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, and more particularly, to an electrolytic copper foil for a secondary battery, which has little change in a physical property of a copper foil before and after vacuum drying in a process of producing an electrolytic copper foil, thereby exhibiting excellent cycle life in a battery test at a high-density negative electrode, and preventing cracking. The electrolytic copper foil for a secondary battery is produced from a plating solution containing Total Organic Carbon (TOC), zinc, and iron by using a drum, in which a ratio of the TOC to the zinc and the iron contained in the electrolytic copper foil follows Formula 1 below: TOC/(zinc+iron)=1.3 to 1.5. Formula 1:
1. A method of producing an electrolytic copper foil for a secondary battery, the method comprising:
preparing a plating solution containing copper, Total Organic Carbon (TOC), zinc, and iron;
applying a current density of 30 Ampere per Square Deci-metre (ASD) to 150 ASD under a temperature condition of 30° C. to 70° C. and performing electroplating by using a drum; and
vacuum drying an electrolytic copper foil formed by the electroplating,
wherein a ratio of the TOC to the zinc and the iron contained in the electrolytic copper foil follows Formula 1 below:
TOC/(zinc+iron)=1.3 to 1.5. Formula 1:
2. The method of claim 1 , wherein a ratio of tensile strength to elongation percentages before and after vacuum drying follows Formula 2 below:
Formula 2 : (tensile strength after vacuum drying/tensile strength before vacuum drying)/(elongation percentage after vacuum drying/elongation percentage before vacuum drying)×tensile strength after vacuum drying=28 to 50 kgf/mm 2 , and
wherein the vacuum drying is performed at a temperature range of 110° C. to 150° C. for 6 hours to 10 hours.
3. The method of claim 1 , wherein a concentration of the TOC contained in the plating solution is equal to or larger than 100 ppm.
4. The method of claim 1 , wherein tensile strength of the electrolytic copper foil at a room temperature is 40 kgf/mm 2 to 51 kgf/mm 2 .
5. The method of claim 1 , wherein a thickness of the electrolytic copper foil is 4 μm to 12 μm.
6. The method of claim 1 , wherein an elongation percentage of the electrolytic copper foil is 2% to 18%.