CN112490423A - Silicon negative electrode material, preparation method thereof and lithium ion battery comprising silicon negative electrode material - Google Patents

Silicon negative electrode material, preparation method thereof and lithium ion battery comprising silicon negative electrode material Download PDF

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CN112490423A
CN112490423A CN202011257852.0A CN202011257852A CN112490423A CN 112490423 A CN112490423 A CN 112490423A CN 202011257852 A CN202011257852 A CN 202011257852A CN 112490423 A CN112490423 A CN 112490423A
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silicon
negative electrode
electrode material
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precursor
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褚光辉
余剑琳
马美品
蔡惠群
李海军
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Yinlong New Energy Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
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    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
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    • H—ELECTRICITY
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention provides a silicon negative electrode material, a preparation method thereof and a lithium ion battery comprising the silicon negative electrode material. The silicon cathode material is of a core-shell structure, wherein a core layer is a nano silicon sphere, and a shell layer is TiO with a bicontinuous phase structure2a/C composite layer. The silicon anode material provided by the invention solves the problems of poor conductivity, poor cycle performance and the like of a silicon-based anode material, has low requirement on produced equipment, is environment-friendly and is suitable for industrialization.

Description

Silicon negative electrode material, preparation method thereof and lithium ion battery comprising silicon negative electrode material
Technical Field
The invention relates to the field of lithium ion batteries, in particular to a silicon negative electrode material, a preparation method thereof and a lithium ion battery comprising the silicon negative electrode material.
Background
In recent years, lithium ion batteries have been widely used in electronic devices, electric vehicles, and energy storage power stations due to their advantages of high operating voltage, small self-discharge effect, long cycle life, no memory effect, and environmental friendliness. However, the current commercialized lithium ion battery cathode material mainly adopts graphite electrode material, but the theoretical specific capacity is only 372mAh/g, and the energy demand cannot be increased day by day.
The theoretical specific capacity of the silicon-based negative electrode material is up to 4200mAh/g, is more than 10 times of the capacity of a graphite negative electrode, is rich in reserves and wide in source, and is considered to be a candidate of the current best negative electrode material. However, the silicon-based negative electrode material has a serious volume effect in the lithium removal/insertion process, and the volume expansion can reach more than 300%, so that the structure of the material collapses and the conductive matrix loses contact, and meanwhile, a large amount of lithium ions are consumed in the continuous formation and decomposition process of an SEI film, and finally the capacity of the silicon-based material is rapidly reduced. The structure of the silicon material can be supported to a certain degree by coating a layer of material on the surface of the silicon material, and the electrochemical performance of the silicon-based cathode material is improved.
In the prior art, a composite lithium battery cathode material and a preparation method thereof are disclosed in a Chinese patent with publication number of CN108878815A and publication date of 2018.11.23, and the composite lithium battery cathode material is prepared by adopting a nano nonmetal matrix, a metal dopant, inorganic silicon salt, polyvinylidene fluoride, a modifier, a carbonization regulator, a conductive agent, a binder and dopamine. Although the material can improve the electrochemical performance to a certain extent, the conductivity of the material is improved. However, the method still has problems that the method has an insufficient effect of inhibiting the side reaction of the material, and the electrolyte is continuously consumed in the charge-discharge cycle process, resulting in poor cycle performance.
Disclosure of Invention
The invention mainly aims to provide a silicon cathode material, a preparation method thereof and a lithium ion battery comprising the silicon cathode material, so as to solve the problem of poor cycle performance of the silicon cathode material in the prior art.
In order to achieve the above object, according to one aspect of the present invention, there is provided a silicon anode material having a core-shell structure, wherein the core layer is a nano-silicon sphere, and the shell layer is TiO having a bicontinuous phase structure2a/C composite layer.
Further, TiO2TiO in/C composite layer2The weight ratio of C to C is (4-5) to (3-4).
Further, the thickness of the shell layer is 50-200 nm.
Furthermore, the particle size of the nano silicon spheres is 100-500 nm.
According to another aspect of the present invention, there is also provided a preparation method of the silicon anode material, which includes the following steps: s1, mixing an organic titanium source, an organic carbon source and an organic solvent to form a first mixed solution; s2, adding and dispersing the nano silicon spheres in the first mixed solution, and then adding a hydrolysis stabilizer to form a second mixed solution; s3, carrying out hydrothermal reaction on the second mixed solution, and cooling to obtain a precursor; and S4, calcining the precursor in an inert atmosphere to obtain the silicon negative electrode material.
Further, the organic titanium source is one or more of titanium tetraisopropoxide, butyl titanate and tetraethoxytitanate; preferably, the organic carbon source is one or more of polyvinylpyrrolidone, aniline, polyacrylate, and polyvinyl alcohol.
Further, in step S1, the weight ratio of the organic titanium source to the organic carbon source is (3-5): 1, the organic solvent is a mixed solvent of anhydrous ethanol and deionized water, and preferably, the volume ratio of the anhydrous ethanol to the deionized water is (1-2): 1; preferably, the mass concentration of the organic titanium source and the organic carbon source in the first mixed solution is 20-35%.
Further, in step S2, the weight ratio of the nano silicon spheres to the organic carbon source is (1.5-2.5): 1; preferably, the volume ratio of the hydrolysis stabilizer to the organic titanium source is (2.5-3.5): 1.
Further, in step S3, heating the second mixed solution to 150-180 ℃ at a speed of 5-10 ℃/min, and preserving heat for 10-15 hours to perform a hydrothermal reaction; after the reaction is finished, cooling to room temperature, filtering, washing and drying to obtain a precursor; preferably, in step S4, the precursor is heated to 700-800 ℃ at a speed of 5-10 ℃/min, and the temperature is maintained for 3-5 h to perform the calcination process.
According to another aspect of the present invention, there is also provided a lithium ion battery, including an anode material, wherein the anode material is the silicon anode material.
The invention provides a bicontinuous phase TiO2The silicon negative electrode material formed by coating the nano silicon spheres with the C solves the problems of poor conductivity, poor cycle performance and the like of the silicon-based negative electrode material, has low requirement on produced equipment, is environment-friendly and is suitable for industrialization.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 shows a schematic structural view of a silicon anode material according to the present invention; and
fig. 2 shows the cycle performance curves of the silicon negative electrode materials prepared in examples 1 to 6 of the present invention corresponding to the batteries, wherein the solid arrow direction is the curve corresponding to the initial specific capacity from high to low, and the dotted arrow direction is the curve corresponding to the capacity retention rate at the end of the cycle from high to low.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
As described in the background art, although the prior art has been directed to improvements in the conductivity and the like of silicon negative electrode materials, there still remains a drawback in terms of cycle performance.
In order to solve the above problems, the present invention provides a silicon negative electrode material, as shown in fig. 1, the silicon negative electrode material is of a core-shell structure, wherein the core layer a is a nano-silicon sphere, and the shell layer B is TiO having a bicontinuous phase structure2a/C composite layer. The silicon cathode material is provided with a dual junctionTiO with continuous phase structure2The core-shell structure of the/C shell layer coating nano silicon spheres can relieve the volume effect of Si in the process of lithium desorption and intercalation and can improve the conductivity of the material. And TiO of bicontinuous phase structure2the/C shell layer can not only protect the material from being corroded by the electrolyte, but also protect the material from being corroded by the electrolyte LiPF6Avoiding chemical reaction with HF, being beneficial to forming SEI film with stable structure, and further improving the cycling stability of the material. Meanwhile, the material also has good thermal stability, and the heat of chemical reaction in the material is effectively reduced.
In a word, the silicon cathode material effectively solves the problem that the silicon cathode material in the prior art cannot give consideration to high conductivity and good cycle performance, the provided silicon cathode material has good cycle stability and high rate performance, and the capacity retention rate of a battery is 97.5% after the battery is cycled for 100 times under the current density of 2A/g. And the method has low requirements on the produced equipment, is environment-friendly and is suitable for industrialization.
In order to further improve the properties of the silicon anode material, in a preferred embodiment, TiO2TiO in/C composite layer2The weight ratio of C to C is (4-5) to (3-4). More preferably, the thickness of the shell layer is 50 to 200 nm. Furthermore, the particle size of the nano silicon spheres is 100-500 nm.
According to another aspect of the present invention, there is also provided a preparation method of the silicon anode material, wherein the preparation method comprises the following steps: s1, mixing an organic titanium source, an organic carbon source and an organic solvent to form a first mixed solution; s2, adding and dispersing the nano silicon spheres in the first mixed solution, and then adding a hydrolysis stabilizer to form a second mixed solution; s3, carrying out hydrothermal reaction on the second mixed solution, and cooling to obtain a precursor; and S4, calcining the precursor in an inert atmosphere to obtain the silicon negative electrode material.
In the method, an organic titanium source and an organic carbon source are prepared into a first mixed solution in advance, then nano silicon spheres and a hydrolysis stabilizer are added to form a stable second mixed solution, then a hydrothermal reaction is carried out, the organic titanium source is gradually hydrolyzed in the process and is coated on the nano silicon spheres together with the organic carbon sourceAnd forming a precursor on the surface. The precursor is further calcined, and TiO with a bicontinuous structure is uniformly coated on the surface of the nano silicon sphere2A shell layer of/C.
The hydrothermal method can coat TiO with a bicontinuous structure on the surface of the nano silicon spheres uniformly2the/C shell layer has good promotion effects on the thermal stability of the silicon cathode material and the reduction of the internal reaction heat of the material, so that the electric conductivity, the cycle performance and the like can be effectively improved. Meanwhile, the method has the advantages of simple and convenient process, low production cost, easy operation and high efficiency.
In a preferred embodiment, the organic titanium source is one or more of titanium tetraisopropoxide, butyl titanate, tetraethyl titanate; preferably, the organic carbon source is one or more of polyvinylpyrrolidone, aniline, polyacrylate, and polyvinyl alcohol. By using the organic titanium sources and the organic carbon sources, on one hand, the reaction process is stable, the coating layer in the precursor is uniform, and correspondingly, the finally formed shell TiO is2the/C has a more complete bicontinuous phase structure, and has better improvement on the overall performance of the material. On the other hand, the organic titanium source and the organic carbon source have lower cost and are beneficial to reducing the production cost of materials.
In order to further improve the reaction stability and promote the formation of a shell bicontinuous phase structure, in a preferred embodiment, in step S1, the weight ratio of the organic titanium source to the organic carbon source is (3-5): 1, the organic solvent is a mixed solvent of anhydrous ethanol and deionized water, and the volume ratio of the anhydrous ethanol to the deionized water is (1-2): 1; preferably, the mass concentration of the organic titanium source and the organic carbon source in the first mixed solution is 20-35%. In the actual mixing process, the organic titanium source is preferably stirred with the organic carbon source and the organic solvent in a magnetic stirrer sufficiently to form a uniformly mixed solution. And in the process of adding the nano silicon spheres, the system is also kept in the process of continuous stirring, after the nano silicon spheres are added, the system is firstly ultrasonically dispersed for a period of time, and then the hydrolysis stabilizer is added.
In a preferred embodiment, in step S2, the weight ratio of the nano silicon spheres to the organic carbon source is (1.5-2.5): 1; preferably, the volume ratio of the hydrolysis stabilizer to the organic titanium source is (2.5-3.5): 1. At the proportion, the thickness of the formed shell layer is more suitable, and the reaction process is more stable.
In order to further improve the reaction efficiency, the structural integrity and the like, in a preferred embodiment, in step S3, the temperature of the second mixed solution is raised to 150-180 ℃ at a rate of 5-10 ℃/min, and the temperature is maintained for 12 hours to perform the hydrothermal reaction; and after the reaction is finished, cooling to room temperature, filtering, washing and drying to obtain the precursor. In practice, the second mixed solution is preferably transferred to a stainless steel reaction vessel and placed in a thermostat.
Preferably, in step S4, the precursor is heated to 700-800 ℃ at a speed of 5-10 ℃/min, and the temperature is maintained for 3-5 h to perform the calcination process. The inert atmosphere used in the calcination process may be nitrogen, argon, or the like. The particular calcination process may be carried out in a tube furnace.
According to another aspect of the present invention, there is also provided a lithium ion battery comprising the anode material, which is the silicon anode material described above.
The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.
Example 1
S1, dissolving 2ml of Titanium Tetraisopropoxide (TTIP) and 0.5g of polyvinylpyrrolidone (PVP) in a mixed solvent of absolute ethyl alcohol and deionized water, wherein the volume ratio of the absolute ethyl alcohol to the deionized water is 1:1, and fully stirring for 15min by using a magnetic stirrer;
s2, under the condition of continuous stirring, adding 1g of nano silicon material with the particle size of 100-500 nm into the solution A obtained in the step S1, performing ultrasonic dispersion for 30min, adding 6ml of acetic acid, stirring at room temperature for 3h, and fully reacting to obtain a solution B;
s3, transferring the solution B obtained in the step S2 to a stainless steel reaction kettle, placing the stainless steel reaction kettle in a thermostat, heating to 165 ℃ at a heating rate of 5 ℃/min, preserving heat for 12 hours, cooling to room temperature along with the furnace, washing, and drying to obtain a precursor C;
s4, weighing the precursor C prepared in the step S3, placing the precursor C in a tube furnace, heating to 750 ℃ at a heating rate of 5 ℃ under a protective atmosphere, preserving heat for 3 hours, and then cooling to room temperature along with the furnace to obtain the silicon-based anode material with the bicontinuous phase structure, which is marked as Si @ TiO2The thickness of a shell layer of the material is 100-200nm, and TiO in the shell layer2The weight ratio of C to C is 5: 3.
The test method comprises the following steps: mixing the prepared silicon-based negative electrode material with a conductive agent sp and a binding agent CMC + SBR (1:1) in a mass ratio of 70:15:15 to prepare slurry, fully grinding and mixing the slurry, uniformly coating the slurry on a metal copper foil, drying the metal copper foil at a constant temperature of 60 ℃ for 6 hours, punching the metal copper foil into a pole piece with the diameter of 12mm by using a punch, transferring the pole piece into a glove box in a protective atmosphere, and adopting a LiPF with a metal lithium piece as a counter electrode and 1mol/L electrolyte6And (EC: DMC 1:1) and Celgard2400 diaphragm, and sequentially assembling the components into a 2032 type button cell. After standing for 24h, transferring the mixture to a Xinwei test system to perform constant-current charge-discharge test at a certain current density, wherein the charge-discharge cut-off voltage interval is 0.01V-1.5V, and the obtained cycle performance curve is shown in figure 2.
Example 2
S1, dissolving 2ml of butyl titanate (TBT) and 0.5g of polyvinylpyrrolidone (PVP) in a mixed solvent of absolute ethyl alcohol and deionized water, wherein the volume ratio of the absolute ethyl alcohol to the deionized water is 1:1, and fully stirring for 15min by using a magnetic stirrer;
s2, under the condition of continuous stirring, adding 1g of nano silicon material with the particle size of 100-500 nm into the solution A obtained in the step S1, performing ultrasonic dispersion for 30min, then adding 6ml of diethanol amine, stirring at room temperature for 3h, and fully reacting to obtain a solution B;
s3, transferring the solution B obtained in the step S2 to a stainless steel reaction kettle, placing the stainless steel reaction kettle in a thermostat, heating to 165 ℃ at a heating rate of 5 ℃/min, preserving heat for 12 hours, cooling to room temperature along with the furnace, washing, and drying to obtain a precursor C;
s4, weighing the precursor C prepared in the step S3, placing the precursor C in a tube furnace, heating to 750 ℃ at a heating rate of 5 ℃ under a protective atmosphere, preserving heat for 3 hours, and then cooling to a chamber along with the furnaceHeating to obtain the silicon-based anode material with the bicontinuous phase structure, which is marked as Si @ TiO2The thickness of a shell layer of the material is 100-200nm, and TiO in the shell layer2The weight ratio of C to C is 4.5: 3.
The test method comprises the following steps: mixing the prepared silicon-based negative electrode material with a conductive agent sp and a binding agent CMC + SBR (1:1) in a mass ratio of 70:15:15 to prepare slurry, fully grinding and mixing the slurry, uniformly coating the slurry on a metal copper foil, drying the metal copper foil at a constant temperature of 60 ℃ for 6 hours, punching the metal copper foil into a pole piece with the diameter of 12mm by using a punch, transferring the pole piece into a glove box in a protective atmosphere, and adopting a LiPF with a metal lithium piece as a counter electrode and 1mol/L electrolyte6And (EC: DMC 1:1) and Celgard2400 diaphragm, and sequentially assembling the components into a 2032 type button cell. After standing for 24h, transferring the mixture to a Xinwei test system to perform constant-current charge-discharge test at a certain current density, wherein the charge-discharge cut-off voltage interval is 0.01V-1.5V, and the obtained cycle performance curve is shown in figure 2.
Example 3
S1, dissolving 2ml of Titanium Tetraisopropoxide (TTIP) and 0.5g of Aniline (ANI) in a mixed solvent of absolute ethyl alcohol and deionized water, wherein the volume ratio of the absolute ethyl alcohol to the deionized water is 1:1, and fully stirring for 15min by using a magnetic stirrer;
s2, under the condition of continuous stirring, adding 1g of nano silicon material with the particle size of 100-500 nm into the solution A obtained in the step S1, performing ultrasonic dispersion for 30min, adding 6ml of acetic acid, stirring at room temperature for 3h, and fully reacting to obtain a solution B;
s3, transferring the solution B obtained in the step S2 to a stainless steel reaction kettle, placing the stainless steel reaction kettle in a thermostat, heating to 165 ℃ at a heating rate of 5 ℃/min, preserving heat for 12 hours, cooling to room temperature along with the furnace, washing, and drying to obtain a precursor C;
s4, weighing the precursor C prepared in the step S3, placing the precursor C in a tube furnace, heating to 750 ℃ at a heating rate of 5 ℃ under a protective atmosphere, preserving heat for 3 hours, and then cooling to room temperature along with the furnace to obtain the silicon-based anode material with the bicontinuous phase structure, which is marked as Si @ TiO2The shell layer thickness of the/C cathode material is 100-200nm, and TiO in the shell layer2The weight ratio of C to C is 5: 3.5.
the test method comprises the following steps: mixing the prepared silicon-based negative electrode material with a conductive agent sp and a binding agent CMC + SBR (1:1) in a mass ratio of 70:15:15 to prepare slurry, fully grinding and mixing the slurry, uniformly coating the slurry on a metal copper foil, drying the metal copper foil at a constant temperature of 60 ℃ for 6 hours, punching the metal copper foil into a pole piece with the diameter of 12mm by using a punch, transferring the pole piece into a glove box in a protective atmosphere, and adopting a LiPF with a metal lithium piece as a counter electrode and 1mol/L electrolyte6And (EC: DMC 1:1) and Celgard2400 diaphragm, and sequentially assembling the components into a 2032 type button cell. After standing for 24h, transferring the mixture to a Xinwei test system to perform constant-current charge-discharge test at a certain current density, wherein the charge-discharge cut-off voltage interval is 0.01V-1.5V, and the obtained cycle performance curve is shown in figure 2.
Example 4
S1, dissolving 2ml of butyl titanate (TBT) and 0.5g of Aniline (ANI) in a mixed solvent of absolute ethyl alcohol and deionized water, wherein the volume ratio of the absolute ethyl alcohol to the deionized water is 1:1, and fully stirring for 15min by adopting a magnetic stirrer;
s2, under the condition of continuous stirring, adding 1g of nano silicon material with the particle size of 100-500 nm into the solution A obtained in the step S1, performing ultrasonic dispersion for 30min, adding 6ml of acetic acid, stirring at room temperature for 3h, and fully reacting to obtain a solution B;
s3, transferring the solution B obtained in the step S2 to a stainless steel reaction kettle, placing the stainless steel reaction kettle in a thermostat, heating to 165 ℃ at a heating rate of 5 ℃/min, preserving heat for 12 hours, cooling to room temperature along with the furnace, washing, and drying to obtain a precursor C;
s4, weighing the precursor C prepared in the step S3, placing the precursor C in a tube furnace, heating to 750 ℃ at a heating rate of 5 ℃ under a protective atmosphere, preserving heat for 3 hours, and then cooling to room temperature along with the furnace to obtain the silicon-based anode material with the bicontinuous phase structure, which is marked as Si @ TiO2The shell layer thickness of the/C cathode material is 100-200nm, and TiO in the shell layer2The weight ratio of C to C is 4.5: 3.5.
the test method comprises the following steps: mixing the prepared silicon-based negative electrode material with a conductive agent sp and a binder CMC + SBR (1:1) in a mass ratio of 70:15:15 to prepare slurry, fully grinding and mixing the slurry, and uniformly coating the slurry on a metal copper foilDrying at constant temperature of 60 ℃ for 6h, punching into a pole piece with the diameter of 12mm by using a punch, transferring into a glove box under protective atmosphere, and adopting a LiPF (lithium ion power) with a metal lithium piece as a counter electrode and 1mol/L electrolyte6And (EC: DMC 1:1) and Celgard2400 diaphragm, and sequentially assembling the components into a 2032 type button cell. After standing for 24h, transferring the mixture to a Xinwei test system to perform constant-current charge-discharge test at a certain current density, wherein the charge-discharge cut-off voltage interval is 0.01V-1.5V, and the obtained cycle performance curve is shown in figure 2.
Example 5
S1, dissolving 2ml of tetraethyl titanate and 0.5g of polyvinylpyrrolidone (PVP) in a mixed solvent of absolute ethyl alcohol and deionized water, wherein the volume ratio of the absolute ethyl alcohol to the deionized water is 1:1, and fully stirring for 15min by using a magnetic stirrer;
s2, under the condition of continuous stirring, adding 1g of nano silicon material with the particle size of 100-500 nm into the solution A obtained in the step S1, performing ultrasonic dispersion for 30min, adding 6ml of acetic acid, stirring at room temperature for 3h, and fully reacting to obtain a solution B;
s3, transferring the solution B obtained in the step S2 to a stainless steel reaction kettle, placing the stainless steel reaction kettle in a thermostat, heating to 165 ℃ at a heating rate of 5 ℃/min, preserving heat for 12 hours, cooling to room temperature along with the furnace, washing, and drying to obtain a precursor C;
s4, weighing the precursor C prepared in the step S3, placing the precursor C in a tube furnace, heating to 750 ℃ at a heating rate of 5 ℃ under a protective atmosphere, preserving heat for 3 hours, and then cooling to room temperature along with the furnace to obtain the silicon-based anode material with the bicontinuous phase structure, which is marked as Si @ TiO2The shell layer thickness of the/C cathode material is 100-200nm, and TiO in the shell layer2The weight ratio of/C is 7: 3.
The test method comprises the following steps: mixing the prepared silicon-based negative electrode material with a conductive agent sp and a binding agent CMC + SBR (1:1) in a mass ratio of 70:15:15 to prepare slurry, fully grinding and mixing the slurry, uniformly coating the slurry on a metal copper foil, drying the metal copper foil at a constant temperature of 60 ℃ for 6 hours, punching the metal copper foil into a pole piece with the diameter of 12mm by using a punch, transferring the pole piece into a glove box in a protective atmosphere, and adopting a LiPF with a metal lithium piece as a counter electrode and 1mol/L electrolyte6(EC: DMC 1:1) Celgard2400 septumAnd the membranes are sequentially assembled into a 2032 type button cell. After standing for 24h, transferring the mixture to a Xinwei test system to perform constant-current charge-discharge test at a certain current density, wherein the charge-discharge cut-off voltage interval is 0.01V-1.5V, and the obtained cycle performance curve is shown in figure 2.
Example 6
S1, dissolving 2ml of Titanium Tetraisopropoxide (TTIP) and 0.5g of Aniline (ANI) in a mixed solvent of absolute ethyl alcohol and deionized water, wherein the volume ratio of the absolute ethyl alcohol to the deionized water is 1:1, and fully stirring for 15min by using a magnetic stirrer;
s2, under the condition of continuous stirring, adding 1g of nano silicon material with the particle size of 100-500 nm into the solution A obtained in the step S1, performing ultrasonic dispersion for 30min, adding 6ml of acetic acid, stirring at room temperature for 3h, and fully reacting to obtain a solution B;
s3, transferring the solution B obtained in the step S2 to a stainless steel reaction kettle, placing the stainless steel reaction kettle in a thermostat, heating to 165 ℃ at a heating rate of 5 ℃/min, preserving heat for 12 hours, cooling to room temperature along with the furnace, washing, and drying to obtain a precursor C;
s4, weighing the precursor C prepared in the step S3, placing the precursor C in a tube furnace, heating to 750 ℃ at a heating rate of 5 ℃ under a protective atmosphere, preserving heat for 3 hours, and then cooling to room temperature along with the furnace to obtain the silicon-based anode material with the bicontinuous phase structure, which is marked as Si @ TiO2The shell layer thickness of the/C cathode material is 100-200nm, and TiO in the shell layer2The weight ratio of C to C is 7: 4.
The test method comprises the following steps: mixing the prepared silicon-based negative electrode material with a conductive agent sp and a binding agent CMC + SBR (1:1) in a mass ratio of 70:15:15 to prepare slurry, fully grinding and mixing the slurry, uniformly coating the slurry on a metal copper foil, drying the metal copper foil at a constant temperature of 60 ℃ for 6 hours, punching the metal copper foil into a pole piece with the diameter of 12mm by using a punch, transferring the pole piece into a glove box in a protective atmosphere, and adopting a LiPF with a metal lithium piece as a counter electrode and 1mol/L electrolyte6And (EC: DMC 1:1) and Celgard2400 diaphragm, and sequentially assembling the components into a 2032 type button cell. After standing for 24h, transferring the mixture to a Xinwei test system to perform constant-current charge-discharge test at a certain current density, wherein the charge-discharge cut-off voltage interval is 0.01V-1.5V, and the obtained cycle performance curve is shown inFig. 2.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The silicon negative electrode material is characterized in that the silicon negative electrode material is of a core-shell structure, wherein the core layer is a nano silicon sphere, and the shell layer is TiO with a bicontinuous phase structure2a/C composite layer.
2. The silicon negative electrode material as claimed in claim 1, wherein the TiO is selected from the group consisting of2TiO in/C composite layer2The weight ratio of C to C is (4-5) to (3-4).
3. The silicon negative electrode material as claimed in claim 1 or 2, wherein the shell layer has a thickness of 50 to 200 nm.
4. The silicon anode material as claimed in claim 1 or 2, wherein the nano silicon spheres have a particle size of 100 to 500 nm.
5. A method for preparing a silicon anode material according to any one of claims 1 to 4, characterized in that the method comprises the steps of:
s1, mixing an organic titanium source, an organic carbon source and an organic solvent to form a first mixed solution;
s2, adding and dispersing the nano silicon spheres into the first mixed solution, and then adding a hydrolysis stabilizer to form a second mixed solution;
s3, carrying out hydrothermal reaction on the second mixed solution, and cooling to obtain a precursor;
and S4, calcining the precursor under an inert atmosphere to obtain the silicon negative electrode material.
6. The preparation method according to claim 5, wherein the organic titanium source is one or more of titanium tetraisopropoxide, butyl titanate and tetraethoxytitanate; preferably, the organic carbon source is one or more of polyvinylpyrrolidone, aniline, polyacrylate and polyvinyl alcohol.
7. The preparation method according to claim 5 or 6, wherein in the step S1, the weight ratio of the organic titanium source to the organic carbon source is (3-5): 1, the organic solvent is a mixed solvent of anhydrous ethanol and deionized water, and preferably the volume ratio of the anhydrous ethanol to the deionized water is (1-2): 1;
preferably, the mass concentration of the organic titanium source and the organic carbon source in the first mixed solution is 20-35%.
8. The method according to claim 7, wherein in step S2, the weight ratio of the nano silicon spheres to the organic carbon source is (1.5-2.5): 1; preferably, the volume ratio of the hydrolysis stabilizer to the organic titanium source is (2.5-3.5): 1.
9. The method according to any one of claims 5 to 8, wherein in step S3, the hydrothermal reaction is performed by raising the temperature of the second mixed solution to 150 to 180 ℃ at a rate of 5 to 10 ℃/min, and maintaining the temperature for 10 to 15 hours; after the reaction is finished, cooling to room temperature, filtering, washing and drying to obtain the precursor;
preferably, in the step S4, the precursor is heated to 700-800 ℃ at a speed of 5-10 ℃/min, and is subjected to heat preservation for 3-5 hours to perform the calcination process.
10. A lithium ion battery comprising a negative electrode material, characterized in that the negative electrode material is the silicon negative electrode material of any one of claims 1 to 4.
CN202011257852.0A 2020-11-11 2020-11-11 Silicon negative electrode material, preparation method thereof and lithium ion battery comprising silicon negative electrode material Pending CN112490423A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114132914A (en) * 2021-11-25 2022-03-04 广东凯金新能源科技股份有限公司 Titanium dioxide-carbon double-layer coated silicon-based composite material, and preparation method and application thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114132914A (en) * 2021-11-25 2022-03-04 广东凯金新能源科技股份有限公司 Titanium dioxide-carbon double-layer coated silicon-based composite material, and preparation method and application thereof

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