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 other surface side of barrier layer. This battery packaging material is configured from at least a laminate provided with a barrier layer, heat-fusible resin layer positioned on one surface side of barrier layer, and a polyester film positioned on other surface side of barrier layer. When infrared absorption spectrum on the polyester film's surface in 18 directions at intervals of 10° from 0°-180° is obtained using total reflection method of Fourier transform infrared spectroscopy, the ratio of the maximum value and the minimum value of 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.