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CN-121983541-A - Silicon-based material with self-adaptive coating layer, preparation method of silicon-based material and lithium battery

CN121983541ACN 121983541 ACN121983541 ACN 121983541ACN-121983541-A

Abstract

The application provides a silicon-based material with a self-adaptive coating layer, a preparation method thereof and a lithium battery, and relates to the field of lithium ion battery preparation. The application provides a preparation method of a silicon-based material with a self-adaptive coating layer, and the material is successfully applied to a sulfide-based all-solid-state battery, wherein a PEGDGE (polyethylene glycol terephthalate) base coating layer is constructed on the surface of the silicon-based material by a liquid phase method, and a reversible disulfide bond is introduced into the PEGDGE base coating layer, so that the preparation method adapts to volume fluctuation of a silicon-based negative electrode in a circulating process, adapts to volume expansion and contraction of the silicon-based material in the circulating process, maintains the integrity of the coating layer, and avoids interface side reaction with sulfide solid electrolyte; and further, the polymer chain is crosslinked and cured through an amino curing agent, so that the mechanical strength of the coating layer is enhanced, the cracking of the coating layer is inhibited, and the cycle life is prolonged.

Inventors

  • YE KEFEN
  • ZHANG XIAOZHU
  • CHEN WEI
  • ZHU DANFENG
  • CHEN SHUIMIN

Assignees

  • 万向一二三股份公司

Dates

Publication Date
20260505
Application Date
20260127

Claims (10)

  1. 1. The silicon-based material with the self-adaptive coating layer is characterized by having a core-shell structure and comprising the silicon-based material and the self-adaptive coating layer coated on the surface of the silicon-based material; The silicon-based material is one of vapor deposition silicon carbon, sand grinding silicon carbon, silica, porous silicon, micron silicon and nano silicon; The self-adaptive coating layer comprises a polyethylene glycol diglycidyl ether structure, an R-S-S-R structure, a curing agent structure and lithium salt, wherein the lithium salt is distributed in a network of a high polymer formed by the polyethylene glycol diglycidyl ether structure, the R-S-S-R structure and the curing agent structure; The curing agent structure is derived from a curing agent, and the curing agent is an organic matter with at least two primary amino groups and a relative molecular weight of less than 800, and the R-S-S-R structure is derived from a disulfide bond chain extender; The polyethylene glycol diglycidyl ether structure is derived from polyethylene glycol diglycidyl ether; wherein R-is an organic group containing an amino group.
  2. 2. The silicon-based material with the adaptive coating layer according to claim 1, wherein the molar ratio of the R-S-S-R structure to the polyethylene glycol diglycidyl ether structure is 100:25-75, the molar ratio of the curing agent structure to the polyethylene glycol diglycidyl ether structure is 5-20:100, and the mass of the lithium salt is 20-50 wt% of the mass of the polyethylene glycol diglycidyl ether.
  3. 3. The silica-based material with an adaptive coating according to claim 1 or 2, wherein the lithium salt comprises one or a combination of two or more of LiTFSI, liFSI, liPF 6 and LiBOB, and the curing agent comprises one or a combination of two or more of hexamethylenediamine, diethylenetriamine, triethylenetetramine, m-xylylenediamine and diaminodiphenylmethane.
  4. 4. A silicon-based material with an adaptive cladding layer according to claim 3, wherein R in said R-S-R structure is any one or a combination of several of 2-aminoethyl, 4-aminophenyl and 2-aminophenyl.
  5. 5. The silica-based material with adaptive coating according to any one of claims 1-2 and 4, wherein the polyethylene glycol diglycidyl ether has a relative molecular mass of 3000-30000.
  6. 6. The silica-based material with adaptive cladding according to claim 5, wherein said polyethylene glycol diglycidyl ether has a relative molecular mass of 4000-20000.
  7. 7. The silicon-based material with adaptive cladding according to any one of claims 1-2, 4, 6, wherein the silicon-based material is any one of vapor deposited silicon carbon, sanded silicon carbon, silica, porous silicon, micro-silicon, and nano-silicon, and the D50 of the silicon-based material is 20 nm-20 μm.
  8. 8. The silicon-based material with adaptive cladding according to claim 7, wherein the adaptive cladding has a thickness of 2-50 nm.
  9. 9. A method of preparing a silicon-based material having an adaptive cladding layer according to any one of claims 1-8, comprising the steps of: s1, dissolving linear polyethylene glycol diglycidyl ether in an organic solvent in an inert atmosphere, heating and stirring, then dropwise adding a disulfide bond chain extender, and performing a graft chain extension reaction to obtain a solution A; s2, adding a silicon-based material and lithium salt into the solution A, stirring, slowly adding a curing agent, and heating for reaction to obtain a suspension B; And S3, transferring the powder product obtained after the suspension is dried into a tube furnace, and heating and curing under inert atmosphere to obtain the silicon-based material with the self-adaptive coating layer.
  10. 10. A lithium battery comprising a silicon-based material with an adaptive coating according to any one of claims 1-8.

Description

Silicon-based material with self-adaptive coating layer, preparation method of silicon-based material and lithium battery Technical Field The invention relates to the field of lithium ion battery preparation, in particular to a silicon-based material with a self-adaptive coating layer, a preparation method thereof and a lithium battery. Background Lithium Ion Batteries (LIBs) are currently the mainstream electrochemical energy storage technology, and have been widely used in the fields of 3C electronics, electric automobiles, power grid energy storage and the like. However, existing commercial liquid lithium ion batteries are limited by the flammability of the liquid electrolyte and the theoretical specific capacity of the graphite negative electrode (372 mAh g1) And the like, and the problems such as that, its energy density and safety are difficult meeting the continuously growing demands of the market. In recent years, solid-state batteries based on solid-state electrolytes (such as oxides, sulfides, polymers and the like) are widely focused in academia and industry because of the characteristics of high intrinsic safety, better compatibility with high-energy-density anode materials (such as lithium metal and silicon-based materials) and the like, and the important development direction of breaking through the energy density and safety bottleneck of the existing liquid-state lithium ion batteries. In various solid electrolyte technology routes, sulfide solid electrolytes are developed by virtue of their extremely high room temperature lithium ion conductivity (up toMagnitude), extremely low electronic conductivity, and good mechanical ductility, are considered as one of the most potential material systems to achieve high performance all-solid state batteries. Compared with a lithium metal anode, the silicon-based anode material has remarkable advantages in the aspects of raw material cost, interface stability, processing and manufacturing process compatibility (such as being capable of being compounded with graphite) and the like. In addition, the lithiation potential of the silicon material (about 0.4V vs.) Above the deposition potential of metallic lithium, helps to inhibit lithium dendrite growth and may alleviate interfacial side reactions with sulfide solid state electrolytes. Nevertheless, the practical progress of silicon-based anode materials in solid state battery systems still faces significant challenges. The method is mainly characterized in that the practical capacity is limited, the initial coulombic efficiency is low, and the cycle life is short. The root of these problems is that the inherent electron conductivity and lithium ion diffusion coefficient of the silicon material are low, and severe repeated volume expansion/contraction (> 300%) occurs in the charge and discharge process, so that active substances are pulverized and broken, contact with a conductive network and solid electrolyte particles fails, interface stability is deteriorated, and finally cycle reversibility is poor. Therefore, improving the structural stability, interface compatibility and ion/electron transmission efficiency of the silicon-based anode material in the solid-state battery environment is a key technical problem to be solved in order to promote the practical application of the high-energy-density solid-state battery. Patent CN107240688B discloses a technical scheme for coating a silicon-based anode material with sulfide solid electrolyte by a one-step method, wherein the coating layer relieves the volume expansion of the silicon anode in the charge-discharge process, effectively improves Li ion diffusion, reduces the internal resistance of the battery, and realizes the improvement of the mechanical property and the electrochemical property stability of the silicon. Patent CN115172669B discloses a method for preparing a ceramic material with a sectional sintering structureThe silicon-based anode material of the coating layer has the advantages of uniform and compact coating layer, high lithium ion conductivity and wide voltage window. The multiplying power performance and the long-cycle stability of the silicon-based negative electrode in the sulfide all-solid-state battery are effectively improved. In the prior art, the sulfide solid electrolyte is directly coated on the silicon negative electrode, so that reduction decomposition of the sulfide solid electrolyte at the interface in the circulation process cannot be avoided, an inert lithium sulfide layer is formed, electron/ion transfer is blocked, and the battery performance is fast attenuated. Meanwhile, the silicon anode material is accompanied by huge volume fluctuation in the lithium intercalation and deintercalation process, and repeated expansion and contraction can lead to cracking and pulverization of the coating layer along with the cyclic progress, so that internal active substances are exposed, the SEI layer is continuously thickened, and the in