NOVELTY - The battery (100) has an electrode group with a positive electrode, a negative electrode, and a separator placed between the positive and negative electrodes. A case (14) houses the electrode group. A cap plate (17) is combined with the case. An electrode terminal (40) is electrically coupled to the electrode group, where the electrode terminal comprises a head portion placed outside the case. A support shaft portion of the terminal is protruded from the head portion and penetrates the cap plate. A fixing member is placed inside the case and combined to the support shaft portion.    USE - Rechargeable battery for use in a battery module (claimed) in a small electronic device e.g. mobile phone, notebook computer, and camcorder, and for use as a power source to drive a motor of a hybrid electric vehicle.    ADVANTAGE - The battery reduces contact resistance and maintains stable output electric current. The inner surface of the head portion is placed in contact with a cooling medium, thus easily releasing heat generated from the electrode terminal and reducing materials, and hence reducing cost of production unit. The head portion is elastically deformed so as to be easily and tightly attached to a flange portion and a bus bar, so that the bus bar is tightly attached to the electrode terminal, thus improving mechanical strength of an auxiliary connection member. The electrode terminal is made of a material with higher electrical conductivity and the auxiliary connection member is made of a material with better mechanical strength compared to the electrode terminal, so that electrical resistance is reduced and mechanical rigidity is improved.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a battery module comprising a bus bar electrically connecting two of rechargeable batteries.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of a rechargeable battery.    Case (14)    Cap plate (17)    Vent portion (19)    Electrode terminal (40)    Rechargeable battery (100)