Negative electrode, method of producing the same, and secondary battery comprising the same

Patent metadata

Field	Value
Publication number	US-2022255060-A1
Application number	US-202017618717-A
Country	US
Kind code	A1
Filing date	Jul 24, 2020
Priority date	Aug 5, 2019
Publication date	Aug 11, 2022
Grant date	—

Abstract

The present invention provides a negative electrode which comprises: a negative electrode current collector; and a negative electrode active material layer formed on the negative electrode current collector and comprising a negative electrode active material containing a silicon-based active material and a carbon-based active material, a binder, and single-walled carbon nanotube aggregates. The single-walled carbon nanotube aggregates are comprised at 0.05 parts by weight to 0.37 parts by weight based on 100 parts by weight of the silicon-based active material in the negative electrode active material layer.

First claim

1 . A negative electrode comprising:
a negative electrode current collector; and a negative electrode active material layer disposed on the negative electrode current collector and comprising a negative electrode active material containing a silicon-based active material and a carbon-based active material, a binder, and single-walled carbon nanotube aggregates, wherein an amount of the single-walled carbon nanotube aggregates in the negative electrode active material layer is from 0.05 parts by weight to 0.37 parts by weight based on 100 parts by weight of the silicon-based active material.

2 . The negative electrode of claim 1 , wherein the single-walled carbon nanotube aggregate includes a secondary structure formed by aggregating two or more single-walled carbon nanotube monomers.

3 . The negative electrode of claim 1 , wherein the silicon-based active material comprises at least one selected from the group consisting of Si, a silicon-based oxide, a Si-metal alloy, and a silicon-carbon composite.

4 . The negative electrode of claim 1 , wherein the carbon-based active material comprises at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, acetylene black, Ketjen black, Super P, graphene, and fibrous carbon.

5 . The negative electrode of claim 1 , wherein an amount of the single-walled carbon nanotube aggregates in the negative electrode active material layer is from 0.008 wt % to 0.055 wt % based on 100 wt % of the negative electrode active material layer.

6 . The negative electrode of claim 1 , wherein the negative electrode active material comprises the silicon-based active material and the carbon-based active material in a weight ratio of 1:99 to 30:70.

7 . The negative electrode of claim 1 , wherein an amount of the negative electrode active material in the negative electrode active material layer is from 70 to 99 wt %-based on 100 wt % of the negative electrode active material layer.

8 . The negative electrode of claim 1 , wherein the single-walled carbon nanotube aggregates have an average length of 3 μm to 20 μm.

9 . The negative electrode of claim 1 , wherein the single-walled carbon nanotube aggregates have an average diameter of 3 nm to 20 nm.

10 . The negative electrode of claim 1 , wherein the negative electrode active material layer further comprises a thickener,
wherein the thickener comprises first carboxymethylcellulose having a weight-average molecular weight of 800,000 to 1,600,000 and second carboxymethylcellulose having a weight-average molecular weight of 350,000 to 750,000.

11 . The negative electrode of claim 10 , wherein the negative electrode active material layer comprises the first carboxymethylcellulose and the second carboxymethylcellulose in a weight ratio of 12:1 to 100:1.

12 . The negative electrode of claim 10 , wherein an amount of the thickener in the negative electrode active material layer is from 0.5 to 5 wt % based on 100 wt % of the negative electrode active material laver.

13 . A method of producing a negative electrode, comprising:
adding and mixing a negative electrode active material comprising a silicon-based active material and a carbon-based active material, a binder, single-walled carbon nanotube aggregates, and first carboxymethylcellulose having a weight-average molecular weight of 800,000 to 1,600,000 to a first solvent to prepare a negative electrode slurry; coating a negative electrode current collector with the negative electrode slurry; and drying the negative electrode slurry, wherein an amount of the single-walled carbon nanotube aggregates in the negative electrode slurry is from 0.05 to 0.37 parts by weight based on 100 parts by weight of the silicon-based active material.

14 . The method of claim 13 , wherein
the method further comprises preparing the single-walled carbon nanotube aggregates by mixing single-walled carbon nanotube monomers with a conductive material solution comprising second carboxymethylcellulose having a weight-average molecular weight of 350,000 to 750,000 and a second solvent, and in the adding and mixing, the conductive material solution including the single-walled carbon nanotube aggregates is added to the first solvent.

15 . A secondary battery comprising:
the negative electrode according to claim 1 ; a positive electrode disposed to face the negative electrode; a separator interposed between the negative electrode and the positive electrode; and an electrolyte.

Assignees

• Lg Energy Solution Ltd

Inventors

• Oh Il Geun
• Kim Je Young
• Lee Yong Ju
• Yoo Jung Woo
• Shin Sun Young
• Kim Ye Lin
• Kim Tae Gon

Classifications

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/1395

  of electrodes based on metals, Si or alloys · CPC title

• H01M10/0525

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

• H01M4/133 Primary

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

• H01M4/1393

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