Composite materials for lithium-ion secondary batteries, their preparation methods and applications

Abstract

A composite material for lithium-ion secondary batteries and its preparation method and application are provided. [Solution] The composite material for lithium ion secondary batteries is a spherical porous non-graphitizable carbon material having hollow holes inside, and inside the pores, products (including silicon nanoparticles) formed by the decomposition of a silicon-containing gas and one or more gaseous compounds containing any of the elements C, N, B, or P are deposited. The porous non-graphitizable carbon material is prepared by hardening a non-graphitizable carbon matrix using a double emulsion method, and then further carbonizing it.

Description

[Technical Field]

[0001] [Cross reference] This application claims priority to a Chinese patent application filed with the China Patent Office on December 22, 2021, bearing application number 202111582639.1 and titled "Composite material for lithium-ion secondary batteries and its preparation method and application."

[0002] [Technical field] The present invention relates to the technical field of materials, and in particular to a composite material for lithium ion secondary batteries and its preparation method and application. [Background technology]

[0003] Silicon is an ideal anode material for high-capacity lithium-ion batteries because its theoretical specific capacity is 4200 mAh / g, an order of magnitude higher than the 372 mAh / g of conventional graphite anodes. However, the high capacity of lithium-ion batteries is accompanied by the volume expansion (300%) of silicon anodes during the lithium insertion process, which leads to massive destruction of the electrode and a decrease in battery capacity.

[0004] Currently, the effects of volume expansion can be effectively alleviated by preparing silicon-carbon composites. For example, in Chinese Patent Application No. 201510448316.1, silicon and a different carbon material are mechanically mixed twice, spray-dried, and then vapor-deposited to form a carbon shell on the outermost layer, thereby alleviating the silicon expansion problem to some extent. However, the current mainstream method of compounding is by mechanical mixing or simple coating, which does not allow the nanosilicon particles to be uniformly dispersed in the carbon material, and therefore the advantages of silicon-carbon composites cannot be fully realized. At the same time, such methods do not effectively solve the problem of material destruction caused by the large volume expansion of silicon. Summary of the Invention [Problem to be solved by the invention]

[0005] This invention provides a composite material for lithium-ion secondary batteries, its preparation method, and its applications. Nanosilicon and one or more gaseous compounds containing C, N, B, or P are uniformly dispersed within the pores of spherical porous carbon by vapor deposition. The porous structure limits the size and uniform distribution of the nanosilicon after deposition, minimizing the effects of volume expansion and avoiding the problem of poor electrical contact due to silicon pulverization. Meanwhile, the large central pores provide ample buffer space for silicon expansion, reducing the risk of structural damage to the composite. Therefore, when lithium insertion and extraction reactions are fully carried out with silicon, the composite structure can be maintained intact, further improving the electrochemical properties of the battery. Furthermore, in multi-element composites, C and N are beneficial for improving the material's cycle performance, while B and P are beneficial for improving the material's rate capability. [Means for solving the problem]

[0006] In a first aspect, an embodiment of the present invention provides a composite material for a lithium-ion secondary battery, the composite material being a spherical porous non-graphitizable carbon material having internal hollow pores, in which products (including silicon nanoparticles) formed by decomposition of a silicon-containing gas and one or more gaseous compounds containing any of C, N, B, and P elements are deposited inside the pores; Here, the porous non-graphitizable carbon material is obtained by preparing a non-graphitizable carbon matrix by hardening it using a double emulsion method, and then carbonizing it.

[0007] Preferably, the silicon content in the composite material is 1 wt % to 70 wt %.

[0008] Preferably, the particle size of the composite material is in the range of 1 μm to 100 μm, the average pore size is in the range of 0.1 nm to 10 nm, and the diameter of the hollow pores is in the range of 0.5 μm to 80 μm.

[0009] Preferably, the non-graphitizable carbon matrix of the spherical porous non-graphitizable carbon material is one or a combination of a phenolic resin, an epoxy resin, a furfural resin, or a polybutadiene resin; the silicon-containing gas is a silane compound and includes one or a combination of monosilane, trisilane, dichlorosilane, trichlorosilane, and tetrachlorosilane; The gaseous compound containing a C element includes one or more of acetylene, methane, propylene, ethylene, propane, and gaseous ethanol; The gaseous compound containing N element includes one or more of nitrogen, ammonia, urea, and melamine, the gaseous compound containing B element includes one or more of diborane, trimethyl borate, tripropyl borate, and boron tribromide; The gaseous compound containing the P element includes phosphine and / or phosphorus oxychloride.

[0010] In a second aspect, an embodiment of the present invention provides a method for preparing a composite material for a lithium ion secondary battery according to the first aspect, the method comprising: Step 1: Using pure oil as the first liquid phase, dissolving resin in a corresponding solvent, adding nonionic surfactant and curing agent to prepare a second liquid phase, oil containing surfactant as the third liquid phase, slowly adding the first liquid phase to the second liquid phase, stirring for 0.5-1 hour, adding the stirred mixture to the third liquid phase, stirring to obtain a desired emulsion, heating to 80-130°C while continuing to stir, and keeping the temperature for 1-24 hours until the resin hardens, forming resin hollow microspheres, which are then centrifuged, washed and dried; Step 2: placing the dried sample in a reactor, raising the temperature to 800°C to 1300°C, and maintaining the temperature at 800°C to 1300°C for 0.5 hours to 15 hours to perform high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix having a particle size in the range of 1 μm to 100 μm; Step 3: continuously introducing a pore-forming gas source into the obtained non-graphitizable carbon matrix at 600°C to 1000°C for 1 hour to 10 hours to subject the non-graphitizable carbon matrix to a pore-forming treatment, thereby obtaining a porous non-graphitizable carbon matrix material, wherein the pore-forming gas source is one or a combination of two of oxygen, carbon dioxide, and water vapor, and the gas flow rate of the pore-forming gas source is 2 L / min to 20 L / min; Step 4: performing vapor deposition on the obtained porous non-graphitizable carbon matrix material to obtain a composite material for a lithium ion secondary battery, wherein a gas source for the vapor deposition includes a silicon-containing gas and one or more gaseous compounds containing any of C, N, B, and P elements; Includes:

[0011] Preferably, the protective gas for vapor deposition is one of nitrogen gas or argon gas or a combination thereof, the flow rate is 1-5 L / min, the gas flow rate of the gaseous compound is 0.5-10 L / min, the flow rate of the silicon-containing gas is 0.5-10 L / min, the deposition temperature is 500-1500°C, and the deposition time is 1-20 hours.

[0012] Preferably, the resin comprises one or more combinations of a phenolic resin, an epoxy resin, a furfural resin, or a polybutadiene resin; the solvent comprises one or a combination of ethanol, acetone, and toluene; The oils include one or a combination of vegetable oil, paraffin oil, mineral oil, etc. The nonionic surfactant comprises one or more combinations of alkyl glucoside, fatty acid glyceride, sorbitan fatty acid ester, and polysorbate; The curing agent includes one or a combination of two or more of trimethylhexamethylenediamine, ethylenediamine, and metaxylenediamine, The surfactant may include one or more of stearic acid, sodium dodecylbenzenesulfonate, lecithin, etc. the silicon-containing gas is a silane compound and includes one or a combination of monosilane, trisilane, dichlorosilane, trichlorosilane, and tetrachlorosilane; The gaseous compound containing a C element includes one or more of acetylene, methane, propylene, ethylene, propane, and gaseous ethanol; The gaseous compound containing N element includes one or more of nitrogen, ammonia, urea, and melamine, the gaseous compound containing B element includes one or more of diborane, trimethyl borate, tripropyl borate, and boron tribromide; The gaseous compound containing the P element includes phosphine and / or phosphorus oxychloride.

[0013] Preferably, the mass fraction of the first liquid phase: the second liquid phase: the third liquid phase = (0, 30%]: (0, 30%]: (0, 50%], In the second liquid phase, the mass fraction of resin:solvent:hardener:nonionic surfactant is (0, 80%):(0, 90%):(0, 30%):(0, 20%), In the third liquid phase, the mass fraction of oil:surfactant is (0, 90%): (0, 30%).

[0014] In a third aspect, an embodiment of the present invention provides a negative electrode material for a lithium battery, comprising the composite material for a lithium ion secondary battery according to the first aspect above.

[0015] In a fourth aspect, an embodiment of the present invention provides a lithium ion battery comprising the composite material for a lithium ion secondary battery according to the first aspect above. [Effects of the Invention]

[0016] In the composite material for lithium-ion secondary batteries according to an embodiment of the present invention, nanosilicon and one or more gaseous compounds containing any of C, N, B, and P are uniformly dispersed within the pores of spherical porous carbon by vapor deposition. The porous structure limits the size and uniform distribution of the nanosilicon after deposition, minimizing the effects of volume expansion and avoiding the problem of poor electrical contact due to silicone pulverization. Meanwhile, the large central pores provide ample buffer space for the expansion of the silicon material, reducing the likelihood of damage to the overall composite structure due to expansion. Therefore, when lithium insertion and extraction reactions are fully carried out with the silicon, the structure of the composite material can be maintained intact, further improving the electrochemical properties of the battery. Furthermore, in the case of multi-element composites, C and N are beneficial for improving the cycle performance of the material, while B and P are beneficial for improving the rate performance of the material. The composite material for lithium-ion batteries provided by the present invention can be used in lithium-ion batteries with liquid, semi-solid, quasi-solid, and all-solid electrolytes. [Brief explanation 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 examples.

[0018] [Figure 1] 1 is a flowchart of a method for preparing a composite material for a lithium ion secondary battery according to an embodiment of the present invention. [Figure 2] 1 is a scanning electron microscope (SEM) image of a cross section of the composite material for a lithium ion secondary battery prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF 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 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.

[0020] The present invention proposes a composite material for lithium ion secondary batteries, which is a spherical porous non-graphitizable carbon material having hollow pores therein, in which products (including silicon nanoparticles) formed by decomposition of a silicon-containing gas and one or more gaseous compounds containing any of C, N, B, and P elements are deposited inside the pores, Here, the porous non-graphitizable carbon material is obtained by preparing a non-graphitizable carbon matrix by hardening it using a double emulsion method, and then carbonizing it.

[0021] The silicon content in the composite material is 1 wt% to 70 wt%.

[0022] The particle size range of the composite material is 1 μm to 100 μm, the average pore size is 0.1 nm to 10 nm, and the diameter of the internal hollow pores is 0.5 μm to 80 μm.

[0023] The flow of the method for producing the hollow pore composite material for lithium batteries is shown in FIG. 1, and includes the following steps: In step 1, pure oil is used as the first liquid phase, resin is dissolved in a corresponding solvent, and a nonionic surfactant and a curing agent are added to prepare a second liquid phase. The oil containing the surfactant is used as the third liquid phase. The first liquid phase is slowly added to the second liquid phase and stirred for 0.5 to 1 hour, and the stirred mixture is added to the third liquid phase and stirred to obtain the desired emulsion. The mixture is heated to 80 to 130°C while continuing to stir, and kept at this temperature for 1 to 24 hours until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried. the resin comprises one or a combination of a phenolic resin, an epoxy resin, a furfural resin, or a polybutadiene resin; and the solvent comprises one or a combination of a phenolic resin, an epoxy resin, a furfural resin, or a polybutadiene resin; The oils include one or a combination of more than one of vegetable oil, paraffin oil, mineral oil, etc.; the nonionic surfactants include one or a combination of more than one of alkyl glucoside, fatty acid glyceride, sorbitan fatty acid ester, polysorbate; the hardening agent includes one or a combination of more than one of trimethylhexamethylenediamine, ethylenediamine, metaxylenediamine; and the surfactants include one or a combination of more than one of stearic acid, sodium dodecylbenzenesulfonate, lecithin, etc.

[0024] The mass fraction of the first liquid phase: the second liquid phase: the third liquid phase = (0, 30%): (0, 30%): (0, 50%). In the second liquid phase, the mass fraction is resin:solvent:hardener:nonionic surfactant = (0, 80%]:(0, 90%]:[0, 30%]:(0, 20%], In the third liquid phase, the mass fraction of oil:surfactant is (0, 90%): (0, 30%).

[0025] In step 2, the dried sample is placed in a reactor, the temperature is raised to 800°C to 1300°C, and the sample is kept at 800°C to 1300°C for 0.5 to 15 hours for high-temperature carbonization treatment to obtain a non-graphitizable carbon matrix with a particle size in the range of 1 μm to 100 μm. Here, as the reactor, specifically, a general reactor such as a high-temperature reactor is selected.

[0026] In step 3, a pore-forming gas source is continuously introduced into the obtained non-graphitizable carbon matrix at 600°C to 1000°C for 1 hour to 10 hours to subject the non-graphitizable carbon matrix to a pore-forming treatment, thereby obtaining a porous non-graphitizable carbon matrix material, Here, the pore-forming gas source is one or a combination of oxygen, carbon dioxide, and water vapor, and the gas flow rate of the pore-forming gas source is 2 L / min to 20 L / min.

[0027] In step 4, vapor deposition is performed on the obtained porous non-graphitizable carbon matrix material to obtain a composite material for a lithium ion secondary battery, Here, the gas source for vapor phase deposition includes a silicon-containing gas and one or more gaseous compounds containing any of the elements C, N, B, and P.

[0028] The protective gas for vapor deposition is one of nitrogen gas or argon gas or a combination thereof, with a flow rate of 1-5 L / min, the gas flow rate of the gaseous compound is 0.5-10 L / min, the flow rate of the silicon-containing gas is 0.5-10 L / min, the deposition temperature is 500-1500°C, and the deposition time is 1-20 hours.

[0029] the silicon-containing gas is a silane compound, and includes one or a combination of monosilane, trisilane, dichlorosilane, trichlorosilane, and tetrachlorosilane; The gaseous compound containing a C element includes one or more of acetylene, methane, propylene, ethylene, propane, and gaseous ethanol; The gaseous compound containing an N element includes one or more of nitrogen, ammonia, urea, and melamine, the gaseous compound containing B element includes one or more of diborane, trimethyl borate, tripropyl borate, and boron tribromide; The gaseous compound containing the element P includes phosphine and / or phosphorus oxychloride.

[0030] The composite material for lithium ion secondary batteries prepared in the present invention can be used as a negative electrode material for lithium ion batteries.

[0031] In order to better understand the technical solution of the present invention, several specific examples will be given below to describe the specific process for preparing a composite material for a lithium ion secondary battery using the method according to the above embodiment of the present invention, as well as the application method and battery characteristics of the same in a lithium ion secondary battery.

[0032] [Example 1] This example provides a method for preparing a composite material for a lithium-ion secondary battery, which includes the following steps: In step 1, vegetable oil is used as the first liquid phase, phenolic resin is dissolved in alcohol, and alkyl glucoside and ethylenediamine are added to prepare the second liquid phase. An oil containing stearic acid is used as the third liquid phase. The first liquid phase is slowly added to the second liquid phase and stirred for 1 hour. The stirred mixture is then added to the third liquid phase and stirred to obtain the desired emulsion. The mixture is heated to 130°C while continuing to stir, and kept at this temperature for 1 hour until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried. In step 2, the dried sample is placed in a reactor, the temperature is raised to 800°C, and the temperature is maintained for 0.5 hours to subject the dried sample to high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix with a particle size of 10.8 μm. In step 3, the non-graphitizable carbon matrix obtained in step 2 is subjected to a pore-forming treatment, the gas source used is oxygen, the flow rate is 2 L / min, the pore-forming temperature is 600°C, and the time is 10 hours. In step 4, nitrogen gas is used as the protective and / or carrier gas at a flow rate of 1 L / min. The porous carbon obtained in step 3 is used as the matrix. Monosilane, a silicon-containing gas, is used as the silicon source. These are introduced into a reaction vessel together with methane, a compound containing carbon, in gaseous form for vapor deposition. The monosilane and methane gas flow rates are 0.5 L / min and 0.5 L / min, respectively. The deposition temperature is 500°C, and the deposition time is 20 hours, yielding a composite material for lithium-ion secondary batteries.

[0033] 2 is an SEM image of the cross section of the composite material for lithium-ion secondary batteries prepared in Example 1 of the present invention. The SEM image of the cross section shows that there is a large cavity in the central region inside the material, which not only enriches the pores but also provides a large buffer space for the expansion of silicon.

[0034] The obtained material is used as the negative electrode material.

[0035] The resulting negative electrode material, conductive additive carbon black, and adhesive (1:1 sodium cellulose and styrene butadiene rubber) were weighed in a 95:2:3 ratio. A slurry was prepared in a beater at room temperature. The prepared slurry was evenly coated on copper foil. After drying for 2 hours in a blast oven at 50°C, it was cut into 8 x 8 mm pole pieces and dried for 10 hours in a vacuum oven at 100°C under vacuum. The dried pole pieces were immediately transferred into a glove box for battery assembly.

[0036] The simulated battery was assembled in a glove box containing a high-purity Ar atmosphere. The lithium metal counter electrode and an ethylene carbonate (EC) / dimethyl carbonate (DMC) solution containing 1 mol / L LiPF6 were used as the electrolyte. A constant-current charge / discharge test was performed using a charger / discharger. The discharge cutoff voltage was 0.005 V, the charge cutoff voltage was 1.5 V, and the charge / discharge test was performed at a C / 10 current density. The results are shown in Table 1.

[0037] [Example 2] This example provides a method for preparing a composite material for a lithium ion secondary battery, comprising the following steps: In step 1, vegetable oil is used as the first liquid phase, phenolic resin is dissolved in alcohol, and alkyl glucoside and ethylenediamine are added to prepare the second liquid phase. An oil containing stearic acid is used as the third liquid phase. The first liquid phase is slowly added to the second liquid phase and stirred for 1 hour. The stirred mixture is then added to the third liquid phase and stirred to obtain the desired emulsion. The mixture is heated to 80°C while continuing to stir, and kept at this temperature for 24 hours until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried. In step 2, the dried sample is placed in a reactor, the temperature is raised to 1300°C, and the temperature is maintained for 0.5 hours to subject the dried sample to high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix with a particle size of 12.1 μm. In step 3, the non-graphitizable carbon matrix obtained in step 2 is subjected to a pore-forming treatment. The gas source used is a combination of carbon dioxide and water vapor, the flow rate is 20 L / min, the pore-forming temperature is 1000°C, and the pore-forming time is 1 hour. In step 4, argon gas was used as the protective gas and / or carrier gas at a flow rate of 1.5 L / min. The porous carbon obtained in step 3 was used as the matrix. The silicon-containing gas trisilane was used as the silicon source. The silicon source and ammonia, a compound containing nitrogen, were introduced into the reaction vessel in gaseous form for vapor deposition. The trisilane gas flow rate was 0.8 L / min, and the ammonia-containing gas flow rate was 0.8 L / min. The deposition temperature was 600°C, and the deposition time was 12.5 hours.

[0038] The button battery was assembled according to the method of Example 1 above, and the electrochemical properties were measured and evaluated under the same test conditions. The results are shown in Table 1.

[0039] [Example 3] This example provides a method for preparing a composite material for a lithium-ion secondary battery, which includes the following steps: In step 1, mineral oil is used as the first liquid phase, phenolic resin is dissolved in alcohol, and alkyl glucoside and meta-xylenediamine are added to prepare the second liquid phase. An oil containing stearic acid is used as the third liquid phase. The first liquid phase is slowly added to the second liquid phase and stirred for 3 hours, after which the stirred mixture is added to the third liquid phase and stirred to obtain the desired emulsion. The mixture is heated to 100°C while continuing to stir, and kept at this temperature for 4 hours until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried. In step 2, the dried sample is placed in a reactor, the temperature is raised to 800°C, and the temperature is maintained for 5 hours to subject the dried sample to high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix with a particle size of 13.5 μm. In step 3, the non-graphitizable carbon matrix obtained in step 2 is subjected to a pore-forming treatment, the gas source used is water vapor, the flow rate is 2 L / min, the pore-forming temperature is 1000°C, and the time is 10 hours. In step 4, nitrogen gas was used as the protective and / or carrier gas at a flow rate of 2 L / min. The porous carbon obtained in step 3 was used as the matrix. The silicon-containing gas, dichlorosilane, was used as the silicon source. The silicon source and the boron-containing compound, tripropyl borate, were introduced into the reaction vessel in gaseous form for vapor deposition. The dichlorosilane and tripropyl borate gas flow rates were 1 L / min and 1 L / min, respectively. The deposition temperature was 700°C, and the deposition time was 10 hours.

[0040] A button battery was assembled according to the method of Example 1 above, and its electrochemical properties were measured and evaluated under the same test conditions. The results are shown in Table 1.

[0041] [Example 4] This example provides a method for preparing a composite material for a lithium-ion secondary battery, which includes the following steps: In step 1, vegetable oil is used as the first liquid phase, phenolic resin is dissolved in alcohol, and alkyl glucoside and ethylenediamine are added to prepare the second liquid phase. An oil containing stearic acid is used as the third liquid phase. The first liquid phase is slowly added to the second liquid phase and stirred for 1 hour. The stirred mixture is then added to the third liquid phase and stirred to obtain the desired emulsion. The mixture is heated to 130°C while continuing to stir, and kept at this temperature for 5 hours until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried. In step 2, the dried sample is placed in a reactor, the temperature is raised to 1000°C, and the temperature is maintained for 6 hours to subject the dried sample to high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix with a particle size of 9.2 μm. In step 3, the non-graphitizable carbon matrix obtained in step 2 is subjected to a pore-forming treatment, the gas source used is carbon dioxide, the flow rate is 2 L / min, the pore-forming temperature is 950°C, and the time is 6 hours. In step 4, argon gas was used as the protective and / or carrier gas at a flow rate of 2.5 L / min. The porous carbon obtained in step 3 was used as the matrix. The silicon-containing gas trichlorosilane was used as the silicon source. The silicon source and the phosphorus oxychloride gas were introduced into the reaction vessel in gaseous form for vapor deposition. The trichlorosilane gas flow rate was 1.25 L / min, and the phosphorus oxychloride gaseous compound flow rate was 1.25 L / min. The deposition temperature was 800°C, and the deposition time was 8 hours.

[0042] A button battery was assembled according to the method of Example 1 above, and its electrochemical properties were measured and evaluated under the same test conditions. The results are shown in Table 1.

[0043] [Example 5] This example provides a method for preparing a composite material for a lithium-ion secondary battery, which includes the following steps: In step 1, paraffin oil is used as the first liquid phase, phenolic resin is dissolved in alcohol, and alkyl glucoside and ethylenediamine are added to prepare the second liquid phase. An oil containing stearic acid is used as the third liquid phase. The first liquid phase is slowly added to the second liquid phase and stirred for 1 hour. The stirred mixture is then added to the third liquid phase and stirred to obtain the desired emulsion. The mixture is heated to 130°C while continuing to stir, and kept at this temperature for 10 hours until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried. In step 2, the dried sample is placed in a reactor, the temperature is raised to 800°C, and the temperature is maintained for 2 hours to subject the dried sample to high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix with a particle size of 15.1 μm. In step 3, the non-graphitizable carbon matrix obtained in step 2 is subjected to a pore-forming treatment, the gas source used is carbon dioxide, the flow rate is 5 L / min, the pore-forming temperature is 800°C, and the pore-forming time is 2 hours. In step 4, nitrogen gas was used as the protective and / or carrier gas at a flow rate of 3 L / min. The porous carbon obtained in step 3 was used as the matrix. The silicon-containing gas tetrachlorosilane was used as the silicon source. The silicon-containing gas, methane, ammonia, trimethyl borate, and phosphorus oxychloride, which were gaseous compounds containing carbon, nitrogen, boron, and phosphorus, were introduced into the reactor in gaseous form. The flow rate of tetrachlorosilane was 2 L / min, and the flow rates of methane, ammonia, trimethyl borate, and phosphorus oxychloride were all 0.5 L / min. The deposition temperature was 900°C, and the deposition time was 5 hours.

[0044] A button battery was assembled according to the method of Example 1 above, and its electrochemical properties were measured and evaluated under the same test conditions. The results are shown in Table 1.

[0045] [Example 6] This example provides a method for preparing a composite material for a lithium-ion secondary battery, which includes the following steps: In step 1, vegetable oil is used as the first liquid phase, phenolic resin is dissolved in alcohol, and alkyl glucoside and ethylenediamine are added to prepare the second liquid phase. An oil containing stearic acid is used as the third liquid phase. The first liquid phase is slowly added to the second liquid phase and stirred for 1 hour. The stirred mixture is then added to the third liquid phase and stirred to obtain the desired emulsion. The mixture is heated to 130°C while continuing to stir, and kept at this temperature for 14 hours until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried. In step 2, the dried sample is placed in a reactor, the temperature is raised to 1300°C, and the temperature is maintained for 2 hours to subject the dried sample to high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix with a particle size of 8.5 μm. In step 3, the non-graphitizable carbon matrix obtained in step 2 is subjected to a pore-forming treatment, the gas source used is oxygen, the flow rate is 2 L / min, the pore-forming temperature is 900°C, and the time is 2 hours. In step 4, argon gas was used as the protective and / or carrier gas at a flow rate of 3.5 L / min. The porous carbon obtained in step 3 was used as the matrix. The silicon-containing gases monosilane and trisilane were used as the silicon source. These gases were introduced into the reaction vessel together with gaseous compounds containing C, N, B, and P, propylene, urea, tripropyl borate, and phosphine, at a gas flow rate of 1.25 L / min for monosilane and trisilane, and 0.6 L / min for propylene, urea, tripropyl borate, and phosphine, respectively. The deposition temperature was 1000°C, and the deposition time was 4 hours.

[0046] A button battery was assembled according to the method of Example 1 above, and its electrochemical properties were measured and evaluated under the same test conditions. The results are shown in Table 1.

[0047] [Example 7] This example provides a method for preparing a composite material for a lithium-ion secondary battery, which includes the following steps: In step 1, vegetable oil is used as the first liquid phase, phenolic resin is dissolved in alcohol, and polysorbate and meta-xylenediamine are added to prepare the second liquid phase. An oil containing stearic acid is used as the third liquid phase. The first liquid phase is slowly added to the second liquid phase and stirred for 1 hour. The stirred mixture is then added to the third liquid phase and stirred to obtain the desired emulsion. The mixture is heated to 130°C while continuing to stir, and kept at this temperature for 5 hours until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried. In step 2, the dried sample is placed in a reactor, the temperature is raised to 900°C, and the temperature is maintained for 2 hours to subject the dried sample to high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix with a particle size of 13.8 μm. In step 3, the non-graphitizable carbon matrix obtained in step 2 is subjected to a pore-forming treatment, the gas source used is one or a combination of two of oxygen, carbon dioxide, and water vapor, the pore-forming temperature is 1000°C, and the time is 5 hours. In step 4, nitrogen gas was used as the protective and / or carrier gas at a flow rate of 4 L / min. The porous carbon obtained in step 3 was used as the matrix. Silicon-containing gases, monosilane, trisilane, and dichlorosilane, were used as the silicon source. These gases were introduced into the reaction vessel along with propane, hydrazine, diborane, and phosphine, which contain the elements C, N, B, and P. The gas flow rates for monosilane, trisilane, and dichlorosilane were all 1.3 L / min, and for propane, hydrazine, diborane, and phosphine were all 0.5 L / min. The deposition temperature was 1100°C, and the deposition time was 2.5 hours.

[0048] A button battery was assembled according to the method of Example 1 above, and its electrochemical properties were measured and evaluated under the same test conditions. The results are shown in Table 1.

[0049] [Example 8] This example provides a method for preparing a composite material for a lithium-ion secondary battery, which includes the following steps: In step 1, vegetable oil is used as the first liquid phase, phenolic resin is dissolved in alcohol, and fatty acid glyceride and ethylenediamine are added to prepare the second liquid phase. An oil containing stearic acid is used as the third liquid phase. The first liquid phase is slowly added to the second liquid phase and stirred for 1 hour. The stirred mixture is then added to the third liquid phase and stirred to obtain the desired emulsion. The mixture is heated to 80-130°C while continuing to stir, and kept at this temperature for 12 hours until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried. In step 2, the dried sample is placed in a reactor, the temperature is raised to 1200°C, and the temperature is maintained for 5 hours to subject the dried sample to high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix with a particle size of 15.8 μm. In step 3, the non-graphitizable carbon matrix obtained in step 2 is subjected to a pore-forming treatment, the gas source used is water vapor, the flow rate is 5 L / min, the pore-forming temperature is 1000°C, and the pore-forming time is 1.5 hours. In step 4, argon gas was used as the protective and / or carrier gas at a flow rate of 4.5 L / min. The porous carbon obtained in step 3 was used as the matrix. Silicon-containing gases, monosilane, trisilane, and trichlorosilane, were used as the silicon source. These gases were introduced into the reaction vessel along with ethanol, nitrogen, trimethyl borate, and phosphorus oxychloride, which are compounds containing C, N, B, and P elements. The gas flow rates for monosilane, trisilane, and trichlorosilane were all 1.7 L / min, and the gas flow rates for ethanol, nitrogen, trimethyl borate, and phosphorus oxychloride were 1.25 L / min. The deposition temperature was 1200°C, and the deposition time was 2 hours.

[0050] A button battery was assembled according to the method of Example 1 above, and its electrochemical properties were measured and evaluated under the same test conditions. The results are shown in Table 1.

[0051] [Example 9] This example provides a method for preparing a composite material for a lithium ion secondary battery, which comprises the following steps: Includes flops. In step 1, vegetable oil is used as the first liquid phase, phenolic resin is dissolved in alcohol, and alkyl glucoside and trimethylhexamethylenediamine are added to prepare the second liquid phase. Oils containing sodium dodecylbenzenesulfonate are used as the third liquid phase. The first liquid phase is slowly added to the second liquid phase and stirred for 1 hour. The stirred mixture is then added to the third liquid phase and stirred to obtain the desired emulsion. The mixture is heated to 100°C while continuing to stir, and kept at this temperature for 6 hours until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried. In step 2, the dried sample is placed in a reactor, the temperature is raised to 900°C, and the temperature is maintained for 6 hours to subject the dried sample to high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix with a particle size of 14.5 μm. In step 3, the non-graphitizable carbon matrix obtained in step 2 is subjected to a pore-forming treatment, the gas source used is carbon dioxide, the flow rate is 10 L / min, the pore-forming temperature is 1000°C, and the pore-forming time is 1 hour. In step 4, nitrogen gas was used as the protective and / or carrier gas at a flow rate of 5 L / min. The porous carbon obtained in step 3 was used as the matrix. Silicon-containing gases trisilane, dichlorosilane, and trichlorosilane were used as the silicon source. These gases were introduced into the reaction vessel together with ethylene, propane, urea, melamine, tripropyl borate, boron tribromide, phosphine, and phosphorus oxychloride, which contain carbon, nitrogen, boron, and phosphorus elements, at a gas flow rate of 2.7 L / min. The gas flow rates of ethylene, propane, urea, melamine, tripropyl borate, boron tribromide, phosphine, and phosphorus oxychloride were all 1 L / min. The deposition temperature was 1400 °C, and the deposition time was 1.25 hours.

[0052] A button battery was assembled according to the method of Example 1 above, and its electrochemical properties were measured and evaluated under the same test conditions. The results are shown in Table 1.

[0053] [Example 10] This example provides a method for preparing a composite material for a lithium-ion secondary battery, which includes the following steps: In step 1, vegetable oil is used as the first liquid phase, phenolic resin is dissolved in alcohol, and alkyl glucoside and ethylenediamine are added to prepare the second liquid phase. An oil containing stearic acid is used as the third liquid phase. The first liquid phase is slowly added to the second liquid phase and stirred for 1 hour. The stirred mixture is then added to the third liquid phase and stirred to obtain the desired emulsion. The mixture is heated to 130°C while continuing to stir, and kept at this temperature for 2 hours until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried. In step 2, the dried sample is placed in a reactor, the temperature is raised to 900°C, and the temperature is maintained at 1000°C for 6 hours, whereby the dried sample is subjected to high-temperature carbonization treatment to obtain a non-graphitizable carbon matrix with a particle size of 16.2 μm. In step 3, the non-graphitizable carbon matrix obtained in step 2 is subjected to a pore-forming treatment, the gas source used is one or a combination of two of oxygen, carbon dioxide, and water vapor, the pore-forming temperature is 800°C, and the time is 5 hours. Step 4: Argon gas was used as the protective and / or carrier gas at a flow rate of 5 L / min. The porous carbon obtained in Step 3 was used as the matrix. Silicon-containing gases dichlorosilane, trichlorosilane, and tetrachlorosilane were used as the silicon source. These gases were introduced into the reactor together with carbon-, nitrogen-, boron-, and phosphorus-containing compounds acetylene, propane, ammonia, hydrazine, tripropyl borate, boron tribromide, phosphine, and phosphorus oxychloride. The gas flow rates of dichlorosilane, trichlorosilane, and tetrachlorosilane were all 3.3 L / min, and the gas flow rates of acetylene, propane, ammonia, hydrazine, tripropyl borate, boron tribromide, phosphine, and phosphorus oxychloride were all 1.3 L / min. The deposition temperature was 1500 °C, and the deposition time was 1 hour.

[0054] A button battery was assembled according to the method of Example 1 above, and its electrochemical properties were measured and evaluated under the same test conditions. The results are shown in Table 1.

[0055] For easier comparison, comparative samples were prepared according to the following method.

[0056] [Comparative Example 1] This comparative example provides a method for preparing a silicon-carbon composite material based on the prior art, which includes the following steps: (1) Silicon particles, polyvinylpyrrolidone as a precursor of the carbon source, graphite, and citric acid as an antioxidant are added to an ethanol system, and the mixture is ground in a mass ratio of 1:1:1:0.1 to obtain a dispersion. (2) The dispersion is spray-dried to obtain silicon-carbon powder. (3) The powder is then vapor-coated to finally obtain a silicon-carbon composite material.

[0057] A button battery was assembled according to the method of Example 1 above, and its electrochemical properties were measured and evaluated under the same test conditions. The results are shown in Table 1.

[0058] [Table 1]

[0059] Comparison of the comparative examples and examples shows that the silicon-containing porous hollow non-graphitizable carbon composite material provided by the present invention has higher specific capacity and first-cycle Coulombic efficiency. At the same time, the present invention can further improve the first-cycle Coulombic efficiency of the material by adjusting the deposition time, temperature, and gas flow rate. The present invention scientifically sets the gas flow rate and temperature during preparation to avoid excessively high gas flow rate and temperature, which would cause the silane to decompose too quickly and deposit directly on the surface of the carbon matrix, thereby affecting battery performance. At the same time, it also avoids excessively low temperature, which would cause incomplete decomposition of the silane and affect battery capacity.

[0060] In the composite material for lithium-ion secondary batteries according to an embodiment of the present invention, nanosilicon and one or more gaseous compounds containing any of C, N, B, and P are uniformly dispersed within the pores of spherical porous carbon by vapor deposition. The porous structure limits the size and uniform distribution of the nanosilicon after deposition, minimizing the effects of volume expansion and avoiding the problem of poor electrical contact due to silicon pulverization. Meanwhile, the large central pores provide ample buffer space for the expansion of the silicon material, reducing the likelihood of damage to the overall composite structure due to expansion. Therefore, when lithium insertion and extraction reactions are fully carried out with silicon, the composite structure can be maintained intact, further improving the electrochemical properties of the battery. Furthermore, in the case of multi-element composites, C and N are beneficial for improving the cycle performance of the material, while B and P are beneficial for improving the rate performance of the material. The composite material for lithium-ion batteries provided by the present invention can be used in lithium-ion batteries with liquid, semi-solid, quasi-solid, and all-solid electrolytes. Furthermore, the multi-element composite further improves the specific capacity and first-cycle Coulombic efficiency.

[0061] 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.

[0062] (Addendum) (Appendix 1) A composite material for a lithium ion secondary battery, The composite material is a spherical porous non-graphitizable carbon material having hollow pores therein, and a product (including silicon nanoparticles) formed by decomposition of a silicon-containing gas and one or more gaseous compounds containing any of C, N, B, and P elements is deposited inside the pores; The porous non-graphitizable carbon material is prepared by hardening a non-graphitizable carbon matrix by a double emulsion method, and then carbonizing the hardened non-graphitizable carbon matrix. A composite material characterized by:

[0063] (Appendix 2) The silicon content in the composite material is 1 wt% to 70 wt%. 2. The composite material of claim 1.

[0064] (Appendix 3) The particle size of the composite material is in the range of 1 μm to 100 μm, the average pore size is in the range of 0.1 nm to 10 nm, and the diameter of the hollow pores is in the range of 0.5 μm to 80 μm. 2. The composite material of claim 1.

[0065] (Appendix 4) the non-graphitizable carbon matrix of the spherical porous non-graphitizable carbon material is one or a combination of a phenolic resin, an epoxy resin, a furfural resin, or a polybutadiene resin; the silicon-containing gas is a silane compound and includes one or a combination of monosilane, trisilane, dichlorosilane, trichlorosilane, and tetrachlorosilane; The gaseous compound containing a C element includes one or more of acetylene, methane, propylene, ethylene, propane, and gaseous ethanol; The gaseous compound containing N element includes one or more of nitrogen, ammonia, urea, and melamine, the gaseous compound containing B element includes one or more of diborane, trimethyl borate, tripropyl borate, and boron tribromide; The gaseous compound containing the P element includes phosphine and / or phosphorus oxychloride. 2. The composite material of claim 1.

[0066] (Appendix 5) A method for preparing a composite material for a lithium ion secondary battery according to any one of Supplementary Notes 1 to 4, comprising: Step 1: Using pure oil as the first liquid phase, dissolving resin in a corresponding solvent, adding nonionic surfactant and curing agent to prepare a second liquid phase, oil containing surfactant as the third liquid phase, slowly adding the first liquid phase to the second liquid phase, stirring for 0.5-1 hour, adding the stirred mixture to the third liquid phase, stirring to obtain a desired emulsion, heating to 80-130°C while continuing to stir, and keeping the temperature for 1-24 hours until the resin hardens, forming resin hollow microspheres, which are then centrifuged, washed and dried; Step 2: placing the dried sample in a reactor, raising the temperature to 800°C to 1300°C, and maintaining the temperature at 800°C to 1300°C for 0.5 hours to 15 hours to perform high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix having a particle size in the range of 1 μm to 100 μm; Step 3: continuously introducing a pore-forming gas source into the obtained non-graphitizable carbon matrix at 600°C to 1000°C for 1 hour to 10 hours to subject the non-graphitizable carbon matrix to a pore-forming treatment, thereby obtaining a porous non-graphitizable carbon matrix material, wherein the pore-forming gas source is one or a combination of two of oxygen, carbon dioxide, and water vapor, and the gas flow rate of the pore-forming gas source is 2 L / min to 20 L / min; Step 4: performing vapor deposition on the obtained porous non-graphitizable carbon matrix material to obtain a composite material for a lithium ion secondary battery, wherein a gas source for the vapor deposition includes a silicon-containing gas and one or more gaseous compounds containing any of C, N, B, and P elements; Including, A preparation method characterized by:

[0067] (Appendix 6) The protective gas for the vapor deposition is one of nitrogen gas or argon gas or a combination thereof, and the flow rate is 1-5 L / min, the gas flow rate of the gaseous compound is 0.5-10 L / min, the flow rate of the silicon-containing gas is 0.5-10 L / min, the deposition temperature is 500-1500°C, and the deposition time is 1-20 hours; 6. The method of claim 5,

[0068] (Appendix 7) the resin comprises one or a combination of a phenolic resin, an epoxy resin, a furfural resin, or a polybutadiene resin; the solvent comprises one or a combination of ethanol, acetone, and toluene; The oils include one or a combination of vegetable oil, paraffin oil, mineral oil, etc. The nonionic surfactant comprises one or more combinations of alkyl glucoside, fatty acid glyceride, sorbitan fatty acid ester, and polysorbate; The curing agent includes one or a combination of two or more of trimethylhexamethylenediamine, ethylenediamine, and metaxylenediamine, The surfactant may include one or more of stearic acid, sodium dodecylbenzenesulfonate, lecithin, etc. the silicon-containing gas is a silane compound and includes one or a combination of monosilane, trisilane, dichlorosilane, trichlorosilane, and tetrachlorosilane; The gaseous compound containing a C element includes one or more of acetylene, methane, propylene, ethylene, propane, and gaseous ethanol; The gaseous compound containing N element includes one or more of nitrogen, ammonia, urea, and melamine, the gaseous compound containing B element includes one or more of diborane, trimethyl borate, tripropyl borate, and boron tribromide; The gaseous compound containing the P element includes phosphine and / or phosphorus oxychloride. 6. The method of claim 5,

[0069] (Appendix 8) The mass fraction of the first liquid phase: the second liquid phase: the third liquid phase = (0, 30%): (0, 30%): (0, 50%). In the second liquid phase, the mass fraction of resin:solvent:hardener:nonionic surfactant is (0, 80%):(0, 90%):(0, 30%):(0, 20%), In the third liquid phase, the mass fraction of oil: surfactant = (0, 90%]: (0, 30%], 6. The method of claim 5,

[0070] (Appendix 9) The composite material for a lithium ion secondary battery according to any one of Supplementary Notes 1 to 4 is included. A negative electrode material for a lithium ion battery.

[0071] (Appendix 10) The composite material for a lithium ion secondary battery according to any one of Supplementary Notes 1 to 4 is included. A lithium-ion battery characterized by:

Claims

1. A method for preparing a composite material for a lithium ion secondary battery, comprising: Step 1: Using pure oil as a first liquid phase, dissolving resin in a corresponding solvent, adding nonionic surfactant and curing agent to prepare a second liquid phase, oil containing surfactant as a third liquid phase, slowly adding the first liquid phase to the second liquid phase, stirring for 0.5 to 1 hour, and then adding the stirred mixture to the third liquid phase and stirring to obtain a desired emulsion, heating to 80 to 130°C while continuing to stir, and keeping the temperature for 1 to 24 hours until the resin hardens, forming hollow resin microspheres, which are then centrifuged, washed, and dried; Step 2: placing the dried sample in a reactor, raising the temperature to 800°C to 1300°C, and maintaining the temperature at 800°C to 1300°C for 0.5 hours to 15 hours to perform high-temperature carbonization treatment, thereby obtaining a non-graphitizable carbon matrix having a particle size distribution of 1 μm to 100 μm; Step 3: continuously introducing a pore-forming gas source into the obtained non-graphitizable carbon matrix at 600°C to 1000°C for 1 hour to 10 hours to form pores in the non-graphitizable carbon matrix, thereby obtaining a porous non-graphitizable carbon matrix material, wherein the pore-forming gas source is one or a combination of two of oxygen, carbon dioxide, and water vapor, and the gas flow rate of the pore-forming gas source is 2 L / min to 20 L / min; Step 4: performing vapor deposition on the obtained porous non-graphitizable carbon matrix material to obtain a composite material for a lithium ion secondary battery, wherein a gas source for the vapor deposition includes a silicon-containing gas and one or more gaseous compounds containing any of C, N, B, and P elements; Including, A preparation method characterized by:

2. the protective gas for vapor deposition is one of nitrogen gas or argon gas or a combination thereof, and the flow rate is 1-5 L / min; the gas flow rate of the gaseous compound is 0.5-10 L / min; the flow rate of the silicon-containing gas is 0.5-10 L / min; the deposition temperature is 500-1500°C; and the deposition time is 1-20 hours; 2. The method of claim 1 .

3. the resin comprises one or a combination of two or more of a phenolic resin, an epoxy resin, a furfural resin, or a polybutadiene resin; the solvent comprises one or a combination of ethanol, acetone, and toluene; The oils include one or a combination of vegetable oil, paraffin oil, mineral oil, etc. The nonionic surfactant comprises one or a combination of more than one of alkyl glucoside, fatty acid glyceride, sorbitan fatty acid ester, and polysorbate; The curing agent includes one or a combination of two or more of trimethylhexamethylenediamine, ethylenediamine, and metaxylenediamine, The surfactant may include one or a combination of sodium dodecylbenzenesulfonate, lecithin, and the like; the silicon-containing gas is a silane compound and includes one or a combination of two or more of monosilane, trisilane, dichlorosilane, trichlorosilane, and tetrachlorosilane; The gaseous compound containing a C element includes one or more of acetylene, methane, propylene, ethylene, propane, and gaseous ethanol; The gaseous compound containing an N element includes one or more of nitrogen, ammonia, urea, and melamine, the gaseous compound containing the B element includes one or more of diborane, trimethyl borate, tripropyl borate, and boron tribromide; The gaseous compound containing the P element includes phosphine and / or phosphorus oxychloride.

2. The method of claim 1 .

4. The mass fraction of the first liquid phase: the second liquid phase: the third liquid phase = (0, 30%]: (0, 30%]: (0, 50%], In the second liquid phase, the mass fraction is resin:solvent:hardener:nonionic surfactant=(0,80%]:(0,90%]:(0,30%]:(0,20%], In the third liquid phase, the mass fraction of oil: surfactant is (0.90%]: (0.30%), 2. The method of claim 1 .

5. A composite material for a lithium ion secondary battery, The composite material is a spherical porous non-graphitizable carbon material having hollow pores therein, in which silicon nanoparticles are deposited inside the hollow pores, and in which one or more of C, N, B, and P elements are compounded. A composite material characterized by:

6. The silicon content in the composite material is 1 wt% to 70 wt%.

6. The composite material according to claim 5.

7. The particle size distribution of the composite material is 1 μm to 100 μm, the average pore diameter is 0.1 nm to 10 nm, and the diameter of the hollow pores is 0.5 μm to 80 μm.

6. The composite material according to claim 5.

8. The composite material for a lithium ion secondary battery according to any one of claims 5 to 7, A negative electrode material for a lithium ion battery.

9. The composite material for a lithium ion secondary battery according to any one of claims 5 to 7, A lithium-ion battery characterized by:

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