Negative electrode for rechargeable lithium battery and rechargeable lithium battery including same

Patent metadata

Field	Value
Publication number	US-2024363835-A1
Application number	US-202318504987-A
Country	US
Kind code	A1
Filing date	Nov 8, 2023
Priority date	Apr 27, 2023
Publication date	Oct 31, 2024
Grant date	—

Abstract

A negative electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same are provided. The negative electrode includes a Si—C composite negative electrode active material and a binder, wherein the binder includes a first binder that is an acrylic copolymer. The acrylic copolymer includes a first acrylic acid monomer, a second acrylonitrile monomer, and a third (meth)acrylate monomer, the first acrylic acid monomer includes acrylic acid substituted with a lithium ion, and the third (meth)acrylate monomer is a (meth)acrylate monomer including an ethylene glycol group and has a weight average molecular weight (Mw) of less than about 900 g/mol.

First claim

What is claimed is:

1 . A negative electrode for a rechargeable lithium battery, the negative electrode comprising
a Si—C composite negative electrode active material; and a binder, wherein the binder comprises a first binder that is an acrylic copolymer, and the acrylic copolymer comprises a first acrylic acid monomer, a second acrylonitrile monomer, and a third (meth)acrylate monomer, wherein the first acrylic acid monomer comprises an acrylic acid substituted with a lithium ion, and wherein the third (meth)acrylate monomer is a (meth)acrylate monomer comprising an ethylene glycol group and has a weight average molecular weight (Mw) of at most about 900 g/mol.

2 . The negative electrode as claimed in claim 1 , wherein the Si—C composite comprises silicon and amorphous carbon.

3 . The negative electrode as claimed in claim 1 , wherein the Si—C composite comprises silicon, crystalline carbon, and amorphous carbon.

4 . The negative electrode as claimed in claim 2 , wherein an amount of silicon is about 1 wt % to about 60 wt % based on 100 wt % of the Si—C composite.

5 . The negative electrode as claimed in claim 1 , wherein the Si—C composite comprises:
an aggregate of silicon and amorphous carbon; and/or
silicon and an amorphous carbon coating layer on a surface of the silicon.

6 . The negative electrode as claimed in claim 1 , wherein the Si—C composite comprises secondary particles, wherein each secondary particle is an aggregate of silicon primary particles, and
wherein an amorphous carbon coating layer is on a surface of each of the secondary particles.

7 . The negative electrode as claimed in claim 1 , wherein an amount of the second acrylonitrile monomer is about 20 wt % to about 50 wt % based on 100 wt % of the acrylic copolymer.

8 . The negative electrode as claimed in claim 1 , wherein a weight average molecular weight (Mw) of the third (meth)acrylate monomer is about 300 g/mol to about 600 g/mol.

9 . The negative electrode as claimed in claim 1 , wherein the acrylic acid substituted with the lithium ion has a degree of lithium ion substitution (Li/AA) of about 40 mol % to about 80 mol %.

10 . The negative electrode as claimed in claim 1 , wherein a weight ratio of the first acrylic acid monomer, the second acrylonitrile monomer, and the third (meth)acrylate monomer is about 45 to 60:about 25 to 45:about 5 to 30.

11 . The negative electrode as claimed in claim 1 , wherein the third (meth)acrylate monomer is a polyethylene glycol methyl ether methacrylate monomer.

12 . The negative electrode as claimed in claim 1 , wherein a weight ratio of the first acrylic acid monomer, the second acrylonitrile monomer, and the third (meth)acrylate monomer is about 50 to 55:about 30 to 40:about 5 to 15.

13 . The negative electrode as claimed in claim 5 , wherein a thickness of the amorphous carbon coating layer is about 5 nm to about 100 nm.

14 . The negative electrode as claimed in claim 6 , wherein a thickness of the amorphous carbon coating layer is about 5 nm to about 100 nm.

15 . The negative electrode as claimed in claim 6 , wherein an average particle diameter (D50) of the silicon primary particles is about 10 nanometer (nm) to about 30 micrometer (μm).

16 . The negative electrode as claimed in claim 6 , wherein an average particle diameter (D50) of the silicon primary particles is about 20 nm to about 150 nm.

17 . The negative electrode as claimed in claim 1 , wherein the negative electrode comprises a negative electrode active material layer comprising the Si—C composite negative electrode active material and the binder, and an amount of the binder is about 1 wt % to about 5 wt % based on 100 wt % of the negative electrode active material layer.

18 . The negative electrode as claimed in claim 1 , wherein the binder further comprises a second binder that is an aqueous binder and a weight ratio of the first binder and the second binder is about 70:30 to about 40:60.

19 . The negative electrode as claimed in claim 18 , wherein the aqueous binder is at least one of a styrene-butadiene rubber (SBR), an acrylated styrene-butadiene rubber (ABR), an acrylonitrile-butadiene rubber, an acrylic rubber, a butyl rubber, or a combination thereof.

20 . A rechargeable lithium battery, comprising
the negative electrode as claimed in claim 1 ; a positive electrode; and an electrolyte.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Jung Kyunghwa
• Lee Kukjoo
• Lee Jungmin
• Cho Yunshik
• Cho Minho
• Kim Hana

Classifications

• H01M10/052

  Li-accumulators · CPC title

• H01M4/623

  fluorinated polymers · CPC title

• H01M4/13 Primary

  Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M2004/027

  Negative electrodes · CPC title