NEGATIVE ELECTRODE COLLECTOR FOR SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a negative electrode collector for obtaining a secondary battery hardly allowing degradation of battery performance and having a long service life. SOLUTION: This negative electrode collector is made of copper rolled foil of 30 μm thickness containing 99.9 wt.% or above of copper. A breaking elongation of the copper rolled foil in the rolling direction is 2-15%. The rolling direction of the copper rolled foil signifies the longitudinal direction (the direction perpendicular to the width direction) of the copper rolled foil. The copper rolled foil can be manufactured by repeatedly applying cold rolling and process annealing after applying a hot-rolling to a copper ingot to obtain a rolled copper foil, then heat-treating the obtained rolled copper foil at a temperature of 150 deg.C or higher. This copper rolled foil is especially suitable for the negative electrode collector of a lithium type secondary battery such as a lithium-ion battery or a polymer battery.