CN-122025599-A - Silicon-based anode material, preparation method thereof and battery

CN122025599ACN 122025599 ACN122025599 ACN 122025599ACN-122025599-A

Abstract

The invention provides a silicon-based anode material, a preparation method thereof and a battery, wherein the silicon-based anode material comprises an inner core and an artificial SEI film coated on the surface of the inner core, the inner core comprises a silicon-containing material, the artificial SEI film comprises a polymer material, and a monomer of the polymer material contains a triazine ring, at least two trihalomethyl groups and at least one furan ring. The artificial SEI film of the silicon-based anode material is a specific polymer containing various functional groups, can simultaneously improve the high-temperature stability, the conductivity, the quick charge capacity, the structural stability and the like of the silicon-containing material, comprehensively improves the performance defects of the silicon-containing material, and particularly meets the high-temperature application requirements of batteries.

Inventors

XIE YINGPENG
ZHAO RUIRUI
JI YAJUAN
LI WENTAO
XU XIAOXIA

Assignees

惠州亿纬锂能股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260313

Claims (10)

1. The silicon-based anode material is characterized by comprising an inner core and an artificial SEI film coated on the surface of the inner core, wherein the inner core comprises a silicon-containing material, and the artificial SEI film comprises a polymer material; the structural formula of the monomer of the polymer material is shown as formula I): ; Formula I); Wherein at least two of R 1 、R 2 and R 3 contain a trihalomethyl group and at least one contains a furan ring.
2. The silicon-based anode material according to claim 1, wherein R 1 and R 2 each contain a trihalomethyl group; Preferably, the R 3 contains a furan ring; preferably, the trihalomethyl group comprises a trichloromethyl group; Preferably, the monomers of the polymeric material comprise And/or 。
3. The silicon-based anode material according to claim 1 or 2, wherein the number average molecular weight of the polymer material is 8 x 10 4 g/mol~9×10 7 g/mol; Preferably, in the silicon-based anode material, the mass ratio of the artificial SEI film is 0.3-4 wt%; Preferably, the thickness of the artificial SEI film is 30 nm-120 nm; Preferably, the artificial SEI film has a porosity of 15% -30%.
4. The silicon-based anode material according to claim 1 or 2, wherein the particle diameter D50 of the silicon-containing material is 3 μm to 7 μm; Preferably, the specific surface area of the silicon-containing material is 1m 2 /g~4m 2 /g; Preferably, the silicon-containing material comprises a silicon-carbon material; preferably, the silicon carbon material comprises silicon grains and a hard carbon substrate.
5. The silicon-based anode material according to claim 4, wherein the mass ratio of the silicon crystal grains to the hard carbon substrate is (0.4-1.2): 1; preferably, the hard carbon substrate comprises micropores and mesopores; Preferably, the pore diameter of the micropore is 0.8-1.5 nm, and the pore volume accounts for 20-40% of the total pore volume of the hard carbon substrate; preferably, the pore diameter of the mesoporous is 5-20 nm, and the pore volume accounts for 60-80% of the total pore volume of the hard carbon substrate; Preferably, the size of the silicon crystal grains is 0.8 nm-2 nm.
6. A method for producing a silicon-based anode material according to any one of claims 1 to 5, comprising the steps of: Mixing a silicon-containing material, a polymer material and a first organic solvent to obtain mixed slurry, and then spray-drying the mixed slurry to obtain the silicon-based anode material.
7. The preparation method according to claim 6, wherein the temperature of the mixing is 30 ℃ to 100 ℃ for 5 hours to 10 hours; preferably, the inlet temperature of the spray drying is 100-200 ℃, and the outlet temperature is 60-100 ℃.
8. The method of manufacturing according to claim 6 or 7, characterized in that the method of manufacturing the polymer material comprises: Mixing a monomer of a polymer material, a second organic solvent and an initiator, performing polymerization reaction to obtain a polymer solution, adding the polymer solution into a precipitation solvent, and then standing, washing and drying to obtain the polymer material; Preferably, the temperature of the polymerization reaction is 60-110 ℃ and the time is 4-9 hours; Preferably, the standing time is 2-4 hours; preferably, in the mixed solution obtained by mixing the monomer of the polymer material, the second organic solvent and the initiator, the concentration of the monomer of the polymer material is 0.5 mol/L-2.0 mol/L; Preferably, the addition amount of the initiator is 0.1-0.8 wt% of the monomer mass of the polymer material; Preferably, the initiator comprises any one or a combination of at least two of azobisisobutyronitrile, azobisisoheptonitrile, or dibenzoyl peroxide; preferably, the first organic solvent and the second organic solvent each independently comprise any one or a combination of at least two of benzene, toluene, NMP or DMF; Preferably, the precipitation solvent includes any one or a combination of at least two of propanol, isopropanol or acetone.
9. A battery comprising a silicon-based anode material according to any one of claims 1-5.
10. The battery of claim 9, wherein the electrolyte of the battery comprises a lithium salt additive, a phosphate additive, and a low impedance additive; preferably, the lithium salt additive comprises LiFSI; Preferably, the phosphate additives include tris (4-nitrophenyl) phosphate; preferably, the low impedance additive comprises LiBOB; Preferably, in the electrolyte of the battery, the content of the lithium salt additive is 2-4 wt%; preferably, in the electrolyte of the battery, the content of the phosphate additive is 0.5-1.5 wt%; preferably, the content of the low-impedance additive in the electrolyte of the battery is 0.2-0.5 wt%.

Description

Silicon-based anode material, preparation method thereof and battery Technical Field The invention belongs to the technical field of batteries, and relates to a silicon-based anode material, a preparation method thereof and a battery. Background At present, graphite materials are main materials used for the negative electrode of a lithium ion battery, the theoretical specific capacity of the commercialized graphite negative electrode materials at the present stage is lower, and in order to further improve the energy density of the battery, searching for negative electrode materials with higher specific capacity becomes a research key point. The silicon-based negative electrode material mainly comprises silicon materials and graphite, has high theoretical specific capacity, good safety, abundant reserves and low cost, can provide channels for lithium ion intercalation and deintercalation from all directions, has excellent quick charge performance, and is the negative electrode material of the next generation lithium ion battery with the most potential. However, the silicon-based anode material has obvious defects that the silicon-based anode material still has obvious volume change in the charge and discharge process, particles are pulverized, and the SEI film is repeatedly broken and regenerated, so that active lithium and electrolyte are continuously consumed, and the cycle life of the battery is greatly reduced. In the prior art, the performance of the silicon-based anode material is improved by coating an artificial SEI film, but the existing artificial SEI film has the problems of poor coating uniformity, easiness in oxidation of the silicon surface at high temperature, insufficient conductivity, unbalance of mechanical support and ion conduction and the like, and is difficult to adapt to the application requirements in a high-temperature environment. Based on the above research, it is necessary to provide a silicon-based anode material, which can comprehensively improve the performance defects of the silicon material and adapt to the application requirements in a high-temperature environment. Disclosure of Invention The invention aims to provide a silicon-based negative electrode material, a preparation method thereof and a battery, wherein an artificial SEI film of the silicon-based negative electrode material is a specific polymer containing various functional groups, so that the high-temperature stability, the conductivity, the quick charge capacity, the structural stability and the like of the silicon-containing material are improved simultaneously, the performance defect of the silicon-containing material is comprehensively improved, and the high-temperature application requirement of the battery is especially met. In order to achieve the aim of the invention, the invention adopts the following technical scheme: in a first aspect, the invention provides a silicon-based anode material, which comprises an inner core and an artificial SEI film coated on the surface of the inner core, wherein the inner core comprises a silicon-containing material, and the artificial SEI film comprises a polymer material; the structural formula of the monomer of the polymer material is shown as formula I): ; Formula I); Wherein at least two of R 1、R2 and R 3 contain a trihalomethyl group and at least one contains a furan ring. The invention adopts triazine polymer containing various functional groups as an artificial SEI film, wherein a furan ring in a polymer material is positioned on a molecular chain side chain and forms a conjugated structure with the triazine ring, the conductivity of the artificial SEI film is greatly improved, the defect of inherent low conductivity of a silicon-based material is improved, a lithium ion transmission path is optimized, the quick charge performance is improved, meanwhile, the rigid structure of the furan ring can improve the mechanical strength of the artificial SEI film, inhibit the breakage of a silicon-containing material, and the furan ring has good compatibility with electrolyte, the interfacial stability of a battery in a high-temperature environment can be further improved, the limitation of insufficient high-temperature performance of the existing triazine material is broken, the interfacial stability of the silicon-containing material is improved, the triazine ring in the polymer material is used as a molecular chain core skeleton, good rigidity and chemical stability are provided, a conjugated system is formed with the furan ring, the electronic transmission path is further optimized, the charge transfer resistance is reduced, the polymer material also contains trihalomethyl groups, each repeating unit contains two trihalomethyl groups, the trihalomethyl groups can release halogen elements to form a passivation layer at high temperature, inhibit the silicon-containing element from forming a passivation layer, inhibit the surface oxidation of the silicon-containing materi