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CN-121975252-A - Interfacial film, method for its preparation and its use in assembling lithium ion batteries

CN121975252ACN 121975252 ACN121975252 ACN 121975252ACN-121975252-A

Abstract

The invention discloses an interface film, a preparation method and application thereof in assembling a lithium ion battery, wherein the interface film comprises the following components of lithium salt, polyvinylidene fluoride and 1-butyl-2, 3-dimethyl imidazolium chloride, the mass ratio of the lithium salt to the polyvinylidene fluoride to the 1-butyl-2, 3-dimethyl imidazolium chloride is about 1:0.9-1.1:0.9-1.1, preferably about 1:0.95-1.05:0.95-1.05, the weight average molecular mass of the polyvinylidene fluoride is about 90-110 g/mol, the lithium salt is lithium bistrifluoromethane sulfonyl imide (LiTFSI) and/or lithium bifluoride sulfonyl imide (LiFeSI), the purity of the lithium salt is more than 99.9%, and the novel interface film is prepared by compounding the polyvinylidene fluoride (PVDF) serving as a polymer matrix with ionic liquid 1-butyl-2, 3-dimethyl imidazolium chloride (BMMImCl) and the lithium salt, has excellent high-temperature resistance and good chemical stability, and has excellent lithium ion absorption performance in various fields, and has excellent high-temperature and high-temperature ion transmission properties.

Inventors

  • CHEN LIN

Assignees

  • 深圳欣界能源科技股份有限公司

Dates

Publication Date
20260505
Application Date
20251229

Claims (10)

  1. 1. An interfacial film, characterized in that the interfacial film comprises the following components: lithium salt, polyvinylidene fluoride and 1-butyl-2, 3-dimethyl imidazolium chloride.
  2. 2. The interfacial film of claim 1, wherein the mass ratio of lithium salt, polyvinylidene fluoride and 1-butyl-2, 3-dimethylimidazolium chloride is about 1:0.9-1.1:0.9-1.1, preferably about 1:0.95-1.05:0.95-1.05.
  3. 3. Interface film according to claim 1 or 2, characterized in that the polyvinylidene fluoride has a weight average molecular mass of about 90 to 120 g/mol, preferably about 95 to 110 g/mol, and/or The lithium salt is lithium bis (trifluoromethanesulfonyl imide) (LiTFSI) and/or lithium bis (fluorosulfonyl imide) (LiWSI), and/or The lithium salt has a purity of greater than about 98.2%, preferably greater than about 99%, and more preferably greater than about 99.9%.
  4. 4. A method for preparing an interfacial film, comprising the steps of: (1) Providing a lithium salt, polyvinylidene fluoride, 1-butyl-2, 3-dimethylimidazolium chloride and a solvent, and (2) And (5) film formation.
  5. 5. The method according to claim 4, wherein the mass ratio of the lithium salt, polyvinylidene fluoride and 1-butyl-2, 3-dimethylimidazolium chloride is about 1:0.9-1.1:0.9-1.1, preferably about 1:0.95-1.05:0.95-1.05.
  6. 6. The method according to claim 4 or 5, wherein the polyvinylidene fluoride has a weight average molecular mass of about 90 to 120 g/mol, preferably about 95 to 110 g/mol, and/or The lithium salt is lithium bis (trifluoromethanesulfonyl imide) (LiTFSI) and/or lithium bis (fluorosulfonyl imide) (LiWSI) and/or The lithium salt has a purity of greater than 98.2%, preferably greater than 99%, more preferably greater than 99.9%, and/or The solvent is one or more of N, N-dimethylformamide, N-methylpyrrolidone and tetrahydrofuran.
  7. 7. The process according to any one of claims 4 to 6, wherein step (1) comprises mixing the lithium salt, polyvinylidene fluoride and 1-butyl-2, 3-dimethylimidazolium chloride with the solvent, preferably to obtain a mixed solution, and/or The step (2) comprises performing the treatment at a temperature above room temperature.
  8. 8. The method of claim 7, wherein the treatment comprises a forced air drying and/or vacuum drying treatment.
  9. 9. The method according to claim 8, wherein the temperature of the air-blast drying is 70-100 ℃, preferably 75-80 ℃, and/or the time of the air-blast drying is 10-14 hours, preferably 11-12 hours, and/or the temperature of the vacuum drying is 40-50 ℃, and/or the time of the vacuum drying is 1-2 hours.
  10. 10. Use of the interfacial film of any one of claims 1-3, or the interfacial film prepared by the method of any one of claims 4-9, in assembling a lithium ion battery.

Description

Interfacial film, method for its preparation and its use in assembling lithium ion batteries Technical Field The invention relates to an interfacial film, a method for the production thereof, and the use thereof for the assembly of lithium ion batteries. Background All-solid-state batteries have been attracting attention due to their higher energy density and longer cycle life than conventional batteries. However, the problem of safety has been one of the key factors limiting its wide application. For example, interfacial contact between an electrolyte and a lithium anode has been a concern. When two hard materials are in direct contact, such an intimate contact can have a number of serious consequences, one of which is the acceleration of lithium dendrite growth. The occurrence of lithium dendrites may further damage the electrolyte membrane, even leading to shorting of the anode and cathode, eventually leading to shorting of the battery, with serious safety hazards. Thus, there is a need for a product that improves interfacial contact in all-solid state batteries. Disclosure of Invention To solve this problem, the present disclosure proposes a solution to introduce a layer of polymer interface film between the lithium anode and the electrolyte membrane. The role of this technique is manifold. First, it can enhance the contact between the electrolyte and the lithium anode to make it more compact, thereby effectively reducing the likelihood of lithium dendrite growth. Second, the introduction of the polymer interfacial film also prevents the formation of lithium dendrites, thereby helping to form a stable and good solid electrolyte interfacial layer (SEI), thereby improving the safety of the battery. The introduction of such a polymeric interfacial film provides a new concept and solution for the development of all-solid-state batteries. By introducing the polymer interface film, the safety of the battery can be effectively improved, and a solid foundation is laid for the application of the battery in the fields of electric vehicles, energy storage systems and the like. The invention aims to provide an interface film, a preparation method and application thereof, wherein polyvinylidene fluoride is innovatively used as a raw material in the preparation process to prepare the interface film with higher room-temperature ion conductivity, and a lithium metal battery prepared based on the interface film has good battery cycle performance and stability. A first aspect of the present disclosure relates to an interfacial film characterized in that the interfacial film material comprises a lithium salt, polyvinylidene fluoride, and 1-butyl-2, 3-dimethylimidazolium chloride. In some embodiments, the mass ratio of the lithium salt, polyvinylidene fluoride, and 1-butyl-2, 3-dimethylimidazolium chloride is about 1:0.9-1.1:0.9-1.1, preferably about 1:0.95-1.05:0.95-1.05. In some embodiments, the polyvinylidene fluoride has a weight to average molecular weight of about 90 to 120 g/mol, preferably about 95 to 110 g/mol. In some embodiments, the lithium salt is lithium bis (trifluoromethanesulfonyl imide) (LiTFSI) and/or lithium bis (fluorosulfonyl imide) (LiFSI). In some embodiments, the lithium salt has a purity of greater than about 98.2%, preferably greater than about 99%, more preferably greater than about 99.9%. Another aspect of the present disclosure relates to a method of making an interfacial film, characterized in that the method comprises the steps of (1) providing a lithium salt, polyvinylidene fluoride (PVDF), 1-butyl-2, 3-dimethylimidazolium chloride, and a solvent, and (2) forming a film. In some embodiments, the mass ratio of the lithium salt, polyvinylidene fluoride, and 1-butyl-2, 3-dimethylimidazolium chloride is about 1:0.9-1.1:0.9-1.1, preferably about 1:0.95-1.05:0.95-1.05. In some embodiments, the polyvinylidene fluoride has a weight to average molecular weight of about 90 to 110 g/mol, preferably about 95 to 110 g/mol. In some embodiments, the lithium salt is lithium bis (trifluoromethanesulfonyl imide) (LiTFSI) and/or lithium bis (fluorosulfonyl imide) (LiFSI). In some embodiments, the lithium salt has a purity of greater than about 99.9%. In some embodiments, the solvent is one or more of N, N-dimethylformamide, N-methylpyrrolidone, tetrahydrofuran. In some embodiments, step (1) comprises mixing a lithium salt, polyvinylidene fluoride, and 1-butyl-2, 3-dimethylimidazolium chloride with a solvent, preferably to obtain a mixed solution. In some embodiments, step (2) comprises performing the treatment at a temperature above room temperature. In some embodiments, the treatment in step (2) comprises a forced air drying and/or vacuum drying treatment. In some embodiments, the temperature of the air-blast drying is about 70-100 ℃, preferably about 75-80 ℃, and the time of the air-blast drying is about 10-14 hours, preferably about 11-12 hours. In some embodiments, the temperature of the vacuum drying is