Electrolytic copper foil having high-temperature dimensional stability and texture stability, and manufacturing method therefor
The present invention relates to: an electrolytic copper foil having high dimensional stability and texture stability in a high temperature environment of a process for manufacturing an Li secondary battery; and a manufacturing method therefor. The electrolytic copper foil of the present invention has a thermal expansion coefficient of 17.1-22 μm/(m·° C.) in a temperature region of 30-190° C., has a variation of full width at half maximum of the (220) plane of 0.81-1.19 according to heat treatment for 30 minutes at 190° C., and has a weight deviation of 5% or less in the transverse direction.
1. An electrolytic copper foil having a first surface and a second surface opposite to the first surface, wherein
a coefficient of thermal expansion of the electrolytic copper foil, measured while a temperature is increased from 30 to 190° C. at a speed of 5° C./min, is 17.1 to 22 μm/(m° C.),
an alteration rate of a full width at half maximum of (220) plane of the electrolytic copper foil is 0.81 to 1.19, the alteration rate being obtained by sequentially performing (i) measurement of a first full width at half maximum of (220) plane of a sample of the electrolytic copper foil, (ii) heat treatment of the sample at 190° C. for 30 minutes, (iii) measurement of a second full width at half maximum of (220) plane of the heat-treated sample, and (iv) calculation of the alteration rate using Equation 1 below,
Alteration rate of full width at half maximum of (220) plane=full width at half maximum of (220) plane)/full width at half maximum of (220) plane), (Equation 1)
a lateral weight deviation of the electrolytic copper foil is 5% or less,
a difference between Rz of the first surface and Rz of the second surface of the electrolytic copper foil is 0.65 μm or less, and
a difference between Ra of the first surface and Ra of the second surface of the electrolytic copper foil is 0.18 μm or less.
2. The electrolytic copper foil according to claim 1 , wherein the electrolytic copper foil comprises a first passivation layer, which forms the first surface, and a second passivation layer, which forms the second surface, each of the first passivation layer and the second passivation layer being a rust-proof layer.
3. The electrolytic copper foil according to claim 1 , wherein the electrolytic copper foil has a thickness of 4 to 30 μm.
4. The electrolytic copper foil according to claim 1 , wherein Rz of the first surface and Rz of the second surface are 2.5 μm or less.
5. A method of manufacturing the electrolytic copper foil according to claim 1 by applying electric current between a positive electrode plate and a rotary negative electrode drum, disposed in an electrolytic solution in an electrolytic bath so as to be spaced apart from each other, in order to electroplate a copper film on the rotary negative electrode drum, wherein
the electrolytic solution comprises 70 to 100 g/L of copper ions, 80 to 130 g/L of sulfuric acid, 55 ppm or less of Pb′ ions, and 2 to 17 ppm of 4-mercaptopyridine,
a content of total organic carbon (TOC) in the electrolytic solution is 450 ppm or less,
a distance between the positive electrode plate and the rotary negative electrode drum is 5 to 15 mm, and
a difference between a maximum distance and a minimum distance between the positive electrode plate and the rotary negative electrode drum is 0.2 mm or less.