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CN-122025792-A - Multi-metal oxyacid salt composite solid electrolyte membrane, preparation method thereof and solid battery

CN122025792ACN 122025792 ACN122025792 ACN 122025792ACN-122025792-A

Abstract

The invention discloses a polyoxometallate composite solid electrolyte membrane, a preparation method thereof and a solid battery, and belongs to the technical field of solid lithium metal batteries. The polyoxometallate composite solid electrolyte membrane provided by the invention comprises polyion liquid and lithium silicotungstate, wherein the polyion liquid consists of polydiallyl dimethyl ammonium cations and lithium salt anions, and the mass ratio of the lithium silicotungstate to the polyion liquid is (4-25) (75-96). The invention constructs the ion transmission network with ordered structure by utilizing the strong electrostatic coupling effect between the polyoxometallate anions and the polymer cation chains. The composite structure effectively promotes dissociation of lithium salt and directional migration of lithium ions, remarkably improves the room-temperature ion conductivity, the lithium ion migration number and the mechanical strength of an electrolyte membrane, and simultaneously enhances the interface compatibility and the electrochemical stability of the electrolyte membrane and a lithium metal negative electrode.

Inventors

  • HUI XIAOBIN
  • ZHAO YUTONG
  • YIN LONGWEI
  • Zhu Ruixiao

Assignees

  • 山东大学
  • 山东大学苏州研究院

Dates

Publication Date
20260512
Application Date
20260410

Claims (10)

  1. 1. The polyoxometalate composite solid electrolyte membrane is characterized by comprising polyion liquid and lithium silicotungstate, wherein the polyion liquid consists of polydiallyl dimethyl ammonium cations and lithium salt anions, and the mass ratio of the lithium silicotungstate to the polyion liquid is (4-25) (75-96).
  2. 2. The polyoxometalate composite solid electrolyte membrane according to claim 1, wherein the mass ratio of the lithium silicotungstic acid to the polyionic liquid is (5-20): (80-95).
  3. 3. The polyoxometallate composite solid electrolyte membrane of claim 1, wherein said lithium salt anion is selected from at least one of bis-trifluoromethanesulfonyl imide, bis-fluorosulfonyl imide, hexafluorophosphate.
  4. 4. The polyoxometalate composite solid electrolyte membrane of claim 1, wherein the polyoxometalate composite solid electrolyte membrane has a thickness of 50-200 μm.
  5. 5. The method for preparing the polyoxometalate composite solid electrolyte membrane according to any one of claims 1 to 4, comprising the steps of: mixing and reacting polydiallyl dimethyl ammonium chloride aqueous solution and lithium salt aqueous solution to prepare polyion liquid; And mixing the polyion liquid with lithium silicotungstate in an organic solvent, and then preparing a membrane to obtain the polyoxometalate composite solid electrolyte membrane.
  6. 6. The preparation method of claim 5, wherein the concentration of the polydiallyl dimethyl ammonium chloride aqueous solution is 20-38 wt%, the concentration of the lithium salt aqueous solution is 0.1-0.5 mol/L, and the lithium salt is at least one selected from lithium bis (trifluoromethanesulfonyl) imide, lithium bis (fluorosulfonyl) imide and lithium hexafluorophosphate.
  7. 7. The preparation method of claim 6, wherein the molar ratio of polydiallyl dimethyl ammonium chloride to lithium salt is 1 (0.9-1.1).
  8. 8. The process according to claim 5, wherein the organic solvent is selected from the group consisting of N, N-dimethylformamide, N-methylpyrrolidone, acetonitrile and dimethylsulfoxide.
  9. 9. A solid state battery comprising the polyoxometalate composite solid electrolyte membrane according to any one of claims 1 to 4 or the polyoxometalate composite solid electrolyte membrane produced by the production method according to any one of claims 5 to 8.
  10. 10. The solid state battery of claim 9, wherein the solid state battery is a solid state lithium metal battery.

Description

Multi-metal oxyacid salt composite solid electrolyte membrane, preparation method thereof and solid battery Technical Field The invention relates to the technical field of solid lithium metal batteries, in particular to a polyoxometallate composite solid electrolyte membrane, a preparation method thereof and a solid battery. Background Lithium metal batteries are considered as promising energy storage systems because of the combination of high theoretical specific capacity and low redox potential of the negative electrode material. However, the progress of the industrialization of lithium metal batteries still faces serious challenges, mainly because conventional organic electrolytes are prone to persistent side reactions with high-activity lithium metals, thereby inducing uncontrolled growth of lithium dendrites. This not only results in a degradation of battery cycle life and coulombic efficiency, but also is more likely to cause internal short circuits or even thermal runaway safety issues. Therefore, the development of intrinsically safe solid state electrolytes is a key to the promotion of lithium metal batteries for practical use. The solid electrolyte is used as an important functional layer between the positive electrode and the negative electrode in the battery, plays roles of isolating the electrodes and preventing short circuit, and is also used as an ion conduction channel to realize migration of charges between the two electrodes, and the ion conduction performance of the solid electrolyte directly influences the energy conversion efficiency and the cycle stability of the battery. The current mainstream technology route includes inorganic solid state electrolytes and polymer solid state electrolytes. Although the inorganic solid electrolyte has high room temperature ionic conductivity, the inherent brittleness of the inorganic solid electrolyte leads to high processing difficulty, poor contact with a solid-solid interface between electrodes and outstanding interface impedance. The polymer solid electrolyte can improve electrode contact by virtue of good flexibility and processability, but the ion conductivity at room temperature is generally low, so that the requirement of a high-power battery is difficult to meet. To coordinate the above advantages, organic-inorganic composite solid electrolyte systems have been widely studied. The system is usually compounded by a polymer matrix, lithium salt and inorganic filler, and aims to have high ionic conductivity and good interface adaptability. However, polymer segment movement in such composite systems is often limited by rigid fillers, and lithium ion transport pathways are often limited to amorphous regions of the polymer or discontinuous interfaces between the filler and the polymer, resulting in higher ion transport energy barriers and limited overall conductivity enhancement. On the basis, the gel composite electrolyte formed by introducing the liquid plasticizer or the ionic liquid can promote ion migration by enhancing chain segment movement, but the residual liquid component is easy to cause continuous side reaction at a lithium negative electrode interface to form a solid electrolyte interface film with unstable structure and component, so that lithium dendrite cannot be effectively inhibited, the interface deterioration is possibly aggravated, and the long-term circulation stability is damaged. The existing composite solid electrolyte technology still has difficulty in realizing long-term stable compatibility with a lithium metal negative electrode while ensuring high ion conductivity. Therefore, developing a composite electrolyte material capable of synergistically improving bulk ion transport kinetics and electrode interface stability has become a problem to be solved in the field. Disclosure of Invention In view of the above, the present invention provides a polyoxometallate composite solid electrolyte membrane, a method for preparing the same, a solid battery, the invention combines specific polyoxometalate as a functional filler with polyion liquid to construct the solid electrolyte membrane with high room temperature ionic conductivity and excellent lithium metal interface stability. The invention provides a polyoxometallate composite solid electrolyte membrane, which comprises polyion liquid and lithium silicotungstate, wherein the polyion liquid consists of polydiallyl dimethyl ammonium cations and lithium salt anions, and the mass ratio of the lithium silicotungstate to the polyion liquid is (4-25) (75-96). Preferably, the mass ratio of the lithium silicotungstic acid to the polyion liquid is (5-20) (80-95). Preferably, the lithium salt anion is at least one selected from the group consisting of bis (trifluoromethanesulfonyl) imide, bis (fluorosulfonyl) imide, and hexafluorophosphate. Preferably, the thickness of the polyoxometalate composite solid electrolyte membrane is 50-200 mu m. In a second aspect, the present invention prov