CN110518226B - Silicon-carbon composite negative electrode material and preparation method thereof - Google Patents
Silicon-carbon composite negative electrode material and preparation method thereof Download PDFInfo
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Abstract
The invention provides a silicon-carbon composite negative electrode material, wherein the surface of a silicon-carbon composite material is coated with lithium acetate, and the lithium acetate has the property similar to that of an SEI (solid electrolyte interphase) film, so that the consumption of lithium ions is reduced in the charge-discharge process, and the primary efficiency of the silicon-carbon composite material is improved; meanwhile, the surface coating layer lithium acetate has the characteristic of high lithium ion content, so that sufficient lithium ions are provided in the charging and discharging process, and the multiplying power and the cycle performance of the material are improved. The inner core of the silicon-carbon composite negative electrode material provided by the invention adopts a silane coupling agent to react with a silane compound to form a cross-linked polymer, so that a silicon oxide compound with a stable net structure is obtained, and titanium dioxide is doped in the silicon oxide compound, so that the conductivity and the safety performance of the material are improved by virtue of the characteristics of high conductivity and high voltage platform of the titanium dioxide; meanwhile, the conductivity of the silicon-carbon material is further improved by using a conductive agent with large specific surface area and strong conductivity.
Description
Technical Field
The invention belongs to the field of lithium ion battery materials, and particularly relates to a silicon-carbon composite negative electrode material and a preparation method thereof.
Background
With the increase of the demand of marketization on the high-specific energy density lithium ion battery, the lithium ion battery cathode material is required to have high specific capacity and cycle performance in the market, graphite is mostly adopted as a raw material for the lithium ion battery cathode in the current market, however, the theoretical capacity of the graphite is only 372mAh/g, and the higher demand of the market on the cathode is difficult to meet. Silicon materials are considered by researchers because of their advantages such as theoretical capacity up to 4200mAh/g, lower cleavage potential and abundant storage capacity. However, silicon generates huge volume change in the charging and discharging process, the change can reach 300% of the original volume, so that the silicon structure is rapidly pulverized and damaged, and the multiplying power performance of the material is influenced by low conductivity of the material. Meanwhile, the electrolyte is contacted with silicon to form an SEI film with poor stability on the surface of the silicon, so that the charge-discharge efficiency is greatly reduced, and the cycle performance is further reduced.
The defects of the carbon-silicon material seriously affect the industrial popularization of the silicon-carbon material, although researchers improve the volume change and the conductivity of the material by means of nanocrystallization, alloying, composite carbon-based materials and the like of the material, for example, the researchers have the problem of compensating the poor conductivity of the silicon material by adopting the amorphous carbon and the silicon material to form an alloy. However, the problems of the silicon cathode in various aspects are not solved systematically, and particularly the problems of low efficiency for the first time and the like.
The patent application numbers are: 201610807619.2 discloses a silicon-carbon cathode material containing an artificial SEI layer with high volume specific capacity and cycle performance, which is composed of a secondary granulation structure, an outer shell layer which is an amorphous carbon coating layer, an inner shell layer which is a compact LiF film and an inner core which is a mesophase graphite structure with uniformly dispersed nano-silicon, so as to improve the cycle and the first efficiency of the material. However, the conductivity of the material is not improved, and the improvement range of the first efficiency is not obvious, because the LiF film of the inner shell is an inorganic film and has general compatibility with an organic electrolyte, and good cycle performance cannot be achieved.
Disclosure of Invention
In order to solve the technical problems, the invention provides a silicon-carbon composite negative electrode material, wherein a shell of the silicon-carbon composite negative electrode material contains a lithium acetate organic film with a Solid Electrolyte Interphase (SEI) component, and a core of the silicon-oxygen compound composite material contains titanium dioxide, and the organic film is doped with titanium dioxide with high conductivity so as to improve the first efficiency, rate capability and cycle performance of the material.
The invention aims to provide a silicon-carbon composite negative electrode material.
The invention also aims to provide a preparation method of the silicon-carbon composite anode material.
The silicon-carbon composite negative electrode material provided by the invention is of a core-shell structure, and the inner core material comprises 67.5-82.5 wt% of silica compound, 7.5-12.375 wt% of conductive agent, 7.5-12.375 wt% of titanium dioxide and the balance of amorphous carbon according to weight percentage; the shell material comprises, by weight, 98-99 wt% of lithium acetate and the balance of sodium dodecyl benzene sulfonate; the thickness of the shell is 50-500 nm.
The silicon-carbon composite negative electrode material provided by the invention is of a core-shell structure, wherein the inner core comprises a silica compound, a conductive agent, titanium dioxide and amorphous carbon, the silica compound is of a net structure, the titanium dioxide is doped, the conductivity and the safety performance are improved by means of the characteristics of strong conductivity and high voltage platform of the titanium dioxide, the amorphous carbon is generated on the surface of the inner core material, the conductivity of the material is improved, and the occurrence probability of side reactions is reduced. The shell material is lithium acetate containing a small amount of sodium dodecyl benzene sulfonate, the lithium acetate has the property similar to that of a solid electrolyte membrane, so that the consumption of lithium ions is reduced in the charging and discharging process, the first efficiency of the silicon-oxygen composite material is improved, the multiplying power and the cycle performance of the material are improved, the sodium dodecyl benzene sulfonate is doped in the lithium acetate, sodium ion doping is brought to the material, and the structural stability of the cathode material is improved.
Preferably, the silicon oxide compound is SiOXWherein X is more than or equal to 0.5 and less than or equal to 2.
Preferably, the conductive agent is one of carbon nanotubes, vapor-deposited carbon fibers, super black, and graphene.
The invention provides a preparation method of the silicon-carbon composite negative electrode material, which comprises the following steps:
(1) adding a silane compound and a silane coupling agent into an organic solvent, uniformly mixing, then adding a conductive agent and titanium dioxide, carrying out ball milling, and carbonizing in an argon atmosphere to obtain a silicon-carbon composite material;
(2) dissolving lithium acetate in a solvent to prepare a 1-10% lithium acetate solution, adding sodium dodecyl benzene sulfonate, the silicon-carbon composite material obtained in the step (1) and distilled water to prepare a uniform solution, and performing spray drying to obtain the silicon-carbon composite negative electrode material.
The preparation method of the silicon-carbon composite negative electrode material comprises the steps of firstly preparing a core material, wherein the core material takes a silane compound, a silane coupling agent, a conductive agent, titanium dioxide and an organic solvent as raw materials, the silane compound and the silane coupling agent are subjected to a crosslinking reaction in the organic solvent to generate a polysilane compound, an active group in the silane coupling agent is reacted with an alkyl group of the silane compound to generate a crosslinking compound, the boiling point of the crosslinking compound is obviously higher than the boiling point of the silane compound/silane coupling agent, the organic solvent is adsorbed on the surface of the formed polysilane compound at the same time, and then the solvent is carbonized, so that the condition that the solvent is volatilized exists, components generating carbon are deposited on the surface of the silane compound, and finally compounds formed by elements such as silicon, carbon, oxygen and the like are formed. Hydrocarbons in the organic solvent adsorbed on the surface of the material in the carbonization process form amorphous carbon after high temperature, so that the surface of the core material is formed, and the electrical conductivity of the material is increased.
Preferably, in the step (1), the silane compound is one of trimethyl bromosilane, triethyl chlorosilane, dimethyl chlorosilane, monophenyl trichlorosilane, n-octyl trichlorosilane, dimethyl dichlorosilane, diisopropyl chlorosilane and trimethylsilylated diazomethane.
Preferably, in the step (1), the silane coupling agent is one of gamma-aminopropyltriethoxysilane, gamma- (2, 3-glycidoxy) propyltrimethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane, octyltriethoxysilane and dimethyldimethoxysilane.
Preferably, the organic solvent is one of N-methyl pyrrolidone, carbon tetrachloride, benzene, xylene and cyclohexane.
Preferably, in the step (1), the weight ratio of the silane compound, the silane coupling agent, the conductive agent, the titanium dioxide and the organic solvent is 10-30: 1-5: 100-500.
Preferably, in the step (1), the carbonization temperature is 780-820 ℃ and the time is 6 h.
Preferably, in the step (2), the solvent is a mixed solution of ethanol and water, and the volume ratio of the ethanol to the water is 1: 1.
Preferably, in the step (2), the weight ratio of the lithium acetate to the silicon-carbon composite material to the sodium dodecyl benzene sulfonate is 1-3: 100: 0.5-2.
Preferably, the temperature of the air inlet of the spray drying in the step (2) is 120-180 ℃, and the temperature of the air outlet is 80-120 ℃.
The invention has the beneficial effects that:
1. according to the silicon-carbon composite negative electrode material provided by the invention, the surface of the silicon-carbon composite material is coated with lithium acetate, wherein the lithium acetate has the property similar to that of an SEI (solid electrolyte interphase) film, so that the consumption of lithium ions is reduced in the charge-discharge process, and the primary efficiency of the silicon-carbon composite material is improved; meanwhile, the surface coating layer lithium acetate has the characteristic of high lithium ion content, so that sufficient lithium ions are provided in the charging and discharging process, and the multiplying power and the cycle performance of the material are improved.
2. The inner core of the silicon-carbon composite negative electrode material provided by the invention adopts a silane coupling agent to react with a silane compound to form a crosslinked polymer, has the characteristic of stable structure, is doped with titanium dioxide, and improves the conductivity and safety performance of the material by virtue of the characteristics of strong conductivity and high voltage platform of the titanium dioxide; meanwhile, the conductivity of the silicon-carbon material is further improved by using a conductive agent with large specific surface area and strong conductivity.
3. According to the preparation method provided by the invention, the material is carbonized in an inert atmosphere, so that an amorphous carbon material is generated on the surface of the inner core material, the conductivity of silicon is increased, the volume effect of the silicon in the de-intercalation process is buffered, the conductivity of the silicon is improved, and the occurrence probability of side reactions of the silicon is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is an SEM image of the silicon-carbon composite anode material obtained in example 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
Example 1
A silicon-carbon composite negative electrode material is of a core-shell structure, and comprises 74-75 wt% of a silica compound, 8.25-11.25 wt% of a conductive agent, 8.25-11.25 wt% of titanium dioxide and the balance of amorphous carbon according to weight percentage; the shell material comprises, by weight, 98-99 wt% of lithium acetate and the balance of sodium dodecyl benzene sulfonate; the thickness of the shell is 50-500 nm.
The preparation method of the silicon-carbon composite negative electrode material comprises the following steps:
(1) firstly, adding 20g of trimethyl bromosilane and 3g of gamma-aminopropyltriethoxysilane into 300ml of N-methylpyrrolidone organic solvent, uniformly mixing, adding 3g of carbon nano tube and 3g of titanium dioxide, carrying out wet ball milling at the ball milling rotation speed of 500 rpm for 12 hours, and then carbonizing at 800 ℃ for 6 hours under the argon atmosphere to obtain the silicon-carbon composite material;
(2) dissolving 2g of lithium acetate in 40ml of mixed solvent of ethanol and water, wherein the volume ratio of ethanol to water in the mixed solvent is 1:1, preparing a lithium acetate solution with the mass concentration of 5%, then adding 100g of the silicon-carbon composite material obtained in the step (1), 1g of sodium dodecyl benzene sulfonate and 200ml of secondary distilled water to prepare a uniform solution, and performing spray drying, wherein the temperature of an air inlet of the spray drying is set to be 150 ℃, the temperature of an air outlet of the spray drying is set to be 100 ℃, so as to obtain the silicon-carbon composite negative electrode material with the shell coated with the lithium acetate.
Example 2
The silicon-carbon composite negative electrode material is of a core-shell structure, and the inner core material comprises 67.5-74.25 wt% of a silica compound, 7.5-8.25 wt% of a conductive agent, 7.5-8.25 wt% of titanium dioxide and the balance of amorphous carbon according to weight percentage; the shell material comprises, by weight, 98-99 wt% of lithium acetate and the balance of sodium dodecyl benzene sulfonate; the thickness of the shell is 50-500 nm.
The preparation method of the silicon-carbon composite negative electrode material comprises the following steps:
(1) adding 10g of triethylchlorosilane and 1g of gamma- (2, 3-epoxypropoxy) propyl trimethoxy silane into 100ml of carbon tetrachloride organic solvent, uniformly mixing, then adding 1g of vapor deposition carbon fiber and 1g of titanium dioxide, carrying out wet ball milling at the rotating speed of 500 rpm for 12h, and then carbonizing at 780 ℃ for 6h under argon atmosphere to obtain a silicon-carbon composite material;
(2) dissolving 1g of lithium acetate in 100ml of mixed solvent of ethanol and water, wherein the volume ratio of ethanol to water in the mixed solvent is 1:1, preparing a lithium acetate solution with the mass concentration of 1%, then adding 100g of the silicon-carbon composite material obtained in the step (1), 0.5g of sodium dodecyl benzene sulfonate and 200ml of secondary distilled water to prepare a uniform solution, and performing spray drying, wherein the temperature of an air inlet of the spray drying is set to be 120 ℃, the temperature of an air outlet of the spray drying is set to be 80 ℃, so as to obtain the silicon-carbon composite negative electrode material with the shell coated with the lithium acetate.
Example 3
The silicon-carbon composite negative electrode material is of a core-shell structure, and the inner core material comprises 75-82.5 wt% of silica compound, 11.25-12.375 wt% of conductive agent, 11.25-12.375 wt% of titanium dioxide and the balance of amorphous carbon according to weight percentage; the shell material comprises, by weight, 98-99 wt% of lithium acetate and the balance of sodium dodecyl benzene sulfonate; the thickness of the shell is 50-500 nm.
The preparation method of the silicon-carbon composite negative electrode material comprises the following steps:
(1) adding 30g of dimethyldichlorosilane and 5g of gamma- (methacryloyloxy) propyl trimethoxy silane into 500ml of xylene organic solvent, uniformly mixing, then adding 5g of graphene and 5g of titanium dioxide, carrying out wet ball milling at the rotation speed of 500 r/min for 12h, and then carbonizing at 820 ℃ for 6h under the argon atmosphere to obtain the silicon-carbon composite material;
2) dissolving 3g of lithium acetate in 30ml of mixed solvent of ethanol and water, wherein the volume ratio of ethanol to water in the mixed solvent is 1:1, preparing a lithium acetate solution with the mass concentration of 10%, then adding 100g of the silicon-carbon composite material obtained in the step (1), 2g of sodium dodecyl benzene sulfonate and 200ml of secondary distilled water to prepare a uniform solution, and performing spray drying, wherein the temperature of an air inlet of the spray drying is set to be 180 ℃, the temperature of an air outlet of the spray drying is set to be 120 ℃, so as to obtain the silicon-carbon composite negative electrode material with the shell coated with the lithium acetate.
Comparative example 1
The silicon-carbon composite negative electrode material is prepared by the following steps:
firstly, 20g of trimethyl bromosilane is added into 300ml of N-methyl pyrrolidone organic solvent to be uniformly mixed, then 3g of carbon nano tube conductive agent is added, wet ball milling is carried out, the rotating speed of the ball milling is 500 r/min, the time is 12 hours, and then carbonization is carried out for 6 hours at 800 ℃ under the argon atmosphere, so as to obtain the silicon-carbon composite material.
Test examples
SEM test
SEM test was performed on the silicon composite anode material obtained in example 1, and the test results are shown in fig. 1. As can be seen from FIG. 1, the particle size distribution of the material is uniform and reasonable, and the particle size of the particles is between 5 and 15 μm.
2. Button cell test
The silicon composite negative electrode materials obtained in the examples 1-3 and the comparative example 1 are used as negative electrode materials of lithium ion batteries to assemble button batteries.
The preparation method comprises the following steps: in the negative electrode material of lithium ion batteryAdding a binder, a conductive agent and a solvent, stirring and pulping, coating the mixture on a copper foil, and drying and rolling to prepare a negative plate; the binder is LA132, the conductive agent is conductive carbon black (SP), the solvent is N-methylpyrrolidone (NMP), and the dosage ratio of the negative electrode material, SP, LA132 and NMP is 95 g: 1 g: 4 g: 220 mL; LiPF in electrolyte6A mixture of EC and DEC with the volume ratio of 1:1 is used as a solvent as electrolyte; the metal lithium sheet is a counter electrode, and the diaphragm is a polypropylene (PP) film. Button cell assembly was performed in an argon-filled glove box. The electrochemical performance is carried out on a Wuhan blue electricity CT2001A type battery tester, the charging and discharging voltage range is 0.005V-2.0V, and the charging and discharging speed is 0.1C. The test results are shown in table 1.
TABLE 1 Performance test results for different cathode materials
As can be seen from the data in Table 1, the specific capacity and the first efficiency of the silicon-carbon composite anode material prepared in the embodiments 1-3 of the invention are obviously superior to those of the comparative example 1. The surface of the core material of the negative electrode material is coated with the lithium acetate shell, so that the quantity of lithium ions in the charging and discharging process is increased, sufficient lithium ions can be provided for forming an SEI (solid electrolyte interphase) film, and the first efficiency and the specific capacity of the negative electrode material are further improved. Meanwhile, the structural stability of the material is improved by adding the silane coupling agent, and the gram volume performance of the material is further improved.
3. Pouch cell testing
The silicon-carbon composite materials in examples 1 to 3 and comparative example were used as negative electrode materials to prepare negative electrode sheets, and ternary material (Li (Ni)0.6Co0.2Mn0.2)O2) Is a positive electrode material; LiPF in electrolyte6As an electrolyte, a mixture of Ethylene Carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 1:1 is used as a solvent; a5 Ah soft package battery is prepared by taking Celgard 2400 membrane as a diaphragm and is marked as C1. C2, C3, and D1.
3.1 testing of liquid absorption Capacity and liquid Retention
3.1.1 liquid absorption Capacity
And (3) adopting a 1mL burette, sucking the electrolyte VmL, dripping a drop on the surface of the pole piece, timing until the electrolyte is completely absorbed, recording the time t, and calculating the liquid absorption speed V/t of the pole piece. The test results are shown in table 2.
3.1.2 liquid retention test
Calculating the theoretical liquid absorption amount m of the pole piece according to the pole piece parameters1And weighing the weight m of the pole piece2Then, the pole piece is placed in electrolyte to be soaked for 24 hours, and the weight of the pole piece is weighed to be m3Calculating the amount m of the pole piece liquid absorption3-m2And calculated according to the following formula: retention rate ═ m3-m2)*100％/m1. The test results are shown in table 2.
3.2 testing resistivity and rebound rate of pole piece
3.2.1 Pole piece resistivity test
The resistivity of the pole piece was measured using a resistivity tester, and the results are shown in table 3.
3.2.2 Pole piece rebound Rate testing
Firstly, testing the average thickness of the pole piece to be D1 by using a thickness gauge, then placing the pole piece in a vacuum drying oven at 80 ℃ for drying for 48h, testing the thickness of the pole piece to be D2, and calculating according to the following formula: the rebound rate was (D2-D1) × 100%/D1. The test results are shown in table 3.
3.3 cycle Performance test
The cycle performance of the battery is tested at the temperature of 25 +/-3 ℃ with the charge-discharge multiplying power of 1C/1C and the voltage range of 2.8V-4.2V. The test results are shown in table 4.
TABLE 2 results of the liquid absorption and retention capability test of the electrode sheets made of different negative electrode materials
As can be seen from Table 2, the liquid absorbing and retaining capabilities of the silicon-carbon composite negative electrode materials obtained in examples 1-3 are obviously higher than those of comparative example 1. Experimental results show that the silicon-carbon composite negative electrode material provided by the invention has high liquid absorption and retention capacity. The shell coating layer of the silicon-carbon composite negative electrode material provided by the invention contains the organic lithium compound, so that the organic lithium compound has good compatibility with electrolyte, and the liquid absorption and retention capacity of a pole piece can be improved; the silicon-carbon composite negative electrode materials of embodiments 1 to 3 have a large specific surface area, and the liquid absorption and retention capacity of the materials is further improved.
TABLE 3 rebound Rate test results for Pole pieces made of different cathode materials
| Group of | Rebound Rate (%) of Pole piece | Pole piece resistivity (m omega) |
| Example 1 | 12.7 | 16.8 |
| Example 2 | 13.6 | 17.9 |
| Example 3 | 15.5 | 20.1 |
| Comparative example 1 | 19.6 | 178.5 |
As can be seen from the data in table 3, the negative electrode sheet prepared by using the silicon-carbon composite negative electrode materials obtained in examples 1 to 3 has a significantly lower rebound ratio than that of comparative example 1, that is, the negative electrode sheet prepared by using the silicon-carbon composite negative electrode material of the present invention has a lower rebound ratio. The material is added with the silane coupling agent to enable the silane compound to form a net structure, and then the silicon oxide compound is formed, so that the structural stability of the material is improved, the rebound rate of the pole piece is further reduced, meanwhile, the material contains the titanium dioxide with high conductivity and the conductive agent, the electronic conductivity of the material is favorably improved, and the resistivity of the pole piece is further reduced.
TABLE 4 cycling performance of batteries made with different anode materials
| Battery with a battery cell | Negative electrode material | Capacity retention (%) after 500 cycles |
| C1 | Example 1 | 84.62 |
| C2 | Example 2 | 83.78 |
| C3 | Example 3 | 82.39 |
| D1 | Comparative example 1 | 75.76 |
As can be seen from table 4, the cycle performance of the battery made of the silicon-carbon composite anode material provided by the invention is obviously better than that of comparative example 1. The electrode plate prepared from the silicon-carbon composite negative electrode material provided by the invention has a lower expansion rate, the structure of the electrode plate is more stable in the charging and discharging processes, and the cycle performance of the electrode plate is improved. In addition, the silicon-carbon composite negative electrode material has the characteristic of high lithium ion content, provides sufficient lithium ions in the charging and discharging process, and further improves the cycle performance of the battery.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (7)
1. The silicon-carbon composite negative electrode material is characterized in that the silicon-carbon composite negative electrode material is of a core-shell structure, and the inner core material comprises 67.5-82.5 wt% of silica compound, 7.5-12.375 wt% of conductive agent, 7.5-12.375 wt% of titanium dioxide and the balance of amorphous carbon according to weight percentage; the shell material comprises, by weight, 98-99 wt% of lithium acetate and the balance of sodium dodecyl benzene sulfonate; the thickness of the shell is 50-500 nm;
the preparation method of the silicon-carbon composite negative electrode material comprises the following steps: (1) adding a silane compound and a silane coupling agent into an organic solvent, uniformly mixing, then adding a conductive agent and titanium dioxide, carrying out ball milling, and carbonizing in an argon atmosphere to obtain a silicon-carbon composite material;
the silane compound is one of trimethyl bromosilane, triethyl chlorosilane, dimethyl chlorosilane, monophenyl trichlorosilane, n-octyl trichlorosilane, dimethyl dichlorosilane, diisopropyl chlorosilane and trimethylsilyl diazomethane;
the silane coupling agent is one of gamma-aminopropyltriethoxysilane, gamma- (2, 3-epoxypropoxy) propyltrimethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane, octyltriethoxysilane and dimethyldimethoxysilane;
the organic solvent comprises N-methyl pyrrolidone, carbon tetrachloride or xylene;
the conductive agent is one of carbon nano tube, vapor deposition carbon fiber, super carbon black and graphene;
(2) dissolving lithium acetate in a solvent to prepare a 1-10% lithium acetate solution, adding sodium dodecyl benzene sulfonate, the silicon-carbon composite material obtained in the step (1) and distilled water to prepare a uniform solution, and performing spray drying to obtain the silicon-carbon composite negative electrode material.
2. The silicon-carbon composite anode material as claimed in claim 1, wherein the silicon oxide compound is SiOXWherein X is more than or equal to 0.5 and less than or equal to 2.
3. The preparation method of the silicon-carbon composite anode material according to claim 1, characterized by comprising the following steps:
(1) adding a silane compound and a silane coupling agent into an organic solvent, uniformly mixing, then adding a conductive agent and titanium dioxide, carrying out ball milling, and carbonizing in an argon atmosphere to obtain a silicon-carbon composite material;
the silane compound is one of trimethyl bromosilane, triethyl chlorosilane, dimethyl chlorosilane, monophenyl trichlorosilane, n-octyl trichlorosilane, dimethyl dichlorosilane, diisopropyl chlorosilane and trimethylsilyl diazomethane;
the silane coupling agent is one of gamma-aminopropyltriethoxysilane, gamma- (2, 3-epoxypropoxy) propyltrimethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane, octyltriethoxysilane and dimethyldimethoxysilane;
the organic solvent comprises N-methyl pyrrolidone, carbon tetrachloride or xylene;
the conductive agent is one of carbon nano tube, vapor deposition carbon fiber, super carbon black and graphene;
(2) dissolving lithium acetate in a solvent to prepare a 1-10% lithium acetate solution, adding sodium dodecyl benzene sulfonate, the silicon-carbon composite material obtained in the step (1) and distilled water to prepare a uniform solution, and performing spray drying to obtain the silicon-carbon composite negative electrode material.
4. The method for producing a silicon-carbon composite anode material according to claim 3, wherein in the step (1), the silane compound: silane coupling agent: conductive agent: titanium dioxide: the weight ratio of the organic solvent is 10-30: 1-5: 1-5: 1-5: 100 to 500.
5. The preparation method of the silicon-carbon composite anode material according to claim 3, wherein in the step (1), the carbonization temperature is 780-820 ℃ and the carbonization time is 6 hours.
6. The method for preparing the silicon-carbon composite anode material according to claim 3, wherein in the step (2), the solvent is a mixed solution of ethanol and water, and the volume ratio of ethanol to water is 1: 1.
7. The preparation method of the silicon-carbon composite negative electrode material as claimed in claim 3, wherein in the step (2), the weight ratio of the lithium acetate to the silicon-carbon composite material to the sodium dodecyl benzene sulfonate is 1-3: 100: 0.5 to 2.
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| CN111293299B (en) * | 2020-02-28 | 2021-07-27 | 苏州清陶新能源科技有限公司 | Modified metal lithium negative electrode battery and preparation method thereof |
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| CN114566619B (en) * | 2021-12-25 | 2023-11-28 | 河南大森林生物科技有限公司 | Green method for preparing lithium ion battery composite anode material by using siliceous biomass |
| CN114843482B (en) * | 2022-05-23 | 2024-06-11 | 常州烯源谷新材料科技有限公司 | Core-shell type silicon-carbon composite material and preparation method and application thereof |
| CN115020710A (en) * | 2022-07-11 | 2022-09-06 | 陕西君和聚源科技有限公司 | Low-expansion silicon-based composite negative electrode material, preparation method thereof and lithium ion battery |
| CN116230911B (en) * | 2023-03-10 | 2024-04-16 | 内蒙古欣源石墨烯科技股份有限公司 | High-power silicon-carbon negative electrode composite material and preparation method thereof |
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