Three-dimensional network structure composite materials for lithium batteries and their preparation methods and applications

Abstract

This paper provides a three-dimensional network structure composite material for lithium batteries, its preparation method and application. [Solution] A composite material with a three-dimensional network structure comprises porous carbon microspheres with through-holes in a network structure, silicon nanowires distributed within the through-holes of the porous carbon microspheres, and a carbon shell. The silicon nanowires are formed by catalyzing a silicon-containing gas with Au or Ag and depositing it within the through-holes. Alternatively, the silicon nanowires are formed by depositing silane gas within the through-holes to form silicon oxide nanoparticles, and then electrolyzing the silicon oxide nanoparticles within the through-holes in a molten salt system. The silicon nanowires form a three-dimensional network structure within the through-holes of the porous carbon microspheres. By applying the three-dimensional network structure composite material of the present invention to a lithium battery as an anode active material, the lithium battery can be endowed with a low volume expansion coefficient, a high mass-specific capacity, good conductivity, and cycle stability.

Description

[Technical Field]

[0001] (cross reference) This application claims priority to a Chinese patent application filed with the China Patent Office on October 24, 2022, bearing application number 202211298670.7 and titled "Three-dimensional mesh structure composite material for lithium batteries and its preparation method and application."

[0002] (Technical field) The present invention relates to the technical field of lithium battery materials, and more particularly to a three-dimensional network structure composite material for lithium batteries and its preparation method and application. [Background technology]

[0003] Silicon-based anode materials have become a hot anode material for lithium-ion batteries due to their extremely high specific capacity, more than 10 times that of commercially available graphite. However, silicon-based anodes undergo large volume changes during electrochemical processes, leading to the formation of an unstable SEI film on the surface of the anode material.

[0004] People have found that by using carbon coating or controlling the porosity of porous materials, the volume expansion of silicon particles can be suppressed and the silicon particles can be prevented from pulverizing. The carbon coating layer can also ensure the stability of the SEI film on the surface of the negative electrode material, which can improve the Li + Although such carbon coatings limit the volume change of silicon particles during lithiation to some extent, the formation of microcracks during cycling still destroys the material structure.

[0005] Therefore, it is necessary to develop a composite material that can effectively suppress volume expansion, prevent microcracks from forming on the surface of the material during cycling, and improve the charge / discharge performance and cycle stability of the battery. Summary of the Invention [Problem to be solved by the invention]

[0006] In one embodiment of the present invention, a three-dimensional network structure composite material for lithium batteries, its preparation method, and application are provided. The three-dimensional network structure composite material is obtained by in-situ growing silicon nanowires in the through-pores of porous carbon microspheres by chemical vapor deposition or molten salt electrolysis, followed by a carbon coating. When the three-dimensional network structure composite material is used as the negative electrode active material in a lithium battery, it can provide the lithium battery with a low volume expansion coefficient, a high mass-specific capacity, good electrical conductivity, and cycle stability. [Means for solving the problem]

[0007] In a first aspect, an embodiment of the present invention relates to a three-dimensional network structure composite material for a lithium battery, the three-dimensional network structure composite material comprising: porous carbon microspheres having a network structure of through-holes; silicon nanowires distributed in the through-holes of the porous carbon microspheres; and a carbon shell; Here, the silicon nanowires are formed by catalyzing a silicon-containing gas with Au or Ag and depositing it in the through-holes. Specifically, Au or Ag is first evaporated and deposited on the pore walls of the through-holes of the porous carbon microspheres to form a metal film of Au or Ag. Thereafter, a silicon-containing gas is introduced and catalyzed by Au or Ag to precipitate silicon atoms, which are then deposited in the through-holes to form silicon nanowires. Alternatively, the silicon nanowires are formed after depositing silane gas in the through-holes to form silicon oxide nanoparticles, and then electrolyzing the silicon oxide nanoparticles in the through-holes in a molten salt system; the silicon nanowires form a three-dimensional network structure within the through-holes of the porous carbon microspheres; The through-holes of the porous carbon microspheres have an average pore size of 15 nm to 50 nm.

[0008] Preferably, the mass of the porous carbon microspheres accounts for 30% to 70% of the total mass of the three-dimensional network structure composite material; the mass of the silicon nanowires accounts for 15% to 60% of the total mass of the three-dimensional network structure composite material; The particle diameter Dv50 of the composite material having the three-dimensional network structure is 1 μm to 100 μm.

[0009] Preferably, the carbon shell is coated on the outermost layer of the composite material of the three-dimensional network structure, and the mass of the carbon shell accounts for 1% to 20% of the total mass of the composite material of the three-dimensional network structure.

[0010] In a second aspect, an embodiment of the present invention relates to a method for preparing a three-dimensional network structure composite material according to the first aspect, said method comprising: placing the porous carbon microspheres having through-holes with a network structure in a deposition device under a protective gas atmosphere, and evaporating Au or Ag to deposit it on the pore walls of the through-holes of the porous carbon microspheres, thereby forming a metal film of Au or Ag as a catalyst; A silicon source gas is introduced into a deposition apparatus for vapor deposition, the silicon source gas is deposited on the surface of the metal film, and the temperature is increased by heating, and silicon nanowires are formed by the catalytic action of metal Au or Ag, thereby obtaining a precursor material containing silicon nanowires with a three-dimensional network structure; A precursor material including silicon nanowires having a three-dimensional network structure is coated with carbon to form a carbon shell, thereby obtaining a composite material having a three-dimensional network structure; Includes:

[0011] Preferably, the protective gas is nitrogen gas or argon gas, and the flow rate of the protective gas is 1 L / min to 50 L / min; the silicon source material comprises a silicon-containing gas and / or a silicon-containing liquid; the silicon-containing gas includes monosilane and / or dichlorosilane; the silicon-containing liquid includes one or more of trisilane, trichlorosilane, tetrachlorosilane, trimethoxysilane, tetramethoxysilane, triethoxysilane, and tetraethoxysilane; When the silicon source material is the silicon-containing gas, the silicon-containing gas is directly introduced into the deposition apparatus or carried to the deposition apparatus by a carrier gas, and the flow rate of the silicon-containing gas is 0.5 L / min to 50 L / min, and the carrier gas is nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min; When the silicon source material is the silicon-containing liquid, the silicon-containing liquid is transported to the deposition device by bubbling with a carrier gas, the carrier gas being nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min.

[0012] Preferably, the deposition apparatus comprises one of a rotary furnace, a tubular furnace, a bell furnace, or a fluidized bed; The temperature at which the silicon source gas is introduced into the deposition apparatus and vapor-phase grown is 600°C to 1200°C, and the time is 1 hour to 20 hours. the carbon coating method includes any one of vapor phase coating, liquid phase coating, and solid phase coating, and the mass of the carbon shell formed by the carbon coating accounts for 1% to 20% of the total mass of the three-dimensional network structure composite material; The method of introducing the silicon source gas into a deposition apparatus to perform vapor deposition includes a thermal plasma method.

[0013] In a third aspect, an embodiment of the present invention relates to a method for preparing a three-dimensional network structure composite material according to the first aspect, said method comprising: placing porous carbon microspheres having through-holes with a network structure in a deposition apparatus under a protective gas atmosphere, introducing a silicon source gas into the deposition apparatus to cause vapor deposition, and depositing the silicon source gas in the through-holes of the porous carbon microspheres to obtain a precursor material; the precursor material is placed in an electrolytic cell and electrolyzed, using the precursor material as a cathode, graphite as an anode, and a molten salt system as an electrolyte, and the voltage and temperature of the electrolytic cell are controlled while applying current in an argon atmosphere to decompose the silicon dioxide deposited in the through-holes of the porous carbon microspheres to form silicon nanowires, thereby obtaining an electrolytic material containing silicon nanowires with a three-dimensional network structure; cooling, washing, vacuum drying, and carbon coating the electrolytic material, and then sieving the electrolytic material to obtain a composite material having a three-dimensional network structure; Includes:

[0014] Preferably, the protective gas is nitrogen gas or argon gas, and the flow rate of the protective gas is 1 L / min to 50 L / min; the silicon source material comprises a silicon-containing gas and / or a silicon-containing liquid; the silicon-containing gas includes monosilane and / or dichlorosilane; the silicon-containing liquid includes one or more of trisilane, trichlorosilane, tetrachlorosilane, trimethoxysilane, tetramethoxysilane, triethoxysilane, and tetraethoxysilane; When the silicon source material is the silicon-containing gas, the silicon-containing gas is directly introduced into the deposition apparatus or carried to the deposition apparatus by a carrier gas, and the flow rate of the silicon-containing gas is 0.5 L / min to 50 L / min, and the carrier gas is nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min; When the silicon source material is the silicon-containing liquid, the silicon-containing liquid is transported to the deposition device by bubbling with a carrier gas, where the carrier gas is nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min.

[0015] Preferably, the deposition apparatus comprises one of a rotary furnace, a tubular furnace, a bell furnace, or a fluidized bed; The temperature at which the silicon source gas is introduced into the deposition apparatus and vapor-phase grown is 600°C to 1200°C, and the time is 1 hour to 20 hours. the carbon coating method includes any one of vapor phase coating, liquid phase coating, and solid phase coating, and the mass of the carbon shell formed by the carbon coating accounts for 1% to 20% of the total mass of the three-dimensional network structure composite material; The method of introducing the silicon source gas into a deposition apparatus to perform vapor deposition includes a thermal plasma method.

[0016] In a fourth aspect, an embodiment of the present invention relates to a lithium battery comprising a three-dimensional network structure composite material according to the first aspect above. [Effects of the Invention]

[0017] In the present invention, a three-dimensional network composite material and its preparation method and application are provided. Silicon nanowires are grown in situ in the through-pores of porous carbon microspheres by chemical vapor deposition or molten salt electrolysis, and then coated with carbon to obtain a three-dimensional network composite material. The through-pores of the porous carbon microspheres have a skeleton structure with high mechanical strength. When subjected to the expansion force of lithium insertion, the high-strength skeleton structure effectively suppresses the volume expansion of the silicon nanowires, maintaining the structural stability of the anode material and improving the cycling performance of the material. Meanwhile, the silicon nanowires are intertwined with each other in the through-pores to form a three-dimensional network structure, which not only increases the capacity of the material but also forms an interconnected conductive network, providing a battery assembled with the anode material with a higher specific charge capacity and better conductivity. Furthermore, the three-dimensional network silicon nanowires have better electrical conductivity than silicon particles, good conductivity at the electrode / electrolyte interface, and are less likely to burst during charging and discharging, thereby improving the cycling stability of the battery.

[0018] In an embodiment of the present invention, the three-dimensional network structure composite material is applied as a negative electrode active material in a lithium battery, thereby providing the lithium battery with a low volume expansion rate, a high mass-specific capacity, good electrical conductivity, and a long cycle life. [Brief explanation of the drawings]

[0019] The technical solutions of the embodiments of the present invention will be described in more detail below with reference to the drawings and examples.

[0020] [Figure 1] 1 is a flowchart of a method for preparing a three-dimensional network structure composite material by chemical vapor deposition according to an embodiment of the present invention. [Figure 2]1 is a flowchart of a method for preparing a composite material with a three-dimensional network structure by molten salt electrolysis according to an embodiment of the present invention. [Figure 3] 1 is a schematic structural diagram showing a cross section of a composite material having a three-dimensional mesh structure according to an embodiment of the present invention. [Figure 4] FIG. 2 is a charge / discharge curve diagram of a button battery assembled using the three-dimensional network structure composite material prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, the present invention will be described in more detail with reference to the drawings and specific examples. However, it should be understood that these examples are merely for the purpose of explaining the present invention in more detail and are not intended to limit the present invention in any way, i.e., they are not intended to limit the protection scope of the present invention.

[0022] In an embodiment of the present invention, a three-dimensional network structure composite material for a lithium battery is provided. The three-dimensional network structure composite material includes porous carbon microspheres having a network structure of through-holes, silicon nanowires distributed in the through-holes of the porous carbon microspheres, and a carbon shell. The particle diameter Dv50 of the three-dimensional network structure composite material is 1 μm to 100 μm, preferably 20 μm.

[0023] Here, the silicon nanowires are formed by catalyzing a silicon-containing gas with Au or Ag and depositing it in the through-holes. Specifically, first, Au or Ag is evaporated and deposited on the pore walls of the through-holes of the porous carbon microspheres to form a metal film of Au or Ag. Then, a silicon-containing gas is introduced and catalyzed by Au or Ag to precipitate silicon atoms, which are deposited in the through-holes, thereby forming silicon nanowires. Alternatively, silicon nanowires are formed after depositing silane gas into the through-holes to form silicon oxide nanoparticles, and then electrolyzing the silicon oxide nanoparticles in the through-holes in a molten salt system.

[0024] Silicon nanowires are one-dimensional semiconductor nanomaterials that form a three-dimensional network structure within the through-holes of the porous carbon microspheres, and the mass of the silicon nanowires accounts for 15% to 60%, preferably 45%, of the total mass of the three-dimensional network structure composite material.

[0025] The porous carbon microspheres have an average pore size of 15 to 50 nm, and the mass of the porous carbon microspheres accounts for 30 to 70%, preferably 50%, of the total mass of the composite material with a three-dimensional network structure.

[0026] The carbon shell is coated on the outermost layer of the composite material having a three-dimensional network structure, and the mass of the carbon shell accounts for 1% to 20%, preferably 5%, of the total mass of the composite material having a three-dimensional network structure.

[0027] In an embodiment of the present invention, a method for preparing the above three-dimensional network structure composite material is provided, the preparation method being a chemical vapor deposition method, which specifically includes the following steps, as shown in FIG.

[0028] In step 110, the porous carbon microspheres having a network of through-holes are placed in a deposition apparatus under a protective gas atmosphere, and Au or Ag is evaporated and deposited on the pore walls of the through-holes of the porous carbon microspheres to form a metal film of Au or Ag.

[0029] Here, the protective gas is nitrogen gas or argon gas, the flow rate of the protective gas is 1 L / min to 50 L / min, and the deposition apparatus includes any of a rotary furnace, a tubular furnace, a bell furnace, or a fluidized bed.

[0030] The deposition process of Au or Ag is a conventional method. Specifically, Au or Ag is placed in a tungsten, molybdenum or alumina crucible, which is then placed in a vacuum heating furnace. -2 The mixture is heated to 1200-1400°C at a vapor pressure of 1 Pa to evaporate the Au or Ag into a gas, and the Au or Ag gas is then introduced into a deposition device and cooled to deposit on the pore walls of the through-holes of the porous carbon microspheres. The deposition time is 10-30 minutes, and a 1-20 nm thick Au or Ag metal film is formed.

[0031] In step 120, a silicon source gas is introduced into a deposition apparatus for vapor deposition, and the silicon source gas is deposited on the surface of the metal film and heated to increase the temperature, and silicon nanowires are formed through the catalytic action of metal Au or Ag, thereby obtaining a precursor material containing silicon nanowires with a three-dimensional network structure.

[0032] Here, the silicon source material includes a silicon-containing gas and / or a silicon-containing liquid, the silicon-containing gas includes monosilane and / or dichlorosilane, and the silicon-containing liquid includes one or more of trisilane, trichlorosilane, tetrachlorosilane, trimethoxysilane, tetramethoxysilane, triethoxysilane, and tetraethoxysilane.

[0033] When the silicon source material is a silicon-containing gas, the silicon-containing gas is directly introduced into the deposition apparatus or carried to the deposition apparatus by a carrier gas, and the flow rate of the directly introduced silicon-containing gas is 0.5 L / min to 50 L / min, and the carrier gas is nitrogen gas or argon gas, and the flow rate of the carrier gas is 0.5 L / min to 50 L / min.

[0034] When the silicon source material is a silicon-containing liquid, the silicon-containing liquid is transported to the deposition device by bubbling with a carrier gas, which is nitrogen gas or argon gas, and the flow rate of the carrier gas is 0.5 L / min to 50 L / min.

[0035] The temperature for vapor deposition of the silicon source gas is 600° C. to 1200° C., and the deposition time is 1 hour to 20 hours.

[0036] As an option, in this preparation method, the method of introducing the silicon source gas into the deposition apparatus for vapor deposition can be a thermal plasma method. Specifically, industrial silicon powder is placed in the high-temperature region of the plasma treatment apparatus, and porous carbon microspheres having a network structure of through-holes are placed in the condensation region of the plasma treatment apparatus. The industrial silicon powder is vaporized and dissociated into a silicon-containing plasma gas through the thermal plasma treatment apparatus, and the silicon-containing plasma gas is transported to the condensation region by a carrier gas and deposited in the pores of the porous carbon microspheres having a network structure of through-holes.

[0037] Specifically, the silicon nanowire formation process involves vapor deposition of a silicon source gas carried by a carrier gas into a deposition system. The silicon source gas is deposited on the surface of a metal film and heated to 370°C. The Au or Ag and silicon in the metal film form metal-silicon alloy droplets. At the same time, silicon atoms in the silicon source gas are absorbed into the metal-silicon alloy droplets. When the silicon atoms reach a supersaturated state in the metal-silicon alloy droplets, they precipitate and deposit between the metal film and the base. Silicon nuclei then form and continue to deposit, forming silicon nanowires, which form a three-dimensional network structure within the through-holes of the porous carbon microspheres. The resulting silicon nanowires have a diameter of 10 nm.

[0038] In step 130, the precursor material including the three-dimensional network of silicon nanowires is carbon-coated to form a carbon shell, resulting in a three-dimensional network of composite material.

[0039] Here, the carbon coating method includes any of vapor phase coating, liquid phase coating, and solid phase coating, and the mass of the carbon shell formed by the carbon coating accounts for 1% to 20% of the total mass of the composite material with a three-dimensional mesh structure.

[0040] In an embodiment of the present invention, a method for preparing the above three-dimensional network structure composite material is provided, the preparation method being a molten salt electrolysis method, which specifically includes the following steps, as shown in FIG. 2:

[0041] In step 210, in a protective gas atmosphere, the porous carbon microspheres having a network of through-holes are placed in a deposition apparatus, and a silicon source gas is introduced into the deposition apparatus for vapor deposition, so that the silicon source gas is deposited in the through-holes of the porous carbon microspheres to obtain a precursor material.

[0042] Here, the protective gas is nitrogen gas or argon gas, the flow rate of the protective gas is 1 L / min to 50 L / min, the deposition apparatus includes any of a rotary furnace, a tubular furnace, a bell-type furnace, or a fluidized bed, the deposition temperature is 600°C to 1200°C, and the deposition time is 1 hour to 20 hours.

[0043] As an option, in this preparation method, the method of introducing the silicon source gas into the deposition apparatus for vapor deposition can be a thermal plasma method. Specifically, industrial silicon powder is placed in the high-temperature region of the plasma treatment apparatus, and porous carbon microspheres having a network structure of through-holes are placed in the condensation region of the plasma treatment apparatus. The industrial silicon powder is vaporized and dissociated into a silicon-containing plasma gas through the thermal plasma treatment apparatus, and the silicon-containing plasma gas is transported to the condensation region by a carrier gas and deposited in the pores of the porous carbon microspheres having a network structure of through-holes.

[0044] In step 220, the precursor material is placed in an electrolytic cell and electrolyzed, using the precursor material as the cathode, graphite as the anode, and a molten salt system as the electrolyte. The voltage and temperature of the electrolytic cell are controlled, and electricity is passed through in an argon atmosphere to decompose the silicon dioxide deposited in the through-holes of the porous carbon microspheres to form silicon nanowires, thereby obtaining an electrolytic material containing silicon nanowires with a three-dimensional network structure.

[0045] Here, the silicon source material includes a silicon-containing gas and / or a silicon-containing liquid, the silicon-containing gas includes monosilane and / or dichlorosilane, and the silicon-containing liquid includes one or more of trisilane, trichlorosilane, tetrachlorosilane, trimethoxysilane, tetramethoxysilane, triethoxysilane, and tetraethoxysilane.

[0046] When the silicon source material is a silicon-containing gas, the silicon-containing gas is directly introduced into the deposition apparatus, and the flow rate of the silicon-containing gas is 0.5 L / min to 50 L / min.

[0047] When the silicon source material is a silicon-containing liquid, the silicon-containing liquid is transported to the deposition device by bubbling with a carrier gas, where the carrier gas is nitrogen gas or argon gas, and the flow rate of the carrier gas is 0.5 L / min to 50 L / min.

[0048] In this example, the molten salt system used in the process for forming silicon nanowires by electrolysis is CaCl-NaCl. The electrolytic cell voltage is controlled to 2V-3.2V, the electrolytic cell temperature is controlled to 550°C-1000°C, and electricity is applied for 5-20 hours in an argon atmosphere. The diameter of the formed silicon nanowires is 10 nm.

[0049] In step 230, the electrolytic material is cooled, washed, vacuum dried, carbon coated, and sieved to obtain a three-dimensional network structure composite material.

[0050] Here, the carbon coating method includes any of vapor phase coating, liquid phase coating, and solid phase coating, and the mass of the carbon shell formed by the carbon coating accounts for 1% to 20%, preferably 5%, of the total mass of the composite material with a three-dimensional mesh structure.

[0051] Figure 3 shows the schematic structure of the three-dimensional network-structured composite material obtained using the two preparation methods. Figure 3 shows that a network-structured silicon nanowire was formed within the through-pores of the porous carbon microspheres. Silicon nanowires are one-dimensional semiconductor nanomaterials. During the charge / discharge process, the volume expansion rate of the silicon nanowires is lower than that of the nanosilicon particles, avoiding the problem of nanosilicon particle pulverization. This effectively controls the stability of the SEI film on the surface of the anode particles, preventing the SEI film from continuously depleting lithium ions, reducing the risk of rupture during charge / discharge, and improving the cycle stability of the battery. Furthermore, the silicon nanowires intertwine with each other within the through-pores, forming a three-dimensional network that not only enhances the capacity of the material but also forms an interconnected conductive network, providing batteries assembled with the anode material with higher specific charge capacity and better conductivity.

[0052] The three-dimensional network structure composite material according to the embodiment of the present invention can be used as a negative electrode active material in a lithium battery.

[0053] Lithium batteries using the three-dimensional network structure composite material of the present invention as a negative electrode active material include, but are not limited to, liquid lithium ion batteries, semi-solid lithium ion batteries, quasi-solid lithium ion batteries, and all-solid electrolyte lithium ion batteries.

[0054] The lithium battery prepared using the negative electrode material according to the embodiment of the present invention has low volume expansion rate, high mass specific capacity, good conductivity performance and cycle life.

[0055] In order to better understand the technical solution of the present invention, several specific examples are given below to respectively illustrate the preparation process and properties of the three-dimensional mesh structure composite material of the present invention.

[0056] Example 1 This example provides a preparation process and property test of a three-dimensional mesh structure composite material using chemical vapor deposition, and the specific steps are as follows: 1. In a nitrogen atmosphere with a flow rate of 50 L / min, porous carbon microspheres with mesh-like through-holes are placed in a rotary furnace, and Au gas is deposited on the pore walls of the porous carbon microspheres to form an Au metal film. 2. Monosilane is transported to a rotary furnace using nitrogen gas as a carrier gas at a flow rate of 50 L / min, where it is grown in the vapor phase and deposited at 600°C for 1 hour, depositing silicon-containing gas on the surface of the Au metal film.The film is then heated to 370°C, and silicon nanowires are formed by the catalytic action of the Au metal, yielding a precursor material containing silicon nanowires with a three-dimensional network structure. 3. A precursor material containing silicon nanowires with a three-dimensional network structure is vapor-coated to form a carbon shell, resulting in a composite material with a three-dimensional network structure.

[0057] A negative electrode sheet was made using the composite material with a three-dimensional network structure prepared in this example, and a button battery was assembled and tested.

[0058] Specifically, to prepare the negative electrode sheet, a three-dimensional mesh structure composite material, carbon black as a conductive additive, and adhesive (sodium cellulose and styrene butadiene rubber in a mass ratio of 1:1) were weighed out in a mass ratio of 95:2:3, and a slurry was prepared in a beater at room temperature. The prepared slurry was uniformly applied to copper foil and dried in a fan dryer at 50°C for 2 hours. After that, the foil was cut into 8 x 8 mm pole pieces, which were then further dried in a vacuum dryer at 100°C for 10 hours under vacuum. The dried pole pieces were immediately transferred into a glove box for battery assembly.

[0059] Specifically, the button battery was assembled in a glove box containing a high-purity Ar atmosphere. Metallic lithium was used as the counter electrode, and a solution of ethylene carbonate (EC) / dimethyl carbonate (DMC) (volume ratio v:v = 1:1) containing 1 mol / L of LiPF6 was used as the electrolyte. Polyethylene was used as the separator, and the battery was assembled.

[0060] The test method used a charger / discharger to conduct a constant current charge / discharge mode test, with the discharge end voltage being 0.005V and the charge end voltage being 1.5V. The charge / discharge test was conducted at a current density of C / 10, and the charge specific capacity and the coulombic efficiency of the first cycle of the button battery were measured. The test results are shown in Table 1.

[0061] The charge-discharge curve of the button battery assembled using the three-dimensional network structure composite material prepared in the example of the present invention is shown in FIG.

[0062] Example 2 This example provides a preparation process and property test of a three-dimensional mesh structure composite material using chemical vapor deposition, and the specific steps are as follows: 1. In an argon atmosphere with a flow rate of 40 L / min, porous carbon microspheres with mesh-like through-holes are placed in a tubular furnace, and Ag gas is deposited on the pore walls of the porous carbon microspheres to form an Ag metal film. 2. Trisilane is transported to a tubular furnace using a bubbling method with argon gas as a carrier gas at a flow rate of 40 L / min, and vapor phase growth is carried out. By depositing it at 800°C for 5 hours, silicon-containing gas is deposited on the surface of the Ag metal film. The film is then heated to 370°C, and silicon nanowires are formed by the catalytic action of the Ag metal, resulting in a precursor material containing silicon nanowires with a three-dimensional network structure. 3. A precursor material containing silicon nanowires with a three-dimensional network structure is vapor-coated to form a carbon shell, resulting in a composite material with a three-dimensional network structure.

[0063] The three-dimensional mesh structure composite material prepared in this example was used to fabricate a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0064] Example 3 This example provides a preparation process and property test of a three-dimensional mesh structure composite material using chemical vapor deposition, and the specific steps are as follows: 1. In a nitrogen atmosphere with a flow rate of 30 L / min, porous carbon microspheres with mesh-like through-holes are placed in a bell-type furnace, and Au gas is deposited on the pore walls of the porous carbon microspheres to form an Au metal film. 2. Dichlorosilane is transported to a bell-type furnace using nitrogen gas as a carrier gas at a flow rate of 30 L / min, and vapor phase growth is carried out. Deposition is carried out at 900°C for 10 hours, depositing silicon-containing gas on the surface of the Au metal film. The film is then heated to 370°C, and silicon nanowires are formed by the catalytic action of the Au metal, yielding a precursor material containing silicon nanowires with a three-dimensional network structure. 3. A liquid-phase coating is applied to a precursor material containing silicon nanowires with a three-dimensional network structure to form a carbon shell, resulting in a composite material with a three-dimensional network structure.

[0065] The three-dimensional mesh structure composite material prepared in this example was used to fabricate a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0066] Example 4 This example provides a preparation process and property test of a three-dimensional mesh structure composite material using chemical vapor deposition, and the specific steps are as follows: 1. Porous carbon microspheres with a mesh-like through-hole structure are placed in a fluidized bed under an argon atmosphere with a flow rate of 10 L / min, and Ag gas is deposited on the pore walls of the porous carbon microspheres to form an Ag metal film. 2. A mixture of trichlorosilane and tetrachlorosilane is transported into a fluidized bed using a bubbling method with argon gas as a carrier gas at a flow rate of 5 L / min, and vapor phase growth is carried out. By depositing at 1000°C for 15 hours, silicon-containing gas is deposited on the surface of the Ag metal film. The film is then heated to 370°C, and silicon nanowires are formed through the catalytic action of the Ag metal, resulting in a precursor material containing silicon nanowires with a three-dimensional network structure. 3. A precursor material containing silicon nanowires with a three-dimensional network structure is vapor-coated to form a carbon shell, resulting in a composite material with a three-dimensional network structure.

[0067] The three-dimensional mesh structure composite material prepared in this example was used to fabricate a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0068] Button cells were assembled according to the method of Example 1 above, and their electrochemical properties were evaluated through testing and recorded in Table 1.

[0069] Example 5 This example provides a preparation process and property test of a three-dimensional mesh structure composite material using chemical vapor deposition, and the specific steps are as follows: 1. In a nitrogen atmosphere with a flow rate of 1 L / min, porous carbon microspheres with a mesh-like through-hole structure are placed in a fluidized bed, and Au gas is deposited on the pore walls of the porous carbon microspheres to form an Au metal film. 2. Monosilane and dichlorosilane are used as gaseous silicon sources, and are directly introduced into a fluidized bed at a flow rate of 0.5 L / min to cause vapor deposition. The deposition is carried out at 1200°C for 20 hours, depositing silicon-containing gas on the surface of the Au metal film. The film is then heated to 370°C, and silicon nanowires are formed through the catalytic action of the metal Au, resulting in a precursor material containing silicon nanowires with a three-dimensional network structure. 3. A precursor material containing silicon nanowires with a three-dimensional network structure is vapor-coated to form a carbon shell, resulting in a composite material with a three-dimensional network structure.

[0070] The three-dimensional mesh structure composite material prepared in this example was used to fabricate a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0071] Example 6 This example provides the preparation process and property test of a three-dimensional mesh structure composite material, and the specific steps are as follows: 1. In a nitrogen atmosphere with a flow rate of 10 L / min, porous carbon microspheres with a mesh-like through-hole structure are placed in a rotary furnace, and Au gas is deposited on the pore walls of the porous carbon microspheres to form an Au metal film. 2. Vapor deposition is performed using a thermal plasma method. Specifically, industrial silicon powder is used as the silicon source material, the industrial silicon powder is placed in the high-temperature region of a plasma treatment device, and a porous carbon microsphere material with an Au metal film in the through-holes is placed in the condensation region of the plasma treatment device. The industrial silicon powder is vaporized through the plasma treatment device and dissociated into silicon-containing plasma gas, and the silicon-containing plasma gas is transported to the condensation region by a carrier gas, and the silicon-containing gas is deposited on the surface of the Au metal film. 3. The material deposited in step 2 is placed in a rotary furnace and heated to 370°C, where silicon nanowires are formed through the catalytic action of metal Au, yielding a precursor material containing silicon nanowires with a three-dimensional network structure. 4. A precursor material containing silicon nanowires with a three-dimensional network structure is vapor-coated to form a carbon shell, resulting in a composite material with a three-dimensional network structure.

[0072] The three-dimensional mesh structure composite material prepared in this example was used to fabricate a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0073] Example 7 This example provides a preparation process and property test of a three-dimensional mesh structure composite material using molten salt electrolysis, and the specific steps are as follows: 1. In an argon atmosphere with a flow rate of 50 L / min, porous carbon microspheres with a mesh-like through-hole structure are placed in a tubular furnace. Trimethoxysilane is transported into the tubular furnace by bubbling with argon gas as a carrier gas with a flow rate of 50 L / min to cause vapor growth. The vapor growth temperature is 600°C and the time is 1 hour. The silicon-containing gas is deposited in the through-holes of the porous carbon microspheres to obtain a precursor material. 2. The precursor material is placed in an electrolytic cell and electrolysis is carried out, with the precursor material as the cathode, graphite as the anode, and a CaCl2-NaCl molten salt system as the electrolyte. The voltage of the electrolytic cell is controlled at 2 V and the temperature at 550°C, and electricity is passed through for 20 hours in an argon atmosphere to decompose the silicon dioxide deposited in the through-holes of the porous carbon microspheres and form silicon nanowires, thereby obtaining an electrolytic material containing silicon nanowires with a three-dimensional network structure. 3. The electrolytic material is cooled, washed, vacuum dried, and carbon-coated, and after sieving, a three-dimensional mesh structure composite material is obtained.

[0074] The three-dimensional mesh structure composite material prepared in this example was used to fabricate a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0075] Example 8 This example provides a preparation process and property test of a three-dimensional mesh structure composite material using molten salt electrolysis, and the specific steps are as follows: 1. In an argon atmosphere with a flow rate of 40 L / min, porous carbon microspheres with a mesh-like through-hole structure are placed in a tubular furnace. Tetramethoxysilane is transported into the tubular furnace by bubbling with argon gas as a carrier gas with a flow rate of 40 L / min to cause vapor growth. The vapor growth temperature is 800°C and the time is 5 hours. The silicon-containing gas is deposited in the through-holes of the porous carbon microspheres to obtain a precursor material. 2. The precursor material is placed in an electrolytic cell and electrolysis is carried out, with the precursor material as the cathode, graphite as the anode, and a CaCl2-NaCl molten salt system as the electrolyte. The voltage of the electrolytic cell is controlled at 2.2 V and the temperature at 600°C, and electricity is passed through for 18 hours in an argon atmosphere to decompose the silicon dioxide deposited in the through-holes of the porous carbon microspheres and form silicon nanowires, thereby obtaining an electrolytic material containing silicon nanowires with a three-dimensional network structure. 3. The electrolytic material is cooled, washed, vacuum dried, and carbon-coated, and after sieving, a three-dimensional mesh structure composite material is obtained.

[0076] The three-dimensional mesh structure composite material prepared in this example was used to fabricate a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0077] Button cells were assembled according to the method of Example 1 above, and their electrochemical properties were evaluated through testing and recorded in Table 1.

[0078] Example 9 This example provides a preparation process and property test of a three-dimensional mesh structure composite material using molten salt electrolysis, and the specific steps are as follows: 1. In an argon atmosphere with a flow rate of 30 L / min, porous carbon microspheres with a mesh-like through-hole structure are placed in a bell-type furnace. Triethoxysilane is transported into the bell-type furnace by bubbling with argon gas as a carrier gas with a flow rate of 30 L / min to cause vapor growth. The vapor growth temperature is 1000°C and the time is 10 hours. The silicon-containing gas is deposited in the through-holes of the porous carbon microspheres to obtain a precursor material. 2. The precursor material is placed in an electrolytic cell and electrolysis is carried out, with the precursor material as the cathode, graphite as the anode, and a CaCl2-NaCl molten salt system as the electrolyte. The voltage of the electrolytic cell is controlled at 2.5 V and the temperature at 800°C, and electricity is passed through for 15 hours in an argon atmosphere to decompose the silicon dioxide deposited in the through-holes of the porous carbon microspheres and form silicon nanowires, thereby obtaining an electrolytic material containing silicon nanowires with a three-dimensional network structure. 3. The electrolytic material is cooled, washed, vacuum dried, and carbon-coated, and after sieving, a three-dimensional mesh structure composite material is obtained.

[0079] The three-dimensional mesh structure composite material prepared in this example was used to fabricate a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0080] Example 10 This example provides a preparation process and property test of a three-dimensional mesh structure composite material using molten salt electrolysis, and the specific steps are as follows: 1. In an argon atmosphere with a flow rate of 10 L / min, porous carbon microspheres with a network structure were placed in a bell-type furnace. Tetraethoxysilane was transported into the bell-type furnace by bubbling with argon gas as a carrier gas at a flow rate of 10 L / min to cause vapor growth. The vapor growth temperature was 1100°C for 15 hours, and the silicon-containing gas was deposited in the pores of the porous carbon microspheres to obtain a precursor material. 2. The precursor material is placed in an electrolytic cell and electrolysis is carried out, with the precursor material as the cathode, graphite as the anode, and a CaCl2-NaCl molten salt system as the electrolyte. The voltage of the electrolytic cell is controlled at 2.7 V and the temperature at 900°C, and electricity is passed through for 10 hours in an argon atmosphere to decompose the silicon dioxide deposited in the through-holes of the porous carbon microspheres and form silicon nanowires, thereby obtaining an electrolytic material containing silicon nanowires with a three-dimensional network structure. 3. The electrolytic material is cooled, washed, vacuum dried, and carbon-coated, and after sieving, a three-dimensional mesh structure composite material is obtained.

[0081] The three-dimensional mesh structure composite material prepared in this example was used to fabricate a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0082] Example 11 This example provides a preparation process and property test of a three-dimensional mesh structure composite material using molten salt electrolysis, and the specific steps are as follows: 1. In an argon atmosphere with a flow rate of 1 L / min, porous carbon microspheres with a mesh-like through-hole structure are placed in a bell-type furnace. Liquid trimethoxysilane and tetramethoxysilane are transported into the bell-type furnace by bubbling with argon gas as a carrier gas with a flow rate of 0.5 L / min to cause vapor growth. The vapor growth temperature is 1200°C and the time is 20 hours. Silicon-containing gas is deposited in the through-holes of the porous carbon microspheres to obtain a precursor material. 2. The precursor material is placed in an electrolytic cell and electrolysis is carried out, with the precursor material as the cathode, graphite as the anode, and a CaCl2-NaCl molten salt system as the electrolyte. The voltage of the electrolytic cell is controlled to 3.2 V and the temperature to 1000°C, and electricity is passed through for 5 hours in an argon atmosphere to decompose the silicon dioxide deposited in the through-holes of the porous carbon microspheres and form silicon nanowires, thereby obtaining an electrolytic material containing silicon nanowires with a three-dimensional network structure. 3. The electrolytic material is cooled, washed, vacuum dried, and carbon-coated, and after sieving, a three-dimensional mesh structure composite material is obtained.

[0083] The three-dimensional mesh structure composite material prepared in this example was used to fabricate a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0084] To better explain the effects of the examples of the present invention, comparative examples 1 and 2 are compared with the examples.

[0085] (Comparative Example 1) This comparative example provides a preparation method and property test of a conventional silicon-carbon composite material, and the specific steps are as follows: 1. 200g of nanosilicon particles and 500g of phenolic resin powder are placed in a hydrothermal reactor and subjected to hydrothermal treatment. The pressure is set to 5Mpa and the heating temperature to 300°C. After 8 hours of heating, the material is removed, washed and filtered until the filtrate becomes colorless and transparent, and then placed in a vacuum dryer for drying to obtain the precursor material. 2. After the precursor materials are uniformly mixed, they are placed in a high-temperature furnace, heated to 900°C at a rate of 3°C / min, and kept at that temperature for 6 hours in a nitrogen atmosphere to carbonize them, obtaining a silicon-carbon composite material.

[0086] The silicon-carbon composite material prepared in this comparative example was used to prepare a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0087] (Comparative Example 2) This comparative example provides a preparation process and property test of a silicon-carbon composite material using chemical vapor deposition, and the specific steps are as follows: 1. In a nitrogen atmosphere with a flow rate of 50 L / min, monosilane is transported to a rotary furnace by nitrogen gas as a carrier gas with a flow rate of 50 L / min, and vapor phase growth is carried out. By depositing at 600°C for 1 hour, silicon-containing gas is deposited on the pore walls of the through-holes of the porous carbon microspheres, and a precursor material is obtained. 2. The precursor material is vapor-coated to form a carbon shell, resulting in a silicon-carbon composite material.

[0088] The silicon-carbon composite material prepared in this comparative example was used to prepare a negative electrode sheet, and a button battery was assembled and tested. The specific process was the same as in Example 1, and the test results are shown in Table 1.

[0089] Table 1 shows the test results of the charge specific capacity and first cycle coulombic efficiency of the button batteries assembled in Examples 1 to 11 and Comparative Example 1.

[0090] [Table 1]

[0091] Comparing the test data in Table 1, it can be seen that the charge specific capacity and first cycle Coulombic efficiency of the button batteries assembled with the three-dimensional network structure composites of Examples 1 to 11 were both superior to those of the button batteries assembled in Comparative Examples 1 and 2. This is because, in the three-dimensional network structure composites prepared in Examples 1 to 11 of the present invention, silicon nanowires are grown in situ within the through-pores of the porous carbon microspheres, and the through-pore structure of the porous carbon microspheres provides a framework with high mechanical strength. When subjected to expansion forces due to lithium insertion, the high-strength framework effectively suppresses the volume expansion of the silicon nanowires, maintaining the structural stability of the anode material and improving the cycling performance of the material. Meanwhile, the silicon nanowires form an alternately entangled three-dimensional network structure within the through-pores, increasing the capacity of the material and forming an interconnected conductive network, thereby endowing the anode material with a higher charge specific capacity and better conductivity. Furthermore, silicon nanowires with a three-dimensional network structure have better electrical conductivity than silicon particles, have good conductive properties at the electrode / electrolyte interface, and are less likely to explode during charging and discharging, thereby improving the cycle stability of the battery.

[0092] The above-mentioned specific embodiments further describe the objectives, technical solutions and beneficial effects of the present invention, and the above are only specific embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0093] (Addendum) (Appendix 1) A three-dimensional network structure composite material for a lithium battery, comprising: The composite material with a three-dimensional network structure includes porous carbon microspheres having through-holes with a network structure, silicon nanowires distributed in the through-holes of the porous carbon microspheres, and a carbon shell; Here, the silicon nanowires are formed by catalyzing a silicon-containing gas with Au or Ag and depositing it in the through-holes. Specifically, Au or Ag is first evaporated and deposited on the pore walls of the through-holes of the porous carbon microspheres to form a metal film of Au or Ag. Thereafter, a silicon-containing gas is introduced and catalyzed by Au or Ag to precipitate silicon atoms, which are then deposited in the through-holes to form silicon nanowires. Alternatively, the silicon nanowires are formed after depositing silane gas in the through-holes to form silicon oxide nanoparticles, and then electrolyzing the silicon oxide nanoparticles in the through-holes in a molten salt system; the silicon nanowires form a three-dimensional network structure within the through-holes of the porous carbon microspheres; The average pore size of the through-holes of the porous carbon microspheres is 15 nm to 50 nm. A three-dimensional network structure composite material for lithium batteries, characterized by:

[0094] (Appendix 2) the mass of the porous carbon microspheres accounts for 30% to 70% of the total mass of the three-dimensional network structure composite material; the mass of the silicon nanowires accounts for 15% to 60% of the total mass of the three-dimensional network structure composite material; The particle diameter Dv50 of the composite material having a three-dimensional network structure is 1 μm to 100 μm. A composite material having a three-dimensional mesh structure according to claim 1.

[0095] (Appendix 3) The carbon shell is coated on the outermost layer of the three-dimensional mesh structure composite material, and the mass of the carbon shell accounts for 1% to 20% of the total mass of the three-dimensional mesh structure composite material. A composite material having a three-dimensional mesh structure according to claim 1.

[0096] (Appendix 4) A method for preparing a composite material having a three-dimensional network structure according to any one of Supplementary Notes 1 to 3, the method comprising: placing the porous carbon microspheres having a network structure of through-holes in a deposition device under a protective atmosphere, and evaporating Au or Ag to deposit it on the pore walls of the through-holes of the porous carbon microspheres to form a metal film of Au or Ag as a catalyst; A silicon source gas is introduced into a deposition apparatus for vapor deposition, the silicon source gas is deposited on the surface of the metal film, and the temperature is increased by heating, and silicon nanowires are formed by the catalytic action of metal Au or Ag, thereby obtaining a precursor material containing silicon nanowires with a three-dimensional network structure; A precursor material including silicon nanowires having a three-dimensional network structure is coated with carbon to form a carbon shell, thereby obtaining a composite material having a three-dimensional network structure; Including, A method for preparing a composite material having a three-dimensional network structure.

[0097] (Appendix 5) The protective gas is nitrogen gas or argon gas, and the flow rate of the protective gas is 1 L / min to 50 L / min; the silicon source material comprises a silicon-containing gas and / or a silicon-containing liquid; the silicon-containing gas includes monosilane and / or dichlorosilane; the silicon-containing liquid includes one or more of trisilane, trichlorosilane, tetrachlorosilane, trimethoxysilane, tetramethoxysilane, triethoxysilane, and tetraethoxysilane; When the silicon source material is the silicon-containing gas, the silicon-containing gas is directly introduced into the deposition apparatus or carried to the deposition apparatus by a carrier gas, and the flow rate of the silicon-containing gas is 0.5 L / min to 50 L / min, and the carrier gas is nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min; When the silicon source material is the silicon-containing liquid, the silicon-containing liquid is transported to the deposition apparatus by bubbling with a carrier gas, the carrier gas being nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min; A method for preparing a composite material having a three-dimensional network structure according to Appendix 4,

[0098] (Appendix 6) the deposition apparatus comprises one of a rotary furnace, a tubular furnace, a bell furnace, or a fluidized bed; The temperature at which the silicon source gas is introduced into the deposition apparatus and vapor-phase grown is 600°C to 1200°C, and the time is 1 hour to 20 hours. the carbon coating method includes any one of vapor phase coating, liquid phase coating, and solid phase coating, and the mass of the carbon shell formed by the carbon coating accounts for 1% to 20% of the total mass of the three-dimensional network structure composite material; The method of introducing the silicon source gas into the deposition apparatus to perform vapor deposition includes a thermal plasma method. A method for preparing a composite material having a three-dimensional network structure according to Appendix 4,

[0099] (Appendix 7) A method for preparing a composite material having a three-dimensional network structure according to any one of Supplementary Notes 1 to 3, comprising: The preparation method comprises: placing the porous carbon microspheres having through-holes with a network structure in a deposition apparatus under a protective atmosphere, introducing a silicon source gas into the deposition apparatus for vapor deposition, and depositing the silicon source gas in the through-holes of the porous carbon microspheres to obtain a precursor material; the precursor material is placed in an electrolytic cell and electrolyzed, using the precursor material as a cathode, graphite as an anode, and a molten salt system as an electrolyte, and the voltage and temperature of the electrolytic cell are controlled while applying current in an argon atmosphere to decompose the silicon dioxide deposited in the through-holes of the porous carbon microspheres to form silicon nanowires, thereby obtaining an electrolytic material containing silicon nanowires with a three-dimensional network structure; cooling, washing, vacuum drying, and carbon coating the electrolytic material, and then sieving the electrolytic material to obtain a composite material having a three-dimensional network structure; Including, A method for preparing a composite material having a three-dimensional network structure.

[0100] (Appendix 8) The protective gas is nitrogen gas or argon gas, and the flow rate of the protective gas is 1 L / min to 50 L / min; the silicon source material comprises a silicon-containing gas and / or a silicon-containing liquid; the silicon-containing gas includes monosilane and / or dichlorosilane; the silicon-containing liquid includes one or more of trisilane, trichlorosilane, tetrachlorosilane, trimethoxysilane, tetramethoxysilane, triethoxysilane, and tetraethoxysilane; When the silicon source material is the silicon-containing gas, the silicon-containing gas is directly introduced into the deposition apparatus or carried to the deposition apparatus by a carrier gas, and the flow rate of the silicon-containing gas is 0.5 L / min to 50 L / min, and the carrier gas is nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min; When the silicon source material is the silicon-containing liquid, the silicon-containing liquid is transported to the deposition device by bubbling with a carrier gas, where the carrier gas is nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min; 8. A method for preparing a composite material having a three-dimensional network structure according to claim 7.

[0101] (Appendix 9) the deposition apparatus comprises one of a rotary furnace, a tubular furnace, a bell furnace, or a fluidized bed; The temperature at which the silicon source gas is introduced into the deposition apparatus and vapor-phase grown is 600°C to 1200°C, and the time is 1 hour to 20 hours. the carbon coating method includes any one of vapor phase coating, liquid phase coating, and solid phase coating, and the mass of the carbon shell formed by the carbon coating accounts for 1% to 20% of the total mass of the three-dimensional network structure composite material; The method of introducing the silicon source gas into the deposition apparatus to perform vapor deposition includes a thermal plasma method. 8. A method for preparing a composite material having a three-dimensional network structure according to claim 7.

[0102] (Appendix 10) The composite material includes a three-dimensional network structure according to any one of Supplementary Notes 1 to 3. A lithium battery characterized by:

Claims

1. A three-dimensional network structure composite material for a lithium battery, comprising: The composite material with a three-dimensional network structure includes porous carbon microspheres having through-holes with a network structure, silicon nanowires distributed in the through-holes of the porous carbon microspheres, and a carbon shell; Here, the silicon nanowires are formed by catalyzing a silicon-containing gas with Au or Ag and depositing it in the through-holes. Specifically, Au or Ag is first evaporated and deposited on the pore walls of the through-holes of the porous carbon microspheres to form a metal film of Au or Ag. Thereafter, a silicon-containing gas is introduced and catalyzed by Au or Ag to precipitate silicon atoms, which are then deposited in the through-holes to form silicon nanowires. Alternatively, the silicon nanowires are formed after depositing silane gas in the through-holes to form silicon oxide nanoparticles, and then electrolyzing the silicon oxide nanoparticles in the through-holes in a molten salt system; the silicon nanowires form a three-dimensional network structure within the through-holes of the porous carbon microspheres; The average pore size of the through-holes of the porous carbon microspheres is 15 nm to 50 nm. A three-dimensional network structure composite material for lithium batteries, characterized by:

2. the mass of the porous carbon microspheres accounts for 30% to 70% of the total mass of the three-dimensional network structure composite material; the mass of the silicon nanowires accounts for 15% to 60% of the total mass of the three-dimensional network structure composite material; The particle diameter Dv50 of the three-dimensional network structure composite material is 1 μm to 100 μm.

2. The composite material having a three-dimensional network structure according to claim 1.

3. the carbon shell is coated on the outermost layer of the composite material having a three-dimensional mesh structure, and the mass of the carbon shell accounts for 1% to 20% of the total mass of the composite material having a three-dimensional mesh structure.

2. The composite material having a three-dimensional network structure according to claim 1.

4. A method for preparing a composite material having a three-dimensional network structure according to any one of claims 1 to 3, comprising the steps of: placing the porous carbon microspheres having through-holes with a network structure in a deposition device under a protective atmosphere, and evaporating Au or Ag to deposit it on the pore walls of the through-holes of the porous carbon microspheres to form a metal film of Au or Ag as a catalyst; A silicon source gas is introduced into a deposition apparatus for vapor deposition, the silicon source gas is deposited on the surface of the metal film, and the temperature is increased by heating, and silicon nanowires are formed by the catalytic action of metal Au or Ag, thereby obtaining a precursor material containing silicon nanowires with a three-dimensional network structure; A precursor material including silicon nanowires having a three-dimensional network structure is coated with carbon to form a carbon shell, thereby obtaining a composite material having a three-dimensional network structure; Including, A method for preparing a composite material having a three-dimensional network structure.

5. The protective gas is nitrogen gas or argon gas, and the flow rate of the protective gas is 1 L / min to 50 L / min; the silicon source material comprises a silicon-containing gas and / or a silicon-containing liquid; the silicon-containing gas includes monosilane and / or dichlorosilane; the silicon-containing liquid includes one or more of trisilane, trichlorosilane, tetrachlorosilane, trimethoxysilane, tetramethoxysilane, triethoxysilane, and tetraethoxysilane; When the silicon source material is the silicon-containing gas, the silicon-containing gas is directly introduced into the deposition apparatus or carried to the deposition apparatus by a carrier gas, and the flow rate of the silicon-containing gas is 0.5 L / min to 50 L / min, and the carrier gas is nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min; When the silicon source material is the silicon-containing liquid, the silicon-containing liquid is transported to the deposition apparatus by bubbling with a carrier gas, the carrier gas being nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min; 5. A method for preparing a composite material having a three-dimensional network structure according to claim 4.

6. the deposition apparatus comprises one of a rotary furnace, a tubular furnace, a bell furnace, or a fluidized bed; The temperature at which the silicon source gas is introduced into the deposition apparatus and vapor-phase grown is 600°C to 1200°C, and the time is 1 hour to 20 hours; the carbon coating method includes any one of vapor phase coating, liquid phase coating, and solid phase coating, and the mass of the carbon shell formed by the carbon coating accounts for 1% to 20% of the total mass of the composite material having the three-dimensional mesh structure; The method of introducing the silicon source gas into the deposition apparatus to perform vapor deposition includes a thermal plasma method.

5. A method for preparing a composite material having a three-dimensional network structure according to claim 4.

7. A method for preparing a composite material having a three-dimensional network structure according to any one of claims 1 to 3, comprising the steps of: The preparation method comprises: placing the porous carbon microspheres having through-holes with a network structure in a deposition apparatus under a protective atmosphere, introducing a silicon source gas into the deposition apparatus for vapor deposition, and depositing the silicon source gas in the through-holes of the porous carbon microspheres to obtain a precursor material; the precursor material is placed in an electrolytic cell and electrolyzed, using the precursor material as a cathode, graphite as an anode, and a molten salt system as an electrolyte, and the voltage and temperature of the electrolytic cell are controlled while applying current in an argon atmosphere to decompose the silicon dioxide deposited in the through-holes of the porous carbon microspheres to form silicon nanowires, thereby obtaining an electrolytic material containing silicon nanowires with a three-dimensional network structure; cooling, washing, vacuum drying, and carbon coating the electrolytic material, and then sieving the electrolytic material to obtain a composite material having a three-dimensional network structure; Including, A method for preparing a composite material having a three-dimensional network structure.

8. The protective gas is nitrogen gas or argon gas, and the flow rate of the protective gas is 1 L / min to 50 L / min; the silicon source material comprises a silicon-containing gas and / or a silicon-containing liquid; the silicon-containing gas includes monosilane and / or dichlorosilane; the silicon-containing liquid includes one or more of trisilane, trichlorosilane, tetrachlorosilane, trimethoxysilane, tetramethoxysilane, triethoxysilane, and tetraethoxysilane; When the silicon source material is the silicon-containing gas, the silicon-containing gas is directly introduced into the deposition apparatus or carried to the deposition apparatus by a carrier gas, and the flow rate of the silicon-containing gas is 0.5 L / min to 50 L / min, and the carrier gas is nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min; When the silicon source material is the silicon-containing liquid, the silicon-containing liquid is transported to a deposition apparatus by bubbling with a carrier gas, where the carrier gas is nitrogen gas or argon gas, and the flow rate is 0.5 L / min to 50 L / min; 8. A method for preparing a three-dimensional network structure composite material according to claim 7.

9. the deposition apparatus comprises one of a rotary furnace, a tubular furnace, a bell furnace, or a fluidized bed; The temperature at which the silicon source gas is introduced into the deposition apparatus and vapor-phase grown is 600°C to 1200°C, and the time is 1 hour to 20 hours; the carbon coating method includes any one of vapor phase coating, liquid phase coating, and solid phase coating, and the mass of the carbon shell formed by the carbon coating accounts for 1% to 20% of the total mass of the composite material having the three-dimensional mesh structure; The method of introducing the silicon source gas into the deposition apparatus to perform vapor deposition includes a thermal plasma method.

8. A method for preparing a three-dimensional network structure composite material according to claim 7.

10. A composite material having a three-dimensional network structure according to any one of claims 1 to 3, A lithium battery characterized by:

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