Molten lithium-sulfur battery with solid electrolyte and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-10312550-B2
Application number	US-201715679383-A
Country	US
Kind code	B2
Filing date	Aug 17, 2017
Priority date	Jun 28, 2017
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

This invention relates to a lithium-sulfur battery and a method of manufacturing the same, and more particularly, to a molten salt-based lithium-sulfur battery and a method of manufacturing the same, in which a metal foam including lithium or a lithium alloy, as an anode active material, and sulfur or metal sulfide, as a cathode active material, is used as a support and a current collector, and a solid-state electrolyte is used to thus improve energy density and power output characteristics.

First claim

What is claimed is:

1. A method of manufacturing a molten lithium-sulfur battery, the method comprising manufacturing a cathode,
wherein the manufacturing the cathode comprises:
a first step of adding a cathode active material to a metal foam by immersing the metal foam in molten sulfur;
a second step of subjecting a surface of the metal foam to sulfuration through heat treatment of the surface of the metal foam, which is obtained from the first step, in a sealed metal container; and
a third step of additionally adding the cathode active material to the metal foam, which is obtained from the second step, by further immersing the metal foam in molten sulfur,
wherein the molten lithium-sulfur battery includes:
a sealed case;
a solid electrolyte;
a conductive metal foam having a plurality of pores;
an anode using the metal foam and using lithium (Li) or a lithium alloy as an active material being accommodated into the metal foam; and
a cathode using the metal foam and using sulfur (S) or a sulfide as an active material.

2. The method of claim 1 , wherein in the first step, the molten sulfur has a temperature of 150 to 200° C.

3. The method of claim 1 , wherein the heat treatment in the sealed metal container is performed at 400 to 600° C.

4. The method of claim 1 , wherein the third step comprises impregnating the metal foam with molten sulfur.

5. The method of claim 4 , wherein in the third step, the impregnating is performed at a temperature of 150 to 200° C.

6. The method of claim 1 , wherein the third step is performed by injecting a slurry comprising a sulfur (S) powder or an iron disulfide (FeS 2 ) powder into the metal foam.

7. The method of claim 1 , wherein an anode is manufactured by immersing or incorporating the metal foam in lithium (Li) that is melted through heating to a predetermined temperature.

8. The method of claim 7 , wherein the lithium is heated to 200 to 500° C.

9. The method of claim 1 , wherein an anode is manufactured by injecting a slurry comprising a lithium (S) powder or a lithium alloy (LiSi) powder into the metal foam at room temperature.

10. The method of claim 1 , wherein the solid electrolyte is interposed between the cathode and the anode and is manufactured through hot pressing.

11. The method of claim 10 , wherein the solid electrolyte is manufactured by sequentially layering an atmosphere-adjusting powder, a multilayered electrolyte powder, and the atmosphere-adjusting powder.

12. The method of claim 11 , wherein the atmosphere-adjusting powder is composed of a material that is the same as a material of the solid electrolyte.

13. The method of claim 12 , wherein the atmosphere-adjusting powder comprises a lithium-rich powder.

14. The method of claim 11 , wherein a graphite sheet is disposed between individual layers comprising powder in order to separate the individual layers upon manufacturing the solid electrolyte.

15. The method of claim 10 , wherein a molten salt film is disposed between the metal foam and the solid electrolyte.

16. The method of claim 15 , wherein the molten salt film is manufactured through powder compaction.

17. The method of claim 15 , wherein the molten salt film comprises a lithium-based eutectic salt and an ionic liquid.

18. The method of claim 17 , wherein the lithium-based eutectic salt is any one or a mixture of two or more selected from among LiCl—KCl, LiCl—LiBr—KBr, LiF—LiBr—KBr, LiNO 3 —NaNO 3 —KNO 3 , LiNO 3 —NaNO 3 —KNO 3 —NaNO 2 , and LiCl—LiNO 3 —NaNO 2 .

19. The method of claim 17 , wherein the ionic liquid is any one or a mixture of two or more selected from among tetramethylammonium bis(trifluoromethanesulfonyl)imide, triethylsulfonium bis(trifluoromethylsulfonyl)imide, N-methyl-N-trioctylammonium bis(trifluoro-methylsulfonyl)imide, and N-butyl-N-methylpyrrolidinium bis(trifluoro-methylsulfonyl)imide.

20. The method of claim 15 , wherein the molten salt film is manufactured by applying or inserting a molten salt powder on or into both contact surfaces of the solid electrolyte and the anode or the cathode.

21. The method of claim 1 , wherein the metal foam is provided as a single layer or multiple layers.

22. The method of claim 21 , wherein when the metal foam is provided as the single layer between an electrolyte and a current collector,
a diameter of pores of the metal foam is gradually decreased in a thickness direction of the metal foam.

23. The method of claim 21 , wherein when the metal foam is provided as the multiple layers between an electrolyte and a current collector,
a diameter of pores formed in each of the multiple layers of the metal foam is gradually decreased moving toward the current collector from the electrolyte.

24. The method of claim 1 , wherein the metal foam is coated with a molten salt before use as an anode and the cathode.

25. The method of claim 24 , wherein the metal foam is coated by being immersed in a molten salt bath or a saturated salt solution.

26. The method of claim 1 , wherein the metal foam is formed of either iron (Fe) or nickel (Ni).

27. A method of manufacturing a molten lithium-sulfur battery, the method comprising manufacturing a cathode,
wherein the manufacturing the cathode comprises:
a first step of adding a cathode active material to a metal foam by injecting a slurry comprising a sulfur (S) powder into a plurality of pores of the metal foam;
a second step of subjecting a surface of the metal foam to sulfuration through heat treatment of the surface of the metal foam, which is obtained from the first step, in a sealed metal container; and
a third step of additionally adding the cathode active material to the metal foam, which is obtained from the second step, by further immersing the metal foam in molten sulfur,
wherein the molten lithium-sulfur battery includes:
a sealed case;
a solid electrolyte;
a conductive metal foam having a plurality of pores;
an anode using the metal foam and using lithium (Li) or a lithium alloy as an active material being accommodated into the metal foam; and
a cathode using the metal foam and using sulfur (S) or a sulfide as an active material.

28. The method of claim 27 , wherein the heat treatment in the sealed metal container is performed at 400 to 600° C.

Assignees

• Agency Defense Dev

Inventors

• Cheong Hae-Won
• Im Chae-Nam
• Kim Ji-Youn
• Kang Sung-Ho
• Cho Jang-Hyeon

Classifications

• H01M4/38

  of elements or alloys · CPC title

• H01M4/0483

  by methods including the handling of a melt (H01M4/0438, take precedence) · CPC title

• H01M4/382

  Lithium (H01M4/405 takes precedence) · CPC title

• H01M4/621

  Binders · CPC title

• H01M4/0471

  involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis · CPC title