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US-20260128363-A1 - SULFIDE SOLID ELECTROLYTE MANUFACTURING METHOD

US20260128363A1US 20260128363 A1US20260128363 A1US 20260128363A1US-20260128363-A1

Abstract

Provided is a method for producing a sulfide solid electrolyte, the method including a first step of mixing a raw material-containing substance that contains a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom in an organic solvent to prepare a mixture, a second step of irradiating the mixture with a microwave of 0.5 to 700 W/g to heat the mixture to 50 to 360° C., and a third step of cooling the mixture to 20 to 70° C., the second and third steps being repeated 2 to 50 times. In the method for producing a sulfide solid electrolyte, a liquid phase method is adopted with a lowered heating temperature, and a sulfide solid electrolyte that has a particle size maintained by suppressing granulation caused by heating and further has a high quality can be efficiently produced.

Inventors

  • Yoshikatsu Seino
  • Yasunobu Kaneko

Assignees

  • IDEMITSU KOSAN CO.,LTD.

Dates

Publication Date
20260507
Application Date
20230928
Priority Date
20221007

Claims (12)

  1. 1 . A method for producing a sulfide solid electrolyte, the method comprising a first step of mixing a raw material-containing substance that contains a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom in an organic solvent to prepare a mixture, a second step of irradiating the mixture with a microwave of 0.5 to 700 W/g to heat the mixture to 50 to 360° C., and a third step of cooling the mixture to 20 to 70° C., the second and third steps being repeated 2 to 50 times.
  2. 2 . The method for producing a sulfide solid electrolyte according to claim 1 , the method comprises, after the second step, a temperature keeping step of irradiating the mixture with a microwave to keep a temperature of 80 to 360° C. for 1 to 300 minutes, which is followed by the third step.
  3. 3 . The method for producing a sulfide solid electrolyte according to claim 1 , wherein the organic solvent has a dielectric loss factor at 25° C. of 10.0 or less.
  4. 4 . The method for producing a sulfide solid electrolyte according to claim 1 , wherein the organic solvent has a boiling point of 50° C. or higher.
  5. 5 . The method for producing a sulfide solid electrolyte according to claim 1 , wherein the organic solvent is an aromatic solvent.
  6. 6 . The method for producing a sulfide solid electrolyte according to claim 1 , wherein the raw material-containing substance is contained in the mixture in an amount of 1% by mass or more and 20% by mass or less.
  7. 7 . The method for producing a sulfide solid electrolyte according to claim 1 , wherein in the second step, the mixture is irradiated with a microwave of 130 to 700 W/g.
  8. 8 . The method for producing a sulfide solid electrolyte according to claim 1 , wherein in the second step, the mixture is heated to 150 to 360° C.
  9. 9 . The method for producing a sulfide solid electrolyte according to claim 2 , wherein in the temperature keeping step, the mixture is kept at a temperature of 150 to 360° C.
  10. 10 . The method for producing a sulfide solid electrolyte according to claim 2 , wherein in the temperature keeping step, the mixture is kept at the temperature for 1 to 240 minutes.
  11. 11 . The method for producing a sulfide solid electrolyte according to claim 1 , wherein the second and third steps are repeated 2 to 20 times.
  12. 12 . The method for producing a sulfide solid electrolyte according to claim 1 , wherein the sulfide solid electrolyte is a crystalline sulfide solid electrolyte having an argyrodite-type crystal structure.

Description

TECHNICAL FIELD The present invention relates to a method for producing a sulfide solid electrolyte. BACKGROUND ART With rapid spread of information-related devices, communication devices, and so on, such as personal computers, video cameras, and mobile phones, in recent years, development of batteries that are utilized as a power source therefor is considered to be important. Above all, from the viewpoint of high energy density, lithium ion batteries attract attention. Since an electrolytic solution containing a flammable organic solvent has heretofore been used in batteries to be used for such an application, it has been required to install a safety unit that suppresses temperature rising in short circuit and to improve the structure and material for preventing short circuit. Against the background, development of a battery having a solid electrolyte layer in place of an electrolytic solution is being made in view of the fact that by replacing an electrolytic solution with a solid electrolyte to make the battery fully solid, simplification of a safety unit can be achieved without using a flammable organic solvent within the battery and the battery is excellent in manufacturing costs and productivity. Methods for producing a solid electrolyte to be used in a solid electrolyte layer are roughly divided into solid phase methods and liquid phase methods, and the liquid phase methods include homogeneous methods in which solid electrolyte materials are completely dissolved in a solvent and heterogeneous methods in which solid electrolyte materials are not completely dissolved but a suspension in which solid and liquid coexist is used. For example, as a solid phase method, a method is known in which raw materials, such as lithium sulfide and diphosphorus tetrasulfide, are subjected to a mechanical milling treatment with an apparatus, such as a ball mill or a bead mill, and are subjected to a heat treatment as needed, to produce an amorphous or crystalline solid electrolyte (see, for example, PTL 1). As a homogeneous method among the liquid phase methods, a method is known in which a solid electrolyte is dissolved in a solvent and then, is re-precipitated (see, for example, PTL 2). As a heterogeneous method, a method is known in which solid electrolyte raw materials such as lithium sulfide are reacted in a solvent containing a polar aprotic solvent (see, for example, PTLs 3 and 4, and NPL 1). In addition, as a method for producing a solid electrolyte, PTL 5 and NPLs 2 and 3 disclose production of an amorphous electrolyte having a composition of Li3PS4 by irradiating lithium sulfide and diphosphorus pentasulfide with a microwave in an organic solvent. CITATION LIST Patent Literature PTL 1: WO 2017/159667PTL 2: JP 2014-191899 APTL 3: WO 2014/192309PTL 4: WO 2018/054709PTL 5: JP 2020-15661 A Non-Patent Literature NPL 1: “CHEMISTRY OF MATERIALS”, 2017, No. 29, p. 1830-1835NPL 2: “Journal of Materials Chemistry A”, 2018, No. 6, p. 21261-21265NPL 3: “Journal of Materials Chemistry A”, 2018, No. 9, p. 400-405 SUMMARY OF INVENTION Technical Problem The present invention has been made in view of such a situation, and has an object to provide a method for producing a sulfide solid electrolyte in which a liquid phase method is adopted with a lowered heating temperature and by which a sulfide solid electrolyte that has a particle size maintained by suppressing granulation caused by heating and further has a high quality can be efficiently produced. Solution to Problem The method for producing a sulfide solid electrolyte according to the present invention is a method for producing a sulfide solid electrolyte, the method including a first step of mixing a raw material-containing substance that contains a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom in an organic solvent to prepare a mixture, a second step of irradiating the mixture with a microwave of 0.5 to 700 W/g to heat the mixture to 50 to 360° C., and a third step of cooling the mixture to 20 to 70° C., the second and third steps being repeated two to 50 times. Advantageous Effects of Invention According to the present invention, it is possible to provide a method for producing a sulfide solid electrolyte in which a liquid phase method is adopted with a lowered heating temperature and by which a sulfide solid electrolyte that has a particle size maintained by suppressing granulation caused by heating and further has a high quality can be efficiently produced. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows an X-ray diffraction spectrum of a sulfide solid electrolyte obtained in Example 1. FIG. 2 shows an X-ray diffraction spectrum of a sulfide solid electrolyte obtained in Example 2. FIG. 3 shows an X-ray diffraction spectrum of a sulfide solid electrolyte obtained in Example 3. FIG. 4 shows an X-ray diffraction spectrum of a sulfide solid electrolyte obtained in Example 4. FIG. 5 shows an X-ray diffraction spectrum of a sulfide solid electrolyte obtaine