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

Patent metadata

Field	Value
Publication number	US-2023116454-A1
Application number	US-202217961475-A
Country	US
Kind code	A1
Filing date	Oct 6, 2022
Priority date	Oct 7, 2021
Publication date	Apr 13, 2023
Grant date	—

Abstract

Disclosed herein is a negative electrode including a current collector, a first active material layer on the current collector, and a second active material layer on the first active material layer, wherein at least one of the first active material layer and the second active material layer includes a silicon-based active material and a binder, and the binder includes a copolymer (A) and a copolymer (B), the copolymer (A) includes a unit (a-1) derived from a (meth)acrylic acid-based monomer and a unit (a-2) derived from a (meth)acrylonitrile monomer, and the copolymer (B) includes a unit (b-1) derived from an aromatic vinyl-based monomer and a unit (b-2) derived from an ethylenically unsaturated monomer that is at least one of an unsaturated carboxylic acid alkyl ester monomer, a (meth)acrylic acid-based monomer, an unsaturated carboxylic acid amide monomer, or a conjugated diene monomer, and a rechargeable lithium battery including the same.

First claim

What is claimed is:

1 . A negative electrode for a rechargeable lithium battery, the negative electrode comprising
a current collector; a first active material layer on the current collector; and a second active material layer on the first active material layer, wherein at least one of the first active material layer or the second active material layer comprises a silicon-based active material and a binder, and the binder comprises a copolymer (A) and a copolymer (B), and wherein the copolymer (A) comprises a unit (a-1) derived from a (meth)acrylic acid-based monomer and a unit (a-2) derived from a (meth)acrylonitrile monomer, and the copolymer (B) comprises a unit (b-1) derived from an aromatic vinyl-based monomer and a unit (b-2) derived from an ethylenically unsaturated monomer that is at least one of an unsaturated carboxylic acid alkyl ester monomer, a (meth)acrylic acid-based monomer, an unsaturated carboxylic acid amide monomer, or a conjugated diene monomer.

2 . The negative electrode of claim 1 , wherein
the copolymer (A) and the copolymer (B) are physically mixed with each other in the binder.

3 . The negative electrode of claim 1 , wherein
at least a portion of the copolymer (B) is around the copolymer (A) in the binder.

4 . The negative electrode of claim 1 , wherein
in the binder, a weight ratio of copolymer (A) and copolymer (B) (A:B) is about 30:70 to about 70:30.

5 . The negative electrode of claim 1 , wherein
the copolymer (A) comprises about 30 wt % to about 70 wt % of the unit (a-1) derived from the (meth)acrylic acid-based monomer and about 30 wt % to about 70 wt % of the unit (a-2) derived from (meth)acrylonitrile based on 100 wt % of the copolymer (A).

6 . The negative electrode of claim 1 , wherein
the copolymer (A) further comprises a unit (a-3) derived from another monomer copolymerizable with the (meth)acrylic acid-based monomer and/or the (meth)acrylonitrile monomer, and the other monomer copolymerizable with the (meth)acrylic acid-based monomer and/or the (meth)acrylonitrile monomer comprises a hydroxyl group-containing monomer, an amide group-containing monomer, or a combination thereof.

7 . The negative electrode of claim 6 , wherein
the unit (a-3) derived from the other monomer copolymerizable with the (meth)acrylic acid-based monomer and/or the (meth)acrylonitrile monomer is greater than about 0 wt % and less than or equal to about 20 wt % based on 100 wt % of the copolymer.

8 . The negative electrode of claim 1 , wherein
a viscosity of the copolymer (A) in an aqueous solution of about 7 wt % of solid content is about 500 mPa·s to about 5000 mPa·s.

9 . The negative electrode of claim 1 , wherein
the unit (b-2) derived from the ethylenically unsaturated monomer is in an amount of greater than or equal to about 5 wt % based on 100 wt % of the copolymer (B).

10 . The negative electrode of claim 1 , wherein
one of the first active material layer and or second active material layer comprises the silicon-based active material and the binder, and the other of the first active material layer or the second active material layer comprises a carbon-based active material.

11 . The negative electrode of claim 1 , wherein
the first active material layer comprises the silicon-based active material, the binder, and a first carbon-based active material, and the second active material layer comprises a second carbon-based active material.

12 . The negative electrode of claim 1 , wherein
the first active material layer and the second active material layer each comprise the silicon-based active material, the binder, and a carbon-based active material, and content of silicon in the first active material layer is about 2 to 25 times that of silicon in the second active material layer.

13 . The negative electrode of claim 1 , wherein
the first active material layer and the second active material layer each comprise the silicon-based active material, the binder, and a carbon-based active material, and the negative electrode has a concentration gradient in which content of silicon increases from the second active material layer to the first active material layer.

14 . The negative electrode of claim 1 , wherein
the silicon-based active material comprises a silicon-carbon composite comprising silicon particles and a first carbon-based material.

15 . The negative electrode of claim 14 , wherein
the first carbon-based material comprises artificial graphite, natural graphite, or a combination thereof.

16 . The negative electrode of claim 1 , wherein
the silicon-based active material comprises a silicon-carbon composite comprising:
a core in which silicon particles and a second carbon-based material are mixed; and
a third carbon-based material is around the core.

17 . The negative electrode of claim 16 , wherein
the second carbon-based material is crystalline carbon comprising artificial graphite, natural graphite, or a combination thereof, and the third carbon-based material is amorphous carbon comprising pitch carbon, soft carbon, hard carbon, a mesophase pitch carbonized product, calcined coke, a carbon fiber, or a combination thereof.

18 . The negative electrode of claim 1 , wherein
the first active material layer or the second active material layer comprising the silicon-based active material and the binder comprises about 0.1 wt % to about 8 wt % of the binder based on 100 wt % of the first active material layer or the second active material layer comprising the silicon-based active material and the binder.

19 . The negative electrode of claim 1 , wherein
the first active material layer or the second active material layer comprising the silicon-based active material and the binder further comprises a carbon-based active material.

20 . A rechargeable lithium battery comprising
the negative electrode for the rechargeable lithium battery of claim 1 , a positive electrode, a separator between the negative electrode and the positive electrode, and an electrolyte.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Lee Jungmin
• Kim Minjae
• Ahn Won-Gi
• Lee Kukjoo

Classifications

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01M4/366

  as layered products · CPC title