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CN-121983663-A - Method for preparing self-repairing disulfide bond-polysiloxane gel electrolyte by in-situ polymerization method at room temperature

CN121983663ACN 121983663 ACN121983663 ACN 121983663ACN-121983663-A

Abstract

The invention belongs to the technical field of lithium ion batteries, and discloses a method for preparing a self-repairing disulfide bond-polysiloxane gel electrolyte by an in-situ polymerization method at room temperature and application thereof. The gel electrolyte is composed of siloxane monomers, diamine monomers, carbon disulfide, lithium salt, solvents and initiators, wherein the cyclic siloxane monomers contain Si-O bond components, the gel electrolyte prepared by the invention can be completely polymerized at room temperature, and the gel electrolyte has certain self-repairing capability by utilizing the property of dynamic crosslinking of the dithiocarbamic acid ester generated by carbon disulfide and amine in situ through a hydrogen bond-disulfide bond network. The siloxane provides a rigid backbone that imparts flame retardant properties to the gel electrolyte. In addition, the gel electrolyte based on in-situ polymerization has better matching property with common anode materials such as LiNi 0.8 Co 0.1 Mn 0.1 O 2 , liFePO 4 and the like, and the assembled button cell shows excellent electrochemical performance.

Inventors

  • DING ZHENGPING
  • ZHANG YI
  • ZHU SHUANG
  • LIU XIAOYU
  • REN YURONG

Assignees

  • 常州大学

Dates

Publication Date
20260505
Application Date
20260228

Claims (10)

  1. 1. A method for preparing a self-repairing disulfide bond-polysiloxane gel electrolyte by an in-situ polymerization method at room temperature, which is characterized by comprising the following steps: (1) Adding siloxane monomers and diamine monomers into an organic solvent, adding carbon disulfide, and stirring to obtain uniform and transparent liquid A, wherein the siloxane monomers contain Si-O bonds and can undergo ring-opening reaction; (2) Adding lithium salt and an initiator into the uniform and transparent liquid A to obtain a gel electrolyte precursor solution, namely liquid B; (3) And (3) placing the liquid B in room temperature or heating condition to perform in-situ polymerization reaction for a certain time, and performing in-situ polymerization to form the self-repairing disulfide bond-polysiloxane gel electrolyte.
  2. 2. The method for preparing a self-repairing disulfide-polysiloxane gel electrolyte as claimed in claim 1, wherein the siloxane monomer is selected from cyclic siloxane or linear siloxane with epoxy group, and the diamine monomer is selected from aliphatic diamine, alicyclic diamine or aromatic diamine.
  3. 3. The method for preparing the self-repairing disulfide-polysiloxane gel electrolyte by the in-situ polymerization method at room temperature as claimed in claim 2, wherein the siloxane monomer structure is one of the following: 。
  4. 4. The method for preparing the self-repairing disulfide-polysiloxane gel electrolyte by the in-situ polymerization method at room temperature as claimed in claim 2, wherein the amine monomer is one of the following: 。
  5. 5. The method for preparing the self-repairing disulfide-polysiloxane gel electrolyte by the in-situ polymerization method at room temperature as claimed in claim 1, wherein the addition amount of the carbon disulfide is such that the concentration of the carbon disulfide in the solution B is 0.1 mol/L-0.3 mol/L; and/or the molar ratio of the siloxane monomer to the diamine monomer is 1:1; And/or the total mass of the siloxane monomer and the diamine monomer accounts for 10-30% of the total mass of the gel electrolyte precursor solution.
  6. 6. The method for preparing a self-repairing disulfide-polysiloxane gel electrolyte as claimed in claim 1, wherein in the step (3), the time of room temperature in situ polymerization is 0.2 to 24 hours or 0.5 to 50 h at 45 ℃.
  7. 7. The method for preparing a self-repairing disulfide-polysiloxane gel electrolyte by in-situ polymerization at room temperature as claimed in claim 1, wherein the solvent is one or a mixture of DEC, EMC, DME, EC, DMC, diethylene glycol dimethyl ether (DME) and tetraethylene glycol dimethyl ether (TEGDME).
  8. 8. The method for preparing the self-repairing disulfide bond-polysiloxane gel electrolyte by using the room temperature in-situ polymerization method as claimed in claim 1, wherein the lithium salt is selected from one or a mixture of more of lithium bis (trifluoromethanesulfonyl imide) (LiTFSI), lithium bis (fluorosulfonyl imide) (LiLiFSI), lithium difluoro (oxalato) borate (LiDFOB) and lithium tetrafluoroborate (LiBF 4), and the concentration of the lithium salt is 0.02-5 mol/L; The initiator is LiBF 4 or lithium difluorooxalato borate (LiDFOB), wherein the concentration of LiBF 4 is 0.01-0.08 mol/L, and the concentration of LiDFOB is 0.5-3 mol/L.
  9. 9. A self-healing disulfide-polysiloxane gel electrolyte prepared according to any one of claims 1 to 8, wherein the gel electrolyte has a dual dynamic network structure composed of dynamic disulfide bonds formed by dithiocarbamate groups and hydrogen bonds formed by polysiloxane segments.
  10. 10. A lithium ion battery comprising a positive electrode, a negative electrode, a separator and an electrolyte, wherein the electrolyte is the self-repairing disulfide-polysiloxane gel electrolyte according to claim 8, and the gel electrolyte is formed by injecting the precursor solution B according to claim 1 into a battery case loaded with the separator and polymerizing in situ between the positive electrode and the negative electrode.

Description

Method for preparing self-repairing disulfide bond-polysiloxane gel electrolyte by in-situ polymerization method at room temperature Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a preparation method of a green self-repairing disulfide bond-polysiloxane gel electrolyte which is self-polymerized at room temperature. Technical Field The traditional liquid electrolyte and the lithium metal cathode have poor stability in the circulating process, lithium dendrites are easy to generate, so that the problems of diaphragm puncture, electrolyte leakage, battery thermal runaway and the like are caused. In addition, the gel electrolyte has certain mechanical strength and flexibility, can prevent puncture of lithium dendrite and can be applied to the field of flexible electronics. The gel electrolyte prepared by the prior art, such as CN202411733131.0, has the common problems of slower polymerization speed and insufficient polymerization kinetics. The long-time curing reaction is difficult to be suitable for mass production of lithium ion batteries. For example, CN201911096963.5 discloses a dual-function self-healing polymer electrolyte which reacts with polyethylene glycol with double bonds by introducing a crosslinking agent with both intrinsic disulfide bonds and hydrogen bonds, CN202510138054.2 discloses a self-healing polymer electrolyte which introduces preformed disulfide bonds into a polymer network by utilizing the point-striking reaction of carbon-carbon double bonds in disulfide diacrylate monomers with thiol crosslinking agents. In addition, in the prior art, sulfur-containing small molecules such as cystamine, 2-aminophenyl disulfide, bis (2-hydroxyethyl) disulfide and the like are also commonly used as monomers to prepare dynamic networks in polyurethane or epoxy systems. The prior art mainly contains disulfide bond preformed monomers (such as disulfide diacrylate, bis-Boc-cystamine and the like). Such monomers are often complex in synthetic routes, costly, and have poor solubility of partially rigid sulfur-containing monomers in electrolyte solvents, making it difficult to obtain a uniform precursor solution. To solve the above problems, researchers of the present invention have attempted to introduce dynamic covalent bonds (such as disulfide bonds) into polymer electrolytes to impart self-healing capabilities to materials. The sulfur atoms in the dithiocarbamic acid ester compound generated by introducing carbon disulfide have higher reactivity, and network reconstruction and crack repair can be realized through C-S bond cleavage recombination. As a compound containing Si-O bonds, the polysiloxane has high Si-O bond energy and better chemical stability. The Si-O bond molecular chain has certain flexibility and can improve the interface contact problem between the electrolyte and the electrode. At present, no report is known about the combination of dithiocarbamic acid ester and polysiloxane, and the self-repairing gel electrolyte is prepared by using the polymerization acceleration characteristic of the dithiocarbamic acid ester through a room temperature in-situ polymerization method. Aiming at the defects of the prior art, the invention develops a polysiloxane gel electrolyte taking a dithiocarbamic acid ester group as a core. Can be polymerized rapidly and uniformly at room temperature, and has excellent self-repairing performance, ion conductivity, mechanical performance and certain flame retardant property. Aiming at the technical scheme that sulfur-containing small molecules such as cystamine, 2-aminophenyl disulfide, bis (2-hydroxyethyl) disulfide and the like are adopted in the prior art, and the self-repairing is realized by constructing dynamic disulfide bond-hydrogen bond in polyurethane, epoxy, polysiloxane and other systems, one of the core differences of the invention is that the source of disulfide bond is different, and the invention selects carbon disulfide (CS 2) as a synthetic raw material, mainly considers the economical efficiency of carbon disulfide and has high reaction conversion efficiency. The dithiocarbamic acid ester compound synthesized by taking carbon disulfide as raw material can be carried out at room temperature under the condition of no catalyst, thereby avoiding the damage of high temperature and the catalyst to the battery performance. The disulfide bonds of the present invention are not derived from the feedstock itself, but rather form dithiocarbamates by the reaction of carbon disulfide with an amine. The two dithiocarbamic acid ester molecules can generate sulfur-sulfur exchange reaction through sulfur atoms in functional groups of the dithiocarbamic acid ester molecules to form stable disulfide bonds, thereby realizing self-repairing of gel. The invention avoids the defects of higher cost, poor solubility, insufficient compatibility with electrolyte and the like of the existing sulfur-containing micromole