Silicon-carbon composite material as well as preparation method and application thereof

Abstract

The invention provides a silicon-carbon composite material as well as a preparation method and application thereof, and belongs to the technical field of lithium ion battery negative electrode materials. The silicon-carbon composite material comprises silicon-carbon composite material particles, and the silicon-carbon composite material particles are spherical or sphere-like particles; the silicon-carbon composite material particles comprise silicon-carbon material particles and coating layers positioned on the surfaces of the silicon-carbon material particles; the silicon-carbon material particles comprise a porous carbon skeleton and nano silicon particles embedded in the porous carbon skeleton; and the coating layer is a conductive polymer coating layer. The conductive polymer coating layer significantly improves the hydrophilicity of the material and the interface bonding force with a binder. And an electron-ion bicontinuous transmission structure is formed by combining an ion transmission channel of the porous carbon skeleton and an electronic network constructed by the conductive polymer, so that the lithium intercalation capacity retention rate of the material at 1C multiplying power reaches 85%. Chemical vapor deposition is combined with in-situ polymerization to realize accurate regulation and control of the thickness and conductivity of the coating layer, and the method is suitable for large-scale production of lithium ion batteries with high energy density and long cycle life.

Description

Technical Field

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

[0002] Among the negative electrode materials for lithium-ion batteries currently developed, silicon-based materials are favored for their low potential and extremely high theoretical capacity. However, in the process of lithium ion insertion and extraction, silicon-based materials undergo severe volume changes (expansion rate up to 300%), which causes damage to the material structure and mechanical pulverization, leading to separation between electrode materials and between electrode materials and current collectors, and then loss of electrical contact, resulting in rapid capacity decay. Therefore, how to improve the cycle performance and rate performance of silicon-based negative electrode materials while obtaining high capacity is a current research focus. In order to buffer the capacity decay caused by the huge volume change of silicon during the electrochemical process, people use various methods to improve the cyclability of silicon negative electrode materials.

[0003] Spherical silicon-carbon materials have high curvature, high hydrophobicity, and poor binding force with binders, which affects their rate performance and cycle stability. There is no report on surface improvement of spherical silicon-carbon materials in the prior art.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] One of the purposes of the present invention is to provide a silicon-carbon composite material to solve the problems in the prior art that the spherical silicon-carbon material has high hydrophobicity, poor bonding strength with the binder and poor magnification.

[0006] The second object of the present invention is to provide a negative electrode to improve the structural stability of the silicon-carbon negative electrode material, increase the initial coulombic efficiency, and improve the cycle life and rate performance.

[0007] The third object of the present invention is to provide a battery, which utilizes the negative electrode to optimize the overall performance of the battery, improve the energy density, cycle stability and service life.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: In a first aspect, the present invention provides a silicon-carbon composite material, which includes silicon-carbon composite material particles, wherein the silicon-carbon composite material particles are spherical or quasi-spherical particles; the silicon-carbon composite material particles include silicon-carbon material particles and a coating layer located on the surface of the silicon-carbon material particles; the silicon-carbon material particles include a porous carbon skeleton and nano-silicon particles embedded in the porous carbon skeleton; the coating layer is a conductive polymer coating layer.

[0009] Furthermore, the sphericity of the silicon-carbon composite material particles is ρ≥0.8.

[0010] Furthermore, the mass content of the coating layer in the silicon-carbon composite material is 0.05-5%.

[0011] Furthermore, the coating layer has a thickness of 5 to 100 nm.

[0012] Furthermore, the silicon-carbon composite material satisfies at least one of the following characteristics: the mass content of the nano-silicon particles in the silicon-carbon composite material is 30-70%; the particle size of the nano-silicon particles is 2-5 nm; the specific surface area of ​​the silicon-carbon composite material is 0.2-10 m 2 / g; the particle size of the silicon-carbon composite material d V50 The diameter of the silicon-carbon composite material is 2~15 μm. d V90 - d V10 ) / d V50 ) is 0.7~1.5.

[0013] Furthermore, the conductive polymer coating layer is obtained by in-situ polymerization of monomers of a conductive polymer compound on the silicon-carbon material particles and optional heat treatment; the conductive polymer compound includes at least one of polyacetylene, polypyrrole, poly(p-phenylene vinylene), polyphenylene sulfide or polyaniline; the monomers of the conductive polymer compound include at least one of aniline monomer, acetylene monomer, pyrrole monomer, p-phenylene vinylene monomer and phenylene sulfide monomer.

[0014] Furthermore, the silicon-carbon material particles are obtained by chemical vapor deposition of a silicon-containing precursor on the porous carbon skeleton.

[0015] Furthermore, the silicon-containing precursor is selected from one or more of monosilane, disilane, trisilane, halogenated silane, polysilane, silole and its derivatives, silanol and its derivatives.

[0016] Furthermore, the temperature of the chemical vapor deposition is 150~1000°C.

[0017] In a second aspect, the present invention provides a negative electrode, wherein the negative electrode comprises a negative electrode active material, and the negative electrode active material comprises the silicon-carbon composite material provided in the first aspect of the present invention.

[0018] In a third aspect, the present invention provides a battery, comprising a positive electrode, a negative electrode, a separator, an electrolyte, etc., wherein the negative electrode comprises a negative electrode active material, and the negative electrode active material comprises the silicon-carbon composite material provided in the first aspect of the present invention.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention provides a silicon-carbon composite material, wherein the conductive polymer coating layer significantly improves the hydrophilicity of the material, promotes uniform coating of the electrode slurry, and reduces the generation of cracks; the strong interface bonding force with the binder inhibits the electrode pulverization caused by silicon volume expansion, and improves the cycle life. On the other hand, the hydrophilic surface accelerates the infiltration of the electrolyte and reduces the diffusion resistance of lithium ions; it realizes rapid electron-ion transmission, and the capacity retention rate at 0.1 C~1 C rate is increased by 20%~40%. The polymer conductive network and the porous carbon skeleton work together to form a flexible network, which dynamically adapts to volume changes, not only enhancing the structural stability of the material, but also preventing the silicon nanoparticles from falling off and agglomerating during the charging and discharging process, further improving the cycle life and reliability of the battery, reducing the capacity attenuation rate, and the capacity retention rate can still reach more than 85% after 100 cycles. The silicon-carbon composite material provided by the present invention has a surface coating layer obtained by using a polymer monomer on the surface of the silicon-carbon material particles, and the coating layer thickness is precisely controllable, which can be adapted to large-scale production, and is conducive to the large-scale application of silicon-carbon negative electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is a SEM image of the silicon-carbon composite material provided in Example 1 of the present invention; Figure 2 This is a SEM image of the silicon-carbon composite material provided in Comparative Example 1 of the present invention; Figure 3 This is a SEM image of the silicon-carbon composite material provided in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0022] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.

[0023] The methods and techniques of the present invention are generally performed according to conventional methods well known in the art and as described in various general and more specific references that are cited and discussed throughout the present specification unless otherwise indicated.

[0024] In a first typical embodiment of the present invention, the silicon-carbon composite material includes silicon-carbon composite material particles, and the silicon-carbon composite material particles are spherical or quasi-spherical particles; the silicon-carbon composite material particles contain silicon-carbon material particles and a coating layer located on the surface of the silicon-carbon material particles; the silicon-carbon material particles include a porous carbon skeleton and nano-silicon particles embedded in the porous carbon skeleton; the coating layer is a conductive polymer coating layer.

[0025] The conductive polymer coating layer significantly improves the hydrophilicity of the material (the contact angle is reduced from 110° to 30°), promotes uniform coating of the electrode slurry, and reduces crack generation; the strong interfacial bonding force with the binder inhibits electrode pulverization caused by silicon volume expansion and improves cycle life. On the other hand, the hydrophilic surface accelerates electrolyte infiltration and reduces lithium ion diffusion resistance; the ion transmission channel of the porous carbon skeleton is combined with the electronic network constructed by the conductive polymer, and the electronic network and the porous spherical or quasi-spherical carbon skeleton work together to form a flexible network that dynamically adapts to volume changes, which not only enhances the structural stability of the material, but also prevents the silicon nanoparticles from falling off and agglomerating during the charging and discharging process, further improving the cycle life and reliability of the battery, reducing the capacity attenuation rate, and the capacity retention rate can still reach more than 85% after 100 cycles. Rapid electron-ion transmission is achieved, and the capacity retention rate at 0.1 C~1 C rate is increased by 20%~40%.

[0026] Compared with pure porous spherical or quasi-spherical silicon-carbon materials, the conductive polymer coating layer improves the hydrophilicity and interfacial bonding strength of the silicon-carbon material, thereby significantly improving the rate performance and cycle stability of the material.

[0027] In some embodiments, the sphericity of the silicon-carbon composite material particles is ρ≥0.8. The sphericity of the particles is obtained by testing the composite material with a nanoflow particle imaging analyzer. The silicon-carbon composite material is prepared by selecting a porous carbon skeleton with a sphericity ≥0.8, and the resulting silicon-carbon composite material may have a sphericity ≥0.8.

[0028] In some embodiments, the mass content of the coating layer in the silicon-carbon composite material is 0.05-5%.

[0029] In some embodiments, the coating layer has a thickness of 5 to 100 nm.

[0030] Among them, the mass content of the coating layer in the silicon-carbon composite material can be but not limited to 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4% or 5%, and can also be any value between 0.05 and 5%; the thickness of the conductive polymer coating layer can be but not limited to 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm, and can also be any value between 5 and 100 nm.

[0031] In some embodiments, the mass content of the nano-silicon particles in the silicon-carbon composite material is 30-70%; the particle size of the nano-silicon particles is 2-5 nm; the specific surface area of ​​the silicon-carbon composite material is 0.2-10 m 2 / g; particle size d V50 2~15 μm, diameter distance (( d V90 - d V10 ) / d V50 )0.7~1.5.

[0032] The mass content of the silicon nanoparticles in the silicon-carbon composite material may be, but not limited to, 30%, 35%, 40%, 45%, 50%, 55%, 60% or 70%, or any size between 30 and 70%; the particle size of the nano silicon particles may be, but not limited to, 2 nm, 2.3 nm, 2.5 nm, 2.8 nm, 3 nm, 3.3 nm, 3.5 nm, 3.8 nm, 4 nm, 4.3 nm, 4.5 nm, 4.8 nm or 5 nm, or any size between 2 and 5 nm; the specific surface area of ​​the silicon-carbon composite material is 0.2 m 2 / g, 0.4 m 2 / g, 0.6 m 2 / g, 1 m 2 / g, 2 m 2 / g, 3 m 2 / g, 4 m 2 / g, 5 m 2 / g, 6 m 2 / g, 7 m 2 / g, 8 m 2 / g, 9 m 2 / g or 10 m 2 / g, or 0.2~10 m 2 Any size between / g.

[0033] In some embodiments, the conductive polymer coating layer is obtained by in-situ polymerization of monomers of a conductive polymer compound on the silicon-carbon material particles; in some embodiments, the conductive polymer compound includes at least one of polyacetylene, polypyrrole, poly(p-phenylene vinylene), polyphenylene sulfide or polyaniline; in some embodiments, the monomers of the conductive polymer compound include at least one of aniline monomer, acetylene monomer, pyrrole monomer, p-phenylene vinylene monomer and phenylene sulfide monomer. In some embodiments, the in-situ polymerization further includes heat treatment of the composite material.

[0034] In some embodiments, the silicon-carbon material particles are obtained by chemical vapor deposition of a silicon-containing precursor on the porous carbon framework.

[0035] In some embodiments, the silicon-containing precursor is selected from one or more of monosilane, disilane, trisilane, halosilanes, polysilanes, siloles and their derivatives, silanols and their derivatives; in some embodiments, the temperature of the chemical vapor deposition is 150~1000 °C.

[0036] In a second typical embodiment of the present invention, a negative electrode is further provided. The negative electrode comprises a negative electrode active material. The negative electrode active material comprises the silicon-carbon composite material in the first typical embodiment of the present invention.

[0037] In a third typical embodiment of the present invention, a battery is also provided, which includes a positive electrode, a negative electrode, a separator, an electrolyte, etc. The negative electrode includes a negative electrode active material, and the negative electrode active material includes the silicon-carbon composite material in the first typical embodiment of the present invention.

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1 Step S1, preparing silicon-carbon material: taking raw material spherical carbon material particles with a sphericity of 0.95 and putting them into a tubular furnace, selecting silane gas (hexamethyldisilane) as a silicon source, and passing the silane gas into the tubular furnace, the selected silane flow rate is 1.02sccm, the deposition temperature is 850°C, and the deposition is performed for 4 hours to obtain a silicon-carbon material, which contains spherical silicon-carbon material particles.

[0040] Step S2, preparing a silicon-carbon composite material: ultrasonically disperse 1 g of the silicon-carbon material obtained in step 1 into 200 mL of deionized water, and drop 2 mL of aniline monomer into the above suspension; then drop a hydrochloric acid aqueous solution of ammonium persulfate (APS) (molar mass ratio of conductive polymer monomer: APS = 1:1) as an oxidant, and stir continuously in an ice-water bath for 24 h until the solution color turns dark green; filter the dark green product and wash it three times with ethanol, and dry the obtained filter cake in a vacuum oven at 60°C for 12 h. The obtained product is placed in a tube furnace for high-temperature treatment under an inert atmosphere (argon, flow rate 150 sccm). High-temperature treatment conditions: keep warm at 700°C for 7 h to obtain a silicon-carbon composite material with a surface-coated polyaniline coating layer.

[0041] The sphericity of the silicon-carbon composite material obtained in this example continues the sphericity of the porous carbon skeleton of the raw material, which is 0.95. Its SEM image is as follows Figure 1 shown.

[0042] Example 2 This embodiment provides a silicon-carbon composite material, and the preparation method is different from that of Embodiment 1 in that the deposition time in step S1 is extended to 7 h, and other conditions remain unchanged.

[0043] Example 3 This embodiment provides a silicon-carbon composite material, and the preparation method is different from that of Embodiment 1 in that the deposition time in step S1 is extended to 10 h, and other conditions remain unchanged.

[0044] Example 4 This embodiment provides a silicon-carbon composite material, and the preparation method is different from that of Embodiment 2 in that: in step S2, 2 mL of aniline monomer is changed to 0.2 mL, and other conditions remain unchanged.

[0045] Example 5 This embodiment provides a silicon-carbon composite material, and the preparation method is different from that of Embodiment 2 in that: in step S2, 2 mL of aniline monomer is changed to 5 mL, and other conditions remain unchanged.

[0046] Example 6 This embodiment provides a silicon-carbon composite material, and the preparation method is different from that of Embodiment 2 in that: in step S2, 2 mL of aniline monomer is changed to 10 mL, and other conditions remain unchanged.

[0047] Example 7 This embodiment provides a silicon-carbon composite material, and the preparation method is different from that of Embodiment 2 in that: in step S2, 2 mL of aniline monomer is replaced with 2 mL of pyrrole monomer, and other conditions remain unchanged.

[0048] Comparative Example 1 The difference from Example 2 is that step S2 is not included. The SEM image of the silicon-carbon composite material is as follows: Figure 2 shown.

[0049] Comparative Example 2 The difference from Example 2 is that the raw carbon material particles used in step S1 are ordinary resin carbon block particles, and their particle size and pore volume are close to those of the carbon material in Example 2; the sphericity of the particles in the obtained silicon-carbon composite material is 0; and because the silicon-carbon material particles do not have sphericity, the coating cannot obtain a uniform coating layer, but is partially gathered in certain parts of the particle surface, such as Figure 3 shown.

[0050] Test method Si content test: Place 3.0 g of the silicon-carbon composite material in an oven at 150°C and dry it to constant weight. Record the mass m 1 ; Place the dried composite material in a muffle furnace, heat it to 1100℃ and keep it for 2 h, cool it down and weigh it, and record the mass m 2 . Si content calculation formula: .

[0051] Sphericity test: obtained by using nano-flow particle imaging analyzer.

[0052] The following is a brief description of the battery test.

[0053] Half-cell test method: The electrochemical performance of the silicon-carbon composite materials obtained in Examples 1 to 7 and Comparative Example 1 was tested, and the results are shown in Table 1. The silicon-carbon composite materials obtained in Examples 1 to 7 and Comparative Example 1 were used as negative electrode active materials to prepare negative electrode sheets, and the negative electrode sheets were used to prepare CR2032 button batteries by conventional methods, and the batteries were tested for electrical performance. The batteries were charged and discharged using a LAND battery test system.

[0054] (1) Half-cell assembly: CR2032 button cells were assembled in a glove box, with lithium metal sheets as counter electrodes, polypropylene microporous membranes as separators, and the electrolyte being LiPF6 dissolved in a mixture of ethyl carbonate (EC) and diethyl carbonate (DEC) (volume ratio EC:DEC = 1:1), where the LiPF6 concentration was 1 mol / L.

[0055] (2) Cyclic gram capacity and first efficiency test: After the CR2032 battery was left uncharged for 6 h, it was discharged at 0.05 C to 0.005 V, and then discharged at 0.01 C to 0.005 V. After standing for 5 min, it was charged to 1.5 V at 0.05 C constant current. The 0.8 V first lithium de-ion gram capacity is the 0.8 V gram capacity (or mass specific capacity) of the electrode material. The ratio of the 0.8 V first lithium de-ion capacity to the 1.5 V first lithium insertion capacity is the 0.8 V first coulombic efficiency of the battery.

[0056] (3) Rate performance test: After the CR2032 battery was left standing for 6 h, it was discharged to 0.005 V at 0.1 C. After standing for 5 min, it was charged to 1.5 V at 0.1 C, and this cycle was repeated three times. It was then discharged to 0.005 V at 1 C. After standing for 5 min, it was charged to 1.5 V at 1 C, and this cycle was repeated three times. The data was recorded. The 1 C lithium insertion retention rate was 1 C discharge specific capacity / 0.1 C discharge specific capacity.

[0057] Full battery test method: The silicon-carbon composite material obtained in Examples 1 to 7 and Comparative Example 1 was used as the negative electrode active material, and the pole piece containing the negative electrode active material was prepared into a soft pack battery by conventional methods and the electrical performance test was performed. The soft pack battery was prepared in a dehumidification room with a dew point of -45°C. The battery was tested for charge and discharge cycles using the LANBTS battery test system. The results are shown in Table 1. The specific test method is: (1) Preparation of positive electrode sheet: The positive electrode active material LiCoO 2 , conductive agent Super P, binder PVDF and solvent NMP are stirred and evenly mixed in a mass ratio of 92:3:5:150, evenly coated on the positive electrode collector, and then dried at 80°C to obtain a positive electrode sheet.

[0058] (2) Preparation of negative electrode sheet: The negative electrode active material, conductive agent Super P, binder polyacrylic acid and solvent deionized water are stirred and mixed in a mass ratio of 95:1:4:120, and then evenly coated on the negative electrode collector, and then dried at 100°C to obtain the negative electrode sheet.

[0059] (3) The positive electrode and the negative electrode are stacked in a square shape and separated by a polypropylene separator to form a battery core, which is then packaged in an aluminum-plastic bag. The aluminum-plastic bag is filled with an electrolyte of a corresponding capacity and vacuum-sealed to obtain a soft-pack battery. The electrolyte is a mixture of LiPF6, EC and DEC, where the concentration of LiPF6 is 1 mol / L and the volume ratio of EC to DEC is 1:1.

[0060] (4) Formation: After the battery is filled and sealed, it begins to form, and is placed in a 25°C constant temperature box for 12 h. It is then charged to 3.3 V at 0.02C constant current, placed for 30 min, charged to 3.8 V at 0.025C constant current, placed for 10 min, and charged to 4.2 V at 0.33C constant current. The formed battery is vacuumed and the air bag is cut, and then the capacity is divided. It is charged to 4.45 V at 0.33C constant current, placed for 10 min, discharged to 3 V at 1C constant current, placed for 10 min, and discharged to 3 V at 0.33C constant current. The ratio of the discharge capacity to the charge capacity in the formation of soft-pack batteries is the first efficiency of the battery.

[0061] (5) 25℃ cycle test: Place the battery in a 25℃ constant temperature box, charge it to 4.45 V at a constant current of 1 C, and then charge it to 0.1 C at a constant voltage of 4.45 V. After standing for 10 min, discharge it to 3.0 V at a constant current of 1 C, and stand it for 10 min. Repeat the above charging and discharging steps until the discharge capacity is lower than 80% of the discharge capacity of the first cycle. The number of cycles obtained at this time is the cycle life of the soft-pack battery. Record the capacity retention rate after 100 cycles.

[0062] Example results and analysis The physical and chemical properties of the silicon-carbon composite materials obtained in Examples 1-7 and Comparative Examples 1-2 are shown in Table 1.

[0063] Table 1 Physical and chemical properties of silicon-carbon composite materials obtained in Examples 1 to 7 and Comparative Examples 1 to 2

[0064] As can be seen from Table 1, the capacity retention rates of the silicon-carbon composite materials in Examples 1 to 7 after 100 cycles at 25°C are all above 99%, and the 1C lithium insertion retention rates are all above 80%, indicating that the thickness of this coating layer takes into account both electron transport and ion diffusion, achieving high capacity (>1500 mAh / g), high cycle stability (>99%) and excellent rate performance (1 C retention rate>80%). Example 3 proves that due to the presence of the conductive polymer coating layer, even if the silicon content is increased to 70%, the silicon-carbon composite material can still maintain a capacity retention rate of 99.7%, breaking through the bottleneck that the high capacity and high stability of silicon-based materials are difficult to be compatible. Compared with Comparative Example 1, when there is no coating layer, its cycle and rate performance deteriorate sharply, highlighting the necessity of the conductive polymer coating layer for the practical silicon-carbon negative electrode. Comparative Example 2 Since the silicon-carbon material particles do not have sphericity, their coating cannot obtain a uniform coating layer, but is partially concentrated in certain parts of the particle surface, such as Figure 3 As shown, its cycle stability and rate performance are significantly deteriorated.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicon-carbon composite material, characterized in that: The silicon-carbon composite material includes silicon-carbon composite material particles, which are spherical or quasi-spherical particles; the silicon-carbon composite material particles include silicon-carbon material particles and a coating layer located on the surface of the silicon-carbon material particles; the silicon-carbon material particles include a porous carbon skeleton and nano-silicon particles embedded in the porous carbon skeleton; the coating layer is a conductive polymer coating layer.

2. The silicon-carbon composite material according to claim 1, characterized in that: The sphericity of the silicon-carbon composite material particles is ρ≥0.

8.

3. The silicon-carbon composite material according to claim 1, characterized in that The mass content of the coating layer in the silicon-carbon composite material is 0.05-5%; and / or the thickness of the coating layer is 5-100 nm.

4. The silicon-carbon composite material according to claim 1, characterized in that: The silicon-carbon composite material meets at least one of the following characteristics: (1) The mass content of the nano silicon particles in the silicon-carbon composite material is 30-70%; (2) The particle size of the nano silicon particles is 2-5 nm; (3) The specific surface area of ​​the silicon-carbon composite material is 0.2 to 10 m 2 / g, (4) Particle size of the silicon-carbon composite material d V50 2~15 μm, diameter distance (( d V90 - d V10 ) / d V50 ) is 0.7~1.

5.

5. The silicon-carbon composite material according to claim 1, characterized in that: The conductive polymer coating layer is obtained by in-situ polymerization of the monomers of the conductive polymer compound on the silicon-carbon material particles; The conductive polymer compound includes at least one of polyacetylene, polypyrrole, polyparaphenylene vinylene, polyphenylene sulfide or polyaniline; The monomer of the conductive polymer compound includes at least one of aniline monomer, acetylene monomer, pyrrole monomer, paraphenylene vinylene monomer and phenylene sulfide monomer.

6. The silicon-carbon composite material according to claim 1, characterized in that: The silicon-carbon material particles are obtained by chemical vapor deposition of a silicon-containing precursor on the porous carbon skeleton.

7. The silicon-carbon composite material according to claim 6, characterized in that: The silicon-containing precursor is selected from one or more of monosilane, disilane, trisilane, halogenated silane, polysilane, silole and its derivatives, silanol and its derivatives.

8. The silicon-carbon composite material according to claim 6, characterized in that: The temperature of the chemical vapor deposition is 150~1000℃.

9. A negative electrode, characterized in that The negative electrode comprises a negative electrode active material, and the negative electrode active material comprises the silicon-carbon composite material according to any one of claims 1 to 8.

10. A battery, characterized in that The battery comprises a positive electrode, a negative electrode, a separator or an electrolyte, and the negative electrode comprises the silicon-carbon composite material according to any one of claims 1 to 8.

Images