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CN-116470014-B - Negative electrode active material, preparation method thereof, secondary battery and electric equipment

CN116470014BCN 116470014 BCN116470014 BCN 116470014BCN-116470014-B

Abstract

The invention belongs to the technical field of negative electrode materials, and particularly relates to a negative electrode active material, a preparation method thereof, a secondary battery and electric equipment. The negative electrode active material provided by the invention comprises the silicon-based material at least part of which is provided with the carbon layer on the surface and the titanium-containing compound layer which is arranged on the surface of the carbon layer and contains nitrogen, and the titanium-containing compound layer which contains nitrogen enables the negative electrode active material to have better conductivity and lithium ion transmission speed than those of pure titanium-containing compounds, so that a lithium ion battery adopting the negative electrode active material has better electrochemical performance.

Inventors

  • CHEN PENG
  • ZHANG ZIDONG
  • CHU CHUNBO

Assignees

  • 欣旺达电动汽车电池有限公司

Dates

Publication Date
20260508
Application Date
20230222

Claims (9)

  1. 1. The negative electrode active material is characterized by comprising a silicon-based material and a carbon layer arranged on at least part of the surface of the silicon-based material, wherein a titanium-containing compound layer is arranged on the surface of the carbon layer, and the titanium-containing compound layer contains nitrogen; Characteristic peaks exist at g=2.002-2.004 in the electron paramagnetic resonance spectrum of the negative electrode active material.
  2. 2. The anode active material according to claim 1, wherein the content of nitrogen element is 0.13% to 3.5% based on the total mass of the anode active material.
  3. 3. The anode active material according to any one of claims 1 to 2, wherein the raman spectrum of the anode active material has an I D /I G value in the range of 0.96 to 1.2, wherein I D represents the intensity of a peak having a raman shift in the vicinity of 1300±50cm -1 , and I G represents the peak intensity of a raman shift of 1480±50cm -1 .
  4. 4. A method for preparing a negative electrode active material, comprising the steps of: s1, dispersing a silicon-based material with at least part of the surface containing a carbon layer in a solvent, adding a surfactant, adding ammonia water under stirring, and keeping stirring; s2, adding a titanium source, maintaining stirring, performing solid-liquid separation, cleaning, drying and roasting to obtain a solid product with the surface coated with the titanium compound layer; And S3, carrying out first plasma enhanced chemical vapor deposition treatment on the solid product coated with the titanium compound layer on the surface of the solid product at room temperature under the condition of introducing argon for 20-30 min, and then carrying out second plasma enhanced chemical vapor deposition treatment under the condition of introducing mixed gas of nitrogen and hydrogen for 20-30 min to obtain the anode active material.
  5. 5. The method for preparing a negative electrode active material according to claim 4, wherein the power of the first plasma-enhanced chemical vapor deposition treatment is 250 to 400w.
  6. 6. The method for preparing a negative electrode active material according to claim 4, wherein the power of the second plasma-enhanced chemical vapor deposition treatment is 200 to 400w.
  7. 7. The method for preparing a negative electrode active material according to claim 4, wherein the flow ratio of nitrogen gas to hydrogen gas introduced during the second plasma-enhanced chemical vapor deposition treatment is (15-23): 5-13.
  8. 8. A lithium ion battery, comprising a negative electrode sheet, wherein the negative electrode sheet comprises a current collector and a negative electrode active material layer arranged on the surface of the current collector, and the negative electrode active material layer comprises the negative electrode active material according to any one of claims 1 to 4 or the negative electrode active material prepared by the preparation method according to any one of claims 5 to 7.
  9. 9. A powered device comprising the lithium-ion battery of claim 8.

Description

Negative electrode active material, preparation method thereof, secondary battery and electric equipment Technical Field The invention belongs to the technical field of negative electrode materials, and particularly relates to a negative electrode active material, a preparation method thereof, a secondary battery and electric equipment. Background The theoretical capacity of the traditional graphite cathode is only 372mAh g -1, and the application development of a lithium battery is severely limited. The theoretical capacity of silicon is as high as 3579mAh g -1 which is ten times that of industrial graphite, so that the silicon becomes one of the most promising cathode materials and has wide application prospect. However, silicon has poor conductivity and large volume change (300 percent) in the processes of lithium intercalation and lithium deintercalation, and is easy to pulverize an electrode, so that the electrical contact between an active substance and a current collector is gradually lost. In addition, due to powdering of the active particles, the surface is easily exposed and Solid Electrolyte Interfaces (SEI) are repeatedly formed, resulting in rapid consumption of electrolyte. These problems directly result in poor cycle performance and rate performance of the silicon-based anode material. The micro-nano structure design provides an effective method for solving the problem of volume expansion of the silicon-based material. Current work in micro-nanostructure design mainly involves the creation of special silicon nanostructures and the creation of silicon doped composite structures. Such as nanoporous silicon, core-shell structures, etc. In addition, the volume expansion of silicon can also be regulated by secondary protective materials such as carbon, niO, tiO 2, and the like. The volume change of the titanium oxide is minimum (4 percent), and the titanium oxide has good mechanical stability in the lithium intercalation and deintercalation process, and is an ideal material for constructing a stable silicon anode. However, titanium oxide itself is poor in conductivity, limiting its use in silicon anode protection materials. Disclosure of Invention Therefore, the technical problem to be solved by the application is to overcome the defects that the electrical property of the existing titanium oxide coated silicon-based material is limited to be improved, the modification needs to be carried out at high temperature, the electrochemical property of the silicon-based material is influenced, the energy consumption is high and the like, so that the negative electrode active material, the preparation method thereof, the secondary battery and the electric equipment are provided. Therefore, the application provides the following technical scheme: The first aspect of the application provides a negative electrode active material, which comprises a silicon-based material and a carbon layer arranged on at least part of the surface of the silicon-based material, wherein a titanium-containing compound layer is arranged on the surface of the carbon layer, and the titanium-containing compound layer contains nitrogen. Optionally, the content of nitrogen element accounts for 0.13% -3.5% based on the total mass of the anode active material. Optionally, the raman spectrum of the negative electrode active material has an I D/IG value ranging from 0.96 to 1.2, wherein I D represents the intensity of a peak with a raman shift near 1300±50cm -1, and I G represents the intensity of a peak with a raman shift near 1480±50cm -1. Optionally, a characteristic peak exists at g=2.002-2.004 in the electron paramagnetic resonance spectrum of the negative electrode active material. Optionally, the titanium-containing compound comprises titanium oxide. A second aspect of the present application provides a method for preparing a negative active material, comprising the steps of: s1, dispersing a silicon-based material with at least part of the surface containing a carbon layer in a solvent, adding a surfactant, adding ammonia water under stirring, and keeping stirring; s2, adding a titanium source, maintaining stirring, performing solid-liquid separation, cleaning, drying and roasting to obtain a solid product with the surface coated with the titanium compound layer; and S3, carrying out first plasma enhanced chemical vapor deposition treatment on the solid product coated with the titanium compound layer on the surface under the condition of introducing argon at room temperature, and then carrying out second plasma enhanced chemical vapor deposition treatment on the solid product under the condition of introducing mixed gas of nitrogen and hydrogen to obtain the anode active material. Optionally, the power of the first plasma enhanced chemical vapor deposition treatment is 250-400W, and the time is 10-50 min. Optionally, the power of the second plasma enhanced chemical vapor deposition treatment is 200-400W, and the time is 10-50 min.