CN112952054B - Silicon-based anode material, preparation method thereof, anode and lithium ion battery - Google Patents
Silicon-based anode material, preparation method thereof, anode and lithium ion battery Download PDFInfo
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Abstract
The invention discloses a preparation method of a silicon-based negative electrode material, which comprises the steps of taking silicon oxide as a raw material, carrying out surface modification treatment on the silicon oxide raw material, then combining the silicon oxide subjected to the surface modification treatment with few layers of graphene to prepare a silicon-based capacity unit, and then mixing the silicon-based capacity unit with a carbon-based material to prepare the silicon-based negative electrode material. The invention also discloses a silicon-based negative electrode material of the lithium ion battery prepared by the method, a negative electrode containing the silicon-based negative electrode material and the lithium ion battery. The invention can improve the reversible capacity and coulomb efficiency of the lithium ion battery and reduce the volume expansion.
Description
Technical Field
The invention belongs to the technical field of lithium ion battery anode materials, and particularly relates to a silicon-based anode material, a preparation method thereof, an anode and a lithium ion battery.
Background
With the rapid development of new energy industry, the market demands for lithium ion batteries with high battery energy density are vigorous, and the key to improving the lithium ion battery energy density is to develop lithium ion battery materials with high energy density.
In the aspect of the cathode material, the capacity improvement space of the traditional graphite cathode material is limited, while the silicon oxide has higher theoretical reversible capacity (> 2500 mAh/g) and the volume effect (< 150%) is far less than 300% of silicon, so that the silicon oxide has unique advantages compared with the silicon material. However, the silicon oxide itself has the problems of poor conductivity, large volume expansion, low initial coulombic efficiency and the like, and is difficult to be directly applied to lithium ion batteries.
In order to solve the problems, at present, a gas phase method or a liquid phase method is generally adopted to carry out carbon coating, or nano modification, metal doping and other means are adopted to improve the electrochemical performance of the catalyst, however, the effect is not obvious, the reversible capacity is generally lower than 1500mAh/g, the coulombic efficiency is lower than 75%, the circularity is poor, and the application requirement is still difficult to meet.
Disclosure of Invention
The invention aims to solve the technical problems in the prior art, and provides a silicon-based anode material, a preparation method thereof, an anode and a lithium ion battery, which can improve the reversible capacity and coulombic efficiency of the lithium ion battery and reduce the volume expansion.
According to one aspect of the invention, a preparation method of a silicon-based anode material is provided, and the technical scheme is as follows:
A preparation method of a silicon-based anode material comprises the steps of,
taking silicon oxide as a raw material,
firstly, surface modification treatment is carried out on the silicon oxide raw material,
then combining the surface-modified silicon oxide with few layers of graphene to prepare a silicon-based capacity unit,
and then mixing the silicon-based capacity unit with a carbon-based material to prepare the silicon-based anode material.
Preferably, the method specifically comprises the following steps:
s1, surface modification treatment: taking a silicon oxide raw material, and performing pre-coating treatment on the silicon oxide raw material by using a carbon source A and/or performing ion doping treatment on the silicon oxide raw material by using a doping source to prepare modified silicon oxide;
s2, preparing a capacity unit: dispersing a carbon source B in an organic solvent B, sequentially adding a few-layer graphene and the modified silicon oxide, uniformly mixing to obtain slurry, and performing rotary evaporation or spray drying, calcination, air crushing and sieving treatment on the slurry to obtain a silicon-based capacity unit, wherein the few-layer graphene is used as a carrier, so that the modified silicon oxide is attached to the surface of the few-layer graphene;
s3, compounding carbon-based materials: and mixing the silicon-based capacity unit with a carbon-based material to prepare a silicon-based negative electrode material product.
Preferably, in the step S1, the pre-coating treatment means that a gas phase method and/or a liquid phase method is adopted to deposit a nano carbon layer on the surface of the silicon oxide raw material, the nano carbon layer is a single carbon layer or a composite carbon layer, and the thickness of the nano carbon layer is 5-40 nm.
Preferably, the vapor deposition of the nanocarbon layer comprises the following steps: heating the silicon oxide raw material to a deposition temperature, then introducing a carbon source A1, and keeping the deposition temperature to deposit the carbon source A1 on the surface of the silicon oxide raw material to form a nano carbon layer, thereby obtaining the modified silicon oxide; the carbon source A1 is one or more of methane, acetylene, ethylene, ethane and butane; the deposition temperature of the gas phase method is 700-1050 ℃, and the deposition time of the gas phase method is 0.5-3.0 h.
Preferably, the liquid phase method for depositing the nano carbon layer comprises the following steps: dispersing a carbon source A2 in an organic solvent A1, adding the silicon oxide raw material, uniformly mixing, and then performing rotary evaporation or spray drying and calcination to deposit the carbon source A2 on the surface of the silicon oxide raw material to form a nano carbon layer, thereby obtaining the modified silicon oxide; the carbon source A2 is one or more of petroleum asphalt, coal asphalt, phenolic resin, polyvinyl alcohol, toluene, phenol, citric acid, sucrose and glucose; the organic solvent A1 is one or more of methanol, ethanol, isopropanol and tetrahydrofuran; the calcination temperature of the liquid phase method deposited nano carbon layer is 850-1000 ℃, and the calcination time of the liquid phase method deposited nano carbon layer is 1.0-1.5 h.
Preferably, in the step S1, the ion doping treatment means that a liquid phase method or a solid phase method is adopted to mix a doping source and the silicon oxide raw material, and then the mixture is calcined to form an ion doping layer on the surface of the silicon oxide raw material, so as to realize doping, wherein the doping source is a compound containing any element of boron, magnesium, nitrogen and sulfur; the calcination temperature in the ion doping treatment is 900-1050 ℃, and the calcination time in the ion doping treatment is 2.0-5.0 h.
Preferably, the ion doping by the liquid phase method comprises the following steps: and dissolving and dispersing the doping source in an organic solvent A2, adding the silicon oxide raw material, performing high-speed dispersion, rotary evaporation or spray drying, and calcining to realize doping to obtain the modified silicon oxide.
Preferably, the organic solvent A2 is one or more of absolute ethyl alcohol, isopropanol, methanol and tetrahydrofuran.
Preferably, the ion doping by the solid phase method comprises the following steps: and uniformly mixing the doping source with the silicon oxide raw material, compacting, and calcining to realize doping to obtain the modified silicon oxide.
Preferably, in the step S2, the carbon source B is one or more of petroleum pitch, coal pitch, phenolic resin, polyvinyl alcohol, toluene, phenol, citric acid, sucrose, and glucose; the organic solvent B is one or more of methanol, ethanol, isopropanol, tetrahydrofuran and toluene.
Preferably, in the step S2, the weight ratio of the carbon source B to the organic solvent B is 1 (50 to 200); the weight ratio of the few-layer graphene to the surface-modified silicon oxide to the organic solvent B is as follows: 1 (5-8), 100-200); the calcination temperature is 850-1000 ℃, and the calcination time is 1.0-5.0 h.
Preferably, in the step 2, the calcination is performed under a protective gas atmosphere, wherein the protective gas is helium, nitrogen, argon, or helium, nitrogen, or argon mixed with hydrogen, and the content of the hydrogen is 10-30% of the protective gas.
Preferably, in the step S3, the carbon-based material is one or more of natural graphite, artificial graphite, and mesophase carbon microspheres; the weight ratio of the silicon-based capacity unit to the carbon-based material is (4:96) - (30:70); the mixing is carried out by adopting one or more modes of a V-shaped mixer, a VC mixer and a ball mill, so that the silicon-based capacity units can be uniformly dispersed in the carbon-based materials.
According to another aspect of the invention, a silicon-based anode material of a lithium ion battery is provided, and the technical scheme is as follows:
the silicon-based negative electrode material of the lithium ion battery is prepared by the method.
According to another aspect of the invention, there is provided a lithium ion battery anode, which has the following technical scheme:
a negative electrode for a lithium ion battery comprising a silicon-based negative electrode material as described above.
According to still another aspect of the present invention, there is provided a lithium ion battery, which has the following technical scheme:
a lithium ion battery comprising a negative electrode employing the negative electrode described above.
The preparation method of the silicon-based anode material provided by the invention has the following beneficial effects that the silicon-based anode material, the anode and the lithium ion battery prepared by the preparation method are as follows:
(1) The reversible capacity and charge-discharge efficiency (coulomb efficiency) of the silicon oxide material can be effectively improved, the conductivity of the silicon oxide particles can be improved, and the volume effect (less than 130%) can be reduced by modifying the surface of the silicon oxide raw material, namely pre-depositing a nano carbon layer and/or carrying out ion doping;
(2) The modified silicon oxide is attached to the surface of the few-layer graphene by adopting the few-layer graphene with high specific surface area as a carrier, so that the volume expansion effect of silicon in the circulation process is further relieved, the conductivity is improved, and the use amount of carbon tubes in the lithium ion battery can be greatly reduced.
(3) The compact nano carbon layer formed on the surface of the silicon oxide has a certain binding effect on silicon, and can form a stable passivation layer (namely solid electrolyte interphase, totally called solid electrolyte interface film, SEI film for short) on the surface of the compact nano carbon layer, so that the consumption of electrolyte in the cycle process of the lithium ion battery can be reduced, the pulverization of materials in the cycle process of the battery can be improved, and the cycle performance of the lithium ion battery can be improved.
Drawings
FIG. 1 is a schematic structural diagram of a silicon-based anode material according to an embodiment of the present invention;
FIG. 2 is a graph showing the first charge and discharge of a silica capacity unit according to example 2 of the present invention;
fig. 3 is a graph showing the first charge and discharge of the silicon-based negative electrode material for lithium ion battery in example 3 of the present invention;
FIG. 4 is a transmission electron microscope spectrum of modified silica with boron doped and composite nanocarbon layer in example 4 of the present invention;
FIG. 5 shows the X-ray diffraction patterns of modified silica in examples 1 to 3 of the present invention.
In the figure: modified silica in curve 1-example 2; curve 2-modified silica in example 3; curve 3-modified silica in example 4.
Detailed Description
In order to better understand the technical solution of the present invention, the present invention will be further clearly and completely described in the following with reference to the drawings and specific embodiments of the present invention.
The cathode material of the lithium ion battery aims at solving the problems of poor conductivity, large volume expansion effect, poor cycle performance and the like of the cathode material of the lithium ion battery in the prior art. The invention provides a preparation method of a silicon-based anode material of a lithium ion battery, which comprises the following steps of,
taking silicon oxide as a raw material,
firstly, surface modification treatment is carried out on the silicon oxide raw material,
then combining the surface-modified silicon oxide with few layers of graphene to prepare a silicon-based capacity unit,
and then mixing the silicon-based capacity unit with a carbon-based material to prepare the silicon-based anode material.
Correspondingly, the invention also provides a silicon-based anode material of the lithium ion battery, which is prepared by the method.
Correspondingly, the invention also provides a negative electrode of the lithium ion battery, which adopts the silicon-based negative electrode material.
Correspondingly, the invention also provides a lithium ion battery, which comprises a negative electrode, wherein the negative electrode adopts the negative electrode.
Example 1
The embodiment discloses a preparation method of a silicon-based anode material of a lithium ion battery, which comprises the following steps: taking silicon oxide as a raw material, and carrying out surface modification treatment on the silicon oxide raw material; then combining the surface-modified silicon oxide with few layers of graphene to prepare a silicon-based capacity unit; and then mixing the silicon-based capacity unit with a carbon-based material to prepare a silicon-based negative electrode material product.
The method of the embodiment specifically comprises the following steps:
s1, surface modification treatment: and (3) taking the silicon oxide raw material, and performing pre-coating treatment on the silicon oxide raw material by using a carbon source A and/or performing ion doping treatment on the silicon oxide raw material by using a doping source to obtain the modified silicon oxide.
In this example, it is preferable to use a silica raw material having a particle diameter of 3 to 12. Mu.m. The pre-coating treatment is to deposit a nano carbon layer on the surface of the silicon oxide raw material particles by adopting a gas phase method and/or a liquid phase method, namely: the single carbon layer is formed on the surface of the silicon oxide raw material by adopting a gas phase method or a liquid phase method, or a combination of the gas phase method and the liquid phase method (such as pre-coating by adopting the liquid phase method and then adopting the gas phase method), a combination of the gas phase method and the gas phase method (such as pre-coating by adopting different carbon sources for a plurality of gas phase methods, and particularly suitable for being used when the coating by adopting the gas phase method is not uniform enough), and a combination of the liquid phase method and the liquid phase method (such as pre-coating by adopting different carbon sources for a plurality of liquid phase methods) are adopted to form the composite carbon layer on the surface of the silicon oxide raw material. In this embodiment, the thickness of the nano carbon layer is preferably 5-40 nm, and the carbon layer content is about 0.5-7.0%.
Specifically, the vapor deposition of the nanocarbon layer comprises the following steps: heating the silicon oxide raw material to a deposition temperature, then introducing a carbon source A1, and keeping the deposition temperature to deposit the carbon source A1 on the surface of the silicon oxide raw material to form a compact nano carbon layer, thereby obtaining the modified silicon oxide with the nano carbon layer. Wherein: the carbon source A1 is one or more of methane, acetylene, ethylene, ethane and butane; the deposition temperature of the gas phase method is 700-1050 ℃, and the deposition time of the gas phase method is 0.5-3.0 h.
Specifically, the deposition of the nano carbon layer by a liquid phase method comprises the following steps: dispersing a carbon source A2 in an organic solvent A1, adding a silicon oxide raw material, uniformly mixing, performing rotary evaporation or spray drying, and calcining (namely high-temperature treatment, also called carbonization treatment and heat treatment), so that the carbon source A2 is deposited on the surface of the silicon oxide raw material to form a nano carbon layer, thereby obtaining the modified silicon oxide with the nano carbon layer. Wherein: the carbon source A2 is one or more of petroleum asphalt, coal asphalt, phenolic resin, polyvinyl alcohol, toluene, phenol, citric acid, sucrose and glucose; the organic solvent A1 is one or more of methanol, ethanol, isopropanol and tetrahydrofuran, and the organic solvent A1 is mainly used for dispersing the carbon source A1 and preventing oxidation of silicon oxide; the weight ratio of the carbon source A2 to the organic solvent A1 is 1: (50-500), wherein the total mass of the carbon source A2 and the silicon oxide is 10-30% of the weight of the organic solvent, and the weight ratio of the carbon source A2 to the silicon oxide is preferably 2-8%; the calcination temperature of the liquid phase method deposited nano carbon layer is 850-1000 ℃, and the calcination time of the liquid phase method deposited nano carbon layer is 1.0-1.5 h.
Practice proves that when the nano carbon layer is deposited, the thickness of the nano carbon layer is easier to control by adopting a gas phase method than a liquid phase method, the nano carbon layer deposited by adopting the gas phase method is more uniform and has higher quality, the thickness is required to be thinner, and the thickness of the nano carbon layer deposited by adopting the gas phase method can be more preferably 5-30 nm.
In this embodiment, the ion doping means that a liquid phase method or a solid phase method is adopted to mix a doping source and a silicon oxide raw material to obtain a mixture, and then the mixture is calcined to form an ion doping layer on the surface of the silicon oxide raw material by the doping source, thereby realizing doping. Wherein: the doping source adopts a compound containing any element of boron, magnesium, nitrogen and sulfur, such as sodium borate, magnesium oxide and the like, so as to dope boron, magnesium, nitrogen and sulfur plasma; the calcination temperature in the ion doping treatment is 900-1050 ℃, and the calcination time in the ion doping treatment is 2.0-5.0 h.
In the present embodiment, the ion doping amount of the silicon oxide is preferably
The doping amount is small, so long as the doping ions can be uniformly dispersed to reach the required doping amount, the doping source dosage is not further limited, and the doping source dosage can be selected according to factors such as doping efficiency and the like.
Specifically, the ion doping by the liquid phase method comprises the following steps: and dissolving and dispersing the doping source in an organic solvent A2, adding a silicon oxide raw material, performing high-speed dispersion, rotary evaporation or spray drying, and calcining (900-1050 ℃) to realize doping, so as to obtain the modified silicon oxide with the ion doped layer on the surface. Wherein the organic solvent A2 is one or more of absolute ethyl alcohol, isopropanol, methanol and tetrahydrofuran, and the organic solvent B is mainly used for dissolving and dispersing doping sources.
Specifically, the ion doping by the solid phase method comprises the following steps: mixing the doping source and the silicon oxide raw material uniformly, compacting, and calcining (900-1050 ℃) to realize doping, so as to obtain the modified silicon oxide with the ion doped layer on the surface.
S2, preparing a capacity unit: dispersing a carbon source B in an organic solvent B, sequentially adding a few layers of graphene and the modified silicon oxide, uniformly mixing to obtain slurry, and performing rotary evaporation or spray drying, calcination, low-pressure crushing and sieving treatment on the slurry to obtain an undersize product which is collectively called a silicon-based capacity unit, namely a capacity unit for short. Through testing, the capacity of the silicon-based capacity unit prepared by the method of the embodiment is 1000-1600 mAh/g.
The carbon source B is one or more of petroleum asphalt, coal asphalt, phenolic resin, polyvinyl alcohol, toluene, phenol, citric acid, sucrose and glucose, and is decomposed and carbon is deposited on the surface of the silicon oxide during calcination (high-temperature carbonization) so as to improve the conductivity of the silicon oxide particles, and the modified silicon oxide is attached to the surface of the few-layer graphene; the organic solvent B adopts one or more of alcohols (such as absolute ethyl alcohol and methanol), tetrahydrofuran and toluene, and is used for dispersing the carbon source B and protecting the silicon oxide from being oxidized; the weight ratio of the carbon source B to the organic solvent B is 1: 50-200 parts; the weight ratio of the few-layer graphene to the surface-modified silicon oxide to the organic solvent B is as follows: 1:5-8:100-200; the calcination temperature is 850-1000 ℃, and the calcination time is 1.0-5.0 h; the air crushing is carried out under a low pressure condition, and the low pressure in the embodiment is preferably 0.005-0.1 MPa; the sieving treatment is preferably a sieving treatment with a 100-300 mesh sieve to obtain a sieve bottom.
In this embodiment, the calcination process in the preparation of the capacity unit is preferably performed under a protective gas atmosphere. The shielding gas can be helium, nitrogen or argon, or helium mixed with hydrogen or nitrogen or argon, and the content of the hydrogen is 10-30% of the total amount of the shielding gas.
S3, compounding carbon-based materials: and mixing the silicon-based capacity unit and the carbon-based material to prepare a silicon-based anode material product, wherein the structure of the silicon-based anode material product is shown in figure 1 (SO/C represents silicon oxide carbon coating, graphene represents Graphene sheets, and Graphite represents Graphite).
Wherein, the mixing treatment refers to uniformly mixing by adopting one or more modes of a V-shaped mixer (also called as a V-shaped mixer, namely a high-efficiency asymmetric mixer), a VC mixer (also called as a VC high-efficiency mixer) and a ball mill. The mixing time is preferably 3 to 5 hours.
In this embodiment, the carbon-based material is one or more of natural graphite, artificial graphite, and mesocarbon microbeads (i.e., MCMB, all called Mesocarbon Microbeads); the weight ratio of the silicon-based capacity unit to the carbon-based material is preferably (4:96) - (30:70), for example, 8:92, 4:96, 20:80, etc.
Through testing, the silicon-based anode material prepared by the method of the embodiment has the capacity of 400-600 mAh/g and the coulomb efficiency of 85-92%, has excellent electrochemical performance, and can be used for preparing the anode of a lithium ion battery and the lithium ion battery.
The embodiment also discloses a silicon-based anode material of the lithium ion battery, which is prepared by adopting the method. Before modification, the first coulomb efficiency of the silicon oxide is lower than 70%, after modification, the first coulomb efficiency of the silicon oxide can be higher than 76%, the few-layer graphene has a high conductivity and lamellar structure, the electron transmission of the modified material in the battery cycle process can be realized, and the lamellar structure can buffer volume expansion, so that the efficiency, multiplying power and cycle performance of the lithium ion battery can be improved.
The embodiment also discloses a negative electrode of the lithium ion battery, which comprises the silicon-based negative electrode material prepared by the method.
The embodiment also discloses a lithium ion battery, which comprises a negative electrode, wherein the negative electrode adopts the negative electrode.
The preparation method of the silicon-based anode material of the lithium ion battery, which is disclosed by the embodiment, has the following beneficial effects that the prepared silicon-based anode material, anode and lithium ion battery are as follows:
(1) The reversible capacity and charge-discharge efficiency (namely coulomb efficiency) of the silicon oxide material can be effectively improved, the conductivity of the silicon oxide particles can be improved, and the volume effect (less than 130%) can be reduced by modifying the surface of the silicon oxide raw material, namely pre-depositing a nano carbon layer and/or carrying out ion doping;
(2) The modified silicon oxide is attached to the surface of the few-layer graphene by adopting the few-layer graphene with high specific surface area as a carrier, so that the volume expansion effect of silicon in the circulation process is further relieved, the conductivity is improved, and the use amount of carbon tubes in the lithium ion battery can be greatly reduced.
(3) The compact nano carbon layer formed on the surface of the silicon oxide has a certain binding effect on silicon, and can form a stable SEI film on the surface of the compact nano carbon layer, so that the consumption of electrolyte in the cycle process of the lithium ion battery can be reduced, the pulverization of materials in the cycle process of the battery can be improved, and the cycle performance of the lithium ion battery can be improved.
Example 2
The embodiment discloses a preparation method of a silicon-based negative electrode material of a lithium ion battery, which comprises the steps of firstly adopting a gas phase method, taking acetylene as a gas carbon source (namely a carbon source A1), carrying out modification treatment on the surface of silicon oxide to form a compact nano carbon layer on the surface of the silicon oxide, then preparing a silicon-based capacity unit by using the modified silicon oxide, and further preparing the silicon-based negative electrode material.
The preparation method of the embodiment comprises the following specific steps:
(1) Taking 5kg of a silicon oxide raw material, putting the silicon oxide raw material into a CVD (chemical vapor deposition) device, heating to 950 ℃, and preserving heat, wherein the heating rate is preferably 5 ℃/min, and the preserving heat time is preferably 15min. And then introducing acetylene and argon into the CVD equipment to decompose the acetylene at 950 ℃ under the argon condition and deposit the acetylene on the surface of the silicon oxide to form a nano carbon layer (single carbon layer), wherein the flow rate of the acetylene is 1.0L/min, the flow rate of the argon is 3L/min, and the deposition time is preferably 45min. After the deposition is completed, the materials (mainly modified silicon oxide) in the CVD equipment are cooled to room temperature along with a furnace under the protection of argon atmosphere, and the modified silicon oxide with a single nano carbon layer is obtained. During cooling, the argon flow is preferably 2L/min.
In this embodiment, in order to ensure uniformity of the nano carbon layer deposited on the surface of the silicon oxide, the CVD apparatus used should have a circulation stirring structure, and the stirring effect of the circulation stirring structure is utilized to ensure complete decomposition of acetylene and sufficient contact with the silicon oxide particles, thereby improving uniformity of the nano carbon layer on the surface of the silicon oxide. The stirring structure was rotated at 3r/pm and the space for deposition (i.e., furnace chamber) in the CDV apparatus should have a graphite lining. The purity of the gas (acetylene, argon) should be greater than 99.99%.
(2) Firstly, petroleum pitch (i.e. carbon source B) is added to isopropanol (i.e. organic solvent B), the weight ratio of petroleum pitch to isopropanol being 1:60, and then shearing and dispersing for 2.0h at high speed to uniformly disperse the petroleum asphalt in the isopropanol, wherein the petroleum asphalt can be subjected to ball milling and air crushing treatment to ensure that the particle size distribution of the petroleum asphalt is more uniform, and the preferred particle size of the petroleum asphalt is 5-7 mu m. Then adding few layers of graphene, continuing to disperse for 1.0h, adding the modified silicon oxide, and dispersing at high speed for 3.0h to obtain slurry, wherein the weight ratio of the added few layers of graphene to the surface modified silicon oxide to the isopropanol is 1:6:60. And then, spray drying the slurry, and carbonizing (namely calcining) the slurry in a carbonization furnace for 2.0h under the condition of argon atmosphere and 950 ℃. And finally, carrying out air crushing on the calcined product under the condition of 0.1MPa, and then sieving the crushed product by a 300-mesh sieve to obtain a silicon oxide capacity unit (namely a silicon-based capacity unit). As shown in fig. 2, the first charge-discharge curve of the silicon oxide capacity unit of this embodiment (the test process is that the charge-discharge test is performed in the voltage range of 0-1.5V, the discharge step is that 0.1C is discharged to 0.1V, then 0.09C, 0.08C, … … C and 0.01C are discharged to 0.005V, and then 0.1C is charged to 1.5V, which is not described herein in detail), and curve a and curve B in fig. 2 are charge curves. As can be seen from FIG. 2, the reversible capacity can reach more than 1550mAh/g, and the battery efficiency can reach 75.8% through test, compared with the capacity of less than 1000mAh/g before the silicon oxide is not modified and the efficiency of less than 70%, the reversible capacity and the efficiency of the battery can be obviously improved after the silicon oxide is modified by adopting the method of the embodiment.
(3) Adding the silicon oxide capacity unit and artificial graphite (namely carbon-based material) into a V-shaped mixer according to the weight ratio of 85:15, and mechanically mixing for 5.0h to obtain the silicon-based anode material. Through detection, the capacity of the silicon-based anode material is 550mAh/g, the first charge-discharge efficiency is more than 85%, and the silicon-based anode material has excellent electrochemical performance.
The embodiment also discloses a silicon-based anode material of the lithium ion battery, which is prepared by adopting the method.
The embodiment also discloses a negative electrode of the lithium ion battery, which comprises the silicon-based negative electrode material prepared by the method.
The embodiment also discloses a lithium ion battery, which comprises a negative electrode, wherein the negative electrode adopts the negative electrode.
Example 3
The embodiment discloses a preparation method of a silicon-based anode material of a lithium ion battery, which comprises the steps of firstly adopting a gas phase method, respectively taking acetylene and methane as gas carbon sources (namely a carbon source A1), carrying out modification treatment on the surface of silicon oxide twice to form a compact composite nano carbon layer on the surface of the silicon oxide, and then preparing a silicon-based capacity unit and further preparing the silicon-based anode material by using the modified silicon oxide.
The specific steps of the method of the embodiment are as follows:
(1) Taking 3kg of silica material with the particle size of 5-7 mu m, putting the silica material into cone-type CVD equipment, setting the heating rate to be 10 ℃/min, introducing argon, heating the silica particles to 950 ℃ under the argon atmosphere, and preserving the temperature for 15min, wherein the argon flow is 3L/min. And then introducing an acetylene and argon mixed gas, wherein the flow rate of acetylene is 2.0L/min, the flow rate of argon is 4L/min, so that acetylene is decomposed at 950 ℃ and under the argon condition and deposited on the surface of silicon oxide to form a nano carbon layer, and after depositing for 25min, stopping introducing acetylene. And then continuously heating the silicon oxide particles with the nano carbon layer to 1000 ℃ under the argon atmosphere, and then introducing methane and argon mixed gas, wherein the flow rate of the methane is 10.0L/min, and the flow rate of the argon is 5L/min, so that the methane continuously deposits the nano carbon layer on the surface of the silicon oxide particles with the nano carbon layer to form a composite nano carbon layer, and the deposition time is 25min. After the deposition is completed, the materials (mainly modified silicon oxide) in the CVD equipment are cooled to room temperature along with a furnace under the protection of argon atmosphere, and the modified silicon oxide with the composite nano carbon layer is obtained. In the cooling process, the argon flow is preferably 5L/min, and the heat in the furnace chamber can be taken away as soon as possible by the larger gas (argon) flow, so that the cooling speed is increased, and the phenomenon that the electrochemical performance of the material is influenced due to excessive disproportionation of silicon oxide particles caused by overlong material in a high-temperature environment is avoided.
Considering uniformity of carbon layer deposition on the surface of the silicon oxide particles, content of metal impurities and the like, electrochemical performance of the whole lithium ion battery can be directly influenced. Therefore, in this embodiment, the CVD apparatus used should have a circulation stirring structure capable of stirring, and the rotation speed of the stirring structure is preferably 4r/pm, so as to improve the uniformity of the nano-carbon layer deposited on the surface of the silicon oxide; the furnace chamber of the CVD equipment is provided with a silicon nitride lining so as to avoid metal pollution, reduce the self-discharge phenomenon of the lithium ion battery manufactured later in the circulation process and improve the circulation performance of the lithium ion battery.
(2) The asphalt (namely, the carbon source B, coal asphalt, petroleum asphalt or other types of asphalt) is subjected to air-break treatment and then added into tetrahydrofuran (namely, the organic solvent C), wherein the weight ratio of the asphalt to the tetrahydrofuran is preferably 1:150. and then dispersing for 1.0h at high speed to dissolve and uniformly disperse the coal pitch in the tetrahydrofuran. Then adding few layers of graphene, continuing to disperse for 1.5 hours, adding the modified silicon oxide with the composite nano carbon layer, and dispersing at a high speed for 1.0 hour to obtain slurry, wherein the weight ratio of the added few layers of graphene, the modified silicon oxide and the tetrahydrofuran is preferably 1:5: 150. and then, carrying out rotary evaporation treatment on the slurry, and then putting the slurry into a carbonization furnace to carbonize for 2.0h under the condition of argon atmosphere and 900 ℃ to obtain a carbonized product. And finally, carrying out air crushing treatment on the carbonized product under the condition of 0.07MPa, and then sieving the carbonized product by a 300-mesh sieve to obtain the silicon oxide capacity unit.
(3) The silicon oxide capacity unit is subjected to demagnetization, and in the embodiment, the demagnetization machine is adopted to perform demagnetization twice so as to remove metal impurities and prevent the lithium ion battery prepared by the silicon oxide capacity unit from micro short circuit. And adding the demagnetized silicon oxide capacity unit and the artificial graphite 830B (namely carbon-based material) into a VC mixer according to the weight ratio of 87:13, and uniformly mixing to obtain a silicon-based negative electrode material product.
In order to avoid the damage of the carbon layer structure on the particle surface of the silicon oxide capacity unit during high-speed stirring and mixing of the VC mixer and to prevent the high temperature generated by the high-speed stirring from affecting the structure of the silicon oxide capacity unit, in this embodiment, the mixing is preferably performed under the conditions of low-speed stirring and argon atmosphere protection, and the mixing time is preferably 3.0h. As shown in fig. 3, the first charge-discharge curve of the silicon-based anode material prepared in this example (the test process is that the charge-discharge test is performed in the voltage range of 0-1.5V, the discharge step is that 0.1C is discharged to 0.1V, 0.09C, 0.08C, … … C and 0.01C are discharged to 0.001V, and then 0.1C is charged to 1.5V), and curve a is the charge curve and curve b is the discharge curve in fig. 3. As can be seen from FIG. 3, the capacity is more than 550mAh/g, the first charge and discharge efficiency is more than 86% through test, and the electrochemical performance is excellent.
The embodiment also discloses a silicon-based anode material of the lithium ion battery, which is prepared by adopting the method.
The embodiment also discloses a negative electrode of the lithium ion battery, which comprises the silicon-based negative electrode material prepared by the method.
The embodiment also discloses a lithium ion battery, which comprises a negative electrode, wherein the negative electrode adopts the negative electrode.
Example 4
The embodiment discloses a preparation method of a silicon-based anode material of a lithium ion battery, which comprises the steps of carrying out modification treatment on the surface of silicon oxide, wherein the preparation method comprises the steps of firstly adopting sodium borate as a doping source to carry out liquid-phase ion doping to form a doping layer, adopting petroleum asphalt as a carbon source (namely a carbon source A2) to carry out liquid-phase deposition to form a single nano carbon layer, and adopting acetylene as a gas carbon source (namely a carbon source A1) to carry out vapor-phase deposition to form a composite nano carbon layer; and preparing a silicon-based capacity unit and further preparing a silicon-based anode material by using the modified silicon oxide.
The specific steps of the method of the embodiment are as follows:
(1) Sodium borate is mixed according to the doping proportion
Dissolving 1.7g sodium borate in absolute ethanol, adding into 15kg absolute ethanol, ball milling, and air pulverizing to obtain powder with particle diameter of 5 75g of petroleum asphalt with the diameter of 7 mu m is dispersed at a high speed to form a suspension, wherein the dispersion speed is 8000-20000rpm, and the dispersion time is 2.0h. In this embodiment, in order to avoid the generation of high temperature during the high-speed dispersion, intermittent dispersion is preferably employed. After the completion of the dispersion, 1.5kg of silica was added thereto, and the mixture was mechanically stirred and mixed for 3.0 hours to obtain a slurry. And (3) carrying out rotary evaporation treatment on the slurry, and carbonizing at 950 ℃ for 3.0h to obtain a carbonized product. The carbonized product is crushed under low pressure (such as 0.07 MPa) and sieved by a 300-mesh sieve to obtain boron doped silicon oxide (i.e. modified silicon oxide). In the process of doping boron, part of carbon (from petroleum asphalt) is deposited on the surface of silicon oxide in a liquid phase deposition mode, but the carbon content is only about 2.0 percent.
In this example, in order to compensate for the lack of uniformity of the carbon deposited in the liquid phase, 1.0kg of the modified silica was placed in a conical CVD apparatus, heated to 950 ℃ at a heating rate of 5 ℃/min under an argon protection atmosphere, and then mixed gas of acetylene and argon was introduced, wherein the flow rate of acetylene was 1.0L/min and the flow rate of argon was 3L/min, so that the acetylene was decomposed at 950 ℃ and under the argon condition and deposited on the silica surface for 30min, thereby forming a composite nano carbon layer, and a modified silica having boron doped and composite nano carbon layer was obtained, the morphology of which is shown in fig. 4, and the X-ray diffraction pattern of which is shown in fig. 5. As can be seen from fig. 4, the nano carbon film coated on the surface of the silicon oxide is uniformly distributed and has a graphene-like structure, and the structure can improve the conductivity of the material, thereby improving the reversible capacity and coulomb efficiency of the material. As can be seen from curves 1-3 in FIG. 5, the silicon oxide is obviously crystallized after being modified by high-temperature treatment, and the crystallization shows that the relative content of nano silicon crystals in the silicon oxide is increased, and the silicon has higher capacity and coulombic efficiency compared with the silicon oxide, so that the increase of the silicon content can be beneficial to improving the reversible capacity and coulombic efficiency of the modified silicon oxide material.
In this embodiment, the CVD apparatus used should have a circulation stirring structure with a rotation speed of 3rpm, and a ceramic liner such as alumina is used for the inner wall of the furnace chamber of the CVD apparatus.
(2) Preparation of silica capacity units: adding ball-milled petroleum asphalt (namely a carbon source B) into absolute ethyl alcohol (namely an organic solvent B), wherein the weight ratio of the petroleum asphalt to the absolute ethyl alcohol is 1:180, and then shearing and dispersing for 1.0h at a high speed to uniformly disperse the petroleum asphalt in the absolute ethyl alcohol. Then adding few layers of graphene, continuing to disperse for 1.0h, adding the modified silicon oxide with the boron doped and composite nano carbon layer, and continuing to disperse at high speed for 1.0h to obtain slurry, wherein the weight ratio of the added few layers of graphene to the modified silicon oxide to the absolute ethyl alcohol is 1:7: 180. and then, carrying out rotary evaporation treatment on the slurry, and then putting the slurry into a carbonization furnace, and carbonizing for 3.0h under the condition of argon atmosphere and 850 ℃ to obtain a carbonized product. And finally, carrying out air crushing treatment on the carbonized product under the condition of 0.05MPa, and then sieving the carbonized product by a 300-mesh sieve to obtain the silicon oxide capacity unit.
(3) Firstly, demagnetizing the silicon oxide capacity unit and sieving the silicon oxide capacity unit with a 300-mesh screen twice. And then adding the treated silicon oxide capacity unit and artificial graphite (preferably artificial graphite S360 series graphite produced by Bei Terui company) into a V-type mixer according to a weight ratio of 96:4, and uniformly mixing for 5.0h to obtain the silicon-based anode material. Through detection, the capacity of the silicon-based anode material of the embodiment is larger than 420mAh/g, and the first charge-discharge efficiency is larger than 92%.
The embodiment also discloses a silicon-based anode material of the lithium ion battery, which is prepared by adopting the method.
The embodiment also discloses a negative electrode of the lithium ion battery, which comprises the silicon-based negative electrode material prepared by the method.
The embodiment also discloses a lithium ion battery, which comprises a negative electrode, wherein the negative electrode adopts the negative electrode.
Example 5
The embodiment discloses a preparation method of a silicon-based anode material of a lithium ion battery, which comprises the steps of carrying out modification treatment on the surface of silicon oxide, wherein the modification treatment comprises the steps of firstly adopting a solid phase method to carry out ion doping to form a doped layer, and then adopting a vapor phase method to deposit a nano carbon layer to form modified silicon oxide with the doped layer and the nano carbon layer; and preparing a silicon-based capacity unit and further preparing a silicon-based anode material by using the modified silicon oxide.
The specific steps of the method of the embodiment are as follows:
(1) To be doped with
Adding boric acid and silicon oxide into a V-shaped mixer, mixing for 5.0h, compacting under the action of 500kg pressure to form a block, forming a round block, then placing into a high-temperature furnace, and calcining for 3.0h under the inert gas atmosphere and 960 ℃ to realize boron doping, thereby obtaining a doped product (namely modified silicon oxide). And then carrying out gas crushing, 300-mesh sieving and other treatments on the doped product, so that the granularity of the doped product meets the use requirement. In this example, the particle size D50 of the doped product was 3 μm and was normally distributed.
(2) 500g of the doped modified silica described above was placed in a CVD rotary furnace and heated to 1000 ℃ under a shield gas split. Then, under the condition of 1000 ℃, methane, argon and carbon dioxide are introduced, wherein the flow rate of the methane is 500sccm, the flow rate of the argon is 500sccm, the flow rate of the carbon dioxide is 100sccm, and the methane and the carbon dioxide (namely the carbon source A1) are deposited on the surface of the modified silicon oxide after doping treatment for 30-50min to form a nano carbon layer, so that the modified silicon oxide with a doped layer and a single nano carbon layer is obtained.
In this embodiment, the rotation speed of the chamber of the CVD rotary furnace is 2rpm, and the chamber is made of a quartz tube.
(3) And (3) dissolving citric acid (namely a carbon source B) in absolute ethyl alcohol (namely an organic solvent B), wherein the weight ratio of the citric acid to the absolute ethyl alcohol is 1:200, and dispersing at a high speed for 1.0h to uniformly disperse the citric acid in the absolute ethyl alcohol. Then adding few layers of graphene, continuing to disperse for 0.5h, adding the modified silicon oxide with the doped layer and the single nano carbon layer, and continuing to disperse at high speed for 1.0h to obtain slurry, wherein the weight ratio of the added few layers of graphene, the modified silicon oxide and the absolute ethyl alcohol is 1:6: 200. and then, carrying out rotary evaporation treatment on the slurry, putting the slurry into a carbonization furnace, carbonizing for 2.0h under the condition of reducing atmosphere and 650 ℃ to obtain carbonized products, and carrying out low-pressure (such as 0.05 MPa) air crushing and 325-mesh sieving treatment on the carbonized products to obtain the silicon oxide capacity units.
(4) Adding the silicon oxide capacity unit and artificial graphite (such as artificial graphite imported from Japan) into a VC mixer at a weight ratio of 86:14, and mixing for 1.0h to obtain silicon-based negative electrode material. The capacity of the silicon-based anode material of the embodiment is 510mAh/g.
The embodiment also discloses a silicon-based anode material of the lithium ion battery, which is prepared by adopting the method.
The embodiment also discloses a negative electrode of the lithium ion battery, which comprises the silicon-based negative electrode material prepared by the method.
The embodiment also discloses a lithium ion battery, which comprises a negative electrode, wherein the negative electrode adopts the negative electrode.
Example 6
The embodiment discloses a preparation method of a silicon-based anode material of a lithium ion battery, which comprises the steps of carrying out modification treatment on the surface of silicon oxide, wherein the modification treatment comprises the steps of firstly carrying out ion doping by adopting a liquid phase method to form a doped layer, and then depositing a nano carbon layer by adopting a vapor phase method to form modified silicon oxide with the doped layer and the nano carbon layer; and preparing a silicon-based capacity unit and further preparing a silicon-based anode material by using the modified silicon oxide.
The specific steps of the method of the embodiment are as follows:
(1) Adding 0.3g of citric acid and 50g of boric acid into 10kg of absolute ethyl alcohol, dispersing and dissolving at high speed for 1.0h, adding 1.0kg of silica particles, and continuing dispersing at high speed for 1.0h to obtain slurry. In this example, it is preferable to use silica having a particle size D50 of 4. Mu.m. Then, spraying the slurry to obtain a precursor, placing the precursor into a carbonization furnace, and calcining (carbonizing) the precursor for 2.0h under the condition of 960 ℃ under the protection of a reducing atmosphere to obtain a carbonized product. The carbonized product is crushed under low pressure (such as 0.07 MPa) and sieved (such as 300 meshes) to obtain the boron doped modified silicon oxide. The boron doping amount in this embodiment was detected as 
(2) 600g of the boron doped modified silicon oxide is placed in a CVD rotary furnace, heated to 950 ℃, then mixed gas of acetylene and argon is introduced, and the temperature is kept for 35min, so that acetylene is deposited on the surface of the boron doped modified silicon oxide to form a nano carbon layer, and the modified silicon oxide with a doped layer and a nano carbon layer is obtained.
In this embodiment, in the mixture of acetylene and argon, the flow ratio of acetylene to argon is 1:5, and when the flow of acetylene is 0.5L/min, the flow of argon is 2.5L/min. After deposition is complete, the CVD rotary furnace is cooled to room temperature under an inert (e.g., argon) atmosphere. The CVD rotary furnace adopts a quartz cavity body so as to avoid metal impurity pollution to the maximum extent.
(3) Adding ball-milled and air-crushed asphalt (such as petroleum asphalt) into isopropanol, wherein the weight ratio of the asphalt to the isopropanol is 1:100, dispersing for 1.0h under the condition of 15000rpm by using a high-speed dispersing machine, and sequentially adding few layers of graphene and the modified silicon oxide, wherein the weight ratio of the few layers of graphene, the modified silicon oxide and the isopropanol is 1:7: 100, and then dispersing for 1.0h to obtain slurry. Then, the slurry is subjected to rotary evaporation treatment, and then is put into a carbonization furnace, and is subjected to heat treatment for 2.0h under the condition of argon atmosphere and 930 ℃, and then is subjected to low-pressure (such as 0.08 Mpa) air crushing treatment and twice screening by a 325-mesh screen, so that the silicon oxide capacity unit is obtained.
(4) Adding the silicon oxide capacity unit and graphite into a conical circulation mixer according to the weight ratio of 8:92, and mixing for 5.0h under the protection of inert (such as argon) atmosphere to obtain the silicon-based anode material. Through detection, the estimated first charge-discharge reversible capacity of the anode material is more than 450mAh/g, the efficiency is more than 90%, and the anode material has excellent electrochemical performance.
The embodiment also discloses a silicon-based anode material of the lithium ion battery, which is prepared by adopting the method.
The embodiment also discloses a negative electrode of the lithium ion battery, which comprises the silicon-based negative electrode material prepared by the method.
The embodiment also discloses a lithium ion battery, which comprises a negative electrode, wherein the negative electrode adopts the negative electrode.
Example 7
The embodiment discloses a preparation method of a silicon-based anode material of a lithium ion battery, which comprises the steps of carrying out modification treatment on the surface of silicon oxide, wherein the modification treatment comprises the steps of firstly adopting a solid phase method to carry out ion doping to form a doped layer, and then adopting a gas phase method to carry out deposition of a nano carbon layer twice to form modified silicon oxide with the doped layer and a composite nano carbon layer; and preparing a silicon-based capacity unit and further preparing a silicon-based anode material by using the modified silicon oxide.
The specific steps of the method of the embodiment are as follows:
(1) The magnesium oxide (i.e. doping source) is mixed according to the doping proportion
The amount of (2) and silica were added to a V-blender and mixed for 3.0h. And then placed in a cylindrical mold, and the mixture is compacted into a cylindrical shape under a pressure of one ton (i.e., 1000 kg). Then, the cylindrical mixture is put into a condition that the temperature is higher than 950 ℃ to be calcined for 3.0h, so as to realize magnesium doping, and the magnesium doped modified silicon oxide is obtained. The modified silicon oxide is crushed (such as 0.06 MPa) under low pressure and is sieved (such as 300 meshes) for standby.
(2) 500g of the magnesium-doped modified silicon oxide is placed in a furnace chamber of a CVD device, heated to 800 ℃, and then introduced with ethylene (namely a carbon source A1) and nitrogen, wherein the flow of the ethylene is 500sccm, and the flow of the nitrogen is 500sccm, so that the ethylene is deposited on the surface of the silicon oxide in a nitrogen atmosphere at 800 ℃ to form a nano carbon layer, and the modified silicon oxide with the magnesium-doped and single nano carbon layer is obtained. In this embodiment, the deposition time using ethylene as the carbon source is preferably 50 minutes. And then continuously heating the modified silicon oxide with the magnesium doped and single nano carbon layer to 980 ℃, and then introducing methane, argon and carbon dioxide, wherein the flow rate of the methane is 600sccm, the flow rate of the argon is 1000sccm, and the flow rate of the carbon dioxide is 300sccm. And then continuously heating to 1000 ℃, and keeping for 30min, so that a nano carbon layer is deposited on the surface of the modified silicon oxide again, and the modified silicon oxide with a magnesium doped layer and a composite nano carbon layer is obtained. After the deposition is completed, the modified silicon oxide is cooled to room temperature along with a furnace under the argon atmosphere, and the argon flow in the cooling process is 1000sccm.
In this example, the heating rate of the modified silica was 5℃per minute. During the carbon deposition in step (2), the rotation speed of the furnace chamber of the CVD apparatus is 3rpm, and the furnace chamber preferably employs a quartz or ceramic chamber to prevent contamination by metal impurities.
(3) Adding the crushed petroleum asphalt 280 (namely a carbon source B) into isopropanol (namely an organic solvent B), wherein the weight ratio of the petroleum asphalt 280 to the isopropanol is 1:120, shearing and dispersing for 1.0h at high speed, adding few layers of graphene, and continuing to disperse for 0.5h at high speed; and adding the modified silicon oxide with the magnesium doped layer and the composite nano carbon layer, wherein the weight ratio of the few layers of graphene to the modified silicon oxide to the isopropanol is 1:7:120, and continuing to disperse at a high speed for 2.0h to obtain the slurry. Then, the slurry is spray dried, and then is put into a carbonization furnace to be carbonized for 1.5 hours under the condition of argon atmosphere and 950 ℃, and then is crushed by low pressure (such as 0.08 Mpa) and sieved (such as 300 meshes) to obtain the silicon oxide capacity unit.
(4) Adding the silicon oxide capacity unit and graphite capacity into a VC mixer according to the weight ratio of 4:96-20:80, and mixing for 1.0-5.0 h to obtain the silicon-based anode material. Through detection, the capacity of the silicon-based anode material of the embodiment is 400-600 mAh/g, and the silicon-based anode material has excellent electrochemical performance.
The embodiment also discloses a silicon-based anode material of the lithium ion battery, which is prepared by adopting the method.
The embodiment also discloses a negative electrode of the lithium ion battery, which comprises the silicon-based negative electrode material prepared by the method.
The embodiment also discloses a lithium ion battery, which comprises a negative electrode, wherein the negative electrode adopts the negative electrode.
It is to be understood that the foregoing description is only of the preferred embodiments of the invention, however, the invention is not limited thereto. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the invention, and are also considered to be within the scope of the invention.
Claims (14)
1. A preparation method of a silicon-based anode material comprises the steps of,
taking silicon oxide as a raw material,
firstly, surface modification treatment is carried out on the silicon oxide raw material,
then combining the surface-modified silicon oxide with few layers of graphene to prepare a silicon-based capacity unit,
then mixing the silicon-based capacity unit with a carbon-based material to prepare a silicon-based anode material;
the method specifically comprises the following steps:
s1, surface modification treatment: taking a silicon oxide raw material, and performing pre-coating treatment on the silicon oxide raw material by using a carbon source A and/or performing ion doping treatment on the silicon oxide raw material by using a doping source to prepare modified silicon oxide;
S2, preparing a capacity unit: dispersing a carbon source B in an organic solvent B, sequentially adding few layers of graphene and the modified silicon oxide, uniformly mixing to obtain slurry, performing rotary evaporation or spray drying, calcining, air crushing and sieving treatment on the slurry to obtain a silicon-based capacity unit,
wherein the weight ratio of the carbon source B to the organic solvent B is 1 (50-200), the weight ratio of the few-layer graphene, the surface-modified silicon oxide and the organic solvent B is as follows: (5-8) (100-200), wherein the calcining temperature is 850-1000 ℃, the calcining time is 3.0-5.0 h, the few-layer graphene is used as a carrier, the modified silicon oxide is attached to the surface of the few-layer graphene, the air crushing is carried out under the low pressure condition of 0.005-0.1 MPa, a 100-300 mesh screen is adopted for sieving treatment, and the capacity of a silicon-based capacity unit is 1000-1600 mAh/g;
s3, compounding carbon-based materials: and mixing the silicon-based capacity units with the carbon-based material to enable the silicon-based capacity units to be uniformly dispersed in the carbon-based material so as to prepare a silicon-based negative electrode material product.
2. The method for producing a silicon-based anode material according to claim 1, wherein, in the step S1,
The pre-coating treatment is to deposit a nano carbon layer on the surface of the silicon oxide raw material by adopting a gas phase method and/or a liquid phase method,
the nano carbon layer is a single carbon layer or a composite carbon layer, and the thickness of the nano carbon layer is 5-40nm.
3. The method for preparing a silicon-based anode material according to claim 2, wherein the vapor deposition of the nano carbon layer comprises the steps of: heating the silicon oxide raw material to a deposition temperature, introducing a carbon source A1, and maintaining the deposition temperature to deposit a nano carbon layer on the surface of the silicon oxide raw material to obtain the modified silicon oxide;
the carbon source A1 is one or more of methane, acetylene, ethylene, ethane and butane;
the deposition temperature of the gas phase method is 700-1050 ℃, and the deposition time of the gas phase method is 0.5-3.0h.
4. The method for preparing a silicon-based anode material according to claim 2, wherein the liquid phase deposition of the nano carbon layer comprises the steps of: dispersing a carbon source A2 in an organic solvent A1, adding the silicon oxide raw material, uniformly mixing, performing rotary evaporation or spray drying, calcining, and depositing a nano carbon layer on the surface of the silicon oxide raw material to obtain the modified silicon oxide;
The carbon source A2 is one or more of petroleum asphalt, coal asphalt, phenolic resin, polyvinyl alcohol, toluene, phenol, citric acid, sucrose and glucose;
the organic solvent A1 is one or more of methanol, ethanol, isopropanol and tetrahydrofuran;
the calcination temperature of the liquid phase method for depositing the nano carbon layer is 850-1000 ℃, and the calcination time of the liquid phase method for depositing the nano carbon layer is 1.0-1.5h.
5. The method for producing a silicon-based anode material according to claim 1, wherein, in the step S1,
the ion doping treatment is to mix a doping source with the silicon oxide raw material by a liquid phase method or a solid phase method, calcine the mixture, form an ion doping layer on the surface of the silicon oxide raw material, thereby realizing doping,
the doping source is a compound containing any element of boron, magnesium, nitrogen and sulfur;
the calcination temperature in the ion doping treatment is 900-1050 ℃, and the calcination time in the ion doping treatment is 2.0-5.0h.
6. The method for preparing a silicon-based anode material according to claim 5, wherein the ion doping by the liquid phase method comprises the steps of: and dissolving and dispersing the doping source in an organic solvent A2, adding the silicon oxide raw material, performing high-speed dispersion, rotary evaporation or spray drying, and calcining to realize doping to obtain the modified silicon oxide.
7. The method for preparing a silicon-based anode material according to claim 6, wherein the organic solvent A2 is one or more of absolute ethanol, isopropanol, methanol, and tetrahydrofuran.
8. The method for preparing a silicon-based anode material according to claim 5, wherein the solid phase method for ion doping comprises the steps of: and uniformly mixing the doping source with the silicon oxide raw material, compacting, and calcining to realize doping to obtain the modified silicon oxide.
9. The method for producing a silicon-based anode material according to claim 1, wherein, in the step S2,
the carbon source B is one or more of petroleum asphalt, coal asphalt, phenolic resin, polyvinyl alcohol, toluene, phenol, citric acid, sucrose and glucose;
the organic solvent B is one or more of methanol, ethanol, isopropanol, tetrahydrofuran and toluene.
10. The method for producing a silicon-based anode material according to claim 9, wherein in the step S2, the calcination is performed under a protective gas atmosphere,
the shielding gas is helium, nitrogen or argon, or helium, nitrogen or argon mixed with hydrogen, and the content of the hydrogen is 10-30% of that of the shielding gas.
11. The method for producing a silicon-based anode material according to claim 1, wherein, in the step S3,
the carbon-based material is one or more of natural graphite, artificial graphite and mesophase carbon microspheres;
the weight ratio of the silicon-based capacity unit to the carbon-based material is (4:96) - (30:70);
the mixing treatment refers to mixing by adopting one or more modes of a V-shaped mixer, a VC mixer and a ball mill.
12. A silicon-based negative electrode material for lithium ion batteries, characterized in that it is prepared by the method according to any one of claims 1 to 11.
13. A negative electrode of a lithium ion battery, comprising the silicon-based negative electrode material of claim 12.
14. A lithium ion battery comprising a negative electrode, wherein the negative electrode employs the negative electrode of the lithium ion battery of claim 13.
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