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CN-121983524-A - Pre-lithiated silicon carbon material and preparation method thereof, negative electrode, secondary battery and power utilization device

CN121983524ACN 121983524 ACN121983524 ACN 121983524ACN-121983524-A

Abstract

The invention discloses a pre-lithiated silicon carbon material and a preparation method thereof, a negative electrode, a secondary battery and an electric device, wherein lithium elements in the silicon carbon material are uniformly distributed on the pore surfaces of porous carbon microspheres and in the carbon skeleton of the porous carbon microspheres, so that uniform reaction of the lithium elements and electrolyte in each region of the negative electrode is ensured, an SEI film with moderate, compact and stable thickness is formed, irreversible capacity loss is accurately compensated, the first coulomb efficiency of the battery is effectively improved, and the problems that lithium metal is separated out and dendrite risk are locally caused by uneven lithium distribution and irreversible capacity loss in partial regions cannot be sufficiently compensated, so that the first coulomb efficiency is low are avoided.

Inventors

  • WANG XUEYIN
  • CHENG XIANGNAN
  • LIU ZHAOBO
  • XIE YAOYI
  • XU CHAQING

Assignees

  • 比亚迪股份有限公司

Dates

Publication Date
20260505
Application Date
20250826

Claims (15)

  1. 1. A prelithiated silicon carbon material, comprising: A pre-lithiated porous carbon microsphere comprising a porous carbon microsphere and lithium elements, wherein the interior of the porous carbon microsphere has a pore structure, the lithium elements are distributed on the pore surface of the porous carbon microsphere and in the carbon skeleton of the porous carbon microsphere, and Silicon particles deposited within the pores of the prelithiated porous carbon microspheres.
  2. 2. The prelithiated silicon-carbon material of claim 1, wherein the mass ratio of lithium element is 1% -15% based on the total mass of the prelithiated silicon-carbon material.
  3. 3. The prelithiated silicon-carbon material according to claim 1 or 2, characterized in that the mass ratio of silicon particles is 10% -80% based on the total mass of the prelithiated silicon-carbon material.
  4. 4. The prelithiated silicon-carbon material of claim 1 or 2, characterized in that the specific surface area of the prelithiated silicon-carbon material is 1m 2 /g-600m 2 /g.
  5. 5. A method of preparing the prelithiated silicon-carbon material of any one of claims 1-4, comprising the steps of: Dissolving a pre-lithiation reagent, a phenol source and an aldehyde source in a solvent to obtain a mixed solution, and heating the mixed solution for reaction to obtain pre-lithiated phenolic resin balls; carbonizing the pre-lithiated phenolic resin spheres in the presence of a pore-forming agent to obtain pre-lithiated porous carbon microspheres; And depositing silicon particles in the holes of the pre-lithiated porous carbon microspheres to obtain the pre-lithiated silicon carbon material.
  6. 6. The method of claim 5, wherein the molar ratio of aldehyde source to phenol source is from 0.5 to 25; the solid content of the mixed solution is 3-20wt%; the heating temperature is 40-120 ℃ and the heating time is 6-48 h.
  7. 7. The method according to claim 5 or 6, wherein the pre-lithiation agent, the phenol source, the aldehyde source and the catalyst are dissolved together in the solvent to obtain a mixed solution; optionally, the catalyst comprises at least one of sodium hydroxide, lithium hydroxide, ammonia water, hexamethylenetetramine, N- (2-aminoethyl) ethanolamine, N- (2-aminoethyl) propanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, and hexamine.
  8. 8. The method of claim 5 or 6, wherein the pre-lithiation agent comprises at least one of organolithium, inorganic lithium; optionally, the organic lithium comprises a complex of lithium and an aromatic compound, wherein the aromatic compound is at least one selected from benzene, biphenyl, dimethylbiphenyl, benzopyrene, benzanthracene, naphthalene, anthracene and Phil; optionally, the inorganic lithium comprises at least one of elemental lithium, lithium carbonate, and lithium hydroxide; the dosage of the pre-lithiation reagent is 0.5% -25% of the total mass of the phenol source and the aldehyde source.
  9. 9. The method according to claim 5 or 6, wherein the prelithiation reagent, the phenol source, the aldehyde source and the celluloses are dissolved together in the solvent to obtain a mixed solution, or And dissolving the prelithiation reagent, the phenol source, the aldehyde source and the surfactant together in the solvent to obtain a mixed solution.
  10. 10. The method of claim 5 or 6, wherein the phenol source comprises at least one of bisphenol a, resorcinol, hydroquinone, catechol, phenol, phloroglucinol, o-aminophenol, m-aminophenol, p-aminophenol; The aldehyde source comprises at least one of formaldehyde, paraformaldehyde, hexamethylenetetramine, benzaldehyde, acetaldehyde, hydroxybenzaldehyde, terephthalaldehyde and furfural; The solvent comprises at least one of water, ethanol, methanol, butanol, tetrahydrofuran, N-dimethylformamide, 2-methyltetrahydrofuran, diethylene glycol dimethyl ether and methyl tertiary butyl ether.
  11. 11. The method of claim 5 or 6, wherein the pore-former comprises at least one of nitrogen and carbon dioxide; the carbonization temperature is 400-1200 ℃.
  12. 12. A negative electrode comprising the prelithiated silicon-carbon material of any one of claims 1-4 or obtained by the method of any one of claims 5-11.
  13. 13. A secondary battery comprising the negative electrode of claim 12.
  14. 14. The secondary battery according to claim 13, wherein the secondary battery comprises a solid-state battery.
  15. 15. An electric device comprising the secondary battery according to claim 13 or 14.

Description

Pre-lithiated silicon carbon material and preparation method thereof, negative electrode, secondary battery and power utilization device Technical Field The invention relates to the technical field of batteries, in particular to a pre-lithiated silicon-carbon material and a preparation method thereof, a negative electrode, a secondary battery and an electric device. Background The silicon-based material has the advantages of high specific capacity (theoretical value 4200 mAh/g), rich reserve and the like when being used as a lithium ion battery cathode material, however, the silicon-based material can cause that part of lithiated Li x Si is separated from the whole electrode and can not be subjected to delithiation reaction due to serious volume expansion and shrinkage in the lithiation and delithiation processes of the battery, so that larger capacity loss is caused, and the first coulombic efficiency of the battery is seriously reduced. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, an object of the present invention is to provide a prelithiated silicon-carbon material that is capable of effectively improving the first coulombic efficiency of a battery. Specifically, a first aspect of the present invention provides a prelithiated silicon-carbon material comprising: A pre-lithiated porous carbon microsphere comprising a porous carbon microsphere and lithium elements, wherein the interior of the porous carbon microsphere has a pore structure, the lithium elements are distributed on the pore surface of the porous carbon microsphere and in the carbon skeleton of the porous carbon microsphere, and Silicon particles deposited within the pores of the prelithiated porous carbon microspheres. According to the invention, lithium is pre-supplemented on the phenolic resin balls through an in-situ pre-lithiation process to form a lithium library, and then the pre-lithiated silicon-carbon material is formed through carbonization and silicon deposition, so that lithium elements are uniformly distributed in the silicon-carbon material, namely, lithium elements are not only distributed on the pore surfaces of the porous carbon microspheres, but also distributed in the carbon skeleton of the porous carbon microspheres. The uniform distribution of the pre-supplemented lithium elements can ensure that the lithium elements uniformly react with the electrolyte in each region of the negative electrode to form an SEI film with moderate thickness, compactness and stability, and the irreversible capacity loss is accurately compensated, so that the first coulomb efficiency of the battery is effectively improved, and the problems that the lithium metal is separated out and dendrite risks are locally caused by uneven distribution of the lithium, and the irreversible capacity loss in partial regions cannot be fully compensated, so that the first coulomb efficiency is low are avoided. According to some embodiments of the invention, the mass ratio of lithium element is 1% -15% based on the total mass of the prelithiated silicon carbon material. According to some embodiments of the invention, the mass fraction of silicon particles is 10% -80% based on the total mass of the prelithiated silicon-carbon material. According to some embodiments of the invention, the pre-lithiated silicon carbon material has a specific surface area of 1m 2/g-600m2/g. In a second aspect, the present invention provides a method of preparing the prelithiated silicon-carbon material of the first aspect of the invention, comprising the steps of: Dissolving a pre-lithiation reagent, a phenol source and an aldehyde source in a solvent to obtain a mixed solution, and heating the mixed solution for reaction to obtain pre-lithiated phenolic resin balls; carbonizing the pre-lithiated phenolic resin spheres in the presence of a pore-forming agent to obtain pre-lithiated porous carbon microspheres; And depositing silicon particles in the holes of the pre-lithiated porous carbon microspheres to obtain the pre-lithiated silicon carbon material. Conventional prelithiation of silicon-carbon materials is typically performed by first preparing porous carbon, then calcining the prelithiation reagent with the porous carbon, and finally depositing silicon. The method directly inputs the pre-lithiation reagent into the raw material, so that the porous carbon and the pre-lithiation treatment are synchronously carried out, and compared with the traditional pre-lithiation treatment method, the method has the advantages of uniform lithium distribution of the silicon-carbon material, simple synthesis procedure, low energy consumption, low production cost, convenient popularization and utilization and contribution to industrialized development. According to some embodiments of the invention, the molar ratio of the aldehyde source to the phenol source is 0.5-25, the solid content of the mixed