Silicon-carbon composite negative electrode material and preparation method and application thereof

Abstract

The invention relates to a silicon-carbon composite negative electrode material as well as a preparation method and application thereof. The silicon-carbon composite negative electrode material comprises porous carbon, nano silicon particles dispersed in pores of the porous carbon, a conductive nano material, a solid electrolyte material and a carbon coating layer coating the outer surface of the porous carbon, the conductive nano material comprises one or more of carbon quantum dots, carbon nanowires, single-walled carbon nanotubes and multi-walled carbon nanotubes; the solid electrolyte material comprises one or more of an oxide solid electrolyte, a sulfide solid electrolyte and an organic solid electrolyte; when the silicon-carbon composite negative electrode material is applied to the lithium ion battery, the rate capability and the cycling stability of the lithium ion battery can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a silicon-carbon composite negative electrode material and a preparation method and application thereof. Background Art

[0002] Silicon's theoretical capacity is over ten times that of commercially available graphite electrodes, but its volume expansion has been a key challenge in its commercialization. Currently, the mainstream approach to addressing this problem is to combine silicon with carbon materials to form silicon-carbon composites, enhancing conductivity while mitigating volume expansion.

[0003] While current research can produce silicon-carbon composites with relatively stable cycling performance, this often sacrifices the electrode's capacity and rate capability. For example, shrinking silicon particles to the nanoscale, due to the simple physical contact with carbon, can easily degrade electrochemical performance. Another approach, such as preparing nano-silicon particles while simultaneously reducing the size of the carbon material to form a core-shell silicon-carbon composite, can achieve stable cycling performance but often compromises rate capability.

[0004] Therefore, it is necessary to develop a structure that can quickly transport electrons and ions away from silicon and maintain stable contact between silicon and carbon materials, while at the same time ensuring the material's rate performance. Summary of the Invention

[0005] The purpose of the present invention is to address the defects of the existing technology and provide a silicon-carbon composite negative electrode material and its preparation method and application. By depositing ion conductor solid electrolyte and electronic conductor conductive nanomaterial in the pores of porous carbon and then depositing silicon particles, on the one hand, it can ensure stable contact between the nano-silicon particles and carbon in the pores, so that the material has stable electrochemical cycle performance, and on the other hand, it can enable ions and electrons to be rapidly transmitted between carbon and silicon, thereby improving the rate performance; and the carbon coating layer coated on the outer surface of the porous carbon particles not only plays a role in physical protection of the material, but also the defect sites given by its hard carbon structure also provide channels for rapid transmission of ions.

[0006] To achieve the above objectives, in a first aspect, an embodiment of the present invention provides a silicon-carbon composite negative electrode material, the silicon-carbon composite negative electrode material comprising: porous carbon, nano-silicon particles, a conductive nano-material, and a solid electrolyte material dispersed in the pores of the porous carbon, and a carbon coating layer coated on the outer surface of the porous carbon;

[0007] The conductive nanomaterials include: one or more of carbon quantum dots, carbon nanowires, single-walled carbon nanotubes, and multi-walled carbon nanotubes;

[0008] The solid electrolyte material includes one or more of an oxide solid electrolyte, a sulfide solid electrolyte, and an organic solid electrolyte.

[0009] Preferably, the porous carbon has a pore size of 0.1 nm to 10 nm and a specific surface area of ​​150 m 2 / g-3000m 2 / g between;

[0010] The particle size DV50 of the silicon-carbon composite negative electrode material is 0.5 μm-100 μm;

[0011] The thickness of the carbon coating layer is between 2nm and 5nm.

[0012] Preferably, the oxide solid electrolyte comprises: SnO2 and / or Bi2O3;

[0013] The sulfide solid electrolyte includes one or more of SnS2, Li2S, and Bi2S3;

[0014] The organic solid electrolyte includes one or more of polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polypropylene oxide (PPO), and polyvinylidene chloride (PVDC);

[0015] The mass of the porous carbon accounts for 25%-70% of the total mass of the silicon-carbon composite negative electrode material;

[0016] The mass of the nano-silicon particles accounts for 25%-70% of the total mass of the silicon-carbon composite negative electrode material;

[0017] The mass of the conductive nanomaterial accounts for 0.1%-10% of the total mass of the silicon-carbon composite negative electrode material;

[0018] The mass of the solid electrolyte material accounts for 0.1%-10% of the total mass of the silicon-carbon composite negative electrode material;

[0019] The mass of the carbon coating layer accounts for 0.1%-10% of the total mass of the silicon-carbon composite negative electrode material.

[0020] In a second aspect, an embodiment of the present invention provides a method for preparing the silicon-carbon composite negative electrode material according to the first aspect, the preparation method comprising:

[0021] Step S1, preparing porous carbon, specifically, the following process: adding chitosan to a glacial acetic acid solution, stirring for 1 hour, then adding sodium nitrate and continuing to stir for 30 minutes, then dropwise adding an aqueous solution prepared with ferric nitrate, stirring for 1 hour to uniformly mix the chitosan, ferric nitrate, and sodium nitrate, and then freeze-drying to obtain a carbonized precursor; then placing the carbonized precursor in a reaction device and performing a high-temperature carbonization treatment under a protective atmosphere to obtain a metal / carbon composite; then acid-washing the metal / carbon composite and then washing it to neutrality to obtain porous carbon;

[0022] Step S2, placing the porous carbon in a deposition chamber of a vapor deposition furnace, bringing the raw materials of the conductive nanomaterial and the solid electrolyte material into the deposition chamber by a carrier gas, and reacting them at a certain temperature so that the surface of the pores of the porous carbon is coated with the conductive nanomaterial and the solid electrolyte material to obtain an intermediate material;

[0023] Step S3, introducing a silicon-containing compound into a deposition chamber by a carrier gas, performing vapor deposition, and depositing silicon particles in the pores of the intermediate material to obtain a precursor material;

[0024] Step S4: Carbon coating the precursor material to obtain a silicon-carbon composite negative electrode material.

[0025] Preferably, the mass ratio of chitosan, ferric nitrate and sodium nitrate in step S1 is 1:1:1;

[0026] The porosity of the porous carbon is 30%-80%;

[0027] The reaction equipment is: a tube furnace or a box furnace;

[0028] The protective atmosphere includes nitrogen atmosphere or argon atmosphere;

[0029] The high temperature carbonization process is specifically as follows: heating the reaction equipment to 500°C-1000°C and keeping the temperature for 1 hour-6 hours;

[0030] The process of pickling and then washing to neutrality is specifically as follows: reacting the metal / carbon composite with 2 mol / L hydrochloric acid at 20° C.-70° C. for 2 hours-12 hours, and then washing with deionized water to neutrality.

[0031] Preferably, the reaction temperature in step S2 is 600° C. to 1200° C., and the reaction time is 1 hour to 8 hours;

[0032] The carrier gas includes nitrogen or argon; the flow rate of the carrier gas is 2L / min-30L / min;

[0033] The raw materials of the conductive nanomaterials include: one or more of methane, acetylene, toluene, fullerene, xylene, and propylene;

[0034] The raw materials of the solid electrolyte material specifically include: one or more raw materials of oxide solid electrolyte, raw materials of sulfide solid electrolyte, and raw materials of organic solid electrolyte;

[0035] The raw materials of the oxide solid electrolyte specifically include: SnO2 and / or Bi2O3;

[0036] The raw materials of the sulfide solid electrolyte material specifically include: any combination of SnO2 and CS2, Li2CO3 and CS2, Bi2O3 and CS2;

[0037] The raw materials of the organic solid electrolyte include: one or more of polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polypropylene oxide (PPO), and polyvinylidene chloride (PVDC).

[0038] Preferably, the silicon-containing compound in step S3 includes: one or more of metallic silicon vapor, monosilane, trisilane, dichlorosilane, trichlorosilane, and tetrachlorosilane;

[0039] The carrier gas includes nitrogen or argon; the flow rate of the carrier gas is 1L / min-20L / min;

[0040] The temperature of the vapor deposition is 400° C.-1600° C., and the time is 1 hour-20 hours.

[0041] Preferably, the carbon coating method is gas phase carbon coating or liquid phase carbon coating.

[0042] In a third aspect, an embodiment of the present invention provides a negative electrode plate, which includes the silicon-carbon composite negative electrode material described in the first aspect.

[0043] In a fourth aspect, an embodiment of the present invention provides a lithium-ion battery, comprising the negative electrode sheet described in the third aspect.

[0044] An embodiment of the present invention provides a silicon-carbon composite negative electrode material, a preparation method, and an application thereof. By depositing an ion conductor solid electrolyte and an electronic conductor conductive nanomaterial in the pores of porous carbon, and then depositing silicon particles, on the one hand, stable contact between the nano-silicon particles and the carbon in the pores can be ensured, so that the material has stable electrochemical cycle performance. On the other hand, ions and electrons can be quickly transmitted between carbon and silicon, thereby improving rate performance. The carbon coating layer coated on the surface of the porous carbon particles not only plays a role in physical protection of the material, but also the defect sites given by its hard carbon structure also provide channels for rapid transmission of ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Flowchart of the preparation method of the silicon-carbon composite negative electrode material provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0047] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

[0048] An embodiment of the present invention provides a silicon-carbon composite anode material. The silicon-carbon composite anode material comprises porous carbon, nano-silicon particles dispersed within the pores of the porous carbon, a conductive nanomaterial, and a solid electrolyte material, and a carbon coating layer coated on the outer surface of the porous carbon. The particle size (DV50) of the silicon-carbon composite anode material is 0.5 μm to 100 μm.

[0049] Among them, the pore size of porous carbon is 0.1nm-10nm, and the specific surface area is 150m 2 / g-3000m 2 / g; the mass of the porous carbon accounts for 25%-70% of the total mass of the silicon-carbon composite negative electrode material.

[0050] The mass of the nano-silicon particles accounts for 25%-70% of the total mass of the silicon-carbon composite negative electrode material;

[0051] The conductive nanomaterials include: one or more of carbon quantum dots, carbon nanowires, single-walled carbon nanotubes, and multi-walled carbon nanotubes; the mass of the conductive nanomaterials accounts for 0.1%-10% of the total mass of the silicon-carbon composite negative electrode material.

[0052] The thickness of the carbon coating layer is between 2nm and 5nm; the mass of the carbon coating layer accounts for 0.1% to 10% of the total mass of the silicon-carbon composite negative electrode material.

[0053] The solid electrolyte material includes one or more of an oxide solid electrolyte, a sulfide solid electrolyte, and an organic solid electrolyte; the mass of the solid electrolyte material accounts for 0.1%-10% of the total mass of the silicon-carbon composite negative electrode material.

[0054] Specifically, the oxide solid electrolyte includes: SnO2 and / or Bi2O3; the sulfide solid electrolyte includes: one or more of SnS2, Li2S, Bi2S3; the organic solid electrolyte includes: one or more of polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polypropylene oxide (PPO), and polyvinylidene chloride (PVDC).

[0055] The present invention provides a method for preparing the above-mentioned silicon-carbon composite negative electrode material, such as Figure 1 As shown, the specific steps include:

[0056] Step S1, preparing porous carbon, specifically, the following process: adding chitosan to a glacial acetic acid solution, stirring for 1 hour, then adding sodium nitrate and continuing to stir for 30 minutes, then dropwise adding an aqueous solution prepared with ferric nitrate, stirring for 1 hour to uniformly mix the chitosan, ferric nitrate, and sodium nitrate, and then freeze-drying to obtain a carbonized precursor; then placing the carbonized precursor in a reaction device and performing a high-temperature carbonization treatment under a protective atmosphere to obtain a metal / carbon composite; then acid-washing the metal / carbon composite and then washing it to neutrality to obtain porous carbon;

[0057] Among them, the mass ratio of chitosan, ferric nitrate and sodium nitrate is 1:1:1;

[0058] The porosity of porous carbon is 30%-80%;

[0059] The reaction equipment is: tube furnace or box furnace;

[0060] The protective atmosphere includes nitrogen atmosphere or argon atmosphere;

[0061] The specific process of high temperature carbonization treatment is as follows: heating the reaction equipment to 500-1000°C and keeping the temperature for 1-6 hours;

[0062] The process of acid-washing the metal / carbon complex and then washing it to neutrality is as follows: reacting the metal / carbon complex with 2 mol / L hydrochloric acid at 20°C-70°C for 2 hours-12 hours, and then washing it with deionized water to neutrality.

[0063] Step S2, placing the porous carbon in a deposition chamber of a vapor deposition furnace, bringing the raw materials of the conductive nanomaterial and the solid electrolyte material into the deposition chamber by a carrier gas, and reacting them at a certain temperature so that the surface of the pores of the porous carbon is coated with the conductive nanomaterial and the solid electrolyte material to obtain an intermediate material;

[0064] The reaction temperature is 600-1200°C and the reaction time is 1-8 hours.

[0065] The carrier gas includes nitrogen or argon; the flow rate of the carrier gas is 2L / min-30L / min;

[0066] The raw materials of the conductive nanomaterials include: one or more of methane, acetylene, toluene, fullerene, xylene, and propylene; carbon quantum dots, carbon nanowires, single-walled carbon nanotubes, and multi-walled carbon nanotubes are obtained from the raw materials of the conductive nanomaterials, wherein in the process of obtaining the carbon nanowires, single-walled carbon nanotubes, and multi-walled carbon nanotubes, a catalyst needs to be mixed with porous carbon so that the catalyst enters the porous carbon, wherein the mixing method is a conventional known method so that the catalyst can enter the pores of the porous carbon; wherein the catalyst includes ferrocene and / or metal particles, and the metal particles include one or more of Au, Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, and Zn particles;

[0067] The raw materials of the solid electrolyte material in this step include: one or more raw materials of oxide solid electrolyte, raw materials of sulfide solid electrolyte, and raw materials of organic solid electrolyte;

[0068] The raw materials of the oxide solid electrolyte specifically include: SnO2 and / or Bi2O3; the raw materials of the oxide solid electrolyte are brought into the deposition chamber in gaseous form by the carrier gas;

[0069] The raw materials of the sulfide solid electrolyte material specifically include any combination of SnO2 and CS2, Li2CO3 and CS2, Bi2O3 and CS2; the raw materials of the sulfide solid electrolyte material are brought into the deposition chamber in gaseous form by a carrier gas;

[0070] The raw materials of the organic solid electrolyte specifically include: one or more of polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polypropylene oxide (PPO), and polyvinylidene chloride (PVDC);

[0071] When the raw materials of the solid electrolyte material include the raw materials of the organic solid electrolyte, it is necessary to mix the raw materials of the organic solid electrolyte with the porous carbon and then spray granulate them by spray drying to obtain porous carbon containing the raw materials of the organic solid electrolyte in the pores and on the surface; the method of mixing the raw materials of the organic solid electrolyte with the porous carbon is a conventional method, and the raw materials of the organic solid electrolyte can enter the pores of the porous carbon; the spray drying method is a conventional known method, which can be used to meet the requirements of spray granulation.

[0072] Step S3, introducing a silicon-containing compound into a deposition chamber by a carrier gas, performing vapor deposition, and depositing silicon particles in the pores of the intermediate material to obtain a precursor material;

[0073] The silicon-containing compound includes one or more of metallic silicon vapor, monosilane, trisilane, dichlorosilane, trichlorosilane, and tetrachlorosilane;

[0074] The carrier gas includes nitrogen or argon; the flow rate of the carrier gas is 1L / min-20L / min;

[0075] The temperature of the vapor deposition is 400° C. to 1600° C., and the time is 1 hour to 20 hours.

[0076] Step S4, carbon coating the precursor material to obtain a silicon-carbon composite negative electrode material;

[0077] Among them, the carbon coating treatment method can be gas phase carbon coating or liquid phase carbon coating, both of which are conventional methods. Specifically, the liquid phase carbon coating adopted in the embodiment of the present invention is to place the precursor material and the liquid resin in a fusion machine, and carry out a fusion treatment at 400r / min-800r / min for 10 minutes to 30 minutes, and then place it in a tubular furnace for carbonization treatment. The carbonization treatment temperature is 400℃-800℃, and the carbonization treatment time is 30 minutes to 4 hours; wherein the mass ratio of the precursor material to the liquid resin is [99:1]-[9:1], and the liquid resin is specifically liquid phenolic resin.

[0078] The above-mentioned silicon-carbon composite negative electrode material provided in the embodiment of the present invention can be used as a negative electrode active material to prepare a negative electrode plate, and the negative electrode plate can be used in a lithium-ion battery. Since the silicon-carbon composite negative electrode material in the negative electrode plate has good electrochemical stability and a faster ion transmission path, it can improve the rate performance and cycle stability of the lithium-ion battery.

[0079] In order to better understand the technical solution provided by the present invention, the preparation process and characteristics of the silicon-carbon particle negative electrode material of the present invention are respectively described below with multiple specific examples.

[0080] Example 1

[0081] This embodiment provides a preparation process and performance test of a silicon-carbon particle negative electrode material. The specific preparation process is as follows:

[0082] (1) Preparation of porous carbon. The specific process is as follows: add 200 g of chitosan to a 2 wt% glacial acetic acid solution, stir for 1 hour, add sodium nitrate, and continue stirring for 30 minutes, then add ferric nitrate into an aqueous solution and stir for 1 hour to mix chitosan, ferric nitrate, and sodium nitrate evenly (the mass ratio of chitosan, ferric nitrate, and sodium nitrate is 1:1:1), and then obtain a carbonized precursor by freeze drying; then place the carbonized precursor in a box furnace, heat it to 800 ° C under a nitrogen atmosphere, and carbonize it for 3 hours to obtain a metal / carbon complex; place the metal / carbon complex in a 2 mol / L hydrochloric acid solution, react at 70 ° C for 2 hours, and then wash it with deionized water until it is neutral to obtain porous carbon.

[0083] (2) The porous carbon was crushed and sieved, mixed with the catalyst ferrocene and placed in the deposition chamber of a vapor deposition furnace. SnO2, CS2 and methane were brought into the deposition chamber by a carrier gas nitrogen with a flow rate of 2 L / min. The mixture was reacted at 800°C for 4 hours to coat the pores of the porous carbon with multi-walled carbon nanotubes and SnS2 to obtain an intermediate material.

[0084] (3) Monosilane was introduced into the deposition chamber by nitrogen carrier gas at a flow rate of 2 L / min, and vapor deposition was performed at 1200° C. for 10 hours to deposit silicon particles in the pores of the intermediate material to obtain a precursor material.

[0085] (4) The precursor material was carbon-coated. The precursor material and liquid phenolic resin with a mass ratio of 99:1 were placed in a fusion machine, the speed was set to 800 r / min, the fusion time was 10 minutes, and then placed in a tubular furnace and heated to 400°C. The temperature was kept for 1 hour to obtain an 8nm carbon coating layer, and finally a silicon-carbon composite negative electrode material with a particle size Dv50 of 32μm was obtained.

[0086] The silicon-carbon composite negative electrode material prepared in this embodiment was used to prepare negative electrode sheets and assembled into lithium-ion batteries for testing. The specific process is as follows:

[0087] The assembly process of the button half-cell is as follows: the silicon-carbon composite negative electrode material, the conductive additive carbon black, and the binder (the binder is sodium carboxymethyl cellulose and styrene-butadiene rubber in a mass ratio of 1:0.8) are weighed in a 95:2:3 mass ratio, and the slurry is prepared in a beater at room temperature. The prepared slurry is evenly coated on copper foil to a thickness of 220μm, placed in a forced air drying oven at 55°C for 2 hours, cut into circular electrode pieces with a diameter of 14mm, and vacuum-dried in a vacuum drying oven at 100°C for 8 hours. The dried electrode pieces are then transferred to a glove box for standby battery assembly.

[0088] The assembly of the simulated battery was carried out in a glove box containing a high-purity Ar atmosphere. Metallic lithium was used as the counter electrode, a solution of LiPF6 with a molar concentration of 1 mol / L in ethylene carbonate (EC) / dimethyl carbonate (DMC) / diethyl carbonate (DEC) (wherein the volume ratio of EC, DMC, and DEC was 1:1:1) was used as the electrolyte, and a polyethylene (PE) diaphragm was used as the separator to assemble the battery.

[0089] Testing of the coin cell half-cell was performed using a charge / discharge instrument in constant current charge / discharge mode, with a discharge cut-off voltage of 0.005V and a charge cut-off voltage of 2V. Conventional charge / discharge testing was conducted at a current density of C / 10, while discharge rate testing was conducted at a current density of 1C / 3C. Detailed data on the charge capacity and first-cycle coulombic efficiency of the coin cell are shown in Table 1.

[0090] Full battery assembly process: The silicon-carbon composite negative electrode material is combined with graphite with a gram capacity of 350mAh / g to form a composite negative electrode material. The theoretical capacity of the composite negative electrode material is 480mAh / g.

[0091] The resulting composite anode material was assembled into a 5085-sized soft-pack battery for electrochemical performance testing. The negative electrode sheet was prepared by mixing the negative electrode active material (composite anode material), conductive agent (Super P), binder (carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBr)) in a mass ratio of 94.5:2:2:1.5, grinding them into a slurry, and then applying it to copper foil. The positive electrode sheet was prepared by mixing the positive electrode active material (811-type high-nickel ternary material), conductive agent 1 (Super P), conductive agent 2 (single-walled carbon nanotubes (CNTs), and binder (PVDF) in a mass ratio of 95.2:1.8:1:2, grinding them into a slurry, and then applying it to aluminum foil. Eleven negative electrode sheets and ten positive electrode sheets were assembled into a 5085-sized soft-pack battery. The electrolyte used was 1 mol / L LiPF6 (the solvent was ethylene carbonate, dimethyl carbonate, and diethyl carbonate in a volume ratio of 1:1:1).

[0092] Full-cell testing process: Electrochemical testing of soft-pack full-cell batteries was performed using a Blue Electric test system. Constant current charge and discharge tests were performed at various current densities between 2.75 and 4.25 V. The batteries were formed at a rate of 0.05C, followed by capacity separation at a rate of 0.1C. Cycling performance was tested at rates of 1C or 3C. The capacity retention data for the full-cell after 500 cycles at 1C or 3C is shown in Table 1.

[0093] In order to better illustrate the effects of the embodiments of the present invention, comparative example 1 is compared with the above embodiment 1.

[0094] Comparative Example 1

[0095] This comparative example provides a preparation process of a silicon-carbon composite material. The difference from Example 1 is that in step (2), the comparative example does not plate conductive nanomaterials and solid electrolyte materials on the surface of the pores of the porous carbon. The other processes are the same as those in Example 1.

[0096] The silicon-carbon composite material prepared in this comparative example was used to prepare negative electrode sheets and assembled into button-type half-cells and full cells for testing. The battery assembly and testing methods were the same as those in Example 1. The test data are detailed in Table 1.

[0097] Example 2

[0098] This embodiment provides a preparation process and performance test of a silicon-carbon particle negative electrode material. The specific preparation process is as follows:

[0099] (1) Preparation of porous carbon. The specific process is as follows: add 200 g of chitosan to a 2 wt% glacial acetic acid solution, stir for 1 hour, add sodium nitrate, and continue stirring for 30 minutes, then add ferric nitrate into an aqueous solution and stir for 1 hour to mix chitosan, ferric nitrate, and sodium nitrate evenly (the mass ratio of chitosan, ferric nitrate, and sodium nitrate is 1:1:1), and then obtain a carbonized precursor by freeze drying; then place the carbonized precursor in a box furnace, heat it to 1000 ° C under a nitrogen atmosphere, and carbonize it for 1 hour to obtain a metal / carbon complex; place the metal / carbon complex in a 2 mol / L hydrochloric acid solution, react at 30 ° C for 6 hours, and then wash it with deionized water until it is neutral to obtain porous carbon.

[0100] (2) The porous carbon was crushed and sieved, mixed with ferrocene, and placed in the deposition chamber of a vapor deposition furnace. Li2CO3, CS2, and acetylene were brought into the deposition chamber by a carrier gas nitrogen at a flow rate of 2 L / min. The mixture was reacted at 600°C for 6 hours to coat the pores of the porous carbon with multi-walled carbon nanotubes and Li2S to obtain an intermediate material.

[0101] (3) Trisilane was introduced into the deposition chamber by nitrogen carrier gas at a flow rate of 2 L / min, and vapor deposition was performed at 1400° C. for 3 hours to deposit silicon particles in the pores of the intermediate material to obtain a precursor material.

[0102] (4) The precursor material was carbon-coated. The precursor material and liquid phenolic resin with a mass ratio of 99:1 were placed in a fusion machine, the speed was set to 500 r / min, the fusion time was 10 minutes, and then placed in a tubular furnace and heated to 500 ° C. and kept warm for 1 hour to obtain a 14 nm carbon coating layer, and finally a silicon-carbon composite negative electrode material with a particle size Dv50 of 48 μm was obtained.

[0103] The silicon-carbon composite negative electrode material prepared in this example was used to prepare negative electrode sheets and assembled into button-type half-cells and full cells for testing. The battery assembly and testing methods were the same as in Example 1. The test data are detailed in Table 1.

[0104] Example 3

[0105] This embodiment provides a preparation process and performance test of a silicon-carbon particle negative electrode material. The specific preparation process is as follows:

[0106] (1) Preparation of porous carbon. The specific process is as follows: add 200 g of chitosan to a 2 wt% glacial acetic acid solution, stir for 1 hour, add sodium nitrate, and continue stirring for 30 minutes, then add ferric nitrate into an aqueous solution and stir for 1 hour to mix chitosan, ferric nitrate, and sodium nitrate evenly (the mass ratio of chitosan, ferric nitrate, and sodium nitrate is 1:1:1), and then obtain a carbonized precursor by freeze drying; then place the carbonized precursor in a box furnace, heat it to 500 ° C under a nitrogen atmosphere, and carbonize it for 6 hours to obtain a metal / carbon complex; place the metal / carbon complex in a 2 mol / L hydrochloric acid solution, react at 45 ° C for 9 hours, and then wash it with deionized water until it is neutral to obtain porous carbon.

[0107] (2) The porous carbon was crushed and sieved, mixed with ferrocene and placed in the deposition chamber of a vapor deposition furnace. Bi2O3, CS2 and acetylene were brought into the deposition chamber by a carrier gas nitrogen with a flow rate of 2 L / min. The mixture was reacted at 1100°C for 5 hours to coat the pores of the porous carbon with single-walled carbon nanotubes and Bi2S3 to obtain an intermediate material.

[0108] (3) Dichlorosilane gas is introduced into the deposition chamber by nitrogen carrier gas at a flow rate of 2 L / min, and vapor deposition is performed at 800° C. for 8 hours to deposit silicon particles in the pores of the intermediate material to obtain a precursor material.

[0109] (4) The precursor material was carbon-coated. The precursor material and liquid phenolic resin with a mass ratio of 99:1 were placed in a fusion machine, the speed was set to 500 r / min, the fusion time was 20 minutes, and then placed in a tubular furnace and heated to 400°C. The temperature was kept for 2 hours to obtain an 8nm carbon coating layer, and finally a silicon-carbon composite negative electrode material with a particle size Dv50 of 17μm was obtained.

[0110] The silicon-carbon composite negative electrode material prepared in this example was used to prepare negative electrode sheets and assembled into button-type half-cells and full cells for testing. The battery assembly and testing methods were the same as in Example 1. The test data are detailed in Table 1.

[0111] Example 4

[0112] This embodiment provides a preparation process and performance test of a silicon-carbon particle negative electrode material. The specific preparation process is as follows:

[0113] (1) Preparation of porous carbon. The specific process is as follows: add 200 g of chitosan to a 2 wt% glacial acetic acid solution, stir for 1 hour, add sodium nitrate and continue stirring for 30 minutes, then add ferric nitrate into an aqueous solution and stir for 1 hour to mix chitosan, ferric nitrate and sodium nitrate evenly (the mass ratio of chitosan, ferric nitrate and sodium nitrate is 1:1:1), and then obtain a carbonized precursor by freeze drying; then place the carbonized precursor in a box furnace, heat to 900 ° C under a nitrogen atmosphere and carbonize for 6 hours to obtain a metal / carbon complex; place the metal / carbon complex in a 2 mol / L hydrochloric acid solution, react at 35 ° C for 4 hours, and then wash with deionized water until neutral to obtain porous carbon.

[0114] (2) The porous carbon is crushed and sieved and placed in the deposition chamber of a vapor deposition furnace. SnO2, CS2 and toluene are brought into the deposition chamber by a carrier gas nitrogen with a flow rate of 2 L / min. The reaction is carried out at 1200°C for 4 hours to coat the pores of the porous carbon with carbon quantum dots and SnS2 to obtain an intermediate material.

[0115] (3) Trichlorosilane gas is introduced into the deposition chamber by nitrogen carrier gas at a flow rate of 2 L / min, and vapor deposition is performed at 1000° C. for 8 hours to deposit silicon particles in the pores of the intermediate material to obtain a precursor material.

[0116] (4) The precursor material was carbon-coated. The precursor material and liquid phenolic resin with a mass ratio of 99:1 were placed in a fusion machine, the speed was set to 500 r / min, the fusion time was 10 minutes, and then placed in a tubular furnace and heated to 400 ° C. and kept warm for 1 hour to obtain a 21 nm carbon coating layer, and finally a silicon-carbon composite negative electrode material with a particle size Dv50 of 55 μm was obtained.

[0117] The silicon-carbon composite negative electrode material prepared in this example was used to prepare negative electrode sheets and assembled into button-type half-cells and full cells for testing. The battery assembly and testing methods were the same as in Example 1. The test data are detailed in Table 1.

[0118] Example 5

[0119] This embodiment provides a preparation process and performance test of a silicon-carbon particle negative electrode material. The specific preparation process is as follows:

[0120] (1) Preparation of porous carbon. The specific process is as follows: add 200 g of chitosan to a 2 wt% glacial acetic acid solution, stir for 1 hour, add sodium nitrate and continue stirring for 30 minutes, then add ferric nitrate into an aqueous solution and stir for 1 hour to mix chitosan, ferric nitrate and sodium nitrate evenly (the mass ratio of chitosan, ferric nitrate and sodium nitrate is 1:1:1), and then obtain a carbonized precursor by freeze drying; then place the carbonized precursor in a box furnace, heat to 800 ° C under a nitrogen atmosphere and carbonize for 4 hours to obtain a metal / carbon complex; place the metal / carbon complex in a 2 mol / L hydrochloric acid solution, react at 25 ° C for 12 hours, and then wash with deionized water until neutral to obtain porous carbon.

[0121] (2) The porous carbon is crushed and sieved, mixed with ferrocene, and placed in the deposition chamber of a vapor deposition furnace. SnO2 and fullerene are brought into the deposition chamber by a carrier gas nitrogen with a flow rate of 2 L / min. The mixture is reacted at 1000°C for 2 hours to coat the pores of the porous carbon with single-walled carbon nanotubes and SnO2 to obtain an intermediate material.

[0122] (3) Tetrachlorosilane gas was introduced into the deposition chamber by nitrogen carrier gas at a flow rate of 2 L / min, and vapor deposition was performed at 1000° C. for 12 hours to deposit silicon particles in the pores of the intermediate material to obtain a precursor material.

[0123] (4) The precursor material was carbon-coated. The precursor material and liquid phenolic resin with a mass ratio of 95:5 were placed in a fusion machine, the speed was set to 500 r / min, and after the fusion time of 10 minutes, the temperature was raised to 700 ° C in a tube furnace and kept warm for 2 hours to obtain a 21 nm carbon coating layer, and finally a silicon-carbon composite negative electrode material with a particle size Dv50 of 55 μm was obtained.

[0124] The silicon-carbon composite negative electrode material prepared in this example was used to prepare negative electrode sheets and assembled into button-type half-cells and full cells for testing. The battery assembly and testing methods were the same as in Example 1. The test data are detailed in Table 1.

[0125] Example 6

[0126] This embodiment provides a preparation process and performance test of a silicon-carbon particle negative electrode material. The specific preparation process is as follows:

[0127] (1) Preparation of porous carbon. The specific process is as follows: add 200 g of chitosan to a 2 wt% glacial acetic acid solution, stir for 1 hour, add sodium nitrate, and continue stirring for 30 minutes, then add ferric nitrate into an aqueous solution and stir for 1 hour to mix chitosan, ferric nitrate, and sodium nitrate evenly (the mass ratio of chitosan, ferric nitrate, and sodium nitrate is 1:1:1), and then obtain a carbonized precursor by freeze drying; then place the carbonized precursor in a box furnace, heat to 700 ° C under a nitrogen atmosphere, and carbonize for 4 hours to obtain a metal / carbon complex; place the metal / carbon complex in a 2 mol / L hydrochloric acid solution, react at 25 ° C for 8 hours, and then wash with deionized water until neutral to obtain porous carbon.

[0128] (2) The porous carbon was crushed and sieved, mixed with ferrocene, and placed in the deposition chamber of a vapor deposition furnace. SnO2, CS2, and xylene were brought into the deposition chamber by a carrier gas nitrogen at a flow rate of 2 L / min. The mixture was reacted at 800°C for 3 hours to coat the pores of the porous carbon with multi-walled carbon nanotubes and SnS2 to obtain an intermediate material.

[0129] (3) Monosilane was introduced into the deposition chamber by nitrogen carrier gas at a flow rate of 2 L / min, and vapor deposition was performed at 1600° C. for 1 hour to deposit silicon particles in the pores of the intermediate material to obtain a precursor material.

[0130] (4) The precursor material was carbon-coated. The precursor material and liquid phenolic resin with a mass ratio of 98:2 were placed in a fusion machine, the speed was set to 500 r / min, and after the fusion time of 10 minutes, the temperature was raised to 800 ° C in a tube furnace and kept warm for 1 hour to obtain a 15 nm carbon coating layer, and finally a silicon-carbon composite negative electrode material with a particle size Dv50 of 41 μm was obtained.

[0131] The silicon-carbon composite negative electrode material prepared in this example was used to prepare negative electrode sheets and assembled into button-type half-cells and full cells for testing. The battery assembly and testing methods were the same as in Example 1. The test data are detailed in Table 1.

[0132] Example 7

[0133] This embodiment provides a preparation process and performance test of a silicon-carbon particle negative electrode material. The specific preparation process is as follows:

[0134] (1) Preparation of porous carbon. The specific process is as follows: add 200 g of chitosan to a 2 wt% glacial acetic acid solution, stir for 1 hour, add sodium nitrate, and continue stirring for 30 minutes, then add ferric nitrate into an aqueous solution and stir for 1 hour to mix chitosan, ferric nitrate, and sodium nitrate evenly (the mass ratio of chitosan, ferric nitrate, and sodium nitrate is 1:1:1), and then obtain a carbonized precursor by freeze drying; then place the carbonized precursor in a box furnace, heat it to 600 ° C under a nitrogen atmosphere, and carbonize it for 6 hours to obtain a metal / carbon complex; place the metal / carbon complex in a 2 mol / L hydrochloric acid solution, react at 25 ° C for 10 hours, and then wash it with deionized water until it is neutral to obtain porous carbon.

[0135] (2) The porous carbon was crushed and sieved, mixed with ferrocene, and placed in the deposition chamber of a vapor deposition furnace. Bi2O3 and methane were brought into the deposition chamber by a carrier gas nitrogen at a flow rate of 2 L / min. The mixture was reacted at 700°C for 5 hours to coat the pores of the porous carbon with multi-walled carbon nanotubes and Bi2O3 to obtain an intermediate material.

[0136] (3) Monosilane was introduced into the deposition chamber by nitrogen carrier gas at a flow rate of 2 L / min, and vapor deposition was performed at 1100° C. for 3 hours to deposit silicon particles in the pores of the intermediate material to obtain a precursor material.

[0137] (4) The precursor material was carbon-coated. The precursor material and liquid phenolic resin with a mass ratio of 91:2 were placed in a fusion machine, the speed was set to 700 r / min, the fusion time was 10 minutes, and then placed in a tubular furnace and heated to 600 ° C. and kept warm for 40 minutes to obtain a 16 nm carbon coating layer, and finally a silicon-carbon composite negative electrode material with a particle size Dv50 of 11 μm was obtained.

[0138] The silicon-carbon composite negative electrode material prepared in this example was used to prepare negative electrode sheets and assembled into button-type half-cells and full cells for testing. The battery assembly and testing methods were the same as in Example 1. The test data are detailed in Table 1.

[0139] Example 8

[0140] This embodiment provides a preparation process and performance test of a silicon-carbon particle negative electrode material. The specific preparation process is as follows:

[0141] (1) Preparation of porous carbon. The specific process is as follows: add 200 g of chitosan to a 2 wt% glacial acetic acid solution, stir for 1 hour, add sodium nitrate, and continue stirring for 30 minutes, then add ferric nitrate into an aqueous solution and stir for 1 hour to mix chitosan, ferric nitrate, and sodium nitrate evenly (the mass ratio of chitosan, ferric nitrate, and sodium nitrate is 1:1:1), and then obtain a carbonized precursor by freeze drying; then place the carbonized precursor in a box furnace, heat to 700 ° C under a nitrogen atmosphere, and carbonize for 2 hours to obtain a metal / carbon complex; place the metal / carbon complex in a 2 mol / L hydrochloric acid solution, react at 30 ° C for 8 hours, and then wash with deionized water until neutral to obtain porous carbon.

[0142] (2) The porous carbon is crushed and sieved and mixed with metal particles Au and placed in the deposition chamber of a vapor deposition furnace. SnO2, CS2 and acetylene are brought into the deposition chamber by a carrier gas nitrogen with a flow rate of 2 L / min. The mixture is reacted at 1000°C for 7 hours to coat the pores of the porous carbon with carbon nanowires and SnS2 to obtain an intermediate material.

[0143] (3) Dichlorosilane gas was introduced into the deposition chamber by nitrogen carrier gas at a flow rate of 2 L / min, and vapor deposition was performed at 1400° C. for 3 hours to deposit silicon particles in the pores of the intermediate material to obtain a precursor material.

[0144] (4) The precursor material was carbon-coated. The precursor material and liquid phenolic resin with a mass ratio of 99:1 were placed in a fusion machine, the speed was set to 400 r / min, the fusion time was 15 minutes, and then placed in a tubular furnace and heated to 500 ° C. and kept warm for 30 minutes to obtain a 9 nm carbon coating layer, and finally a silicon-carbon composite negative electrode material with a particle size Dv50 of 66 μm was obtained.

[0145] The silicon-carbon composite negative electrode material prepared in this example was used to prepare negative electrode sheets and assembled into button-type half-cells and full cells for testing. The battery assembly and testing methods were the same as in Example 1. The test data are detailed in Table 1.

[0146] Example 9

[0147] This embodiment provides a preparation process and performance test of a silicon-carbon particle negative electrode material. The specific preparation process is as follows:

[0148] (1) Preparation of porous carbon. The specific process is as follows: add 200 g of chitosan to a 2 wt% glacial acetic acid solution, stir for 1 hour, add sodium nitrate and continue stirring for 30 minutes, then add ferric nitrate prepared into an aqueous solution and stir for 1 hour to mix chitosan, ferric nitrate and sodium nitrate evenly (the mass ratio of chitosan, ferric nitrate and sodium nitrate is 1:1:1), and then obtain a carbonized precursor by freeze drying; then place the carbonized precursor in a box furnace, heat to 500 ° C under a nitrogen atmosphere and carbonize for 6 hours to obtain a metal / carbon complex; place the metal / carbon complex in a 2 mol / L hydrochloric acid solution, react at 30 ° C for 9 hours, and then wash with deionized water until neutral to obtain porous carbon.

[0149] (2) PEO is mixed with the obtained porous carbon and then spray-dried to obtain porous carbon containing PEO in the pores and on the surface; the porous carbon containing PEO in the pores and on the surface is mixed with metal particles Au and placed together in a deposition chamber of a vapor deposition furnace, propylene is brought into the deposition chamber by a carrier gas nitrogen with a flow rate of 2 L / min, and reacted at 900°C for 4 hours to coat the surface of the pores of the porous carbon with carbon nanowires, thereby obtaining an intermediate material containing organic solid electrolyte PEO and conductive nanomaterial carbon nanowires in the pores.

[0150] (3) Trisilane was introduced into the deposition chamber by nitrogen carrier gas at a flow rate of 2 L / min, and vapor deposition was performed at 600° C. for 8 hours to deposit silicon particles in the pores of the intermediate material to obtain a precursor material.

[0151] (4) The precursor material was carbon-coated. The precursor material and liquid phenolic resin with a mass ratio of 99:1 were placed in a fusion machine, the speed was set to 500 r / min, the fusion time was 10 minutes, and then placed in a tubular furnace and heated to 600 ° C. and kept warm for 2 hours to obtain a 6 nm carbon coating layer, and finally a silicon-carbon composite negative electrode material with a particle size Dv50 of 17 μm was obtained.

[0152] The silicon-carbon composite negative electrode material prepared in this example was used to prepare negative electrode sheets and assembled into button-type half-cells and full cells for testing. The battery assembly and testing methods were the same as in Example 1. The test data are detailed in Table 1.

[0153] Example 10

[0154] This embodiment provides a preparation process and performance test of a silicon-carbon particle negative electrode material. The specific preparation process is as follows:

[0155] (1) Preparation of porous carbon. The specific process is as follows: add 200 g of chitosan to a 2 wt% glacial acetic acid solution, stir for 1 hour, add sodium nitrate, and continue stirring for 30 minutes, then add ferric nitrate into an aqueous solution and stir for 1 hour to mix chitosan, ferric nitrate, and sodium nitrate evenly (the mass ratio of chitosan, ferric nitrate, and sodium nitrate is 1:1:1), and then obtain a carbonized precursor by freeze drying; then place the carbonized precursor in a box furnace, heat to 400 ° C under a nitrogen atmosphere, and carbonize for 6 hours to obtain a metal / carbon complex; place the metal / carbon complex in a 2 mol / L hydrochloric acid solution, react at 40 ° C for 4 hours, and then wash with deionized water until neutral to obtain porous carbon.

[0156] (2) The porous carbon was crushed and sieved, mixed with ferrocene, and placed in the deposition chamber of a vapor deposition furnace. SnO2, CS2, and methane were brought into the deposition chamber by a carrier gas nitrogen at a flow rate of 2 L / min. The mixture was reacted at 1100°C for 4 hours to coat the pores of the porous carbon with single-walled carbon nanotubes and SnS2 to obtain an intermediate material.

[0157] (3) Monosilane was introduced into the deposition chamber by nitrogen carrier gas at a flow rate of 2 L / min, and vapor deposition was performed at 800° C. for 8 hours to deposit silicon particles in the pores of the intermediate material to obtain a precursor material.

[0158] (4) The precursor material was carbon-coated. The precursor material and liquid phenolic resin with a mass ratio of 99:1 were placed in a fusion machine, the speed was set to 500 r / min, the fusion time was 10 minutes, and then placed in a tubular furnace and heated to 400°C and kept warm for 40 minutes to obtain a 7nm carbon coating layer, and finally a silicon-carbon composite negative electrode material with a particle size Dv50 of 36μm was obtained.

[0159] The silicon-carbon composite negative electrode material prepared in this example was used to prepare negative electrode sheets and assembled into button-type half-cells and full cells for testing. The battery assembly and testing methods were the same as in Example 1. The test data are detailed in Table 1.

[0160] Table 1 Table 1 summarizes the test data of button half-cells and full cells assembled in Examples 1-10 and Comparative Example 1:

[0161]

[0162] Table 1

[0163] Comparing the data in Table 1, it can be seen that compared to the battery assembled in Comparative Example 1, the batteries using the silicon-carbon composite negative electrode material of Examples 1-10 exhibited higher cycle capacity retention at a high rate of 3C. This is because the ion-conducting and electrically conductive structure within the porous carbon pores of the silicon-carbon composite negative electrode material in the battery electrodes of Examples 1-10 of the present invention ensures stable contact between the nano-silicon particles and the carbon within the pores, thereby ensuring the cyclic stability of the electrochemical performance and the rapid transmission of ions and electrons between the carbon and silicon.

[0164] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A silicon-carbon composite negative electrode material, characterized in that: The silicon-carbon composite negative electrode material comprises: porous carbon, nano-silicon particles, conductive nano-materials and solid electrolyte materials dispersed in the pores of the porous carbon, and a carbon coating layer coated on the outer surface of the porous carbon; The conductive nanomaterials include: one or more of carbon quantum dots, carbon nanowires, single-walled carbon nanotubes, and multi-walled carbon nanotubes; The solid electrolyte material includes one or more of an oxide solid electrolyte, a sulfide solid electrolyte, and an organic solid electrolyte.

2. The silicon-carbon composite negative electrode material according to claim 1, characterized in that The pore size of the porous carbon is 0.1nm-10nm, and the specific surface area is 150m 2 / g-3000m 2 / g between; The particle size DV50 of the silicon-carbon composite negative electrode material is 0.5 μm-100 μm; The thickness of the carbon coating layer is between 2nm and 5nm.

3. The silicon-carbon composite negative electrode material according to claim 1, characterized in that The oxide solid electrolyte includes: SnO2 and / or Bi2O3; The sulfide solid electrolyte includes: one or more of SnS2, Li2S, and Bi2S3; The organic solid electrolyte includes one or more of polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polypropylene oxide (PPO), and polyvinylidene chloride (PVDC); The mass of the porous carbon accounts for 25%-70% of the total mass of the silicon-carbon composite negative electrode material; The mass of the nano-silicon particles accounts for 25%-70% of the total mass of the silicon-carbon composite negative electrode material; The mass of the conductive nanomaterial accounts for 0.1%-10% of the total mass of the silicon-carbon composite negative electrode material; The mass of the solid electrolyte material accounts for 0.1%-10% of the total mass of the silicon-carbon composite negative electrode material; The mass of the carbon coating layer accounts for 0.1%-10% of the total mass of the silicon-carbon composite negative electrode material.

4. A method for preparing the silicon-carbon composite negative electrode material according to any one of claims 1 to 3, characterized in that: The preparation method comprises: Step S1, preparing porous carbon, specifically, the following process: adding chitosan to a glacial acetic acid solution, stirring for 1 hour, then adding sodium nitrate and continuing to stir for 30 minutes, then dropwise adding an aqueous solution prepared with ferric nitrate, stirring for 1 hour to uniformly mix the chitosan, ferric nitrate, and sodium nitrate, and then freeze-drying to obtain a carbonized precursor; then placing the carbonized precursor in a reaction device and performing a high-temperature carbonization treatment under a protective atmosphere to obtain a metal / carbon composite; then acid-washing the metal / carbon composite and then washing it to neutrality to obtain porous carbon; Step S2, placing the porous carbon in a deposition chamber of a vapor deposition furnace, bringing the raw materials of the conductive nanomaterial and the solid electrolyte material into the deposition chamber by a carrier gas, and reacting them at a certain temperature so that the surface of the pores of the porous carbon is coated with the conductive nanomaterial and the solid electrolyte material to obtain an intermediate material; Step S3, introducing a silicon-containing compound into a deposition chamber by a carrier gas, performing vapor deposition, and depositing silicon particles in the pores of the intermediate material to obtain a precursor material; Step S4: Carbon coating the precursor material to obtain a silicon-carbon composite negative electrode material.

5. The preparation method according to claim 4, characterized in that The mass ratio of chitosan, ferric nitrate and sodium nitrate in step S1 is 1:1:1; The porosity of the porous carbon is 30%-80%; The reaction equipment is: a tube furnace or a box furnace; The protective atmosphere includes nitrogen atmosphere or argon atmosphere; The high temperature carbonization process is specifically as follows: heating the reaction equipment to 500°C-1000°C and keeping the temperature for 1 hour-6 hours; The process of pickling and then washing to neutrality is specifically as follows: reacting the metal / carbon composite with 2 mol / L hydrochloric acid at 20° C.-70° C. for 2 hours-12 hours, and then washing with deionized water to neutrality.

6. The preparation method according to claim 4, characterized in that The temperature of the reaction at a certain temperature in step S2 is 600° C.-1200° C., and the reaction time is 1 hour-8 hours; The carrier gas includes nitrogen or argon; the flow rate of the carrier gas is 2L / min-30L / min; The raw materials of the conductive nanomaterials include: one or more of methane, acetylene, toluene, fullerene, xylene, and propylene; The raw materials of the solid electrolyte material specifically include: one or more raw materials of oxide solid electrolyte, raw materials of sulfide solid electrolyte, and raw materials of organic solid electrolyte; The raw materials of the oxide solid electrolyte specifically include: SnO2 and / or Bi2O3; The raw materials of the sulfide solid electrolyte material specifically include: any combination of SnO2 and CS2, Li2CO3 and CS2, Bi2O3 and CS2; The raw materials of the organic solid electrolyte include: one or more of polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polypropylene oxide (PPO), and polyvinylidene chloride (PVDC).

7. The preparation method according to claim 4, characterized in that The silicon-containing compound in step S3 includes one or more of metallic silicon vapor, monosilane, trisilane, dichlorosilane, trichlorosilane, and tetrachlorosilane; The carrier gas includes nitrogen or argon; the flow rate of the carrier gas is 1L / min-20L / min; The temperature of the vapor deposition is 400° C.-1600° C., and the time is 1 hour-20 hours.

8. The preparation method according to claim 4, characterized in that The carbon coating method is gas phase carbon coating or liquid phase carbon coating.

9. A negative electrode plate, characterized in that: The negative electrode plate comprises the silicon-carbon composite negative electrode material according to any one of claims 1 to 3.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the negative electrode sheet according to claim 9.

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