Porous carbon-silicon negative electrode material and preparation method thereof

Abstract

The application discloses a kind of porous carbon silicon negative electrode materials and preparation method thereof, belong to new energy material technical field, including porous carbon framework, silicon layer and carbon layer;The porous carbon framework includes macroporous carbon framework and the small pore carbon framework nested in macroporous carbon framework inside;The silicon layer is located at the surface of macroporous carbon framework and in small pore carbon framework;The carbon layer is coated on the surface of macroporous carbon framework silicon layer and in the silicon layer located in small pore carbon framework.This application shows a kind of porous carbon silicon negative electrode material, and the lithium ion battery can be prepared using the negative electrode material, and the lithium ion battery prepared has high first efficiency, low expansion and long cycle and the like advantages.

Description

TECHNICAL FIELD

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

[0002] Various anode materials have been proposed in the past decade to improve the storage capacity and thermal stability of lithium ion batteries (LIBs). Silicon (Si) has been extensively studied as an anode active material in lithium ion batteries due to its remarkable properties. Based on the intercalation ratio of one lithium (Li) per six carbon (C) atoms, the theoretical specific capacity of carbon active materials is 372 milliampere per gram. The use of lithium to C atom ratio of 1 / 6 in full carbon materials can form silicon and lithium alloys with a higher lithium to silicon ratio. In these alloys, the Li / Si ratio of the alloy phase (theoretical capacity of 1636 milliampere hours per gram) ranges from 1.71 to 3.75. The most abundant Li 15 Si4 (theoretical capacity of 3579 milliampere hours per gram) has a Li / Si ratio of 3.75. The most abundant Li 22 Si5 alloy phase has a ratio of 4.4, with a theoretical capacity of 4200 mAh / g. In addition to the high specific capacity, the voltage of silicon is slightly higher than that of the graphite platform, so it has an attractive safety feature. In addition, silicon is an abundant and inexpensive material, and lithium is more stable than graphite in typical lithium ion battery electrolytes.

[0003] However, the silicon material itself has poor electrical conductivity, and it has a serious volume effect during the lithium insertion and extraction process, with a volume change rate of about 400%, which can cause the electrode material to pulverize and the electrode material to separate from the current collector. In addition, due to the volume effect during the charging and discharging process, the silicon negative electrode material exposed to the electrolyte continuously forms a fresh surface, thus continuously consuming the electrolyte to generate an SEI film, reducing the cycle performance of the electrode material. The above defects of silicon-based materials severely limit their commercial application. SUMMARY

[0004] In order to solve the above problems in the prior art, the present application aims to provide a porous carbon-silicon negative electrode material and a preparation method thereof. The negative electrode material can be used to prepare a lithium ion battery, and the prepared lithium ion battery has the advantages of high initial efficiency, low expansion, and long cycle.

[0005] The technical scheme adopted by the present application to solve its technical problems is:

[0006] A porous carbon-silicon negative electrode material is provided, comprising a porous carbon skeleton, a silicon layer and a carbon layer.

[0007] The porous carbon skeleton comprises a large-pore carbon skeleton and a small-pore carbon skeleton nested inside the large-pore carbon skeleton.

[0008] The silicon layer is located on the surface of the macroporous carbon framework and in the microporous carbon framework.

[0009] The carbon layer is coated on the surface of the macroporous carbon framework silicon layer and in the silicon layer located in the microporous carbon framework.

[0010] Further, the specific surface area of the porous carbon silicon negative electrode material is 1-200m 2 / g, or the particle size D 50 of the porous carbon silicon negative electrode material is 2-40μm.

[0011] Further, the pore size D 50 of the macroporous carbon framework is distributed in 200-2000nm, the pore size D 50 of the microporous carbon framework is distributed in 2-50nm, and the mass ratio of the microporous carbon framework to the macroporous carbon framework is 60-98%.

[0012] Further, the mass fraction of the silicon layer in the negative electrode material is 2-70%, or the thickness of the silicon layer is 1-40nm, and the silicon layer is one or more of elemental silicon material, silicon alloy material, silicon-carbon material and silicon-oxygen material.

[0013] Or, the thickness of the carbon layer is 3-120nm.

[0014] Further, the porous carbon silicon negative electrode material further comprises a carbon modification layer, which is located at the interface where the carbon layer and the silicon layer contact, and the thickness of the carbon modification layer is 0.2-10nm.

[0015] A preparation method of a porous carbon silicon negative electrode material, comprising:

[0016] S1: After mixing the macroporous carbon framework and the solution one, the solution two and the solution three are added in sequence, and after stirring, solidification reaction and high-temperature carbonization, a porous carbon framework containing a microporous carbon framework is obtained;

[0017] S2: The porous carbon framework is taken out and placed in a rotary furnace, silane and nitrogen are introduced into the rotary furnace, and a mesoporous porous carbon silicon composite material with a silicon layer deposited in the carbon pores is obtained by high-temperature silane deposition;

[0018] S3: After the silane deposition is completed, a carbon-containing gas and a protective gas are introduced into the rotary furnace, and a porous carbon silicon negative electrode material containing a carbon layer is obtained by high-temperature deposition.

[0019] Further, in step S1, the macroporous carbon framework is one or more of wood activated carbon, modified coconut shell activated carbon, modified coal activated carbon and modified fruit shell activated carbon, the pore size D 50 is 200-2000nm, and the specific surface area is 300-600m 2 / g.

[0020] Or, the first solution solute is one or more of phenol, m-dihydroxybenzene, o-dihydroxybenzene, p-dihydroxybenzene, m-trihydroxybenzene, bisphenol A; the mass concentration of the first solution is 10-50%;

[0021] Or, the second solution solute is one or more of 2-propenal, 2-butenal, 3-butenal, salicylaldehyde, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, cinnamaldehyde; the mass concentration of the second solution is 10-35%;

[0022] Or, the third solution solute is sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide; the mass concentration of the third solution is 1-8%;

[0023] Or, the solvent of the first solution, the second solution, and the third solution is one or more of water, ethanol, butanol, and acetone;

[0024] Or, the mass ratio of the macroporous carbon: the first solution solute: the second solution solute: the third solution solute is (30-50):(40-70):(20-40):(0.1-2).

[0025] Further, the macroporous carbon framework is stirred and mixed with the first solution, the second solution, and the third solution at room temperature, the stirring speed is 200-600 rpm, and the stirring and mixing time is 1-8 h;

[0026] The solidification reaction temperature is 60-140℃, and the solidification reaction time is 5-20 h;

[0027] The carbonization reaction temperature is 600-1200℃, and the carbonization reaction time is 2-6 h;

[0028] In the porous carbon framework, the pore diameter of the microporous carbon framework is <50 nm, and the specific surface area is >600 m 2 / g.

[0029] Further, in step S2, the silane is any one or more of monosilane, disilane, trisilane, tetrasilane, chlorosilane, and silicon tetrachloride;

[0030] The silane inlet amount is 0.5-10 L / min;

[0031] The argon protection gas inlet amount is 0.2-2 L / min;

[0032] The rotary furnace rotation speed is 0.5-5 r / min; the high-temperature silane deposition temperature is 500-1000℃, and the deposition time is 2-8 h;

[0033] The thickness of the silicon layer is 3-15 nm.

[0034] Further, in step S3, the carbon-containing gas is one or more of methane, ethane, propane, acetylene, ethylene;

[0035] The carbon-containing gas is introduced at a flow rate of 0.2-10 L / min;

[0036] The protective gas is argon, and the argon is introduced at a flow rate of 0.5-3 L / min;

[0037] The rotary furnace rotates at a speed of 1-8 r / min, the deposition temperature is 800-1400℃, and the deposition time is 3-10 h.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] 1. The porous carbon-silicon negative electrode material of the present application has a porous carbon framework that can act as a channel during the deposition of silicon and carbon, and more silicon and carbon can be deposited in the small pores.

[0040] 2. The porous carbon-silicon negative electrode material of the present application has a small-pore carbon framework structure that can slow down the volume expansion effect of the silicon-based material.

[0041] 3. The porous carbon-silicon negative electrode material of the present application has silicon based on the carbon framework and the carbon layer, which can improve the conductivity and rate performance of the silicon material.

[0042] 4. The porous carbon-silicon negative electrode material of the present application can be used to prepare lithium ion batteries, and the prepared lithium ion batteries have high initial efficiency, low expansion, and long cycle life, effectively avoiding material pulverization during the cycle process, improving the cycle performance, and maintaining a capacity retention rate of 90% or more after 600 cycles. BRIEF DESCRIPTION OF DRAWINGS

[0043] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the accompanying drawings:

[0044] Figure 1 The electron microscope image of the porous carbon-silicon negative electrode material of Example 1.

[0045] Figure 2 The cycle performance graph of the porous silicon-carbon negative electrode material of Example 1 applied to a lithium battery.

[0046] In the figure: 1 - large-pore carbon framework, 2 - small-pore carbon framework, 3 - silicon layer, 4 - carbon layer. DETAILED DESCRIPTION

[0047] The application will be described in further detail below with reference to the drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the application and are not intended to limit the application. In addition, it should be noted that only parts related to the application are shown in the drawings for ease of description.

[0048] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and embodiments.

[0049] A porous carbon-silicon negative electrode material includes a porous carbon framework, a silicon layer 3, and a carbon layer 4. Specifically:

[0050] The porous carbon framework includes a large-pore carbon framework 1 and a small-pore carbon framework 2 nested inside the large-pore carbon framework 1, and gaps exist between the small-pore carbon frameworks; the silicon layer 3 is located on the surface of the large-pore carbon framework 1 and in the small-pore carbon framework 2; and the carbon layer 4 is coated on the surface of the silicon layer 3 of the large-pore carbon framework 1 and the silicon layer 3 located in the small-pore carbon framework 2.

[0051] The specific surface area of the porous carbon-silicon negative electrode material is 1-200 m 2 / g, the particle size D 50 of the porous carbon-silicon negative electrode material is 2-40 μm.

[0052] The pore size D 50 of the large-pore carbon framework 1 is distributed in a range of 200-2000 nm, the pore size D 50 of the small-pore carbon framework 2 is distributed in a range of 2-50 nm, and the mass ratio of the small-pore carbon framework 2 to the large-pore carbon framework 1 is 60-98%.

[0053] The silicon layer 3 includes one or more of elemental silicon material, silicon alloy material, silicon-carbon material, and silicon-oxygen material, the mass fraction of the silicon layer 3 in the negative electrode material is 2-70%, and the thickness of the silicon layer 3 is 1-40 nm.

[0054] The thickness of the carbon layer 4 is 3-120 nm.

[0055] In addition, the porous carbon-silicon negative electrode material further includes a carbon modification layer, the carbon modification layer is located at the interface where the carbon layer 4 and the silicon layer 3 contact, and the thickness of the carbon modification layer is 0.2-10 nm.

[0056] Embodiment 1:

[0057] As Figure 1 shown, the embodiment provides a preparation method of a porous carbon-silicon negative electrode material, and the steps are as follows:

[0058] Take 50 parts of modified coconut shell activated carbon (D 50500nm) and 50 parts of a 30% phenol aqueous solution, 25 parts of a 20% formaldehyde aqueous solution, and 0.1 parts of a 1% sodium carbonate aqueous solution, stirred at 200 rpm for 8 h, and then solidified at 90°C for 15 h, and then carbonized at 1000°C for 3 h to obtain the porous carbon skeleton 2 containing small pores.

[0059] Then, the rotary furnace was supplied with a benzene silane gas at a flow rate of 4 g / min, and argon protective gas at a flow rate of 1 L / min, and the silane deposition temperature was 900°C, the silane deposition time was 6 h, and the rotary furnace speed was 2.5 r / min.

[0060] After the deposition of the silicon layer 3 was completed, the rotary furnace was supplied with propane gas at a flow rate of 2 L / min, and argon gas at a flow rate of 1 L / min, and the carbon deposition temperature was 900°C, the carbon deposition time was 5 h, and the rotary furnace speed was 5 r / min.

[0061] The preparation method of the porous silicon-carbon negative electrode material electrode is also provided in the embodiment.

[0062] The porous silicon-carbon negative electrode material 80 parts, SP 10 parts, and CMC 10 parts were mixed to obtain a slurry, and the slurry was coated on a copper foil, wherein the coating thickness was 200 μm, and the slurry was sequentially subjected to drying at 100°C for 240 min, rolling once, and cutting into an electrode piece with a diameter of 12 mm to obtain the silicon nanowire electrode.

[0063] The scanning electron microscope (SEM) image of the porous carbon-silicon negative electrode material prepared in the embodiment is shown in FIG. 2. Figure 1 The cycle performance of the porous silicon-carbon negative electrode material electrode prepared in the embodiment is shown in FIG. 3. Figure 2

[0064] Embodiment 2:

[0065] 50 parts of wood-based activated carbon (D 50 600nm) and 40 parts of a 30% resorcinol ethanol solution, 20 parts of a 20% acetaldehyde aqueous solution, and 0.1 parts of a 1% sodium carbonate ethanol solution; stirred at 300 rpm for 6 h, and then solidified at 100°C for 13 h, and then carbonized at 900°C for 4 h.

[0066] Then, the rotary furnace was supplied with a benzene silane gas at a flow rate of 4 g / min, and argon protective gas at a flow rate of 1 L / min, and the silane deposition temperature was 900°C, the silane deposition time was 6 h, and the rotary furnace speed was 2.5 r / min.

[0067] ​After the deposition of the silicon layer 3, ethylene is introduced into the rotary furnace at a flow rate of 6 g / min, argon is introduced at a flow rate of 1.5 L / min, the carbon deposition temperature is 1300°C, the carbon deposition time is 3 h, and the rotary furnace speed during carbon deposition is 7 r / min.

[0068] Example 3:

[0069] Take 30 parts of modified coal quality activated carbon (D 50 300nm) and 70 parts of 30% bisphenol A ethanol solution, 35 parts of 15% benzaldehyde aqueous solution, and 0.1 parts of 2% sodium hydroxide ethanol solution; after stirring at 400 rpm for 7 h, solidification reaction at 120°C for 16 h, and then carbonization reaction at 1100°C for 6 h.

[0070] Then introduce tetrasilane into the rotary furnace at a flow rate of 2 g / min, introduce argon at a flow rate of 0.8 L / min, the silane deposition temperature is 600°C, the silane deposition time is 7 h, and the rotary furnace speed during silane deposition is 4 r / min.

[0071] After the deposition of the silicon layer 3, ethylene is introduced into the rotary furnace at a flow rate of 6 g / min, argon is introduced at a flow rate of 1.5 L / min, the carbon deposition temperature is 1300°C, the carbon deposition time is 3 h, and the rotary furnace speed during carbon deposition is 7 r / min.

[0072] Example 4:

[0073] Take 40 parts of wood activated carbon mixed with modified shell activated carbon (D 50 350nm) and 50 parts of 20% phloroglucinol acetone solution, 25 parts of 15% 2-butenal acetone solution, and 0.5 parts of 1% potassium hydroxide acetone solution; after stirring at 500 rpm for 5 h, solidification reaction at 130°C for 12 h, and then carbonization reaction at 1200°C for 6 h.

[0074] Then introduce triethylsilane into the rotary furnace at a flow rate of 5 g / min, introduce argon at a flow rate of 2 L / min, the silane deposition temperature is 1000°C, the silane deposition time is 4 h, and the rotary furnace speed during silane deposition is 5 r / min.

[0075] After the deposition of the silicon layer 3, methane is introduced into the rotary furnace at a flow rate of 10 g / min, argon is introduced at a flow rate of 3 L / min, the carbon deposition temperature is 1400°C, the carbon deposition time is 4 h, and the rotary furnace speed during carbon deposition is 8 r / min.

[0076] Comparative Example 1:

[0077] The comparative example provides a preparation process and performance test of a conventional silicon-carbon composite material prepared by a spray drying method. The specific preparation process is as follows:

[0078] In an ethanol system, silicon particles, graphite, a dispersant, and a carbon source precursor are added, and sanding is performed to obtain a dispersion liquid. The dispersion liquid is subjected to spray drying to obtain a silicon-containing composite material. The silicon-carbon composite material prepared is subjected to carbon coating. Specifically, 1 kg of the silicon-containing composite material is placed in a rotary furnace, heated to 800°C under a protective atmosphere, argon and methane gas are introduced at a volume ratio of 2.5:1 for gas phase coating, and the organic gas source is turned off after 3 hours of heat preservation. After the temperature is reduced to room temperature, the material is discharged, and a silicon-carbon composite material with a carbon coating layer is obtained.

[0079] The porous silicon-carbon negative electrode material prepared in Examples 1-4 and Comparative Example 1 is mixed with 80 parts of the porous silicon-carbon negative electrode material, 10 parts of SP, and 10 parts of CMC to obtain a slurry, the slurry is coated on a copper foil, the coating thickness is 200 μm, and the slurry is subjected to 100°C drying for 240 min, one-time rolling, and cutting into an electrode piece with a diameter of 12 mm in sequence to obtain a silicon nanowire electrode. The electrode is assembled into a lithium ion battery, and the lithium ion battery is subjected to cycle performance test and discharge performance test. The test results are shown in Table 1.

[0080] The lithium ion battery is assembled by using 1 mol / L lithium hexafluorophosphate as the electrolyte, ethyl carbonate + dimethyl carbonate (volume ratio of ethyl carbonate to dimethyl carbonate is 1:1-1:3) as the solvent, lithium sheet as the corresponding electrode, and Lelgard2400 separator to prepare a CR2032 button cell. The constant current charge-discharge test is performed by using a blue cell detection system, and the half-cell is subjected to charge-discharge test by using a 0.1C current. The test temperature is 25°C.

[0081] Table 1 Cycle performance test and discharge performance test of lithium ion battery

[0082]

[0083] From the above table, it can be seen that the porous silicon-carbon negative electrode material electrodes obtained in Examples 1-4 are applied to the battery. The large pore carbon framework 1 provides a silicon source and a carbon source path, can deposit sufficient silicon and carbon in the small pore carbon framework 2, and the silicon is located between the carbon framework and the deposited carbon, which can improve the conductivity and rate performance of the silicon material. It can also provide sufficient space for the expansion of lithium intercalation silicon and prevent stress expansion and even breakage caused by lithium intercalation silicon. The mesoporous structure of the porous silicon F carbon negative electrode material slows down the volume expansion effect of the silicon-based material, effectively avoids material pulverization during the cycle process, and improves the cycle performance. The lithium ion battery silicon-carbon negative electrode material has the advantages of high initial efficiency, low expansion, and long cycle, and the capacity retention rate is more than 90% after 600 cycles.

[0084] Those skilled in the art should understand that the application scope of the application involved in the present application is not limited to the technical solutions formed by the specific combinations of the technical features described above, and should also cover other technical solutions formed by any combinations of the technical features described above or their equivalent features without departing from the inventive concept. For example, technical solutions formed by mutually replacing the technical features described above and the technical features disclosed in the present application (but not limited to) having similar functions.

Claims

1. A porous carbon-silicon anode material, characterized in that, The porous carbon skeleton, the silicon layer (3) and the carbon layer (4); The porous carbon skeleton comprises a large-pore carbon skeleton and a small-pore carbon skeleton (2) nested inside the large-pore carbon skeleton (1); the large-pore carbon skeleton (1) has a pore size D 50 The small-pore carbon skeleton (2) has a diameter distribution of 200-2000 nm, and a pore size D 50 The small-pore carbon skeleton (2) has a diameter distribution of 2-50 nm, and the mass ratio of the small-pore carbon skeleton (2) to the large-pore carbon skeleton (1) is 60-98%. The silicon layer (3) is located on the surface of the macroporous carbon skeleton (1) and in the microporous carbon skeleton (2); The carbon layer (4) is coated on the surface of the silicon layer (3) of the macroporous carbon skeleton (1) and in the silicon layer (3) located in the microporous carbon skeleton (2); The specific surface area of ​​the porous silicon carbide anode material is 1-200 m². 2 / g, Particle size D of porous silicon carbon anode material 50 It ranges from 2 to 40 μm.

2. The porous carbon-silicon negative electrode material of claim 1, wherein, The mass fraction of the silicon layer (3) in the negative electrode material is 2-70%, or the thickness of the silicon layer (3) is 1-40nm, and the silicon layer (3) is one or more of elemental silicon material, silicon alloy material, silicon-carbon material and silicon-oxygen material; Or, the thickness of the carbon layer (4) is 3-120nm.

3. The porous carbon-silicon anode material of claim 1, wherein, The porous carbon-silicon negative electrode material further comprises a carbon modification layer, the carbon modification layer is located at the interface where the carbon layer (4) and the silicon layer (3) contact, and the thickness of the carbon modification layer is 0.2-10nm.

4. A method of producing the porous carbon-silicon negative electrode material according to claim 1, characterized by, Comprise: S1: After mixing the macroporous carbon skeleton (1) and solution one, solution two and solution three are added in turn, and after stirring mixing, curing reaction and high-temperature carbonization, a porous carbon skeleton containing microporous carbon skeleton (2) is obtained; S2: The porous carbon skeleton is taken out and placed in a rotary furnace, silane and argon are introduced into the rotary furnace, and a mesoporous porous carbon-silicon composite material with a silicon layer (3) deposited in the carbon pores is obtained by high-temperature silane deposition; S3: After the silane deposition is completed, a carbon-containing layer (4) is introduced into the rotary furnace, and a porous carbon-silicon negative electrode material is obtained by high-temperature deposition of the carbon-containing layer (4); The solute of the solution one is one or more of phenol, m-dihydroxybenzene, o-dihydroxybenzene, p-dihydroxybenzene, phloroglucinol and bisphenol A; the mass concentration of the solution one is 10-50%; The solute of the solution two is one or more of 2-propenal, 2-butenal, 3-butenal, salicylaldehyde, formaldehyde, acetaldehyde, propyl aldehyde, butyl aldehyde, benzaldehyde and cinnamaldehyde; the mass concentration of the solution two is 10-35%; The solute of the solution three is sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide and potassium hydroxide; the mass concentration of the solution three is 1-8%; The solvent of the solution one, the solution two and the solution three is one or more of water, ethanol, butanol and acetone; The mass ratio of the macroporous carbon: the solute of the solution one: the solute of the solution two: the solute of the solution three is (30-50):(40-70):(20-40):(0.1-2).

5. The method for preparing porous silicon-carbon anode material according to claim 4, characterized in that, In step S1, the macroporous carbon skeleton (1) is one or more of a wooden activated carbon, a modified coconut shell activated carbon, and a modified coal-based activated carbon, and the pore diameter D 50 is 200-2000 nm, and the specific surface area is 300-600 m 2 / g.

6. The method of claim 4, wherein the porous carbon-silicon negative electrode material is prepared by the steps of: mixing a carbon source and a silicon source; and heating the mixture to a temperature of 800-1,200°C under an inert gas atmosphere. The stirring mixing of the macroporous carbon skeleton and the solution one, the solution two and the solution three is at room temperature, the rotating speed is 200-600rpm, and the stirring mixing time is 1-8h; The curing reaction temperature is 60-140℃, and the curing reaction time is 5-20h; The carbonization reaction temperature is 600-1200℃, and the carbonization reaction time is 2-6h; In the porous carbon skeleton, the small pore carbon skeleton (2) has a pore diameter < 50 nm, a specific surface area > 600 m 2 / g.

7. The method of claim 4, wherein the porous carbon-silicon negative electrode material is prepared by a process comprising: mixing a carbon source and a silicon source; and heating the mixture to a temperature of 800-1,200 °C in an inert atmosphere. In step S2, the silane is any one or more of monosilane, disilane, trisilane, tetrasilane, chlorosilane and silicon tetrachloride; The silane introduction amount is 0.5-10L / min; The argon protection gas introduction amount is 0.2-2L / min; The rotating speed of the rotary furnace is 0.5-5r / min; the high-temperature silane deposition temperature is 500-1000℃, and the deposition time is 2-8h; The thickness of the silicon layer (3) is 3-15 nm.

8. The method of claim 4, wherein the porous carbon-silicon negative electrode material is prepared by the steps of: mixing a carbon source and a silicon source to form a mixture; and heating the mixture to form the porous carbon-silicon negative electrode material. In step S3, the carbon-containing gas is one or more of methane, ethane, propane, acetylene, and ethylene; The amount of the carbon-containing gas introduced is 0.2-10 L / min; The protective gas is argon, and the amount of the argon introduced is 0.5-3 L / min; The rotation speed of the rotary furnace is 1-8 r / min, the deposition temperature is 800-1400℃, and the deposition time is 3-10 h.

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