Lithium ion conductive sulfide-based solid electrolyte with controlled halogen elements content and method of preparing the same

Patent metadata

Field	Value
Publication number	US-11329314-B2
Application number	US-201916596659-A
Country	US
Kind code	B2
Filing date	Oct 8, 2019
Priority date	May 8, 2019
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

Disclosed are a sulfide-based solid electrolyte imparted with improved lithium ion conductivity and a method of preparing the same. More particularly, disclosed is a sulfide-based solid electrolyte containing a lithium element (Li), a phosphorus element (P), a sulfur element (S) and a halogen element (X), and including a crystal phase of an argyrodite crystal structure, wherein a molar ratio (X/P) of the halogen element (X) to the phosphorus element (P) is higher than 1.

First claim

What is claimed is:

1. A sulfide-based solid electrolyte comprising a lithium element (Li), a phosphorus element (P), a sulfur element (S) and a halogen element (X), and comprising a crystal phase having an argyrodite crystal structure,
wherein a molar ratio (X/P) of the halogen element (X) to the phosphorus element (P) is higher than 1,
three main peaks are found in a 31 P-NMR spectrum,
the three main peaks comprise Peak 1 found at about 75 ppm, Peak 2 found at about 77 ppm and Peak 3 found at about 79 ppm, and

area ratios of the three main peaks are 42%<Peak 1<60%, 21%<Peak 2<28%, and 12%<Peak 3<31%, respectively.

2. The sulfide-based solid electrolyte according to claim 1 , wherein the sulfide-based solid electrolyte comprises a compound represented by the following Formula 1:
Li 7−a PS 6−a X a   [Formula 1]

wherein X is a halogen element selected from the group consisting of chlorine (Cl), bromine (Br), iodine (I) and a combination thereof, and a satisfies 1<a<2.5.

3. The sulfide-based solid electrolyte according to claim 2 , wherein the sulfide-based solid electrolyte has major peaks at 2θ=26°±1.00°, 2θ=30°±1.00°, and 2θ=32°±1.00° when measuring X-ray diffraction patterns using CuKα rays, and
a 2θ value of each peak increases by 0.5° or less as a increases.

4. The sulfide-based solid electrolyte according to claim 2 , wherein, as a increases, a full width at half maximum (FWHM) of a peak of PS 4 3− increases,
wherein the full width at half maximum is 11.0 cm −1 to 12.5 cm −1 .

5. The sulfide-based solid electrolyte according to claim 4 , wherein the sulfide-based solid electrolyte has a wave number of the peak of PS 4 3− , of 429 cm −1 to 430 cm −1 .

6. The sulfide-based solid electrolyte according to claim 2 , wherein, in a 7 Li-NMR spectrum, a full width at half maximum of a main peak decreases as a increases and the full width at half maximum is within a range of 0.4 ppm to 0.5 ppm.

7. The sulfide-based solid electrolyte according to claim 1 , wherein the sulfide-based solid electrolyte comprises a compound represented by the following Formula 2:
Li 6 PS 5 X b   [Formula 2]

wherein X is a halogen element selected from the group consisting of chlorine (Cl), bromine (Br), iodine (I) and a combination thereof, and b satisfies 1<b<2.5.

8. The sulfide-based solid electrolyte according to claim 7 , wherein the sulfide-based solid electrolyte has major peaks at 2θ=26°±1.00°, 2θ=30°±1.00°, and 2θ=32°±1.00° when measuring X-ray diffraction patterns using CuKα rays, and
a 2θ value of each peak increases by 0.2° or less as b increases.

9. The sulfide-based solid electrolyte according to claim 7 ,
wherein the sulfide-based solid electrolyte has major peaks at 2θ=26°±1.00°, 2θ=30°±1.00°, and 2θ=32°±1.00° when measuring X-ray diffraction patterns using CuKα rays,
as b increases, a diffraction intensity ratio [I (222) /I (311) ] decreases, wherein I (311) represents a diffraction intensity of the peak at 2θ=30°±1.00° and I (222) represents a diffraction intensity of the peak at 2θ=32°±1.00°, and
the diffraction intensity ratio [I (222) /I (311) ] is 68% to 78%.

10. The sulfide-based solid electrolyte according to claim 7 , wherein, as b increases, a full width at half maximum (FWHM) of a peak of PS 4 3− obtained by Raman spectroscopy increases and the full width at half maximum is 9.3 cm −1 to 12 cm −1 .

11. The sulfide-based solid electrolyte according to claim 10 , wherein the sulfide-based solid electrolyte has a wave number of the peak of PS 4 3− , of 426 cm −1 to 429.5 cm −1 .

12. The sulfide-based solid electrolyte according to claim 7 , wherein, in a 7 Li-NMR spectrum, a full width at half maximum of a main peak is within a range of 0.515 ppm to 0.530 ppm.

13. The sulfide-based solid electrolyte according to claim 7 , wherein three main peaks are found in a 31 P-NMR spectrum and area ratios of the three main peaks are 15%<Peak 1<35%, 25%<Peak 2<38% and 38%<Peak 3<50%, respectively.

14. A method for preparing a sulfide-based solid electrolyte comprising:
preparing a mixture comprising lithium sulfide (Li 2 S), diphosphorus pentasulfide (P 2 S 5 ) and lithium halide (LiX);
pulverizing the mixture; and
heat-treating the pulverized mixture,
wherein the sulfide-based solid electrolyte comprises a lithium element (Li), a phosphorus element (P), a sulfur element (S) and a halogen element (X), and comprises a crystal phase having an argyrodite crystal structure,
wherein a molar ratio (X/P) of the halogen element (X) to the phosphorus element (P) is higher than 1,
three main peaks are found in a 31P-NMR spectrum,
the three main peaks comprise Peak 1 found at about 75 ppm, Peak 2 found at about 77 ppm and Peak 3 found at about 79 ppm, and

area ratios of the three main peaks are 42%<Peak 1<60%, 21%<Peak 2<28%, and 12%<Peak 3<31%, respectively.

15. The method according to claim 14 , wherein the sulfide-based solid electrolyte comprises a compound represented by the following Formula 1 or 2:
Li 7−a PS 6−a X a   [Formula 1]

wherein X is a halogen element selected from the group consisting of chlorine (Cl), bromine (Br), iodine (I) and a combination thereof, and a satisfies 1<a<2.5,
Li 6 PS 5 X b   [Formula 2]

wherein X is a halogen element selected from the group consisting of chlorine (Cl), bromine (Br), iodine (I) and a combination thereof, and b satisfies 1<b<2.5.

16. The method according to claim 14 , wherein the mixture comprises 44 mol % to 50 mol % of lithium sulfide, 9 mol % to 15 mol % of phosphorus pentasulfide, and 38 mol % to 43 mol % of lithium halide.

17. The method according to claim 14 , wherein the mixture further comprises elemental sulfur (S),
wherein the mixture comprises 35 mol % to 55 mol % of lithium sulfide, 9 mol % to 15 mol % of phosphorus pentasulfide, 3 mol % to 15 mol % of elemental sulfur and 30 mol % to 50 mol % of lithium halide.

18. The method according to claim 14 , wherein the mixture is pulverized by applying a G-force of 40 G or more to the mixture.

19. The method according to claim 14 , wherein the pulverized mixture is heat-treated at a temperature of 300° C. to 600° C. for 10 seconds to 10 hours.

Assignees

• Korea Inst Sci & Tech

Inventors

• Kim Hyoung Chul
• Kim Byung Kook
• Jung Hun Gi
• Chung Kyung Yoon
• Lee Jong Ho
• Lee Hae Weon
• Son Ji Won
• Jung Eu Deum
• Kim Ji Su
• Choi Sung Jun

Classifications

• H01M10/052

  Li-accumulators · CPC title

• C01P2002/86

  by NMR- or ESR-data · CPC title

• H01M2300/0068

  inorganic · CPC title

• H01M2300/008

  Halides · CPC title

• H01B1/10

  sulfides · CPC title