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CN-122025749-A - Self-supporting high-pressure-resistant flame-retardant solid polymer electrolyte and preparation method and application thereof

CN122025749ACN 122025749 ACN122025749 ACN 122025749ACN-122025749-A

Abstract

The invention discloses a self-supporting high-voltage-resistant flame-retardant solid polymer electrolyte, and a preparation method and application thereof, and belongs to the technical field of solid batteries. The electrolyte comprises polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) polymer, lithium salt, lithium Aluminum Titanium Phosphate (LATP) ceramic powder and trimethyl phosphate (TMP) solvent. The invention can interact with PVDF-HFP based on the abundant Lewis acid sites on the surface of LATP powder, enhance the stability of an electrode/electrolyte interface, improve the high-pressure resistance, greatly improve the thermal safety and nonflammability of the electrolyte by taking TMP as a flame-retardant solvent, and cooperatively improve the ion migration number and the electrochemical stability by compounding lithium difluoro oxalate borate (LiDFOB) and lithium bis (trifluoromethyl) sulfonyl imide (LiTFSI). The solid electrolyte provided by the invention has the advantages of high ionic conductivity, wide electrochemical window, excellent flame retardant property and interface stability, and is suitable for a lithium ion battery with high energy density and high safety.

Inventors

  • YU JING
  • CHEN YEYING
  • LONG JUN
  • HONG ZHIDAN
  • LIANG HAIYI
  • YANG FUJIE

Assignees

  • 仲恺农业工程学院

Dates

Publication Date
20260512
Application Date
20260323

Claims (10)

  1. 1. A self-supporting high-pressure-resistant flame-retardant solid polymer electrolyte is characterized by comprising polyvinylidene fluoride-hexafluoropropylene polymer, lithium salt, lithium aluminum titanium phosphate ceramic powder and trimethyl phosphate solvent as raw materials, wherein the lithium salt is a mixture of lithium difluoro oxalate borate and lithium bis (trifluoromethane sulfonyl) imide.
  2. 2. The self-supporting high pressure resistant flame retardant solid polymer electrolyte of claim 1, wherein the lithium aluminum titanium phosphate ceramic powder is added in an amount of 0.1wt% to 15wt%, based on the mass of the polyvinylidene fluoride-hexafluoropropylene polymer.
  3. 3. The self-supporting high-pressure resistant flame-retardant solid polymer electrolyte according to claim 1, wherein the addition amount of the lithium difluorooxalato borate is 0.01-0.2M and the addition amount of the lithium bistrifluoromethane sulfonyl imide is 0.1-0.8M based on the trimethyl phosphate solvent.
  4. 4. The self-supporting high pressure resistant flame retardant solid polymer electrolyte of claim 1, wherein the ratio of trimethyl phosphate solvent to polyvinylidene fluoride-hexafluoropropylene polymer is 4mL to (0.2-0.6) g.
  5. 5. The self-supporting high pressure resistant flame retardant solid polymer electrolyte of claim 1, wherein the lithium aluminum titanium phosphate ceramic powder has a chemical formula of Li 1+x Al x Ti 2-x (PO 4 ) 3 , wherein 0.2< x <0.5.
  6. 6. A method of preparing a self-supporting high pressure resistant, flame retardant solid polymer electrolyte according to any one of claims 1 to 5, comprising the steps of: mixing polyvinylidene fluoride-hexafluoropropylene polymer, lithium difluorooxalato borate and lithium bistrifluoromethane sulfonyl imide with trimethyl phosphate solvent, and stirring until the mixture is completely dissolved to obtain polymer solution; adding lithium aluminum titanium phosphate ceramic powder into the polymer solution, and stirring to obtain composite slurry; And pouring the composite slurry on a substrate, drying, solidifying and stripping to obtain the self-supporting high-pressure-resistant flame-retardant solid polymer electrolyte.
  7. 7. The method for preparing a self-supporting high pressure resistant flame retardant solid polymer electrolyte according to claim 6, wherein the temperature of the drying and curing is 40 ℃ to 80 ℃ for 6 to 24 hours.
  8. 8. The method for preparing the self-supporting high-pressure resistant and flame-retardant solid polymer electrolyte according to claim 6, wherein the high-pressure resistant and flame-retardant solid polymer electrolyte is in a self-supporting film form and has a thickness of 100-500 μm.
  9. 9. Use of the self-supporting high pressure resistant flame retardant solid polymer electrolyte of any one of claims 1-5 in the preparation of a lithium ion battery.
  10. 10. A lithium ion battery comprising the self-supporting high voltage resistant flame retardant solid polymer electrolyte of any one of claims 1-5.

Description

Self-supporting high-pressure-resistant flame-retardant solid polymer electrolyte and preparation method and application thereof Technical Field The invention belongs to the technical field of solid battery materials, and particularly relates to a self-supporting high-voltage-resistant flame-retardant solid polymer electrolyte, and a preparation method and application thereof. Background Along with the rapid development of electric automobiles and large-scale energy storage, higher requirements are put on the energy density and the safety of lithium ion batteries. Traditional liquid electrolytes are flammable and easy to leak, and have thermal runaway risks. Solid polymer electrolytes are a research hotspot due to their good mechanical properties and safety. The polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) based electrolyte has higher dielectric constant and lower crystallinity, is favorable for dissociation of lithium salt and ion transmission, and still has the problems of low ion conductivity, narrow electrochemical window, unstable interface with a high-voltage positive electrode and the like. In order to improve the comprehensive performance of the solid electrolyte, inorganic ceramic fillers are often introduced to construct the composite electrolyte. Li 1+xAlxTi2-x(PO4)3 (LATP) is a fast ion conductor with a NASICON structure, and has high ion conductivity and good air stability. The research shows that the LATP surface is rich in Lewis acid sites, can interact with a polymer matrix, and optimizes the chain segment arrangement of PVDF & # x2011 and HFP, so that the interface stability and the high pressure resistance are enhanced. In addition, the flame retardant properties of the electrolyte are critical to battery safety. TMP is used as a green flame-retardant solvent, has higher flash point and good thermal stability, and can obviously reduce the flammability of electrolyte. The intrinsic safety of the battery can be improved on the premise of not affecting the electrochemical performance by introducing the electrolyte into a solid electrolyte system. The choice of lithium salt also has a significant impact on the electrolyte performance. LiDFOB has better film forming property and interface stability, and LiTFSI is favorable for improving ion conductivity. The two can synergistically optimize the comprehensive electrochemical performance of the electrolyte. Therefore, the development of a solid polymer electrolyte integrating high ionic conductivity, wide electrochemical window, excellent flame retardance and interface stability has important significance for promoting the practical application of high-safety and high-energy-density solid batteries. Disclosure of Invention The invention provides a self-supporting high-voltage-resistant flame-retardant solid polymer electrolyte, a preparation method and application thereof, and aims to solve the problems of unstable interface and insufficient safety of the existing solid electrolyte under high voltage. In order to achieve the above purpose, the present invention provides the following technical solutions: The invention provides a self-supporting high-pressure-resistant flame-retardant solid polymer electrolyte, which comprises polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) polymer, lithium salt, lithium aluminum titanium phosphate ceramic powder (LATP) and trimethyl phosphate (TMP) solvent as raw materials, wherein the lithium salt is a mixture of lithium difluoro oxalate borate (LiDFOB) and lithium bis (trifluoromethyl) sulfonyl imide (LiTFSI). In the raw materials, the PVDF-HFP polymer is used as an electrolyte matrix, has higher dielectric constant and lower crystallinity, is favorable for dissociation of lithium salt and transmission of lithium ions, has good film forming property and mechanical property, and can form a self-supporting electrolyte film structure; The LATP ceramic powder has a NASICON fast ion conductor structure, the surface is rich in Lewis acid sites, the LATP ceramic powder can interact with PVDF-HFP, interface side reaction is reduced, electrode/electrolyte interface stability and high voltage resistance are improved, and meanwhile, the LATP ceramic powder has high ion conductivity and assists in improving the overall ion transmission capacity; TMP (trimethyl phosphate) solvent is taken as a green flame-retardant solvent, has high flash point and good thermal stability, can obviously reduce the flammability of electrolyte, improves the thermal safety, and does not influence the electrochemical performance of the electrolyte; LiDFOB and LiTFSI compound lithium salt, wherein LiDFOB has excellent film forming property and interface stability, electrode/electrolyte interface compatibility can be optimized, liTFSI can effectively improve lithium salt dissociation degree and electrolyte ion conductivity, and the two compound lithium salts realize cooperative improvement of ion migration number and electrochemic