Lithium-ion secondary battery, electrode for the secondary battery, and electrolytic copper foil for electrode for the secondary battery

Patent metadata

Field	Value
Publication number	US-9603245-B2
Application number	US-201113976503-A
Country	US
Kind code	B2
Filing date	Dec 27, 2011
Priority date	Dec 27, 2010
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

To provide an electrolytic copper foil for a negative electrode for a lithium-ion secondary battery with which it is possible to produce a long-life lithium-ion secondary battery in which there is no decline in the capacity retention ratio even when the charge-discharge cycling is repeated, that has long life, and no deformation of a negative electrode current collector occurs. The electrolytic copper foil constituting the negative electrode current collector for the lithium-ion secondary battery has, after heat treatment at from 200 to 400° C., a 0.2% proof stress of 250 N/mm 2 or more, and elongation of 2.5% or more; and the surface on which an active material layer of the electrolytic copper foil is provided has been rust-proofed, or roughened and rust-proofed. As a result of analysis of the depth profile (depth direction) obtained by performing secondary ion mass spectrometry (SIMS) in the thickness direction of the copper foil, the copper foil including: chlorine (Cl), carbon (C), and oxygen (O) each in a concentration of 10 17 to 5×10 20 atoms/cm 3 , and sulfur (S) and nitrogen (N) each in a concentration of 10 15 to 10 19 atoms/cm 3 .

First claim

The invention claimed is:

1. An electrolytic copper foil for a negative electrode current collector of a lithium-ion secondary battery constituting the negative electrode current collector for the lithium-ion secondary battery,
the electrolytic copper foil having a surface roughness Rz of from 0.8 to 2.8 μm on both a first surface and a second surface thereof,
the electrolytic copper foil having a 0.2% proof stress after heat treatment under a temperature between 200 and 400° C. of 250 N/mm 2 or more and an elongation of 2.5% or more, and
at least one of the first surface and the second surface of the electrolytic copper foil on which an active material layer is provided being rust-proofed.

2. An electrolytic copper foil for a negative electrode current collector for a lithium-ion secondary battery constituting the negative electrode current collector for the lithium-ion secondary battery,
the electrolytic copper foil having a surface roughness Rz of from 0.8 to 2.8 μm on both a first surface and a second surface thereof,
the electrolytic copper foil having a 0.2% proof stress of 250 N/mm 2 or more and an elongation of 2.5% or more after heat treatment under a temperature between 200 and 400° C., and
at least one of the first surface and the second surface of the electrolytic copper foil on which an active material layer is provided being roughened and rust-proofed.

3. The electrolytic copper foil according to claim 2 , wherein the at least one of the first surface and the second surface is roughened by attaching particles whose main component is Cu using a plating method.

4. The electrolytic copper foil according to claim 2 , wherein the at least one of the first surface and the second surface includes a granular copper plating layer formed by burn plating of copper and a precise copper plating (cover plating) formed on the granular copper plating layer.

5. The electrolytic copper foil according to claim 2 , wherein the at least one of the first surface and the second surface is roughened by an etching method.

6. A negative electrode for a lithium-ion secondary battery,
the negative electrode including a current collector formed of an electrolytic copper foil,
the electrolytic copper foil having a surface roughness Rz of from 0.8 to 2.8 μm on both a first surface and a second surface thereof,
the electrolytic copper foil having a 0.2% proof stress of 250 N/mm 2 or more and an elongation of 2.5% or more after heat treatment under a temperature between 200 and 400° C.,
at least one of the first surface and the second surface being rust-proofed, and
an active material layer being formed on the at least one of the first surface and the second surface that has been rust-proofed.

7. A negative electrode for a lithium-ion secondary battery,
the negative electrode including a current collector formed of an electrolytic copper foil,
the electrolytic copper foil having a surface roughness Rz of from 0.8 to 2.8 μm on both a first surface and a second surface thereof,
the electrolytic copper foil having a 0.2% proof stress of 250 N/mm 2 or more and an elongation of 2.5% or more after heat treatment under a temperature between 200 and 400° C.,
at least one of the first surface and the second surface being roughened and rust-proofed, and
an active material layer being formed on the at least one of the first surface and the second surface that has been rust-proofed.

8. The negative electrode according to claim 6 or 7 , wherein the active material layer is applied to the negative electrode current collector as a slurry of kneaded active material, binder, and solvent, and being dried and pressed.

9. The negative electrode according to claim 6 or 7 , wherein the active material layer is formed from an active material whose main component is carbon, silicon, germanium, or tin.

10. A lithium-ion secondary battery comprising a positive electrode and a negative electrode,
the negative electrode including a current collector formed of an electrolytic copper foil,
the electrolytic copper foil having a surface roughness Rz of from 0.8 to 2.8 μm on both a first surface and a second surface thereof,
the electrolytic copper foil having a 0.2% proof stress of 250 N/mm 2 or more and an elongation of 2.5% or more after heat treatment under a temperature between 200 and 400° C.,
at least one of the first surface and the second surface being rust-proofed, and
an active material layer being formed on the at least one of the first surface and the second surface that has been rust-proofed.

11. A lithium-ion secondary battery comprising a positive electrode and a negative electrode,
the negative electrode including a current collector formed of an electrolytic copper foil,
the electrolytic copper foil having a surface roughness Rz of from 0.8 to 2.8 μm on both a first surface and a second surface thereof,
the electrolytic copper foil having a 0.2% proof stress of 250 N/mm 2 or more and an elongation of 2.5% or more after heat treatment under a temperature between 200 and 400° C.,
at least one of the first surface and the second surface being roughened and rust-proofed, and
an active material layer being formed on the at least one of the first surface and the second surface that has been rust-proofed.

Assignees

• Suzuki Akitoshi
• Shinozaki Kensaku
• Tani Toshio
• Sasaki Hirokazu
• Futaba Isamu
• Hataya Kouji
• Ohtomo Shinya
• Yoshikawa Hirokazu
• Furukawa Electric Co Ltd

Inventors

• Suzuki Akitoshi
• Shinozaki Kensaku
• Tani Toshio
• Sasaki Hirokazu
• Futaba Isamu
• Hataya Kouji
• Ohtomo Shinya
• Yoshikawa Hirokazu

Classifications

• H01M4/043

  involving compressing or compaction · CPC title

• H01M4/661

  Metal or alloys, e.g. alloy coatings (H01M4/669 take precedence) · CPC title

• H01M4/0404

  by coating on electrode collectors · CPC title

• H01M4/133

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

• H01M4/1395

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