Electrolyte liquid, method for preparing the same, and lithium sulfur battery using the same

Patent metadata

Field	Value
Publication number	US-2018269531-A1
Application number	US-201615763440-A
Country	US
Kind code	A1
Filing date	Sep 9, 2016
Priority date	Sep 25, 2015
Publication date	Sep 20, 2018
Grant date	—

Abstract

The present disclosure provides an electrolyte liquid of a lithium sulfur battery comprising a carbonate ester organic solvent, a lithium salt, and a flame-retardant cosolvent, the flame-retardant cosolvent being a phosphazene compound, wherein a mass percentage of the flame-retardant cosolvent is 20% to 50%, a concentration of the lithium salt is 0.8 mol/L to 1.2 mol/L. The present disclosure also provides a lithium sulfur battery and a method for preparing the electrolyte liquid.

First claim

1 - 10 . (canceled)

11 . An electrolyte liquid of a lithium sulfur battery comprising a carbonate ester organic solvent, a lithium salt, and a flame-retardant cosolvent, the flame-retardant cosolvent being a phosphazene compound having a molecular structure represented by one of formulas (1) to (3),

12 . The electrolyte liquid of claim 1 , wherein a mass percentage of the flame-retardant cosolvent is 20% to 50%.

13 . The electrolyte liquid of claim 1 , wherein a concentration of the lithium salt is 0.8 mol/L to 1.2 mol/L.

14 . The electrolyte liquid of claim 1 , wherein R1 and R2 are hydrocarbon groups, and at least one hydrogen atom is replaced by a fluorine atom, R1 and R2 respectively have 1 to 8 carbon atoms, and R1 and R2 have different carbon chain lengths.

15 . The electrolyte liquid of claim 1 , wherein in the phosphazene compound, a ratio between fluorine atoms and hydrogen atoms is greater than 3.

16 . The electrolyte liquid of claim 1 , wherein the carbonate ester organic solvent is two or three selected from the group consisting of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, and ethyl propionate.

17 . The electrolyte liquid of claim 1 , wherein the lithium salt is selected from the group consisting of LiCl, LiPF 6 , LiBF 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiAsF 6 , LiClO 4 , LiBOB, LiN(CF 3 SO 2 ) 2 and combinations thereof.

18 . A lithium sulfur battery comprising a cathode electrode, an anode electrode, a separator, and the electrolyte liquid,
wherein the cathode electrode and the anode electrode are spaced, the separator is disposed between the cathode electrode and the anode electrode, and the electrolyte liquid infiltrates the cathode electrode, the anode electrode, and the separator; the electrolyte liquid comprises a carbonate ester organic solvent, a lithium salt, and a flame-retardant cosolvent, the flame-retardant cosolvent is a phosphazene compound having a molecular structure represented by one of formulas (1) to (3),

19 . The lithium sulfur battery of claim 18 , wherein the cathode electrode comprises sulfur.

20 . A method for preparing the electrolyte liquid of the lithium sulfur battery comprising:
respectively reacting sodium metal or sodium hydride in a first organic solvent with a first fluorine-containing alcohol and a second fluorine-containing alcohol to form a first fluorine-containing sodium alkoxide solution and a second fluorine-containing sodium alkoxide solution; dissolving hexachlorocyclotriphosphazene in a second organic solvent to form a hexachlorocyclotriphosphazene solution; adding the first fluorine-containing sodium alkoxide solution into the hexachlorocyclotriphosphazene solution to have a first reaction; then adding the second fluorine-containing sodium alkoxide solution, raising the temperature to 45° C. to 55° C., and carrying a second reaction to obtain a milky turbid liquid; drying the milky turbid liquid, and washing a dried product thereof with an alkaline water solution; purifying the dried product to obtain an orange-yellow transparent liquid; and mixing the orange-yellow transparent liquid and a carbonate ester organic solvent to form a mixed solvent.

21 . The method of claim 20 , wherein the first fluorine-containing alcohol and the second fluorine-containing alcohol respectively have 1 to 8 carbon atoms, and have different carbon chain lengths.

22 . The method of claim 20 , wherein the first and second organic solvent are respectively selected from the group consisting of tetrahydrofuran, dioxane, dichloromethane, chloroform, and combination thereof.

23 . The method of claim 20 , wherein a molar ratio of the first fluorine-containing sodium alkoxide to the hexachlorocyclotriphosphazene is 1:1 to 3:1, and a molar ratio of the second fluorine-containing sodium alkoxide to the hexachlorocyclotriphosphazene is 3:1 to 5:1.

Assignees

• Jiangsu Huadong Inst Of Li Ion Battery Co Ltd
• Univ Tsinghua

Inventors

• Liu Zhen
• Shang yu-ming
• He xiang-ming
• Wang Li

Classifications

• H01M10/052

  Li-accumulators · CPC title

• H01M10/4235

  Safety or regulating additives or arrangements in electrodes, separators or electrolyte (H01M10/4242 takes precedence) · CPC title

• H01M10/0569 Primary

  characterised by the solvents · CPC title

• H01M10/0567 Primary

  characterised by the additives · CPC title

• H01M2300/0028

  characterised by the solvent · CPC title