Sulfide-based solid electrolyte for lithium ion cell, and solid electrolyte compound

• US 9,899,702 B2
• Filed: 12/25/2015
• Issued: 02/20/2018
• Est. Priority Date: 12/26/2014
• Status: Active Grant

• Current Assignee: Mitsui Mining and Smelting Company Limited
• Original Assignee: Mitsui Mining and Smelting Company Limited
• Inventors: Miyashita, Norihiko, Chikumoto, Takashi, Aoki, Tatsuya, Ide, Hitohiko, Matsuzaki, Kenji
• Primary Examiner(s): Crepeau, Jonathan
• Application Number:
  US15/538,667
• Publication Number:
  US 20170352916A1
• Time in Patent Office: 788 Days
• Field of Search: None
• CPC Class Codes: C01B 25/14 Sulfur, selenium, or tellurium compounds of phosphorus
• CPC Class Codes: H01B 1/06 mainly consisting of other non-metallic substances
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/0562 Solid materials
• CPC Class Codes: H01M 2300/0068 inorganic
• CPC Class Codes: H01M 4/38 of elements or alloys
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• CPC Class Codes: H01M 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 4/62 Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Relating to a sulfide-based solid electrolyte compound for lithium ion batteries which has a cubic argyrodite-type crystal structure, to provide a compound which can suppress a generation amount of hydrogen sulfide when being left to stand in the air and which can maintain high conductivity even when being left to stand in dry air. Proposed is a sulfide-based solid electrolyte compound for lithium ion batteries containing a crystal phase of the cubic argyrodite-type crystal structure and represented by a composition formula (1): Li_7−x+yPS_6−xCl_x+y, wherein x and y in the composition formula (1) satisfy 0.05≦y≦0.9 and −3.0x+1.8≦y≦−3.0x+5.7.

Claims

1. A sulfide-based solid electrolyte compound for a lithium ion battery comprising a crystal phase of a cubic argyrodite-type crystal structure, and

being represented by a composition formula (1):

Li<sub>7−

x+y</sub>PS<sub>6−

x</sub>Cl_x+y, wherein x and y in the composition formula (1) satisfy 0.05≦

y≦

0.9 and −

3.0x+1.8≦

y≦

−

3.0x+5.7.

2. The sulfide-based solid electrolyte compound for a lithium ion battery according to claim 1, wherein x and y in the composition formula (1) satisfy 0.05≦

y≦

0.4 and −

3.0x+3.9≦

y≦

−

3.0x+5.7.

3. A solid electrolyte comprising the sulfide-based solid electrolyte compound for a lithium ion battery according to claim 1.

4. The solid electrolyte according to claim 3 comprising a single phase of the crystal phase of the cubic argyrodite-type crystal structure.

5. The solid electrolyte according to claim 3 comprising the crystal phase of the cubic argyrodite-type crystal structure and a crystal phase which is represented by LiCl.

6. The solid electrolyte according to claim 3,

wherein, in an X-ray diffraction pattern, a ratio [I_L/(200)/I_A(220)] of a peak intensity I_L(200) of a (200) plane of the LiCl crystal phase with respect to a peak intensity I_A(220) of a (220) plane of the cubic argyrodite-type crystal phase is 0.30 or less.

7. A method for producing the sulfide-based solid electrolyte compound for a lithium ion battery having the solid electrolyte according to claim 3,

wherein 38.8 to 72.0 parts (mol %) of lithium sulfide (Li₂S) powder, 10.2 to 12.4 parts (mol %) of diphosphorus pentasulfide (P₂S₅) powder, and 15.6 to 51.0 parts (mol %) of lithium chloride (LiCl) powder are mixed, and

the resultant mixture is calcined at 350 to 500 C under an inert atmosphere, or at 350 to 550 C under an atmosphere comprising a hydrogen sulfide gas.

8. A lithium ion battery comprising the solid electrolyte according to claim 3.

9. A lithium ion battery comprising the solid electrolyte according to claim 3, and a negative electrode active material containing carbon or silicon.

10. An application method of a lithium ion battery comprising

the solid electrolyte according to claim 3,

a negative electrode active material containing silicon, and

a positive electrode active material containing a lithium composite oxide,

wherein, in charge and discharge cycles, a termination voltage in a first charging is set to be higher than a termination voltage in a second or later charging.

11. A solid electrolyte comprising the sulfide-based solid electrolyte compound for a lithium ion battery according to claim 2.

12. The solid electrolyte according to claim 11 comprising a single phase of the crystal phase of the cubic argyrodite-type crystal structure.

13. The solid electrolyte according to claim 11 comprising the crystal phase of the cubic argyrodite-type crystal structure and a crystal phase which is represented by LiCl.

14. The solid electrolyte according to claim 11,

wherein, in an X-ray diffraction pattern, a ratio [I_L(200)/I_A(220)] of a peak intensity I_L(200) of a (200) plane of the LiCl crystal phase with respect to a peak intensity I_A(220) of a (220) plane of the cubic argyrodite-type crystal phase is 0.30 or less.

15. A lithium ion battery comprising the solid electrolyte according to claim 4.

16. A lithium ion battery comprising the solid electrolyte according to claim 5.

17. A lithium ion battery comprising the solid electrolyte according to claim 6.

18. A lithium ion battery comprising the solid electrolyte according to claim 11.