| 摘要 |
PROBLEM TO BE SOLVED: To provide an electrolytic copper foil having an excellent charge-discharge cycle life, and suitable as the negative electrode collector material of a secondary battery including a lithium ion secondary battery.SOLUTION: Disclosed is an electrolytic copper foil made of copper or a copper alloy. In the electrolytic copper foil, before and after heating for 1 hour at any temperature of 120°C, 130°C, 150°C and 200°C, regarding a diffraction intensity ratio between the (200) face and (111) face in X-ray diffraction with a CuKα ray in the copper or copper alloy (200)/(111), the maximum value of the absolute values of change rates obtained by the following formula is 30% or lower: the maximum value of the change rates=((the maximum value of the diffraction intensity ratio after the heating)-(the diffraction intensity ratio before the heating))/(the diffraction intensity ratio before the heating)×100. |
