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CN-117585680-B - Silicon-based active material and preparation and application thereof

CN117585680BCN 117585680 BCN117585680 BCN 117585680BCN-117585680-B

Abstract

The invention belongs to the field of battery materials, and particularly discloses a preparation method of a silicon-based active material, which comprises the steps of carrying out pressure gradient heat treatment on a mixture of silicon oxide, MX n , liX and metal N to obtain a heat treatment material, carrying out acid treatment to obtain a precursor, and then compounding the precursor with a carbon source to carry out carbonization treatment, wherein M is at least one of Al and Zn, N is the valence of M, X is halogen, N is Mg and/Al, the pressure of the pressure gradient heat treatment process is 0.2-2 MPa, and the pressure gradient heat treatment process comprises a first heat preservation process at a temperature of 200-350 ℃ and a second heat preservation process at a temperature of 450-600 ℃. The invention also comprises the silicon-based active material prepared by the preparation method and application thereof. The material provided by the invention has excellent electrochemical performance, and particularly has excellent high-temperature stability.

Inventors

  • FAN HAOYU
  • CHEN SONG
  • ZHOU QIN
  • Shi Dieer

Assignees

  • 湖南宸宇富基新能源科技有限公司

Dates

Publication Date
20260505
Application Date
20231122

Claims (20)

  1. 1. A preparation method of a silicon-based active material is characterized in that a mixture of silicon oxide, MX n , liX and metal N is subjected to pressure gradient heat treatment to obtain a heat treatment material, then an acid treatment is carried out to obtain a precursor, and then the precursor and a carbon source are compounded and carbonized to obtain the silicon-based active material; M is at least one of Al and Zn, N is the valence of M, X is halogen, N is Mg and/Al, and the molar ratio of metal N to silicon oxide is (0.05-0.5): 1; The weight ratio of the silicon oxide to the MX n to the LiX is 1:2-20:1-10; The pressure of the pressurizing gradient heat treatment process is 0.4-0.6 MPa, and the pressurizing gradient heat treatment process comprises a first heat preservation process at the temperature of 200-350 ℃ and a second heat preservation process at the temperature of 450-600 ℃; the pressure gradient heat treatment process adopts protective atmosphere for pressure control.
  2. 2. The method for preparing a silicon-based active material according to claim 1, wherein the chemical formula of the silicon oxide is SiO X , and x is 0< 2.
  3. 3. The method of claim 1, wherein the silicon oxide has a D50 of 3um to 10um.
  4. 4. The method of preparing a silicon-based active material as defined in claim 1, wherein M is Al; X is Cl; The metal N is Mg.
  5. 5. The method of preparing a silicon-based active material as defined in claim 1, wherein the protective atmosphere is at least one of nitrogen and inert gas.
  6. 6. The method of claim 1, wherein the first thermal insulation process is performed at a temperature of 280 ℃ to 320 ℃.
  7. 7. The method for preparing a silicon-based active material as claimed in claim 1, wherein the time of the first heat-retaining process is 2 to 4 hours.
  8. 8. The method for preparing a silicon-based active material according to claim 1, wherein the temperature of the second heat preservation process is 480-520 ℃.
  9. 9. The method for preparing a silicon-based active material according to claim 1, wherein the second heat preservation process is performed for 1 to 4 hours.
  10. 10. The method for preparing a silicon-based active material according to claim 1, wherein the acid solution in the acid treatment process is an inorganic acid solution with a concentration of 0.1-5 m.
  11. 11. The method of claim 10, wherein the acid solution in the acid treatment process is at least one of HCl and HNO 3 、H 2 SO 4 .
  12. 12. The method for preparing a silicon-based active material according to claim 1, wherein the precursor is prepared by washing with water and drying after the acid treatment.
  13. 13. The method of claim 1, wherein the carbon source is at least one of a gaseous carbon source, a liquid carbon source, and a solid carbon source.
  14. 14. The method of preparing a silicon-based active material as defined in claim 1, wherein the carbonization process is performed in a protective atmosphere.
  15. 15. The method for preparing a silicon-based active material as defined in claim 1, wherein the carbonization process is performed at a temperature of 500-1000 ℃.
  16. 16. The method for preparing a silicon-based active material as claimed in claim 1, wherein the carbonization process is performed for 1 to 5 hours.
  17. 17. A silicon-based active material prepared by the preparation method of any one of claims 1 to 16.
  18. 18. Use of a silicon-based active material prepared by the preparation method according to any one of claims 1 to 16 as a negative electrode active material.
  19. 19. Use of a silicon-based active material prepared by a preparation method according to any one of claims 1 to 16 for preparing a lithium ion battery.
  20. 20. The negative electrode of the lithium ion battery comprises a current collector and a negative electrode material compounded on the surface of the current collector, wherein the negative electrode material comprises a negative electrode active material, and the negative electrode active material is characterized by comprising the silicon-based active material prepared by the preparation method of any one of claims 1-16.

Description

Silicon-based active material and preparation and application thereof Technical Field The invention relates to the field of battery materials, in particular to the field of lithium ion battery anode materials. Background The specific capacity (372 mAh/g) of graphite is difficult to meet the requirement of high energy density, and a silicon negative electrode is a new choice. Pure silicon expands greatly (≡300%) during cycling, resulting in poor cell cycling performance. The SiO x material expands relatively low (-150%) and has better cycle performance, but the first effect of SiO x is low (-75%). The prior art also provides solutions to the problems faced by silicon-based materials, mainly by compositing silicon with porous carbon, for example, publication No. CN 116504986a discloses a way to alternately deposit silicon-carbon layers on a porous carbon substrate, which can improve its conductivity and, in addition, can buffer the expansion of silicon. For another example, chinese patent publication No. CN 117038855A also discloses a similar means of vapor deposition of silicon on porous carbon. Although the prior art reports some improved modes of silicon-based materials, the problem of volume expansion of silicon can be solved well, the problem of influencing the first effect of the silicon-based materials and the problem of high-temperature stability are not solved well. Disclosure of Invention In order to overcome the defects in the prior art, the invention provides a preparation method of a silicon-based active material, which aims to inhibit silicon grains in the preparation process and improve the initial effect and the stability at high temperature. The second object of the invention is to provide the silicon-based active material prepared by the preparation method and the application of the silicon-based active material in lithium ion batteries. A third object of the present invention is to provide a lithium ion battery including the silicon-based active material and a negative electrode thereof. A preparation method of silicon-based active material comprises the steps of carrying out pressurizing gradient heat treatment on a mixture of silicon oxide, MX n, liX and metal N to obtain a heat treatment material, carrying out acid treatment to obtain a precursor, and then compounding the precursor with a carbon source to carry out carbonization treatment to obtain the silicon-based active material; m is at least one of Al and Zn, N is the valence of M, X is halogen, and N is Mg and/Al; The pressure of the pressurizing gradient heat treatment process is 0.2-2 MPa, and the pressurizing gradient heat treatment process comprises a first heat preservation process at the temperature of 200-350 ℃ and a second heat preservation process at the temperature of 450-600 ℃. The invention innovatively carries out pressurized gradient heat treatment on the mixture of silicon oxide, MX n, liX and metal N, and based on the combination of MX n, liX, pressurization and two-stage gradient reaction, the invention can accidentally and effectively control the nucleation crystal grains of silicon and induce to form inert active sites in situ, thus being capable of synergistically improving the performance of the prepared material, and particularly being capable of effectively improving the initial effect and the stability at high temperature. In the invention, the combination of the Lewis acid type MX n and LiX is further matched with the pressurizing two-stage heat treatment mode and condition, so that the coordination can be realized unexpectedly, the nucleation behavior of silicon in the reaction process can be regulated and controlled, and the Li silicate type inert active site can be constructed in situ, thereby improving the performance of the Li silicate type inert active site. In the invention, the chemical formula of the silicon oxide is SiO X, and x is more than 0 and less than or equal to 2. In the present invention, the particle size of the silicon oxide is not particularly required, and can meet the battery use requirement, for example, the D50 thereof may be 3um to 10um. According to the invention, silicon oxide, MX n, liX and metal N are adopted for synergistic reaction, based on the physicochemical characteristics of the reaction stage, the reduction nucleation of SiO X can be catalyzed, the grain aggregation is controlled, and in addition, rich inert active sites can be formed in situ, so that the performance of the composite material is synergistically improved. In the invention, M is preferably Al; in the invention, X is halogen such as Cl, br and the like, preferably Cl; In the invention, the metal N is Mg. In the invention, the molar ratio of the metal N to the silicon oxide is (0.05-0.5): 1, and further can be 0.2-0.4:1; The weight ratio of the silicon oxide to the MX n to the LiX is 1:2-20:1-10, and further can be 1:5-10:2-4. According to the invention, under the synergistic combination of the silicon oxi