EP-4738513-A1 - SULFIDE ELECTROLYTE PREPARATION METHOD

EP4738513A1EP 4738513 A1EP4738513 A1EP 4738513A1EP-4738513-A1

Abstract

The present invention relates to a method of preparing a sulfide electrolyte. According to one aspect of the present invention, a method of preparing a sulfide electrolyte of the present invention includes: a moisture control step of controlling the moisture content in a solvent; a step of preparing a precursor solution by stirring a precursor and the solvent with the controlled moisture content; and a powder synthesis step of synthesizing electrolyte powder using the precursor solution.

Inventors

JEONG, Nam Yeong
LIM, HYUN TAEK
YOO, SU JEONG
LEE, SONG HEE
LEE, JI WOON
CHOI, JUNG SIK
KIM, HONG SEOK
RYU, KWANG HYUN

Assignees

Enflow Co., Ltd.

Dates

Publication Date: 20260506
Application Date: 20250404

Claims (13)

A method of preparing a sulfide electrolyte, comprising: a moisture control step of controlling a moisture content in a solvent; a step of preparing a precursor solution by stirring a precursor and the solvent with the controlled moisture content; and a powder synthesis step of synthesizing electrolyte powder using the precursor solution.
The method of claim 1, wherein the moisture control step includes: a first moisture control step of controlling moisture in a first solvent including an aprotic solvent; and a second moisture control step of controlling moisture in a second solvent including a protic solvent.
The method of claim 2, wherein, in the first moisture control step, the moisture content in the first solvent is controlled to 135 ppm or less.
The method of claim 2, wherein, in the second moisture control step, the moisture content in the second solvent is controlled to 35 ppm or less.
The method of claim 2, wherein the aprotic solvent includes at least one selected from the group consisting of acetonitrile, tetrahydrofuran, hexane, acetone, dimethyl ether, and ethyl acetate.
The method of claim 2, wherein the protic solvent is an alcohol.
The method of claim 1, wherein the moisture control step is carried out by any one method of an adsorbent method, a membrane method, an electrolysis method, or a heating distillation method.
The method of claim 2, wherein the step of preparing the precursor solution includes: a first solution preparation step of stirring a first precursor including lithium, phosphorus, and sulfur and the first solvent; a second solution preparation step of stirring a second precursor including a halogen and the second solvent; and a step of mixing the first solution and the second solution to prepare the precursor solution.
The method of claim 8, wherein the first solvent is configured to produce a seed precipitate formed by a liquid phase reaction of the first precursor, and the second solvent is configured to dissolve the seed precipitate formed by the liquid phase reaction of the first precursor.
The method of claim 1, wherein the powder synthesis step includes: a atomizing step of atomizing droplets; a transporting step of transporting the droplets to a heating furnace; and a pyrolytic synthesis step of inducing a reaction of the transported droplets within the heating furnace to synthesize electrolyte powder.
The method of claim 10, wherein the atomizing step is carried out using an ultrasonic atomizer.
The method of claim 10, wherein the transporting step includes a step of transporting the droplets using an inert gas as a carrier gas.
The method of claim 10, wherein, in the pyrolytic synthesis step, the synthesized electrolyte powder is amorphous or crystalline.

Description

[Technical Field] The present invention relates to a method of preparing a sulfide electrolyte, and more particularly, to a method of preparing a sulfide electrolyte for all-solid-state batteries. [Background Art] Lithium-ion secondary batteries are currently used not only in small electronic devices but also in medium- to large-sized devices such as electric vehicles, demonstrating a wide range of applications. Currently, extensive research is being conducted to increase the energy density and safety of lithium-ion secondary batteries. However, problems such as battery explosions and fires caused by excessive increases in energy density in high-voltage batteries continue to arise. To resolve these problems, active research is being conducted on all-solid-state batteries that utilize solid electrolytes, which offer superior heat resistance and durability compared to liquid electrolytes. Solid electrolytes include oxide-, sulfide-, and polymer-based solid electrolytes. Sulfide-based solid electrolytes have the highest ionic conductivity and offer process advantages, so extensive research is being conducted thereon. Methods of preparing solid electrolytes include solid-phase methods and liquid-phase methods. The solid-phase methods involve mixing solid starting materials using a ball mill or mixer, followed by heat treatment at high temperatures to synthesize electrolyte powder. However, controlling the particle size of the solid electrolyte is difficult, and therefore, the resulting particle size may not be uniform and ionic conductivity may be reduced. In the liquid-phase methods, solid electrolytes are prepared by dissolving various starting materials in a solvent and then synthesizing electrolyte powder through solubility reduction or hydrolysis-condensation reactions. However, the liquid-phase methods leave residual solvents during the preparation process, and some raw materials may be diluted by the residual solvent, affecting the ionic conductivity of the solid electrolytes. Therefore, the development of solid electrolyte preparation techniques that overcome the limitations of both the solid-phase and liquid-phase methods is required. Meanwhile, the above-mentioned background technology represents technical information possessed by the present inventors for the purpose of developing the present invention or acquired during the process of developing the present invention, and therefore, it may not necessarily be considered publicly known technology prior to the filing of the application of the present invention. [Disclosure] [Technical Problem] An object of one embodiment of the present invention is to provide a method of preparing a sulfide electrolyte having a low impurity content and high ionic conductivity. [Technical Solution] As a technical means for achieving the above-described technical task, according to one aspect of the present invention, a method of preparing a sulfide electrolyte includes: a moisture control step of controlling the moisture content in a solvent; a step of preparing a precursor solution by stirring a precursor and the solvent with the controlled moisture content; and a powder synthesis step of synthesizing electrolyte powder using the precursor solution. According to another aspect of the present invention, the moisture control step may include: a first moisture control step of controlling moisture in a first solvent including an aprotic solvent; and a second moisture control step of controlling moisture in a second solvent including a protic solvent. According to still another aspect of the present invention, in the first moisture control step, the moisture content in the first solvent may be controlled to 135 ppm or less. According to yet another aspect of the present invention, in the second moisture control step, the moisture content in the second solvent is controlled to 35 ppm or less. According to yet another aspect of the present invention, the aprotic solvent may include at least one selected from the group consisting of acetonitrile, tetrahydrofuran, hexane, acetone, dimethyl ether, and ethyl acetate. According to yet another aspect of the present invention, the protic solvent may be an alcohol. According to yet another aspect of the present invention, the moisture control step may be carried out by any one method of an adsorbent method, a membrane method, an electrolysis method, or a heating distillation method. According to yet another aspect of the present invention, the step of preparing the precursor solution may include: a first solution preparation step of stirring a first precursor including lithium, phosphorus, and sulfur and the first solvent; a second solution preparation step of stirring a second precursor including a halogen and the second solvent; and a step of mixing the first solution and the second solution to prepare the precursor solution. According to yet another aspect of the present invention, the first solvent may be configured to produce a