Patent ID: 8808893

Claim:
A middle or large-sized battery module having secondary batteries or unit modules, each of which has two or more secondary batteries mounted therein, stacked in a state in which the secondary batteries or the unit modules are erected vertically, the battery module comprising: a base plate on which the secondary batteries or the unit modules are stacked in a vertically erected state; a pair of end plates disposed in tight contact with outer sides of the outermost unit modules or the outermost unit modules in a state in which the bottom of each of the end plates is fixed to the base plate; and supporting bars connected between opposite sides of upper parts or side parts of the end plates so as to interconnect and support the end plates, wherein the base plate is provided at opposite sides thereof with a pair of upward protrusions extending in a longitudinal direction of the base plate to prevent the base plate from being deformed due to vertical vibration and to disperse pressure, and opposite sides of the bottom of each of the unit modules are disposed at the top of the upward protrusions, wherein each of the upper protrusions comprises an upper side part, with which the bottom of each of the secondary batteries or the unit modules comes into contact, and an inner side part and an outer side part vertically connected between the upper side part and a main body of the base plate, and wherein the upper side part has a width (x) determined relative to an area moment of inertia in a direction perpendicular to a direction in which the secondary batteries or the unit modules are stacked, wherein the width (x) of the upper side part is within a range satisfying Equation (1): 0.5 w max ≦x≦ 1.5 w max (1) where, w max indicates a width of the upper side part where the area moment of inertia is maximum.