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, wherein at least one of the bottom wall or the plurality of side walls includes a liquid crystal aromatic polymer, at least a portion of the liquid crystal aromatic polymer includes an aliphatic organic group at one terminal end, and the battery case has a WVTR at a thickness of about 1 mm at about 38° C. and a relative humidity of about 100% of less than about 0.07 g/m2/day and an impact strength of greater than or equal to about 20 KJ/m2, a battery including the battery case, and a battery module.