Silicon-based composite material, preparation method thereof, negative plate and all-solid-state battery

Abstract

The invention relates to a silicon-based composite material and a preparation method thereof, a negative plate and an all-solid-state battery, and the preparation method of the silicon-based composite material comprises the following steps: in an inert atmosphere, mixing silicon powder and metal oxygen halide with a layered structure, then carrying out ball milling, and then carrying out solid-phase reaction to obtain silicon-based powder; in an inert atmosphere, the silicon-based powder and metal halide are mixed and then subjected to ball milling, then a halogenation reaction is conducted in a halogenation reaction gas environment, the silicon-based composite material is obtained, the radius of metal ions in the metal halide is 40-60 pm, and the valence of the metal ions in the metal halide is larger than or equal to trivalence. The silicon-based composite material prepared by the preparation method disclosed by the invention can effectively inhibit interface side reaction and enhance the structural stability of the material, so that the comprehensive electrochemical properties such as rate capability, cycling stability and coulombic efficiency of the all-solid-state battery can be synergistically improved.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, and in particular to silicon-based composite materials and their preparation methods, negative electrode sheets, and all-solid-state batteries. Background Technology

[0002] Achieving high safety and high energy density in all-solid-state batteries requires the development of high-capacity anode materials. Silicon, as an anode material, possesses a specific capacity of 3579 mAh / g and a low voltage plateau of ~0.4V, and its raw materials are widely available and inexpensive, making it an ideal anode material for solid-state batteries. However, silicon anodes suffer from severe interfacial side reactions with traditional solid-state electrolytes such as sulfide solid electrolytes, and silicon itself experiences a volume expansion of ~300%. This leads to continuous deterioration of the interface between the silicon anode and the solid electrolyte, hindering interfacial ion and electron transport and increasing irreversible lithium loss. Ultimately, this results in poor overall electrochemical performance of silicon-based anodes, including low cycle stability, rate performance, and coulombic efficiency.

[0003] To address the above problems, traditional technologies mainly use the following methods: (1) carbon coating modification, but carbon coating introduces a conductive network, which intensifies the side reactions between the silicon-based anode and the solid electrolyte; (2) mixing silicon, solid electrolyte and conductive agent in a specific ratio to prepare a composite electrode, but this method usually intensifies the side reactions, and reducing the proportion of active material will affect the battery capacity; (3) developing new solid electrolytes to improve the side reaction problem, but the development of new solid electrolyte systems is not yet mature and there are many uncertainties; (4) constructing a lithium-silicon alloy system, but when the lithium content of the lithium-silicon alloy is too high, there are safety hazards such as lithium plating and short circuit. Summary of the Invention

[0004] Based on this, it is necessary to provide a silicon-based composite material and its preparation method, a negative electrode sheet, and an all-solid-state battery to address the above problems. The silicon-based composite material prepared by the method described above can effectively suppress interfacial side reactions and enhance the structural stability of the material, thereby synergistically improving the comprehensive electrochemical performance of the all-solid-state battery, such as rate performance, cycle stability, and coulombic efficiency.

[0005] A method for preparing a silicon-based composite material includes the following steps:

[0006] Silicon powder was mixed with a layered metal oxide halide under an inert atmosphere and then ball-milled, followed by a solid-phase reaction to obtain silicon-based powder.

[0007] Under an inert atmosphere, the silicon-based powder is mixed with a metal halide and then ball-milled. The mixture is then subjected to a halogenation reaction in a halogenation reaction gas environment to obtain a silicon-based composite material. The metal halide contains metal ions with a radius of 40 pm-60 pm and a valence greater than or equal to trivalent.

[0008] In one embodiment, the silicon powder has a particle size of 40 nm-5 μm;

[0009] And / or, the layered metal oxyhalide is selected from at least one of SbOCl, BiOCl or VOCl3;

[0010] And / or, the mass ratio of the silicon powder to the layered metal oxyhalide is 1:0.01-1:0.5.

[0011] In one embodiment, during the step of mixing the silicon powder with the layered metal oxyhalide, an acidic compound is also added to adjust the pH to 5-6.

[0012] And / or, in the step of ball milling the silicon powder with the layered metal oxyhalide, the ball milling time is 2h-6h.

[0013] In one embodiment, the solid-phase reaction is carried out at a temperature of 200°C-600°C for a reaction time of 5 hours or more.

[0014] And / or, the solid-phase reaction is carried out under sealed conditions.

[0015] In one embodiment, the metal halide is selected from at least one of AlCl3, FeCl3, or SnCl4;

[0016] And / or, the mass ratio of the silicon-based powder to the metal halide is 1:0.01-1:0.5.

[0017] In one embodiment, in the step of ball milling the silicon-based powder with the metal halide, the ball milling time is 2h-6h.

[0018] In one embodiment, in the step of carrying out the halogenation reaction in the halogenation reaction gas environment, the halogenation reaction gas is selected from at least one of a mixture of NF3 and Ar or NH4Cl.

[0019] And / or, the temperature of the halogenation reaction is greater than or equal to 800°C, and the holding time is 2h-6h.

[0020] A silicon-based composite material is prepared using the method described above for preparing silicon-based composite materials.

[0021] A negative electrode includes a current collector and a negative electrode active material layer disposed on the surface of the current collector, wherein the active material in the negative electrode active material layer is selected from the silicon-based composite materials described above.

[0022] An all-solid-state battery, wherein the all-solid-state battery uses the negative electrode as described above.

[0023] In the preparation method of this invention, silicon powder is first reacted with a layered metal oxyhalide to form a flexible inner layer of a "Si-O-metal-halogen" network. Then, it further reacts with the metal halide to generate a rigid outer layer of "Si-halogen," thereby constructing a "flexible-rigid" gradient bonding interface on the silicon surface. In this gradient bonding interface, the flexible "Si-O-metal-halogen" network of the inner layer not only utilizes the elastic deformation of the oxygen bridging structure to achieve stress buffering, suppressing silicon volume expansion and enhancing material structural stability, but also allows oxygen vacancies and halogen ion channels to synergistically improve lithium-ion transport efficiency. The outer "Si-halogen" layer, through strong covalent bonds, fixes the active sites on the silicon surface, suppressing side reactions. Simultaneously, this gradient bonding interface does not affect conductivity, thus ensuring the proportion of silicon-based composite material used in the negative electrode, thereby guaranteeing battery capacity. Therefore, the silicon-based composite material prepared using this invention can synergistically improve the rate performance, cycle stability, and coulombic efficiency of all-solid-state batteries, resulting in improved overall electrochemical performance. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a SEM image of the silicon-based composite material prepared in Example 7 of the present invention. Detailed Implementation

[0026] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all the related listed items.

[0028] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0029] The method for preparing silicon-based composite materials provided by the present invention includes the following steps:

[0030] S1, under an inert atmosphere, silicon powder is mixed with a layered metal oxide halide and then ball-milled, followed by a solid-phase reaction to obtain silicon-based powder;

[0031] S2, Under an inert atmosphere, the silicon-based powder is mixed with a metal halide and then ball-milled, followed by a halogenation reaction in a halogenation reaction gas environment to obtain a silicon-based composite material, wherein the metal ions in the metal halide have a radius of 40 pm-60 pm and a valence greater than or equal to trivalent.

[0032] Metal oxyhalides include aluminum-based oxyhalides such as lithium aluminum oxychloride, sodium aluminum oxybromide, and silver aluminum oxychloride; rare-earth oxyhalides such as yttrium oxychloride, yttrium oxybromide, and lutetium oxybromide; and transition metal oxyhalides such as antimony oxychloride, bismuth oxychloride, and vanadium oxychloride. In step S1 of this invention, the reaction of silicon powder with a layered metal oxyhalide can form a flexible "Si-O-metal-halogen" network layer. This not only utilizes the elastic deformation of the oxygen bridging structure to achieve stress buffering, suppressing the volume expansion of silicon and enhancing the structural stability of the material, but also allows the oxygen vacancies and halogen ion channels to synergistically improve lithium-ion transport efficiency, resulting in an ionic conductivity greater than 1×10⁻⁶. -4 S / cm.

[0033] Optionally, the layered metal oxyhalides include at least one of SbOCl, BiOCl, or VOCl3.

[0034] To optimize the material structure and electrochemical behavior and significantly improve battery performance, the particle size of the silicon powder can be optionally controlled within the range of 40nm-5μm, and can be selected as any point value or any range between 40nm, 100nm, 500nm, 1μm, 3μm or 5μm.

[0035] Optionally, the mass ratio of silicon powder to layered metal oxyhalides is preferably controlled at 1:0.05-1:0.1. This effectively constrains the volume change of silicon without causing excessive electrode density due to excessive addition, thus balancing energy density and cycle stability.

[0036] Since layered metal oxyhalides are sensitive to moisture and oxygen in the air, in order to prevent the layered metal oxyhalides from hydrolyzing or oxidizing, the step of mixing silicon powder with the layered metal oxyhalides and ball milling them is carried out under an inert gas, such as argon or nitrogen.

[0037] Optionally, in the step of mixing the silicon powder with the layered metal oxyhalide, an acidic compound is added to adjust the pH to 5-6. This not only maintains the activity of the layered metal oxyhalide, preventing premature decomposition or deactivation, but also activates the surface chemical properties of the silicon powder, promoting easier redox reactions between the layered metal oxyhalide and the silicon powder surface. To avoid the introduction of other anions, the acidic compound is preferably a halogen-containing compound, such as hydrochloric acid.

[0038] Optionally, in the step of ball milling after mixing silicon powder with layered metal oxyhalides, the ball milling time is preferably 2h-6h, which can be any value of 2h, 4h or 6h or any range between the two. This allows the two to react more fully and the layered metal oxyhalides to uniformly coat the surface of the silicon powder.

[0039] Since layered metal oxyhalides are sensitive to moisture and oxygen in the air, during solid-state reactions, in order to prevent hydrolysis or oxidation of the layered metal oxyhalides and reduce coating defects caused by halogen volatilization, the solid-state reaction is preferably carried out under sealed conditions. The temperature is preferably 200℃-600℃, and can be any value of 200℃, 300℃, 400℃ or 600℃ or any range between two. The reaction time is greater than or equal to 5h, for example 5h, 6h, 7h, and more preferably 6h-8h.

[0040] Metal halides include transition metal halides such as ferric chloride, tin chloride, magnesium chloride, copper chloride, ferric bromide, tin bromide, magnesium bromide, copper bromide, ferric iodide, tin iodide, magnesium iodide, and copper iodide, as well as rare earth halides such as lanthanum chloride and cerium chloride. In step S2 of this invention, a metal halide with a metal ion radius of 40 pm-60 pm and a valence greater than or equal to trivalent is reacted with silicon-based powder to generate a rigid "Si-halogen" layer. This rigid layer can cooperate with the flexible "Si-O-metal-halogen" network layer formed in step S1 to suppress the volume expansion of silicon and enhance the structural stability of the material. Moreover, the covalent bond energy of the "Si-halogen" rigid layer is ~452 kJ / mol, and the strong covalent bonds can fix the active sites on the silicon surface and suppress the occurrence of side reactions.

[0041] Therefore, this invention, by constructing a "flexible-rigid" gradient bonding interface on the silicon surface, not only suppresses silicon volume expansion and enhances material structural stability, but also improves the electrochemical compatibility of the interface and suppresses side reactions. Simultaneously, this gradient bonding interface is not an inert interface and does not affect conductivity, thus ensuring the proper proportion of silicon-based composite materials when used in negative electrodes. Furthermore, the silicon-based composite material prepared using this invention can synergistically improve the overall electrochemical performance of all-solid-state batteries, including rate performance, cycle stability, and coulombic efficiency.

[0042] Alternatively, the metal halide includes at least one of AlCl3, FeCl3, or SnCl4.

[0043] To prevent the metal halide from deliquescing in the air and affecting the coating effect, the step of mixing the silicon-based powder with the metal halide and ball milling is carried out under an inert gas, which can be selected from nitrogen, argon, etc.

[0044] Optionally, in the step of ball milling the silicon-based powder with the metal halide, the ball milling time is preferably 2h-6h, which can be any value of 2h, 3h, 4h or 6h or any range between two, so that the two can react more fully and the metal halide can be uniformly coated on the surface of the silicon-based powder.

[0045] Optionally, the mass ratio of the silicon-based powder to the metal halide is 1:0.05-1:0.1, which can further stabilize the structure of the composite material and also take into account the electrochemical performance of the composite material.

[0046] Optionally, in the step of carrying out the halogenation reaction in the halogenation reaction gas environment, the method of using the halogenation reaction gas is not particularly limited. It can be introduced before the reaction, or it can be introduced continuously or intermittently during the reaction. The temperature of the halogenation reaction is preferably greater than or equal to 800°C, such as 850°C, 900°C or 1000°C, and more preferably 850°C-950°C. The holding time is preferably 2h-6h, and can be selected as any value among 2h, 3h, 4h or 6h or any range between two, so that the halogenation reaction gas can participate in the reaction more fully.

[0047] Optionally, the halogenation reaction gas is preferably a mixture of NF3 and Ar or at least one of NH4Cl gas. This allows for a highly uniform and strongly constrained halide coating layer, providing passivation and ion conduction functions, making it more suitable for long-cycle applications. The synergistic application of both can further optimize the electrochemical performance of silicon-based anodes.

[0048] The present invention also provides a silicon-based composite material, which is prepared using the method for preparing the silicon-based composite material.

[0049] The present invention also provides a negative electrode sheet, comprising a current collector and a negative electrode active material layer disposed on the surface of the current collector, wherein the active material in the negative electrode active material layer is selected from the silicon-based composite material.

[0050] The present invention also provides an all-solid-state battery, wherein the all-solid-state battery uses the aforementioned negative electrode. Preferably, the solid electrolyte of the all-solid-state battery is a sulfide solid electrolyte.

[0051] The technical solution of the present invention will be further described below through specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without specified manufacturers are all commercially available conventional products.

[0052] Example 1

[0053] Under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with BiOCl at a mass ratio of 1:0.02. Dilute hydrochloric acid was added to adjust the pH to 6, and the mixture was ball-milled for 4 hours. Then, under sealed conditions, the mixture was heated to 400°C and reacted for 6 hours. After cooling, silicon-based powder was obtained.

[0054] Silicon-based powder was mixed with FeCl3 in an argon atmosphere at a mass ratio of 1:0.02. The mixture was ball-milled for 4 hours, and then NH4Cl gas was introduced. The mixture was reacted at 800°C for 3 hours. After cooling, a silicon-based composite material was obtained.

[0055] Take 990 mg of the prepared silicon-based composite material and 10 mg of polytetrafluoroethylene, disperse them in 2 mL of N-methylpyrrolidone solvent, stir evenly, coat the mixture onto copper foil, and then vacuum dry at 50 °C to obtain a loading of 3 mg / cm³. 2 The negative electrode plate.

[0056] High-voltage lithium cobalt oxide / NCM ternary cathode material was mixed with solid electrolyte Li3InCl6 at a mass ratio of 7:3, ground uniformly, and used as the cathode. Li6PS5Cl was used as the solid electrolyte, and the prepared anode sheet was matched. The N / P ratio of the battery was controlled to be 1.1, and the electrochemical performance was tested in the range of 2.5V-4.3V.

[0057] Example 2

[0058] The difference between Example 2 and Example 1 is that: under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with BiOCl at a mass ratio of 1:0.05, dilute hydrochloric acid was added to adjust the pH to 6, and the mixture was ball-milled for 4 hours. Then, under sealed conditions, the mixture was heated to 400°C and reacted for 6 hours. After cooling, silicon-based powder was obtained.

[0059] Silicon-based powder was mixed with FeCl3 in an argon atmosphere at a mass ratio of 1:0.05. The mixture was ball-milled for 4 hours, and then NH4Cl gas was introduced. The mixture was reacted at 800°C for 3 hours. After cooling, a silicon-based composite material was obtained.

[0060] Example 3

[0061] The difference between Example 3 and Example 1 is that: under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with BiOCl at a mass ratio of 1:0.1, dilute hydrochloric acid was added to adjust the pH to 6, and the mixture was ball-milled for 4 hours. Then, under sealed conditions, the mixture was heated to 400°C and reacted for 6 hours. After cooling, silicon-based powder was obtained.

[0062] Silicon-based powder was mixed with FeCl3 in an argon atmosphere at a mass ratio of 1:0.1. The mixture was ball-milled for 4 hours, and then NH4Cl gas was introduced. The mixture was reacted at 800°C for 3 hours. After cooling, a silicon-based composite material was obtained.

[0063] Example 4

[0064] The difference between Example 4 and Example 1 is that: under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with BiOCl at a mass ratio of 1:0.2, dilute hydrochloric acid was added to adjust the pH to 6, and the mixture was ball-milled for 4 hours. Then, under sealed conditions, the mixture was heated to 400°C and reacted for 6 hours. After cooling, silicon-based powder was obtained.

[0065] Silicon-based powder was mixed with FeCl3 in an argon atmosphere at a mass ratio of 1:0.2. The mixture was ball-milled for 4 hours, and then NH4Cl gas was introduced. The mixture was reacted at 800°C for 3 hours. After cooling, a silicon-based composite material was obtained.

[0066] Example 5

[0067] The difference between Example 5 and Example 1 is that: under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with VOCl3 at a mass ratio of 1:0.05, dilute hydrochloric acid was added to adjust the pH to 5, and the mixture was ball-milled for 4 hours. Then, under sealed conditions, the mixture was heated to 400°C and reacted for 6 hours. After cooling, silicon-based powder was obtained.

[0068] Silicon-based powder was mixed with AlCl3 in an argon atmosphere at a mass ratio of 1:0.05. The mixture was ball-milled for 4 hours, and then NH4Cl gas was introduced. The mixture was reacted at 800°C for 3 hours. After cooling, a silicon-based composite material was obtained.

[0069] Example 6

[0070] The difference between Example 6 and Example 1 is that: under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with VOCl3 at a mass ratio of 1:0.1, dilute hydrochloric acid was added to adjust the pH to 5, and the mixture was ball-milled for 4 hours. Then, under sealed conditions, the mixture was heated to 400°C and reacted for 8 hours. After cooling, silicon-based powder was obtained.

[0071] Silicon-based powder was mixed with AlCl3 in an argon atmosphere at a mass ratio of 1:0.05. The mixture was ball-milled for 4 hours, and then NH4Cl gas was introduced. The mixture was reacted at 800°C for 3 hours. After cooling, a silicon-based composite material was obtained.

[0072] Example 7

[0073] The difference between Example 7 and Example 1 is that: under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with VOCl3 at a mass ratio of 1:0.1, dilute hydrochloric acid was added to adjust the pH to 6, and the mixture was ball-milled for 4 hours. Then, under sealed conditions, the mixture was heated to 400°C and reacted for 8 hours. After cooling, silicon-based powder was obtained.

[0074] Under an argon atmosphere, silicon-based powder was mixed with AlCl3 at a mass ratio of 1:0.1. The mixture was ball-milled for 4 hours, then NH4Cl gas was introduced, and the reaction was carried out at 800℃ for 3 hours. After cooling, the mixture was obtained as shown in the figure. Figure 1 The silicon-based composite material shown.

[0075] Example 8

[0076] The difference between Example 8 and Example 1 is that: under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with SbOCl at a mass ratio of 1:0.1, dilute hydrochloric acid was added to adjust the pH to 6, and the mixture was ball-milled for 4 hours. Then, under sealed conditions, the mixture was heated to 400°C and reacted for 8 hours. After cooling, silicon-based powder was obtained.

[0077] Silicon-based powder was mixed with AlCl3 in an argon atmosphere at a mass ratio of 1:0.1. The mixture was ball-milled for 4 hours, and then NH4Cl gas was introduced. The mixture was reacted at 800°C for 3 hours. After cooling, a silicon-based composite material was obtained.

[0078] Example 9

[0079] The difference between Example 9 and Example 1 is that: under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with SbOCl at a mass ratio of 1:0.1, dilute hydrochloric acid was added to adjust the pH to 6, and the mixture was ball-milled for 4 hours. Then, under sealed conditions, the mixture was heated to 400°C and reacted for 8 hours. After cooling, silicon-based powder was obtained.

[0080] Silicon-based powder was mixed with SnCl4 in an argon atmosphere at a mass ratio of 1:0.1. The mixture was ball-milled for 4 hours, and then NH4Cl gas was introduced. The mixture was reacted at 800°C for 3 hours. After cooling, a silicon-based composite material was obtained.

[0081] Comparative Example 1

[0082] The difference between Comparative Example 1 and Example 1 is as follows: 990 mg of silicon powder and 10 mg of polytetrafluoroethylene were dispersed in 2 mL of N-methylpyrrolidone solvent, stirred evenly, coated onto copper foil, and then vacuum dried at 50 °C to obtain a loading of 3 mg / cm³. 2 The negative electrode plate.

[0083] Comparative Example 2

[0084] The difference between Comparative Example 2 and Example 1 is that: under an argon atmosphere, VOCl3 and AlCl3 were mixed to form a mixed metal powder, and then silicon powder and the mixed metal powder were mixed evenly at a ratio of 1:0.1 and ball-milled for 4 hours to obtain a silicon-based composite material.

[0085] Comparative Example 3

[0086] The difference between Comparative Example 3 and Example 1 is that: under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with AlCl3 at a mass ratio of 1:0.1, ball milled for 4 h, then NH4Cl gas was introduced, and the mixture was reacted at 800 °C for 3 h. After cooling, silicon-based powder was obtained.

[0087] Under an argon atmosphere, silicon-based powder was mixed with VOCl3 at a mass ratio of 1:0.1. Dilute hydrochloric acid was added to adjust the pH to 6, and the mixture was ball-milled for 4 hours to obtain a silicon-based composite material.

[0088] Comparative Example 4

[0089] The difference between Comparative Example 4 and Example 1 is that: under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with VOCl3 at a mass ratio of 1:0.1, dilute hydrochloric acid was added to adjust the pH to 6, and the mixture was ball-milled for 4 hours to obtain silicon-based powder.

[0090] Silicon-based powder was mixed with AlCl3 in an argon atmosphere at a mass ratio of 1:0.1. The mixture was ball-milled for 4 hours, and then NH4Cl gas was introduced. The mixture was reacted at 800°C for 3 hours. After cooling, a silicon-based composite material was obtained.

[0091] Comparative Example 5

[0092] The difference between Comparative Example 5 and Example 1 is that: under an argon atmosphere, silicon powder with a particle size of 40 nm was mixed with VOCl3 at a mass ratio of 1:0.1, dilute hydrochloric acid was added to adjust the pH to 6, and the mixture was ball-milled for 4 hours. Then, under sealed conditions, the mixture was heated to 400°C and reacted for 8 hours. After cooling, silicon-based powder was obtained.

[0093] Silicon-based powder was mixed with FeCl3 in an argon atmosphere at a mass ratio of 1:0.1 and ball-milled for 4 hours to obtain a silicon-based composite material.

[0094] Comparative Example 6

[0095] The difference between Comparative Example 6 and Example 1 is that YOCl is used instead of BiOCl.

[0096] Comparative Example 7

[0097] The difference between Comparative Example 7 and Example 1 is that MgCl2 is used instead of FeCl3.

[0098] The electrochemical performance of the negative electrode sheets prepared in Examples 1-9 and Comparative Examples 1-7 was tested, and the results are shown in Table 1.

[0099] Table 1

[0100]

[0101] As shown in Table 1, the negative electrode prepared using the method of this application significantly improves the rate performance, cycle stability and coulombic efficiency of the all-solid-state battery while maintaining a high specific capacity (greater than 2500 mAh / g).

[0102] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a silicon-based composite material, characterized in that, Includes the following steps: Silicon powder was mixed with a layered metal oxide halide under an inert atmosphere and then ball-milled, followed by a solid-phase reaction to obtain silicon-based powder. Under an inert atmosphere, the silicon-based powder is mixed with a metal halide and then ball-milled. The mixture is then subjected to a halogenation reaction in a halogenation reaction gas environment to obtain a silicon-based composite material. The metal halide contains metal ions with a radius of 40 pm-60 pm and a valence greater than or equal to trivalent.

2. The method for preparing the silicon-based composite material according to claim 1, characterized in that, The silicon powder has a particle size of 40nm-5μm; And / or, the layered metal oxyhalide is selected from at least one of SbOCl, BiOCl or VOCl3; And / or, the mass ratio of the silicon powder to the layered metal oxyhalide is 1:0.01-1:0.

5.

3. The method for preparing the silicon-based composite material according to claim 1, characterized in that, In the step of mixing the silicon powder with the layered metal oxyhalide, an acidic compound is also added to adjust the pH to 5-6; And / or, in the step of ball milling the silicon powder with the layered metal oxyhalide, the ball milling time is 2h-6h.

4. The method for preparing the silicon-based composite material according to claim 1, characterized in that, The solid-phase reaction is carried out at a temperature of 200℃-600℃ for a time of 5 hours or more. And / or, the solid-phase reaction is carried out under sealed conditions.

5. The method for preparing the silicon-based composite material according to claim 1, characterized in that, The metal halide is selected from at least one of AlCl3, FeCl3 or SnCl4; And / or, the mass ratio of the silicon-based powder to the metal halide is 1:0.01-1:0.

5.

6. The method for preparing the silicon-based composite material according to claim 1, characterized in that, In the step of ball milling the silicon-based powder with the metal halide, the ball milling time is 2h-6h.

7. The method for preparing the silicon-based composite material according to claim 1, characterized in that, In the step of carrying out the halogenation reaction in the halogenation reaction gas environment, the halogenation reaction gas is selected from at least one of a mixture of NF3 and Ar or NH4Cl; And / or, the temperature of the halogenation reaction is greater than or equal to 800°C, and the holding time is 2h-6h.

8. A silicon-based composite material, characterized in that, It is prepared using the method for preparing silicon-based composite materials as described in any one of claims 1-7.

9. A negative electrode sheet, characterized in that, It includes a current collector and a negative electrode active material layer disposed on the surface of the current collector, wherein the active material in the negative electrode active material layer is selected from the silicon-based composite material as described in claim 8.

10. An all-solid-state battery, characterized in that, The all-solid-state battery uses the negative electrode as described in claim 9.

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