CN112382740A - Graphene-like carbon coated silicon/carbon/graphene composite material, preparation method thereof and negative electrode material - Google Patents

Graphene-like carbon coated silicon/carbon/graphene composite material, preparation method thereof and negative electrode material Download PDF

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CN112382740A
CN112382740A CN202011066232.9A CN202011066232A CN112382740A CN 112382740 A CN112382740 A CN 112382740A CN 202011066232 A CN202011066232 A CN 202011066232A CN 112382740 A CN112382740 A CN 112382740A
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graphene
silicon
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朱守超
马源
詹世英
李海军
蔡惠群
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Yinlong New Energy Co Ltd
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Abstract

The invention provides a graphene-like carbon-coated silicon/carbon/graphene composite material, a preparation method thereof and a negative electrode material. The graphene-carbon-coated silicon/carbon/graphene composite material comprises the following components in percentage by mass: 1-10% of a graphene-like carbon coating layer, 1-15% of silicon, 80-95% of carbon and 0.1-5% of graphene. The silicon/carbon/graphene composite material coated with the graphene-like carbon is used as an electrode of a battery, so that the cost can be greatly reduced, and large-scale mass production is realized. The utility model provides a graphite alkene carbon-like coated silicon/carbon/graphite alkene combined material's nanometer silicon is wrapped up by the two carbon-layer of graphite alkene and graphite alkene-like, can effectively alleviate the volume effect of nanometer silicon to avoid the direct contact of nanometer silicon and electrolyte, and then improve Si/C combined material's circulation stability. And the silicon/carbon/graphene composite material coated by the graphene carbon has the advantages of good conductivity, high specific capacity, wide raw material source, economy and environmental protection.

Description

Graphene-like carbon coated silicon/carbon/graphene composite material, preparation method thereof and negative electrode material
Technical Field
The invention relates to the technical field of battery materials, in particular to a graphene-like carbon-coated silicon/carbon/graphene composite material, a preparation method thereof and a negative electrode material.
Background
With the rapid development of portable electronic devices and electric vehicles, the increasing demand for high-energy electronic devices, and the development of high-energy density batteries is imminent. However, the commercial graphite negative electrode has a low theoretical capacity (372mAh/g), which cannot meet the increasing demand for high-energy electronic devices. Silicon negative electrode materials are due to their highest theoretical specific capacity (about 4200mAh/g) and lower (with Li/Li)+Compared with) discharge potential: (<0.5V) has attracted great attention. However, silicon has low conductivity, and silicon generates a great volume expansion effect during lithium ion intercalation/deintercalation, thereby causing pulverization of electrode materials and separation of active materials, resulting in poor cycle performance thereof, while volume expansion easily causes breakage of a solid electrolyte membrane (SEI film). Many researchers have struggled to build various Si/C composite materials including graphitic or graphitized carbon, amorphous carbon, graphene or N-doped graphene, carbon nanotubes, carbon fibers, porous carbon. The C in the Si/C composite can not only relieve the volume effect, but also improve the electronic conductivity of the Si/C composite material and can be electrically connectedA stable solid electrolyte membrane (SEI) is formed on the polar surface. However, the cycling stability of the prior art Si/C composite is still poor.
Disclosure of Invention
The invention mainly aims to provide a graphene-like carbon-coated silicon/carbon/graphene composite material, a preparation method thereof and a negative electrode material, so as to solve the problem of poor cycle stability of a Si/C composite material in the prior art.
In order to achieve the above object, according to one aspect of the present invention, there is provided a graphene-like carbon-coated silicon/carbon/graphene composite material, including, in mass percent: 1-10% of a graphene-like carbon coating layer, 1-15% of silicon, 80-95% of carbon and 0.1-5% of graphene.
Further, the thickness of the graphene-like carbon coating layer of the graphene-like carbon coated silicon/carbon/graphene composite material is 5nm, the particle size of the graphene-like carbon coated silicon/carbon/graphene composite material is preferably 23-30 μm, and the graphene-like carbon coated silicon/carbon/graphene composite material preferably comprises, by mass: 1-7% of a graphene-like carbon coating layer, 5-15% of silicon, 83-90% of carbon and 0.1-3% of graphene.
In order to achieve the above object, according to another aspect of the present invention, there is provided a method for preparing the above graphene-like carbon-coated silicon/carbon/graphene composite material, the method comprising: step S1, mixing the nano-silicon solution, the phenolic resin solution, the graphene slurry and graphite to obtain a mixture; step S2, drying the mixture to obtain dried composite material powder; step S3, mixing the dried composite material powder, a carbon source and a foaming agent in an inert atmosphere, and then heating to obtain a carbon-coated composite material; and step S4, calcining the carbon-coated composite material to obtain the silicon/carbon/graphene composite material coated by the graphene-like carbon.
In step S3, the mass ratio of the composite powder after drying, the carbon source and the foaming agent is 90-95: 5-10, the carbon source is preferably selected from one or more of glucose, sucrose and maltose, and the foaming agent is preferably selected from one or more of ammonium chloride, ammonium sulfate and ammonium carbonate.
Further, in the step S3, the temperature of the heating treatment is 200 to 400 ℃, preferably 250 to 400 ℃, and the time of the heating treatment is 1 to 5 hours, preferably 1 to 3 hours.
Further, in the step S4, the calcination temperature is 500 to 1500 ℃, preferably 1200 to 1500 ℃, and the calcination time is 1 to 10 hours, preferably 5 to 10 hours.
Further, in the step S1, the dried composite material powder includes, by mass, 5 to 15% of nano-silicon, 1 to 4% of phenolic resin, 0.1 to 2% of graphene, and 80 to 90% of graphite, and preferably the dried composite material powder includes 8 to 12% of nano-silicon, 2 to 3% of phenolic resin, 0.2 to 1% of graphene, and 84 to 89% of graphite.
Further, in the step S2, the drying is spray drying, and the temperature of the spray drying is preferably 100 to 200 ℃.
Further, before the step S1, the preparation method further includes: carrying out ball milling on a silicon source with the particle size of 100-200 mu m in an organic solvent to obtain a nano silicon solution; preferably, the silicon source is silicon powder, the organic solvent is selected from one or more of ethanol, ethylene glycol and isopropanol, the mass ratio of the grinding ball to the silicon source is preferably 1.4-2.2: 1, the mass ratio is further preferably 1.6-2.2: 1, the grinding ball is preferably a zirconium oxide grinding ball, the particle size of the zirconium oxide grinding ball is preferably 0.1-1 mm, the ball milling speed is preferably 2000rpm/min, and the ball milling time is 1-6 h.
According to another aspect of the present invention, there is provided an anode material comprising the aforementioned graphene-like carbon-coated silicon/carbon/graphene composite.
By applying the technical scheme of the invention, the graphene is considered to be an ideal composite matrix of the lithium ion battery cathode material due to the excellent performance: the large surface area of the composite material can increase the storage density of lithium ions, the good mechanical flexibility can effectively relieve the structural change in the electrochemical reaction process, the excellent conductivity can ensure the minimum ohmic loss during the discharging and charging reaction of the cathode, but the graphene is expensive, so that the composite material is formed by adopting graphene-like carbon coated silicon/carbon/graphene, the cost of the graphene-like carbon is far lower than that of the graphene, and the cost of the composite material can be reduced by using the graphene-like carbon to replace part of the graphene as the coating material. The utility model provides a graphite alkene carbon-like coated silicon/carbon/graphite alkene combined material's nanometer silicon is wrapped up by the two carbon-layer of graphite alkene and graphite alkene-like, can effectively alleviate the volume effect of nanometer silicon to avoid the direct contact of nanometer silicon and electrolyte, and then improve Si/C combined material's circulation stability. And the silicon/carbon/graphene composite material coated by the graphene carbon has the advantages of good conductivity, high specific capacity, wide raw material source, economy and environmental protection.
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 scanning electron microscope image of a kind of graphene-carbon-coated silicon/carbon/graphene composite material provided in embodiment 1 of the present invention; and
fig. 2 shows a cycle performance graph of a graphene-like carbon-coated silicon/carbon/graphene composite material provided in example 1 of the present invention.
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 analyzed by the background art, the problem of poor cycle stability of Si/C composite materials exists in the prior art, and to solve the problem, the present invention provides a graphene-like carbon-coated silicon/carbon/graphene composite material, a preparation method thereof, and a negative electrode material.
In an exemplary embodiment of the present application, there is provided a graphene-like carbon-coated silicon/carbon/graphene composite material, including, in mass percent: 1-10% of a graphene-like carbon coating layer, 1-15% of silicon, 80-95% of carbon and 0.1-5% of graphene.
Graphene is considered to be an ideal composite matrix for a lithium ion battery negative electrode material due to its excellent properties: the large surface area of the composite material can increase the storage density of lithium ions, the good mechanical flexibility can effectively relieve the structural change in the electrochemical reaction process, the excellent conductivity can ensure the minimum ohmic loss during the discharging and charging reaction of the cathode, but the graphene is expensive, so that the composite material is formed by adopting graphene-like carbon coated silicon/carbon/graphene, the cost of the graphene-like carbon is far lower than that of the graphene, and the cost of the composite material can be reduced by using the graphene-like carbon to replace part of the graphene as the coating material. The utility model provides a graphite alkene carbon-like coated silicon/carbon/graphite alkene combined material's nanometer silicon is wrapped up by the two carbon-layer of graphite alkene and graphite alkene-like, can effectively alleviate the volume effect of nanometer silicon to avoid the direct contact of nanometer silicon and electrolyte, and then improve Si/C combined material's circulation stability. And the silicon/carbon/graphene composite material coated by the graphene carbon has the advantages of good conductivity, high specific capacity, wide raw material source, economy and environmental protection.
In an embodiment of the present application, the thickness of the graphene-like carbon coating layer of the graphene-like carbon coated silicon/carbon/graphene composite material is 5nm, preferably, the particle size of the graphene-like carbon coated silicon/carbon/graphene composite material is 23 to 30 μm, and preferably, the graphene-like carbon coated silicon/carbon/graphene composite material includes, by mass: 1-7% of a graphene-like carbon coating layer, 5-15% of silicon, 83-90% of carbon and 0.1-3% of graphene.
The graphene-like carbon-coated silicon/carbon/graphene composite material having the thickness, the particle size, and the respective composition contents within the above ranges has more excellent cycle stability and electrical conductivity.
In another exemplary embodiment of the present application, there is provided a method for preparing the aforementioned graphene-like carbon-coated silicon/carbon/graphene composite, the method comprising: step S1, mixing the nano-silicon solution, the phenolic resin solution, the graphene slurry and graphite to obtain a mixture; step S2, drying the mixture to obtain dried composite material powder; step S3, mixing the dried composite material powder, a carbon source and a foaming agent in an inert atmosphere, and then heating to obtain a carbon-coated composite material; and step S4, calcining the carbon-coated composite material to obtain the silicon/carbon/graphene composite material coated by the graphene-like carbon.
During the heating process of the carbon source, the carbon source is firstly melted into liquid slurry, and the liquid slurry can be gradually polymerized to obtain a macromolecular polymer which is coated on the surface of the composite material powder. And the chemical gas released by the foaming agent can blow out the macromolecular polymer, the macromolecular polymer is continuously heated, the surface tension of the polymer liquid is released and becomes thinner gradually along with the release of the gas, a polymer thin layer which is tightly attached to the surface of the composite material powder is obtained, and the polymer thin layer is converted into a graphene-like carbon coating layer through high-temperature calcination and coated on the surface of silicon/carbon/graphene. And because the graphene-like carbon coating acts on the surface of the silicon/carbon/graphene in the formation process of the graphene-like carbon, the formed graphene-like carbon coating is combined with the silicon/carbon/graphene more tightly, so that the direct contact between the nano silicon and the electrolyte is further avoided, and the circulation stability of the Si/C composite material is further improved. The preparation method is simple, wide in raw material source, economical and environment-friendly.
In order to allow the carbon source and the foaming agent to act more sufficiently to form the graphene-like coating layer and to coat the silicon material as much as possible, thereby effectively alleviating the volume effect of the nano-silicon, it is preferable that in step S3, the mass ratio of the dried composite powder, the carbon source and the foaming agent is 90-95: 5-10, the carbon source is preferably selected from one or more of glucose, sucrose and maltose, and the foaming agent is preferably selected from one or more of ammonium chloride, ammonium sulfate and ammonium carbonate.
The carbon source has wide sources, is clean and environment-friendly, and can avoid the pollution of harmful gas generated by coating the carbon source of the asphalt.
In an embodiment of the present invention, in the step S3, the temperature of the heating treatment is 200 to 400 ℃, preferably 250 to 400 ℃, and the time of the heating treatment is 1 to 5 hours, preferably 1 to 3 hours.
Controlling the temperature and time of the heat treatment within the above ranges contributes to better action of the carbon source and the foaming agent and thus to formation of the carbon coating layer of the carbon-coated composite material.
In order to promote the carbon coating layer of the carbon-coated composite material to be converted into the graphene-like coating layer, in the step S4, the calcining temperature is preferably 500-1500 ℃, preferably 1200-1500 ℃, and the calcining time is preferably 1-10 hours, preferably 5-10 hours.
In an embodiment of the application, in the step S1, the composite material powder after drying includes, by mass, 5 to 15% of nano silicon, 1 to 4% of phenolic resin, 0.1 to 2% of graphene, and 80 to 90% of graphite, and preferably the composite material powder after drying includes 8 to 12% of nano silicon, 2 to 3% of phenolic resin, 0.2 to 1% of graphene, and 84 to 89% of graphite.
The method combines the characteristics of the graphene and the graphite and the advantages and disadvantages of the nano-silicon, controls the usage amount of the graphene, the graphite and the nano-silicon within the range, and is beneficial to improving the conductivity and specific capacity of the obtained graphene-like carbon coated silicon/carbon/graphene composite material.
In an embodiment of the present invention, in the step S2, the drying is spray drying, and preferably the temperature of the spray drying is 100 to 200 ℃.
By adopting a spray granulation technology, the synthesized dried composite material powder has good spherical morphology, better overall consistency and high drying efficiency, thereby being beneficial to improving the stability of the finally prepared graphene-like carbon-coated silicon/carbon/graphene composite material. The spray drying conditions are adopted to further improve the drying effect.
In order to obtain nano-silicon with a particle size more consistent with that required for preparing the graphene-like carbon-coated silicon/carbon/graphene composite material, it is preferable that before the step S1, the preparation method further includes: carrying out ball milling on a silicon source with the particle size of 100-200 mu m in an organic solvent to obtain a nano silicon solution; preferably, the silicon source is silicon powder, the organic solvent is selected from one or more of ethanol, ethylene glycol and isopropanol, the mass ratio of the grinding ball to the silicon source is preferably 1.4-2.2: 1, the mass ratio is further preferably 1.6-2.2: 1, the grinding ball is preferably a zirconium oxide grinding ball, the particle size of the zirconium oxide grinding ball is preferably 0.1-1 mm, the ball milling speed is preferably 2000rpm/min, and the ball milling time is 1-6 h.
In another exemplary embodiment of the present application, there is provided an anode material comprising any one of the aforementioned graphene-like carbon-coated silicon/carbon/graphene composite materials.
Although graphene is considered an ideal composite matrix for a negative electrode material of a lithium ion battery due to its excellent properties: the large surface area of the composite material can increase the storage density of lithium ions, the good mechanical flexibility can effectively relieve the structural change in the electrochemical reaction process, the excellent conductivity can ensure the minimum ohmic loss during the discharging and charging reaction of the cathode, but the graphene is expensive, so that the composite material is formed by adopting graphene-like carbon coated silicon/carbon/graphene, the cost of the graphene-like carbon is far lower than that of the graphene, and the cost of the composite material can be reduced by using the graphene-like carbon to replace part of the graphene as the coating material. The utility model provides a graphite alkene carbon-like coated silicon/carbon/graphite alkene combined material's nanometer silicon is wrapped up by the two carbon-layer of graphite alkene and graphite alkene-like, can effectively alleviate the volume effect of nanometer silicon to avoid the direct contact of nanometer silicon and electrolyte, and then improve Si/C combined material's circulation stability. And the silicon/carbon/graphene composite material coated by the graphene carbon has the advantages of good conductivity, high specific capacity, wide raw material source, economy and environmental protection.
The advantageous effects of the present application will be described below with reference to specific examples and comparative examples.
Example 1
Weighing 400g of silicon powder with the particle size of 100 mu m, ball-milling the silicon powder by adopting zirconia grinding balls with the particle size of 0.1mm, wherein the mass ratio of the ball to the material is 1.6:1, the solvent is ethanol, uniformly mixing, adding the mixed solution into a nano sand mill, and ball-milling for 5 hours at the ball-milling speed of 2000rpm/min to obtain the nano silicon solution with the mass concentration of 0.13 g/mL.
3000mL of nano silicon solution, 500mL of phenolic resin ethanol solution with the mass concentration of 0.2g/mL, 500mL of graphene slurry with the mass concentration of 0.03g/mL and 4485g of graphite are mixed and stirred to be uniform, and then the mixture is ground and dispersed for 2 hours at the speed of 2000rpm/min by a high-speed grinding dispersion machine to obtain a mixture. And (3) carrying out spray drying on the mixture at 160 ℃ for 0.5h to obtain dried composite material powder, wherein the dried composite material powder comprises 8% of nano silicon, 2% of phenolic resin, 0.1% of graphene and 89.9% of graphite.
Adding 4000g of dried composite material powder into a high-temperature coating furnace, weighing glucose and ammonium chloride, wherein the mass ratio of the dried composite material powder to the glucose to the ammonium chloride is 93:7:7, heating to 400 ℃ under the argon atmosphere, heating at the speed of 5 ℃/min, and preserving heat for 3 hours to obtain the carbon-coated composite material.
Transferring the carbon-coated composite material to a rotary kiln, heating to 1200 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, carbonizing for 5h, and naturally cooling to room temperature in argon gas to obtain the graphene-like carbon-coated silicon/carbon/graphene composite material, wherein the particle size (D50) is 25 mu m, the graphene-like carbon-coated silicon/carbon/graphene composite material comprises 3% of a graphene-like carbon coating layer, 8% of silicon, 88.7% of carbon and 0.3% of graphene, and the thickness of the graphene-like carbon coating layer is 5 nm. The scanning electron microscope image of the graphene-carbon-coated silicon/carbon/graphene composite material is shown in fig. 1, and the cycle performance image of the graphene-carbon-coated silicon/carbon/graphene composite material is shown in fig. 2.
Example 2
Example 2 differs from example 1 in that the mass ratio of the composite powder after drying, glucose and ammonium chloride was 95:5:5, yielding a graphene-like carbon coated silicon/carbon/graphene composite material with a particle size (D50) of 23 μm comprising 1% graphene-like carbon coating, 10% silicon, 88.7% carbon and 0.3% graphene.
Example 3
Example 3 differs from example 1 in that the mass ratio of the composite powder after drying, glucose and ammonium chloride was 90:10:10, yielding a graphene-like carbon coated silicon/carbon/graphene composite material having a particle size (D50) of 28 μm and comprising 7% of the graphene-like carbon coating layer, 5% of silicon, 87.9% of carbon and 0.1% of graphene.
Example 4
Example 4 differs from example 1 in that the mass ratio of the composite powder after drying, glucose and ammonium chloride was 80:20:20, yielding a graphene-like carbon coated silicon/carbon/graphene composite material having a particle size (D50) of 30 μm and comprising 8% of the graphene-like carbon coating layer, 3% of silicon, 88.9% of carbon and 0.1% of graphene.
Example 5
Example 5 differs from example 1 in that heating to 250 ℃ under an argon atmosphere resulted in a graphene-like carbon coated silicon/carbon/graphene composite material having a particle size (D50) of 25 μm comprising 3% graphene-like carbon coating, 8% silicon, 88.7% carbon and 0.3% graphene.
Example 6
Example 6 is different from example 1 in that it was heated to 200 ℃ under an argon atmosphere for 1 hour to obtain a graphene-like carbon-coated silicon/carbon/graphene composite material having a particle size (D50) of 25 μm comprising 3% of a graphene-like carbon coating layer, 8% of silicon, 88.7% of carbon, and 0.3% of graphene.
Example 7
Example 7 differs from example 1 in that heating to 150 ℃ under an argon atmosphere resulted in a graphene-like carbon coated silicon/carbon/graphene composite material having a particle size (D50) of 25 μm comprising 3% graphene-like carbon coating, 8% silicon, 88.7% carbon and 0.3% graphene.
Example 8
Example 8 differs from example 1 in that the carbon-coated composite material was transferred to a rotary kiln furnace and carbonized at 1500 ℃ for 8h under the protection of argon gas to obtain a graphene-like carbon-coated silicon/carbon/graphene composite material having a particle size (D50) of 25 μm comprising 3% graphene-like carbon coating, 8% silicon, 88.7% carbon and 0.3% graphene.
Example 9
Example 9 differs from example 1 in that the carbon-coated composite material was transferred to a rotary kiln furnace and carbonized at 1300 ℃ for 10h under the protection of argon gas to obtain a graphene-like carbon-coated silicon/carbon/graphene composite material having a particle size (D50) of 25 μm comprising 3% graphene-like carbon coating layer, 8% silicon, 88.7% carbon and 0.3% graphene.
Example 10
Example 10 differs from example 1 in that the carbon-coated composite material was transferred to a rotary kiln furnace and carbonized at 500 ℃ for 1h under the protection of argon gas to obtain a graphene-like carbon-coated silicon/carbon/graphene composite material having a particle size (D50) of 25 μm comprising 3% graphene-like carbon coating layer, 8% silicon, 88.7% carbon and 0.3% graphene.
Example 11
Example 11 differs from example 1 in that the carbon-coated composite material was transferred to a rotary kiln furnace and carbonized at 400 ℃ for 1h under the protection of argon gas to obtain a graphene-like carbon-coated silicon/carbon/graphene composite material having a particle size (D50) of 25 μm comprising 3% graphene-like carbon coating layer, 8% silicon, 88.7% carbon and 0.3% graphene.
Example 12
Example 12 differs from example 1 in that 400g of silicon powder with a particle size of 150 μm is weighed and ball-milled with zirconia milling balls with a particle size of 0.6mm, wherein the mass ratio of the ball to the material is 1.4:1, the solvent is ethanol, after uniform mixing, the mixed solution is added into a nano-mill and ball-milled for 10h at a ball-milling speed of 1500rpm/min, and nano-silicon solution with a mass concentration of 0.13g/mL is obtained.
3000mL of nano silicon solution, 500mL of phenolic resin ethanol solution with the mass concentration of 0.2g/mL, 500mL of graphene slurry with the mass concentration of 0.03g/mL and 4485g of graphite are mixed and stirred uniformly, and then the mixture is ground and dispersed for 2 hours by a high-speed grinding dispersion machine to obtain a mixture. And (3) carrying out spray drying on the mixture at 180 ℃ for 0.2h to obtain dried composite material powder, wherein the dried composite material powder comprises 8% of nano silicon, 2% of phenolic resin, 0.1% of graphene and 89.9% of graphite.
The graphene-like carbon-coated silicon/carbon/graphene composite material was obtained, which had a particle size (D50) of 32 μm and contained 3% of the graphene-like carbon coating layer, 8% of silicon, 88.7% of carbon, and 0.3% of graphene.
Example 13
Example 13 differs from example 1 in that 400g of silicon powder with a particle size of 200 μm is weighed and ball milled with zirconia milling balls with a particle size of 1mm, wherein the mass ratio of the ball to the material is 2.2:1, the solvent is ethylene glycol, after uniform mixing, the mixed solution is added into a nano-sand mill and ball milled for 2h at a ball milling speed of 2500rpm/min, and nano-silicon solution with a mass concentration of 0.13g/mL is obtained.
3000mL of nano silicon solution, 500mL of phenolic resin ethanol solution with the mass concentration of 0.2g/mL, 500mL of graphene slurry with the mass concentration of 0.03g/mL and 4485g of graphite are mixed and stirred uniformly, and then the mixture is ground and dispersed for 2 hours by a high-speed grinding dispersion machine to obtain a mixture. And (3) carrying out spray drying on the mixture at 150 ℃ for 1h to obtain dried composite material powder, wherein the dried composite material powder comprises 8% of nano silicon, 2% of phenolic resin, 0.1% of graphene and 89.9% of graphite.
The graphene-like carbon-coated silicon/carbon/graphene composite material was obtained, which had a particle size (D50) of 22 μm and contained 3% of the graphene-like carbon coating layer, 8% of silicon, 88.7% of carbon, and 0.3% of graphene.
Example 14
Example 14 differs from example 1 in that 3000mL of a nano-silicon solution was mixed with 1000mL of a phenol resin ethanol solution with a mass concentration of 0.2, 1111mL of graphene slurry with a mass concentration of 0.03, and 2800g of graphite, and stirred until uniform, and then the mixture was ground and dispersed for 2 hours using a high-speed grinding and dispersing machine to obtain a mixture. And (3) carrying out spray drying on the mixture at 160 ℃ for 0.5h to obtain dried composite material powder, wherein the dried composite material powder comprises 12% of nano silicon, 4% of phenolic resin, 0.2% of graphene and 83.8% of graphite, and finally obtaining the graphene-like carbon coated silicon/carbon/graphene composite material which comprises a graphene-like carbon coating layer of 10%, silicon of 9.8%, carbon of 80% and graphene of 0.2%.
Example 15
Example 15 differs from example 1 in that 3000mL of a nano-silicon solution was mixed with 1000mL of a phenol resin ethanol solution with a mass concentration of 0.2, 667mL of graphene slurry with a mass concentration of 0.03, and 3480g of graphite, stirred until uniform, and then the mixture was ground and dispersed for 2 hours using a high-speed grinding and dispersing machine to obtain a mixture. And (3) carrying out spray drying on the mixture at 160 ℃ for 0.5h to obtain dried composite material powder, wherein the dried composite material powder comprises 9% of nano-silicon, 1% of phenolic resin, 1% of graphene and 89% of graphite, and finally obtaining the graphene-like carbon coated silicon/carbon/graphene composite material, which comprises 3% of graphene-like carbon coating layers, 9% of silicon, 83% of carbon and 5% of graphene.
Example 16
Example 16 differs from example 1 in that 1500mL of the nano-silicon solution was mixed with 600mL of a phenol resin ethanol solution with a mass concentration of 0.2, 1333mL of graphene slurry with a mass concentration of 0.03, and 3460g of graphite, stirred until uniform, and then the mixture was ground and dispersed for 2 hours using a high-speed grinding and dispersing machine to obtain a mixture. And (3) carrying out spray drying on the mixture at 160 ℃ for 0.5h to obtain dried composite material powder, wherein the dried composite material powder comprises 5% of nano-silicon, 4% of phenolic resin, 1% of graphene and 90% of graphite, and finally obtaining the graphene-like carbon coated silicon/carbon/graphene composite material, which comprises 3% of graphene-like carbon coating layers, 5% of silicon, 90% of carbon and 2% of graphene.
Example 17
Example 17 differs from example 1 in that 3500mL of the nano-silicon solution, 175mL of the phenol resin ethanol solution having a mass concentration of 0.2, 583mL of the graphene slurry having a mass concentration of 0.03, and 2993g of graphite were mixed, stirred until uniform, and then the mixture was ground and dispersed for 2 hours by a high-speed grinding and dispersing machine to obtain a mixture. And (3) carrying out spray drying on the mixture at 160 ℃ for 0.5h to obtain dried composite material powder, wherein the dried composite material powder comprises 13% of nano silicon, 1% of phenolic resin, 0.5% of graphene and 85.5% of graphite, and finally obtaining the graphene-like carbon coated silicon/carbon/graphene composite material which comprises 3% of graphene-like carbon coating layer, 10% of silicon, 83% of carbon and 4% of graphene.
Example 18
Example 18 differs from example 1 in that 4000mL of the nano-silicon solution was mixed with 693mL of a phenol resin ethanol solution with a mass concentration of 0.2, 1155mL of graphene slurry with a mass concentration of 0.03, and 2773g of graphite, stirred until uniform, and then the mixture was ground and dispersed for 2 hours using a high-speed grinding and dispersing machine to obtain a mixture. And (3) spray-drying the mixture at 160 ℃ for 0.5h to obtain dried composite material powder, wherein the dried composite material powder comprises 15% of nano-silicon, 3% of phenolic resin, 2% of graphene and 80% of graphite, and finally the graphene-like carbon coated silicon/carbon/graphene composite material is obtained, and comprises 2% of graphene-like carbon coating layers, 15% of silicon, 80% of carbon and 3% of graphene.
Example 19
Example 19 differs from example 1 in that 1500mL of a nano-silicon solution, 420mL of a phenol resin ethanol solution with a mass concentration of 0.2, 1655mL of graphene slurry with a mass concentration of 0.03, and 3120g of graphite were mixed and stirred until uniform, and then the mixture was polish-dispersed for 2 hours using a high-speed polishing disperser to obtain a mixture. And (3) spray-drying the mixture at 160 ℃ for 0.5h to obtain dried composite material powder, wherein the dried composite material powder comprises 5% of nano-silicon, 2% of phenolic resin, 3% of graphene and 90% of graphite, and finally the graphene-like carbon coated silicon/carbon/graphene composite material is obtained, and comprises 1% of graphene-like carbon coating layer, 3% of silicon, 95% of carbon and 1% of graphene.
Comparative example 1
Comparative example 1 is different from example 1 in that,
the silicon/carbon/graphene composite material was obtained by the same operation as in example 1, except that the carbon coating was not performed on the dried composite material powder.
Comparative example 2
Comparative example 2 differs from example 1 in that,
the preparation of the graphene-like material is performed first, and then the silicon/carbon/graphene material is coated, and the rest of the operations are the same as those in example 1, specifically as follows:
weighing glucose and ammonium chloride, wherein the mass ratio of the glucose to the ammonium chloride is 1:1, heating to 400 ℃ under the argon atmosphere condition, heating at the temperature rise speed of 5 ℃/min, preserving heat for 3 hours, heating to 1200 ℃ at the temperature rise speed of 5 ℃/min, and carbonizing for 5 hours to obtain the graphene-like material. The graphene-like carbon-coated silicon/carbon/graphene composite material is prepared by mixing the graphene-like material, PVA and a silicon/carbon/graphene material according to a mass ratio of 7:2:91, heating to 500 ℃ under an argon atmosphere, heating at a speed of 5 ℃/min, and preserving heat for 3 hours.
The grapheme-like carbon-coated silicon/carbon/graphene composite materials obtained in the above examples 1 to 19, the silicon/carbon/graphene composite material obtained in the comparative example 1, and the grapheme-like carbon-coated silicon/carbon/graphene composite material obtained in the comparative example 2 were used as working electrodes, lithium sheets were used as counter electrodes, and the electrolyte was a general lithium ion battery electrolyte, so that a 2032 type coin cell was prepared, the discharge capacity after 100 cycles was tested at a current density of 0.1A/g, and the test results were listed in table 1.
TABLE 1
Figure BDA0002713826650000091
Figure BDA0002713826650000101
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:
graphene is considered to be an ideal composite matrix for a lithium ion battery negative electrode material due to its excellent properties: the large surface area of the composite material can increase the storage density of lithium ions, the good mechanical flexibility can effectively relieve the structural change in the electrochemical reaction process, the excellent conductivity can ensure the minimum ohmic loss during the discharging and charging reaction of the cathode, but the graphene is expensive, so that the composite material is formed by adopting graphene-like carbon coated silicon/carbon/graphene, the cost of the graphene-like carbon is far lower than that of the graphene, and the cost of the composite material can be reduced by using the graphene-like carbon to replace part of the graphene as the coating material. The utility model provides a graphite alkene carbon-like coated silicon/carbon/graphite alkene combined material's nanometer silicon is wrapped up by the two carbon-layer of graphite alkene and graphite alkene-like, can effectively alleviate the volume effect of nanometer silicon to avoid the direct contact of nanometer silicon and electrolyte, and then improve Si/C combined material's circulation stability. And the silicon/carbon/graphene composite material coated by the graphene carbon has the advantages of good conductivity, high specific capacity, wide raw material source, economy and environmental protection.
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. A graphene-like carbon-coated silicon/carbon/graphene composite material, wherein the graphene-like carbon-coated silicon/carbon/graphene composite material comprises, by mass: 1-10% of a graphene-like carbon coating layer, 1-15% of silicon, 80-95% of carbon and 0.1-5% of graphene.
2. The graphene-like carbon coated silicon/carbon/graphene composite material according to claim 1, wherein the graphene-like carbon coating layer of the graphene-like carbon coated silicon/carbon/graphene composite material has a thickness of 5nm, preferably the graphene-like carbon coated silicon/carbon/graphene composite material has a particle size of 23-30 μm, preferably the graphene-like carbon coated silicon/carbon/graphene composite material comprises, by mass: 1-7% of a graphene-like carbon coating layer, 5-15% of silicon, 83-90% of carbon and 0.1-3% of graphene.
3. A method of preparing the graphene-like carbon-coated silicon/carbon/graphene composite material according to claim 1 or 2, wherein the method comprises:
step S1, mixing the nano-silicon solution, the phenolic resin solution, the graphene slurry and graphite to obtain a mixture;
step S2, drying the mixture to obtain dried composite material powder;
step S3, mixing the dried composite material powder, a carbon source and a foaming agent in an inert atmosphere, and then heating to obtain a carbon-coated composite material; and
and step S4, calcining the carbon-coated composite material to obtain the graphene-like carbon-coated silicon/carbon/graphene composite material.
4. The method according to claim 3, wherein in step S3, the mass ratio of the dried composite material powder, the carbon source and the foaming agent is 90-95: 5-10, the carbon source is preferably selected from one or more of glucose, sucrose and maltose, and the foaming agent is preferably selected from one or more of ammonium chloride, ammonium sulfate and ammonium carbonate.
5. The method according to claim 3, wherein in step S3, the temperature of the heat treatment is 200 to 400 ℃, preferably 250 to 400 ℃, and the time of the heat treatment is 1 to 5 hours, preferably 1 to 3 hours.
6. The preparation method according to claim 3, wherein in the step S4, the calcination temperature is 500-1500 ℃, preferably 1200-1500 ℃, and the calcination time is 1-10 h, preferably 5-10 h.
7. The preparation method according to claim 3, wherein in the step S1, the dried composite material powder comprises, by mass, 5-15% of nano silicon, 1-4% of phenolic resin, 0.1-2% of graphene, and 80-90% of graphite, and preferably the dried composite material powder comprises 8-12% of nano silicon, 2-3% of phenolic resin, 0.2-1% of graphene, and 84-89% of graphite.
8. The method according to claim 3, wherein the drying in step S2 is spray drying, and preferably the temperature of the spray drying is 100 to 200 ℃.
9. The method according to claim 3, wherein before the step S1, the method further comprises:
carrying out ball milling on a silicon source with the particle size of 100-200 mu m in an organic solvent to obtain a nano silicon solution;
preferably, the silicon source is silicon powder, the organic solvent is selected from one or more of ethanol, ethylene glycol and isopropanol, the mass ratio of the grinding ball to the silicon source is preferably 1.4-2.2: 1, the mass ratio of the grinding ball to the silicon source is further preferably 1.6-2.2: 1, the grinding ball is preferably a zirconia grinding ball, the particle size of the zirconia grinding ball is preferably 0.1-1 mm, the ball milling speed is preferably 2000rpm/min, and the ball milling time is 1-6 h.
10. An anode material, characterized in that the anode material comprises the graphene-like carbon-coated silicon/carbon/graphene composite material according to any one of claims 1 or 2.
CN202011066232.9A 2020-09-30 2020-09-30 Graphene-like carbon coated silicon/carbon/graphene composite material, preparation method thereof and negative electrode material Pending CN112382740A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116002660A (en) * 2022-12-28 2023-04-25 太原科技大学 Preparation method of carbon-silicon composite material, carbon-silicon composite material and lithium battery

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