Disclosed are a battery case including a container configured to accommodate an electrode assembly, wherein the container includes a bottom wall and a plurality of side walls, the bottom wall and the plurality of side walls are integrated to have an open side opposed to the bottom wall and to provide a space for accommodating the electrode assembly, the container includes a composite including a base polymer and an inorganic moisture absorbent, expanded graphite, and red phosphorus, each of which are dispersed in the base polymer, and the battery case has a water vapor transmittance rate at about 38° C. under relative humidity of about 100% according to ISO 15106 or ASTM F1249 of less than about 0.07 g/m2/day and flame retardancy of V-0 measured according to UL (Underwriter's Laboratories)-94, and a battery or battery module including an electrode assembly accommodated in the container of the battery case.