Electrolytic solution and lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-11201354-B2
Application number	US-201716093353-A
Country	US
Kind code	B2
Filing date	Apr 14, 2017
Priority date	Apr 15, 2016
Publication date	Dec 14, 2021
Grant date	Dec 14, 2021

Abstract

An electrolytic solution contains: an electrolyte including a lithium salt represented by general formula (1) below; an organic solvent including a linear carbonate represented by general formula (2) below; and an unsaturated cyclic carbonate, wherein
the linear carbonate is contained at a mole ratio of 3 to 6 relative to the lithium salt, and/or the lithium salt is contained at a concentration of 1.1 to 3.8 mol/L.

(R 1 X 1 )(R 2 SO 2 )NLi  general formula (1)

R 20 OCOOR 21   general formula (2)

First claim

The invention claimed is:

1. An electrolytic solution containing: an electrolyte including a lithium salt represented by general formula (1) below; an organic solvent including a linear carbonate represented by general formula (2) below; and an unsaturated cyclic carbonate, the linear carbonate being contained by not less than 70 mass % relative to an entire organic solvent contained in the electrolytic solution, wherein
the linear carbonate is contained at a mole ratio of 3 to 6 relative to the lithium salt, and/or
the lithium salt is contained at a concentration of 1.1 to 3.8 mol/L,
(R 1 X 1 )(R 2 SO 2 )NLi  general formula (1)

(R 1 is selected from: hydrogen; a halogen; an alkyl group optionally substituted with a substituent group; a cycloalkyl group optionally substituted with a substituent group; an unsaturated alkyl group optionally substituted with a substituent group; an unsaturated cycloalkyl group optionally substituted with a substituent group; an aromatic group optionally substituted with a substituent group; a heterocyclic group optionally substituted with a substituent group; an alkoxy group optionally substituted with a substituent group; an unsaturated alkoxy group optionally substituted with a substituent group; a thioalkoxy group optionally substituted with a substituent group; an unsaturated thioalkoxy group optionally substituted with a substituent group; CN; SCN; or OCN,
R 2 is selected from halogens,
X 1 is selected from SO 2 , C═O, C═S, R a P═O, R b P═S, S═O, or Si═O,
R a and R b are each independently selected from: hydrogen; a halogen; an alkyl group optionally substituted with a substituent group; a cycloalkyl group optionally substituted with a substituent group; an unsaturated alkyl group optionally substituted with a substituent group; an unsaturated cycloalkyl group optionally substituted with a substituent group; an aromatic group optionally substituted with a substituent group; a heterocyclic group optionally substituted with a substituent group; an alkoxy group optionally substituted with a substituent group; an unsaturated alkoxy group optionally substituted with a substituent group; a thioalkoxy group optionally substituted with a substituent group; an unsaturated thioalkoxy group optionally substituted with a substituent group; OH; SH; CN; SCN; or OCN,
R a and R b each optionally bind with R 1 to form a ring),
R 20 OCOOR 21   general formula (2)

(R 20 and R 21 are each independently selected from C n H a F b Cl c Br d I e that is a linear alkyl, or C m H f F g Cl h Br i I j that includes a cyclic alkyl in the chemical structure thereof, “n” is an integer not smaller than 1, “m” is an integer not smaller than 3, and “a”, “b”, “c”, “d”, “e”, “f”, “g”, “h”, “i”, and “j” are each independently an integer not smaller than 0, and satisfy 2n+1=a+b+c+d+e and 2m−1=f+g+h+i+j).

2. The electrolytic solution according to claim 1 , wherein
(FSO 2 ) 2 NLi is contained at a concentration of 1.1 to 3.8 mol/L.

3. The electrolytic solution according to claim 1 , wherein
the unsaturated cyclic carbonate is contained by greater than 0 and not greater than 6.5 mass % relative to an entire electrolytic solution.

4. The electrolytic solution according to claim 1 , wherein
the unsaturated cyclic carbonate is contained by greater than 0 and less than 2.5 mass % relative to an entire electrolytic solution.

5. The electrolytic solution according to claim 1 , wherein
the unsaturated cyclic carbonate is represented by general formula (A) below,

(R 1 and R 2 are each independently hydrogen, an alkyl group, a halogen-substituted alkyl group, or a halogen).

6. The electrolytic solution according to claim 1 , wherein
the unsaturated cyclic carbonate is vinylene carbonate.

7. The electrolytic solution according to claim 1 , wherein
(FSO 2 ) 2 NLi is contained at a concentration of 1.5 to 3.0 mol/L.

8. The electrolytic solution according to claim 1 , wherein
the linear carbonate is contained by not less than 80 mass % relative to the entire organic solvent contained in the electrolytic solution.

9. The electrolytic solution according to claim 1 , wherein
a voltage at which the electrolytic solution is degraded in the presence of a graphite is not less than 0.6 V based on metal lithium.

10. A lithium ion secondary battery comprising: the electrolytic solution according to claim 1 ; a negative electrode; a positive electrode; and a coating
containing S, O, and C on a surface of the negative electrode and/or the positive electrode.

11. A lithium ion secondary battery comprising:
the electrolytic solution according to claim 1 ;
a negative electrode;
a positive electrode; and
a coating containing S, O, and C on a surface of the negative electrode and/or the positive electrode, wherein
a value of (mass (mg) of unsaturated cyclic carbonate/surface area (m 2 ) of negative electrode) is greater than 0 and not greater than 60.

12. The lithium ion secondary battery according to claim 10 , wherein
the value of (mass (mg) of unsaturated cyclic carbonate/surface area (m 2 ) of negative electrode) is 2.5 to 60.

13. A lithium ion secondary battery comprising:
the electrolytic solution according to claim 1 ;
a negative electrode;
a positive electrode; and
a coating containing S, O, and C on a surface of the negative electrode and/or the positive electrode, wherein
in the coating, a number of materials having a long diameter of 30 nm or greater is less than 80 counts/μm 2 .

14. The lithium ion secondary battery according to claim 10 , wherein
an element percentage of C is 40.2 to 49.1 atm % when the surface of the negative electrode is measured by X-ray photoelectron spectroscopy.

15. The lithium ion secondary battery according to claim 10 , wherein
a total element percentage of N, F, and S is 5.1 to 10.4 atm % when the surface of the negative electrode is measured by X-ray photoelectron spectroscopy.

16. The lithium ion secondary battery according to claim 10 , wherein
the negative electrode includes a graphite as a negative electrode active material.

17. A lithium ion secondary battery comprising:
the electrolytic solution according to claim 1 ;
a positive electrode; and
a negative electrode, wherein
an amount of the unsaturated cyclic carbonate relative to a surface area of the negative electrode is in a range of greater than 0 and not greater than 12 mg/m 2 .

18. The lithium ion secondary battery according to claim 17 , wherein
a chemical structure of the lithium salt is represented by general formula (1-1) below,
(R 3 X 2 )(R 4 SO 2 )NLi  general formula (1-1)

(R 3 is C n H a F b Cl c Br d I e (CN) f (SCN) g (OCN) h ,
“n”, “a”, “b”, “c”, “d”, “e”, “f”, “g”, and “h” are each independently an integer not smaller than 0, and satisfy 2n+1=a+b+c+d+e+f+g+h,
R 4 is selected from halogens,
R 3 and R 4 optionally bind with each other to form a ring, and in that case, satisfy 2n=a+b+c+d+e+f+g+h,
X 2 is selected from SO 2 , C═O, C═S, R c P═O, R d P═S, S═O, or Si═O,
R c and R d are each independently selected from: hydrogen; a halogen; an alkyl group optionally substituted with a substituent group; a cycloalkyl group optionally substituted with a substituent group; an unsaturated alkyl group optionally substituted with a substituent group; an unsaturated cycloalkyl group optionally substituted with a substituent group; an aromatic group optionally substituted wi

Assignees

• Toyota Jidoshokki Kk

Inventors

• Sasaki Hiroyuki
• Kawai Tomoyuki
• Nakagaki Yoshihiro
• Okamoto Ryota
• Yotsumoto Kensuke
• MINAGATA Atsushi
• Sugimoto Yuki
• Sato Yuuhi

Classifications

• H01G11/32

  Carbon-based · CPC title

• H01M10/0568 Primary

  characterised by the solutes · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M10/058

  Construction or manufacture · CPC title

• H01G11/62

  characterised by the solute, e.g. salts, anions or cations therein · CPC title