Copper foil for current collector of lithium secondary battery with improved wrinkle characteristics
View Patent ↗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 (R z -JIS) of 2 μm or less, weight deviation of 3% or less, tensile strength of 30 to 40 kgf/mm 2 , elongation of 3 to 20%, and thickness of 1 to 35 μm.
1. A 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
)
wherein I(hkl) represents a measured diffraction intensity with respect to a (hkl) surface, and I 0 (hkl) represents a standard diffraction intensity of ASTM (American Society of Testing Materials) standard powder-shaped diffraction data,
wherein the copper foil has a weight deviation of 3% or less, and
wherein the copper foil has a tensile strength of 30 to 40 kgf/mm 2 ,
so as to prevent the generation of wrinkles at a surface of the copper foil.
2. The copper foil for a current collector of a lithium secondary battery according to claim 1 , wherein the copper foil has a surface roughness (R z -JIS) of 2 μm or less.
3. The copper foil for a current collector of a lithium secondary battery according to claim 1 , wherein the copper foil has an elongation of 3 to 20%.
4. The copper foil for a current collector of a lithium secondary battery according to claim 1 , wherein the copper foil has a thickness of 1 to 35 μm.