during the cyclic expansion and contraction process, resulting in severe cycle drop phenomenon; (3) Existing porous carbon is mainly composed of disordered micropores. After the deposition of silicon nanoparticles, a large number of silicon-carbon interfaces are brought about, which hinder and block the lithium ion transport channels. Lithium ion transport needs to cross the silicon-carbon interface, which is not conducive to the dynamic performance of the battery. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a silicon-carbon anode material based on spherical phenolic resin and its preparation method, aiming to solve the problem that spherical or blocky porous carbon is easily mechanically broken and ion transport is hindered, which in turn leads to cycle decay and a decrease in rate performance.

[0007] To solve the above-mentioned technical problems, the present invention provides a method for preparing a silicon-carbon anode material based on a spherical phenolic resin, comprising the following steps:

[0008] S1. Phenolic monomers, aldehyde monomers, alkaline catalysts and pore-forming agents are mixed in deionized water to form an aqueous phase. Then, an oil phase containing oil monomers and emulsifiers is added to the aqueous phase to carry out a reverse emulsion polycondensation reaction. After curing, spherical phenolic resin is obtained.

[0009] S2. After heating the spherical phenolic resin, it is pre-oxidized, then heated in an inert atmosphere to carry out a carbonization reaction. After cooling, it is impregnated in an activator for gradient activation treatment to obtain spherical porous carbon. The gradient activation treatment is a treatment method using segmented temperature or segmented impregnation.

[0010] S3. After degassing the spherical porous carbon under vacuum, it is placed in a chemical vapor deposition reaction chamber, heated, and then a silicon source gas is introduced to carry out a deposition reaction to obtain a deposition precursor. A carbon source and a nitrogen source are coated on the outer surface of the deposition precursor. After high-temperature reaction, a silicon-carbon anode material based on spherical phenolic resin is obtained. The outer surface of the silicon-carbon anode material is a nitrogen-doped soft carbon layer.

[0011] In some embodiments, step S1 includes:

[0012] S1.1 Add phenolic monomers to a reaction vessel equipped with a mechanical stirrer, thermometer and condenser, add aldehyde monomers corresponding to the phenolic monomers in a molar ratio of (1.5 to 2.5):1, and then add an alkaline catalyst equivalent to 15 to 25 wt% of the phenolic monomers. Stir and react at 60 to 75°C for 1.5 to 2.5 h to obtain phenolic prepolymer resin liquid.

[0013] S1.2 Add 50-80 wt% of phenolic prepolymer resin liquid to a pore-forming agent and 400-600 wt% of deionized water, and stir at 300-600 rpm for 30-60 min at room temperature to obtain an aqueous phase.

[0014] S1.3 Add an emulsifier equivalent to 0.1 to 0.3 wt% of the oil monomer to the oil monomer, and perform high-speed shearing at 6000 to 10000 rpm for 5 to 15 min to obtain the oil phase;

[0015] S1.4. The aqueous phase is dripped into the oil phase over 5 to 20 minutes, and then sheared at high speed at 6000 to 10000 rpm for 5 to 20 minutes. The mixture is then sonicated in an ultrasonic device with a power of 800 to 2000 W for 20 to 90 minutes to obtain a homogeneous reverse emulsion.

[0016] S1.5. Add hydrochloric acid to the homogeneous reverse emulsion to adjust the pH to 1.5-2.5, heat to 130-150℃ and let stand for 12-30 hours to carry out polycondensation and curing to obtain spherical phenolic resin microspheres. Wash with deionized water and ethanol until neutral, and dry at 80-120℃ for 8-12 hours to obtain spherical phenolic resin.

[0017] In some embodiments, in step S1, the phenolic monomers include at least one of phenol, resorcinol, hydroquinone, catechol, m-cresol, p-cresol, bisphenol A, and bisphenol F; the aldehyde monomers include at least one of formaldehyde, glutaraldehyde, furfural, acetaldehyde, and propionaldehyde; the alkaline catalyst includes at least one of NaOH, ethylenediamine, triethanolamine, triethylamine, aniline, and ammonia; the porogen includes at least one of block polyether, F127, and P123; the emulsifier includes at least one of Span 80, Span 60, glyceryl monostearate, and diglyceryl oleate; and the oil monomers include at least one of castor oil, mineral oil, paraffin oil, and vegetable oil.

[0018] In some embodiments, step S2 includes:

[0019] S2.1. The spherical phenolic resin is heated to 200-300℃ in air at a heating rate of 1-3℃ / min and held for 1-4h to obtain a pre-oxidized spherical phenolic resin precursor.

[0020] S2.2 Transfer the pre-oxidized spheroidal phenolic resin precursor into a tube furnace, introduce nitrogen or argon at a flow rate of 50-200 mL / min to establish an inert protective atmosphere, heat to 600-800℃ at a heating rate of 2-5℃ / min, hold for 1-3 hours to carry out the carbonization reaction, and obtain spheroidal hard carbon material.

[0021] S2.3 After cooling the spherical hard carbon material to room temperature, add it to an activator with a mass fraction of 5-15 wt% of the spherical hard carbon material. Impregnate at room temperature to 40°C for 0.5-2 hours. Then filter out the impregnated spherical hard carbon material and dry it at 80-120°C for 4-8 hours to obtain pre-impregnated hard carbon. Then place the pre-impregnated hard carbon in a tube furnace and heat it to 650-750°C at a heating rate of 2-5°C / min under nitrogen or argon protection. Hold it at this temperature for 0.5-1.5 hours to carry out the first stage of medium-temperature activation to obtain semi-activated spherical carbon material.

[0022] S2.4 After cooling the semi-activated spherical carbon material to room temperature, it is added again to an activator with a mass fraction of 1-5 wt% of the spherical hard carbon material. The mixture is impregnated at 25-40℃ for 2-6 hours, then dried at 80-120℃ for 4-8 hours. Under nitrogen or argon protection, the temperature is increased to 800-850℃ at 2-3℃ / min, and carbon dioxide or water vapor is introduced for gas-assisted activation. The temperature is maintained for 0.5-1.5 hours to obtain the spherical porous carbon material preproduct.

[0023] S2.5. Take out the preproduct of the spheroidal porous carbon material, add it to dilute hydrochloric acid or dilute nitric acid solution, soak it at room temperature for 0.5 to 2 hours, then wash it repeatedly with deionized water until the pH of the filtrate is close to neutral, and then dry it at 80 to 120°C for 8 to 12 hours to obtain spheroidal porous carbon.

[0024] In some embodiments, the activator includes at least one selected from potassium hydroxide, potassium carbonate, zinc chloride, phosphoric acid, and sodium hydroxide.

[0025] In some embodiments, step S3 includes:

[0026] S3.1. The spheroidal porous carbon is placed in a quartz boat and placed in a chemical vapor deposition reaction chamber. Under a vacuum of 10-100 Pa, the temperature is increased to 150-250°C at a heating rate of 1-3°C / min and held for 1-3 hours to obtain a spheroidal porous carbon precursor that has undergone vacuum degassing.

[0027] S3.2. The spherical porous carbon precursor, which has been degassed under vacuum, is kept in the chemical vapor deposition reaction chamber and heated to 350-450°C at a heating rate of 2-5°C / min under the protection of argon or argon / hydrogen mixed gas. The pressure is adjusted to 100-1000Pa. Then, silicon source gas with a volume fraction of 5-20 vol% in the reaction chamber is introduced and the deposition time is controlled to be 0.5-4h to carry out the vapor deposition reaction and obtain the deposition precursor.

[0028] S3.3 Add the deposition precursor to a ball mill jar, add a carbon source and a nitrogen source, and simultaneously add 300-600 wt% of an ethanol / water mixed solvent equivalent to the total solid mass. Ball mill at a stirring speed of 150-300 rpm for 1-4 h, and then dry at 80-120℃ for 8-12 h to obtain a deposition composite material coated with carbon and nitrogen precursors, wherein the mass ratio of carbon source to deposition precursor is (10-30):100, and the mass ratio of nitrogen source to deposition precursor is (5-20):100.

[0029] S3.4 Place the deposited composite material into a tube furnace and heat it to 800-1100℃ at a heating rate of 2-5℃ / min under nitrogen or argon protection. Hold it at this temperature for 1-3 hours to form a nitrogen-doped soft carbon shell and obtain a silicon-carbon anode material based on spherical phenolic resin.

[0030] In some embodiments, the silicon source gas includes at least one of silane, dichlorosilane, trichlorosilane, silicon tetrachloride, and diethylsilane; the carbon source includes at least one of glucose, sucrose, pitch, and polyvinylpyrrolidone; and the nitrogen source includes at least one of melamine, urea, and polyacrylonitrile.

[0031] In some embodiments, the process may further include the following steps between S3.3 and S3.4:

[0032] The deposited composite material was placed in a tube furnace and heated to 300–450°C at a rate of 2–5°C / min under argon protection. Then, a mixed gas containing oxygen and ammonia was introduced at a total flow rate of 50–200 mL / min for 0.5–2 h to obtain the oxygen-nitrided deposited composite material.

[0033] This invention proposes a silicon-carbon anode material based on spherical phenolic resin, which is prepared by a method described above. The silicon-carbon anode material based on spherical phenolic resin comprises spherical porous carbon, a silicon-based material filling the pores of the spherical porous carbon, and a soft carbon layer on the outer surface of the silicon-carbon anode material; wherein...

[0034] The thickness of the soft carbon layer is 1-100 nm, the silicon content in the silicon-carbon anode material is 5% to 50% by mass, the carbon content is 50% to 95% by mass, and the specific surface area of ​​the silicon-carbon anode material is less than 50 m². 2 The true density of the silicon-carbon anode material powder is 1.9 g / cm³. 3 Up to 2.4 g / cm 3 The average crush strength of 20 random single particles of silicon-carbon anode material is greater than 500 MPa, and the crush displacement deformation is >16%.

[0035] The spherical porous carbon is composed of perfect spherical porous carbon and ellipsoidal porous carbon. The parameters of the spherical porous carbon are 0.8um < Dv50 < 14um, 0.4 < span < 1.2. The proportion of the number of ellipsoidal porous carbon is 5% - 70%, and the number of perfect spherical porous carbon is 30% - 95%. The dispersion degree of the spherical particles of the spherical porous carbon > 90%. There are cylindrical straight through-holes with a diameter of 1.5 - 8nm and a length less than or equal to the particle size of the spherical porous carbon in the spherical porous carbon. The arrangement of the cylindrical straight through-holes in the porous carbon matrix is regular. The included angle between the connecting lines of two adjacent cylindrical straight through-holes is an integer multiple of 60 degrees. The distance between two adjacent straight through-holes is 5 - 10nm. The total pore volume of the straight through-holes is 0.2cc / g - 0.7cc / g. The straight through-holes are connected by irregular worm-like micropores. The ratio of the pore volume of the micropores to the pore volume of the straight through-holes is 1:1 - 9:1. The proportion of the pore volume of the spherical porous carbon with a pore size of 5nm and above is less than or equal to 10%. The average value of the crushing strength of 20 random single particles of the spherical porous carbon is greater than 300MPa, and the crushing deformation is greater than 30%. The precursor of the spherical porous carbon is spherical phenolic resin;

[0036] The spherical phenolic resin is composed of perfect spherical phenolic resin and ellipsoidal phenolic resin. The parameters of the spherical phenolic resin are 1um < Dv50 < 15um, 0.4 < span < 1.8. The proportion of the number of ellipsoidal phenolic resin is 5% - 80%, and the number of perfect spherical phenolic resin is 20% - 95%. The ratio of the shortest diameter to the longest diameter of the ellipsoidal phenolic resin ≤ 0.9, and the ratio of the shortest diameter to the longest diameter of the perfect spherical phenolic resin > 0.9. The surface of the spherical phenolic resin has spherical bulges or spherical pits or both. The number of spherical bulges or spherical pits is 2 - 200. The boundaries of the spherical bulges or spherical pits are arcs or straight lines or a mixture of arcs and straight lines. The number of straight lines or arcs of the boundaries of the spherical bulges or spherical pits is 4 - 18, the perimeter is 0.3 - 30um, and the area is 0.01um 2 - 176.7um 2 , and the distance between the boundaries forming the spherical bulges or spherical pits is 0.02um - 20um. The height of the spherical bulges is 20nm - 20um, and the depth of the spherical pits is 50nm - 10um. The nitrogen element content of the spherical phenolic resin is less than 4%, the carbon element content > 70%, the oxygen element content < 20%, and the ethanol loss rate ≤ 5%.

[0037] Compared with the prior art, the beneficial effects of a silicon-carbon anode material based on spherical phenolic resin and its preparation method in the present invention are as follows:

[0038] In step S1, the spherical phenolic resin constructed through reverse emulsion polycondensation has a perfectly round spherical shape, ensuring that the carbon skeleton obtained after subsequent carbonization has no sharp edges. This significantly reduces the risk of compaction breakage and the probability of puncturing the diaphragm, fundamentally avoiding the internal micro-short circuit problem easily caused by blocky carbon materials. In step S2, a segmented process is used to form an ordered multi-scale porous structure inside the spherical carbon material. In particular, segmented impregnation or segmented temperature activation allows micropores and mesopores to be generated in a gradient. This avoids the rate performance bottleneck caused by point-to-point lithium conduction in perfectly spherical materials and also avoids pore blockage caused by disordered microporous systems. This results in a porous carbon skeleton with good permeability and low ion diffusion resistance, providing a continuous channel for ion transport after silicon deposition. In step S3, vacuum degassing is first used to prevent residual gas in the pores from hindering uniform silicon deposition. Then, chemical vapor deposition is used to obtain a structurally complete and firmly attached silicon deposition precursor, uniformly confining silicon within the porous carbon channels and reducing large-area exposed interfaces. Meanwhile, the nitrogen-doped soft carbon layer formed by coating the surface of the deposition precursor with carbon and nitrogen sources and then treating it at high temperature can significantly improve the interfacial bonding force and prevent the spherical material from debonding and failing due to volume expansion during cycling. In addition, the conductivity of the soft carbon layer and the defect sites introduced by N doping can promote the rapid transport of electrons / ions and improve rate performance. Attached Figure Description

[0039] Figure 1 This is an optical microscope image of the spherical phenolic resin of Embodiment 1 of the present invention;

[0040] Figure 2 This is an optical microscope image of the spherical phenolic resin of Embodiment 2 of the present invention;

[0041] Figure 3 This is an optical microscope image of the spherical phenolic resin of Embodiment 3 of the present invention;

[0042] Figure 4 This is an optical microscope image of the spherical phenolic resin of Embodiment 4 of the present invention;

[0043] Figure 5 This is an optical microscope image of the spherical phenolic resin of Embodiment 5 of the present invention;

[0044] Figure 6 This is an optical microscope image of the spherical phenolic resin of Embodiment 7 of the present invention;

[0045] Figure 7 This is an optical microscope image of the spherical phenolic resin of Embodiment 10 of the present invention;

[0046] Figure 8 This is a TEM image of porous carbon in Example 7 of the present invention.

[0047] Figure 9This is a scanning electron microscope image of the spherical phenolic resin of Embodiment 1 of the present invention;

[0048] Figure 10 This is a scanning electron microscope image of the spherical phenolic resin of Embodiment 2 of the present invention;

[0049] Figure 11 This is a scanning electron microscope image of the spherical phenolic resin of Embodiment 3 of the present invention;

[0050] Figure 12 This is a scanning electron microscope image of the spherical phenolic resin of Embodiment 4 of the present invention;

[0051] Figure 13 This is a scanning electron microscope image of the spherical phenolic resin of Embodiment 5 of the present invention;

[0052] Figure 14 This is a scanning electron microscope image of the spherical phenolic resin of Embodiment 7 of the present invention;

[0053] Figure 15 This is a scanning electron microscope image of the spherical phenolic resin of Embodiment 10 of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0055] Example 1:

[0056] Preparation of spherical phenolic resin:

[0057] 70g of phenol was uniformly mixed with 120.7g of formaldehyde and 15g of NaOH and reacted at 68°C for 2 hours. 40g of the resulting resin solution was taken and mixed uniformly with 24.5g of block polyether F127 and 200g of water to obtain liquid A. 1g of Span80 and 700g of castor oil were uniformly mixed using a dispersing disc at 8000rpm to obtain liquid B. Liquid A was added to liquid B, and after high-speed shearing at 8000rpm, the mixture was ultrasonicated at 1000W for 30 minutes to form a uniformly dispersed emulsion. The pH of the emulsion was adjusted to 2 with hydrochloric acid and then left to stand in a 140°C oven for 24 hours to solidify the phenolic resin spheres suspended in the emulsion, yielding spherical phenolic resin. The median particle size D of this spherical phenolic resin was... V The spherical phenolic resin has a carbon content of 75.5%, an oxygen content of 19%, and an ethanol loss rate of 3.9%. The preparation and performance parameters of this type of spherical phenolic resin are shown in Table 1. (Note: The original text contains some formatting errors and inconsistencies. A more accurate translation would require the full context.)

[0058] Preparation of spherical porous carbon:

[0059] The obtained spherical phenolic resin was placed in an air atmosphere and heated to 250℃ at 2℃ / min and held for 2 hours to induce mild cross-linking oxidation, yielding a pre-oxidized precursor. This precursor was then transferred to a tube furnace and heated to 700℃ at 3℃ / min under nitrogen protection (100 mL / min) and held for 2 hours to obtain spherical hard carbon material. After cooling, 10 g of hard carbon was added to a 1 g potassium hydroxide (10 wt%) solution (40℃) for 1 hour of impregnation. After filtration, it was dried at 100℃ for 6 hours to obtain pre-impregnated hard carbon. This pre-impregnated hard carbon was then activated at 700℃ at 3℃ / min for 1 hour under argon atmosphere to achieve the first stage of medium-temperature activation. After cooling, it was again impregnated with a 0.3 g zinc chloride (3 wt%) solution for 4 hours, dried, heated to 820℃ at 2℃ / min, and activated by purging carbon dioxide (80 mL / min) for 1 hour to obtain a porous carbon preproduct. Finally, the preproduct was soaked in dilute hydrochloric acid for 1 hour, washed with water until neutral, and dried at 100°C for 10 hours to obtain spherical porous carbon. The preparation parameters and performance parameters of this spherical porous carbon are shown in Table 2.

[0060] Preparation of silicon-carbon anode materials based on spherical phenolic resin:

[0061] The obtained porous carbon was placed in a quartz boat and evacuated to 50 Pa. The temperature was increased to 200 °C at 2 °C / min and held for 2 hours to complete degassing. Then, an argon / hydrogen (95 / 5) mixture was introduced, the temperature was increased to 400 °C at 3 °C / min, the pressure was adjusted to 200 Pa, and 10% silane was introduced for deposition for 2 hours to obtain a silicon deposition precursor. 10 g of the deposition precursor was added to a ball mill jar, along with 2 g of glucose (20 wt%), 1 g of melamine (10 wt%), and 50 g of ethanol / water (1:1) mixed solvent. The mixture was ball-milled at 200 rpm for 2 hours and dried at 80 °C for 10 hours to obtain a carbon-nitrogen coated composite. This composite was then placed in a tube furnace and heated to 350 °C at 3 °C / min, and a mixture of oxygen (0.5 vol%) and ammonia (5 vol%) was introduced for 1 hour to form 1–3 nm SiO₂ on the silicon surface. X –N X The outer carbon source was then pyrolyzed to form a nitrogen-doped soft carbon layer under nitrogen protection at a rate of 4°C / min and held for 2 hours, resulting in the silicon-carbon anode material of Example 1. This silicon-carbon anode material was then used to fabricate a pouch cell, and the performance of this pouch cell as a lithium-ion battery was tested. The performance parameters are shown in Table 3.

[0062] Example 2:

[0063] Preparation of spheroidal phenolic resin: 70g phenol, 120.7g formaldehyde, and 5g triethylamine were uniformly mixed and reacted at 68°C for 2 hours. 40g of the resin solution was taken and mixed uniformly with 24.5g block polyether F127 and 200g water to obtain liquid A. 10g Span80 and 700g castor oil were uniformly mixed by high-speed shearing at 1500rpm using a dispersion disc to obtain liquid B. Liquid A was added to liquid B, and after high-speed shearing at 1500rpm, it was ultrasonicated in a 1000W ultrasonic machine for 30 minutes to form a uniformly dispersed emulsion. The pH of the emulsion was adjusted to 2 with hydrochloric acid and then placed in a 140°C oven for 24 hours to solidify the phenolic resin spheres suspended in the emulsion, obtaining spheroidal phenolic resin. The median particle size D of this spheroidal phenolic resin was... V The spherical phenolic resin has a carbon content of 75%, an oxygen content of 19.2%, and an ethanol loss rate of 3.8%. The preparation and performance parameters of this type of spherical phenolic resin are shown in Table 1. (Note: The original text contains some formatting errors and inconsistencies. A more accurate translation would require the full context.)

[0064] Preparation of spherical porous carbon:

[0065] The obtained resin was pre-oxidized by heating to 230℃ at 2℃ / min and holding for 3h; then carbonized by heating to 650℃ at 3℃ / min under argon at 150mL / min and holding for 2h. After cooling, 10g of hard carbon was added to 0.8g of potassium carbonate solution (8wt%) and impregnated for 1h, dried, and activated at 680℃ for 1h to obtain semi-activated carbon. Then, it was impregnated with 0.25g of phosphoric acid (2.5wt%) for 4h, dried, and activated at 830℃ with steam for 1h to obtain porous carbon preproduct. After acid washing, washing with deionized water, and drying at 100℃, porous carbon was obtained. The preparation parameters and performance parameters of this type of spherical porous carbon are shown in Table 2.

[0066] Preparation of silicon-carbon anode materials:

[0067] Porous carbon was degassed at 30 Pa and heated to 180 °C for 1.5 h; subsequently, under argon protection, the temperature was raised to 380 °C, the pressure was adjusted to 300 Pa, and 15 vol% dichlorosilane was introduced for deposition for 1.5 h to obtain a deposition precursor. 10 g of the precursor was added to 1.5 g sucrose (15 wt%), 2 g polyacrylonitrile (20 wt%), and 60 g ethanol aqueous solution, ball-milled at 250 rpm for 2 h, and then dried at 100 °C. Then, oxynitridation was performed at 320 °C with 0.3% oxygen and 8% ammonia for 1 h to form SiO₂. X –N XThe silicon-carbon anode material was then heated to 1000℃ in nitrogen and held for 1 hour to obtain nitrogen-doped soft carbon-coated silicon-carbon anode material. This silicon-carbon anode material was then used to fabricate a pouch cell, and the pouch cell was subjected to lithium-ion battery performance tests. The performance parameters are shown in Table 3.

[0068] Example 3:

[0069] Preparation of spherical phenolic resin: 70g phenol, 181.5g formaldehyde, and 10g 25% ammonia were uniformly mixed and reacted at 68℃ for 2h. 40g of the resin solution was taken and mixed with 18.9g block polyether F127 and 200g water to form liquid A. 5g Span80 and 700g castor oil were mixed by high-speed shearing at 5000rpm through a dispersing disc to form liquid B. Liquid A was added to liquid B, and after high-speed shearing through an emulsifying head, it was ultrasonicated in a high-power ultrasonic machine (above 1000W) for at least 1h to form a uniformly dispersed emulsion. The emulsion was then placed in a 120℃ oven for 30h to solidify the suspended phenolic resin spheres, yielding spherical phenolic resin. Its median particle size D... V The resin has a diameter of 7.14 μm (50), a span of 1.092, and an ellipsoidal proportion of 48%. The resin surface exhibits spherical pits. It contains 79.5% carbon, 18.5% oxygen, and has an ethanol loss rate of 1.2%. The preparation and performance parameters of this type of spherical phenolic resin are shown in Table 1.

[0070] Preparation of spherical porous carbon:

[0071] The aforementioned spherical phenolic resin was placed in an air atmosphere and heated to 260°C at a rate of 2°C / min, and held for 2 hours to obtain a pre-oxidized phenolic precursor. This precursor was then placed in a tube furnace, purged with nitrogen at a rate of 120 mL / min, and heated to 700°C at a rate of 3°C / min, and held for 1.5 hours to complete carbonization, yielding a spherical hard carbon material. After cooling, 10 g of the hard carbon was added to a 1 g potassium hydroxide (10 wt%) aqueous solution and impregnated at 35°C for 1.5 hours. After filtration and drying at 90°C for 5 hours, the material was then heated to 700°C at a rate of 3°C / min and held for 1 hour to complete the first stage of activation. Spherical hard carbon material was added to an aqueous solution containing boric acid or ammonium metaborate, with the amount of boron added controlled at 3 wt% of the carbon material mass. The mixture was impregnated at 80°C for 3 h to allow the boron source to fully penetrate the pore walls and the pore interface region. Subsequently, it was dried at 120°C for 8 h, and then heated to 850°C at a rate of 4°C / min under nitrogen or argon protection and held for 1.5 h to allow the boron source to be converted in situ into B–C or B–O–C structural units, resulting in boron-doped spherical hard carbon with lightly boron-doped pore walls and both high strength and high defect activity sites. After cooling, it was impregnated with 0.4 g of zinc chloride (4 wt%) solution for 4 h, dried at 100°C, and then heated to 830°C at a rate of 2°C / min. Carbon dioxide was introduced (80 mL / min) for 1 h to activate the pre-product, yielding a porous carbon. The pre-product was soaked in dilute hydrochloric acid for 1 h, washed with water until neutral, and dried at 100°C for 10 h to obtain spherical porous carbon. The preparation parameters and performance parameters of this type of spherical porous carbon are shown in Table 2.

[0072] Preparation of silicon-carbon composite anode materials:

[0073] Spherical porous carbon was placed in a quartz boat and degassed by heating to 200°C at 2°C / min under a vacuum of 20 Pa and holding for 2 h. Then, under argon protection (200 mL / min), the temperature was increased to 380°C at 3°C / min, the pressure was adjusted to 200 Pa, and 10 vol% silane was introduced for deposition for 1.5 h to obtain a silicon deposition precursor. Subsequently, 10 g of the precursor was taken, and 2 g of glucose (20 wt%) and 1 g of urea (10 wt%) were added, along with 50 g of ethanol / water (1:1) mixed solvent. The mixture was ball-milled at 250 rpm for 2 h and then dried at 80°C for 10 h to obtain a carbon-nitrogen coated composite material. This composite material was placed in a tube furnace and heated to 350°C at 2°C / min, and treated with a mixed gas of 1 vol% oxygen and 5 vol% ammonia for 1 h to form SiO₂ on the silicon surface at approximately 1–3 nm. X –N X Interface layer. Nitrogen gas was then introduced, and the temperature was increased to 900℃ at 4℃ / min and held for 2 hours to pyrolyze the carbon source, forming a nitrogen-doped soft carbon shell, thus obtaining the silicon-carbon anode material of Example 3. This silicon-carbon anode material was used to fabricate a pouch cell, and the pouch cell was subjected to lithium-ion battery performance tests. The performance parameters are shown in Table 3.

[0074] Example 4:

[0075] Preparation of spherical phenolic resin:

[0076] 70g of phenol was mixed with 181.5g of formaldehyde and 15g of NaOH and reacted at 68℃ for 2 hours. 40g of the resin solution was mixed with 9.5g of F127 and 200g of water to form solution A. 5g of Span80 and 700g of castor oil were sheared at 5000rpm to form solution B. Solution A was added to solution B and sheared at high speed, then sonicated at 1000W for at least 1 hour. After adjusting the pH to 2, the mixture was allowed to stand at 120℃ for 30 hours to cure, yielding a spherical phenolic resin (D). V (50=7.86μm, Span=0.947). The resin surface has spherical pits. The preparation parameters and performance parameters of this type of spherical phenolic resin are shown in Table 1.

[0077] Preparation of spherical porous carbon:

[0078] The obtained phenolic resin was pre-oxidized by heating to 240℃ at 2℃ / min and holding for 3h; then carbonized by heating to 650℃ at 3℃ / min under argon at 150mL / min and holding for 1.5h. After cooling, 10g of hard carbon was impregnated in 1.2g of potassium hydroxide solution (12wt%) for 1h and dried at 100℃, then heated to 700℃ at 3℃ / min and held for 1h to obtain semi-activated carbon. Subsequently, 0.3g of phosphoric acid (3wt%) was added and impregnated for 3h, dried at 90℃, heated to 820℃ and purged with steam for 1h to obtain porous carbon preproduct. After acid washing, it was dried at 110℃ for 10h to obtain spherical porous carbon. The preparation parameters and performance parameters of this spherical porous carbon are shown in Table 2.

[0079] Preparation of silicon-carbon anode materials:

[0080] Spherical porous carbon was degassed at 30 Pa and heated to 180 °C for 2 h. Then, it was heated to 400 °C with argon gas, pressurized to 300 Pa, and deposited with 15 vol% trichlorosilane for 2 h to obtain a silicon deposition precursor. 10 g of the precursor was mixed with 3 g of pitch (30 wt%) and 1.5 g of melamine (15 wt%), and 60 g of ethanol-water solvent was added. The mixture was ball-milled at 200 rpm for 2 h and dried at 100 °C to obtain a carbon-nitrogen coating composite. Then, it was heated to 380 °C at 3 °C / min and treated with 0.5 vol% oxygen + 8 vol% ammonia gas for 1 h to form 1–3 nm SiO₂. X –N X The layers were then heated to 950℃ at a rate of 4℃ / min and held for 2 hours under argon protection to obtain the silicon-carbon anode material of Example 4. This silicon-carbon anode material was then used to fabricate a pouch cell, and the pouch cell was subjected to lithium-ion battery performance tests. The performance parameters are shown in Table 3.

[0081] Example 5:

[0082] Preparation of spherical phenolic resin:

[0083] 70g of phenol, 96.6g of formaldehyde, and 5g of triethylamine were uniformly mixed and reacted at 68℃ for 2 hours. 40g of the resulting resin solution was taken and mixed uniformly with 27.7g of block polyether F127 and 200g of water to obtain solution A. 5g of Span80 and 700g of castor oil were mixed by high-speed shearing at 5000rpm using a dispersing disc to obtain solution B. Solution A was added to solution B, and after high-speed shearing through an emulsifying head, the mixture was ultrasonically sonicated in a high-power ultrasonic machine (1000W or higher) for at least 1 hour to form a uniformly dispersed emulsion. The pH was adjusted to 2 with hydrochloric acid, and the emulsion was left to stand in a 120℃ oven for 30 hours to solidify the phenolic resin spheres suspended in the emulsion, yielding spherical phenolic resin. Its median particle size D... V The resin has a diameter of 6.45 μm, a span of 0.897, and an ellipsoidal proportion of 41%. The resin surface exhibits spherical pits. It contains 73.1% carbon, 18.2% oxygen, and has an ethanol loss rate of 5.6%. The preparation and performance parameters of this type of spherical phenolic resin are shown in Table 1.

[0084] Preparation of spherical porous carbon:

[0085] The obtained phenolic resin was placed in air and heated to 240℃ at 2℃ / min and held for 2 hours to undergo pre-oxidation, yielding a pre-oxidized phenolic precursor. This precursor was then placed in a tube furnace under nitrogen protection at 100 mL / min, and heated to 650℃ at 3℃ / min and held for 2 hours to complete the carbonization reaction, yielding a spherical hard carbon material. After cooling, 10 g of hard carbon was weighed and added to a 1.0 g potassium carbonate (10 wt%) solution, impregnated at 35℃ for 1 hour, filtered, and dried at 100℃ for 6 hours. The mixture was then heated to 680℃ at 3℃ / min and held for 1 hour to obtain a semi-activated carbon material. This semi-activated material was then impregnated in a 0.3 g zinc chloride (3 wt%) solution for 4 hours, dried at 90℃, and activated at 830℃ at 2℃ / min with carbon dioxide at 70 mL / min for 1 hour. Finally, the preproduct was soaked in dilute nitric acid solution for 1 hour, washed with water until neutral, and then dried at 100℃ for 10 hours to obtain spherical porous carbon. The preparation parameters and performance parameters of this type of spherical porous carbon are shown in Table 2.

[0086] Preparation of silicon-carbon anode materials:

[0087] Spherical porous carbon was placed in a quartz boat, degassed at 30 Pa, and heated to 200 °C at 2 °C / min and held for 2 h to obtain a fully degassed porous carbon precursor. Subsequently, under argon protection, the temperature was increased to 400 °C at 3 °C / min, the pressure was adjusted to 300 Pa, and 12 vol% dichlorosilane was introduced for deposition for 2 h to obtain a silicon deposition precursor. 10 g of the deposition precursor was added to 2.5 g of sucrose (25 wt%), 1 g of polyacrylonitrile (10 wt%), and 60 g of ethanol / water (1:1) mixed solvent, and ball-milled at 200 rpm for 2 h, followed by drying at 90 °C for 8 h to obtain a carbon-nitrogen coated composite material. This composite material was placed in a tube furnace, heated to 350 °C at 2 °C / min, and reacted for 1 h with a mixed gas of 0.5 vol% oxygen and 8 vol% ammonia to form 1–3 nm SiO₂. X –N X The composite material of the layer was then used. Finally, under nitrogen protection, the temperature was increased to 950℃ at 4℃ / min and held for 2 hours to pyrolyze the carbon source and form a nitrogen-doped soft carbon shell, thus obtaining the silicon-carbon anode material of Example 5. This silicon-carbon anode material was used to make a pouch cell, and the performance of the pouch cell as a lithium-ion battery was tested. The performance parameters are shown in Table 3.

[0088] Example 6

[0089] Preparation of phenolic resin: 70g phenol, 96.6g formaldehyde, and 15g NaOH were uniformly mixed and reacted at 68℃ for 2h. 40g of the resin solution was taken and mixed uniformly with 27.7g block polyether F127 and 200g water to obtain liquid A. 5g Span80 and 700g castor oil were uniformly mixed by high-speed shearing at 5000rpm through a dispersing disc to obtain liquid B. Liquid A was added to liquid B, and after high-speed shearing through an emulsifying head, the pH was adjusted to 2 with hydrochloric acid. The emulsion was then placed in a 120℃ oven for 30h to obtain millimeter-sized yellow phenolic resin particles. The carbon content was 74.1%, the oxygen content was 19.1%, and the ethanol loss rate was 5.4%. The preparation parameters and performance parameters of this type of spherical phenolic resin are shown in Table 1.

[0090] Preparation of porous carbon:

[0091] The phenolic resin was pre-oxidized by heating to 250℃ at 2℃ / min and holding for 2h to obtain pre-oxidized particles. These particles were then placed in nitrogen at 120mL / min and heated to 700℃ at 3℃ / min for 2h to obtain spherical hard carbon. After cooling, 10g of hard carbon was impregnated in a 1.2g sodium hydroxide (12wt%) solution for 1h, dried at 100℃, and then activated at 700℃ at 3℃ / min for 1h to obtain semi-activated carbon. Next, 0.5g zinc chloride (5wt%) was added and impregnated for 4h, dried at 100℃, and then activated at 830℃ with carbon dioxide purging at 60mL / min for 1h. After acid washing, washing, and drying, spherical porous carbon was obtained. The preparation parameters and performance parameters of this porous carbon are shown in Table 2.

[0092] Preparation of silicon-carbon anode materials:

[0093] The spherical porous carbon was degassed at 40 Pa, heated to 220 °C at 2 °C / min and held for 2 h; then heated to 420 °C under an argon / hydrogen atmosphere (95 / 5), and after adjusting the pressure to 200 Pa, 10 vol% trichlorosilane was introduced for deposition for 1.5 h. 10 g of the deposition precursor was added to 3 g of glucose (30 wt%), 1.5 g of urea (15 wt%), and 55 g of ethanol / water solvent, and ball-milled at 250 rpm for 2 h, followed by drying at 90 °C for 10 h. The dried material was then heated to 370 °C at 3 °C / min and treated with 0.3 vol% oxygen + 10 vol% ammonia for 1 h to form SiO₂. X –N X Interface layer. Finally, the temperature was raised to 1000℃ under nitrogen protection and held for 2 hours to allow the carbon source to pyrolyze and form a nitrogen-doped soft carbon layer, obtaining the silicon-carbon anode material of Example 6. This silicon-carbon anode material was used to fabricate a pouch cell, and the performance of the pouch cell as a lithium-ion battery was tested. The performance parameters are shown in Table 3.

[0094] Example 7

[0095] Preparation of spherical phenolic resin:

[0096] 70g of phenol was uniformly mixed with 181.5g of formaldehyde and 15g of NaOH and reacted at 68℃ for 2 hours. 40g of the resulting resin solution was taken and mixed with 9.5g of block polyether P123 and 200g of water to form solution A. 5g of Span80 and 700g of castor oil were mixed by high-speed shearing at 5000rpm using a dispersing disc to form solution B. Solution A was added to solution B, and after high-speed shearing through an emulsifying head, the mixture was ultrasonically sonicated in a high-power ultrasonic machine (1000W or higher) for at least 1 hour to form a uniformly dispersed emulsion. The pH was adjusted to 2 with hydrochloric acid, and the emulsion was left to stand in a 120℃ oven for 30 hours to solidify the phenolic resin spheres. The median particle size D of this type of spherical phenolic resin was determined. VThe resin has a particle size of 7.85 μm, a span of 1.045, an ellipsoidal proportion of 43%, a surface with spherical pits, a carbon content of 80.2%, an oxygen content of 16.3%, and an ethanol loss rate of 1.0%. The preparation parameters and performance parameters of this type of spherical phenolic resin are shown in Table 1.

[0097] Preparation of spherical porous carbon:

[0098] First, spheroidal phenolic resin was placed in air and heated to 260℃ at a rate of 2℃ / min, then held for 2 hours to allow the molecular chains to undergo preliminary cross-linking and dehydration condensation reactions, resulting in a pre-oxidized precursor with stable structure and improved heat resistance. The pre-oxidized material was then transferred to a quartz tube furnace, where an inert atmosphere was established using nitrogen at a rate of 120 mL / min, and the temperature was increased to 700℃ at a rate of 3℃ / min, held for 2 hours to complete the pyrolysis of the phenolic resin and the formation of the graphitized precursor carbon structure, yielding spheroidal hard carbon. The carbonized spheroidal hard carbon was then placed in a tube furnace and heated to 4550℃ at a rate of 3℃ / min under an atmosphere of only carbon dioxide or water vapor, held for 1.5 hours. This caused mild physical activation and defect rearrangement on the surface of the spheroidal hard carbon, resulting in gradient pre-activated spheroidal hard carbon with enriched surface micropores and a still dense internal structure. After cooling, 10g of hard carbon was added to a 1.0g potassium hydroxide (10wt%) solution and impregnated for 1h. After filtration, it was dried at 100℃, and then heated to 680℃ at 3℃ / min and held for 1h to expand the pores from micropores to mesopores, thus obtaining a semi-activated material. Further, the semi-activated spherical carbon was added to a 0.4g zinc chloride (4wt%) solution and impregnated for 4h to adjust the defect density of the carbon framework through ion penetration. After drying, it was placed at 840℃ and activated by purging with carbon dioxide (70mL / min) for 1h to form a spherical porous carbon framework with a hierarchical pore structure. Finally, it was soaked in dilute nitric acid for 1h to remove inorganic residues, washed with water until neutral, and dried at 100℃ for 10h to obtain the spherical porous carbon material. The preparation parameters and performance parameters of this spherical porous carbon are shown in Table 2.

[0099] Preparation of silicon-carbon anode materials:

[0100] Spherical porous carbon was placed in a quartz boat, degassed under a vacuum of 40 Pa, and heated to 200 °C at a rate of 2 °C / min, holding for 2 h to remove weakly adsorbed substances within the pores. Subsequently, under argon protection, the temperature was raised to 420 °C, adjusted to 200 Pa, and 10 vol% trichlorosilane was introduced for in-situ chemical vapor deposition of the porous carbon for 1.8 h. Silicon was deposited confined within the pores and on the surface, yielding a silicon deposition precursor. 10 g of the precursor was mixed with 3 g of glucose (30 wt%) and 1 g of urea (10 wt%), and then 55 g of water / ethanol (1:1) solvent was added. The mixture was ball-milled for 2 h and dried at 90 °C for 8 h to obtain a carbon-nitrogen coated material. Subsequently, the temperature was raised to 360 °C at a rate of 3 °C / min, and 0.3 vol% oxygen + 10 vol% ammonia was introduced for mild oxynitriding treatment for 1 h, resulting in the formation of 1–3 nm SiO₂ on the silicon surface. X –N X Interface layer. Finally, the temperature was raised to 1000℃ under nitrogen protection and held for 2 hours to convert the carbon source into a continuous nitrogen-doped soft carbon layer, obtaining the silicon-carbon anode material of Example 7. The silicon-carbon anode material was used to make a pouch cell, and the performance of the pouch cell as a lithium-ion battery was tested. The performance parameters are shown in Table 3.

[0101] Example 8

[0102] Preparation of phenolic resin: 60g phenol, 10g cashew nut shell phenol, 181.5g formaldehyde, and 15g NaOH were uniformly mixed and reacted at 68℃ for 2 hours. 40g of the resin solution was taken and mixed with 9.5g block polyether P123 and 200g water to obtain liquid A. 5g Span80 and 700g castor oil were sheared and mixed at 5000rpm to obtain liquid B. Liquid A was added to liquid B, and the mixture was sheared at high speed through an emulsifying head and ultrasonicated at 1000W for 1 hour to form a stable emulsion. The emulsion was adjusted to pH=2 with hydrochloric acid and cured in a 90℃ oven for 30 hours to obtain bulk viscous phenolic resin.

[0103] Preparation of porous carbon:

[0104] Bulk viscous phenolic resin was pre-oxidized by heating to 240℃ at 1.5℃ / min and holding for 3 hours, which initiated additional cross-linking reactions in the cashew phenol side chains, improving carbonization yield and thermal stability. Subsequently, under nitrogen atmosphere (100 mL / min), the temperature was increased to 680℃ at 3℃ / min and held for 2 hours to complete the carbonization reaction, yielding a dense hard carbon framework. After cooling, 10 g of hard carbon was added to 1 g of potassium carbonate (10 wt%) for 1 hour, dried at 100℃, and activated at 700℃ at 3℃ / min for 1 hour to obtain semi-activated hard carbon. The semi-activated carbon was further immersed in 0.4 g of zinc chloride (4 wt%) solution for 4 hours; after drying at 95℃, it was activated at 830℃ at 2℃ / min with carbon dioxide (70 mL / min) for 1 hour to construct a gradient pore structure connecting micropores, mesopores, and macropores. The activator residue was then removed by soaking in dilute nitric acid, washed with water until neutral, and dried at 100℃ for 10 h to obtain spherical porous carbon. The preparation parameters and performance parameters of this spherical porous carbon are shown in Table 2.

[0105] Preparation of silicon-carbon anode materials:

[0106] Bulk porous carbon was degassed under a vacuum of 30 Pa for 2 h, and then heated to 220 °C at 2 °C / min and held for 2 h to ensure the pores were truly open. Subsequently, under argon protection, the temperature was raised to 450 °C, the pressure was adjusted to 250 Pa, and 8 vol% silane was introduced for deposition for 1 h to form a deposition precursor. 10 g of the deposition precursor was taken, and 2.5 g of sucrose (25 wt%), 1 g of urea (10 wt%), and 60 g of water / ethanol solvent were added. The mixture was ball-milled at 250 rpm for 2 h to obtain a homogeneous carbon-nitrogen coated mixture, which was then dried at 90 °C for 10 h. This composite material was then heated to 350 °C at 3 °C / min and treated with a mixed gas of 0.5 vol% oxygen and 6 vol% ammonia for 1 h to form a stable 1–3 nm SiSiO₂. X –N X Transition layer. Finally, the temperature was raised to 950℃ under nitrogen protection and held for 2 hours to decompose the sugar carbon source into a continuous nitrogen-doped soft carbon shell, obtaining the silicon-carbon anode material of Example 8. This silicon-carbon anode material was used to make a pouch cell, and the performance of the pouch cell as a lithium-ion battery was tested. The performance parameters are shown in Table 3.

[0107] Example 9

[0108] Preparation of phenolic resin: 70g phenol, 96.6g formaldehyde, and 7g triethanolamine were uniformly mixed and reacted at 68℃ for 2h. 40g of the resin solution was taken and mixed with 9.5g block polyether P123 and 200g water to form liquid A. 5g Span80 and 700g castor oil were mixed by high-speed shearing at 5000rpm through a dispersing disc to form liquid B. Liquid A was added to liquid B, and after high-speed shearing through an emulsifying head, it was ultrasonicated in an ultrasonic machine of 1000W or higher for at least 1h to form a homogeneous emulsion. After adjusting the pH to 6, it was cured in an oven at 120℃ for 30h to obtain irregular block phenolic resin with a carbon content of 73.1%, an oxygen content of 19.4%, and an ethanol loss rate of 5.8%. The preparation parameters and performance parameters of this irregular block phenolic resin are shown in Table 1.

[0109] Preparation of porous carbon:

[0110] The obtained phenolic resin was heated to 280℃ at 1.5℃ / min in air and held for 2 hours to ensure complete pre-oxidation and the formation of a heat-resistant cross-linked structure. It was then transferred to a tube furnace and heated to 720℃ at 4℃ / min under argon protection at 150mL / min and held for 1.5 hours to achieve complete carbonization, yielding hard carbon material. After cooling, 10g of hard carbon was added to a 1g potassium hydroxide (10wt%) solution and impregnated for 1 hour. After drying, it was activated at 700℃ at 3℃ / min for 1 hour to form a primary porous structure. The semi-activated carbon was then impregnated with 0.3g potassium carbonate (3wt%) for 4 hours, further adjusting the pore wall spacing using alkali ions. After drying, it was heated to 820℃ at 2℃ / min and activated with carbon dioxide at 50mL / min for 1 hour to form a hierarchical porous structure. Finally, residual activator was removed by soaking in dilute nitric acid for 1 hour, followed by washing with water until neutral and drying at 100℃ to obtain spherical porous carbon. The preparation parameters and performance parameters of this type of spherical porous carbon are shown in Table 2.

[0111] Preparation of silicon-carbon anode materials:

[0112] Porous carbon was placed in a quartz boat and degassed at 180°C for 1.5 h under a vacuum of 30 Pa at a rate of 2°C / min. Then, under argon protection, the temperature was raised to 400°C, the pressure adjusted to 180 Pa, and 12 vol% dichlorosilane was introduced for CVD for 1.5 h, allowing silicon to be directionally deposited within the pores to form a deposition precursor. 10 g of the deposition precursor was taken, and 2 g of pitch powder (20 wt%) and 1.5 g of melamine (15 wt%) were added, along with 50 g of a water / ethanol (1:1) mixed solvent. The mixture was ball-milled at 200 rpm for 2.5 h and dried at 90°C to obtain a carbon-nitrogen coated material. Subsequently, the temperature was raised to 380°C at a rate of 2.5°C / min, and a mixed gas of 0.4 vol% oxygen and 8 vol% ammonia was introduced for 1 h, causing a dense SiO2 layer to form on the silicon surface. X –N XIntermediate layer. The material is then heated to 1050℃ under nitrogen protection and held for 2 hours to convert the pitch carbon source into a flexible nitrogen-doped soft carbon shell, obtaining the silicon-carbon anode material of Example 9. This silicon-carbon anode material is used to make a pouch cell, and the performance of the pouch cell as a lithium-ion battery is tested. The performance parameters are shown in Table 3.

[0113] Example 10

[0114] Preparation of spherical phenolic resin: 70g phenol was mixed with 181.5g formaldehyde and 15g NaOH and reacted at 68℃ for 2h. 40g of the resin solution was taken and mixed with 27.7g block polyether F127 and 200g water to form liquid A. 5g Span80 and 700g castor oil were sheared at 5000rpm to form liquid B. Liquid A was added to liquid B, sheared through an emulsifying head, and sonicated at 1000W for 1h to form an emulsion. The emulsion was cured in a 120℃ oven for 30h to obtain spherical phenolic resin, D. V The 50 = 8.23 ​​μm, Span = 1.023, ellipsoidal proportions are 46%, and the surface has spherical pits. The preparation parameters and performance parameters of this type of spherical phenolic resin are shown in Table 1.

[0115] Preparation of spherical porous carbon:

[0116] The obtained phenolic resin was heated to 250℃ at 2℃ / min and held for 3 hours in air to ensure complete pre-oxidation. The material was then placed in a tube furnace under nitrogen protection at 120 mL / min and heated to 750℃ at 3℃ / min for 2 hours to form hard carbon. After cooling, 10 g of hard carbon was added to a 1.5 g zinc chloride (15 wt%) solution and impregnated for 1 hour. After drying, it was activated at 700℃ at 3℃ / min for 1 hour to obtain semi-activated carbon. Then, 0.2 g sodium hydroxide (2 wt%) was added and impregnated for 4 hours. After drying at 100℃, it was heated to 830℃ at 2℃ / min and activated with steam at 60 mL / min for 1 hour to obtain porous carbon with a rich mesoporous structure. Subsequently, it was soaked in dilute hydrochloric acid for 1 hour, washed with water until neutral, and dried at 100℃ for 10 hours. The preparation parameters and performance parameters of this type of spherical porous carbon are shown in Table 2.

[0117] Preparation of silicon-carbon anode materials:

[0118] Spherical porous carbon was deeply degassed by heating to 200℃ at 2℃ / min under a vacuum of 50 Pa and holding for 2 h. Then, under argon protection, the temperature was raised to 430℃ and the pressure adjusted to 300 Pa, followed by CVD for 1 h with 10 vol% silicon tetrachloride. Silicon was deposited inside the pores to form a deposition precursor. 10 g of the deposition precursor was mixed with 3 g of polyvinylpyrrolidone (30 wt%) and 1 g of urea (10 wt%), and then 70 g of water / ethanol (1:1) solvent was added. The mixture was ball-milled at 250 rpm for 3 h, followed by drying at 100℃ for 12 h to obtain a carbon-nitrogen coated deposition composite. This composite was then heated to 400℃ at 3℃ / min and treated with a mixed gas of 0.5 vol% oxygen and 5 vol% ammonia for 0.8 h to form 1–3 nm SiO₂. X –N X Intermediate layer. The temperature is then raised to 1100℃ under nitrogen protection and held for 1.5 hours to form a continuous and dense nitrogen-doped soft carbon shell layer on the outer layer, yielding the silicon-carbon anode material of Example 10. This silicon-carbon anode material was used to fabricate a pouch cell, and the pouch cell was subjected to lithium-ion battery performance testing. The performance parameters are shown in Table 3.

[0119] Figures 1-7 The optical microscope images of Examples 1, 2, 3, 4, 5, 7, and 10 show that the outline projections of the spheroidal phenolic resins are all a mixture of perfect spheres and ellipsoids. Figures 9-15 The scanning electron microscope (SEM) images of Examples 1, 2, 3, 4, 5, 7, and 10 show that the surface morphology of the spherical phenolic resin consists of spherical bumps or pits, or a mixture of both. The SEM images of Examples 1 and 2 further illustrate this. Figure 9 , 10 Excessively high shear rates paired with excessively low emulsifier dosage, or excessively low shear rates paired with excessively high emulsifier dosage, both result in surface morphologies dominated by spherical bulges. Moderate shear rates paired with moderate emulsifier dosage produce surface morphologies of spherical pits. This is because excessively high shear rates cause the spherical emulsion droplets to move too fast, making particle agglomeration easier, while excessively low shear rates result in higher system viscosity, leading to a greater tendency for particle agglomeration. The mixed contours of perfect spheres and ellipsoids, along with the surface morphologies of spherical bulges or pits, improve the contact problems associated with the high sphericity and smooth surface of perfect spheres prepared by traditional emulsion methods, thereby enhancing the cycle and rate performance of the battery cell.

[0120] Figure 8This is a high-resolution transmission electron microscope (TEM) image of the porous carbon material, clearly showing the regular, nearly ordered interlayer texture of graphite. The interlayer distance is approximately 0.36–0.38 nm, slightly larger than that of natural graphite, indicating that the material belongs to a mixed state of hard carbon and graphite-like structures. Local defect areas and blurred pore regions are visible in the lower part of the image. This is related to the use of a stronger activator or prolonged activation in Example 7, resulting in a certain degree of pore connectivity and disordered layer structure between the carbon sheets, which is beneficial for forming lithium-ion diffusion channels and improving rate performance.

[0121] Methods for manufacturing lithium batteries:

[0122] (1) Preparation of the positive electrode

[0123] Lithium cobalt oxide (LiCoO2), conductive carbon black, and polyvinylidene fluoride binder were mixed in a weight ratio of 95:2.5:2.5. N-methylpyrrolidone (NMP) was added and the mixture was stirred evenly under vacuum to obtain a positive electrode slurry. The positive electrode slurry was uniformly coated onto the positive electrode current collector aluminum foil. The aluminum foil was dried, and then cold-pressed, cut, and slit before being dried under vacuum to obtain the positive electrode sheet.

[0124] (2) Preparation of negative electrode

[0125] The negative electrode material, graphite, conductive agent (conductive carbon black, SuperP) and binder PAA of the above embodiments and comparative examples were mixed in a weight ratio of 70:15:5:10, deionized water was added, and a negative electrode slurry was obtained under the action of a vacuum stirrer. The negative electrode slurry was uniformly coated on the negative electrode current collector copper foil. The copper foil was dried, and then cold-pressed, cut, and slit, and dried under vacuum conditions to obtain the negative electrode sheet.

[0126] (3) Electrolyte

[0127] In a dry argon atmosphere glove box, LiPF6 is added to a solvent composed of propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) in a weight ratio of approximately 1:1:1, and mixed thoroughly. The concentration of LiPF6 is approximately 1.15 mol / L. The electrolyte is obtained by mixing thoroughly.

[0128] (4) Separating membrane

[0129] Polyethylene porous polymer film is used as the separator.

[0130] (5) Assembly of pouch batteries

[0131] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrode sheets. Then, they are wound to obtain a bare cell. After welding the tabs, the bare cell is placed in an outer packaging aluminum-plastic foil film. The prepared electrolyte is injected into the dried bare cell. After vacuum sealing, settling, formation, shaping, and capacity testing, a lithium-ion battery is obtained.

[0132] Lithium battery performance testing:

[0133] (1) Lithium-ion battery cycle performance test:

[0134] The lithium-ion battery was placed in a constant temperature chamber at 45℃ or 25℃ and left to stand for 30 minutes to reach a constant temperature. The battery was then charged at a constant current of 0.7C to a voltage of 4.4V, followed by constant voltage charging at 4.4V to a current of 0.025C. After standing for 5 minutes, it was discharged at a constant current of 0.5C to a voltage of 3.0V. The capacity obtained from this process was taken as the initial capacity. Cyclic tests were performed using 0.7C charging / 0.5C discharging. The capacity decay curve was obtained by comparing the capacity at each step with the initial capacity. The number of cycles at 25℃ until 90% capacity retention was recorded as the room temperature cycle performance, and the number of cycles at 45℃ until 80% capacity retention was recorded as the high temperature cycle performance. The cycle performance of the material was compared by comparing the number of cycles under these two conditions.

[0135] (2) Discharge rate test:

[0136] The lithium-ion battery was placed in a 25°C constant temperature chamber and left to stand for 30 minutes to reach a constant temperature. The battery was then discharged at a constant current of 0.2C to a voltage of 3.0V, left to stand for 5 minutes, charged at a constant current of 0.5C to a voltage of 4.45V, and then charged at a constant voltage of 4.45V to a current of 0.05C, left to stand for 5 minutes. The discharge rate was adjusted, and discharge tests were conducted at 0.2C, 0.5C, 1C, 1.5C, and 2.0C respectively. The discharge capacity was obtained at each rate and compared with the capacity obtained at 0.2C. The rate performance was compared by comparing the ratio of the 2C to 0.2C values.

[0137] (3) Battery full charge expansion rate test:

[0138] The thickness of a fresh battery at half charge (50% SOC) is measured using a micrometer. After 400 cycles, the battery is fully charged (100% SOC). The thickness of the battery at this time is measured again using a micrometer. By comparing the thickness of the fresh battery at the initial half charge (50% SOC), the expansion rate of the fully charged (100% SOC) battery can be obtained.

[0139] Other tests:

[0140] Sphericity test: Place the powder sample under an optical microscope and observe it. Measure the shortest diameter and the longest diameter using a manual ruler. If the ratio of the two is less than or equal to 0.9, it is classified as an ellipsoid; if it is greater than 0.9, it is classified as a perfect sphere. Randomly select more than 100 particles for measurement to determine the proportion of ellipsoidal particles in the sample.

[0141] Ethanol loss test: After thoroughly grinding and dispersing the phenolic resin powder sample, pass it through a 100-mesh sieve. Take 5g of the sample (accurate to 0.001g), mix it with 250g of ethanol, sonicate it in a 65°C water bath for 1 hour, filter the mixture, dry the remaining powder, and the mass ratio of the powder to the initial sample is the ethanol loss rate of the sample group.

[0142] Analysis of C, O, and N elements in spherical resin: The C, O, and N elements of the spherical phenolic resin sample were analyzed using an organic elemental analyzer.

[0143] HRTEM analysis of spheroidal porous carbon: After ultrasonically dispersing an anhydrous ethanol solution of ordered mesoporous carbon, the suspension was dropped onto a copper grid and allowed to air dry. The pore shape, pore distribution, and pore size of the ordered mesoporous carbon were characterized by high resolution transmission electron microscopy.

[0144] Single particle strength test: A 50μm diameter planar diamond indenter was used to determine the particle size at D. V For particles around 50, a load is applied to the particle, and the test force and compressive displacement are measured in real time until the compressive displacement no longer changes with the load. The ratio of this load to the indentation area is the compressive strength. This compressive displacement is related to D. V The ratio of 50 is the crush strain; 50 particles are selected for each test, and the average compressive strength is taken; the equipment used is a microhardness tester.

[0145] Test method for silicon content in anode materials:

[0146] Weigh 0.05 to 0.1 g of sample and add 1.2 to 1.5 g of dry potassium hydroxide. Place the sample in a muffle furnace at 400°C. After cooling, add boiling water to moisten the sample. Repeat the washing and drying process. Filter the sample solution into a 100 mL PP bottle using medium-speed filter paper and make up to volume. Then dilute the solution 100 times and test the diluted solution using ICP-OES. Calculate the silicon content of the sample.

[0147] Test method for specific surface area of ​​negative electrode material:

[0148] After measuring the amount of gas adsorbed on the solid surface at different relative pressures under constant temperature and low temperature, the monolayer adsorption capacity of the sample was calculated based on the Brownauer-Etter-Taylor adsorption theory and its formula (BET formula), thereby calculating the specific surface area of ​​the solid. Approximately 1.5 g to 3.5 g of powder sample was weighed and placed into the test sample tube of TriStarII3020, degassed at approximately 200 °C for 120 min, and then tested.

[0149] Methods for testing the true density of negative electrode materials:

[0150] Weigh a sample of a certain mass (1g to 5g) and place it in a true density analyzer. Seal the testing system and introduce helium or nitrogen gas according to the procedure. By testing the gas pressure in the sample chamber and expansion chamber, and then calculating the true volume according to Bohr's Law (PV=nRT), the true density can be calculated.

[0151] Table 1:

[0152]

[0153] Table 1 shows the differences in particle size / span, ellipsoid ratio, C / O content, and ethanol dissolution loss rate of spherical phenolic resins in different examples, used to evaluate the spheroidization process of reverse emulsions, the degree of phenolic condensation, and structural stability. This table illustrates that: First, suitable oil / water phase ratios and shear conditions (such as Examples 1, 3, 4, 5, 7, and 10) can yield highly spherical resin particles with a particle size of 6–8 μm, a span < 1.1, and an ellipsoid ratio < 50%. Deviating from suitable conditions results in millimeter-sized particles (Example 6), viscous resin lumps (Example 8), or irregular lumps (Example 9), indicating that the spheroidization window has significant process sensitivity. Second, the C / O ratio reflects the degree of condensation and network density. Examples 3, 7, and 10 have a C content of 79–80%, indicating more complete condensation, which is beneficial for subsequent carbonization to form a high carbon yield and a more regular carbon skeleton; while Examples 5 and 9 have a lower C content (73%), corresponding to insufficient condensation and a loose structure. Third, the ethanol loss rate represents the stability of the phenolic network. Examples 3, 4, 7, 8, and 10 showed ethanol loss rates of less than 1.5%, indicating a higher degree of cross-linking within the resin and making it less susceptible to solvent erosion. In contrast, Examples 5, 6, and 9 showed loss rates exceeding 5%, indicating insufficient cross-linking and potentially the presence of a large amount of free phenolic oligomers. Therefore, Table 1 comprehensively reflects the process dependence of pellet quality, network density, and resin stability, and provides a basis for the controllability of the pore structure after subsequent carbonization and activation.

[0154] Table 2:

[0155]

[0156] Table 2 shows the pore volume, pore size distribution, pore shape, most probable pore size, pore wall thickness, particle size / span, and single-particle compressive strength of the porous carbon materials in different embodiments, demonstrating the influence of different precursor morphologies on the final porous carbon structure. First, the total pore volume reflects the specific capacity potential and liquid absorption capacity. The pore volumes of Examples 1, 2, 7, and 8 range from 1.43 to 1.65 cc / g, which are typical high-pore-volume materials, allowing for the formation of larger lithium storage spaces; while Examples 3, 4, 5, 9, and 10 have lower pore volumes (0.87–0.92 cc / g), corresponding to a denser hard carbon structure. Second, the pore size distribution can determine the potential rate performance of the porous carbon. Examples 1–4 and 7–8, with pore sizes concentrated in the <4nm range (>95%), exhibit regular p6m columnar channels, which facilitate rapid lithium-ion diffusion. Examples 4 and 10, however, show ink bottle-like pores (1m3m), indicating higher activation temperatures or uneven activator diffusion, resulting in narrowing / expansion of the channels, maintaining some stability but with a slightly lower uptake. Third, the most probable pore size can be adjusted within the 2.2–2.9nm range, demonstrating that precise micropore-to-mesopore control can be achieved by controlling the activator, activation temperature, and segmented activation. Fourth, the compressive strength of individual particles ranges from 305–465MPa, generally showing a trend of higher strength with more regular pores and thicker pore walls. Example 7 exhibits the highest strength (465MPa), corresponding to p6m channels and a moderate pore wall thickness (6.9nm). By controlling the sphericity, surface bumps or pits, and degree of condensation of phenolic resin, the pore structure type, order, pore volume, and mechanical strength of the final carbon material can be further regulated, forming a structured and controllable carbon-based framework that directly affects the performance of silicon-carbon anodes.

[0157] Table 3:

[0158]

[0159] Table 3 highlights the performance of the final prepared silicon-carbon anode material in key performance indicators such as specific surface area, true density, compressive strength, crush deformation, full-cell specific capacity, cycle life, rate performance, and expansion rate, representing a concentrated reflection of the final technical effect. First, specific surface area and true density together reflect the number of reaction sites and the material's compactness. Examples 4 and 10 have the highest specific surface area (78–85 m² / g), corresponding to more accessible interfaces, but also have relatively high true density, indicating a denser carbon shell and stronger resistance to pulverization. Second, the compressive strength is generally in the 880–1000 MPa range, showing that the material is suitable for high-stress environments such as winding and electrode pressing. Example 8 has a strength as high as 992 MPa, indicating that its carbon skeleton structure is more regular and the pore wall thickness is reasonable. Third, the full-cell specific capacity shows a stepwise increase: Example 1 (1932 mAh / g) and Example 8 (2245 mAh / g), demonstrating that the more uniform the pore structure, the more stable the carbon shell, and the more controlled the interface, the more efficient lithium storage can be achieved. Fourth, excellent performance was observed in both room temperature cycling and 45°C high-temperature cycling. Most embodiments maintained high capacity at >1500 cycles (room temperature) and >1000 cycles (45°C), demonstrating the significant synergistic effect of the nitrogen-doped soft carbon layer and porous carbon structure in combating volume expansion. Fifth, rate performance was generally between 90–96%, reflecting the high-speed lithium channels jointly established by multi-scale channels and the soft carbon shell. Sixth, the expansion rate was significantly lower than that of ordinary silicon-carbon materials (typically 10–20%), indicating that the confined structure has a significant effect on slowing down volume expansion, which is a particular advantage of this invention. This invention constructs a regular porous carbon framework using spherical phenolic resin, and then achieves comprehensive improvements in capacity, lifetime, rate capability, and expansion control through CVD silicon deposition and nitrogen-doped soft carbon coating, demonstrating a significant synergistic enhancement of electrochemical performance brought about by structural innovation.

[0160] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A spheroid-like phenolic resin-based silicon-carbon negative electrode material, characterized by, It includes spheroid porous carbon, a silicon-based material filled inside the pores of the spheroid porous carbon, and a soft carbon layer on the outer surface of the silicon-carbon negative electrode material; among which, The thickness of the soft carbon layer is 1-100 nm, the mass percentage content of silicon in the silicon-carbon negative electrode material is 5% to 65%, the mass percentage content of carbon in the silicon-carbon negative electrode material is 35% to 95%, the specific surface area of the silicon-carbon negative electrode material is less than 100 m 2 / g, the powder true density of the silicon-carbon negative electrode material is 1.9 g / cm 3 to 2.4 g / cm 3 , and the average value of the crush strength of 20 random single particles of the silicon-carbon negative electrode material is greater than 300 MPa, and the crush displacement deformation is > 16%. The spheroid porous carbon is composed of perfect sphere porous carbon and ellipsoid porous carbon. The parameters of the spheroid porous carbon are 0.8um < Dv50 < 14um, 0.4 < span < 1.

8. The proportion of the number of ellipsoid porous carbon is 5% - 80%, and the number of perfect sphere porous carbon is 20% - 95%. There are cylindrical straight through-holes with a diameter of 1.5 - 8nm and a length less than or equal to the particle size of the spheroid porous carbon inside the spheroid porous carbon. The arrangement of the cylindrical straight through-holes in the porous carbon matrix is an ordered arrangement. The included angle between the connecting lines of adjacent two cylindrical straight through-holes is an integer multiple of 60 degrees. The distance between adjacent two straight through-holes is 5 - 10nm. The total pore volume of the straight through-holes is 0.1cc / g - 0.9cc / g. The straight through-holes are connected by disordered worm-like micropores. The ratio of the pore volume of the micropores to the pore volume of the straight through-holes is 1:1 - 9:

1. The proportion of the pore volume of 5nm and above in the spheroid porous carbon is less than or equal to 10%. The average value of the crushing strength of 20 random single particles of the spheroid porous carbon is greater than 300MPa, and the crushing deformation is greater than 30%. The precursor of the spheroid porous carbon is spheroid phenolic resin; The spheroid-like phenolic resin is mixed by perfect sphere phenolic resin and ellipsoid phenolic resin, the parameters of the spheroid-like phenolic resin are 1um < Dv50 < 15um, 0.4 < span < 1.8, the quantity ratio of the ellipsoid phenolic resin is 5%-80%, the quantity of the perfect sphere phenolic resin is 20%-95%, the ratio of the shortest diameter and the longest diameter of the ellipsoid phenolic resin is ≤0.9, the ratio of the shortest diameter and the longest diameter of the perfect sphere phenolic resin is >0.9, the spheroid-like phenolic resin surface has spheroid-like bulges or spheroid-like pits or both, the number of the spheroid-like bulges or spheroid-like pits is 2-200, the boundary of the spheroid-like bulges or spheroid-like pits is an arc line or a straight line or a mixture of the arc line and the straight line, the number of the straight line or the arc line of the boundary of the spheroid-like bulges or spheroid-like pits is 4-18, the circumference is 0.3-30um, the area is 0.01um 2 -176.7um 2 , the distance between the boundaries of the spheroid-like bulges or spheroid-like pits is 0.02um-20um, the spheroid-like bulges height is 20nm-20um, the spheroid-like pits depth is 50nm-10um, the nitrogen content of the spheroid-like phenolic resin is less than 4%, the carbon content is >70%, the oxygen content is <20%, the ethanol loss rate is ≤5%.

2. A method for preparing a spheroid-like phenolic resin-based silicon-carbon negative electrode material, characterized by, The steps for preparing a silicon-carbon negative electrode material based on spheroid phenolic resin as described in claim 1 include: S1. Mix phenolic monomers, aldehyde monomers, alkaline catalysts, and pore-forming agents in deionized water to form an aqueous phase, and then add an oil phase containing oil monomers and emulsifiers to the aqueous phase to carry out inverse emulsion polycondensation reaction. After curing, spheroid phenolic resin is obtained; S2. Heat the spheroid phenolic resin and then carry out pre-oxidation treatment, then heat in an inert atmosphere for carbonization reaction, and after cooling, immerse it in an activator for gradient activation treatment to obtain spheroid porous carbon. Among which, the gradient activation treatment is a treatment method using segmented temperature or segmented impregnation; S3. Degas the spheroid porous carbon under vacuum and then place it in a chemical vapor deposition reaction chamber. After heating, introduce a silicon source gas for deposition reaction to obtain a deposition precursor. Coating a carbon source and a nitrogen source on the outer surface of the deposition precursor, and after high-temperature reaction, a silicon-carbon negative electrode material based on spheroid phenolic resin is obtained. Among which, the outer surface of the silicon-carbon negative electrode material is a nitrogen-doped soft carbon layer.

3. The method of claim 2, wherein the method is characterized by: Step S1 includes: S1.

1. Add phenolic monomers to a reaction kettle equipped with mechanical stirring, a thermometer, and a condensation device, add aldehyde monomers corresponding to a molar ratio of (1.5 - 2.5):1 to the phenolic monomers, and then add an alkaline catalyst equivalent to 15 - 25wt% of the mass of the phenolic monomers. Stir and react at 60 - 75°C for 1.5 - 2.5h to obtain a phenolic prepolymer resin solution; S1.

2. Add the phenolic prepolymer resin solution to a pore-forming agent equivalent to 50 - 80wt% of the mass of the phenolic prepolymer resin solution, and add deionized water equivalent to 400 - 600wt% of the mass of the phenolic prepolymer resin. Stir at 300 - 600rpm at room temperature for 30 - 60min to obtain an aqueous phase; S1.3, add emulsifier in oil monomer, which is 0.1-0.3wt% of the mass of the oil monomer, and perform high-speed shearing at 6000-10000 rpm for 5-15 min to obtain an oil phase; S1.4, drop the water phase into the oil phase within 5-20 min, and continue high-speed shearing at 6000-10000 rpm for 5-20 min, and then perform ultrasonic treatment in an ultrasonic device with a power of 800-2000 W for 20-90 min to obtain a uniform reverse-phase emulsion; S1.5, adjust the pH of the uniform reverse-phase emulsion to 1.5-2.5 by adding hydrochloric acid, and heat to 130-150℃ and stand for 12-30 h to perform polycondensation solidification, to obtain spheroid phenolic resin microspheres, which are washed with deionized water and ethanol until neutral, and dried at 80-120℃ for 8-12 h to obtain spheroid phenolic resin.

4. The method for preparing a spheroid-like phenolic resin-based silicon-carbon negative electrode material according to claim 2 or 3, characterized in that, In step S1, the phenolic monomer includes at least one of phenol, m-dihydroxybenzene, p-dihydroxybenzene, o-dihydroxybenzene, m-cresol, p-cresol, bisphenol A, bisphenol F, the aldehyde monomer includes at least one of formaldehyde, glutaraldehyde, furfural, acetaldehyde, propionaldehyde, the alkaline catalyst includes at least one of NaOH, ethylenediamine, triethanolamine, triethylamine, aniline, ammonia water, the pore-forming agent includes at least one of block polyether, F127, P123, and the emulsifier includes at least one of Span 80, Span 60, glycerol monostearate, and dipolyglycerol oleate, and the oil monomer includes at least one of castor oil, mineral oil, paraffin oil, and vegetable oil.

5. The method of claim 2, wherein the method is characterized by: Step S2 includes: S2.1, heat the spheroid phenolic resin to 200-300℃ at a temperature increasing rate of 1-3℃ / min in an air atmosphere, and keep the temperature for 1-4 h to obtain a pre-oxidized spheroid phenolic resin precursor; S2.2, transfer the pre-oxidized spheroid phenolic resin precursor into a tube furnace, establish an inert protective atmosphere by introducing nitrogen or argon at a flow rate of 50-200 mL / min, heat to 600-800℃ at a temperature increasing rate of 2-5℃ / min, keep the temperature for 1-3 h to perform carbonization reaction, and obtain a spheroid hard carbon material; S2.3, after cooling the spheroid hard carbon material to room temperature, add it into an activator with a mass fraction of 5-15wt% of the spheroid hard carbon material, immerse at room temperature to 40℃ for 0.5-2 h, then filter out the immersed spheroid hard carbon material, and dry at 80-120℃ for 4-8 h to obtain a pre-impregnated hard carbon, and then place the pre-impregnated hard carbon into a tube furnace, heat to 650-750℃ at a temperature increasing rate of 2-5℃ / min under nitrogen or argon protection, keep the temperature for 0.5-1.5 h to perform first-stage medium-temperature activation, and obtain a semi-activated spheroid carbon material; S2.4, after the semi-activated spheroid-like carbon material is cooled to room temperature, it is added again into the activator with a mass fraction of 1-5wt% of the spheroid-like hard carbon material, and is immersed at 25-40℃ for 2-6h, and then is dried at 80-120℃ for 4-8h, is heated to 800-850℃ at a rate of 2-3℃ / min under the protection of nitrogen or argon, and is subjected to gas-assisted activation by inputting carbon dioxide or water vapor, is kept for 0.5-1.5h, and a spheroid-like porous carbon material pre-product is obtained; S2.5, the spheroid-like porous carbon material pre-product is taken out, is added into a dilute hydrochloric acid or dilute nitric acid solution, is soaked at room temperature for 0.5-2h, and then is repeatedly washed with deionized water until the pH of the filtrate is close to neutral, and is dried at 80-120℃ for 8-12h, and a spheroid-like porous carbon is obtained.

6. The method of claim 5, wherein the method is characterized by: The activator includes at least one of potassium hydroxide, potassium carbonate, zinc chloride, phosphoric acid, and sodium hydroxide.

7. The method of claim 2, wherein the method is characterized by: Step S3 includes: S3.1, the spheroid-like porous carbon is placed in a quartz boat and is put into a chemical vapor deposition reaction chamber, is heated to 150-250℃ at a rate of 1-3℃ / min under a vacuum degree of 10-100Pa and is kept for 1-3h, and a spheroid-like porous carbon precursor after vacuum degassing treatment is obtained; S3.2, the spheroid-like porous carbon precursor after vacuum degassing treatment is kept in the chemical vapor deposition reaction chamber, is heated to 350-450℃ at a rate of 2-5℃ / min under the protection of argon or argon / hydrogen mixed gas, the pressure is adjusted to 100-1000Pa, and then a silicon source gas with a volume fraction of 5-20vol% of the reaction chamber is inputted, the deposition time is controlled to be 0.5-4h, a gas deposition reaction is carried out, and a deposition precursor is obtained; S3.3, the deposition precursor is added into a ball milling tank, a carbon source and a nitrogen source are added, and an ethanol / water mixed solvent corresponding to 300-600wt% of the total mass of solids is added, the ball milling is carried out at a stirring speed of 150-300rpm for 1-4h, and then is dried at 80-120℃ for 8-12h, and a deposition composite material coated with a carbon-nitrogen precursor is obtained, wherein the mass ratio of the carbon source to the deposition precursor is (10-30):100, and the mass ratio of the nitrogen source to the deposition precursor is (5-20):100; S3.4, the deposition composite material is put into a tube furnace, is heated to 800-1100℃ at a rate of 2-5℃ / min under the protection of nitrogen or argon, and is kept at the temperature for 1-3h, a nitrogen-doped soft carbon shell layer is formed, and a spheroid-like phenolic resin-based silicon-carbon negative electrode material is obtained.

8. The method of claim 2 or 7, wherein the method is characterized by, The silicon source gas includes at least one of silane, dichlorosilane, trichlorosilane, silicon tetrachloride, and diethylsilane, the carbon source includes at least one of glucose, sucrose, pitch, and polyvinylpyrrolidone, and the nitrogen source includes at least one of melamine, urea, and polyacrylonitrile.

9. The method of claim 2, wherein the method is characterized by: Between step S3.3 and step S3.4, The deposition composite is placed in a tube furnace, and heated to 300-450℃ at 2-5℃ / min under argon protection, then mixed gas containing oxygen and ammonia is introduced, the total flow rate of the mixed gas is 50-200 mL / min, and the deposition composite is treated for 0.5-2 h, to obtain an oxygen-nitrogen treated deposition composite.

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