Preparation method and application of high-tap-density spheroidized silicon-carbon negative electrode material

Abstract

The invention relates to the field of battery materials, in particular to a preparation method and application of a high-tap-density spheroidized silicon-carbon negative electrode material. The preparation method of the high-tap-density spheroidized silicon-carbon negative electrode material comprises the following steps: S1, graphite is subjected to shaping treatment; s2, preparing silicon-carbon mixed slurry; s3, carrying out spray granulation on the silicon-carbon mixed slurry; and S4, mixing, coating and carbonizing the silicon-carbon mixed particles and a coating agent. The invention provides the preparation method of the high-tap-density spheroidized silicon-carbon negative electrode material, and the finally prepared silicon-carbon negative electrode material improves the volume expansion of a silicon-based negative electrode and improves the tap density; according to the present invention, the sand milling mixing technology improves the non-uniform mixing of the materials in the precursor slurry of the spray granulation technology, the secondary coating of the particles can be achieved after the carbonization of the binder and the coating agent, and the coated silicon-carbon negative electrode battery has advantages of stable capacity, good cycle performance and wide application potential.

Description

Technical Field

[0001] The present application relates to the field of battery materials, and more specifically to a preparation method and application of a high tap density spherical silicon-carbon negative electrode material. Background Art

[0002] With the global energy transition, the development of new energy technologies has become a key focus in resolving the conflict between surging energy demand and environmental protection. The rapid growth of clean energy applications, particularly in electric vehicles, has placed higher demands on energy storage technologies with high energy density and long cycle life. Lithium-ion batteries, with their core advantages of high energy density, excellent cycle performance, and environmental friendliness, have become the mainstream power source for mobile electronic devices and electric vehicles, and continue to evolve towards higher capacity and greater safety.

[0003] In the core material system of lithium-ion batteries, technological breakthroughs in negative electrode materials directly affect the overall performance of the battery. The specific capacity of the battery is determined by the specific capacity of the negative and positive electrode materials. Among various negative electrode materials, silicon has a high theoretical specific capacity (about 4200mAh / g), which is 10 times higher than that of traditional carbon negative electrodes (372mAh / g), and has better lithium insertion and release potential. However, in actual applications, the development of silicon negative electrodes is still subject to various obstacles, the main one of which is its huge volume change (about 300%). Expansion / contraction stress will be generated during the lithium insertion / delithiation process, causing severe cracking of the silicon, resulting in the formation of an unstable SEI film on the silicon surface and consumption of active lithium ions, resulting in rapid loss of capacity and low initial coulombic efficiency.

[0004] Graphite and porous carbon, which exhibit minimal volume changes during lithiation (e.g., graphite's volume expansion rate is approximately 10.6%), are anode materials and exhibit excellent cycling stability and conductivity. Compared to silicon, carbon materials have similar properties and can bond tightly to each other. Therefore, silicon-carbon anodes have been widely studied due to their higher capacity, improved conductivity, and cycling stability.

[0005] Generally speaking, the greater the tap density, the higher the battery capacity can be, so the tap density is also regarded as one of the reference indicators of material energy density. Under certain process conditions, the greater the tap density, the higher the battery capacity. Summary of the Invention

[0006] In order to improve the core performance of lithium-ion batteries, it is necessary to pursue a better tap density of the anode material. The greater the tap density, the higher the capacity of the battery can be. Therefore, the tap density is also regarded as one of the reference indicators for the energy density of the material. Under certain process conditions, the greater the tap density, the higher the capacity of the battery. Therefore, this application provides a method for preparing a spherical silicon-carbon anode material with a high tap density, and finally obtains a silicon-carbon anode material that improves the volume expansion of the silicon-based anode and increases the tap density; the sanding mixing technology improves the uneven mixing of materials in the precursor slurry of the spray granulation technology. After carbonization, the binder and the coating agent can achieve secondary coating of the particles. The silicon-carbon anode battery after coating has a stable capacity and better cycle performance, and has broad application potential.

[0007] A method for preparing a spherical silicon-carbon anode material with a high tap density specifically includes the following steps: S1: Obtain graphite and perform shaping treatment to obtain shaped graphite; S2: Add the shaped graphite, nano-silicon, binder and dispersant to ethanol and perform sanding treatment in a sand mill to obtain a silicon-carbon mixed slurry; S3: Perform spray granulation on the silicon-carbon mixed slurry to obtain silicon-carbon mixed particles; S4: Mix, coat and carbonize the silicon-carbon mixed particles with a coating agent, crush and screen to obtain a spherical silicon-carbon anode material with a high tap density.

[0008] As a preferred embodiment, the graphite is artificial graphite powder.

[0009] As a preferred embodiment, in S1, the shaping treatment frequency is 40-50 Hz.

[0010] As a preferred embodiment, in S1, the shaping treatment time is 60-100 min.

[0011] As a preferred embodiment, in S1, the tap density of the shaped graphite after shaping treatment is 0.8-1 g / cm 3 , and the D50 average particle size is 6-10 μm.

[0012] As a preferred embodiment, in S2, the rotation speed of the sanding treatment is 800-1500 r / min, and the time is 2-6 h.

[0013] As a preferred embodiment, the solid content of the silicon-carbon mixed slurry is 5-40%.

[0014] As a preferred embodiment, the solid content of the silicon-carbon mixed slurry is 20-30%.

[0015] As a preferred embodiment, in S2, the mass ratio of the shaped graphite, nano-silicon, binder and dispersant is (50-90):(5-40):(1-5):(0.5-3).

[0016] As a preferred embodiment, in S2, the mass ratio of the shaped graphite, nano-silicon, binder, and dispersant is (85 - 90):(5 - 10):(3 - 4):(1.5 - 2).

[0017] As a preferred embodiment, the D50 average particle size of the nano-silicon is 100 - 1500 nm.

[0018] As a preferred embodiment, the D50 average particle size of the nano-silicon is 500 - 1000 nm.

[0019] As a preferred embodiment, the D50 average particle size of the artificial graphite powder is 5 - 15 μm.

[0020] As a preferred embodiment, the D50 average particle size of the artificial graphite powder is 6.5 - 10 μm.

[0021] As a preferred embodiment, the binder is a composition of melamine, polyacrylic acid, and polyimide.

[0022] As a preferred embodiment, the mass ratio of melamine, polyacrylic acid, and polyimide is (5 - 5.5):(2.5 - 3):(1 - 1.2).

[0023] As a preferred embodiment, the mass ratio of melamine, polyacrylic acid, and polyimide is 5:3:1.

[0024] As a preferred embodiment, the dispersant is at least one of polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, polycarboxylic acid, and lignosulfonate.

[0025] As a preferred embodiment, the dispersant is polyvinylpyrrolidone or polycarboxylic acid.

[0026] As a preferred embodiment, the dispersant is polyvinylpyrrolidone K30.

[0027] As a preferred embodiment, in S3, the inlet temperature of spray granulation is 160 - 220 °C, the outlet temperature is 80 - 105 °C, the fan frequency is 40 - 50 Hz, the atomizer frequency is 100 - 400 Hz, and the feeding rate is 30 - 40%.

[0028] As a preferred embodiment, in S3, the inlet temperature of spray granulation is 200 - 205 °C, the outlet temperature is 100 - 105 °C, the fan frequency is 40 - 45 Hz, the atomizer frequency is 300 - 350 Hz, and the feeding rate is 30 - 35%.

[0029] As a preferred embodiment, the mass ratio of the silicon-carbon hybrid particles to the coating agent is 1:(8-10).

[0030] As a preferred embodiment, the mass ratio of the silicon-carbon hybrid particles to the coating agent is 1:9.

[0031] As a preferred embodiment, the D50 average particle size of the silicon-carbon hybrid particles is 5.5-7.5 μm.

[0032] As a preferred embodiment, the coating agent is modified asphalt.

[0033] As a preferred embodiment, the preparation method of the modified asphalt specifically comprises the following steps: S1: Mesophase pitch is mixed and stirred with ammonium polyphosphate, polyphosphazene and phenylboric acid to obtain a mixture; S2: The mixture is transferred to a tube furnace and subjected to secondary staged high-temperature treatment to promote the fusion of raw materials; S3: The product is rapidly cooled by liquid nitrogen, ball-milled and sieved, and then obtained.

[0034] As a preferred embodiment, the preparation method of the modified asphalt specifically comprises the following steps: S1: The mesophase pitch is crushed to a particle size of 0.5-1 mm, mixed with ammonium polyphosphate, polyphosphazene and phenylboric acid, and added to a double planetary mixer, and stirred at a speed of 150-200 rpm under nitrogen protection at 260-280 °C for 2.5-3 h to obtain a mixture; S2: The mixture is transferred to a tube furnace, heated to 400 °C at a rate of 4-5 °C / min in an inert atmosphere and kept warm for 1-1.5 h, and then heated to 900-1000 °C at a rate of 3-4 °C / min and kept warm for 2-3 h; S3: The product is rapidly cooled by liquid nitrogen and then ball-milled, and then sieved through a 600-800 mesh sieve to obtain it.

[0035] As a preferred embodiment, the mass ratio of the mesophase pitch, ammonium polyphosphate, polyphosphazene and phenylboric acid is (10-10.5):(1.4-1.6):(0.8-1.2):(0.3-0.5).

[0036] As a preferred embodiment, the mass ratio of the mesophase pitch, ammonium polyphosphate, polyphosphazene and phenylboric acid is 10:1.5:1:0.4.

[0037] As a preferred embodiment, the D50 average particle size of the modified asphalt is 5-10 μm.

[0038] By adding the modified asphalt as a coating agent, the electrical properties and cycling performance of the anode material can be significantly improved. Ammonium polyphosphate in the modified asphalt decomposes to generate PO4 during the carbonization process 3-, reacting with the silicon surface to form Li3PO4, which has high ionic conductivity, promotes lithium ion transport, and at the same time inhibits the direct contact between silicon and the electrolyte. Meanwhile, the polyphosphazene pyrolyzes at high temperature to generate a P / N co-doped carbon skeleton, where N atoms (pyridine nitrogen, graphitic nitrogen) provide electron conduction sites, and P atoms (P-O bonds) enhance the compatibility between the carbon layer and the electrolyte. On the other hand, the phenylboric acid cross-linked network is retained after carbonization, and the increased elastic modulus effectively inhibits the rupture of the coating layer caused by silicon expansion. Moreover, the modified asphalt can form a certain degree of gradient structure. The outer asphalt assists the highly graphitized carbon layer formed by carbonization to provide rapid electron conduction, while the inner layer can accelerate lithium ion diffusion through the defect sites of the derived P / N doped carbon.

[0039] As a preferred embodiment, in S4, the coating temperature for coating carbonization is 700 - 900 °C, and the coating time is 5 - 6 h.

[0040] As a preferred embodiment, the D50 average particle size of the silicon-carbon anode material is 18 - 20 μm.

[0041] This application further defines the application of the high tap density spherical silicon-carbon anode material in the fields of electronic devices and electric vehicles.

[0042] The beneficial effects of this application are as follows:

[0043] 1. The preparation method of a high tap density spherical silicon-carbon anode material provided in this application finally prepares a silicon-carbon anode material that improves the volume expansion of the silicon-based anode and increases the tap density. The sanding and mixing technology improves the uneven mixing of materials in the precursor slurry of the spray granulation technology. The binder and the coating agent can achieve secondary coating of the particles after carbonization. The battery capacity of the coated silicon-carbon anode is stable, and the cycle performance is better, with broad application potential.

[0044] 2. The preparation method of a high tap density spherical silicon-carbon anode material provided in this application can effectively improve the electrical properties and stability of the anode material by adding a composite binder. Among them, melamine is used as the main binder, which forms a three-dimensional rigid network through triazine ring cross-linking during high-temperature carbonization, providing structural support, inhibiting the volume expansion of silicon particles, and the flexible chain segments containing carboxyl groups in it form hydrogen bonds with the silicon surface hydroxyl groups during the drying stage and undergo condensation reactions with the amino groups (-NH2) of melamine during the carbonization process to generate amide bonds to enhance the network toughness. On the other hand, the nitrogen-doped carbon generated after the carbonization of melamine resin provides an electron transport channel, reduces the charge transfer impedance, and the polyimide carbonizes to form a carbon layer, expanding the lithium ion intercalation channel, and at the same time forming a gradient conductive interface with the nitrogen-doped carbon of melamine.

[0045] 3. In the preparation method of the high tap density spherical silicon-carbon anode material provided in this application, ammonium polyphosphate in the added modified asphalt decomposes during carbonization to generate PO4 3- , which reacts with the silicon surface to form Li3PO4. Its high ionic conductivity promotes lithium ion transport, while inhibiting the direct contact between silicon and the electrolyte. At the same time, polyphosphazene pyrolyzes at high temperature to generate a P / N co-doped carbon skeleton, where N atoms (pyridine nitrogen, graphitic nitrogen) provide electron conduction sites, and P atoms (P-O bonds) enhance the compatibility between the carbon layer and the electrolyte; on the other hand, the phenylboric acid cross-linked network remains after carbonization, and the increased elastic modulus effectively inhibits the rupture of the coating layer caused by silicon expansion. Moreover, the modified asphalt can form a gradient structure to a certain extent. The outer layer of asphalt assists the highly graphitized carbon layer formed by carbonization to provide fast electron conduction, while the inner layer can accelerate lithium ion diffusion through the derived P / N doped carbon via defect sites. Description of the Drawings

[0046] Figure 1 It is the SEM image of the high tap density spherical silicon-carbon anode material prepared in Example 1 of this application.

[0047] Figure 2 It is the SEM image of the high tap density spherical silicon-carbon anode material prepared in Example 2 of this application.

[0048] Figure 3 It is the cyclic performance test result graph of the high tap density spherical silicon-carbon anode material prepared in Example 1 of this application at a current density of 0.1C. Detailed Embodiments

[0049] In the detailed embodiments, specific implementation cases will be used to more intuitively display and illustrate the content in the inventive content of this application.

[0050] Example 1

[0051] The preparation method of the high tap density spherical silicon-carbon anode material specifically includes the following steps: S1: Obtain artificial graphite powder with an average D50 particle size of 7.5 μm, and perform shaping treatment on the graphite to obtain shaped graphite; S2: Add the shaped graphite, nano-silicon, binder and dispersant to ethanol and perform sand milling treatment in a sand mill to obtain a silicon-carbon mixed slurry; S3: Perform spray granulation on the silicon-carbon mixed slurry to obtain silicon-carbon mixed particles; S4: Mix, coat and carbonize the silicon-carbon mixed particles with a coating agent, and then pulverize and screen to obtain the high tap density spherical silicon-carbon anode material.

[0052] The graphite is artificial graphite powder with an average D50 particle size of 7.5 μm.

[0053] In S1, the shaping treatment frequency is 45 Hz, and the shaping treatment time is 80 min; the tap density of the shaped graphite after shaping treatment is 0.92 g / cm 3, the D50 average particle size is 7.1 μm.

[0054] In S2, the rotation speed of the sanding treatment is 1400 r / min, and the time is 2 h.

[0055] The solid content of the silicon-carbon mixed slurry is 20%; in S2, the mass ratio of the shaped graphite, nano-silicon, binder, and dispersant is 85:10:3:2.

[0056] The D50 average particle size of the nano-silicon is 600 nm.

[0057] The binder is a composition of melamine, polyacrylic acid, and polyimide, and the mass ratio is 5:3:1.

[0058] Melamine is purchased from the product of model 303 sold by BASF in Germany; polyacrylic acid is purchased from the high-quality product sold by Wuhan Lanaibai Pharmaceutical Chemical Co., Ltd. in China; polyimide is purchased from the product of model HN sold by DuPont in the United States. HN model product.

[0059] The dispersant is polyvinylpyrrolidone K30.

[0060] In S3, the inlet temperature of the spray granulation is 200 °C, the outlet temperature is 102 °C, the fan frequency is 40 Hz, the atomizer frequency is 300 Hz, and the feeding rate is 30%.

[0061] The D50 average particle size of the silicon-carbon mixed particles is 6.6 μm.

[0062] The mass ratio of the silicon-carbon mixed particles to the coating agent is 1:9.

[0063] The coating agent is modified asphalt. The preparation method of the modified asphalt, in terms of parts by mass, specifically includes the following steps: S1: Crush 10 parts of mesophase pitch to a particle size of 0.8 mm, mix it with 1.5 parts of ammonium polyphosphate, 1 part of polyphosphazene, and 0.4 part of phenylboric acid, and add them to a double planetary mixer, and stir at a rotation speed of 180 rpm under nitrogen protection at 260 °C for 3 h to obtain a mixture; S2: Transfer the mixture to a tubular furnace, raise the temperature to 400 °C at a rate of 5 °C / min in an inert atmosphere and hold for 1 h, and then raise the temperature to 950 °C at a rate of 4 °C / min and hold for 3 h; S3: Quench the product with liquid nitrogen and then ball mill it, and then pass through a 600-mesh sieve to obtain it.

[0064] The mesophase pitch is purchased from the mesophase pitch product for coating sold by Hebei Deri New Material Technology Co., Ltd. in China; the ammonium polyphosphate is purchased from the industrial-grade product sold by Shandong Zhijia Chemical Technology Co., Ltd. in China; the polyphosphazene is purchased from the industrial-grade product of polydiphenoxyphosphazene sold by Hubei Xinghengye Technology Co., Ltd. in China.

[0065] The D50 average particle size of the modified asphalt is 5.5 μm.

[0066] In S4, the coating temperature for carbon coating is 700 °C and the coating time is 5 h.

[0067] Example 2

[0068] This example is only different from Example 1 in the following aspects: the binder is a composition of melamine, polyacrylic acid and polyimide, and the mass ratio is 5.5:2.5:1.1.

[0069] In S4, the coating temperature for carbon coating is 900 °C and the coating time is 6 h.

[0070] Example 3

[0071] This example is only different from Example 1 in the following aspects: in S2, the mass ratio of shaped graphite, nano-silicon, binder and dispersant is 90:5:3:2.

[0072] The mass ratio of silicon-carbon mixed particles to the coating agent is 1:8.

[0073] Example 4

[0074] This example is only different from Example 1 in the following aspects: the mass ratio of silicon-carbon mixed particles to the coating agent is 1:10.

[0075] In S4, the coating temperature for carbon coating is 900 °C and the coating time is 5 h.

[0076] Comparative Example 1

[0077] This comparative example is only different from Example 1 in the following aspects: the graphite is artificial graphite powder with an average D50 particle size of 7 μm and has not been subjected to shaping treatment.

[0078] Comparative Example 2

[0079] This comparative example is only different from Example 1 in the following aspects: the solid content of the silicon-carbon mixed slurry is 35%; in S2, the mass ratio of shaped graphite, nano-silicon, binder and dispersant is 90:5:1.5:3.5.

[0080] Comparative Example 3

[0081] This comparative example is only different from Example 1 in the following aspects: the binder is a composition of melamine, polyacrylic acid and polyimide, and the mass ratio is 9:1:0.5.

[0082] Comparative Example 4

[0083] This comparative example is only different from Example 1 in the following aspects: the binder is a composition of melamine, polyacrylic acid and polyimide, and the mass ratio is 2:3:4.

[0084] Comparative Example 5

[0085] This comparative example only differs from Example 1 in the following aspects: The coating agent is modified asphalt, and the preparation method of the modified asphalt, by mass, specifically includes the following steps: S1: Crush 18.5 parts of mesophase pitch to a particle size of 0.8 mm, mix it with 0.8 part of ammonium polyphosphate, 1.8 parts of polyphosphazene and 0.2 part of phenylboric acid, add them to a double planetary mixer, and stir at a speed of 180 rpm under nitrogen protection at 260 °C for 3 h to obtain a mixture; S2: Transfer the mixture to a tubular furnace, raise the temperature to 400 °C at a rate of 5 °C / min under an inert atmosphere and hold for 1 h, then raise the temperature to 950 °C at a rate of 4 °C / min and hold for 3 h; S3: Quench the product with liquid nitrogen and then ball-mill it, and then pass through a 600-mesh sieve to obtain the product.

[0086] Comparative Example 6

[0087] This comparative example only differs from Example 1 in the following aspects: The coating agent is modified asphalt, and the preparation method of the modified asphalt, by mass, specifically includes the following steps: S1: Crush 8.5 parts of mesophase pitch to a particle size of 0.8 mm, mix it with 2.8 parts of ammonium polyphosphate, 0.5 part of polyphosphazene and 0.1 part of phenylboric acid, add them to a double planetary mixer, and stir at a speed of 180 rpm under nitrogen protection at 260 °C for 3 h to obtain a mixture; S2: Transfer the mixture to a tubular furnace, raise the temperature to 400 °C at a rate of 5 °C / min under an inert atmosphere and hold for 1 h, then raise the temperature to 950 °C at a rate of 4 °C / min and hold for 3 h; S3: Quench the product with liquid nitrogen and then ball-mill it, and then pass through a 600-mesh sieve to obtain the product.

[0088] Performance evaluation

[0089] The particle size and tap density of the silicon-carbon anode materials prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were tested respectively, and the results are listed in Table 1. The names and models of the instruments used for the test are: for particle size, laser particle size distribution analyzer, Malvern - Mastersizer 2000; for tap density, tap density tester BT-311, and the average value of 10 tests was taken for the test.

[0090] The discharge capacity of the silicon-carbon anode materials in Examples 1 to 4 and Comparative Examples 1 to 6 was tested by using a half-cell test method, and the results are listed in Table 1.

[0091] The half-cell test method is as follows: Use the silicon-carbon anode materials prepared in the examples and comparative examples as the active substances, weigh them according to a ratio of 8:1:1 with the conductive agent (SP) and the binder (PVDF), mix them, add N-methylpyrrolidone, stir evenly to form a negative electrode paste, coat it on a copper foil, and put the coated electrode sheet into a vacuum drying oven at 100 °C for vacuum drying for 12 h for standby.

[0092] Half-cell preparation and electrochemical performance test: The half-cell was assembled in a glove box filled with argon. The electrolyte was 1 M LiPF6 + EC∶DEC∶DMC = 1∶1∶1 (volume ratio). The metallic lithium sheet was used as the counter electrode. The electrochemical performance test was carried out on a LADN battery tester. The charge-discharge voltage range was from 0.005 V to 1.5 V, and the cycle performance of the battery at a rate of 0.1 C was tested.

[0093] Table 1 Performance evaluation table

[0094]

[0095] From the final performance test results of the examples and comparative examples, Comparative Example 1 obtained worse performance results compared to the examples. The examples had higher discharge capacity and better battery cycle performance while ensuring high tap density. This is because the examples adopted the better technical solutions defined in this application to prepare better modified asphalt, and through the combined action of the aforementioned composite binder, the comprehensive performance of the anode material was significantly improved.

Claims

1. A preparation method of a spherical silicon-carbon anode material with high tap density, characterized in that: S1: Obtain the shaped graphite through shaping treatment to get shaped graphite; S2: Add the shaped graphite, nano-silicon, binder and dispersant into ethanol and grind them in a sand mill to obtain a silicon-carbon mixed slurry; S3: Spray granulate the silicon-carbon mixed slurry to obtain silicon-carbon mixed particles; S4: Mix and coat the silicon-carbon mixed particles with a coating agent, carbonize them, crush and screen them to obtain a high tap density spherical silicon-carbon anode material; In S1, the frequency of the shaping treatment is 40 to 50 Hz, the time is 60 to 100 min, and the tapped density of the shaped graphite after the shaping treatment is 0.8 to 1 g / cm 3 , and the average particle size of D50 is 6 to 10 μm; In S2, the mass ratio of the shaped graphite, nano-silicon, binder and dispersant is (50 - 90):(5 - 40):(1 - 5):(0.5 - 3); The binder is a composition of melamine, polyacrylic acid and polyimide, and the mass ratio is (5 - 5.5):(2.5 - 3):(1 - 1.2).

2. The method for preparing a high tap density spherical silicon-carbon negative electrode material according to claim 1, characterized in that: The D50 average particle size of the nano-silicon is 100 - 1500 nm.

3. The preparation method of the high tap density spherical silicon-carbon anode material according to claim 2, characterized in that: The D50 average particle size of the artificial graphite powder is 5 - 15 μm.

4. The method for preparing a high tap density spherical silicon-carbon negative electrode material according to claim 3, characterized in that: The dispersant is at least one of polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, polycarboxylic acid and lignosulfonate.

5. The preparation method of the high tap density spherical silicon-carbon anode material according to claim 4, characterized in that: In S3, the inlet temperature of the spray granulation is 160 - 220 °C, the outlet temperature is 80 - 105 °C, the fan frequency is 40 - 50 Hz, the atomizer frequency is 100 - 400 Hz, and the feeding rate is 30 - 40%.

6. The preparation method of the high tap density spherical silicon-carbon anode material according to claim 5, wherein: The mass ratio of the silicon-carbon mixed particles and the coating agent is 1:(8 - 10).

7. The preparation method of the spherical silicon-carbon anode material with high tap density according to claim 6, characterized in that: The D50 average particle size of the silicon-carbon mixed particles is 5.5 - 7.5 μm.

8. The preparation method of the high tap density spherical silicon-carbon anode material according to claim 7, wherein: The coating agent is modified asphalt; The preparation method of the modified asphalt specifically includes the following steps: S1: Mix and stir mesophase pitch with ammonium polyphosphate, polyphosphazene and phenylboric acid to obtain a mixture; S2: Transfer the mixture to a tubular furnace and perform secondary staged high-temperature treatment to promote the fusion of raw materials; S3: Quench, ball mill and screen the product to obtain it.

9. The preparation method of the high tap density spherical silicon-carbon anode material according to claim 8, characterized in that: The D50 average particle size of the modified asphalt is 5 - 10 μm.

10. Application of a silicon-carbon anode material prepared by the preparation method of the high tap density spherical silicon-carbon anode material according to any one of claims 1 - 9 in the fields of electronic devices and electric vehicles.

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