CN-122000338-A - Silane deposited silicon-carbon composite material and preparation method and application thereof

CN122000338ACN 122000338 ACN122000338 ACN 122000338ACN-122000338-A

Abstract

The invention provides a silane deposited silicon-carbon composite material, and a preparation method and application thereof, and belongs to the technical field of lithium battery materials. The invention obtains a first precursor by in-situ reaction of zinc salt, dimethyl imidazole and pore-forming agent, and obtains a silane deposited silicon-carbon composite material by alkali activation and vapor deposition after carbonization treatment. The silane deposited silicon carbon composite material prepared by the method has good stability and mechanical strength, hierarchical pore structure distribution and high capacity and ultra-long circulation, and the method can solve the problems that the structural stability of the existing vapor deposited silicon carbon is poor, and the pore channel of a carbon matrix obtained by carbonization of the traditional ZIF-8 is easy to collapse.

Inventors

LI SHENG
WANG FANGRUI
Wang Daomiao
YUAN LIANG
LAI GUITANG
FANG BIN
HUANG SHIQIANG
CAO ENDE
CHEN JUNYI
MAO MIAOMIAO
CHEN ZIHAO

Assignees

银硅(宁波)科技有限公司
银硅(宜昌)科技有限公司

Dates

Publication Date: 20260508
Application Date: 20260311

Claims (10)

1. The preparation method of the silane deposited silicon-carbon composite material is characterized by comprising the following steps of: mixing zinc salt, dimethyl imidazole, a pore-forming agent and a solvent, and then carrying out in-situ reaction to obtain a first precursor; carbonizing the precursor to obtain a second precursor; mixing the second precursor with an alkali activator, performing heat treatment, and pickling the obtained product to obtain a third precursor; and under the condition of shielding gas, introducing silane gas into the third precursor, performing vapor deposition, introducing carbon source gas, and performing carbon coating to obtain the silane deposited silicon-carbon composite material.
2. The method of preparation of claim 1, wherein the zinc salt comprises one or more of zinc nitrate, zinc acetate, zinc sulfate, and zinc chloride; The pore-forming agent comprises one of Pluronic F-127, polyvinylpyrrolidone, cetyltrimethylammonium bromide, sodium dodecyl sulfate, polyethylene glycol and polystyrene microsphere.
3. The method of preparation according to claim 1 or 2, wherein the solvent comprises one or more of water, methanol and ethanol; The mass ratio of the zinc salt to the dimethylimidazole is 1:1-10, and the mass of the pore-forming agent is 0.1-20% of the total mass of the zinc salt and the dimethylimidazole.
4. The preparation method according to claim 3, wherein the in-situ reaction is performed at room temperature for 12-36 hours.
5. The production method according to claim 1, wherein the carbonization treatment is performed at a temperature of 800 to 1200 ℃ for 2to 5 hours, and a temperature rising rate from a temperature of 1 to 10 ℃ per minute.
6. The preparation method of claim 1, wherein the alkali activator comprises one or more of KOH, naOH and K 2 CO 3 , and the mass ratio of the alkali activator to the second precursor is 1-4:1; The temperature of the heat treatment is 600-900 ℃, the time is 1-3 h, and the temperature is raised until the temperature rise rate of the heat treatment is 2-5 ℃ per minute.
7. The method according to claim 1, wherein the acid used for the acid washing is one or more of hydrochloric acid, nitric acid and sulfuric acid.
8. The preparation method of the silicon dioxide film according to claim 1, wherein the shielding gas is one or more of nitrogen, argon and helium, the silane gas comprises one or two of monosilane and disilane, the flow ratio of the silane gas to the shielding gas is 1:1-10, the vapor deposition temperature is 500-1000 ℃ and the time is 6-12 h; the carbon source gas comprises one or more of methane, ethane, propane, acetylene and propyne, the flow ratio of the carbon source gas to the shielding gas is 1:1-10, the temperature of the carbon coating is 500-1000 ℃, and the time is 6-12 h.
9. The silane-deposited silicon-carbon composite material prepared by the preparation method of any one of claims 1-8 is characterized in that the Si content is 10-90 wt% and the carbon content is 10-90 wt%.
10. The use of the silane deposited silicon-carbon composite material of claim 9 in a negative electrode material of a lithium ion battery.

Description

Silane deposited silicon-carbon composite material and preparation method and application thereof Technical Field The invention relates to the technical field of lithium battery materials, in particular to a silane deposited silicon-carbon composite material, and a preparation method and application thereof. Background Lithium ion batteries have become the mainstream products of electrochemical energy storage at present due to the advantages of high specific energy, long cycle life, no memory, low self-discharge rate and the like. Currently, commercial anode materials are mainly graphite, but the lower theoretical specific capacity (372 mAh/g) is difficult to meet the requirement. While silicon, while having a theoretical specific capacity as high as 4200 mAh/g and a lower operating potential, is inherently poor in electrical conductivity and undergoes more than 300% volume expansion during the insertion/extraction process of Li +. These factors severely limit the commercialization of silicon-based cathodes. For this reason, silicon particles are generally nanocrystallized to suppress the pulverization phenomenon of the material during charge and discharge while relieving the volume expansion effect thereof, and silicon is restrained in volume expansion by a high-strength material and to improve conductivity. The silicon-carbon composite material prepared by the vapor deposition method not only can obtain silicon particles smaller than 10 nm, but also can realize the in-situ limited-domain growth of the silicon particles through the abundant micropore structure of the porous carbon matrix, and meanwhile, the silicon-carbon composite material is beneficial to the excellent conductivity and mechanical strength of the carbon material, and the vapor deposition silicon-carbon cathode shows excellent specific capacity and cycle stability. However, the porous carbon still has the problems of insufficient structural stability, poor interfacial stability and the like as a carbon matrix. Patent CN117352685A pyrolyzes ZIF-8 metal organic framework to obtain porous carbon framework, and then introduces silicon source to perform vapor deposition reaction to obtain silicon-carbon composite material, but the method needs to precisely control pyrolysis temperature to avoid partial pore collapse phenomenon caused by too high pyrolysis temperature. Therefore, a more excellent carbon matrix structure is still required to be explored to improve the mechanical strength of the vapor deposition silicon-carbon negative electrode and improve the interface stability of the material, so that a novel silane deposition silicon negative electrode material with excellent performance is obtained. Disclosure of Invention The invention aims to provide a silane deposited silicon-carbon composite material, a preparation method and application thereof, wherein the silane deposited silicon-carbon composite material has good stability and mechanical strength, multistage pore structure distribution and high capacity and ultra-long cycle. In order to achieve the above object, the present invention provides the following technical solutions: the invention provides a preparation method of a silane deposited silicon-carbon composite material, which comprises the following steps: mixing zinc salt, dimethyl imidazole, a pore-forming agent and a solvent, and then carrying out in-situ reaction to obtain a first precursor; carbonizing the precursor to obtain a second precursor; mixing the second precursor with an alkali activator, performing heat treatment, and pickling the obtained product to obtain a third precursor; and under the condition of shielding gas, introducing silane gas into the third precursor, performing vapor deposition, introducing carbon source gas, and performing carbon coating to obtain the silane deposited silicon-carbon composite material. Preferably, the zinc salt comprises one or more of zinc nitrate, zinc acetate, zinc sulphate and zinc chloride; The pore-forming agent comprises one of Pluronic F-127, polyvinylpyrrolidone, cetyltrimethylammonium bromide, sodium dodecyl sulfate, polyethylene glycol and polystyrene microsphere. Preferably, the solvent comprises one or more of water, methanol and ethanol; The mass ratio of the zinc salt to the dimethylimidazole is 1:1-10, and the mass of the pore-forming agent is 0.1-20% of the total mass of the zinc salt and the dimethylimidazole. Preferably, the temperature of the in-situ reaction is room temperature and the time is 12-36 hours. Preferably, the carbonization temperature is 800-1200 ℃, the time is 2-5h, and the heating rate from the heating to the carbonization temperature is 1-10 ℃ per minute. Preferably, the alkali activator comprises one or more of KOH, naOH and K 2CO3, and the mass ratio of the alkali activator to the second precursor is 1-4:1; The temperature of the heat treatment is 600-900 ℃, the time is 1-3 h, and the temperature is raised until the temperature rise rate of