NOVELTY - The unit (1) has a terminal element (330) extending into a case (20) through a terminal insertion portion (35). A fixing element (340) is arranged in the terminal insertion portion for fixing the terminal element to a cap plate (310). The fixing element is formed by an insert injection molding process, in which plastic resin is injected in the terminal insertion portion in a state, where the terminal element is inserted in the terminal insertion portion in the state. The fixing element comprises a recessed portion that is recessed from an upper surface of the fixing element.    USE - Battery unit for a battery module (claimed) i.e. secondary battery. Uses include but are not limited to a mobile device i.e. mobile phone, an electric vehicle e.g. electric bicycle, a hybrid car and an uninterruptable power supply.    ADVANTAGE - The unit ensures that a large contact area between the negative current collector portion and the negative material uncoated portion can be obtained, so that contact resistance can be small or reduced. The uniform thickness of the battery unit can prevent deformation of the negative fixing element during a process, in which the negative terminal fixing element is cooled after injection molding. The recessed portion can prevent the thicknesses of the lower walls from being overly increased when the side walls extend upward so as to prevent deformation after the injection of the positive terminal fixing element and the negative terminal fixing element. The positive terminal element and the negative terminal element are formed without a coupling process such as welding, so that manufacturing cost can be reduced and an electrical characteristic of a current path from each of the positive current collector portion and the negative current collector portion to the respective positive terminal portion and the negative terminal portion can be uniform. The unit ensures that the extended portions extend over the edges of the positive terminal insertion portion and the negative terminal insertion portion, so that intrusion of moisture into the case through a gap between the positive terminal fixing element and the positive terminal insertion portion or between the negative terminal fixing element and the negative terminal insertion portion can be reduced, thus reducing possibility of corrosion of the cap plate, the electrode assembly, the positive and negative current collector portions and the case. The positive terminal portion and the negative terminal portion are supported by the fixing portions, so that the positive terminal portion and the negative terminal portion can be prevented from being bent downwardly in the processing of welding the bus bar, thus improving coupling quality between the bus bar and the positive and negative terminal portions.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a battery module.    DESCRIPTION OF DRAWING(S) - The drawing shows an exploded perspective view of a battery unit.    Battery unit (1)    Case (20)    Terminal insertion portion (35)    Cap plate (310)    Terminal element (330)    Fixing element (340)