Electrolytic copper foil and method for manufacturing the same and surface-treated copper foil using the electrolytic copper foil

The present invention is to provide an electrolytic copper foil with excellent physical characteristics after high temperature heating compared to that of the prior art, and the also electrolytic copper foil is suit for use in negative electrode collector of lithium ion secondary cell. To this end, electrolytic cooper foil with following features is used: normal tensile strength over 600 MPa, tensile strength over 470 MPa after heating at temperature of 350 DEG C for 1h. The invention also provides a method for manufacturing the electrolytic cooper foil using polyethylenimine having a concentration of 20 mg/L to 100 mg/L (molecular weight is about 10000 to 70000) and a sulfuric acid copper electrolyte having a chloride concentration of 0.5 mg/L to 2.5 mg/L.