A battery includes a cell element that is disposed in a housing, and the housing is sealed with a top cover made primarily of plastic. The top cover may include a layer of metallic foil, which may make the top cover more impermeable to moisture. The top cover may also include a vent, which may or may not utilize the metallic foil to determine the primary opening force of the vent. The top cover may also have one or more stiffening ribs that extend downwardly from a bottom portion of the top cover to contact the cell element, so as to limit movement of the cell element within the housing. In addition, the top cover may have one or more conductive terminals that are at least partially overmolded by the plastic of the top cover.