COPPER ALLOY FOIL, NEGATIVE ELECTRODE FOR LITHIUM ION SECONDARY BATTERY, LITHIUM ION SECONDARY BATTERY, METHOD FOR MANUFACTURING COPPER ALLOY FOIL AND METHOD FOR MANUFACTURING NEGATIVE ELECTRODE FOR LITHIUM ION SECONDARY BATTERY

摘要

(Subject) The present invention stably maintains the sufficient mechanical strength even after the heat treatment in the process of manufacturing a negative electrode for lithium ion secondary battery. (Solution) The present invention contains at least 0.20 to 0.40 weight% of Cr, 0.01 to 0.10 weight% of Ag, and 0.10 to 0.20 weight% of Sn, and remainder copper (Cu) and satisfies that Z is 0.4 or less, wherein the Z is the solid index of the below formula (1). Formula (1): Z = (RM-RS)/(RP-RS) The RM is the actual measurement value (%IACS) of R which is the conductivity rate of a copper alloy foil (10). The RS is the calculated value (%IACS) of R which is the conductivity rate of the copper alloy foil (10) in a case where the entire chrome (Cr) is solidified. The RP is the calculated value (%IACS) of R which is the conductivity rate of the copper alloy foil (10) in a case where the entire chrome (Cr) is extracted. [Reference numerals] (AA) Start a process of manufacturing a copper alloy foil;(BB) Repeated process;(CC) (Repeat predetermined times)Repeated process;(DD) End the process of manufacturing a copper alloy foil;(S10) Copper alloy foil preparing process;(S20) Hot rolling process;(S31) Cold rolling process;(S32) Solution heat treatment process;(S40) Final cold rolling process