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CN-122025745-A - Sulfide composite electrolyte membrane and preparation method thereof

CN122025745ACN 122025745 ACN122025745 ACN 122025745ACN-122025745-A

Abstract

The invention provides a sulfide composite electrolyte membrane and a preparation method thereof, belonging to the technical field of electrolytes. The sulfide composite electrolyte membrane comprises, by mass, 1-3% of polytetrafluoroethylene, 0.5-2% of mercapto-polyethylene glycol-amino, and the balance sulfide electrolyte. According to the invention, mercapto-polyethylene glycol-amino is used as an interface stabilizer to coordinate lithium ions in sulfide electrolyte to form a dynamic interface layer, stress concentration is relieved, mercapto forms a stable disulfide bond with metal elements in a high-voltage positive electrode, so that interface contact between the electrolyte layer and an electrode layer is enhanced, amino is combined with hydroxyl on the surface of the positive electrode through hydrogen bonding to inhibit interface side reaction, and interfacial degradation of sulfide electrolyte and a high-nickel positive electrode is inhibited through synergistic effect of mercapto and amino.

Inventors

  • DU XILAN
  • ZHANG KAIZHOU
  • YANG JUNZHU
  • SHI OULING
  • JIN JINBO
  • XIAO JUN
  • QIN SHUHAO
  • YAN YAN
  • LEI TING

Assignees

  • 贵州省材料产业技术研究院

Dates

Publication Date
20260512
Application Date
20260205

Claims (9)

  1. 1. The sulfide composite electrolyte membrane is characterized by comprising the following components in percentage by mass: 1-3wt% of polytetrafluoroethylene; 0.5-2wt% of sulfhydryl-polyethylene glycol-amino; The balance being sulfide electrolyte.
  2. 2. The sulfide composite electrolyte membrane according to claim 1, comprising the following components in mass percent: 2wt% of polytetrafluoroethylene; 1wt% of sulfhydryl-polyethylene glycol-amino; 97wt% sulfide electrolyte.
  3. 3. The sulfide composite electrolyte membrane according to claim 1, wherein the sulfide electrolyte is Li 7 P 3 S 11 .
  4. 4. The sulfide composite electrolyte membrane according to claim 1, wherein the thickness of the sulfide composite electrolyte membrane is 50 μm or less.
  5. 5. The sulfide composite electrolyte membrane according to claim 1, wherein the room temperature conductivity of the sulfide composite electrolyte membrane is not lower than 10 -3 S/cm.
  6. 6. The sulfide composite electrolyte membrane according to claim 1, wherein the capacity retention rate after 300 cycles of the sulfide composite electrolyte membrane is equal to or higher than 90%.
  7. 7. A method for producing a sulfide composite electrolyte membrane according to any one of claims 1 to 6, comprising the steps of: step S1, mixing sulfhydryl-polyethylene glycol-amino and sulfide electrolyte in a dry way to form uniform mixed powder; step S2, polytetrafluoroethylene is added into the mixed powder, a uniform fiber network is formed through high-speed shearing, and the mixed powder is dispersed in gaps of the fiber network to form an intermediate; And S3, pressing the intermediate into the composite electrolyte membrane by adopting a hot press molding process.
  8. 8. The method for producing a sulfide composite electrolyte membrane according to claim 7, wherein in step S2, the shearing rate is 800r/min.
  9. 9. The method for producing a sulfide composite electrolyte membrane according to claim 7, wherein in step S3, the hot pressing is performed at a pressure of 120 to 600MPa and a temperature of 60 ℃.

Description

Sulfide composite electrolyte membrane and preparation method thereof Technical Field The invention belongs to the technical field of electrolyte, and particularly relates to a sulfide composite electrolyte membrane and a preparation method thereof. Background Sulfide solid state electrolytes are ideal choices for high energy density batteries due to their high ionic conductivity (10 -2-10-3 S/cm) and wide electrochemical window, but have serious side reactions at their interface with high nickel anodes (e.g., liCoO 2) resulting in reduced cycle life. Traditional PTFE binders, while enhancing mechanical strength, react with lithium ions to form lithium fluoride, consuming active lithium and reducing interfacial stability. In the prior art, the problem can be alleviated by adding an interface modification layer (such as fluorinated polymer), but the cost is high and the process is complex. Disclosure of Invention The invention discloses a sulfide composite electrolyte membrane and a preparation method thereof, wherein mercapto-polyethylene glycol-amino is introduced as an interface stabilizer, and the interface degradation of sulfide electrolyte and a high-nickel anode is inhibited through the synergistic effect of mercapto (-SH) and amino (-NH 2), so that at least one technical problem related in the background technology can be effectively solved. In order to achieve the above purpose, the technical scheme of the invention is as follows: The sulfide composite electrolyte membrane comprises the following components in percentage by mass: 1-3wt% of polytetrafluoroethylene; 0.5-2wt% of sulfhydryl-polyethylene glycol-amino; The balance being sulfide electrolyte. As a preferred improvement, the composition comprises the following components in percentage by mass: 2wt% of polytetrafluoroethylene; 1wt% of sulfhydryl-polyethylene glycol-amino; 97wt% sulfide electrolyte. As a preferred modification, the sulfide electrolyte is Li 7P3S11. As a preferable improvement, the thickness of the sulfide composite electrolyte membrane is 50 μm or less. As a preferable improvement, the room temperature conductivity of the sulfide composite electrolyte membrane is not less than 10 -3 S/cm. As a preferable improvement, the capacity retention rate of the sulfide composite electrolyte membrane after 300 cycles is not less than 90%. The preparation method of the sulfide composite electrolyte membrane comprises the following steps: step S1, mixing sulfhydryl-polyethylene glycol-amino and sulfide electrolyte in a dry way to form uniform mixed powder; step S2, polytetrafluoroethylene is added into the mixed powder, a uniform fiber network is formed through high-speed shearing, and the mixed powder is dispersed in gaps of the fiber network to form an intermediate; And S3, pressing the intermediate into the composite electrolyte membrane by adopting a hot press molding process. As a preferred improvement, in step S2, the shear rate is 800r/min. As a preferred improvement, in step S3, the hot pressing is performed at a pressure of 120-600MPa and a temperature of 60 ℃. The beneficial effects of the invention are as follows: According to the invention, mercapto-polyethylene glycol-amino is introduced into sulfide electrolyte as an interface stabilizer, mercapto (-SH) can coordinate lithium ions in sulfide electrolyte to form a dynamic interface layer, stress concentration is relieved, mercapto can form stable disulfide bond with metal elements in a high-voltage positive electrode, so that interface contact between an electrolyte layer and an electrode layer is enhanced, amino (-NH 2) is combined with hydroxyl on the surface of the positive electrode through hydrogen bonding, interface side reaction (such as sulfide oxidation) is inhibited, interface degradation of sulfide electrolyte and a high-nickel positive electrode is inhibited through synergistic effect of mercapto (-SH) and amino (-NH 2), and in addition, polytetrafluoroethylene is added as a fibrosis agent, a three-dimensional fiber network is formed through shear induction, and the mechanical strength of an electrolyte membrane is enhanced. Detailed Description The technical solutions of the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. The embodiment provides a sulfide composite electrolyte membrane, which comprises the following components in percentage by mass: 1-3wt% of polytetrafluoroethylene; 0.5-2wt% of sulfhydryl-polyethylene glycol-amino; The balance being sulfide electrolyte. Preferably, the composition comprises the following components in