Electrolytic copper foil for secondary battery and method for producing the same
The present invention relates to an electrolytic copper foil for a secondary battery, and a method of producing the same. The electrolytic copper foil for a secondary battery exhibits a little change in a physical property caused by a difference in a crosshead speed when tensile strength and an elongation percentage of the electrolytic copper foil are measured, thereby achieving excellent charging and discharging characteristics of a battery and preventing exfoliation of an active material. The electrolytic copper foil for a secondary battery is produced from a plating solution containing Total Organic Carbon (TOC), cobalt, and iron by using a drum, in which a ratio of the TOC to the cobalt and the iron contained in the electrolytic copper foil follows Formula 1 below. TOC/(cobalt+iron)=1.3 to 1.5 [Formula 1]
1. An electrolytic copper foil for a secondary battery, comprising:
a layer that contains copper, Total Organic Carbon (TOC) and metallic additives that contain cobalt and iron,
wherein the layer is capable of being coated with a negative electrode active material, and
wherein a ratio of the TOC to the cobalt and the iron contained in the layer follows Formula 1:
TOC/(cobalt+iron)=1.3 to 1.5. [Formula 1]
2. The electrolytic copper foil of claim 1 , wherein a difference in a crosshead speed for measuring tensile strength at room temperature and 110° C. (six hours) follows Formula 2, and
a difference in a crosshead speed for measuring an elongation percentage at room temperature and 110° C. (six hours) follows Formula 3:
(Tensile strength at 1 mm/min crosshead speed)/(Tensile strength at 50 mm/min crosshead speed)≥0.9, and [Formula 2]
(Elongation percentage at 1 mm/min crosshead speed)/(Elongation percentage at 50 mm/min crosshead speed)≥0.8. [Formula 3]
3. The electrolytic copper foil of claim 1 , wherein tensile strength of the electrolytic copper foil at room temperature is 40 kgf/mm 2 to 51 kgf/mm 2 .
4. The electrolytic copper foil of claim 1 , wherein a thickness of the electrolytic copper foil is 4 μm to 12 μm.
5. The electrolytic copper foil of claim 1 , wherein an elongation percentage of the electrolytic copper foil is 2% to 18%.