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EP-4742353-A1 - SULFIDE-BASED SOLID ELECTROLYTE, METHOD FOR PREPARING SULFIDE-BASED SOLID ELECTROLYTE AND ALL-SOLID-STATE BATTERY INCLUDING SULFIDE-BASED SOLID ELECTROLYTE

EP4742353A1EP 4742353 A1EP4742353 A1EP 4742353A1EP-4742353-A1

Abstract

The present disclosure is directed to providing a sulfide-based solid electrolyte having improved ion conductivity, a method for preparing a sulfide-based solid electrolyte, and an all-solid-state battery including a sulfide-based solid electrolyte. The present disclosure provides a sulfide-based solid electrolyte containing a Group 3 element and having an argyrodite-type crystal structure, the sulfide-based solid electrolyte being represented by the chemical formula of Li 7-x-3y M y PS 6-x Ha x , wherein M is at least one element selected from Group 3 elements, Ha is at least one element selected from halogen elements, and x and y satisfy 1.0 < x < 2.5 and 0 < y ≤ 0.2.

Inventors

  • NARIMATSU, Eiichiro
  • MATSUBARA, KEIKO

Assignees

  • LG Energy Solution, Ltd.

Dates

Publication Date
20260513
Application Date
20241227

Claims (9)

  1. A sulfide-based solid electrolyte containing a Group 3 element and having an argyrodite-type crystal structure, the sulfide-based solid electrolyte being represented by the chemical formula of Li 7-x-3y M y PS 6-x Ha x , wherein M is at least one element selected from Group 3 elements, Ha is at least one element selected from halogen elements, and x and y satisfy 1.0 < x < 2.5 and 0 < y ≤ 0.2.
  2. The sulfide-based solid electrolyte according to claim 1, wherein M is Y and 0 < y < 0.2.
  3. The sulfide-based solid electrolyte according to claim 1, Wherein M is La.
  4. The sulfide-based solid electrolyte according to claim 2 or 3, wherein y satisfies 0 < y < 0.05.
  5. The sulfide-based solid electrolyte according to claim 1, wherein Ha comprises Br.
  6. The sulfide-based solid electrolyte according to claim 1, wherein x satisfies 1.3 ≤ x ≤ 2.0.
  7. The sulfide-based solid electrolyte according to claim 1, which has a lattice volume of 940-980 Å 3 .
  8. A method for preparing the sulfide-based solid electrolyte as defined in claim 1, comprising the steps of: mixing a lithium source, a Group 3 element source, a phosphorus source and a halogen source to obtain a mixture, and firing the mixture at a temperature of 250-600°C.
  9. An all-solid-state battery comprising a positive electrode, a negative electrode and a solid electrolyte layer, wherein the solid electrolyte layer comprises the sulfide-based solid electrolyte as defined in claim 1.

Description

TECHNICAL FIELD The present disclosure relates to a sulfide-based solid electrolyte, a method for preparing a sulfide-based solid electrolyte, and an all-solid-state battery including a sulfide-based solid electrolyte. This application is based on and claims priority from Japanese Patent Application No. 2023-221544 filed on December 27, 2023, the disclosure of which is incorporated herein in its entirety by reference. BACKGROUND ART Development of all-solid-state batteries using a solid electrolyte substituting for a liquid electrolyte of lithium-ion batteries has been conducted in order to provide batteries with high safety, long service life and high energy density. Among many types of solid electrolytes, a sulfide-based solid electrolyte, such as Li10GeP2S12, has high ion conductivity close to the ion conductivity of a liquid electrolyte and is soft, and thus is advantageous in that it is easy to obtain close adhesive property to an active material. Therefore, commercialization of all-solid-state batteries using a sulfide-based solid electrolyte has been expected. Since lithium metal can increase energy density per weight (Wh/kg) by virtue of its low weight per unit volume and high theoretical capacity, it has been given many attentions as a negative electrode material of an all-solid-state battery. However, a sulfide-based solid electrolyte, such as Li10GeP2S12, has low stability to lithium metal, and thus is problematic in that it has a difficulty in using together with a lithium metal negative electrode. To solve the above-mentioned problem, Patent documents 1 to 3 disclose a sulfide-based solid electrolyte which has an argyrodite-type crystal structure represented by Li7-x-2yPS6-x-yClx and is stable against lithium metal. Patent document 4 discloses a sulfide-based solid electrolyte having improved stability to lithium metal by precisely controlling the composition of a sulfide-based solid electrolyte having a crystal structure represented by Li10GeP2S12. However, according to the related art, there is a problem in that the sulfide-based solid electrolytes have low ion conductivity. DISCLOSURE Technical Problem The present disclosure is directed to providing a sulfide-based solid electrolyte having improved ion conductivity, a method for preparing a sulfide-based solid electrolyte, and an all-solid-state battery including a sulfide-based solid electrolyte. Technical Solution In one aspect of the present disclosure, there is provided a sulfide-based solid electrolyte containing a Group 3 element and having an argyrodite-type crystal structure,the sulfide-based solid electrolyte being represented by the chemical formula of Li7-x-3yMyPS6-xHax,wherein M is at least one element selected from Group 3 elements, Ha is at least one element selected from halogen elements, and x and y satisfy 1.0 < x < 2.5 and 0 < y ≤ 0.2. According to an embodiment, M may be Y and 0 < y < 0.2. According to an embodiment, M may be La. According to an embodiment, y may satisfy 0 < y < 0.05. According to an embodiment, Ha may include Br. According to an embodiment, x may satisfy 1.3 ≤ x ≤ 2.0. According to an embodiment, the sulfide-based solid electrolyte may have a lattice volume of 940-980 Å3. In another aspect of the present disclosure, there is provided a method for preparing the sulfide-based solid electrolyte as defined in any one of the above-described embodiments, including the steps of: mixing a lithium source, a Group 3 element source, a phosphorus source, a sulfur source and a halogen source to obtain a mixture, andfiring the mixture at a temperature of 250-600°C. In still another aspect of the present disclosure, there is provided an all-solid-state battery including a positive electrode, a negative electrode and a solid electrolyte layer, wherein the solid electrolyte layer includes the sulfide-based solid electrolyte as defined in any one of the above-described embodiments. Advantageous Effects The present disclosure can provide a sulfide-based solid electrolyte having improved ion conductivity, a method for preparing a sulfide-based solid electrolyte, and an all-solid-state battery including a sulfide-based solid electrolyte. DESCRIPTION OF DRAWINGS FIG. 1 is an X-ray diffractometry (XRD) pattern of each of Examples 1 to 3 and Comparative Examples 1 and 2.FIG. 2 is an XRD pattern of each of Examples 4 to 7 and Comparative Example 2.FIG. 3 is a graph illustrating lithium-ion conductivity depending on the composition of a sulfide-based solid electrolyte. BEST MODE Hereinafter, the present disclosure will be described in more detail. It should be understood that the terms used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. [So