Negative Electrode, Secondary Battery Including the Negative Electrode, and Method of Preparing the Negative Electrode

Patent metadata

Field	Value
Publication number	US-2026058157-A1
Application number	US-202519372715-A
Country	US
Kind code	A1
Filing date	Oct 29, 2025
Priority date	Aug 1, 2019
Publication date	Feb 26, 2026
Grant date	—

Abstract

A negative electrode includes a negative electrode active material layer, wherein the negative electrode active material layer includes a negative electrode active material and a conductive agent, wherein the negative electrode active material includes a silicon-based active material, the silicon-based active material includes SiO x (0≤x<2), the conductive agent includes a carbon nanotube structure in which 2 to 5,000 single-walled carbon nanotube units are bonded side by side, and the carbon nanotube structure is included in an amount of 0.01 wt % to 1.0 wt % in the negative electrode active material layer. A secondary battery including the negative electrode, and a method of preparing same are also provided.

First claim

1 . A negative electrode, comprising:
a negative electrode active material layer comprising a negative electrode active material and a conductive agent, wherein the negative electrode active material comprises a silicon-based active material, wherein the conductive agent comprises a carbon nanotube structure comprising a plurality of single-walled carbon nanotube units bonded together, wherein an average diameter of the carbon nanotube structure ranges from 10 nm to 100 nm, and wherein a plurality of carbon nanotube structures are connected to each other to form a conductive network structure in the negative electrode active material layer, and the conductive network structure comprises carbon nanotube structures attached to silicon-based active material particles of the silicon-based active material.

2 . The negative electrode of claim 1 , wherein the conductive network structure connects the silicon-based active material particles to each other to suppress cracks in the negative electrode active material resulting from a volume change of the silicon-based active material during operation of a battery comprising the negative electrode.

3 . The negative electrode of claim 1 , wherein the plurality of single-walled carbon nanotube units are bonded side by side in the carbon nanotube structure.

4 . The negative electrode of claim 1 , wherein the single-walled carbon nanotube units. are bonded side by side in a parallel arrangement in the carbon nanotube structure.

5 . The negative electrode of claim 1 , wherein each single-walled carbon nanotube unit has an average diameter ranging from 0.5 nm to 10 nm.

6 . The negative electrode of claim 1 , wherein the silicon-based active material particles comprise SiOx (0≤x<2).

7 . The negative electrode of claim 1 , wherein the carbon nanotube structure has an average length ranging from 1 μm to 100 μm.

8 . The negative electrode of claim 1 , wherein each single-walled carbon nanotube unit has an average length ranging from 1 μm to 100 μm.

9 . The negative electrode of claim 1 , wherein each single-walled carbon nanotube unit has a specific surface area ranging from 500 m 2 /g to 1,000 m 2 /g.

10 . The negative electrode of claim 1 , wherein the silicon-based active material has an average particle diameter (D 50 ) ranging from 0.1 μm to 20 μm.

11 . The negative electrode of claim 1 , wherein the silicon-based active material further comprises a carbon coating layer.

12 . The negative electrode of claim 1 , wherein the negative electrode active material layer further comprises a carbon-based active material.

13 . The negative electrode of claim 12 , wherein a weight ratio of the silicon-based active material to the carbon-based active material ranges from of 0.5:99.5 to 20:80.

14 . The negative electrode of claim 1 , wherein the negative electrode active material layer further comprises carboxymethyl cellulose.

15 . A secondary battery comprising the negative electrode of claim 1 .

16 . The secondary battery of claim 15 , wherein the secondary battery has a capacity retention rate of more than 93.2% at 100 cycles, wherein the capacity retention is measured by charging the secondary battery at 45° C. at a constant current of 0.5 C to 4.25 V, then charging at 4.2 V until a current flows at a rate of 0.2 C, and then discharging at a current of 0.5° C. to 2.8 V.

17 . A method of preparing a negative electrode, comprising:
preparing a conductive agent dispersion (S1); forming a negative electrode slurry including the conductive agent dispersion and a negative electrode active material (S2); and forming a negative electrode active material layer by drying the negative electrode slurry, wherein the preparing of the conductive agent dispersion (S1) comprises: preparing a mixed solution containing a dispersion medium, a dispersant, and single-walled carbon nanotubes (S1-1); and dispersing the single-walled carbon nanotubes by applying a shear force to the mixed solution to form a carbon nanotube structure in which a plurality of single-walled carbon nanotube units are bonded together (S1-2), wherein an average diameter of the carbon nanotube structure ranges from 10 nm to 100 nm, wherein the negative electrode active material comprises silicon-based active material particles, and wherein a plurality of carbon nanotube structures are connected to each other to form a conductive network structure in the negative electrode active material layer, and the conductive network structure comprises the carbon nanotube structures attached to the silicon-based active material particles.

18 . The method of claim 17 , wherein the step of S1-2 is performed in a homogenizer, and a pressure applied to the mixed solution in the homogenizer ranges from 500 bar to 1,800 bar.

19 . The method of claim 17 , wherein the dispersant comprises carboxymethyl cellulose, and the carboxymethyl cellulose has a weight-average molecular weight ranging from 50,000 g/mol to 150,000 g/mol.

20 . The method of claim 17 , wherein the silicon-based active material particles comprise SiOx (0≤x<2).

Assignees

• Lg Energy Solution Ltd

Inventors

• Kim Tae Gon
• Cho Hyung Man
• Moon Ii Jae
• Park Sun Wook
• Kwak Min

Classifications

• H01M4/622

  being polymers · CPC title

• H01M4/366

  as layered products · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M2220/10

  Batteries in stationary systems, e.g. emergency power source in plant · CPC title

• H01M2004/027

  Negative electrodes · CPC title