BATTERY PACKAGING MATERIAL, PRODUCTION METHOD THEREFOR, BATTERY, AND POLYESTER FILM

The present invention related to a battery packaging material comprising a laminate that includes at least a barrier layer, a heat-sealable resin layer situated on one surface side of the barrier layer, and a polyester film situated on the other surface side of the barrier layer, the thickness of the barrier layer being 100 µm or less, the polyester film having a ratio in a range of 1.4 or more and 2.7 or less between a maximum value Y and a minimum value Y (degree of surface orientation: Y/Y), with the maximum value Y and the minimum value Y respectively representing a maximum value and a minimum value of a ratio between an absorption peak intensity Y at 1340 cm and an absorption peak intensity Y at 1410 cm (Y/Y) in infrared absorption spectra acquired for 18 directions at intervals of 10° from 0° to 180° on a surface of the polyester film according to attenuated total reflection of Fourier transform infrared spectroscopy, determined as disclosed in the description.