| 摘要 |
Provided are a surface-treated copper foil that has an improved suitability for welding resistance so as to achieve an enhanced productivity, a negative electrode for a lithium ion secondary battery, and a lithium ion secondary battery. The surface-treated copper foil is characterized in that: the sum (atomic %) of the carbon element content and nitrogen element content, said element contents being measured in the depth direction of the copper foil by X-ray photoelectron spectroscopy (XPS), attains the maximum value on the outermost surface; at the depth at which the sum (atomic %) of the carbon element content and nitrogen element content is halved compared to the maximum value thereof on the outermost surface, the decreasing rate of the sum (atomic %) of the carbon element content and nitrogen element content in the depth direction of the copper foil is 50%/nm or greater; and the surface resistivity that is defined in JIS-K7194:1994 is 2.5-40 mOmega. |
