Silicon-carbon negative electrode material and preparation method therefor
By depositing n-type doped amorphous silicon within the carbon framework channels and forming a silicon-carbon layer, the problems of insufficient conductivity and fast-charging performance of silicon-based anode materials are solved, and a silicon-carbon anode material with high conductivity and fast-charging performance is realized.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SHANGHAI SHANSHAN NEW MATERIAL CO LTD
- Filing Date
- 2024-12-31
- Publication Date
- 2026-07-09
AI Technical Summary
Existing silicon-based anode materials in lithium-ion batteries suffer from large volume expansion, poor conductivity and rate performance, and low initial charge and discharge efficiency, failing to meet the requirements for fast charging performance.
By depositing n-type doped amorphous silicon within the pores of a carbon framework and forming a silicon-carbon layer on the surface to increase the carrier concentration, and by using methods such as chemical vapor deposition and ion implantation to adjust the doping effect, n-type doped amorphous silicon is formed.
It significantly improves the conductivity and fast-charging performance of silicon-carbon anode materials, overcomes the problem of poor conductivity caused by low carrier concentration in existing technologies, and meets the fast-charging requirements of lithium-ion batteries.
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Figure CN2024144475_09072026_PF_FP_ABST
Abstract
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, as novel lithium-ion battery anode materials (theoretical specific capacity 4200 mAh / g), possess high specific capacity. 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, modifications are used to improve the performance of silicon-based anode materials, including nano-sizing, carbon-based composites, alloying, and conductive polymer composites. A novel method for preparing silicon-based anode materials utilizes chemical vapor deposition (CVD) with silane as a raw material. Nano-silicon is deposited in porous carbon and then coated with carbon to form a silicon-carbon anode material. This method effectively reduces the volume expansion during charge-discharge processes, resulting in 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, leading to poor kinetic performance of the resulting silicon-carbon anode material, which cannot meet the current market demand for fast-charging performance in lithium-ion batteries.
[0003] 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 new silicon-carbon anode material with strong conductivity, good kinetic performance, and low cost. Summary of the Invention
[0004] This application provides a silicon-carbon anode material and its preparation method. The method significantly improves the conductivity of amorphous silicon deposited in the carbon framework, thereby significantly improving the conductivity and fast-charging performance of the silicon-carbon anode material.
[0005] One aspect of this application provides a silicon-carbon anode material, comprising: silicon-carbon single particles, wherein the silicon-carbon single particles comprise a carbon matrix and n-type doped amorphous silicon, the carbon matrix comprises a carbon framework and channels located within the carbon framework, and the n-type doped amorphous silicon partially fills the channels, wherein the doping effect W of the n-type doped amorphous silicon in the silicon-carbon anode material is greater than or equal to 1 and less than or equal to 10. 4 The doping effect W is determined by the Hall coefficient R of the silicon-carbon anode material. H Hall coefficient R of intrinsic silicon HSi Confirmed; First coating layer, the first coating layer is a silicon-carbon layer, which coats the surface of the silicon-carbon single particle.
[0006] In some embodiments of this application, the doping effect is |R HSi / R H|
[0007] In some embodiments of this application, the doping element in the n-type doped amorphous silicon includes at least one of phosphorus, antimony, and arsenic, and the mass percentage of the doping element in the total mass of the silicon-carbon anode material is 0.01% to 8%.
[0008] In some embodiments of this application, the carbon skeleton includes hard carbon and carbon allotropes, including graphite, amorphous carbon, diamond, C60, carbon nanotubes, graphene, and carbon fibers.
[0009] In some embodiments of this application, the silicon-carbon anode material contains 25% to 75% silicon 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 n-type doped amorphous silicon in the channels to form silicon-carbon single particles; providing a first carbon source gas to form a first coating layer on the surface of the silicon-carbon single particles, the first coating layer being a silicon-carbon layer coating the surface of the silicon-carbon single particles; wherein the doping effect W of the n-type doped amorphous silicon in the silicon-carbon anode material is greater than or equal to 1 and less than or equal to 10. 4 The doping effect W is determined by the Hall coefficient R of the silicon-carbon anode material. H Hall coefficient R of intrinsic silicon HSi Sure.
[0011] In some embodiments of this application, the doping effect is |R HSi / R H |
[0012] In some embodiments of this application, the method for depositing n-type doped amorphous silicon within the channel includes: simultaneously introducing a silicon source gas and a dopant gas into a deposition chamber, and depositing n-type doped amorphous silicon within the channel using a chemical vapor deposition (CVD) process. The silicon source gas includes a silane gas, and the dopant gas includes at least one gaseous compound of phosphorus, antimony, and arsenic. The volume ratio of the silane gas to the dopant gas is 1:(0.01–0.5); the CVD deposition temperature is 300°C–800°C, and the deposition time is at least 1 hour.
[0013] 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. The volume of the carrier gas is 5% to 90% of the total volume of all the introduced reaction gases.
[0014] In some embodiments of this application, the method for depositing n-type doped amorphous silicon within the channel includes: introducing a silicon source gas into a deposition chamber, depositing intrinsic-state amorphous silicon within the channel using a chemical vapor deposition process, and implanting dopant ions into the intrinsic-state amorphous silicon using an ion implantation method. The silicon source gas includes silane-based gases, and the dopant ions include at least one selected from phosphorus ions, antimony ions, and arsenic ions. In the ion implantation method, the ion implantation energy is 2 kV to 1000 kV.
[0015] In some embodiments of this application, the method for depositing n-type doped amorphous silicon within the channel includes: introducing a silicon source gas into a deposition chamber, depositing intrinsic amorphous silicon within the channel using a chemical vapor deposition process; and incorporating dopant atoms from a dopant source into the intrinsic amorphous silicon using ion diffusion. The dopant 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 and P₂O₅, the liquid-phase source includes AsAl and POCl₃, and the gas-phase source includes AsH₃ and PH₃. In the ion diffusion method, the diffusion temperature is 400–1100°C, and the diffusion time is 1 s–4 h.
[0016] In some embodiments of this application, the preparation method of the silicon-carbon anode material further includes: performing an annealing treatment, wherein the annealing treatment is carried out under hydrogen or an inert atmosphere, the annealing temperature is 600℃~1100℃, and the annealing time is 1s~8h.
[0017] 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 200–700°C.
[0018] In some embodiments of this application, the particle size of the n-type doped amorphous silicon is 0.1 nm to 4 nm.
[0019] In some embodiments of this application, the silicon-carbon anode material contains 25% to 75% silicon by mass.
[0020] Compared with the prior art, the present invention has at least the following beneficial effects:
[0021] The silicon-carbon anode material provided in this application fills the channels inside the carbon framework with n-type doped amorphous silicon, wherein the doping effect W of the n-type doped amorphous silicon in the silicon-carbon anode material is greater than or equal to 1 and less than or equal to 10. 4 The doping effect W is determined by the Hall coefficient R of the silicon-carbon anode material. H Hall coefficient R of intrinsic silicon HSiIt has been determined that by adjusting the doping effect of the silicon-carbon anode material, increasing the concentration of charge carriers (i.e., free electrons), the conductivity of the silicon-carbon anode material is enhanced, 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 charge carrier concentration and poor conductivity, which leads to poor kinetic performance of the silicon-carbon anode material and fails to meet the current market demand for fast-charging performance of lithium-ion batteries.
[0022] Furthermore, n-type semiconductors have a higher concentration of free electrons, while p-type semiconductors have a higher concentration of holes. Because electrons have a higher mobility than holes, n-type semiconductors have better conductivity than p-type semiconductors. This application uses n-type doped amorphous silicon, which more effectively improves the fast-charging performance of the material by doping with group 5 dopants.
[0023] By measuring the Hall coefficient of the silicon-carbon anode material formed in this embodiment and comparing it with the Hall coefficient of silicon-carbon anode materials formed in the prior art, it can be found that the Hall effect of the silicon-carbon anode material formed in this embodiment is reduced, which can significantly improve the fast charging performance of the material both theoretically and practically. Attached Figure Description
[0024] 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:
[0025] Figure 1 is a process flow diagram of the preparation method of silicon-carbon anode material according to an embodiment of this application;
[0026] Figure 2 shows the XRD pattern of the silicon-carbon anode material prepared in Example 1. Detailed Implementation
[0027] 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.
[0028] To improve the conductivity of semiconductor materials, a certain amount of impurities is typically incorporated into the semiconductor material to increase the carrier concentration and improve its electrical properties. Intrinsic semiconductors, after doping, are classified into n-type and p-type semiconductors. In n-type semiconductors, free electrons are the majority carriers, while holes are the minority carriers. This means that the electron concentration is higher and the hole concentration is lower in n-type semiconductors. In p-type semiconductors, holes are the majority carriers, while free electrons are the minority carriers. This means that the hole concentration is higher and the electron concentration is lower in p-type semiconductors, and p-type semiconductors primarily rely on holes for conductivity. Because the mobility of free electrons is greater than that of holes, n-type semiconductors have better conductivity than p-type semiconductors. In this application, the amorphous silicon deposited in the silicon-carbon anode material is doped to increase the concentration of carriers, i.e., free electrons, forming n-type doped amorphous silicon, thereby significantly improving the conductivity of the amorphous silicon, and consequently significantly improving the conductivity and fast-charging performance of the silicon-carbon anode material.
[0029] This application provides a silicon-carbon anode material, comprising: silicon-carbon single particles, wherein each silicon-carbon single particle includes a carbon matrix and n-type doped amorphous silicon, the carbon matrix includes a carbon framework and channels located within the carbon framework, and the n-type doped amorphous silicon partially fills the channels; and a first coating layer, the first coating layer being a silicon-carbon layer coating the surface of the silicon-carbon single particles, wherein the doping effect W of the n-type doped amorphous silicon in the silicon-carbon anode material is greater than or equal to 1 and less than or equal to 10. 4 The doping effect W is determined by the Hall coefficient R of the silicon-carbon anode material. H Hall coefficient R of intrinsic silicon HSi Confirmed. Optionally, the doping effect is |R HSi / R H |
[0030] 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 .
[0031] 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 n-type doped amorphous silicon; that is, the n-type doped amorphous silicon fills 70% to 99% of the channels. The n-type 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.
[0032] In some embodiments of this application, the carbon skeleton includes hard carbon and carbon allotropes, including graphite, amorphous carbon, diamond, C60, carbon nanotubes, graphene, and carbon fibers.
[0033] In some embodiments of this application, the size of the n-type doped amorphous silicon particles is 0.1 nm to 4 nm. Optionally, the size of the n-type 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.
[0034] In some embodiments of this application, the doping element in the n-type doped amorphous silicon includes at least one of phosphorus, antimony, and arsenic, and the mass percentage of the doping element in the total mass of the silicon-carbon anode material is 0.01% to 8%, for example, 0.05%, 1%, 3%, 5%, 7%, etc. Since the atomic radius of phosphorus is more similar to that of silicon, phosphorus is more preferably used as the doping element.
[0035] The n-type doped amorphous silicon-carbon anode material is deposited within the channels, and its doping effect is denoted as W = |R|. HSi / R H | where W ranges from 1 to 10 4 The larger the value of W, the better the doping effect and conductivity. H R is the Hall coefficient of the silicon-carbon anode material. HSi The Hall coefficient of intrinsic silicon is given.
[0036] In some embodiments of this application, the silicon-carbon anode material contains 25% to 75% silicon by mass, preferably 35% to 65%, such as 45%, 48%, 53%, etc.
[0037] The silicon-carbon anode material described in this embodiment further includes a first coating layer, which is a silicon-carbon 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, while limiting the volume expansion of silicon in the battery prepared using the silicon-carbon anode material during charge-discharge cycles, thus significantly improving the cycle performance of the material.
[0038] Referring to Figure 1, the preparation method of the silicon-carbon anode material according to an embodiment of this application includes the following steps:
[0039] Step S1: Provide a carbon matrix, the carbon matrix including a carbon skeleton and channels located inside the carbon skeleton, and deposit n-type doped amorphous silicon in the channels to form silicon-carbon single particles;
[0040] A carbon matrix is provided, comprising a carbon framework and channels located within the carbon framework. A silicon-containing precursor is used as the silicon source and introduced into a reaction chamber. n-type doped amorphous silicon is deposited within the channels using a chemical vapor deposition process to form silicon-carbon single particles, wherein the n-type 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.
[0041] In some embodiments of this application, the carbon skeleton includes hard carbon and carbon allotropes, including graphite, amorphous carbon, diamond, C60, carbon nanotubes, graphene, and carbon fibers.
[0042] 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.
[0043] In some embodiments of this application, the size of the n-type doped amorphous silicon particles is 0.1 nm to 4 nm. Optionally, the size of the n-type 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 to the total volume after the n-type doped amorphous silicon is deposited in the channels.
[0044] In some embodiments of this application, the method for depositing n-type doped amorphous silicon in the channel includes: simultaneously introducing silicon source gas and doping gas into the deposition chamber, and depositing n-type doped amorphous silicon in the channel by chemical vapor deposition.
[0045] In this embodiment, the silicon source gas includes silane gases, and the dopant gas includes at least one gaseous compound of phosphorus, antimony, and arsenic, such as phosphine (PH3) and arsine (AsH3). The volume ratio of the silane gas to the dopant gas is 1:(0.01–0.5); the chemical vapor deposition temperature is 300°C–800°C, and the deposition time is 1 hour or more.
[0046] 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 600 degrees Celsius 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 degrees Celsius, thereby generating n-type doped amorphous silicon within the pores of the porous carbon, forming the silicon-carbon single particles.
[0047] In some other embodiments of this application, the carrier gas may 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 5% to 90% of the total volume of all introduced reaction gases. The carrier gas may be at least one of nitrogen, hydrogen, helium, neon, argon, krypton, and xenon.
[0048] In some embodiments of this application, the method for depositing n-type doped amorphous silicon within the channel includes:
[0049] A silicon source gas is introduced into the deposition chamber, and intrinsic amorphous silicon is deposited within the channels 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 reaction chamber. The trichlorosilane reacts with the porous carbon at 650°C for 3 hours. After the trichlorosilane is adsorbed onto the surface of the channels, it undergoes thermal decomposition within the channels at 650°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 then introduced into the deposition chamber. The volume of the carrier gas is 5% to 90% of the total volume of all introduced reaction gases, for example, 20%, 30%, 40%, 50%, 60%, 70%, and 80%.
[0050] The intrinsic amorphous silicon is an amorphous solid with non-periodic atomic arrangement. 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. This process introduces a large number of hydrogen atoms, which inhibit the formation of a long-range ordered crystal structure in the silicon atoms. This process disrupts the periodic arrangement of atoms in the silicon crystal, resulting in an amorphous state and thus altering 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.
[0051] 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 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 then 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 in a controllable manner into the intrinsic amorphous silicon deposited within the channels, thereby forming n-type doped amorphous silicon. The ion implanter can inject plasma at an implantation energy of 2kV to 1000kV. 17 ~10 20 ion / cm 2 The silicon deposited within the pore is implanted at an implantation rate of 2 kV to 1000 kV per hour.
[0052] In some embodiments of this application, the method for depositing n-type doped amorphous silicon within the channel includes:
[0053] 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 reaction chamber. The tetrasilane reacts with the porous carbon at 700 degrees Celsius for 5 hours. After the tetrasilane is adsorbed onto the surface of the pores, it undergoes thermal decomposition inside the pores at 700 degrees Celsius, thereby generating intrinsic amorphous silicon within the pores of the porous carbon. In some other embodiments of this application, a carrier gas can also be mixed with the silicon source gas and introduced into the deposition chamber, wherein the volume of the carrier gas is 5% to 90% of the total volume of all introduced reaction gases.
[0054] 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 its conductivity type and impurity 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 400℃ to 1100℃. 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 4 hours.
[0055] 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 and P₂O₅, the liquid-phase source includes AsAl and POCl₃, and the gas-phase source includes AsH₃ and PH₃. In the ion diffusion method, the diffusion temperature is 400–1100℃, and the diffusion time is 1 s–5 h.
[0056] In some embodiments of this application, after forming n-type 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 also 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 600℃ to 1100℃ for 1 second to 8 hours. In some embodiments of this application, the particle size of the n-type doped amorphous silicon is 0.1 nm to 4 nm.
[0057] 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 silicon-carbon layer that coats the surface of the silicon-carbon single particle. Wherein, the doping effect W of the n-type doped amorphous silicon in the silicon-carbon anode material is greater than or equal to 1 and less than or equal to 10. 4 The doping effect W is determined by the Hall coefficient R of the silicon-carbon anode material. H Hall coefficient R of intrinsic silicon HSi Confirmed. Optionally, the doping effect is |R HSi / R H |
[0058] 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 200–700°C; and the reaction time is 0.1–5 h.
[0059] The Hall effect refers to the phenomenon where, under an applied magnetic field, charge carriers in a conductive material are deflected by the Lorentz force, causing opposite charges to accumulate at the ends of the material perpendicular to the magnetic field. Furthermore, when the applied magnetic field, current, and temperature are constant, the number of charges accumulated at the ends of the parallel magnetic field reaches a stable level, thus generating a constant voltage V. H This is called Hall voltage, V H =IBR H / t, where V H Units are V, t is the sample thickness in meters, I is the current passing through the sample in amperes (A), and B is the magnetic flux density in wb / m³. 2 ;R H The Hall coefficient is related to the properties of the material and is measured in meters (m). 3 / C or cm 3 / C. The Hall coefficient is a physical quantity describing the strength of the Hall effect; it represents the proportional relationship between the Hall potential difference and the excitation current and magnetic flux density. The magnitude of the Hall coefficient is directly proportional to the product of the resistivity ρ and the electron mobility μ of the Hall element material, i.e., R. H =μ×ρ. Generally, material R H The higher the value, the greater the resistivity ρ, and the worse the conductivity.
[0060] In a semiconductor, when a magnetic field is applied, charge carriers (electrons or holes) are deflected by the Lorentz force, creating a potential difference across the semiconductor, known as the Hall voltage. Measuring this Hall voltage determines whether the semiconductor is n-type or p-type. For p-type semiconductors, the primary charge carriers are holes. Under the influence of a magnetic field, holes deflect in one direction, resulting in a positive charge accumulation on the other side of the semiconductor, forming a positive Hall voltage. For n-type semiconductors, the primary charge carriers are electrons. Under the influence of a magnetic field, electrons deflect in the opposite direction, resulting in a negative charge accumulation on the other side of the semiconductor, forming a negative Hall voltage.
[0061] The silicon-carbon anode material with channels filled with n-type doped amorphous silicon formed using the embodiments of this application has a Hall coefficient R. H The range is -10 -3 ~10 4 cm 3 / C, resistivity ρ is 10 -3 ~10 2 Ω·cm.
[0062] In some embodiments of this application, the silicon-carbon anode material contains 25% to 75% silicon by mass.
[0063] Example 1
[0064] 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 10 L / min, 5 L / min, and 2 L / min, respectively. The phosphine mixture was a mixture of phosphine and hydrogen, with a phosphine concentration of approximately 5%.
[0065] Nitrogen gas was introduced into the fluidized bed at a flow rate of 10 L / min to heat the reactor to 700 degrees Celsius and then held at that temperature for 10 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 2 L / min, respectively. The reaction was carried out for 3 h to form the first coating layer (silicon-carbon layer) on the surface of the silicon-carbon single particles. After cooling, silicon-carbon anode material doped with n-type doped amorphous silicon was obtained.
[0066] Figure 2 shows the XRD pattern of the silicon-carbon anode material prepared in Example 1. The XRD pattern of Example 2 shows no silicon peaks, indicating that the silicon in this material is amorphous silicon. Figure 2 was obtained using a Rikka X-ray diffractometer Ultima IV from Japan.
[0067] Example 2
[0068] 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 10 L / min, 5 L / min, and 4 L / min, respectively. The phosphine mixture was a mixture of phosphine and hydrogen, with a phosphine concentration of approximately 5%.
[0069] Nitrogen gas was introduced into the fluidized bed at a flow rate of 10 L / min to heat the reactor to 700 degrees Celsius and then held at that temperature for 10 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 2 L / min, respectively. The reaction was carried out for 3 h to form the first coating layer (silicon-carbon layer) on the surface of the silicon-carbon single particles. After cooling, silicon-carbon anode material doped with n-type doped amorphous silicon was obtained.
[0070] Example 3
[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 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 nano-amorphous silicon in the pores of the porous carbon. The flow rates of nitrogen and silane in the mixed gas were 10 L / min and 5 L / min, respectively.
[0072] 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 polycrystalline silicon nanoparticles to form silicon-carbon single particles. The phosphorus ion implantation energy is 900 keV, and the implantation dose is 5 × 10⁻⁶. 19 cm -2 .
[0073] Silicon-carbon single particles were placed in a rotary furnace under a nitrogen protective atmosphere, and nitrogen was introduced at a flow rate of 6 L / min. The temperature inside the rotary furnace was raised to 700 degrees Celsius and held at that temperature for 10 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 2 L / min, respectively. The reaction was carried out for 3 h, and a first coating layer (silicon-carbon layer) was formed on the surface of the silicon-carbon single particles. After cooling, silicon-carbon anode material doped with n-type doped amorphous silicon was obtained.
[0074] Example 4
[0075] 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 nano-amorphous silicon in the pores of the porous carbon. The flow rates of nitrogen and silane in the mixed gas were 10 L / min and 5 L / min, respectively.
[0076] 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 polycrystalline silicon nanoparticles to form silicon-carbon single particles. The phosphorus ion implantation energy is 900 keV, and the implantation dose is 10. 20 cm -2 .
[0077] Silicon-carbon single particles were placed in a rotary furnace under a nitrogen protective atmosphere, and nitrogen was introduced at a flow rate of 6 L / min. The temperature inside the rotary furnace was raised to 700 degrees Celsius and held at that temperature for 10 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 2 L / min, respectively. The reaction was carried out for 3 h, and a first coating layer (silicon-carbon layer) was formed on the surface of the silicon-carbon single particles. After cooling, silicon-carbon anode material doped with n-type doped amorphous silicon was obtained.
[0078] Example 5
[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 nano-amorphous silicon in the pores of the porous carbon. The flow rates of nitrogen and silane in the mixed gas were 10 L / min and 5 L / min, respectively.
[0080] 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 5%) is introduced at a flow rate of 2 L / min and diffused for 4 hours at a diffusion temperature of 600 degrees Celsius. The intrinsic state nano-polycrystalline silicon is doped with the phosphine mixed gas to form silicon-carbon single particles.
[0081] Silicon-carbon single particles were placed in a tube diffusion furnace under a nitrogen protective atmosphere, and nitrogen was introduced at a flow rate of 6 L / min. The temperature inside the rotary furnace was raised to 700 degrees Celsius and held at that temperature for 10 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 2 L / min, respectively. The reaction was carried out for 3 h, and a first coating layer (silicon-carbon layer) was formed on the surface of the silicon-carbon single particles. After cooling, silicon-carbon anode material doped with n-type doped amorphous silicon was obtained.
[0082] Example 6
[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 nano-amorphous silicon in the pores of the porous carbon. The flow rates of nitrogen and silane in the mixed gas were 10 L / min and 5 L / min, respectively.
[0084] 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 5%) is introduced at a flow rate of 4 L / min. The diffusion temperature is 600 degrees Celsius, and the diffusion is carried out for 4 hours. The intrinsic state nano-polycrystalline silicon is doped with the phosphine mixed gas to form silicon-carbon single particles.
[0085] Silicon-carbon single particles were placed in a tube diffusion furnace under a nitrogen protective atmosphere, and nitrogen was introduced at a flow rate of 6 L / min. The temperature inside the rotary furnace was raised to 700 degrees Celsius and held at that temperature for 10 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 2 L / min, respectively. The reaction was carried out for 3 h, and a first coating layer (silicon-carbon layer) was formed on the surface of the silicon-carbon single particles. After cooling, silicon-carbon anode material doped with n-type doped amorphous silicon was obtained.
[0086] Comparative Example 1
[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 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 10 L / min and 5 L / min, respectively. The reactor was then heated to 600 °C by introducing nitrogen, and carbon coating was performed for 3 h at nitrogen and acetylene flow rates of 10 L / min and 2 L / min, respectively, to form a silicon-carbon anode material.
[0088] Comparative Example 2
[0089] 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 10 L / min, 5 L / min, and 2 L / min, respectively. The borane mixed gas was a mixture of borane and hydrogen, with a borane concentration of approximately 5%.
[0090] Nitrogen gas was introduced into the fluidized bed at a flow rate of 10 L / min to heat the reactor to 700 degrees Celsius and then held at that temperature for 10 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 2 L / min, respectively. The reaction was carried out for 3 h to form the first coating layer (silicon-carbon layer) on the surface of the silicon-carbon single particles. After cooling, silicon-carbon anode material doped with n-type doped amorphous silicon was obtained.
[0091] The silicon-carbon anode materials prepared in Examples 1-6 and Comparative Examples 1-2 were tested using the following methods:
[0092] 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.
[0093] 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.
[0094] Table 1
[0095] Table 2
[0096] Table 1 shows that, with the same amount of silicon deposited, the capacity efficiency of the resulting silicon-carbon anode material remains at a similar level, with an initial charge specific capacity of 2000 mAh / g to 2060 mAh / g and an initial coulombic efficiency of 88.7% to 94.4%. When the mass percentage of doped elements is less than one-thousandth, it does not affect the initial charge specific capacity and initial coulombic efficiency of the silicon-carbon anode material.
[0097] In Examples 1-6, the Hall coefficients of the silicon-carbon anode materials formed by doping silicon with phosphorus were negative, indicating that Examples 1-6 were all n-type doped amorphous silicon-carbon anode materials. The Hall coefficients of the silicon-carbon anode materials formed in Comparative Examples 1-2 were positive, indicating that doping silicon with boron resulted in p-type doped amorphous silicon.
[0098] In Examples 1-6, the Hall coefficient R of the silicon-carbon anode material formed by doping phosphorus into silicon is... H The obtained doping effect W ranged from 6.2 to 43.2; the doping effect W of the silicon-carbon anode material doped with B in Comparative Example 2 was 12.3; and the doping effect W of the silicon-carbon anode material obtained in Comparative Example 1 was 3.5. This indicates that doping the silicon-carbon anode material can improve its doping effect.
[0099] In Examples 1-6, the doping amount of the silicon-carbon anode materials formed by doping silicon with phosphorus ranged from 0.12‰ to 2.95‰. The higher the doping amount, the greater the doping effect (W value), showing a positive correlation. This indicates that increasing the doping amount of the n-type dopant can improve the doping effect.
[0100] Example 1 forms a P-doped n-type amorphous silicon-carbon anode material, while Comparative Example 2 forms a boron-doped p-type amorphous silicon-carbon anode material; the doping amounts of the two are 1.63 and 1.54, respectively, and the doping effects obtained are 19 and 12.3, respectively; however, the doping effect of Example 1 is greater than that of Comparative Example 2.
[0101] Table 2 shows that the capacity retention of batteries made from silicon-carbon anode materials prepared in Examples 1-6 and Comparative Examples 1-2 decreased with increasing discharge rate after being cycled 5 times at discharge rates of 0.2C, 0.5C, 1C, 2C, and 4C, respectively. However, the capacity retention of batteries made from silicon-carbon anode materials prepared in Examples 1-6 and Comparative Examples 1-2 remained relatively constant after being cycled at discharge rates of 0.2C, 0.5C, and 1C. This indicates that there is no significant difference in fast-charging performance at low discharge rates.
[0102] The batteries made from the silicon-carbon anode materials prepared in Examples 1-6 and Comparative Examples 1-2 showed significant differences in capacity retention when cycled at 2C and 4C discharge rates. At 4C discharge rate cycling, the capacity retention of the p-doped n-type amorphous silicon-carbon anode materials in Examples 1-6 was 36.7%–45.6%; the capacity retention of the boron-doped silicon-carbon anode material in Comparative Example 2 was 38.2%; and the capacity retention of the undoped silicon-carbon anode material in Comparative Example 1 was 27.4%. This indicates that doping silicon-carbon anode materials can improve their fast-charging performance.
[0103] When batteries made from the silicon-carbon anode materials prepared in Examples 1-6 and Comparative Examples 1-2 are cycled at a 4C discharge rate, the doping effect W and capacity retention are positively correlated. A higher doping effect W corresponds to a higher capacity retention. The doping effect W reflects the improvement in fast-charging performance of the amorphous silicon-carbon anode material after doping modification.
[0104] When cycled at a 4C discharge rate, the battery made of the silicon-carbon anode material prepared in Example 1 retained a capacity of 45.6%, while the battery made of the silicon-carbon anode material prepared in Comparative Example 2 retained a capacity of 38.2%, indicating that under the same doping amount, n-type doping is better than p-type doping.
[0105] 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: A silicon-carbon single particle, wherein the silicon-carbon single particle comprises a carbon matrix and n-type doped amorphous silicon, wherein the carbon matrix comprises a carbon skeleton and channels located inside the carbon skeleton, and the n-type doped amorphous silicon partially fills the channels. The first coating layer is a silicon-carbon layer that coats the surface of the silicon-carbon single particle. The doping effect W of the n-type doped amorphous silicon in the silicon-carbon anode material is greater than or equal to 1 and less than or equal to 10. 4 The doping effect W is determined by the Hall coefficient RH of the silicon-carbon anode material and the Hall coefficient R of intrinsic silicon. HSi Sure.
2. The silicon-carbon anode material according to claim 1, characterized in that, The doping effect is |R HSi / R H | 3. The silicon-carbon anode material according to claim 1, characterized in that, The doping element in the n-type doped amorphous silicon includes at least one of phosphorus, antimony, and arsenic, and the mass percentage of the doping element in the total mass of the silicon-carbon anode material is 0.01% to 8%.
4. The silicon-carbon anode material according to claim 3, characterized in that, The carbon framework includes hard carbon and carbon allotropes, including graphite, amorphous carbon, diamond, C60, carbon nanotubes, graphene, and carbon fibers.
5. The silicon-carbon anode material according to claim 1, characterized in that, The silicon-carbon anode material contains 25% to 75% 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 comprising a carbon skeleton and channels located inside the carbon skeleton, wherein n-type doped amorphous silicon is deposited in the channels to form silicon-carbon single particles; A first carbon source gas is provided to form a first coating layer on the surface of the silicon-carbon single particle. The first coating layer is a silicon-carbon layer that coats the surface of the silicon-carbon single particle. The doping effect W of the n-type doped amorphous silicon in the silicon-carbon anode material is greater than or equal to 1 and less than or equal to 10. 4 The doping effect W is determined by the Hall coefficient R of the silicon-carbon anode material. H Hall coefficient R of intrinsic silicon HSi Sure.
7. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The doping effect is |R HSi / R H | 8. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The method for depositing n-type doped amorphous silicon in the channel includes: simultaneously introducing silicon source gas and doping gas into the deposition chamber, and depositing n-type doped amorphous silicon in the channel by chemical vapor deposition process.
9. 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 of the gaseous compounds of phosphorus, antimony, and arsenic.
10. The method for preparing the silicon-carbon anode material according to claim 9, characterized in that, The volume ratio of the silane gas to the dopant gas is 1:(0.01~0.5); the chemical vapor deposition temperature is 300℃~800℃, and the time is more than 1 hour.
11. The method for preparing the silicon-carbon anode material according to claim 9, 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 volume of the carrier gas is 5% to 90% of the total volume of all the reactant gases introduced.
12. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The method for depositing n-type doped amorphous silicon in the channel includes: introducing a 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.
13. The method for preparing the silicon-carbon anode material according to claim 12, characterized in that, The silicon source gas includes silane gases, and the dopant ions include at least one of phosphorus ions, antimony ions, and arsenic ions.
14. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The method for depositing n-type 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 and P2O5, the liquid-phase source includes AsAl and POCl3, and the gas-phase source includes AsH3 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 400–1100℃ and the diffusion time is 1 s–4 h.
17. The method for preparing silicon-carbon anode material according to claim 8, 12, 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 600℃~1100℃, and the annealing time is 1s~8h.
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 200–700°C.
19. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The particle size of the n-type doped amorphous silicon is 0.1 nm to 4 nm.
20. The method for preparing the silicon-carbon anode material according to claim 6, characterized in that, The silicon-carbon anode material contains 25% to 75% silicon by mass.