ELECTROLYTIC COPPER FOIL PROCESSES FOR PRODUCING SAID ELECTROLYTIC COPPER FOIL AND SURFACE-TREATED COPPER FOIL OBTAINED USING SAID ELECTROLYTIC COPPER FOIL

摘要

An object of the present invention is to provide an electrolytic copper foil which is excellent in physical properties after heating at a high temperature beyond the conventional electrolytic copper foil and which is also suitable for use in a negative electrode current collector of a lithium ion secondary battery. In order to achieve this object, an electrolytic copper foil or the like is used which is characterized by having a tensile strength of 600 MPa or more in steady state tensile strength and a tensile strength of 470 MPa or more after heating at 350 占 폚 for 1 hour. As the method for producing the electrolytic copper foil, a sulfuric acidic copper electrolytic solution containing polyethyleneimine having a concentration of 20 mg / L to 100 mg / L and a molecular weight of 10,000 to 70,000 and having a chlorine concentration of 0.5 mg / L to 2.5 mg / Is used.