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

Abstract

The application relates to the field of battery materials, and more particularly to a preparation method of high-tap-density spheroidized silicon-carbon negative electrode material and application thereof. 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, silicon-carbon mixed slurry is prepared; S3, the silicon-carbon mixed slurry is subjected to spray granulation; and S4, the silicon-carbon mixed particles are mixed with a coating agent to coat carbon. The application provides a preparation method of high-tap-density spheroidized silicon-carbon negative electrode material, and the finally prepared silicon-carbon negative electrode material improves the effects of improving the volume expansion of a silicon-based negative electrode and improving the tap density; the sand-milling mixing technology improves the uneven mixing of materials in the precursor slurry of the spray granulation technology, the binder and the coating agent can realize secondary coating of the particles after carbonization, the silicon-carbon negative electrode battery capacity after coating is stable, and the cycle performance is better, so that the application has wide application potential.

Description

TECHNICAL FIELD

[0001] The application relates to the field of battery materials, in particular to a preparation method of a high-tapped-density spherical silicon-carbon negative electrode material and application thereof. BACKGROUND

[0002] With the transformation of global energy structure, the development of new energy technology has become the core direction to solve the contradiction between the rapid increase of energy demand and environmental protection. The rapid development of clean energy application represented by electric vehicles puts forward higher requirements for energy storage technology with high energy density and long cycle life. Lithium ion battery has become the mainstream power source in the field of mobile electronic devices and electric vehicles due to its high energy density, excellent cycle performance and environmental friendliness, and continues to iterate and upgrade in the direction of high capacity and high safety.

[0003] In the core material system of lithium ion battery, the breakthrough of negative electrode material directly affects the overall performance of the battery. The specific capacity of the battery is determined by the specific capacity of the negative electrode and the positive electrode material. Among various negative electrode materials, silicon has a high theoretical specific capacity (about 4200 mAh / g), which is 10 times higher than that of traditional carbon negative electrode (372 mAh / g), and has better lithium insertion and release potential. However, in practical application, the development of silicon negative electrode is still hindered by many factors, one of which is its huge volume change (about 300%). During the lithium insertion / desorption process, expansion / contraction stress will be generated, which will cause the silicon to crack seriously, resulting in the formation of unstable SEI film on the surface of silicon and the consumption of active lithium ions, thereby causing rapid loss of capacity and low initial coulombic efficiency.

[0004] And the negative electrode material with small volume change (such as graphite volume expansion rate about 10.6%) during lithiation, such as graphite and porous carbon, has good cycle stability and conductivity. Compared with silicon, carbon materials have similar properties, and they can be closely combined with each other. Therefore, silicon-carbon negative electrode has been widely studied due to its higher capacity, better electrical conductivity and cycle stability.

[0005] Generally speaking, the greater the tapped density, the higher the capacity of the battery can be made, so the tapped density is also considered as one of the reference indicators of the energy density of the material. Under certain process conditions, the greater the tapped density, the higher the capacity of the battery. SUMMARY

[0006] In order to improve the core performance of lithium ion battery, better tap density of negative electrode material needs to be pursued, the greater the tap density, the higher the capacity of the battery can be made, so the tap density is also regarded as one of the reference indexes of material energy density, under certain process conditions, the greater the tap density, the higher the capacity of the battery. Therefore, the application provides a preparation method of high-tap-density spheroidized silicon-carbon negative electrode material, and the finally prepared silicon-carbon negative electrode material improves the effects of improving the volume expansion of silicon-based negative electrode and improving the tap density; the sanding mixing technology improves the uneven mixing of materials in the precursor slurry of the spray granulation technology, the binder and the coating agent can realize secondary coating of the particles after carbonization, the silicon-carbon negative electrode battery after coating has stable capacity and better cycle performance, and has wide application potential.

[0007] The preparation method of the high-tap-density spheroidized silicon-carbon negative electrode material specifically comprises the following steps: S1: obtaining graphite after shaping treatment to obtain shaped graphite; S2: adding the shaped graphite, nano-silicon, a binder and a dispersing agent into ethanol and sanding in a sand mill to obtain a silicon-carbon mixed slurry; S3: spray granulating the silicon-carbon mixed slurry to obtain silicon-carbon mixed particles; and S4: mixing and coating the silicon-carbon mixed particles with a coating agent, carbonizing, crushing and screening to obtain the high-tap-density spheroidized silicon-carbon negative electrode material.

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

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

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

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

[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, the nano-silicon, the binder and the dispersing agent is (50-90) :(5-40) :(1-5) :(0.5-3).

[0016] As a preferred embodiment, in the S2, the mass ratio of the shaped graphite, the nano-silicon, the binder and the 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 combination of melamine, polyacrylic acid and polyimide.

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

[0023] As a preferred embodiment, the mass ratio of the melamine, the polyacrylic acid and the 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 lignin sulfonate.

[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 the S3, the spray granulation inlet temperature is 160-220℃, the outlet temperature is 80-105℃, 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 the S3, the spray granulation inlet temperature is 200-205℃, the outlet temperature is 100-105℃, 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 mixed particles and the coating agent is 1:(8-10).

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

[0031] As a preferred embodiment, the D50 average particle size of the silicon-carbon mixed 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: mixing and stirring mesophase pitch, ammonium polyphosphate, polyphosphazene and phenylboric acid to obtain a mixture; S2: transferring the mixture to a tube furnace, and promoting raw material fusion through secondary staged high-temperature treatment; S3: rapidly cooling the product, ball milling and sieving, and obtaining the product.

[0034] As a preferred embodiment, the preparation method of the modified asphalt specifically comprises the following steps: S1: crushing mesophase pitch to a particle size of 0.5-1 mm, and mixing and adding ammonium polyphosphate, polyphosphazene and phenylboric acid into a double-planetary stirrer, stirring at a speed of 150-200 rpm under nitrogen protection at 260-280℃ for 2.5-3 h to obtain a mixture; S2: transferring the mixture to a tube furnace, and raising the temperature to 400℃ at a rate of 4-5℃ / min in an inert atmosphere and maintaining for 1-1.5 h, and then raising the temperature to 900-1000℃ at a rate of 3-4℃ / min and maintaining for 2-3 h; S3: rapidly cooling the product with liquid nitrogen, ball milling and sieving through a 600-800 mesh sieve, and obtaining the product.

[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] The addition of the modified asphalt as a coating agent can greatly improve the electrical performance and cycle performance of the negative electrode material. The ammonium polyphosphate in the modified asphalt decomposes to generate PO4 3-, which reacts with the silicon surface to form Li3PO4, its high ionic conductivity, promotes lithium ion transmission, while inhibiting the direct contact of silicon and electrolyte, and the high-temperature pyrolysis of polyphosphazene generates P / N co-doped carbon skeleton, wherein the N atoms (pyridine nitrogen, graphite nitrogen) provide electron conduction sites, and the P atoms (P-O bonds) enhance the compatibility of the carbon layer with the electrolyte; on the other hand, the phenyl borate cross-linking network is retained after carbonization, and the improved elastic modulus effectively inhibits the rupture of the coating layer caused by the expansion of silicon, and the modified asphalt can form a certain degree of gradient structure, and the outer layer of asphalt assists the high graphitization carbon layer formed by carbonization to provide fast electron conduction, while the inner layer can accelerate the diffusion of lithium ions through the defect sites of the derived P / N doped carbon.

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

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

[0041] The application further limits the application of the high tap density spherical silicon-carbon negative electrode material in the field of electronic equipment and electric vehicles.

[0042] The application has the following beneficial effects:

[0043] 1. The preparation method of the high tap density spherical silicon-carbon negative electrode material provided in the application improves the volume expansion of the silicon-based negative electrode and improves the tap density; the sanding mixing technology improves the uneven mixing of the material in the precursor slurry of the spray granulation technology, and the binder and the coating agent can realize secondary coating of the particles after carbonization, the capacity of the silicon-carbon negative electrode battery after coating is stable, and the cycle performance is better, which has wide application potential.

[0044] 2. The preparation method of the high tap density spherical silicon-carbon negative electrode material provided in the application can effectively improve the electrical performance and stability of the negative electrode material by adding a composite binder, wherein melamine as the main binder forms a three-dimensional rigid network through triazine ring cross-linking at high temperature, provides structural support, inhibits the volume expansion of silicon particles, and its flexible segment containing carboxyl forms hydrogen bonds with the silicon surface hydroxyl group during the drying stage, and condensation reaction occurs between the amino group (-NH2) of melamine and the carboxyl group during the carbonization process, generating amide bonds to enhance the toughness of the network; on the other hand, the nitrogen-doped carbon generated after carbonization of melamine resin provides an electron transport channel, reduces the charge transfer impedance, and the carbon layer formed by carbonization of polyimide expands the lithium ion intercalation channel, while forming a gradient conductive interface with the nitrogen-doped carbon of melamine.

[0045] 3、The preparation method of the high-tapped-density spherical silicon-carbon negative electrode material provided in the application, the ammonium polyphosphate added in the modified pitch decomposes to generate PO4 3- reacts with the silicon surface to form Li3PO4, which has high ion conductivity and promotes lithium ion transmission, while inhibiting direct contact between silicon and electrolyte, and the polyphosphazene high-temperature cracking generates P / N co-doped carbon skeleton, in which N atoms (pyridine nitrogen, graphite nitrogen) provide electron conduction sites and P atoms (P-O bonds) enhance the compatibility of the carbon layer with electrolyte; on the other hand, the phenyl boronic acid crosslinking network is retained after carbonization, and the improved elasticity modulus effectively inhibits the rupture of the coating layer caused by silicon expansion, and the modified pitch can form a gradient structure to some extent, the outer layer of pitch assists the high-graphitized carbon layer formed by carbonization to provide fast electron conduction, while the inner layer can accelerate lithium ion diffusion through the defect sites of the derived P / N doped carbon. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 The SEM image of the high-tapped-density spherical silicon-carbon negative electrode material prepared in Example 1 of the application.

[0047] Figure 2 The SEM image of the high-tapped-density spherical silicon-carbon negative electrode material prepared in Example 2 of the application.

[0048] Figure 3 The cycle performance test result graph of the high-tapped-density spherical silicon-carbon negative electrode material prepared in Example 1 of the application at a current density of 0.1C. DETAILED DESCRIPTION

[0049] In the detailed description, the content in the inventive content of the application will be more intuitively displayed and explained through specific implementation cases.

[0050] Example 1

[0051] The preparation method of the high-tapped-density spherical silicon-carbon negative electrode material specifically includes the following steps: S1: obtaining graphite after shaping treatment to obtain shaped graphite; S2: adding the shaped graphite, nano-silicon, binder and dispersing agent into ethanol and performing sand milling treatment in a sand mill to obtain a silicon-carbon mixed slurry; S3: performing spray granulation on the silicon-carbon mixed slurry to obtain silicon-carbon mixed particles; S4: mixing and coating the silicon-carbon mixed particles with a coating agent for carbonization, crushing and sieving to obtain the high-tapped-density spherical silicon-carbon negative electrode material.

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

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

[0054] In S2, the sanding treatment speed 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 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 combination of melamine, polyacrylic acid and polyimide, with a mass ratio of 5:3:1.

[0058] The melamine is purchased from the product of type 303 sold by BASF, Germany; the polyacrylic acid is purchased from the product of superior grade sold by LANABAI Pharmaceutical Chemical Co., Ltd., Wuhan, China; and the polyimide is purchased from the product of type HN sold by DuPont, USA.

[0059] The dispersant is polyvinylpyrrolidone K30.

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

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

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

[0063] The coating agent is modified asphalt, and the preparation method of the modified asphalt, in parts by mass, specifically includes the following steps: S1: crushing 10 parts of mesophase pitch to a particle size of 0.8 mm, mixing with 1.5 parts of ammonium polyphosphate, 1 part of polyphosphazene and 0.4 part of phenylboric acid into a double planetary mixer, stirring at 260℃ under nitrogen protection at a speed of 180 rpm for 3h to obtain a mixture; S2: transferring the mixture to a tube furnace, raising to 400℃ at a rate of 5℃ / min under inert atmosphere and keeping for 1h, then raising to 950℃ at a rate of 4℃ / min and keeping for 3h; S3: ball milling the product after liquid nitrogen quenching, and then passing through a 600 mesh sieve to obtain the modified asphalt.

[0064] The mesophase pitch is purchased from the mesophase pitch product for coating sold by Hebei Derixin Material Technology Co., Ltd., China; the ammonium polyphosphate is purchased from the industrial grade product sold by Shandong Zhijia Chemical Technology Co., Ltd., China; and the polyphosphazene is purchased from the industrial grade polydiphenyloxyphosphazene product sold by Hubei Xingheng Industry Technology Co., Ltd., China.

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

[0066] In S4, the coating temperature of the carbonization-coating is 700°C, and the coating time is 5h.

[0067] Example 2

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

[0069] In S4, the coating temperature of the carbonization-coating is 900°C, and the coating time is 6h.

[0070] Example 3

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

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

[0073] Example 4

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

[0075] In S4, the coating temperature of the carbonization-coating is 900°C, and the coating time is 5h.

[0076] Comparative Example 1

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

[0078] Comparative Example 2

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

[0080] Comparative Example 3

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

[0082] Comparative Example 4

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

[0084] Comparative Example 5

[0085] The only difference between this comparative example and Example 1 is that the coating agent is modified asphalt. The preparation method of the modified asphalt, by mass, specifically includes the following steps: S1: 18.5 parts of mesophase asphalt are crushed to a particle size of 0.8 mm, mixed with 0.8 parts of ammonium polyphosphate, 1.8 parts of polyphosphazene and 0.2 parts of phenylboronic acid, and added to a double planetary mixer. The mixture is stirred at 180 rpm for 3 hours under nitrogen protection at 260°C to obtain a mixture; S2: The mixture is transferred to a tube furnace, heated to 400°C at 5°C / min and held for 1 hour under an inert atmosphere, and then heated to 950°C at 4°C / min and held for 3 hours; S3: The product is rapidly cooled with liquid nitrogen and then ball-milled, and then passed through a 600-mesh sieve to obtain the final product.

[0086] Comparative Example 6

[0087] The only difference between this comparative example and Example 1 is as follows: the coating agent is modified asphalt, and the preparation method of the modified asphalt, by mass, specifically includes the following steps: S1: 8.5 parts of mesophase asphalt are crushed to a particle size of 0.8 mm, mixed with 2.8 parts of ammonium polyphosphate, 0.5 parts of polyphosphazene and 0.1 parts of phenylboronic acid, and added to a double planetary mixer. The mixture is stirred at 180 rpm for 3 hours under nitrogen protection at 260°C to obtain a mixture; S2: The mixture is transferred to a tube furnace, heated to 400°C at 5°C / min and held for 1 hour under an inert atmosphere, and then heated to 950°C at 4°C / min and held for 3 hours; S3: The product is rapidly cooled with liquid nitrogen and then ball-milled, and then passed through a 600-mesh sieve to obtain the final product.

[0088] Performance Evaluation

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

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

[0091] The half-cell test method is as follows: The silicon-carbon anode material prepared in the examples and comparative examples is used as the active material. It is weighed with conductive agent (SP) and binder (PVDF) in a ratio of 8:1:1. After mixing, N-methylpyrrolidone is added and stirred evenly to form a negative electrode slurry. The slurry is coated on copper foil and the coated electrode is placed in a vacuum drying oven at 100°C for 12 hours for later use.

[0092] Half-cell preparation and electrochemical performance test: the half-cell was assembled in an argon-filled glove box, the electrolyte was 1M LiPF6+ EC:DEC:DMC=1:1:1 (volume ratio), lithium metal was the counter electrode, and the electrochemical performance test was carried out on a LADN battery tester, the charge and discharge voltage range was 0.005 to 1.5 V, and the cycle performance of the battery at 0.1C rate 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 achieved worse performance results relative to the examples, while the examples had higher discharge capacity and battery cycle performance while ensuring high tap density. This is because the examples used the better technical solution defined in the application to produce better modified bitumen, and through the joint action of the aforementioned composite binder, the overall performance of the negative electrode material was greatly improved.

Claims

1. A method for preparing a high tap-density spheroidized silicon-carbon negative electrode material, characterized by comprising the following steps: S1: obtaining graphite after shaping treatment to obtain shaped graphite; S2: adding the shaped graphite, nano-silicon, binder and dispersant into ethanol and sanding treatment in a sand mill to obtain a silicon-carbon mixed slurry; S3: spray granulation of the silicon-carbon mixed slurry to obtain silicon-carbon mixed particles; S4: mixing and coating the silicon-carbon mixed particles with a coating agent, carbonizing, crushing and screening to obtain a high tap density spherical silicon-carbon negative electrode material; ​ The frequency of the shaping treatment in the S1 is 40-50 Hz, the time is 60-100 min, and the tap density of the shaped graphite after the shaping treatment is 0.8-1 g / cm 3 , and the D50 average particle size is 6-10 μm. In the 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 combination of melamine, polyacrylic acid and polyimide, and the mass ratio is (5-5.5):(2.5-3):(1-1.2); The coating agent is modified asphalt; The preparation method of the modified asphalt specifically includes the following steps: S1: mixing and stirring intermediate phase asphalt with ammonium polyphosphate, polyphosphazene and phenylboric acid to obtain a mixture; S2: transferring the mixture to a tube furnace and promoting raw material fusion through twice sub-section high temperature treatment; S3: product quenching, ball milling and screening, and the modified asphalt is obtained; The D50 average particle size of the modified asphalt is 5-10 μm.

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

3. The method for preparing the high tap density spherical silicon-carbon anode material according to claim 1, characterized in that: The dispersant is at least one of polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, polycarboxylic acid and lignin sulfonate.

4. The method for preparing the high tap density spherical silicon-carbon anode material according to claim 3, characterized in that: In the S3, the spray granulation inlet temperature 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%.

5. The method for preparing the high tap density spherical silicon-carbon anode material according to claim 4, characterized in that: The mass ratio of the silicon-carbon mixed particles and the coating agent is 1:(8-10).

6. The method for preparing the high tap density spherical silicon-carbon anode material according to claim 5, characterized in that: The D50 average particle size of the silicon-carbon mixed particles is 5.5-7.5 μm.

7. Application of the silicon-carbon negative electrode material prepared by the preparation method of the high tap density spherical silicon-carbon negative electrode material according to any one of claims 1-6 in the field of electronic devices and electric vehicles.

Images