Multilayer composite material prepared at ultra-high temperature, its preparation method and application

Abstract

Provided are a multilayer composite material prepared at ultra-high temperature, a preparation method thereof, and an application thereof. 【Solution means】The multilayer composite material includes a carbon matrix and a nanosilicon-based composite material. The nanosilicon-based composite material is prepared by a thermal plasma method. Specifically, one or more substances containing micron-sized silicon powder and doping elements collide and are ionized in a high-frequency plasma processing device to form a plasma gas with a temperature of 5000 K or higher, and then cooled, deposited, and nucleated to obtain a nanoscale silicon-based composite material in which the doping elements are uniformly embedded at the atomic scale. The doping elements include at least one of C, N, B, P, S, Mg, Ca, Al, Zn, Mn, Ni, or Ti. The carbon matrix is a porous carbon material, and the nanosilicon-based composite material is deposited in the porous structure of the carbon matrix.

Description

Technical Field

[0001] (Cross-reference) This application claims the priority of a Chinese patent application with an application number of 202210750606.1, titled "Multilayer Composite Material Prepared at Ultra-High Temperature and Its Preparation Method and Application", which was filed with the China National Intellectual Property Administration on June 29, 2022.

[0002] (Technical Field) The present invention relates to the technical field of batteries, and particularly to a multilayer composite material prepared at ultra-high temperature and its preparation method and application.

Background Art

[0003] With the development of modern society, the demand for batteries with high energy density is increasing day by day, and it is becoming increasingly difficult for graphite anodes to meet the demands of various devices. Silicon is considered to be one of the most promising materials to replace graphite anodes, and its maximum theoretical capacity is 4200 mAh / g. However, silicon undergoes a large volume change during charge and discharge processes, easily causing pulverization of the electrode material. At the same time, the intrinsic conductivity of silicon is low, which has a great impact on battery performance.

[0004] Combining silicon materials and carbon materials can effectively solve the above problems, but uniformly compounding silicon and carbon materials remains a major challenge. The commonly used method in the market is compounding by physical and mechanical methods, which is difficult to uniformly disperse silicon and carbon materials. Silicon has been dispersed in carbon materials and synthesized by chemical vapor deposition (CVD), but the silicon-carbon materials prepared by the CVD method cannot control the forms of Si and C, and there are concerns about safety in the use of silane in this method, which is relatively dangerous.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The object of the present invention is to provide a multilayer composite material prepared at ultra-high temperature, a preparation method thereof, and an application. The multilayer composite material prepared at ultra-high temperature according to the present invention has a stable structure. Compared with conventional silicon-based materials, due to the interaction between the multilayer structure and the composite material, this material has the characteristics of small volume expansion, better cycle characteristics and rate characteristics.

Means for Solving the Problems

[0006] In a first aspect, an embodiment of the present invention provides a multilayer composite material including a carbon matrix and a nano-silicon-based composite material, The nano-silicon-based composite material is prepared by a thermal plasma method. Specifically, one or more substances containing micron-sized silicon powder and doping elements are collided and ionized in a high-frequency plasma processing apparatus to form a plasma gas with a temperature of 5000K or higher, and then cooled, deposited, and nucleated to obtain a nano-scale silicon-based composite material in which the doping elements are uniformly embedded at the atomic scale. The doping elements include at least one of C, N, B, P, S, Mg, Ca, Al, Zn, Mn, Ni, or Ti. The carbon matrix is a porous carbon material, and the nano-silicon-based composite material is deposited in the porous structure of the carbon matrix.

[0007] Preferably, the particle size of the nano-silicon-based composite material is 0.1 nm to 200 nm, the mass of the nano-silicon-based composite material accounts for 10% to 90% of the mass of the multilayer composite material, the mass of the doping elements accounts for 0.1% to 50% of the mass of the nano-silicon-based composite material, and the mass of the carbon matrix accounts for 10% to 70% of the mass of the multilayer composite material.

[0008] More preferably, the multilayer composite material further includes a carbon shell, the carbon shell covers the outer layer of the carbon matrix on which the nano-silicon-based composite material is deposited, and the mass of the carbon shell accounts for 0 to 10% of the mass of the multilayer composite material.

[0009] Preferably, when the multilayer composite material contains C element, in the NMR spectrum of solid nuclear magnetic resonance of the multilayer composite material, when the peak of silicon is at -65 ppm to -140 ppm, it is shown that there is a resonance peak of Si-C between 10 ppm and -30 ppm, and the area ratio of the resonance peak of Si-C to the peak of silicon is 0.05 to 6.0.

[0010] In a second aspect, an embodiment of the present invention provides a method for preparing a multilayer composite material prepared at an ultra-high temperature as described in the first aspect above. The preparation method is a thermal plasma method. Place the porous carbon material in the condensation region of the high-frequency plasma processing apparatus, and place micron-sized silicon powder and one or more substances containing a doping element in the high-temperature region of the high-frequency plasma processing apparatus at a mass ratio of 1:0.1 to 1:1 (the doping element includes at least one of C, N, B, P, S, Mg, Ca, Al, Zn, Mn, Ni, or Ti). Introduce a protective gas into the high-frequency plasma processing apparatus to replace the air. Turn on the plasma generator of the high-frequency plasma processing apparatus to ionize the working gas, vaporize and dissociate the micron-sized silicon powder and the substance containing the doping element to form a plasma gas with a temperature of 5000 K or higher. Furthermore, carry it to the condensation region by a carrier gas, deposit silicon element and the doping element in the pores of the porous carbon material, nucleate and grow to the nanometer size to obtain the multilayer composite material prepared at the ultra-high temperature. including.

[0011] The method further includes performing carbon coating by at least one of gas-phase coating, liquid-phase coating, and solid-phase coating.

[0012] Preferably, the micron-sized silicon powder is an industrial micron-sized silicon powder containing one or more of the silicon powder by-produced during diamond wire cutting, the waste generated during the production of organosilicon, and industrial silicon powder, and the particle size D50 of the industrial micron-sized silicon powder is 5 μm to 100 μm.

[0013] Preferably, The substance containing the doping element C includes one or more of carbon black, acetylene, methane, propylene, ethylene, propane, and gaseous ethanol, The substance containing the doping element N includes one or more of nitrogen, ammonia, urea, melamine, and hydrazine, The substance containing the doping element B includes one or more of boron, diborane, trimethyl borate, tripropyl borate, and boron tribromide, The substance containing the doping element P includes one or two of white phosphorus, red phosphorus, black phosphorus, phosphine, and phosphorus oxychloride, The substance containing the doping element S includes one or more of sulfur, thiourea, thiol, thiophenol, and thioether, The substance containing the doping element Mg includes one or more of magnesium, magnesium oxide, and magnesium chloride, The substance containing the doping element Ca includes one or more of calcium oxide, calcium hydroxide, and calcium chloride, The substance containing the doping element Al includes one or more of aluminum, alumina, and aluminum chloride, The substance containing the doping element Zn includes one or more of zinc, zinc oxide, zinc hydroxide, and zinc chloride, The substance containing the doping element Mn includes one or more of manganese oxide, manganese hydroxide, and manganese chloride, The substance containing the doping element Ni includes one or more of nickel, nickel oxide, nickel hydroxide, and nickel chloride, The substance containing the doping element Ti includes one or more of titanium simple substance, titanium oxide, titanium hydroxide, and titanium chloride.

[0014] In a third aspect, an embodiment of the present invention provides an application of the multi-layer composite material prepared at ultra-high temperature described in the first aspect above, and the multi-layer composite material is used as a negative electrode material of a lithium-ion battery.

[0015] In a fourth aspect, an embodiment of the present invention provides a lithium-ion battery including the multi-layer composite material prepared at ultra-high temperature described in the first aspect above.

Advantages of the Invention

[0016] The multi-layer composite material prepared at ultra-high temperature according to the embodiment of the present invention, its preparation method and application realize in-situ nucleation and growth of silicon materials and doping elements in porous carbon by high-temperature plasma, and the doping elements are uniformly embedded at the atomic scale, thereby making the structure of the material more stable in the lithium insertion / desorption process, reducing the volume expansion, and having better cycle characteristics when used as the negative electrode of a lithium battery. The multi-layer composite material of the present invention has the characteristics of small volume expansion, better cycle characteristics and rate characteristics due to the three-layer structure of the carbon matrix, nano-silicon-based composite material and carbon shell and the interaction between the composite materials. More importantly, this material is prepared by the thermal plasma method, and the CVD method commonly used in the preparation process is safer.

Brief Description of the Drawings

[0017] Hereinafter, the technical solutions in the embodiments of the present invention will be described in more detail with reference to the drawings and embodiments.

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0019] Hereinafter, the present invention will be further described with reference to the drawings and specific examples. However, it should be understood that these examples are only for explaining the present invention in more detail and are not intended to limit the present invention in any way, that is, they are not intended to limit the protection scope of the present invention.

[0020] Examples of the present invention propose a multilayer composite material prepared at ultra-high temperature, including a carbon matrix and a nanosilicon-based composite material. The nanosilicon-based composite material is prepared by a thermal plasma method. Specifically, one or more substances containing micron-sized silicon powder and any one of doping elements C, N, B, P, S, Mg, Ca, Al, Zn, Mn, Ni, or Ti are collided and ionized in a high-frequency plasma processing apparatus to form a plasma gas with a temperature of 5000K or higher, and then cooled, deposited, and nucleated to obtain a nanoscale silicon-based composite material in which the doping element is uniformly embedded at the atomic scale. The carbon matrix is a porous carbon material, preferably a porous non-graphitizable carbon material, and the nanosilicon-based composite material is deposited in the porous structure of the carbon matrix.

[0021] The particle size of the above-mentioned nanosilicon-based composite material is 0.1 nm to 200 nm. The mass of the nanosilicon-based composite material accounts for 10% to 90% of the mass of the multilayer composite material. The mass of the doping element accounts for 0.1% to 50% of the mass of the nanosilicon-based composite material. The mass of the carbon matrix accounts for 10% to 70% of the mass of the multilayer composite material.

[0022] The multilayer composite material further includes a carbon shell, the carbon shell is coated on the outer layer of the carbon matrix on which the nanosilicon-based composite material is deposited, and the mass of the carbon shell accounts for 0 to 10% of the mass of the multilayer composite material.

[0023] When the multilayer composite material contains C element, in the NMR spectrum of the solid nuclear magnetic resonance of the multilayer composite material, when the peak of silicon is at -65 ppm to -140 ppm, it is shown that there is a resonance peak of Si-C between 10 ppm and -30 ppm, and the area ratio of the resonance peak of Si-C to the peak of silicon is 0.05 to 6.0.

[0024] The above-mentioned multilayer composite material of the present invention can be prepared by the thermal plasma method. The specific steps are shown in Figure 1, and the preparation method includes the following steps.

[0025] In step 110, the porous carbon material is placed in the condensation region of the high-frequency plasma processing device, and the micron-sized silicon powder and one or more substances containing doping elements are placed in the high-temperature region of the high-frequency plasma processing device at a mass ratio of 1:0.1 to 1:1. The doping element includes at least one of C, N, B, P, S, Mg, Ca, Al, Zn, Mn, Ni or Ti.

[0026] In step 120, a protective gas is introduced into the high-frequency plasma processing device to replace the existing air in the chamber of the device. The protective gas is nitrogen gas or argon gas, and the flow rate of the protective gas is 0.5 m 3 / h to 3 m 3 / h.

[0027] In step 130, the plasma generator of the high-frequency plasma processing device is turned on to ionize the working gas, vaporize and dissociate the substance containing micron-sized silicon powder and doping elements to form a plasma gas with a temperature of 5000 K or higher. The working gas is nitrogen gas or argon gas, and the flow rate of the working gas is 3 m3 / hour ~ 8 m 3 / hour. By ionizing the working gas, a substance containing micron-sized silicon powder and doping elements is collided, and they are vaporized and dissociated under the action of high-temperature plasma.

[0028] In step 140, it is carried to the condensation region by the carrier gas, and the silicon element and the doping element are deposited in the pores of the porous carbon material, nucleated and grown to the nanometer size to obtain a multi-layer composite material prepared at ultra-high temperature.

[0029] The carrier gas is nitrogen gas or argon gas, and the flow rate of the carrier gas is 0.1 m 3 / hour ~ 1 m 3 / hour. The by-products after the substance containing the doping element is vaporized and dissociated are finally discharged together with the tail gas along with the carrier gas.

[0030] As one of the options, carbon coating can also be applied to the obtained material by at least one of gas-phase coating, liquid-phase coating, and solid-phase coating.

[0031] In the above preparation method, the operating frequency of the high-frequency plasma processing device is 1 MHz ~ 300 MHz. The operating voltage is 100 V ~ 150 V, and the current is 80 A ~ 180 A. The following specific examples of the present invention are realized by using a DLZ-MA-300-B plasma generator as the high-frequency plasma processing device. It is possible that the selection of various gases, especially the setting of the flow rate, may be different by the device, and anyone skilled in the art will know this.

[0032] The temperature of the plasma refers to the ion temperature and the electron temperature of the thermal equilibrium plasma (also called thermal plasma). In a specific embodiment, the temperature of the plasma may be 5000 K ~ 20000 K, or even higher.

[0033] The micron-sized silicon powder is an industrial silicon powder with a micron size, and the particle size D50 is 5 μm to 100 μm. It contains one or more of the silicon powder by-produced during diamond wire cutting, the waste generated during the production of organosilicon, and industrial silicon powder. By using the silicon powder by-produced during cutting or the waste silicon powder generated during production, the effects of further savings and cost reduction can be achieved. Moreover, since the micron-sized silicon powder needs to be vaporized and ionized in the preparation process, using the silicon powder by-produced during cutting or the waste silicon powder generated during production will not affect the product quality.

[0034] The substances of the doping elements used in step 110 can be specifically selected as follows. The substances containing the doping element C include one or more of carbon black, acetylene, methane, propylene, ethylene, propane, and gaseous ethanol. The substances containing the doping element N include one or more of nitrogen, ammonia, urea, melamine, and hydrazine. The substances containing the doping element B include one or more of boron, diborane, trimethyl borate, tripropyl borate, and boron tribromide. The substances containing the doping element P include one or two of white phosphorus, red phosphorus, black phosphorus, phosphine, and phosphorus oxychloride. The substances containing the doping element S include one or more of sulfur, thiourea, thiol, thiophenol, and thioether. The substances containing the doping element Mg include one or more of magnesium, magnesium oxide, and magnesium chloride. The substances containing the doping element Ca include one or more of calcium oxide, calcium hydroxide, and calcium chloride. The substances containing the doping element Al include one or more of aluminum, alumina, and aluminum chloride. The substances containing the doping element Zn include one or more of zinc, zinc oxide, zinc hydroxide, and zinc chloride. The substance containing the doping element Mn includes one or more of manganese oxide, manganese hydroxide, and manganese chloride, The substance containing the doping element Ni includes one or more of nickel metal, nickel oxide, nickel hydroxide, and nickel chloride, The substance containing the doping element Ti includes one or more of titanium metal, titanium oxide, titanium hydroxide, and titanium chloride.

[0035] The schematic configuration diagram of the multi-layer composite material prepared at ultra-high temperature by the above method of the present invention is shown in Fig. 2. As can be seen from the figure, the method of the present invention can perform in-situ nucleation and growth within the porous carbon by treating the silicon material and the doping element with high-temperature plasma, enabling the doping element to be uniformly embedded at the atomic scale, making the structure of the material more stable in the lithium insertion / desorption process, reducing the volume expansion, and having better cycle characteristics when used as the negative electrode of a lithium battery. The multi-layer composite material of the present invention has the characteristics of small volume expansion, better cycle characteristics and rate characteristics due to the interaction between the three-layer structure of the carbon matrix, the nano-silicon-based composite material and the carbon shell and the composite material. More importantly, this material is prepared by the thermal plasma method, and the CVD method commonly used in the preparation process is safer.

[0036] The multi-layer composite material prepared at ultra-high temperature in the examples of the present invention can be used as the negative electrode material of a lithium-ion battery, especially as the negative electrode active material, and the negative electrode material can be applied to a lithium-ion battery.

[0037] To better understand the technical solution of the present invention, the preparation process and characteristics of the multi-layer composite material prepared at ultra-high temperature of the present invention will be described below with a plurality of specific examples respectively.

[0038] (Example 1) In this example, a porous graphitizable carbon material is placed in the condensation region of a high-frequency plasma processing apparatus, and by-products generated during diamond wire cutting and carbon black are placed in the high-temperature region of the high-frequency plasma processing apparatus, with a ratio of 1:0.1. A protective gas is introduced into the high-frequency plasma processing apparatus to replace the air, the plasma generator of the high-frequency plasma processing apparatus is turned on to ionize the working gas, vaporize silicon powder, vaporize and dissociate acetylene at a high temperature, and transport the plasma gas substance containing gaseous silicon and C element to the condensation region by a carrier gas. Deposit silicon and C element doped with silicon into the pores of the porous graphitizable carbon material, nucleate and grow to the nanometer size. Finally, perform carbon coating on the deposited product by vapor phase coating to obtain a multilayer composite material prepared at ultra-high temperature, and provide a method for preparing a multilayer composite material prepared at ultra-high temperature.

[0039] The nuclear magnetic resonance (NMR) spectrum of the solid nuclear magnetic resonance of the multilayer composite material prepared at ultra-high temperature prepared in this example is shown in Figure 3. In the NMR spectrum of the solid nuclear magnetic resonance of the multilayer composite material, when the peak of silicon is at -65 ppm to -140 ppm, it is shown that there is a resonance peak of Si-C between 10 ppm and -30 ppm, and the area ratio of the resonance peak of Si-C to the peak of silicon is 0.05 to 6.0.

[0040] The XRD pattern of the multilayer composite material prepared at ultra-high temperature prepared in this example is shown in Figure 4.

[0041] Weigh the multilayer composite material obtained as the negative electrode material, carbon black as the conductive additive, and the adhesive (1:1 sodium cellulose and styrene-butadiene rubber) in a ratio of 95:2:3. Prepare a slurry in a beater at room temperature. Uniformly apply the prepared slurry on a copper foil. After drying in a blower dryer at a temperature of 50 °C for 2 hours, cut it into 8×8 mm electrode pieces, and vacuum dry it in a vacuum dryer at a temperature of 100 °C for 10 hours. Immediately transfer the dried electrode pieces into a glove box for battery assembly preparation.

[0042] The assembly of the simulated battery was carried out in a glove box containing a high-purity Ar atmosphere. Lithium metal was used as the counter electrode, and a solution of ethylene carbonate (EC) / dimethyl carbonate (DMC) (v:v = 1:1) containing 1 mol / L of LiPF6 was used as the electrolyte and assembled into the battery. A constant current charge-discharge mode test was carried out using a charger, the discharge cut-off voltage was 0.005 V, the charge cut-off voltage was 1.5 V, and the charge-discharge test was carried out at a C / 10 current density. The charge-discharge curve diagram of the composite lithium storage material for lithium-ion batteries prepared in this example is shown in Figure 5. The discharge capacity of the first cycle was 1494 mAh / g, and the Coulomb efficiency of the first cycle was 90.65%.

[0043] For better comparison, comparative samples were prepared in the following manner.

[0044] (Comparative Example 1) This comparative example provides a preparation method for a general silicon-carbon composite material and includes the following steps. In Step 1, 200 g of nanosilicon particles and 500 g of phenol resin powder were put into a hydrothermal reactor for hydrothermal reaction. The pressure was 5 Mpa, the heating temperature was 300 °C, and it was kept warm for 8 hours. The material was taken out, the filtrate was washed and filtered until it became colorless and transparent, and then dried to obtain a spherical silicon-containing carbon precursor. In Step 2, after mixing the sample obtained in Step 1, it was put into a reaction device, heated to 900 °C at a rate of 3 °C / min, and carbonized by keeping it warm for 6 hours under a nitrogen gas atmosphere to obtain a general silicon-carbon composite material.

[0045] The obtained material was used to assemble and test the battery. The specific process was the same as that in Example 1. The test data are shown in Table 1.

[0046] (Example 2) In this example, a porous graphitizable carbon material is placed in the condensation region of a high-frequency plasma processing apparatus, and waste generated during the production of organic silicon and methane and ammonia, which are substances containing C and N elements, are placed in the high-temperature region of the high-frequency plasma processing apparatus. The ratio is 1:0.1:0.1. A protective gas is introduced into the high-frequency plasma processing apparatus to replace the air. The plasma generator of the high-frequency plasma processing apparatus is turned on to ionize the working gas, vaporize the silicon powder, vaporize and dissociate methane and ammonia at high temperature, and transport the gaseous silicon and the plasma gas substance containing C and N to the condensation region by a carrier gas. Silicon and C and N doped in silicon are deposited in the pores of the porous graphitizable carbon material, nucleated and grown to the nanometer size, and the deposited product is carbon-coated by liquid-phase coating to obtain a multi-layer composite material prepared at ultra-high temperature. A method for preparing a multi-layer composite material prepared at ultra-high temperature is provided.

[0047] The obtained material was used to assemble and test a battery, and the specific process was the same as that in Example 1. The test data are shown in Table 1.

[0048] (Example 3) In this example, a porous graphitizable carbon material is placed in the condensation region of a high-frequency plasma processing apparatus, and industrial silicon powder and propylene, urea, diborane, and phosphine, which are substances containing C, N, B, and P elements, are placed in the high-temperature region of the high-frequency plasma processing apparatus. The ratio is 1:0.075:0.075:0.075:0.075. A protective gas is introduced into the high-frequency plasma processing apparatus to replace the air. The plasma generator of the high-frequency plasma processing apparatus is turned on to ionize the working gas, vaporize the silicon powder, vaporize and dissociate propylene, urea, diborane, and phosphine at high temperature, and transport the gaseous silicon and the plasma gas substance containing C, N, B, and P to the condensation region by a carrier gas. Silicon and C, N, B, and P elements doped in silicon are deposited in the pores of the porous graphitizable carbon material, nucleated and grown to the nanometer size, and the deposited product is carbon-coated by solid-phase coating to obtain a multi-layer composite material prepared at ultra-high temperature. A method for preparing a multi-layer composite material prepared at ultra-high temperature is provided.

[0049] The obtained material was used to assemble and test a battery, and the specific process was the same as that in Example 1. The test data are shown in Table 1.

[0050] (Example 4) In this example, a porous graphitizable carbon material was placed in the condensation region of a high-frequency plasma processing apparatus, and ethylene, thiourea, magnesium oxide, and calcium oxide, which are substances containing C, S, Mg, and Ca and are by-products during diamond wire cutting, were placed in the high-temperature region of the high-frequency plasma processing apparatus. The ratio was 1:0.1:0.1:0.1:0.1. A protective gas was introduced into the high-frequency plasma processing apparatus to replace the air, the plasma generator of the high-frequency plasma processing apparatus was turned on to ionize the working gas, silicon powder was vaporized, ethylene, thiourea, magnesium oxide, and calcium oxide were vaporized and dissociated at high temperature, and the gaseous silicon and the plasma gas substance containing C, S, Mg, and Ca were transported to the condensation region by a carrier gas. Silicon and C, S, Mg, and Ca doped in silicon were deposited in the pores of the porous graphitizable carbon material, nucleated and grown to a nanometer size, and the product after deposition was carbon-coated by vapor phase coating, providing a method for preparing a multi-layer composite material prepared at ultra-high temperature to obtain a multi-layer composite material prepared at ultra-high temperature.

[0051] The obtained material was used to assemble and test a battery, and the specific process was the same as that in Example 1. The test data are shown in Table 1.

[0052] (Example 5) In this example, a porous graphitizable carbon material is placed in the condensation region of a high-frequency plasma processing apparatus, and propane, alumina, zinc oxide, and manganese oxide, which are waste generated during the production of organic silicon and substances containing C, Al, Zn, and Mn, are placed in the high-temperature region of the high-frequency plasma processing apparatus. The ratio is 1:0.125:0.125:0.125:0.125. A protective gas is introduced into the high-frequency plasma processing apparatus to replace the air. The plasma generator of the high-frequency plasma processing apparatus is turned on to ionize the working gas, vaporize the silicon powder, vaporize and dissociate propane, alumina, zinc oxide, and manganese oxide at high temperature, and transport the gaseous silicon and the plasma gas substance containing C, Al, Zn, and Mn to the condensation region by a carrier gas. Deposit silicon and C, Al, Zn, and Mn doped in silicon into the pores of the porous graphitizable carbon material, nucleate and grow to the nanometer size, and apply a carbon coating to the product after deposition by liquid-phase coating to obtain a multilayer composite material prepared at ultra-high temperature. A method for preparing a multilayer composite material prepared at ultra-high temperature is provided.

[0053] The obtained material was used to assemble and test a battery, and the specific process was the same as that in Example 1. The test data are shown in Table 1.

[0054] (Example 6) In this example, a porous graphitizable carbon material is placed in the condensation region of a high-frequency plasma processing apparatus, and industrial silicon powder and zinc hydroxide, manganese hydroxide, nickel hydroxide, and titanium oxide, which are substances containing Zn, Mn, Ni, and Ti, are placed in the high-temperature region of the high-frequency plasma processing apparatus. The ratio is 1:0.15:0.15:0.15:0.15. A protective gas is introduced into the high-frequency plasma processing apparatus to replace the air, the plasma generator of the high-frequency plasma processing apparatus is turned on to ionize the working gas, the silicon powder is vaporized, zinc hydroxide, manganese hydroxide, nickel hydroxide, and titanium oxide are vaporized and dissociated at high temperature, and a plasma gas substance containing gaseous silicon and Zn, Mn, Ni, and Ti is transported to the condensation region by a carrier gas. Silicon and Zn, Mn, Ni, and Ti doped into the silicon are deposited in the pores of the porous graphitizable carbon material, nucleated and grown to the nanometer size, and the product after deposition is coated with carbon by solid-phase coating to obtain a multilayer composite material prepared at ultra-high temperature. A method for preparing a multilayer composite material prepared at ultra-high temperature is provided.

[0055] The obtained material was used to assemble and test a battery, and the specific process was the same as that of Example 1. The test data are shown in Table 1.

[0056] (Example 7) In this embodiment, a porous graphitizable carbon material is placed in the condensation region of a high-frequency plasma processing apparatus, and ethanol and titanium hydroxide, which are by-products during diamond wire cutting, waste generated during the production of organosilicon, and substances containing C and Ti, are placed in the high-temperature region of the high-frequency plasma processing apparatus. The ratio is 1:0.35:0.35. A protective gas is introduced into the high-frequency plasma processing apparatus to replace the air. The plasma generator of the high-frequency plasma processing apparatus is turned on to ionize the working gas, vaporize the silicon powder, vaporize and dissociate ethanol and titanium hydroxide at high temperature, and transport the gaseous silicon and the plasma gas substance containing C and Ti to the condensation region by means of a carrier gas. Silicon and C and Ti doped in silicon are deposited in the pores of the porous graphitizable carbon material, nucleate and grow to the nanometer size, and a carbon coating is applied to the deposited product by vapor phase coating to obtain a multilayer composite material prepared at ultra-high temperature. A method for preparing a multilayer composite material prepared at ultra-high temperature is provided.

[0057] The obtained material was used to assemble and test a battery, and the specific process was the same as that in Example 1. The test data are shown in Table 1.

[0058] (Example 8) In this embodiment, a porous graphitizable carbon material is placed in the condensation region of a high-frequency plasma processing apparatus, and acetylene and nickel oxide, which are by-products during diamond wire cutting, industrial silicon powder, and substances containing C and Ni, are placed in the high-temperature region of the high-frequency plasma processing apparatus. The ratio is 1:0.4:0.4. A protective gas is introduced into the high-frequency plasma processing apparatus to replace the air. The plasma generator of the high-frequency plasma processing apparatus is turned on to ionize the working gas, vaporize the silicon powder, vaporize and dissociate acetylene and nickel oxide at high temperature, and transport the gaseous silicon and the plasma gas substance containing C and Ni to the condensation region by means of a carrier gas. Silicon and C and Ni doped in silicon are deposited in the pores of the porous graphitizable carbon material, nucleate and grow to the nanometer size, and a carbon coating is applied to the deposited product by liquid phase coating to obtain a multilayer composite material prepared at ultra-high temperature. A method for preparing a multilayer composite material prepared at ultra-high temperature is provided.

[0059] The obtained material was used to assemble and test a battery, and the specific process was the same as that in Example 1. The test data are shown in Table 1.

[0060] (Example 9) In this example, a porous graphitizable carbon material was placed in the condensation region of a high-frequency plasma processing apparatus, and waste generated during the production of organic silicon, industrial silicon powder, and methane and manganese chloride, which are substances containing C and Mn, were placed in the high-temperature region of the high-frequency plasma processing apparatus. The ratio was 1:0.45:0.45. A protective gas was introduced into the high-frequency plasma processing apparatus to replace the air, the plasma generator of the high-frequency plasma processing apparatus was turned on to ionize the working gas, the silicon powder was vaporized, methane and manganese chloride were vaporized and dissociated at high temperature, and the gaseous silicon and the plasma gas substance containing C and Mn were transported to the condensation region by a carrier gas. Silicon and C and Mn doped into the silicon were deposited in the pores of the porous graphitizable carbon material, nucleated and grown to the nanometer size, and the product after deposition was coated with carbon by solid-phase coating to obtain a multilayer composite material prepared at ultra-high temperature. A method for preparing a multilayer composite material prepared at ultra-high temperature was provided.

[0061] The obtained material was used to assemble and test a battery, and the specific process was the same as that in Example 1. The test data are shown in Table 1.

[0062] (Example 10) In this example, a porous graphitizable carbon material is placed in the condensation region of a high-frequency plasma processing apparatus, and by-products generated during diamond wire cutting, waste generated during the production of organosilicon, industrial silicon powder, and propylene and zinc chloride, which are substances containing C and Zn, are placed in the high-temperature region of the high-frequency plasma processing apparatus. The ratio is 1:0.5:0.5. A protective gas is introduced into the high-frequency plasma processing apparatus to replace the air, the plasma generator of the high-frequency plasma processing apparatus is turned on to ionize the working gas, vaporize the silicon powder, vaporize and dissociate propylene and zinc chloride at high temperature, and carry the gaseous silicon and the plasma gas substance containing C and Zn to the condensation region by a carrier gas. Deposit the gaseous compounds of silicon and C and Zn doped in silicon in the pores of the porous graphitizable carbon material, nucleate and grow to the nanometer size, apply a carbon coating to the product after deposition by vapor phase coating, and provide a method for preparing a multilayer composite material prepared at ultra-high temperature to obtain a multilayer composite material prepared at ultra-high temperature.

[0063] The obtained material was used to assemble and test a battery, and the specific process was the same as that in Example 1. The test data are shown in Table 1.

[0064]

Table 1

[0065] The composite materials obtained in the above examples and comparative examples and commercially available graphite were proportionally combined into a composite material of 450 mAh / g and assembled into a button-shaped all-solid-state battery together with lithium cobaltate, and cycled at a 1C rate to evaluate its cycle characteristics. The data are shown in Table 2.

[0066]

Table 2

[0067] From the comparative examples and the examples, it can be seen that the multilayer composite material prepared at ultra-high temperature according to the present invention has a higher specific capacity and Coulomb efficiency in the first cycle. At the same time, when comparing the cycle characteristics of all-solid-state batteries, the multilayer composite material prepared at ultra-high temperature of the present invention has better cycle characteristics. Due to the interaction between the three-layer structure of the carbon matrix, the nanosilicon-based composite material and the carbon shell and the composite material, this material has the characteristics of small volume expansion, better cycle characteristics and rate characteristics. At the same time, from the adjustment of the ratio of the deposited silicon to the doping element, it can be seen that as the ratio of the doping element increases, the charge specific capacity continues to decrease, but the Coulomb efficiency of its first cycle continues to increase. For this material, by doping silicon with one or more of C, N, B, P, S, Mg, Ca, Al, Zn, Mn, Ni, and Ti by the thermal plasma method, the structure of the material can be made more stable in the lithium insertion / desorption process, the volume expansion can be reduced, and when used as the negative electrode of a lithium battery, it has better cycle characteristics.

[0068] In the above specific embodiments, the object, technical solution and beneficial effects of the present invention are further described in detail. 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.

[0069] (Appendix) (Appendix 1) A multilayer composite material prepared at ultra-high temperature, The multilayer composite material includes a carbon matrix and a nanosilicon-based composite material, The nano-silicon composite material is prepared by a thermal plasma method. Specifically, micron-sized silicon powder and one or more substances containing doping elements collide and are ionized in a high-frequency plasma processing apparatus to form a plasma gas with a temperature of 5000 K or higher, and then cooled, deposited, and nucleated to obtain a nano-scale silicon composite material in which the doping elements are uniformly embedded at the atomic scale. The doping elements include at least one of C, N, B, P, S, Mg, Ca, Al, Zn, Mn, Ni, or Ti. The carbon matrix is a porous carbon material, and the nano-silicon composite material is deposited in the porous structure of the carbon matrix. A multilayer composite material characterized by the above.

[0070] (Appendix 2) The particle size of the nano-silicon composite material is 0.1 nm to 200 nm. The mass of the nano-silicon composite material accounts for 10% to 90% of the mass of the multilayer composite material. The mass of the doping elements accounts for 0.1% to 50% of the mass of the nano-silicon composite material. The mass of the carbon matrix accounts for 10% to 70% of the mass of the multilayer composite material. The multilayer composite material according to Appendix 1, characterized by the above.

[0071] (Appendix 3) Further including a carbon shell, the carbon shell is coated on the outer layer of the carbon matrix on which the nano-silicon composite material is deposited. The mass of the carbon shell accounts for 0 to 10% of the mass of the multilayer composite material. The multilayer composite material according to Appendix 2, characterized by the above.

[0072] (Appendix 4) When the multilayer composite material contains C element, in the NMR spectrum of the solid nuclear magnetic resonance of the multilayer composite material, when the peak of silicon is at -65 ppm to -140 ppm, it is shown that there is a resonance peak of Si-C between 10 ppm and -30 ppm, and the area ratio of the resonance peak of Si-C to the peak of silicon is 0.05 to 6.0. The multilayer composite material according to Addendum 1, characterized in that...

[0073] (Addendum 5) A method for preparing a multilayer composite material prepared at an ultra-high temperature according to any one of Addenda 1 to 4 above, wherein the preparation method is a thermal plasma method, placing a porous carbon material in the condensation region of a high-frequency plasma processing apparatus, and placing micron-sized silicon powder and one or more substances containing a doping element in the high-temperature region of the high-frequency plasma processing apparatus at a mass ratio of 1:0.1 to 1:1 (the doping element includes at least one of C, N, B, P, S, Mg, Ca, Al, Zn, Mn, Ni, or Ti), introducing a protective gas into the high-frequency plasma processing apparatus to displace the air, turning on the plasma generator of the high-frequency plasma processing apparatus to ionize the working gas, vaporize and dissociate the micron-sized silicon powder and the substance containing the doping element to form a plasma gas with a temperature of 5000K or higher, further transporting it to the condensation region by a carrier gas, depositing silicon elements and the doping elements in the pores of the porous carbon material, nucleating and growing to a nanometer size to obtain the multilayer composite material prepared at the ultra-high temperature, A preparation method characterized in that...

[0074] (Addendum 6) further comprising performing carbon coating by at least one of gas-phase coating, liquid-phase coating, and solid-phase coating, A preparation method according to Addendum 5, characterized in that...

[0075] (Addendum 7) The micron-sized silicon powder is micron-sized industrial silicon powder including one or more of those by-produced during diamond wire cutting, wastes generated during the production of organosilicon, and industrial silicon powder, and the particle size D50 of the micron-sized industrial silicon powder is 5μm to 100μm, A preparation method according to Addendum 5, characterized in that...

[0076] (Supplementary Note 8) The substance containing the doping element C includes one or more of carbon black, acetylene, methane, propylene, ethylene, propane, and gaseous ethanol, The substance containing the doping element N includes one or more of nitrogen, ammonia, urea, melamine, and hydrazine, The substance containing the doping element B includes one or more of boron monomer, diborane, trimethyl borate, tripropyl borate, and boron tribromide, The substance containing the doping element P includes one or two of white phosphorus, red phosphorus, black phosphorus, phosphine, and phosphorus oxychloride, The substance containing the doping element S includes one or more of sulfur, thiourea, thiol, thiophenol, and thioether, The substance containing the doping element Mg includes one or more of magnesium monomer, magnesium oxide, and magnesium chloride, The substance containing the doping element Ca includes one or more of calcium oxide, calcium hydroxide, and calcium chloride, The substance containing the doping element Al includes one or more of aluminum monomer, alumina, and aluminum chloride, The substance containing the doping element Zn includes one or more of zinc monomer, zinc oxide, zinc hydroxide, and zinc chloride, The substance containing the doping element Mn includes one or more of manganese oxide, manganese hydroxide, and manganese chloride, The substance containing the doping element Ni includes one or more of nickel monomer, nickel oxide, nickel hydroxide, and nickel chloride, The substance containing the doping element Ti includes one or more of titanium monomer, titanium oxide, titanium hydroxide, and titanium chloride. The preparation method according to Supplementary Note 5, characterized by the above.

[0077] (Supplementary Note 9) Use of the multilayer composite material prepared at ultra-high temperature according to any one of the above Appendices 1 to 4, wherein the multilayer composite material is used as a negative electrode material of a lithium ion battery, characterized by the use.

[0078] (Appendix 10) A lithium ion battery comprising the multilayer composite material prepared at ultra-high temperature according to any one of the above Appendices 1 to 4.

Claims

1. A multilayer composite material prepared at ultra-high temperature, wherein the multilayer composite material includes a carbon matrix and a nano-silicon-based composite material, the nano-silicon-based composite material is prepared by a thermal plasma method. Specifically, one or more substances containing micron-sized silicon powder and doping elements are collided and ionized in a high-frequency plasma processing apparatus to form a plasma gas with a temperature of 5000 K or higher, and then cooled, deposited, and nucleated to obtain a nano-scale silicon-based composite material in which the doping elements are uniformly embedded at the atomic scale. The doping elements include at least one of C, N, B, P, S, Mg, Ca, Al, Zn, Mn, Ni, or Ti, the carbon matrix is a porous carbon material, and the nano-silicon-based composite material is deposited in the porous structure of the carbon matrix, characterized in that it is a multilayer composite material.

2. The particle size of the nano-silicon-based composite material is 0.1 nm to 200 nm. The mass of the nano-silicon-based composite material accounts for 10% to 90% of the mass of the multilayer composite material. The mass of the doping elements accounts for 0.1% to 50% of the mass of the nano-silicon-based composite material. The mass of the carbon matrix accounts for 10% to 70% of the mass of the multilayer composite material, characterized in that it is the multilayer composite material according to Claim 1.

3. further including a carbon shell, the carbon shell is coated on the outer layer of the carbon matrix on which the nano-silicon-based composite material is deposited, and the mass of the carbon shell accounts for 0 to 10% of the mass of the multilayer composite material, characterized in that it is the multilayer composite material according to Claim 2.

4. When the multilayer composite material contains C element, in the NMR spectrum of the solid nuclear magnetic resonance of the multilayer composite material, when the peak of silicon is at -65 ppm to -140 ppm, it is shown that there is a resonance peak of Si-C between 10 ppm and -30 ppm, and the area ratio of the resonance peak of Si-C to the peak of silicon is 0.05 to 6.0, characterized in that it is the multilayer composite material according to Claim 1.

5. A method for preparing a multilayer composite material prepared at ultra-high temperature according to any one of Claims 1 to 4 above, wherein the preparation method is a thermal plasma method, Place the porous carbon material in the condensation region of a high-frequency plasma processing apparatus, and place a silicon powder of micron size and one or more substances containing a doping element in the high-temperature region of the high-frequency plasma processing apparatus at a mass ratio of 1:0.1 to 1:1 (the doping element includes at least one of C, N, B, P, S, Mg, Ca, Al, Zn, Mn, Ni, or Ti). Introduce a protective gas into the high-frequency plasma processing apparatus to replace the air. Turn on the plasma generator of the high-frequency plasma processing apparatus to ionize the working gas, vaporize and dissociate the silicon powder of micron size and the substance containing the doping element to form a plasma gas with a temperature of 5000 K or higher. Furthermore, carry it to the condensation region by a carrier gas, deposit silicon elements and the doping element in the pores of the porous carbon material, nucleate and grow to the nanometer size to obtain the multi-layer composite material prepared at the ultra-high temperature. A preparation method characterized by the above.

6. Further comprising performing carbon coating by at least one of vapor phase coating, liquid phase coating, and solid phase coating. The preparation method according to claim 5, characterized by the above.

7. The silicon powder of micron size is an industrial silicon powder of micron size containing one or more of those by-produced during diamond wire cutting, waste generated during the production of organosilicon, and industrial silicon powder, and the particle size D50 of the industrial silicon powder of micron size is 5 μm to 100 μm. The preparation method according to claim 5, characterized by the above.

8. The substance containing the doping element C includes one or more of carbon black, acetylene, methane, propylene, ethylene, propane, and gaseous ethanol. The substance containing the doping element N includes one or more of nitrogen, ammonia, urea, melamine, and hydrazine. The substance containing the doping element B includes one or more of boron, diborane, trimethyl borate, tripropyl borate, and boron tribromide. The substance containing the doping element P includes one or two of white phosphorus, red phosphorus, black phosphorus, phosphine, and phosphorus oxychloride. The substance containing the doping element S includes one or more of sulfur, thiourea, thiol, thiophenol, and thioether. The substance containing the doping element Mg contains one or more of magnesium simple substance, magnesium oxide and magnesium chloride, The substance containing the doping element Ca contains one or more of calcium oxide, calcium hydroxide and calcium chloride, The substance containing the doping element Al contains one or more of aluminum simple substance, alumina and aluminum chloride, The substance containing the doping element Zn contains one or more of zinc simple substance, zinc oxide, zinc hydroxide and zinc chloride, The substance containing the doping element Mn contains one or more of manganese oxide, manganese hydroxide and manganese chloride, The substance containing the doping element Ni contains one or more of nickel simple substance, nickel oxide, nickel hydroxide and nickel chloride, The substance containing the doping element Ti contains one or more of titanium simple substance, titanium oxide, titanium hydroxide and titanium chloride, The preparation method according to claim 5, characterized in that.

9. Use of the multi-layer composite material prepared at ultra-high temperature according to any one of claims 1 to 4 above, wherein the multi-layer composite material is used as a negative electrode material of a lithium-ion battery, Use characterized by that.

10. A lithium-ion battery comprising the multi-layer composite material prepared at ultra-high temperature according to any one of claims 1 to 4 above.

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