Electrolytic solution, lithium-sulfur secondary battery, and module

Patent metadata

Field	Value
Publication number	US-12322759-B2
Application number	US-202017596113-A
Country	US
Kind code	B2
Filing date	Jun 5, 2020
Priority date	Jun 5, 2019
Publication date	Jun 3, 2025
Grant date	Jun 3, 2025

Abstract

An electrolytic solution, a lithium-sulfur secondary battery including the electrolytic solution and a module. The lithium-sulfur secondary battery has a positive electrode or a negative electrode containing a sulfur-containing electrode active material containing at least one selected from simple sulfur, lithium polysulfides (Li 2 S n : 1≤n≤8) and organosulfur compounds. The electrolytic solution contains: a fluorinated ether represented by: Rf—(OR 1 ) n —O—R 2 ; an ether compound represented by: R 4 —(OCHR 3 CH 2 ) x —OR 5 ; and an alkali metal salt, wherein Rf, R 1 , R 2 , R 3 , R 4 , R 5 , n and x are as defined herein.

First claim

The invention claimed is:

1. A lithium-sulfur secondary battery comprising a positive electrode or a negative electrode containing a sulfur-containing electrode active material containing at least one selected from the group consisting of simple sulfur, lithium polysulfides (Li 2 S n : 1≤n≤8) and organosulfur compounds, wherein the lithium-sulfur secondary battery comprises an electrolytic solution comprising:
a fluorinated ether which is at least one selected from the group consisting of HCF 2 CF 2 OCH 2 CH 2 CH 3 , HCF 2 CF 2 CH 2 OCH 2 CH 3 , HCF 2 CF 2 CH 2 OCH 2 CH 2 CH 3 , CF 3 CHFCF 2 OCH 2 CH 3 and CF 3 CHFCF 2 OCH 2 CH 2 CH 3 ;
an ether compound represented by formula (2):
R 4 —(OCHR 3 CH 2 ) x —OR 5   (2)

wherein R 4 and R 5 are each independently selected from the group consisting of alkyl groups having 1 to 9 carbon atoms and having no fluorine atom, a phenyl group optionally substituted by a halogen atom and a cyclohexyl group optionally substituted by a halogen atom, and optionally together form a ring; R 3 each independently represent H or CH 3 ; and x represents 0 to 10; and
an alkali metal salt.

2. The lithium-sulfur secondary battery according to claim 1 , wherein the fluorinated ether is at least one selected from the group consisting of HCF 2 CF 2 CH 2 OCH 2 CH 3 , HCF 2 CF 2 CH 2 OCH 2 CH 2 CH 3 , CF 3 CHFCF 2 OCH 2 CH 3 and CF 3 CHFCF 2 OCH 2 CH 2 CH 3 .

3. The lithium-sulfur secondary battery according to claim 1 , wherein the fluorinated ether represented by the formula (1) and the ether compound represented by the formula (2) in total is 60% by weight or more of a solvent in the electrolytic solution.

4. The lithium-sulfur secondary battery according to claim 1 , wherein the ether compound is at least one selected from the group consisting of tetrahydrofuran (THF), 1,3-dioxolane, 1,4-dioxane, glymes, and derivatives thereof.

5. The lithium-sulfur secondary battery according to claim 1 , wherein the alkali metal salt is represented by LiX; and
X is at least one selected from the group consisting of Cl, Br, I, BF 4 , PF 6 , CF 3 SO 3 , ClO 4 , CF 3 CO 2 , AsF 6 , SbF 6 , AlCl 4 , bistrifluoromethanesulfonylamide (TFSA), N(CF 3 SO 2 ) 2 , N(CF 3 CF 2 SO 2 ) 2 , PF 3 (C 2 F 5 ) 3 , N(FSO 2 ) 2 , N(FSO 2 )(CF 3 SO 2 ), N(CF 3 CF 2 SO 2 ) 2 , N(C 2 F 4 S 2 O 4 ), N(C 3 F 6 S 2 O 4 ), N(CN) 2 , N(CF 3 SO 2 )(CF 3 CO), R 6 FBF 3 wherein R 6 F is n-C m F 2m+1 and m is a natural number of 1 to 4, and R 7 BF 3 wherein R 7 is n-C p H 2p+1 and p is a natural number of 1 to 5.

6. The lithium-sulfur secondary battery according to claim 1 , comprising a positive electrode containing a sulfur-containing electrode active material.

7. A module, comprising the lithium-sulfur secondary battery according to claim 1 .

8. The lithium-sulfur secondary battery according to claim 1 , wherein the fluorinated ether is at least one selected from the group consisting of HCF 2 CF 2 OCH 2 CH 2 CH 3 , HCF 2 CF 2 CH 2 OCH 2 CH 2 CH 3 , CF 3 CHFCF 2 OCH 2 CH 3 and CF 3 CHFCF 2 OCH 2 CH 2 CH 3 .

9. The lithium-sulfur secondary battery according to claim 1 , wherein the fluorinated ether is at least one selected from the group consisting of HCF 2 CF 2 OCH 2 CH 2 CH 3 , HCF 2 CF 2 CH 2 OCH 2 CH 3 , CF 3 CHFCF 2 OCH 2 CH 3 and CF 3 CHFCF 2 OCH 2 CH 2 CH 3 .

10. The lithium-sulfur secondary battery according to claim 1 , wherein the fluorinated ether is at least one selected from the group consisting of HCF 2 CF 2 OCH 2 CH 2 CH 3 , HCF 2 CF 2 CH 2 OCH 2 CH 3 , HCF 2 CF 2 CH 2 OCH 2 CH 2 CH 3 , and CF 3 CHFCF 2 OCH 2 CH 2 CH 3 .

11. The lithium-sulfur secondary battery according to claim 1 , wherein the fluorinated ether is at least one selected from the group consisting of HCF 2 CF 2 OCH 2 CH 2 CH 3 , HCF 2 CF 2 CH 2 OCH 2 CH 3 , HCF 2 CF 2 CH 2 OCH 2 CH 2 CH 3 , and CF 3 CHFCF 2 OCH 2 CH 3 .

Assignees

• Daikin Ind Ltd

Inventors

• Hidaka Tomoya
• Kuwajima Yoshiko
• Yamazaki Shigeaki

Classifications

• H01M2300/0034

  Fluorinated solvents · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M10/0568

  characterised by the solutes · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/60

  of organic compounds · CPC title