Lithium secondary battery including fluoroethylene carbonate in electrolyte

Patent metadata

Field	Value
Publication number	US-11721837-B2
Application number	US-201816638526-A
Country	US
Kind code	B2
Filing date	Aug 1, 2018
Priority date	Sep 6, 2017
Publication date	Aug 8, 2023
Grant date	Aug 8, 2023

Abstract

The present invention relates to a lithium secondary battery comprising: a negative electrode comprising a negative electrode active material containing Si or Sn, a positive electrode comprising a positive electrode active material, and a non-aqueous electrolyte. The non-aqueous electrolyte comprises: a non-aqueous organic solvent; a lithium salt; fluoroethylene carbonate; a first additive containing at least one compound among compounds resented by chemical formulas 1 to 4; and a second additive containing at least one compound among compounds represented by chemical formula 5 or 6.

First claim

The invention claimed is:

1. A lithium secondary battery, comprising:
a negative electrode comprising a negative electrode active material comprising Si or Sn;
a positive electrode comprising a positive electrode active material; and
a non-aqueous electrolyte comprising a non-aqueous organic solvent; a lithium salt; fluoroethylene carbonate; a first additive comprising a compound represented by Chemical Formula 1; and a second additive comprising a compound represented by Chemical Formula 2:

wherein R 1 to R 6 are independently a substituted or unsubstituted primary, secondary, or tertiary alkyl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted aryl group,

wherein R g , R h , R i , and R j are independently a halogen or a halogen substituted or unsubstituted alkyl group or at least two of R g , R h , R i , and R j are linked with each other to form an oxalate group,
wherein a mixing ratio of the first additive to the second additive is a weight ratio of 10:1 to 0.066:1,
wherein an amount of the first additive is 0.5 wt % to 5 wt % based on a total weight of the electrolyte,
wherein an amount of the second additive is 0.5 wt % to 7 wt % based on total weight of the electrolyte, and
wherein an amount of the fluoroethylene carbonate is 0.1 wt % to 3 wt % based on a total weight of the electrolyte.

2. The lithium secondary battery of claim 1 , wherein the first additive is bis(trimethylsilyl) sulfate.

3. The lithium secondary battery of claim 1 , wherein the second additive is lithium difluorobis(oxalate)phosphate.

4. The lithium secondary battery of claim 1 , wherein the negative electrode further comprises a carbon-based negative electrode active material.

5. The lithium secondary battery of claim 1 , wherein the negative electrode active material comprises Si, and the negative electrode active material comprising Si is a silicon-carbon composite.

6. The lithium secondary battery of claim 5 , wherein the silicon-carbon composite further comprises an amorphous carbon coating layer thereon.

7. The lithium secondary battery of claim 1 , wherein an amount of the second additive is 1 wt % to 7 wt % based on a total weight of the electrolyte.

8. The lithium secondary battery of claim 1 , wherein a mixing ratio of the first additive to the second additive is a weight ratio of 10:1 to 0.1:1.

9. The lithium secondary battery of claim 1 , wherein the first additive and the second additive are included in the non-aqueous electrolyte in different amounts such that a mixing ratio of the first additive to the second additive is not a weight ratio of 1:1.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Kim Yunhee
• Kim Kyoung Soo
• You Yongchan
• Cho Erang
• Choi Seonju

Classifications

• H01M10/0567 Primary

  characterised by the additives · CPC title

• C07F5/04

  Esters of boric acids · CPC title

• C07F7/0834

  Compounds having one or more O-Si linkage (for compounds with C-O-Si linkages see C07F7/18) · CPC title

• C07F9/65742

  non-condensed with carbocyclic rings or heterocyclic rings or ring systems · CPC title

• H01M4/364

  as mixtures · CPC title