Copper-covered steel foil, negative electrode, and battery

Patent metadata

Field	Value
Publication number	US-2016190598-A1
Application number	US-201615064696-A
Country	US
Kind code	A1
Filing date	Mar 9, 2016
Priority date	Jul 9, 2010
Publication date	Jun 30, 2016
Grant date	—

Abstract

A negative electrode collector using a copper-covered steel foil for carrying a negative electrode active material for lithium ion secondary batteries has a steel sheet as the core material thereof and has, on both surfaces thereof, a copper covering layer having a mean thickness t Cu of from 0.02 to 5.0 μm on each surface, and of which the total mean thickness, t, including the copper covering layer 7 is from 3 to 100 μm with t Cu /t of at most 0.3. The steel sheet can be common steel, austenitic stainless steel, or ferritic stainless steel. The copper covering layer can be a copper electroplating layer (including one rolled after plating). On the surface of the copper covering layer, for example, a carbon-based active material layer that has been densified through strong roll pressing is formed, and the copper-covered steel foil and the carbon-based active material layer constitute the negative electrode collector.

First claim

1 . A copper-covered steel foil for carrying a negative electrode active material for a lithium ion secondary battery, which has a steel sheet as a core material thereof and has, on both surfaces thereof, a copper covering layer having a mean thickness t Cu of from 0.02 to 5.0 μm on each surface, and of which the total mean thickness, t, including the copper covering layer is from 3 to 100 μm with t Cu /t of at most 0.3.

2 . The copper-covered steel foil as claimed in claim 1 , wherein the copper covering layer is a copper electroplating layer (including one rolled after plating).

3 . The copper-covered steel foil as claimed in claim 1 , wherein the copper covering layer is a copper foil layer integrated with the steel sheet through cladding.

4 . The copper-covered steel foil as claimed in claim 1 , wherein the steel sheet is formed of a cold-rolled steel plate (including steel strip) as defined in JIS G3141:2009.

5 . The copper-covered steel foil as claimed in claim 1 , wherein the steel sheet has an austenitic or ferritic chemical composition as defined in JIS G4305:2005.

6 . The copper-covered steel foil as claimed in claim 1 , wherein the steel sheet has a composition comprising, in terms of % by mass, C: 0.001 to 0.15%, Si: 0.001 to 0.1%, Mn: 0.005 to 0.6%, P: 0.001 to 0.05%, S: 0.001 to 0.5%, Al: 0.001 to 0.5%, Ni: 0.001 to 1.0%, Cr: 0.001 to 1.0%, Cu: 0 to 0.1%, Ti: 0 to 0.5%, Nb: 0 to 0.5%, N: 0 to 0.05%, with a balance of Fe and an inevitable impurity.

7 . The copper-covered steel foil as claimed in claim 1 , wherein the steel sheet has a composition comprising, in terms of % by mass, C: 0.0001 to 0.15%, Si: 0.001 to 4.0%, Mn: 0.001 to 2.5%, P: 0.001 to 0.045%, S: 0.0005 to 0.03%, Ni: 6.0 to 28.0%, Cr: 15.0 to 26.0%, Mo: 0 to 7.0%, Cu: 0 to 3.5%, Nb: 0 to 1.0%, Ti: 0 to 1.0%, Al: 0 to 0.1%, N: 0 to 0.3%, B: 0 to 0.01%, V: 0 to 0.5%, W: 0 to 0.3%, total of Ca, Mg, Y, REM (rare earth metal): 0 to 0.1%, with a balance of Fe and an inevitable impurity.

8 . The copper-covered steel foil as claimed in claim 1 , wherein the steel sheet has a composition comprising, in terms of % by mass, C: 0.0001 to 0.15%, Si: 0.001 to 1.2%, Mn: 0.001 to 1.2%, P: 0.001 to 0.04%, S: 0.0005 to 0.03%, Ni: 0 to 0.6%, Cr: 11.5 to 32.0%, Mo: 0 to 2.5%, Cu: 0 to 1.0%, Nb: 0 to 1.0%, Ti: 0 to 1.0%, Al: 0 to 0.2%, N: 0 to 0.025%, B: 0 to 0.01%, V: 0 to 0.5%, W: 0 to 0.3%, total of Ca, Mg, Y, REM (rare earth metal): 0 to 0.1%, with a balance of Fe and an inevitable impurity.

9 . The copper-covered steel foil as claimed in claim 1 , which has a tensile strength of from 450 to 900 MPa.

10 . The copper-covered steel foil as claimed in claim 1 , which has a tensile strength of from more than 600 to 900 MPa.

11 . A negative electrode for a lithium ion secondary battery, which has an active material layer for the negative electrode of a lithium ion secondary battery, as formed on the surface of at least one copper covering layer of the copper-covered steel foil of claim 1 .

12 . A negative electrode for a lithium ion secondary battery, which has a carbon-based active material layer for the negative electrode of a lithium ion secondary battery, as formed on the surface of at least one copper covering layer of the copper-covered steel foil of claim 1 , at a density of at least 1.50 g/cm 3 .

13 . A negative electrode for a lithium ion secondary battery, which has a carbon-based active material layer for the negative electrode of a lithium ion secondary battery, as formed on the surface of at least one copper covering layer of the copper-covered steel foil of claim 1 , at a density of at least 1.80 g/cm 3 .

14 . A negative electrode for a lithium ion secondary battery, which has a carbon-based active material layer for the negative electrode of a lithium ion secondary battery, as formed on the surface of at least one copper covering layer of the copper-covered steel foil of claim 1 , at a density of at least 2.00 g/cm 3 .

15 . (canceled)

16 . (canceled)

17 . A lithium ion secondary battery using the negative electrode of claim 11 for a negative electrode therein.

Assignees

• Nisshin Steel Co Ltd

Inventors

• Majima Sho
• Tsujimura Takao
• Shimizu Takeshi
• Morita Yoshikazu
• Fujii Takahiro
• Kon Norihiro
• Yoshida Yoshie

Classifications

• C22C38/44

  with molybdenum or tungsten · CPC title

• C22C38/02

  containing silicon · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title

• C22C38/42

  with copper · CPC title

• H01M10/0525

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