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CN-121983655-A - Sulfide electrolyte material for all-solid-state lithium battery, and preparation method and application thereof

CN121983655ACN 121983655 ACN121983655 ACN 121983655ACN-121983655-A

Abstract

The invention provides a sulfide electrolyte material for an all-solid-state lithium battery, a preparation method and application thereof, and relates to the technical field of all-solid-state lithium batteries, wherein the sulfide electrolyte material has a film structure of at least three layers, and comprises an upper layer and a lower layer which are both matrix layers and an intermediate layer which is clamped between the two layers; wherein the intermediate layer comprises a composite of sulfide electrolyte and ethylene-methyl acrylate copolymer, and the substrate layer has a fiber network porous structure. The invention provides an all-solid-state sulfide electrolyte material with ultra-thin thickness and high mechanical strength, which solves the problems of low volume/weight energy density caused by large thickness and poor mechanical strength caused by thinning of the traditional sulfide electrolyte material at present.

Inventors

  • GAO RUIZHE
  • GAO YUANHONG

Assignees

  • 奇瑞汽车股份有限公司

Dates

Publication Date
20260505
Application Date
20260228

Claims (10)

  1. 1. The sulfide electrolyte material for the all-solid-state lithium battery is characterized by having a film layer structure of at least three layers, and comprising an upper layer and a lower layer which are matrix layers and an intermediate layer which is clamped between the two layers; wherein the intermediate layer comprises a composite of sulfide electrolyte and ethylene-methyl acrylate copolymer, and the substrate layer has a fiber network porous structure.
  2. 2. The sulfide electrolyte material for an all-solid-state lithium battery according to claim 1, wherein the thickness of the film layer structure is 60-80 um.
  3. 3. Sulfide electrolyte material for an all-solid-state lithium battery according to claim 1, characterized in that the bulk thickness of the intermediate layer is 15-20 μm, and the intermediate layer is at least partially embedded in the pores of the upper and lower substrate layers.
  4. 4. The sulfide electrolyte material for an all-solid-state lithium battery according to claim 1, wherein the material of the base layer includes PEVA; Preferably, the thickness of the substrate layer is 30-40um.
  5. 5. The method for producing a sulfide electrolyte material for an all-solid-state lithium battery according to any one of claims 1 to 4, comprising: (a) Mixing sulfide electrolyte with ethylene-methyl acrylate copolymer, and then performing primary pressing to obtain a mixture; (b) Placing the mixture on a substrate layer, and performing secondary pressing to form an intermediate prefabricated layer; (c) And placing another basal body layer on the middle prefabricated layer, and pressing for three times to obtain the sulfide electrolyte membrane.
  6. 6. The method according to claim 5, wherein the sulfide electrolyte is prepared by ball milling Li 2 S、P 2 S 5 and LiCl and sintering in an inert atmosphere; Preferably, the stoichiometric ratio of the Li 2 S, the P 2 S 5 , and the LiCl is 2.0-2.3:0.5:1.2-1.5; preferably, the sintering temperature is 450-550 ℃ and the time is 7-10 hours.
  7. 7. The method according to claim 5, wherein the preparation of the ethylene-methyl acrylate copolymer comprises preparing the ethylene-methyl acrylate copolymer from ethylene and methyl acrylate by free radical polymerization of the preparation under the catalysis of di-t-butyl peroxide; Preferably, the molar ratio of the ethylene to the methyl acrylate is 80-90:10-20; preferably, the temperature of the radical polymerization reaction is 270-300 ℃ and the time is 2-4 hours.
  8. 8. The method of claim 5, wherein in step (a), the weight ratio of the sulfide electrolyte to the ethylene-methyl acrylate copolymer is 93-97:3-7.
  9. 9. The method according to claim 5, wherein the primary pressing is performed at a temperature of 80 to 90 ℃ and a pressure of 180 to 220 MPa; Preferably, the temperature of the secondary pressing is 80-90 ℃ and the pressure is 180-220 MPa; preferably, the temperature of the three presses is 80-90 ℃ and the pressure is 180-220 MPa.
  10. 10. Use of the sulfide electrolyte material for an all-solid lithium battery according to any one of claims 1 to 4 or the sulfide electrolyte material for an all-solid lithium battery prepared by the preparation method according to any one of claims 5 to 9 in the preparation of an all-solid lithium battery.

Description

Sulfide electrolyte material for all-solid-state lithium battery, and preparation method and application thereof Technical Field The invention relates to the technical field of all-solid-state lithium batteries, in particular to a sulfide electrolyte material for an all-solid-state lithium battery, and a preparation method and application thereof. Background The solid-state lithium battery has high theoretical specific capacity, and sulfide electrolyte is a mainstream electrolyte material at present because of high ionic conductivity, but the film thickness is difficult to be ultrathin and has high mechanical strength. The existing traditional sulfide electrolyte material has at least the following problems of 1. Low volume/weight energy density caused by large thickness, 2. Poor mechanical strength of an ultrathin film, easy penetration by lithium dendrites or short circuit caused by cracking of the ultrathin film due to volume expansion of a negative electrode silicon material, 3. The existing method for preparing an electrolyte film uses a polytetrafluoroethylene and other binders, the existence of fluorine elements influences the environment, 4. Organic solvents are introduced into the wet film preparation, the follow-up process is difficult to completely remove, the evaporation of the solvents in the drying process easily causes cavities of an electrode microstructure, 5. The electrolyte material is reduced in ionic conductivity due to reaction with the solvents in the pulping process, so that the impedance of a full cell is increased, the electrochemical performance is reduced, 6. The sulfide electrolyte film prepared by the existing dry method is brittle, and the mechanical performance is poor. Disclosure of Invention It is an object of the present invention to provide a sulfide electrolyte material for an all-solid-state lithium battery, which solves at least one of the technical problems of the prior art. The second object of the present invention is to provide a method for preparing sulfide electrolyte material for all-solid-state lithium battery. The invention further aims to provide an application of the sulfide electrolyte material for the all-solid-state lithium battery, which is prepared by adopting the preparation method, in preparation of the all-solid-state lithium battery. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: In a first aspect, the invention provides a sulfide electrolyte material for an all-solid-state lithium battery, wherein the sulfide electrolyte material has a film structure of at least three layers, and comprises an upper layer and a lower layer which are substrate layers and an intermediate layer which is clamped between the two layers; wherein the intermediate layer comprises a composite of sulfide electrolyte and ethylene-methyl acrylate copolymer, and the substrate layer has a fiber network porous structure. Further, the thickness of the film layer structure is 60-80 um. Further, the main body thickness of the middle layer is 15-20 mu m, and at least part of particles of the middle layer are embedded into pores of the substrate layers at the upper side and the lower side. Further, the material of the matrix layer comprises PEVA; Preferably, the thickness of the substrate layer is 30-40um. In a second aspect, the present invention provides a method for preparing a sulfide electrolyte material for an all-solid-state lithium battery, comprising: (a) Mixing sulfide electrolyte with ethylene-methyl acrylate copolymer, and then performing primary pressing to obtain a mixture; (b) Placing the mixture on a substrate layer, and performing secondary pressing to form an intermediate prefabricated layer; (c) And placing another basal body layer on the middle prefabricated layer, and pressing for three times to obtain the sulfide electrolyte membrane. Further, the sulfide electrolyte is prepared by ball milling Li 2S、P2S5 and LiCl and sintering in an inert atmosphere; Preferably, the stoichiometric ratio of the Li 2 S, the P 2S5, and the LiCl is 2.0-2.3:0.5:1.2-1.5; preferably, the sintering temperature is 450-550 ℃ and the time is 7-10 hours. Further, the preparation raw materials of the ethylene-methyl acrylate copolymer comprise ethylene and methyl acrylate, and the ethylene-methyl acrylate copolymer is prepared by free radical polymerization of the preparation raw materials under the catalysis of di-tert-butyl peroxide; Preferably, the molar ratio of the ethylene to the methyl acrylate is 80-90:10-20; preferably, the temperature of the radical polymerization reaction is 270-300 ℃ and the time is 2-4 hours. Further, in step (a), the weight ratio of the sulfide electrolyte to the ethylene-methyl acrylate copolymer is 93-97:3-7. Further, the temperature of the primary pressing is 80-90 ℃ and the pressure is 180-220 MPa; Preferably, the temperature of the secondary pressing is 80-90 ℃ and the pressure is 1