CN112952054A - Silicon-based negative electrode material, preparation method, negative electrode and lithium ion battery - Google Patents
Silicon-based negative electrode material, preparation method, negative electrode 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, combining the silicon oxide subjected to the surface modification treatment with few layers of graphene to prepare a silicon-based capacity unit, and mixing the silicon-based capacity unit and a carbon-based material to prepare the silicon-based negative electrode material. The invention also discloses the 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 coulombic 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 cathode materials, and particularly relates to a silicon-based cathode material, a preparation method thereof, a cathode and a lithium ion battery.
Background
With the rapid development of new energy industry, the market has a strong demand for lithium ion batteries with high battery energy density, and the key for improving the energy density of the lithium ion batteries is to develop lithium ion battery materials with high energy density.
In the aspect of the cathode material, the capacity of the traditional graphite cathode material is limited, and the silicon oxide has higher theoretical reversible capacity (more than 2500mAh/g), and the volume effect (less than 150%) is far less than 300% of that of silicon, so that the graphite cathode material has unique advantages compared with the silicon material. However, the problem that the silicon monoxide has poor conductivity, large volume expansion, low first coulombic efficiency and the like exists, and the silicon monoxide is difficult to be directly applied to the lithium ion battery.
In order to solve the problems, at present, a gas phase method or a liquid phase method is generally adopted for carbon coating, or nano modification, metal doping and other means are adopted to improve the electrochemical performance of the carbon-coated carbon-.
Disclosure of Invention
The invention aims to solve the technical problems in the prior art, and provides a silicon-based negative electrode material, a preparation method thereof, a negative electrode and a lithium ion battery, which can improve the reversible capacity and the 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 negative electrode material is provided, and the technical scheme is as follows:
a preparation method of a silicon-based anode material comprises the following steps,
taking the silicon monoxide as a raw material,
firstly, carrying out surface modification treatment on a silicon monoxide raw material,
then the surface modified silicon monoxide is combined with few layers of graphene to prepare a silicon-based capacity unit,
and then mixing the silicon-based capacity unit with the carbon-based material to prepare the silicon-based negative electrode material.
Preferably, the method specifically comprises the following steps:
s1, surface modification treatment: taking a silicon monoxide raw material, and carrying out pre-coating treatment on the silicon monoxide raw material by using a carbon source A, and/or carrying out ion doping treatment on the silicon monoxide raw material by using a doping source to prepare modified silicon monoxide;
s2, preparing a capacity cell: dispersing a carbon source B in an organic solvent B, sequentially adding few-layer graphene and the modified silicon monoxide, 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 monoxide 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 step S1, the pre-coating treatment is to deposit a nano carbon layer on the surface of the raw material of silicon oxide by using a vapor phase method and/or a liquid phase method, wherein the nano carbon layer is a single carbon layer or a composite carbon layer, and the thickness of the nano carbon layer is 5 to 40 nm.
Preferably, the vapor deposition of the nano carbon layer comprises the following steps: heating the silicon monoxide raw material to a deposition temperature, introducing a carbon source A1, and maintaining the deposition temperature to deposit the carbon source A1 on the surface of the silicon monoxide raw material to form a nano carbon layer, thereby obtaining the modified silicon monoxide; the carbon source A1 is one or more of methane, acetylene, ethylene, ethane and butane; the deposition temperature of the vapor phase method is 700-1050 ℃, and the deposition time of the vapor 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 monoxide raw material, uniformly mixing, performing rotary evaporation or spray drying, and calcining to deposit the carbon source A2 on the surface of the silicon monoxide raw material to form a nano carbon layer, thereby obtaining the modified silicon monoxide; 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 calcining temperature of the nano carbon layer deposited by the liquid phase method is 850-1000 ℃, and the calcining time of the nano carbon layer deposited by the liquid phase method is 1.0-1.5 h.
Preferably, in step S1, the ion doping treatment is performed by mixing a doping source with the raw material of silicon monoxide by a liquid phase method or a solid phase method, and then calcining the mixture to form an ion doped layer on the surface of the raw material of silicon monoxide, wherein the doping source is a compound containing any element of boron, magnesium, nitrogen, and sulfur; the calcining temperature in the ion doping treatment is 900-1050 ℃, and the calcining 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 then calcining to realize doping to obtain the modified silicon oxide.
Preferably, the organic solvent A2 is one or more of absolute ethyl alcohol, isopropyl alcohol, methanol and tetrahydrofuran.
Preferably, the ion doping by the solid phase method comprises the following steps: and uniformly mixing the doping source and the silicon monoxide raw material, compacting, and calcining to realize doping to obtain the modified silicon monoxide.
Preferably, 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.
Preferably, in the step S2, 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 monoxide and the organic solvent B is as follows: 1 (5-8) 100-200; the calcining temperature is 850-1000 ℃, and the calcining time is 1.0-5.0 h.
Preferably, in the step 2, the calcination is performed in a protective gas atmosphere, the protective gas is helium, nitrogen, argon, or helium mixed with hydrogen, nitrogen or argon, and the content of hydrogen is 10-30% of the protective gas.
Preferably, in step S3, the carbon-based material is one or more of natural graphite, artificial graphite, and mesocarbon microbeads; the weight ratio of the silicon-based capacity unit to the carbon-based material is (4:96) - (30: 70); the mixing is performed 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 material.
According to another aspect of the present invention, a silicon-based negative electrode material for a lithium ion battery is provided, which has the following technical scheme:
a silicon-based negative electrode material of a lithium ion battery is prepared by the method.
According to another aspect of the present invention, there is provided a lithium ion battery cathode, which comprises:
a negative electrode for a lithium ion battery comprising a silicon-based negative electrode material as described above.
According to another aspect of the present invention, there is provided a lithium ion battery, which comprises the following technical solutions:
a lithium ion battery comprises a negative electrode, wherein the negative electrode is adopted.
The preparation method of the silicon-based negative electrode material and the silicon-based negative electrode material, the negative electrode and the lithium ion battery prepared by the preparation method have the following beneficial effects:
(1) by modifying the surface of the raw material of the silicon monoxide, namely pre-depositing a nano carbon layer and/or carrying out ion doping, the reversible capacity and the charge-discharge efficiency (coulombic efficiency) of the silicon monoxide material can be effectively improved, the conductivity of the silicon monoxide particles is improved, and the volume effect (less than 130%) is reduced;
(2) the few-layer graphene with high specific surface area is used as a carrier, so that modified silicon monoxide is attached to the surface of the few-layer graphene, the volume expansion effect of silicon in the circulation process is further relieved, the conductivity is improved, and the using 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, a solid electrolyte interface film, which is called as an SEI film for short) on the surface of the silicon oxide, so that the consumption of an electrolyte of the lithium ion battery in a circulating process can be reduced, the pulverization of a material in the circulating process of the battery can be improved, and the circulating performance of the lithium ion battery can be improved.
Drawings
Fig. 1 is a schematic structural diagram of a silicon-based negative electrode material according to an embodiment of the present invention;
FIG. 2 is a graph showing the first charge and discharge curves of a SiOx capacity unit in example 2 of the present invention;
fig. 3 is a first charge-discharge curve diagram of the silicon-based negative electrode material for the lithium ion battery in embodiment 3 of the present invention;
FIG. 4 is a TEM image of a modified SiOx layer with a boron-doped and composite nanocarbon layer in example 4 of the present invention;
FIG. 5 shows an X-ray diffraction pattern of modified silica in examples 1 to 3 of the present invention.
In the figure: curve 1-modified silica in example 2; curve 2-modified silica in example 3; curve 3-modified silica from example 4.
Detailed Description
In order to make the technical solutions of the present invention better understood, the present invention will be further clearly and completely described below with reference to the accompanying drawings and specific examples of the present invention.
The method aims at solving the problems of poor conductivity, large volume expansion effect, poor cycle performance and the like of the negative electrode material of the lithium ion battery in the prior art. Therefore, the invention provides a preparation method of a silicon-based negative electrode material of a lithium ion battery, which comprises the following steps,
taking the silicon monoxide as a raw material,
firstly, carrying out surface modification treatment on a silicon monoxide raw material,
then the surface modified silicon monoxide is combined with few layers of graphene to prepare a silicon-based capacity unit,
and then mixing the silicon-based capacity unit with the carbon-based material to prepare the silicon-based negative electrode material.
Correspondingly, the invention also provides a silicon-based negative electrode 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 is adopted.
Example 1
The embodiment discloses a preparation method of a silicon-based negative electrode material of a lithium ion battery, which comprises the following steps: taking silicon monoxide as a raw material, and firstly carrying out surface modification treatment on the silicon monoxide raw material; then, the surface-modified silicon monoxide is combined with few layers of graphene to prepare a silicon-based capacity unit; and then mixing the silicon-based capacity unit with the carbon-based material to obtain a silicon-based negative electrode material product.
The method of the embodiment specifically comprises the following steps:
s1, surface modification treatment: taking a silicon monoxide raw material, and carrying out pre-coating treatment on the silicon monoxide raw material by using a carbon source A and/or carrying out ion doping treatment on the silicon monoxide raw material by using a doping source to prepare the modified silicon monoxide.
In this embodiment, it is preferable to use a silica raw material having a particle diameter of 3 to 12 μm. The pre-coating treatment refers to depositing a nano carbon layer on the surface of the silicon monoxide raw material particles by adopting a gas phase method and/or a liquid phase method, namely: a 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 composite carbon layer is formed on the surface of the silicon oxide raw material by adopting the combination of the gas phase method and the liquid phase method (such as the liquid phase method is adopted firstly and then the gas phase method is adopted for pre-coating), the combination of the gas phase method and the gas phase method (such as the gas phase method is adopted for pre-coating for a plurality of times by adopting different carbon sources, and the gas phase method are particularly suitable for being used when the coating is not uniform enough by adopting the one-time gas phase method), and. In the present embodiment, the thickness of the nano carbon layer is preferably 5 to 40nm, and the carbon layer content is about 0.5 to 7.0%.
Specifically, the method for depositing the nano carbon layer by adopting the vapor phase method comprises the following steps: heating the raw material of the silicon monoxide to a deposition temperature, introducing a carbon source A1, and keeping the deposition temperature to deposit a carbon source A1 on the surface of the raw material of the silicon monoxide to form a compact nano carbon layer, thereby obtaining the modified silicon monoxide 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 vapor phase method is 700-1050 ℃, and the deposition time of the vapor phase method is 0.5-3.0 h.
Specifically, the method for depositing the nano carbon layer by adopting the liquid phase method comprises the following steps: dispersing a carbon source A2 in an organic solvent A1, adding a silicon monoxide raw material, uniformly mixing, performing rotary evaporation or spray drying, calcining (namely high-temperature treatment, also called carbonization treatment and heat treatment), and depositing the carbon source A2 on the surface of the silicon monoxide raw material to form a nano carbon layer to obtain the modified silicon monoxide 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 the silicon monoxide from being oxidized; 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 monoxide accounts for 10-30% of the weight of the organic solvent, and the weight ratio of the carbon source A2 to the silicon monoxide is preferably 2-8%; the calcining temperature of the nano carbon layer deposited by the liquid phase method is 850-1000 ℃, and the calcining time of the nano carbon layer deposited by the liquid phase method 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 vapor phase method than a liquid phase method, the nano carbon layer deposited by the vapor phase method is more uniform and has higher quality, the thickness requirement is thinner, and the thickness of the nano carbon layer deposited by the vapor phase method can be further preferably 5-30 nm.
In this embodiment, the ion doping is to mix a doping source and a raw material of silicon oxide by a liquid phase method or a solid phase method to obtain a mixture, and then calcine the mixture to form an ion doping layer on the surface of the raw material of silicon oxide by the doping source, thereby implementing 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, sulfur and the like; the calcining temperature in the ion doping treatment is 900-1050 ℃, and the calcining time in the ion doping treatment is 2.0-5.0 h.
In this embodiment, the ion doping amount of the silicon monoxide is preferably set to
Since the doping amount is small, the doping source can be selected according to factors such as doping efficiency, as long as the doping ions can be uniformly dispersed to achieve the required doping amount.
Specifically, the ion doping by the liquid phase method comprises the following steps: dissolving and dispersing a doping source in an organic solvent A2, adding a raw material of the silicon oxide, performing high-speed dispersion, rotary evaporation or spray drying, and then calcining (900-1050 ℃) to realize doping, thereby obtaining the modified silicon oxide with the ion doping 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 the doping source.
Specifically, the ion doping by the solid phase method comprises the following steps: and uniformly mixing the doping source and the raw material of the silicon monoxide, compacting, and calcining (900-1050 ℃) to realize doping to obtain the modified silicon monoxide with the ion doping layer on the surface.
S2, preparing a capacity cell: dispersing a carbon source B in an organic solvent B, sequentially adding few-layer graphene and the modified silicon monoxide, uniformly mixing to obtain slurry, and performing rotary evaporation or spray drying, calcination, low-pressure air 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 tests, the silicon-based capacity unit prepared by the method has the capacity of 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 silicon oxide particles, and the modified silicon oxide is attached to the surface of few-layer graphene; the organic solvent B adopts one or more of alcohols (such as absolute ethyl alcohol and methanol), tetrahydrofuran and toluene, is used for dispersing the carbon source B and protecting the silicon monoxide from being oxidized; the weight ratio of the carbon source B to the organic solvent B is 1: 50-200 parts of; the weight ratio of the few-layer graphene, the surface-modified silicon monoxide and the organic solvent B is as follows: 1: 5-8: 100-200; the calcining temperature is 850-1000 ℃, and the calcining time is 1.0-5.0 h; the air breaking is carried out under the condition of low pressure, and the low pressure in the embodiment is preferably 0.005-0.1 MPa; the sieving treatment is preferably carried out by adopting a 100-300-mesh screen to obtain undersize products.
In this embodiment, the calcination process in the process of preparing the capacity unit is preferably performed under a protective gas atmosphere. The protective gas can be helium, nitrogen or argon, or helium mixed with hydrogen, nitrogen or argon, and the content of the hydrogen is 10-30% of the total amount of the protective gas.
S3, compounding carbon-based materials: and (3) mixing the silicon-based capacity units and the carbon-based material to obtain a silicon-based negative electrode material product, wherein the structure of the silicon-based negative electrode material product is shown in figure 1 (SO/C represents a silicon-monoxide carbon coating, Graphene represents a Graphene sheet layer, and Graphite represents Graphite).
The mixing treatment is to uniformly mix the raw materials by one or more modes of a V-shaped mixer (also called a V-shaped mixer, namely a high-efficiency asymmetric mixer), a VC mixer (also called a VC high-efficiency mixer) and a ball mill. The mixing time is preferably 3-5 h.
In this embodiment, the carbon-based material is one or more of natural graphite, artificial graphite, and Mesocarbon Microbeads (MCMB, which is collectively referred to as Mesocarbon Microbeads); the weight ratio of the silicon-based capacity unit to the carbon-based material is preferably (4:96) to (30:70), and may be, for example, 8:92, 4:96, 20: 80, etc.
Through tests, the silicon-based negative electrode material prepared by the method has the capacity of 400-600 mAh/g and the coulombic efficiency of 85-92%, has excellent electrochemical performance, and can be used for preparing a negative electrode of a lithium ion battery and the lithium ion battery.
The embodiment also discloses a silicon-based negative electrode material of the lithium ion battery, which is prepared by adopting the method. Before the silicon monoxide is not modified, the initial coulombic efficiency is lower than 70%, after the modification, the initial coulombic efficiency can be higher than 76%, the few-layer graphene has a high-conductivity and lamellar structure, the electron transmission of the material in the battery cycle process can be modified, and the lamellar structure can buffer the volume expansion, so that the efficiency, the multiplying power and the 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.
According to the preparation method of the silicon-based negative electrode material of the lithium ion battery disclosed by the embodiment, the prepared silicon-based negative electrode material, the prepared negative electrode and the prepared lithium ion battery have the following beneficial effects:
(1) by modifying the surface of the raw material of the silicon monoxide, namely pre-depositing a nano carbon layer and/or carrying out ion doping, the reversible capacity and the charge-discharge efficiency (namely coulombic efficiency) of the silicon monoxide material can be effectively improved, the conductive performance of silicon monoxide particles is improved, and the volume effect (less than 130%) is reduced;
(2) the few-layer graphene with high specific surface area is used as a carrier, so that modified silicon monoxide is attached to the surface of the few-layer graphene, the volume expansion effect of silicon in the circulation process is further relieved, the conductivity is improved, and the using 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 oxidized sub-silicon 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 of the lithium ion battery in the circulating process can be reduced, the pulverization of the material in the battery circulating process can be improved, and the circulating 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 monoxide to form a compact nano carbon layer on the surface of the silicon monoxide, then preparing a silicon-based capacity unit from the modified silicon monoxide 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 monoxide raw material, putting the silicon monoxide raw material into a CVD (chemical vapor deposition) device, heating to 950 ℃, and carrying out heat preservation, wherein the heating rate is preferably 5 ℃/min, and the heat preservation time is preferably 15 min. And then introducing acetylene and argon into the CVD equipment, so that the acetylene is decomposed at 950 ℃ under the argon condition and is deposited on the surface of the oxidized silicon 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 45 min. After the deposition is finished, the material (mainly the modified silicon monoxide) in the CVD equipment is cooled to room temperature along with the furnace under the protection of argon atmosphere, and the modified silicon monoxide with the single nano carbon layer is obtained. During the cooling, the argon flow is preferably 2L/min.
In this embodiment, in order to ensure the uniformity of the nano carbon layer deposited on the surface of the silicon oxide, the CVD equipment used should have a circulating stirring structure, and the stirring effect of the circulating stirring structure is utilized to ensure that acetylene is completely decomposed and fully contacts with the silicon oxide particles, thereby improving the uniformity of the nano carbon layer on the surface of the silicon oxide. The stirring structure has a rotational speed of 3r/pm and the space for deposition in the CDV apparatus (i.e. the furnace chamber) should be lined with graphite. The purity of the gas (acetylene, argon) should be more than 99.99%.
(2) Firstly, adding petroleum asphalt (namely a carbon source B) into isopropanol (namely an organic solvent B), wherein the weight ratio of the petroleum asphalt to the isopropanol is 1: and 60, shearing and dispersing at a high speed for 2.0 hours to uniformly disperse the petroleum asphalt in the isopropanol, wherein the petroleum asphalt can be subjected to ball milling and air crushing to ensure that the particle size distribution of the petroleum asphalt is more uniform, and the particle size of the petroleum asphalt is preferably 5-7 microns. And then adding few-layer graphene, continuing to disperse for 1.0h, adding the modified silica, and dispersing at a high speed for 3.0h to obtain slurry, wherein the weight ratio of the added few-layer graphene, the surface modified silica and isopropanol is 1:6: 60. Then, the slurry is spray-dried and then put into a carbonization furnace to be carbonized (i.e. calcined) for 2.0h under the condition of 950 ℃ and argon atmosphere. And finally, carrying out gas crushing on the calcined product under the condition of 0.1MPa, and then sieving by using a 300-mesh sieve to obtain the silica capacity unit (namely the silicon-based capacity unit). As shown in fig. 2, the first charging and discharging curve of the sub-silicon oxide capacitor unit of this embodiment is shown (the testing process is to perform the charging and discharging test in the voltage range of 0-1.5V, the discharging step is to discharge 0.1C to 0.1V, then discharge 0.09C, 0.08C, … … 0.01.01C to 0.005V, and then charge 0.1C to 1.5V, which is not repeated herein), curve a is the charging curve, and curve B is the discharging curve in fig. 2. As can be seen from FIG. 2, the reversible capacity can reach more than 1550mAh/g, and tests show that the battery efficiency can reach 75.8%, compared with the capacity of less than 1000mAh/g and the efficiency of less than 70% before the silicon monoxide is not modified, the reversible capacity and the efficiency of the battery can be obviously improved after the silicon monoxide is modified by the method of the present embodiment.
(3) And adding the silicon oxide capacity unit and artificial graphite (namely the 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 negative electrode material. Through detection, the capacity of the silicon-based negative electrode material is 550mAh/g, the first charge-discharge efficiency is more than 85%, and the silicon-based negative electrode material has excellent electrochemical performance.
The embodiment also discloses a silicon-based negative electrode 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 negative electrode 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 a silicon oxide twice to form a compact composite nano carbon layer on the surface of the silicon oxide, then preparing a silicon-based capacity unit from the modified silicon oxide and further preparing the silicon-based negative electrode material.
The method comprises the following specific steps:
(1) 3kg of a silicon monoxide material with the particle size of 5-7 microns is taken and put into a conical CVD device, the heating rate is set to be 10 ℃/min, argon is introduced, the flow of the argon is 3L/min, the silicon monoxide particles are heated to 950 ℃ in the argon atmosphere, and the temperature is kept for 15 min. And introducing mixed gas of acetylene and argon, wherein the flow of acetylene is 2.0L/min, the flow of argon is 4L/min, so that acetylene is decomposed at 950 ℃ under the condition of argon and is deposited on the surface of the silicon oxide to form a nano carbon layer, and after 25min of deposition, stopping introducing acetylene. And then, continuously heating the silicon monoxide particles with the nano carbon layer to 1000 ℃ in an argon atmosphere, and introducing a methane and argon mixed gas, wherein the flow rate of methane is 10.0L/min, and the flow rate of argon is 5L/min, so that the methane continuously deposits the nano carbon layer on the surface of the silicon monoxide particles with the nano carbon layer to form a composite nano carbon layer, and the deposition time is 25 min. After the deposition is finished, the material (mainly the modified silicon monoxide) in the CVD equipment is cooled to room temperature along with the furnace under the protection of argon atmosphere, and the modified silicon monoxide with the composite nano carbon layer is obtained. In the cooling process, the flow of argon is preferably 5L/min, the heat in the furnace cavity can be taken away as soon as possible by the larger flow of gas (argon), the cooling speed is accelerated, and the phenomenon that the electrochemical performance of the material is influenced due to excessive disproportionation of the silicon monoxide particles caused by overlong time of the material in a high-temperature environment is avoided.
Considering that the uniformity of carbon layer deposition on the surface of the silicon monoxide particles, the content of metal impurities and the like can directly influence the electrochemical performance of the whole lithium ion battery. Therefore, in the embodiment, the CVD equipment used should have a circulating stirring structure capable of stirring, and the rotation speed of the stirring structure is preferably 4r/pm 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 liner to avoid metal pollution, reduce the self-discharge phenomenon of the lithium ion battery manufactured subsequently in circulation and improve the cycle performance of the lithium ion battery.
(2) Subjecting pitch (i.e. carbon source B, coal pitch, petroleum pitch or other types of pitch) to air-crushing treatment, and adding into tetrahydrofuran (i.e. organic solvent C), wherein the weight ratio of pitch to tetrahydrofuran is preferably 1: 150. and then dispersing at high speed for 1.0h to dissolve and uniformly disperse the coal tar pitch in tetrahydrofuran. Then adding few-layer graphene, continuing to disperse for 1.5h, adding the modified silicon monoxide with the composite nano carbon layer, and dispersing at high speed for 1.0h to obtain slurry, wherein the weight ratio of the added few-layer graphene to the modified silicon monoxide to 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 be carbonized for 2.0h under the conditions of argon atmosphere and 900 ℃, thus obtaining a carbonized product. And finally, carrying out gas 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 a volume unit of the silicon monoxide.
(3) Firstly, the silicon monoxide capacity unit is demagnetized, in this embodiment, a demagnetizing machine is used to demagnetize twice to remove metal impurities and prevent micro short circuit of the lithium ion battery. And then adding the demagnetized silicon oxide capacity units and artificial graphite 830B (namely the 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 surface of the silicon monoxide volume cell particles during the high-speed stirring and mixing of the VC mixer and the influence of the high temperature generated by the high-speed stirring on the structure of the silicon monoxide volume cell, in the embodiment, the mixing is preferably performed under the protection of low-speed stirring and argon atmosphere, and the mixing time is preferably 3.0 h. As shown in fig. 3, a first charging/discharging curve (the testing process is to perform a charging/discharging test in a voltage range of 0-1.5V, the discharging step is to discharge from 0.1C to 0.1V, from 0.09C, 0.08C, … … 0.01.01C to 0.001V, and then from 0.1C to 1.5V) of the silicon-based anode material prepared in this embodiment is shown, in which curve a is a charging curve and curve b is a discharging curve in fig. 3. As can be seen from FIG. 3, the capacity is greater than 550mAh/g, the first charge-discharge efficiency is greater than 86% through the test, and the electrochemical performance is excellent.
The embodiment also discloses a silicon-based negative electrode 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 negative electrode material of a lithium ion battery, which comprises the steps of modifying the surface of silicon oxide, wherein the modification comprises the steps of carrying out liquid-phase method ion doping by using sodium borate as a doping source to form a doping layer, carrying out liquid-phase method deposition by using petroleum asphalt as a carbon source (namely a carbon source A2) to form a single nano carbon layer, and carrying out vapor-phase method deposition by using acetylene as a gas carbon source (namely a carbon source A1) to form a composite nano carbon layer; and preparing a silicon-based capacity unit by using the modified silicon monoxide and further preparing a silicon-based negative electrode material.
The method comprises the following specific steps:
(1) sodium borate is mixed according to the proportion of
The amount of the sodium borate is dissolved in the absolute ethyl alcohol, for example, 1.7g of sodium borate is added into 15kg of absolute ethyl alcohol, 75g of petroleum asphalt with the particle size of 5-7 mu m obtained by ball milling and air breaking treatment is added for high-speed dispersion to form suspension, wherein the dispersion speed is 8000-. In this embodiment, in order to avoid high temperature during high-speed dispersion, it is preferable to use batch dispersion. After the dispersion was completed, 1.5kg of silica was added, and mechanically stirred and mixed for 3.0 hours to obtain a slurry. And (3) performing rotary evaporation treatment on the slurry, and carbonizing the slurry for 3.0 hours at the temperature of 950 ℃ to obtain a carbonized product. The carbonized product is processed by low pressure (such as 0.07MPa) gas crushing and 300-mesh sieving to obtain boron-doped silicon oxide (namely modified silicon oxide). During the boron doping process, part of carbon (derived from petroleum pitch) is deposited on the surface of the silicon oxide by liquid phase deposition, but rarely, the carbon content is only about 2.0%.
In this embodiment, in order to make up for the lack of uniformity of the carbon deposited in the liquid phase, 1.0kg of the modified silicon monoxide is placed in a tapered CVD device, heated to 950 ℃ at a heating rate of 5 ℃/min under the protection of argon, and then mixed gas of acetylene and argon is introduced, wherein the flow rate of acetylene is 1.0L/min and the flow rate of argon is 3L/min, so that acetylene is decomposed at 950 ℃ and under the condition of argon and is deposited on the surface of the silicon monoxide for 30min to form a composite nanocarbon layer, and thus modified silicon monoxide having a boron-doped and composite nanocarbon layer is 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, which can improve the conductivity of the material, and further improve the reversible capacity and coulombic efficiency of the material. As can be seen from curves 1-3 in FIG. 5, the modified silicon monoxide is obviously crystallized after being subjected to high-temperature treatment, and the crystallization shows that the relative content of nano-silicon crystals in the silicon monoxide is increased, and the silicon has higher capacity and coulombic efficiency compared with the silicon monoxide, so that the increase of the silicon content is beneficial to improving the reversible capacity and coulombic efficiency of the modified silicon monoxide.
In this embodiment, the CVD apparatus should have a circular stirring structure, the rotation speed of the stirring structure is 3rpm, and the inner wall of the furnace chamber of the CVD apparatus is made of a ceramic lining, such as alumina.
(2) Preparation of a silica capacity unit: adding the petroleum asphalt (namely the carbon source B) subjected to ball milling treatment into absolute ethyl alcohol (namely the organic solvent B), wherein the weight ratio of the petroleum asphalt to the absolute ethyl alcohol is 1:180, and then shearing and dispersing at high speed for 1.0h to uniformly disperse the petroleum asphalt in the absolute ethyl alcohol. Then adding few-layer graphene, continuing to disperse for 1.0h, adding the modified silicon monoxide with the boron-doped and composite nano carbon layer, continuing to disperse for 1.0h at a high speed, and obtaining slurry, wherein the weight ratio of the added few-layer graphene to the modified silicon monoxide to the absolute ethyl alcohol is 1:7: 180. and then, carrying out rotary evaporation treatment on the slurry, putting the slurry into a carbonization furnace, and carbonizing the slurry for 3.0 hours at 850 ℃ in an argon atmosphere to obtain a carbonized product. And finally, carrying out gas 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 a silicon monoxide capacity unit.
(3) Firstly, the silicon oxide capacity unit is demagnetized and sieved by a 300-mesh screen twice. Then, the treated silica capacity unit and artificial graphite (preferably, artificial graphite S360 series graphite produced by Beibei company) are added into a V-shaped mixer according to the weight ratio of 96: 4 and uniformly mixed for 5.0h to obtain the silicon-based negative electrode material. Through detection, the capacity of the silicon-based negative electrode material is larger than 420mAh/g, and the first charge-discharge efficiency is larger than 92%.
The embodiment also discloses a silicon-based negative electrode 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 cathode material of a lithium ion battery, which comprises the steps of modifying the surface of silicon oxide, wherein ion doping is carried out by adopting a solid phase method to form a doping layer, and then a nano carbon layer is deposited by adopting a gas phase method to form modified silicon oxide with the doping layer and the nano carbon layer; and preparing a silicon-based capacity unit by using the modified silicon monoxide and further preparing a silicon-based negative electrode material.
The method comprises the following specific steps:
(1) to a doping ratio of
The boric acid and the silica are added into a V-shaped mixer, mixed for 5.0h, compacted into blocks under the action of 500kg of pressure, such as circular blocks, and then placed into a high-temperature furnace to be calcined for 3.0h under the inert gas atmosphere and 960 ℃ so as to realize boron doping, and a doped product (namely, the modified silica) is obtained. And then the doped product is subjected to gas crushing, 300-mesh sieving and other treatment, so that the particle size 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 above-mentioned modified silica subjected to doping treatment was placed in a CVD rotary furnace and heated to 1000 ℃ under a protective gas atmosphere. And then, introducing methane, argon and carbon dioxide at the temperature of 1000 ℃, wherein the flow rate of methane is 500sccm, the flow rate of argon is 500sccm, and the flow rate of carbon dioxide is 100sccm, so that the methane and the carbon dioxide (namely a carbon source A1) are deposited on the surface of the doped modified silicon oxide for 30-50min to form a nano carbon layer, and the modified silicon oxide with the doped layer and the single nano carbon layer is obtained.
In this embodiment, the rotation speed of the furnace chamber of the CVD rotary furnace is 2rpm, and the furnace chamber is made of a quartz tube.
(3) Dissolving citric acid (namely carbon source B) in absolute ethyl alcohol (namely organic solvent B), wherein the weight ratio of the citric acid to the absolute ethyl alcohol is 1:200, and then dispersing at high speed for 1.0h to uniformly disperse the citric acid in the absolute ethyl alcohol. Then adding few-layer graphene, continuing to disperse for 0.5h, adding the modified silica with the doped layer and the single nano carbon layer, continuing to disperse for 1.0h at a high speed to obtain slurry, wherein the weight ratio of the added few-layer graphene to the modified silica to the absolute ethyl alcohol is 1:6: 200. and then, carrying out rotary evaporation treatment on the slurry, then putting the slurry into a carbonization furnace, carbonizing the slurry for 2.0h at 650 ℃ in a reducing atmosphere to obtain a carbonized product, and carrying out low-pressure (such as 0.05MPa) air crushing and 325-mesh sieving treatment on the carbonized product to obtain a silicon monoxide capacity unit.
(4) Adding the silica content unit and artificial graphite (such as artificial graphite imported from Japan) at weight ratio of 86: 14 into VC mixer, and mixing for 1.0h to obtain silicon-based negative electrode material. Through detection, the capacity of the silicon-based anode material of the embodiment is 510 mAh/g.
The embodiment also discloses a silicon-based negative electrode 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 cathode material of a lithium ion battery, which comprises the steps of modifying 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 doping layer, and then depositing a nano carbon layer by adopting a vapor phase method to form modified silicon oxide with the doping layer and the nano carbon layer; and preparing a silicon-based capacity unit by using the modified silicon monoxide and further preparing a silicon-based negative electrode material.
The method comprises the following specific steps:
(1) adding 0.3g of citric acid and 50g of boric acid into 10kg of anhydrous sodium borateAnd dispersing and dissolving in ethanol at high speed for 1.0h, adding 1.0kg of silica particles, and continuously dispersing at high speed for 1.0h to obtain slurry. In this example, silica having a particle size D50 of 4 μm is preferably used. And then, carrying out spray treatment on the slurry to obtain a precursor, putting the precursor into a carbonization furnace, and calcining (carbonizing) the precursor for 2.0 hours under the conditions of reducing atmosphere protection and 960 ℃ to obtain a carbonized product. The carbonized product is processed by low pressure (such as 0.07MPa) air breaking and sieving (such as 300 meshes) to obtain the boron-doped modified silicon monoxide. The doping amount of boron in this embodiment is detected to be
(2) And (3) placing 600g of the boron-doped modified silicon monoxide in a CVD rotary furnace, heating to 950 ℃, introducing acetylene and argon mixed gas, and preserving the heat for 35min to deposit acetylene on the surface of the boron-doped modified silicon monoxide to form a nano carbon layer, thereby obtaining the modified silicon monoxide with the doped layer and the nano carbon layer.
In this embodiment, the flow ratio of acetylene to argon in the introduced mixed gas of acetylene and 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 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 by using a high-speed dispersion machine at 15000rpm, sequentially adding the few-layer graphene and the modified silica, wherein the weight ratio of the few-layer graphene, the modified silica and the isopropanol is 1:7: 100, and then continuously 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 argon atmosphere and at 930 ℃, and then is subjected to low-pressure (such as 0.08Mpa) air crushing treatment and two-time 325-mesh screen sieving to obtain a volume unit of the silicon oxide.
(4) Adding the silicon oxide capacity unit and graphite into a cone-shaped circulating 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 negative electrode material. Through detection, the first charge-discharge reversible capacity of the negative electrode material estimated in the embodiment is larger than 450mAh/g, the efficiency is larger than 90%, and the negative electrode material has excellent electrochemical performance.
The embodiment also discloses a silicon-based negative electrode 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 cathode material of a lithium ion battery, which comprises the steps of modifying the surface of silicon oxide, wherein the ion doping is carried out by adopting a solid phase method to form a doping layer, and then a nano carbon layer is deposited twice by adopting a gas phase method to form modified silicon oxide with the doping layer and a composite nano carbon layer; and preparing a silicon-based capacity unit by using the modified silicon monoxide and further preparing a silicon-based negative electrode material.
The method comprises the following specific steps:
(1) the magnesium oxide (i.e. doping source) is doped in the proportion of
The amount of (2) and silica were added to a type V blender and mixed for 3.0 h. 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 placed into a condition with the temperature of more than 950 ℃ to be calcined for 3.0h, so as to realize magnesium doping, and the modified silicon monoxide doped with magnesium is obtained. The modified silicon monoxide is subjected to low-pressure air crushing (such as 0.06MPa) and sieving (such as 300 meshes) for later use.
(2) And (2) placing 500g of the magnesium-doped modified silicon monoxide in a CVD (chemical vapor deposition) equipment furnace cavity, heating to 800 ℃, and introducing ethylene (namely a carbon source A1) and nitrogen, wherein the flow rate of the ethylene is 500sccm, and the flow rate of the nitrogen is 500sccm, so that the ethylene is deposited on the surface of the silicon monoxide under the nitrogen atmosphere and at 800 ℃ to form a nano carbon layer, and the modified silicon monoxide with the magnesium-doped and single nano carbon layer is obtained. In the embodiment, the deposition time is preferably 50min by using ethylene as a carbon source. And then, continuously heating the modified silicon monoxide with the magnesium doping and the single nano carbon layer to the temperature of 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 300 sccm. And then, continuously heating to 1000 ℃, and keeping for 30min to ensure that a layer of nano carbon layer is deposited on the surface of the modified silicon monoxide again to obtain the modified silicon monoxide with the magnesium doped layer and the composite nano carbon layer. After the deposition is finished, the modified silicon monoxide is cooled to room temperature along with the furnace in the argon atmosphere, and the argon flow in the cooling process is 1000 sccm.
In this example, the heating rate of the modified silica was 5 ℃/min. In the carbon deposition process in the step (2), the furnace chamber of the CVD equipment is rotated at 3rpm, and the furnace chamber is preferably made of quartz or ceramic to prevent contamination by metal impurities.
(3) Adding the petroleum asphalt 280 (namely a carbon source B) subjected to air-assisted pulverization into isopropanol (namely an organic solvent B), wherein the weight ratio of the petroleum asphalt 280 to the isopropanol is 1:120, carrying out high-speed shearing dispersion for 1.0h, adding few-layer graphene, and continuing to carry out high-speed dispersion for 0.5 h; and adding the modified silicon monoxide with the magnesium doped layer and the composite nano carbon layer, wherein the weight ratio of the few-layer graphene to the modified silicon monoxide to the isopropanol is 1:7:120, and continuously dispersing at high speed for 2.0h to obtain slurry. Then, the slurry is subjected to spray drying treatment, and is put into a carbonization furnace, and is carbonized for 1.5h under the condition of argon atmosphere and 950 ℃, and then is subjected to low-pressure (such as 0.08Mpa) air crushing treatment and sieving (such as 300 meshes) to obtain a volume unit of the silicon oxide.
(4) Adding the volume unit of the silicon oxide and the volume of the graphite 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 negative electrode material. Through detection, the capacity of the silicon-based negative electrode material is 400-600 mAh/g, and the silicon-based negative electrode material has excellent electrochemical performance.
The embodiment also discloses a silicon-based negative electrode 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 will be understood that the foregoing is only a preferred embodiment of the invention, and that the invention is not limited thereto. It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention, and these changes and modifications are to be considered as within the scope of the invention.
Claims (16)
1. A preparation method of a silicon-based anode material comprises the following steps,
taking the silicon monoxide as a raw material,
firstly, carrying out surface modification treatment on a silicon monoxide raw material,
then the surface modified silicon monoxide is combined with few layers of graphene to prepare a silicon-based capacity unit,
and then mixing the silicon-based capacity unit with the carbon-based material to prepare the silicon-based negative electrode material.
2. The preparation method of the silicon-based anode material as claimed in claim 1, wherein the method specifically comprises the following steps:
s1, surface modification treatment: taking a silicon monoxide raw material, and carrying out pre-coating treatment on the silicon monoxide raw material by using a carbon source A, and/or carrying out ion doping treatment on the silicon monoxide raw material by using a doping source to prepare modified silicon monoxide;
s2, preparing a capacity cell: dispersing a carbon source B in an organic solvent B, sequentially adding few-layer graphene and the modified silicon monoxide, 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;
s3, compounding carbon-based materials: and mixing the silicon-based capacity units with the carbon-based material to ensure that the silicon-based capacity units can be uniformly dispersed in the carbon-based material so as to prepare a silicon-based negative electrode material product.
3. The method for preparing silicon-based anode material according to claim 2, 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 5-40 nm.
4. The method for preparing the silicon-based anode material as claimed in claim 3, wherein the step of depositing the nano carbon layer by the vapor phase method comprises the following steps: heating the raw material of the silicon monoxide to a deposition temperature, introducing a carbon source A1, keeping the deposition temperature, and depositing on the surface of the raw material of the silicon monoxide to form a nano carbon layer to obtain the modified silicon monoxide;
the carbon source A1 is one or more of methane, acetylene, ethylene, ethane and butane;
the deposition temperature of the vapor phase method is 700-1050 ℃, and the deposition time of the vapor phase method is 0.5-3.0 h.
5. The preparation method of the silicon-based anode material as claimed in claim 3, wherein the step of depositing the nano carbon layer by the liquid phase method comprises the following steps: dispersing a carbon source A2 in an organic solvent A1, adding the silicon monoxide raw material, uniformly mixing, performing rotary evaporation or spray drying, calcining, and depositing on the surface of the silicon monoxide raw material to form a nano carbon layer to obtain the modified silicon monoxide;
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 calcining temperature for depositing the nano carbon layer by the liquid phase method is 850-1000 ℃, and the calcining time for depositing the nano carbon layer by the liquid phase method is 1.0-1.5 h.
6. The method for preparing silicon-based anode material according to claim 2, wherein, in the step S1,
the ion doping treatment is to mix a doping source and the raw material of the silicon monoxide by adopting a liquid phase method or a solid phase method, then calcine the mixture, form an ion doping layer on the surface of the raw material of the silicon monoxide, thereby realizing doping,
the doping source is a compound containing any element of boron, magnesium, nitrogen and sulfur;
the calcining temperature in the ion doping treatment is 900-1050 ℃, and the calcining time in the ion doping treatment is 2.0-5.0 h.
7. The preparation method of the silicon-based anode material as claimed in claim 6, wherein 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 then calcining to realize doping to obtain the modified silicon oxide.
8. The method for preparing the silicon-based anode material of the lithium ion battery as claimed in claim 7, wherein the organic solvent A2 is one or more of absolute ethyl alcohol, isopropyl alcohol, methanol and tetrahydrofuran.
9. The preparation method of the silicon-based anode material as claimed in claim 6, wherein the ion doping by the solid phase method comprises the following steps: and uniformly mixing the doping source and the silicon monoxide raw material, compacting, and calcining to realize doping to obtain the modified silicon monoxide.
10. The method for preparing silicon-based anode material according to claim 2, 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.
11. The method for preparing silicon-based anode material according to claim 10, wherein, in the step S2,
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 modified silicon monoxide and the organic solvent B is as follows: 1 (5-8) 100-200;
the calcining temperature is 850-1000 ℃, and the calcining time is 1.0-5.0 h.
12. The method for preparing a silicon-based anode material according to claim 11, wherein in the step S2, the calcination is performed in a protective gas atmosphere,
the protective gas is helium, nitrogen or argon, or helium mixed with hydrogen, nitrogen or argon, and the content of the hydrogen is 10-30% of the protective gas.
13. The method for preparing silicon-based anode material according to claim 2, wherein, in the step S3,
the carbon-based material is one or more of natural graphite, artificial graphite and mesocarbon microbeads;
the weight ratio of the silicon-based capacity unit to the carbon-based material is (4:96) - (30: 70);
the mixing treatment is to adopt one or more modes of a V-shaped mixer, a VC mixer and a ball mill to mix.
14. A silicon-based negative electrode material for a lithium ion battery, characterized by being prepared by the method of any one of claims 1 to 13.
15. A negative electrode of a lithium ion battery, comprising the silicon-based negative electrode material of claim 14.
16. A lithium ion battery comprising a negative electrode, wherein the negative electrode of claim 15 is used as the negative electrode.
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