Precipitation hardening type copper alloy foil, negative electrode for lithium ion secondary battery using the same, and method for producing precipitation hardening type copper alloy foil

摘要

PROBLEM TO BE SOLVED: To provide a precipitation hardening copper alloy foil improved in both strength and ductibility, a lithium ion secondary battery negative electrode using it, and a manufacturing method of the precipitation hardening copper alloy foil.SOLUTION: The precipitation hardening copper alloy foil is a Cu-Cr-Zr system copper alloy consisting of: 0.05-0.4 mass% Cr; 0.01-0.08 mass% Zr; 0.05-0.3 mass% Sn; and Cu and inevitable impurities as the remnants. The composition of a cross section perpendicular to the rolling direction of the alloy foil has a 50 m or less crystal grain size in a mother phase in a 600 nm×400 nm area. Out of optional 100 pieces of precipitated objects containing Cr or Zr existing in the area, the arithmetic mean value of the largest crystal grain size is 15 nm or less, and in ten optional 900 nmareas in the area, the number of 15 nm or less precipitated objects is five or more.