Negative electrode and lithium battery including the same

Patent metadata

Field	Value
Publication number	US-2024322174-A1
Application number	US-202318482608-A
Country	US
Kind code	A1
Filing date	Oct 6, 2023
Priority date	Mar 26, 2023
Publication date	Sep 26, 2024
Grant date	—

Abstract

A negative electrode and a lithium battery including the same are provided. The negative electrode includes a negative electrode current collector, and a negative electrode active material layer provided on the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material, a binder, and a carbon-based conductive material. The negative electrode active material includes a metal-based negative electrode active material, the binder includes an acrylic-based binder, and the carbon-based conductive material includes a fibrous carbon-based conductive material. The acrylic-based binder includes monomers having carboxyl, cyano, alkylene oxide, and/or sulfonic acid functionalities and at least a portion of the carboxyl groups are metal (e.g., lithium) carboxylate salts. Volume changes of the negative electrode material during charging/discharging may be suppressed or reduced and the capacity and lifespan characteristics of the lithium battery may be improved.

First claim

What is claimed is:

1 . A negative electrode comprising:
a negative electrode current collector; and a negative electrode active material layer on the negative electrode current collector, wherein the negative electrode active material layer comprises a negative electrode active material, a binder, and a carbon-based conductive material, the negative electrode active material comprises a metal-based negative electrode active material, the binder comprises an acrylic-based binder, the carbon-based conductive material comprises a fibrous carbon-based conductive material having an aspect ratio of 10 or more, the acrylic-based binder comprises a first repeating unit derived from a carboxyl group-containing monomer, a second repeating unit derived from a cyano group-containing monomer, and a third repeating unit derived from an alkylene oxide group-containing monomer, a sulfonic acid group-containing monomer, or a combination thereof, at least a portion of the first repeating unit comprises a metal carboxylate salt, and a weight ratio of the acrylic-based binder and the fibrous carbon-based conductive material is about 2:1 to about 40:1.

2 . The negative electrode as claimed in claim 1 , wherein the fibrous carbon-based conductive material comprises carbon nanotubes, and
the carbon nanotubes comprise single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, or a combination thereof and have an average length of about 40 micrometer (μm) to about 250 μm and an average diameter of about 5 nm to about 100 nm.

3 . The negative electrode as claimed in claim 1 , wherein an amount of the fibrous carbon-based conductive material is about 0.01 wt % to about 1.0 wt % with respect to a total weight of the negative electrode active material, the binder, and the carbon-based conductive material.

4 . The negative electrode as claimed in claim 1 , wherein a loading level of the negative electrode active material layer is about 10 milligram per square centimeter (mg/cm 2 ) to about 30 mg/cm 2 , and
an amount of the fibrous carbon-based conductive material is about 0.01 wt % to about 0.3 wt % with respect to a total weight of the negative electrode active material, the binder, and the carbon-based conductive material.

5 . The negative electrode as claimed in claim 1 , wherein the carbon-based conductive material further comprises a particulate carbon-based conductive material having an aspect ratio of 5 or less,
the particulate carbon-based conductive material has an average particle diameter of 200 nanometer (nm) or less, and a weight ratio of the fibrous carbon-based conductive material and the particulate carbon-based conductive material is about 4:1 to about 1:4.

6 . The negative electrode as claimed in claim 1 , wherein in the first repeating unit, an amount of a repeating unit comprising a metal carboxylate salt is about 40 mol % to about 80 mol %, and
the metal carboxylate salt comprises a lithium salt, a sodium salt, a potassium salt, a rubidium salt, a cesium salt, or a combination thereof.

7 . The negative electrode as claimed in claim 1 , wherein the carboxyl group-containing monomer comprises an unsaturated carboxylic acid, and
the unsaturated carboxylic acid comprises a monocarboxylic acid, a dicarboxylic acid, a dicarboxylic acid anhydride, or a combination thereof or comprises an acrylic acid, a methacrylic acid, a crotonic acid, a maleic acid, a fumaric acid, an itaconic acid, or a combination thereof.

8 . The negative electrode as claimed in claim 1 , wherein an amount of the first repeating unit derived from the carboxyl group-containing monomer is about 40 mol % to about 60 mol % with respect to all repeating units in the acrylic-based binder.

9 . The negative electrode as claimed in claim 1 , wherein the cyano group-containing monomer comprises an unsaturated nitrile compound, and
the unsaturated nitrile compound comprises acrylonitrile, methacrylonitrile, chloroacrylonitrile, ethylacrylonitrile, vinylidene cyanide, or a combination thereof.

10 . The negative electrode as claimed in claim 1 , wherein an amount of the second repeating unit derived from the cyano group-containing monomer is about 40 mol % to about 70 mol % with respect to all repeating units in the acrylic-based binder.

11 . The negative electrode as claimed in claim 1 , wherein the alkylene oxide group-containing monomer comprises an unsaturated carboxylic acid ester comprising 1 to 20 alkylene oxide repeating units,
the alkylene oxide repeating units comprise a methylene oxide repeating unit, an ethylene oxide repeating unit, a propylene oxide repeating unit, or a combination thereof, the unsaturated carboxylic acid ester comprising the 1 to 20 alkylene oxide repeating units comprises polyethylene glycol methyl ether acrylate, polyethylene glycol methyl ether methacrylate, polyethylene glycol ethyl ether acrylate, polyethylene glycol ethyl ether methacrylate, or a combination thereof, and a weight average molecular weight of the alkylene oxide group-containing monomer is about 200 Dalton to about 950 Dalton.

12 . The negative electrode as claimed in claim 1 , wherein the sulfonic acid group-containing monomer comprises at least one selected from among 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-ethylpropanesulfonic acid, 2-methacrylamido-2-ethylpropanesulfonic acid, 2-acrylamido-2-methylbutanesulfonic acid, 2-methacrylamido-2-methylbutanesulfonic acid, 2-acrylamido-2-ethylbutanesulfonic acid, and 2-methacrylamido-2-ethylbutanesulfonic acid.

13 . The negative electrode as claimed in claim 1 , wherein an amount of the third repeating unit is about 1 wt % to about 10 mol % with respect to all repeating units in the acrylic-based binder.

14 . The negative electrode as claimed in claim 1 , wherein, in all repeating units in the acrylic-based binder, an amount of the first repeating unit derived from the carboxyl group-containing monomer is about 40 mol % to about 60 mol %, an amount of the second repeating unit derived from the cyano group-containing monomer is about 40 mol % to about 60 mol %, and an amount of the third repeating unit derived from the alkylene oxide group-containing monomer is about 1 mol % to about 10 mol %, and
wherein a viscosity of a 7.7 wt % aqueous solution of the acrylic-based binder at a temperature of 25° C. and a pressure of 1 atm is about 1,500 centipoise to about 4,500 centipoise.

15 . The negative electrode as claimed in claim 1 , wherein an amount of the acrylic-based binder is about 0.1 wt % to about 5 wt % with respect to a total weight of the negative electrode active material, the binder, and the carbon-based conductive material.

16 . The negative electrode as claimed in claim 1 , wherein the binder further comprises a non-acrylic-based binder and comprises about 10 parts by weight to about 50 parts by weight of the acrylic-based binder with respect to about 100 parts by weight of the non-acrylic-based binder.

17 . The negative electrode as claimed in claim 1 , wherein the metal-based negative electrode active material comprises silicon, a silicon alloy, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, a silicon-carbon composite, or a combination thereof,
the silicon-carbon composite comprises a composite of silicon nanoparticles, carbon nanoparticles, or a combination thereof, the silicon-carbon composite has an average particle diameter of about 5 μm to about 20 μm, the silicon nanoparticles have an average par

Assignees

• Samsung Sdi Co Ltd

Inventors

• Lee Kukjoo
• Cho Yunshik
• Oh Seunghyun
• Cho Minho
• Jung Kyunghwa
• Lee Jungmin

Classifications

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M2004/027

  Negative electrodes · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/386

  Silicon or alloys based on silicon · CPC title

• H01M4/133

  Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title