Silicon-carbon negative electrode material, and preparation method therefor and use thereof

Abstract

Provided in the present application are a silicon-carbon negative electrode material, and a preparation method therefor and the use thereof. The negative electrode material comprises a porous carbon substrate, and the porous carbon substrate comprises a carbon layer arranged on the surface thereof; pores of the porous carbon substrate are filled with a silicon-carbon material and a carbon material; and the carbon material comprises carbon nanotubes and graphene, wherein the carbon nanotubes and the graphene are compounded on the surface of the silicon-carbon material particles and / or among the silicon-carbon material particles.

Description

A silicon-carbon negative electrode material and its preparation method and application

[0001] This application claims priority to Chinese patent application No. 202410095258.8 filed on January 23, 2024, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to, but is not limited to, the field of battery technology, and in particular to a silicon-carbon negative electrode material and a preparation method and application thereof. Background Art

[0003] Silicon-based materials have the highest capacity among anode materials and are considered one of the most promising anode materials for lithium-ion batteries. However, their cycling stability is poor due to the large volume expansion (>300%) caused by the alloying reaction between silicon and lithium during charge and discharge, which leads to particle pulverization and deactivation. Technical Solutions

[0004] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0005] The present application is made in view of the above-mentioned problems, and its purpose is to provide a silicon-carbon negative electrode material having excellent cycle performance.

[0006] This application also provides a method for preparing the above-mentioned silicon-carbon negative electrode material.

[0007] This application also provides applications of the above-mentioned silicon-carbon negative electrode material.

[0008] Specifically as follows, the first aspect of the present application provides a silicon-carbon negative electrode material, including a porous carbon matrix;

[0009] The porous carbon matrix includes a carbon layer disposed on the surface;

[0010] The pores of the porous carbon matrix are filled with silicon-carbon material and carbon material;

[0011] The mass ratio of the silicon-carbon material to the carbon material is 30:1 to 40:1; the carbon material includes carbon nanotubes and graphene;

[0012] The mass ratio of the carbon nanotubes to the graphene is 2:1 to 5:1;

[0013] The carbon nanotubes and graphene are compounded on the surface of the silicon-carbon material and / or between the silicon-carbon materials.

[0014] In the present application, a carbon layer is provided on the surface of the porous carbon matrix of the silicon-carbon negative electrode material, wherein the inner carbon layer of the porous carbon matrix is ​​used to adapt to volume changes, and the outer carbon layer is used to stabilize the electrolyte interface; there is a mechanical and chemical synergistic effect between the carbon layers on the inner and outer surfaces, so that the final silicon-carbon negative electrode material has both high density and crack resistance; at the same time, silicon-carbon materials, carbon nanotubes and graphene are also introduced into the pores; wherein the carbon nanotubes and the silicon-carbon materials are in point contact or line contact, and the graphene and the silicon-carbon materials are in surface contact; the carbon nanotubes, graphene and silicon-carbon materials form a point-line-surface conductive network, thereby optimizing the electronic conductivity network and improving the conductive performance.

[0015] At the same time, carbon nanotubes and graphene filled in the pores can support the silicon-carbon material, similar to an internal shrapnel; and graphene and carbon nanotubes have excellent flexibility, which can play a good buffering role during the volume expansion of the silicon-carbon material, and can also alleviate the point contact failure caused by the volume expansion of the silicon-carbon material, thereby greatly alleviating the performance degradation of the silicon-carbon material caused by the volume expansion, thus forming a silicon-carbon negative electrode material with good conductivity, excellent cycle performance and high capacity.

[0016] Controlling the mass ratio of silicon-carbon material to carbon material within a certain range can further improve the electrical performance of silicon-carbon negative electrode materials;

[0017] Controlling the mass ratio of carbon nanotubes and graphene within a certain range can further improve the electrical properties of silicon-carbon negative electrode materials.

[0018] In one embodiment, the carbon nanotube is at least one of a single-arm carbon nanotube or a multi-arm carbon nanotube.

[0019] Single-arm carbon nanotubes and multi-arm carbon nanotubes have good flexibility and mechanical properties; they can increase the conduction rate of electrons and improve conductivity; at the same time, single-arm carbon nanotubes can also connect silicon-carbon materials, increase the connection strength between particles, and form a conductive network to improve conductivity.

[0020] In one embodiment, the porosity of the porous carbon matrix is ​​15% to 25%.

[0021] If the porosity of the porous carbon matrix is ​​too small, the amount of silicon-carbon material and carbon material that can be filled is limited, so that the capacity improvement rate of the silicon-carbon negative electrode material is limited, and the infiltration amount of the electrolyte is limited, thereby affecting the electrical properties of the silicon-carbon negative electrode material; and if the porosity of the porous carbon matrix is ​​too large, the filling amount of silicon-carbon material particles increases, and the expansion force received by the porous carbon matrix during the charging and discharging process increases, thereby affecting the structural stability of the porous carbon matrix; therefore, controlling the porosity of the porous carbon matrix within a certain range is conducive to further alleviating the deformation and pulverization of the silicon-carbon material, thereby further improving the electrochemical performance of the silicon-carbon negative electrode material.

[0022] In one embodiment, the pores in the porous carbon matrix have a diameter of 10 nm to 55 nm.

[0023] When the pore size is smaller, it becomes more difficult to fill the silicon-carbon material and the carbon material; when the pore size is larger, the bonding tightness between the silicon-carbon material and the carbon material decreases, which has a certain impact on the construction of the conductive network; therefore, controlling the pore size within a certain range is conducive to further improving the electrochemical performance of the silicon-carbon negative electrode material.

[0024] In one embodiment, the particle size of the silicon-carbon material is 4 nm to 15 nm.

[0025] If the particle size of the silicon-carbon material is too small, the deposition process of the silicon-carbon material becomes more difficult; if the particle size of the silicon-carbon material is too large, the ability of the silicon-carbon material to squeeze the carbon material becomes greater, and the carbon material is in a squeezed state for a long time, resulting in greater stress on the porous carbon matrix; and during the cycle, the silicon-carbon material will expand, and if its particle size is too large, the expansion force will be directly applied to the porous carbon matrix, thereby affecting the structural stability of the silicon-carbon negative electrode material; therefore, controlling the silicon-carbon material within a certain range is conducive to further improving the structural stability of the silicon-carbon negative electrode material, thereby obtaining a silicon-carbon negative electrode material with excellent electrochemical performance.

[0026] In one embodiment, the carbon layer has a thickness of 1 nm to 3 nm.

[0027] If the thickness of the carbon layer is too small, the uniformity of the inner and outer surfaces of the porous carbon matrix will be poor; if the thickness of the carbon layer is too large, it will affect the deposition of silicon-carbon materials and carbon materials; therefore, controlling the thickness of the carbon layer within a certain range will help further improve the electrochemical performance of silicon-carbon negative electrode materials.

[0028] In one embodiment, the volume ratio of the graphene to the pores of the porous carbon matrix is ​​0.1:100 to 2:100.

[0029] In one embodiment, the volume ratio of the carbon nanotubes to the pores of the porous carbon matrix is ​​3:100 to 15:100.

[0030] In one embodiment, the volume ratio of the silicon-carbon material to the pores of the porous carbon matrix is ​​0.1:100 to 20:100.

[0031] Controlling the amount of graphene, carbon nanotubes and silicon-carbon materials within a certain range can give full play to the advantages of graphene, carbon nanotubes and silicon-carbon materials to construct a conductive network with excellent conductive properties; at the same time, it can also greatly alleviate the volume effect of silicon-carbon materials, thereby further improving the electrochemical performance of silicon-carbon negative electrode materials.

[0032] The second aspect of the present application provides a method for preparing the above-mentioned silicon-carbon negative electrode material, comprising the following steps:

[0033] carbonizing the carbon matrix to obtain a porous carbon matrix containing a carbon layer;

[0034] A carbon material and a silicon-carbon material are sequentially deposited in the pores of the porous carbon matrix of the carbon-containing layer.

[0035] The preparation method of the present application comprises the following steps: carbonizing a carbon matrix to form a carbon layer on the surface of the carbon matrix; then sequentially forming carbon nanotubes and graphene (carbon material) on the surface of the carbon layer; then forming silicon-carbon material in the conductive network formed by the carbon nanotubes and graphene to construct a conductive network of points, lines and surfaces; at the same time, the carbon nanotubes, graphene and carbon-silicon particles grown directly from the porous carbon matrix containing the carbon layer have closer connections internally, can play a better conductive role, and can also strengthen internal connections.

[0036] In one embodiment, the carbonization temperature is 600°C to 800°C.

[0037] By carbonizing the carbon matrix, a dense carbon layer is formed on both the outer and inner surfaces of the carbon matrix, thereby optimizing the interface of the carbon matrix and improving the structural stability.

[0038] In one embodiment, a first carrier gas is selected during the carbonization process, and the first carrier gas is composed of a hydrocarbon compound and a protective gas.

[0039] In one embodiment, the volume fraction of hydrocarbon compounds in the first carrier gas is 50% to 60%.

[0040] By controlling the carrier gas during the carbonization process, the growth quality of the carbon layer is further improved, and the stability of the carbon layer is further improved.

[0041] In one embodiment, a second carrier gas is selected during the carbon material deposition process; the second carrier gas includes a hydrocarbon compound and a protective gas.

[0042] In one embodiment, the volume fraction of hydrocarbon compounds in the second carrier gas is 10% to 20%.

[0043] In one embodiment, the carbon material is deposited at a temperature of 150°C to 250°C.

[0044] In one embodiment, the carbon material is deposited for 1.5 hours to 2.5 hours.

[0045] During the carbon material deposition process, carbon nanotubes are first formed on the surface of the porous carbon matrix containing the carbon layer, and then graphene is further formed as the deposition time is delayed. By controlling the deposition parameters, the ratio of carbon nanotubes to graphene is controlled, thereby further improving the performance of the silicon-carbon negative electrode material.

[0046] In one embodiment, a third carrier gas is selected for the silicon-carbon material deposition, and the third carrier gas includes a hydrocarbon compound, a silane compound, and a protective gas.

[0047] In one embodiment, the volume fraction of hydrocarbon compounds in the third carrier gas is 10% to 20%.

[0048] In one embodiment, the volume fraction of the silane compound in the third carrier gas is 20% to 40%.

[0049] In one embodiment, the silicon-carbon material is deposited at a temperature of 150° C. to 250° C.

[0050] In one embodiment, the silicon-carbon material is deposited for 1.5 hours to 2.5 hours.

[0051] By controlling the deposition parameters of the silicon-carbon material, the mass fraction of silicon in the silicon-carbon material and the size of the silicon-carbon material can be regulated, thereby producing a silicon-carbon negative electrode material with excellent performance.

[0052] In one embodiment, the silicon-carbon material is subjected to pressurization and homogenization treatments after deposition.

[0053] After pressure treatment, the material is homogenized and its stability is further improved.

[0054] In one embodiment, the pressure of the pressurization treatment is 900 kPa to 1000 kPa.

[0055] In one embodiment, the temperature of the pressurization treatment is 900° C. to 1100° C.

[0056] By pressurizing the composite material at the above-mentioned pressure and temperature, the stability of the material is further improved, thereby producing a silicon-carbon negative electrode material with excellent stability.

[0057] In one embodiment, the homogenization is ultrasonication.

[0058] Through ultrasonic treatment, the uniformity of the silicon-carbon negative electrode material is further improved; at the same time, ultrasonic treatment will separate the carbon material attached to the outer surface and the silicon-carbon material from the outer surface carbon layer.

[0059] A third aspect of the present application provides an electrode sheet, comprising the silicon-carbon negative electrode material of the first aspect of the present application;

[0060] And / or, the silicon-carbon negative electrode material prepared in the second aspect of the present application.

[0061] A fourth aspect of the present application provides a battery pack, comprising the silicon-carbon negative electrode material of the first aspect of the present application;

[0062] and / or, the silicon-carbon negative electrode material prepared according to the second aspect of the present application;

[0063] And / or, the electrode sheet of the third aspect of the present application.

[0064] In one embodiment, the silicon-carbon negative electrode material and / or electrode sheet is used to prepare a battery module.

[0065] In one embodiment, the silicon-carbon negative electrode material, electrode sheet and / or battery pack are used to manufacture an electrical device.

[0066] In one embodiment, the electrical device includes an electric vehicle.

[0067] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the embodiments of the present drawings or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present drawings. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0069] FIG1 is a schematic diagram of the cross-sectional structure of a silicon-carbon negative electrode material in an embodiment;

[0070] FIG2 is a schematic diagram of the cross-sectional structure of internal pores in the silicon-carbon negative electrode material in the embodiment.

[0071] Description of Figure Numbers:

[0072] 100. Outer carbon layer; 101. Porous carbon matrix; 102. Pores in porous carbon matrix; 103. Inner carbon layer; 104. Silicon-carbon material; 105. Graphene; 106. Carbon nanotubes.

[0073] The purpose, features and advantages of this drawing will be further described with reference to the accompanying drawings in conjunction with the embodiments. Modes for Carrying Out the Invention

[0074] Below, the embodiments of the silicon-carbon negative electrode material, its preparation method and application of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0075] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0076] Unless otherwise specified, all embodiments and some embodiments of the present application can be combined with each other to form new technical solutions.

[0077] Unless otherwise specified, all technical features and some technical features of this application can be combined with each other to form a new technical solution.

[0078] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0079] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0080] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0081] Lithium-ion batteries have excellent properties such as high energy density, low self-discharge, high operating voltage, long cycle life, no memory effect and no environmental pollution. They have been rapidly developed and have been widely used in various portable electronic devices such as mobile phones, digital cameras, and laptops.

[0082] There are still many problems to be solved in order to further improve the performance of lithium-ion batteries. For example, the widely used graphite carbon negative electrode material, although it has the advantages of being cheap, environmentally friendly, highly structurally stable and having intrinsic conductivity, has a low theoretical specific capacity, which limits its application in fields requiring high energy density and power density output. Replacing the traditional graphite negative electrode with a high-capacity material is the most promising way to achieve higher energy density lithium-ion batteries.

[0083] Silicon (Si), which reacts with lithium through alloying, is considered a viable alternative to graphite-based anode materials due to its high specific capacity (3592 mAh g⁻¹). However, Si undergoes severe structural degradation and solid electrolyte interface (SEI) instability due to large volume fluctuations during crystallization. This not only leads to particle fracture and loss of electrical contact with the electrode system, but also hinders the stable formation of the SEI layer, continuously exposing new surfaces of the material to the electrolyte; resulting in poor cycling performance of silicon anode materials.

[0084] To this end, an embodiment of the present application provides a silicon-carbon negative electrode material having excellent cycle performance.

[0085] A first aspect of an embodiment of the present application provides a silicon-carbon negative electrode material, comprising a porous carbon matrix;

[0086] The porous carbon matrix includes a carbon layer disposed on the surface;

[0087] The pores of the porous carbon matrix are filled with silicon-carbon material and carbon material;

[0088] The mass ratio of the silicon-carbon material to the carbon material is 30:1 to 40:1; the carbon material includes carbon nanotubes and graphene;

[0089] The mass ratio of the carbon nanotubes to the graphene is 2:1 to 5:1;

[0090] The carbon nanotubes and graphene are compounded on the surface of silicon-carbon material particles and / or between silicon-carbon material particles.

[0091] The silicon-carbon negative electrode material in the embodiment of the present application has at least the following beneficial effects:

[0092] In the embodiment of the present application, a carbon layer is provided on the surface of the porous carbon matrix of the silicon-carbon negative electrode material, wherein the inner carbon layer of the porous carbon matrix is ​​used to adapt to volume changes, and the outer carbon layer is used to stabilize the electrolyte interface; there is a mechanical and chemical synergistic effect between the carbon layers on the inner and outer surfaces, so that the final silicon-carbon negative electrode material has both high density and crack resistance; at the same time, silicon-carbon materials, carbon nanotubes and graphene are also introduced into the pores; wherein the carbon nanotubes and the silicon-carbon materials are in point contact or line contact, and the graphene and the silicon-carbon materials are in surface contact; the carbon nanotubes, graphene and silicon-carbon materials form a point-line-surface conductive network, thereby optimizing the electronic conductivity network and improving the conductive performance.

[0093] At the same time, carbon nanotubes and graphene filled in the pores can support the silicon-carbon material, similar to an internal shrapnel; and graphene and carbon nanotubes have excellent flexibility, which can play a good buffering role during the volume expansion of the silicon-carbon material, and can also alleviate the point contact failure caused by the volume expansion of the silicon-carbon material, thereby greatly alleviating the performance degradation of the silicon-carbon material caused by the volume expansion, thus forming a silicon-carbon negative electrode material with good conductivity, excellent cycle performance and high capacity.

[0094] That is, in the embodiment of the present application, the structure of the silicon-carbon negative electrode material is designed, a dense outer layer of carbon is used to stabilize the electrolyte interface, and an inner layer of carbon in a porous carbon matrix is ​​used to adapt to volume changes. The mechanical and chemical synergy between the two carbon layers with different structures enables the silicon-carbon material to have both high densification and crack resistance. In the embodiment of the present application, the silicon particles are replaced with silicon-carbon materials to reduce the volume expansion rate, thereby reducing the risk of contact failure or porous carbon matrix rupture due to volume expansion of silicon particles. In the embodiment of the present application, graphene, conductive carbon nanotubes, single-arm carbon nanotubes, etc. are introduced to optimize the electronic conductivity network, thereby improving the electron transport performance (whereas in an optional method, the volume expansion of silicon particles in the pore structure of the porous carbon matrix will cause electrical contact failure, further resulting in poor interface electron transport performance).

[0095] Controlling the mass ratio of silicon-carbon material to carbon material within a certain range can further improve the electrical performance of silicon-carbon negative electrode materials;

[0096] Controlling the mass ratio of carbon nanotubes and graphene within a certain range can further improve the electrical properties of silicon-carbon negative electrode materials.

[0097] In some embodiments, the carbon nanotube is at least one of a single-arm carbon nanotube or a multi-arm carbon nanotube.

[0098] Single-arm carbon nanotubes and multi-arm carbon nanotubes have good flexibility and mechanical properties; they can increase the conduction rate of electrons and improve conductivity; at the same time, single-arm carbon nanotubes can also connect silicon-carbon materials, increase the connection strength between particles, and form a conductive network to improve conductivity.

[0099] In some embodiments, the mass ratio of the silicon-carbon material to the carbon material is 35:1 to 40:1.

[0100] In some embodiments, the mass ratio of the silicon-carbon material to the carbon material is 35:1 to 39:1.

[0101] In some embodiments, the mass ratio of the silicon-carbon material to the carbon material is 35:1 to 37:1.

[0102] In some embodiments, the mass ratio of the carbon nanotubes to graphene is 3:1 to 5:1.

[0103] In some embodiments, the mass ratio of the carbon nanotubes to graphene is 3:1 to 4:1.

[0104] In some embodiments, the porous carbon matrix has a porosity of 15% to 25%.

[0105] If the porosity of the porous carbon matrix is ​​too small, the amount of silicon-carbon material and carbon material that can be filled is limited, so that the capacity improvement rate of the silicon-carbon negative electrode material is limited, and the infiltration amount of the electrolyte is limited, thereby affecting the electrical properties of the silicon-carbon negative electrode material; and if the porosity of the porous carbon matrix is ​​too large, the filling amount of silicon-carbon material particles increases, and the expansion force received by the porous carbon matrix during the charging and discharging process increases, thereby affecting the structural stability of the porous carbon matrix; therefore, controlling the porosity of the porous carbon matrix within a certain range is conducive to further alleviating the deformation and pulverization of the silicon-carbon material, thereby further improving the electrochemical performance of the silicon-carbon negative electrode material.

[0106] In some embodiments, the porous carbon matrix has a porosity of 20% to 25%.

[0107] In some embodiments, the pores in the porous carbon matrix have a pore size of 10 nm to 55 nm.

[0108] When the pore size is smaller, it becomes more difficult to fill the silicon-carbon material and the carbon material; when the pore size is larger, the bonding tightness between the silicon-carbon material and the carbon material decreases, which has a certain impact on the construction of the conductive network; therefore, controlling the pore size within a certain range is conducive to further improving the electrochemical performance of the silicon-carbon negative electrode material.

[0109] In some embodiments, the particle size of the silicon-carbon material is 4 nm to 15 nm.

[0110] If the particle size of the silicon-carbon material is too small, the deposition process of the silicon-carbon material becomes more difficult; if the particle size of the silicon-carbon material is too large, the ability of the silicon-carbon material to squeeze the carbon material becomes greater, and the carbon material is in a squeezed state for a long time, resulting in greater stress on the porous carbon matrix; and during the cycle, the silicon-carbon material will expand, and if its particle size is too large, the expansion force will be directly applied to the porous carbon matrix, thereby affecting the structural stability of the silicon-carbon negative electrode material; therefore, controlling the silicon-carbon material within a certain range is conducive to further improving the structural stability of the silicon-carbon negative electrode material, thereby obtaining a silicon-carbon negative electrode material with excellent electrochemical performance.

[0111] In some embodiments, the carbon layer has a thickness of 1 nm to 3 nm.

[0112] If the thickness of the carbon layer is too small, the uniformity of the inner and outer surfaces of the porous carbon matrix will be poor; if the thickness of the carbon layer is too large, it will affect the deposition of silicon-carbon materials and carbon materials; therefore, controlling the thickness of the carbon layer within a certain range will help further improve the electrochemical performance of silicon-carbon negative electrode materials.

[0113] In some embodiments, the volume ratio of the graphene to the pores of the porous carbon matrix is ​​0.1:100 to 2:100.

[0114] In some embodiments, the volume ratio of the carbon nanotubes to the pores of the porous carbon matrix is ​​3:100 to 15:100.

[0115] In some embodiments, the volume ratio of the silicon-carbon material to the pores of the porous carbon matrix is ​​0.1:100 to 20:100.

[0116] Controlling the amount of graphene, carbon nanotubes and silicon-carbon materials within a certain range can give full play to the advantages of graphene, carbon nanotubes and silicon-carbon materials to construct a conductive network with excellent conductive properties; at the same time, it can also greatly alleviate the volume effect of silicon-carbon materials, thereby further improving the electrochemical performance of silicon-carbon negative electrode materials.

[0117] In some embodiments, the graphene includes at least one of single-layer graphene, few-layer graphene, multi-layer graphene, and graphene microplatelets.

[0118] In some embodiments, the carbon nanotubes are interspersed and interwoven between the silicon-carbon materials.

[0119] This application further ensures the specific morphology and structure of the composite material, better alleviates the deformation and pulverization of the silicon-carbon material, improves the electron transmission performance, and thus improves the electrochemical performance.

[0120] In some embodiments, the carbon nanotubes are interspersed and interwoven between the silicon-carbon materials.

[0121] In some embodiments, the cross-sectional structure of the silicon-carbon negative electrode material is shown in Figures 1 to 2, including a porous carbon matrix 101;

[0122] The porous carbon substrate 101 includes a carbon layer disposed on the surface;

[0123] The carbon layer includes an outer layer of carbon 100;

[0124] The porous carbon matrix 101 further includes porous carbon matrix pores 102 disposed therein;

[0125] An inner layer of carbon 103 is provided on the pore walls of the porous carbon matrix pores 102;

[0126] The porous carbon matrix pores 102 are also filled with carbon material and silicon-carbon material particles 104;

[0127] The carbon material includes graphene 105 and carbon nanotubes 106;

[0128] The carbon nanotubes 106 and the graphene 105 are composited on the surface of the silicon-carbon material particles 104 and / or between the silicon-carbon material particles 104 .

[0129] A second aspect of the embodiments of the present application provides a method for preparing the above-mentioned silicon-carbon negative electrode material, comprising the following steps:

[0130] carbonizing the carbon matrix to obtain a porous carbon matrix containing a carbon layer;

[0131] A carbon material and a silicon-carbon material are sequentially deposited on the surface of the porous carbon matrix of the carbon-containing layer.

[0132] The preparation method of the present application performs a carbonization treatment on a carbon matrix to form a carbon layer on the surface of the carbon matrix through the carbonization treatment; then carbon nanotubes and graphene are formed in sequence on the surface of the carbon layer; then silicon-carbon material is formed in the conductive network formed by the carbon nanotubes and graphene to construct a conductive network of points, lines and surfaces; at the same time, the carbon nanotubes, graphene and carbon-silicon particles grown directly from the porous carbon matrix containing the carbon layer have closer connections inside, can play a better conductive role, and can also strengthen internal connections.

[0133] In some embodiments, the method for preparing the carbon matrix comprises the following steps:

[0134] The carbon source, the iron source, the auxiliary agent and water are mixed and concentrated, the solid-liquid separation is performed, and the solid phase is collected to obtain a precursor;

[0135] The precursor is calcined and then acid washed.

[0136] The carbon source, iron source, and auxiliary agent are mixed in water to achieve thorough mixing of the carbon source, iron source, and auxiliary agent, and to fully disperse the iron source in the carbon source. During the calcination process, the carbon source is converted into a carbon-based material, while the iron source is converted into elemental iron particles and dispersed in the carbon-based material. Through acid washing, the elemental iron is removed, forming voids in the carbon-based material, thereby producing a carbon matrix. At the same time, the iron source can also increase the degree of graphitization of the carbon matrix, thereby producing a carbon matrix with a high degree of graphitization.

[0137] In some embodiments, the solid content after concentration is 40% to 50%.

[0138] In some embodiments, the carbon source comprises a carbohydrate compound.

[0139] Sugars are widely available, which helps reduce production costs.

[0140] In some embodiments, the carbohydrate compound includes at least one of chitosan, sucrose, fructose, and glucose.

[0141] In some embodiments, the iron source is an iron salt.

[0142] In some embodiments, the iron salt includes at least one of ferric sulfate, ferric nitrate, ferric acetate, and ferric chloride.

[0143] The above iron salts have good solubility in water, which is conducive to the full mixing of the iron source and the sugar compound.

[0144] In some embodiments, the adjuvant comprises nitric acid.

[0145] In some embodiments, the mass ratio of the carbon source to the adjuvant is 1:4 to 3:4.

[0146] In some embodiments, the mass ratio of the auxiliary agent to the iron source is 4:0.5 to 4:1.

[0147] In some embodiments, the calcination temperature is 900°C to 1100°C.

[0148] In some embodiments, the calcination time is 3 hours to 5 hours.

[0149] The porous carbon matrix is ​​fully graphitized by controlling the calcination temperature and time.

[0150] In some embodiments, the calcination atmosphere is a nitrogen atmosphere or a rare gas atmosphere.

[0151] In some embodiments, the rare gas atmosphere includes at least one of a helium atmosphere, a neon atmosphere, an argon atmosphere, a krypton atmosphere, or a xenon atmosphere.

[0152] Calcination in a nitrogen atmosphere or a rare gas atmosphere is beneficial to improving the utilization rate of the carbon source.

[0153] In some embodiments, hydrochloric acid is used for pickling.

[0154] In some embodiments, the carbonization temperature is 600°C to 800°C.

[0155] By carbonizing the carbon matrix, a dense carbon layer is formed on both the outer and inner surfaces of the carbon matrix, thereby optimizing the interface of the carbon matrix and improving the structural stability.

[0156] In some embodiments, a first carrier gas is selected during the carbonization process, and the first carrier gas is composed of a hydrocarbon compound and a protective gas.

[0157] In some embodiments, the volume fraction of hydrocarbon compounds in the first carrier gas is 50% to 60%.

[0158] By controlling the carrier gas during the carbonization process, the growth quality of the carbon layer is further improved, and the stability of the carbon layer is further improved.

[0159] In some embodiments, the carbonization time is 10 min to 30 min.

[0160] In some embodiments, a second carrier gas is selected during the carbon material deposition process; the second carrier gas includes a hydrocarbon compound and a protective gas.

[0161] In some embodiments, the volume fraction of the hydrocarbon compound in the second carrier gas is 10% to 20%.

[0162] In some embodiments, the carbon material is deposited at a temperature of 150°C to 250°C.

[0163] In some embodiments, the carbon material is deposited for a time period of 1.5 hours to 2.5 hours.

[0164] During the carbon material deposition process, carbon nanotubes are first formed on the surface of the porous carbon matrix containing the carbon layer, and then graphene is further formed as the deposition time is delayed. By controlling the deposition parameters, the ratio of carbon nanotubes to graphene is controlled, thereby further improving the performance of the silicon-carbon negative electrode material.

[0165] In some embodiments, a third carrier gas is selected for the silicon-carbon material deposition, and the third carrier gas includes a hydrocarbon compound, a silane compound, and a protective gas.

[0166] In some embodiments, the volume fraction of hydrocarbon compounds in the third carrier gas is 10% to 20%.

[0167] In some embodiments, the volume fraction of the silane compound in the third carrier gas is 20% to 40%.

[0168] In some embodiments, the silicon-carbon material is deposited at a temperature of 150° C. to 250° C.

[0169] In some embodiments, the silicon-carbon material is deposited for 1.5 hours to 2.5 hours.

[0170] By controlling the deposition parameters of the silicon-carbon material, the mass fraction of silicon in the silicon-carbon material and the size of the carbon-silicon particles can be regulated, thereby producing a silicon-carbon negative electrode material with excellent performance.

[0171] In some embodiments, the hydrocarbon compounds in the first carrier gas, the second carrier gas, and the third carrier gas are independently selected from at least one of alkanes, alkenes, alkynes, and aromatic hydrocarbons.

[0172] In some embodiments, the alkane is a C1 to C10 alkane.

[0173] C1 to C10 refers to a total carbon atom number of 1 to 10.

[0174] In some embodiments, the alkane includes at least one of methane, ethane, propane, n-butane, and isobutane.

[0175] In some embodiments, the olefin is a C1 to C10 olefin.

[0176] In some embodiments, the olefin comprises at least one of ethylene, propylene, 2-methylpropylene, 1-butene, and 2-butene.

[0177] In some embodiments, the alkyne is a C1 to C10 alkyne.

[0178] In some embodiments, the alkyne comprises at least one of acetylene, propyne, 1-butyne, and 2-butyne.

[0179] Methane, ethylene and acetylene are gases at room temperature.

[0180] In some embodiments, the aromatic hydrocarbon is a C6 to C20 aromatic hydrocarbon.

[0181] In some embodiments, the aromatic hydrocarbon includes at least one of benzene, toluene, ethylbenzene, xylene, and naphthalene.

[0182] In some embodiments, the carbon material is deposited by chemical vapor deposition.

[0183] The parameters in the chemical vapor deposition process are controllable, which is conducive to the production of carbon materials with small defects and high quality.

[0184] During the chemical vapor deposition process of carbon materials, the growth quality of carbon materials (graphene and carbon nanotubes) is further improved by controlling the carbon source; during the growth process of carbon materials, carbon source gas molecules will nucleate on the substrate surface to form carbon clusters, and then as the temperature increases and time increases, the carbon clusters gradually fuse and grow into graphene.

[0185] In some embodiments, the silane compound includes at least one of SiH4, Si2H6, ClSiH3, Cl2SiH2, Cl3SiH, SiCl4, and Si2Cl6.

[0186] In some embodiments, the protective gas in the first carrier gas, the second carrier gas, and the third carrier gas is independently selected from at least one of hydrogen, nitrogen, and a rare gas.

[0187] In some embodiments, the noble gas includes at least one of helium, neon, argon, krypton, or xenon.

[0188] In some embodiments, the protective gas in the first carrier gas, the second carrier gas, and the third carrier gas consists of hydrogen and argon.

[0189] In some embodiments, the silicon-carbon material is subjected to pressurization and homogenization treatments after deposition.

[0190] After pressure treatment, the material is homogenized and its stability is further improved.

[0191] In some embodiments, the pressure of the pressurization treatment is 900 kPa to 1000 kPa.

[0192] In some embodiments, the temperature of the pressurization treatment is 900° C. to 1100° C.

[0193] By pressurizing the composite material at the above-mentioned pressure and temperature, the stability of the material is further improved, thereby producing a silicon-carbon negative electrode material with excellent stability.

[0194] In some embodiments, the homogenizing is ultrasonication.

[0195] Through ultrasonic treatment, the uniformity of the silicon-carbon negative electrode material is further improved. At the same time, ultrasonic treatment will separate the carbon material attached to the outer surface and the silicon-carbon material from the outer surface carbon layer.

[0196] In some embodiments, the ultrasonic treatment is to add the pressurized material into a solvent for ultrasonic treatment.

[0197] In some embodiments, the sonication frequency is 4 kHz to 5 kHz.

[0198] In some embodiments, the temperature of the ultrasonic treatment is 40°C to 60°C.

[0199] In some embodiments, the solvent is ethanol.

[0200] In some embodiments, the mass concentration of the pressurized material in the solvent is 10 g / L to 20 g / L.

[0201] A third aspect of the embodiments of the present application provides an electrode sheet, comprising the silicon-carbon negative electrode material of the first aspect of the embodiments of the present application;

[0202] And / or, the silicon-carbon negative electrode material prepared according to the second aspect of the embodiment of the present application.

[0203] A fourth aspect of the embodiments of the present application provides a battery pack, comprising the silicon-carbon negative electrode material of the first aspect of the embodiments of the present application;

[0204] And / or, the silicon-carbon negative electrode material prepared according to the second aspect of the embodiment of the present application;

[0205] And / or, the electrode sheet of the third aspect of the embodiments of the present application.

[0206] In some embodiments, the silicon-carbon negative electrode material and / or electrode sheet is used to prepare a battery module.

[0207] In some embodiments, the silicon-carbon negative electrode material, electrode sheet and / or battery pack are used to manufacture electrical devices.

[0208] In some embodiments, the electric device includes an electric vehicle.

[0209] Example 1

[0210] This embodiment is a method for preparing a silicon-carbon negative electrode material, which comprises the following steps:

[0211] S1. Adding a carbon source (glucose), an auxiliary agent (nitric acid), and an iron source (ferric nitrate) to water to prepare a mixed solution;

[0212] The molar ratio of carbon source, adjuvant and iron source is 1:4:1;

[0213] The mixed solution was concentrated to a solid content of 40%, solid-liquid separation was performed, and the solid phase was collected and dried to obtain a precursor;

[0214] The precursor is calcined (calcination temperature is 1300 ° C, calcination time is 4 hours, calcination atmosphere is nitrogen) and then pickled (the pickling agent is hydrochloric acid), and then dried to obtain a porous carbon matrix;

[0215] S2. While passing the first carrier gas, heating the porous carbon substrate obtained in step S1 to 700° C. (heating rate of 10° C. / min) and carbonizing for 30 min to obtain a porous carbon substrate containing a carbon layer;

[0216] The first carrier gas consists of argon and methane; wherein the flow rate of argon is 400 mL / min, and the flow rate of methane is 500 mL / min;

[0217] S3, heating the porous carbon substrate containing the carbon layer in an argon-hydrogen mixed gas (the volume ratio of argon and hydrogen is 1:1, and the flow rate is 5 mL / min) for 2 h (from 25°C to 200°C), and then introducing a second carrier gas for deposition (the deposition temperature is 200°C); after the second carrier gas deposition is completed, a third carrier gas is deposited to obtain a composite material;

[0218] The second carrier gas is composed of a mixture of methane and argon-hydrogen (the volume ratio of argon to hydrogen is 1:1), the volume fraction of methane is 10%, and the flow rate of the argon-hydrogen mixture is 5 mL / min;

[0219] The third carrier gas is composed of methane, silane, and an argon-hydrogen mixture (the volume ratio of argon to hydrogen is 1:1), with a volume fraction of methane of 10% and a volume fraction of silane (SiH4) of 25%. The flow rate of the argon-hydrogen mixture is 5 mL / min.

[0220] S4, cooling and homogenizing the composite material after pressurizing it;

[0221] The temperature of the pressurization treatment is 1000°C, the pressure of the pressurization treatment is 950 kPa, and the time is 10 h;

[0222] The homogenization operation is as follows:

[0223] The cooled material was added to anhydrous ethanol to form a mixture (mass concentration was 20 g / L);

[0224] The mixture was then ultrasonically treated (ultrasonic frequency of 5 kHz, temperature of 50°C, time of 2 h), and after the ultrasonic treatment, the solid and liquid were separated and dried.

[0225] Example 2

[0226] This embodiment is a method for preparing a silicon-carbon negative electrode material, which differs from Example 1 only in that:

[0227] The molar ratio of the carbon source, the auxiliary agent and the iron source is 2:4:1.

[0228] Example 3

[0229] This embodiment is a method for preparing a silicon-carbon negative electrode material, which differs from Example 1 only in that:

[0230] The molar ratio of the carbon source, the auxiliary agent and the iron source is 3:4:1.

[0231] Example 4

[0232] This embodiment is a method for preparing a silicon-carbon negative electrode material, which differs from Example 1 only in that:

[0233] The molar ratio of carbon source, auxiliary agent and iron source is 2:4:0.5.

[0234] Example 5

[0235] This embodiment is a method for preparing a silicon-carbon negative electrode material, which differs from Example 2 only in that:

[0236] The volume fraction of silane (SiH4) in the third carrier gas is 30%.

[0237] Example 6

[0238] This embodiment is a method for preparing a silicon-carbon negative electrode material, which differs from Example 2 only in that:

[0239] The volume fraction of silane (SiH4) in the third carrier gas is 35%.

[0240] Example 7

[0241] This embodiment is a method for preparing a silicon-carbon negative electrode material, which differs from Example 2 only in that:

[0242] The volume fraction of methane in the second carrier gas is 5%; the volume fraction of methane in the third carrier gas is 5%, and the volume fraction of silane (SiH4) is 30%.

[0243] Example 8

[0244] This embodiment is a method for preparing a silicon-carbon negative electrode material, which differs from Example 2 only in that:

[0245] The volume fraction of methane in the second carrier gas is 15%; the volume fraction of methane in the third carrier gas is 15%, and the volume fraction of silane (SiH4) is 30%.

[0246] Comparative Example 1

[0247] This comparative example is a method for preparing a negative electrode material, which differs from Example 2 only in that:

[0248] No deposition of silicon carbon material was performed.

[0249] Comparative Example 2

[0250] This comparative example is a method for preparing a silicon-carbon negative electrode material, which differs from Example 8 only in that:

[0251] The volume fraction of methane in the third carrier gas is 0%.

[0252] The negative electrode materials prepared in Examples 1 to 8 and Comparative Examples 1 to 2 were made into soft-pack batteries for performance testing:

[0253] The positive electrode production formula is NCM: PVDF: CNT: SP = 96:2:1:1 (mass ratio), and the positive electrode sheet is produced by coating;

[0254] Negative electrode preparation formula - negative electrode material (negative electrode material prepared in Examples 1 to 8 and Comparative Examples 1 to 2): Si:PAA:CNT = 90:5:4:1 (mass ratio); coating to prepare electrode sheet;

[0255] The positive and negative electrodes were stacked with the separator to form a battery cell. After drying, the electrolyte was injected into the battery cell (the battery cell was designed with the same capacity, with a design capacity of 2.3Ah). After formation and constant capacity, EIS (Electrochemical Impedance Spectroscopy) and cycle testing were performed. The test temperature was 25°C and the voltage range was 2.5V to 4.4V. The test capacity and capacity retention were calculated after 400 cycles at 1C / 1C. The charge transfer resistance (Rct) was calculated from the EIS test, and ΔRct was obtained from the charge transfer resistance before and after cycling. The test results are shown in Table 1.

[0256] Table 1 Performance test results of negative electrode materials prepared in Examples 1 to 8 and Comparative Examples 1 to 2

[0257] -Molar ratio of carbon source, auxiliary agent and iron source Methane volume fraction Silane volume fraction 1C / 1C Capacity retention rate (%) ΔRct Capacity (Ah) Example 11: 4:1 10% 25% 91.7% 0.0% 2.109 Example 22: 4:1 10% 25% 93.2% -1.6% 2.144 Example 33: 4:1 10% 25% 92.4% -0.8% 2.125 Example 42: 4:0.5 10% 25% 90.2% 1.6% 2.075 Example 52: 4:1 10% 30% 9 4.4%-2.9% 2.171 Example 6 2:4:1 10% 35% 92.4%-0.8% 2.125 Example 7 2:4:1 5% 30% 91.2% 0.5% 2.098 Example 8 2:4:1 15% 30% 93.9%-2.4% 2.160 Comparative Example 1 2:4:1 / / 87.1% 5.0% 2.003 Comparative Example 2 2:4:1 / 30% 88.4% 3.6% 2.033

[0258] Note: Charge transfer resistance refers to the resistance formed by the transfer of electrons in the charge layer formed on the electrode surface when current passes through the contact surface. The change in charge transfer resistance is used to measure the kinetic changes in electron transfer before and after the cycle.

[0259] The difference between Examples 1 to 3 lies in the amount of carbon source used. The test results show that controlling the amount of carbon source within a certain range is beneficial to further improving the capacity retention rate and capacity.

[0260] The difference between Example 2 and Example 4 is the amount of iron source used. From the test results, it is known that increasing the amount of iron source is beneficial to further improving the capacity retention rate and capacity.

[0261] The difference between Example 2 and Examples 5 to 6 is the volume fraction of silane. From the test results, it is known that controlling the volume fraction of silane within a certain range is beneficial to further improving the capacity retention rate and capacity.

[0262] The difference between Example 5 and Examples 7 to 8 is the volume fraction of methane. From the test results, it is known that controlling the volume fraction of methane within a certain range is beneficial to further improving the capacity retention rate and capacity.

[0263] In Comparative Examples 1 to 2, the silicon-carbon negative electrode material with a specific structure was not formed, and its cycle performance was greatly deteriorated; that is, the silicon-carbon negative electrode material with a specific structure prepared in this embodiment has greater advantages in cycle performance, interface performance and capacity.

[0264] The silicon-carbon negative electrode material structure in the embodiment is designed as follows:

[0265] The dense outer carbon layer stabilizes the electrolyte interface, while the inner carbon layer within the porous carbon matrix accommodates volume changes. The mechanical and chemical synergy between the two structurally distinct carbon layers enables Si-C particles to achieve both high densification and crack resistance. The volume expansion of silicon-carbon particles within the pore structure can lead to electrical contact failure, resulting in poor electron transport at the cell interface. To avoid poor contact due to pores, graphene, conductive carbon nanotubes, and single-arm carbon nanotubes are introduced to optimize the electronic conductivity network.

[0266] In the embodiment, by filling the pores of the porous carbon matrix with small Si-C particles, the risk of contact failure and porous carbon matrix shell rupture caused by volume changes of pure silicon particles is reduced, thereby improving the cycle stability;

[0267] At the same time, by filling carbon materials such as graphene and carbon nanotubes into the porous carbon matrix, the pore dynamics is improved; the compound of graphene and carbon nanotubes forms a structure similar to the spring clip inside the button, and the conductive carbon material has good flexibility, structural stability, electrical conductivity and thermal conductivity; thereby further alleviating a series of degradations caused by volume changes during the cycle.

[0268] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A silicon-carbon negative electrode material, comprising a porous carbon matrix; The porous carbon matrix includes a carbon layer disposed on the surface; The pores of the porous carbon matrix are filled with a silicon-carbon material and a carbon material; The mass ratio of the silicon-carbon material to the carbon material is 30:1 to 40:1; The carbon material includes carbon nanotubes and graphene; The mass ratio of the carbon nanotubes to the graphene is 2:1 to 5:1; The carbon nanotubes and the graphene are compounded on the surface of the silicon-carbon material and / or between the silicon-carbon materials.

2. The silicon-carbon negative electrode material according to claim 1, wherein, The mass ratio of the silicon-carbon material to the carbon material is 35:1 to 37:

1.

3. The silicon-carbon anode material according to claim 1, wherein, The mass ratio of the carbon nanotubes to the graphene is 3:1 to 4:

1.

4. The silicon-carbon anode material according to claim 1, wherein The porosity of the porous carbon matrix is 15% to 25%; And / or, the pore diameter of the pores in the porous carbon matrix is 10 nm to 55 nm; And / or, the particle size of the silicon-carbon material is 4 nm to 15 nm.

5. The silicon-carbon anode material according to claim 1, wherein, The thickness of the carbon layer is 1 nm to 3 nm.

6. The silicon-carbon negative electrode material according to claim 1, wherein, The volume ratio of the graphene to the pores of the porous carbon matrix is 0.1:100 to 2:100; And / or, the volume ratio of the carbon nanotubes to the pores of the porous carbon matrix is 3:100 to 15:100; And / or, the volume ratio of the silicon-carbon material to the pores of the porous carbon matrix is 0.1:100 to 20:

100.

7. The silicon-carbon anode material according to claim 1, wherein The graphene includes at least one of monolayer graphene, few-layer graphene, multi-layer graphene, and graphene nanosheets.

8. The silicon-carbon anode material according to claim 1, wherein, The carbon nanotubes are interspersed and intertwined between the silicon-carbon materials.

9. A method for preparing the silicon-carbon negative electrode material according to any one of claims 1 to 8, comprising the following steps: Carbonize the carbon matrix to obtain a porous carbon matrix with a carbon layer; Deposit a carbon material and a silicon-carbon material in sequence in the pores of the porous carbon matrix with the carbon layer.

10. The preparation method according to claim 9, wherein, The temperature of the carbonization is 600 °C to 800 °C; And / or, a first carrier gas is selected during the carbonization process, and the first carrier gas is composed of a hydrocarbon compound and a protective gas; The volume fraction of the hydrocarbon compound in the first carrier gas is 50% to 60%.

11. The preparation method according to claim 9, wherein, A second carrier gas is selected during the deposition process of the carbon material; the second carrier gas includes a hydrocarbon compound and a protective gas; And / or, the volume fraction of the hydrocarbon compound in the second carrier gas is 10% to 20%; And / or, the temperature of the carbon material deposition is 150 °C to 250 °C; And / or, the time of the carbon material deposition is 1.5 h to 2.5 h; And / or, a third carrier gas is selected for the deposition of the silicon-carbon material, and the third carrier gas includes a hydrocarbon compound, a silane compound, and a protective gas; And / or, the volume fraction of the hydrocarbon compound in the third carrier gas is 10% to 20%; And / or, the volume fraction of the silane compound in the third carrier gas is 20% to 40%; And / or, the temperature of the silicon-carbon material deposition is 150 °C to 250 °C; And / or, the time of the silicon-carbon material deposition is 1.5 h to 2.5 h.

12. The preparation method according to any one of claims 9 to 11, wherein, After the deposition of the silicon-carbon material is completed, pressure treatment and homogenization treatment are carried out; And / or, the pressure of the pressure treatment is 900 kPa to 1000 kPa; And / or, the temperature of the pressure treatment is 900 °C to 1100 °C; And / or, the homogenization treatment is ultrasonic treatment.

13. The preparation method according to claim 9, wherein, The deposition method of the carbon material is chemical vapor deposition.

14. An electrode sheet, comprising the silicon-carbon negative electrode material according to any one of claims 1 to 8; and / or, the silicon-carbon negative electrode material prepared by the preparation method according to any one of claims 9 to 13.

15. A battery pack, comprising the silicon-carbon negative electrode material according to any one of claims 1 to 8; and / or, the silicon-carbon negative electrode material prepared by the preparation method according to any one of claims 9 to 13; and / or, the electrode sheet according to claim 14.

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