Easily handleable electrolytic copper foil, electrode comprising the same, secondary battery comprising the same, and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-2018102546-A1
Application number	US-201715696360-A
Country	US
Kind code	A1
Filing date	Sep 6, 2017
Priority date	Oct 12, 2016
Publication date	Apr 12, 2018
Grant date	—

Abstract

An easily handleable electrolytic copper foil securing a highly durable secondary battery, an electrode including same, a secondary battery including same, and a method of manufacturing same. The electrolytic copper foil including first and second surfaces includes a copper layer including a matte surface facing the first surface and a shiny surface facing the second surface, a first protective layer formed on the matte surface of the copper layer, and a second protective layer formed on the shiny surface of the copper layer. A coefficient of thermal expansion of the electrolyte copper foil measured using thermomechanical analyzer while heating the electrolytic copper foil from 30 to 190° C. at 5° C./min ranges from 16 to 22 μm/(m·° C.), tensile strength of the electrolytic copper foil measured after heat treatment at 190° C., ranges from 21 to 36 kgf/mm 2 , and weight deviation of the electrolytic copper foil is 5% or less.

First claim

What is claimed is:

1 . An electrolytic copper foil, which includes a first surface and a second surface opposite the first surface, the electrolytic copper foil comprising:
a copper layer including a matte surface facing the first surface and a shiny surface facing the second surface; a first protective layer on the matte surface of the copper layer, and a second protective layer on the shiny surface of the copper layer, wherein: a coefficient of thermal expansion of the electrolytic foil, which is measured using a thermomechanical analyzer (TMA) while heating the electrolytic copper foil from 30° C. to 190° C. at a speed of 5° C./min, ranges from 16 to 22 pun/(m·° C.), a tensile strength of the electrolytic copper foil, which is measured after a heat treatment at a temperature of 190° C. for 1 hour, ranges from 21 to 36 kgf/mm 2 , and a weight deviation of the electrolytic copper foil is 5% or less.

2 . The electrolytic copper foil of claim 1 , having an elongation of 3% or more at room temperature.

3 . The electrolytic copper foil of claim 1 , wherein a peak count (Pc) of each of the first and second surfaces of the electrolytic copper foil ranges from 3 to 92.

4 . The electrolytic copper foil of claim 1 , wherein each of the first and second protective layers includes at least one of chromium (Cr), a silane compound, and a nitrogen compound.

5 . The electrolytic copper foil of claim 1 , having a thickness of 4 to 30 μm.

6 . The electrolytic copper foil of claim 1 , wherein each of the first and second surfaces has a surface roughness (R z ) of 3.5 μm or less.

7 . The electrolytic copper foil of claim 1 , having a coefficient of thermal expansion of 17.3 to 22 μm/(m·° C.).

8 . A secondary battery electrode comprising:
an electrolytic copper foil including a first surface and a second surface opposite the first surface; and a first active material layer on the first surface of the electrolytic copper foil, wherein: the electrolytic copper foil comprises: a copper layer including a matte surface facing the first surface and a shiny surface facing the second surface; a first protective layer on the matte surface of the copper layer, and a second protective layer on the shiny surface of the copper layer, a coefficient of thermal expansion of the electrolytic foil, which is measured using a TMA while heating the electrolytic copper foil from 30° C. to 190° C. at a speed of 5° C./min, ranges from 16 to 22 μm/(m·° C.), a tensile strength of the electrolytic copper foil, which is measured after a heat treatment at a temperature of 190° C. for 1 hour, ranges from 21 to 36 kgf/mm 2 , and a weight deviation of the electrolytic copper foil is 5% or less.

9 . The secondary battery electrode of claim 8 , wherein the first active material layer includes at least one active material selected from a group consisting of carbon, a metal (Me) such as Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni, or Fe, an alloy containing the metal (Me), an oxide of the metal (MeOx), and a composite of the metal (Me) and carbon.

10 . The secondary battery electrode of claim 8 , wherein the first active material layer comprises Si.

11 . The secondary battery electrode of claim 8 , further comprising a second active material layer on the second protective layer.

12 . A secondary battery comprising:
a cathode; an anode including a secondary battery electrode; an electrolyte configured to provide an environment in which lithium ions may move between the cathode and the anode; and a separator configured to electrically insulate the cathode from the anode, wherein the secondary battery electrode comprises: an electrolytic copper foil including a first surface and a second surface opposite the first surface; and a first active material layer on the first surface of the electrolytic copper foil, wherein the electrolytic copper foil comprises: a copper layer including a matte surface facing the first surface and a shiny surface facing the second surface; a first protective layer on the matte surface of the copper layer, and a second protective layer on the shiny surface of the copper layer, a coefficient of thermal expansion of the electrolytic foil, which is measured using a TMA while heating the electrolytic copper foil from 30° C. to 190° C. at a speed of 5° C./min, ranges from 16 to 22 μm/(m·° C.), a tensile strength of the electrolytic copper foil, which is measured after a heat treatment at a temperature of 190° C. for 1 hour, ranges from 21 to 36 kgf/mm 2 , and a weight deviation of the electrolytic copper foil is 5% or less.

13 . A method of manufacturing a secondary battery electrolytic copper foil, the method comprising:
preparing an electrolytic solution containing 70 to 90 g/L of copper ions and 80 to 130 g/L of sulfuric acid; forming a copper layer by performing electroplating which applies electricity between a positive electrode plate and a rotating negative electrode drum which are disposed to in the electrolytic solution be spaced apart from each other; and forming a protective layer on the copper layer, wherein, while the electroplating is performed, an interval between the positive electrode plate and the rotating negative electrode drum is maintained to be in a range of 5 to 15 mm, a difference between a maximum interval and a minimum interval of the positive electrode plate and the rotating negative electrode drum in a width direction of the copper layer is maintained to be less than 0.2 mm, total organic carbon (TOC) in the electrolytic solution is maintained at 50 ppm or less, and a concentration of silver (Ag) in the electrolytic solution is maintained at 25 ppm or less.

14 . The method of claim 13 , wherein the electroplating is performed by applying a current density of 30 to 80 A/dm 2 between the positive electrode plate and the rotating negative electrode drum.

15 . The method of claim 13 , wherein the preparing of the electrolytic solution comprises:
performing a heat treatment on a copper wire; pickling the heat-treated copper wire; and introducing the pickled copper wire into sulfuric acid.

16 . The method of claim 15 , wherein:
the copper wire is heat-treated at a temperature of 600 to 900° C. for 2 to 6 hours, and the heat-treated copper wire is pickled by being immersed in an acidic solution containing 8 to 10 wt % of sulfuric acid and 1 to 2 wt % of hydrogen peroxide and then being washed with water.

17 . The method of claim 13 , wherein, while the electroplating is performed, continuous filtration for removing solid impurities from the electrolytic solution is performed at a flow rate of 31 to 45 m 3 /hr.

18 . The method of claim 13 , wherein the electrolytic solution further comprises chloride ions capable of precipitating silver (Ag) in the form of AgCl to prevent the concentration of silver (Ag) from exceeding 25 ppm by silver (Ag) being introduced into the electrolytic solution while the electroplating is performed.

19 . The method of claim 13 , wherein the electrolytic solution further comprises an organic additive selected from a group consisting of hydroxyethyl cellulose (HEC), organic sulfides, organic nitrides, and thiourea-based compounds.

20 . The method of claim 13 , wherein the forming of the protective layer comprises immersing the copper layer in an antirust solution containing 0.5 to 1.5 g/L of chromium (Cr).

Assignees

• Ls Mtron Ltd

Inventors

• Kim Seung Min

Classifications

• C25D3/38

  of copper · CPC title

• H01M4/661 Primary

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

• H01M4/1395

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

• C25D1/04

  Wires; Strips; Foils · CPC title

• H01M10/052

  Li-accumulators · CPC title