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

A battery packaging material including a laminate that is provided with a barrier layer, a heat-fusible resin layer positioned on one surface side of the barrier layer, and a polyester film positioned on the other surface side of the barrier layer. When the infrared absorption spectrum on the surface of the polyester film in 18 directions at intervals of 10° from 0° to 180° is obtained using the total reflection method of Fourier transform infrared spectroscopy, the ratio (surface orientation degree, Y/Y) of the maximum value Yand the minimum value Yof the ratio (Y/Y) of the absorption peak intensity Yin 1340 cmand the absorption peak intensity Yin 1410 cmin the infrared absorption spectrum is in the range of 1.4-2.7.