Solid electrolyte, and method for producing same

Patent metadata

Field	Value
Publication number	US-12404173-B2
Application number	US-202117636312-A
Country	US
Kind code	B2
Filing date	Mar 18, 2021
Priority date	Apr 1, 2020
Publication date	Sep 2, 2025
Grant date	Sep 2, 2025

Abstract

The present disclosure relates to a novel material used as a solid electrolyte for an all-solid-state battery. Particularly, the present disclosure relates to a sulfide-based solid electrolyte including lithium, sulfur, phosphorus and zinc elements, and a method for preparing the same.

First claim

What is claimed is:

1. A sulfide-based solid electrolyte comprising a compound represented by the following Chemical Formula 1 or Chemical Formula 2:
Li x Zn y P z S 6   [Chemical Formula 1]

wherein 1≤x≤4, 0<y≤2, and 0<z≤3;
Li 2+2k Zn 1−k P 2 S 6   [Chemical Formula 2]

wherein 0≤k<1;
wherein the compound has a crystal structure satisfying the following conditions (a)-(c):
(a) a space group that belongs to P31m (No. 162);
(b) unit cell parameters of a=6.03±0.5 Å and c=6.59±0.5 Å; and
(c) crystallographic coordinates of cations occupying 2c, 2d and 2e coordinates in a unit cell with a site occupancy of each coordinate of larger than 0 and equal to or less than 1, and a crystallographic coordinate of anions occupying 6k coordinate in a unit cell with a site occupancy of 6k of larger than 0 and equal to or less than 1, wherein each of the coordinates represents the following:
2c (⅓, ⅔, 0);
2d (⅓, ⅔, ½);
2e (0, 0, z), wherein 0.30≤z≤0.33; and
6k (x, 0, z), wherein 0.325≤x≤0.35 and 0.23≤z≤0.28.

2. The sulfide-based solid electrolyte according to claim 1 , which comprises a compound represented by the following Chemical Formula 1:
Li x Zn y P z S 6   [Chemical Formula 1]

wherein 1≤x≤4,0<y≤2, and 0<z≤3.

3. The sulfide-based solid electrolyte according to claim 1 , which comprises a compound represented by the following Chemical Formula 2:
Li 2+2k Zn 1−k P 2 S 6   [Chemical Formula 2]

wherein 0≤k<1.

4. The sulfide-based solid electrolyte according to claim 1 , which shows peaks at the following positions, as analyzed by powder X-ray diffractometry (XRD) using Cu-Kα rays with an X-ray wavelength of 1.5406 Å and 1.5444 Å:
12-14° 2θ;
16-18° 2θ;
25-26° 2θ;
30-33° 2θ;
39-41° 2θ; and
50-53° 2θ.

5. The sulfide-based solid electrolyte according to claim 1 , wherein each of the coordinates represents the following:
2c (⅓, ⅔, 0);
2e (0, 0, 0.3273); and
6k (0.3301, 0, 0.2565).

6. The sulfide-based solid electrolyte according to claim 1 , which has an average particle diameter (D 50 ) of 1-20 μm.

7. The sulfide-based solid electrolyte according to claim 1 , wherein k is 0-0.75, and the sulfide-based solid electrolyte has an ion conductivity of 1×10 −6 to 15×10 −6 S/cm.

8. A method for preparing a sulfide-based solid electrolyte according to claim 1 , comprising:
(S 1 ) mixing lithium sulfide (Li 2 S), zinc sulfide (ZnS), a phosphorus (P) compound and a sulfur(S) compound to obtain a mixture; and
(S 2 ) heat treating the mixture to obtain a crystalline or vitreous solid electrolyte comprising a compound represented by the following Chemical Formula 1 or Chemical Formula 2:
Li x Zn y P z S 6   [Chemical Formula 1]

wherein 1≤x≤4, 0<y≤2, and 0<z≤3;
Li 2+2k Z n1−k P 2 S 6   [Chemical Formula 2]

wherein 0≤k<1.

9. The method for preparing a sulfide-based solid electrolyte according to claim 8 , wherein lithium sulfide and zinc sulfide are used at a molar ratio of 2+2k: 1−k wherein 0≤k<1.

10. The method for preparing a sulfide-based solid electrolyte according to claim 9 , wherein k is 0-0.75, and the sulfide-based solid electrolyte has an ion conductivity of 1×10 −6 to 15×10 −6 S/cm.

11. The method for preparing a sulfide-based solid electrolyte according to claim 8 , which further comprises a step of pelletizing the mixture between step (S 1 ) and step (S 2 ).

12. The method for preparing a sulfide-based solid electrolyte according to claim 8 , which is carried out under vacuum or under inert gas atmosphere.

13. An all-solid-state battery comprising: a positive electrode; a negative electrode; and an electrolyte layer interposed between the positive electrode and the negative electrode, wherein at least one of the positive electrode, the negative electrode and the electrolyte layer includes the sulfide-based solid electrolyte as defined in claim 1 .

Assignees

• Lg Energy Solution Ltd

Inventors

• Jo Vin-Na
• Han Hyea-Eun
• Lyoo Je-Yne
• Hong Seung-Tae

Classifications

• H01M2300/0091

  in the form of mixtures · CPC title

• H01M2300/0068

  inorganic · CPC title

• H01M10/0562 Primary

  Solid materials · CPC title

• H01M10/052

  Li-accumulators · CPC title

• C01P2006/40

  Electric properties · CPC title