Fluororesin film for battery exterior body, battery exterior body and secondary battery

Abstract

The present disclosure provides a fluororesin film for a battery exterior body, which is excellent in adhesion to a metal layer. The present disclosure further provides a battery exterior body which is excellent in electrolytic solution permeation resistance. The fluororesin film for the battery exterior body includes a composition including a fluororesin. An oxygen element ratio of a surface of the film after heating the film at 180° C. during 3 minutes is 1.35 atomic % or more. The oxygen element ratio is obtained by measuring a surface state of one or both surfaces of the film by a scanning X-ray photoelectron spectrometer (XPS/ESCA). An absolute value of a rate of dimensional change of the film in MD and TD, measured before and after heating the film at 180° C. during 10 minutes and then cooling down the film to 25° C., is 2% or less.

Dependencies are inferred from the claim text.