Abstract: A battery module according to one embodiment of the present disclosure includes: a battery cell stack in which a plurality of battery cells are stacked, a first L-shaped frame accommodating the battery cell stack, and an upper part and one side surface of which are opened, and a second L-shaped frame accommodating the battery cell stack, and a lower part and one side surface of which are opened, wherein the first L-shaped frame and the second L-shaped frame are engaged with each other to surround four surfaces of the battery cell stack, a lower surface of the first L-shaped frame includes a first part and a second part, the first part is located at the edge with respect to a lengthwise direction of the battery cell, the second part is located in the interior of the first part, and a thickness of the first part is smaller than the thickness of the second part.

Abstract: A battery module includes a battery cell stack in which a plurality of battery cells are stacked and a module frame that accommodates the battery cell stack. The module frame includes a bottom part, two side surface parts facing each other, and an upper plate to cover the battery cell stack. The bottom part extends in a longitudinal direction between two terminal edges and includes a first part located at at least one of terminal the edges and a second part located inside the first part relative to the terminal edges, and wherein a thickness of the first part is thinner than that of the second part.

Abstract: Disclosed herein is a bus bar for electrically connecting electrode leads of unit modules or battery cells (unit cells) in a battery module through a coupling method employing laser welding. Each of the electrode leads and the bus bar has a plate-shaped structure and a protrusion projecting toward the electrode leads is formed on the bus bar at a portion thereof, which is to be welded to the electrode leads through laser irradiation, to allow the portion of the bus bar, which is to be welded to the electrode leads, to be brought into close contact with the electrode leads.

Abstract: Disclosed herein is a bus bar for electrically connecting electrode leads of unit modules or battery cells (unit cells) in a battery module through a coupling method employing laser welding. Each of the electrode leads and the bus bar has a plate-shaped structure and a protrusion projecting toward the electrode leads is formed on the bus bar at a portion thereof, which is to be welded to the electrode leads through laser irradiation, to allow the portion of the bus bar, which is to be welded to the electrode leads, to be brought into close contact with the electrode leads.