Copper foil for current collector of lithium secondary battery with improved wrinkle characteristics
A copper foil for a current collector of a lithium secondary battery has a crystalline structure, in which a ratio of the sum of texture coefficients of a (111) surface and a (200) surface to the total sum of texture coefficients of the (111), (200) and (220) surfaces is 60 to 85%, a ratio of the texture coefficient of the (111) surface to the total sum of texture coefficients of the (111), (200) and (220) is 18 to 38%, a ratio of the texture coefficient of the (200) surface thereto is 28 to 62%, and a ratio of the texture coefficient of the (220) surface thereto is 15 to 40%. The copper foil has surface roughness (Rz-JIS) of 2 mum or less, weight deviation of 3% or less, tensile strength of 30 to 40 kgf/mm2, elongation of 3 to 20%, and thickness of 1 to 35 mum.
1. A wrinkle-free copper foil for a current collector of a lithium secondary battery,
wherein, in a crystalline structure, a ratio of a sum of texture coefficients of a (111) surface and a (200) surface to a total sum of texture coefficients of the (111) surface, the (200) surface and a (220) surface is 60 to 85%, a ratio of a texture coefficient of the (111) surface to the total sum of texture coefficients of the (111) surface, the (200) surface and the (220) surface is 18 to 38%, a ratio of the texture coefficient of the (200) surface to the total sum of texture coefficients of the (111) surface, the (200) surface and the (220) surface is 28 to 62%, and a ratio of the texture coefficient of the (220) surface to the total sum of texture coefficients of the (111) surface, the (200) surface and the (220) surface is 15 to 40%,
wherein the texture coefficient satisfies the following equation:
TC
(
hkl
)
=
I
(
hkl
)
I
0
(
hkl
)
1
n
Σ
I
(
hkl
)
I
0
(
hkl
)
where TC(hkl) represents a texture coefficient of a (hkl) surface, I(hkl) represents a measured diffraction intensity with respect to the (hkl) surface, and I 0 (hkl) represents a standard diffraction intensity of the (hkl) surface obtainable from ASTM (American Society of Testing Materials) standard powder-shaped diffraction data,
wherein the wrinkle-free copper foil has a surface roughness (R z -JIS) of 2 μm or less,
wherein the wrinkle-free copper foil has a weight deviation of 3% or less,
wherein the wrinkle-free copper foil has a tensile strength of 30 to 40 kgf/mm 2 ,
wherein the wrinkle-free copper foil has an elongation of 3 to 20%,
wherein the wrinkle-free copper foil has a thickness of 1 to 35 μm, and
wherein the wrinkle-free copper foil is treated to prevent corrosion.
2. The wrinkle-free copper foil according to claim 1 , wherein the wrinkle-free copper foil is surface-chromated to prevent corrosion.