Silicon-carbon negative electrode material and preparation method therefor

Abstract

Provided in the present application are a silicon-carbon negative electrode material and a preparation method therefor. The silicon-carbon negative electrode material comprises: single silicon-carbon particles, wherein each single silicon-carbon particle comprises a carbon matrix and doped amorphous silicon, the carbon matrix comprises a carbon framework and channels located inside the carbon framework, the channels are partially filled with the doped amorphous silicon, the beneficial doping coefficient of a doping element in the doped amorphous silicon is greater than or equal to 25 and less than or equal to 48, and the beneficial doping coefficient is determined by the carrier concentration of the silicon-carbon negative electrode material and the mass proportion of the doping element in the doped amorphous silicon; and a first coating layer, wherein the first coating layer is a carbon coating layer and coats the surfaces of the single silicon-carbon particles. The silicon-carbon negative electrode material and the preparation method therefor significantly improve the conductivity of amorphous silicon deposited in the carbon framework, thereby significantly improving the conductivity and fast charging performance of the silicon-carbon negative electrode material.

Description

Silicon-carbon anode materials and their preparation methods Technical Field

[0001] This application relates to the field of lithium-ion batteries, and in particular to a silicon-carbon anode material and its preparation method. Background Technology

[0002] Silicon-based materials, used as anode materials for lithium-ion batteries, possess high specific capacity (theoretical specific capacity 4200 mAh / g), more than 10 times that of graphite, and are abundant, non-toxic, and environmentally friendly. However, silicon-based anodes suffer from drawbacks such as large volume expansion, poor conductivity and rate performance, low initial charge-discharge efficiency, and susceptibility to pulverization and detachment, severely impacting their lifespan. Currently, the performance of silicon-based anode materials is improved through modification methods, including nano-sizing, carbon-based composites, alloying, and conductive polymer composites.

[0003] A novel method for preparing silicon-based anode materials utilizes chemical vapor deposition (CVD) to deposit nano-silicon into porous carbon, followed by carbon coating to form a silicon-carbon anode material. This method effectively reduces the material's volume expansion during charge and discharge, resulting in advantages such as high capacity, high initial charge-discharge efficiency, and cycle stability. However, the nano-silicon is amorphous silicon, close to an intrinsic semiconductor, with low carrier concentration and poor conductivity. This leads to poor kinetic performance of the resulting silicon-carbon anode material, failing to meet current market demands for fast-charging performance in lithium-ion batteries.

[0004] In summary, in order to meet the current market demand for energy density and fast charging performance of lithium-ion batteries, it is particularly important to develop a silicon-carbon anode material with strong conductivity, good kinetic performance, and low cost. Summary of the Invention

[0005] One aspect of this application provides a silicon-carbon anode material, comprising: silicon-carbon single particles, wherein the silicon-carbon single particles include a carbon matrix and doped amorphous silicon, the carbon matrix includes a carbon skeleton and channels located inside the carbon skeleton, the doped amorphous silicon partially fills the channels, the beneficial doping coefficient of the doping element in the doped amorphous silicon is greater than or equal to 25 and less than or equal to 48, the beneficial doping coefficient being determined by the carrier concentration in the silicon-carbon anode material and the mass percentage of the doping element in the doped amorphous silicon; and a first coating layer, the first coating layer being a carbon coating layer, coating the surface of the silicon-carbon single particles.

[0006] In some embodiments of this application, the beneficial doping coefficient Where n is the carrier concentration in the silicon-carbon anode material, and the value of n ranges from 10. 12 ~10 22 cm -3w% represents the mass percentage of doped elements in the silicon-carbon anode material, and the value of w% ranges from 0.02% to 10%.

[0007] In some embodiments of this application, the doping element in the doped amorphous silicon includes at least one of phosphorus, antimony, and arsenic; or the doping element in the doped amorphous silicon includes at least one of boron, gallium, and indium.

[0008] In some embodiments of this application, the carbon framework includes hard carbon and carbon allotropes, including graphite, amorphous carbon, diamond, C60, carbon nanotubes, graphene, and / or carbon fibers.

[0009] In some embodiments of this application, the silicon element content in the silicon-carbon anode material is 30% to 80% by mass.

[0010] This application also provides a method for preparing a silicon-carbon anode material, comprising: providing a carbon matrix, the carbon matrix including a carbon skeleton and channels located inside the carbon skeleton; depositing doped amorphous silicon in the channels to form silicon-carbon single particles, wherein the beneficial doping coefficient of the doping element in the doped amorphous silicon is greater than or equal to 25 and less than or equal to 48, and the beneficial doping coefficient is determined by the carrier concentration in the silicon-carbon anode material and the mass ratio of the doping element in the doped amorphous silicon; providing a first carbon source gas, such that the first carbon source gas forms a first coating layer on the surface of the silicon-carbon single particles, the first coating layer being a carbon coating layer, coating the surface of the silicon-carbon single particles.

[0011] In some embodiments of this application, the method for depositing doped amorphous silicon in the channel includes: simultaneously introducing silicon source gas and dopant gas into the deposition chamber, and depositing doped amorphous silicon in the channel by chemical vapor deposition.

[0012] In some embodiments of this application, the silicon source gas includes silane gases, the doping gas includes at least one of gaseous compounds of phosphorus, antimony, and arsenic, or the doping gas includes at least one of gaseous compounds of boron, gallium, and indium.

[0013] In some embodiments of this application, the volume ratio of the silane gas to the dopant gas is 1:(0.02~1); the chemical vapor deposition temperature is 400℃~900℃, and the time is greater than 0.5 hours.

[0014] In some embodiments of this application, the carrier gas is mixed with the silicon source gas and then simultaneously introduced into the deposition chamber along with the doping gas, wherein the content of the carrier gas is 10% to 99%.

[0015] In some embodiments of this application, the method for depositing doped amorphous silicon in the channel includes: introducing a silicon source gas into a deposition chamber, depositing intrinsic amorphous silicon in the channel by chemical vapor deposition, and implanting doped ions into the intrinsic amorphous silicon by ion implantation.

[0016] In some embodiments of this application, the silicon source gas includes silane gases, and the dopant ions include at least one of boron ions, phosphorus ions, antimony ions, and arsenic ions.

[0017] In some embodiments of this application, the ion implantation method uses an ion implantation energy of 2kV to 900kV and an ion implantation dose of 10. 17 ~10 20 ion / cm 2 .

[0018] In some embodiments of this application, the method for depositing doped amorphous silicon in the channel includes: introducing a silicon source gas into a deposition chamber and depositing intrinsic amorphous silicon in the channel by chemical vapor deposition; and incorporating dopant atoms from a dopant source into the intrinsic amorphous silicon by ion diffusion.

[0019] In some embodiments of this application, the doping source includes at least one of a solid-phase source, a liquid-phase source, and a gas-phase source. The solid-phase source includes As2O3, P2O5, and BN. The liquid-phase source includes AsAl, B(OCH3)3, and POCl3. The gas-phase source includes AsH3, BH5, and PH3.

[0020] In some embodiments of this application, the diffusion temperature in the ion diffusion method is 500–1200°C, and the diffusion time is 10 s–5 h.

[0021] In some embodiments of this application, the method further includes: performing an annealing treatment, wherein the annealing treatment is performed under hydrogen or an inert atmosphere, the annealing temperature is 650℃~1200℃, and the annealing time is 10s~10h.

[0022] In some embodiments of this application, the first carbon source gas includes at least one of acetylene, methane, ethylene, propane, and propylene, and the reaction temperature for forming the first coating layer is 300–800°C.

[0023] In some embodiments of this application, the particle size of the doped amorphous silicon is 0.2 nm to 5 nm.

[0024] In some embodiments of this application, the silicon element content in the silicon-carbon anode material is 30% to 80% by mass.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] This application provides a silicon-carbon anode material and its preparation method. The method forms doped amorphous silicon in the channels inside the carbon skeleton, which significantly increases the concentration of charge carriers, i.e., free electrons, in the formed silicon-carbon anode material. By controlling the beneficial doping coefficient of the doping element in the silicon-carbon anode material, the conductivity of the doped amorphous silicon is significantly improved without reducing other electrochemical properties of the silicon-carbon anode material, thereby improving the conductivity and fast charging performance of the silicon-carbon anode material.

[0027] This application embodiment controls the doping effect by controlling the beneficial doping coefficient of the dopant element in the silicon-carbon anode material. When the mass of the dopant element in the amorphous silicon is 0.02% of the total mass of the silicon-carbon anode material, the change of the dopant element to the basic properties of the amorphous silicon is relatively small, but it can still optimize the electrical performance of the silicon-carbon anode material. As the ratio of the mass of the dopant element in the amorphous silicon to the total mass of the silicon-carbon anode material increases, for example, when the mass of the dopant element in the amorphous silicon is 10% of the total mass of the silicon-carbon anode material, the conductivity of the amorphous silicon increases significantly, but other electrical properties of the silicon-carbon anode material, such as capacity efficiency, decrease significantly. Therefore, if the amount of dopant element in the amorphous silicon is too high, it may have a negative impact on the structural stability and other electrical properties of the silicon-carbon anode material.

[0028] The embodiments of this application overcome the shortcomings of the prior art, which uses conventional nano-silicon to fill the channels, resulting in low carrier concentration and poor conductivity, leading to poor dynamic performance of silicon-carbon anode materials and failing to meet the current market demand for fast charging performance of lithium-ion batteries. Attached Figure Description

[0029] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals denote similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are not drawn to scale. Wherein:

[0030] Figure 1 is a process flow diagram of the preparation method of silicon-carbon anode material according to an embodiment of this application;

[0031] Figure 2 shows the XRD pattern of the silicon-carbon anode material prepared in Example 1;

[0032] Figure 3 shows the SEM image of the silicon-carbon anode material prepared in Example 1. Detailed Implementation

[0033] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to make and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0034] Research has found that the silicon component in silicon-carbon anode materials exists in the form of nano-amorphous silicon, with properties close to those of intrinsic semiconductors. The conductivity of a semiconductor is closely related to the concentration of charge carriers; a higher carrier concentration means more freely moving charges within the semiconductor, thus resulting in higher conductivity. The generation of charge carriers in intrinsic semiconductors mainly relies on intrinsic excitation, where electrons gain sufficient energy through thermal motion to break free from covalent bonds and become free electrons, leaving a hole within the covalent bond. At room temperature, this thermal motion is relatively weak, resulting in a small number of free electrons and holes generated. For example, in pure silicon crystals, the concentration of charge carriers generated by intrinsic excitation is typically very low, leading to insufficient particles capable of participating in conductivity, thus resulting in poor conductivity. Therefore, the low carrier concentration of the silicon component in intrinsic semiconductor silicon-carbon anode materials leads to poor conductivity and kinetic performance, a characteristic that prevents the material from meeting the current market demand for fast-charging performance in lithium-ion batteries. Developing a silicon-carbon anode material that combines strong conductivity, excellent kinetic performance, and low cost is of particular importance to current technological advancements and market demands.

[0035] To improve the conductivity of semiconductor materials, a certain number of doping elements can be incorporated into them, thereby improving their electrical properties. The conductivity of doped semiconductors is significantly improved compared to intrinsic semiconductors. Depending on the doping element, doped semiconductors can be classified as n-type and p-type semiconductors. When a trace amount of a pentavalent element, such as phosphorus, is added to intrinsic silicon, the phosphorus atom replaces a small number of silicon atoms in the crystal, occupying certain positions on the crystal lattice. Phosphorus atoms have five valence electrons in their outermost shell. Four of these valence electrons form covalent bonds with four neighboring silicon atoms, leaving one extra electron outside these covalent bonds. This extra electron is only weakly bound to the phosphorus atom and can easily gain the energy to break free at room temperature, becoming a free electron that roams freely within the crystal lattice. The phosphorus atom that has lost its electron becomes an immobile positive ion.

[0036] Phosphorus atoms are called donor atoms because they can release one electron, and are also known as donor dopant elements. In intrinsic semiconductors, each phosphorus atom introduced generates one free electron, while the number of holes generated by intrinsic excitation remains unchanged. Thus, in phosphorus-doped semiconductors, the number of free electrons far exceeds the number of holes, becoming the majority carriers, while holes become the minority carriers. Clearly, electrons are the primary agents of conductivity, hence this type of semiconductor is called an electron-type semiconductor, or n-type semiconductor. In intrinsic semiconductor silicon, if a trace amount of a trivalent element, such as boron, is introduced, the boron atom replaces a small number of silicon atoms in the crystal, occupying certain positions on the crystal lattice. The three valence electrons of the boron atom form complete covalent bonds with the three valence electrons of its three neighboring silicon atoms, while the covalent bond of the third adjacent silicon atom lacks one electron, creating a hole. This hole is filled by the valence electrons of a nearby silicon atom, allowing the trivalent boron atom to gain an electron and become a negative ion. Simultaneously, a hole appears on the adjacent covalent bond. Since the boron atom acts as an electron acceptor, it is called an acceptor atom, or acceptor dopant. In an intrinsic semiconductor, each boron atom provides one hole. When a certain number of boron atoms are added, the number of holes in the semiconductor can far exceed the number of intrinsically excited electrons, making them the majority carriers, while electrons become the minority carriers. Clearly, holes are the primary carriers involved in conduction; therefore, this type of semiconductor is called a hole-type semiconductor, or p-type semiconductor for short. In summary, doping intrinsic semiconductors with pentavalent or trivalent elements can significantly increase the number of free electrons or holes, substantially improving their carrier concentration.

[0037] The silicon-carbon anode material and its preparation method provided in this application partially fill the channels within the carbon framework with doped amorphous silicon. The beneficial doping coefficient of the doping element in the doped amorphous silicon is greater than or equal to 25 and less than or equal to 48. The beneficial doping coefficient is determined by the carrier concentration in the silicon-carbon anode material and the mass ratio of the doping element in the doped amorphous silicon. The doping element in the doped amorphous silicon increases the concentration of carriers, i.e., free electrons, thereby enhancing the conductivity of the silicon-carbon anode material and significantly improving the fast-charging performance of the formed silicon-carbon anode material. This overcomes the shortcomings of existing technologies that use conventional nano-silicon to fill the channels, resulting in low carrier concentration and poor conductivity, leading to poor kinetic performance of the silicon-carbon anode material and failing to meet the current market demand for fast-charging performance of lithium-ion batteries.

[0038] This application provides a silicon-carbon anode material, comprising: silicon-carbon single particles, wherein the silicon-carbon single particles include a carbon matrix and doped amorphous silicon, the carbon matrix includes a carbon skeleton and channels located inside the carbon skeleton, the doped amorphous silicon partially fills the channels, the beneficial doping coefficient of the doping element in the doped amorphous silicon is greater than or equal to 25 and less than or equal to 48, the beneficial doping coefficient being determined by the carrier concentration in the silicon-carbon anode material and the mass percentage of the doping element in the doped amorphous silicon; and a first coating layer, the first coating layer being a carbon coating layer, coating the surface of the silicon-carbon single particles.

[0039] In some embodiments of this application, the carbon matrix includes a carbon framework and channels located within the carbon framework. The channels include micropores with a diameter less than 2 nm, mesopores with a diameter between 2 and 50 nm, and macropores with a diameter greater than 50 nm. The carbon framework comprises porous carbon, for example, where the total volume ratio of mesopores and micropores is greater than 70%, and the specific surface area is greater than 500 m². 2 / g and the total volume of micropores, mesopores, and pores is greater than 0.4cm³. 3 / g of granular porous carbon. For example, the specific surface area of ​​the porous carbon is 1600m². 2 / g, wherein the porous carbon has a particle size of 5μm to 20μm and a tap density of 0.3 to 0.5g / cm³. 3 .

[0040] In some embodiments of this application, the porosity of the channels is 1% to 30%, which is the proportion of the remaining volume of the channels to the total volume after the deposition of doped amorphous silicon; that is, the doped amorphous silicon fills 70% to 99% of the channels. The doped amorphous silicon is deposited in the channels, partially filling them. The presence of a certain amount of porosity within the carbon framework can significantly reduce the expansion rate of the formed silicon-carbon anode material.

[0041] In some embodiments of this application, the carbon framework includes hard carbon and carbon allotropes, the carbon allotropes including graphite, amorphous carbon, diamond, C60, carbon nanotubes, graphene and / or carbon fibers, and the carbon nanotubes including single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0042] In some embodiments of this application, the size of the doped amorphous silicon particles is 0.2 nm to 5 nm. Optionally, the size of the doped amorphous silicon particles is 0.1 nm to 2 nm, such as 0.5 nm, 1 nm, 1.2 nm, 1.6 nm, etc.

[0043] In some embodiments of this application, the doping element in the doped amorphous silicon can be at least one of Group V elements such as phosphorus, antimony and arsenic, or at least one of Group III elements such as boron (B), Ga (gallium) and In (indium). The mass of the doping element accounts for 0.02% to 10% of the total mass of the silicon-carbon anode material, for example, 0.05%, 0.8%, 3%, 5%, 8%, etc.

[0044] When the mass of the dopant element accounts for 0.01% of the total mass of the silicon-carbon anode material, the change in the electrical properties of amorphous silicon by the dopant element is relatively small, but it still optimizes its electrical performance to some extent. As the mass of the dopant element gradually increases to the total mass of the silicon-carbon anode material, for example, reaching 10%, the electrical properties of the doped amorphous silicon will change significantly, for example, the conductivity of the doped amorphous silicon will increase significantly. However, if the mass of the dopant element accounts for too high a proportion of the total mass of the silicon-carbon anode material, it may also have a negative effect on the structural stability and other properties of the silicon-carbon anode material. Therefore, in order to obtain a silicon-carbon anode material with excellent performance, it is necessary to precisely control the mass of the dopant element to the total mass of the silicon-carbon anode material so that it can exhibit ideal performance in different application scenarios, including electronic devices and energy storage. Preferably, the mass of the dopant element accounts for 0.1% to 1% of the total mass of the silicon-carbon anode material, which can improve the conductivity and fast-charging performance of the silicon-carbon anode material, while also taking into account the theoretical specific capacity of the silicon-carbon additive material.

[0045] The silicon-carbon anode material described in this application embodiment has a beneficial doping coefficient of the doped element as follows: Where n is the carrier concentration in the silicon-carbon anode material, representing the conductivity of the silicon-carbon anode material, and the value of n ranges from 10. 12 ~10 22 cm -3 w% is the mass percentage of the doped element in the silicon-carbon anode material (the percentage of the mass of the doped element in the total mass of the silicon-carbon anode material), and the value range of w% is 0.02% to 10%. The carrier concentration per unit dopant element in the silicon-carbon anode material represents the carrier growth contributed by an average dopant element introduction of 1%, indicating the effective doping size of the dopant element. (1-w%) represents the mass percentage of silicon-carbon components required to maintain the basic electrochemical performance of the silicon-carbon anode material. Since the dopant element lacks lithium intercalation activity and does not positively affect the structural stability or other electrochemical performance of the silicon-carbon anode material, the mass percentage of the dopant element needs to be controlled. The mass percentage of the dopant element should not be excessively increased simply to improve the conductivity of the silicon-carbon anode material. In this embodiment, a higher beneficial doping coefficient T indicates better conductivity and a higher effective doping ratio in the formed silicon-carbon anode material, while also reducing the negative effects of doping.

[0046] In some embodiments of this application, the silicon element content in the silicon-carbon anode material is 30% to 80% by mass, preferably 30% to 60%, such as 48%, 50%, 52%, etc.

[0047] The silicon-carbon anode material described in this embodiment further includes a first coating layer, which is a carbon coating layer that coats the surface of the silicon-carbon single particles. By coating the surface of the silicon-carbon single particles with a layer of silicon carbide, the activity of the silicon-carbon single particles can be reduced, and the volume expansion of silicon in the battery prepared using the silicon-carbon anode material during charge-discharge cycles can be limited, thereby significantly improving the cycle performance of the material.

[0048] Referring to Figure 1, the preparation method of the silicon-carbon anode material according to an embodiment of this application includes the following steps:

[0049] Step S1: Provide a carbon matrix, the carbon matrix including a carbon skeleton and channels located inside the carbon skeleton, and deposit doped amorphous silicon in the channels to form silicon-carbon single particles;

[0050] A carbon matrix is ​​provided, comprising a carbon framework and channels located within the carbon framework. A silicon-containing precursor is used as a silicon source and introduced into a reaction chamber. Doped amorphous silicon is deposited within the channels using a chemical vapor deposition process to form silicon-carbon single particles, wherein the doped amorphous silicon partially fills the channels. In some embodiments of this application, the total volume ratio of mesopores and micropores in the carbon matrix is ​​greater than 70%, and the surface area is greater than 500 m². 2 / g and the total volume of micropores, mesopores, and pores is greater than 0.4cm³. 3 / g of granular porous carbon.

[0051] In some embodiments of this application, the carbon framework includes hard carbon and carbon allotropes, the carbon allotropes including graphite, amorphous carbon, diamond, C60, carbon nanotubes, graphene and / or carbon fibers, and the carbon nanotubes including single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0052] The silicon source is Si n H 2n+2 (n is a positive integer) may include silane gases, including but not limited to at least one of silane, disilane, trisilane, tetrasilane, chlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane.

[0053] In some embodiments of this application, the size of the doped amorphous silicon particles is 0.2 nm to 5 nm. Optionally, the size of the doped amorphous silicon particles is 0.1 nm to 2 nm, such as 0.5 nm, 1 nm, 1.2 nm, 1.6 nm, etc. In some embodiments of this application, the porosity of the channels in the silicon-carbon single particles is 1% to 30%, and the porosity is the proportion of the remaining volume of the channels after the doped amorphous silicon is deposited in the channels to the total volume.

[0054] In some embodiments of this application, the method for depositing doped amorphous silicon in the channel includes: simultaneously introducing a silicon source gas and a dopant gas into the deposition chamber, and depositing doped amorphous silicon in the channel by a chemical vapor deposition process.

[0055] In this embodiment, the silicon source includes a silane gas, and the dopant gas includes at least one gaseous compound of a Group 5 element, such as phosphorus, antimony, and arsenic, for example, phosphine (PH3) and arsine (AsH3); it may also include at least one gaseous compound of a Group 3 element, such as boron (B), gallium (Ga), and indium (In), for example, borane (BH5). The volume ratio of the silane gas to the dopant gas is 1:(0.02~1); the chemical vapor deposition is performed at a deposition temperature of 400℃~900℃ for a time of 0.5h or more.

[0056] In some embodiments of this application, porous carbon is placed in the reaction chamber of a chemical deposition apparatus, and silane and dopant gas PH3 are introduced into the reaction chamber. The volume ratio of silane to dopant gas PH3 is 1:0.3. The silane reacts with the porous carbon at a temperature of 580 degrees Celsius for 7 hours. After the silane and the dopant gas are adsorbed on the surface of the pores, they undergo thermal decomposition inside the pores at a temperature of 580 degrees Celsius, thereby generating doped amorphous silicon within the pores of the porous carbon, forming the silicon-carbon single particles.

[0057] In other embodiments of this application, porous carbon is placed in the reaction chamber of a chemical deposition apparatus, and silane and dopant gas BH5 are introduced into the reaction chamber. The volume ratio of silane to dopant gas BH5 is 1:0.2. The silane reacts with the porous carbon at a temperature of 600°C for 6 hours. After the silane and the dopant gas are adsorbed on the surface of the pores, they undergo thermal decomposition inside the pores at a temperature of 600°C, thereby generating doped amorphous silicon within the pores of the porous carbon, forming the silicon-carbon single particles.

[0058] In some other embodiments of this application, the carrier gas can be mixed with the silicon source gas and then simultaneously introduced into the deposition chamber along with the dopant gas. The volume of the carrier gas is 10% to 99% of the total volume of all introduced reaction gases. The carrier gas can be at least one of nitrogen, hydrogen, helium, neon, argon, krypton, and xenon.

[0059] In some embodiments of this application, the method of depositing doped amorphous silicon within the channels includes:

[0060] A silicon source gas is introduced into the deposition chamber, and intrinsic amorphous silicon is deposited within the pores using a chemical vapor deposition (CVD) process. Specifically, porous carbon is placed in the reaction chamber of a CVD apparatus, and trichlorosilane is introduced into the chamber. The trichlorosilane reacts with the porous carbon at 550°C for 3 hours. After the trichlorosilane is adsorbed onto the surface of the pores, it undergoes thermal decomposition within the pores at 550°C, thereby generating intrinsic amorphous silicon within the pores of the porous carbon. In other embodiments of this application, a carrier gas can be mixed with the silicon source gas and introduced into the deposition chamber. The volume of the carrier gas is 10% to 99% of the total volume of all introduced reaction gases, for example, 20%, 30%, 40%, 50%, 60%, 70%, and 80%.

[0061] The intrinsic amorphous silicon is an amorphous solid in which the arrangement of atoms is not periodic. During the preparation of intrinsic amorphous silicon using methods such as chemical vapor deposition, the silicon source gas decomposes at relatively low temperatures to form silicon particles, while simultaneously introducing a large number of hydrogen atoms. This prevents the silicon atoms from forming a long-range ordered arrangement before a crystal structure is formed. This process disrupts the periodic arrangement of atoms in the silicon crystal, resulting in an amorphous state, and thus alters the physical and chemical properties of the silicon material. The random structure of amorphous silicon leads to its unique optical and electrical properties, such as low electrical conductivity and optical absorption characteristics, making it an intrinsic semiconductor.

[0062] After generating the intrinsic amorphous silicon, dopant ions are implanted into the intrinsic amorphous silicon using ion implantation. The silicon source gas includes silane gases, and the dopant ions include at least one of boron ions, phosphorus ions, antimony ions, and arsenic ions. In the ion implantation method, the dopant gas is converted into dopant ions in an ion implanter. The dopant gas is introduced into the ion implanter, which can accelerate the dopant gas to a high speed, converting it into dopant ions. These dopant ions can then be implanted into the intrinsic amorphous silicon deposited within the channels in a controllable manner, thereby forming doped amorphous silicon. The ion implanter can inject plasma at an implantation energy of 1 kV to 900 kV. 17 ~10 20 ion / cm 2 The silicon deposited within the pores is implanted at an implantation rate of 1 kV to 900 kV per hour. In this ion implantation method, the ion implantation energy is 1 kV to 900 kV, and the ion implantation dose is 10. 17 ~10 20 ion / cm 2 .

[0063] In some embodiments of this application, the method of depositing doped amorphous silicon within the channels includes:

[0064] First, a silicon source gas is introduced into the deposition chamber, and intrinsic amorphous silicon is deposited within the pores using a chemical vapor deposition (CVD) process. Specifically, porous carbon is placed in the reaction chamber of the CVD apparatus, and tetrasilane is introduced into the chamber. The tetrasilane reacts with the porous carbon at 550°C for 4 hours. After the tetrasilane is adsorbed onto the surface of the pores, it undergoes thermal decomposition inside the pores at 550°C, thereby generating intrinsic amorphous silicon within the pores of the porous carbon. In some other embodiments of this application, a carrier gas can be mixed with the silicon source gas and then introduced into the deposition chamber, with the carrier gas volume ranging from 10% to 99% of the total introduced gas volume.

[0065] After depositing the intrinsic amorphous silicon within the channels, dopant atoms from the dopant source are incorporated into the intrinsic amorphous silicon via ion diffusion. This ion diffusion method utilizes the property of dopant atoms moving from high concentration to low concentration under high temperature conditions to controllably incorporate dopant atoms into the intrinsic amorphous silicon, thereby altering the conductivity type and dopant concentration. The ion diffusion equipment is typically a tubular diffusion furnace, and the diffusion temperature has a decisive influence on the process, generally ranging from 500℃ to 1200℃. Adjusting the diffusion process time and dopant atom flow rate can regulate the concentration of dopant atoms incorporated into the intrinsic amorphous silicon; the ion diffusion time ranges from 1 second to 5 hours.

[0066] The doping source includes at least one of a solid-phase source, a liquid-phase source, and a gas-phase source. The solid-phase source includes As₂O₃, P₂O₅, and BN; the liquid-phase source includes AsAl, B(OCH₃)₃, and POCl₃; and the gas-phase source includes AsH₃, BH₅, and PH₃. In the ion diffusion method, the diffusion temperature is 500–1200℃, and the diffusion time is 10 s–5 h.

[0067] In some embodiments of this application, after forming the doped amorphous silicon using any of the methods described above, the process may further include an annealing step. The annealing process repairs crystal damage and activates the implanted dopant ions. The annealing process alters the positions of semiconductor atoms, rearranging and loosening them within the crystal, causing atoms at defects to move into the defect area or crystal boundary, thus eliminating or minimizing defects. Simultaneously, annealing can help adjust the bandgap of the material, improve crystal quality and crystallinity, thereby improving the electrical properties of the material. The annealing process is performed under hydrogen or an inert atmosphere at a temperature of 650℃ to 1200℃ for 10 seconds to 10 hours. In some embodiments of this application, the particle size of the doped amorphous silicon is 0.2 nm to 5 nm. In some embodiments of this application, the silicon element content in the silicon-carbon anode material is 30% to 80% by mass.

[0068] Step S2: Provide a first carbon source gas to form a first coating layer on the surface of the silicon-carbon single particle. The first coating layer is a carbon coating layer that coats the surface of the silicon-carbon single particle. In some embodiments of this application, the first carbon source gas includes at least one of acetylene, methane, ethylene, propane, and propylene. The reaction temperature for forming the first coating layer is 300–800°C, and the reaction time is 0.1–5 h.

[0069] The silicon-carbon anode material described in this application embodiment can be applied to secondary batteries, which can be combined in multiple units to form an energy storage device, including a rechargeable battery. The silicon-carbon anode material described in this application embodiment has high conductivity, which can accelerate the electron transport speed during charging and discharging, thereby achieving fast charging. Therefore, when used as an anode material in secondary batteries, the silicon-carbon anode material can better accommodate the insertion and extraction of lithium ions, reduce the volume change of the electrode during charging and discharging, and improve the cycle stability and service life of the electrode. Good conductivity and structural stability also help reduce the internal resistance of the secondary battery, reduce energy loss during charging and discharging, and improve the charging and discharging efficiency and power performance of the secondary battery. In summary, the application of the silicon-carbon anode material in secondary batteries provides strong support for the performance improvement and widespread application of lithium-ion batteries, enabling lithium-ion batteries to play an important role in electric vehicles, portable electronic devices, and other fields.

[0070] Example 1

[0071] 1 kg of porous carbon was added to a fluidized bed reactor. The reactor was evacuated to a pressure below 100 Pa. Then, an inert gas (nitrogen) was introduced into the reactor until the pressure reached atmospheric pressure and maintained for 10 min. At a temperature of 0.11 MPa and 550 °C, a mixed gas (including a mixture of nitrogen, silane, and phosphine) was introduced and reacted for 4 h. P-doped nanocrystalline amorphous silicon was deposited in the pores of the porous carbon to form silicon-carbon single particles. The flow rates of nitrogen, silane, and phosphine in the mixed gas were 9 L / min, 5 L / min, and 1 L / min, respectively. The phosphine mixture was a mixture of phosphine and hydrogen, with a volume percentage concentration of approximately 10% for phosphine.

[0072] Nitrogen gas was introduced into the fluidized bed at a flow rate of 10 L / min to heat the reactor to 680 degrees Celsius and then held at that temperature for 20 min for annealing. The temperature was then lowered to 600 degrees Celsius, and nitrogen and acetylene were introduced into the reactor at flow rates of 10 L / min and 3 L / min, respectively. The reaction was carried out for 2 h to form the first coating layer (carbon coating layer) on the surface of the silicon-carbon single particles. After cooling, the silicon-carbon anode material was obtained.

[0073] Figure 2 shows the XRD pattern of the silicon-carbon anode material prepared in Example 1. The absence of silicon peaks in the XRD pattern indicates that the silicon in this material is amorphous silicon. Figure 2 was obtained using a Rikka X-ray diffractometer Ultima IV. Figure 3 shows the SEM image of the silicon-carbon anode material prepared in Example 1.

[0074] The porous carbon described in this application embodiment can be any commercially available porous carbon, and the specific surface area (BET) of the porous carbon is 1664.5 m². 3 / g, D50 is 8μm, tap density is 0.46g / cm³ 3 Other embodiments also use the same porous carbon.

[0075] Example 2

[0076] 1 kg of porous carbon was added to a fluidized bed reactor. The reactor was evacuated to a pressure below 100 Pa. Then, an inert gas (nitrogen) was introduced into the reactor until the pressure reached atmospheric pressure and maintained for 10 min. At a temperature of 0.11 MPa and 550 °C, a mixed gas (including a mixture of nitrogen, silane, and borane) was introduced and reacted for 4 h. P-doped nanocrystalline amorphous silicon was deposited in the pores of the porous carbon to form silicon-carbon single particles. The flow rates of nitrogen, silane, and borane in the mixed gas were 9 L / min, 5 L / min, and 1 L / min, respectively. The borane mixture was a mixture of borane and hydrogen with a borane concentration of approximately 10%.

[0077] Nitrogen gas was introduced into the fluidized bed at a flow rate of 10 L / min to heat the reactor to 680 degrees Celsius and then held at that temperature for 20 min for annealing. The temperature was then lowered to 600 degrees Celsius, and nitrogen and acetylene were introduced into the reactor at flow rates of 10 L / min and 3 L / min, respectively. The reaction was carried out for 2 h to form the first coating layer (carbon coating layer) on the surface of the silicon-carbon single particles. After cooling, the silicon-carbon anode material was obtained.

[0078] Example 3

[0079] 1 kg of porous carbon was added to a fluidized bed reactor. The reactor was evacuated to a pressure below 100 Pa. Then, an inert gas (nitrogen) was introduced into the reactor until the pressure was at atmospheric pressure and maintained for 10 min. At a temperature of 0.11 MPa and 550 °C, a mixed gas (including nitrogen and silane) was introduced and reacted for 4 h to deposit intrinsic amorphous silicon nanoparticles in the pores of the porous carbon. The flow rates of nitrogen and silane in the mixed gas were 9 L / min and 5 L / min, respectively.

[0080] After cooling, the porous carbon containing intrinsic amorphous silicon nanoparticles deposited within the pores is placed in an ion implanter under a nitrogen protective atmosphere. Phosphorus ions are then implanted into the intrinsic amorphous silicon nanoparticles to form silicon-carbon single particles. The phosphorus ion implantation energy is 800 keV, and the implantation dose is 10. 20 cm -2 .

[0081] Silicon-carbon single particles were placed in a rotary furnace under a nitrogen protective atmosphere. Nitrogen was introduced at a flow rate of 6 L / min, and the temperature inside the rotary furnace was raised to 680 degrees Celsius and held at that temperature for 20 min for annealing. Then, the temperature was lowered to 600 degrees Celsius, and nitrogen and acetylene were introduced into the rotary furnace at flow rates of 6 L / min and 3 L / min, respectively. The reaction was carried out for 2 h, and the first coating layer (carbon coating layer) was formed on the surface of the silicon-carbon single particles. After cooling, the silicon-carbon anode material was obtained.

[0082] Example 4

[0083] 1 kg of porous carbon was added to a fluidized bed reactor. The reactor was evacuated to a pressure below 100 Pa. Then, an inert gas (nitrogen) was introduced into the reactor until the pressure was at atmospheric pressure and maintained for 10 min. At a temperature of 0.11 MPa and 550 °C, a mixed gas (including nitrogen and silane) was introduced and reacted for 4 h to deposit intrinsic amorphous silicon nanoparticles in the pores of the porous carbon. The flow rates of nitrogen and silane in the mixed gas were 9 L / min and 5 L / min, respectively.

[0084] After cooling, the porous carbon containing intrinsic amorphous silicon nanoparticles deposited within the pores is placed in an ion implanter under a nitrogen protective atmosphere. Boron ions are then implanted into the intrinsic amorphous silicon nanoparticles to form silicon-carbon single particles. The implantation energy of the boron ions is 800 keV, and the implantation dose is 10.20 cm -2 .

[0085] Silicon-carbon single particles were placed in a rotary furnace under a nitrogen protective atmosphere. Nitrogen was introduced at a flow rate of 6 L / min, and the temperature inside the rotary furnace was raised to 680 degrees Celsius and held at that temperature for 20 min for annealing. Then, the temperature was lowered to 600 degrees Celsius, and nitrogen and acetylene were introduced into the rotary furnace at flow rates of 6 L / min and 3 L / min, respectively. The reaction was carried out for 2 h, and the first coating layer (carbon coating layer) was formed on the surface of the silicon-carbon single particles. After cooling, the silicon-carbon anode material was obtained.

[0086] Example 5

[0087] 1 kg of porous carbon was added to a fluidized bed reactor. The reactor was evacuated to a pressure below 100 Pa. Then, an inert gas (nitrogen) was introduced into the reactor until the pressure was at atmospheric pressure and maintained for 10 min. At a temperature of 0.11 MPa and 550 °C, a mixed gas (including nitrogen and silane) was introduced and reacted for 4 h to deposit intrinsic amorphous silicon nanoparticles in the pores of the porous carbon. The flow rates of nitrogen and silane in the mixed gas were 9 L / min and 5 L / min, respectively.

[0088] After cooling, the porous carbon deposited in the intrinsic state nano-amorphous silicon is placed in a tube diffusion furnace under a nitrogen protective atmosphere. A phosphine mixed gas (a mixture of phosphine and hydrogen with a phosphine concentration of about 3%) is introduced at a flow rate of 3 L / min and diffused for 5 hours at a diffusion temperature of 580 degrees Celsius. The intrinsic state nano-polycrystalline silicon is doped with the phosphine mixed gas to form silicon-carbon single particles.

[0089] Silicon-carbon single particles were placed in a rotary furnace under a nitrogen protective atmosphere. Nitrogen was introduced at a flow rate of 6 L / min, and the temperature inside the rotary furnace was raised to 680 degrees Celsius and held at that temperature for 20 min for annealing. Then, the temperature was lowered to 600 degrees Celsius, and nitrogen and acetylene were introduced into the rotary furnace at flow rates of 6 L / min and 3 L / min, respectively. The reaction was carried out for 2 h, and the first coating layer (carbon coating layer) was formed on the surface of the silicon-carbon single particles. After cooling, the silicon-carbon anode material was obtained.

[0090] Example 6

[0091] 1 kg of porous carbon was added to a fluidized bed reactor. The reactor was evacuated to a pressure below 100 Pa. Then, an inert gas (nitrogen) was introduced into the reactor until the pressure was at atmospheric pressure and maintained for 10 min. At a temperature of 0.11 MPa and 550 °C, a mixed gas (including nitrogen and silane) was introduced and reacted for 4 h to deposit intrinsic amorphous silicon nanoparticles in the pores of the porous carbon. The flow rates of nitrogen and silane in the mixed gas were 9 L / min and 5 L / min, respectively.

[0092] After cooling, the porous carbon deposited in the intrinsic state nano-amorphous silicon is placed in a tube diffusion furnace under a nitrogen protective atmosphere, and a borane mixed gas (a mixture of phosphine and hydrogen with a borane concentration of about 5%) is introduced at a flow rate of 3 L / min. After diffusion for 5 hours, the intrinsic state nano-polycrystalline silicon is doped with the phosphine mixed gas to form silicon-carbon single particles.

[0093] Silicon-carbon single particles were placed in a tube diffusion furnace under a nitrogen protective atmosphere. Nitrogen was introduced at a flow rate of 6 L / min, and the temperature inside the rotary furnace was raised to 680 degrees Celsius and held at that temperature for 20 min for annealing. Then, the temperature was lowered to 600 degrees Celsius, and nitrogen and acetylene were introduced into the rotary furnace at flow rates of 6 L / min and 3 L / min, respectively. The reaction was carried out for 2 h, and the first coating layer (carbon coating layer) was formed on the surface of the silicon-carbon single particles. After cooling, the silicon-carbon anode material was obtained.

[0094] Comparative Example 1

[0095] 1 kg of porous carbon was added to a fluidized bed reactor. The reactor was evacuated to a pressure below 100 Pa. Then, an inert gas (nitrogen) was introduced into the reactor until the pressure reached atmospheric pressure and maintained for 10 min. At 0.11 MPa and 550 °C, a mixed gas (including nitrogen and silane) was introduced and reacted for 4 h, depositing intrinsic amorphous silicon nanoparticles within the pores of the porous carbon. The flow rates of nitrogen and silane in the mixed gas were 9 L / min and 5 L / min, respectively. The reactor was then heated to 600 °C with nitrogen, and carbon coating was performed for 2 h at nitrogen and acetylene flow rates of 10 L / min and 3 L / min, respectively, to form a silicon-carbon anode material.

[0096] Comparative Example 2

[0097] 1 kg of porous carbon was added to a fluidized bed reactor. The reactor was evacuated to a pressure below 100 Pa. Then, an inert gas (nitrogen) was introduced into the reactor until the pressure reached atmospheric pressure and maintained for 10 min. At a temperature of 0.11 MPa and 550 °C, a mixed gas (including a mixture of nitrogen, silane, and borane) was introduced and reacted for 4 h. B-doped nanocrystalline amorphous silicon was deposited in the pores of the porous carbon to form silicon-carbon single particles. The flow rates of nitrogen, silane, and borane in the mixed gas were 9 L / min, 5 L / min, and 1 L / min, respectively. The borane mixture was a mixture of borane and hydrogen with a borane concentration of approximately 10%.

[0098] Nitrogen gas was introduced into the fluidized bed at a flow rate of 10 L / min to heat the reactor to 680 degrees Celsius and then held at that temperature for 20 min for annealing. The temperature was then lowered to 600 degrees Celsius, and nitrogen and acetylene were introduced into the reactor at flow rates of 10 L / min and 3 L / min, respectively. The reaction was carried out for 2 h to form the first coating layer (carbon coating layer) on the surface of the silicon-carbon single particles. After cooling, the silicon-carbon anode material was obtained.

[0099] The silicon-carbon anode materials prepared in Examples 1-6 and Comparative Examples 1-2 were tested using the following methods:

[0100] Electrochemical performance determination: The silicon-carbon anode materials prepared in Examples 1-6 and Comparative Examples 1-2 were coated onto copper foil and then vacuum dried and rolled to prepare anode sheets. A 1 mol / L LiPF6 three-component mixed solvent (ethyl carbonate: dimethyl carbonate: methyl ethyl carbonate) was mixed at a volume ratio of 1:1:1 to form the electrolyte. A polypropylene microporous membrane was used as the separator, and a lithium metal sheet was used as the positive electrode. Coin cells were assembled in an argon-filled inert gas glove box system. Charge-discharge tests were conducted on the coin cells using a battery testing system. Under room temperature conditions, constant current charge-discharge was performed at 0.1C, with the charge-discharge voltage limited to 0.005–1.5V. Cycle stability was determined by comparing the percentage of the initial specific capacity after 10 charge-discharge cycles under the same test conditions. A lower value indicates a faster capacity decrease and poorer cycle stability. Rate performance was assessed by charging at the same 0.1C rate but discharging at different rates under the same test conditions. Under normal temperature conditions, after constant current charge-discharge cycles at 0.1C, the capacity retention rate after 5 cycles at discharge rates of 0.2C, 0.5C, 1C, 2C, and 4C is as follows: the lower the capacity retention rate, the worse the rate performance.

[0101] The charge / discharge tests of the button batteries were conducted using the LAND battery testing system of Wuhan Landian Electronics Co., Ltd. The electrical performance data are shown in Tables 1 and 2. The Hall coefficient of the material was measured using an Ecopia HMS-7000 Hall effect tester; the Hall coefficient RHSi of intrinsic semiconductor silicon was 16 × 10⁻⁶. 3 cm 3 / C, the doping effect W was calculated, Table 1; the C content in the material was measured using a CS844 Leco CS analyzer, see Table 1; the doping concentration in the material was measured using Thermo iCAP6300 inductively coupled plasma mass spectrometry (ICP-MS), see Table 1; the Si content in the silicon-carbon anode material was measured using the ignition method (GB / T 38823-2020), see Table 1; the specific surface area of ​​the material was measured using a Konta NOVA touch™ fully automated specific surface area and pore size analyzer, see Table 1.

[0102] Table 1

[0103] Table 2

[0104] Table 1 shows that, with the same amount of silicon deposited, the capacity efficiency of the formed silicon-carbon anode material remains at a similar level, with the initial charge specific capacity ranging from 2019.6 mAh / g to 2049.5 mAh / g and the initial coulombic efficiency from 88.1% to 89.1%. Doping with a small amount of the dopant element does not affect the initial charge capacity and efficiency of the silicon-carbon anode material. In Comparative Example 2, where the dopant element content exceeds 10% (reaching 10.2%), the initial charge specific capacity decreases to 1794.5 mAh / g, and the initial coulombic efficiency also decreases to 84.8%. Because the dopant element lacks lithium intercalation activity, it has a negative effect on the structural stability and other properties of the silicon-carbon anode material. Excessive doping should not be pursued simply to improve conductivity.

[0105] In Examples 1-6, after doping the amorphous silicon in the silicon-carbon anode material, the carrier concentration range in the silicon-carbon anode material is 6.4 × 10⁻⁶. 17 ~2.3×10 19 The carrier concentration in the undoped silicon-carbon anode material in Comparative Example 1 was 3.4 × 10⁻⁶. 16 This indicates that the doping element can significantly increase the carrier concentration of the silicon-carbon anode material.

[0106] In Examples 1-6, the doping amount, i.e., the proportion of the doped element by mass, is positively correlated with the carrier concentration of the silicon-carbon anode material. The higher the doping amount, the higher the carrier concentration.

[0107] In Examples 1-6, the beneficial doping coefficient and carrier concentration of the silicon-carbon anode material are not positively correlated because T is a comprehensive indicator of carrier concentration, effective doping, and the negative effects of doping. For example, in Example 1, the carrier concentration is 1.9 × 10⁻⁶. 19 T is 38.32; the carrier concentration in Example 2 is 2.3 × 10⁻⁶. 19 T is 38.25; the carrier concentration of Example 1 is lower than that of Example 2, and the beneficial doping coefficient T is higher than that of Example 2, indicating that the doping effect of Example 1 is better.

[0108] Table 2 shows that after Examples 1-6 and Comparative Examples 1-2 were cycled 5 times at discharge rates of 0.2C, 0.5C, 1C, 2C, and 4C respectively, the capacity retention decreased as the discharge rate increased. However, when Examples 1-6 were cycled at discharge rates of 0.2C, 0.5C, and 1C, the capacity retention remained relatively constant. This indicates that there is no significant difference in fast charging performance at low discharge rates.

[0109] Significant differences were observed in capacity retention when Examples 1-6 and Comparative Examples 1-2 were cycled at 2C and 4C discharge rates. At 4C discharge rate cycling, the capacity retention of the doped silicon-carbon anode material in Examples 1-6 ranged from 36.52% to 45.37%; the capacity retention of the over-doped silicon-carbon anode material in Comparative Example 2 was 24.43%; and the capacity retention of the undoped silicon-carbon anode material in Comparative Example 1 was 27.24%. This demonstrates that efficient and beneficial doping of the silicon-carbon anode material can improve its fast-charging performance.

[0110] In Examples 1-6, the beneficial doping coefficient T and capacity retention are positively correlated. A larger beneficial doping coefficient T corresponds to a higher capacity retention. The beneficial doping coefficient T reflects the improvement in fast-charging performance of the silicon-carbon anode material after doping modification.

[0111] As described above, the fast-charging performance of the silicon-carbon anode materials prepared in Examples 1 to 6 of this application is significantly improved.

[0112] Finally, it should be understood that the embodiments disclosed herein are illustrative of the principles of the embodiments of this application. Other modified embodiments are also within the scope of this application. Therefore, the embodiments disclosed herein are merely examples and not limitations. Those skilled in the art can implement the applications in this application by adopting alternative configurations based on the embodiments in this application. Therefore, the embodiments of this application are not limited to those embodiments precisely described in the application.

Claims

1. A silicon-carbon anode material, characterized in that, include: The silicon-carbon single particle comprises a carbon matrix and doped amorphous silicon. The carbon matrix includes a carbon skeleton and channels located inside the carbon skeleton. The doped amorphous silicon partially fills the channels. The beneficial doping coefficient of the doping element in the doped amorphous silicon is greater than or equal to 25 and less than or equal to 48. The beneficial doping coefficient is determined by the carrier concentration in the silicon-carbon anode material and the mass ratio of the doping element in the doped amorphous silicon. The first coating layer is a carbon coating layer that coats the surface of the silicon-carbon single particle.

2. The silicon-carbon anode material according to claim 1, characterized in that, The beneficial doping coefficient Where n is the carrier concentration in the silicon-carbon anode material, and the value of n ranges from 10. 12 ~10 22 cm -3 w% represents the mass percentage of doped elements in the silicon-carbon anode material, and the value of w% ranges from 0.02% to 10%.

3. The silicon-carbon anode material according to claim 1, characterized in that, The doping element in the doped amorphous silicon includes at least one of phosphorus, antimony, and arsenic; or the doping element in the doped amorphous silicon includes at least one of boron, gallium, and indium.

4. The silicon-carbon anode material according to claim 1, characterized in that, The carbon framework includes hard carbon and carbon allotropes, including graphite, amorphous carbon, diamond, C60, carbon nanotubes, graphene, and / or carbon fibers.

5. The silicon-carbon anode material according to claim 1, characterized in that, The silicon-carbon anode material contains 30% to 80% silicon by mass.

6. A method for preparing a silicon-carbon anode material, characterized in that, include: A carbon matrix is ​​provided, the carbon matrix including a carbon skeleton and channels located inside the carbon skeleton, and doped amorphous silicon is deposited in the channels to form silicon-carbon single particles. The beneficial doping coefficient of the doping element in the doped amorphous silicon is greater than or equal to 25 and less than or equal to 48. The beneficial doping coefficient is determined by the carrier concentration in the silicon-carbon anode material and the mass ratio of the doping element in the doped amorphous silicon. A first carbon source gas is provided, which forms a first coating layer on the surface of the silicon-carbon single particle. The first coating layer is a carbon coating layer that coats the surface of the silicon-carbon single particle.

7. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The method for depositing doped amorphous silicon in the channel includes: simultaneously introducing silicon source gas and doping gas into the deposition chamber, and depositing doped amorphous silicon in the channel by chemical vapor deposition process.

8. The method for preparing the silicon-carbon anode material according to claim 7, characterized in that, The silicon source gas includes silane gases, and the doping gas includes at least one gaseous compound of phosphorus, antimony, and arsenic, or the doping gas includes at least one gaseous compound of boron, gallium, and indium.

9. The method for preparing the silicon-carbon anode material according to claim 8, characterized in that, The volume ratio of the silane gas to the dopant gas is 1:(0.02~1); the chemical vapor deposition temperature is 400℃~900℃, and the time is greater than 0.5 hours.

10. The method for preparing the silicon-carbon anode material according to claim 7, characterized in that, The carrier gas is mixed with the silicon source gas and then introduced into the deposition chamber simultaneously with the doping gas. The carrier gas content is 10% to 99%.

11. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The method for depositing doped amorphous silicon in the channel includes: introducing silicon source gas into the deposition chamber, depositing intrinsic amorphous silicon in the channel by chemical vapor deposition; and implanting doped ions into the intrinsic amorphous silicon by ion implantation.

12. The method for preparing the silicon-carbon anode material according to claim 11, characterized in that, The silicon source gas includes silane gases, and the doping ions include at least one of boron ions, phosphorus ions, antimony ions, gallium ions, indium ions, and arsenic ions.

13. The method for preparing the silicon-carbon anode material according to claim 12, characterized in that, In the ion implantation method, the ion implantation energy is 1kV to 900kV.

14. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The method for depositing doped amorphous silicon in the channel includes: introducing silicon source gas into the deposition chamber, depositing intrinsic amorphous silicon in the channel by chemical vapor deposition; and incorporating dopant atoms from the dopant source into the intrinsic amorphous silicon by ion diffusion.

15. The method for preparing the silicon-carbon anode material according to claim 14, characterized in that, The doping source includes at least one of a solid-phase source, a liquid-phase source, and a gas-phase source. The solid-phase source includes As2O3, P2O5, and BN. The liquid-phase source includes AsAl, B(OCH3)3, and POCl3. The gas-phase source includes AsH3, BH5, and PH3.

16. The method for preparing the silicon-carbon anode material according to claim 15, characterized in that, In the ion diffusion method, the diffusion temperature is 500–1200℃ and the diffusion time is 10s–5h.

17. The method for preparing silicon-carbon anode material according to claim 7, 11, or 14, characterized in that, The method further includes: performing an annealing treatment, wherein the annealing treatment is carried out in a hydrogen or inert atmosphere, the annealing temperature is 650℃~1200℃, and the annealing time is 10s~10h.

18. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The first carbon source gas includes at least one of acetylene, methane, ethylene, propane, and propylene, and the reaction temperature for forming the first coating layer is 300–800°C.

19. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The particle size of the doped amorphous silicon is 0.2 nm to 5 nm.

20. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The silicon-carbon anode material contains 30% to 80% silicon by mass.

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