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CN-120933455-B - High ion conductivity polymer electrolyte, lithium metal battery and preparation method

CN120933455BCN 120933455 BCN120933455 BCN 120933455BCN-120933455-B

Abstract

The invention discloses a high-ion conductivity polymer electrolyte, a lithium metal battery and a preparation method thereof, which belong to the technical field of high-energy density lithium metal batteries and are prepared by in-situ polymerization of a polymer precursor solution comprising 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecyl methacrylate, methyl acrylate, lithium bistrifluoromethane sulfonyl imide, a cross-linking agent, an initiator and a plasticizer in the battery. According to the invention, the ultra-long fluorine chain monomer 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate is introduced into the precursor liquid of the polymer electrolyte, has good compatibility with methyl acrylate, does not generate phase separation, and is copolymerized into the ultra-long fluorine chain polymer, so that the structural stability of an electrolyte frame is effectively ensured, the impedance is reduced, the ionic conductivity of the electrolyte is improved, and the electrochemical window is further improved. The polymer electrolyte of the in-situ polymerized ultralong fluorine chain has the advantages of lithium metal stability and high-voltage stability, and in-situ polymerization improves the contact stability with an anode interface and a cathode interface, and further promotes the cycle stability of a lithium metal battery.

Inventors

  • YANG HUI
  • LIU GUOFENG
  • WANG MENG
  • CHEN DONGXU
  • YUE PEIYU
  • WANG YIDING
  • ZHANG SHILIN

Assignees

  • 中国铁塔股份有限公司

Dates

Publication Date
20260512
Application Date
20250717

Claims (8)

  1. 1. The high-ion conductivity polymer electrolyte is characterized by being prepared by in-situ polymerization of a polymer precursor solution comprising 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecyl fluorooctyl acrylate, methyl acrylate, lithium bistrifluoromethane sulfonyl imide, a cross-linking agent, an initiator and a plasticizer in a battery, wherein the 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecyl fluorooctyl acrylate and the methyl acrylate are copolymerized to form a fluorine chain polymer; the volume ratio of 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate to methyl acrylate is x 10-x, wherein 3< x <7; In the polymer precursor solution, the mass fraction of 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate is 15-30%; The molar concentration of the lithium bistrifluoromethane sulfonyl imide is 0.5-3M.
  2. 2. The high ion conductivity polymer electrolyte according to claim 1, wherein in the polymer precursor solution, the mass fraction of the crosslinking agent is 0.3 to 0.5%; And/or, in the polymer precursor solution, the mass fraction of the initiator is 0.1-0.2%; And/or, in the polymer precursor solution, the mass fraction of the plasticizer is 20-25%.
  3. 3. The high ionic conductivity polymer electrolyte according to claim 1, wherein said cross-linking agent is selected from one or more of polyethylene glycol diacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate or pentaerythritol tetraacrylate; And/or the plasticizer is selected from fluorine-containing solvents and/or ether solvents.
  4. 4. A lithium metal battery comprising the high ionic conductivity polymer electrolyte according to any one of claims 1 to 3.
  5. 5. A method of preparing a lithium metal battery according to claim 4, comprising the steps of: S1, mixing 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate, methyl acrylate, lithium bistrifluoromethane sulfonyl imide, a cross-linking agent, an initiator and a plasticizer to obtain a polymer precursor solution; s2, assembling a battery anode, a lithium metal cathode, a diaphragm and the polymer precursor solution to obtain a button battery; and S3, carrying out vacuum standing on the button cell, and carrying out heating and curing after vacuum standing, so that the polymer precursor solution is polymerized into a solid electrolyte in situ, thereby obtaining the lithium metal cell.
  6. 6. The method for producing a lithium metal battery according to claim 5, wherein in step S1, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate, methyl acrylate, lithium bistrifluoromethane sulfonyl imide, a crosslinking agent, an initiator, and a plasticizer are mixed to obtain a polymer precursor solution, comprising: Stirring and mixing a cross-linking agent, an initiator and a plasticizer to obtain a first mixed solution; Mixing 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate and methyl acrylate to obtain a second mixed solution; and mixing the first mixed solution and the second mixed solution, and then adding the lithium bistrifluoromethane sulfonyl imide to stir and mix to obtain a polymer precursor solution.
  7. 7. The method for preparing a lithium metal battery according to claim 5, wherein the addition amount of the polymer precursor solution is 20 to 50 μl; And/or the temperature of the heating and curing is 60-80 ℃ and the time is 12-48 h.
  8. 8. The preparation method of the lithium metal battery according to claim 5 is characterized in that the battery anode is prepared by stirring and mixing polyvinylidene fluoride, nickel cobalt manganese ternary anode material, lithium bis (trifluoromethanesulfonyl imide), acetylene black and a solvent to obtain slurry, coating the slurry on the surface of a current collector aluminum foil, and drying to obtain the battery anode.

Description

High ion conductivity polymer electrolyte, lithium metal battery and preparation method Technical Field The invention belongs to the technical field of high-energy density lithium metal batteries, and particularly relates to a high-ion conductivity polymer electrolyte, a lithium metal battery and a preparation method. Background Solid-state lithium metal batteries are of great interest because of their high safety and high theoretical specific capacity. Among the many solid electrolytes, polymer electrolytes have received much attention due to their low interfacial resistance and flexibility, and in-situ polyelectrolytes have significant advantages in cost, scale production. However, most of the current polymer electrolytes have low ionic conductivity, and poor interface stability with lithium metal, so that the electrochemical performance of the polymer electrolytes has a large improvement space, and the development of polymer electrolyte-based lithium metal batteries is limited. Among the polymer classes, methyl acrylate has a broad electrochemical window and good compatibility with high-pressure transition metal oxides. However, the problem of low ionic conductivity at room temperature has limited its further development. At present, inorganic fillers such as SiO 2、Al2O3、TiO2 and the like are added to the means for improving the ionic conductivity, and the composite structure not only improves the mechanical strength of the polymer electrolyte, but also improves the ionic conductivity, and the improvement effect of the performance is related to the type and the size of the added fillers. However, the addition of the inorganic filler increases the interfacial resistance between the polymer and the inorganic filler, which has a certain influence on the flexibility and the processability of the polymer, and meanwhile, the filler particles with high concentration may be agglomerated to block the chain segment movement, so that the ion transmission network is blocked and destroyed. In addition to the addition of fillers, the prior art has also proposed the incorporation of small molecule plasticizers. Compared to inorganic fillers, organic plasticizers are more compatible with polymeric substrates and more easily uniformly dispersed in the polymer. Plasticizers improve the ionic conductivity of polymer electrolytes by weakening the interaction forces between macromolecules and disrupting the crystalline regions of crystalline materials. However, as the amorphous region increases, the mechanical properties of the polymer electrolyte as a whole decrease. When the plasticizer is added in too small amount, molecular chains are easier to move, so that the directional crystallization of a macromolecular non-oriented region is possible to play a role in anti-plasticization, when the plasticizer content is too large, the containing degree of the matrix to the plasticizer is limited, and small molecules are separated from the polymer matrix, and the conduction mechanism is similar to that of a liquid electrolyte, so that the mechanical strength of the electrolyte is weakened. Furthermore, the addition of organic plasticizers weakens the high pressure stability of the polymer matrix. Disclosure of Invention In order to solve the technical problems of the background, the main purpose of the invention is to provide a polymer electrolyte with high ion conductivity, a lithium metal battery and a preparation method, which solve the problem of low ion conductivity of the polymer electrolyte on the premise of not influencing electrolyte impedance, ensure the electrochemical stability of the polymer electrolyte and have good compatibility with a lithium metal interface at the same time, thereby promoting the cycle stability of the lithium metal battery. In order to achieve the above object, the present invention provides a high ion conductivity polymer electrolyte prepared by in-situ polymerization of a polymer precursor solution comprising 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate, methyl acrylate, lithium bistrifluoromethane sulfonyl imide, a crosslinking agent, an initiator and a plasticizer in a battery. Further, the volume ratio of 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate to methyl acrylate is x 10-x, wherein 3< x <7. Further, in the polymer precursor solution, the mass fraction of 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate is 15-30%. Further, in the polymer precursor solution, the molar concentration of the lithium bistrifluoromethane sulfonyl imide is 0.5-3M. Further, in the polymer precursor solution, the mass fraction of the crosslinking agent is 0.3-0.5%. Further, in the polymer precursor solution, the mass fraction of the initiator is 0.1-0.2%. Further, in the polymer precursor solution, the mass fraction of the plasticizer is 20-25%. Further, the cross-linking agent is selected from one or more of polyethylene glycol diacrylate, pentaerythritol triacrylate, dipentaerythritol hexa