KR-20260062552-A - METHOD FOR MANUFACTURING LITHIUM ION CONDUCTIVE SULFIDE-BASED COMPOUND

Abstract

This specification relates to a method for manufacturing a lithium ion-conducting sulfide-based compound and a lithium secondary battery comprising the same. More specifically, this specification relates to a method for obtaining a sulfide-based compound having excellent electrochemical properties and atmospheric stability by improving the problem of easy degradation during grinding of a sulfide-based solid electrolyte compound having an azirodite-type crystal structure.

Inventors

• 설재창
• 권우신
• 정현수
• 양아름
• 윤의신

Assignees

• 주식회사 에코프로비엠

Dates

Publication Date

20260507

Application Date

20241029

Claims (10)

1. (a) a step of preparing a sulfide-based compound comprising a crystalline phase having an argyrodite-type crystal structure; and (b) a step of wet-grinding the sulfide-based compound to obtain particles having an average particle size of 3 μm or less; comprising, The above wet grinding is performed using a solvent with a moisture content of less than 12.0 ppm, Method for manufacturing lithium ion conductive sulfide-based compounds.
2. In paragraph 1, The crystalline phase of the above azirodite-type crystal structure is represented by the following chemical formula 1, Method for preparing lithium ion-conducting sulfide compounds: [Chemical Formula 1] Li 7-x PS 6-x X x In the above chemical formula 1, X is at least one selected from the group consisting of Cl, Br, and I, and 0≤x≤2.
3. In paragraph 1, The wet grinding of step (b) above is performed using at least one selected from the group consisting of a ball mill, a pebble mill, a rod mill, a roller mill, a colloid mill, an impact mill, a jet mill, a bead mill, a vibrating mill, a stirring mill, a disc mill, and a grinding classifier mill. Method for manufacturing lithium ion conductive sulfide-based compounds.
4. In paragraph 1, The above solvent is a compound in which one or more alkyl groups are bonded to a benzene ring, Method for manufacturing lithium ion conductive sulfide-based compounds.
5. In paragraph 1, The above solvent is purified by microfilters and molecular sieves, Method for manufacturing lithium ion conductive sulfide-based compounds.
6. In paragraph 5, The above solvent is purified by microfilter and then purified by molecular sieve, Method for manufacturing lithium ion conductive sulfide-based compounds.
7. In paragraph 5, The above microfilter has a pore size of 0.1 to 1 μm, Method for manufacturing lithium ion conductive sulfide-based compounds.
8. In paragraph 1, The proportion of particles with a particle size of 1 μm or less among the particles obtained in step (b) above is 20 weight% or more, Method for manufacturing lithium ion conductive sulfide-based compounds.
9. In paragraph 1, After step (b) above, (c) a step of separating particles having a particle size of 1 μm or less among the above particles; further comprising, Method for manufacturing lithium ion conductive sulfide-based compounds.
10. A lithium ion-conducting sulfide-based compound manufactured according to any one of claims 1 to 9, comprising Lithium secondary battery.

Description

Method for manufacturing lithium ion conductive sulfide-based compound This specification relates to a method for manufacturing a lithium ion-conducting sulfide-based compound and a lithium secondary battery comprising the same. More specifically, this specification relates to a method for obtaining a sulfide-based compound having excellent electrochemical properties and atmospheric stability by improving the problem of easy degradation during grinding of a sulfide-based solid electrolyte compound having an azirodite-type crystal structure. A battery stores electrical power by using materials capable of electrochemical reactions at the positive and negative electrodes. A representative example of such a battery is the lithium secondary battery, which stores electrical energy based on the difference in chemical potential when lithium ions intercalate or deintercalate at the positive and negative electrodes. The above lithium secondary battery is manufactured by using materials capable of reversible intercalation/deintercalation of lithium ions as positive and negative active materials, and by filling an organic electrolyte or a polymer electrolyte between the positive and negative electrodes. However, these organic or polymer electrolytes typically use flammable organic solvents. Therefore, if abnormally high temperatures occur due to internal or external factors of the lithium secondary battery, a fire or explosion may occur due to the electrolyte. Due to these safety concerns, solid-state batteries utilizing solid electrolytes are attracting attention as a substitute for liquid batteries. Solid-state batteries are expected to be commercialized as next-generation batteries with high energy density due to their high stability. Among the solid electrolytes used in lithium-ion batteries, sulfide-based solid electrolytes are currently receiving significant attention. Various crystal structures of sulfide-based solid electrolytes are known, one of which is the argyrodite-type crystal structure. However, sulfide-based solid electrolytes with an agitite-type crystal structure have problems such as high reactivity with moisture and oxygen, complex manufacturing processes, and significant variability in ionic conductivity performance. Additionally, due to the nature of solid-phase materials, micronization is essential to maximize the contact surface area; however, this grinding process leads to degradation such as amorphization and impurity formation, resulting in a decrease in ionic conductivity. Figure 1 is the result of an analysis of the critical current density and electrochemical characteristics of a sulfide-based compound according to one example of the present specification. For convenience, specific terms are defined herein to facilitate a better understanding of this specification. Unless otherwise defined herein, scientific and technical terms used in this invention shall have the meanings generally understood by those skilled in the art. Furthermore, unless specifically indicated in the context, terms in their singular form shall be understood to include their plural form, and terms in their plural form shall be understood to include their singular form. Method for manufacturing lithium ion-conducting sulfide-based compounds A method for preparing a lithium ion-conducting sulfide-based compound according to one aspect of the present specification comprises: (a) preparing a sulfide-based compound having a crystalline phase having an argyrodite-type crystal structure; and (b) wet grinding the sulfide-based compound to obtain particles having an average particle size of 3 μm or less; wherein the wet grinding may be performed using a solvent having a moisture content of less than 12.0 ppm. Step (a) above may be a step of synthesizing a lithium ion-conducting sulfide-based compound or preparing a compound prior to grinding. The above sulfide-based compound has lithium ion conductivity and can have a crystal phase with an azirodite-type crystal structure. An azirodite-type crystal structure refers to a structure identical to that of azirodite ( Ag₅GeS₆ ) , a silver-germanium-sulfur mineral. The azirodite-type crystal structure can possess orthorhombic ( Pna₂₁ ) and cubic (F₄³m) phases, among which the cubic crystal structure can exhibit high lithium ion conductivity. Typically, the azirodite-type crystal structure exhibits the cubic phase, which has excellent lithium ion conductivity at high temperatures, and the orthorhombic phase at low temperatures. For example, Li 7 PS 6 and Li 6 PS 5 X (where X is at least one of Cl, Br, and I) are known as lithium ion conductive solid electrolyte compounds having an azirodite-type crystal structure. However, the azirodite crystal structure has the problem of easily degrading performance due to sensitivity to air and humidity. Therefore, compounds having an azirodite crystal structure may experience performance degradation or easily form impurities during the manufacturin