CN-122000434-A - Lithium lanthanum zirconium oxide and polyacrylonitrile composite solid electrolyte, preparation method and application thereof, and all-solid-state battery

CN122000434ACN 122000434 ACN122000434 ACN 122000434ACN-122000434-A

Abstract

The invention belongs to the technical field of solid-state electrolytes, and particularly relates to a lithium lanthanum zirconium oxygen and polyacrylonitrile composite solid-state electrolyte, a preparation method and application thereof, and an all-solid-state battery. The preparation method comprises the following steps of 1) preparing cubic phase LLZTO powder, 2) carrying out surface silanization treatment on the cubic phase LLZTO powder under an acidic condition, 3) preparing composite electrolyte slurry from polyacrylonitrile, polyion liquid, lithium salt and cubic phase LLZTO with silanized surface at room temperature, 4) casting the composite electrolyte slurry into a film, and then carrying out vacuum drying to obtain the composite solid electrolyte of lithium lanthanum zirconium oxide and polyacrylonitrile. The LLZTO and polyacrylonitrile composite solid electrolyte provided by the invention can integrate the advantages of organic and inorganic materials, solve the problem of interface contact between traditional polyacrylonitrile and LLZTO and the anode side, and realize a stable composite structure with high voltage resistance, high temperature resistance and high ion conductivity.

Inventors

WANG YAN
WANG HONGYU
YU FAQUAN
Wang Soujun
YANG HUI

Assignees

武汉工程大学
武汉工程大学潜江绿色化工产业技术研究院

Dates

Publication Date: 20260508
Application Date: 20251231

Claims (10)

1. The preparation method of the lithium lanthanum zirconium oxide and polyacrylonitrile composite solid electrolyte is characterized by comprising the following steps of: 1) Preparing cubic LLZTO powder; 2) Carrying out surface silanization treatment on the cubic phase LLZTO powder obtained in the step 1) under an acidic condition to obtain a cubic phase LLZTO with a silanized surface; 3) Polyacrylonitrile, polyionic liquid, lithium salt and the surface silanized cubic phase LLZTO are formulated into a composite electrolyte slurry at room temperature, wherein: The mass ratio of the polyacrylonitrile to the polyionic liquid is 1:0.5-1.2; the mass ratio of the polyacrylonitrile to the lithium salt is 1:0.5-1.2; The mass of the cubic phase LLZTO with the silanized surface is 5-50% of that of the polyacrylonitrile; 4) Casting the composite electrolyte slurry obtained in the step 3) into a film, and then drying in vacuum to obtain the composite solid electrolyte of lithium lanthanum zirconium oxide and polyacrylonitrile.
2. The method for preparing a composite solid electrolyte of lithium lanthanum zirconium oxide and polyacrylonitrile according to claim 1, wherein the step 1) comprises: 1a) Mixing a lithium source, a lanthanum source and a zirconium source, grinding, and drying to obtain mixed powder; 1b) Raising the temperature of the mixed powder to 950-1050 ℃ at the temperature rise rate of 2-5 ℃ per minute under the air atmosphere, preserving the heat for 6-12 hours, and sintering to obtain a primary cubic phase LLZTO; 1c) Secondary grinding of primary cubic phase LLZTO and drying; 1d) Calcining the material obtained in the step 1C) for 4-8 hours at 1050-1150 ℃, controlling the temperature rising rate in the calcining process within 2-5 ℃ per minute, and then sequentially grinding, drying and sieving with a 200-300 mesh sieve to obtain the cubic-phase LLZTO powder.
3. The method for preparing a composite solid electrolyte of lithium lanthanum zirconium oxide and polyacrylonitrile according to claim 1, wherein the step 2) comprises: 2a) Vacuum drying the cubic LLZTO powder; 2b) Adding the cubic phase LLZTO powder obtained in the step 2 a) into acidic silane hydrolysate with the pH value of 3-5, and heating to react, wherein the solvent in the silane hydrolysate is ethanol water solution, and the volume usage ratio of ethanol to water in the ethanol water solution is 95:3-95:6; 2c) And (3) centrifugally cleaning the reaction product, drying the cleaned solid in vacuum, and then carrying out a heating reaction to fully crosslink and solidify the silane layer to obtain the cubic phase LLZTO with the silanized surface.
4. The method for preparing the lithium lanthanum zirconium oxide and polyacrylonitrile composite solid electrolyte according to claim 3, wherein the method comprises the following steps: in the step 2 b), the reaction temperature is 55-65 ℃ and the reaction time is 4-8 hours; in the step 2C), the vacuum drying temperature is 55-65 ℃ and the vacuum drying time is 4-6 hours; in step 2C), the reaction temperature is heated to 100-120 ℃ and the reaction time is 1-2 hours.
5. The method for preparing a composite solid electrolyte of lithium lanthanum zirconium oxide and polyacrylonitrile according to claim 1, wherein the step 3) comprises: 3a) Preparing polyacrylonitrile, polyion liquid and lithium salt into a polymer solution; 3b) Preparing a surface silanized cubic phase LLZTO into a suspension; 3c) And continuously stirring the polymer solution at room temperature, slowly dripping the suspension, and continuing to magnetically stir at room temperature after dripping, so as to obtain the composite electrolyte slurry.
6. The method for preparing the lithium lanthanum zirconium oxide and polyacrylonitrile composite solid electrolyte according to claim 5, wherein the method comprises the following steps: the polyion liquid is 1-butyl-3-methylimidazole bis (trifluoromethyl) sulfonyl imide salt; The lithium salt is lithium bis (trifluoromethyl) sulfonyl imide; The solvent of the polymer solution is N, N-dimethylformamide; the total mass concentration of solutes in the polymer solution is 8-12wt%; the dispersion liquid of the suspension liquid is N, N-dimethylformamide.
7. The method for preparing a composite solid electrolyte of lithium lanthanum zirconium oxide and polyacrylonitrile according to any one of claims 1 to 6, wherein the step 4) comprises: Pouring the composite electrolyte slurry into a leveling mold, placing the leveling mold in a fume hood, and standing the leveling mold at room temperature to form a primary film; And (3) vacuum drying the primary film at 55-65 ℃ for 24-48 hours to obtain the lithium lanthanum zirconium oxide and polyacrylonitrile composite solid electrolyte.
8. A lithium lanthanum zirconium oxide and polyacrylonitrile composite solid electrolyte, which is characterized in that the electrolyte is prepared by the preparation method according to any one of claims 1 to 7.
9. An all-solid-state battery comprises a positive electrode, a solid electrolyte membrane and a negative electrode, and is characterized in that the solid electrolyte membrane is made of the composite solid electrolyte of lithium lanthanum zirconium oxide and polyacrylonitrile as claimed in claim 8.
10. A method of preparing a composite solid electrolyte of lithium lanthanum zirconium oxide and polyacrylonitrile as claimed in claim 8, wherein the composite solid electrolyte is a solid electrolyte material or a quasi-solid electrolyte material.

Description

Lithium lanthanum zirconium oxide and polyacrylonitrile composite solid electrolyte, preparation method and application thereof, and all-solid-state battery Technical Field The invention belongs to the technical field of solid-state electrolytes, and particularly relates to a lithium lanthanum zirconium oxygen and polyacrylonitrile composite solid-state electrolyte, a preparation method and application thereof, and an all-solid-state battery. Background Li 6.5La3Zr1.5Ta0.5O12 (LLZTO) solid electrolyte is widely used as ceramic filler or 3D skeleton for composite solid electrolytes (CPEs) due to its high ionic conductivity, wide electrochemical window, and good stability to lithium anodes. However, garnet particles of nano-or submicron order are easily agglomerated due to the large specific surface area. In addition, the organic/inorganic interfacial incompatibility exacerbates the agglomeration of garnet particles in the polymer, which is detrimental to the ionic conductivity enhancement of CPES. Although LLZTO has a wide electrochemical window, the contact of the solid interface with the positive electrode is a very difficult problem due to its relatively large brittleness. Polyacrylonitrile (PAN) is a special polymer solid electrolyte, has stable electrochemical performance, high mechanical strength and oxidation resistance, and wide electrochemical window, and the pure PAN window can reach 4.6V, and can be matched with various high-voltage anodes. However, the ionic conductivity of PAN is lower, and generally, the pure PAN system film can only reach 10 −5Scm-1 at room temperature, meanwhile, the contact between a harder material and an electrode is insufficient, and the polar group nitrile group contained in PAN can generate stronger passivation reaction with lithium metal, so that the interface impedance is increased, and the interface compatibility is poor. PAN is difficult to process, and is brittle compared to other polymer electrolytes, which makes it prohibitive for the average researchers. From the perspective of preparing the solid electrolyte, the synthesis condition of the inorganic-organic composite solid electrolyte is relatively simple, and the method is beneficial to large-scale industrial production. The main current preparation methods of the composite electrolyte mainly comprise a solution casting method, an in-situ polymerization method, a solvent-free hot pressing method, a coating method and the like. The most common and simplest process is solution casting. The solution casting method is to cast a mixed solution containing a polymer, a lithium salt, an inorganic filler and an organic solvent on a mold, and then evaporate the solvent under vacuum and high temperature conditions to obtain a composite solid electrolyte. The process is simple and is also the preparation method with the most commercial value. Disclosure of Invention Aiming at the problems that a pure inorganic system LLZTO is poor in interface contact with a positive electrode, poor in cycle performance when being matched with various positive electrodes, and instability of a pure Polyacrylonitrile (PAN) polymer system and a lithium metal anode, and high brittleness and low ionic conductivity in the polymer system, the invention provides a lithium lanthanum zirconium oxygen and polyacrylonitrile composite solid electrolyte, a preparation method, application and an all-solid-state battery thereof. The LLZTO and polyacrylonitrile composite solid electrolyte provided by the invention can integrate the advantages of organic and inorganic materials, solve the problem of interface contact between traditional polyacrylonitrile and LLZTO and the anode side, and realize a stable composite structure with high voltage resistance, high temperature resistance and high ion conductivity. Meanwhile, the invention also solves the problems that the cyano group in the polyacrylonitrile can be subjected to cyclization reaction under the strong alkaline environment LLZTO and the room temperature condition under the action of the metal active site in the environment, the stability and the ionic conductivity of the cyclized polyacrylonitrile are improved, but the excessive cyclization can cause more difficult casting film formation of the polyacrylonitrile, and the polyacrylonitrile is easy to gel in the stirring process, irreversible in the process and greatly poor in processability. The technical scheme provided by the invention is as follows: A preparation method of a lithium lanthanum zirconium oxide and polyacrylonitrile composite solid electrolyte comprises the following steps: 1) Preparing cubic LLZTO powder; 2) Carrying out surface silanization treatment on the cubic phase LLZTO powder obtained in the step 1) under an acidic condition; 3) Polyacrylonitrile, polyionic liquid, lithium salt and surface silanized cubic phase LLZTO are formulated into a composite electrolyte slurry at room temperature, wherein: The mass ratio of the polyacry