SECONDARY BATTERY AND BATTERY MODULE INCLUDING THE SAME

The present invention relates to a battery module in which terminals of two secondary batteries are directly coupled by welding, and which thus does not require a separate component for electrical connection and can reduce electrical contact resistance. Disclosed as an embodiment of the present invention is a battery module comprising a first secondary battery and a second secondary battery having the same structure as the first secondary battery, the first secondary battery comprising: an electrode assembly having a first electrode tab and a second electrode tab respectively exposed on both sides thereof; a case accommodating the electrode assembly and having two open sides; a first cap plate sealing one open side of the case; a first terminal electrically connected to the first electrode tab and exposed to the outside of the first cap plate; a second cap plate sealing the other open side of the case; and a second terminal electrically connected to the second electrode tab and exposed to the outside of the second cap plate, wherein a first protrusion portion protruding outwardly from the first terminal of the first secondary battery is coupled to and connected in series, by welding, with a second recessed portion recessed into the second terminal of the second secondary battery.