POLYESTER FILM FOR BATTERY OUTER PACKAGE, LAMINATE FOR BATTERY OUTER PACKAGE INCLUDING THE SAME, AND CONSTITUTIONAL BODY

摘要

PROBLEM TO BE SOLVED: To provide a polyester film for a battery outer package, capable of being used for a battery outer package, specifically used suitable for a lithium ion secondary battery having an electrolyte (solid, liquid).SOLUTION: In a polyester film for a battery outer package, a thermal shrinkage stress Yin an MD direction and a thermal shrinkage stress Yin a TD direction at 200°C satisfy the following expressions, and at least one surface of the polyester film is subjected to corona discharge treatment or surface coating treatment. 50≤Y≤120 g/10 mm and 5≤Y≤80 g/10 mm.