SURFACE TREATMENT METHOD FOR COPPER FOIL, SURFACE-TREATED COPPER FOIL, AND COPPER FOIL FOR NEGATIVE ELECTRODE COLLECTOR OF LITHIUM ION SECONDARY BATTERY

摘要

Disclosed is a copper foil for a negative electrode collector capable of simultaneously achieving high capacity and long life charge/discharge cycles in a secondary battery, wherein the front and back surfaces are of a uniform shape and, for example, the properties of a silicon active material of a lithium ion secondary battery are sufficiently realized; and a negative electrode using the copper foil. In one embodiment, a first roughened layer of metallic copper is formed by pulse cathode electrolysis roughening treatment on the surface of an untreated rolled copper foil base material of oxygen-free copper in a first roughening treatment tank (1) filled with a copper-sulphuric acid electrolyte (12), and a second copper-plate layer is formed on the surface of the first roughened layer by smooth copper plating treatment in a second copper plating treatment tank (2) filled with a copper-sulphuric acid electrolyte (22).