COPPER FOIL, ELECTRODE FOR SECONDARY BATTERY, SECONDARY BATTERY, AND PRINTED CIRCUIT BOARD

摘要

PROBLEM TO BE SOLVED: To provide a copper foil for an negative electrode of a lithium ion secondary battery, which allows the production of a lithium ion secondary battery causing no decrease in capacity even if charge and discharge cycles are repeated, having a long life and prevented from being deformed in a negative electrode collector.SOLUTION: The analysis of the copper foil in the depth direction by SIMS (Secondary Ion Mass Spectroscopy) in the foil thickness direction shows that the copper foil includes each of chlorine and carbon in a concentration of 10to 5×10atoms/cmand sulfur or/and nitrogen in a concentration of 10to 5×10atoms/cm. By using the copper foil in a negative electrode collector of a Li ion battery, a lithium ion secondary battery can be provided in which the generation of deformation such as wrinkle in the collector caused by charge and discharge is suppressed, which causes no decrease in capacity even if charge and discharge cycles are repeated and which has long life and can be made compact.