Electrolytic copper foil for secondary battery, having enhanced physical properties at low temperature, and method for producing same
The present invention relates to an electrolytic copper foil for a secondary battery, having excellent physical properties at a low temperature, and a method for producing the electrolytic copper foil. The electrolytic copper foil for a secondary battery shows little change in the physical properties, such as tensile strength and elongation, of a copper foil even at a low temperature and thereby exhibits excellent cycle properties at the low temperature. The electrolytic copper foil for a secondary battery is produced from a plating solution, containing total organic carbon (TOC), cobalt, iron and zinc, by using a drum and coated with a negative electrode active material, wherein the ratio between the TOC, cobalt, iron and zinc contained in the electrolytic copper foil follows the following formula 1: TOC/(cobalt+iron+zinc)=1.0-1.2. [Formula 1]
1. An electrolytic copper foil for a secondary battery, comprising:
a layer that contains total organic carbon (TOC) and metallic additives that contain cobalt, iron and zinc, wherein the layer is capable of being coated with a negative electrode active material, and
wherein a ratio of the TOC to the cobalt, iron and zinc contained in the layer satisfies a following Equation 1:
TOC/(cobalt+iron+zinc)=1.0 to 1.2. [Equation 1]
2. The electrolytic copper foil of claim 1 , wherein each of a tensile strength and an elongation at −30° C. of the electrolytic copper foil is maintained to be greater than or equal to 80% of each of a tensile strength and an elongation at room temperature of the electrolytic copper foil.
3. The electrolytic copper foil of claim 1 , wherein the layer of the electrolytic copper foil has a first face and a second face that is opposite to the first face, and
wherein a cross-sectional average of a grain size in said first face is smaller than or equal to 80% of a cross-sectional average of a grain size of the second face.
4. The electrolytic copper foil of claim 1 , wherein a tensile strength of the electrolytic copper foil is in a range of 40 kgf/mm 2 to 51 kgf/mm 2 .
5. The electrolytic copper foil of claim 1 , wherein an elongation of the electrolytic copper foil is in a range of 2% to 12%.
6. The electrolytic copper foil of claim 1 , wherein a thickness of the electrolytic copper foil is in a range of 4 μm to 10 μm.