CN109713280B - Silicon carbon anode material and preparation method, lithium ion battery - Google Patents
Silicon carbon anode material and preparation method, lithium ion battery Download PDFInfo
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- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 title claims abstract description 60
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 18
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 18
- 239000010405 anode material Substances 0.000 title claims description 17
- 238000002360 preparation method Methods 0.000 title abstract description 5
- 239000006185 dispersion Substances 0.000 claims abstract description 61
- 239000007773 negative electrode material Substances 0.000 claims abstract description 58
- 239000002245 particle Substances 0.000 claims abstract description 58
- 239000011164 primary particle Substances 0.000 claims abstract description 52
- 239000000463 material Substances 0.000 claims abstract description 50
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 47
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 47
- 239000011259 mixed solution Substances 0.000 claims abstract description 32
- 239000002270 dispersing agent Substances 0.000 claims abstract description 26
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- 238000003763 carbonization Methods 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 18
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 14
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 9
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 6
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 6
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 6
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 3
- 239000004698 Polyethylene Substances 0.000 claims description 3
- 150000001335 aliphatic alkanes Chemical class 0.000 claims description 3
- 150000002148 esters Chemical class 0.000 claims description 3
- 239000005011 phenolic resin Substances 0.000 claims description 3
- 229920000915 polyvinyl chloride Polymers 0.000 claims description 3
- 239000004800 polyvinyl chloride Substances 0.000 claims description 3
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 2
- 125000003118 aryl group Chemical group 0.000 claims description 2
- 229920001568 phenolic resin Polymers 0.000 claims description 2
- 229920013716 polyethylene resin Polymers 0.000 claims description 2
- ATHHXGZTWNVVOU-UHFFFAOYSA-N N-methylformamide Chemical compound CNC=O ATHHXGZTWNVVOU-UHFFFAOYSA-N 0.000 claims 2
- 102000020897 Formins Human genes 0.000 claims 1
- 108091022623 Formins Proteins 0.000 claims 1
- 239000003795 chemical substances by application Substances 0.000 claims 1
- 238000010298 pulverizing process Methods 0.000 abstract description 2
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 20
- 229910052814 silicon oxide Inorganic materials 0.000 description 18
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 16
- 229910052744 lithium Inorganic materials 0.000 description 16
- 230000002687 intercalation Effects 0.000 description 13
- 238000009830 intercalation Methods 0.000 description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- 229910052710 silicon Inorganic materials 0.000 description 7
- 239000010703 silicon Substances 0.000 description 7
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 6
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- 229910052757 nitrogen Inorganic materials 0.000 description 4
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- -1 aromatics Substances 0.000 description 2
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- 238000004519 manufacturing process Methods 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000010000 carbonizing Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
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- 229920000573 polyethylene Polymers 0.000 description 1
- 239000002153 silicon-carbon composite material Substances 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- 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
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Abstract
本发明提供了一种硅碳负极材料及制备方法、锂离子电池。制备硅碳负极材料的方法包括：将SiOx、碳源与分散剂进行混合，获得第一混合溶液，x＝0.5‑1.0；对第一混合溶液进行第一分散处理，过滤干燥，获得第一分散材料；对第一分散材料进行第一碳化处理，粉碎获得一次粒子，一次粒子的粒径为0.5‑1μm；将一次粒子与碳源和分散剂进行混合，获得第二混合溶液；对第二混合溶液进行第二分散处理，过滤干燥，获得第二分散材料；对第二分散材料进行第二碳化处理，粉碎获得二次粒子，二次粒子的粒径为10‑15μm，获得硅碳负极材料。本发明所述的方法可以使最终获得的硅碳负极材料具有较小的体积膨胀以及良好的循环性能。
The invention provides a silicon carbon negative electrode material, a preparation method and a lithium ion battery. The method for preparing a silicon carbon negative electrode material includes: mixing SiO x , a carbon source and a dispersant to obtain a first mixed solution, where x=0.5-1.0; performing a first dispersion treatment on the first mixed solution, filtering and drying to obtain a first mixed solution dispersing material; performing a first carbonization treatment on the first dispersing material, pulverizing to obtain primary particles, and the particle size of the primary particles is 0.5-1 μm; mixing the primary particles with a carbon source and a dispersant to obtain a second mixed solution; The mixed solution is subjected to a second dispersion treatment, filtered and dried to obtain a second dispersion material; the second dispersion material is subjected to a second carbonization treatment, pulverized to obtain secondary particles, and the particle size of the secondary particles is 10-15 μm to obtain a silicon carbon negative electrode material . The method of the present invention can make the finally obtained silicon carbon negative electrode material have small volume expansion and good cycle performance.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a silicon-carbon negative electrode material, a preparation method and a lithium ion battery.
Background
At present, the lithium ion battery negative electrode material is mainly a graphite material, however, the specific capacity of the graphite material is close to the theoretical limit capacity (372mAh/g), and the theoretical limit capacity of the graphite material is still smaller. Therefore, in order to increase the energy density of lithium ion batteries, it is necessary to further develop a novel negative electrode material. The theoretical specific capacity of the silicon negative electrode material is 10 times that of the graphite material, but the silicon negative electrode material has serious volume expansion after lithium insertion, specifically, the volume expansion reaches 300%, and the cycle performance and the service life of the lithium ion battery are seriously influenced.
At present, a silicon oxide material and a silicon-carbon composite material are generally adopted to solve the problem that the volume expansion of a silicon negative electrode material is serious after lithium is embedded. Wherein SiO in the silicon oxide materialxThe component can buffer the volume expansion of the silicon during lithium intercalation, and the Si crystal particle size in the silicon oxide material is smaller (usually 2-8nm), so that the problems of serious volume expansion, poor cycle performance and the like of the silicon-based negative electrode material can be solved.
However, the inventors found that the silicon-based anode material still needs to be improved in terms of improving the problems of severe volume expansion and poor cycle performance. Specifically, the silicon-based negative electrode material is a one-step formed particle, and if the particle size of the particle is larger, the lithium ion transmission path is lengthened, the lithium intercalation expansion stress is increased, and the negative electrode material is easy to break and lose activity. If the particle size of the particles is small, the compacted density of the negative electrode sheet is low, the particles are difficult to disperse in slurry and easy to aggregate, and the lithium intercalation expansion stress is increased, so that the negative electrode material is easy to break and lose activity. In addition, the one-step molded particles have poor isotropy, which results in large volume expansion of the negative electrode material during lithium intercalation, and thus poor cycle performance.
Disclosure of Invention
In view of the above, the present invention provides a method for preparing a silicon-carbon negative electrode material, which can make the finally obtained silicon-carbon negative electrode material have the advantages of good dynamic performance of small-particle-size particles and small expansion stress, and also have the advantages of large compacted density of large-particle-size particles, easy processing and forming, and easy dispersion, and the silicon-carbon negative electrode material particles have good isotropy, so that the silicon-carbon negative electrode material has small volume expansion during lithium intercalation, and the cycle performance is improved.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a method of making a silicon carbon anode material, the method comprising: mixing SiOxMixing a carbon source and a dispersant to obtain a first mixed solution, wherein x is 0.5-1.0; performing first dispersion treatment on the first mixed solution, and filtering and drying to obtain a second mixed solutionA dispersion material; carrying out first carbonization treatment on the first dispersion material, and crushing to obtain primary particles, wherein the particle size of the primary particles is 0.5-1 mu m; mixing the primary particles with the carbon source and the dispersing agent to obtain a second mixed solution; carrying out second dispersion treatment on the second mixed solution, and filtering and drying to obtain a second dispersion material; and carrying out second carbonization treatment on the second dispersion material, and crushing to obtain secondary particles, wherein the particle size of the secondary particles is 10-15 mu m, so as to obtain the silicon-carbon negative electrode material.
Further, the SiOxThe particle size of the (B) is 80-200 nm; optionally, the carbon source comprises at least one of pitch, polyvinyl chloride, polyethylene, and phenolic resin; optionally, the dispersant comprises at least one of water, ethanol, methanol, acetone, alkanes, esters, aromatics, tetrahydrofuran, dimethyl sulfoxide, N-methylpyrrolidone, and N, N-dimethylformamide.
Further, the SiOxThe mass ratio of the carbon source to the dispersant is 1:20-1:1, and the mass of the dispersant to the SiOxAnd the total mass ratio of the carbon source is 1:1-10: 1.
Further, the rotation speed of the first dispersion treatment is 500-700 r/min, and the time is 1-20 h.
Further, the temperature of the first carbonization treatment is raised from room temperature to 500-800 ℃ at the speed of 2-10 ℃/min, and the temperature is kept for 10-20 h.
Further, the mass ratio of the primary particles to the carbon source is 1:1-1:5, and the mass ratio of the dispersant to the total mass of the primary particles and the carbon source is 20:1-5: 1.
Further, the rotation speed of the second dispersion treatment is 700-900 rpm, and the time is 2-10 h.
Further, the second carbonization treatment is carried out at the temperature of 1-10 ℃/min from the room temperature to 500-1100 ℃, and the temperature is kept for 2-20 h.
Compared with the prior art, the method for preparing the silicon-carbon anode material has the following advantages:
according to the method, the primary particles with the small particle size are formed firstly, and then the primary particles are dispersed and carbonized continuously to obtain the secondary particles with the large particle size, so that the silicon-carbon negative electrode material is obtained, and the silicon-carbon negative electrode material has the advantages of small particle size and small expansion stress, and also has the advantages of large particle size, high compaction density, easiness in processing and forming and easiness in dispersion.
Another object of the present invention is to provide a silicon-carbon negative electrode material, which is prepared by the above-described method, and therefore, the silicon-carbon negative electrode material has all the features and advantages of the silicon-carbon negative electrode material prepared by the above-described method, and will not be described herein again. In general, the silicon-carbon negative electrode material has the advantages of good dynamic performance and small expansion stress of small-particle-size particles, and also has the advantages of large compacted density, easiness in processing and forming and easiness in dispersion of large-particle-size particles, and the silicon-carbon negative electrode material particles are good in isotropy, so that the silicon-carbon negative electrode material is small in volume expansion during lithium intercalation, and the cycle performance is improved.
Another object of the present invention is to provide a lithium ion battery, which includes a negative electrode sheet, wherein the negative electrode sheet includes the aforesaid silicon-carbon negative electrode material, and therefore, the lithium ion battery has all the features and advantages of the aforesaid silicon-carbon negative electrode material, and will not be described herein again. In general, the lithium ion battery has good cycle performance and long service life.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic flow chart of a method for preparing a silicon-carbon negative electrode material according to an embodiment of the invention;
FIG. 2 is an electron micrograph of a silicon carbon negative electrode material obtained in example 1; and
fig. 3 is a cycle performance test curve of the silicon carbon anode material obtained in example 1 and comparative example 1.
Detailed Description
It should be noted that the embodiments and features of the embodiments 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.
In one aspect of the invention, a method of making a silicon carbon anode material is presented. As described above, the conventional silicon-carbon negative electrode material is a primary molded particle, and a lithium ion transmission path is lengthened and lithium intercalation expansion stress is increased due to a large particle size of the particle, so that the negative electrode material is easily broken and loses activity. The particle size of the particles is small, the compaction density of the negative plate is low, the particles are difficult to disperse in slurry and easy to aggregate, and the lithium intercalation expansion stress is increased, so that the negative material is easy to break and lose activity. In addition, the one-step molded particles have poor isotropy, which results in large volume expansion of the negative electrode material during lithium intercalation, and thus poor cycle performance.
According to an embodiment of the invention, with reference to fig. 1, the method comprises:
s100: mixing SiOxMixing a carbon source and a dispersing agent to obtain a first mixed solution
According to an embodiment of the invention, in this step SiO is addedxAnd mixing the carbon source and the dispersing agent to obtain a first mixed solution. According to an embodiment of the invention, SiOxWherein x is 0.5-1.0. Thus, the silicon oxide is compounded with carbon, the volume expansion of the material during lithium intercalation can be reduced by the silicon oxide, and the capacity of the material can be improved by coating the silicon oxide with the carbon.
According to an embodiment of the invention, SiOxThe particle size of (a) may be 80-200 nm. Therefore, the silicon monoxide can effectively reduce the volume expansion of the material when lithium is embedded.
According to an embodiment of the present invention, the carbon source may include at least one of asphalt, polyvinyl chloride, polyethylene, and phenol resin. Therefore, the carbon-coated silicon monoxide obtained by the carbon source cracking can be utilized to improve the capacity of the material.
According to an embodiment of the present invention, the dispersant may include at least one of water, ethanol, methanol, acetone, alkane, ester, aromatic, tetrahydrofuran, dimethyl sulfoxide, N-methylpyrrolidone, and N, N-dimethylformamide. Thus, the silica and the carbon source can be dispersed by the dispersant to obtain the first mixed solution.
According to an embodiment of the invention, SiOxThe mass ratio of the carbon source to the dispersant can be 1:20-1:1, and the mass of the dispersant to SiOxThe ratio of the total mass of the carbon source may be 1:1 to 10: 1. Therefore, enough carbon can be ensured to coat the silicon monoxide after the subsequent first carbonization treatment, and enough dispersing agent can be ensured to disperse the silicon monoxide and the carbon source, so that a uniform first mixed solution can be obtained. Specifically, SiOxThe mass ratio of the carbon source to the dispersant can be 1:10, and the mass of the dispersant to SiOxThe ratio of the total mass of the carbon source may be 1.5: 1.
S200: carrying out first dispersion treatment on the first mixed solution, filtering and drying to obtain a first dispersion material
According to an embodiment of the present invention, in this step, the first mixed solution is subjected to a first dispersion treatment, and is filtered and dried to obtain a first dispersed material. According to the embodiment of the invention, the first dispersion treatment may be performed on the first mixed solution by using a dispersion machine, the rotation speed of the first dispersion treatment may be 500-700 rpm, and the time may be 1-20 h. Thus, a uniformly dispersed solution can be obtained, and a uniformly dispersed first dispersion material can be obtained after filtration and drying. Specifically, the rotation speed of the first dispersion treatment may be 600 rpm, and the time may be 3 hours.
S300: subjecting the first dispersed material to a first carbonization treatment and pulverizing to obtain primary particles
According to an embodiment of the present invention, in this step, the first dispersed material is subjected to the first carbonization treatment and pulverized to obtain primary particles. According to the embodiment of the invention, the first carbonization treatment can be performed on the first dispersion material by placing the first dispersion material into a tube furnace or an atmosphere box furnace, introducing high-purity nitrogen as a protective gas, raising the temperature from room temperature to 800 ℃ at a temperature-raising speed of 2-10 ℃/min, and keeping the temperature for 10-20 h. Thus, the material of carbon-coated silicon oxide can be obtained after carbonization. Specifically, the first carbonization treatment may be performed by raising the temperature from room temperature to 700 ℃ at a rate of 5 ℃/min and holding the temperature for 15 hours.
According to an embodiment of the present invention, after a material of carbon-coated silica is obtained, the above material is pulverized to obtain primary particles, which may have a particle size of 0.5 to 1 μm and a particle size classification of D50. Thus, primary particles having a small particle size, which have the advantages of good dynamic properties and a small expansion stress, can be obtained. Specifically, the primary particles may have a particle size of 0.8. mu.m.
S400: mixing the primary particles with a carbon source and a dispersant to obtain a second mixed solution
According to an embodiment of the present invention, in this step, the primary particles are mixed with a carbon source and a dispersant to obtain a second mixed solution. That is, after the primary particles are obtained, the subsequent steps are based on the primary particles, and the primary particles are continuously dispersed and carbonized to obtain secondary particles with larger particle size, the secondary particles retain the structure of the primary particles, and the secondary particles are carbon-coated on the primary particles, so that the finally obtained silicon-carbon anode material can have the advantages of both the primary particles and the secondary particles.
According to an embodiment of the present invention, the mass ratio of the primary particles to the carbon source may be 1:1 to 1:5, and the ratio of the mass of the dispersant to the total mass of the primary particles and the carbon source may be 20:1 to 5: 1. Therefore, enough carbon can be ensured to coat the primary particles after the subsequent second carbonization treatment, and enough dispersing agent can be ensured to disperse the primary particles and the carbon source, so that a uniform second mixed solution can be obtained. Specifically, the mass ratio of the primary particles to the carbon source may be 1:2, and the mass ratio of the dispersant to the total mass of the primary particles and the carbon source may be 10: 1.
S500: performing second dispersion treatment on the second mixed solution, filtering and drying to obtain a second dispersion material
According to an embodiment of the present invention, in this step, the second mixed solution is subjected to the second dispersion treatment, and is filtered and dried to obtain a second dispersed material. According to the embodiment of the invention, the second dispersion treatment may be performed on the second mixed solution by using a dispersion machine, the rotation speed of the second dispersion treatment may be 700-900 rpm, and the time may be 2-10 h. Thus, a uniformly dispersed solution can be obtained, and a second uniformly dispersed material can be obtained after filtration and drying. Specifically, the rotation speed of the second dispersion treatment may be 800 rpm, and the time may be 5 hours.
S600: performing second carbonization treatment on the second dispersion material, and crushing to obtain secondary particles so as to obtain the silicon-carbon negative electrode material
According to an embodiment of the present invention, in this step, the second dispersion material is subjected to the second carbonization treatment and pulverized to obtain secondary particles, so as to obtain a silicon carbon anode material. According to the embodiment of the invention, the second carbonization treatment can be performed on the second dispersion material by placing the second dispersion material into a tube furnace or an atmosphere box furnace, introducing high-purity nitrogen as a protective gas, raising the temperature from room temperature to 1100 ℃ at a temperature-raising speed of 1-10 ℃/min, and keeping the temperature for 2-20 h. Thus, a material of carbon-coated primary particles can be obtained after carbonization. Specifically, the second carbonization treatment may be performed by raising the temperature from room temperature to 1100 ℃ at a temperature raising rate of 1 ℃/min and holding the temperature for 15 hours.
According to an embodiment of the present invention, after a material of carbon-coated primary particles is obtained, the above material is pulverized to obtain secondary particles, which may have a particle size of 10 to 15 μm and a particle size classification of D50. Thus, secondary particles having a large particle diameter, which have the advantages of a large compacted density, easy processing and molding, and easy dispersion, and which retain the structure of the primary particles and are carbon-coated on the primary particles, can be obtained, and thus, have the advantages of good dynamic performance of the primary particles and small expansion stress. Specifically, the secondary particles may have a particle size of 12 μm.
According to the embodiment of the invention, the secondary particles are obtained, namely, the silicon-carbon negative electrode material is obtained, and the silicon-carbon negative electrode material has good isotropic performance compared with the primary particles due to twice dispersion and carbonization, so that the volume expansion of the negative electrode material during lithium intercalation can be further reduced, and the cycle performance of the negative electrode material can be improved.
In conclusion, the method comprises the steps of firstly forming primary particles with small particle size, and then continuously dispersing and carbonizing the primary particles to obtain secondary particles with large particle size, namely obtaining the silicon-carbon negative electrode material, wherein the secondary particles retain the structure of the primary particles, and the secondary particles are used for coating the primary particles with carbon, so that the silicon-carbon negative electrode material can simultaneously have the advantages of the primary particles and the advantages of the secondary particles, namely the silicon-carbon negative electrode material has the advantages of good dynamic performance and small expansion stress of small-particle-size particles, and also has the advantages of large compacted density, easiness in processing and forming and easiness in dispersion of large-particle-size particles, and the silicon-carbon negative electrode material particles are good in isotropy, so that the silicon-carbon negative electrode material is small in volume expansion during lithium intercalation, and the cycle performance is improved.
In another aspect of the invention, a silicon carbon anode material is provided. According to the embodiment of the invention, the silicon-carbon anode material is prepared by the method described above, so that the silicon-carbon anode material has all the characteristics and advantages of the silicon-carbon anode material prepared by the method described above, and further description is omitted. In general, the silicon-carbon negative electrode material has the advantages of good dynamic performance and small expansion stress of small-particle-size particles, and also has the advantages of large compacted density, easiness in processing and forming and easiness in dispersion of large-particle-size particles, and the silicon-carbon negative electrode material particles are good in isotropy, so that the silicon-carbon negative electrode material is small in volume expansion during lithium intercalation, and the cycle performance is improved.
In another aspect of the present invention, a lithium ion battery is provided. According to an embodiment of the present invention, the lithium ion battery includes a negative electrode sheet, and the negative electrode sheet includes the aforesaid silicon-carbon negative electrode material, so that the lithium ion battery has all the features and advantages of the aforesaid silicon-carbon negative electrode material, and will not be described herein again. In general, the lithium ion battery has good cycle performance and long service life.
The invention will now be illustrated by means of specific examples, which are provided for illustration only and should not be construed as limiting the scope of the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications.
Example 1
(1) A first mixed solution is prepared. Selecting SiO with the particle size of 100nm, mixing the SiO and the asphalt according to the mass ratio of 1:10, and then adding ethanol to obtain a first mixed solution, wherein the mass ratio of the ethanol to the total mass of the SiO and the asphalt is 1.5: 1.
(2) A first dispersion material is prepared. And (3) carrying out first dispersion treatment on the first mixed solution by using a dispersion machine, wherein the rotation speed of the first dispersion treatment is 600 revolutions per minute, and the time is 3 hours, and filtering and drying after dispersion to obtain a first dispersion material.
(3) Primary particles were prepared. And (3) putting the first dispersion material into a tube furnace, introducing high-purity nitrogen as protective gas, heating to 700 ℃ from room temperature at a heating rate of 5 ℃/min, and keeping the temperature for 15h to obtain the carbon-coated SiO material. Subsequently, the above material was pulverized to obtain primary particles having a particle diameter D50 ═ 0.8 μm.
(4) A second mixed solution is prepared. The primary particles and the asphalt were mixed in a mass ratio of 1:2, followed by addition of ethanol to obtain a second mixed solution, the mass ratio of ethanol to the total mass of the primary particles and the asphalt being 10: 1.
(5) A second dispersion material is prepared. And (3) carrying out second dispersion treatment on the second mixed solution by using a dispersion machine, wherein the rotation speed of the second dispersion treatment is 800 r/min, the time is 5h, and filtering and drying after dispersion to obtain a second dispersion material.
(6) Secondary particles are prepared. And (3) putting the second dispersed material into a tube furnace, introducing high-purity nitrogen as protective gas, heating to 1100 ℃ from room temperature at the heating rate of 1 ℃/min, and keeping the temperature for 15h to obtain the material of the carbon-coated primary particles. Subsequently, the above material was pulverized to obtain secondary particles having a particle size of D50 ═ 12 μm, that is, a silicon carbon negative electrode material.
SEM (scanning electron microscope) detection is carried out on the silicon-carbon negative electrode material obtained in the example 1, and an electron micrograph is shown in figure 2, so that the silicon-carbon negative electrode material has a uniform secondary particle appearance.
Comparative example 1
The preparation process of this comparative example is the same as that of example 1, except that the primary particles obtained in steps (1) to (3) are the final silicon carbon negative electrode material.
The silicon-carbon anode materials obtained in example 1 and comparative example 1 were respectively subjected to cycle performance tests, and as shown in fig. 3, compared with the primary particle silicon-carbon anode material obtained in comparative example 1, the secondary particle silicon-carbon anode material obtained in example 1 has no obvious decrease in gram specific capacity and is stable with the increase of cycle number, and has better cycle performance.
By comparison, the silicon carbon negative electrode material obtained in example 1 has both the advantages of the small particle size particles and the advantages of the large particle size particles, and thus has better cycle performance and longer service life.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
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| CN111509232B (en) * | 2020-05-29 | 2022-10-25 | 蜂巢能源科技有限公司 | Positive electrode sheet and its preparation method and application |
| CN117790704A (en) * | 2022-09-29 | 2024-03-29 | 贝特瑞新材料集团股份有限公司 | Negative electrode material and preparation method thereof, and secondary battery |
| CN116190592A (en) * | 2022-12-14 | 2023-05-30 | 贝特瑞新材料集团股份有限公司 | Negative electrode materials and lithium-ion batteries |
| CN119170786A (en) * | 2024-11-18 | 2024-12-20 | 赣州立探新能源科技有限公司 | Secondary particle silicon-carbon material and preparation method and application thereof |
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