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CN-122025787-A - High-voltage-resistant solid polymer electrolyte, preparation method thereof and solid lithium metal battery

CN122025787ACN 122025787 ACN122025787 ACN 122025787ACN-122025787-A

Abstract

The invention provides a high-voltage-resistant solid polymer electrolyte, a preparation method thereof and a solid lithium metal battery. The high-pressure-resistant solid polymer electrolyte comprises an organic filler, lithium salt and a polymer matrix, wherein the organic filler is a polymer PDDA-DFOB formed by combining polydiallyl dimethyl ammonium cations (PDDA + ) and difluoro oxalic acid borate anions (DFOB – ), and the organic filler accounts for 10-30wt% of the polymer matrix in the high-pressure-resistant solid polymer electrolyte. The high-voltage-resistant solid polymer electrolyte disclosed by the invention has excellent comprehensive performance, is suitable for high-voltage positive electrode materials and is easy to prepare in a large scale.

Inventors

  • KANG FEIYU
  • CHENG XING
  • HE YANBING
  • LIU XIAOCHONG
  • CHEN YONGQI
  • DOU YING
  • SHI PEIRAN
  • WANG CUICUI

Assignees

  • 清华大学深圳国际研究生院

Dates

Publication Date
20260512
Application Date
20260317

Claims (10)

  1. 1. The high-pressure-resistant solid polymer electrolyte is characterized by comprising an organic filler, lithium salt and a polymer matrix, wherein the organic filler is a polymer PDDA-DFOB formed by combining polydiallyl dimethyl ammonium cations (PDDA + ) and difluoro oxalic acid borate anions (DFOB – ), and the organic filler accounts for 10-30wt% of the polymer matrix in the high-pressure-resistant solid polymer electrolyte.
  2. 2. The high-pressure resistant solid polymer electrolyte of claim 1, wherein the polydiallyldimethyl ammonium cation (PDDA + ) is derived from polydiallyldimethyl ammonium chloride (PDDA), the difluoro-oxalato-borate anion (DFOB – ) is derived from lithium difluoro-oxalato-borate (LiDFOB), and the organic filler is prepared by ion exchange deposition.
  3. 3. The high-pressure resistant solid polymer electrolyte according to claim 2, wherein the preparation process of the organic filler comprises the steps of respectively preparing aqueous solutions of polydiallyl dimethyl ammonium chloride (PDDA) and lithium difluorooxalato borate (LiDFOB), mixing and stirring the aqueous solutions according to the molar ratio of polydiallyl dimethyl ammonium cation to difluorooxalato borate anion of at least 1:1, generating a precipitate PDDA-DFOB through ion exchange deposition, and drying to obtain PDDA-DFOB powder.
  4. 4. The high-pressure solid polymer electrolyte according to claim 1, wherein the main particles of the organic filler have a particle diameter of 200 nm or less, and the content of the organic filler is 20wt% of the polymer matrix.
  5. 5. The high-pressure-resistant solid polymer electrolyte according to claim 1, wherein the lithium salt is lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) and the content of the lithium salt is 25 to 50wt% of the polymer matrix.
  6. 6. The high pressure resistant solid polymer electrolyte of claim 1 wherein the lithium salt is present in an amount of 40wt% of the polymer matrix.
  7. 7. The high pressure resistant solid polymer electrolyte of claim 1 wherein the polymer matrix is a PEO polymer comprising-C-O-C-segments, the molar ratio of lithium ions in the lithium salt to oxygen in one-C-O-C-segment in the PEO polymer being between 1:12 and 1:24.
  8. 8. The high pressure resistant solid polymer electrolyte of claim 7 wherein the molar ratio of lithium ions in said lithium salt to oxygen in one of said-C-O-C-segments in said PEO polymer is 1:16 and wherein said PEO polymer has a molecular weight of 60 ten thousand.
  9. 9. A method for preparing the high pressure resistant solid polymer electrolyte according to any one of claims 1 to 8, comprising the steps of: s1, dissolving a polymer matrix and lithium salt in an organic solvent according to a predetermined mass ratio, and stirring at room temperature for more than 2 h to obtain a uniform transparent solution; S2, preparing an aqueous solution of a substance containing polydiallyl dimethyl ammonium cations (PDDA + ) and a substance containing difluoro oxalic acid borate anions (DFOB – ), stirring at room temperature according to the molar ratio of polydiallyl dimethyl ammonium cations to difluoro oxalic acid borate anions of at least 1:1, and performing ion exchange deposition to generate a precipitate PDDA-DFOB; S3, drying the obtained PDDA-DFOB to obtain PDDA-DFOB powder serving as an organic filler; s4, adding an organic filler accounting for 10-30wt% of the polymer mass into the transparent solution obtained in the step S1, and stirring at room temperature for more than 6 hours to obtain a uniform transparent solution; S5, pouring the transparent solution obtained in the step S4 into a mold, and drying to remove redundant organic solvents to obtain the high-pressure-resistant solid polymer electrolyte.
  10. 10. A solid lithium metal battery, comprising a positive electrode, the high-voltage resistant solid polymer electrolyte according to any one of claims 1 to 8, and a negative electrode.

Description

High-voltage-resistant solid polymer electrolyte, preparation method thereof and solid lithium metal battery Technical Field The invention relates to the technical field of polymer electrolytes and lithium metal all-solid-state batteries, in particular to a high-voltage-resistant solid-state polymer electrolyte, a preparation method thereof and a solid-state lithium metal battery. Background Solid state lithium batteries are considered to be an ideal choice for next generation energy storage devices, and solid state electrolytes have attracted considerable attention as a key component of solid state batteries. Solid Polymer Electrolytes (SPEs) have significant advantages in forming good interfacial contact with electrodes due to their excellent flexibility and processing compatibility, which helps to reduce interfacial resistance, making them of greater interest than inorganic solid electrolytes. However, development and application of SPEs has long been limited by their low ionic conductivity, narrow Electrochemical Stability Window (ESW), and insufficient mechanical strength. While much research has been devoted to improving the ion-conducting properties of polymer electrolytes, systematic discussion and review of ESW remains limited. Among the many SPE materials, polyethylene oxide (PEO) based solid state electrolytes are currently the most widely used system due to their potential for high energy density, high power density and safety. However, PEO typically has an ESW below 4V, a bottleneck that severely impedes its matching to high voltage positive electrode materials, and thus limits further improvement in solid state battery energy density. It should be noted that the information disclosed in the above background section is only for understanding the background of the application and thus may include information that does not form the prior art that is already known to those of ordinary skill in the art. Disclosure of Invention In order to make up the defects of the prior art, the invention provides the high-voltage-resistant solid polymer electrolyte which has excellent comprehensive performance, is suitable for high-voltage positive electrode materials and is easy to prepare in a large scale. The invention adopts the following technical scheme: The first aspect provides a high-pressure-resistant solid polymer electrolyte, which comprises an organic filler, lithium salt and a polymer matrix, wherein the organic filler is a polymer PDDA-DFOB formed by combining polydiallyl dimethyl ammonium cations (PDDA +) and difluoro oxalic acid borate anions (DFOB –), and the organic filler accounts for 10-30wt% of the polymer matrix in the high-pressure-resistant solid polymer electrolyte. According to a second aspect, a preparation method of the high-pressure-resistant solid polymer electrolyte is provided, which comprises the following steps of S1, dissolving a polymer matrix and lithium salt in an organic solvent according to a preset mass ratio, stirring at room temperature for more than 2 h to obtain a uniform transparent solution, S2, preparing an aqueous solution of a substance containing polydiallyl dimethyl ammonium cation (PDDA +) and a substance containing difluoro oxalic acid borate anion (DFOB –), stirring at room temperature according to a molar ratio of polydiallyl dimethyl ammonium cation to difluoro oxalic acid borate anion of at least 1:1, performing ion exchange deposition to obtain a precipitate PDDA-DFOB, S3, drying the obtained PDDA-DFOB to obtain PDDA-DFOB powder as an organic filler, adding the organic filler accounting for 10-30 wt% of the polymer mass into the transparent solution obtained in the step S1, stirring at room temperature for more than 6 hours to obtain the uniform transparent solution, S5, pouring the transparent solution obtained in the step S4 into a mould, and removing the excess solid-state electrolyte through ion exchange deposition to obtain the high-pressure-resistant solid polymer electrolyte. In a third aspect, a solid state lithium metal battery is provided that includes a positive electrode, the high voltage resistant solid state polymer electrolyte, and a negative electrode. The invention has the beneficial effects that: The high-pressure-resistant solid polymer electrolyte provided by the invention solves the problem of instability under high voltage when the solid electrolyte runs at high temperature through the synergistic effect of the organic filler, the lithium salt and the polymer matrix in a specific ratio. The organic filler PDDA-DFOB is used for regulating the interaction between the organic filler PDDA-DFOB, a polymer matrix and anions, so that the highly stable solid-state-resistant electrolyte suitable for a high-voltage environment is prepared. In addition, the polycation can keep the obtained high-pressure-resistant solid polymer electrolyte dry for a long time under the moist air by regulating and controlling intermolecular interaction, has air