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CN-122025751-A - High-dispersity low-crystallinity composite solid electrolyte and all-solid lithium metal battery

CN122025751ACN 122025751 ACN122025751 ACN 122025751ACN-122025751-A

Abstract

The invention relates to the technical field of batteries, in particular to a high-dispersity and low-crystallinity composite solid electrolyte and an all-solid lithium metal battery. The composite solid electrolyte comprises a polymer matrix, lithium salt, inorganic filler and quaternary ammonium salt surfactant, wherein the mass ratio of the polymer matrix to the lithium salt to the inorganic filler to the quaternary ammonium salt surfactant is 100:60-80:10-20:1-15. Through the quaternary ammonium salt additive, the uniform dispersion of the inorganic filler in the polymer matrix is realized, and the crystallinity of polyethylene oxide (PEO) is effectively reduced, so that the ion transmission performance of the electrolyte and the cycling stability of the battery are remarkably improved, the problem of incompatibility of an organic-inorganic interface between PEO and LLZTO in the composite solid electrolyte is systematically solved, and a key technical path is provided for developing a new generation of energy storage device with high safety, long cycle life and excellent electrochemical performance.

Inventors

  • LI FANGYUAN
  • QIN BINGSHENG
  • SHENG JIE
  • GAO FEI

Assignees

  • 蜂巢能源科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260327

Claims (10)

  1. 1. The high-dispersivity and low-crystallinity composite solid electrolyte is characterized by comprising a polymer matrix, lithium salt, an inorganic filler and a quaternary ammonium salt surfactant; The mass ratio of the polymer matrix to the lithium salt to the inorganic filler to the quaternary ammonium salt surfactant is 100:60-80:10-20:1-15.
  2. 2. The composite solid electrolyte according to claim 1, wherein the weight ratio of the inorganic filler to the quaternary ammonium salt surfactant is 1:5-20.
  3. 3. The composite solid state electrolyte of claim 1, wherein the inorganic filler comprises at least one of lithium lanthanum zirconium tantalum oxide, lithium indium chloride, lithium yttrium chloride, lithium zirconium chloride, lithium tantalum chloride, lithium aluminum titanium phosphorus, lithium aluminum germanium phosphorus, and lithium phosphorus sulfur chloride; and/or the polymer matrix comprises at least one of polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyvinylidene chloride and polypropylene oxide; And/or the lithium salt comprises at least one of lithium bis (trifluoromethanesulfonyl) imide, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium perchlorate, lithium bis (oxalato) borate, lithium trifluoromethanesulfonate, lithium arsenate fluoride, and lithium bis (fluorosulfonyl) imide; And/or the quaternary ammonium salt surfactant is at least one selected from tetrabutylammonium fluoride, cetyltrimethylammonium chloride, dodecyltrimethylammonium chloride, octadecyltrimethylammonium chloride and cetyltrimethylammonium bromide.
  4. 4. The composite solid state electrolyte of any one of claims 1-3, further comprising an organic solvent in the composite solid state electrolyte; The organic solvent is at least one of methanol, ethanol, isopropanol and acetonitrile.
  5. 5. An all-solid-state lithium metal battery, which is characterized by comprising an electrolyte, a negative electrode and a positive electrode, wherein the electrolyte comprises the composite solid-state electrolyte as claimed in any one of claims 1 to 4.
  6. 6. The all-solid-state lithium metal battery according to claim 5, wherein the negative electrode is a lithium metal negative electrode, preferably the metal lithium negative electrode is at least one of a metal lithium foil, a lithium sheet, a lithium alloy, a hard carbon, a titanium-based negative electrode.
  7. 7. The all-solid lithium metal battery according to claim 5 or 6, wherein the positive electrode comprises a current collector, a positive electrode active material, a binder, and a conductive agent.
  8. 8. The all-solid-state lithium metal battery according to claim 7, wherein the current collector is an aluminum foil, a carbon-coated aluminum foil, or a stainless steel foil; and/or the positive electrode active material is at least one selected from lithium iron phosphate, lithium vanadium phosphate, lithium manganate, lithium titanium chloride and lithium cobaltate; and/or the binder is at least one selected from polyvinylidene fluoride, polyamide, polyvinyl alcohol and carboxymethyl cellulose; and/or the conductive agent is at least one selected from acetylene black, ketjen black and Super P.
  9. 9. A method for preparing an all-solid-state lithium metal battery according to any one of claims 5 to 8, comprising the steps of: (1) Preparing a composite solid electrolyte; (2) Preparing a positive plate, namely coating raw materials comprising a positive electrode active material, a binder and a conductive agent on a current collector; (3) And (5) assembling.
  10. 10. The method according to claim 9, wherein the step (1) comprises mixing the inorganic filler and the quaternary ammonium salt surfactant, and adding the polymer matrix and the lithium salt.

Description

High-dispersity low-crystallinity composite solid electrolyte and all-solid lithium metal battery Technical Field The invention relates to the technical field of all-solid-state lithium metal batteries, in particular to a high-dispersity and low-crystallinity composite solid-state electrolyte and an all-solid-state lithium metal battery. Background With the increasing global demand for sustainable energy, new energy industries rapidly develop, and lithium ion batteries are one of the most widely used energy storage devices at present, and play an important role in the fields of consumer electronics, electric automobiles, large-scale energy storage and the like. However, the traditional liquid electrolyte has potential safety hazards such as inflammability, easy leakage, battery short circuit caused by lithium dendrite growth and the like, and the energy density gradually approaches the theoretical limit, so that the requirements of high energy density and high safety energy storage in the future are difficult to meet. In this context, lithium metal solid-state batteries are considered as core solutions for next-generation power batteries because of their higher theoretical specific capacity (3860 mAh-g -1), lower redox potential (-3.04 vvs. She), while solid-state electrolytes (SSE) are used as their core components, directly determining the upper limit of battery performance. The solid electrolyte widely studied at present mainly comprises three major categories of inorganic solid electrolyte, polymer solid electrolyte and organic/inorganic composite solid electrolyte. The polymer solid electrolyte includes polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, and the like. The polymer solid electrolyte using polyethylene oxide (PEO) as a matrix is the most widely studied polymer electrolyte at present, and although the polymer solid electrolyte is easy to prepare, controllable in shape, low in cost and good in flexibility, the high crystallinity at room temperature leads to insufficient ionic conductivity and narrow electrochemical window, and the commercialization requirement is difficult to meet. The polymer solid electrolyte conducts lithium ions mainly through segmental motion of non-crystalline regions, and in order to reduce crystallinity and improve ion conductivity, generally adopted means or strategies include crosslinking, block copolymer formation, plasticizer addition, inorganic filler introduction, and the like. In all of these attempts, the dispersion of an inorganic filler in a polymer matrix to synthesize an organic/inorganic composite solid electrolyte is considered as a very promising technique in solid-state lithium metal batteries. This is because the composite mode can not only effectively improve the ionic conductivity, but also improve the mechanical properties and the thermal stability of the electrolyte to a certain extent. Wherein LLZTO (Li 6.4La3Zr1.4Ta0.6O12) is used as a typical perovskite type inorganic solid electrolyte, has the characteristics of high ionic conductivity and good chemical stability, and is widely applied to modification of PEO-based composite solid electrolyte. However, a large number of hydroxyl groups exist on the surface of LLZTO, side reactions are easy to occur with the PEO matrix, and LLZTO particles are easy to agglomerate, so that the dispersibility of the particles in the PEO matrix is poor, the interface contact resistance of the formed composite solid electrolyte is large, and the ion transmission efficiency is still difficult to meet the requirements of high-performance solid batteries. In summary, the existing organic/inorganic composite solid electrolyte still has the following key problems that 1, the aggregation and dispersion of the filler are uneven, and inorganic filler is easy to agglomerate in a polymer matrix, so that the crystallinity is reduced, an ion transmission channel is discontinuous, and the uneven deposition of lithium dendrites is aggravated. 2. Poor interfacial compatibility, insufficient interfacial compatibility between the polymer and the inorganic filler, reduced interfacial contact area, reduced ion transport efficiency and increased interfacial impedance. 3. The balance between mechanical properties and electrical conductivity is that high levels of inorganic fillers, while promoting electrical conductivity, may deteriorate interfacial compatibility and initiate lithium dendrite growth. Therefore, the development of the composite solid electrolyte capable of synchronously solving the problems of poor dispersibility of the inorganic filler and high crystallinity of the polymer matrix has important significance for promoting the industrialization of solid lithium metal batteries. Disclosure of Invention Therefore, the invention aims to solve the problem of compatibility between the polymer and the inorganic filler, realize uniform dispersion of the nano filler in the polymer, further improve the performance of